LINCS Annual Workshop with the Scientific Committee 2026
2026-07-02 09:00 - 2026-07-03 17:00 (Europe/Paris) | Amphi Rose Dieng, 19 place Marguerite Perey, Palaiseau, France
Please save the date!

As is tradition, we are pleasedto invite you to the 2026 edition of our Annual Workshop with theScientific Committee : a two-day event taking place on July Tuesday 2 andFriday 3 in Palaiseau, featuring scientific highlights, surveys,elevator pitches, and posters from our scientific community.

TBD
2026-05-28 14:00 - 15:00, 2026-05-07 14:00 - 15:00, 2026-04-16 14:00 - 15:00

LINCS PhD Student Day 2026
2026-05-21 09:00 - 18:00
Please save the date!

We are currently preparing thenext edition of LINCS Ph.D Student DAY: an event entirely dedicated to thePhD students and postdocs of the lab that includes sessions with elevatorpitches, poster presentations, and brainstorming, along with a friendlylunch and a team-building activity that may take place outdoors.

Theaim of this event is to offer PhD students and postdocs an opportunity topresent their work, discover their peers’ research, and receivevaluable feedback from senior members of LINCS. Additionally, it willserve as practice for those who will be presenting at the upcoming annualworkshop in front of the scientific committee, scheduled for July 2 &3.

The program is still a work in progress. We’d love to hear anysuggestions you might have for the team-building activity.

Theproposed lunch and recreational activity will be covered by LINCS.

"How to Present” Workshop
2026-04-09 14:00 - 15:00 | Amphi 7, 19 Place Marguerite Perey, Palaiseau, France
Especially conceived for Ph.D students, interns and postocs,the “How to Present” workshop, will go over some ideas on how toconceive your presentation based on the timing (from 3 to 40 minutes),your audience (scientific vs. industrial, specialized vs. general),your content (is it a big chunk of maths? system architecture? a survey?etc.), and more.

We warmly encourage to seize this opportunity byattending on April 9, presenting both a poster and an elevator pitch, andjoining the afternoon activity on May 21.

Real-Time Cloud: Between Vision and Reality
2026-04-02 14:00 - 15:00 | Amphi 3, 19 Place Marguerite Perey, Palaiseau, France
Real-time cloud envisions the migration of time-criticalapplications to shared cloud infrastructures in order to leverageelasticity, scalability, and operational flexibility. However, thisvision conflicts with core cloud design principles: deep resource sharing,multi-tenancy, and increasingly complex virtualization stacks.

In thistalk, we analyze the main threats to predictability and security inmulti-tenant cloud systems that hinder the deployment of time-sinsitiveapplications, with particular attention to shared memory subsystems andvirtualization boundaries.
We then focus on two representative challenges:memory bandwidth isolation and hypervisor attack surfaces, examiningrecent research efforts as well as their practical limitations.

Weconclude by questioning whether real-time cloud is a technically groundedobjective, or a business-driven narrative that underestimates thestructural constraints of modern cloud architectures.

Resource-efficient NextG MIMO Sensing and Communications: BridgingSparse Arrays, Spatial Modulation and Subspace Codes
2026-03-26 14:00 - 15:00 | Amphi 3, 19 Place Marguerite Perey, Palaiseau, France
This talk explores emerging connections between sensing,modulation and coding through the unifying lens of sparse antenna arraygeometries. We first explore the versatile uses of index modulation viaantenna selection in integrated communications and sensing (ISAC). Wedemonstrate that judicious antenna subset selection can offer enhancedsensing performance, as well as a balance between spectral and energyefficiency by making clever use of multiple antennas per radio-frequency(RF) chain. We then show that the canonical sensing problem ofdirection-of-arrival estimation can be naturally interpreted as a so-calledanalog subspace coding problem. Subspace coding conventionally arises innon-coherent communications, where neither transmitter nor receiver knowsthe channel, and information is encoded in subspaces rather than vectors.However, connections to sensing have remained unexplored. We bridge thisgap and demonstrate how it fosters new research problems at theintersection of coding theory and signal processing, including a newprincipled approach to noise-robust sparse array design based on optimizingsubspace distance. Throughout the talk, we show how sparse arraygeometries are key to enhancing sensing performance, reducing hardwarecomplexity, and increasing energy efficiency of next-generationmultiple-input multiple-output systems equipped with far fewer RF chainsthan antennas.

Bio: Robin Rajamäki (Member, IEEE) receivedhis D.Sc. degree in electrical engineering in 2021 from Aalto University,Finland. From 2022-2024, he was a postdoctoral scholar at the Universityof California San Diego. He is currently an assistant professor at TampereUniversity, Finland. His research interests lie in the intersection oftheory and applications of statistical signal processing with a focus onmultisensor systems in sensing and wireless communications.

Coexistence of eMBB and mMTC in CF-mMIMO Systems
2026-03-19 14:00 - 15:00 | Amphi 3, 19 Place Marguerite Perey, Palaiseau, France
Future wireless networks must support heterogeneous serviceswith markedly different requirements, such as enhanced mobile broadband(eMBB), which demand high data rates, and massive machine-typecommunications (mMTC), which seek long battery lifetimes. Recently,cell-free massive MIMO (CF-mMIMO) has emerged as a promising paradigm forproviding uniform service quality and flexible resource allocation in suchscenarios.

In this talk, we investigate uplink multiple-access schemesfor the coexistence between these two use cases. We consider anon-orthogonal access strategy in which low-rate mMTC transmissions arespread across the time–frequency resources concurrently used by eMBBusers, enabling efficient resource reuse while supporting heterogeneoustraffic.

Assuming imperfect channel state information, we deriveclosed-form expressions for the achievable uplink rates of both services,based solely on statistical channel knowledge. For mMTC devices, theanalysis explicitly accounts for the finite blocklength (FBL) regime tocharacterize short-packet transmissions.

To accommodate heterogeneousservice requirements, we formulate a power-control problem that maximizesthe minimum energy efficiency across mMTC devices while enforcingquality-of-service constraints for eMBB users. The resulting nonconvexfractional optimization is addressed via sequential fractionalprogramming, with formulations that cover both the classical Shannon andFBL regimes.

Numerical results demonstrate that the proposed schemeenables effective multiplexing of eMBB and mMTC traffic while maintainingthe desired reliability-efficiency trade-offs. As future work, we plan toinvestigate learning-based approximations of the proposed optimizationframework (e.g., using graph neural networks) to further reducecomputational complexity and enable real-time operation.
BIO
SergiLiesegang (Member, IEEE) received the bachelor’s degree intelecommunication engineering from the Universitat Politècnica deCatalunya (UPC) in 2015, the joint master’s degree in telecommunicationengineering from UPC in collaboration with the Technische UniversitätMünchen (TUM) in 2017, and the Ph.D. degree (cum laude) in signal theoryand communications from UPC in 2022. From 2015 to 2018, he was a ResearchAssistant in the Signal Theory and Communications Department at UPC. FromMarch 2022 to June 2022, he was a Visiting Researcher with the Universitàdegli Studi di Cassino e del Lazio Meridionale (UNICAS). From September2022 to May 2023, he was a Research Associate with UPC. From June 2023 toJuly 2025, he was a Post-Doctoral Fellow with the Consorzio NazionaleInteruniversitario per le Telecomunicazioni (CNIT). Since February 2024,he has been the recipient of a Marie Sk?odowska-Curie Actions (MSCA)Individual Grant with UNICAS and is currently on secondment with Nokia BellLabs Paris-Saclay. His areas of interest include signal processing andwireless communication theory, with special emphasis on beyond-5G and 6Gsystems.

Scientific Strategy Session: Follow-Up to the Members’ Retreat
2026-03-12 00:00 | Amphi 2, 19 place Marguerite Perey, Palaiseau, France
The immersive LINCS workshop on December 17–18 wasproductive, resulting in the identification of promising research areas,new collaborations, and adjustments to some lab activities.

The purposeof this meeting is to share these outcomes with all LINCS members (seniorresearchers, postdoctoral fellows, PhD candidates, research engineers,and interns), to present the thematic areas in detail, to discusspossible extensions, and to collectively shape the organization of ourlaboratory’s future activities.

GROUPS

AI & Networks(Daniel, Leonardo, Qiong, Andrea, Alonso, Francesca, Marc-OlivierB., Fabio)
Quantum 2.0 (Ludovic, Rémi, Marc-Olivier R.,Sébastien, Joaquin)
NTN (François, Aslan, Ashutosh, Calvin,Philippe)
Information Theory (Aslan, François, Ashutosh,Philippe)

The program and the presentations by the participatingresearchers are available on the event page:
https://www.lincs.fr/events/members-immersive-workshop/

Network Calculus: Guaranteed performance analysis in networks
2026-02-19 13:00 - 14:00 | Amphi 3, 19 Place Marguerite Perey, Palaiseau, France
Network calculus is a theory developed to compute worst-caseperformance guarantees in networks. When analyzing complex networks (inparticular multi-class), the analysis requires two-step approach:decomposing the network into several single-class networks, and analyzingthese single-class network. In this talk, I will show that some schedulingpolicies (such as DRR) exhibit some inter-dependency structures and requirethat these two steps are intricate. I will present an iterative scheme thatimproves both the performance bounds and stability region compared to thestate of the art.

MetaLore: Learning to Orchestrate Communication and Computation forMetaverse Synchronization
2026-02-12 14:00 - 15:00 | Amphi 7, 19 Place Marguerite Perey, Palaiseau, France
As augmented and virtual reality evolve, achieving seamlesssynchronization between physical and digital realms remains a criticalchallenge, especially for real-time applications where delays affect theuser experience. This paper presents MetaLore, a Deep ReinforcementLearning (DRL) based framework for joint communication and computationalresource allocation in Metaverse or digital twin environments.

MetaLoredynamically shares the communication bandwidth and computational resourcesamong sensors and mobile devices to optimize synchronization, whileoffering high throughput performance. Special treatment is given insatisfying end-to-end delay guarantees. A key contribution is theintroduction of two novel Age of Information (AoI) metrics: Age of RequestInformation (AoRI) and Age of Sensor Information (AoSI) — integrated intothe reward function to enhance synchronization quality.

An open sourcesimulator has been extended to incorporate and evaluate the approach. TheDRL solution is shown to achieve the performance of full-enumerationbrute-force solutions by making use of a small, task-oriented observationspace of two queue lengths at the network side. This allows the DRLapproach the flexibility to effectively and autonomously adapt to dynamictraffic conditions.

Towards a Federated Public Computing Continuum Platform
2026-02-04 13:45 - 14:45 | Amphi Rose Dieng, 19 place Marguerite Perey, Palaiseau, France
Building a large-scale, multi-tenant, public, andgeo-distributed computing continuum platform that includes both cloud andedge environments, and where any application can be deployed, requires alarge amount of computing resources deployed across strategicallydistributed locations, spanning an entire country or even a continent. Oneof the challenges to realizing this public computing continuum platform isscalability. To this end, we focus on addressing some scalabilitychallenges and propose a series of solutions. First, we present themeta-federations concept, where many independent local resource providersmay lease their resources to multiple fog providers to solve the servicecoverage and resource utilization issues. We propose UnBound, a scalablemeta-federations framework that specifically addresses the difficultmulti-tenancy challenges introduced by metafederations. Second, we proposetwo monitoring frameworks designed for geo-distributed cluster federationenvironments, Acala and AdapPF, which aim to reduce the cross-clusternetwork traffic of monitoring while maintaining the accuracy of themonitoring data.

Queuing Theory for Throttled Quantum Link Protocol Modeling
2026-01-28 14:00 - 15:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
To facilitate the control and management of the future quantumnetworks, one needs a quantum link protocol (QLP) that ensures a constantand reliable rate of entangled qubit storage in the adjacent nodes. In thistalk, we propose a throttled QLP. We use queuing modeling with Markovchains to evaluate its performances. We show the good performances of ourthrottled QLP proposal, with stabilized rate of entanglement distributionand low probability of delivery failure.

Toward a privacy aware intrusion detection in IntelligentTransportation Systems
2026-01-21 14:00 - 15:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
In Cooperative Intelligent Transportation Systems (C-ITS), thecontinuous exchange of large data volumes is critical for the effectivenessof applications, making the security of these messages essential. Forinstance, to protect the privacy of road users, vehicles are required tofrequently change their pseudonyms, along with other network identifierssuch as IP addresses, MAC addresses, and so on. This dynamic nature ofidentifier changes introduces significant challenges for performingefficient intrusion detection, as tracking and identifying maliciousbehavior becomes more complex.

In this context, there is a growing needfor an advanced Intrusion Detection System (IDS) tailored for C-ITSenvironments. This IDS must ensure a balance between meeting the strictprivacy requirements set by standards and enhancing the detection andprevention of intrusions and cyber threats.

In this presentation, weemphasize the critical importance of privacy-aware intrusion detection andprovide key recommendations for conducting research in this domain.

Network acceleration for AI workloads
2026-01-14 14:00 - 15:00
Network acceleration is critical for modern AI workloads,particularly in optimizing communication and data transfer amongdistributed GPUs. The network has emerged as a significant bottleneck forLarge Language Model (LLM) training and execution, driving rapidadvancements in GPU network technologies. This evolution, however,introduces complex research challenges spanning load balancing, congestioncontrol, collective communications, and novel network architectures. Thispresentation will first establish the fundamental distinctions between AIdata centers and conventional cloud computing environments, followed by anoverview of ongoing research topics in this rapidly evolving field.

Bio:
Jeremie Leguay received his Ph.D. degree in computer science fromPierre et Marie Curie University, Paris, France. He is Department Head atNokia Bell Labs Paris Saclay on Network Systems Research. From 2004, heconducted research and led the Networking Lab at Thales Communications andSecurity (SIX GTS division) where he developed activities on sensornetworks, mobile networks, and software-defined networks formission-critical networked systems. In 2014, he joined Huawei Technologiesas leader of the Network and Traffic Optimization Team to conduct researchactivities on the planning and control of IP networks. He is Senior IEEEmember. He has been a Senior Expert and Director of the Datacom DijkstraLab at Huawei Technologies. His current activities are mainly on Routing,Network Management and Optimization, Self-driving networks, Automation,Network for AI.

Multi-User Linearly-Decomposable Distributed Computing: FundamentalLimits and New Coded Architectures
2026-01-08 14:00 - 15:00 | Room 3C41, 19 Pl. Marguerite Perey, Palaiseau, 91120, France
This talk presents the main results of my PhD thesis, defendedin 2024 at Sorbonne University, devoted to the theoretical study ofmulti-user distributed computation for linearly-decomposable functions. Inthis framework, we construct a general model in which a matrix ofcomputational demands can be factorized into two sparse matrices—acomputation matrix and a communication matrix—revealing deep connectionswith several areas: coding theory, covering codes, syndrome decoding,compressed sensing, and fixed-support matrix factorization(tessellation).

We will discuss:

fundamental lower and upperbounds on computation and communication costs;
the characterization ofa new class of codes, called partial covering codes;
optimalarchitectures for perfect distributed computing;
a new method calledTessellated Distributed Computing, offering optimalcomputation–communication trade-offs, both in the exact and approximateregimes.

These results lead to practical applications in large-scaledistributed systems, distributed machine learning, and high-performancecomputing infrastructures.

Bio: Ali Khalesi is an AssistantProfessor (Maître de conférences) at IPSA, Ivry-sur-Seine, andrecipient of the 2nd Prize for the Best PhD Thesis—EDITE Paris 2025, aswell as finalist for the 2025 Chancellerie de Paris Awards.
He obtainedhis PhD in 2024 from Sorbonne University, within EURECOM, under thesupervision of Prof. Petros Elia.
His research focuses on the fundamentallimits of distributed computing, information theory, coding theory, andthe analysis of communication–computation trade-offs in moderndistributed architectures.

The role of AI in the phenomenon of Information Disorder:Challenges, Methods and Insights
2026-01-07 14:00 - 15:00 | Amphi 7, 19 Place Marguerite Perey, Palaiseau, France
This talk explores the growing phenomenon of informationdisorder and the dual role of artificial intelligence, both inexacerbating the problem through increasingly sophisticated generativetools and in supporting its analysis, detection and mitigation.

Withina national initiative, SERICS (Security and Rights in the Cyberspace), wehave developed and tested a set of models, analytical components, andprototype tools inspired by industry standards for threat intelligence andcognitive security. These research prototypes combine large-scaleacquisition and enrichment of online content with AI-based modules forassessing source reliability, detecting coordinated behaviours andsupporting claim verification.

The seminar will also outline thedirections we are now pursuing toward pre-bunking strategies, aiming toanticipate manipulative dynamics before they unfold and to better supportanalysts and decision-makers in managing emerging cognitivethreats.

Short bio
Giuseppe Fenza is an Associate Professor of ComputerScience at the University of Salerno, where his research spanscomputational intelligence, knowledge extraction, and AI-drivenapproaches to information disorder and cognitive security. He wasco-founder of the digital-health spin-off Riatlas and is currentlycontributing to the creation of IntelliTrust, focused on advancedsolutions for countering disinformation. He has authored over 90publications and serves as Associate Editor-in-Chief of Neurocomputing andArea Editor of KSII Transactions on Internet and InformationSystems.
Slides:
https://www.lincs.fr/wp-content/uploads/2026/01/LINCS-Seminar_Fenza_07012026.pdf
Links

https://github.com/Information-Disorder-Awareness
https://huggingface.co/IDA-SERICS

Members Immersive Workshop
2025-12-17 - 2025-12-18
The objective is to step away from ourdaily routines in order to collectively reflect on the future activities ofLINCS, share our scientific visions, identify priority research themes,and strengthen collaborations within our joint laboratory.

Thisdedicated time will allow everyone to contribute to a strategic reflectionon the lab’s future directions, while benefiting from an environmentconducive to exchange, creativity, and collegiality, complemented by arange of informal and engaging activities.

The program will combinescientific sessions with brainstorming and debate, as well as informalmoments.

The outcomes of the plenary sessions and thematic workinggroups will soon be presented to the full community and will serve as thebasis for shaping the LINCS two-year strategy through an inclusive,collective process.
Scientific Programme

Mot du directeur

Rappel des objectifs du LINCS, de son organisation, des résultatsstructurants obtenus, présentation de son écosystème (PEPR, CentreRSTN, FRAMExG, France6G, CSF, agences de programme, etc.)
Rappeldes difficultés générées par le déménagement et des actionsentreprises pour les mitiger
Etat de situation et vision d’ensembledes activités à venir
Introduction aux échanges prévus dans lesdiverses activités des 2 journées

Présentations de nouveauxmembres : parcours, sujets de recherche, vision d’ensembleinteractions prévues au sein du LINCS

Aslan Tchamkerten (TélécomParis)
Ashutosh Balakrishnan (Télécom Paris)
Marc-Olivier Renou(Inria)

Présentations travaux membres

Alonso Silva (Nokia BellLabs)
Andrea Araldo (Telecom Sud)
Ashutosh Balakrishnan
Chung Sue- Calvin (Nokia Bell Labs)
Fabio Pianese (Nokia Bell Labs)
JoaquinGarcia-Alfaro (Telecom SudParis)
Remi Varloot (Nokia Bell Labs)

Présentations thématiques structurantes pour le LINCS par les membres duCOMEX

François Baccelli (Inria, Télécom Paris) : NTN
FrancescaBassi (SystemX) : Cyber
Ludovic Noirie (Nokia Bell Labs) : Quantique
Sébastien Tixeuil (Sorbonne Université) : IA et Réseaux

Brainstorming

Identification de sujets de recherche existants etémergents au sein du LINCS à fort potentiel et à visibilitéinternationale
Désignation d’un volontaire chargé de structurer lesactivités futures
Sélection des sujets qui seront abordés dans lasuite de l’événement

Travail en groupe parthématique

Synthèse et conclusions

LLM-Driven Scheduler Generation for Intent-Based RAN
2025-12-10 14:00 - 15:00 | Amphi 7, 19 Place Marguerite Perey, Palaiseau, France
The shift toward open, programmable O-RAN and AI-RAN 6Gnetworks presents new opportunities for Intent-Based Networking (IBN) todynamically optimize RAN operations. However, applying IBN to the RANscheduler—a key component for resource allocation—remains challenging.Existing methods rely on coarse network slicing, lacking the granularityto adapt to individual user conditions and traffic. While many schedulingalgorithms exist, their use is limited by implementation complexity, lackof systematic evaluation, and deployment challenges. To overcome this, weintroduce ALLSTaR, a novel framework that uses LLMs to automateintent-driven scheduler design, implementation, and evaluation. ALLSTaRtranslates natural language intents, extracts scheduler logic fromacademic literature using OCR and LLMs, and deploys them as O-RAN dApps ona production-grade, multi-vendor 5G testbed. This enables the largest OTAcomparison of 18 synthesized schedulers and forms the basis for anIntent-Based Scheduling system that dynamically selects and deploys theoptimal scheduler. Our approach supports use cases beyond current slicingtechniques, enabling fine-grained control based on buffer status, PHYconditions, and diverse traffic types.

Preprint 1:https://arxiv.org/pdf/2505.18389

Preprint 2:https://arxiv.org/abs/2508.17778

High Speed Networking: From Kernel Bottlenecks to Line-Rate PacketProcessing
2025-12-03 15:15 - 16:15 | Amphi 7, 19 Place Marguerite Perey, Palaiseau, France
Modern networked systems are moving from hardware intoflexible, programmable platforms. Among the key enablers of this shift welist the Intel DPDK and the eBPF ecosystem in conjunction with the eXpressData Path (XDP), both allowing packet processing at very high rates.
Asthe classic per-packet processing model used by the usual networking stackcan become a bottleneck (especially with pressure on CPU pipelines and thenumber of instructions per packet required), new designs require treatingpackets in batches, data prefetching, vectorized operations and betterinstruction-level parallelism. In this talk, we will show how kernelbottlenecks impact line-rate packet processing and how modern approachesattempt to overcome them, offering an accessible introduction toprofiling, optimization, and programmable data paths in virtualizednetworking environments.
These ideas illustrate how rethinking executionmodels can significantly improve packet-processing efficiency. This talkprovides an accessible introduction to these concepts, focusing on how XDPfits into virtualized networking, why profiling matters, and howbatching-aware techniques can unlock new optimization opportunities formodern programmable data paths.

Bio: Vladimiro is a second-year PhDstudent at Sapienza University of Rome. At the beginning of his PhD, hefocused on studying network functions and their performance. Together withhis advisor, Salvatore Pontarelli, and his colleagues, he developed aprofiler for eBPF applications that introduces only minimal overhead on theprogram being analyzed. He is now working on improving the performance ofeBPF-based networking applications by bringing a batching model to eBPF.

Fundamental Limits of Distributed Detection in the Low-Power Regime
2025-12-03 14:00 - 15:00 | Amphi 4, 19 Pl. Marguerite Perey, Palaiseau, 91120, France
In this talk we consider distributed detection systems (sensornetworks) where the sensors are subject to stringent communicationconstraints, mostly stringent power or bandwidth constraints.
We presentthe optimal Stein-error exponents for different distributed detectionsystems and explain the communication and testing schemes that achievethese optimal exponents. Our results reveal interesting dichotomies of theStein-exponent with respect to the connectivity of the channel: If allinputs can lead to all outputs, then the Stein-exponent under stringent(probability 1) power constraints equals the exponent of a local test atthe decision center only. I.e., The sensors and their observations cannotimprove this exponent. In contrast, if the channel is degenerate theStein-exponent is the same as when communication is over a noiselesschannel. Under slightly less stringent power constraints (on expectationinstead of probability 1) the Stein-exponent will depend on the exactchannel law if the channel is fully connected and also on whether the powerconstraint is imposed under all hypotheses or not. We completelycharacterize the Stein-exponent also when stringent power constraints areimposed on expectation.

Optimisation de l’allocation des ressources dans les réseauxsans fil du futur en présence d’incertitude
2025-11-27 14:00 - 18:00 | Amphi Rose Dieng, 19 place Marguerite Perey, Palaiseau, France
We address in this thesis the challenge of efficient resourceallocation under uncertainty for the transport of time-critical ultrareliable traffic in next-generation networks. We develop optimization andonline-learning methods that provide rigorous performance guarantees forshort-horizon probabilistic requirements and long-term cumulativeconstraints. We begin with Ultra-Reliable Low-Latency Communications(URLLC). Prior models for probabilistic delay either impose strongassumptions on arrivals or focus primarily on queue stability. We relaxthese assumptions and formulate a chance-constrained minimization ofresource usage that holds under general arrival processes. By exploitingstructural properties of the policy space, we design efficientbandit-based algorithms for both offline (known statistics) and online(unknown statistics) settings. These algorithms provably converge in afixed number of iterations while meeting stringent 1ms delay and (10^{-5})reliability targets with minimal resource consumption. We then push theseguarantees to extreme URLLC targeting (0.1,mathrm{ms}) latency andreliability on the order of (10^{-7}), where queuing is impermissible andthe resource allocation schemes must rely on limited arrival information(historical samples, mean, variance). Static methods tend toover-allocate resources. We introduce an online, dynamic reservationpolicy based on a sliding-window scenario approach that is robust and safe:it tracks minimal reservations from empirical data and avoids conservativeover-provisioning while preserving stringent QoS constraints. Next, weconsider goal-oriented communications, focusing on haptic applicationsthat are highly sensitive to bursts of packet losses. We propose aqueuing-theoretic framework which minimizes resource costs in the presenceof losses from both collisions with other haptic packets and poor radioconditions. We design a joint control policy that combines adaptivetransmit-power boosting with preemption of resources initially provisionedfor enhanced Mobile Broadband (eMBB), governed by threshold policies. Forheterogeneous users, interdependence across user groups induces ahigh-dimensional decision space, ruling out exhaustive search. To addressthis complexity, we make use of a modified simulated-annealing algorithmwith constraint handling through direct rejection of infeasible policies orcost-based penalties. Eventually, we study long-term compliance andintroduce Constrained Online Convex Optimization with Memory (COCO-M),where losses and constraints depend on the last (m) decisions. Prior workconsidered mainly fixed memory length. We generalize to arbitrary memorylengths and incorporate untrusted short-horizon predictions, providing thefirst algorithms with provable sublinear regret and sublinear cumulativeconstraint violation in this general setting. This yields a versatiletoolbox for online learning and predictive network control underadversarial conditions.

Privacy-aware passive sniffing: from wireless measurements tobounded trajectories
2025-11-26 13:00 - 14:00 | Amphi 7, 19 Place Marguerite Perey, Palaiseau, France
With the widespread proliferation of smartphones, wirelessconnectivity data has become a powerful lens for studying human behaviorand mobility. In this talk, I will focus on the full pipeline of usingwireless connectivity data for mobility analysis. We will start from thedesign of the data collection itself: selecting the appropriatetechnologies, frame types, and header fields to capture, while embeddingprivacy-preserving mechanisms directly into this process. Then, we willaddress how to consolidate raw observations into coherent device-levelviews and how to build on these representations to reconstruct users’trajectories. This spans the entire workflow, ultimately transforming rawsignals into meaningful mobility and context insights.

DDoS Attacks: Impacts, detection methods, and advanced strategies
2025-11-19 14:00 - 15:00 | Amphi 5, 19 Place Marguerite Perey, Palaiseau, France
Distributed Denial of Service (DDoS) attack detection remains achallenging problem in cybersecurity. In DDoS, a network of compromiseddevices is used to overwhelm a target with a flood of requests, making itunable to serve legitimate requests. Recently, we have witnessedincreasing interest in DDoS detection using machine learning (ML) and deeplearning (DL) algorithms. ML/DL can improve the detection accuracy, butthey can still be evaded through the use of ML/DL techniques in thegeneration of the attack traffic. In this talk, we will discuss DDoSattacks, their impacts, and detection solutions. We will also present aDDoS detection method based on Long Short-Term Memory (LSTM) and explainhow a GAN model generator can create DDoS traffic that closely matches theDDoS instances from our dataset, making it appear similar to benigntraffic. Additionally, we will explain how to enhance this approach todetect adversarial DDoS attacks.

User-side Opportunistic Channel Charting & Location-Aware AccessPoint Selection
2025-11-12 14:00 - 15:00 | Amphi 7, 19 Place Marguerite Perey, Palaiseau, France
Channel Charting (CC) is a promising tool for managing radioresources, especially those tied to user location. Conventionally, CCinvolves a dimensionality reduction of channel state information (CSI) toobtain a low-dimensional latent space. While conceived to be performed atthe network side (e.g., base stations or access points), CC could bebeneficial for end-devices. In practice, end-user devices often haveaccess to heterogeneous and non-cooperating networks, with nocoordination. In such a setup, decision-making must occur on the user sideto fully leverage available networks. For this reason, user-side CC isparticularly relevant. In this work, we introduce a user-side CCframework: Opportunistic Channel Charting (OCC). OCC allows mobile devicesto localize themselves in the radio environment opportunistically. UnlikeCC, OCC allows devices to build a chart from passively acquired CSI. Thisis done by monitoring the ambient wireless channels. Via real-worldexperiments, using commodity devices, we validate OCC. Our results showthat OCC captures geometric information comparable to conventional CC interms of trustworthiness and continuity while requiring no cooperation fromsurrounding devices. During measurements of CSI, we also measure networkquality. To exploit this, we propose a new OCC-based Wi-Fi Access Point(AP) selection (OCCAPS).

RAN Automation using Reinforcement Learning: the cases of MobilityRobustness Optimization and MU-MIMO Frequency Scheduling
2025-11-05 14:00 - 15:00 | Amphi Estaunié, 19 Place Marguerite Perey, Palaiseau, France
This talk will present the ongoing activities at EricssonResearch in Massy, France related to RAN automation. After a generalpresentation, we will discuss in detail two specific use cases:

(a) theMobility Robustness Optimization for intra-frequency handover; we learn toautomatically tune the Cell Individual Offset of each cell boundary usingoffline Reinforcement Learning without exploration, by exploiting alreadycollected data.

(b) the frequency scheduling of users to sub-bandssupporting MU-MIMO concurrent transmission. This is a challenginglarge-action and large-state space problem which we tackle using onlineaction decomposition methods inspired my multi-agent reinforcement learning(MARL) and Graph Neural Networks (GNNs).

In both use cases we show thatAI-methods outperform traditional rule-based solutions and highlight thepotential benefits from AI in RAN automation of future 6Gnetworks.

References:

[MRO] “Offline Reinforcement Learning forMobility Robustness Optimization”, P. Alizadeh, A. Giovanidis, P.Ramachandra, V. Koutsoukis, O. Arouk, in European Wireless 2025(https://arxiv.org/abs/2506.22793)

[MU-MIMO Frequency scheduling] A.Giovanidis, M. Leconte, S. Aroua, T. Kvernvik and D. Sandberg, "OnlineFrequency Scheduling by Learning Parallel Actions," 2024 3rd InternationalConference on 6G Networking (6GNet), Paris, France, 2024, pp. 153-160,doi: 10.1109/6GNet63182.2024.10765674.

Technical, Economic and Environmental Evaluation of Vehicular andEdge Computing
2025-11-04 14:00 - 18:00
Keywords: Vehicular Cloud Computing, Task Offloading,Game-Theoretic Optimization, Sustainable Computing

Abstract:
Thisthesis investigates the technical, economical and environmentalfeasibility of computing architectures for supporting delaysensitiveapplications such as Augmented Reality (AR) and Autonomous Driving (AD).While Cloud Computing (CC) is the prevalent computing paradigm today, itcannot offer sufficiently low latency. This limitation is overcome by EdgeComputing (EC), which consists in deploying computational capability atthe edge of the access network. However, EC entails high infrastructurecosts and raises environmental concerns, due to the short lifecycle ofelectronic devices (around four years) and increased energyconsumption.

Meanwhile, the number of connected vehicles is steadilyincreasing. These vehicles already carry onboard computing andcommunication resources that can be opportunistically exploited, not onlyfor driving-related tasks, but also for task offloading computation fromexternal devices, e.g., smartphones, laptops, or wearable healthdevices of end-users. These resources available in the vehicles can bemanaged under the paradigm of Vehicular Cloud Computing (VCC).

In thisthesis, we first analyze the economic feasibility of Edge Computingdeployment through a game-theoretic model, showing how multitenantcooperation can mitigate the high cost of deployment. Then, we evaluateunder which conditions VCC can replace EC, i.e., whether offloading tasksto vehicles can provide similar performance to EC. Results are obtained viahigh fidelity network and mobility simulations, in an urban mobile networkscenario. We find that VCC can achieve ultra-low latency, with delays ofabout 10 ms, even when vehicles are sparsely distributed. A comparativecost analysis shows that replacing EC with VCC can reduce infrastructureexpenditure by approximately 10% over five years. Finally, we propose aVCC management scheme to optimize energy consumption, carbon emissions,and to compute a fair allocation of the revenues generated by serviceend-user tasks.

The scheme is based on mathematical programming andcoalitional game theory. Via Monte-Carlo simulation, we show that energyconsumption due to VCC is below 0.1% of the overall vehicle consumption inrealistic scenarios, and that vehicle owners receive substantialincentives for participating in task execution.

In summary, this thesisdemonstrates the feasibility of future generation mobile networkarchitectures, such as Edge Computing and Vehicular Cloud Computing, tosupport extremely low-latency applications.

«Way to 6G» @ MASCOTS Conference
2025-10-22 09:00 - 2025-10-23 17:00 | Sorbonne University - Campus Les Cordeliers, 15, rue del'École-de-médecine, Paris, 75006, France
The 33rd International Conference on Modelling, Analysis andSimulation of Computer and Telecommunications Systems(https://mascots25.iitis.pl/) will take place in Paris at SorbonneUniversity.

The LINCS organise the workshop « Way to 6G » that willbe held on October 23.

5G systems are now up and running in manycountries and various regions across the world, and research is turningits attention towards understanding the full potential and limitations of5G, defining and investigating relevant test-beds and experimentalframeworks, and defining the new frontier of 6G networks. Thus, new andmore demanding application areas are being considered, such as IntegratedSensing and Communications (ISAC), Tele-Presence and enhanced reality,Dependable Low Latency Systems that are needed for the Internet of Vehiclesand other applications, and massive-scale ubiquitous communications. Thesedevelopments will be aided by artificial intelligence, quantumcommunications and new terrestrial and spatial technologied to meetextremely high technical specifications. International bodies such 3GPP andthe International Mobile Telecommunications project are already planningfor these developments and the next five to six years 2025-2030 will allowus to address these challenges.

This workshop will attract researchpapers that:

Investigate the important issues of sustainability,security and network resilience
Investigate the relevant theoretical andexperimental methods
The wired and wireless technologies that enablemassive bandwidth enhancements and connect the unconnected
Discusspotential technical solutions and usage scenarios
Investigate theimportant issues of sustainability, security and network resilience.

Multi-Agent Reinforcement Learning for URLLC Modern Random Access
2025-10-15 14:00 - 15:00 | Amphi 7, 19 Place Marguerite Perey, Palaiseau, France
Future wireless networks are expected to support a wide rangeof use cases with diverse requirements. Among these, Ultra-ReliableLow-Latency Communications (URLLC) stand out as a key enabler fortransformative applications across industries such as intelligenttransportation, smart grids, and industrial automation.

Theseapplications demand extremely high transmission reliability coupled withvery low latency, posing stringent quality of service (QoS) challenges.Since the emergence of 5G, numerous enhancements have been introduced tomeet URLLC demands.

However, ensuring adequate QoS still requires thedesign of new medium access control (MAC) protocols and advanced schedulingpolicies. In this seminar, we present recent research addressing thescheduling of URLLC traffic on the uplink using Modern Random Access (MRA)and Multi-Agent Reinforcement Learning (MARL).

We first formulate theURLLC MRA (uMRA) problem as a Decentralized Partially Observable MarkovDecision Process (Dec-POMDP). We then introduce uMRA-HAPPO, a MARL-basedsolution employing the Heterogeneous Agents Proximal Policy Optimization(HAPPO) algorithm.

Finally, we evaluate our approach in scenariosinspired by 3GPP use cases, demonstrating that uMRA-HAPPO achieves higherreliability than traditional deterministic and random schedulingstrategies, while satisfying strict latency constraints.

Estimating the hyperuniformity exponent of point processes
2025-10-08 14:00 - 15:00 | Amphi 7, 19 Place Marguerite Perey, Palaiseau, France
A joint work with G. Mastrilli, B. Blaszczyszyn, F.Lavancier

Hyperuniformity characterizes random spatial structures whoselarge-scale variance grows more slowly than that of Poisson processes.First introduced in statistical physics by Torquato and Stillinger [1],hyperuniform systems have attracted considerable attention due to theirintermediate nature between perfect crystals, liquids, and glasses, andappears in a wide range of applications, from DNA organization and immunesystem dynamics to photoreceptor arrangements, urban planning, andcosmology.
Detecting and quantifying hyperuniformity is essential acrossthese diverse fields. Yet, statistical testing for hyperuniformity hasonly recently begun to develop. In joint work [2], we address the problemof estimating the “strength” of hyperuniformity—formally, theexponent governing the decay of the spectral density near zerofrequency—in a class of stationary point
processes in Euclidean space.The key mathematical idea is that the variance of linear statistics,defined using smooth, rapidly decaying test functions, grows in a waythat explicitly reflects this exponent. Using a multivariate central limittheorem for a family of such statistics, constructed from orthogonalfunctions at multiple scales (e.g., wavelets), we derivean
asymptotically consistent estimator of the strength of hyperuniformity.This estimator can be computed from a single realization of the pointprocess and comes with explicit confidence intervals. We validate thisapproach through simulations of various point process models anddemonstrate its applicability on real data.

Bibliography
[1] Torquato,S. and Stillinger, F. H. (2003). Local density fluctuations,hyperuniformity, and order metrics. Physical Review E 68 041113.
[2]Mastrilli, G., B laszczyszyn, B. and Lavancier, F. (2024) Estimatingthe hyperuniformity exponent of point processes arXiv:2407.16797.

Statistical learning from high-dimensional and distributed data
2025-10-01 14:00 - 15:00 | Zoom + Amphi 4 chez Télécom-Paris, 19 Place Marguerite Perey,Palaiseau, 91120, France
Modern learning algorithms must tackle real-world problemsinvolving complex, heterogeneous, often unlabeled, high-dimensional,and potentially large-scale and/or distributed data.

In this talk, thespeaker will present a statistical learning approach focused on the designof latent variable models, with approximation capabilities and learningguarantees. He will begin by introducing mixture-of-experts models designedfor heterogeneous data and high-dimensional functional predictors, whichmay be noisy, and their training via regularization methods, enablingsparse and interpretable representations.

Finally, when data areinherently distributed and/or constrained by confidentiality requirements,the speaker will present federated learning and aggregation strategy for(statistical or neural) models trained in parallel.

Stochastic Geometry and Dynamical System Analysis ofNon-Terrestrial Networks
2025-09-24 14:00 - 15:00
This lecture will be mainly focused on broadband communicationnetworks based Low Earth Orbit satellite constellations.

It will firstdescribe the structure of these constellations, their overallfunctionalities, as well as the economic and strategic context of theircurrent deployment.

It will then survey recent and ongoing results onthe mathematical analysis of such networks.

It will first show that thestochastic geometry framework for planar cellular networks can be extendedto this new spherical geometry setting. This leads to a system levelanalysis of coverage and spectral efficiency of this new
class ofnetworks.

In addition, it will show that a dynamical system analysis ofthis class of networks leads to new results on their ergodic or periodicbehavior. The consequences on the dynamics of association, handover, androuting algorithms used in these networks will also be discussed.

Measuring and Mitigating Risks with AI-Driven Information Targeting
2025-09-17 14:00 - 15:00 | Amphi 7, 19 Place Marguerite Perey, Palaiseau, France
In this talk, the speaker will discuss risks related to onlineadvertising and micro-targeting, and present methods for measuring andreducing these risks. I will share insights from some of our latest resultson political ad micro targeting

LINCS Annual Workshop with the Scientific Committee 2025
2025-07-10 09:00 - 2025-07-11 17:00 | Amphi Rose Dieng, 19 place Marguerite Perey, Palaiseau, France
As is tradition, we are pleased to invite you to the 2025edition of our Annual Workshop with the Scientific Committee : a two-dayevent taking place on July Tuesday 10 and Friday 11 in Palaiseau,featuring scientific highlights, surveys, elevator pitches, and postersfrom our scientific community.In addition, on the evening of the 10th, weare pleased to invite you to a dinner cruise on the river Seine.

Wewarmly encourage everyone, to submit a presentation of their work to sharewith our scientific community.

Like past years, the 2025 editionwill be filled by diffrents kind of talks:

Talks by scientificcommittee members

Scientific Highlights talks by LINCS members, Phdstudents, postdocs or engineers

Survey talks by LINCSmembers

Elevator pitch & poster session by Phd students &postdocs

Thank you for your continued support and dedication toscientific progress and collaboration.

Program(click for printableversion)

Thursday, July 10th, 2025

Coffeereception

9:00/9:30

Opening by Sébastien Tixeuil(Sorbonne University) Presentation of the edition 2025 of the LINCS AnnualWorkshop with the Scientific Committee

9:30/9:35

Directorspeech by Daniel Kofman (Télécom Paris) Presentation of LINCS: Identity/ Spirit / Mission / Perspectives

9:35/9:45

1st LINCSScientific Highlights Securing V2X communications in cooperative drivingapplications: the platooning use caseFrancesca Bassi(SystemX)

9:45/10:00

1st Invited talk from the ScientificCommittee A load-balancing journey towards improving earth-scaleatmospheric modeling*Roch Guerin (Washington University in SaintLouis)
Modeling the earth atmosphere is both a scientific andcomputational grand challenge. Much progress has been made in developingand implementing models that track the planet-scale evolution of the earthatmosphere and predict its response to various perturbations. Those modelsare unsurprisingly computationally onerous and running them at scale isfeasible only through extensive parallelization. In this work, we targetGEOS-Chem, an open-source software for simulating the earth atmosphereused by hundreds of researchers worldwide and capable of large-scaleparallelism. GEOS-Chem inherent parallelism notwithstanding, leveraging itto realize effective speed-ups gives rise to interesting load-balancing andscheduling challenges. Of particular interest are the fact thatcomputational workloads exhibit spatial and temporal variations and thatthe effectiveness of solutions to accommodate them vary based on thecharacteristics of the computational and communication platforms, e.g.,whether data movement is realized through a combination of Infiniband andRDMA or Ethernet and (AWS) EFA affects the underlying trade-off betweencomputations and communication. This talks explores those questions and thedifferent approaches they gave rise to, and attempts to offer anillustration of the interplay between engineering and scientificinvestigations that effective solutions often require.
* This is jointwork with Daisy Wang, Jordan Sun, and KunalAgrawal

10:00/10:30

Coffeebreak

10:30/11:00

PhD Elevator Pitch: Ahmad Nasser(Nokia Bell Labs) / Amal Sakr (Télécom SudParis) / Jules Sintes (Inria) /Alessa Mayer (Télécom SudParis) / Baptiste Corban (Inria) / Thomas LeCorre (Inria) / Emanuele Mengoli (Télécom Paris) / Mohammed AmineLegheraba (Sorbonne University) / Ludmila Courtillat-Piazza (TélécomParis)

11:00/11:45

Lunch at the cantine + coffee in theinner garden

11:45/13:30

1st LINCS Survey Quantum 2.0 @LINCSRémi Varloot et Ludovic Noirie (Nokia Bell Labs)
The 1st quantumrevolution was about manipulating groups of quantum particles such asphotons, electrons and atoms, and brought us technologies such astransistors and lasers. The 2nd quantum revolution, or “Quantum 2.0”,is about manipulating individual particles, and promises its own set ofgame-changing innovations. These include quantum computing,communications, networks, security, sensing and more. These technologiesare not fully mature, however, and each one provides numerous researchopportunities. In this talk, we give a quick overview of all thingsQuantum-2.0-related, and outline the past, current and future activitiesat LINCS in this field.

13:30/14:00

2nd LINCS ScientificHighlights Managing the cloud-to-edge continuum under uncertainty via AImethods with performance guaranteesAndrea Araldo (TélécomSudParis)
There is a long tradition of network management methods basedon a precise model of the network and of the load. However, in practicalsituations it is impossible to build such a model, mainly because the loadis uncertain and not known in advance. AI methods can overcome thismodel/reality gap, by continuously adjusting decisions based on streams ofmonitoring observations. In this talk, I will show how we applied AI tomanage the cloud-to-edge continuum, focusing on the following decisions:pricing, placement of multiple “versions” of machine learning models,resource allocation. The methods we applied are Hidden Parameter MarkovDecision Processes, Model-Based QLearning, Online Learning. I will showthat, despite the uncertainty on the input load, we are able to provideanalytic guarantees on the worst-case performance or on the averageperformance. Such guarantees are important to foster the applicability ofAI algorithms, which is often hindered by their black-boxnature.

14:00/14:15

3rd LINCS Scientific Highlights Somehighlights and perspectives in Network CalculusAnne Bouillard(Inria)
Network Calculus is a theory that has been developed to computeperformance guarantees, such as end-to-end delays, in networks. In thistalk, I will discuss some improvement in analysis of multiclass networkobtained in the past years (while working at Huawei), and present someperspective about the worst-casesimulation.

14:15/14:30

4th LINCS Scientific Highlights Certainty-Guided Reasoning in Large Language Models: A Dynamic ThinkingBudget ApproachAlonso Silva (Nokia Bell Labs)
The rise of large reasoninglanguage models (LRLMs) has unlocked new potential for solving complextasks. These models operate with a thinking budget, that is, a predefinednumber of reasoning tokens used to arrive at a solution. We propose a novelapproach, inspired by the generator/discriminator framework in generativeadversarial networks, in which a critic model (potentially a specializedmodel) periodically probes to assess whether it has reasoned enough toreach a confident conclusion. If not, it continues reasoning until atarget certainty threshold is met. We explore how model certainty can bequantified and integrated into the reasoning process, and discuss itspractical implications. Through experiments and analysis, we show thatcertainty-guided reasoning improves accuracy while reducing unnecessarytoken usage.

14:30/14:45

Poster session / RefreshmentBreak

14:45/15:30

2nd Invited talk from the ScientificCommittee DRACO: Dynamic Resource Allocation for Concurrent MLApplicationsHolger Karl (Universität Potsdam)
GPUs are increasinglyused to accelerate ML applications. Often, they are used to offloadinference tasks, which are usually latency-critical. But the arrivalpatterns of inference requests are often bursty and include periods withoutany load. Furthermore, inference tasks may not be able to fully utilizethe compute resources of a GPU, even with larger batch sizes.Consequently, the average utilization of a GPU that is exclusively usedfor an inference service is low. Industry has recognized the problem ofunderutilization and offers solutions to co-locate applications, improvingutilization and cost-efficiency. We show, however, that thesestate-of-the-art solutions only maintain low inference latency when theircompute resources are significantly overprovisioned. We propose DRACO, asystem to co-locate latency-critical inference tasks with a batch job,e.g., training an ML model, without violating the inference latencyrequirements. DRACO autonomously estimates the resource requirements ofinference tasks and detects periods with low load by periodically samplingthe GPU's performance monitoring unit (PMU). Furthermore, DRACO manages apool of streaming multiprocessor (SM) partitions and dynamically assignsthem to inference tasks to meet latency requirements. Leftover resourcesare granted to the co-located batch job. Depending on the workload, DRACOincreases throughput of the batch job by up to 4x compared to industrialsolutions while keeping inference latency low.
* This is a joint work withTheo Radig

15:30/16:00

5rd LINCS Scientific Highlights Modelling Equilibria under IrrationalityAshok Krishnan (Inria)
Models ofstrategic decision making by human agents, usually assume that the agentsare rational. However, in practice, humans exhibit different kinds ofirrational behaviour in their decision making. Prospect theory is amathematical framework that models some aspects of this irrationality. Theapplication of prospect theory in the study of games and equilibria is anemerging area; this provides insights on change in equilibrium behaviourin the presence of irrationality. However, the application of prospecttheory throws open a number of theoretical challenges. The talk willoutline some preliminary results and openquestions.

16:00/16:15

6th LINCS Scientific Highlights Preventing WebRTC IP Address LeaksGuillaume Nibert (SorbonneUniversity)
The WebRTC API enables real-time communication of text,video, and audio media streams through a web browser without requiringthird-party extensions. However, it was not designed with privacy in mind.We conduct an experiment to analyse privacy leaks associated with WebRTC.Our findings show that despite recent updates to the WebRTC specificationand its implementations, sensitive public IP addresses can still be leakedduring audio/video communication, particularly in large non-NAT corporatenetworks, even when using a VPN, SOCKS or HTTP/S proxy. To address theobserved leaks, we develop a simple, easily maintainable, cross-platformopen-source solution that confines the Mozilla Firefox web browser in adocker container. We also take into account the possibility of a maliciousadversary compromising the browser. Our tests have shown that ourcontainerised solution is effective in all situations without restrictingapplications.

https://hal.science/hal-05048077

16:15/16:30

Transfer to Paris for Reception Cruise

17:00

PenicheTIVANO - Escales de Grenelle : Métro : Ligne 6 – stop Bir-Hakeim / RER C: stop Champ de Mars Tour Eiffel / Parking Centre commercial Beaugrenelle,5, Quai André Citroën (70015) / Parking Kennedy / Radio France, 1, av.du Pdt Kennedy (70016)

18:30

Friday, July 11th,2025

Coffeereception

9:00/9:30

7th LINCS ScientificHighlights Overview of Regular Activities for the Upcoming AcademicYearFrancesca Bassi (SystemX)

9:30/9:45

8th LINCSScientific Highlights Handover frequency in dynamic terrestrialcommunication networkSanjoy Kumar Jhawar (Télécom Paris)
In modernarchitecture of communication network using LEO and MEO satelliteconstellation, it is crucial to know how frequently an user is performinghandover. As a key performance metric of the system, handover frequencyessentially reflects onto the cost of quality service. In this talk weconsider a far more simplified model of the same flavor of LEO and MEOsatellite constellation using stochastic geometry. In this dynamiccommunication model on the Euclidean plane we consider an user located atorigin and it is served by the mobile base stations with initial locationsgiven by a homogeneous Poisson point process. The base stations are movingat an identical speed in a random direction. The user stays connected tothe nearest base station at any given point of time. Since the basestations are moving, the user disconnects and connects with different basestations over time, which ever base station is the closest. We determinethe handover frequency first in the single-speed setting and use it as ainspiration to the multi-speed scenario. The model explored in this workhave several important variants which are linked to these motivations.These variants include the finite visibility case, the case when theinitial locations of the base stations are given by Poisson or Manhattanline Cox point processes. Their motion is along the underlying lines. Thefinal variant is of course the spherical case. We shall briefly discussabout the steps towards relaxing these simplifications from the planar tospherical geometry.
*This is a joint work with François Baccelli, InriaParis & Telecom Paris.

9:45/10:00

3rd Invited talkfrom the Scientific Committee Finding General Hierarchies Beyond BinaryTreesPatrick Thiran (EPFL)
Hierarchical clustering seeks to uncovernested structures in data by constructing a tree of clusters, where deeperlevels reveal finer-grained relationships. Traditional methods, includingtop-down and bottom-up approaches, face two major limitations: (i) Theyalways return a hierarchy, even if none exists, and (ii) they arerestricted to binary trees. In this talk, we address both challenges andfind the hierarchy that provides maximal insight into the relationshipsdefined by a similarity measure: We call it the most informative hierarchy.It is not constrained to binary structures and, when no hierarchicalrelationships exist, it collapses to a star tree. To infer the mostinformative hierarchy, we propose a two-step algorithm that trims thebinary hierarchy obtained by a linkage algorithm, and we show that itrecovers the true hierarchy among clusters of a graph generated by ahierarchical extension of the degree-corrected block model.
Joint workwith Maximilien Dreveton, Daichi Kuroda et Matthias Grossglauser,EPFL.

10:00/10:30

Coffeebreak

10:30/11:00

PhD Elevator Pitch: Alex Pierron(Télécom SudParis) / Tiphaine George (Télécom Paris) / JulienCardinal (Inria) / Luis Muneca Tomas (Nokia Bell Labs / Inria) / Aoyu Pang(Nokia Bell Labs) / Iain Burges (Télécom SudParis) / Hugo Rimlinger(Sorbonne University) / Shu Li (Inria)

11:00/11:45

Lunch atthe cantine + coffee in the inner garden

11:45/13:30

2ndLINCS Survey Towards greener AIsMarc-Olivier Buob (Nokia BellLabs)
This presentation explains how to make AI more eco-friendly.First, we assess the current environmental impact of AI and its futureevolution, more specifically regarding to energy consumption. Secondly,we present tools estimating the energy footprint of an AI. Thirdly, wepresent techniques to mitigate this problem. Finally, we conclude thispresentation with a list of bestpractices.

13:30/14:00

9thLINCS Scientific Highlights Federated learning-based collaborative intrusion detection in highlyheterogeneous environmentsGregory Blanc (Télécom SudParis)
Networks ofthe future, including 5G and Beyond 5G, as well as IoT, are connectingmore and more devices to the Internet, improving the connectivity andincreasing the service offer, at the expense of their exposure tomalicious actors. Although many countermeasures exist, it remains adaunting task tosecure all devices, in particular, when they are owned bythird parties. Monitoring has thus gained importance to assist securityoperators in discovering ongoing threats. Recent works have focused onleveraging machine learning (ML) to automate knowledge acquisition fromlocal data or publiclyavailable datasets, with the latter focusing onattack data and the former on benign data. The quality of such ML-basedintrusion detection system (ML-IDS) depends on the quality or availabilityof the data. Therefore, a collaborative approach may significantly improvethe performance of individual ML-IDSes, provided the data is from similardomains. As local training data cannot be shared for privacy reasons,Federated learning-based IDS (FL-IDS) emerge as a promising solution. A fewscientific locks remain on its true ability to enable knowledge sharing,to work on heterogeneous data or to guarantee the privacy of itsparticipants. In this talk, we will discuss somesolutions.

14:00/14:15

10th LINCS Scientific Highlights Timing advance and Doppler shift estimation in 5G NTN satellitenetworksAshutosh Balakrishnan (Télécom Paris)
Accurate timing advance(TA) computation is critical in 5G non-terrestrial networks (NTN). It isnecessary to compute it accurately to avoid inter user interference in theuplink at the satellite (BS) level. Estimating TA in low earth orbit (LEO)satellite networks is more challenging than in classical terrestrialdeployments due to the larger path loss and high-speed movement ofnon-stationary LEO satellites. Capturing the doppler shift also becomesvery pertinent in such scenarios. The problem becomes more challenging inthe event of the UE being mobile itself. In this talk, we first showcasean extended Kalman filter (EKF) based recursive Bayesian framework toaccurately estimate the TA and Doppler shift in the presence of LEOsatellite-UE joint motion dynamics. The framework first accurately modelsthe joint motion dynamics and then constructs a Jacobian to linearize theinherent non-linearities present in the motion process. Probabilisticinsights are also provided. The proposed framework is also useful when thesatellite and UE clocks are not in sync, with the corresponding clockdrift a function of the measured time difference of arrivals. Our resultsshowcase the efficacy and robustness of the proposed EKF framework toestimate the TA and Doppler shift, even at very high UE speeds. The workis expected to be extremely useful in realizing LEO satellite basednon-terrestrial networks. Further, as a current work, we are working onstatistical characterization of the Doppler shift experienced at the UE. Weshowcase the probability densities of the Doppler shift in a 2D isotropicscenario and the engineering insights through it.

14:15/14:30

Poster session / RefreshmentBreak

14:30/15:15

11th LINCS Scientific Highlights Robustness of Causal Discovery Algorithms: a Testbed Study on NFVSystemsFabio Pianese (Nokia Bell Labs)
We explore the applicability tohigh-speed NFV systems of causal discovery, a framework of statistical andalgorithmic techniques that aims to uncover causal relationships. Thisframework highlights the ‘true’ structure of the processes that lead toobserved outcomes while transcending spurious correlations. Causaldiscovery is crucial in the NFV domain, where introducing new levels ofabstraction in the execution of virtualized services may diminish anobserver’s ability to understand configuration or runtime issues. As adrawback, however, strict assumptions must be established concerning thedata collection and the underlying system behavior. Most causal discoverytechniques have been exercised on synthetic data, which lack thecomplexity and subtlety of real-world data generation processes. In thispaper, we instrument a testbed to allow the controlled deployment andperturbation of NFV topologies and evaluate the algorithms’ robustness,defined as their ability to successfully reconstruct a correctconfiguration from observational and interventional probings. We thenconsider some ramifications of discovery quality for anomalydetection.

15:15/15:30

12h LINCS Scientific Highlights Why Instant-Runoff Voting Is So Resilient to Coalitional Manipulation:Phase Transitions in the Perturbed CultureFrançois Durand (Nokia BellLabs)
Previous studies have shown that Instant-Runoff Voting (IRV) ishighly resistant to coalitional manipulation (CM), though the theoreticalreasons for this remain unclear. To address this gap, we analyze thesusceptibility to CM of three major voting rules—Plurality, Two-RoundSystem, and IRV—within the Perturbed Culture model. Our findings revealthat each rule undergoes a phase transition at a critical value ?_? of theconcentration of preferences: the probability of CM for large electoratesconverges exponentially fast to 1 below ?_? and to 0 above ?_?. Weintroduce the Super Condorcet Winner (SCW), showing that its presence is akey factor of IRV’s resistance to coalitional manipulation, boththeoretically and empirically. Notably, we use this notion to prove thatfor IRV, ?_? = 0, making it resistant to CM with even minimal preferenceconcentration.

15:30/15:45

13h LINCS ScientificHighlights Stochastic Geometry and Dynamical System Analysis of WalkerSatellite ConstellationsFrançois Baccelli (Inria/Télécom Paris)
LowEarth orbit (LEO) and medium Earth orbit (MEO) satellite networks consistof multiple orbits which are populated with many satellites. A widely usedspatial architecture for LEO or MEO satellites is the Walkerconstellation, where the longitudes of orbits are equally spaced and thesatellites are equally spaced along the orbits. In this paper, we developa stochastic geometry model for the Walker constellations. This proposedmodel enables an analysis based on dynamical system theory, which allowsone to address essential structural properties such as periodicity andergodicity. It also enables a stochastic geometry analysis under which wederive the performance of downlink communications of a typical user at agiven latitude, as a function of the key constellationparameters.

15:45/16:00

Public Comment by the LINCSScientific Committee

16:00/16:30

WorkshopClosing

Designing Server Sets for Anycast CDN
2025-07-04 11:00 - 12:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
In recent years, there has been growing interest in theeffective operation of anycast Content Delivery Networks (CDN). Existinganycast CDNs answer the same set of cache servers (CSes) for all contentrequests without considering the geographical distribution of popularity ofcontents. It has also been reported that the appropriateness of theselection of delivery servers decreases as the number of servers assignedto the same IP address increases in anycast delivery. To solve theseproblems, we propose a new anycast distribution method that incorporatesthe spatial locality of the popularity of content. Specifically, wepropose an algorithm that creates multiple CS sets consisting of a smallnumber of CSs and assigns the optimal CS set to each content by minimizingthe number of CSes in the CS set. The algorithm aims to reduce thedispersion of delivery delay by minimizing the number of CSes in the CSset, while covering a wide range of countries. Using a genetic algorithm,we construct CS sets that incorporates spatially biased ASes and verify itseffectiveness through computer simulation. Numerical evaluation resultsshow that the proposed method can effectively cover ab out 80% of requestsof highly popular content with about 15 ASes. It is expected that theproposed method can effectively cover the requirements for most of thecontents with a small number.

Short bio:
Noriaki Kamiyama received hisM.E. and Ph.D. degrees in communications engineering from Osaka Universityin 1994 and 1996, respectively. From 1996 to 1997, he was with theUniversity of Southern California as a visiting researcher. He joined NTTMultimedia Network Laboratories in 1997, and he has been at NTT NetworkTechnology Laboratories by 2016. He was also with the Osaka University asan invited associate professor from 2013 to 2014 and an invited professorin 2015. From 2017, he has been a professor of Fukuoka University. From2021, he is a professor of Ritsumeikan University. He has been engaged inresearch concerning content distribution systems, network design, networkeconomics, traffic measurement and analysis, and traffic engineering. Hereceived the best paper award at the IFIP/IEEE IM 2013. He is a member ofIEEE, ACM, and IEICE.

LINCS PhD Student Day 2025
2025-06-25 09:00 - 18:00
#RegistrationForm
Similar to last year, for those who werethere, this day is entirely dedicated to the PhD Students and Postdocs ofthe lab. It will consist of a morning with elevator pitches, posters, andbrainstorming, followed by a friendly lunch and a team-building activityheld outdoors.

The purpose of this day is to provide participants withan opportunity to present their work, learn about their peers’research, and receive valuable feedback from senior members ofLINCS.

All PhD Students and Postdocs are kindly invited to present botha poster and an elevator pitch.

If you need your poster to be printed,please send it to me no later than June 16, as the printing procedure atTelecom Paris requires a few days and is not under my control.

Thisevent will also serve as practice for those presenting at the upcomingannual workshop in front of the scientific committee, scheduled for July10 & 11.

For the team-building activity, we are still evaluatingoptions, but we truly appreciate the suggestions many of you haveshared.

The proposed lunch and recreational activity will be covered byLINCS.
PROGRAM OVERVIEW

8:45 – 12:00 TEAM BUILDING SESSION: Theprovider OOXYGENE – Jeux d’aventure will welcome you on Wednesday,June 25 at 9:30 AM at the western section of Parc Eugène Chanlon (near47, rue de Corbeville – see attached map).

It will be a fun, dynamicadventure! The goal is to slow down other teams, hide to escape them,find immunity items, or rely on fate—anything goes, as long as yourquest leads you to the legendary treasure before others. Distance: about2.5–3 km.

Dress code: sports shoes, cap, water bottle, and shortsor lightweight trousers. No dedicated parking—you can park in nearbystreets. Suggested team size: up to 7 participants. Please try to mix withpeople you don’t know yet! Note: there are no public restrooms onsite.

12:00 – 13:45 LUNCH: In the hall of Telecom Paris or, weatherpermitting, in the inner garden next to the lecture halls.
13:45OPENING: Speech by LINCS Director Daniel Kofman.
14:00 ELEVATOR PITCHSESSION 1

Alex Pierron (14:00–14:05)
Baptiste Corban(14:05–14:10)
Capucine Barré (14:10–14:15)
Emanuele Mengoli(14:15–14:20)
Alessa Mayer (14:20–14:25)
Daniel Henning(14:25–14:30)
Israa Khaled (14:30–14:35)
Guillaume Nibert(14:35–14:40)
Jorge Mirande (14:40–14:45)
Hugo Rimlinger(14:45–14:50)
Junepyo Jung (14:50–14:55)
Julien Cardinal(14:55–15:00)

15:00 REFRESHMENT BREAK & POSTER SESSION
15:20 ELEVATOR PITCH SESSION 2

Ashutosh Balahrishnan(15:20–15:25)
Ludmila Courtillat-Piazza (15:25–15:30)
Iain Burge(15:30–15:35)
Hakim Ouedraogo (15:35–15:40)
Jules Sintes(15:40–15:45)
Luis Munecas Tomas (15:45–15:50)
Mohamed AmineLegheraba (15:50–15:55)
Rosario Patanè (15:55–16:00)
Tom Boumba(16:00–16:05)
Tiphaine George (16:05–16:10)
Ufuk Bombar(16:10–16:15)

16:15 – 17:00 REFRESHMENT BREAK & POSTERSESSION

Geometric lower bounds for stochastic processing networks withlimited connectivity
2025-06-18 14:00 - 15:00
Abstract:

We consider processing networks where multipledispatchers are connected to single-server queues by a bipartitecompatibility graph, modeling constraints that are common in distributeddata center networks, typical in cloud systems, due to geographic reasonsor data locality issues. We prove lower bounds for the steady-stateoccupancy, i.e., the complementary cumulative distribution of theempirical queue length measure. Our lower bounds are geometric, withratios determined by two flexibility metrics: the average degree of thedispatchers and a novel metric that averages the minimum degree over thecompatible dispatchers across the servers. Using these lower bounds, weestablish that the large scale asymptotic performance of a processingnetwork cannot match that of the classic Power-of-d or JSQ policies unlessthese flexibility metrics approach infinity in this large scalelimit.

Preprint: https://arxiv.org/abs/2505.08974

Speaker: AndresFerragut, https://aferragu.github.io

Writing reactive code in Python
2025-06-06 11:00 - 12:00
It is often stated that “there are 2 hard problems incomputer science: cache invalidation, naming things, and off-by-1errors.” In this talk, we’ll take a shot at addressing an instance ofthe first problem: cache invalidation. More specifically, we consider codein which a number of values are 1- computed based off of other (dynamic)values and 2- cached to avoid recomputing them all the time, and look athow to automate lazy computation, caching, cache invalidation anddependency tracking. This will be designed with the mindset of building alibrary/module which aims to minimize the impact on user code.

Pushing the Boundary for Index Policies: Recent Advances,Challenges and Opportunities
2025-05-28 14:00 - 15:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
Abstract
Many network control problems (e.g., minimizingage-of-information, network slicing, and caching, just to name a fewexamples) can be cast as Markov Decision Processes (MDP). However, as thenetwork size increases, MDP is known to suffer fromcurse-of-dimensionality. Index policies, e.g., the Whittle index, can bea useful tool to decompose an otherwise intractable multi-agent MDP intoper-agent problems, which can then lead to low-complexity, scalable andhighly adaptive solutions. However, the existing theory of Whittle indexstill has severe limitations. First, when the problem of interest isslightly more complex, even verifying Whittle indexability becomes verychallenging. Second, Whittle index cannot be used for systems withmultiple heterogeneous resources. Third, calculating the index can stillincur high overhead. In this talk, we will introduce some recent work thatpushes the boundary for index policies in terms of (i) indexabilityverification, (ii) partial index for multiple resources, and (iii) fastindex-computation. Our goal is to make index policies more easilyapplicable to a larger class of problem settings. We conclude with somediscussions on further challenges and potential opportunities for indexpolicies.
Bio:
Xiaojun Lin received his B.S. from Zhongshan University,Guangzhou, China, in 1994, and his M.S. and Ph.D. degrees from PurdueUniversity, West Lafayette, Indiana, in 2000 and 2005, respectively. Hejoined the faculty of School of Electrical and Computer Engineering atPurdue University in 2005, and became a Professor in 2017. Since June2023, he joined the Department of Information Engineering, The ChineseUniversity of Hong Kong, as a Professor and Global STEM Scholar.
Dr.Lin's research interests are in the analysis, control and learning oflarge and complex networked systems, including both communication networksand cyber-physical systems. He received 2005 best paper of the year awardfrom Journal of Communications and Networks, IEEE INFOCOM 2008 best paperaward, ACM MobiHoc 2021 best paper award, and ACM e-Energy 2022 bestpaper award. He received the NSF CAREER award in 2007. He has served as anAssociate Editor for IEEE/ACM Transactions on Networking, as an AreaEditor for (Elsevier) Computer Networks journal, and as a Guest Editor for(Elsevier) Ad Hoc Networks journal. Dr. Lin is a Fellow of IEEE.

Home Assistant : a newbie’s impressions
2025-05-23 11:00 - 12:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
Home IoT deployments including multi-vendor appliances andcloud services are becoming commonplace. In this talk, I relate my firstimpressions of Home Assistant, an open-source software project driven by acommunity of home automation enthusiasts which is approaching maturityafter 12 years of development. I describe my experience setting up a basesystem at home, learning about ESP32 microcontrollers and self-hostedvoice assistants, and then taking Home Assistant to work as a convenientbase platform for voice-controlled, LLM powered demos.

Resilient and Efficient Decentralized Learning
2025-05-07 14:00 - 15:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
Decentralized learning enhances privacy, scalability, andfault tolerance by distributing data and computation across nodes. Apopular approach is Federated learning, which relies on a centralaggregator, yet faces challenges such as server vulnerabilities,scalability issues, privacy risks and most importantly, the single pointof failure. Alternatively Gossip Learning offers fully decentralizationthrough peer-to-peer exchanges of model updates, ensuring robustness andprivacy, at the price of slower model convergence. In our work, weintroduce a novel decentralized learning framework called HEAL. Byexploiting an innovative topology based on dynamic hubs, HEAL deliversperformance similar to that of Federated learning, but with thedecentralization and resilience of Gossip learning.

Joint LINCS / Sorbonne University / Grifin Workshop on AI,Networks & Cybersecurity
2025-04-22 09:00 - 2025-04-23 18:30 | Sorbonne University - Campus Les Cordeliers, 15, rue del'École-de-médecine, Paris, 75006, France
We are pleased to announce the upcoming Joint LINCS / SorbonneUniversity / ANR - Grifin Workshop on AI, Networks & Cybersecurity,which will take place on April 22 & 23, 2025, in SorbonneUniversity, Les Cordeliers campus, 15 rue de l'École-de-médecine,75006 Paris.
Registration

Registration is mandatory.
Are you a PhDStudent or a Postdoc and want to be part of it? You can submit your posterand give an elevator pitch! Fill in the blanks.

Speakers
April 22 - Day1

9h30-10h15: Accueil/Café
10h15-10h30: Introduction(presentation of LINCS, GRIFIN, and program)
10h30-11h00: "How datasetquality shapes resistance to data poisoning", by Katarzyna Wasielewska
11h00-11h30: "Network Data Augmentation Through Protocol-ConstrainedTraffic Generation" , by Francesco Bronzino
11h30-12h30: "AI for theDetection and Mitigation of Cyberattacks" , by Erol Gelenbe
12h30-14h00: Lunch
14h00-14h30: Elevator Pitch

"Cybersecurityimpact of AI Optimization in B5G networks", by Alex Pierron
"PrivacyBenchmarking of IDS with FREIDA", by Solayman Ayoubi
"MetaLore:Learning to Orchestrate Communication and Computational Resources forMetaverse Synchronization" by Ohri Elif
"Studying Gossip Learning" byAlexandre Pham

14h30-15h15: Poster around coffee
15h15-16h15:"Collaborative Learning attacks and defenses", by Alice Héliou
16h15-17h15: "A Small Tutorial on Byzantine-Robustness - FederatedLearning with adversarial nodes", by Rafael Pinot

April 23 - Day 2

09h30-10h30: "Securing the Future: Understanding Attacks on AI-DrivenNetwork Management", by Valeria Loscri
10h30-11h00: Pause café
11h00-11h30: "Can we still learn something from Darknet traffic?", byJérôme François
11h30-12h00: "Automating security management for thecyberspace", by Rémi Badonnel
12h00-12h30: "Advanced Network Fuzzingfor Networked System Testing" , by W. Mallouli
12h30-14h00: Lunch
14h00-15h00: Elevator pitches

"Improving anonymous securecommunications on the Internet", by Guillaume Nibert
"HEAL: Resilientand Self-* Hub-based Learning" by Mohamed Amine Legheraba
"DDoSMitigation while Preserving QoS: A Deep Reinforcement Learning-BasedApproach" by Shurok Khozam
"A genetic algorithm approach to flightoptimization", by Massinissa Tighilt

14h30-15h30: Poster aroundcoffee
15h30-16h00: "Data quality: the key to automation", by JoséCamacho
16h00-16h30: "Managing the cloud-to-edge continuum underuncertainty via AI methods with performance guarantees" by Andrea Araldo
16:30-16:45: Conclusion

Talks
Andrea Araldo (Télécom SudParis)
"Managing the cloud-to-edge continuum under uncertainty via AImethods with performance guarantees"

There is a long tradition ofnetwork management methods based on a precise model of the network and ofthe load. However, in practical situations it is impossible to build sucha model, mainly because the load is uncertain and not known in advance. AImethods can overcome this model/reality gap, by continuously adjustingdecisions based on streams of monitoring observations.

In this talk, Iwill show how we applied AI to manage the cloud-to-edge continuum,focusing on the following decisions: pricing, placement of multiple“versions” of machine learning models, resource allocation. Themethods we applied are Hidden Parameter Markov Decision Processes,Model-Based QLearning, Online Learning. I will show that, despite theuncertainty on the input load, we are able to provide analytic guaranteeson the worst-case performance or on the average performance. Suchguarantees are important to foster the applicability of AI algorithms,which is often hindered by their black-box nature.
Rémi Badonnel(Loria)
"Automating security management for the cyberspace"

TheInternet has become a great integration platform capable of efficientlyinterconnecting billions of entities, from simple sensors to large datacenters. This platform provides access to multiple hardware and virtualizedresources (servers, networking, storage, applications, connectedobjects) ranging from cloud computing to Internet-of-Thingsinfrastructures. From these resources that may be hosted and distributedamongst different providers and tenants, the building and operation ofcomplex and value-added networked systems is enabled. These systems arehowever exposed to a large variety of security attacks, that are alsogaining in sophistication and coordination.

In that context, weinvestigate challenges about automating security management for thecyber-space, through the development of new monitoring and configurationsolutions tailored to these systems.
Francesco Bronzino (ENSLyon)
"Network Data Augmentation Through Protocol-Constrained TrafficGeneration"

Traffic Generation Datasets of labeled network traces areessential for a multitude of machine learning (ML) tasks in networking,yet their availability is hindered by privacy and maintenance concerns,such as data staleness. To overcome this limitation, synthetic networktraces can often augment existing datasets. Unfortunately, currentsynthetic trace generation methods, which typically produce onlyaggregated flow statistics or a few selected packet attributes, do notalways suffice, especially when model training relies on having featuresthat are only available from packet traces. This shortfall manifests insub-optimal performance on ML tasks when employed for dataaugmentation.

In this talk, we discuss our ongoing work on developinggenerative techniques to augment network datasets for a variety of tasks,from traffic classification to QoE measurement. First, we presentNetDiffusion, a tool that uses a finely-tuned, controlled variant of aStable Diffusion model to generate synthetic network traffic that is highfidelity and conforms to protocol specifications. Our evaluationdemonstrates that packet captures generated from NetDiffusion can achievehigher statistical similarity to real data and improved ML modelperformance than current state-of-the-art approaches (e.g., GAN-basedapproaches). Second, we discuss how this approach is more suited tosupport common network analysis tasks, as well as our ongoing effortssolving NetDiffusion’s limitations.
José Camacho (University ofGranada)
"Data quality: the key to automation"

Data quality is acentral topic often neglected in Data Science. With the current interest inAI and Deep Learning, some data scientists believe that creating asuccessful data analysis pipeline is simply a matter of finding a suitableAI model, disregarding the possibility that the data itself may be poor.This view conflicts with the old Data Science mantra, “Garbage In,Garbage Out,” which dates back to the origins of computational science.Can you predict when you will suffer from cancer, if at all, based onyour eye color? Probably not. Can you detect a cybersecurity attack onlyfrom traffic traces? Well, maybe, but that might not be sufficient.

Inmy experience, many data pipelines succeed only after proper experimentaldesign (that controls data generation), data visualization andunderstanding, filtering, cleaning, transformation, and data fusionfrom complementary sources. In my experience, again, 75% of a datascientist’s traditional work is often devoted to data preparation, whichis quite complicated to automate.

In this talk, I will discuss some ofthe pitfalls we face when designing an AI pipeline, drawing examples fromareas other than autonomic networks, and I will make the association withchallenges for AI automation in network management.
Jérôme François(University of Luxembourg)
"Can we still learn something from Darknettraffic?"

Darknet allows to collect supposed malicious traffic byexposing entire IP subnetworks into the wild. They have been used for morethan two decades for monitoring large threats over Internet such as DDoS,botnets or probing activities. Their passive nature limits the knowledgethat can be gathered beyond these large phenomena.

Using the Darknet ofthe High Security Lab in Inria Nancy, we have performed several analysisover the years showing that Darknet can still be used to anticipate somethreats or extract relevant knowledge to perform traffic analysis in othernetworks. We'll briefly these different approaches and showing limitationsand remaining opportunities.
Erol Gelenbe (Institute of Theoretical &Applied Informatics, Polish Academy of Sciences, King’s CollegeLondon & CNRS I3S, Université Côte d’Azur, Nice, France)
AIfor the Detection and Mitigation of Cyberattacks

Gateway Servers forthe Internet of Things are used in critical application areas such asindustrial IoT, the Internet of Vehicles and health monitoring. Thus theymust meet stringent Security and Quality of Service (QoS) requirements,offering cyber-attack protection with fast response and minimal loss ofbenign data. Therefore, protecting these systems with effective trafficshaping, accurate Attack Detection (AD) and Mitigation mechanisms isvital.

We will first demonstrate online and federated learningtechniques that accurately detect attacks. Measurements of packet floodsthat convey a cyber-attack will be shown to impair the QoS at the Gatewaysand impede their capability to carry out AD. Using Queueing Theory, andexperimental measurements, we show that the novel traffic shaping methodQDTP ensures that a Gateway can allow AD to operate promptly during anattack. A new Adaptive Attack Mitigation (AAM) system is then introduced tosample the incoming packet stream, determine whether an attack isongoing, and dynamically drop batches of packets at the input to reducethe effects of the attack, and minimize the AD overhead and the cost oflost benign packets.
Alice Héliou (Thales)
"Collaborative Learningattacks and defenses"

Collaborative learning allows to work togetherto train better models without directly exchanging data. Although verypowerful, applying secure, robust, and ethical machine learningapproaches in a collaborative setting proves to be more complex thanexpected.

This talk will present our past, current, and future work onattacks and defenses applied to collaborative learning.
Valeria Loscri(Inria)
"Securing the Future: Understanding Attacks on AI-Driven NetworkManagement"

In the context of network management, the integration ofArtificial Intelligence (AI) and Machine Learning (ML) is gainingmomentum, permitting automation and optimization. However, integratingAI/ML into network management, changes the security landscape. From oneside, security can be improved, by enhancing threat and anomalydetection, by enabling a more rapid response to threats. Moreover,vulnerabilities can be predicted and patches can be considered to avoid theexploitation of such vulnerabilities to convey impacting attacks. Fromanother side, AI/ML-based approaches are prone to different types ofattacks, ranging from adversarial attacks, data privacy andconfidentiality and model drift. These points need to be carefullyconsidered and to mitigate security risks some key aspects related tosecure AI/ML training and deployment and adversarial defense mechanism needto be explicitly considered.

In this talk, we will review the benefitsof AI/ML in network management as well as their dark side when employed innetwork management.
Wissam Mallouli (Montimage)
"Advanced Network Fuzzingfor Networked System Testing"

In this lecture, we will explore thetopic of network fuzzing, a powerful technique for networked systemtesting, used to identify both software bugs and security vulnerabilitiesthat may affect the reliability and robustness of networked applications.Network fuzzing allows automatically generating and injecting malformed orunexpected inputs into network communications leading to potentialcrashes, unexpected behaviors, or security breaches.

This session willprovide both theoretical insights and practical demonstrations using theMontimage Network Fuzzer, an open-source tool designed to enhanceautomated testing.
Rafael Pinot (Sorbonne University)
"A Small Tutorialon Byzantine-Robustness - Federated Learning with adversarial nodes"

Thevast amount of data collected every day, combined with the increasingcomplexity of machine learning models, has led to the emergence ofdistributed learning schemes. In the now classical Federated learningarchitecture, the learning procedure consists of multiple data owners (orclients) collaborating to build a global model with the help of a centralentity (the server), typically using a distributed variant of SGD.Nevertheless, this algorithm is vulnerable to ” misbehaving ” clientsthat could (either intentionally or inadvertently) sabotage the learning bysending arbitrarily bad gradients to the server. These clients are commonlyreferred to as Byzantine and can model very versatile behaviors going fromcrashing machines in a datacenter to colluding bots attempting to biase theoutcome of a poll on the internet.

The purpose of this talk is topresent a small introduction the emerging topic of Byzantine Robustness.Essentially, the goal is to enhance distributed optimization algorithms,such as distributed SGD, in a way that guarantees convergence despite thepresence of some Byzantine clients. We will take the time to present thesetting and review some recent results as well as open problems in thecommunity.
Katarzyna Wasielewska (University of Granada)
"How datasetquality shapes resistance to data poisoning"

Data poisoning attackscan introduce false data into the training dataset, causing ML models tomake incorrect and misleading decisions. These types of attacks exploitweaknesses in datasets.

In this talk, we will try to answer thequestion of whether dataset quality is the first line of defense againstdata poisoning in AI systems.

Elevator Pitch Session
Solayman Ayoubi(Sorbonne University)
"Privacy Benchmarking of IDS with FREIDA"

Ohri Elif (Sorbonne University)
"MetaLore: Learning to OrchestrateCommunication and Computational Resources for Metaverse Synchronization"

Shurok Khozam (Telecom SudParis)
"HEAL: DDoS Mitigation whilePreserving QoS: A Deep Reinforcement Learning-Based Approach"

MohamedAmine Legheraba (Sorbonne University)
"HEAL: Resilient and Self-*Hub-based Learning"

Guillaume Nibert (SorbonneUniversity)
"Improving anonymous secure communications on the Internet"

Alexandre Pham (Sorbonne University)
"Studying Gossip Learning"

Alex Pierron (Telecom SudParis)
"Cybersecurity impact of AIOptimization in B5G networks"

Massinissa Tighilt (SorbonneUniversity)
"A genetic algorithm approach to flight optimization"

Optimally deceiving a learning leader in Stackelberg games
2025-04-11 11:00 - 12:00 | Zoom + Amphi 5 chez Télécom-Paris, 19 place Marguerite Perey,Palaiseau, 91120, France
Andrea Araldo will present the setting and some interestingproofs contained in the NeurIPS 2020 paper "Optimally deceiving a learningleader in Stackelberg games".

To ground the discussion in a concretecontext, I will discuss the paper is a demand-side managementscenario.

The regulator (e.g., the government - acting as a leader)proposes incentives to users (followers), to convince them to switch tosustainable alternatives (e.g., when choosing products or services). Theregulator optimizes such incentives with the goal of maximizing socialwelfare. Users choose alternatives so as to maximize their utilityfunction. The regulator has only partial information about the users' trueutility function. Therefore, users can can manipulate the regulator, bychoosing alternatives according to a "fake" utility function, differentthan their true one. By doing so, users can mislead the regulator andreceive more favourable incentives than they would deserve. The papershows analytically under which conditions users can basically mislead theregulator as much as they want.

Data Compression with Locality Properties
2025-04-09 14:00 - 15:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
Traditional compression schemes typically require decompressingthe entire compressed archive to access a single bit. Similarly, updatinga single bit requires re-encoding the entire archive. In this talk, I willpresent recent advances in compression with locality, where the goal is tominimize the number of bits that need to be accessed or modified whendecoding or updating a single bit. Sample questions we will addressinclude: What is the minimum number of bits that must be read or changed todecode or update a single bit? How does this minimum change whencompression is handled in a distributed fashion (à la Slepian-Wolf)? Andis it possible to decode a single bit with perfect privacy?

Optimisation of energy-aware DNS server allocation by Wang & Rose
2025-04-04 11:00 - 12:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
The lecture will focus on the paper written by Zheng Wang andScott Rose, which deals with the allocation of DNS servers by takingenergy consumption into account while maintaining a satisfying quality ofservice. The authors have devised an analytical mathematical optimisationmodel that takes into account network and query processing delays, andenergy costs, in order to minimise revenue losses without affectingquality of service. We will examine the proposed model and optimisationstrategy, as well as the results they obtained.

Green digitalization ?
2025-04-02 14:00 - 15:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
We provide an overview on Information and CommunicationTechnologies comsumption in recent years by conducting different types ofanalysis. We evoke the rebound effect related to Green IT as well as theenablement effect related to ICT for Green. We also show on some simpleexamples how LCA (Life Cycle Assesment) can be taken into account instandard performance analysis.

Responsible digital developments in research and education: wheredo we start?
2025-03-26 14:00 - 15:00 | Amphi 2, 19 place Marguerite Perey, Palaiseau, France
Several recent initiatives have proposed new directions forresearch practices and their operations in the computer science community,from updated codes of conduct that clarify the use of AI-assisted tools tothe inclusion of ethical statements and the organisation of working groupson the environmental footprint of digitalisation. In this talk, we willdiscuss what framework(s) are needed to help describe the sense ofengagement and responsibilities to which the practitioner of acomputing-related area may be confronted, and guide one to think about theincidence of technical realisations beyond techno-centric contributions. Wewill share examples from current research projects and teaching practicesto illustrate some concrete scenarios.

Incentives in large-scale demand-side flexibility management insmart energy grids: the RESONANCE approach
2025-03-21 11:00 - 12:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
The increased contribution of renewable energy sources toenergy production has led to increased variability and lower levels ofcontrolability of energy generation. On the hand, the electrification oftransportation and heating systems and their integration to smart energygrids allows for higher levels of demand-side flexibility, which can playa key role in achieving the desired balance of such grids. To this end,Horizon Europe project RESONANCE aims to facilitate the management offlexibility at a large scale by developing and testing in pilots its ownsoftware architecture.

In the first part of this talk, I will overviewthe technical approach of project RESONANCE, with emphasis on the use ofincentives for provision of flexibility by consumers. In the second part(*), I will present a model where a population of consumers has tocollectively achieve a particular total volume of flexibility but thecontribution of each consumer to this target is not directly measurable.This case is modeled as the formation of the public good; theanalysis reveals that offering the proper incentives to users can have aconsiderable positive effect in reaching the flexibility target.

(*)Joint work with Thanasis Papaioannou (Professor at National KapodistrianUniversity of Athens – Research Associate of STEcon-AUEBgroup).

Bio :

George D. Stamoulis is a Professor in theDepartment of Informatics, of Athens University of Economics andBusiness (AUEB), and Head of the Services, Technologies and Economics(STEcon - http://stecon.cs.aueb.gr/) research group.

He received theDiploma in Electrical Engineering (1987, with highest honors) from theNational Technical University of Athens, Greece, and the MS (1988) andPhD (1991) degrees in Electrical Engineering from the MassachusettsInstitute of Technology, Cambridge, Massachusetts, USA. His researchinterests are in economic and business models for networks, clouds, smartenergy grids and blockchain environments, demand response and flexibilitymanagement in smart energy grids, telecommunications and powerregulation, auction mechanisms for scarce goods, and reputationmechanisms for electronic environments. He has coordinated theparticipation of the STEcon Group of AUEB in several successful FP7, H2020and Horizon Europe projects, including 6 projects in progress in the areasof smart grids, blockchains and 5G/6G telecoms. He has published over 100articles in high-quality scientific journals (IEEE Transactions on Controlof Networked Systems, IEEE/ACM Transactions on Networks, IEEETransactions on Communications, Computer Networks, Journal of the ACMetc.) and in top scientific conferences (such as INFOCOM, ITC, ACMSIGMETRICS, CCGRID, e- Energy, SmartGridComm.) He has also collaboratedwith Greek Regulatory Authorities for Telecoms and Power on auction designand other regulatory issues and with Greek telecom companies on servicepricing, data analysis etc.

Cybersecurity and Cyber Resilience of Complex Systems
2025-03-19 14:00 - 15:00 | Amphi 3, 19 Place Marguerite Perey, Palaiseau, France
Thanks to technological advancements, critical infrastructuresintegrate many smart technologies and become highly connected to the cyberworld. This is especially true for Cyber-Physical Systems (CPSs), whichcombine hardware and software components. Despite the advantages of smartinfrastructures, they remain vulnerable to cyber threats and adversarialevents such as cyber-attacks. This talk focuses on quantifying the cyberresilience of complex systems modeled with a multi-layering approach. As ause case, we consider the Secure Water Treatment System (SWaT)testbed.

Deployment of an end to end 4G/5G testbed based on a singlecomputer
2025-03-14 11:00 - 12:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
This presentation will present the deployment and installationprocedure of a 4G/5G testbded on single computer.

This testbed is basedon SRSRAN open source 4G/5G software and relies on ZMQ socket interface forcommunication between different network nodes. The major networkinterfaces are provided, including the air the interface. A software UE,potentially connected to a smart card reader, with a programmable SIMcard, can also be used to investigate security procedures between UE andSIM card.

This platform makes it possible to investigate radio and corenetwork procedures.

By using Gnuradio software, and connecting it tothe simulator through ZMQ socket interface, it is possible to do a widerange of processing on information exchanges on the air interface(simulation of a channel, simulation of jamming, ...)

Python tricks for discrete-event simulation
2025-03-07 11:00 - 12:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
In this presentation, I will introduce discrete-eventsimulation, provide a minimal Python implementation, and then showcasehow we can use certain Python features (decorators, generator functions,etc.) to improve upon this implementation.

Discrete-event-simulation.pdf

Orchestration of AI-based Applications in Heterogeneous andDistributed Computing Systems
2025-03-05 14:00 - 15:00 | Amphi 2, 19 place Marguerite Perey, Palaiseau, France
Today, distributed systems are increasingly needed to supportdistributed applications that involve machine learning (ML) operations forboth service providers and end users. These operations include training MLmodels across distributed infrastructures and deploying them over thenetwork for inference. While the training of these models, whethercentralized or decentralized, has been extensively studied, theorchestration of inference models across the network remains largelyunexamined. To ensure high-quality applications run effectively over theseinfrastructures, orchestration presents several challenges, including i)the interaction of models with other software components distributed acrossthe network; ii) deploying such components on heterogeneous andcomputationally limited resources; and iii) adapting orchestrationstrategies to continuous changes in the data fed into these models. Thisseminar aims at exploring and discussing these methodological andtechnological challenges in the design of algorithmic solution fororchestrating AI-based applications within distributed computingsystems.

Short Bio. Francescomaria Faticanti is a postdoctoralresearcher at ENS de Lyon, France. From January 2022 to August 2023 he wasa postdcotoral researcher at Inria Sophia Antipolis, France. He receivedthe PhD in Information and Communication Technology from University ofTrento and Fondazione Bruno Kessler (FBK), Italy, in November 2021. Heserves as reviewer, and member of the TPC, for several internationalconferences and journals in the field of Networking and DistributedSystems. His research interests include algorithms for resource allocationin distributed systems, distributed ML and combinatorial optimization.

Communication Complexity of Common Voting Rules
2025-02-28 11:00 - 12:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
In this presentation, I will discuss the paper CommunicationComplexity of Common Voting Rules [1], which examines how many bits mustbe exchanged to elicit voters’ preferences and determine the outcome ofan election, depending on the voting rule used. I begin by presenting theconcept of deterministic and non-deterministic communication complexity,followed by an introduction of the main voting rules analyzed in the paper.I then explain the paper’s main results, which primarily establish lowerand upper bounds on the communication complexity of several well-knownvoting rules, such as plurality, Borda count, and the Condorcet rule.This talk aims to provide a deeper understanding of the communicationrequirements of different voting systems.

References
[1] VincentConitzer and Tuomas Sandholm. Communication complexity of common votingrules. In Proceedings of the 6th ACM conference on Electronic commerce,pages 78–87,2005.

https://www.irif.fr/~mdr/cours2-2019.pdf

FjORD: Fair and Accurate Federated Learning under heterogeneoustargets with Ordered Dropout
2025-02-21 11:00 - 12:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
Federated Learning (FL) has been gaining significant tractionacross different ML tasks, ranging from vision to keyboard predictions. Inlarge-scale deployments, client heterogeneity is a fact and constitutes aprimary problem for fairness, training performance and accuracy. Althoughsignificant efforts have been made into tackling statistical dataheterogeneity, the diversity in the processing capabilities and networkbandwidth of clients, termed as system heterogeneity, has remainedlargely unexplored. Current solutions either disregard a large portion ofavailable devices or set a uniform limit on the model's capacity,restricted by the least capable participants. This work introduces OrderedDropout, a mechanism that achieves an ordered, nested representation ofknowledge in deep neural networks (DNNs) and enables the extraction oflower footprint submodels without the need of retraining. It further showsthat for linear maps, Ordered Dropout is equivalent to SVD. Thistechnique, along with a self-distillation methodology, is applied in therealm of FL in a framework called FjORD. FjORD alleviates the problem ofclient system heterogeneity by tailoring the model width to the client'scapabilities. Extensive evaluation on both CNNs and RNNs across diversemodalities shows that FjORD consistently leads to significant performancegains over state-of-the-art baselines, while maintaining its nestedstructure. In this seminar, we discuss this paper and we highlight some ofits features and how it relates to my current work.

AI for the Detection and Mitigation of Cyberattacks
2025-02-19 14:00 - 15:00 | Amphi 3, 19 Place Marguerite Perey, Palaiseau, France
Gateway Servers for the Internet of Things, including criticalapplication areas such as the Internet of Vehicles and health monitoring,must meet stringent Security and Quality of Service (QoS) requirements,offering cyberattack protection with fast response and minimal loss ofbenign data. Therefore, it is vital to protect these systems withadequate Attack Detection (AD) and Mitigation mechanisms.

We will firstdemonstrate online as well as federated learning techniques that accuratelydetect attacks. Measurements of packet floods that convey a cyberattackwill also be shown to impair the QoS at the Gateways and impede theircapability to carry out AD. Novel traffic shaping methods to ensure that aGateway can allow AD to operate promptly during an attack will bediscussed. A new Adaptive Attack Mitigation (AAM) system will beintroduced to sample the incoming packet stream, determine whether theattack is ongoing, dynamically drop batches of packets at the input toreduce the effects of the attack and minimize the AD overhead and the costof lost benign packets.

Speaker’s Bio: Erol Gelenbe MAE’05FIEEE’86 FACM’02 FIFIP’19 FRSA’24 FRSS’20 FIET’03 graduatedfrom METU (Ankara), received his PhD from the Tandon School ofEngineering, New York University and the State Doctorate in MathematicalSciences from the Sorbonne (Paris). An expert on System PerformanceEvaluation as well as Machine Learning, he invented the Random NeuralNetwork and the eponymous G-Networks, developed methods such as diffusionapproximations, and derived some of the first analytical results regardingthe performance of communication protocols. Currently a Professor at theInstitute of Theoretical and Applied Informatics, Polish Academy ofSciences, he graduated over 90 PhDs during his professorships in Belgium,France, the USA, the UK and Poland. For his services to research andhigher education, he received the honours of Chevalier de la Légiond’Honneur, Commander of Merit of France and Italy, Commander of theOrder of the Crown of Belgium, and Officer of the Order of Merit ofPoland, and was elected Fellow of the National Academy of Technologies ofFrance, of the Science Academies of Belgium, Poland and Turkey, HonoraryFellow of the Hungarian Academy of Sciences (Budapest) and of the IslamicAcademy of Sciences (Amman). He chairs the Informatics Section of AcademiaEuropaea and won the ACM SIGMETRICS’08 Life-Time Award for his work onsystem performance modelling and analysis, the Mustafa Award’17 for hisinvention of G-Networks, the Grand Prix France-Télécom’96 (FrenchAcademy of Sciences) for his research on stochastic networks, the IETInnovation Award (Oliver Lodge Medal’10) and other prizes.

Master Python Efficiency with itertools and joblib
2025-02-14 11:00 - 12:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
This Python programming tutorial is designed for intermediatelearners who want to optimize their code for performance, scalability,and elegance using two powerful libraries: itertools (for efficientiteration) and joblib (for parallel computing and caching). Whetheryou’re working with large datasets, complex simulations, or machinelearning workflows, this tutorial will equip you with tools to writefaster, cleaner, and more memory-efficient code.

How can alpha-information theory formally prove that your sensitivecircuits are protected against side-channel attacks?
2025-02-12 14:00 - 15:00 | Amphi 3, 19 Place Marguerite Perey, Palaiseau, France
Cryptographic algorithms are ubiquitous in our digital society.Principles (such as Kerckhoffs’) and mathematical techniques for securingdata against cryptanalysis are well established, even with future quantumcomputers: the best attacks of this type are essentially brute force,which takes several times the age of the universe.

However, one realthreat is that algorithm implementations are vulnerable to side-channelattacks, that exploit sensitive information leaks to recover the secret ina “divide and conquer” approach. Some attacks only require a fewqueries (leakage measurements). Thus, the question is not whether you aresecure or not, since it is only a matter of time. The question is how muchyou can be secure, e.g. with a protected implementation that use datamasking. For that, we need a formal evaluation.

In this talk, Ipresent such a formal evaluation using alpha-information theory, based onRényi alpha-divergence and alpha-entropy, and Sibson’salpha-information. The parameter alpha can be positive or negative, andthe limiting case alpha = minus infinity is related to the important notionof Doeblin coefficient, which can be used to reduce the noisy leakagemodel to a random probing model. Fano and data processing inequalities, aswell as Mrs. Gerber’s lemma in the case of additive masking, are used toestablish lower bounds on the number of queries that any attacker has tomake to achieve a given level of success. In this way, it is possible tobe proactive, for example with ephemeral keys, to maintain the securityof an implementation.

Bio: Olivier Rioul(https://perso.telecom-paristech.fr/rioul/) is full Professor at theDepartment of Communication and Electronics at Télécom Paris, InstitutPolytechnique de Paris, France. He graduated from École Polytechnique andfrom École Nationale Supérieure des Télécommunications, Paris,France, where he obtained his PhD degree. His research interests are inapplied mathematics and include various, sometimes unconventional,applications of information theory such as inequalities in statistics,hardware security, and experimental psychology. He has been teachinginformation theory and statistics at various universities for twenty yearsand has published a textbook which has become a classical French referencein the field.

Particle filter based statistical inference for positioning andtracking applications
2025-02-07 11:00 - 12:00 | Amphi 2, 19 place Marguerite Perey, Palaiseau, France
The lecture will provide a comprehensive summary of statisticalinference using particle filters for positioning and tracking applications.The lecture will cover the motivation behind developing such frameworks,the underlying motion and measurement models, assumptions, and theBayesian approach towards solving such an estimation problem. The talk willalso highlight the importance of linearity, Gaussian, and Markovianassumptions, enabling a tractable solution framework also popularly termedas Kalman filter (KF). Insights will be provided into discrete time andcontinuous time KFs, including the steady state stability conditions.Further, to deal with non-linear systems, the talk with discuss thelinearization based extended Kalman filter.

Reference: Niclas Bergman,"Recursive Bayesian Estimation Navigation and Tracking Applications",Department of Electrical Engineering Linkoping University, Sweden

The RESTART Project: focus on Network Programmability andOrchestration
2025-02-07 10:00 - 10:45 | Amphi 2, 19 place Marguerite Perey, Palaiseau, France
In the last decade, software has been playing an increasinglyrelevant role in communication networks, bringing advanced programmabilityfeatures to network infrastructure management, and enabling the adoptionof solutions and technologies typical of the cloud computing paradigm. Allthis led to what is nowadays called “Network Softwarization.” In theseminar we will showcase the evolution of modern network infrastructurestoward Network Softwarization, discussing the main concepts andtechnologies that enabled the emerging network programmability andorchestration paradigms. Then, we will explore the data models employed bycommon orchestration platforms (e.g., OpenSource MANO and Kubernetes) andshow how services and applications can be defined. In the same context, wewill survey some monitoring tools and techniques to export the currentrelevant metrics from the system to the orchestration platform of choice.Finally, we will show how these paradigms are already integrated into thecurrent generation of mobile networks.

Bio: Walter Cerroni (SeniorMember, IEEE) is an Associate Professor of communication networks with theUniversity of Bologna, Italy. He coauthored more than 150 articlespublished in the most renowned international journals, magazines, andconference proceedings. His recent research interests focused on multipleaspects of control, management and orchestration of communication networkinfrastructures, including software-defined networking, network functionvirtualization, multi-access edge computing, fog computing, servicefunction chaining, intent-based networking systems. He serves/served asSeries Editor for the IEEE Communications Magazine, Associate Editor forthe IEEE Communications Letters, and General / Technical Program Co-Chairfor IEEE-sponsored international workshops and conferences. He is alsoserving as Steering Committee Chair of the IEEE NetSoft conference and asChair of the Transmission, Access, and Optical Systems (TAOS) TechnicalCommittee of the IEEE Communications Society.

A functioning 5G core network deployed on top of a standardKubernetes cluster
2025-02-05 01:30 - 03:00 | Amphi 7, 19 Place Marguerite Perey, Palaiseau, France
In this seminar, we will show how to deploy a functioning 5Gcore network on top of a standard Kubernetes cluster. This talk will startby presenting how Kubernetes applications could be shipped with Helm,explaining the concepts of Helm templates and Helm charts. After that, aHelm chart of an open-source distribution of a 5G core network will beemployed to show how we can customize the setup with our desired 5G networkfunctions configuration.
Bio: Davide Borsatti (Member, IEEE) received hisB.S., M.S., and Ph.D. in Electronics, Telecommunications, andInformation Technologies Engineering from the University of Bologna,Italy, in 2016, 2018 and 2022, respectively. He is currently anAssistant Professor in the Department of Electrical, Electronic, andInformation Engineering "Guglielmo Marconi" at the University of Bologna.His research interests include NFV, SDN, intent-based networking, MEC,and 5G network slicing.

Enhancing Network Efficiency with eBPF/XDP Technology
2025-01-31 11:00 - 12:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
eBPF (Extended Berkeley Packet Filter) and XDP (eXpress DataPath) have revolutionized the way we interact with the Linux kernel,enabling developers to run custom, high-performance programs directly inthe kernel space without requiring kernel modifications. These technologieshave opened up new possibilities in observability, security, and networkoptimization, particularly in environments where low latency and highthroughput are critical. In this talk, we will explore how eBPF and XDPprovide powerful tools to address the challenges of modern networking. Iwill demonstrate three practical examples: tracking kernel functionexecution time, optimizing socket communication within the host, andimplementing high-performance packet filtering at the XDP layer.

Quantum advantage in distributed computing
2025-01-22 14:00 - 15:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
In recent years many advances have been made in the field ofquantum networks and even bigger improvements are expected in theforeseeable future: tasks are no longer processed by a centraladministrator, but rather tackled in distributed networks with manyinterconnected processing units. To achieve that goal, a lot more carewill have to be employed to analyse and overcome the technical difficultiesthat accompany such advances, in particular latency issues. As such,reducing the communication with each other that independent processingunits require is crucial to the viability of any protocol that we hope toimplement. In this talk, we will present and discuss our recent paper[arXiv:2411.03240v1], where we show that considering quantum strategies todistributed problems can greatly improve the communication cost of atask.

Bio: Isadora is a postdoc at PHIQuS, located at InriaParis-Saclay, under the supervision of Marc-Olivier Renou. She did her PhDin CBPF - Brazil on quantum information theory.

Exploiting Partial System Knowledge in Reinforcement Learning forAdmission Control and Electricity Storage Optimization
2025-01-17 14:00 - 17:00 | Inria Paris, 48 rue Barrault, Paris, 75013, France
This thesis exploits partial system knowledge to design moreefficient reinforcement learning (RL) algorithms for three problems:admission control (1), electricity storage optimization (2), and theacceleration of bias function computation (3).

For (1), the system ismodeled as an M/M/c/S queue with m job classes. We propose a model-basedalgorithm, named UCRL-AC, with a finite-time regret bound dominated byO(S\log T + \sqrt{mT \log T}), where T is the total running time.UCRL-AC exploits the queuing structure by learning the arrivalrates.

For (2), we design an RL algorithm that minimizes energy anddemand charges by controlling a battery. The knowledge of the batterydynamics allows an efficient offline exploration, which enables fasttraining with minimal data. The algorithm is tested on real-worlddata.

For (3), we show that for a fixed policy, the bias functioncomputation can be accelerated through the knowledge of eigenvalues of thetransition probability matrix.

Composition du jury:

UrtziAyesta, IRIT (rapporteur)
Giovanni Neglia, Centre Inria d'UniversitéCôte d'Azur (rapporteur)
Johanne Cohen, LISN - UniversitéParis-Saclay (examinatrice)
Bruno Gaujal, Inria Grenoble(examinateur)
Alain Jean-Marie, Inria Montpellier (examinateur)
Lorenzo Maggi, NVIDIA (examinateur)
Ana Buši?, Inria Paris(directrice de thèse)
Jiamin Zhu, IFP Energies Nouvelles(co-encadrante de thèse)
Tristan Charrier, AMIAD (membre invité,superviseur DGA)

Sharp phase transition in discrete and continuum percolation.
2025-01-17 11:00 - 12:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
This talk consists of simple example of percolation models:Bernoulli bond and site percolation on lattice and Poisson Boolean model onEuclidean space. In these models we say that percolation happens, if thereexists a critical value of the parameter such that, the system hasinfinite component above the critical value of the parameter and all thecomponents are finite if it is below the critical value. In this talk weshall explore the concept of sharp phase transition in the abovepercolation models using the seminal works by Hugo Duminil-Copin andco-authors. The term ``sharp phase transition" is about how the probabilityof having a path from origin to a distance $n$, decays in $n$, in thesub-critical regime. It also captures how the percolation probabilitybehaves in the supercritical regime. Later in this talk I will present someexample of higher dimensional percolation models on the lattice on Z^d,namely the hypercube percolation and hole percolation model. The firstmodel can be thought of as a generalization of the usual bond/sitepercolation model. Hiraoka and Mikami was the first to define the holegraph model. We will try to see how we can use the ``OSSS method" developedby Hugo Duminil-Copin and co-authors, to prove sharp phase transition.

Some network emulation tools
2025-01-10 11:00 - 12:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
In this talk, we will explore various practical methods toobtain a functional network for running applications based on TCP/UDP/IP.We will delve into the SNEAC/NetMirage emulators [2,3] and Mininet [1],particularly in conjunction with a SDN controller, exclusively used tomanage packet routing. Additionally, we will examine the Internet TopologyZoo project [5], which features national research network topologiesencoded in GraphML format, importable into Mininet with the help of theAssessing Mininet project [4]. We will also provide a brief overview ofother approaches, including network simulation and large-scaletestbeds.

References:

[1]
B. Lantz, B. Heller, and N.McKeown, A network in a laptop: rapid prototyping for software-definednetworks, in Proceedings of the 9th ACM SIGCOMM Workshop on Hot Topics inNetworks, in Hotnets-IX. New York, NY, USA: Association for ComputingMachinery, Oct. 2010, pp. 1–6. doi: 10.1145/1868447.1868466. Accessed:Jan. 6, 2025. [Project Website].Available: https://mininet.org/

[2]
CrySP Team, NetMirage |Cryptography, Security, and Privacy (CrySP) | University of Waterloo.(Jan. 09, 2019). C. University of Waterloo. Accessed: Jan. 06, 2025.[Linux].Available: https://crysp.uwaterloo.ca/software/netmirage/

[3]
S.Singh, Large-Scale Emulation of Anonymous Communication Networks, MasterThesis, University of Waterloo, Waterloo, Ontario, Canada, 2014.Accessed: Oct. 24, 2024. [Online].Available: http://hdl.handle.net/10012/8642

[4]
M. Großmann andS. J. A. Schuberth, Auto-Mininet?: Assessing the Internet Topology Zoo ina Software-Defined Network Emulator, 2014. Accessed: Nov. 20, 2024.[Online].Available: https://www.semanticscholar.org/paper/Auto-Mininet-%3A-Assessing-the-Internet-Topology-Zoo-Gro%C3%9Fmann-Schuberth/9520a901f0d452cc29f60426ce0b26bda15eb12d. Accessed: Jan. 6, 2024.[GitHub]: https://github.com/sjas/assessing-mininet

[5]
S.Knight, H. X. Nguyen, N. Falkner, R. Bowden, and M. Roughan, TheInternet Topology Zoo, IEEE Journal on Selected Areas in Communications,vol. 29, no. 9, pp. 1765–1775, Oct. 2011,doi: 10.1109/JSAC.2011.111002. Accessed: Jan. 6, 2025. [Online].Available: https://topology-zoo.org/

Preventing WebRTC IP Address Leaks
2025-01-08 14:00 - 15:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
The WebRTC API enables real-time communication of text,video, and audio media streams through a web browser without requiringthird-party extensions. However, it was not designed with privacy in mind.We conduct an experiment to analyse privacy leaks associated with WebRTC.Our findings show that despite recent updates to the WebRTC specificationand its implementations, sensitive public IP addresses can still be leakedduring audio/video communication, particularly in large non-NAT corporatenetworks, even when using a VPN, SOCKS or HTTP/S proxy. To address theobserved leaks, we develop a simple, easily maintainable, cross-platformopen-source solution that confines the Mozilla Firefox web browser in adocker container. We also take into account the possibility of a maliciousadversary compromising the browser.
Our tests have shown that ourcontainerised solution is effective in all situations without restrictingapplications.

Git happens: from first commit sadness, to CI/CD greatness
2024-12-20 11:00 - 12:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
Git is a developer’s best friend… until it isn’t. Whetherit’s an accidental git push --force, a mysterious merge conflict or thefeared “detached HEAD” state that reflects more a state of mind than aGit feature, we’ve all been there. In this talk, we’ll embrace thoseedge cases, laugh at our past mistakes, and learn how to handle Git likea pro.

But Git is not just about fixing mistakes: it’s also thebackbone of modern development workflows. We’ll dive into how effectivelyuse Continuous Integration/Continuous Deployment (CI/CD) pipelines andWebhooks, turning our repositories into automated collaborationcompanions. From triggering tests and deployments to notifying Slack whensomeone finally fixes the typo in the documentation, we’ll explore howGit can make your development life easier. By the end of this tutorial,you will know how to recover gracefully from errors, optimize yourworkflows, and master the powerful tool that is Git.

A Stochastic Geometry Framework for RIS-Assisted Cellular Networks
2024-12-18 02:00 - 05:00 | Inria Paris, 48 rue Barrault, Paris, 75013, France
This thesis is jointly supervised by Prof. François Baccelli,Dr. Luis Uzeda Garcia, and Dr. Stefano Paris.

This thesisinvestigates the impact of deploying reconfigurable intelligent surfaces(RIS), which can engineer spatial diversity in complex cellular networks,at a system level. We develop a framework to characterize the performanceof RIS-assisted cellular networks, focusing on downlink coverageprobability and ergodic rate, where we consider that multiple RISs canserve one UE simultaneously. To account for the inherent randomness in thespatial deployments of base stations (BSs) and RISs, we model theplacements of the RISs as point processes (PPs) conditioned on theassociated BSs, which are modeled by a Poisson point process (PPP). TheseRIS PPs can be adapted based on the deployment strategy. We focus onmodeling the RISs as a Matérn cluster process (MCP), where each RIScluster is a finite PPP with support of a disc centered on the associationBS. We assume that the system uses the orthogonal frequency divisionmultiplexing (OFDM) technique to exploit the multipath diversity providedby RISs. The coverage probability and the ergodic rate can be evaluatedwhen RISs operate as batched powerless beamformers. The resultinganalytical expressions provide a general methodology to evaluate the impactof key RIS-related parameters, such as the density of RISs, onsystem-level performance. To demonstrate the framework’s broadapplicability, we also analyze a RIS placement variant where RISs aredeployed around coverage holes. Furthermore, the proposed frameworkenables techno-economic analysis of RIS-assisted networks. We introduce arelative cost model considering the total cost of ownership (TCO) ofdeploying both BSs and RISs, along with a return on investment (ROI) modelthat is proportional to spectral efficiency. This approach gives operatorsquantitative insights to develop investment strategies regarding whether toinvest in RISs based on current BS and RIS densities. To assess performanceand conduct techno-economic analysis, the analytical expressions involvingmultiple integrals are computationally complex. We address this challengeby developing a novel numerical solver based on the Genz-Malik rule andparallel computing, allowing efficient evaluation within acceptable timeconsumption and improving the practical applicability of the proposedframework. Based on this solver, numerical evaluations of the analyticalexpressions and Monte-Carlosimulations jointly validate the proposedanalytical approach and provide valuable insights into the design of futureRIS-assisted cellular networks.

Line Cox Processes Part II: Large Scale Automotive Radar Networksand Statistics of Successive Successful Detection
2024-12-11 14:00 - 15:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
Note: Part I of this talk was presented at LINCS in 2023(www.lincs.fr/events/seminar-talk-by-gourab-ghatak/).

In this talk,first, we revisit the newly introduced model -the binomial line Coxprocesses (BLCP) and discuss its validity from the perspective of realworld street data. Then, we employ the BLCP and the Poisson line Coxprocess (PLCP) to emulate a large scale automotive radar network. We willbriefly discuss the classical stochastic geometry metrics of detectionprobability and the meta-distribution.

Then, we introduce a novelmetric for stochastic geometry based analysis of automotive radar networkscalled target tracking probability. Unlike the well-investigated detectionprobability (often termed as the success or coverage probability instochastic geometry), the tracking probability characterizes the event ofsuccessive successful target detection with a sequence of radar pulses.From a theoretical standpoint, this work adds to the rich repertoire ofstatistical metrics in stochastic geometry. To optimize the target trackingprobability in high interference scenarios, we study a block medium accesscontrol (MAC) protocol for the automotive radars and recommend the optimalMAC parameter for a given vehicle and street density. Importantly, we showthat the optimal MAC parameter that maximizes the detection probability maynot be the one that maximizes the tracking probability. Our researchreveals how the tracking event can be naturally mapped to the quality ofservice (QoS) requirements of latency and reliability for differentvehicular technology use-cases. This can enable use-case specific adaptiveselection of radar parameters for optimal target tracking.

Heroes: Lightweight Federated Learning with Neural Composition andAdaptive Local Update in Heterogeneous Edge Networks
2024-12-06 11:00 - 12:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
Federated Learning (FL) enables distributed clients tocollaboratively train models without exposing their private data. However,it is difficult to implement efficient FL due to limited resources. Mostexisting works compress the transmitted gradients or prune the global modelto reduce the resource cost, but leave the compressed or pruned parametersunder-optimized, which degrades the training performance. To address thisissue, the neural composition technique constructs size-adjustable modelsby composing low-rank tensors, allowing every parameter in the globalmodel to learn the knowledge from all clients. Nevertheless, some tensorscan only be optimized by a small fraction of clients, thus the globalmodel may get insufficient training, leading to a long completion time,especially in heterogeneous edge scenarios. To this end, we enhance theneural composition technique, enabling all parameters to be fully trained.Further, we propose a lightweight FL framework, called Heroes, withenhanced neural composition and adaptive local update. A greedy-basedalgorithm is designed to adaptively assign the proper tensors and localupdate frequencies for participating clients according to theirheterogeneous capabilities and resource budgets. Extensive experimentsdemonstrate that Heroes can reduce traffic consumption by about 72.05% andprovide up to 2.97× speedup compared to thebaselines.

Authors: Jiaming Yan; Jianchun Liu; ShilongWang; Hongli Xu; Haifeng Liu; Jianhua Zhou

Published in: IEEEINFOCOM 2024 - IEEE Conference on Computer Communications

Handover frequency in dynamic terrestrial network
2024-12-04 14:00 - 15:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
In this work we shall consider a dynamic wireless communicationmodel on real line or plane. Let us assume that a user located at origin,which is served by mobile base stations. The initial locations of the basestations are given by a homogeneous Poisson point process. The basestations are given identical speed in uniformly chosen random direction.The user stays connected to the nearest base station at given point oftime. Since the base stations are moving, the user disconnects andconnects with different base stations over time, which ever base stationis the closest. This gives rise to a handover phenomenon in the system anda point process on the time axis, called as the ''handover pointprocess''. We shall determine the handover frequency in single-speed andmulti-speed scenarios. It is also interesting to investigate the case whenuser has finite visibility. If time permits, we shall touch upon the casewhen the initial locations of the base stations are given by a Cox pointprocess and their motion is along the underlying randomenvironment.

This is an ongoing work with Prof. François Baccelli.

The functools python module
2024-11-29 11:00 - 12:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
First, we recall several concepts (lambda functions,callbacks, callables, functors, decorators) needed for the rest of thepresentation.
Second, we present the "functools" module, which provideshigher-order utilities dedicated to use callables (including caching,ordering, dispatching, wrapping).
Third, we give a quick overview ofthe "operator" module, which is commonly used to transform pythonoperators to callables or to define elegant callbacks.

Knowledge Graphs Construction using Small Language Models
2024-11-27 14:00 - 15:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
This talk demonstrates how to efficiently Knowledge GraphsConstruction using Small Language Models like Llama-3.2-3B, showingpractical techniques for extracting structured knowledge from JSON and PDFsources through strategic prompting and LLM-based agents. By breaking downcomplex tasks and orchestrating these lighter models, we achieve robustknowledge extraction while maintaining low computational costs and ensuringprivacy.

https://github.com/camilochs

Lagrangian multipliers, normal cones and KKT optimality conditions
2024-11-22 11:00 - 12:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
Lagrange multipliers are a go-to tool for anyone who’s workedin optimization.
In this talk we will explore the renownedKarush-Kuhn-Tucker optimality conditions starting from first principles,leveraging visual insights, and gradually progressing to the formal proofin the context of linear constraints.
The talk is based on the blogpost: https://mlwithouttears.com/2024/11/06/lagrangian-multipliers-normal-cones-and-kkt-optimality-conditions/

Lincs PhD Welcome Day
2024-11-20 08:30 - 13:30
We are delighted to finally announce the programme (click onit!) for this special day dedicated to welcoming our PhD students !
Theevent will begin with a presentation of the lab by its director, followedby an overview of our annual activities presented by the coordinators ofour Reading groups. Each PhD student will then have three minutes tointroduce themselves, share their background, and briefly present theirresearch.

Optimizing Energy Consumption and Performance in Modern CloudSystems
2024-11-15 11:00 - 12:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
In the modern era of data-driven innovation, the challenge ofoptimizing energy consumption without sacrificing performance in moderncloud system networks has become increasingly important. This talk goesthrough strategies to achieve energy-efficient, high-performance cloudenvironments, focusing on approaches like resource consolidation,workload orchestration, and intelligent offloading.

uv: an extremely fast Python package installer and resolver &marimo notebooks: rethinking the notebook to create reproducible notebooks
2024-11-08 11:00 - 12:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
In this session, we will talk about uv, an extremely fastPython package and project manager designed as a single tool to replacepip, pip-tools, pipx, poetry, pyenv, virtualenv, and more. We willalso discuss marimo, an open-source reactive notebook for Python that isreproducible, git-friendly, executable as a script, and shareable as anapp.

Presentation :https://alonsosilvaallende.github.io/2024-11-08_uv_marimo_at_LINCS

Codeto make the presentation work in :alonsosilvaallende/2024-11-08_uv_marimo_at_LINCS: Presentation uv+marimo atLINCS

The Squared Kemeny Rule for Averaging Rankings
2024-11-06 14:00 - 15:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
For the problem of aggregating several rankings into oneranking, Kemeny (1959) proposed two methods: the median rule which selectsthe ranking with the smallest total swap distance to the input rankings,and the mean rule which minimizes the squared swap distances to the inputrankings. The median rule has been extensively studied since and is nowknown simply as Kemeny's rule. It exhibits majoritarian properties, so forexample if more than half of the input rankings are the same, then theoutput of the rule is the same ranking.

We observe that this behavior isundesirable in many rank aggregation settings. For example, when we rankobjects by different criteria (quality, price, etc.) and want toaggregate them with specified weights for the criteria, then a criterionwith weight 51% should have 51% influence on the output instead of 100%. Weshow that the Squared Kemeny rule (i.e., the mean rule) behaves this way,by establishing a bound on the distance of the output ranking to any inputrankings, as a function of their weights. Furthermore, we give anaxiomatic characterization of the Squared Kemeny rule, which mirrors theexisting characterization of the Kemeny rule but replaces the majoritarianCondorcet axiom by a proportionality axiom. Finally, we discuss thecomputation of the rule and show its behavior in a simulationstudy.

Joint work with Patrick Lederer and Tomasz W?s.

Optimal time partitioning in V2V ISAC Systems
2024-10-30 14:00 - 15:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
Platooning-based vehicle-to-vehicle (V2V) integrated sensingand communication (ISAC) frameworks have emerged as an attractive strategyin recent years. In this work, we present an optimal time partitioning(OTP) framework in V2V ISAC systems. We propose a novel sensing measure forquantifying radar sensing performance as a function of the maximumdetectable range and velocity of the radar. With the communicationoperation following the sensing operation, an OTP problem is formulatedand solved as a convex problem, constrained by sensing and communicationperformance guarantees. Optimal bounds on the time duration for sensing andcommunication are derived, along with the maximum achievable communicationthroughput. Furthermore, analytical insights on the inherent trade-offsassociated with the design parameters are presented.

Hierarchical Community Detection in Hierarchical Stochastic BlockModels
2024-10-25 11:00 - 12:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
In this session of our reading group, I will discuss communitydetection in hierarchical clustering of networks, based on thepaper "When Does Bottom-up Beat Top-down in Hierarchical CommunityDetection?" by Maximilien Dreveton et al. Hierarchical clustering involvesconstructing a tree of communities, with lower levels revealingfiner-grained structures. Two main approaches address this problem:divisive (top-down) algorithms, which recursively split nodes, andagglomerative (bottom-up) algorithms, which start by identifying thesmallest communities and then merge them using a linkage method. This talkwill focus on establishing theoretical guarantees for the exact recovery ofthe hierarchical tree under a Hierarchical Stochastic Block Model (HSBM)using a bottom-up algorithm. The findings show that bottom-up methods canachieve the information-theoretic threshold for exact recovery atintermediate hierarchy levels, offering less restrictive conditions thantop-down algorithms and expanding the feasible region for accuratecommunity detection.

Understanding Reinforcement Learning error in image-basedenvironments
2024-10-18 14:00 - 15:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
In many Reinforcement Learning (RL) environments the state isrepresented by an image. In such cases, if the RL doesn’t work well, isthe problem that the image processing doesn’t recognize the salientfeatures of the image well (i.e. there’s a recognition issue)? Or is theproblem that the RL can’t learn the correct action, even though itcorrectly recognizes the state (i.e. there’s a decision issue)? Or is ita bit of both?

In this talk we’ll discuss two ways to formalize thesequestions. In the first, we examine how well an agent can learn the“Q-value” of an image, if it is given some explicit examples in atraining set. We then compare an agent trained in this way with an agenttrained with standard RL techniques. In the second, we decompose theregret of an RL agent into two terms that separately capture therecognition and decision error.

We illustrate our techniques usingstandard RL environments such as Minigrid and Pong.

Joint work withAlihan Huyuk, Xueyuan She, Atefeh Mohajeri, Ryo Koblitz

Decentralized Federated Policy Gradient with ByzantineFault-Tolerance and Provably Fast Convergence
2024-10-18 11:00 - 12:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
In Federated Reinforcement Learning (FRL), agents aim tocollaboratively learn a common task, while each agent is acting in itslocal environment without exchanging raw trajectories. Existing approachesfor FRL either (a) do not provide any fault-tolerance guarantees (againstmisbehaving agents), or (b) rely on a trusted central agent (a singlepoint of failure) for aggregating updates. We provide the firstdecentralized Byzantine fault-tolerant FRL method. Towards this end, wefirst propose a new centralized Byzantine fault-tolerant policy gradient(PG) algorithm that improves over existing methods by relying only onassumptions standard for non-fault-tolerant PG. Then, as our maincontribution, we show how a combination of robust aggregation andByzantine-resilient agreement methods can be leveraged in order toeliminate the need for a trusted central entity. Since our resultsrepresent the first sample complexity analysis for Byzantine fault-tolerantdecentralized federated non-convex optimization, our technicalcontributions may be of independent interest. Finally, we corroborate ourtheoretical results experimentally for common RL environments,demonstrating the speed-up of decentralized federations w.r.t. the numberof participating agents and resilience against various Byzantineattacks.

Paper from Philip Jordan, Florian Grötschla, Flint XiaofengFan and Roger Wattenhofer.

Visual Studio Code, an all-in-one development environment
2024-10-11 11:00 - 12:00
Rémi Varloot will present VS Code, a text editor /development environment that can be used for just about every coding need,and showcase how it can be used to work with Python (including notebooks),LaTeX, Git, code hosted on remote machines, and more if time permits.

Zero knowledge proofs in blockchain
2024-10-09 14:00 - 15:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
In this talk, we will explore the fundamental concept of ZeroKnowledge Proofs (ZKPs), a cryptographic technique that allows one partyto prove knowledge of a specific piece of information to another partywithout revealing the information itself. We will delve into two corecomputation models used in ZKPs: the circuit computation model and themachine computation model. These models form the basis of how ZKPs aredesigned and implemented. Furthermore, we will examine various real-worldapplications of ZKPs, with particular emphasis on their critical role inenhancing privacy and security in blockchain systems. Attendees will gain afoundational understanding of ZKPs and insight into how they are applied todiverse scenarios in modern cryptographic systems.

Short bio

José L.Muñoz-Tapia received the M.S. degree in telecommunications engineering andthe Ph.D. degree in security engineering, in 1999 and 2003, respectively.He is currently a Researcher with the Information Security Group (ISG) andan Associate Professor with the Department of Network Engineering,Universitat Politècnica de Catalunya (UPC). He is also the Director of theMaster Program in Blockchain Technologies, UPC School. He has worked inapplied cryptography, network security, and game theory models applied tonetworks and simulators. His research interest includes distributed ledgerstechnologies.

Quantum states are relative to observers!
2024-10-04 11:00 - 12:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
Many "pseudo-paradoxes" arise in quantum physics because"quantum states" are generally considered to be absolute, that is,independent of observers. But entangled pairs of qubits in Bell states withtwo distant observers, one per qubit, force us to reconsider the statusof quantum states, revealing their observer-dependence. It is at the coreof the "relational" interpretation of quantum mechanics, as proposed byCarlo Rovelli [Rovelli 1996], or Asher Peres' interpretation of theEinstein-Podolsky-Rosen dilemma [Peres 2004, §2],
and it is related tothe observer-dependence of time in special relativity. It is important tohave in mind this observer-dependence in distributed quantum systems, suchas quantum networks where the speed of light cannot be considered as"infinite". It helps in understanding and accepting the physical phenomenainvolved in such systems.

References:

("easy" to read, mostlyphilosophical views on quantum physics)
[Rovelli 1996] CarloRovelli, Relational Quantum Mechanics,1996
https://arxiv.org/abs/quant-ph/9609002
[Peres 2004] AsherPeres, Quantum information and general relativity,2004
https://arxiv.org/abs/quant-ph/0405127

Slides of thepresentation: PDF.

How Much Can Reconfigurable Intelligent Surfaces Augment SkyVisibility: A Stochastic Geometry Approach
2024-10-02 15:00 - 16:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
This talk presents the application of point processes andstochastic geometry to quantify the sky visibility experienced by userslocated in an outdoor environment. The general idea is to represent thebuildings of this environment as a stationary marked point process, wherethe points represent the building locations and the marks their heights.The point process framework is first used to characterize the distributionof the blockage angle, which limits the visibility of a typical user intothe sky due to the obstruction by buildings. In the context ofcommunications, this distribution is useful when users try to connect tothe nodes of an aerial or non-terrestrial network in a Line-of-Sight way.Within this context, the point process framework can also be used toinvestigate the gain of connectivity obtained thanks to ReconfigurableIntelligent Surfaces.
Assuming that such surfaces are installed on the topof buildings to extend the user's sky visibility, this point processapproach allows one to quantify the gain in visibility and hence the gainin connectivity obtained by the typical user. The distributional propertiesof visibility-related metrics are cross-validated by comparison tosimulation results and 3GPP measurements.

Design and Optimizations Toward Smart Grid Connected Green FutureNetworks
2024-10-02 14:00 - 15:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
Realizing energy sustainable communication networks has been akey challenge in the upcoming sixth generation (6G) networks. A keybottleneck has been to make the energy-efficient network solutionsindustrially attractive and scalable, thereby necessitating atechno-economic analysis. Through this talk, the prospects of achievingenergy sustainability as well as cost profitability through ambient poweredand grid connected communication framework is analyzed and studied. Thepower grid connectivity plays a vital role in achieving the aforesaidobjective, alongside ambient powered base stations (BSs). The networkedsystem is further analyzed to outlay the challenges, physicalconstraints, and network operations involved in optimizing the system. Thetalk highlights the key system design objectives and their inherenttechno-economic tradeoffs. Specifically, the talk outlines the importanceof energy balancing in networks, and showcases the benefit of jointload-energy balancing in networks in contrast to the traditional loadbalancing paradigm.

Gaming on the Edge: Performance Issues of Distributed Online Gaming
2024-09-25 15:00 - 16:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
Edge computing is revolutionising gaming and streaming servicesby processing data closer to the user, which greatly reduces latency andenhances bandwidth efficiency. This talk delves into the integration ofedge computing with online gaming, focusing on the Gaming as a Service(GaaS) paradigm. Through an analytical model we show that edge-based gamingarchitectures can outperform traditional cloud gaming solutions in terms ofresponse times. We will discuss insights into the benefits and complexitiesof edge computing in online gaming, offering a framework for futuredevelopments in this dynamic field.

Job migrations in queueing networks: some non-conventionalproduct-forms
2024-09-25 14:00 - 15:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
Job migrations are important to improve the performance indistributed systems. In this talk, we explore two policies for jobmigration that are receiver-initiated, i.e., the migration of one or morejobs is triggered by the state of the stations that will receive the newworkload. The first policy is aimed at improving the load-balancing in thequeueing network, and allows an empty station to 'steal' a geometricallydistributed batch of jobs from another station, if these are present. Thesecond policy that we propose forces an empty station to steal one job fromanother station but, if this is empty, the job-stealing signal ispropagated backward along the routing topology until a station with atleast one job is found. We show that the queueing network models underlyingthese policies admit product-form solution under the usual exponentialassumptions and discuss their mean value analysis.

An Economic Analysis of 5G Network Slicing and the Impact ofRegulation
2024-09-18 15:00 - 16:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
A joint work with Yassine Hadjadj-Aoul, Maël LeTreust, and Bruno Tuffin

Network slicing is a key component of5G-and- beyond networks, requiring to define a business model for resourceallocation. We consider a model with a Service Provider (SP) that maypurchase a slice in a wireless network, in order to offer a “premium”service where the improved quality stems from higher prices leading to lessdemand and less congestion than the basic service offered by the networkowner, a scheme known as Paris Metro Pricing. One optimization problem forthe SP is the choice of how much resource to allocate to that slice. Wealso compare with the case of a unique “pipe” (no premium service) andwith the case of vertical integration to evaluate the impact of slicing onall actors and identify the “best” economic scenario.

Performance analysis of a buffered cellular network: Coverageprobability, channel capacity, and steady-state analysis
2024-09-18 14:00 - 15:00 | Amphi 6, 19 Place Marguerite Perey, Palaiseau, France
In this talk I will discuss a stochastic geometric model of abuffered cellular network with either uplink or downlink transmissions.Various network models have been widely considered in many works fromdifferent perspectives, and our work partially adopts general concepts ofnetwork topology. Some crucial features of our model include the presenceof a buffer of finite or infinite capacity for failed signals, thebusy/idle state of the transmitters, and the time-inhomogeneity of thenetwork behavior. We start with defining a tractable mathematical model ofthe network which we then use to derive analytical expressions for coverageprobability, Shannon capacity, stationary busy probability and bufferdistribution. We will also look at some numerical and simulation resultsfor visualization and model validation.

LINCS Annual Workshop with its Scientific Committee 2024
2024-06-27 09:00 - 2024-06-28 18:00 | Amphi Rose Dieng, 19 place Marguerite Perey, Palaiseau, France
https://www.lincs.fr/2024-lincs-annual-workshop-with-its-scientific-committee/

The event is reserved to the LINCS community

Pleasefind the program by clicking => Workshop LINCS - agenda 2024

Elevator: Self-* and Persistent Hub Sampling Service inUnstructured Peer-to-Peer Networks
2024-06-19 14:00 - 15:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
We present Elevator, a novel algorithm for hub sampling inpeer-to-peer networks, enabling the construction of overlays witha
topology between a random graph and a star network, and networks thathave both hubs and are resilient to failures. Our approach emerges
fromprinciples of preferential attachment, forming hubs spontaneously,offering an innovative solution for decentralized networks that canbenefit
use cases requiring a network with both low diameter andresilience to failures.

LINCS PhD Student Day + Team Building
2024-06-12 08:30 - 18:00
Supporting our PhD students is crucial for nurturing theirtalent and ensuring the success of their research.

We are glad to bethere for them, stimulating their creativity and motivation, which areessential for meaningful innovations.

PREVISIONAL PROGRAMME OVERVIEW

8h30 Welcome Breakfast
9h00 Moderator Welcome Speech
9h05Présentation of the PEPR Future Network and the National Center RS TN
9h15 Elevator Pitch - Session 1 : Each doctoral candidate will have 3minutes to present their work, followed by a brief Q&A session andfeedback from senior members
10h15 Coffee Break & Posters Session
10h30 Elevator Pitch - Session 2 : Each doctoral candidate will have 3minutes to present their work, followed by a brief Q&A session andfeedback from senior members
11h30 Brainstorming
12h30 Lunch
13h15 Depart to Aventure Floraval

Understanding and Modeling Collective User (Mis-)Behavior DrivingInformation Spread Online
2024-05-29 14:00 - 15:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
The literature is quite rich in efforts to model and analyzehow different aspects of user behavior may drive the dissemination of apiece of content online, favoring its spread at large. Yet, humanbehavior is often very heterogeneous, highly dynamic, and may manifestitself in multiple facets and scales, with components that areconceptually hard to operationalize. As such, inferring behavioralpatterns and profiles from digital traces can be quite challenging. In thistalk, I will discuss our efforts towards inferring, modeling andanalyzing collective user behavior (notably user campaigns) towardsfavoring information dissemination online. I will show results applied tothe study of spread of fake news, illegal political ads, and hate speech.Finally, as a short detour, I will discuss recent results on the use ofsimilar techniques to a completely different context, namelyscientometrics, to analyze the emergence of anomalous hyperprolificresearchers.

Short Bio

Jussara M Almeida is a Full Professor atthe Universidade Federal de Minas Gerais, Brazil, where she currentlyleads the Social Computing Laboratory (LOCUS) at the Department of ComputerScience. She holds a PhD from the University of Wisconsin-Madison (US) andis a former affiliate member of the Brazilian Academy of Sciences. Herareas of expertise are workload and user behavior characterization,performance analysis and modeling of large-scale distributed systems, andsocial computing.

Caching and pre-fetching: the role of hazard rates
2024-05-22 15:00 - 16:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Consider a local memory system receiving requests from a givencatalog: the typical caching objective is to maximize its hit rate, i.e.the number of items that are served directly from the cache. Two mainalternatives have been studied: replacement policies (such as LRU) andtimer-based policies (TTL).
In previous work, we have explored the roleof the hazard rate function of the inter-request times in the optimal TTLpolicy. Recently, Towsley et al. also identified that the optimalnon-anticipative replacement policy involves the hazard rate function.
Inthis talk we will discuss how these two concepts relate: we show that, inlarge scale systems, the optimal non-anticipative policy converges to afixed threshold policy, and that this threshold also characterizes theoptimal TTL policy. Thus TTL caching is asymptotically optimal, and we canapproximate the maximal hit rate by that of the TTL policy fluid limit.This enables us to compute new a universal performance bound for cachingperformance. We also remark that, in the case of increasing hazard rates,caching is far from optimal and introduce the notion of optimal timer-basedpre-fetching.

https://aferragu.github.io

Hypercomputation: a paradigm for network-inspired computing
2024-05-22 14:00 - 15:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
In this talk Carlos Zapata-Carratala will present evidence fromrecent work on hypergraph rewriting research and abstract algebra thatpoints towards new ways to conceptualise and implement universalcomputation. The recent success of GPUs for ML/AI algorithm implementationillustrates the phenomenon that he will be presenting in a more generalcontext. He will propose computing architectures that may optimizecomputational processes that are dependent on network topology.

How to create pure Python web apps (Solara+AnyWidget)
2024-05-22 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Solara lets you build pure Python web apps. These apps workboth inside the Jupyter Notebook and as standalone web apps.

WithSolara, you benefit from a paradigm that promotes component-based code andsimplifies state management, making the development process more efficientand the applications more maintainable. Solara offers the flexibility tobuild complex apps, but keeps the simplicity of a small code base. We willcompare Solara to Streamlit/Gradio and show their benefits anddisadvantages.

AnyWidget is a Python library that simplifies creatingand publishing custom Jupyter Widgets. No messy build configuration orcomplicated cookiecutter templates. It is not a new interactive widgetsframework, but rather an abstraction for creating custom Jupyter Widgetsusing modern web standards.

Finally, we will see how Solara andAnyWidget synergize to create pure Python apps, demonstrating thecomplementary nature of these two powerful tools.

Notebook

Fullgithub repo

Navigating 5G Virtualization: Constructing a Kubernetes Cluster forSeamless Deployments
2024-05-15 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
This presentation navigates the intersection of 5G andvirtualization, offering a comprehensive guide to building a Kubernetes(K8s) cluster and configuring the OAI 5G core network. It explores the roleof virtualization in 5G networks, emphasizing Docker's pivotal role incontainerization. Attendees will gain insights into building their K8scluster, laying the groundwork for 5G deployments and learn to deploy theOpenAirInterface (OAI) core network alongside UERANSIM (gNB and UE)integration. This session provides essential insights for architects anddevelopers venturing into 5G deployments amidst virtualized environments.

What a confidence interval really is
2024-04-24 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
By analyzing a (hopefully) illuminating example in depth, wewill show what a confidence interval really is, and what are the commontraps in its interpretation.

The overview of the notebook is givenbelow. Unfortunately, the interactive plots cannot be displayed in this"gist" version. To see them, download the notebook and run it with yourlocal distribution.

Seminar Talk : A Protocol to Assess the Accuracy of Process-LevelPower Models
2024-04-17 14:00 - 15:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
The energy consumption of servers has been a critical researcharea, drawing significant interest from academic and industrial sectors.Various models have been developed to estimate power consumption ofcomputing devices, ranging from simple linear models to more complex ones.In recent years, as the cloud paradigm has expanded and allowedapplications to be hosted alongside others in virtual machines, powermodels have evolved to distribute energy usage among applications on aserver. These models aim to achieve two primary objec-tives: monitoring theenergy footprint and optimizing energy consumption. Nonetheless, littleattention has been given in academic literature to evaluate the efficiencyand accuracy of the allocation phase of this models. This paper presents adefinition of power division and a protocol to evaluate models using suchdivision. The proposed protocol is used to evaluate models on physicalmachines with different performance settings, toggeling hyperthreading andturboboost. Before discussing the conceptual distinctions between power andenergy allocation models, our results show the existence of somelimitations in the existing models. These results provide valuable insightinto the missing information needed to improve the accuracy of powermodels.

Level-strategyproof Belief Aggregation Mechanisms
2024-04-10 14:00 - 15:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
In the problem of aggregating experts' probabilisticpredictions over an ordered set of outcomes, we introduce the axiom oflevel-strategy\-proofness (level-SP) and prove that it is a natural notionwith several applications. Moreover, it is a robust concept as it impliesincentive compatibility in a rich domain of single-peakedness over thespace of cumulative distribution functions (CDFs). This contrasts with theliterature which assumes single-peaked preferences over the space ofprobability distributions. Our main results are: (1) a reduction of ourproblem to the aggregation of CDFs; (2) the axiomatic characterization oflevel-SP probability aggregation functions with and without the addition ofother axioms; (3) impossibility results which provide bounds for ourcharacterization; (4) the axiomatic characterization of two new andpractical level-SP methods: the proportional-cumulative method and themiddlemost-cumulative method; and (5) the application ofproportional-cumulative to extend approval voting, majority rule, andmajority judgment methods to situations where voters/experts are uncertainabout how to grade the candidates/alternatives to be ranked.

Double talk : "Can Edge Computing fulfill the requirements ofautomated vehicular services using 5G network?" & "Can Vehicular CloudReplace Edge Computing?"
2024-04-03 14:00 - 15:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Abstract 1: Communication and computation servicessupport-
ing Connected and Automated Vehicles (CAVs) are characterized
bystringent requirements, in terms of response time andreliability.
Fulfilling these requirements is crucial for ensuringroad
safety and traffic optimization. The conceptually simple solution
ofhosting these services in the vehicles increases their cost
(mainly due tothe installation and maintenance of computation
infrastructure) and maydrain their battery excessively. Such
disadvantages can be tackled viaMulti-Access Edge Computing
(MEC), consisting in deploying computationcapability in network
nodes deployed close to the devices (vehicles inthis case),
such as to satisfy the stringent CAV requirements.
However,it is not yet clear under which conditions MEC can
support CAVrequirements and for which services. To shed light
on this question, weconduct a simulation campaign using well-
known open-source simulationtools, namely OMNeT++, Simu5G,
Veins, INET, and SUMO. We are thusable to provide a reality
check on MEC for CAV, pinpointing what are thecomputation
capacities that must be installed in the MEC, to supportthe
different services, and the amount of vehicles that a singleMEC
node can support. We find that such parameters must vary a
lot,depending on the service considered. This study can serve
as a preliminarybasis for network operators to plan future
deployment of MEC to supportCAV.

Abstract 2: Edge computing (EC) consists of deployingcom-
putation resources close to the users, thus enablinglow-latency
applications, such as augmented reality and onlinegaming.
However, large-scale deployment of edge nodes can behighly
impractical and expensive. Besides EC, there is a risingconcept
known as Vehicular Cloud Computing (VCC). VCC is a com-
putingparadigm that amplifies the capabilities of vehicles by
exploiting part oftheir computational resources, enabling them
to participate in servicessimilar to those provided by the EC.
The advantage of VCC is that it canopportunistically exploit
part of the computation resources alreadypresent on vehicles,
thus relieving a network operator from thedeployment and
maintenance cost of EC nodes. However, it is still unknownunder
which circumstances VCC can enable low-latency applications
withoutEC. In this work, we show that VCC has the potential to
effectivelysupplant EC in urban areas, especially given the higher
density ofvehicles in such environments. The goal of this paper
is to analyze, viasimulation, the key parameters determining
the conditions under whichthis substitution of EC by VCC is
feasible. In addition, we provide ahigh level cost analysis to
show that VCC is much less costly for anetwork operator than
adopting EC.

C
2024-04-03 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
As stated in WIkipedia, C is a general-purpose computerprogramming language. It was created in the 1970s by Dennis Ritchie, andremains very widely used and influential. By design, C's features cleanlyreflect the capabilities of the targeted CPUs. It has found lasting use inoperating systems, device drivers, and protocol stacks, but its use inapplication software has been decreasing. C is commonly used on computerarchitectures that range from the largest supercomputers to the smallestmicrocontrollers and embedded systems.

As the C language issignificantly more efficient than language like Python, it also offer theopportunity to develop efficient core module which can later be wrapped ina Python function.

This tutorial assumes that the audience is alreadyfamiliar with another programming language (e.g., Python or Java). Afterbriefly recalling the syntax of the C language, we focus on notionsspecific to the C language:

precompilation and compilation (gcc,make)
pointers and memory allocation
debugging (gdb, valgrind)
how to wrap C functions in python using poetry [1]

Here are theslides.

[1] https://github.com/ibgp2/Poetry_C_Extension_Example

Tournament Solutions
2024-03-27 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
A tournament is an oriented graph where there is exactly oneedge between each pair of nodes, in one direction or the other, with theimplicit interpretation that one node "beats" the other. If the binaryrelation induced by the tournament is transitive, then there is a naturalnotion of winner, which is the maximal element. But in the general case,it would be interesting to have a function that, to each tournament,associates a set of cowinners, and that has intuitively appealingproperties. We will investigate such functions, called "tournamentsolutions".

References:
Laslier, Jean-François. Tournament solutionsand majority voting. Springer, 1997.
Brandt, Felix, Markus Brill andPaul Harrenstein. Tournament Solution. In: Brandt, Felix, VincentConitzer, Ulle Endriss, et al (ed.). Handbook of computational socialchoice. Cambridge University Press, 2016.

Slides

Double Feature: IPyWidgets + Using LLM
2024-03-20 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
IPyWidgets is a popular Python library for creatinginteractive, customizable user interfaces in Jupyter Notebooks and otherenvironments using the power of the Widgets system from the InteractiveComputing and Visualization Toolkit (IPython).
Large Language Models(LLMs) are advanced artificial intelligence models capable of generatinghuman-like text based on the input they receive. These models have gainedsignificant attention in recent times due to their ability to understandcontext, generate creative responses, and assist with various tasks suchas text generation, summarization, translation, and more.
In thistutorial, we'll explore how to create interactive data visualizationsusing IPywidgets, a popular Python library for building dynamic userinterfaces, and Large Language Models (LLMs) like Hugging FaceTransformers. By combining these two powerful tools, you can createengaging data visualizations that respond to user input inreal-time.
Prerequisites:
- Basic understanding of Python programming
-Familiarity with Jupyter Notebook or JupyterLabenvironment
Preparation:
- Install IPywidgets if it is not already inyour distribution
- Install llama-cpp-python with server option
-Details: https://github.com/abetlen/llama-cpp-python
- If you have a Cudacard, try to install with cuBLAS option
- Choose and download a GGUFmodel from Hugging Face
- Small configurations:https://huggingface.co/TheBloke/phi-2-GGUF
- Got a decent Cuda card?https://huggingface.co/TheBloke/Mistral-7B-Instruct-v0.2-GGUF
- Look thesize and required RAM to choose a specific (sub)version
- Files are in the"Files and versions" tab
Learning Objectives:
- Understand the basics ofIPywidgets and Hugging Face Transformers
- Learn how to create interactivedata visualizations using IPywidgets
- Discover how to integrate LLMs withIPywidgets to create dynamic visualizations that respond to user input
-Explore examples of practical applications of these techniques
Thedescription above was generated using the assistance of aMistral-7B-Instruct-v0.2-GGUF model ;)

Group Signature in Dynamic Clusters
2024-03-13 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
This talk presents a group signature scheme specificallydesigned for a cluster of moving vehicles. The group signature enablesvehicles to authenticate themselves within dynamic clusters upon thedeparture or the arrival of entities. This ensures secure communicationbetween entities, while preserving their privacy.

Introduction to the cake cutting problem
2024-03-06 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
The cake cutting problem arises when a cake must be dividedfairly among individuals who have different preferences. In thispresentation, after a brief explanation of the model, we will introducedifferent definitions of "dividing fairly", exploring what it means toachieve fairness in such a scenario. Notably, we will emphasize on"envy-freeness" (no one envies the piece of cake allocated to anotherperson), especially by showing an algorithm that achieves it when thenumber of individuals is 2 or 3. This will be the occasion to talk aboutthe computational complexity of allocation algorithms, and the theoreticalbounds obtained so far in the literature.

Is Reinforcement Learning all you need?
2024-02-28 10:30 - 11:30
When attacking a new problem, the algorithm designer typicallyfollows 3 main steps:

rule out options that are unlikely to workwell
test the handful of options that made the first cut
pick thebest one and polish it until it shines

When reporting her/his work, thealgorithm designer will proudly focus on step 3), briefly mention 2) andlikely sweep 1) under the carpet. Yet, skimming alternatives off is acrucial step, that inevitably impacts (positively or negatively) months ofhard work on testing and polishing.

I would like to lift the veil onstep 1) and start sharing some subjective, but hopefully relatable,insights on how to navigate through the staggering amount of optionsavailable to the algorithm designer to solve a sequential decision-makingproblem, notably in the field of telecommunications.

Based on a recentblog posthttps://mlwithouttears.com/2023/10/27/is-reinforcement-learning-all-you-need/

Slides

International Workshop on RIS
2024-02-22 09:30 - 2024-02-23 17:00
Reconfigurable Intelligent Surfaces are very promisingphysical-layer candidates for sixth-generation cellular networks.
Thisinternational workshop will cover the main scientific and technologicalquestions underlying this promise: electromagnetism, meta-materials,beamforming, adaptive control,network architecture, and network energyexpenditure.
Click here below for further information :

click hereto acces the program and the registration form

A visual journey to convey complex messages through MAThematicalANIMation - manim
2024-02-21 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Manim is a tool used to programmatically create precise andhigh-quality animations.
Based (almost) entirely on Python, manimevolved from being a powerful visualization engine for complex mathematicalconcepts, to a general-purpose utility that extends far beyond the realmof mathematics.
In this presentation/tutorial, we will dive into someManim concepts, exploring how can educators, researchers, and scientistleverage it to create dynamic and engaging scientific animations.
Throughthis hands-on session, we will explore how to create simple animationswith basic shapes, how to animate generic text or formulas, and then seesome real examples (both from my personal library and some communitycode).

A new perspective of entropy
2024-02-14 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Have you ever wondered how mathematicians "understand"? In a1932 lecture, Hermann Weyl identified two key modes of mathematicalreasoning: topology and abstract algebra. These, he argued, can help ussolve problems in a way subject to the Dirichlet principle, minimizingmindless calculations and maximizing insightful thoughts. Recently, Dr.Tai-Danae Bradley took this idea further, suggesting that informationtheory, using the formular of Shannon entropy, can bridge these two modesof understanding. In this lecture, I'll explore her fascinating work,"Entropy as a Topological Operad Derivation", and show how it offers a new way to understand entropy - not just as a measure of disorder, butalso as a tool for mathematical reasoning. Join me to gain a freshperspective on this interesting concept and its potential impact on ourunderstanding of the world.

[1]: Weyl, Hermann. "Part I. Topology andabstract algebra as two roads of mathematical comprehension." The Americanmathematical monthly 102.5 (1995): 453-460.

[2]: Weyl, Hermann. "PartII. Topology and Abstract Algebra as Two Roads of MathematicalComprehension." The American mathematical monthly 102.7 (1995):646-651.

[3]: Bradley, Tai-Danae. "Entropy as a topological operadderivation." Entropy 23.9 (2021): 1195.

[4]: A more accessible versionof [3] provided by the same author https://uploads-ssl.webflow.com/649f7839d1d9d9bbdb8bc7ea/650e1fa362d02601b24d560b_bradley_spring22.pdf.

Bell theorem and the role of complex numbers in quantum informationtheory
2024-02-07 14:00 - 15:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Quantum information theory has several puzzling properties. Inparticular, it predicts that information carried by quantum objects isincompatible with the use of the logical ‘or’.

While in ourintuition of the world, a cat hidden in a box can be dead or alive,according to quantum mechanics this assertion is not valid anymore. Hence,we need a new concept: we say that a quantum cat can be dead ‘and’alive.

This new concept is however hard to accept: couldn’t we imaginea new theory replacing quantum information theory and compatible againwith our stadard logical ‘or’?

In 1964, Bell proved that, insome sense, this puzzling feature of quantum theory is a necessity: theredoes not exist any ‘reasonable’ theory of information (which wouldreplace quantum information theory) compatible with this logical‘or’.

Bell’s seminal proof is based on quantum correlations,which are obtained when multiple parties perform independent measurementson a shared quantum state.

I’ll first review this Bell theorem, anddiscuss some of its main consequences for the foundations of physics andthe more philosophical notion of determinism and randomness.

Then, Iwill discuss recent generalization of this theorem which were obtained inthe context of quantum networks, in which multiple parties performindependent measurements on several, independent quantum states.

Inparticular, I’ll show that Real Quantum Theory (the theory obtainedreplacing complex by real numbers in standard Quantum Information Theory)can be ruled out by a Bell-like experiment.

This talk is based on "Lanon-localité quantique à l’ère des réseaux, Marc Olivier Renou,Nicolas Brunner et Nicolas Gisin, POUR LA SCIENCE N° 528 (20 septembre2021)" and "Les nombres imaginaires sont indispensables à la théoriequantique pour décrire le monde, Marc-Olivier Renou, Antonio Acin etMiguel Navascués, POUR LA SCIENCE N° 551, 30 août2023"

Bio:
Marc-Olivier research focuses onquantum networks anddistributed computing, quantum protocols based on quantum correlations andthe
foundations of quantum information theory. He obtained his PhD fromGeneva university in 2019 (under the supervision of NicolasGisin).

After a postdoc at ICFO (Barcelona, Spain), he joined InriaSaclay in 2023.

An introduction to anonymity networks
2024-02-07 10:30 - 11:30 | Room 4B07, 19 place Marguerite Perey, Palaiseau, Gabon
Anonymity networks play a crucial role in preserving privacy onthe Internet by masking users' identities and guaranteeing theconfidentiality of communications. In this talk, we will explore theorigins of anonymisation networks through Chaum's seminal paper on mixnetworks [1]. Following this paper, research in this area emerged and gaverise to four classes of anonymity networks [2], those based on mixnets,those based on Tor and Onion Routing [3,4], those based on random walksand DHTs, and those based on DCNets [5]. There are others that fall intoseveral classes [2].
We will present some popular networks from theseclasses and use them in a practical way to connect to differentservices.

--
References

[1] D. Chaum, Untraceable electronic mail,return addresses, and digital pseudonyms, Communications of the ACM,vol. 24, no. 2, pp. 84–90, Feb. 1981, doi: 10.1145/358549.358563.Available at: https://www.doi.org/10.1145/358549.358563
[2] F. Shirazi,M. Simeonovski, M. R. Asghar, M. Backes, and C. Diaz, A Survey onRouting in Anonymous Communication Protocols, ACM Computing Surveys, vol.51, no. 3, p. 51:1-51:39, Jun. 2018, doi: 10.1145/3182658. Availableat: https://lirias.kuleuven.be/bitstream/123456789/626536/2/a51-shirazi.pdf
[3] R. Dingledine, N. Mathewson, and P. Syverson, Tor: TheSecond-Generation Onion Router, Defense Technical Information Center,Fort Belvoir, VA, Jan. 2004. doi: 10.21236/ADA465464. Available at: https://apps.dtic.mil/sti/citations/ADA465464
[4] D. M. Goldschlag, M. G.Reed, and P. F. Syverson, Hiding Routing information, in InformationHiding, R. Anderson, Ed., in Lecture Notes in Computer Science. Berlin,Heidelberg: Springer, 1996, pp. 137–150. doi: 10.1007/3-540-61996-8_37.Available at: https://www.doi.org/10.1007/3-540-61996-8_37
[5] D. Chaum,The dining cryptographers problem: Unconditional sender and recipientuntraceability, J. Cryptology, vol. 1, no. 1, pp. 65–75, Jan. 1988,doi: 10.1007/BF00206326. Available at: https://www.doi.org/10.1007/BF00206326

SLIDES

Everyone procrastinates: a Beamer demo
2024-01-31 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
This tutorial delves into the intricacies of Beamer, apowerful LaTeX document class designed for crafting presentations. We willexplore basic and advanced features and customization options. Finally, wewill discover how to use Beamer for creatingposters.

https://overleaf.lincs.fr/read/psmtjjpmchcx#014e88

Understanding quantum computing using Quirk, a drag-and-dropquantum circuit simulator - Quantum
2024-01-24 10:30 - 11:30 | Salle 4A113 - TP @Palaiseau, 19 place Marguerite Perey,Palaiseau, France
Quirk (https://algassert.com/quirk) is a drag-and-drop quantumcircuit simulator that is easy to use and very interesting to understandhow quantum computers works. In this session, I will use this tool toillustrate some quantum paradoxes.

Data Poisoning Attacks in Gossip Learning
2024-01-17 14:00 - 15:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Traditional machine learning systems were designed in acentralized man-ner. In such designs, the central entity maintains boththe machine learningmodel and the data used to adjust the model’sparameters. As data central-ization yields privacy issues, FederatedLearning was introduced to reducedata sharing and have a central servercoordinate the learning of multiple devices.

While Federated Learning ismore decentralized, it still relies on a centralentity that may fail or besubject to attacks, provoking the failure of thewhole system. Then,Decentralized Federated Learning removes the need fora central serverentirely, letting participating processes handle the coordina-tion of themodel construction. This distributed control urges studying thepossibilityof malicious attacks by the participants themselves.

While poisoningattacks on Federated Learning have been extensively stud-ied, theireffects in Decentralized Federated Learning did not get the samelevel ofattention. Our work is the first to propose a methodology toassesspoisoning attacks in Decentralized Federated Learning in both churnfree andchurn prone scenarios. Furthermore, in order to evaluate ourmethodologyon a case study representative for gossip learning we extendedthe gossipysimulator with an attack injector module.

Additionalinformation
This presentation is about a work in submission by AlexandrePham, Maria Potop-Butucaru, Sebastien Tixeuil and Serge Fdida.

Understanding quantum computing using Quirk, a drag-and-dropquantum circuit simulator - Basic
2024-01-17 10:30 - 11:30 | Salle 4A113 - TP @Palaiseau, 19 place Marguerite Perey,Palaiseau, France
Quirk (https://algassert.com/quirk) is a drag-and-drop quantumcircuit simulator that is easy to use and very interesting to understandhow quantum computers works. In this session, Ludovic Noirie will explainthe basics of this tool, illustrating how it woks on very small quantumcircuits.

Authentication through error estimation in QKD
2024-01-10 14:00 - 15:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
The one-time pad is an encryption technique that is provento be unbreakable by an eavesdropper. It relies on a single-use secret keyshared between a sender and a receiver, whose length is that of themessage to be encrypted.

The creation of such a key can be achievedthrough Quantum Key Distribution (QKD), a method based on quantum physicsthat ensures eavesdroppers’ actions can be statistically detected witharbitrarily high probability. It requires a quantum channel for qubittransmission and a classical channel for classical bittransmission.

However, the classical channel is generally authenticatedby classical means using cryptographic hash functions that are not provablysecure. In this paper, we propose for the first time a QKD protocol,based on BB84, that uses quantum error estimation to authenticate bothchannels.

This method relies on the consumption of a smaller pre-sharedkey, and is provably secure thanks to fundamental results in bothinformation theory and quantum physics.

This work is a publicationby Ludovic Noirie and Rémi Varloot (Nokia Bell Labs) at Globecom 2023: https://globecom2023.ieee-globecom.org/technical-program#S1569621407.

D3.js tutorial: animating a card game
2024-01-10 10:30 - 11:30 | Room 4A113, 19 place Marguerite Perey, Palaiseau, France
D3.js is a JavaScript library that facilitates the creation andanimation of HTML and SVG content representing a (possibly dynamic) datastructure. While clearly more involved than off-the-shelf solutions such asChart.js or Highcharts, it also provides more flexibility, allowing us todefine arbitrary representations for our data. In this tutorial, we willlearn the fundamentals of D3.js by creating a (minimalist) animation of acard game.

https://github.com/rvarloot/lincs-d3js

Proving and analysing security protocols with Tamarin Prover
2023-12-20 10:30 - 11:30 | Room 4A113, 19 place Marguerite Perey, Palaiseau, France
Tamarin Prover is an open source model checker for proving andverifying security protocols in the Dolev-Yao symbolic model, initiallydeveloped at the Information Security Institute, ETH Zürich. Theverification algorithms implemented in Tamarin enable unboundedverification and falsification of the security properties of a protocol tobe analysed. Tamarin supports XOR and Diffie-Hellmann exponentiation andhas been used to analyse widely deployed protocols such as TLS 1.3 [1, 2,3], 5G authentication [4, 5, 6] or the IEEE 802.11 WPA2 protocol [7] andits patched version against the KRACK attack [8].

In this session wewill get to grips with the tool, formally model protocols, adversaries,security properties and understand the mathematical logic behind theseproperties. The structure of the presentation follows that of the Tamarinmanual.

The presentation is an adapted material from the TamarinProver's manual and is available under the CC BY-NC-SA 4.0license.

Slides

Prerequisites for the participants who want to usethe tool:
- Windows: install Windows Subsystem for Linux (WSL) -https://learn.microsoft.com/en-gb/windows/wsl/install, then installHomebrew - https://brew.sh/
- macOS & Linux: install Homebrew -https://brew.sh/

Website: https://tamarin-prover.com/
User manual:https://tamarin-prover.com/manual/
Teaching materials:https://github.com/tamarin-prover/teaching
Google Groups:https://groups.google.com/g/tamarin-prover
Source code:https://github.com/tamarin-prover/tamarin-prover
License: GNU GPLv3

Research materials:https://tamarin-prover.com/#research_papers_and_theses

---
References:

[1] C. Cremers, M. Horvat, S. Scott and T. van der Merwe, AutomatedAnalysis and Verification of TLS 1.3: 0-RTT, Resumption and DelayedAuthentication, 2016 IEEE Symposium on Security and Privacy (SP), SanJose, CA, USA, 2016, pp. 470-485, doi: 10.1109/SP.2016.35. Availableat: https://ieeexplore.ieee.org/abstract/document/7546518

[2] V.Stettler, Formally Analyzing the TLS 1.3 proposal, Bachelor thesis, ETHZürich, Switzerland, 2016. Available at:https://ethz.ch/content/dam/ethz/special-interest/infk/inst-infsec/information-security-group-dam/research/software/TLS-1.3_thesis_vincent_stettler.pdf

[3] C. Cremers, M. Horvat, J. Hoyland, S. Scott, and T. van derMerwe, A Comprehensive Symbolic Analysis of TLS 1.3, Proceedings of the2017 ACM SIGSAC Conference on Computer and Communications Security, CCS'17. New York, NY, USA, 2017, pp. 1773–1788. doi:10.1145/3133956.3134063. Available at:https://dl.acm.org/doi/10.1145/3133956.3134063

[4] D. Lanzenberger,Formal Analysis of 5G Protocols, Bachelor thesis, ETH Zürich,Switzerland, 2017. Available at:https://ethz.ch/content/dam/ethz/special-interest/infk/inst-infsec/information-security-group-dam/research/software/5G_lanzenberger.pdf

[5] D.Basin, J. Dreier, L. Hirschi, S. Radomirovic, R. Sasse, and V.Stettler, A Formal Analysis of 5G Authentication, Proceedings of the 2018ACM SIGSAC Conference on Computer and Communications Security, CCS '18.New York, NY, USA, 2018, pp. 1383–1396. doi: 10.1145/3243734.3243846.Available at: https://arxiv.org/pdf/1806.10360

[6] C. Cremers and M.Dehnel-Wild, Component-based formal analysis of 5G-AKA: channelassumptions and session confusion, Network and Distributed System SecuritySymposium (NDSS), 2019, doi: 10.14722/ndss.2019.23394. Available at:https://ora.ox.ac.uk/objects/uuid:650ef867-79e1-476d-a602-e7e28dc64970

[7] C. Cremers, B. Kiesl, and N. Medinger, A Formal Analysis of IEEE802.11's WPA2: Countering the Kracks Caused by Cracking the Counters, 29thUSENIX Security Symposium (USENIX Security 20), 2020, pp. 1–17.Available at:https://www.usenix.org/conference/usenixsecurity20/presentation/cremers

[8] M. Vanhoef and F. Piessens, Key Reinstallation Attacks: Forcing NonceReuse in WPA2, Proceedings of the 2017 ACM SIGSAC Conference on Computerand Communications Security, CCS '17. New York, NY, USA, Oct. 2017,pp. 1313–1328. doi: 10.1145/3133956.3134027. Available at:https://papers.mathyvanhoef.com/ccs2017.pdf

Binomial Line Cox Processes - Modeling Streets Across a City
2023-12-13 14:00 - 15:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Acknowledgment: Joint work with Martin Haenggi (University ofNotre Dame)

The current analysis of wireless networks whose transceiversare confined to streets is largely based on Poissonian models, such asPoisson line processes and Poisson line Cox processes. We demonstrateimportant scenarios where a model with a finite and deterministic number ofstreets, termed the binomial line process (BLP), is more accurate. Wecharacterize the statistical properties of the BLP and the correspondingbinomial line Cox process (BLCP) and apply them to analyze the performanceof a network whose access points (APs) are deployed along the streets of acity. In order to obtain a fine-grained insight into the networkperformance, we derive the meta-distribution of the signal-to-interferenceand noise ratio (SINR). Accordingly, we investigate the mean local delayin transmission and the density of successful transmissions. Thesemetrics, respectively, characterize the latency and coverage performanceof the network and are key performance indicators of next-generationwireless systems.

Bio:
Gourab Ghatak is an Assistant Professor at theDepartment of Electrical Engineering at IIT Delhi, where he is alsoaffiliated with the Bharti School of Telecommunication Technology andManagement. His research interests are stochastic geometry, MAC-PHYcross-layer issues in beyond 5G, and machine learning for wirelesscommunications.

Ensemble distillation for robust model fusion in federated learning
2023-12-13 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Federated Learning (FL) attempts to protect the privacy of theparticipants in the scheme by uploading locally-trained models from edgedevices to a server, where they get combined into a global model andredistributed to the edge devices. In the established FL literature, thiscombination usually happens by averaging, which appears to limit theaccuracy of the global model and introduces challenges in applying thescheme to heterogeneous devices with different model architectures.

Thepaper we will present in this session, "Ensemble distillation for robustmodel fusion in federated learning", introduces model fusion techniquesbased on knowledge distillation that enable the simultaneous use of variouslocal model sizes / architectures. Distillation also drastically improvesthe global accuracy compared to average-based methods such as FedAVG -still without compromising users' data privacy. The proposed scheme,FedDF, is faster to train and requires fewer communication rounds thanpreviously published FL techniques. We liked this paper because itintroduces a couple of nifty ideas that might also be profitably applied inother FL scenarios.

Reference

Tao Lin, Lingjing Kong, Sebastian U.Stich, and Martin Jaggi. Ensemble distillation for robust model fusion infederated learning. In Proceedings of the 34th International Conference onNeural Information Processing Systems, NIPS’20, pages 2351–2363, RedHook, NY, USA, December 2020.

Wireless Network Optimization: From Algorithm Design to FieldTrials
2023-12-08 10:00 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
An overview of François Durand and Lorenzo Maggi's activitieson beamforming, energy savings, radiation exposure mitigation, andscheduling over the last few years.

François' slides

Lorenzo'sslides

APT: managing software under Debian-based GNU/Linux distributions
2023-12-06 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
APT (Advanced Package Tool) is the package manager used underDebian and any Linux distribution based on Debian (Ubuntu, Mint, etc.).APT is used needed to search, install, remove and update packages. It isalso used to upgrade the system release.

The tutoriel will present allthe related notions (releases, mirror, file organization). Then, it willshowcase many practical use cases and the corresponding commands (apt,apt-file, aptitude, dpkg, deborphan, etc).

The participants areencouraged to install virtualbox and download an iso of debian to trythemselves the practicals.

[1] https://www.virtualbox.org/
[2]https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/debian-12.2.0-amd64-netinst.iso

apt.md

Pushing Programmability to the Edge and beyond: the Evolutions ofMobile Networks Architecture towards Smart Radio Environments
2023-12-01 10:00 - 12:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
This talk precede the talk of Prof. Andrea Araldo"Technical and economic strategies for Multi-Tenant Edge Computing".

Theevolution of the architecture of Mobile Radio Networks is going in thedirection of "softwarization" of network functions and the disaggregationof the Radio Access Network (RAN).

Moving from specialized hardware togeneral purpose servers for a fully distributed system requires deepchanges in the physical infrastructure with a hierarchy of mini datacenters to be deployed, but creates interesting synergies with theevolution of the Cloud architecture which is pushing computation towardsthe edge of the network.

Embracing the cloud paradigm does not onlyallows to virtualize network functions but also create opportunities toopen programmable interfaces and to implement intelligent controlstrategies able to optimize resources and adapt to traffic needs.

Atthe extreme periphery of the radio access network the need to use of highfrequencies is also modifying the architecture with new smart radio devices(such as Reflective Intelligent Surfaces or Network Controlled Repeaters)that can also be controlled through open programmable interface.

Theseminar will present these evolution trends of the architecture of radionetworks and pinpoint the research opportunities for defining newalgorithms for optimizing network behavior.

Phd Thesis Defense : Artificial Intelligence for ResourceAllocation in Multi-Tenant Edge Computing
2023-11-30 14:00 - 15:00 | Amphi 2, 19 place Marguerite Perey, Palaiseau, France
We consider in this thesis Edge Computing (EC) as amulti-tenant environment where Net- work Operators (NOs) own edgeresources deployed in base stations, central oces and/or smart boxes,virtualize them and let third party Service Providers (SPs) - or tenants -dis- tribute part of their applications in the edge in order to serve therequests sent by the users. SPs with heterogeneous requirements coexist inthe edge, ranging from Ultra-Reliable Low Latency Communications (URLLC)for controlling cars or robots, to massive Machine Type Communication(mMTC) for Internet of Things (IoT) requiring a massive number of connecteddevices, to media services, such as video streaming and Augmented/VirtualReality (AR/VR), whose quality of experience is strongly dependant on theavailable re- sources. SPs independently orchestrate their set ofmicroservices, running on containers, which can be easily replicated,migrated or stopped. Each SP can adapt to the resources allocated by theNO, deciding whether to run microservices in the devices, in the edgenodes or in the cloud. We aim in this thesis to advance the emergence ofreal deployments of the “true” EC in real networks, by showing theutility that NOs can collect thanks to EC. We believe that this cancontribute to encourage concrete engagement and investments engagement ofNOs in EC. For this, we point to design novel data-driven strategies thatefficiently allocate resources between heterogeneous SPs, at the edgeowned by the NO, in order to optimize its relevant objectives, e.g.,cost reduction, revenue maximization and better Quality of Service (QoS)perceived by end users, in terms of latency, reliability and throughput,while satisfying the SPs requirements.

This thesis presents aperspective on how NOs, the sole owners of resources at the far edge(e.g., at base stations), can extract value through the implementation ofEC within a multi-tenant environment. By promoting this vision of EC and bysupporting it via quantitative results and analysis, this thesisprovides, mainly to NOs, findings that can influence decision strategiesabout the future deployment of EC. This might foster the emergence of novellow-latency and data-intensive applications, such as high resolutionaugmented reality, which are not feasible in the current Cloud Computing(CC) setting.

Another contribution of the thesis it that it providessolutions based on novel methods that harness the power of data-drivenoptimization. We indeed adapt cutting-edge tech- niques from ReinforcementLearning (RL) and sequential decision making to the practical problem ofresource allocation in EC. In doing so, we succeed in reducing thelearning time of the adopted strategies up to scales that are compatiblewith the EC dynamics, via careful design of estimation models embedded inthe learning process. Our strategies are conceived in order not to violatethe confidentiality guarantees that are essential for SPs to accept runningtheir computation at the EC, thanks to the multi-tenant setting.

Reinforcement Learning and optimization for an energy and resourceefficient 5G slicing
2023-11-29 14:00 - 15:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
This talk, which will be the rehearsal of my thesis,addresses resource allocation problems in 5G networks. Our objective is toleverage network slicing (e.g. the set of techniques based onvirtualization and network softwarization which allows the network operatorto provide different amounts of resources to different tenants) in order toto improve the energy-efficiency and resource consumption of 5G networks,while guaranteeing Quality of Service constraints. To do so, we formulateand solve optimization problems at the different domains of the network: Weare first concerned with the placement of slices in the core network. Tosolve the problem, a new approach combining Monte Carlo Search andNeighborhood Search is formulated.

We show it accepts more core slicesthan state-of-the-art approaches for the core network placement problem.Then we shift the focus to energy efficiency in resource allocation in 5Gnetworks shared between Physical Network Operators (PNOs) and MobileVirtual Network Operators (MVNOs). This framework jointly considerssoftware component placement, user request routing, and resourcedimensioning while meeting Service Level Agreements (SLAs) based on latencyand reliability constraints.

Through Column Generation, we obtain exactsolutions, demonstrating energy savings of up to 50\% in real networkscompared to existing placement or resource minimization algorithms.Finally, we delve into the realm of energy optimization in IntegratedAccess and Backhaul (IAB) networks, a key component of dense 5Gdeployments. Leveraging the Open Radio Access Network (O-RAN) framework,our model minimizes active IAB nodes while ensuring a minimum capacity forUser Equipment (UE).

Formulated as a binary nonlinear program, thisapproach reduces RAN energy consumption by 47\%, while maintainingQuality-Of-Service for UEs. Overall, this thesis provides novel algorithmsfor improving resource and energy efficiency of 5G network slicing. Suchimprovement is studied in different parts of the network, from the core upto the access network.

Coverage and Capacity of Joint Communication and Sensing inWireless Networks
2023-11-29 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Joint Communication and Sensing (JCAS) is a technology aimingat integrating both communication and sensing in one single system. Itrequires the reevaluation of network performance from a multi-objectiveperspective.

In this reading group session, we will see how tocharacterize and quantify the performance of JCAS using some informationtheoretic tools. To this end, we'll need to give a formulation of sensingand communication coverage and capacity, which will be our metrics forperformance. Using stochastic geometry, we'll employ a network model thatallows us to derive expressions for SINR and then deduce tractable boundsfor making numerical computations.

Référence :
Coverage and Capacityof Joint Communication and Sensing in Wireless Networks (2022) - NicholasR. Olson, Jeffrey G. Andrews, and Robert W. Heath, Jr.

From Data Networks to Intelligent Networks: In-Network Computing'sPromise
2023-11-22 14:00 - 15:00 | Room 4A113, 19 place Marguerite Perey, Palaiseau, France
In-network computing technologies encompass a range ofapproaches and tools designed to enable computation and data processingwithin the network infrastructure, such as Network Interface Card (NIC),and switches. The se technologies aim to reduce latency, improve networkefficiency, and enhance the performance of distributed applications.

Inthis talk, we will review the hardware and software technologies currentlyaccessible forin-network computing. In our discussion, we will outline theobstacles encountered in in-network computing and delve into theopportunities that this technology presents. Additionally, we will explorea selection of applications that leverage in-networkcomputing.

BIO
Masoud Hemmatpour is a Research Scientist at SimulaResearch Laboratory (SRL) and a postdoctoral fellow at the ArcticUniversity of Norway (UiT). His research interests include memory accessover High-Performance Computing (HPC) interconnect (e.g., InfiniBand,RoCE, and PCIe) and in-network computing.

Gossip learning with linear models on fully distributed data
2023-11-22 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
In the realm of distributed machine learning, a novel approachcalled Gossip Learning, was presented in 2013 by the paper "GossipLearning with Linear Models on Fully Distributed Data"[1]. Gossip Learningintroduces a decentralized communication framework among nodes, allowingthem to collaboratively train a machine learning model without the need fora central aggregator. This decentralized paradigm offers advantages inscalability, fault tolerance, and privacy preservation.

Thepresentation will delve into the key components of Gossip Learning,highlighting the communication protocol that enable nodes to exchangeinformation in a gossip-like fashion, the convergence properties of GossipLearning and its resilience to node failures.
Additionally, thepresentation will discuss comparisons with traditional centralized learningapproaches (and federated learning approaches).

References:

[1]Ormándi, R., Heged?s, I., & Jelasity, M. (2013). Gossip learningwith linear models on fully distributed data. Concurrency and Computation:Practice and Experience, 25(4), 556-571.
https://arxiv.org/abs/1109.1396

Twin talk part 2 : 3GPP Standardization at Nokia Bell Labs and ItsInteractions with Research
2023-11-17 14:00 - 16:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Luis Uzeda-Garcia and Stefano Paris will survey the topics ofcurrent and future interest to 3GPP.

#SystemX : Attacks & trust in connected networks: secure behavioralmodels
2023-11-16 14:00 - 15:00
A System X seminar. Please find all details and theregistration form on the organiser's website:

https://www.irt-systemx.fr/evenements/lyes-khoukhi-animera-un-seminarsystemx-le-16-novembre-2023/

Developing Python packages with Poetry and Package Helper 3
2023-11-15 10:30 - 11:30 | Salle 4B01, 19 place Marguerite Perey, Palaiseau, France
When you develop a Python project, it is highly recommendedthat you design it as a Python package, which gives you access to avariety of powerful development tools. With Package Helper 3(https://balouf.github.io/package-helper-3/), it is easy and fast to doit! Things will go this way:

PH3 helps you to create the filestructure of your package in less than a minute.
Using PyCharm, you canout-of-the-box:

Generate the documentation locally,
Run tests,
Have a “coverage” page, which displays what parts of the package arecovered by the tests.

Your project is hosted on GitHub, which isconfigured to automatically run the tests with several versions of Pythonand to automatically generate and publish the documentation.
Whendesired, GitHub publishes your package on PyPI, so that any Python usercan install it.

Under the hood, the management of your package will beperformed by Poetry, a modern tool that unifies and simplifies the tasksrequired to develop a package, such as installing a dedicated developmentenvironment, making installation easy for other users, building wheels,managing and updating dependencies...

Tutorial:https://balouf.github.io/package-helper-3/tutorial.html.

Performance Analysis of RIS-assisted MIMO-OFDM Cellular NetworksBased on Matern Cluster Processes
2023-11-08 14:00 - 15:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Reconfigurable Intelligent Surfaces (RIS) technology are apromising physical-layer candidate for sixth-generation (6G) cellularnetworks. This paper provides a system-level performance assessment ofRIS-assisted multi-input multi-output (MIMO) cellular networks in terms ofdownlink coverage probability and ergodic rate.

To capture theinherent randomness in the spatial deployments of both Base Stations (BSs)and RISs, we propose a new stochastic geometry model for such systemsbased on the Matern Cluster Process (MCP). This model consists inrandomly distributed RISs around BSs, whose placement is according to aPoisson Point Process (PPP). The RISs provide the multipath diversity andthe multiple antenna receiver provide the antenna diversity.

The systemis assumed to use the orthogonal frequency division multiplexing (OFDM)technique to modulate the former and employ the maximal ratio combining(MRC) technique at the receiver to exploit the latter. We show that thecoverage probability and the ergodic rate can be evaluated when consideringRISs operate as batched powerless beamformers.

The resulting analyticalexpressions provide a generic methodology to evaluate the impact of keyRIS-related parameters, such as the size of RIS and the density of nodes,on system level performance. Numerical evaluations of the analyticalexpressions and Monte-Carlo simulations jointly validate the proposedanalytical approach and provide valuable insights into the design of futureRIS-assisted radio cellular networks.

The Projection Method: A Unified Framework for Community Detection
2023-11-08 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
We present the class of projection methods for communitydetection that generalizes many popular community detection methods. Inthis framework, we represent each clustering (partition) by a vector on ahigh-dimensional hypersphere. A community detection method is a projectionmethod if it can be described by the following two-step approach:

thegraph is mapped to a query vector on the hypersphere;
the query vectoris projected to the set of clustering vectors.

This last projection stepis performed by minimizing the distance between the query vector and theclustering vector, over the set of clusterings. This setup generalizesmany popular community detection methods, including the maximization ofmodularity, Markov stability and the likelihood of several models.

Weshow that these different methods suffer from the same granularity problem:they have parameters that control the granularity of the resultingclustering, but choosing these to obtain clusterings of the desiredgranularity is nontrivial. We provide a general heuristic to address thisgranularity problem, which can be applied to any projection method.Finally, we show how, given a generator of graphs with communitystructure, we can optimize a projection method for this generator in orderto obtain a community detection method that performs well on thisgenerator.

Twin talk part 1 : 3GPP Standardization at Nokia Bell Labs and ItsInteractions with Research
2023-11-03 10:00 - 12:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France

Opportunistic Federated Learning: An Exploration of EgocentricCollaboration for Pervasive Computing Applications.
2023-10-25 10:30 - 11:30 | Salle 4B01, 19 place Marguerite Perey, Palaiseau, France
Federated learning (FL) is an emerging distributed learningtechnique, through which models can be trained using the data collectedby user devices in resource-constrained situations while protecting userprivacy. However, FL has three main limitations: First, the parameterserver (PS), which aggregates the local models that are trained usinglocal user data, is typically far from users. The large distance mayburden the path links between the PS and local nodes, thereby increasingthe consumption of the network and computing resources. Second, userdevice resources are limited , but this aspect is not considered in thetraining of the local model and transmission of the model parameters.Third, the PS-side links tend to become highly loaded as the number ofparticipating clients increases. The links become congested owing to thelarge size of model parameters.
One of the kind in Federated Learning,opportunistic federated learning, in which individual devices belonging todifferent users seek to learn robust models that are personalized to theiruser’s own experiences. However, instead of learning in isolation,these models opportunistically incorporate the learned experiences of otherdevices they encounter opportunistically.

Modeling of LEO Satellite Constellation and Downlink AnalysisLeveraging Cox Point Processes
2023-10-18 15:30 - 16:30 | Salle 4A113 - TP @Palaiseau, 19 place Marguerite Perey,Palaiseau, France
This work develops an analytical framework for downlink lowearth orbit (LEO) satellite communications, leveraging tools fromstochastic geometry. We propose a tractable approach to the analysis ofsuch satellite communication systems accounting for the fact thatsatellites are located on circular orbits. We accurately characterize thisgeometric property of such LEO satellite constellations by developing a Coxpoint process model that jointly produces orbits and satellites on theseorbits. Our work differs from existing modeling studies that have assumedsatellites' locations as completely random binomial point processes. Forthis newly developed Cox model, we derive the outage probability of theproposed network and the distribution of thesignal-to-interference-plus-noise ratio (SINR) of an arbitrarily locateduser in the network. By presenting various key network performance metricsas functions of key network parameters, this work allows one to assess thestatistical properties of downlink LEO satellite communications and thuscan be used as a system-level design tool.

Application of Chaos Engineering Techniques to Protect Cloud-basedIoT Ecosystems
2023-10-18 14:00 - 15:00 | Salle 4A113 - TP @Palaiseau, 19 place Marguerite Perey,Palaiseau, France
System security represents a big challenge for manyorganizations, and it must be specifically handled when a system isintended to be deployed in a cloud environment. Cloud environments providemultiple security services that run over a Shared Responsibility Model thatrequires the participation of the cloud provider and the customer. Thus,this talk presents an architecture based on Artificial Intelligence tosupport the finding of system threats and errors in an early stage and onSecurity Chaos Engineering methodology to reliably test the existence ofsuch errors. This proposed architecture may help orientate better systemdesigns and contribute to building holistic security. A particular use caseis described to show how the proposal can be applied to protect Cloud-basedIoT Ecosystems.

Short Bio
Daniel Díaz-López holds a Ph.D. in ComputerScience from the University of Murcia (Spain), is visiting professor atNew York University (NYU) and assistant professor at the University ofRosario. He has been professor for more than 7 years, teaching differentcybersecurity courses: Ethical Hacking, Security in the SoftwareDevelopment Life Cycle, Forensic Analysis and Incident Management, ThreatIntelligence, Security in Enterprise Architecture, ArtificialIntelligence for Cybersecurity, among others. Daniel is a cybersecurityresearcher with different publications in journals and conferences aroundtechniques for cyber threat intelligence, privacy-preserving mechanisms,secure software development lifecycle, techniques in ethical hacking, andsecurity for the Internet of Things (IoT).

Tikz introduction: how to draw a platypus
2023-10-18 10:30 - 11:30 | Room 4A113, 19 place Marguerite Perey, Palaiseau, France
Emma Caizergues will present Tikz, which is a language forproducing vector graphics.
In particular, I will show the method to drawgraph-like figures (graphs, automata, trees, etc) and to plotfunctions.
No background in Tikz is required. This presentation isdesigned as a tutorial to take your first steps with Tikz.

Click here tofind the support of the presentation : tikz intro

Critical real-time in cellular networks
2023-10-13 10:00 - 12:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France

Quantum Networks for 5-Year-Old Network Researchers
2023-10-11 10:30 - 11:30 | Room 4A 101, 19 place Marguerite Perey, Palaiseau, France
The aim of this talk is to present a quick overview of quantumnetworks. It will focus on their uses, how they operate, and mostimportantly how they differ from “classical” networks, and the newnetworking challenges this provides. Rest assured: no understanding ofquantum physics/computing is required, nor will you gain any from thistalk!

Slides

Launch of Communication Network Day
2023-10-06 09:30 - 11:30
This semester, LINCS is organizing regular meetings oncommunication networks. These meetings take place on Fridays and are opento all LINCS members interested in these topics. The aim is to fosterinteractions among LINCS partners. This particular semester also allowsthem to engage with visiting Prof. Catherine Rosenberg from the Universityof Waterloo in Canada.

Nous nous réunissons vendredi 6 à 9h30 en Salle4B01 dans le but de lancer de nouvelles activités du LINCS dans le domainedes réseaux de communications.

Nous prévoyons pour cette premièreréunion 20 minutes de présentation de Catherine Rosemberg et 5 minutespour chacun d'entre vous.

Toward Quantum Explainable AI: A Quantum Algorithm for ShapleyValue Estimation
2023-10-04 14:00 - 15:00 | Room 4A101, 19 place Marguerite Perey, Palaiseau, France
In the classical context, the cooperative game theory
conceptof the Shapley value has been adapted for post hoc explanations
of MachineLearning models. This approach does not easily translate to
eXplainableQuantum Machine Learning. Finding Shapley values can be
highlycomputationally complex. In this joint work with Prof. Michel
Barbeau(Carleton University) and Prof. Joaquin Garcia- Alfaro(Télécom
SudParis), we propose a quantum algorithm which can extractShapley
values within some confidence interval. Our results performin
polynomial time. We demonstrate the validity of our approachunder
specific examples of cooperative voting games.

Bio
Iain Burge isa research assistant at Carleton University
working in the emerging fieldof quantum explainable AI. He has an
undergraduate degree in cognitivescience with a concentration in
computation and minor in mathematics.

Colosseum - A hands-on introduction to software defined radio basednetwork emulation
2023-10-04 10:30 - 11:30 | Salle 4A101 - Palaiseau, 19 place Marguerite Perey, Palaiseau,France
Abstract: We will have a session on the Colosseum SDN-basedemulation platform, which lies at the intersection of software-definedradio (SDR) and advanced network emulation technology. The Colosseumplatform offers a fresh approach to wireless network experimentation,making use of genuine radio hardware and advanced channel emulation toestablish a versatile and realistic testing environment.
In this talk, wewill introduce you to the Colosseum platform and demonstrate how itempowers researchers and engineers to emulate complex wireless scenarios.We will dive into the practical aspects of using Colosseum to emulate a 5Gnetwork, with various scenarios, leveraging openairinterface toinstantiate a real network, and perform data collection. This session willequip you with the knowledge and skills needed to harness the power ofColosseum for your own network experiments. If we have time we will alsocover the use of Colosseum for experimenting with other radio technologiessuch as WiFi.

Resources

An introduction to Colusseum can be foundhere:
https://arxiv.org/pdf/2110.10617.pdf

Tutorial material onColosseum can be foundhere:
https://github.com/colosseum-wiot/colosseum-school-2023
inparticular, slides arehere:
https://github.com/colosseum-wiot/colosseum-school-2023/tree/main/slides

Furtherresources:
https://github.com/wineslab/colosseum-scope
https://openrangym.com/

Phd Thesis Defense : Unimodularity in Random Networks: Applicationsto the Null Recurrent Doeblin Graph and Hierarchical Clustering
2023-09-26 15:00 - 17:00 | Inria, salle Philippe Flajolet, 2 rue Simone Iff, Paris,75012, France
This thesis is based on the notion of unimodularity in thecontext of random networks and explores two domains of application:Coupling from the Past in the null recurrent case based on the associatedDoeblin Graphs and unsupervised classification based on hierarchicalclustering on point processes. The first part of this thesis focuses on theproperties of a specific random graph called the Doeblin Graph, which isassociated with the Coupling from the Past algorithm used for perfectsampling of the stationary distribution of a Markov Chain. In theirreducible, aperiodic, and positive recurrent case, it is known thatthe Bridge Doeblin Graph, a subgraph of the Doeblin Graph, is an infinitetree that is unimodularizable and contains a unique biinfinite path. Thisbi-infinite path plays a crucial role in constructing a perfect sample ofthe stationary state of the Markov chain. This thesis extends the study tothe null recurrent case, where it is shown that the Bridge Doeblin Graphis either an infinite tree or a forest composed of a countable collectionof infinite trees. In the former case, the infinite tree possesses asingle end, is not generally unimodularizable, but exhibits localunimodularity. These properties are leveraged to investigate the stationaryregime of measure-valued random dynamics on the Bridge Doeblin Tree,particularly the taboo and potential random dynamics. The second part ofthis thesis introduces a novel hierarchical clustering model tailored forunsupervised classifications of datasets which are countably infinite.Clustering, a widely used technique in unsupervised learning, aims toidentify groups within a dataset based on element similarities. Theproposed algorithm employs multiple levels of clustering, constructingclusters at each level using nearest-neighbor chains of points or clusters.This algorithm is applied to the Poisson point process, and it is proventhat the clustering algorithm defines a phylogenetic forest on the Poissonpoint process, which is a factor of the point process and is thereforeunimodular. Various properties of this random forest, such as the meansizes of clusters at each level or the mean size of the cluster of atypical node, are examined.

Phd Thesis Defense : Dynamiques markoviennes à base de processusponctuels et leurs applications
2023-09-25 14:00 - 17:00 | Inria, salle Jacque-Louis Lion, 2 rue Simone Iff, Paris, 75012, France
In this thesis, we are interested in mathematical models ofphenomena that can be interpreted as network dynamics. This includes forexample neuron population models in which neurons interact at random timeswith their neighbors or epidemics propagation where infected or susceptibleindividuals move from town to town. The mathematical description of suchphenomena generally requires a compromise between physical or biologicalrelevance and mathematical tractability. The main focus of this work is theelaboration of mathematical proofs to justify the introduction of modelstaking into account the geometry of the underlying networks whilstpreserving tractability. The main mathematical tool for that purpose is thereplica-mean-field, which consists in copies of the studied networkbetween which interactions are routed randomly. The main results of thisthesis concern the behavior of such a dynamical system when the number ofreplicas goes to infinity. In various settings, we show that it concergesto dynamics under the Poisson Hypothesis, that is, interaction times arereplaced by independent Poisson processes, which allows to obtain closedforms in certain models.

Phd Thesis Defense : Records of stationary processes and unimodulargraphs
2023-09-18 14:00 - 17:00 | Inria, salle Gilles Hahn, 2 rue Simone Iff, Paris, 75012,France
Consider a navigation rule defined on a graph that maps everyvertex of
the graph to a vertex in such a way that the navigation rulecommutes
with every automorphism of the graph. It is to say that thenavigation
rule applied to the vertices remains the same after takingany
automorphism of the graph. Such a navigation rule is said to havethe
covariance property. This study delves into a collection ofsuch
covariant navigation rules, indexed by locally finite graphs,and
subject to a measurability condition. This ensemble of rules is termeda
vertex-shift. More generally, one can consider vertex-shiftson
networks, graphs that have labels on edges and on vertices.A
vertex-shift induces a dynamic on the space of locally finiterooted
networks. The central focus of this work lies in investigatingthe
dynamic associated to a specific navigation rule called therecord
vertex-shift. It is defined on the trajectories of any onedimensional
discrete random walk whose increments have finite mean and therandom
walk can jump only one step to the left. Additionally, the workincludes
several notable results concerning record vertex-shifts appliedto
processes with stationary increments. The thesis also containsresults
on more general vertex-shifts on unimodular networks.

ERC NEMO Workshop : 8 Days on Network Mathematics
2023-09-18 - 2023-09-27 | INRIA Paris, 2 rue Simone Iff, Paris., France
Between September 18th and September 27th, our partner INRIAis hosting a two-week informal international workshop with a primary focuson stochastic networks, spatial stochastic processes, and their dynamicaspects. The workshop will feature three thesis defenses and a series ofone-hour lectures delivered by active researchers in this domain.

Titlesand abstracts
Clic here to find all details and registration form on theorganiser's website.

2023 LINCS Annual Workshop
2023-07-05 09:30 - 2023-07-06 18:00 | Amphi Rose Dieng, 19 place Marguerite Perey, Palaiseau, France
The LINCS organizes its Annual Workshop with the ScientificCommittee.
**PROGRAM** (<= click)
§ LINK to the SLIDESFOLDER

A 2-day workshop with:

LINCS members"scientific highlights"
Scientific Committee members invited talks
PhD students "elevator pitch" session + posters

We'll have coffe-breaksjust outside the Amphi Rose Dieng and we'll have lunch at the cantine ofTélécom-Paris.

On the evening of Wednesday July 5th we'll have ashuttle bringing us from Palaiseau to Jussieu (Paris 5e arr.) for a dinnercocktail on top of the Zamansky Tower.
Confirmed talks by members of theScientific Committee who will be in Palaiseau:

Prof. Marco AjmoneMarsan (Politecnico di Torino)
Prof. Nick Bambos (Stanford University)
Prof. Roch Guerin (Washington University in Saint Luis)
Prof. PatrickThiran (EPFL)

Confirmed talks by members of the Scientific Committee whowill be connected via Zoom:

Prof. Leandros Tassiulas (YaleUniversity)

Scientific Committee members' titles+abstracts:
Prof. MarcoAjmone-Marsan (Politecnico di Torino)
Titolo: Equalizing end user accessto edge-based services

Abstract: We consider a portion of a RAN whereend-users access services that imply the issue of a request through theirassociated base station (BS), followed by a computation on one of theavailable in-network computing facilities, and finally by the return ofthe result of the computation to the end-user who issued the request. Theresult must be returned within a specified latency deadline in order to beuseful.

Since not all BSs are equipped with a computing facility, someend-users may be disadvantaged, because they are associated with a BS fromwhich the delay for a service request to reach a computing facility and forthe results of the computation to come back is longer.
Aiming at uniformend-user satisfaction, network operators should strive to on the one handreduce differences in achieved end-user performance, while on the otherobtain an efficient use of network resources.
With simple analyticalmodels we investigate the effectiveness of light network managementalgorithms, consisting in carefully choosing the routing probabilities ofservice requests toward one of the available computing facilities. We arguethat at least some of such light network management algorithms should becompatible with the very stringent European Network Neutrality rules, andwe show that they allow a good trade-off between overall resourceutilization and equal performance experienced by end-users.

Prof. NickBambos (Stanford University)
Title: Controlling Epidemics in RandomEnvironments via Testing

Abstract: We model epidemic spreading (e.g.of pathogens, rumors/misinformation) in a population within a largeregion. We allow for mobility of infected individuals, who can infectothers while roaming around. We distribute testing centers around theregion, where individuals testing positive are quarantined. Infected andrecovered individuals cannot be reinfected in the current epidemic wave.The infection transmission rate (infectivity) is a random field over theregion, for example, due to various counter-measures (e.g. masking andsocial distancing in the case of airborne pathogens).We infinitesimallyseed the infection in the large region and explore conditions under whichit inherently spreads (as opposed to dying out). We observe that theaverage infectivity is not enough to characterize spreading andfluctuations do matter; indeed, even under subcritical averages,overcritical infectivity fluctuations can cause the infection to spread. Wethen focus on the impact of testing center density on suppressing anepidemic that has the inherent potential to spread. Finally, we discusshow to optimize testing vs. recovery resources.

*Joint work with PetrosMeramveliotakis and Prof. Aris Moustakas (Univ. of Athens, Greece) andKyriakos Lotidis (Stanford).

Prof. Roch Guerin (WashingtonUniversity in Saint Luis)
Title: On the benefits of proactively changingtraffic profiles*§

Abstract: Token buckets are commonly used tospecify traffic profiles and there is a growing number of networkenvironments where hard delay bounds are required (e.g., as in the DetNetor TSN standards). In this talk, we explore the extent to which it maybe beneficial to modify up-front the traffic profiles originally specifiedby users, i.e., "reprofile" them, while still delivering the end-to-enddelay bounds they require albeit with fewer network resources (lessbandwidth). The answer depends on the type of schedulers available in thenetwork, and in the degenerate one-hop case, it is known that reprofilingis of no benefit when optimal schedulers (EDF) are available. We explorewhether this also holds in a more general network setting and demonstratethat it does not. However, devising optimal reprofiling solutions,unfortunately, appears intractable. As a result, we explore andevaluate heuristics for networks with both EDF and FIFO schedulers. Inthe latter case, a simple strategy appears to perform well.

* Jointwork with Jiaming Qiu (WashU), Henry Sariowan (Google), and Jiayi Song(WashU, now at ByteDance)

§Some of this work is still inprogress

Prof. Patrick Thiran (EPFL)
Title: Source location inrandom networks: the noisy case.

Abstract: Last year, I surveyed recentresults on the location of the source of a diffusion or of an epidemics ina network, given the infection data gathered at some of the nodes, whenthe propagation delays along the edges of the network are deterministic. Inthis follow-up talk, I will survey some early results on the more complexcase, when propagation delays are i.i.d. Gaussian random variables. Wecompare two sensor placement strategies: either all the sensors are placedat once, before the diffusion starts (off-line placement) or they areplaced sequentially, as the diffusion unfolds in the network (on-lineplacement). The on-line placement strategy consumes obviously fewer sensorsthan an off-line placement, but the difference is very small when thepropagation delays are deterministic and the network is an Erdos-Renyirandom graph. In contrast, when the propagation delays have a sufficientlylarge variance, the difference can be huge: from the order of n to log logn, for a linear graph of n nodes. This is a joint work with Gergely Odorand Victor Lecomte.
LINCS members scientific highlights:
francoisbaccelli (inria)
Title: Cox Point Processes for Multi-Altitude LEOSatellite Networks

Abstract: We propose a simple analytical approach todescribe the locations of low earth orbit (LEO) satellites based on a Coxpoint process. We develop a variable-altitude Poisson orbit process byaccounting for the fact that satellites are always located on circularorbits and these orbits may have different altitudes. Then, the satelliteson these orbits are modeled as the Poisson point processes conditionally onthe orbit process. For this model, we derive the distribution of thedistance to the nearest visible satellite, the outage probability, theLaplace functional of the proposed satellite Cox point process, and theLaplace transform of the interference under a general fading. The derivedstatistics allow one to evaluate the performance of such LEO satellitecommunication systems as functions of networkparameters.

LUDOVIC NOIRIE (Nokia)
Title: Quantum networkingat LINCS

Abstract: Quantum networking is an emerging scientific domain.Quantum networks are distributed systems of quantum devices that utilizefundamental
quantum mechanical phenomena such as superposition,entanglement, and
quantum measurement to achieve capabilities beyond whatis possible with
classical networks. The potential applications of quantumnetworks are
quantum cryptography (Quantum Key Distribution), quantumconsensus,
privacy-preserving quantum computing or distributed quantumcomputing
applications. In this talk, we will describe the past, currentand
future activities at LINCS related to this prospective researchdomain
on quantum networking.

LEONARDO LINGUAGLOSSA(Télécom-Paris)
Title: Inference of network characteristics usingnon-invasive data exploration

Abstract: Recent years witnessed a trendof "softwarization" of network components. Instead of static, expensivehardware, operators have started to adopt a more flexible approach basedon Virtual Network Functions. This paradigm (aka Network FunctionVirtualization) advocates implementing network middleboxes such asfirewalls or NATs as pieces of software to be deployed and executed oncommercial off-the-shelf (COTS) hardware. This has boosted the developmentof several packet processing frameworks and software switches, which shownowadays multi 10-Gbps capabilities in COTS servers. In parallel, networksystems are increasingly adopting machine learning (ML) techniques to solvecomplex networking tasks such as traffic classification or resourceallocation.

As ML techniques require a large amount of data to becollected for both training and validation, when done in software, suchmeasurements can highly affect the measured values, thus biasing thecollected data. The intensity of this becomes stronger when measurementsare taken close to the data path. Second, even after the training phase,complex model calculations may require dedicated hardware such as externalGPUs or custom hardware designed for neural network processing such as TPUsor VPUs.
In this talk, we present a novel approach based on non-invasivedata collection relying on pure software.

Our methodology consists in(i) low-impact network measurements with both direct and indirectobservations; (ii) inference/predictive modeling of a complete system withML and/or classical approaches; (iii) deployment of low-resource modelsfor runtime query/action operations and automated recovery. The project(acronym: IONOS-DX) has received an individual grant from the ANR (FrenchAgency of Research).

ALONSO SILVA (Nokia)
Title:Predicting network hardware faults through layered treatment of alarmslogs

Abstract: Maintaining and managing ever more complextelecommunication networks is an increasingly complex task, which oftenchallenges the capabilities of human experts. There is a consensus both inacademia and in the industry on the need of enhancing human capabilitieswith sophisticated algorithmic tools for decision-making, with the aim oftransitioning towards more autonomous, self-optimizing networks. We aim atcontributing to this larger project. We tackle the problem of detecting andpredicting the occurrence of faults in hardware components in a radioaccess network, leveraging the alarm logs produced by the networkelements. We design a range of algorithmic solutions, and we test them onreal data, collected from a major telecommunication operator. We are ableto predict the failure of a network component, with satisfying precisionand recall.

TIMUR FRIEDMAN (Sorbonne)
Title: Towards An Open EdgeCloud

Abstract: Cloud services are moving to the edge. With 5G, it isenvisaged that telecom operators will have their own data centers. Serviceshosted in these data centers will be closer to their customers than theywould be if they were hosted in classic large centralized data centers.These services will enjoy: lower latency, higher bandwidth, and nointermediate parties along the path. Quality of service will be higher,and the responsibility for maintaining that quality of service will beclearer. At least, that is the vision. But much of the architecture ofthis future edge cloud remains to be conceived. We offer one importantbrick: a container orchestration tool for the edge cloud. Our tool,EdgeNet, is an extension to Kubernetes, the de facto standard fordeploying containers to classic large centralized data centers. EdgeNettakes into account the particular nature of the edge cloud: there will bemany providers of edge clouds; and there will be many customers that needto share more limited resources in each cloud. We describe the EdgeNetvision, the components that we have built, and those that remain to bebuilt.

This talk presents the work of Berat Senel, which formed thebasis of the doctoral dissertation that he defended in June 2023 atSorbonne Université.

KE FENG (Inria)
Title: Spatial NetworkCalculus and Performance Guarantees in Wireless NetworksAbstract: Networkcalculus is initially a methodology allowing one to provide performanceguarantees in queuing networks subject to regulated traffic arrivals andservice guarantees. It is a key design tool for latency-critical wirelinecommunication networks where it allows one to e.g. guarantee bounds on theend-to-end latency of all transmitted packets. In wireless networks,service guarantees are more intricate as electromagnetic signals propagatein a heterogeneous medium and interfere each other. In this work, wepresent a novel approach toward performance guarantees for all links inarbitrarily large wireless networks. We introduce spatial regulationproperties for stationary spatial point processes, and develop the firststeps of a calculus for this type of regulation.

fabien mathieu(invited inria)
Title: Corsort: An anytime sortingalgorithm

Abstract: An anytime algorithm is an algorithm that is ableto give an estimation of the result after each step of execution. Ee studythe problem of anytime sorting. We consider that each comparison is a stepof execution, and we measure the proximity between the estimation and thesorted list with the Kendall tau distance. We present Corsort, a family ofanytime sorting algorithms using estimators. By simulation, we show that awell-configured Corsort has a quasi-optimal termination time, and givesbetter estimations than the other algorithms of ourbenchmark.

SWAPNIL DHAMAL(Télécom-SudParis)
Title: Resource Allocation and Pricing for NetworkSlicing in 5G: A Learning Perspective

Abstract: Network slicing is acritical component in 5G networks, since the intended services such asUltra Reliable Low Latency Communications (URLLC) and enhanced MobileBroadBand (eMBB) give rise to very distinct requirements. Each slice can becustomized for a given type of service, and a given tenant who ischaracterized by a stochastic demand and a resource utility functionreflecting its Quality-of-Service (QoS) requirements. In this work, westudy the techno-economic aspect of the slice market that involves theoperator and the tenants (slice owners). In particular, the game that westudy is a Stackelberg game, where the operator is the leader who presentsa pricing scheme that defines the price corresponding to eachbandwidth-level, and the tenants are the followers who decide whichbandwidth-level to request. Since the operator has a certain capacityconstraint, it takes the requested bandwidth-levels of the tenants intoaccount, and determines the admission control and resource allocation suchthat its expected profit is maximized while satisfying the capacityconstraint. Our framework models the joint admission control, resourceallocation, and pricing for network slicing in the above game, as anoptimization problem aiming to maximize the operator’s expectedprofit. We show that solving the formulated optimization problem isNP-hard. We also encounter a paradox that the operator's profit coulddecrease if a tenant’s resource utility increases. We consider apractical scenario where the utility matrix, comprising the resourceutilities of the tenants for the different bandwidth-levels, are not knownto the operator. We propose several approaches for learning an optimalpricing scheme, including a neural network-based approach, as well asapproaches based on iteratively updating and refining the ambiguity set ofutility matrices by observing the tenants’ requested bandwidth-levelscorresponding to the presented pricing schemes. We study the performance ofthe various approaches and present insights.

TIANZHU ZHANG(Nokia)
Title: Causal Reasoning for configurable networksystems

Abstract: With the rapid advancement in B5G, IoT, and networksoftwarization, modern ICT network systems are becoming increasinglydiverse, disaggregated, and complex. Consequently, understanding andmanaging these systems has thus become a daunting task. Although AI/MLtechniques can lend sound predictive services, they need more robust,counterfactual reasoning and decision-making. In this talk, I will presentour ongoing work exploring causal research for network diagnosis andoptimization. Our study focuses on real-world systems capable of processingnetwork traffic at extremely high speed, e.g., 10-100 Gbps. We take twopaths to approach causal reasoning: i) causal discovery fromobservational/interventional data and ii) causal inference for insightextraction. The ultimate goal is to implement a generic, robust,production-ready toolset that can effectively uncover performancebottlenecks and guide optimizations for different network systems.

PhD thesis defense of Pierre POPINEAU "Study of the dynamics ofspatial point processes in wireless communication networks"
2023-06-14 14:00 - 17:30 | Amphi Rose Dieng, 19 place Marguerite Perey, Palaiseau, France
Thanks to the new paradigms introduced in the latest generationof wireless networks, expectations concerning service time, latency andnetwork performance have increased. To model such networks, point processtheory and stochastic geometry have proven to be useful as they provide aversatile and robust framework to obtain results when working with suchwireless networks. Adding to this Markov dynamics to model connections andservice times completes this framework to analyze such wireless networks.The first contribution of the work presented in this thesis lies in theanalysis of service differentiation: 5G NR networks have introducedbandwidth partitioning as a tool to increase network performance. Underthis network setup, not all users interfere with each other with the samepower: users transmitting with a broader transmitting frequency spectrumwill have a larger bandwidth, but they will also encounter moreinterference from the other users in the network. In contrast, users witha narrower spectrum will experience less interference. We define aMarkovian framework to study such a multiclass spatial birth-and-deathprocess, and we describe its stability region. For such systems,properties of the stationary regime are analyzed, such as moment measuresor statistical clustering, leading to a better understanding of thesedynamics. The second problem we look into is mobility, which has become animportant feature in wireless networks due to the use of highly directionalantennas. Using a simple architecture for a two-tier cellular network, westudy two families of association policies: a first family which onlyrelies on user mobility, and the second offers a trade-off between networkgeometry and user mobility to increase network performance. These policiesare then compared to a classical max-power association policy to asserttheir performance.

PhD thesis defense by Matthieu Gouel "Internet-Scale Route TracingCapture and Analysis"
2023-06-12 13:00 - 16:00 | Jussieu, Room 24-25/405-SOC, 4 place Jussieu, Paris, 75005,France
The Internet is one of the most remarkable human creations,enabling com-
munication among about two thirds of the global population.This network
of networks spans the entire globe and is managed in a highlydecentralized
way, making it impossible to fully comprehend at IP-level.Nonetheless, for
over two decades, researchers have been devising newtechniques, developing
new tools, and creating new platforms to captureand provide more precise
and comprehensive maps of the Internet’stopology. These e?orts support
network operators in the industry and otherresearchers in improving core
features of the Internet such as itsconnectivity, performance, security, or
neutrality.
This thesispresents new contributions that improve the scalability of
Internettopology measurement. It introduces a state of the artmeasurement
platform that enables the use of high-speed probing techniquesfor IP route
tracing at Internet scale, as well as a reinforcementlearning approach to
maximize the discovery of the Internet topology.Because the analysis of the
route tracing data collected requiresadditional metadata, the evolution of
IP address geolocation over a10-year period in a widely used proprietary
database is examined, andlessons are provided to avoid biases in studies
using this database.Finally, a large-scale analysis framework is developed to
effectivelyutilize the large number of collected data and augmented metadata
fromother sources, such as IP address geolocation, to produceinsightful
studies at the Internet scale.
This work aims to considerablyimprove the study of the Internet topology
by providing tools to collectand analyze large amounts of Internet topology
data. This will allowresearchers to better understand how the Internet is
structured and how itevolves over time, leading to a more comprehensive
understanding of thiscomplex system.

2nd PhDs “elevator pitch” training session
2023-06-07 15:00 - 16:00 | Room 4A113, 19 place Marguerite Perey, Palaiseau, France
Bharath Roy Choudhury (Inria)

Guillaume Nibert(Sorbonne/Snowpack)

Sayeh Khaniha (Inria)

Thomas Le Corre(Inria)

Claire Bizon-Monroc (Inria)

Lucas Weber (Inria)

Séance préparation POSTER
2023-05-31 15:00 - 16:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France

1st PhDs "elevator pitch" training session
2023-05-24 15:00 - 16:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Emma Caizergues (Dauphine/Nokia)

Guodong Sun(Inria/Nokia)

Emma Braiteh (Télécom-Paris/SystemX)

ShashwatMishra (Nokia)

Mohammad Abdullah (Télécom-SudParis)

Digital Twins for Networks of Future: Open Research Challenges andOpportunities
2023-05-24 10:30 - 11:15 | Room 4A113, 19 place Marguerite Perey, Palaiseau, France
In this talk, I will address the different definitions ofDigital Twins (DT) and explain their differences according to the sectorsand domains we consider. Next, I propose to discuss the referencearchitecture of a Digital Twin highlighting its different and necessary microservices. The talk will also consider certain domains ofapplications necessitating the DT and will focus on the specific case ofDigital Twin for Networks of Future while addressing open researchchallenges and opportunities allowed by DTs.

Three Perspectives to Enhance the Performance of High-SpeedDatacenter Networks
2023-05-17 15:00 - 16:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
The performance of large-scale computing systems oftencritically depends on high-performance communication networks. In thispresentation, I will focus on two key metrics throughput and latency fromthree perspectives within a datacenter network: end-host, networkdataplane and topology.

At the end-host, I will discuss the impact ofcongestion control in achieving high throughput and low latency whilerequiring little to no buffer in the network. I will then presentPowerTCP, a power-based congestion control algorithm that leverages inbandnetwork telemetry and adapts to both the absolute state as well as thechanges in the network (NSDI 2022).

At the network core, I will discussthe role of buffer management in improving datacenter performance andpresent Active Buffer Management (ABM), a novel buffer sharing scheme fordatacenter switches. ABM not only offers isolation but also offers stablequeueing delays which as we show essentially enhances the burst absorptioncapabilities of the switch (SIGCOMM 2022).

At the topological level, Iwill show the fundamental tradeoffs across throughput, latency and bufferrequirements within a subset of the design space. I will briefly presentMars, a near-optimal throughput reconfigurable datacenter topology thatachieves high throughput within the given buffer capacity of the networkdevices (SIGMETRICS 2023).

I will conclude by discussing ongoing worksand open questions.

Bio
Vamsi is a third year PhD student atTU Berlin under the supervision of Prof. Stefan Schmid. He obtained MSc.from Sorbonne University Paris and did his thesis at ETH Zurich. In 2017,he started off his path towards research at Telecom Paris with Prof. DarioRossi and Leonardo Linguaglossa hosted at Lincs. Currently, he is broadlyinterested in network topologies; congestion control and network flowproblems; online algorithms and competitive analysis; buffer requirementsand management; and related areas. His research is mainly at theintersection of networking theory and systems.

Sorting under Partial Information
2023-05-17 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
We present the following article: Cardinal, Fiorini, Joret,Jungers, and Munro. Sorting under partial information (without theellipsoid algorithm). Proceedings of the forty-second ACM symposium onTheory of computing. 2010.

"We revisit the well-known problem of sortingunder partial information: sort a finite set given the outcomes ofcomparisons between some pairs of elements. The input is a partiallyordered set P, and solving the problem amounts to discovering an unknownlinear extension of P, using pairwise comparisons. Theinformation-theoretic lower bound on the number of comparisons needed inthe worst case is log e(P), the binary logarithm of the number of linearextensions of P. In a breakthrough paper, Jeff Kahn and Jeong Han Kim(STOC 1992) showed that there exists a polynomial-time algorithm for theproblem achieving this bound up to a constant factor. Their algorithminvokes the ellipsoid algorithm at each iteration for determining the nextcomparison, making it impractical.

We develop efficient algorithms forsorting under partial information. Like Kahn and Kim, our approach relieson graph entropy. However, our algorithms differ in essential ways fromtheirs. Rather than resorting to convex programming for computing theentropy, we approximate the entropy, or make sure it is computed onlyonce in a restricted class of graphs, permitting the use of a simpleralgorithm."

Quantifying the Bias of Transformer-Based Language Models forAfrican American English in Masked Language Modeling
2023-05-10 15:00 - 16:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
In recent years, groundbreaking transformer-based languagemodels (LMs) have made tremendous advances in natural language processing(NLP) tasks. However, the measurement of their fairness with respect todifferent social groups still remains unsolved. In this paper, we proposeand thoroughly validate an evaluation technique to assess the quality andbias of language model predictions on transcripts of both spoken AfricanAmerican English (AAE) and Spoken American English (SAE). Our analysisreveals the presence of a bias towards SAE encoded by state-of-the-art LMssuch as BERT and DistilBERT and a lower bias in distilled LMs. We alsoobserve a bias towards AAE in RoBERTa and BART. Additionally, we showevidence that this disparity is present across all the LMs when we onlyconsider the grammar and the syntax specific to AAE.
Short bio:
JeromeRamos is a second year PhD student at University College London supervisedby Dr. Aldo Lipani. His research interests include explainability andscrutability in conversational recommender systems.

Proving and analysing security protocols with Scyther
2023-05-10 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Scyther is an open source Python tool for proving and verifyingsecurity protocols. It offers the possibility to integrate adversaries tocompromise protocols and to visualise the result associated with thecorruption of these protocols. It has also been used to analyse the IKEv1and IKEv2 protocols [1] used in VPNs and various authentication protocols[2]. In this workshop we will learn how to use the tool and prove someprotocols.

Website: https://people.cispa.io/cas.cremers/scyther/index.html
Sourcecode: https://github.com/cascremers/scyther

References:

[1] C.Cremers, Key exchange in IPsec revisited: Formal analysis of IKEv1 andIKEv2 in Computer Security–ESORICS 2011: 16th European Symposium onResearch in Computer Security, Leuven, Belgium, September 12-14, 2011.Proceedings 16, Springer, 2011, pp. 315–334. Availableat: https://people.cispa.io/cas.cremers/downloads/papers/Cr2011-IKE.pdf [accessed on May 4, 2023]

[2] [1] D. Basin, C. Cremers, and S.Meier, Provably repairing the ISO/IEC 9798 standard for entityauthentication, Journal of Computer Security, vol. 21, no. 6, pp.817–846, 2013. Availableat: https://people.cispa.io/cas.cremers/downloads/papers/BCM2012-iso9798.pdf [accessed on May 4, 2023]

A necessary and sufficient condition for stability of queuingnetworks with state-dependent departure rates
2023-04-26 15:00 - 16:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Reaching stability conditions for Markovian queueing networksis a problem for which many methods have been developed, depending on thequeueing policies, laws for arrivals and departure of users in thesystem, but obtaining instability or transience is a problem known to beharder.
In this talk, we will focus on a type of queuing networks wherethe departure rate in a given queue is a decreasing function of the otherqueue lengths, and increasing in its queue length. This type of queuingnetworks can be encountered in wireless communication systems, where thedeparture rate depends on the interference in the system.
We first obtaina stability condition for the system using fluid limits, and proveinstability using stochastic domination arguments. This stability conditionis interesting as it allows us to study systems for which the fluid modelsare not defined near 0.

The talk is based on the results of these papers:
- S. Shneer and A. Stolyar, Stability conditions for a decentralisedmedium access algorithm: single- and multi-hop networks, Queuing Systems,vol. 94, pp. 109–128, 2020,https://link.springer.com/article/10.1007/s11134-019-09635-w
- P. Popineauand S. Shneer, An instability condition for queuing systems withstate-dependent departure rates, 2023, https://arxiv.org/abs/2304.08853

Strategic Computational Investment in Blockchain Mining
2023-04-19 15:00 - 16:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
This presentation will be based on our work on strategicinvestment of computational power by miners in blockchain. In particular,we shall consider a setting where miners can arrive and depart over time,and hence analyze their investment strategies and the obtained payoffs inthe equilibrium of the underlying stochastic game. We shall see thatdepending on the mining scenario, miners either follow a thresholdingpolicy that is independent of the other miners, or a smooth policy thatdepends on the other miners. Thereafter, we will look at a Stackelberggame, where the system decides the amount of reward to offer for mining ablock and the miners decide how much power to invest based on the offeredreward.
Authors: Swapnil Dhamal (Telecom SudParis), Walid Ben-Ameur(Telecom SudParis), Tijani Chahed (Telecom SudParis), Eitan Altman (INRIASophia Antipolis), Albert Sunny (IIT Palakkad), and Sudheer Poojary(Qualcomm)

A Bit of Gymnastics in Python
2023-04-19 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
In this interactive session, I will propose exercises inspiredby the most popular questions about Python in Stack Overflow:https://stackoverflow.com/questions/tagged/python?tab=votes.

Here is theapproach of the session:

For beginners, search answers on the web,discover some elements of the Python syntax;
For more advanced users,try to do as much as possible without any help from the web, gain speedand agility, find several answers to the same question.

Requirements: acomputer with a Python installation + Jupyter Notebook. Only a minimalknowledge of Python is necessary.

The notebook displayed below givesonly the problems. The one with the solutions can be accessed here:https://gist.github.com/francois-durand/d7f814a4336d3d00d3adec4cdf75113b.

Distributed Function Computation over Networks
2023-04-12 15:00 - 16:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Large-scale distributed computing systems, such as MapReduce,Spark, or distributed deep networks, are critical for parallelizing theexecution of computational tasks. Nevertheless, a struggle betweencomputation and communication complexity lies at the heart of distributedcomputing. There has been recently a substantial effort to address thisproblem for a class of functions, such as distributed matrixmultiplication, distributed gradient coding, linearly separablefunctions, etc. The optimal cost has been achieved under someconstraints, based mainly on ideas of linear separability of the tasks andlinear space intersections. Motivated by the same challenge, we propose anovel distributed computing framework where a master seeks to compute anarbitrary function of distributed datasets in an asymptotically losslessmanner. Our approach exploits the notion of characteristic graphs, whichhave been widely utilized by Shannon, K¨orner, and Witsenhausen toderive the rate lower bounds for computation, and later by Alon-Orlitsky, Orlitsky-Roche, Doshi-Shah-M´edard, and Feizi-M´edard, toresolve some well known distributed coding and communication problems,allowing for lowered communication complexity and even for a) correlateddata, b) a broad class of functions, and c) well-known topologies. Thenovelty of our approach lies in accurately capturing thecommunication-computation cost tradeoff by melding the notions ofcharacteristic graphs and distributed placement, to provide a naturalgeneralization of distributed linear function computation, thus elevatingdistributed gradient coding and distributed linear transform to the realmof distributed computing of any function. In toy scenarios, we demonstrategains up to %70 over fully distributed solutions and an approximation ratioof 2 within the optimal centralized rate.

Age of Information Processes under Strongly Mixing Communication
2023-04-05 15:00 - 16:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
The decentralized nature of multi-agent systems requirescontinuous data
exchange to achieve global objectives. In suchscenarios,
Age-of-Information (AoI) has become an important metric forthe
freshness of communicated data. The study of AoI consequently hasto
take into account the dependencies that communication systemsexhibit:
The process describing the success or failure of communication ishighly
correlated when these attempts are ``close'' in some domain. Tostudy
AoI in such scenarios, I will introduce fundamental AoIprocesses
$\Delta(n)$, expressing the discrete-time since the lastupdate from a
source at a monitor: If during time slot $n$ the monitorreceives a
status update from the source (event $A(n)$), then$\Delta(n+1)$ is
reset to one, otherwise, $\Delta(n)$ grows linearlyin time. This AoI
process is a special random walk with resets. The eventprocess $A(n)$
may be non-stationary and we assume that its temporaldependencies
decay, described by $\alpha$-mixing. With this, momentbounds and growth
bounds follow for the resulting AoI process as afunction of the mixing
rate of $A(n)$. In addition, the AoI process$\Delta(n)$ is itself
$\alpha$-mixing. I will then discuss how thefundamental AoI processes
presented can be used to model more complex AoIstructures that do not
necessarily reset to one when information isupdated and where multiple
sources may lead to AoI at a monitor.

Gaussian limit laws and generating series
2023-04-05 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
The Central Limit Theorem states that some sums of randomvariables, once renormalized, converge to the Gaussian distribution. Someparameters of large combinatorial objects have a similar flavor but do notsatisfy the independence assumption. I will present tools from analyticcombinatorics to handle those parameters and prove Gaussian limit laws (andmany others!).

fAST: How to find relevant regular expression from a small set ofpositive examples
2023-03-29 15:00 - 16:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Regular expressions are ubiquitous in computer science but arecumbersome to code. In this work, we present a new algorithm, named fAST(find Abstract Syntax Tree), that infers a regular expression from a smallset of positive examples. Its main strength (with respect to the start ofthe art) resides in its ability to perform this inference without counterexamples.

Authors: Maxime Raynal (LIG, NBLF), Marc-Olivier Buob(NBLF), Georges Quénot (LIG)

Content Delivery Networks: providing content at global scale
2023-03-29 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
On April 13, 2019, 17.4 million users watched the newlyreleased episode of Games of Thrones. The Trump vs. Clinton debate wasstreamed to 2 million simultaneous users over the Internet. Serving contentat such a huge scale requires advanced engineering solutions, to ensurescalability and security.

Content Delivery Networks (CDNs) solve thischallenge. Being conceived during a student competition on algorithms atMIT, they are now the pillars of the Internet, although the common mandoes not even know they exist.

In this talk I will describe the innermechanics of CDNs, with a particular focus on redirection,authentication, caching and video workflow.

Talk à définir
2023-03-22 15:00 - 16:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France

Wireless communications for dummies – part 2
2023-03-22 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
We will cover Chapter 3 of [1], including important conceptsfor modern wireless networks such as time/frequency/antenna diversity,space-time codes, and—if time permits—OFDM.

[1] Tse, David, andPramod Viswanath. Fundamentals of wireless communication. Cambridgeuniversity press, 2005.

slides: Wireless-for-dummies

An introduction to the numerical solver for multiple integrals
2023-03-15 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Evaluating multiple integrals is challenging when there existsno simple closed form representations. However, they are frequentlyencountered in network analysis, such as in queueing theory and stochasticgeometry. In this reading group talk, I will introduce the development ofnumerical integration, namely the line of though from Newton’sTrapezoidal rule to Fourier’s spectrum method and to Gauss-Kronrodquadrature method, in which the latest one is proven to be one of the mostefficient for one dimensional(1D) numerical integration. This line ofthought inspires numerical multiple integrals. As an example,“Genz-Malik algorithm” will be presented, which is used to solveN-dimensional smooth multiple integrals and is prove to be efficient whenthe dimension ranges from two (2D) to seven (7D). In addition, I willcompare the Genz-Malik algorithm with other solvers, such as iterative onedimensional algorithm and Monte Carlo integration.

LINCS and ERC-NEMO 2-day Workshop "Performance Guarantees inWireless Networks"
2023-03-08 09:00 - 2023-03-09 17:45 | Amphi Rose Dieng, 19 place Marguerite Perey, Palaiseau, France
**CLICK to reach the web page of the Workshop**
You will findthere the list of the confirmed invited speakers and theprogram

The LINCS and the ERC-NEMO are glad to announce a2-day Workshop entitled "Performance Guarantees in Wireless Networks",organized by François Baccelli (INRIA and Telecom-Paris) and Jean-MarieGorce (INRIA Lyon).

The workshop will take place on March 2023,Wednesday 8th and Thursday 9th, @LINCS: Télécom Paris, 19 placeMarguerite Perey, Palaiseau, Amphi Rose Dieng.

IMPORTANT! Registeringat the following link is required toattend: https://www.telecom-paris.fr/agenda/lincs-workshop-wireless-networks

The event is sponsored by LINCS and ERC-NEMO, and by Telecom-Parisfor the premises

Coverage and Capacity of Joint Communication and Sensing inWireless Networks
2023-03-01 15:00 - 16:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
From an information theoretic perspective, joint communicationand sensing (JCAS) represents a natural generalization of communicationnetwork functionality. However, it requires the re-evaluation of networkperformance from a multi-objective perspective. We develop a novelmathematical framework for characterizing the sensing and communicationcoverage probability and ergodic capacity in JCAS networks. We employ aninformation theoretic formulation of radar tracking to extend the notionsof coverage probability and ergodic capacity to the radar setting. Wedefine sensing coverage probability as the probability that the rate ofinformation extracted about the parameters of interest associated with atypical radar target exceeds some threshold, and sensing ergodic capacityas the expected value of the aforementioned rate of information. Using thisframework, we analyze the downlink sensing and communication coverage andcapacity of a JCAS network employing a shared multicarrier waveform andanalog beamforming. Leveraging tools from stochastic geometry, we deriveupper and lower bounds for these quantities. We also develop severalgeneral technical results including: i) a generic method for obtainingclosed form upper and lower bounds on the Laplace Transform of a shot noiseprocess, ii) a new analog of Ho?lder’s Inequality to the setting ofharmonic means, and iii) a relation between the Laplace and MellinTransforms of a non-negative random variable. We use the derived bounds tonumerically investigate the performance of JCAS networks under varying basestation and blockage density. Among several insights, our numericalanalysis indicates that network densification improves sensing performance– in contrast to communications.

Slides

Parse and analyze source codes with Tree-sitter
2023-03-01 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Tree-sitter is a library for parsing source codes. Compared tosimilar libraries, Tree-sitter is very fast and dependency-free. Thismakes it easy to embed it in other programs, such as text editors, anduse it for real-time applications, such as syntax highlighting. In thistalk we will study Tree-sitter’s query language to search for patterns insyntax trees, and show how to use it from Python to analyze otherprograms.

Some Methods to Improve IoT Performance and Cybersecurity
2023-02-22 15:00 - 16:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
The relative simplicity and lightweight nature of many IoTdevices, and their widespread connectivity via the Internet and otherwired and wireless networks, raise issues regarding both their performanceand vulnerability. Indeed, their own connectivity patterns based on theneed to frequently forward and receive, data has given rise to the« Massive Access Problem (MAP) of the IoT » which is a form ofcongestion caused by the IoT’s synchronized and repetitive datatransmission patterns. On the other hand, the opportunity that IoT devicespresent to malicious third parties for generating highly contagiousdistributed denial of service (DDoS) and Botnet attacks, is also a subjectof concern which is widely studied. Thus this presentation will discuss ourrecent results and research directions that address both of these issues.Regarding the MAP, we will outline the Quasi-Deterministic TransmissionPolicy (QDTP), and its main theoretical result, and present trace drivenmeasurements, which show that QDTP can effectively mitigate MAP. We willalso show how a Machine Learning approach using novel Auto-AssociativeDense Random Neural Networks can detect DDos attacks with a high degree ofaccuracy, and discuss the potential of « low cost » online learning toprotect IoT gateways and devices against Cyberattacks. The speakergratefully acknowledges research funding from the EC as part of the H2020GHOST, SerIoT and IoTAC projects.

Info on the speaker:https://en.wikipedia.org/wiki/Erol_Gelenbe

SLIDES LINK

Introduction to Differential Privacy
2023-02-22 10:30 - 11:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Consider an individual who is deciding whether to allow theirdata to be included in a database. For example, it may be a patientdeciding whether their medical records can be used in a study, or someonedeciding whether to answer a survey. A useful notion of privacy would be anassurance that allowing their data to be included should have negligibleimpact on them in the future. Absolute privacy is inherently impossible butwhat we want to be guaranteed is that that the chance of a privacyviolation is small. This is precisely what differential privacy (DP)provides. We will have an introduction to differential privacy, in whichwe will cover the fundamentals of differential privacy, such asepsilon-differential privacy, the Laplace mechanism, and the exponentialmechanism. We will also discuss the strengths and limitations ofdifferential privacy, and the challenges associated with itsimplementation.

Note taking and knowledge management with Obsidian.md and Zotero
2023-02-15 11:30 - 12:30 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Obsidian is a recent markdown note-taking software (2020) withpowerful features, such as the ability to link notes to each other, toview these links as a graph, and to read BibTex/BibLaTeX files viaextensions. Connecting Zotero to Obsidian is great way to start studying aresearch topic. In this workshop, we will learn how to use the power ofZotero combined with Obsidian and some useful extensions to be moreefficient when taking notes, writing articles and managing bibliographicreferences.

Download links:

Zotero: https://www.zotero.org/
Zotero Connector: https://www.zotero.org/download/connectors
Obsidian:https://obsidian.md/
Better BibTeX/BibLaTeX:https://retorque.re/zotero-better-bibtex/
Zotfile: http://zotfile.com/
Zotero Citation Counts:https://github.com/eschnett/zotero-citationcounts
Zotero Translate:https://github.com/windingwind/zotero-pdf-translate

Slides of thepresentation.

"What next?" - event for the PhDs
2023-02-08 17:30 - 19:00 | Room 4C06, 19 place Marguerite Perey, Palaiseau, France
WHAT NEXT?

Navigating the PhD is certainly not an easytask, but making decisions about what to do next can be even morecomplicated and stressful.
@LINCS we know how difficult and disorientingthis can be, thus we invited some former LINCS members (who were in thissituation only a few years ago) to tell us their stories.
We chose peoplewho undertook very different paths: they ended up in academia, instartups, in big companies, in public institutions… They are alleasy-going and nice people, ready to share their experience, includingall their doubts, their hesitations, their failures, theirinspirations, etc.
It is good to have an idea of “what’s outside”and it is important to think about what can make you happy. Different pathsbring different pros and cons, which it is worth exploring. Together isdefinitely better!
We hope to see many PhD students participating in thisevent :) Lot of time for Q&A and something for an apéro!

LIST ofCONFIRMED SPEAKERS:

Francesca Bassi (SystemX)
Gabriele Castellano(Huawei)
Céline Comte (CNRS Toulouse)
Rémy Léone (Scaleway)
Leonardo Linguaglossa (Télécom-Paris)
Flavia Salutari (BNPParibas)

Here're the slides of the event with a descriptionof the best and worst aspects of each speaker's professionalpath.

Here's the flyer of the event.

A Converse for Fault-tolerant Quantum Computation
2023-02-08 15:00 - 16:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
As techniques for fault-tolerant quantum computation keepimproving, it is natural to ask: what is the fundamental lower bound onredundancy? In this paper, we obtain a lower bound on the redundancyrequired for $\epsilon$-accurate implementation of a large class ofoperations that includes unitary operators. For the practically relevantcase of sub-exponential depth and sub-linear gate size, our bound onredundancy is tighter than the known lower bounds. We obtain this bound byconnecting fault-tolerant computation with a set of finite blocklengthquantum communication problems whose accuracy requirements satisfy a jointconstraint. The lower bound on redundancy obtained here leads to a strictlysmaller upper bound on the noise threshold for non-degradable noise. Ourbound directly extends to the case where noise at the outputs of a gate arenon-i.i.d. but noise across gates are i.i.d.
(This is a joint work withUthirakalyani G, IIT Madras and Anuj K. Nayak, UIUC. No prior knowledgeabout quantum computation and communication will be assumed in this talk.)

Platooning in VANETs
2023-02-08 11:30 - 12:30 | Telecom Paris, 4A113 (4th floor), Telecom Paris, 4A113 (4thfloor), Palaiseau, 91120, France
Platooning is a group of vehicles that drive in the same lanein a close proximity aiming at improving road safety and trafficefficiency and reducing fuel consumption. This application firstly reliedon vehicular sensors to calculate a minimal inter-vehicle distance, ithas then been enhanced to integrate wireless communication to communicatevehicular information and calculate a safe driving distance within theplatoon. In the LINCS talks, I'll go over different existing platooningalgorithms and technologies in VANETs and discuss the importance ofcollaborative in-platooning decisions to protect the platoon fromcyberattacks.
Slides

Communications and sensing, a Winning team for 6G wirelesscommunications
2023-02-01 15:00 - 16:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Up until now, communications and radar sensing applicationshave employed different spectrum allocations and equipment, despite bothemploying the same physical phenomenon, i.e., the propagation ofelectromagnetic waves. Recently however, technological trends, like theusage of multiple antennas and wider bandwidths for communications, andthe increased digitalization of radar processing, have made theintegration of both systems easier. With this in mind, jointcommunications and sensing is likely to be one of the key features of 6Gwireless systems, bringing about a plethora of new use cases. In this talkthe promises and challenges of this new exciting technology will bediscussed.

Collective Behavior Emerging From Multiple Agents in Networks
2023-02-01 11:30 - 12:30 | Telecom Paris, 4A113 (4th floor), 19 place Marguerite Perey,Palaiseau, 91120, France
Transport networks and computer networks can be described withthe same mathematical framework: the infrastructure can be described as agraph and on top of it a set of agents compete for its capacity, eachaiming to selfishly optimize its own objective. Such agents are passengersin transport networks and TCP origin-destination pairs in computernetworks.
In this talk I will review classic models that help tounderstand what happens in such networks from a macroscopic point of view.I will show that by acting selfishly, agents are unwittingly alsocollectively solving a centralized optimization problem. This can beinterpreted as a collective behavior resulting from the interaction ofmultiple selfish agents.

Spatial network calculus and performance guarantees in wirelessnetworks
2023-01-25 15:00 - 16:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Network calculus is initially a methodology allowing one toprovide
performance guarantees in queuing networks subject to randomarrival and
service processes. It relies on the notions of regulatedtraffic arrivals
and service curves or guarantees. It is a key designtool for
latency-critical wireline communication networks where itallows one to
e.g. guarantee bounds on the end-to-end latency of alltransmitted
packets. In wireless networks, service guarantees are moreintricate as
electromagnetic signals propagate in a heterogeneous mediumwhere they
are subject to unpredictable reflections and obstructions andas it is
more difficult to isolate these signals from each other than inthe
wireline case. There is hence no methodology yet allowing one togive
performance bounds holding for all links in wirelessnetworks.

In this talk, we present a novel approach toward suchbounds for all
links in arbitrarily large wireless networks. Weintroduce spatial
regulation properties for stationary spatial pointprocesses, which model
transmitter and receiver locations, and developthe first steps of a
calculus for this type of regulation. Usingthis approach, we derive performance guarantees for
various types ofdevice-to-device and cellular wireless networks. Such guarantees do notexist in
networks without spatial regulation, e.g., Poisson networks.

Hands-on JavaScript
2023-01-25 11:30 - 12:30 | Telecom Paris, 4A113 (4th floor), 19 place Marguerite Perey,Palaiseau, 91120, France
In this tutorial, we’ll build a simple “to-do list”client-server application. The aim is to present the different features,pitfalls, and general quirks of JavaScript through actual code.
If youwant to play around with the code during the session, you should installNode.js and NPM.
The code on GitHub:https://github.com/rvarloot/lincs-js-todo.

A Linear Algebric Framework for Quantum Internet Dynamic Scheduling
2023-01-18 15:00 - 16:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
The quantum internet is an envisioned worldwide quantum networkthat
promises to enable quantum communication between arbitrary pairsof
distant nodes through the sharing of end-to-end entanglement. Torealize
the quantum internet, we need to solve the practical problemsthat arise
when scaling up a network system, which are already well knownto
classical network science but come with new complicationswhen
considered on quantum hardware. I will introduce the problemof
scheduling in classical and quantum networks, propose apreliminary
solution to it through our recently published work "A LinearAlgebraic
Framework for Quantum Internet Dynamic Scheduling", thatintroduces a
toolbox for designing and benchmarking quantum dynamicscheduling
policies, and show some examples of results that can bederived by
applying our model to a small quantum network example.

How Google Manages Its Data-Center Interconnexion With SDN
2023-01-18 11:30 - 12:30 | Telecom Paris, 4A113 (4th floor), 19 place Marguerite Perey,Palaiseau, 91120, France
Google has built a dozen data centers around the world. Toavoid data loss and offer high availability, Google replicates a massiveamount of data through its own WAN network connecting all its sites withterabits/s bandwidth. But these kinds of networks are *very* expensive,and are usually over-provisioned to face traffic variance. Google B4optimizes the utilization of its network via sophisticated software-definednetworking on handcrafted hardware. Let’s scratch together the surface ofthis large-scale real-world SDN implementation.

Coalitional Manipulation of Voting Rules: Simulations on EmpiricalData
2023-01-11 15:00 - 16:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Using computer simulations based on empirical data, we showthat seven voting rules that we call the IRV family (Instant-RunoffVoting, exhaustive ballot, Condorcet-IRV, Benham, Smith-IRV, Tidemanand Woodall) are less sensitive to coalitional manipulation than a largeselection of prominent voting rules. While the relative performances ofthese seven rules still deserve further investigation, we show that thedifferences are at most marginal.
TALK'S SLIDES

Optimal Bounds for the No-Show Paradox via SAT Solving
2023-01-11 11:30 - 12:30 | Room 4A113, 19 place Marguerite Perey, Palaiseau, France
The participation criterion is a social choice criterion thatcharacterizes voting rules. A voting rule satisfies this criterion if,considering a is the winner of the election, the addition of a ballotwhere candidate a is preferred to candidate b should not make b win.
Whena voting rule fails the participation criterion, the phenomenon is calledthe no-show paradox (Fishburn and Brams, 1983). With this paradox comesseveral questions. One of them is to obtain a bound (on the number ofcandidates and/or voters) that characterizes the criterion's satisfactionfor a given voting rule.
In this talk, I will first present theparticipation criterion, some voting rules that satisfy it and some thatdo not (Moulin, 1987). Then, I will focus an article of Brandt et al.(2017), which presents a way to obtain optimal bounds for the no-showparadox via SAT solving.

References
Felix Brandt, Christian Geist,and Dominik Peters. Optimal bounds for the no-show paradox via SAT solving.2017.
Peter C. Fishburn and Steven J. Brams. Paradoxes of preferentialvoting. 1983.
Hervé Moulin. Condorcet’s principle implies the no showparadox. 1987.

INFRES seminar on "Kubernetes"
2023-01-04 13:30 - 16:45 | Room 4B07, 19 place Marguerite Perey, Palaiseau, Gabon
Leonardo Linguaglossa, maitre de Conf. at Télécom-Paris(Dept. INFRES), invited Rémy Léone (Scaleway) to give a seminar talkon "Kubernetes" in the framework of his course on Cloud Systems.

PA-CODA: Planner-Agnostic Collision Detection and Avoidance forMulti-Robot Navigation
2022-12-14 15:00 - 16:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
Coordinated path planning and motion control are crucial forcollision-free navigation of a fleet of robots that share a space andpotentially contend for the same paths and passages. Many existingnavigation software packages are designed for single-robot navigation andtreat other robots as any other observed obstacle, but this strategy aloneis not sufficient for the system to work reliably. The ability to use theexisting single-robot stacks without modification while also achievingcoordination has high practical value. This talk will present a system thatachieves coordination without modifying the path planner or motioncontroller. The only requirement, which exists already in most navigationstacks and is otherwise easy to implement using existing interfaces, isthat the navigation stack provide interfaces for injecting dynamicprohibition regions into the cost map and for requesting that the robottemporarily stop its motion. The system, which we call PA-CODA, observesthe robots’ intents and uses a learned hidden Markov model to anticipatecollisions, which are then avoided by manipulating the cost map ortemporarily stopping one or more robots. We ran a series of experimentswith real robots to demonstrate PA-CODA’s ability to successfully detectand avoid collisions.

What is JavaScript?
2022-12-14 11:30 - 12:30 | Telecom Paris, 19 place Marguerite Perey, Palaiseau, 91120,France
As a programming language, JavaScript does has a few quirkshere and there, but what truly sets it apart is the central role it playsin the creation of web pages and applications. As such, understandingJavaScript has more to do with understanding its contribution to the Web,and the numerous evolutions it has undergone, than mastering its syntaxand internal logic. This presentation gives an overview of the moreprominent trends that have appeared over the years, and aims to showcasewhat programming in JavaScript can actually look like, depending on yourneeds.

Special RG session: presentation of the TP software radio platform
2022-12-07 15:00 - 16:00 | Room 4A120, 19 place Marguerite Perey, Palaiseau, France
Exceptionally, we'll have a session of the "Practical Network"Reading Group that will be moved to the usual schedule of the LINCSseminar.

Philippe Martins will guide us in exploring the software radioplatform installed at Télécom-Paris.

The magic of container networking: a (not-so) short introduction
2022-12-07 11:30 - 12:30 | Room 4A113, 19 place Marguerite Perey, Palaiseau, France
Like regular applications, containers deployed within highlyvirtualized contexts need to communicate via a networking abstraction. Inorder to do so, common technologies adopt Linux bridges, virtualinterfaces, software switching (or routing) and other techniques. In thistalk, we explore how containerization has evolved from simple networknamespace definition to fully fledged pure-software routing solutions. Weprovide examples of networking between containers on the same machine(using the default docker model) towards applications spanning multiplemachines in cloud systems (as in Kubernetes). We conclude the talk withsome real-life examples of cloud networking.

Network Intelligence in the Open RAN: architectures, challengesand open experimental platforms
2022-11-30 15:00 - 16:00 | Room 4B01, 19 place Marguerite Perey, Palaiseau, France
The Open Radio Access Network (RAN) paradigm and its embodimentbased on the O-RAN Alliance specifications is poised to transform thetelecom ecosystem via virtualized and disaggregated RAN, open interfacesand RAN intelligent controllers (RICs). This talk will provide acomprehensive introduction to O-RAN, including a clear overview of thepotentials of the Open RAN paradigm and of the challenges to itsrealization. After a brief introduction on O-RAN and its architecture, wewill focus our attention on discussing how Artificial Intelligence (AI) anddata-driven optimization will transform the ecosystem and will identifychallenges to be overcome to de-risk AI, as well as how to design, trainand deploy AI-based solutions that are able to generalize across multipletopologies, network and traffic conditions. Finally, the talk with focuson showcasing selected results obtained using OpenRAN Gym(https://openrangym.com/), an experimental platform for research on O-RANdeveloped by our team at Northeastern University.

Unimodular Random Graphs
2022-11-30 11:30 - 12:30 | Telecom Paris, 19 place Marguerite Perey, Palaiseau, 91120,France
I will define the unimodularity of random graphs and then Iwill give several examples of applications concerning tessellations,optimization, dynamic systems, etc. If time permits, I will also showhow unimodularity allows to develop analysis tools for random graphs whichin a sense generalize Palm calculus of point processes.

Coverage and Stability Analysis of Cellular Network with TemporalTraffic
2022-11-16 15:00 - 16:00 | Room 4A467 - Telecom Paris, 19 place marguerite perey,Palaiseau, 91120, France
In this talk, we discuss the stability region characterizationof a random network when a traffic model is integrated into the networkgeometry description.

First, we characterized the stable coverageprobability of a random network. Starting from the notion of dynamiccoverage probability, the interaction between the queue states in thenetwork is taken into account using discrete Markov chain modelling of thequeues, where the typical user's service rate depends on the dynamiccoverage probability.

A more fine-grated description of the phenomenonis made by answering the question, "what is the proportion of unstablequeues in the network?" In this case, the notion of epsilon-stability isexploited, which describes the set of traffic intensities for which aqueue taken at random has a probability of diverging less thanepsilon.

Finally, the characterization of the stable region byconsidering the resource allocation is very difficult to obtain, becauseof the dependence between the geometry and the network's dynamicists andthe allocation strategy. However, the dynamic nature of the networkconsidered lends itself perfectly to description by a Markovian decisionprocess, for which reinforcement learning technologies can be proposed. Wetherefore study the stability-cost characteristic of the network operationaccording to the transmission policy.

Introduction to Multi-Agent Reinforcement Learning with Petting Zoo
2022-11-16 11:30 - 12:30 | Telecom Paris, 19 place Marguerite Perey, Palaiseau, 91120,France
PettingZoo (https://pettingzoo.farama.org/) is an open sourcePython source library supported by Farama Foundation to accelerate researchin multi-agent reinforcement learning (RL). Inheriting the standardfeatures of the popular RL interface Gym, it extends its API to handlemultiple agents by following an Agent Environment Cycle ("AEC") games mode.In this workshop we will:

Discover the PettingZoo library and exploresupported multi-agent environments,
Learn RL policies for a multi-agentbenchmark task in a PettingZoo environment,
Create a custom environmentin PettingZoo.

Talking to robots and drones: Network requirements for autonomousagents in factories and warehouses of the future
2022-11-09 15:00 - 16:00 | Room 4A467 - Telecom Paris, 19 place marguerite perey,Palaiseau, 91120, France
Future factories and warehouses will contain fleets ofautonomous agents to assist with monitoring and control. In this talk wewill describe a variety of machine learning problems that arise in such asetting. These include robot navigation, localization and multi-agentcoordination, as well as the construction of an analytics pipeline tounderstand the images streamed from an indoor drone. A common thread inall these problems is the utilization of cloud robotics, where most of theintelligence is migrated from the agents themselves to an edge cloud. Inthis environment the quality of the network is critical for effectiveoperation. We will discuss the network performance required to support suchsystems, and also describe some concrete deployments that support indoorfarming and warehouse inventory management.

An introduction to network calculus
2022-11-09 11:30 - 12:30 | Telecom Paris, 19 place Marguerite Perey, Palaiseau, 91120,France
Network calculus is a theoretical framework for performanceguarantees in communication networks. Here we present a first introductionto some fundamental concepts and principles in network calculus,including:

Arrival curve,
Leaky bucket,
Deterministic guarantees onqueueing delay and backlog,
The min-plus algebra and its connection withsystem theory.

PhD thesis defense "Analysis and Control of Online Interactionsthrough Neural Natural Language Processing"
2022-11-08 15:00 - 18:00 | Zoom + Amphi 4 chez Télécom-Paris, 19 Place Marguerite Perey,Palaiseau, 91120, France
Natural Language Processing is motivated by applications wherecomputers should gain a semantic and syntactic understanding of humanlanguage. Recently, the field has been impacted by a paradigm shift. Deeplearning architectures coupled with self-supervised training have becomethe core of state-of-the-art models used in Natural Language Understandingand Natural Language Generation. Sometimes considered as foundationmodels, these systems pave the way for novel use cases. Driven by anacademic-industrial partnership between the Institut Polytechnique de Parisand Google AI Research, the present research has focused on investigatinghow pretrained neural Natural Language Processing models could be leveragedto improve online interactions.

This thesis first explored howself-supervised style transfer could be applied to the toxic-to-civilrephrasing of offensive comments found in online conversations. In thecontext of toxic content moderation online, we proposed to fine-tune apretrained text-to-text model (T5) with a denoising and cyclic auto-encoderloss.

Then, a subsequent work investigated the human labeling andautomatic detection of toxic spans in online conversations. We released anew labeled dataset to train and evaluate systems, which led to a sharedtask at the 15th International Workshop on SemanticEvaluation.

Finally, we developed a recommender system based on onlinereviews of items, taking part in the topic of explaining users' tastesconsidered by the predicted recommendations. The method uses textualsemantic similarity models to represent a user's preferences as a graph oftextual snippets, where the edges are defined by semanticsimilarity.

The jury is composed as follows:

Mr. BenoîtSagot, Research Director, INRIA, France (Examiner, President)
Ms.Serena Villata, Tenured Researcher, CNRS, France (Reviewer)
Mr.François Yvon, Research Director, CNRS, France (Reviewer)
Mr. IonAndroutsopoulos, Professor, Athens University of Economics and Business,Greece (Examiner)
Ms. Marine Carpuat, Assistant professor, Universityof Maryland, United States (Examiner)
Mr. Slav Petrov, DistinguishedScientist, Google AI Research, United States (Examiner)
Mr. ThomasBonald, Professor, Télécom Paris, France (Ph.D. supervisor)
Mr.Lucas Dixon, Research scientist, Google AI Research, France (Ph.D.co-supervisor)

Distributed Optimization for Cellular Networks
2022-11-02 11:30 - 12:30 | Room 4A120, 19 place Marguerite Perey, Palaiseau, France
In this presentation, we will introduce a class ofdistributed optimization algorithms for resource allocation problem, builton potential game and related to simulated annealing. We will useconventional 3GPP-LTE like eICIC/FeICIC networks in the real life asexample to illustrate. A general objective is to address the entangledinter-cell interference and user association problem. Some related worksand questions would be discussed based on computer simulation results toexplain some observations.

Work Memory Requirements in Error Susceptible Quantum Networks
2022-10-26 15:00 - 16:00 | Room 4A467 - Telecom Paris, 19 place marguerite perey,Palaiseau, 91120, France
We consider the problem of path congestion avoidance innetworks of quantum repeaters and terminals. In other words, the avoidanceof situations when demands exceed capacity. We assume networks in which thesets of complete paths between terminals may affect the capacity ofrepeaters in the network. We compare the reduction of congestion avoidanceof path establishment algorithms: shortest-path establishment vs.layer-peeling path establishment. We observe that both strategies providean equivalent entanglement rate, while the layer-peeling establishmentalgorithm considerably reduces the congestion in the network of repeaters.Repeaters in the inner layers get less congested and require a lower numberof qubits while providing a similar entanglement rate.

MichelBarbeau,
Professor and Director
School of Computer Science
CarletonUniversity, Ottawa, Canada

Concurrent Programming in Python3 Using Asyncio
2022-10-26 11:30 - 12:30 | Telecom Paris, 19 place Marguerite Perey, Palaiseau, 91120,France
Asyncio is a library to write concurrent code using theasync/await syntax. Asyncio is used as a foundation for multiple Pythonasynchronous frameworks that provide high-performance network andweb-servers, database connection libraries, distributed task queues,etc. This tutorial presents the concepts and the syntax related to asynciothrough simple examples. It is mainly based on the asyncio tutorialprovided by realpython.com.

Quantum Cryptography: Quantum Key Distribution protocols
2022-10-19 11:30 - 12:30 | Telecom Paris, 19 place Marguerite Perey, Palaiseau, 91120,France
Quantum cryptography [BBE92] consists of the communication of ashared secret key between two users (Alice and Bob) which prevents aneavesdropper (Eve) from intercepting it without being detected, thesecurity being proven by the principles of quantum physics. Thesemechanisms are called quantum key distribution (QKD) protocols.
In thistalk, we will present the first QKD protocol proposed in 1984 by Bennetand Brassard [BB84], explaining how the protocol works and why Eve cannotintercept the distributed key without being detected. We will also brieflypresent another protocol proposed by Ekert in 1991 [Eke91]. Thisalternative protocol is based on the violation of Bell's inequalities withquantum physics, a fact that led to the 2022 Nobel Prize in Physics forAlain Aspect, John Clauser and Anton Zeilinger[Nobel2022].

References:

[BB84] Charles H. Bennett and GillesBrassard, "Quantum cryptography: Public key distribution and cointossing", in Proceedings of the International Conference on Computers,Systems and Signal Processing, pp. 175-179, Bangalore, 1984,republished in Theoretical Computer Science, vol. 560,? 2014, pp.7–11, https://dx.doi.org/10.1016/j.tcs.2014.05.025.

[Eke91] Artur K.Ekert, "Quantum cryptography based on Bell's theorem", Physical ReviewLetters, Vol. 67, no. 6, pp. 661-663, 1991,https://link.aps.org/doi/10.1103/PhysRevLett.67.661.

[BBE92] Charles H.Bennett, Gilles Brassard and Artur K. Ekert, "Quantum Cryptography",Scientific American, vol. 267, no. 4, 1992, pp. 50–57, http://www.jstor.org/stable/24939253.

[Nobel2022] The Nobel Prizewebsite, "The Nobel Prize in Physics 2022",https://www.nobelprize.org/prizes/physics/2022/summary/.

See alsoWikipedia:
- https://en.wikipedia.org/wiki/Quantum_cryptography,
-https://en.wikipedia.org/wiki/BB84.

Presentation material:https://www.ludovic-noirie.fr/html/sciences/quantum-cryptography/.

Extended Reality in 5G NR and Beyond
2022-10-12 15:00 - 16:00 | Room 4A467 - Telecom Paris, 19 place marguerite perey,Palaiseau, 91120, France
Extended Reality (XR) has been one of the ambitious researchtopics under development for several decades and today it is becomingmature enough to appear in the mass market. The replacement of smartphoneswith smaller wearable devices and headset mounted devices enables numerousnovel use cases in consumer, engineering, industrial, and healthcareareas, as well as represents a foundation for upcoming Metaverserevolution. The successful adoption of XR requires support from theunderlying 5G system, since XR introduce challenging requirements forradio mobile systems in terms of capacity and latency that do not perfectlyfit into the existing classification of fifth-generation (5G) applicationsand services. Additionally, power saving needs of user devices result in aclear trade-off between capacity and energy consumption. In this talk, wewill revise the main challenges discussed in 3GPP and possible solutions tofully support XR applications over 5G NR. In particular, we will highlightthe trade-off between power-saving and capacity focusing on possibleenhancements to power saving features.

Vehicular Networks, in Practice
2022-10-12 11:30 - 12:30 | Telecom Paris, 19 place Marguerite Perey, Palaiseau, 91120,France
Vehicular ad hoc networks are composed by vehicles sharing dataover the radio channel. They are the basic infrastructure of CooperativeIntelligent Transport Systems (C-ITS), where vehicles communicate withother vehicles, with other nomadic devices and with the infrastructure,in order to increase road safety and eventually to enable cooperative andautonomous driving applications. This talk will overview some practicalissues in the design and deployement of C-ITS originating from the use ofheterogeneous radio access technologies.

Distributed Task Processing with GNU Parallel
2022-10-05 11:30 - 12:30 | Room 4A467 - Telecom Paris, 19 place marguerite perey,Palaiseau, 91120, France
You probably tried many times to execute a script on multiplefiles in parallel, or to download multiple files at the same time, onlyto find out that you’ve exhausted your machine's resources or that somejobs have failed and needs to be retried. GNU Parallel is a tool forexecuting jobs in parallel using one or more computers. In this talk wewill see how GNU Parallel makes it easy to distribute and monitor tasks,independently of the programming language.

Commands used in thissession:

Dataset of URLs used as an example:

PCANT — Programable Capture and Analysis of Network Traffic
2022-09-28 15:00 - 16:00 | Salle 4A101 - Palaiseau, 19 place Marguerite Perey, Palaiseau,France
PCANT is a solution for streamlining the deployment ofarbitrary online traffic analysis methods inside networks. It allowsnetwork administrators to dynamically instantiate new monitoring techniqueson their network without the need for any manual setup, and datascientists to test new algorithms on a network without requiring any skillspertaining to network equipment administration and configuration.

Calculating the probability of the Condorcet Paradox usingcombinatorics tools
2022-09-21 15:00 - 16:00 | Salle 4A120 - Palaiseau, 19 place Marguerite Perey, Palaiseau,France
The paradox of Condorcet (1785) is a phenomenon that occurswhen people express their preferences amongst candidates. Calculating thelimiting probability of the Condorcet paradox can be done by probabilisticmethods. Krishnamoorthy and Raghavachari (2005) in particular, foundresults for the General Independent Culture. During this talk, I willfirst introduce some required knowledge in social choice theory and explainthe problem. Then, I will focus on Krishnamoorthy and Raghavachari (2005)work to detail and clear up their results. Finally, I will present ananalytic combinatorics method that permits to obtain the same kind ofresults. This will be the occasion to develop some classical technics ofasymptotic analysis.

References:

Marie Jean Antoine Nicolas deCaritat, marquis de Condorcet. Essai sur
l’application de l’analyseà la probabilité des décisions rendues à la pluralité
des voix.Imprimerie royale, 1785.
Mukkai Krishnamoorthy and MadabhushiRaghavachari. Condorcet winner
probabilities - A statistical perspective,2005. URL https://arxiv.org/abs/math/0511140.

2022 LINCS Workshop with the Scientific Committee
2022-06-29 09:00 - 2022-06-30 18:00 | Amphi Rose Dieng, 19 place Marguerite Perey, Palaiseau, France
This year Annual Workshop with the Scientific Committe willtake place in LINCS new premises in Palaiseau (@Télécom-Paris).

Fourmembers of our Scientific Committee will be with us in presence and theothers will be connected from abroad.

The event is reserved to the LINCScommunity but we will publish the Scientific Committee members' videorecordings afterwards.

As last year, the event will by hybrid (on placeand through Zoom), but we hope it will be a chance to gather togetheragain!

We'll have:

the Invited Talks by the Scientific Committee
the Scientific Highlights by the LINCS members
the "Elevator Pitch"presentations by LINCS PhD students

**WORKSHOP'S PROGRAM** (soon to bepublished)

Invertibility on the Poisson space and construction of Hawkesprocesses
2022-06-22 15:00 - 16:00 | Salle 4A301 - TP @Palaiseau, 19 place Marguerite Perey,Palaiseau, France, 91120, Ile de France, France
Following previous investigations by Üstünel about theinvertibility of some transformations on the Wiener space, we find someentropic conditions under which a random change of time is invertible onthe Poisson space. As a consequence, we provide a new construction ofHawkes processes. We also establish a new variational representation of theentropy.

Bio
Laurent Decreusefond is professor of probability andanalysis at Telecom Paris since … (well, most of you were not yet born).His research topics are focused around stochastic analysis and itsapplications, mainly to telecommunications systems.

Bidding efficiently in Simultaneous Ascending Auctions using MonteCarlo Tree Search
2022-06-15 15:00 - 16:00
We tackle in this work the problem for a player to efficientlybid in Simultaneous Ascending Auctions (SAA). Although the success of SAApartially comes from its relative simplicity, bidding efficiently in suchan auction is complicated as it presents a number of complex strategicalproblems. No generic algorithm or analytical solution has yet been able tocompute the optimal bidding strategy in face of such complexities. Bymodelling the auction as a turn-based deterministic game with completeinformation, we propose the first algorithm which tackles simultaneouslytwo of its main issues: exposure and own price effect. Our bidding strategyis computed by Monte Carlo Tree Search (MCTS) which relies on a newmethod for the prediction of closing prices. We show that our algorithmsignificantly outperforms state-of-the-art existing bidding methods. Moreprecisely, our algorithm achieves a higher expected utility by takinglower risks than existing strategies.

Enumerating Bipartite Graphs With Degree Constraints
2022-06-15 11:00 - 12:00 | Telecom Paristech, 19 place marguerite perey, Palaiseau,91120, France
Enumerating graphs with a given degree sequence is a problem ofinterest in many fields such as voting theory and statistics. If we areable to give nice asymptotic formulas [1], there does not exist an exactformula that is feasible to compute. Even though asymptotics alreadyprovides sufficient information for most applications, some require anexact enumeration. In this presentation, we will enumerate bipartitegraphs with degree constraints using a special combinatorial technique.This will be the occasion to make an introduction to some classicalcombinatorial tools such as generating functions [2].

[1] Asymptoticenumeration of digraphs and bipartite graphs by degree sequence, ALiebenau, N Wormald, 2020
[2] Analytic combinatorics, P Flajolet, RSedgewick, 2009

Stability of multiclass spatial birth-and-death processes withwireless-type interactions
2022-06-08 15:00 - 16:00 | Salle 4A113 - TP @Palaiseau, 19 place Marguerite Perey,Palaiseau, France
With the densification of wireless networks and theincreasing standards of wireless communication protocols, the study of thestochastic stability of wireless networks becomes increasingly important.Here, we study a multiclass spatial birth-and-death process on a compactregion of the Euclidean plane modeling wireless interactions as seen in atelecommunication network: users arrive at a constant rate and leave thenetwork at a rate inversely proportional to a shot-noise created by otherinterfering users in the network. The novelty of this work lies in theaddition of service differentiation, inspired by bandwidth partitioningintroduced in the latest generation of wireless networks. In this setup,users choose a fixed number of transmission channels, and only interferewith transmissions on the channels they use. We restrict our study tosymmetric networks, where users transmitting on the same number of bandshave the same stochastic properties in the network.
We define a generalmathematical framework using stochastic geometry and queuing the ory toolsto study this category of processes and we prove the existence of acritical arrival rate above which the system is always unstable. We thenintroduce a discretization of the dynamics to reduce the study of stabilityto which of a queuing network in a countable state space. We then find aclosed form of the critical arrival rate using fluid limits arguments. In asecond part, we define a heuristics to estimate the steady-state densitiesof users in the network. The first one relies on a Poisson approximation ofthe steady-states processes and allows us to define a heuristic for thecritical arrival rate of the network. The second heuristic uses a cavityapproximation and a second-order approximation to improve theperformance.

Easy Convex Optimization in Python with CVXPY
2022-06-08 11:00 - 12:00 | Telecom Paris, 19 place marguerite perey, Palaiseau, 91120,France
Convex Optimization provide a set of fast, practical tools andalgorithms which have applications accross many fields, from MachineLearning to Networking or Finance. However, most solvers require theirusers to have some knowledge of convex optimization to leverage theirpower. On the other hand, CVXPY is a Python-based modeling framework whichenables users to specify their problem with little to no mastery of convexoptimization. In this workshop we will:

Discover the basic conceptsunderlying CVXPY,
Learn how to formulate problems from machine learningand networking and solve them with CVXPY,
Introduce how extensions ofCVXPY can be used for non-convex problems.

Operationalizing machine learning in real world networks
2022-05-18 15:00 - 16:00 | LINCS + Zoom, 23 avenue d'Italie, Paris, 75013, France
Applications of machine learning to networking, fromperformance diagnosis to security, have conventionally relied on modelsthat are trained on offline packet traces, without regard to thelimitations of existing measurement systems nor the cost of gathering,computing, and storing the corresponding input features. As a result,there remains a significant gap between the development of statisticalmodels for network operations and their application and systemization inpractice. In this talk, we explore the challenges of operationalizingmachine learning models in real world networks. First, we develop newmodels to infer quality metrics (i.e., startup delay and resolution) forencrypted streaming video services and demonstrate the models are practicalthrough a 16-month deployment in 66 homes. Building on the lessonslearned, we design and develop Traffic Refinery, a new framework andsystem that enables a joint evaluation of both the conventional notions ofmachine learning performance (e.g., model accuracy) and the systems-levelcosts of different representations of network traffic. Traffic Refinerymakes it possible to explore different representations for learning,balancing systems costs related to feature extraction and model trainingagainst model accuracy.

Bio
Francesco Bronzino is an AssistantProfessor (maitre de conference) at Université Savoie Mont Blanc. Hisresearch interests broadly focus on the Internet infrastructure and theservices that populate it, particularly studying how to leverage emergenttechnologies to engineer software systems designed to measure and improvenetwork service performance. His work has been published papers in top-tierconferences in this area such as ACM Sigmetrics, IEEE/ACM SEC, andPAM.
Francesco received his Ph.D. in Electrical and Computer Engineeringfrom WINLAB at Rutgers University, working on the design of name basedservices for future Internet and mobile network architectures. Beforejoining Université Savoie Mont Blanc, he was a Research Scientist atNokia Bell Labs as well as Post-Doctoral research fellow at Inria Parisfocusing on network systems for application quality monitoring andinference.

Introduction to submodular functions
2022-05-18 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Submodularity is a property that models "diminishing return",when the benefits of adding a new element to a set decreases with the sizeof the set. One of its main advantages is a guarantee on the performanceof greedy algorithms for problems where the optimal solution isNP-hard.
This session aims at presenting submodular functions at abeginners' level:

Equivalent definitions;
A few practical examplesof submodular functions;
(1-1/e) approximation under cardinalityconstraints.

LINCS young researchers "elevator pitch" presentation n°3/2022
2022-05-11 15:00 - 16:00 | LINCS + Zoom, 23 avenue d'Italie, Paris, 75013, France
Bizon Monroc
Claire
Inria
PhD
Informatique

LeCorre
Thomas
Inria
PhD
Smartgreed

Shilov
Ilia
Inria
PhD
Game theoretic approaches fordecentralized electricity markets

Weber
Lucas
Inria
PhD
Théoriedu controle/reinforcement learning

LINCS young researchers "elevator pitch" presentation n°2/2022
2022-05-04 15:00 - 16:15 | LINCS + Zoom, 23 avenue d'Italie, Paris, 75013, France
Davydov
Michel
Inria
PhD
Dynamiques markoviennes à basede processus ponctuels et leursapplications

Khaniha
Sayeh
Inria
PhD

Popineau
Pierre
Inria
PhD
Study of the dynamics of spatial pointprocesses

Raynal
Maxime
Nokia Bell Labs
PhD
Alarm prediction incommunication networks via space-time pattern matching and explainablemachine learning

RoyChoudhury
Bharath
Inria
PhD

Sun
Guodong
Inria
PhD
Network Theory

Introduction to Gym and Stable Baselines for reinforcement learning
2022-05-04 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Gym by OpenAI is an open source interface to reinforcementlearning (RL) tasks. It comes with a set of standard tasks useful forbenchmarking RL algorithms (CartPole, Pendulum, Walking Humanoid,etc.), and an easy, standardized way to create a learning environment fora research problem. Stable Baselines 3 provides a set of reliable,rigorously tested PyTorch implementations of popular Deep RL algorithms tofacilitate results replication. Together they can be used for fast and easyRL benchmarks and prototyping.

In this workshop we will:

Discoverthe python gym library and explore standard RL tasks,
Use StableBaselines 3 to benchmark RL models in a Gym environment,
Learn how tocreate a Gym environment for a specific learning task.

PhD Thesis defense "Model-Based Reinforcement Learning for DynamicResource Allocation in Cloud Environments"
2022-05-02 10:00 - 13:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
The emergence of new technologies (Internet of Things, smartcities, autonomous vehicles, health, industrial automation, ...)requires efficient resource allocation to satisfy the demand. These newoffers are compatible with new 5G network infrastructure since it canprovide low latency and reliability. However, these new needs require highcomputational power to fulfill the demand, implying more energyconsumption in particular in cloud infrastructures and more particularly indata centers. Therefore, it is critical to find new solutions that cansatisfy these needs still reducing the power usage of resources in cloudenvironments. In this thesis we propose and compare new AI solutions(Reinforcement Learning) to orchestrate virtual resources in virtualnetwork environments such that performances are guaranteed and operationalcosts are minimised. We consider queuing systems as a model for clouds IaaSinfrastructures and bring learning methodologies to efficiently allocatethe right number of resources for the users. Our objective is to minimise acost function considering performance costs and operational costs. We gothrough different types of reinforcement learning algorithms (frommodel-free to relational model-based) to learn the best policy.Reinforcement learning is concerned with how a software agent ought to takeactions in an environment to maximise some cumulative reward. We firstdevelop queuing model of a cloud system with one physical node hostingseveral virtual resources. On this first part we assume the agent perfectlyknows the model (dynamics of the environment and the cost function),giving him the opportunity to perform dynamic programming methods foroptimal policy computation. Since the model is known in this part, we alsoconcentrate on the properties of the optimal policies, which arethreshold-based and hysteresis-based rules. This allows us to integrate thestructural property of the policies into MDP algorithms. After providing aconcrete cloud model with exponential arrivals with real intensities andenergy data for cloud provider, we compare in this first approachefficiency and time computation of MDP algorithms against heuristics builton top of the queuing Markov Chain stationary distributions. In a secondpart we consider that the agent does not have access to the model of theenvironment and concentrate our work with reinforcement learningtechniques, especially model based reinforcement learning. We firstdevelop model-based reinforcement learning methods where the agent canre-use its experience replay to update its value function. We also considerMDP online techniques where the autonomous agent approximates environmentmodel to perform dynamic programming. This part is evaluated in a largernetwork environment with two physical nodes in tandem and we assessconvergence time and accuracy of different reinforcement learning methods,mainly model-based techniques versus the state-of-the-art model-freemethods (e.g. Q-Learning). The last part focuses on model-basedreinforcement learning techniques with relational structure betweenenvironment variables. As these tandem networks have structural propertiesdue to their infrastructure shape, we investigate factored and causalapproaches built-in reinforcement learning methods to integrate thisinformation. We provide the autonomous agent with a relational knowledge ofthe environment where it can understand how variables are related to eachother. The main goal is to accelerate convergence by: first having a morecompact representation with factorisation where we devise a factored MDPonline algorithm that we evaluate and compare with model-free andmodel-based reinforcement learning algorithms; second integrating causaland counterfactual reasoning that can tackle environments with partialobservations and unobserved confounders.

Representing reputation in a multiagent system
2022-04-27 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
We consider the problem of a multiagent system where entitiesmeet and interact in a pairwise fashion. Agents may rate the outcome of theinteraction (e.g., on a discrete scale). In time, this allows to build areputation score for each agent. The aim of this talk is to explore how thereputation is represented, using a Bayesian approach, in the Beta andDirichlet reputation systems. The Dirichlet reputation system is thefoundation of Subjective Logic, which is a probabilistic logic system thatallows to explicitly represent uncertainty along with beliefs. Subjectivelogic, which provides among other things a formalism to treat transitivityof trust, is very useful in the representation of trust networks.

[1]A. Josang and R. Ismail, The beta reputation system, Proc. of the 15thbled electronic commerce conference, 2002.

[2] A. Josang and H.Jochen, Dirichlet reputation systems, Proc. of the Second IEEEInternational Conference on Availability, Reliability and Security(ARES), 2007.

[3] A. Josang, Subjective Logic: A formalism forreasoning under uncertainty, Springer Verlag, 2016.

Cache Allocation in Multi-Tenant Edge Computing via onlineReinforcement Learning
2022-04-20 15:00 - 16:00 | LINCS + Zoom, 23 avenue d'Italie, Paris, 75013, France
We consider in this work Edge Computing (EC) in amulti-tenant environment: the resource owner, i.e., the Network Operator(NO), virtualizes the resources and lets third party Service Providers(SPs - tenants) run their services, which can be diverse and withheterogeneous requirements. Due to confidentiality guarantees, the NOcannot observe the nature of the traffic of SPs, which is encrypted. Thismakes resource allocation decisions challenging, since they must be takenbased solely on observed monitoring information.
We focus on one specificresource, i.e., cache space, deployed in some edge node, e.g., a basestation. We study the decision of the NO about how to partition cache amongseveral SPs in order to minimize the upstream traffic. Our goal is tooptimize cache allocation using purely data-driven, model-freeReinforcement Learning (RL). Differently from most applications of RL, inwhich the decision policy is learned offline on a simulator, we assume noprevious knowledge is available to build such a simulator. We thus apply RLin an online fashion, i.e., the policy is learned by directly perturbingthe actual system and monitoring how its performance changes. Sinceperturbations generate spurious traffic, we also limit them. We show insimulation that our method rapidly converges toward the theoreticaloptimum, we study its fairness, its sensitivity to several scenariocharacteristics and compare it with a method from the state-of-the-art.

Towards an interactive visualization of the Internet
2022-04-13 15:00 - 16:00 | LINCS + Zoom, 23 avenue d'Italie, Paris, 75013, France
All kinds of Internet maps have been produced to emphasizevarious features of the network such as undersea cables [1], relationshipsbetween autonomous systems [2] or the use of the IPv4 address space [3].The Opte Project [4], started in 2003, uses the Large Graph Layoutalgorithm [5] to visualize paths between autonomous systems and theevolution of the Internet over time. This project has been widelysuccessful in communicating the nature of the Internet towards the world,including a map on display at the Museum of Modern Art in New York City. Inthis presentation we will revisit The Opte Project with 1) much morecomprehensive measurements of the Internet topology than previouslyavailable and 2) the use of web cartography tools to build interactivemaps. We will demonstrate such an interactive map, and discuss how thesemaps can be useful for research but also for communicating the nature ofthe Internet tonon-specialists.

[1] https://www.submarinecablemap.com
[2] https://www.caida.org/projects/cartography/as-core/
[3] https://www.caida.org/archive/id-consumption/census-map/
[4] https://www.opte.org
[5] Adai, Alex T., et al. "LGL: creating a map of proteinfunction with an algorithm for visualizing very large biologicalnetworks." Journal of molecular biology 340.1 (2004): 179-190.

Architecture in Object-Oriented Programming: A Case Study
2022-04-13 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
What is often done:

Explain basics of OOP (e.g.syntax),
Give principles of clean programming (e.g. SOLID) withsimplified examples, more or less realistic.

What I propose in thissession:

Take a more realistic example, based on my personalexperience,
See cases where application of principles is not as obviousas in didactic examples,
Show how understanding the "spirit" of theprinciples is the most important, to be able to adapt them to realproblems.

LINCS young researchers "elevator pitch" presentation n°1/2022
2022-04-06 15:00 - 16:15 | LINCS + Zoom, 23 avenue d'Italie, Paris, 75013, France
Elkael
Maxime
Télécom-SudParis(IMT)
PhD
Reinforcement learning, Networking

BenAmeur
Ayoub
Télécom-SudParis (IMT)
PhD
Edgecomputing

Bezerra de Araujo
Joao Paulo
Télécom-Paris(IMT)
PhD
Blockchain

Huang
Wei
Télécom-SudParis(IMT)
PhD
Wireless Network, ArtificialIntelligence

Patané
Rosario
Télécom-SudParis(IMT)
PhD
VehiCloud: How can vehicles increase the cloudintelligence?

Spallina
Alessandro
Télécom-Paris(IMT)
Ingenieur
5G, Edgecomputing

Tonkikh
Andrei
Télécom-Paris(IMT)
PhD
Distributed computing & Blockchain

The Weakest Failure Detector Abstraction
2022-04-06 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Many important distributed computing problems cannot be solvedin purely asynchronous fault-prone systems. These impossibilities can becircumvented with failure detectors, distributed oracles that providecomputing units with hints about failures. The weakest failure detector fora given problem defines necessary and sufficient assumptions about failuresthat enable the problem's solutions. In this meeting, we are going todiscuss how to determine two important weakest failure detectors: (1)Omega, the leader election failure detector for solving consensus and (2)Sigma, the quorum failure detector for implementing read-writestorage.

Literature:
[1] Tushar Deepak Chandra, Sam Toueg: UnreliableFailure Detectors for Reliable Distributed Systems. J. ACM 43(2): 225-267(1996).
[2] Tushar Deepak Chandra, Vassos Hadzilacos, Sam Toueg: TheWeakest Failure Detector for Solving Consensus. J. ACM 43(4): 685-722(1996).
[3] Carole Delporte-Gallet, Hugues Fauconnier, Rachid Guerraoui:Tight failure detection bounds on atomic object implementations. J. ACM57(4): 22:1-22:32 (2010).

Learning Optimal Bids in Second Price Auctions with Temporal andOverlapping Targeting Constraints
2022-03-30 15:00 - 16:00 | LINCS + Zoom, 23 avenue d'Italie, Paris, 75013, France
Ad placement in web-browsing and wireless mobiles is anincreasingly important component of the advertisement market. The marketsize is over $ 100 billion and counting. The mechanism is as follows: whena user opens a webpage or mobile ap a message is sent to an exchange wheremultiple bidders have the possibility of placing an ad that would targetthe right user, eg. age, sex, location, etc. The ad that is displayedcorresponds to the bidder who bids the highest while the cost is calculatedaccording to a first or second price. Typically bidders are DSP (DemandSide Platforms) that aggregate bids on behalf of clients who wish to run acampaign for a given length of time with certain targeting criteria. Thegoal is to minimize the total cost of obtaining the required number ofimpressions (ads that meet targeting criteria) over the duration of acontract. The real time constraint is that bidding must be done within100ms.

In this talk I will build upon the theory that we had earlierdeveloped for computing the least cost bids in the second price context.This involves the notion of an information state for the problem. There isa very rich primal-dual theory that emerges, one in the so calledimpressions space and the other in the contracts space. Computationally andstructurally the primal and dual views of the optimization have differentproperties that can be exploited to come up with fast algorithms.

Theoptimal solutions depend on solving a constrained convex optimizationproblem when the information state is known. However this is not readilyavailable and thus there is the problem of learning the information state.We show that in the second price case, stochastic approximation (SA)algorithms that operate on censored data (prices are only known by a bidderwhen the bidder wins) can be devised that solve the constrainedoptimization problem without learning the information state explicitly andwe prove their convergence. Finally I will present the dynamic behaviourthrough simulations.

Joint work with Ryan Kinnear (Waterloo) and PeterMarbach (Toronto). We thank Addictive Mobility Inc., a Pelmorex companyfor having proposed the problem and to Addictive Mobility, Ontario OCE VIPII, and NSERC funding the work.
Biography:
The speaker was educated atthe Indian Institute of Technology, Bombay (B.Tech, 1977), ImperialCollege, London (MSc, DIC, 1978) and obtained his PhD in Control Theoryunder A. V. Balakrishnan at UCLA in 1983. He is currently a UniversityResearch Chair Professor in the Dept. of ECE at the University ofWaterloo, Ont., Canada where he has been since September 2004. Prior tothis he was Professor of ECE at Purdue University, West Lafayette, USA.Since 2012 he is a D.J. Gandhi Distinguished Visiting Professor at theIndian Institute of Technology, Bombay, India and since May 2019 anAdjunct Professor at the Tata Institute of Fundamental Research (TIFR),Mumbai. He is a Fellow of the IEEE and the Royal Statistical Society. He isa recipient of the INFOCOM 2006 Best Paper Award, the ITC-27 2015 BestPaper Award, the Performance 2015 Best Paper Award and was runner-up forthe Best Paper Award at INFOCOM 1998. His research interests are instochastic modelling and analysis applied to complex networks andstatistical inference.

GeoLink: a Multimodal approach Internet Scale Geolocation Systemfor Improved Coverage and Accuracy
2022-03-23 15:00 - 16:00 | LINCS + Zoom, 23 avenue d'Italie, Paris, 75013, France
Despite being critical infrastructure, it remains challengingto accurately position the physical location of Internet routers. Incontrast to end-host geolocation where provider databases, registryinformation, and crowd-sourcing techniques can be successfully leveraged,router geolocation is known to be relatively inaccurate. While concertedefforts by the research community have produced recent systems capable ofsignificantly better accuracy, their coverage is generally low; astate-of-the-art systems is capable of geolocating only 7.6% of the routerIP addresses in Internet scale topology datasets. We develop, evaluate,and make public the GeoLink system for geolocating router IP addresses atInternet scale. Our key insights are three-fold: i) utilize uniquecapabilities and properties of routers, i.e., timestamps, aliases, andDNS names; ii) use multiple active measurement techniques to deriveper-link latencies and identify co-location; and iii) combine existingtechniques to improve coverage and refine candidate inferences. Tobootstrap GeoLink, we extract geolocation candidates from multiple datasources including existing geolocation databases, DNS names, andPeeringDB. We finally use our new measurement techniques to obtain soundlink latencies, extend coverage for bidirectional links, and ensurealiases are location geo-consistent. On a large validation set, GeoLinkprovides 5 times coverage improvement over existing systems, whilesimultaneously lowering error.

Shortbio:
Kevin Vermeulen is a researcher at CNRS. He has obtainedhis doctorate at Sorbonne Université ok internet cartography in 2020 anddid a postdoc at Columbia University on building systems to analyze andimprove internet paths before joining the CNRS. He is interested inbuilding measurement systems for a better understanding of the internet.

A brief introduction to Sagemath
2022-03-23 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
SageMath is a free open-source mathematics software systemlicensed under the GPL. It builds on top of many existing open-sourcepackages: NumPy, SciPy, matplotlib, Sympy, Maxima, GAP, FLINT, R andmany more. This session will give a quick overview of the features ofSagemath and how to get starting using Sagemath.

Prerequisite: eitherinstall Sagemath on your computer(https://doc.sagemath.org/html/en/installation/index.html) to benefit fromall the functionalities, or open a free account on CoCalc(https://cocalc.com) to use Sagemath online on a notebook (slow).

Usefullinks:

https://www.sagemath.org - the main webpage ofSagemath.
https://doc.sagemath.org/html/en/installation/index.html -installation instructions (many ways).
https://cocalc.com — CoCalc(Collaborative Calculation and Data Science) - you can open a free accountto use Sagemathonline.
https://doc.sagemath.org/html/en/reference/index.html - referencemanual of Sagemath.
https://doc.sagemath.org/html/en/tutorial/index.html- some tutorials.
https://www.sagemath.org/sagebook/ — book in openaccess « Computational Mathematics with Sagemath».
https://ask.sagemath.org — get help on coding with Sagemath (andso many examples).
https://groups.google.com/g/sage-devel — reportbugs, get help installing Sagemath, etc.
https://cython.org — knowmore about Cython.
https://trac.sagemath.org — Sagemath developmentpage (tickets, git, etc.).

Cryptocurrency Wallet Security Solutions
2022-03-16 15:00 - 16:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
With the growing popularity of cryptocurrencies, interest indigital signatures for securing keys is also on the rise. Researchers havebeen attempting since the 90’s to enhance known signature schemes withnew properties useful in specific cases. Due to their use incryptocurrencies, threshold ECDSA and EdDSA signatures have received muchattention in recent years.

In the past few months, a range ofprotocols has been published, allowing for non-interactive, proactivesecurity, identifiable aborts, fairness in the honest majority setting,and other properties such as dynamic settings and interoperability.Proactive security and non-interactivity properties are the most studiedsolutions for cryptocurrency securities. Proactive security is the notionof defending a distributed system against an attacker who compromisesdifferent devices through its lifetime, but no more than a thresholdnumber of them at any given time. Non-interactivity: allowing a subset of agroup of people to generate a signature without having to interact. Asolution to the quest for noninteractivity is to divide the signature intotwo steps: the presigning (or offline) phase condenses most communicationrounds and can be performed long before the signature is needed, while thesigning (or online) phase takes only a single round and happens after themessage is chosen. Most protocols however require that the subset of thesigners be fixed before presigning, since they are the only ones whoparticipate in it.

In this talk, I will present our two novelnon-interactive threshold ECDSA protocols that remove the need for thisassumption either partially or entirely. The security of these schemes isproven in a simulation-based definition. To evaluate the performance of thesecond protocol, it has been implemented in RUST and benchmarked.Additionally, I will talk about the extension of this work towardsproactive security and interoperability-based solutions.

Wireless communication channel for dummies (like me)
2022-03-16 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
The bulk of the scientific talks on wireless communicationbegin with: "Let’s consider the classic model y = Hx where x and y arethe transmitted and received (complex) signals, respectively, and H isthe channel (complex) matrix." Let’s try to understand together what thismeans from basic principles.

Material largely inspired from chapter1,3 of https://web.stanford.edu/~dntse/wireless_book.html.

Slides.

LINCS-NEMO WORKSHOP on V2X
2022-03-10 09:00 - 2022-03-11 18:00 | LINCS + Zoom, 23 avenue d'Italie, Paris, 75013, France
LINCS-NEMO workshop on vehicularnetworks

Program

MARCH 2022, THURSDAY 10TH AND FRIDAY11TH (9AM – 6PM)

To make our vehicles smarter and our roadssafer, communications are of paramount importance: vehicles willcommunicate with other vehicles (V2V), with the infrastructure (V2I), andwith everything (V2X). Enabling and exploiting V2X communication at scaleis still facing a huge amount of challenges, at all levels of the networkprotocol stack, in terms of global network architecture, up to the designof advanced next-generation applications.

This international workshopwill bring together researchers from the industry and Academia working on awide class of topics including models and performance of the physicalcommunication channel at different bands, vehicle positioning andsensing, 5G networks for V2X, overall network architecture, services ontop of V2X and their requirements, edge computing for vehicularapplications, etc.

Organization Committee

François Baccelli(Inria)
Andrea Araldo (Télécom-SudParis)
Anna Frisone(LINCS)

THE WORKSHOP WILL BE HELD IN APRESENCE-REMOTE HYBRID FORM AT LINCS – 23 AVENUED’ITALIE, 75013 PARIS

INTERACTIVE MAP FOR LUNCH OPTIONS CLOSE TO THELINCS [CREDITS TO ALESSANDROSPALLINA]
https://www.google.com/maps/d/edit?mid=1L-wdmqbhM9Btn2DPITTox41eTl2SmQJk&usp=sharing
Confirmed speakers:
OnurALTINTAS – Toyota : “Cooperation inAutomation”

Connected, automated, shared and electric (CASE)continues to be the dominant keyword in the automotive industry. In thistalk we will briefly look into the general computing and communicationsvision supporting CASE and summarize recent developments in connectedvehicles area, including emerging standards.

CarlaCHIASSERINI – PoliTo : “Crowd-sourcing learning:Leveraging Connected Cars in ML Tasks”

One of the fundamentalcomponents of many applications in the automotive domain is represented bya machine learning (ML) task. At the same time, vehicles are becomingmobile, powerful computers that can gather, share, and process data;thus, they can not only consume services, but also contribute to enablingML-based applications. This can be enacted through distributed learningapproaches, according to which the learning process is split among anumber of computing nodes. Distributed learning, however, may lead tosignificant communication overhead, or to learners converging to differentmodels. In this talk, we therefore introduce a new distributed learningscheme that, with the assistance of the network edge, aims at exploitingthe vehicles’ data and computing capabilities, while enabling anaccurate learning process. Further, the talk will discuss differentapproaches to distributed learning and edge computing that can effectivelyinvolve connected vehicles.

Chang-sik CHOI – HongikUniversity : “Stochastic Geometry for Modeling and Analysis ofVehicular Networks”

In this lecture, I will talk about recent work onthe modeling and analysis of vehicular networks based on stochasticgeometry. I will cover a few topics such as SIR of vehicle-to-allcommunications, data harvesting based on vehicles, and an analyticalframework for blockage. This lecture aims to provide a high-level idea onmathematical frameworks such as the Cox point process, random graphs, andBoolean model, to characterize vehicular network architectures and toidentify new challenges therein.

HarpreetDHILLON – VirginiaTech “Poisson Line Cox Process:Distributional Properties and Applications to Vehicular Networks”

Inthis talk, we present a doubly-stochastic model for vehicular networks,termed the Poisson Line Cox Process (PLCP), in which the layout of theroads is modeled as a Poisson line process (PLP) and the wireless nodes,such as vehicles and roadside units, are modeled as independent Poissonpoint processes (PPPs) on each road. We will first share a brief historicalperspective of PLP tracing back to a question posed by Neils Bohr thatinspired early work on line processes. We will then discuss theconstruction of PLCP and a few representative distributional properties tohighlight its analytical tractability. The rest of the talk will focus onthe applications of PLCP to vehicular networks. Our specific focus will beon the rate and coverage analysis of a comprehensive cellularvehicle-to-everything (C-V2X) setup consisting of vehicular nodes,roadside units, and macrocellular base stations. As a part of thisanalysis, we will also discuss some results related to the load served bymacrocellular base stations and roadside units that will rely onunderstanding the intersection of PLP with the typical cell of anindependent Poisson Voronoi tessellation modeling the service regions ofmacrocellular base stations. We will conclude the talk with a comparison ofthis model with the one used in 3GPP simulation studies. Time permitting,we will also discuss the problem of shortest path distance distribution inPLCP and its potential applications to vehicular networks.

FalkoDRESSLER – TU Berlin : “From Vehicular Networking to5G and Mobile Edge Computing to 6G and Virtual Edge Computing”

We willdiscuss the challenges and opportunities of the connected cars vision inrelation to the need for distributed data management solutions ranging fromthe vehicle to the mobile edge and to the data centers. Vehicularnetworking solutions have been investigated for more than a decade butrecent standardization efforts just enable a broad use of this technologyto build large scale Intelligent Transportation Systems (ITS). Modern 5Gnetworks promise to provide all means for communication in this domain,particularly when integrating Mobile Edge Computing (MEC). However, itturns out that despite the many advantages, it is unlikely that suchservices will be provided with sufficient coverage. As a novel concept,vehicle micro clouds have been proposed that bridge the gap between fullydistributed vehicular networks based on short range device to devicecommunication and 5G-based infrastructure. Using selected applicationexamples, we assess the advantages of such systems. We conclude the talkby shedding light on future virtual edge computing concepts that willenable edge computing even considering minimal deployment and coverage of5G MEC.

Thierry ERNST – YoGoKo : “Cooperative ITSstandards and technologies for automated connected & cooperativemobility”

In this talk, Dr. Thierry Ernst is going to highlight thetechnologies and standards developed for Cooperative Intelligent TransportSystems (C-ITS) services, i.e. services developed to share data betweenvehicles, other road users, the roadside infrastructure, the urbaninfrastructure, and control and service centers in the cloud. This sharingof data is essential to improve road safety and traffic efficiency and todevelop many other innovative value added services for mobility of peopleand goods, including but not limited to connected cooperative andautomated mobility (CCAM). This presentation will particularly highlightstandards developed at ISO, CEN and ETSI under deployment in Europe andother regions in the world. C-ITS services under deployment rely on the ITSstation communication and data management architecture. This architecturecombines localized communication technologies (without support of telecominfrastructure) together with networked communication technologies (withsupport of telecom infrastructure) and facilities to manage and share databetween various service domains and stakeholders.

Nuria GONZÁLEZPRELCIC – NC State : “Integrating sensing andcommunication in millimeter wave vehicular networks”

Wireless networksare incorporating millimeter wave spectrum and beyond. This, together withMIMO technology using large antenna arrays, provides the keyingredients to develop integrated communication and sensing systems thatexploit the similarities between the required hardware, the signalprocessing algorithms or the sensing and communication channels. This isespecially relevant in vehicular networks, given the wealth of sensorsavailable in a vehicular environment and the impact on safety that sensingcapabilities can provide. In this talk, I provide an overview of machinelearning and signal processing techniques that enable different types ofintegration between sensing and communication. First, I describealternative strategies that pursue a fruitful collaboration amongcollocated sensing and communication modules which may be using differenthardware or radio resources. I discuss algorithms for sensor-aidedmillimeter wave communication that significantly reduce the overheadassociated with link configuration and reconfiguration or enable earlyblockage detection and array reconfiguration. Then I review the oppositesetting: sensing aided by communications and its applications, wherecommunication provides information for enhanced sensing. Leveragingcommunication for sensing gives a new perspective on joint communication,tracking and localization at mmWave frequencies. Throughout the talk, Imake the case that time is right for communication and sensing to beconsidered together. I also explain why communication and sensing willlikely to be the defining physical layer feature of 6G.

MartinHAENGGI – Notre Dame : “Transdimensional Modeling andReliability Analysis of Vehicular Networks on General StreetSystems”

Due to their rapidly changing topology, vehicular networksare naturally modeled and analyzed using tools from stochastic geometry. Iflinks are required to be highly reliable, as in vehicular safetymessaging, it is essential to find the maximum link density or distance ortransmit probability that can be accommodated under a reliabilityconstraint. To answer these questions, standard spatial averages areinadequate; instead, meta distributions (distributions of conditionaldistributions) need to be derived, which is considerably harder. To do sowhile maintaining wide generality in the underlying street system wepropose an approximate approach based on transdimensional models, whichare a union of one- and two-dimensional point processes. This leads tosignificant simplifications and allows for a unified treatment of modelswith finite and infinitely long streets and intersections of arbitraryorder.

Robert HEATH – NC State : “Beam training inV2X leveraging machine learning”
Millimeter-wave (MmWave) vehicularcommunication enables massive sensor data sharing in vehicular systems,leading to enhances in automation, safety, transportation efficiency andinfotainment. Estimating and tracking beams in mmWave vehicularcommunication, however, is challenging due to the use of large antennaarrays and high mobility in the vehicular context. In this talk, Iintroduce data-driven approaches for beam training that leverage positioninformation or underlying channel statistics to reduce training overhead.Data driven machine learning is valuable for V2X given the underlyingcorrelations that can be exploited as vehicles travel similar paths throughthe environment.

Vincenzo MANCUSO – IMDEANetworks : “Edge-assisted platooning control andoptimization”

Grouping vehicles into platoons promises to improve roadcapacity, driver safety, and fuel consumption. However, when largeplatoons have to allow for cross traffic maneuvers, e.g., because ofhighway junctions, the ability to control single large platoons is notsufficient, and chaining smaller platoons becomes necessary. To this aimwe study how to harmonically coordinate the maneuvers of multiple platoonsand define a multi-platoon control architectures, analyzing costs andbenefits of multi-platooning and investigating on the feasibility ofedge-controlled multi-platoons. We also consider distributed machinelearning tools to handle the platoon control as a virtual network functionresiding at the edge of a cellular network. Using simulation, we show thatmulti-platoons can be effectively controlled as long as the latency betweenindividual platoon managers and the multi-platoon manager is kept below afew tens of milliseconds. Instead, the latency between vehicles andmanagers is one order of magnitude less critical.

Tien vietNGUYEN – Qualcomm : “V2X at Qualcomm”

Nowadays,with the proliferation of electronics components, vehicles on the roadsare becoming ever smarter and more connected. At Qualcomm technology, wepioneer the ubiquitous 5G connection between vehicles to the cloud, V2Xcommunication among vehicles and infrastructure to provide maximum benefitsto the transportation ecosystem. In this talk, we would like to showcasethree examples where such connectivity improves the safety, positioning,and enhanced user experience. In the first example, we provide an examplewhere the ubiquitous 5G connection helps to address the issue of vehicularradar interference. The second example demonstrates how V2X communicationcan augment positioning in scenarios where GNSS is not available. In thethird example, we show how such communication can improve safety anddriver experience by providing real time information about trafficconditions and road hazards.

Vitaly PETROV – Nokia BellLabs : “Terahertz Band Vehicular Communications”

Future smartconnected vehicles are envisioned to incorporate high-data ratecommunications and high-resolution radar sensing capabilities operating inthe millimeter-wave and (sub-)terahertz (THz) frequencies. This lecturewill cover the recent progress in developing terahertz band wirelesssystems focusing on vehicular setups. The specifics of THz wireless channelare first revealed. Then, several aspects are discussed related to thedesign of reliable and efficient solutions for physical and link layers.Finally, some open research problems in the area areoutlined.

Oyunchimeg SHAGDAR – VEDECOM : “MessageRedundancy and Congestion Control for V2X Collective PerceptionService”

One of the key roles of C-ITS is to contribute in extendingperception of vehicles and road users so that they can avoid potentialaccidents. Such an extended perception is built by information exchangeamong vehicles, pedestrians, and infrastructure using different types ofmessages including Cooperative Awareness Message (CAM) and CollectivePerception Message (CPM). The data carried by these messages are critical,however, they can be resource-consuming and may contain highly redundantinformation. In this work, we propose a context-aware CPM generationschemes that take into account message contents and roadside infrastructureavailability. An extensive simulation has been carried out to evaluate theperformances of the schemes. The results present remarkable performanceimprovements provided by the schemes, particularly in terms of PacketDelivery Ratio (PDR), CBR (Channel Busy Ratio), and awareness ratecompared to the conventional non-context-aware CPM generationstrategy.

Henk WYMEERSCH – Chalmers :“Radio-Localization for 5G and Beyond 5G V2X”

Increases in carrierfrequencies and bandwidths, driven by high-rate communication applicationshave led to vastly improved capabilities for user positioning. Withresearch underway towards 6G, opportunities for integrating positioningand sensing into the communication system have become even more apparent.The aim of this talk is to provide an overview of this evolution, focusingon 5G and 6G. The talk will comprise 3 main parts: first, the foundationsof radio-based positioning are introduced. Second, we go deeper into 5Gpositioning, covering both the standard approaches, as well as moreforward-looking potential modifications. In the last part, we consider 6Gfrom the perspective of positioning and sensing, highlighting some of thenovel enablers, methods, potentials, but also the correspondingchallenges.

Given the limited number of places due toanti-covid restrictions, we invite you to register throughthe link here below to receive the details ofthe Zoom streaming. We’ll keep you posted about the possibility toattend in presence.
Registration LINK

Wireless scheduling subject to slice constraints
2022-03-02 15:00 - 16:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
We present methods for achieving slice guarantees in cellularnetworks by adjusting the MAC scheduling weights. A network slice is aportion of a network that is carved out for a particular set of users or aparticular type of traffic. One slice provided by a national operator couldbe used to support a Mobile Virtual Network Operator (MVNO), another couldsupport Ultra-Reliable Low Latency Communication for vehicularapplications, and a third could support an enterprise application such asan advanced wireless enabled factory.
Our goal is to optimize networkutility (e.g. Proportional Fairness) subject to a variety of sliceconstraints such as the minimum aggregate rate provided to a slice, theminimum total resources provided to a slice, or a guarantee on thefairness of service within a slice. We show how such constraints can beachieved using multiplicative or additive adjustments to the standardProportional Fair scheduler weights and we analyze the differences betweenthe two approaches. We also discuss how the interaction between theconstraints can make the situation significantly more complex than theanalogous problem with single-user minimum rate constraints only. Forexample, with minimum resource constraints the optimum solution can lie inthe interior of the achievable rate region.
This is joint work with SemBorst, Siegfried Klein, Hans Kroener and Silvio Mandelli.

SOLID Principles in Object-Oriented Programming
2022-03-02 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Once you know the basics of object-oriented programming, amore difficult step can be to design the architecture of your code for agiven project: what should be an object, how to organize the classes, howto make them work together, etc. To that end, you can find help in theprogramming principles gathered in the SOLID acronym:

Single-Responsibility Principle.
Open-Closed Principle.
LiskovSubstitution Principle.
Interface Segregation Principle.
DependencyInversion Principle.

In this talk, I will explain what these esotericterms mean and illustrate them with very simple examples, requiring only aminimal knowledge of Python.

Application of stream graphs theory on internet topology
2022-02-23 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
The network topology of the internet and its dynamics has beenstudied extensively for two decades. Meanwhile, Latapy et al. extendedgraph theory to capture the temporal and structural nature of interactions.In this session we propose to present the stream graphs and link streamswork applied to internet topology dynamics.

PhD thesis defense "Unsupervised Anomaly Detection: Methods andapplications"
2022-02-18 14:30 - 17:00 | Zoom + Amphi 5 chez Télécom-Paris, 19 place Marguerite Perey,Palaiseau, 91120, France
An anomaly (also known as outlier) is an instance thatsignificantly deviates from the rest of the input data and being defined byHawkins as an observation, which deviates so much from other observationsas to arouse suspicions that it was generated by a differentmechanism.Anomaly detection (also known as outlier or novelty detection) isthus the machine learning and data mining field with the purpose ofidentifying those instances whose features appear to be inconsistent withthe remainder of the dataset. In many applications, correctlydistinguishing the set of anomalous data points (outliers) from the set ofnormal ones (inliers) proves to be very important. A first application isdata cleaning, i.e., identifying noisy and fallacious measurement in adataset before further applying learning algorithms.However, with theexplosive growth of data volume collectable from various sources, e.g.,card transactions, internet connections, temperature measurements, etc.the use of anomaly detection becomes a crucial stand-alone task forcontinuous monitoring of the systems. In this context, anomaly detectioncan be used to detect ongoing intrusion attacks, faulty sensor networks orcancerous masses.The thesis proposes first a batch tree-based approach forunsupervised anomaly detection, called Random Histogram Forest (RHF). Thealgorithm solves the curse of dimensionality problem using the fourthcentral moment (aka kurtosis) in the model construction while boastinglinear running time. A stream based anomaly detection engine, called ODS,that leverages DenStream, an unsupervised clustering technique ispresented subsequently and finally Automated Anomaly Detection engine whichalleviates the human effort required when dealing with several algorithmand hyper-parameters is presented as last contribution.

Securing communications in the C-ITS
2022-02-16 15:00 - 16:00 | LINCS + Zoom, 23 avenue d'Italie, Paris, 75013, France
Cooperative Intelligent Transport Systems allow connectedvehicles to communicate with each other, with the road-sideinfrastructure, and with other smart devices to improve road safety andoptimize traffic efficiency. They allow to develop new services to preparefuture semi-automated or fully automated vehicles.
Applications are basedon the exchange of V2X beacons broadcast by stations and received byneighboring vehicles. The beacons contain alerts and/or kinematicinformation of the originating station.

The functionality of theservices and the safety of their operation depend on the correctness of thecommunication between stations. In this talk we explore the characteristicsof the vehicular network and the measures that can be taken to secure thecommunication within the C-ITS.

Graph-based contributions to machine learning
2022-02-09 14:30 - 17:30 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
A graph is a mathematical object that makes it possible torepresent relationships (called edges) between entities (called nodes).Graphs have long been a focal point in a number of problems ranging fromwork by Euler to PageRank and shortest-path problems. In more recenttimes, graphs have been used for machine learning.

With the advent ofsocial networks and the world-wide web, more and more datasets can berepresented using graphs. Those graphs are ever bigger, sometimes withbillions of edges and billions of nodes. Designing efficient algorithms foranalyzing those datasets has thus proven necessary. This thesis reviews thestate of the art and introduces new algorithms for the clustering and theembedding of the nodes of massive graphs. Furthermore, in order tofacilitate the handling of large graphs and to apply the techniques understudy, we introduce Scikit-network, a free and open-source Python librarywhich was developed during the thesis. Many tasks, such as theclassification or the ranking of the nodes using centrality measures, canbe carried out thanks to Scikit-network.

We also tackle the problem oflabeling data. Supervised machine learning techniques require labeled datato be trained. The quality of this labeled data has a heavy influence onthe quality of the predictions of those techniques once trained. However,building this data cannot be achieved through the sole use of machines andrequires human intervention. We study the data labeling problem in agraph-based setting, and we aim at describing the solutions that requireas little human intervention as possible. We characterize those solutionsand illustrate how they can be applied in real use-cases.

Object-Oriented Programming in Python
2022-02-09 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
We will deep dive into the OOP paradigm and see how it’simplemented in Python. This session will be beginner-friendly and aims togive explanations and practical examples on how to use OOP in a regularbasis.

Slides
Progress sheet:https://docs.google.com/spreadsheets/d/1lBwaAsTdWx8Pl8WSZWLbaOb89MqBA7qmAE0qxsZ-_og/edit?usp=sharing

The Quantum Internet: Recent Advances and Challenges
2022-02-02 15:00 - 16:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
Quantum information processing is at the cusp of havingsignificant impact on technology and society in the form of providingunbreakable security, ultra-high-precision distributed sensing withapplications to metrology and science discovery (e.g., LIGO), andpolynomial speeds up on search with implications to big data. Most of theseapplications are enabled by high-rate distributed shared entanglementbetween pairs and groups of users. A critical missing component thatprevents crossing this threshold is a distributed infrastructure in theform of a world-wide “Quantum Internet”. This motivates our study ofquantum networks, namely what is the right architecture and how should itoperate, i.e., route multiple quantum information flows, and dynamicallyallocate resources fairly.

In this talk I will review a specific classof quantum networks - those that generate and distribute entangled quantumstates to pairs or groups of users. I will present opportunities andchallenges related to resource sharing in such networks focusing onsimilarities to and differences from classical networks. I will alsopresent challenges of analyzing the performance of such networks. I willend the talk with a list of open problems.

Infinite Hidden Markov Models
2022-02-02 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
The Hidden Markov Model is a generative model in which thedistribution of the observations depends on the state of a Markov chain.These models have been successfully applied to many problems, includingpart-of-speech tagging, handwriting recognition and time seriesclustering. A common issue is to infer the parameters of the HMM, given aset of observations, when the number of latent states is unknown. Atraditional approach is to evaluate models of different dimensions andchoose the one that offers a good compromise between the complexity of themodel, and its adequacy to the data, in order to preventover-fitting.

In this talk we will present the Infinite Hidden MarkovModel, or HDP-HMM (Hierarchical Dirichlet Process Hidden Markov Model),which offers an alternative solution to this problem. The HDP-HMMgeneralizes the HMM model by considering the number of state itself as anunknown quantity to be inferred, through Bayesian inference. We willdiscuss the HDP-HMM and its variants, as well as an application to networkdelay time series clustering.

References
[1] Beal, M. J.,Ghahramani, Z., & Rasmussen, C. E. (2002). The infinite hiddenMarkov model. Advances in neural information processing systems, 1,577-584.
https://people.csail.mit.edu/jrennie/trg/papers/beal-ihmm-03.pdf
[2] Fox, E. B., Sudderth, E. B., Jordan, M. I., & Willsky, A.S. (2011). A sticky HDP-HMM with application to speaker diarization. TheAnnals of Applied Statistics,1020-1056.
http://willsky.lids.mit.edu/publ_pdfs/204_pub_AAS.pdf

A stochastic matching between graph theory and linear algebra
2022-01-26 15:00 - 16:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
Stochastic dynamic matching has numerous applications, rangingfrom supply-chain management to kidney exchange programs. In amatching problem, different classes arrive according to independentPoisson processes. Unmatched items are stored in a queue, and twoitems can be matched if their classes are neighbors in a (simple)compatibility graph. We analyze the efficiency of matching policiesin terms of system stability and of matching rates between differentclasses. Our results, which rely on the observation of theconservation equation between departures and arrivals, arethreefold. We first relate the way the conservation equation mapsarrival and departure vectors, the structure of the compatibilitygraph, and the existence of a stable policy. This allows us toderive a necessary and sufficient stability condition that isverifiable in polynomial time. Secondly, we describe the convexpolytope of non-negative solutions of the conservation equation. Whenthis polytope is reduced to a single point, we give a closed-formexpression of the solution; in general, we characterize thevertices of this polytope using again the graph structure.Lastly, we show that greedy policies cannot, in general, achieveevery point in the polytope. In contrast, non-greedy policies can atleast reach any point of the interior of this polytope, and can alsoreach its boundary if a specific condition on its vertices ischecked.

This is a joint work with Céline Comte and Ana Bušic.

Accountable distributed computing
2022-01-19 15:00 - 16:00 | LINCS + Zoom, 23 avenue d'Italie, Paris, 75013, France
There are two major ways to deal with failures in distributedcomputing: fault-tolerance and accountability. Fault-tolerance intends toanticipate failures by investing into replication and synchronization, sothat the system’s correctness is not affected by faulty components. Incontrast, accountability enables detecting failures a posteriori andraising undeniable evidences against faulty components.

In this talk,we discuss how accountability can be achieved, both in generic andapplication-specific ways. We also discuss how fault detection can becombined with reconfiguration, opening an avenue towards "self-healing"systems that seamlessly replace faulty components with correct ones.

Developping in Python
2022-01-19 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
When you develop a Python project, it is highly recommendedthat you design it as a Python package, which gives you access to avariety of powerful development tools. With Package Helper 2, it is easyand fast to do it! Things will go this way:

The file structure of yourpackage is created in less than a minute with Cookiecutter.
The PyCharmeditor is configured to generate the documentation locally and run the unittests.
Your documentation includes a “coverage” page, whichdisplays what parts of the package are covered by the unit tests.
Yourproject is hosted on GitHub, which is configured to run the unit testswith several versions of Python and to automatically generate and publishthe documentation.
When desired, GitHub publishes your package onPyPI, so that any Python user can install it.

Tutorial:https://package-helper-2.readthedocs.io/en/latest/tutorial.html.

Progress Sheet:https://docs.google.com/spreadsheets/d/19dI-wMSOaWd_OSoBoOtZRMJY7AMrdRz3UIV-BpcABGI/edit?usp=sharing.

Poisson approximations of sums of Bernoulli random variables
2022-01-12 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Approximation by Poisson distributions or processes is of greatinterest in many applications including networks, queueing theory and evenneuroscience, as the Poisson distribution arises as a natural limitdistribution in many situations involving independent "rare" events. Inthis talk, we propose to give an overview of classical methods of Poissonapproximation of sums of Bernoulli random variables. We will first focus onLe Cam's result for the case of independent random variables and give aproof based on the coupling method. We will then focus on the case when thevariables are not necessarily independent and present the classicalChen-Stein method.

Testing in Python
2021-12-15 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Thanks to its dynamic nature, it is extremely easy toprototype code with Python.
However, this also means that it is difficultto catch errors before executing the program.
Software tests allow toautomatically check the behavior of a program, thus freeing time for thedeveloper, and increasing the confidence in the correctness of theprogram.
In this session we will discuss the test facilities provided byPython, to write robust and self-documenting code.

Slides

Progresssheet

Meta Distributions and Joint Geometric Modeling of CellularNetworks
2021-12-08 15:00 - 16:00 | LINCS + Zoom, 23 avenue d'Italie, Paris, 75013, France
In cellular networks, there is a growing emphasis on the userexperienced performance and ultra-reliable low-latency communications.This necessitates an analysis of the performance achieved by most usersmost of the time, rather than a subset of users with peakperformance. To this end, the meta distribution is introduced as anessential analytical tool in the framework of stochastic geometry. In thefirst part of the talk, we discuss some analytical results about the metadistribution in cellular networks. Exploiting the independence betweenthe small-scale fading and the large-scale path loss, we derive theseparability of the meta distribution for arbitrary fading in Poissonnetworks. We further look at the impact of fading statistics, noise, andthe network geometry.In the second part, we propose a jointspatial-propagation model for coverage-oriented cellular networks. Thismodel ascribes the irregular deployment of base stations to anintelligent design by the operators and reverse-engineers the underlyingcell-dependent shadowing from the shape and size of the Voronoi cells.

MIMO Performance: From Theory to Practice
2021-12-08 11:00 - 12:00 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
In the past decades, multiple antenna systems were widelyemployed in modern wireless network to improve the communicationperformance. For example, iPhone XS is equipped with six antennas andNokia 5G AirScale has up to sixty-four antennas. How multiple inputmultiple output (MIMO) technique boosts both the channel capacity and linkreliability simultaneously? In this reading group sharing, I will discussthe theoretical foundation of MIMO setup by Emre Telatar at the end of 20thcentury and a powerful statistical tool, Wishart distribution, to analyzeMIMO performance. Then I will go through its development from early dayspoint-to-point MIMO to today’s massive MIMO. We can discover how MIMOovercomes the challenges along the way of bringing theoretical analysisinto current real applications.
Here the presentation's slides.

MPLS in Internet topologies
2021-12-01 10:45 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Dear all, The Internet Measurement reading group will meet onWednesday 1st.

In this session, Matthieu Gouel (Sorbonne Université,LIP6) will talk about MPLS in Internet topologies.

I encourage you tojoin us at 10:45 for a virtual coffee break, so that the talk beginsat 11:00.
https://telecom-paris.zoom.us/j/98157419805?pwd=[REDACTED]

Abstract

MPLS is now widely used by autonomoussystems to carry IP packets through their network. In order to detect MPLStunnels, multiple active measurement techniques have been developed.
Inthis reading group we talk about how to detect MPLS tunnels and how itaffects Internet topologies with the support of multiple papers.

Paperlist:

Revealing MPLS Tunnels Obscured from Traceroute (Benoit Donnetet. al.)
Unveiling the MPLS Structure on Internet Topology (GabrielDavila Revelo et. al.)
Through the Wormhole: Tracking Invisible MPLSTunnels (Yves Vanaubel et. al.)
TNT, Watch me Explode: A Light in theDark for Revealing MPLS Tunnels (Yves Vanaubel et. al.)

PyCharm
2021-11-24 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
While Python offers a useful command-line interface, it isoften more productive to rely on an IDE (Integrated DevelopmentEnvironment) for larger projects. In this session, we will present PyCharmCommunity Edition, a free and popular Python IDE. We will review its mainfeatures, including:

Project management,
Code completion,
Refactoring,
Debugging,
Keyboard shortcuts.

Prerequisite: yourcomputer with a working Python installation.

Slides

Progresssheet

Dynamic Secure-Emulation
2021-11-17 15:00 - 16:00 | LINCS + Zoom, 23 avenue d'Italie, Paris, 75013, France
We present probabilistic dynamic I/O automata, a framework tomodel dynamic probabilistic systems. Our work extends dynamic I/O Automataformalism from Attie & Lynch to probabilistic setting. Theoriginal dynamic I/O Automata formalism included operators for parallelcomposition, action hiding, action renaming, automaton creation, andbehavioral sub-typing by means of trace inclusion. They can modelmobility by using signature modification. They are also hierarchical: adynamically changing system of interacting automata is itself modeled as asingle automaton.
Our work extends to probabilistic settings all thesefeatures. Furthermore, we prove sufficient (weak) conditions toobtain the implementation monotonicity with respect to automata creationand destruction. Secondly, we extends composable secure-emulation from Canetti & al. to dynamic settings, an important tooltowards the formal verification of protocols combining probabilisticdistributed systems and cryptography in dynamic settings (e.g.blockchains, secure distributed computation, cybersecure distributedprotocols etc). Here again, we prove sufficient (weak) conditions toobtain the secure-emulation monotonicity with respect to automata creationand destruction.

Chaos Engineering
2021-11-17 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
"Chaos Engineering is the discipline of experimenting on adistributed system in order to build confidence in the system's capabilityto withstand turbulent conditions in production." (Principles ofChaos)

In this reading group's session we will discover what ChaosEngineering is and how it is used in systems in production through the book"Chaos Engineering" written by Rosenthal et al. from Netflix. We willexplain the context of distributed system resiliency, the principles ofChaos Engineering and the application of Chaos inpractice.

Reference:
Casey Rosenthal, Lorin Hochstein, AaronBlohowiak, Nora Jones, Ali Basiri, Chaos Engineering, O'Reilly Media,Inc., August 2017,http://www.oreilly.com/webops-perf/free/chaos-engineering.csp.

Presentation materials:

PDF of the presentation: link to the slides.

HLOC: Hints-based geolocation leveraging multiple measurementframeworks
2021-11-10 10:45 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Dear all, The Internet Measurement reading group will meet onWednesday 10th.

In this session, Maxime Mouchet (Sorbonne Université,LIP6) will present HLOC: Hints-based geolocation leveraging multiplemeasurement frameworks (Quirin Scheitle et al., TMA 2017).

Iencourage you to join us at 10:45 for a virtual coffee break, so thatthe talk beginsat 11:00.
https://telecom-paris.zoom.us/j/98157419805?pwd=[REDACTED]

Slides

Abstract
Geographically locating an IPaddress is of interest for many purposes. There are two major ways toobtain the location of an IP address: querying commercial databases orconducting latency measurements. For structural Internet nodes, such asrouters, commercial databases are limited by low accuracy, while currentmeasurement-based approaches overwhelm users with setup overhead andscalability issues. In this work we present our system HLOC, aiming tocombine the ease of database use with the accuracy of latency measurements.We evaluate HLOC on a comprehensive router data set of 1.4M IPv4 and 183kIPv6 routers. HLOC first extracts location hints from rDNS names, and thenconducts multi-tier latency measurements. Configuration complexity isminimized by using publicly available large-scale measurement frameworkssuch as RIPE Atlas. Using this measurement, we can confirm or disprove thelocation hints found in domain names. We publicly release HLOC'sready-to-use source code, enabling researchers to easily increasegeolocation accuracy with minimum overhead.

PhD thesis defense "Stochastic matching models and theirapplications to demand-supply balancing"
2021-11-09 10:00 - 13:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
The recent growth of the collaborative economy withpeer-to-peer networks created the need for interfaces that put in relationdifferent types of populations. Applications such as ride sharing, houserenting, job search, dating websites and so on, link people togetherbased on various preferences or compatibilities. This motivates thedevelopment of new algorithms that optimize those associations, alsocalled matchings. Matching models have been studied at great length in theliterature when parts of the population is static. However, when customersarrive randomly over time, the problem is much more challenging and manyquestions remain open. This thesis tackles the matter through the lens ofcontrol in stochastic matching models.
These models are formalized asfollows. Items of different classes arrive to the system according to agiven probability distribution. Upon arrival, each item is matched withanother compatible item according to a matching policy and both items leavethe system immediately. If there are no compatible items, the new arrivalsjoin the queues of unmatched items of the same class. Compatibilitiesbetween item classes are defined by a connected graph, where nodesrepresent the classes of items and the edges the compatibilities betweenitem classes. Unmatched items induce a holding cost at each time step andwe model this problem as a Markov Decision Process.
In particular, westudy the Bipartite Matching Model which considers bipartite compatibilitygraphs and arrivals by pair. We are interested in finding the optimalcontrol for the discounted and average cost problems. For the N-shapedcompatibility graph, we fully characterize the optimal matching policy. Wealso identify optimal matchings for more general bipartite graphs underadditional assumptions on the costs.
We also analyze the performance ofthe General Matching Model, where new items arrive one by one with anon-bipartite compatibility graph, under the First Come First Matchedpolicy. We show that such a model may exhibit a non intuitive behavior:increasing the matching flexibility by adding new edges in thecompatibility graph may lead, when the system is close to the stabilitycondition, to a larger average population at the steady state.
Finally,we use Reinforcement Learning to find the optimal threshold-type policy forBipartite Matching models. We develop an Actor-Critic algorithm composed ofa Temporal Difference critic and a Policy Gradient actor that includes thisthreshold type structure and learns the optimal threshold within this setof policies.

Keywords: Stochastic matching models, Markovdecision processes, Optimal control, Braess paradox, Reinforcementlearning

Here the link toattend: https://global.gotomeeting.com/join/212030933

Developing With Style: The Pythonic Way
2021-11-03 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Beautiful is better than ugly…

In this session we will usemodern coding-style to improve the readability, the performance and thecorrectness of Python code. We will also see from interactive examples somepitfalls that beginners (and less beginners) often fall and how to avoidthem.

Prerequisite: your computer with a working Pythoninstallation.

Joint Channel Coding of Consecutive Messages with HeterogeneousDecoding Deadlines in the Finite Blocklength Regime
2021-10-27 15:00 - 16:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
One of the pillars of 5G is ultra-reliable low latencycommunications (URLLC), where the goal is to transmit typically smallquantities of data with a very low probability of error and strict decodingdeadlines. With applications ranging from autonomous driving to remotesurgery, a number of channel coding schemes have been proposed includingshort LDPC and polar codes. A standard assumption in the design ofultra-reliable low-latency communication systems is that the durationbetween message arrivals is larger than the number of channel uses beforethe decoding deadline. Nevertheless, this assumption fails when messagesrapidly arrive and reliability constraints require that the number ofchannel uses exceeds the time between arrivals. In this talk, we studychannel coding in this setting by jointly encoding messages as they arrivewhile decoding the messages separately, allowing for heterogeneousdecoding deadlines.

Stability Conditions for a Discrete-Time Decentralised MediumAccess Algorithm
2021-10-27 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
We will present the paper: Shneer, S., & Stolyar, A.(2018). Stability conditions for a discrete-time decentralised mediumaccess algorithm. The Annals of Applied Probability, 28(6),3600-3628.

We consider a stochastic queueing system modelling thebehaviour of a wireless network with nodes employing a discrete-timeversion of the standard decentralised medium access algorithm. The systemis unsaturated – each node receives an exogenous flow of packets at therate ? packets per time slot. Each packet takes one slot to transmit, butneighbouring nodes cannot transmit simultaneously. The algorithm we studyis standard in that: a node with empty queue does not compete for mediumaccess; the access procedure by a node does not depend on its queuelength, as long as it is non-zero. Two system topologies are considered,with nodes arranged in a circle and in a line. We prove that, for eithertopology, the system is stochastically stable under condition λ< 2/5. This result is intuitive for the circle topology as thethroughput each node receives in a saturated system (with infinite queues)is equal to the so-called parking constant, which is larger than 2/5.(This fact, however, does not help to prove our result.) The result isnot intuitive at all for the line topology as in a saturated system somenodes receive a throughput lower than 2/5.

Slides

"Big Thought Time Talk" by Nokia: “Fast Distributed Optimizationwith Asynchrony and Time Delays”
2021-10-21 17:00 - 18:00 | LINCS + Teams, 23 avenue d'Italie, Paris, France
The training of models over distributed data calls fordistributed optimization schemes. This has motivated research ondistributed convex optimization, leading to the identification of lowerbounds on convergence speed, and distributed optimization algorithms withconvergence speed potentially matching these lower bounds, for a varietyof settings.

In this talk we focus on the important setting ofasynchronous operation, for which we propose optimization algorithms withoptimal speed. We next consider systems with heterogeneous communicationand computation delays, for which we propose fast asynchronous algorithmsadapted to these heterogeneous delays.

Bio:
Laurent Massoulié isresearch director at Inria, head of the Microsoft Research – Inria JointCentre, and professor at the Applied Maths Centre of Ecole Polytechnique.His research interests are in machine learning, probabilistic modellingand algorithms for networks. He has held research scientist positions at:France Telecom, Microsoft Research, Thomson-Technicolor, where he headedthe Paris Research Lab. He obtained best paper awards at IEEE INFOCOM1999, ACM SIGMETRICS 2005, ACM CoNEXT 2007, NeurIPS 2018, was elected"Technicolor Fellow" in 2011, received the "Grand PrixScientifique" of the Del Duca Foundation delivered by the French Academy ofScience in 2017, and is a Fellow of the LINCS Laboratory.

LINCShosted this talk in its premises at 23 avenued'Italie.

**The talk was organised by Nokia in theframework of its "Big Thought Time Talk" series. All institutionalparteners of the LINCS, including Nokia and Inria, have indeedlong-standing partnership in solving future network challenges as well asthe role of machines in automating and augmenting human existence.

On Velocity-based Association Policies for Multi-tier 5G WirelessNetworks
2021-10-20 14:00 - 15:00 | LINCS + Zoom, 23 avenue d'Italie, Paris, 75013, France
Mobility is a key challenge for beam management in 5G cellularnetworks due to the overhead incurred at beam switching and base station(BS) handover events. This paper focuses on a network that has a multi-tierstructure with two types of BSs operating in the same frequency bands,namely macro BSs that are sparser but with higher transmit power, andmicro BSs that are denser and with lower transmit power. We propose adownlink user association policy which is a function of the user mobility.Typically, high mobility users should associate with macro BSs so as toincur less beam switching overhead, whereas low mobility ones should beassociated with micro BSs. The main contribution of the paper is aformalization of the optimal threshold association policy, when theoptimality is understood with respect to the effective Shannon rate. Theanalysis is based on stochastic geometry and on an exact representation ofthe effective Shannon rate of the typical user in this beamformingmulti-tier context. Two models are discussed. The simplest one focuses on asingle-user optimization problem. We also discuss a more realistic modelwith bandwidth sharing between all users in the cell. Finally, we identifythe mobility and user-density patterns where the velocity-based thresholdassociation policy outperforms the classical best mean power associationpolicy. In a last part, we will explore on a generalization of suchpolicies by adding a velocity-biased threshold for the two tiers in thenetwork and discuss preliminary results for this optimizationproblem.

** This talk is based on a paper accepted at Globecom2021.
Here the SLIDES of this talk

PCAP tools for practical traffic monitoring in LAN
2021-10-20 10:45 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Pcap (Packet CAPture) is an API for network monitoring innetwork, essentially in LANs (Ethernet, WiFi). It is mainly use forpassive monitoring (packet capture) but it can also be used for activemonitoring (packet injection). There are implementations for Linux(libpcap), Apple (libpcap) and Windows (WinPcap, Npcap and Win10Pcap)systems. Pcap is used by tcpdump, tshark and Wireshark software, but youcan make your own software using it. In this session of InternetMeasurement Reading Group, we will present how it works, how it can beused with Node.js (cap and pcap modules) and Python (Scapy), with someapplication uses cases. For the applications use cases, we will explainhow we used Pcap for IoT device type identification and how we are usingPcap in our current IoT Network Monitoring project.

References

Pcap:
https://www.tcpdump.org/
pcap fileformat:https://wiki.wireshark.org/Development/LibpcapFileFormat

Node.jsmodules:
- node_pcap (pcap): https://www.npmjs.com/package/pcap
- cap:https://www.npmjs.com/package/cap

Python module:
- scapy:https://scapy.readthedocs.io/en/latest/

Application example:
NesrineAmmar, Ludovic Noirie, Sébastien Tixeuil, "Autonomous IoT DeviceIdentification Prototype," best demo paper at Network Traffic Measurementand Analysis Conference 2019, Jun 2019,Paris
https://dx.doi.org/10.23919/TMA.2019.8784517

Presentationmaterials: Jupyter notebook used during the presentation

Zipped folderwith Jupyter notebook and attached files: link to archive.
HTML version ofthe Jupyter notebook: link to the html version of the notebook.

Discv5 - service discovery for the Ethereum P2P network
2021-10-13 14:00 - 15:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
Ethereum is one of the largest permissionless,open-source
blockchains supporting Turing-complete scripting via smartcontracts.
Ethereum runs a Peer-to-Peer (P2P) network based onKademlia
Distributed Hash Table (DHT) to exchange pendingtransactions and
mined blocks. Apart from supporting blockchain dataexchange, the
Ethereum P2P network is used by other applications. Thisincludes
multiple Ethereum testnets (Rinkeby, Ropsten),decentralized
application (iExec, Swarm, Whisper) or alternativecryptocurrencies
(Pirl, Musicoin). In this talk, we present Discv5 - anew service
discovery protocol designed with the Ethereum foundationallowing
application-specific peers to find each other in anopen,
permissionless setup.

Bio: Michal Król is a lecturer in CyberSecurity at City, University of
London. He did his PhD at the UniversityGrenoble Alpes in France and
spent several years as a research associateat University College
London, University of California, Los Angeles andUCLouvain in Belgium.
His research research interest include blockchains,distributed systems
and privacy-preserving communication.

Python 101
2021-10-13 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
We will see how to install a complete Python environment:

Python distribution (Anaconda),
Python IDEs (Jupyter Notebook /JupyterLab / PyCharm).

We will go through the installation process,make our first "Hello World", and introduce various useful features, likeNB extensions, PyCharm projects, or keyboard shortcuts.

This openingtutorial is intended for people with no or low experience of Python thatwant to dive in.

Prerequisite: your computer.

Recommendation: to savetime and bandwidth, you may want to download the following in advance:

Anaconda distribution, from https://www.anaconda.com/products/individual(3.8 version for your system; this should be the default proposal).
Pycharm community edition, fromhttps://www.jetbrains.com/pycharm/download.

Random Line and Hyperplane Processes
2021-10-06 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
We will talk about:

Stationarity
The Poisson case.
Associated random measures.
Associated tessellations.
The Croftoncell.
Mass transport.
Applications.

Reference: Random Measures,Point Processes, and Stochastic Geometry.
François Baccelli,Bartłomiej Błaszczyszyn and Mohamed Karray, 2020 preprint.https://hal.inria.fr/hal-02460214.

PhD thesis defense "Longitudinal, large scale and unbiasedInternet Measurements"
2021-09-21 14:00 - 17:00 | Zoom + Amphi 4 chez Télécom-Paris, 19 Place Marguerite Perey,Palaiseau, 91120, France
Today, a world without the Internet is unimaginable. Byinterconnecting billions of people worldwide and by offering an uncountablenumber of services, it is now fully embedded in the modern society. Yet,despite technology evolution and development, its pervasiveness andheterogeneity still raise new challenges, such as security concerns,monitoring of the users' Quality of Experience (QoE), care fortransparency and fairness. Accordingly, the goal of this thesis is to shednew light on some of the challenges emerged in recent years. Inparticular, we provide an in-depth analysis of some of the most prominentaspects of modern Internet. A particular emphasis is given on the WorldWide Web, which among all, is undoubtedly one of the most popularInternet applications, and a specific regard to its interaction withmachine learning. The first part of this work studies the Quality ofExperience of users' browsing the Web, with measurements led both in thewild and in controlled environments. Our contributions follow with anoriginal analysis of both the subjective user feedback and the objectiveQoE metrics, showing how hard it is to build accurate superviseddata-driven models capable to predict the user satisfaction, along with anin-depth discussion of the multi-modal nature of the subjective useropinions.In the second part of this work, we analyze and discuss thefairness of state-of-the-art transformer-based language models, which arepre-trained on Web-based corpora and which are typically used to solve awide variety of Natural Language Processing (NLP) tasks. Here, we questionwhether the sheer size and heterogeneity of the Web guarantee diversity inthe models. The core of our contributions rests in the measure of the biasembedded in the models, that we discuss under different angles. Finally,the last part of this dissertation addresses the classification of objectsgenerated by machines through some of the simplest state-of-the-artsupervised machine learning algorithms. Through a minimally intrusive,robust and lightweight framework, we show that the different behaviors ofa field of the IP packet, the IP identification (IP-ID), could be easilyclassified with few features having high discriminative power. We finallyapply our technique to an Internet-wide census and provide an updated viewof the adoption of the different implementations in theInternet.

Jury composition:
Isabelle CHRISMENT, Professor,LORIA Campus Scientifique (President, Reviewer)
Pedro CASAS, SeniorScientist, AIT Austrian Institute Of Technology (Reviewer)
ChadiBARAKAT, Senior Researcher, INRIA (Examinator)
Tobias HOßFELD,Professor, University of Würzburg(Examinator)
Marco MELLIA, Professor,Politecnico di Torino (Examinator)
Philippe OWEZARSKI, Director ofResearch, LAAS-CNRS (Examinator)

Mauro SOZIO, Professeur,Télécom Paris (PhD Supervisor)
Dario ROSSI, Chief Expert, HuaweiTechnologies France (PhD Co-Supervisor)

To watch thedefense:
https://telecom-paris.zoom.us/j/94526858841?pwd=[REDACTED]

ID de réunion : 945 26858841
Code secret : [REDACTED]

Higher-Order Spectral Clustering for Geometric Graphs
2021-09-15 14:00 - 15:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
This work is devoted to clustering geometric graphs. It appearsthat the standard spectral clustering is often not effective for geometricgraphs. We present an effective generalization, which we call higher-orderspectral clustering. It resembles in concept the classical spectralclustering method but uses for partitioning the eigenvector associated witha higher-order eigenvalue. We establish the weak consistency of thisalgorithm for a wide class of geometric graphs which we call Soft GeometricBlock Model. A small adjustment of the algorithm provides strongconsistency. We also show that our method is effective in numericalexperiments even for graphs of modest size.

This is a joint workwith A. Bobu and M. Dreveton, done in the framework of Inria - Nokia BellLabs and recently appeared in JFAA, 27:22,2021.
https://link.springer.com/article/10.1007/s00041-021-09825-2

**Here the link to the presentation's slides: HOSC_LINCSPresent

PhD thesis defense "Alarm prediction in networks via space-timepattern matching and machine learning"
2021-07-08 14:00 - 17:00 | LINCS + Zoom, 23 avenue d'Italie, Paris, 75013, France
Nowadays, telecommunication networks occupy a predominantplace in our world. Indeed, they allow to share worldwide a huge amount ofinformation. Networks are however complex systems, both in size andtechnological diversity. Therefore, it makes their management and repairmore difficult. In order to limit the negative impact of such failures,some tools have to be developed to detect a failure whenever as soons as itoccurs, analyse its root causes to solve it efficiently, or even predictthis failure to prevent it rather than cure it. In this thesis, wemainly focus on these last two problems. To do so, we use files, calledalarm logs, storing all the alarms issued by the system. However, thesefiles are generally noisy and verbose: an operator managing a network needstools able to extract and handle in an interpretable manner the causalrelationships within a log. First, we build online a structure, calledDIG-DAG, that stores all the potential causal relationships involving theevents of a log. We then propose a query system to exploit this structure.Finally, we apply this approach in the context of root causeanalysis. Second, we discuss a generative approach for times seriesprediction. In particular, we compare two well-known models for this task:recurrent neural nets on the one hand, hidden Markov models on the otherhand. Indeed, in their respective communities, these two models are stateof the art. Here, we compare analytically their expressivity byencompassing them into a probabilistic model, called GUM.

"Maliciously secure consensus from succinct arguments, and shorttransparent threshold signatures"
2021-07-07 14:00 - 15:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
We consider consensus protocols, for application to statemachine replication, in the model of Castro-Liskov-Dolev-Lynch-Stockmeyer(partial synchrony, black box leader election, malicious corruptions).These protocols enable n players to output the same value, such that theoutput satisfies some publicly verifiable validity condition.

Effortssince "PBFT" (Castro-Liskov '99), aim at reducing the communicationcomplexity. A breakthrough was achieved by Hotstuff (Podc'19), implementedin Facebook's Diem. It has complexity quasi linear in n the number ofplayers, but at the price of extra latency.

We show how to overcomethis limitation. First, with an explicit elementary construction in O(nlog(n)), with a small constant overhead. Then, from the use of succinctnoninteractive arguments of knowledge.

If time allows, we will explainthe simplest: an argument of knowledge of k BLS signatures on thesame message m, out of n public keys. This provides the first thresholdsignature with logarithmic size without trustedsetup.

Experience in research and deployment of AI-based techniques for“networks”
2021-06-30 14:00 - 15:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
In the talk we will first present Telefonica Research, ateam of researchers in Machine Learning/Deep Learning, HumanComputer Interaction, Security/Privacy and Networks/Systems and highlightpotential collaboration opportunities. The aim of the team is to carryresearch studies on mid to long-term related to several technological areasof interest to the Telefónica Group following an open research model andgenerating impact through technology transfers. We will then focus onone of the key area we are working on that is Artificial Intelligenceapplied to “networks”. Indeed, Artificial Intelligence (AI) isrecognized as a main driver for future telco industry business and digitaltransformation. It will lead towards increasingly autonomous andintelligent networks, will improve customer experience, and generatesignificant economic impact.
However, despite this relevance and twodecades of research in applying AI techniques to networks, there is stilla limited applicability of AI technologies to actual productionenvironments.
In this talk we will present our experience in research anddeployment of AI-based techniques in a large technology company. We willoverview several use cases including fixed and mobile networks,platforms, network access, end user devices where we have developed novelmachine learning and deep learning algorithms. We then zoom into two usecases where AI can bring significant benefits, namely advanced networkoperations in rural areas mobile network deployments and in aninternational roaming platform. Finally, we will discuss lessons learnedduring this process and the relevant research and innovationdirections.

Bio
Diego Perino is the Directorof Telefonica Research and lead a team of researchers inMachine Learning/Deep Learning, HCI, Privacy/Security, Networks andSystems. He also recently led ARIANA, a Telefonica Innovation startupproject leveraging Artificial Intelligence for Automatic NetworkActions. Previously he worked at Bell Labs (Paris, France)from September 2009 to June 2016 and six months at NICTA (Sydney,Australia) in 2016 as visiting researcher. He received his Ph.D. inComputer Science from the Paris Diderot-Paris 7 university in 2009: thethesis was a collaboration between Orange Labs and INRIA through a CIFREcontract.

Algorithms for generating random permutations
2021-06-30 11:00 - 12:00
Systems such as masscan, yarrp and diamond-miner send in theorder of a million packets/s in order to discover open ports and packetpaths on the Internet. To avoid overloading the network and triggerrate-limiting or intrusion detection systems, the probes must bedistributed evenly across the network. Standard methods for generatingrandom permutations, such as the Fisher-Yates shuffle, usually require tostore the whole permutation in memory, which is prohibitive when thenumber of probes to send is large (>1B typically). In this talk we willdiscuss methods to generate random permutations, and in particular theGeneralized-Feistel Cipher [1] which can generate permutations on arbitrarydomains, on-the-fly and in constant memory.

[1] Black, John, andPhillip Rogaway. “Ciphers with arbitrary finite domains.”/Cryptographers’ track at the RSA conference/. Springer, Berlin,Heidelberg, 2002.

Reverse Traceroute
2021-06-23 13:45 - 15:00
Dear all, The Internet Measurement reading group will meetagain on June 23rd.
We will exceptionally meet at 13:45 instead of ourregular time of 10:45. In this session Kevin Vermeulen (ColumbiaUniversity) will present « Reverse Traceroute » (E. Katz-Bassett etal., NSDI 2010).
I encourage you to join us at 13:45 for a virtualcoffee break, so that the talk begins at 14:00.

Abstract
Tracerouteis the most widely used Internet diagnostic tool today. Network operatorsuse it to help identify routing failures, poor performance, and routermisconfigurations. Researchers use it to map the Internet, predictperformance, geolocate routers, and classify the performance of ISPs.However, traceroute has a fundamental limitation that affects all theseapplications: it does not provide reverse path information. Althoughvarious public traceroute servers across the Internet provide somevisibility, no general method exists for determining a re- verse path froman arbitrary destination.
In this paper, we address this longstandinglimitation by building a reverse traceroute system. Our system provides thesame information as traceroute, but for the reverse path, and it works inthe same case as traceroute, when the user may lack control of thedestination. We use a variety of measurement techniques to incrementallypiece together the path from the destination back to thesource.

Speaker

Kevin is currently a postdoc at ColumbiaUniversity working with Professsor Ethan Katz-Bassett. His research focuseson building networked systems for a better understanding of theInternet.

Best,
Maxime

—Participer à la réunionZoomhttps://telecom-paris.zoom.us/j/97120167222?pwd=[REDACTED]
ID de réunion : 971 2016 7222Code secret : 895458

Edge Classification: Offloading under Token Bucket Constraints
2021-06-22 16:35 - 17:20 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
We consider an edge-computing setting where machinelearning-based algorithms are used for real-time classification of inputsacquired by devices, e.g., cameras. Computational resources on thedevices are constrained, and therefore only capable of running machinelearning models of limited accuracy. A subset of inputs can be offloaded tothe edge for processing by a more accurate but resource-intensive machinelearning model. Both models process inputs with low-latency, butoffloading incurs additional network and compute delays. To manage thesedelays and meet application deadlines, a token bucket constrainstransmissions from the device. We first introduce a Markov DecisionProcess-based framework to make offload decisions under such constraintswhen the input process is i.i.d. Decisions are based on the local model'sconfidence and the token bucket state, with the goal of minimizing aspecified error measure for the application. We then extend the approach toconfigurations involving multiple devices connected to the same accessswitch to realize the benefits of a shared token bucket. Next we explore anapproach based on deep Q-networks (DQN) to handle more complex input andclassification processes, and demonstrate its ability to learn suchfeatures and effectively incorporate them into policy decisions. Weevaluate and analyze the policies derived using our framework on thestandard ImageNet image classification benchmark. 1, 2

This is jointwork with Ayan Chakrabarti, Chenyang Lu, Jiaming Qiu, Ruiqi Wang, andJiangnan Liu
Part of this work will be presented at the 2021 ACM/IEEESECconference

https://telecom-paris.zoom.us/j/97120167222?pwd=[REDACTED]
- ID de réunion : 971 2016 7222- Code secret: [REDACTED]

Enabling intelligent services via function virtualization at thenetwork edge
2021-06-22 15:40 - 16:25 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
The proliferation of novel mobile applications and theassociated AI services necessitates a fresh view on the architecture,algorithms and services at the network edge in order to meet stringentperformance requirements. Some recent work addressing these challenges ispresented. In order to meet the requirement for low-latency, the executionof computing tasks moves form the cloud to the network edge, closer to theend-users. The joint optimization of service placement and request routingin dense mobile edge computing networks is considered. Multidimensionalconstraints are introduced to capture the storage requirements of the vastamounts of data needed. An algorithm that achieves close-to-optimalperformance using a randomized rounding technique is presented. Recentadvances in network virtualization and programmability enable realizationof services as chains, where flows can be steered through a pre-definedsequence of functions deployed at different network locations. The optimaldeployment of such service chains where storage is a stringent constraintin addition to computation and bandwidth is considered and an approximationalgorithm with provable performance guarantees is proposed and evaluated.Finally the problem of traffic flow classification as it arises infirewalls and intrusion detection applications is presented. An approachfor realizing such functions based on a novel two-stage deep learningmethod for attack detection is presented. Leveraging the high level of dataplane programmability in modern network hardware, the realization of thesemechanisms at the network edge isdemonstrated.

https://telecom-paris.zoom.us/j/97120167222?pwd=[REDACTED]
- ID de réunion : 971 2016 7222-Code secret : [REDACTED]

Machine Learning for Network Management
2021-06-22 14:25 - 15:10 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
Machine Learning has been applied to a wide range of networkingtopics. Network management provides ample examples, often of the type ofcombinatorial optimizations. In the talk, we look at two examples. Oneexample comes from the context of network softwarization, where weinvestigate how machine learning approaches can help with scaling andplacing virtual network functions, as well as routing traffic betweenthem. The second example comes from wireless sensor networks with acousticapplications in mind, where we need to balance acoustic sensing qualitywith wireless network quality and use these two metrics to move mobilemicrophones into goodlocations.

https://telecom-paris.zoom.us/j/97120167222?pwd=[REDACTED]
- ID de réunion : 971 2016 7222- Code secret: [REDACTED]

Internet of Things @ LINCS
2021-06-22 13:45 - 14:15 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
In this presentation, we will present the main researchactivities of LINCS concerning the Internet of Things (IoT) in recentyears: the management of IoT devices in home/enterprisenetworks, Wireless Body Area Networks technologies, remote connectivityfor Bluetooth, data aggregation in IoT networks, networks ofrobots.

https://telecom-paris.zoom.us/j/94880732137?pwd=[REDACTED]

– ID de réunion : 948 80732137
– Code secret : [REDACTED]

LINCS supervised members elevator pitches + poster session (day 2)
2021-06-22 10:45 - 12:15 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
Michel Davydov (PhD - Inria)
Poisson hypothesis for replica-mean-fieldnetworks
Phenomena as diverse as neural computations, opinion dynamics orflow control on the internet can be modeled as punctuate interactionsbetween agents in a network. Unfortunately, most relevant dynamics involvecomplex graphs of interactions for which an exact computational treatmentis impossible. To circumvent this difficulty, the replica-mean-fieldapproach focuses on randomly interacting replicas of the networks ofinterest. In contrast with classical mean-fields, interaction couplings donot scale with the number of neurons and preserve both the geometry of thenetwork and the finite-size correlations. In the limit of an infinitenumber of replicas, these networks become analytically tractable under theso-called Poisson Hypothesis, which postulates that replicas becomeasymptotically independent and arrivals to a given neuron become Poissondistributed. This hypothesis is often conjectured or numerically validatedbut not proven. We show the validity of the Poisson Hypothesis for largeclasses of processes in both discrete and continuous time.
Bharath RoyChoudhury (PhD - Inria)
Local limits of vertex-shifts on random rootednetworks
While navigating on a network, it is desirable to follow a rulethat does not require knowledge of the whole network and yet can guidetowards the target. In this study, we consider deterministic navigationrules that depend only on the local neighbourhoods of the origin ( alsocalled the root). These rules are examples of vertex-shifts, a collectionof maps defined on vertices of network that respect the network structure.The underlined network on which a vertex-shift is defined could be random.We choose a class of random graphs with high spatial homogeneity calledunimodular graphs and study the asymptotic behaviour of vertex-shifts onthem. We show that under some conditions on the vertex-shifts, thelimiting behaviour can be expressed in relation to the distribution of theunderlined unimodular random graph.

Victor Vermes (intern -inria)
Dynamic matching on hypergraphs
Matching systems systems have awide range of applications, to collaborative economy (matchingpeople in car sharing systems) or healthcare systems (matching organ donorsand organ recipient). I study the extension of such systems tohypergraphical structures (rather than grpahical), where more than twoitems can get matched together. At each time step, a single item arrivesaccording to a fixed probability distribution, and compatible items can bematched according to a matching policy. I compare different matchingpolicies (such as "First in, First out" or "Match the longest"), andstudy the stability of such policies.

Razanne Abu-Aisheh (PhD -inria+NBLF)
Atlas: Exploration and Mapping with aSparce Swarm of Networked Robots
Exploration and mapping of unknownenvironments is an essential application of swarm robotics, especially incritical missions such as hazard detection, search and rescue andsurveillance. These missions share the need to reach full coverage of theexplorable space and build a complete map of the environmentrapidly.

Existing exploration and mapping algorithms tend to either beinefficient, or rely on having a dense swarm of robots. Hence, wedeveloped Atlas, an exploration and mapping algorithm for sparse swarms ofrobots, which completes a full exploration within set time limits even inthe extreme case of a single robot. We also studied how communicationimpacts swarm exploration tasks and designed and implemented acommunication protocol that enables efficient, reliable and packet losstolerant exploration and mapping in various network conditions. Wedeveloped our own simulator to experiment on and test our algorithms andprotocols with. In future works we will be adding furtherinaccuracies to Atlas to utilize the understanding of these inaccuracies toincrease the efficiency of the algorithm.

Sayeh Khaniha (phd -inria)
Perfect sampling of the null recurrent Markov Chain in theDoeblin graph
Any irreducible, aperiodic, and positive recurrent MarkovChain has a unique stationary distribution. One classical problem relatedto this MC is to produce a perfect sample from its stationary distribution.There is a known algorithm coupling from the past (CFTP), introduced byPropp and Wilson for perfect sampling when the MC is aperiodic,irreducible and the state space is finite. This algorithm is based on arandom graph called Doeblin graph. When the MC is null recurrent, it doesnot have stationary distribution. So we can not speak about perfectsampling in the classical sense. In the null recurrent MC, we have astationary measure instead. We introduce a random set as a perfect sampleof stationary measure, in this case, using the Doeblin graph and itsproperties. And study the constructability of this perfect sample in somecases.

Flavia Salutari (Phd - tp)
Longitudinal, large-scaleand unbiased Internet measurements
Today, a world without theInternet is unimaginable. By interconnecting billions of people worldwideand by offering an uncountable number of services, it is now fullyembedded in the modern society. Yet, despite technology evolution anddevelopment, its pervasiveness and heterogeneity still raise newchallenges, such as security concerns, monitoring of the users’ Qualityof Experience (QoE), care for transparency and fairness.

Accordingly,the goal of this work is to shed new light on some of the challengesemerged in recent years. In particular, we provide an in-depth analysis ofsome of the most prominent aspects of modern Internet. A particularemphasis is given on the World Wide Web, which among all, is undoubtedlyone of the most popular Internet applications, and a specific regard toits interaction with machine learning.

First, we study theQuality of Experience of users’ browsing the Web, with measurements ledboth in the wild and in controlled environments. Then, we analyze anddiscuss the fairness of state-of-the-art transformer-based languagemodels, which are pre-trained on Web-based corpora and which are typicallyused to solve a wide variety of Natural Language Processing (NLP) tasks.Here, we question whether the sheer size and heterogeneity of the Webguarantee diversity in the models. Finally, we address the classificationof objects generated by machines through some of the simpleststate-of-the-art supervised machine learningalgorithms.

Gabriele Castellano (postdoc - inria)
Towards Inference Delivery Networks:Distributing Inference Tasks with Optimality Guarantees
Thisresearch introduces the idea of inference delivery networks (IDN),networks of computing nodes that coordinate to satisfy inference requestsachieving the best trade-off between latency and accuracy. IDNs bridge thedichotomy between device and cloud execution by integrating inferencedelivery at the various tiers of the infrastructure continuum (access,edge, regional data center, cloud).
We propose a distributed dynamicpolicy for ML model allocation in an IDN by which each node periodicallyupdates its local set of inference models based on requests observed duringthe recent past plus limited information exchange with its neighbor nodes.Our policy offers strong performance guarantees in an adversarial settingand shows improvements over greedy heuristics with similar complexityin realistic scenarios.

Ayoub Ben Ameur (phd -TSP)
Cache Allocation in Multi-Tenant Edge Computing via onlineReinforcement Learning
Edge Computing (EC) consists in deployingcomputational resources (CPU, memory, storage) into the edge of thenetwork (base stations, central offices, access points), thusconstituting a “cloud at the edge”. Most of the related work examinesthe performance of a single generic service running in the Edge. In ourvision, instead, EC is a multi-tenant environment: the resource owner,i.e., the Network Operator (NO), virtualizes the resources and let thirdparty Service Providers (SPs - tenants) run their services, which can bediverse and with heterogeneous requirements. The NO allocates the availablelimited resources to SPs, in order to satisfy their requirements and tooptimize a global utility function. Due to confidentiality guarantees, theNO cannot observe the traffic and the data of SPs, which are encrypted.This makes allocation decisions challenging, since they have to be takenjust based on observed monitoring information. In this work, weconcentrate on one specific resource, i.e., cache space, and we decidehow to partition it among several SPs in order to minimize the upstreamtraffic. Our goal is to optimize cache allocation using purely data-driven, model-free Reinforcement Learning (RL). Differentlyfrom most applications of RL, in which RL is trained offline insimulations, we apply it in an online fashion: we train RL while adaptingit to optimize the edge cache allocation, on a hot-and-running system. Wethus observe the improvement of RL decisions based on the feedback (onlinemeasurement of upstream traffic) determined by the user request flows. Starting from a simple Q-learning algorithm, we highlight theimpact of several learning techniques, e.g. ?-Stretched Exponential Decayand Experience Replay, in order to improve the performance of ouralgorithm.

Berat Senel (phd - sorbonne)
EdgeNet: A multi-tenant, multi-provider, globallydistributed Kubernetes cluster
EdgeNet (https://www.edge-net.org/) is adistributed Kubernetes cluster with nodes all across the world. Thiscluster is publicly available to researchers who wish to performexperiments in networking and distributed systems. Anyone can contribute anode to the cluster, from any machine on the Internet. EdgeNet’smulti-tenant and multi-provider design has been built around a set ofKubernetes operators that manage tenants, teams and users. Experimenterscan schedule workloads based on nodes’ geographical locations usingEdgeNet’s SelectiveDeployment custom resource. Those who wish tocontribute an EdgeNet node can do so within minutes via a single-linecopy-and-paste call to an Ansible script.

Ilia Shilov (phd -inria)
Algorithmic Game and Distributed Learning for Peer-to-Peer EnergyTrading
We propose different designs for the decentralized markets takinginto account the local-global market interactions andpropose mathematical approaches to analyze them. We focus on problems withcoupled constraints, thus we rely on the Generalized Nash Equilibrium andVariational Equilibrium concepts. We formulated risk neutral andrisk-averse models, further extending the former one to include therandomized reports to investigate strategic information sharing. Ourcurrent work focuses on network-aware peer-to-peer energy trading(inclusion of OPF, distribution grid constraints).

LéoLaugier (PhD - TP)
Civil Rephrases Of Toxic Texts With Self-SupervisedTransformers
Abstract : Platforms that support online commentary,from social networks to news sites, are increasingly leveraging machinelearning to assist their moderation efforts. But this process does nottypically provide feedback to the author that would help them contributeaccording to the community guidelines. This is prohibitively time-consumingfor human moderators to do, and computational approaches are stillnascent. This work focuses on models that can help suggest rephrasings oftoxic comments in a more civil manner. Inspired by recent progress inunpaired sequence-to-sequence tasks, a self-supervised learning model isintroduced, called CAE-T5. CAE-T5 employs a pre-trained text-to-texttransformer, which is fine tuned with a denoising and cyclic auto-encoderloss. Experimenting with the largest toxicity detection dataset to date(Civil Comments) our model generates sentences that are more fluent andbetter at preserving the initial content compared to earlier text styletransfer systems which we compare with using several scoring systems andhumanevaluation.

https://telecom-paris.zoom.us/j/94880732137?pwd=[REDACTED]

– ID de réunion : 948 8073 2137
–Code secret : [REDACTED]

LINCS members scientific highlights (day 2)
2021-06-22 09:15 - 10:15 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
Petr Kuznetsov (Télécom-Paris)
A sledgehammer to crack anut: why blockchain is not (always) a good idea
Abstract: In this shorttalk, we are going to discuss two, somewhat provocative, claims. First,cryptocurrency, the most popular application of the blockchain technologycan be implemented in a much simpler and efficient way. Second, thepermissionless setting with mutual distrust, assumed by conventionalblockchain implementations, is way too pessimistic in most cases. We thenshow how the two observations can help in designing efficient and robustreplicated services.

Fabien Mathieu (NBLF)
Once upon atime... in LINCS!
The notions of ``scientific community'' and ``researchfield'' are central elements for researchers and the articles they publish.We propose to explore the evolution of the LINCS community since itscreation, based on the articles listed in DBLP and the LINCS members,using the Gismo navigation engine and specially developed extensions. Ourresults allow to better understand the evolution of thecommunity.

Timur Friedman (Sorbonne)
Diamond-Miner:Comprehensive Discovery of the Internet's Topology Diamonds
Despite thewell-known existence of load-balanced forwarding paths in the Internet,current active topology Internet-wide mapping efforts are multipathagnostic — largely because of the probing volume and time required forexisting multipath discovery techniques. This paper introduces D-Miner, asystem that marries previous work on high-speed probing with multipathdiscovery to make Internet-wide topology mapping, inclusive ofload-balanced paths, feasible. We deploy D-Miner and collect multiple IPv4interface-level topology snapshots, where we find >64% more edges,and significantly more complex topologies relative to existing systems. Wefurther scrutinize topological changes between snapshots and attributeforwarding differences not to routing or policy changes, but to loadbalancer "remapping" events. We precisely categorize remapping events andfind that they are a much more frequent contributor of path changes thanpreviously recognized. By making D-Miner and our collected Internet-widetopologies publicly available, we hope to help facilitate betterunderstanding of the Internet's true structure andresilience.

Maxime Raynal (NBLF)
String alignment andclustering at the pattern level
Edit distances, such as the LongestCommon Subsequence (LCS) distance, or the Levenshtein distance, arewidely used to compare strings. Their use-cases include system logsclustering and automatic log parsing, fuzzy string search, as well as DNAsequences comparison and alignment. All the existing edit distances onstrings compare them at the character level; this does not allow tocompare the underlying structure of two strings, only the character whichcomposethem.

https://telecom-paris.zoom.us/j/94880732137?pwd=[REDACTED]

– ID de réunion : 948 8073 2137
– Codesecret : 705442

From artifacts to systems to people: evolving directions incomputing research and education
2021-06-21 17:05 - 17:50 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
Computing is now “old enough” as a discipline that we canalready detect broad trends in research directions. We discuss thesetrends, with an emphasis on both current and future directions incomputing research, which we see reflected locally (at my own university,UMass Amherst) nationally and internationally. We’ll discussrecent national computing research and education programmatics and trends,and the role of computing in the larger R&Denterprise.

https://telecom-paris.zoom.us/j/97120167222?pwd=[REDACTED]
- ID de réunion : 971 2016 7222- Codesecret : 895458

Security of Cyberphysical Systems
2021-06-21 16:10 - 16:55 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
The coming decades may see the large scale deployment ofnetworked cyber–physical systems to address global needs in areas such asenergy, water, health care, and transportation. However, as recentevents have shown, such systems are vulnerable to cyber attacks. Wepresent a general technique, called "dynamic watermarking," for detectingany sort of malicious activity in networked systems of sensors andactuators. We present results of tests on automobiles both in a labsetting, and on a test track, a lab process control system, a lab modelof a helicopter, a lab version of a solar-powered distribution system,and a simulation study of defense against an attack on the powersystem.

[Joint work with Bharadwaj Satchidanandan, Jaewon Kim, WooHyun Ko, Tong Huang, Lantian Shangguan, Kenny Chour, Gopal Kamath,Jorge Ramos, Le, Swaminathan Gopalswamy, Le Xie, and PrasadEnjeti].

https://telecom-paris.zoom.us/j/97120167222?pwd=[REDACTED]
- ID de réunion : 971 2016 7222- Code secret :[REDACTED]

Queuing Models of Radio Access Networks Offering Streaming andElastic Services
2021-06-21 15:15 - 16:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
We consider radio access networks (RANs) offering streaming andelastic services. The RAN is modeled with tools from queuing theory, andwe examine the cases in which the system performance can be derived withlow complexity. In addition, we provide numerical results for common cellconfigurations, showing that some of the emerging behaviors can beunexpected, and provide insight into the effective deployment of smallcells.

https://telecom-paris.zoom.us/j/97120167222?pwd=[REDACTED]
- ID de réunion : 971 2016 7222- Code secret :[REDACTED]

LINCS supervised members elevator pitches + poster session (day 1)
2021-06-21 13:15 - 14:45 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
Matthieu Gouel (PhD - Sorbonne)
Zeph &Iris Map the Internet - A resilient reinforcement learning approach todistributed IP route tracing
We describe a new state-of-the-art system fordistributed tracing at the IP level of the routes that packets take throughthe IPv4 internet. Our Zeph algorithm coordinates route tracing effortsacross agents at multiple vantage points, assigning to each agent anumber of /24 destination prefixes in proportion to its probing budget andchosen according to a reinforcement learning heuristic that aims tomaximize the number of multipath links discovered. Zeph runs on topof Iris, our fault tolerant system for orchestrating internet measurementsacross distributed agents of heterogeneous probing capacities. Iris isbuilt around third party free open source software and moderncontainerization technology, thereby presenting a new model for assemblinga resilient and maintainable internet measurement architecture. Zeph,deployed on 18 Iris agents, is capable of discovering in 10cycles of 1 day each 2.10M nodes and 13.98M edges, as compared to2.71M nodes and 6.34M edges over the same amount of time by the 110 agentsof a currently deployed reference measurement system,Archipelago.

Abhishek Kumar Mishra (PhD - Inria)
NemFi - Record-and-replay forWiFi
We present NemFi: a trace-driven WiFi emulator. NemFi isa record-and-replay tool that can capture traces representing real WiFiconditions, and later replay these traces to reproduce the sameconditions. We demonstrate that the state-of-the-art cellular emulatorcannot emulate WiFi conditions. We identify the key properties that need tobe addressed to enable accurate WiFi record-and-replay; namely: WiFipacket losses, medium-access control, and frame-aggregation. We thereforeextend and re-design the existing cellular network emulator to incorporatethese properties to support WiFi record-and-replay. We evaluate theperformance of NemFi against repeated experimentation acrossdifferent WiFi conditions and for three different types of applications:speed-test, file download, and video streaming. Our experimental resultsdemonstrate that NemFi achieves accurate record-and-replay aswe obtain 97 percent similar application performance using NemFiversus repeated experimentation in similar settings.

Anh Nguyen(PhD - TP)
Cellular Traffic Type Recognition and Prediction
4G and 5Gcellular traffic pattern recognition and prediction are key objectives fornetwork optimization. They also are becoming of fundamental importance forthe next-generation cellular network. Recognizing mobile traffic patternsand proactively knowing the user behaviors allow the operator to optimizethe resource allocation. On the other hand, it is a complex problem due tothe diverse set of applications behind the traffic. Most traffic predictionproblems focus on capturing the dynamic of traffic and enhancing theperformance. In this paper, we design a deep learning model for trafficpattern recognition and prediction of the type of arrival packet using LongShort-Term Memory (LSTM) neural networks. The mobile traffic information iscollected from the Downlink Control Information (DCI) using the Amarisoftsoftware. The learning phase of the model relies on a well-known trafficpattern simulated on Amarisoft 4G and 5G testbed.

PierrePopineau (PhD - Inria)
Stochastic geometry and wireless networks
Geometry plays a keycomponent in the study of wireless networks. In order to conduct bothstationary and dynamical analysis of wireless network, stochastic geometryhas proven to be a versatile tool that provides a framework to studycomplex, layered networks, following the latest norms in 5G communicationnorms

Yibo Quan (PhD - TP)
Spatio-Temporal Wireless D2D Network With Beamforming
We considera dynamic device-to-device (D2D) communication model where transmitters andreceivers adopt beamforming (BF). A continuous spatio-temporal model forthe wireless network is analyzed, which combines a spatial point processand a dynamic birth-death process .
We model BF by using a uniform lineararray (ULA) and derive an analytical stability condition of such a network.We show that the critical arrival rate increases with the number ofantennas at the transmitter and the receiver.

Deepa Jagyasi(engineer - TP)
A Moving User Beam-Predictor for mmWHeterogeneous Networks
This study demonstrates anefficient machine learning (ML)-aided moving user beam predictor formillimeter wave (mmW) base stations (BSs) while leveraging the sub-6GHz BSschannel information in a heterogeneous network setting. Heterogeneousnetwork architecture wherein multiple small-cell mmW BSs coexist withlegacy sub-6GHZ macro-cells is considered as a promising technique for thenext-generation cellular networks, since it benefits in achieving improvedreliability, enhanced coverage and huge unlicensed communication bandwidthwhile reducing overall infrastructural cost. However, identifying theoptimal mmW BS and best beam to serve the user equipment (UE) is atime-taking challenging task and introduces unacceptable latency.Furthermore, the dynamic movement of users and obstacles increases theoverall complexity of the problem. In this paper, we propose a novel deeprecurrent neural network (RNN)-based method for BS and beam predictionwhile accommodating user movement in the presence of multiple static anddynamic obstacles. To achieve this task, we propose a two-step process. Atfirst, we design a DNN which consider the basic components from theChannel State Information (CSI) of the sub-6GHz network along with the 3Dfeature map as input and predicts the best mmW BS and beam for the currenttime slot. Later the predicted results of the first step along with the 3Dfeature map are passed through the designed RNN to obtain the predictionsof best mmW BS and beam for next-slot on-wards to multiple futuretime-slots. The main contributions of the paper are; a) the proposedsystem is designed for a highly mobile user environment which accounts forthe static and dynamic blockages, b) prediction for the best BS and beamare obtained for the current time slot along with multiple time-slotsahead, c) we develop a static 3D feature map encapsulating the environmentinformation for better learning, and, d) the system is designed withoutany external sensor and user-location information as input feature. Theperformance of the method is evaluated over multiple metrics and iscompared with the conventional exhaustive search method. The proposedmethod demonstrates better performance than exhaustive search in terms oflatency with at least 85% accuracy.

Camila Fernandez (PhD- Sorbonne+NBLF)
Time-to-eventAnalysis
Time-to-event analysis is a branch of statistics that looks formodeling the time remaining until a certain critical event occurs. One ofthe main interests of time-to-event analysis is right censoring, it comesnaturally from the fact that not necessary all the samples have reached theevent time which makes the problem more difficult and a different challengefrom the typical regression problem. I will show in this presentation anexperimental comparison between different types of time-to-event analysismethods through the implementation of two differentscores.

Armand Boschin (PhD - TP)
Relation Prediction by Knowledge GraphEmbedding
We address the issue of relation prediction in a knowledge graph(KG). For instance, we would like to complete the triple (Berlin, *,Germany) with the relation capital of, assuming this fact is not in theKG. While existing KG embedding models can be used for this task, theirperformance is not satisfactory. In this paper, we propose two methodsthat greatly improve the performance of these models: first, a new neg-ative sampling method that balances the roles of entities and relationsduring training; second, a method to select candidate relations linkingtwo entities using the rdf:type edges of these entities. We obtain accu-racy scores as high as 94% on the popular FB15k237 dataset and 75% onWDV5, an extraction of Wikidata. This performance is all the moreremarkable that it is obtained with TransE, the simplest model for KGembedding. As an application of our approach, we show how to enrichWikidata by the semantification of Wikipedia, i.e., by predicting therelations associated with hyperlinks between pages ofWikipedia.

Eva Bouba (Intern - Inria)
Wind Farm Optimization Using Reinforcement Learning
After anintroduction on what wind farm optimization and reinforcement learningare, I will present how the latter can be applied to wind farmoptimization and the main challenges this poses

Pierre Civit (PhD- Sorbonne)
Dynamic Composable SecureEmulation
We present probabilistic dynamic I/O automata, a framework tomodel dynamic probabilistic systems. Our work extends dynamic I/O Automataformalism (Attie & Lynch) to probabilistic setting. Theoriginal dynamic I/O Automata formalism included operators for parallelcomposition, action hiding, action renaming, automaton creation, andbehavioral sub-typing by means of trace inclusion. They can modelmobility by using signature modification. They are also hierarchical: adynamically changing system of interacting automata is itself modeled as asingle automaton.

Our work extends to probabilistic settings all thesefeatures. Furthermore, we prove necessary and sufficient conditionsto obtain the implementation monotonicity with respect to automata creationand destruction. Our work lays down the premises for extending composablesecure-emulation (Canetti, Lynch & al.) to dynamic settings,an important tool towards the formal verification of protocolscombining probabilistic distributed systems and cryptography indynamic settings (e.g. blockchains, secure distributed computation,cybersecure distributed protocols etc).

Thomas Le Corre (Intern -Inria)
Kullback-Leibler optimal control
The gradual increase in theelectricity mix of the part of renewable intermittent resources is makingthe production / consumption adjustment at any time more difficult. It istherefore necessary to face this challenge in order to move towards smartgrids. This is why an idea is emerging which consists in usingflexibilities of some agents in order to absorb the excess or lack ofelectricity, when needed.

We place ourselves here from the point ofview of a "central planner" who receives a signal corresponding to theelectrical production and tries to optimize the consumption of a largenumber of agents. We want to minimize the Kullback-Leibler distance to thenominal behaviour, in order to conserve a good quality of service, whiletrying to fit the global consumption to the signal.

AndrianPutina (PhD - TP)
Random Histogram Forest for Unsupervised AnomalyDetection
Roughly speaking, anomaly detection consists of identifyinginstances whose features significantly deviate from the rest of input data.It is one of the most widely studied problems in unsupervised machinelearning, boasting applications in network intrusion detection,healthcare and many others. Several methods have been developed in recentyears, however, a satisfactory solution is still missing to the best ofour knowledge. We present Random Histogram Forest an effective approach forunsupervised anomaly detection. Our approach is probabilistic, which hasbeen proved to be effective in identifying anomalies. Moreover, it employsthe fourth central moment (aka kurtosis), so as to identify potentialanomalous instances. We conduct an extensive experimental evaluation on 38datasets including all benchmarks for anomaly detection, as well as themost successful algorithms for unsupervised anomaly detection, to the bestof our knowledge. We evaluate all the approaches in terms of the averageprecision of the area under the precision-recall curve (AP). Our evaluationshows that our approach significantly outperforms all other approaches interms of AP while boasting linear runningtime.

https://telecom-paris.zoom.us/j/94880732137?pwd=[REDACTED]

– ID de réunion : 948 8073 2137
– Codesecret : 705442

LINCS members scientific highlights (day 1)
2021-06-21 10:30 - 11:45 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
Quentin Lutz (Télécom-Paris)
Scikit-network: Graph Analysisin Python
Scikit-network is a Python package inspired by scikit-learn forthe analysis of large graphs. Graphs are represented by their adjacencymatrix in the sparse CSR format of SciPy. The package providesstate-of-the-art algorithms for ranking, clustering, classifying,embedding and visualizing the nodes of a graph. High performance isachieved through a mix of fast matrix-vector products (using SciPy),compiled code (using Cython) and parallel processing. The package isdistributed under the BSD license, with dependencies limited to NumPy andSciPy. It is compatible with Python 3.7 and newer. Source code,documentation and installation instructions are availableonline.

Ana Busic (Inria)
Zap Q-learning with NonlinearFunction Approximation
Zap Q-learning is a recent class of reinforcementlearning algorithms,
motivated primarily as a means to accelerateconvergence. Stability
theory has been absent outside of two restrictiveclasses: the tabular
setting, and optimal stopping. This paper introducesa new framework for
analysis of a more general class of Zap stochasticapproximation
algorithms. Based on this general theory, it is shown thatZap
Q-learning converges, even when the function approximationarchitecture
is nonlinear.

Based on a joint work with Shuhang Chen,Adithya M. Devraj, Fan Lu, and
Sean Meyn.

Mariapotop-butucaru (Sorbonne)
gaming the decentralized financePotop-Butucaru
Decentralized finance opens a new research field: reliabledistributed economical systems that is a cross research between classicaldistributed systems and mathematical models for economical systems.Blockchain technology is today at the core of decentralized finance.Differently from the classical distributed systems, blockchain technologyfaces complex faults and behaviors including rational. Interestingly, whenrational behaviors are combined with classical faults (e.g. Byzantinebehaviors) established results in distributed computing need to berevisited. This talk reports several results related to robustness ofdistributed abstractions used in blockchain technologies toByzantine and rational behaviors analyzed through the lens of gametheory.

François Durand (NBLF)
Voting rules for the aggregationof algorithms
Many problems, for example in decision-making, cannot besolved in an exact way and use heuristics which assign scores to thevarious possible choices. These heuristics can be numerous and more or lesscorrelated: for example, by varying the hyperparameters of an algorithm,we can generate a whole family of heuristics that are strongly correlatedbut of variable quality. Rather than looking for the best heuristic, wepropose to aggregate the scores in a smart way that is inspired by votingtheory. Our solution, which uses correlations between heuristics, is moreefficient than trivial aggregation and more robust than an approach basedon maximum likelihood.

Kalpana Singh (SystemX)
Bitcoin walletsecurity using non-interactive threshold ECDSA
Abstract In this talk, wewill study the risen need of threshold ECDSA for Cryptocurrencies security.As with the financial transactions, the intent is for the digitalsignature to uniquely identify and verify authorization of the approvingparty, to prevent forgery by unauthorized parties, and to be associatedwith a specific transaction. Cryptocurrencies achieve these objectives byusing cryptographic keys to generate an Elliptic Curve Digital SignatureAlgorithm (ECDSA) signature which authorize transactions. Protecting thesecryptographic keys is paramount to protecting the wallet and the walletholder’s associated digital assets. To achieve this objective, thresholdECDSA has been studied in the cryptocurrency’ssecurity.

https://telecom-paris.zoom.us/j/94880732137?pwd=[REDACTED]

– ID de réunion : 948 8073 2137
–Code secret : [REDACTED]

Communication Network Research @ LINCS
2021-06-21 09:30 - 10:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
I will review recent contributions of members of LINCS to thefield of cellular communication networks. This will cover topics rangingfrom the development of new stochastic geometry tools for these networks,to research conducted on core 5G issues like beam management or bandwidthpart, to research on specific domains like vehicular networks ornon-terrestrialnetworks.

https://telecom-paris.zoom.us/j/94880732137?pwd=[REDACTED]

– ID de réunion : 948 8073 2137
–Code secret : [REDACTED]

2021 Workshop with LINCS Scientific Committee
2021-06-21 - 2021-06-22 | LINCS + Zoom, 23 avenue d'Italie, Paris, 75013, France
LINCS organizes a rich two-day eventwith talks by its international Scientific Committee.
Monday 21st (Paristime)
15.15 - 16.00 Invited talk by Professor Marco Ajmone-Marsan(PoliTecnico di torino) on “Queuing Models of Radio Access NetworksOffering Streaming and ElasticServices”
We consider radio access networks (RANs) offering streaming and elasticservices. The RAN is modeled with tools from queuing theory, and weexamine the cases in which the system performance can be derived with lowcomplexity. In addition, we provide numerical results for common cellconfigurations, showing that some of the emerging behaviors can beunexpected, and provide insight into the effective deployment of smallcells.
16.10 -16.55 Invited talk by Professor P.R. Kumar (Texas A&MUniversity) on “Security of Cyberphysical Systems”
The coming decadesmay see the large scale deployment of networked cyber-physical systems toaddress global needs in areas such as energy, water, health care, andtransportation. However, as recent events have shown, such systems arevulnerable to cyber attacks. We present a general technique, called"dynamic watermarking," for detecting any sort of malicious activity innetworked systems of sensors and actuators. We present results of tests onautomobiles both in a lab setting, and on a test track, a lab processcontrol system, a lab model of a helicopter, a lab version of asolar-powered distribution system, and a simulation study of defenseagainst an attack on the power system.
[Joint work with BharadwajSatchidanandan, Jaewon Kim, Woo Hyun Ko, Tong Huang, LantianShangguan, Kenny Chour, Gopal Kamath, Jorge Ramos, Le, SwaminathanGopalswamy, Le Xie, and Prasad Enjeti].
17.05 - 17.50 Invited talk byProfessor Jim Kurose (University of Massachusetts) on “From artifacts tosystems to people: evolving directions in computing research andeducation”
Computing is now “old enough” as a discipline that we canalready detect broad trends in research directions. We discuss thesetrends, with an emphasis on both current and future directions incomputing research, which we see reflected locally (at my own university,UMass Amherst) nationally and internationally. We’ll discussrecent national computing research and education programmatics and trends,and the role of computing in the larger R&D enterprise.

Tuesday22nd (Paris time)

14.25 - 15.10 Invited talk by Professor HolgerKarl (Universität Paderborn) on “Machine Learning for NetworkManagement”

Machine Learning has been applied to a wide range of networking topics.Network management provides ample examples, often of the type ofcombinatorial optimizations. In the talk, we look at two examples. Oneexample comes from the context of network softwarization, where weinvestigate how machine learning approaches can help with scaling andplacing virtual network functions, as well as routing traffic betweenthem. The second example comes from wireless sensor networks with acousticapplications in mind, where we need to balance acoustic sensing qualitywith wireless network quality and use these two metrics to move mobilemicrophones into good locations.

15.40 - 16.25 Invited talk byProfessor Leandros Tassiulas (Yale University) on “Enabling intelligentservices via function virtualization at the network edge”
Theproliferation of novel mobile applications and the associated AI servicesnecessitates a fresh view on the architecture, algorithms and services atthe network edge in order to meet stringent performance requirements. Somerecent work addressing these challenges is presented. In order to meet therequirement for low-latency, the execution of computing tasks moves formthe cloud to the network edge, closer to the end-users. The jointoptimization of service placement and request routing in dense mobile edgecomputing networks is considered. Multidimensional constraints areintroduced to capture the storage requirements of the vast amounts of dataneeded. An algorithm that achieves close-to-optimal performance using arandomized rounding technique is presented. Recent advances in networkvirtualization and programmability enable realization of services aschains, where flows can be steered through a pre-defined sequence offunctions deployed at different network locations. The optimal deploymentof such service chains where storage is a stringent constraint in additionto computation and bandwidth is considered and an approximation algorithmwith provable performance guarantees is proposed and evaluated. Finally theproblem of traffic flow classification as it arises in firewalls andintrusion detection applications is presented. An approach for realizingsuch functions based on a novel two-stage deep learning method for attackdetection is presented. Leveraging the high level of data planeprogrammability in modern network hardware, the realization of thesemechanisms at the network edge is demonstrated.

16.35 - 17.20Invited talk by Professor Roch Guerin (Washington University in SaintLouis) on “Edge Classification: Offloading under Token BucketConstraints”

We consider an edge-computing setting where machine learning-basedalgorithms are used for real-time classification of inputs acquired bydevices, e.g., cameras. Computational resources on the devices areconstrained, and therefore only capable of running machine learning modelsof limited accuracy. A subset of inputs can be offloaded to the edge forprocessing by a more accurate but resource-intensive machine learningmodel. Both models process inputs with low-latency, but offloading incursadditional network and compute delays. To manage these delays and meetapplication deadlines, a token bucket constrains transmissions from thedevice. We first introduce a Markov Decision Process-based framework tomake offload decisions under such constraints when the input process isi.i.d. Decisions are based on the local model's confidence and the tokenbucket state, with the goal of minimizing a specified error measure forthe application. We then extend the approach to configurations involvingmultiple devices connected to the same access switch to realize thebenefits of a shared token bucket. Next we explore an approach based ondeep Q-networks (DQN) to handle more complex input and classificationprocesses, and demonstrate its ability to learn such features andeffectively incorporate them into policy decisions. We evaluate andanalyze the policies derived using our framework on the standard ImageNetimage classification benchmark.1,2

1. This is joint work with AyanChakrabarti, Chenyang Lu, Jiaming Qiu, Ruiqi Wang, and Jiangnan Liu 2.Part of this work will be presented at the 2021 ACM/IEEE SECconference

Git 101 - How to use git in an idiomatic way
2021-06-18 13:00 - 14:00
Git is a very popular version control software. While beingvery flexible, it is quite easy to get lost in the command and use it in avery un-optimal way. In this presentation, we will show visualizationsoftware for git, how to avoid anti patterns in git and more generallyhave a better time collaborating with git. Bring all your git questionswith you :).

Useful links:
-http://git-school.github.io/visualizing-git/,
-https://learngitbranching.js.org/.

Slides

R-SWAP: Relay based atomic cross-chain swap protocol
2021-06-16 14:00 - 15:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
In this presentation, we consider the problem of cross-chaintransactions where parties that do not trust each other safely exchangedigital assets across blockchains. Open blockchains models aredecentralized ledgers that keep records of transac- tions. They arecomparable with distributed account books. While they have proven theirpotential as a store of value, exchanging assets across severalblockchains remains a challenge. We propose a new protocol, R-SWAP, forcross-chain swaps that outperforms existing solutions. Our protocol isbuilt on top of two abstractions: relays and adapters that we formalize forthe first time. Furthermore, we prove the correctness of R-SWAP andanalytically evaluate its performances, in terms of cost and latency.Moreover, we evaluate the performances of R-SWAP in two case studiesshowing the generality of our approach: atomic swaps between Ethereum andBitcoin (two popular permissionless blockchains) and atomic swaps betweenEthereum and Tendermint (one permissionless and one permis- sionedblockchain).

Replica-mean-field limits for intensity-based neural networks
2021-06-09 14:00 - 15:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
Computational neuroscience features a variety of stochasticnetwork models where both the input and the output of each neuron are pointprocesses. In these models, each neuron has a state which evolves as anintegral with respect to its input point processes and which resets whenthe neuron spikes. In intensity-based neural networks, the spikes of agiven neuron have a stochastic intensity which is a linear function of theneuron state. Spiking events define the output point processes of theneuron. These, together with the geometry of the network connections,define in turn the input point processes of other neurons.

Due to theinherent complexity of such intensity-based neural models, relating thespiking activity of a network to its structure currently requiressimplifying assumptions, such as considering models in the thermodynamicmean-field limit. In this limit, an infinite number of neurons interactvia vanishingly small interactions, thereby erasing the finite sizegeometry of interactions.

To better capture the geometry in question,this paper analyzes the activity of intensity-based neural networks in thereplica-mean-field limit regime. Such systems are made of infinitely manyreplicas which have the same basic structure as that of the finite networkof interest and interact through randomized connections.

The maincontribution is an analytical characterization of the stationary dynamicsof intensity-based neural networks excitatory synapses in thisreplica-mean-field limit. Specifically, the stationary dynamics of theselimiting networks is functionally characterized via ordinary or partialdifferential equations derived from the Poisson Hypothesis of stochasticnetwork theory. This functional characterization is reduced to a system ofself-consistency equations specifying the stationary neuronal spikingrates. The approach combines the rate-conservation principle of Palmcalculus, analytical considerations from generating-function methods, andpropagation of chaos techniques.

Such limits can be used for first-ordermodels, whereby elementary replica constituents are single neurons withindependent Poisson inputs, and in second-order models, where theseconstituents are pairs of neurons with exact pairwise interactions. In bothcases, these replica-mean-field networks provide tractable versions thatretain important features of the finite network structure ofinterest.

Joint work with T. Taillefumier.

Around the Poisson-Voronoi tessellation
2021-06-09 11:00 - 12:00
Poisson point processes are one of the most common pointprocesses studied in stochastic geometry. Adding a Voronoi tessellation toa Poisson point process leads to the Poisson-Voronoi tessellation, whichis commonly used to study wireless networks. In this talk, we will studysome useful and interesting results revolving around the Poisson-Voronoitessellations and some applications.

Slides

PhDs presentations n° 3
2021-06-02 14:00 - 15:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
Seminar by:

* Razanne Abu-aisheh (PhD, Inria+NBLF)

*Gabriele Castellano (Postdoc, Inria)

* Camila Fernandez (PhD,Sorbonne+NBLF)

ISP Probing Reduction with Anaximander
2021-06-02 10:45 - 12:00
Dear all, The Internet Measurement reading group will meetagain on June 2nd. In this session Emeline Maréchal (ULiège) willpresent « ISP Probing Reduction with Anaximander ».
I encourage you tojoin us at 10:45 for a virtual coffee break, so that the talk beginsat 11:00.

Dans cette présentation, je vais parler de découverte detopologie, et plus particulièrement de découverte de la topologieintra-domaine d’un AS en particulier.Rocketfuel est toujours considérécomme l’état de l’art pour se focaliser sur un AS d’intérêt.Seulement, il date d’il y a 20 ans. Et le plus étonnant, c’est quedepuis Rocketfuel, il n’y a pas eu de nouvelles tentatives pourcartographier des ASes.Je vais donc commencer par montrer les limites deRocketFuel dans l’Internet d’aujourd’hui, ce qui nous permettra devoir en quoi il n’est plus adapté de nos jours.Je continuerai ensuite envous présentant Anaximander, notre nouvel outil, qui est capable dediriger ses sondes vers l’AS d’intérêt, tout en réduisant unmaximum le nombre de sondes envoyées, afin d’obtenir les cartesintra-domaines les plus précises possibles.Je présenterai nosdifférentes stratégies, depuis le design de notre liste initiale desondes, jusqu’à nos différentes techniques de réduction, basées surl’analyse des tables de routage. Anaximander offre aussi la possibilitéde contrôler le dilemme entre maximiser la couverture de l’AS etminimiser le nombre de sondes envoyées.

Emeline Marechalreceived her MS degree in Computer Engineering from the Université deLiège (Belgium) in 2019. She is currently a Ph.D. student at theMontefiore Institute at the Université de Liège. Her research interestsare in network measurements, including traffic and topology measurements,and measurement applied tosecurity.

Best,
Maxime

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"Risk-Averse Equilibrium Analysis and Privacy Impact on GeneralizedNash Equilibrium in Peer-to-Peer Electricity Market"
2021-05-26 14:00 - 15:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
We consider a network of prosumers trading electricity under(i) a centralized market design, seen as the benchmark, formulated as anoptimization problem, and (ii) a peer-to-peer market design, formulatedas a generalized Nash equilibrium problem. High renewable energypenetration requires that the market properly handles uncertainty. To thatpurpose, we introduce coherent risk measures in the prosumers’ utilityfunctions, reflecting heterogeneity in their risk attitudes. In this riskaugmented setting, we formulate risk neutral and risk-averse models for(i), (ii). We characterize risk-neutral and risk-averse marketequilibrium, relying on generalized Nash equilibrium and variationalequilibrium as solution concepts. To hedge their risk towards uncertaintyand complete the market, prosumers can trade financial contracts. Weprovide closed form characterizations of the risk-adjusted probabilitiesand the prices for the financial contracts trading under different marketregimes. Privacy being one crucial feature of peer-to-peermarkets, we extend the risk-neutral model ofthe peer-to-peer electricity market by formulating it asa noncooperative communication game, where the agents determinetheir randomized reports to share with the other market players, whileanticipating the form of the peer-to-peer market equilibrium. Wecharacterize the equilibrium of the game, prove the uniqueness of theVariational Equilibria and provide a closed form expression of the privacyprice. On a three node toy network and the IEEE 14-bus network, weprovide numerical analysis of the impact of risk heterogeneity, financialcontracts and privacy inclusion on the prosumers’ expected costs.

Asynchronous programming in Python
2021-05-26 11:00 - 12:00
By default, in most programming languages, input/outputoperations are blocking: the execution flow of the program is stopped whilewaiting for external data from the disk or the network.
This is wastefulas these operations can take up to multiple seconds, and during this timethe CPU is free for running other tasks.
Asynchronous I/O is a set oftechniques to enable non-blocking I/O operations and achieve greaterconcurrency levels in I/O bound programs such as web servers.
In thissession, we will introduce asynchronous programming in Python by using thebuilt-in asyncio library.

Slides (pdf)

Radio and compute resource allocation in C-RAN
2021-05-19 14:00 - 15:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
The principal tenet of C-RAN is the softwarization of thebase-band signal processing, which enables the sharing of computeresources among multiple radio heads. Resource allocation in C-RAN isconstrained by the hard deadline within which the computation in the sharedresource pool needs to happen to preserve the functionality of thesystem.

When the aggregate demand of compute resources in thepool exceeds the capacity, a fraction of the radio packets is lost. Anatural choice for the allocation policy is to minimize the loss rate. Analternative strategy is to maximize the PHY layer througput. Bothstrategies may be pursued by framing the allocation of compute resources asan optimization problem.

In order to select the best strategy itis useful to consider the impact of the choice on upper layers. We considerthe performance at the MAC layer, after the HARQ process has taken place.Each packet lost due to lack of compute resources triggers an HARQ requestof retransmission. If the loss happens on the last allowed transmission,all the radio resources (present and past) spent for the message go towaste. This consideration suggests that a policy of allocation of thecompute resources accounting for the retransmission age of the frame mayincrease the performance.

Existence of fixed points for the ./GI/1 queue
2021-05-19 11:00 - 12:00
We present the work of Mairesse and Prabakhar on the existenceof fixed points for infinite tandems of queues with i.i.d. service times.We will first introduce the formalism of queueing maps in a generalsetting, before presenting the main results on both existence anduniqueness of fixed points for these queueing maps. We will also discussthe range of means of service times for which such fixed pointsexist.

Slides

Networking on the Move
2021-05-12 10:45 - 12:00
Dear all,
The Internet Measurement reading group will meetagain on May 12th.

In this session we will discuss Internet aboardtrains, planes and in space.
We will discuss the technologies, theirperformance and the challenges for Internet measurements.

I encourageyou to join us at 10:45 for a virtual coffee break, so that the talkbegins at 11:00.

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PhDs presentations n° 2 on "Network Theory + Wireless (5g & V2X)"
2021-05-05 14:00 - 15:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
Seminar by:

Stefano Iellamo (Engineer TP) = WirelessNetworks
Yibo Quan (PhD TP) = Wireless Networks
Maxime Raynal (PhDNokia) = Graphs, machine learning, algorithmics
Bharath Roy Choudhury(PhD Inria) = Network Theory
Michael Davidov (PhD Inria) = NetworkTheory
Sayeh Khaniha (PhD Inria) = Network Theory
Pierre Popineau(PhD Inria) = Network Theory

Python profiling
2021-05-05 11:00 - 12:00
This session will be devoted to a non-exhaustive view ofprofiling techniques that can be useful in Python. While profiling isabsolutely no substitute for the algorithmic complexity analysis, it is aquick, easy, and seductive path to find out the real bottlenecks of yourcode and get rid of them.

Hyperlinks mentionned in the chat during thesession:

IPython magics:https://ipython.readthedocs.io/en/stable/interactive/magics.html,
Python3-cprofile (Lincs intranet):https://wiki.inria.fr/lincs/Python3-cprofile.

SOBA: Session optimal MDP-based network friendly recommendations
2021-04-28 14:00 - 15:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
Caching content over CDNs or at the network edge has beensolidified as a means to improve network cost and offer better streamingexperience to users. Furthermore, nudging the users towards low-costcontent has recently gained momentum as a strategy to boost networkperformance. We focus on the problem of optimal policy design for NetworkFriendly Recommendations (NFR). We depart from recent modeling attempts,and propose a Markov Decision Process (MDP) formulation. MDPs offer aunified framework that can model a user with random session length. As itturns out, many state-of-the-art approaches can be cast as subcases of ourMDP formulation. Moreover, the approach offers flexibility to model userswho are reactive to the quality of the received recommendations. In termsof performance, for users consuming an arbitrary number of contents insequence, we show theoretically and using extensive validation over realtraces that the MDP approach outperforms myopic algorithms both in sessioncost as well as in offered recommendation quality. Finally, even comparedto optimal state-of-art algorithms targeting specific subcases, our MDPframework is significantly more efficient, speeding the execution time bya factor of 10, and enjoying better scaling with the content catalog andrecommendation batch sizes.

Exponential families
2021-04-28 11:00 - 12:00
Exponential families are parametric sets of probabilitydistributions that arise in many applications. These include well-knownunivariate distributions (such as the binomial, Poisson, geometric,exponential, and normal distributions), but also multi-variatedistributions like probabilistic graphical models and stationarydistributions of several queueing models. In this presentation, we willfirst recall the definition of exponential families and motivate theirstudy. In a second time, we will present a generic method forapproximating the normalization constant of these distributions, as theexact calculation of this constant is practically infeasible in highdimension.

References:

M. J. Wainwright and M. I. Jordan. GraphicalModels, Exponential Families, and Variational Inference. Foundations andTrends® in Machine Learning 1.1 (2008),https://people.eecs.berkeley.edu/~wainwrig/Papers/WaiJor08_FTML.pdf.Chapters 1, 2, and 3 and Appendix A.
S. Boyd and L. Vandenberghe.Convex Optimization. Cambridge University Press (2004),https://web.stanford.edu/~boyd/cvxbook/bv_cvxbook.pdf. Section 3.3.
Wikipedia pages Exponential family, Maximum-entropy probabilitydistribution, Principle of maximum entropy, Lagrange multiplier, Convexconjugate.

Slides

Pattern Matching, text generation and sequence complexity
2021-04-21 14:00 - 15:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
Pattern matching is a powerful tool used on many kinds of dataas long as they stand on a linear support such as texts or other sequences.It can also be extended to regular supports standing in any Euclidianspace. It constitutes the engine of the most powerful compressionalgorithms on texts and also the foundation of many universal predictorsover time sequences. Recently pattern matching has been applied in shorttext classification under the name “Joint Complexity” in a perspectiveof Accelerated Artificial Intelligence. One of the interesting aspects ofpattern matching is that it is based on extremely strong foundations ininformation theory and in the asymptotic analysis of algorithms. Inparticular when the source of sequence is well defined and parametrized. Wewill investigate the special case of Markov source models and show how theyare “good enough” to model natural language texts. We will present somesmall games which illustrate this fact, in parallel with the descriptionof deeper theoretical results.

Reduce, Reuse, Recycle: Repurposing Existing Measurements toIdentify Stale Traceroutes
2021-04-21 10:45 - 12:00
Dear all,
The Internet Measurement reading group will meetagain on April 21st.
We will talk about the following paper : Reduce,Reuse, Recycle: Repurposing Existing Measurements to Identify StaleTraceroutes (Giotsas et al, IMC 2020).

I encourage you to join usat 10:45 for a virtual coffee break, so that the talk beginsat 11:00.

Abstract:

Many systems rely on traceroutes tomonitor or characterize the Internet. The quality of the systems’inferences depends on the completeness and freshness of the traceroutes,but the refreshing of traceroutes is constrained by limited resources atvantage points. Previous approaches predict which traceroutes are likelyout-of-date in order to allocate measurements, or monitor BGP feeds forchanges that overlap traceroutes. Both approaches miss many path changesfor reasons including the difficulty in predicting changes and the coarsegranularity of BGP paths.
This paper presents techniques to identifyout-of-date traceroutes without issuing any measurements, even if a changeis not visible at BGP granularity. We base our techniques on twoobservations. First, although BGP updates encode routes at ASgranularity, routers issue updates when they change intra-domain routes orpeering points within the same AS path. Second, route changes correlateacross paths, and many publicly available traceroutes exist. Ourtechniques maintain an atlas of traceroutes by monitoring BGP updates andpublicly available traceroutes for signals to mark overlapping atlastraceroutes as stale. We focus our analysis of traceroute path changes atthe granularity of border router IPs which provides an abstraction finerthan AS or PoP-level but is not affected by the periodicity of intra-domainload balancers. Our evaluation indicates that 80% of the traceroutes thatour techniques signal as stale have indeed changed, even though the AShops remained the same. Our techniques combine to identify 79% of allborder IP changes, without issuing a single onlinemeasurement.

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PhDs presentations n° 1 on Network Metrology, Blockchain,Computational Social Choice
2021-04-07 14:00 - 15:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
Seminar by:

- Maxime Mouchet (Postdoc UPMC) = NetworkMetrology

- Matthieu Gouel (PhD UPMC) = Network Metrology

- PierreCivit (PhD UPMC) = Blockchain

- Simona Ramos (PhD NBLF) =Blockchain

- Abhimanyu Rawat (PhD NBLF) = Blockchain

- ThéoDelemazure (Intern NBLF) = Computational Social Choice

Design of algorithms for the production of training data
2021-04-07 11:00 - 12:00
There is a well-known saying in the supervised machine learningcommunity: "garbage in, garbage out". The performance of a supervisedlearning algorithm depends critically on the quantity and quality oftraining data. This training data is obtained from raw data through datalabeling performed by human experts. The growing use of machine learningtools makes the design of efficient data labeling algorithms more relevantthan ever.

We will present progress made in collaboration with MayaStein (University of Chile) and Alexander Scott (Oxford University) on aproblem proposed by Maria Laura Maag (Nokia). It corresponds to thereconstruction of a set partition using as few queries as possible, eachquery asking whether two elements belong to the same block. We characterizethe optimal algorithms and analyze the optimal distribution of the numberof queries.

Slides (Quentin)

Slides (Élie)

Reconfigurable Intelligent Surfaces for Wireless Communications
2021-03-31 14:00 - 15:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
Reconfigurable intelligent surfaces (RISs) have recentlyemerged as the new wireless communication research frontier with the goalof realizing metamaterial-coated smart and reconfigurable radio propagationenvironments via passive and tunable signal transformations. Featured byorders of magnitude lower hardware and energy cost than traditional activeantenna-arrays and yet superior performance, RISs are the new drivingtechnology for future wireless networks, especially for enabling them tomigrate to higher frequency bands. RISs have the inherent potential offundamentally transforming the current wireless network with active nodessolely into a new hybrid network comprising active and passive componentsco-working in an intelligent way, so as to achieve a sustainable capacitygrowth with a low and affordable cost and power consumption. Therefore,RISs have the potential to change how wireless networks are currentlydesigned, usher in that hoped-for wireless future, and are regarded as anenabling technology for realizing the emerging concept ofmetamaterial-assisted smart radio environments (SREs). RIS-assisted SREsare a multidisciplinary research endeavor but are not well-understood. Inthis talk, I will introduce the state of the art, the researchchallenges, and some recent research results at the crossroad of wirelesscommunications, electromagnetics, physics, and metamaterials. Source:arXiv:2004.09352 (IEEE JSAC, Nov. 2020).
Bio
Marco Di Renzo received theLaurea (cum laude) and Ph.D. degrees in electrical engineering from theUniversity of L'Aquila, Italy, in 2003 and 2007, respectively, and theHabilitation à Diriger des Recherches (Doctor of Science) degree fromUniversity Paris-Sud, France, in 2013. Since 2010, he has been with theFrench National Center for Scientific Research (CNRS), where he is a CNRSResearch Director in the Laboratory of Signals and Systems (L2S) ofParis-Saclay University – CNRS and CentraleSupelec, Paris, France. InParis-Saclay University, he serves as the Coordinator of theCommunications and Networks Research Area of the Laboratory of ExcellenceDigiCosme, and as a member of the Admission and Evaluation Committee ofthe Ph.D. School on Information and Communication Technologies. Currently,he serves as the Editor-in-Chief of IEEE Communications Letters, and is aDistinguished Lecturer of the IEEE Vehicular Technology Society and IEEECommunications Society. Also, he serves as the Founding Chair of theSpecial Interest Group on Reconfigurable Intelligent Surfaces of theWireless Technical Committee of the IEEE Communications Society. He is aHighly Cited Researcher (Clarivate Analytics, Web of Science), a Fellowof the IEEE, and a Fellow of the IET. In 2019, he was a recipient of aNokia Foundation Visiting Professorship for conducting research onmetamaterial-assisted wireless communications at Aalto University,Finland.

Classification of Load Balancing in the Internet
2021-03-31 10:45 - 12:00
Dear all,

Next Wednesday (31/03/2021) will take place thefirst Internet Measurement reading group !
We will talk about thefollowing paper : Classification of Load Balancing in the Internet(https://homepages.dcc.ufmg.br/~cunha/papers/almeida20infocom-mca.pdf).

I encourage you to join us at 10:45 for a virtual coffee break, so thatthe talk begins at 11:00.

Abstract:

Recent advances inprogrammable data planes, software-defined networking, and the adoptionof IPv6 support novel, more complex load balancing strategies. Weintroduce the Multipath Classification Algorithm (MCA), a probingalgorithm that extends traceroute to identify and classify load balancingin Internet routes. MCA extends existing formalism and techniques toconsider that load balancers may use arbitrary combinations of bits in thepacket header for load balancing. We propose optimizations to reduceprobing cost that are applicable to MCA and existing load balancingmeasurement techniques. Through large-scale measurement campaigns, wecharacterize and study the evolution of load balancing on the IPv4 and IPv6Internet with multiple transport protocols. Our results show that loadbalancing is more prevalent and that load balancing strategies are moremature than previous characterizations have found.

--
Sujet : Zoommeeting invitation - Internet Measurement Reading Group
Heure : 31 mars2021 10:45 AM Paris

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DNN Based Beam Selection in mmW Heterogeneous Networks
2021-03-24 14:00 - 15:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
In this work, we consider a heterogeneous cellular networkwherein multiple small cell millimeter wave (mmW) base stations (BSs)coexist with legacy sub-6GHz macro BSs. In the mmW band, small cells usemultiple narrow beams to ensure sufficient coverage and User Equipments(UEs) have to select the best small cell and the best beam in order toaccess the network. This process usually based on exhaustive search mayintroduce unacceptable latency. In order to address this issue, we rely onthe sub-6GHz macro BS support and propose a deep neural network (DNN)architecture that utilizes basic components from the Channel StateInformation (CSI) of sub-6GHz network as input features. The output of theDNN is the mmW BS and beam selection that can provide the bestcommunication performance. In the set of features, we avoid using the UElocation, which may not be readily available for every device. Weformulate a mmW BS selection and beam selection problem as a classificationand regression problem respectively and propose a joint solution using abranched neural network. The numerical comparison with the conventionalexhaustive search results shows that the proposed design demonstrate betterperformance than exhaustive search in terms of latency with at least 85%accuracy.

Python Threads 101 + Python Sockets 102
2021-03-24 11:00 - 12:00
The threading library permits programs to execute severalthings at the same time on the same machine. This talk will review thebasics of the Python threading library to write concurrent applications,and how it can be used to build responsive network applications.

Thenotebooks use for the presentation are available athttps://github.com/tixeuil/lincs-python-workshop

Collective brainstorming for the organization of the June WS withthe LINCS Co.Sci.
2021-03-17 14:00 - 15:00 | LINCS + Zoom, 23 avenue d'Italie, Paris, 75013, France
This time, during our usual seminar time-slot, the wholeLINCS community is encouraged to participate in a remote collectivebrainstorming to elaborate on the organizational structure of the workshopthat will take place in June (21st, 22nd) with the LINCS ScientificCommittee. 7 out of 9 members already confirmed theirparticipation.

The session will be coordinated bySébastin Tixeuil who's the member of the LINCS ExecutifCommittee in charge for the scientific organization of the 2021 Juneworkshop.

You'll find here embedded a scheme of previousworkshops organized with the LINCS Co.Sci. As you'll see, variations havebeen limited, but this year we'll have to take into account that 1)Compared to the past, more Co.Sci. members will present their works. 2) Itwill probably take place remotely via Zoom, thus its format should adaptto this new situation (which sets limits, but also open up newpossibilities!).

Ensemble methods
2021-03-17 11:00 - 12:00
Ensemble methods are popular machine learning techniques thatcombine the predictions of multiple agents to improve their accuracy androbustness. We will introduce these methods, with a focus on twoalgorithms, random forest and XGBoost.

Slides

Formalizing the analysis of blockchains robustness through gametheory
2021-03-10 14:00 - 15:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
Blockchains systems evolve in complex environments that mixclassical patterns of faults with selfish, rational or irrationalbehaviours typical of economic systems. During the presentation we discussa new game theoretical framework that formally characterizes the robustnessof blockchains systems in terms of resilience to rational deviations andimmunity to Byzantine behaviors. We apply the model to known blockchainprotocols, including Bitcoin, and we identify the upper and lower boundsof their robustness indices.

FCLTs for Determining the Performance in Finite Systems of Serverswith Randomized Load Balancing
2021-03-03 14:00 - 15:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
Here the abstract and bibliography provided by ProfessorMazumdar for histalk: http://www.lincs.fr/wp-content/uploads/2021/01/FCLT_MFE.pdf

Container Overview
2021-03-03 11:00 - 12:00
Containers are one of the fundamentals of cloud nativeapplication development. Popularized by Docker and now widely adopted bythe cloud computing industry, containers paved the way for a immutablestyle of application deployment. In this presentation, we will go oversome of the fundamentals about containers: What are they? What problems dothey solve? How can I get started with them today? What benefits docontainers bring in the long run? What is container orchestration?

Ifyou have questions about containers that you always had in the back of yourmind, be sure to bring them over!

Rémy Léone (LINCS alumni) is aCloud Developer Advocate at Scaleway and contributor to Kubernetesdocumentation French localization.

Slides

Can we automate our own work — or show that it is hard?
2021-02-24 14:00 - 15:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
Computer scientists seek to understand what can be automated,but what do we know about automating our own work? Can we outsource our ownresearch questions to computers? In this talk I will discuss this questionfrom the perspective of the theory of distributed computing. I will presentnot only recent examples of human-computer-collaborations that haveresulted in major breakthroughs in our understanding of distributedcomputing, but I will also explore the fundamental limits of suchapproaches.
Bio
Jukka Suomela (https://jukkasuomela.fi/) is AssociateProfessor in the Department of Computer Science at Aalto University,Finland. His work focuses on the theoretical foundations of distributed andparallel computing, with particular emphasis on the concept of locality.He was the PC chair of DISC 2019 and SIROCCO 2016 and one of the localchairs of ALGO 2018, he has served in the EATCS council, and he iscurrently the vice chair of the DISC steering committee. He has receivedthe FOCS 2019 best paper award and DISC 2012 and 2017 best paper awards,as well as a number of teaching awards.

Here's the Zoom linkto attend the seminar talk:https://telecom-paris.zoom.us/j/94270583366?pwd=[REDACTED]

ID de réunion : 942 7058 3366
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A Mathematical Theory of Communication: Discrete Noisy Systems (2)
2021-02-24 11:00 - 12:00
In 1948 Shannon published the article that defines moderninformation theory. For this reading group, we will briefly remind thefirst part of the article about noiseless system, then we will present thesecond part of the article, which is concerned with transmission errors.We will in particular see how the trade-off between compression androbustness can be explained very simply with the notion of entropyintroduced by Shannon.

The video of the first part is available here:https://www.lincs.fr/events/a-mathematical-theory-of-communication-discrete-noisy-systems/.

The impact of multi-user massive MIMO on resource allocation in 5Gcellular networks
2021-02-17 14:00 - 15:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
One of the very important technologies for 5G is multi-usermassive MIMO. It has the potential to deliver excellent performance if usedwell. However, it is a very complex technology that changes the way weoperate networks.

Our presentation contains three parts. In thefirst part, we explain how resource allocation (RA) is performed in amulti-user massive MIMO system and present our latest results on therelative importance of different RA processes and assumptions. In thesecond part, we discuss preliminary results on how sharing betweenoperators can be managed in a Neutral Host setting when multi-user massiveMIMO is used. Finally, in the third part, we briefly discuss howmulti-user massive MIMO enables 5G Fixed Wireless Access that can be usedto bridge the digital divide in rural areas.

The work was done incollaboration with Prof. P. Mitran, Y. Zhang, A. Hussein, and A.Lappalainen. It was sponsored by NSERC, Cisco andRogers.

BIO

Catherine Rosenberg is a Professor inElectrical and Computer Engineering at the University of Waterloo since2004. Since June 2010, she holds the Canada Research Chair in the FutureInternet. She was elected an IEEE Fellow for contributions to resourcemanagement in wireless and satellite networks on 2011 and was elected aFellow of the Canadian Academy of Engineering in 2013. In April 2018, shebecame the Cisco Research Chair in 5G Systems.

Here, Prof. Rosenbergwebpage for further infos about her academic and research path:https://uwaterloo.ca/scholar/cath

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ID de réunion : 942 7058 3366
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A Mathematical Theory of Communication: Discrete Noisy Systems (1)
2021-02-17 11:00 - 12:00
In 1948 Shannon published the article that defines moderninformation theory. For this reading group, we will briefly remind thefirst part of the article about noiseless system, then we will present thesecond part of the article, which is concerned with transmission errors.We will in particular see how the trade-off between compression androbustness can be explained very simply with the notion of entropyintroduced by Shannon.

Real-time Bidding in First and Second Price Auctions with Temporaland Targeting Constraints
2021-02-10 14:00 - 15:00 | Zoom + LINCS, 23 avenue d'Italie, Paris, 75013, France
Please, find here the abstract and bibliography provided byProfessor Mazumdar for his talk:http://www.lincs.fr/wp-content/uploads/2021/01/Bidding_LINCS_Jan2021.pdf

Here, Professor Mazumdar's webpage with info on his academic path:https://ece.uwaterloo.ca/~mazum/

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The Zoom link toattend the eventis: https://telecom-paris.zoom.us/j/94270583366?pwd=[REDACTED]

ID de réunion : 942 7058 3366
Codesecret : 821734

Fastcore
2021-02-10 11:00 - 12:00
According to its website, fastcore is a set of "Python goodiesto make your coding faster, easier, and more maintainable".

"Fastcore[adds] to Python features inspired by other languages we've loved, likemultiple dispatch from Julia, mixins from Ruby, and currying, binding,and more from Haskell. It also adds some "missing features" and clean upsome rough edges in the Python standard library, such as simplifyingparallel processing, and bringing ideas from NumPy over to Python's listtype."

Edit distances, string alignments and dynamic programming
2021-02-03 11:00 - 12:00
Edit distances quantify how dissimilar two strings are bycounting the minimum number of edit operation (insertion, deletion, etc)to transform one string into the other. They are used in computer science(approximate string matching, file comparison, ...), in bioinformatic(nucleic acid sequence alignment...), etc. This presentation presents themain edit distances (Longest Common Subsequence, Levenshtein, Hamming,...), and shows how to compute them using dynamic programming.

Thispresentation was prepared in collaboration with Maxime Raynal (Nokia BellLabs France).

Slides.

Presentation of Huggingface Transformers library for NaturalLanguage Processing
2021-01-27 11:00 - 12:00
Transformers architectures have been dominating the benchmarksof most Natural Language Processing tasks for the past 3 years with newmodels popping up every week, making it difficult to keep up with thestate-of-the-art when trying to decide which model to use for a real worldscenario. The French/American startup Huggingface is helping a lot to unifythe efforts to make these new models available and I will present a part ofthese efforts and an example demonstrating how easy it now is to use andtest various models of their transformers library.

"Secure and Robust MIMO Transceiver for Multicast Mission CriticalCommunications"
2021-01-20 14:00 - 15:00
Mission-critical communications (MCC) involve allcommunications between people in charge of the safety of the civil society.MCC have unique requirements that include improved reliability, securityand group communication support. In this paper, we propose a secure androbust Multiple-Input-Multiple-Output (MIMO) transceiver, designed formultiple Base Stations supporting multicast MCC in presence of multipleeavesdroppers. We formulate minimization problems with theSum-Mean-Square-Error (SMSE) at legitimate users as an objective function,and a lower bound for the MSE at eavesdroppers as a constraint. Security isachieved thanks to physical layer security mechanisms, namely MIMObeamforming and Artificial Noise (AN). Reliability is achieved by designinga system which is robust to Channel State Information errors. They can beof known distribution or norm-bounded. In the former case, a coordinatedescent algorithm is proposed to solve the problem. In the latter case, wepropose a worst-case based iterative algorithm. Numerical results atphysical layer and system level reveal the crucial role of robust designsfor reliable MCC. We show the interest of both robust design and AN toimprove the security gap. We show that full BS cooperation is preferred forhighly secured and reliable MCC but dynamic clustering allows to trade-offsecurity and reliability against capacity.

Here's the streaming link:https://telecom-paris.zoom.us/j/94054078947?pwd=[REDACTED]

ID de réunion : 940 5407 8947
Code secret : [REDACTED]

A tutorial on Bayesian optimization with Gaussian processes
2021-01-20 11:00 - 12:00
Bayesian optimization proves to be useful when our goal is toi) optimize an unknown function, that we can learn by sampling ii) oursample budget is (very) limited iii) we can afford (potentially) heavycomputations in between two consecutive samples.

Slides will be largelyinspired by https://arxiv.org/abs/2012.08469.

"Self-Adjusting Networks: From Metrics to Algorithms"
2021-01-13 14:00 - 15:00
In this talk I will present the vision of self-adjustingnetworks: communication networks whose physical topology adapts to thetraffic pattern it serves, in a demand-aware manner. This vision isreminiscent of biased and self-adjusting datastructures, such as Mehlhorntrees and splay trees. Self-adjusting networks are enabled by emergingreconfigurable optical technologies. I will show that the benefit ofself-adjusting networks depends on the amount of "structure" there is inthe demand, and present an information-theoretical approach to measure thecomplexity of traffic traces and derive entropy-based metrics accordingly.I will also present optimal offline and online algorithms to designself-adjusting networks whose performance matches the derived metricsasymptotically.

The talk is primarily based on the followingpapers:

ReNets: Statically-Optimal Demand-Aware Networks
Chen Avinand Stefan Schmid.
SIAM Symposium on Algorithmic Principles ofComputer Systems (APOCS), Alexandria, Virgina, USA, January2021.
https://www.univie.ac.at/ct/stefan/apocs21renets.pdf

On theComplexity of Traffic Traces and Implications
Chen Avin, Manya Ghobadi,Chen Griner, and Stefan Schmid.
ACM SIGMETRICS, Boston,Massachusetts, USA, June2020.
https://www.univie.ac.at/ct/stefan/sigmetrics20complexity.pdf

Demand-Aware Network Designs of Bounded Degree
Chen Avin, Kaushik Mondal,and Stefan Schmid.
Distributed Computing (DIST), Springer,2020.
https://www.univie.ac.at/ct/stefan/dist20journal.pdf

SplayNet:Towards Locally Self-Adjusting Networks
Stefan Schmid, Chen Avin,Christian Scheideler, Michael Borokhovich, Bernhard Haeupler, and ZviLotker.
IEEE/ACM Transactions on Networking (TON), Volume 24, Issue 3,2016.
https://www.univie.ac.at/ct/stefan/ton15splay.pdf

For moredetails, see the project website:
https://self-adjusting.net/

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Here’s the streaming link:https://telecom-paris.zoom.us/j/94054078947?pwd=[REDACTED]

ID de réunion : 940 5407 8947
Code secret : [REDACTED]

Takeaways of building a research-oriented system
2021-01-13 11:00 - 12:00
Building a modern, scalable and fault-tolerant system inPython has never been so easy and enjoyable. Here is some takeaways ofbuilding such system in for research operations.

Slides

Multi-winner voting rules
2021-01-06 11:00 - 12:00
Multi-winner voting rules aggregate the opinions of severalagents and yield a set of several options. We will give an overview of theclassic rules of the literature, and show that different rules pursuedifferent objectives: excellence, proportionality or diversity.

Slides

Thesis defense "Tractable Reliable Communication in CompromisedNetworks"
2020-12-21 14:00 - 17:00
Reliable communication is a fundamental primitive indistributed systems prone to Byzantine (i.e. arbitrary, and possiblymalicious) failures to guarantee integrity, delivery, and authorship ofmessages exchanged between processes. Its practical adoption stronglydepends on the system assumptions. Several solutions have been proposed sofar in the literature implementing such a primitive, but some lack inscalability and/or demands topological network conditions computationallyhard to be verified.
This thesis aims to investigate and address some ofthe open problems and challenges implementing such a communicationprimitive. Specifically, we analyze how a reliable communication primitivecan be implemented in 1) a static distributed system where a subset ofprocesses is compromised, 2) a dynamic distributed system where part ofthe processes is Byzantine faulty, and 3) a static distributed systemwhere every process can be compromised and recover.
We define several moreefficient protocols and we characterize alternative network conditionsguaranteeing their correctness.

This is a joint thesis with SapienzaUniversità di Roma, Rome.

You can access the videoconference throughthe followinglink
https://uniroma1.zoom.us/j/82300863370?pwd=[REDACTED]

ID Zoom conference: 823 0086 3370
Passcode: [REDACTED]

The memberof the jury are:

M. Pierre Sens (LIP6, Sorbonne Université) -President
M. Luca Becchetti (DIAG, Sapienza Università di Roma) -Examiner
Mme. Maria Potop-Butucaru (LIP6, Sorbonne Université) -Examiner
M. Andrea Vitaletti (DIAG, Sapienza Università di Roma) -Examiner
M. Xavier Défago (Tokyo Institute of Technology, Tokyo) -Reviewer
M. Roy Friedman (Technion - Israel Institute of Technology,Isreael) - Reviewer
Mme. Silvia Bonomi (DIAG, Sapienza Università diRoma) – Thesis co-director
M. Sébastien Tixeuil (LIP6, SorbonneUniversité) – Thesis co-director

The presentation will be in English.

Thesis defense "Deep learning techniques for graph embedding atdifferent scales"
2020-12-17 14:00 - 17:00
In many scientific fields, studied data have an underlyinggraph or manifold structure such as communication networks (whether socialor technical), knowledge graphs or molecules. A graph is composed ofnodes, also called vertices, con- nected together by edges. Recently,deep learning algorithms have become state-of-the-art models in many fieldsand in particular in natural language processing and image analysis. It ledthe way to a great line of studies to generalize deep learning models tographs. In particular, several formulations of convolutional neuralnetworks were proposed and research is carried to develop new layers andnetwork architectures to graphs. Those models aim at solving differenttasks such as node classification, link prediction or graphclassification. In this work, we study node, subgraph or graph embeddingsproduced by graph neural networks. These embeddings at different scalesencode hierarchical represen- tations of graphs. Based on these embeddingtechniques, we propose new deep learning architectures to tackle nodeclassification or graph classification tasks. We study several applicationsof these new techniques. For example, we study the problem of having agraph embedding invariant by node permutation and the interpretability ofgraph neural networks.

Here's the details to follow it onGoToMeeting:

Participez à ma réunion depuis votre ordinateur,tablette ousmartphone. https://global.gotomeeting.com/join/962144589 Vouspouvez aussi appeler à l'aide de votretéléphone. États-Unis: +1 (872) 240-3311 Coded'accès: 962-144-589 Rejoignez la réunion depuis une salle ouun système de vidéoconférence. Composez ou tapez : 67.217.95.2ou inroomlink.goto.com ID réunion: 962 144 589 Ouappelez directement: 962144589@67.217.95.2 ou67.217.95.2##962144589 Vous n'utilisez pas encore GoToMeeting ?Téléchargez l’application dès maintenant et soyez prêt pour votrepremièreréunion : https://global.gotomeeting.com/install/962144589

Special meeting: new tool for LINCS research&projects
2020-12-16 14:00 - 15:00
The LINCS community is encouraged to participate in anexceptional Wednesday meeting with Fabien Mathieu to check, discussand exchange about a new tool to share infos about our lab research topicsand ongoing projects.

This operational meeting is important andwe wish it will be widely attended!

Python Sockets 101
2020-12-16 11:00 - 12:00
The socket library permits programs that execute on variousmachines over a network to communicate. This talk will review the basics ofthe Python socket library to write distributed applications.

Thesis defense "Mechanisms and architectures to encourage themassive and efficient use of local renewable energy"
2020-12-14 15:00 - 18:00
To meet carbon reduction goals in Europe but worldwide too, alarge number of renewable distributed energy resources (DER) still need tobe deployed.
Aiming at mobilizing private capital, several plans havebeen developed to put end-customers at the heart of the energy transition,hoping to accelerate the adoption of green energy by increasing itsattractiveness and profitability.
Some of the proposed models include thecreation of local energy markets where households can sell their energy totheir neighbors at a higher price than what the government would be willingto pay (but lower than what other customers normally pay), sharedinvestment models in which consumers own a carbon-free power plant such asa wind turbine or a solar farm and they obtain dividends from itsproduction to collective auto-consumption models in which several familiesare ‘hidden’ behind the same smart meter, allowing them to optimizetheir aggregated consumption profile and therefore maximizing the value oftheir DER.

One of the main objectives of the thesis is to understandthese different incentives as they will play a crucial role in tacklingclimate change if correctly implemented. To do so, we design a frameworkfor ‘local energy trading’ that encompasses a large number ofincentives.
In the context of local energy trading, we study theinteractions of prosumers (consumers with generation capabilities) locatedin the same Low Voltage network, possibly behind the same feeder. Theseprosumers will still be connected to the main power grid and they will havethe option, as they do today, to buy and sell to/from their utilitycompany at a fixed price (a flat rate or a Time-of-Use, for example). Forthese agents to fully benefit from the advantages of local energy trading,we shall assume that they own appliances (such as batteries) that, withoutchanging their perceived energy demand, can enable them to change theirnet energy demand as seen from outside their homes. Modeling prosumers asrational utility maximizers, they will schedule their battery to decreasethe cost associated with their net energy demand (as their perceived demandremains unchanged).

In the first part of the thesis, we investigatecompetitive models in which prosumers sell their surplus to their neighborsvia a local energy market. We analyze different strategies that playerscould use to participate in these markets and their impact on the normaloperation of the power grid and the Distribution System Operator. In thisregard, it is shown that sequential markets can pose a problem to thesystem and a new market mechanism that exploits domain knowledge isproposed to increase the efficiency of the local trades.

In the secondpart of the thesis, we delve into incentives that can be implementedthrough cooperation. In this regard, we use cooperative game theory tomodel the shared investment into energy storage and photovoltaic panels(PV) by a group of prosumers. For the studied model we show that a stablesolution (in the core of the game) exists in which all participantscooperate and we provide an efficient algorithm to find it. Furthermore,we also show that cooperation is stable for participants that already ownbatteries and PVs but prefer to operate them in coordination to increasetheir value, effectively implementing collectiveauto-consumption.
Finally, we demonstrate how to integrate both models:the shared investment and the cooperative control of existing resourcesinto a single cooperative framework which also enjoys the existence ofstable outcomes. For this later model, we propose to decouple the returnover investments (ROI) obtained between the ROI produced by the investmentin hardware and the ROI obtained by cooperation itself. By doing so, wecan offer the former profit to external investors to raise the requiredcapital (although nothing forbids the member of the coalition tocontribute) and the latter to the actual consumers.

Here's the streaminglink to follow:https://telecom-paris.zoom.us/j/99499019699?pwd=[REDACTED]

- ID de réunion : 994 9901 9699
- Code secret : [REDACTED]

Thesis defense "Random walk on simplicial complexes"
2020-12-10 14:00 - 17:00
The notion of Laplacian of a graph can be generalized tosimplicial complexes and hypergraphs. This notion contains information onthe topology of these structures. Even for a graph, the consideration ofassociated simplicial complexes can provide information on its shape.Whereas the Laplacian of a graph has a simple probabilistic interpretationas the generator of a continuous time Markov chain on the graph, thingsare not so direct when considering simplicial complexes. In the first partof this thesis, we define a new Markov chain on simplicial complexes. Fora given degree k of simplices, the state space is not the k-simplices asin previous papers about this subject but rather the set of k-chains ork-cochains. This new framework is the natural generalization on thecanonical Markov chains on graphs. We show that the generator of our Markovchain is related to the upper Laplacian defined in the context of algebraictopology for discrete structure. We establish several key properties ofthis new process. We show that when the simplicial complexes under scrutinyare a sequence of ever refining triangulation of the flat torus, theMarkov chains tend to a differential form valued continuousprocess.

In the second part of this thesis, we explore someapplications of the random walk, i.e., random walk based hole detectionand simplicial complexes kernels. For the random walk based holedetection, we introduce an algorithm to make simulations carried for thecycle-valued random walk (k = 1) on a simplicial complex with holes. Sincethe state space of the cycle-valued random walk consists of all the statesin the same homology group, the paths with minimal lengths are supposed tobe the holes of the simplicial complex, which is the idea of thealgorithm. In the case where we do not know the boundary of the simplicialcomplex, we need to find the initial state which is in the same homologygroup as the holes and has an integer value. Thus we calculate the initialstates and propose another algorithm to make simulations of integerweighted random walk. Simulation results show that we can always detect theholes of simplicial complexes with boundary (initial state) known, andapproximately with initial state unknown. For the simplicialcomplexes kernels, we extend the definition of random walk based graphkernels in order to measure the similarity between two simplicialcomplexes. The definition is based on this idea: given a pair of simplicialcomplexes, we perform our random walks on both, and count the number ofmatching walks. The more matching walks, the more similar these twosimplicial complexes are. In order to count the number of matching walks,we perform a random walk on the direct product simplicial complex of thesetwo simplicial complexes. We compute the probability of the random walkwhose length is k, and sum them for all k. The result is the kernel ofthese two simplicial complexes. In order to reduce computationalcomplexity, we rewrite the sum formula to the inverse of a matrix, anduse conjugate gradient methods instead of direct computation. Simulationresults show that graph kernels are related to the number of vertices andtheir connectivity, while simplicial complexes kernels put emphasis onhomology properties.

Here's the streaminglink:

https://telecom-paris.zoom.us/j/99001968945pwd=[REDACTED]
ID de réunion : 990 0196 8945
Code secret : [REDACTED]

"On the deployability of Augmented Reality Using Embedded EdgeDevices"
2020-12-09 14:00 - 15:00
Edge Computing exploits computational capabilities deployedat the very edge of the network to support applications with low latencyrequirements. Such capabilities can reside in small embedded devices thatintegrate dedicated hardware -- e.g., a GPU -- in a low cost package. Butthese devices have limited computing capabilities compared to standardserver grade equipment.
When deploying an Edge Computing basedapplication, understanding whether the available hardware can meet targetrequirements is key in meeting the expected performance.

In thispaper, we study the feasibility of deploying Augmented Realityapplications using Embedded Edge Devices (EEDs). We compare such deploymentapproach to one exploiting a standard dedicated server grade machine.Starting from an empirical evaluation of the capabilities of thesedevices, we propose a simple theoretical model to compare the performanceof the two approaches. We
then validate such model with NS-3 simulationsand study their feasibility. Our results show that there is no one-fits-allsolution. If we need to deploy high responsiveness applications, we need acentralized server grade architecture and we can in any case only supportvery few users. The centralized architecture fails to serve a larger numberof users, even when low to mid responsiveness is required. In this case,we need to resort instead to a distributed deployment based onEEDs.

Authors: Ayoub BEN AMEUR, Andrea ARALDO, FrancescoBRONZINO

Voting in Networks
2020-12-09 11:00 - 12:00
In this talk, we are investigating a selection of problemsrelated to the process of voting on a (social) network. Among otherproblems, I am going to present the notion of liquid democracy and how itcan be used on a network to elect a representative and approve/disapprovepropositions.

Slides

Thesis defense "Speed of convergence of diffusion approximations"
2020-12-08 14:00 - 17:00
In many fields of interest, Markov processes are a primarymodelisation tool for random processes. Unfortunately it is often necessaryto use very large or even infinite dimension state spaces, making theexact analysis of the various characteristics of interest (stability,stationary law, hitting times of certain domains, etc.) of the processdifficult or even impossible . For quite a time, thanks in particular tomartingale theory, it has been possible to make use of approximations bybrownian diffusions. This enables an approximate analysis of the initialproblem.
The main drawback of this approach is that it does not measurethe error made in this approximation. The purpose is to dévelop a theoryof error calculation for diffusion approximations .
For some time, thedevelopement of the Stein-Malliavin method has enabled to get someprecision over speed of convergence in classical theorems such as theDonsker theorem (functionnal convergence of a random walk towardsthe Brownian motion) or in the generalisation of the BinomialPoisson approximation path by path.
In this work we intend to extend thedevelopment of this theory for Markovian processes such as those than canbe found in queueing theory, in epidemiology or in other fields ofapplication.
Starting from the representation of Markov processes asPoisson measures, we extend the method developped by Laurent Decreusefondand Laure Coutin to assess the speed of convergence in diffusionapproximations . To do so, we extend the Stein-Malliavin method to vectorsof processes rather than a single process. The limit is a gaussianprocess changed in time. The Stein Malliavin method being mainly developpedto calculate convergence towards the standard Brownian motion, itis adapted to the problem of convergence towards a time changend processusing linear approximation methods. We therefore make use of Gaussiananalysis to assess the dependency between the various time periods and tofunctionnal analysis to elect the right probabilistic spaces.
Here's thestreaminglink:
https://telecom-paris.zoom.us/j/93338351493?pwd=[REDACTED]

ID de réunion : 933 3835 1493
Codesecret : 226860

Thesis defense "Contributions to the representation of multivariatetime series and graphs"
2020-12-07 14:00 - 17:00
Machine learning (ML) algorithms are designed to learn modelsthat have the ability to take decisions or make predictions from data, ina large panel of tasks like classification of images or monitoring ofmechanical systems. In general, the learned models are statisticalapproximations of the true/optimal unknown decision models. The efficiencyof a learning algorithm depends on an equilibrium between model richness,complexity of the data distribution and complexity of the task to solvefrom data. Nevertheless, for computational convenience, the statisticaldecision models often adopt simplifying assumptions about the data (e.g.linear separability, independence of the observed variables, etc.).However, when data distribution is complex (e.g. high-dimensional withnonlinear interactions between observed variables), the simplifyingassumptions can be counterproductive. In this situation, a solution is tofeed the model with an alternative representation of the data. Theobjective of data representation is to separate the relevant informationwith respect to the task to solve from the noise, in particular if therelevant information is hidden (latent), in order to help the statisticalmodel. Until recently and the rise of modern ML, many standardrepresentations consisted in an expert-based handcrafted preprocessing ofdata. Recently, a branch of ML called deep learning (DL) completelyshifted the paradigm. DL uses neural networks (NNs), a family of powerfulparametric functions, as learning data representation pipelines. Theserecent advances outperformed most of the handcrafted data in manydomains.

In this thesis, we are interested in learning representationsof multivariate time series (MTS) and graphs. MTS and graphs are particularobjects that do not directly match standard requirements of ML algorithms.They can have variable size and non-trivial alignment, such that comparingtwo MTS or two graphs with standard metrics is generally not relevant.Hence, particular representations are required for their analysis using MLapproaches. The contributions of this thesis consist of practical andtheoretical results presenting new MTS and graphs representation learningframeworks.

Two MTS representation learning frameworks are dedicated tothe ageing detection of mechanical systems. First, we propose amodel-based MTS representation learning framework called Sequence-to-graph(Seq2Graph). Seq2Graph assumes that the data we observe has been generatedby a model whose graphical representation is a causality graph. It thenrepresents, using an appropriate neural network, the sample on thisgraph. From this representation, when it is appropriate, we can findinteresting information about the state of the studied mechanical system.Second, we propose a generic trend detection method called ContrastiveTrend Estimation (CTE). CTE learns to classify pairs of samples withrespect to the monotony of the trend between them. We show that using thismethod, under few assumptions, we identify the true state underlying thestudied mechanical system, up-to monotone scalar transform.

Two graphrepresentation learning frameworks are dedicated to the classification ofgraphs. First, we propose to see graphs as sequences of nodes and create aframework based on recurrent neural networks to represent and classifythem. Second, we analyze a simple baseline feature for graphclassification: the Laplacian spectrum. We show that this feature matchesminimal requirements to classify graphs when all the meaningful informationis contained in the structure of the graphs.

Here's the streaming link:https://safran-group.webex.com/safran-group-fr/j.php?MTID=mfda124766b7a93fc255f3da5a14ab4ec

Thesis defense "Transport of critical services over unlicensedspectrum in 5G networks"
2020-12-02 16:00 - 19:00
Critical services in 5G networks, denoted by Ultra-ReliableLow-Latency Communication (URLLC), allow the existence of many promisingapplications such as factory automation, remote surgery and autonomousvehicles. However, URLLC has unprecedented stringent requirements in termsof reliability and latency, on the order of 99,999% and 1ms,respectively.
One of the most important aspects of URLLC transport is thetime-frequency trade-off, where restrictions in the time domain require alarge frequency bandwidth to guarantee the target reliability. Usinglicensed spectrum, as in previous generations, entails a huge cost foroperators who buy, at very high price, the license to use certainchannels. The cost and scarcity of licensed spectrum calls then for theusage of unlicensed spectrum that is cheaper and available at higherquantities.
In this thesis, we study the transport of critical servicesover unlicensed spectrum. We design new medium access schemes for URLLC tomeet its requirements, by using additional licensed resources or byincreasing the transmission power of URLLC while competing with otherservices.
Streaming link to attend: https://youtu.be/SrLAEyn_R6Y

Pyinstaller / Vis.js Network
2020-12-02 10:45 - 12:15
Two independent tools will be presented for thissession.

Pyinstaller is a tool that converts Python code in standaloneexecutable. The goal is not to speed up things, but to have portable codeto run on a computer without installing additional software.

Vis.jsnetwork is the javascript library that was used to display the Lincs graph(https://www.lincs.fr/research/lincs-graph/). It's a relatively simple wayto display a json graph.

Talk by a member of LINCS Scientific Committee "On the Use of SmallSolar Panels and Small Batteries to Reduce the RAN Carbon Footprint"
2020-11-25 14:00 - 15:00 | Teams + LINCS Seminar Rooms, 23 avenue d'Italie, Paris, 75013,France
The limited power requirements of new generations of basestations make the use of renewable energy sources, solar in particular,extremely attractive for mobile network operators. Exploiting solar energyimplies a reduction of the network operation cost as well as of the carbonfootprint of radio access networks. However, previous research worksindicate that the area of the solar panels that are necessary to power astandard macro base station (BS) is large, making the solar paneldeployment problematic, especially within urban areas. In this paper weuse a modeling approach based on Markov reward processes to investigate thepossibility of combining a connection to the power grid with small areasolar panels and small batteries to run a macro base station. By so doing,it is possible to exploit a significant fraction of renewable energy to runa radio access network, while also reducing the cost incurred by thenetwork operator to power its base stations. We assume that energy is drawnfrom the power grid only when needed to keep the BS operational, or duringthe night, which corresponds to the period with lowest electricity price.The proposed energy management policies have advantages in terms of bothcost and carbon footprint. Our results show that solar panels of the orderof 1-2 kW peak, i.e., with a surface of about 5-10 square meters,combined with limited capacity energy storage (of the order of 1-5 kWh,corresponding to about 1-2 car batteries) and a smart energy managementpolicy, can lead to an effective exploitation of renewableenergy.
Bio
Marco Ajmone Marsan is full professor at theElectronics and Telecommunications Department of the Politecnico di Torinoin Italy, and part-time research professor at IMDEA Networks Institute inLeganes, Spain. He obtained degrees in EE from the Politecnico di Torinoand the University of California, Los Angeles (UCLA). He received ahonorary doctoral degree from the Budapest University of Technology andEconomics. Since 1974 he has been at Politecnico di Torino, in thedifferent roles of an academic career, with an interruption from 1987 to1990, when he was a full professor at the Computer Science Department ofthe University of Milan. Marco Ajmone Marsan has been doing research in thefields of digital transmission, distributed systems and networking. He wasa member of the editorial board and of the steering committee of the“ACM/IEEE Transactions on Networking”. He is a member of the editorialboards of the journals “Computer Networks”and “PerformanceEvaluation”of Elsevier, and of the “ACM Transactions on Modeling andPerformance Evaluation of Computer Systems”. He served in the organizingcommittee of several leading networking conferences, and he was generalchair of INFOCOM 2013. Marco Ajmone Marsan is a Fellow of the IEEE, amember of the Academy of Sciences of Torino, and a member of AcademiaEuropaea.

An introduction to mean field theory
2020-11-25 11:00 - 12:00
When working with interacting particle systems, mean-fieldmodels provide a link between models on a microscopic scale describing thebehavior of the system and simplified models on a macroscopic scaledescribing the statistical distribution of the particles. In this talk, wewill introduce and discuss some main theoretical concepts associated withmean field models, in particular Sznitman's propagation of chaos resultsand coupling techniques.

Slides

Mini Workshop I.A. appliquée
2020-11-20 09:30 - 12:30

Mini Workshop 5G et ses application (incluant V2X)
2020-11-19 09:30 - 12:30

Talk by a member of LINCS Scientific Committee "Distributingservice execution"
2020-11-18 14:00 - 15:00 | Teams + LINCS Seminar Rooms, 23 avenue d'Italie, Paris, 75013,France
Services often consists of independent components that can beexecuted independently (so-called microservices) and they often deal withvery large user populations. This setup presents various opportunities,e.g., reducing latency or overheads, by executing service instances closeto the user. This talk will look at several algorithmic and engineeringproblems in this context, for both backhaul networks and wirednetworks.
Bio
Holger Karl received his PhD in 1999 from HumboldtUniversity Berlin; afterwards, he joined Technical University Berlin.Since 2004, he is Professor for Computer Networks at Paderborn University.His main research interests are wireless communication and architecturesfor the Future Internet. Recently, he has focused mostly on SDN andNFV.

Teams link to the seminar: https://teams.microsoft.com/l/meetup-join/19%3a9d61b1d307fe451ebb27c5e6d70b244a%40thread.tacv2/1605540304584?context=%7b%22Tid%22%3a%225d471751-9675-428d-917b-70f44f9630b0%22%2c%22Oid%22%3a%22d64605ca-67ce-4b7d-ab88-bc16f4e176ec%22%7d

SimPy Package tutorial
2020-11-18 10:45 - 12:15
SimPy is a python package for discrete event simulations basedon python’s standard generators. This tutorial will demonstrate how youcan use SimPy to implement event-discrete simulations and which featuresSimPy offers to help you doing that. We will also go through an example forqueueing network systems.

Mini Workshop BlockChain
2020-11-16 09:30 - 12:30

Mini Workshop IoT
2020-11-13 09:30 - 12:30

Fluid limits : a useful tool to study the stability of queuingnetworks
2020-11-04 10:45 - 12:15
Introduced by Rybko and Stolyar in 1992, fluid-scaling andfluid limits offer a systematic way to study the stability or instabilityof queuing networks over a vast range of queuing disciplines and queuingnetworks. In this talk, I am going to present some of the main resultsassociated with fluid limits and illustrate how we can use them with asimple M/G/1 queuing network.

Slides

What problems does cloud solve? Non BS introduction by a formeracademic.
2020-10-28 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Cloud computing in addition to being a large industry can alsoseem daunting to understand. In this introduction, we will present in avery didactic manner what problems cloud computing is solving. In additionto a general introduction, I will also present several tools that can beapplied in the context of the everyday work of a scientist / PhD student.This course can help you get a better grasp of the different products andproblems tackled by cloud computing and how is it relevant for you. Bringall your infrastructure questions with you! If you have questions about howlarge scale cloud infrastructure work this is the time to have themsolved.

All-day Workshop LINCS-SystemX
2020-10-23 09:00 - 17:00
A one-day collaborative workshop gathering researchers fromLINCS and engineers from SystemX who will share their ongoing research toconsolidate joint R&D activities, to create synergies in theframework of new inspiring projects on networks, blockchain, V2X, cloudand AI.
Program
09h00-09h30: Welcome. Introduction by LINCS and SystemXmanagements

Digital Security and Blockchain:

09h30-09h50: R&D topics on Blockchain. Maria Potop-Butucaru (Lincs)
09h50-10h10: Blockchain@SystemX. Khalifa Toumi (SystemX)
10h10-10h30:Cryptography@SystemX. Kalpana Singh (SystemX)
10h30-10h50: Q&A andcollaborations

Applied AI and IoT:

11h00-11h20:Scikit-Network@Lincs. Thomas Bonald (Lincs)
11h20-12h00: Applied AI andIoT@Lincs. Ludovic Noirie (Lincs)
12h00-12h20: AI@SystemX. Hatem Hajri(SystemX)
12h20-12h45: Q&A and collaborations

12h45-14h00:Lunch break

V2X & 5G:

14h00- 14h30: Presentation of theproject 5G-OpenRoad. Joëlle Gauthier (Systematic)
14h30-14h45: Q&Aand collaborations on 5G-OpenRoad
14h45-15h30: V2X@Lincs and 5G@LINCS.François Baccelli (Lincs)
15h30- 16h10: V2X@SystemX and 5G@SystemX.Ines Benjemaa and Francesca Bassi (SystemX)
16h10-16h30: Q&A andcollaborations

16h30-17h00: Smart Grid @LINCS. DanielKofman (Lincs)

17h00-17:15: Wrap-up and collaborations

Conclusionof workshop n° 1

Seminar Presentation by a new LINCS associate member "Multi-TenantResource Allocation at the Network Edge"
2020-10-21 14:00 - 15:00
Edge Computing (EC) is a network paradigm in whichcomputational resources, e.g., CPU, memory, are distributed in theaccess networks, close to the final users. Network elements at the edge,e.g., base stations, road side units, access points, become intelligentand can be used by multiple third party Service Providers (SPs) to run (apart of) their application at the edge. Such applications can beheterogeneous, ranging from video-streaming to augmented reality, toservices needed to autonomous driving.

In order to enable this, theNetwork Operator (NO), owning the physical infrastructure, needs tovirtualize edge resources and allocate them to the SPs, which representthe tenants.

Unlike Cloud Computing, EC resources are scarce andcontention arises between SPs. Therefore, the NO needs to carefullyallocate virtual resources among them, in order to increase its utility,e.g., reduction in bandwidth consumption, user QoE. Such allocation ischallenging, since SPs must be kept isolated, i.e., data and computationof each SP must be inaccessible to other SPs and to the NO. In otherwords, SPs are black boxes for the NO, which still must be able toproperly allocate resources among them.

A. Araldo will present somesolutions to the problem of Multi-Tenant Resource Allocation in EC,described above, based on two approaches: explicit information exchangebetween SPs and NO or data-driven allocation algorithms, as reinforcementlearning and stochastic perturbation.

Finally, A. Araldo will presentsome preliminary results related to the performance of large scaleaugmented reality applications implemented via a distributed system of EdgeAI boards, which are small and cheap embedded devices equipped with GPU,able to run deep neural networks.

Seminar Presentation by a new LINCS associate member "PerformanceBenchmarking of State-of-the-Art Software Switches for NFV"
2020-10-14 14:00 - 15:00
With the goal of replacing proprietary hardware appliances withVirtual Network Functions (VNFs) implemented in software, Network FunctionVirtualization (NFV) has gained popularity in the past few years. Softwareswitches are widely employed to route traffic between VNFs and physicalNetwork Interface Cards (NICs). It is thus of paramount importance tocompare the performance of different switch designs and architectures. Inthis paper, we propose a methodology to compare fairly and comprehensivelythe performance of software switches. We first explore the design spaces of7 state-of-the-art software switches and then compare their performanceunder four representative test scenarios. Each scenario corresponds to aspecific case of routing NFV traffic between NICs and/or VNFs. In ourexperiments, we evaluate the throughput and latency between VNFs in two ofthe most popular virtualization environments, namely virtual machines(VMs) and containers. Our experimental results show that no single softwareswitch prevails in all scenarios. It is, therefore, crucial to choose themost suitable solution for the given use case. At the same time, thepresented results and analysis provide a more in-depth insight into thedesign tradeoffs and identify potential performance bottlenecks that couldinspire new designs.

Iterators: A Simple Tool to Browse Objects in Python
2020-10-14 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Iterators are simple tools to browse objects in Python. Theydefine a unique interface called iteration protocol, that enables todecorrelate the objects that contain the data from the object that iterateson data. All standard Python functions to browse objects like 'for','while', etc. are based on iterators. In this presentation, I willformally present iterators, and in particular explain why they areinteresting and useful. I will also introduce useful concepts and modulesrelated to iterators: list comprehension, generative expressions andfunctions, itertools.

Thesis defense "FabLabs, a global and growing network ofcollaborative organizations: an analysis of intra and inter-organizationalcoordination modes"
2020-10-12 14:00 - 17:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
This thesis contributes to the understanding of theorganizational phenomenon of FabLabs, which aims to democratize personaldigital manufacturing and promote knowledge sharing. To this end, weinvestigate the modes of coordination that have emerged in this globalnetwork of local collaborative organizations, whose number has grownrapidly and continuously since 2005. Our work addresses both theintra-organizational level (a FabLab as an organization) and theinter-organizational level (the FabLab network as a whole).
It builds onthe literature relative to the modes of coordination in communities ofknowledge, and in particular communities of practice, in the context ofcollective management of common goods as well as ininter-organizational networks. We have adopted a comprehensive approachbased on a participatory observation posture. Our work is based on threecase studies (one on the FabLab Artilect and two on the Global FabLabNetwork) and sheds light on the modes of coordination within andbetween FabLabs, with two main contributions.
We show that theprinciples shared in a collaborative network can be structuring fororganizational configurations that are otherwise diverse. Also, wehighlight that in the observed context, two processes of structuralfragmentation appear at both the intra and inter-organizational levels. Thefirst process operates according to a core-periphery logic. The secondprocess results in the formation of thematic and, in some cases,geographical proximity sub-groups. Our work suggests that these processescan help preserve collaborative dynamics despite the growth of theorganization when "bridge members" are each active in both the core and oneof the subgroups.

To participate in visio-conference
Meetinglinc : https://telecom-paris.zoom.us/j/93062897097?pwd=[REDACTED]
ID: 930 6289 7097
Pw : [REDACTED]

Thesis Defense "Governing the Commons in Blockchains"
2020-10-08 15:00 - 18:00
Blockchains are one of most appealing technologies over thelast years,
both for scientists and for the general public. Blockchainsare
distributed ledgers that aim to offer transparency, integrity andmany
more advantages over their centralised counterparts. Blockchainswere
“revealed” and became popular thanks to the creation and raise ofthe
cryptocurrency Bitcoin. Over the years, blockchain technologiesbecome
more and more popular with an exceptional peak in 2017. Blockchainsare
becoming mainstream technologies, as there is an observatoryfor
blockchains established by the European Commission, blockchain forumsin
many countries, blockchain start-ups are flourishing,scientific
conferences are discussing the topic, and even somescientific
conferences are now specifically dedicated to the technology,etc.
The blockchain technology promises, thanks to its integrityand
transparency properties to be useful and interesting in variousdomains,
and not only for financial systems. However, many questions anddoubts
float around it. Is it environmentally viable? Is the technologyeven
ensuring its promises? Can they be used in real life settings,etc.
In this thesis, using the lens of distributed systems, we studyand
defined the properties of committee-based blockchains andtheir
fairness; that definition allows formalising and helping correctone of
the most used blockchain of that class. Furthermore, adding lensesfrom
game theory, we propose a methodology to analyse the rationalbehaviours
of participants in a blockchains system. Using thatmethodology, we
show, under different mechanism of rewards, thenecessary conditions
needed to ensure the blockchainproperties.

Participer à la réunionZoom
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ID de réunion : 818 1955 3516
Code secret :[REDACTED]/10/08

"CoronaSurveys: Using Indirect Reporting to Estimate the Incidenceof Epidemics"
2020-10-07 14:00 - 15:00
The world is suffering from a pandemic called COVID-19, causedby the SARS-CoV-2 virus. National governments have problems evaluating thereach of the epidemic, due to having limited resources and tests at theirdisposal. This problem is especially acute in low and middle-incomecountries (LMICs). Hence, any simple, cheap and flexible means ofevaluating the incidence and evolution of the epidemic in a givencountry with a reasonable level of accuracy is useful.
In this talk, Iwill present the CoronaSurveys project (https://coronasurveys.org/).CoronaSurveys uses a technique based on (anonymous) surveys in whichparticipants report on the health status of their contacts. This indirectreporting technique, known in the literature as network scale-upmethod, preserves the privacy of the participants and their contacts, andcollects information from a larger fraction of the population (as comparedto individual surveys). The CoronaSurveys project has been collectingreports for the COVID-19 pandemic since March 2020. Results obtainedby CoronaSurveys show the power and flexibility of the approach,suggesting that it could be an inexpensive and powerful tool to track theCOVID-19 pandemic. This makes it especially interesting and useful forLMICs.
Bio
Dr. Antonio Fernández Anta is a Research Professor at IMDEANetworks.
Previously he was a Full Professor at the Universidad Rey JuanCarlos (URJC) and was on the Faculty of the Universidad Politécnicade Madrid (UPM), where he received an award for his researchproductivity. He was a postdoc at MIT from 1995 to 1997, and spentsabbatical years at Bell Labs Murray Hill and MIT Media Lab. He hasbeen awarded the Premio Nacional de Informática "Aritmel" in 2019and is a Mercator Fellow of the SFB MAKI in Germany since 2018. Hehas more than 25 years of research experience, and more than 200scientific publications. He was the Chair of the Steering Committeeof DISC and has served in the TPC of numerous conferences andworkshops. He received his M.Sc. and Ph.D. from the University of SWLouisiana in 1992 and 1994, respectively. He completed hisundergraduate studies at the UPM, having received awards at theuniversity and national level for his academic performance. He is aSenior Member of ACM and IEEE.

Zap Stochastic Approximation and Reinforcement Learning
2020-10-07 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Many reinforcement learning problems can be seen from the pointof view of stochastic approximation. Unfortunately, classic stochasticapproximation algorithms, such as Robbins-Monro, may have an infiniteasymptotic variance. The class of "zap" algorithms aim at solving thatproblem. We then examine the application of zap algorithms to reinforcementlearning, with the example of zap Q-learning.

Slides

Seminar Presentation by a new LINCS associate member "On theinference of high-speed networks’ behavior via Machine Learning"
2020-09-23 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Network Function Virtualization (NFV) is a novel trend in ITnetworks which advocates replacing hardware middleboxes with equivalentpieces of code executed on general-purpose servers.
This on-going processof network softwarization can help network operators to reduce theoperational and management costs of their networkinfrastructures.
Alongside the benefits from the operator's perspective,new strategies to provide the network's resources to users arearising.
Following the principle of "everything as a service", multipletenants can access the required resources -- typically CPUs, NICs, or RAM-- according to a Service-Level Agreement (SLA). This provides theopportunity for network managers to continuously monitor the network'sbehavior, collect a huge amount of network data that can be used, inconjunction with machine learning algorithms, to solve several problems(from resource allocation, to intrusiondetection/prevention).
Unfortunately, there is no free lunch, andcurrent machine learning techniques require a huge amount of computationalresources: in the case of softwarized networks, allocating thecomputational resources requires a tradeoff between the networkcommunication's capabilities (i.e., the "speed") and the quality of the MLalgorithm (i.e., the "intelligence").
In this talk, I will present anetwork inference problem, which consists in identifying the globalbehavior of a high-level network function executed on top of a commodityserver, by accessing low-level information represented by the server's CPUutilization.
The focus of this presentation will be on the performance(accuracy) of the ML algorithm utilized to make the prediction, and on theimpact of such an algorithm on the overall network performance.
I willfinally identify the most promising approaches to be able to deploy machinelearning algorithms together with real-world high-speed networkapplications.

Dictionaries
2020-09-23 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
In this second session about collections, I will talk aboutdictionaries and their main subclasses: OrderedDict, defaultdict, Counterand ChainMap.

Thesis defense: "Algorithmic and Software Contributions to GraphMining"
2020-09-22 09:00 - 13:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Since the introduction of Google’s Page Rank method for Websearches in the late 1990s, graph algorithms have been part of our dailylives. In the mid 2000s, the arrival of social networks has amplified thisphenomenon, creating new use-cases for these algorithms. Relationshipsbetween entities can be of multiple types: user-user symmetricrelationships for Facebook or LinkedIn, follower-followee asymmetric onesfor Twitter or even user-content bipartite ones for Netflix, Deezer orAmazon. They all come with their own challenges and the applications arenumerous: centrality calculus for influence measurement, node clusteringfor knowledge discovery, node classification for recommendation orembedding for link prediction, to name a few. In the meantime, thecontext in which graph algorithms are applied has rapidly become moreconstrained. On the one hand, the increasing size of the datasets withmillions of entities, and sometimes billions of relationships, bounds theasymptotic complexity of the algorithms for industrial applications. On theother hand, as these algorithms affect our daily lives, there is agrowing demand for explanability and fairness in the domain of artificialintelligence in general. Graph mining is no exception. For example, theEuropean Union has published a set of ethics guidelines for trustworthy AI.This calls for further analysis of the current models and even new ones.This thesis provides specific answers via a novel analysis of not onlystandard, but also extensions, variants, and original graph algorithms.Scalability is taken into account every step of the way. Following what theScikit-learn project does for standard machine learning, we deem itimportant to make these algorithms available to as many people as possibleand participate in graph mining popularization. Therefore, we havedeveloped an open-source software, Scikit-network, which implements anddocuments the algorithms in a simple and efficient way. With this tool, wecover several areas of graph mining such as graph embedding, clustering,and semi-supervised node classification.

Participer à la réunionZoom
https://telecom-paris.zoom.us/j/99270581285?pwd=[REDACTED]

ID de réunion : 992 7058 1285
Code secret : [REDACTED]

Seminar presentation "Nash equilibrium structure of a class ofspatial competition games"
2020-09-16 14:00 - 15:00
We study an N-player game where a pure action of each player isto
select a non-negative function on a Polish space supporting afinite
diffuse measure, subject to a finite constraint on the integral ofthe
function. This function is used to define the intensity of aPoisson
point process on the Polish space. The processes are independentover
the players, and the value to a player is the measure of the unionof
its open Voronoi cells in the superposition point process.Under
randomized strategies, the process of points of a player is thus aCox
process, and the nature of competition between the players is akinto
that in Hotelling competition games. We characterize when such agame
admits Nash equilibria and prove that when a Nash equilibriumexists, it
is unique and comprised of pure strategies that areproportional in the
same proportions as the total intensities. We giveexamples of such
games where Nash equilibria do not exist.

This is ajoint work with Venkat Anantharam, UC Berkeley, EECS.

Collections in Python
2020-09-16 11:00 - 12:00
I will talk about collections in Python.

Sets: set,frozenset.
Sequences: tuple, named tuples, list, deque (we will justmention str and bytes).
Mappings: dict, defaultdict, OrderedDict,Counter, ChainMap.

I will assume at least a basic knowledge of set,tuple, list and dict.

Thesis defense : "Malliavin calculus and Dirichlet structures forindependent random variables"
2020-09-14 14:00 - 17:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
In a pioneer work from 1976, Paul Malliavin lays thefoundations for an infinite-dimensional stochastic calculus of variations.Initially developed on the Wiener space, the Malliavin calculus was laterextended to other families of processes such as Poisson, Rademacher orLévy processes. It seems possible to identify a terminology common to allthese formalisms; this lies on the notions of Malliavin operators(gradient, divergence, Laplacian / Ornstein-Uhlenbeck operator) and thefundamental relation between the gradient operator and the divergence(defined as the adjoint of the gradient): the integration by partsformula.
We develop in this thesis a Malliavin calculus for two classes ofdiscrete processes: the sequences of independent random variables (notnecessarily identically distributed) and the compound geometric processes.These constructions were motivated by several applications; two of themwill be developed during the presentation.
The first one deals with theestimation of distances between two probability laws using Stein's method.One of the step of this method is performed using advantageously Malliavinintegration by parts formula. In order to use it to get convergence resultsfor functionals of independent random variables, we equip any countableproduct of probability spaces with a discrete Dirichlet-Malliavin structurebuilt on a family of Malliavin operators (gradient discrete, divergence,operator number), an integration by parts formula, and the forms ofDirichlet naturally induced in this context. In this framework, weestablish a Normal and Gamma approximation criteria by functionals ofindependent random variables in terms of Malliavin operators.
Themotivation for the second work was to use our tools to deal with portfoliomanagement problems in a discrete financial market model. It turned out tobe impossible to state an hedging formula within our precedent formalism.We replace thus the initial model with a ternary model, underlied by acompound geometric process for which we develop a pseudo-decompositionchaotic and define Malliavin operators. By plugging this formalism toportfolio optimization, we show that the minimizing quadratic riskstrategy can be expressed in terms of the newly introduced Malliavinoperators.

Zoomlink:

[ https://telecom-paris.zoom.us/j/93395747795?pwd=[REDACTED] | https://telecom-paris.zoom.us/j/93395747795?pwd=[REDACTED] ]

ID de réunion : 9339574 7795
Code secret : [REDACTED]

Interns' talks: (1) Monitoring as a service for IoT networks and(2) Structured and interactive summarization
2020-09-09 14:00 - 15:00
Two interns from LINCS will present their works at this LINCSseminar:

1) Pooneh Mokariasl (Nokia Bell Labs / Sorbonne Université):Monitoring as a service for IoT networks

2) Mélanie Cambus (Nokia BellLabs / Université de Versailles): Structured and interactive summarization

Quantum Internet
2020-09-09 11:00 - 12:00
IRTF is the research part of the IETF, producing InternetDrafts and Requests For Comments on topics that are still in the researchphase. The Quantum Internet Research Group was proposed end of 2018 andofficially approved in March 2020 to work on the emerging quantumcommunication technologies in the Internet context. There are currently twoInternet Drafts that are working documents in QIRG:

Architectural Principles for a Quantum Internet;
Applications and UseCases for the Quantum Internet.

During this session of the NetworkTheory Working Group at LINCS, I will describe the content of these twoInternet Drafts. You will understand:

What QuantumInternet is: a distributed system to make entangled pairs of qubits betweenend-points of the network;
To what Quantum Internet is useful: toextend the distance of the currently available Quantum Key Distributionsystems (quantum cryptography) and to allow futuristic quantum clouds(distributed quantum computing).

Knowing quantum mechanicsby "popular science" only is enough to follow this session!

Slides:http://www.lincs.fr/wp-content/uploads/2020/09/20200909_Quantum_Internet_LN.pdf

Contact process on point processes, part II
2020-07-15 11:00 - 12:00
I will first review some results on the contact process ongraphs.
I will then describe ongoing research on this type of dynamics onrandom
point processes.
Two instances of point processes will bediscussed, static and with random
motion.

Warning: Sound quality isbad the first minute, but fine for the rest of the talk.

"Clean Code" from Robert Martin
2020-07-01 11:00 - 12:00
What is the difference between "good" and "bad" code? What gainis there to expect from turning to clean code? I know how to code and havegood notions of algorithmic (publication in computer algebra and teachingin master). But something was clearly missing, since my projects, afterreaching around 300 lines of code, would become heavy to develop et hardto evolve.

Following the advice of a coder friend, I read the book"Clean Code" from Robert Martin. My coding skill have since improved and,even more important, I find joy again into coding even for my longestprojects. In this short presentation, I will cover the first few chaptersof the book: code readability, single responsibility principle for classesand functions, comments, tests.

Models and Solutions of Strategic Resource Allocation Problems:Approximate Equilibrium and Online Learning in Blotto Games
2020-06-25 14:00 - 16:00
In this thesis, we investigate resource allocation games,broadly defined as resource allocation problems involving interactionsbetween competitive decision makers. We primarily focus on the ColonelBlotto game (CB game). In the CB game, two competitive players, eachhaving a fixed budget, simultaneously distribute their resources toward nbattlefields. Each player evaluates each battlefield with a certain value.In each battlefield, the player who has the higher allocation wins andgains the corresponding value. Each player's payoff is her aggregate gainsfrom all the battlefields.

First, we model several variants of the CBgame and their extensions as one-shot complete-information games andanalyze players' strategic behaviors. Our first main contribution is aclass of approximate equilibria in these games for which we prove that theapproximation error can be well-controlled. Second, we model resourceallocation games with combinatorial structures as online learning problemsto study situations involving sequential plays and incomplete information. We make a connection between these games and online shortest path problems(OSP). Our second main contribution is a set of novel regret-minimizationalgorithms for OSP under several feedback settings that provide significantimprovements in regret guarantees and running time in comparison withexisting solutions.

Contact process on point processes, part I
2020-06-24 11:00 - 12:00
I will first review some results on the contact process ongraphs.
I will then describe ongoing research on this type of dynamics onrandom
point processes.
Two instances of point processes will bediscussed, static and with random
motion.

Characterizing the Expressive Power of Invariant and EquivariantGraph Neural Networks
2020-06-17 14:00 - 15:00
Various classes of Graph Neural Networks (GNN) have beenproposed and shown to be successful in a wide range of applications withgraph structured data. In this work, we propose a theoretical frameworkable to compare the expressive power of these GNN architectures. Thecurrent universality theorems only apply to intractable classes of GNNs.Here, we prove the first approximation guarantees for practical GNNs,paving the way for a better understanding of their generalization. Ourtheoretical results are proved for invariant GNNs computing a graphembedding (permutation of the nodes of the input graph does not affect theoutput) and equivariant GNNs computing node embeddings (permutation of theinput permutes the output). We show that Folklore Graph Neural Networks(FGNN), which are tensor based GNNs augmented with matrix multiplicationare the most expressive architectures proposed so far for a given tensororder. We illustrate our results on the Quadratic Assignment Problem (aNP-Hard combinatorial problem) by showing that FGNNs are able to learn howto solve the problem, leading to much better average performances thanexisting algorithms (based on spectral, SDP or other GNNs architectures).On a practical side, we also implement masked tensors to handle batches ofgraphs of varying sizes.

This is a joint work with Waiss Azizian(ENS).

Use of Teams meetings for this seminar: contactludovic.noirie{AT}nokia-bell-labs{DOT}com to get the Teams link

Introduction to Pygame
2020-06-17 11:00 - 12:00
Pygame is a Python package that wraps the SDL library. SDL(Simple DirectMedia Layer) is a cross-platform development library writtenin C, designed to provide access to multimedia: 2D graphics, audio,keyboard, mouse and joystick. Pygame can be used to design games but notonly: anything that makes use of a graphical interface, sound, etc; andin particular, it can be used for demos. I will present and comment onseveral simple code examples that introduce the main modules of Pygame,dealing with display, images, sprites, text, events, time, sound,keyboard and mouse.

Github repo, with slides and code examples:https://github.com/francois-durand/pygame_presentation.

Direct link toslides.

Gismo: a Generic Information Search... with a Mind of its Own!
2020-06-10 14:00 - 15:00
Searching for documents is a task that everyone faces on aregular basis, especially when looking for a relevant Internet page, ane-mail, or a document on an Intranet. An effective search relies on aprecise and well-organized search engine.
The majority of currenttechniques combine a keyword search with structural information(ontologies, relationships between elements) in order to order thedocuments in a corpus by relevance.
In this talk, we present a new lightnavigation engine called Gismo (Generic Information Search with a Mind ofits Own). Gismo exploits only the textual content of documents and does notrequire ontology, metadata, or pre-learning. It is thus possible to useit on any corpus without making assumptions about the type of documents ortheir language. The model chosen and the algorithms used allow Gismo to beextremely fast even on large corpora. Finally, Gismo allows you to find,sort and organize documents by theme and relevance, making it a navigationengine and not a simple search engine.

Gismo is available as anopen-source Python module.

Presentation slides (PDF)

A Mathematical Theory of Communication: Discrete Noiseless Systems
2020-06-10 11:00 - 12:00
In 1948 Shannon published the article that defines moderninformation theory. For this reading group, we will present the first partof the article, which is concerned with discrete lossless systems like thetelegraph. We will present the way in which Shannon defines and gives theintuition of concepts like the capacity of a communication channel,entropy, the Markovian model of a language, and much more...

IoT Network Control and Management
2020-06-03 14:00 - 15:00
Internet of Things (IoT) devices are increasingly present inour lives. This plethora of devices creates a need to manage them easily,transparently and quickly from anywhere, especially when unskilled peopleare involved, as is the case in private IoT networks such as home, officeand corporate LANs. During this LINCS seminar conference, you will learnabout the research carried out in the Nokia Bell Labs on the control andmanagement of these private IoT networks. We have designed an SDN / cloudplatform to facilitate the use of IoT devices. We have developed a solutionbased on supervised machine learning to identify the types of connecteddevices. We are currently working on a generic and easy to use IoT networkmonitoring solution.

Use of Teams meetings for this seminar: contactludovic.noirie{AT}nokia-bell-labs{DOT}com to get the Teams link

Slides

Input, Output, and the Internet: Part II
2020-06-03 11:00 - 12:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Python offers a lot of tools to easily deal with local andInternet files. We will present a selection of these tools illustrated withnice examples.

This will be presented in two parts.

Part I: LocalFiles

pathlib: the pythonic way to manipulate files;
gzip /zipfile: compress transparently;
tempfile / io: no more mess toclean.

Part II: Internet

requests: retrieve Internet files;
BeautifulSoup: parse HTML like a charm;
Selenium: when everything elsefails.

Beam management in 5G
2020-05-27 15:00 - 16:00
Beam management is central in the operation of dense 5Gcellular networks. Focusing the energy radiated to mobile terminals (MTs)by increasing the number of beams per cell increases signal power anddecreases interference, and has hence the potential to bring majorimprovements on area spectral efficiency (ASE). This benefit, however,comes with unavoidable overheads that increase with the number of beams andthe MT speed. This paper proposes a first system-level stochastic geometrymodel encompassing major aspects of the beam management problem:frequencies, antennas, and propagation; physical layer, wirelesslinks, and coding; network geometry, interference, and resourcesharing; sensing, signaling, and mobility management. This model leadsto a simple analytical expression for the effective ASE that the typicaluser gets in this context. This in turn allows one to find, for a widevariety of 5G network scenarios including millimeter wave (mmWave) andsub-6 GHz, the number of beams per cell that offers the best globaltrade-off between these benefits and costs. We finally provide numericalresults that discuss the effects of different systemic trade-offs andperformances of mmWave and sub-6 GHz 5G deployments.

The talk will alsohighlight the interplay between pure and standardization-oriented researchand the lessons learned through the collaboration.

This is acollaborative work done at LINCS between Sanket Kalamkar and FrancoisBaccelli from Inria, and Fuad Abinader, Andrea Marcano and Luis GuilhermeUzeda Garcia from Nokia Bell Labs.

Support-vector networks
2020-05-27 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Cortes, C., Vapnik, V. Support-vector networks. Mach Learn20, 273–297 (1995). https://doi.org/10.1007/BF00994018 .

Abstract ofthe paper:

"The support-vector network is a new leaming machine fortwo-group classification problems. The machine conceptually implements thefollowing idea: input vectors are non-linearly mapped to a very high-dimension feature space. In this feature space a linear decision surface isconstructed. Special properties of the decision surface ensures highgeneralization ability of the learning machine. The idea behind thesupport-vector network was previously implemented for the restricted casewhere the training data can be separated without errors. We here extendthis result to non-separable training data. High generalization ability ofsupport-vector networks utilizing polynomial input transformations isdemonstrated. We also compare the performance of the support-vector networkto various classical learning algorithms that all took part in a benchmarkstudy of Optical Character Recognition."

Talk material available here:https://github.com/yokaiAG/DataNets-Course

Input, Output, and the Internet: Part I
2020-05-20 11:00 - 12:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France

Thesis Defense : Resource allocation and optimization for thenon-orthogonal multiple access
2020-03-12 14:00 - 16:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Non-orthogonal multiple access (NOMA) is a promising technologyto increase the spectral efficiency and enable massive connectivity infuture wireless networks. In contrast to orthogonal schemes, such asOFDMA, NOMA can serve multiple users on the same frequency and timeresource by superposing their signal in the power domain. One of the keychallenges for radio resource management (RRM) in NOMA systems is to solvethe joint subcarrier and power allocation (JSPA) problem.
In this thesis,we present a novel optimization framework to study a general class of JSPAproblems. This framework employs a generic objective function which can beused to represent the popular weighted sum-rate (WSR), proportionalfairness, harmonic mean and max-min fairness utilities. Our work alsointegrates various realistic constraints. We prove under this frameworkthat JSPA is NP-hard to solve in general. In addition, we study itscomputational complexity and approximability in various special cases, fordifferent objective functions and constraints.
In this framework, wefirst consider the WSR maximization problem subject to cellular powerconstraint. We propose three new algorithms: Opt-JSPA computes an optimalsolution with lower complexity than current optimal schemes in theliterature. It can be used as an optimal benchmark in simulations.However, its pseudo-polynomial time complexity remains impractical forreal-world systems with low latency requirements. To further reduce thecomplexity, we propose a fully polynomial-time approximation scheme calledƐ-JSPA, which allows tight trade-offs between performance guaranteeand complexity. To the best of our knowledge, Ɛ-JSPA is the firstpolynomial-time approximation scheme proposed for this problem. Finally,Grad-JSPA is a heuristic based on gradient descent. Numerical results showthat it achieves near-optimal WSR with much lower complexity than existingoptimal methods.
As a second application of our framework, we studyindividual power constraints. Power control is solved optimally by gradientdescent methods. Then, we develop three heuristics: DGA, DPGA and DIWA,which solve the JSPA problem for centralized and distributed settings.Their performance and computational complexity are compared throughsimulations.

Keywords : NOMA, SIC, resource allocation, convex andcombinatorial optimization

Titre : Allocation des ressources etoptimisation pour l’accès multiple non-orthogonal

Comparing the modelling powers of RNN and HMM
2020-03-11 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Recurrent Neural Networks (RNN) and Hidden Markov Models(HMM) are popular models for processing sequential data and have found manyapplications such as speech recognition, time series prediction or machinetranslation. Although both models have been extended in several ways (eg.Long Short Term Memory and Gated Recurrent Unit architectures, VariationalRNN, partially observed Markov models), their theoretical understandingremains partially open. In this context, our approach consists inclassifying both models from an information geometry point of view. Moreprecisely, both
models can be used for modeling the distribution of asequence of random observations from a set of latent variables; however,in RNN the latent variable is deterministically deduced from the currentobservation and the previous latent variable, while in HMM the set of(random) latent variables is a Markov chain. In this paper, we first embedthese two generative models into a generative unified model (GUM). We nextconsider the subclass of GUM models which yield a stationary Gaussianobservations probability distribution function (pdf). Such pdf arecharacterized by their covariance sequence; we show that the GUM model canproduce any stationary Gaussian distribution with geometrical covariancestructure. We finally discuss about the modeling power of the HMM and RNNsubmodels, via their associated observations pdf: some observations pdfcan be modeled by a RNN, but not by an HMM, and vice versa; some can beproduced by both structures, up to a reparameterization.

Introduction to PyTorch
2020-03-11 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Join us on for an introduction to PyTorch! Learn how to use itfor machine learning purposes, and why it is useful for deep learningresearch.

PyTorch is a Python based scientific computing packagetargeted as a replacement for NumPy that leverages the power of GPUs. It isalso used as a deep learning research platform that provides maximumflexibility and speed for developping neural networks architectures andtraining models through automatic differentation.

Slides

Notebook:https://colab.research.google.com/drive/16fHimaBw8zp9zp9AktOLE6BC7GLAUi90#scrollTo=_y251XyQ-V0D .

Thesis Defense : Autonomous IoT device type identification
2020-03-06 10:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
With the proliferation of smart devices, more and more peoplebuy IP devices and home appliances to benefit from new services, allowingthem to control their home anywhere, anytime and to remain informedabout.
The number of services enabled by the IoT devices is quicklyincreasing, and so is the diversity of types of such devices: cameras,sensors, smart phones, tablets, speakers coming from several vendors andwith different models. Devices and IoT service management systems ina home network needs to find out which IoT devices are connected tothe network. A device management system for all kind of devices beingconnected to the home network is necessary. In this thesis, we propose amethodology based on the analysis of network protocol messages to extractrelevant information about the devices in order to identify their type.Then, we proposed an other identification methodology based on MachineLearning algorithms. Our classification approach is based on thecombination of textual features extracted from packets payload andstatistical network communication features. We evaluate our proposal andshow that it outperforms the state of the art in this field withan
accuracy equal to 0.98.

En Français:
------------
Identificationdu type d’objet connecté de façon autonome

Avec la proliférationdes objets connectés, de plus en plus de personnes achètent des objetset des électroménagers connectés pour bénéficier de nouveauxservices, leur permettant de contrôler leur maison n'importe où, àtout moment et de rester informés. Le nombre de services activés par lesobjets IoT augmente rapidement, tout comme la diversité des types de cesobjets: caméras, capteurs, téléphones intelligents, tablettes,haut-parleurs provenant de plusieurs fournisseurs et avec différentsmodèles. Les objets et les systèmes de gestion des servicesIoT d'un réseau domestique doivent savoir quels objets IoTsont connectés au réseau. Un système de gestion d’objets pour tous lestypes dans un réseau domestique est nécessaire. Dans cette thèse, nousproposons une méthodologie basée sur l'analyse des messages de protocoleréseau pour extraire des informations pertinentes sur les dispositifs afind'identifier leur type. Ensuite, nous avons proposé une autreméthodologie d'identification basée sur des algorithmes de MachineLearning. Notre approche de classification est basée sur la combinaison defonctionnalités textuelles extraites de la charge utile des paquets et descaractéristiques de communication du réseau statistique. Nous évaluonsnotre solution et montrons qu'elle surpasse les solutions mentionnées dansl'état de l'art de la thèse avec une précision égale à 0,98.

Log Analysis via Space-time Pattern Matching
2020-03-04 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
The increasing number of machines and technologies involved inexisting infrastructures and networks hardens their management. Even ifmany monitoring solutions help to detect a faulty behavior, having a clearunderstanding of its causes is not always straightforward, especially ifrelevant information is scattered over logs issued by different software orhardware components. This paper proposes a new methodology inspired frompattern matching and able to find alarm correlations with or without priorknowledge about the monitored system. The proposed data structurecan store every observed pattern of correlated alarms by processing logsonline. It can be queried to extract the patterns of alarms leading to anarbitrary failure. This paper comes with three main contributions. First,we propose a framework able to represent alarm logs according tospatio-temporal dependencies. Second, we design a new scalable datastructure, able to store every observed pattern of alarms, and validateit by simulation on real and artificial datasets. Third, we show how toexploit this data structure for fault diagnosis.

Rare geometries: revealing rare categories via dimension-drivenstatistics
2020-03-04 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
In many situations, classes of data points of primary interestalso happen to be those that are least numerous. A well-known example isdetection of fraudulent transactions among the collection of all financialtransactions, the vast majority of which are legitimate. These types ofproblems fall under the label of ‘rare-category detection. There are twochallenging aspects of these problems. The first is a general lack oflabeled examples of the rare class and the second is the potentialnon-separability of the rare class from the majority (in terms of availablefeatures). Statistics related to the geometry of the rare class (such asits intrinsic dimension) can be significantly different from those for themajority class, reflecting the different dynamics driving variation in thedifferent classes. In this paper we present a new supervised learningalgorithm that uses a dimension-driven statistic, called thekappa-profile, to determine whether unlabeled points belong to a rareclass. Our algorithm requires very few labeled examples and is invariantwith respect to translation so that it performs equivalently on bothseparable and non-separable classes.

Reference: Rare geometries:revealing rare categories via dimension-driven statistics, Henry Kvinge,Elin Farnell, Jingya Li, Yujia Chen, 2019.

Converting Python plots to tikz with tikzplotlib
2020-02-26 16:00 - 16:10 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Short presentation of tikzplotlib.

Example.

Abstract Classes in Python
2020-02-26 15:00 - 16:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
An abstract class can be considered as a blueprint for otherclasses. It allows you to create a set of methods that must be createdwithin any child classes built from your abstract class. Abstract classprovides default functionality for the subclasses. By defining an abstractbase class, you can define a common Application Program Interface(API) fora set of subclasses. This capability is especially useful in situationswhere a third-party is going to provide implementations, such as withplugins in an application. It can also help you when working on a largeteam or with a large code-base where keeping all classes in your head atthe same time is difficult or not possible.

The notebook.

Beam Based Operations in 5G NR Rel-15
2020-02-26 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Deploying cellular networks in millimeter wave (mmWave)frequencies require coping with rapid channel variations and severefree-space pathloss and atmospheric absorption. In order to make use of thelarge portions of novel spectrum available at mmWave frequencies,highly-directional antennas generating radio beams (beamforming) are usedat base station and mobile terminal side. This presentation presents thenovel mechanisms introduced with 5G New Radio (NR) air interface forallowing the use of beamforming both for control and data channels,including (a) synchronization and initial access, and (b) beam managementprocedures.
Bio:
Fuad Abinader has pursued his BSc in Computer Scienceand MSc in Informatics at UFAM (Brazil), in 2002 and 2006, respectively,and his PhD in Telecommunications at UFRN (Brazil) in 2015. Hisprofessional career started in 2002, and he has been working with researchand development in Telecommunications since 2007, having publishednumerous papers and patents in the field. He's currently working at NokiaBell Labs Paris as a Research Engineer, and he's involved in thestandardization of 5G NR at 3GPP.

Collaboration and Innovation in an International Science andEngineering Competition
2020-02-19 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
In this talk, we will present our recent work investigatingcriteria of performance and success of teams in a scientific context usinga quantitative approach. We leverage electronic laboratory notebooks editedon wiki websites by over 2,000 teams of students participating to theinternational Genetically Engineered Machines (iGEM) synthetic biologycompetition over 10 years to uncover what features of team work bestpredict short term quality (medals, prizes) and long term impact (how thebiological parts that teams engineer are re-used by other teams). Usinginsights from the wiki commits (~1,000 per team), we unravel universalaspects of team dynamics and team collaborative patterns underlying iGEMteam work. Finally, by studying teams that
participated multiple times weexhibit mechanisms of collective learning underlying performanceimprovement. We will finish the talk by introducing our ongoing ‘IGEMTIES’ project conducted at the CRI Paris, where we are mappingtemporal, high-resolution team interaction networks using a bluetoothapp.

Bio: https://marcsantolini.com/about/

Asymptotics for Euclidean minimal spanning trees on random points
2020-02-19 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
I will present the main ideas of the paper "Asymptotics forEuclidean minimal spanning trees on random points" by David Aldous and J.Michael Steele. In this paper, the authors define Euclidean minimalspanning forest on a Poisson point process using a greedy algorithm. Theycompute the expectation of functionals on this minimal spanning forest suchas the degree of a vertex, the sum of the d-th power of edge lengthsincident at a vertex (where d is the dimension of the Euclidean space onwhich Poisson point lie). Their computations are based on the approximationof the Poisson point process with a scaled and shifted uniform i.i.d.random points on the unit cube. The conjectures posed by the authors inthis paper were partially resolved later and stimulated furtherresearch.

The slides.

Insights from heterogeneous random walks: from theory toapplications
2020-02-12 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
First I will introduce our model, heterogeneous continuoustime random walk (HCTRW) model as a versatile analytical formalism forstudying and modeling diffusion processes in heterogeneous structures,such as porous or disordered media, multiscale or crowded environments,weighted graphs or networks.
After some theoretical results about thisrandom walk model, diffusive dynamics and the spectral properties of thegeneralized transition matrix. In particular, we will talk about importantproperty, the distribution of the first passage times changes due to localand global heterogeneities of the medium. The HCTRW formalism offers aunified mathematical language to address various diffusion-reactionproblems, with numerous applications in material sciences, physics,chemistry, biology, and social sciences. We will also discuss somepossible applications for mobility and epidemiological models.
Bio:
Ihave been working in theoretical physics, mathematics, data analysis,computer science and applications to biology, climatology, socialscience, epidemiology and education. During my Phd I was working inHumboldt University and Potsdam Climate Institute in Marie-Curie project ondeveloping network methods for big data analysis >here<, then Idid several postdocs in Ecole Polytechnique working on transport in crowdedenvironments (here) After I got fellowship at CRI to work on mobilit,epidemiological models and data analysis methods applied to metascience andhealth data. Some publications are here on Google Scholar.

Currently Iam researcher in Bell labs in Data Analytics team.

Crawling the web with Scrapy
2020-02-12 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Scrapy is a Python-based tool for the collection of data fromwebpages which can be used either within Python code or in a stand-alonefashion (with very little knowledge of Python syntax). We will present thebasics of Scrapy and its limitations on a fewexamples.

Slides

Notebook

Diamond-Miner: Comprehensive Discovery of the Internet’s TopologyDiamonds
2020-02-05 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
(NSDI preview)
Despite the well-known existence ofload-balanced forwarding paths in the Internet, currentInternet-wide active topology mapping efforts are multipath agnostic– largely because of the probing volume and time required ofexisting multipath discovery techniques. This paper introducesD-Miner, a system that marries previous work on high-speed probingwith multipath discovery to make Internet-wide topologymapping, inclusive of load-balanced paths, feasible.We deployD-Miner and collect multiple IPv4 interface-level topologysnapshots, where we find > 64% more edges, and significantlymore complex and rich topologies, than existing systems. Wefurther scrutinize topological changes between snapshots andattribute forwarding differences not to routing or policychanges, but to load balancer “remapping” events. We preciselycategorize remapping events and find that they are a muchlarger and frequent contributor of path changes than previouslyrecognized. By making D-Miner and our collectedInternet-wide topologies publicly available, we hope to helpfacilitate better understanding of the Internet’s true structureand resilience.

Propagation of chaos in discrete-time Replica Mean Field models
2020-02-05 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Replica mean-field (RMF) models have been introduced in variousfields (biological neural networks, telecommunication networks) to studylimit behaviors in models whilst preserving the finite-size effects ofinteractions inside the considered networks. Replica-mean-field models aremade of infinitely many replicas which interact according to the same basicstructure as that of the finite network of interest.
I will present theRMF structure in discrete time in a very general setting and showproperties that arise at the limit in the number of replicas, such asasymptotic independence between replicas and the asymptotic behavior of thearrivals process to a given replica. I will also present RMF models incontinuous time which are of particular interest in computationalneuroscience.

Thesis Defense : Full-Duplex for Cellular Networks: A StochasticGeometry Approach
2020-01-30 14:00 - 16:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
English Version:

Full-duplex (FD) is a principle in which atransceiver can receive and transmit on the same time-frequency radioresource. The principle was long held as impractical due to the highself-interference that arises when simultaneously transmitting andreceiving in the same resource block. When assuming perfectself-interference cancellation, FD can potentially double the spectralefficiency (SE) of a given point-to-point communication. In practicethough, it is not possible to achieve the aforementioned characteristic.Moreover, under a cellular network context, not only theself-interference limits the performance, since additional co-channelinterference is created by base stations (BSs) and users equipment (UEs).However, even with the higher interference dowlinks (DLs) still obtainhigher SE performances, whereas uplinks (ULs) are generally criticallydegraded, when compared to half-duplex (HD).

We focus our work in thestudy of alternatives that can help improve the impaired ULs in FDnetworks, while still trying to profit from the gains experienced by DLs.In this regard, we use stochastic geometry along the thesis as a means tocharacterize key performance indicators of cellular networks, such as:coverage probability, average SE and data rates. The thesis is dividedinto three major studies. Firstly, we propose a duplex-switching policywhich enables BSs to operate in FD- or HD- depending on the UL and DLconditions. Secondly, we investigate the performance of hybrid HD/FDnetworks under a millimeter wave context. Finally, we propose a novelalgorithm based on non-orthogonal multiple-access (NOMA) and successiveinterference cancellation (SIC), which allows BSs to coordinate on theirrespective transmission schemes to reduce the BS-to-BS interference.

Wedemonstrate that the models presented in the thesis allow to balance thegains of one link over the other; reducing the UL degradation, whilemaintaining DL gains. In addition, we show that scenarios in whichequipment is able to perform beamforming are ideal for FD deployments,since they directly reduce the co-channel interference.

VersionFrançaise:

Le full-duplex (FD) est un principe selon lequel un appareilpeut recevoir et émettre sur la même ressource radiotemporaux-fréquentiel. Le principe a été longtemps considéré commeirréaliste en raison de la forte auto-interférence qui se produit lors dela transmission et la réception dans le même bloc de ressources. Ensupposant une annulation parfaite de l'auto-interférence (self-IC), ilpeut potentiellement doubler l'efficacité spectrale (SE) d'unecommunication point à point donnée. Dans la pratique, il n'est toutefoispas possible d'obtenir la caractéristique susmentionnée. En outre, dansle contexte d'un réseau cellulaire, la performance du FD n'est paslimité seulement par l'efficacité du self-IC, puisque des interférencessupplémentaires sont créées par les stations de base (BS) et leséquipements des utilisateurs (UEs). Toutefois, même avec des niveaux desinterférences plus élevés, les liens en voie-descendantes (DLs) obtientainsi de meilleures performances en termes de SE, tandis que les liaisonsmontantes (UL) sont généralement gravement dégradées par rapport auhalf-duplex (HD).

Nous focalisons notre travail sur l'étuded'alternatives qui peuvent aider à améliorer les UL dégradés dans lesréseaux basés sur FD, tout en essayant de profiter des gains obtenus parles DLs. À cet égard, nous utilisons la géométrie stochastique pourcaractériser les indicateurs clés de performance des réseauxcellulaires, tels que : probabilité de couverture, SE moyenne et débitde données. La thèse est divisé en trois grandes études.Premièrement, nous proposons une politique qui permet aux BSs de opéreren FD ou HD en fonction des conditions UL et DL. Deuxièmement, nousétudions la performance des réseaux hybrides HD/FD dans un contexted'ondes millimétriques. Finalement, nous proposons un algorithme basésur l'accès multiple non orthogonal (NOMA) et l'annulationd'interférences successives (SIC), qui permet aux stations de base decoordonner leurs schémas de transmission respectifs pour réduire lesinterférences BS vers BS.

Nous démontrons que les modèles présentéspermettent d'équilibrer les gains d'une liaison par rapport à l'autre ;réduisant la dégradation de l'UL, tout en maintenant les gains DL. Enoutre, nous montrons que les scénarios dans lesquels les équipement sontcapables de former des faisceaux sont idéaux pour les déploiements FD,puisqu'ils réduisent directement l'intérference co-canal.

BandWidth Part (BWP): A 5G feature for improving spectrumflexibility and power savings
2020-01-29 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Bandwidth Part (BWP) is a feature introduced in 3GPP Release 15as part of the standard for 5G New Radio (NR). The introduction of BWPs wasdriven by two factors: spectrum usage flexibility and power saving for theuser equipment (UE). Through spectrum flexibility the carrier bandwidth andnumerology in which a UE operates can be dynamically configured, thusallowing the network to simultaneously serve UEs with different servicerequirements (e.g., eMMB and mMTC). Furthermore, such flexibility allowsUEs to monitor a bandwidth narrower than the actual carrier bandwidth,which allows for power saving. This talk focuses on the basic aspects ofBWPs, it's configuration, and some of the already identified challengesthat come with its implementation. For the latter, simulation results arepresented to better illustrate the advantages and disadvantages of usingBWPs.
Bio:
Andrea Marcano is currently working as a Research Engineer forNokia Bell Labs France. She is part of a standardization research groupfocusing on radio interface architecture and protocols, where her workcenters on Radio Resource Management; she has been working with BWPs since2018.

Testing in Python
2020-01-29 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Testing enables you to quickly detect when you break somethingin your code. Python has very convenient tools to do it, such as Doctestand Pytest. We will also say a few words about Unittest, Tox and TravisCI.

Slides.

GitHub Repo.

Mutual Information Neural Estimation
2020-01-22 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Reference: Mutual Information Neural Estimation, Belghazi etal. , 2018.

The mutual information (MI) of two random variables is ameasure of the mutual dependence between two variables. More specifically,it quantifies the "amount of information" obtained about one randomvariable through observing the other random variable. Despite being apivotal quantity across data science, mutual information has historicallybeen difficult to compute. Exact computation is only tractable for discretevariables, or for a limited family of problems where the probabilitydistributions are known. For more general problems, this is not possible.Common approaches for MI estimation generally do not scale withdimensionality or sample size. I will present a method for estimatingefficiently a strongly consistent lower bound of mutual information thatcan be used in numerous machine learning problems.

Slides.

Notebook.

Reviewing code using Codecov
2020-01-15 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
When developing a package, it is often stressed that testsplay a crucial role in ensuring that your code works as intended. However,one may then wonder how to assert that—in turn—those very tests work asthey should. With that perspective in mind, we will go through the setupand use of Codecov, a code reviewing service that boasts a wide range ofsupported languages (thus this Python academy is open to most programmingorientations) and seamless setup with continuous integrationtools.

Slides: Reviewing_Code_Using_Codecov.

Spatial Birth-And-Death Wireless Networks
2020-01-08 11:00 - 12:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Reference: Spatial birth-and-death wireless networks, F.Baccelli et A. Sankararaman.

Stochastic geometry can prove useful tomodel spatial stochastic systems. In this paper, Baccelli and Sankararamanpresent a continuous space-time model for wireless networks taking intoaccount stochastic interactions between users. The paper studies thestability region for the underlying Markov chain and produces an exactvalue for the cutoff arrival rate for the system. As an extension, I willtalk about some natural extensions of the model I'm currently workingon.

Slides: Spatial_Birth-And-Death_Wireless_Networks.

Rewarding Miners: Bankruptcy games and Pooling Strategies
2019-12-18 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
In the Bitcoin system, mining is the procedure through whichminers can gain money on regular basis by finding solutions to amathematical crypto puzzle (full solution) which validates bitcointransactions. In order to reduce the uncertainty of the remuneration overtime, miners cooperate and form pools. Each pool receives a reward whichhas to be split among pool's participants. The focus of this paper is tounderstand which is best method for a mining pool to redistribute thereward among cooperating miners using proper game theoreticalmodels.
There exist, in the literature and in practice, several rewardfunctions which allocate bitcoins inside pools such as: (i) theproportional rule, (ii) the pay-per-share rule and (iii) an incentivecompatible rule ensuring that miners report full solutions to the poolimmediately and not with a delay. However, this last rule encourages aharmful intra-pool behaviour (i.e. pool hopping) in bankruptcy situations(where the gained reward results insufficient to remunerate pool miners)that causes a loss in terms of pool's computational power.
Byreinterpreting the allocating rules as outcomes of bankruptcy games (i.e.,a type of cooperative games) we construct two new reward functions (i.e.,the PPS-CEA and the PPS-CEL) and investigate their properties. The PPS-CELrules results having a good inter-pool behavior discouraging pool hoppinghowever, concerning the intra-pool behavior it does not behave as well asthe incentive compatible rule.
We provide then a suitable modification ofthe PPS-CEL that discourages pool hopping in bankruptcy situations whileguaranteeing the incentive compatible property.

Documenting code in Python
2019-12-18 11:00 - 12:00 | Doctoral Training Center (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
We will cover the basics of docstrings and see how to generatedocumentation with Sphinx.
Estimated duration: 30min.

Thesis Defense : Towards a scalable and programmable incrementaldeployment of ICN in the real world
2019-12-17 15:00 - 18:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Information-Centric Networking (ICN) embraces a family ofnetwork architectures re-thinking Internet communication principles aroundnamed-data. After several years of research and the emergence of a fewpopular proposals, the idea to replace TCP/IP with data-centric networkingremains a subject of debate. ICN advantages have been advocated in thecontext of 5G networks for the support of highly mobile,multi-access/source and latency minimal patterns of communications.However, large-scale testing and insertion in operational networks are yetto happen, likely due to the lack of a clear incremental deploymentstrategy. The aim of this thesis is to propose and evaluate effectivesolutions for deploying ICN.
Firstly, we propose Hybrid-ICN (hICN), anICN integration inside IP (rather that over/under/ in place of) that hasthe ambition to trade-off no ICN architectural principles. By reusingexisting packet formats, hICN brings innovation inside the IP stack,requiring minimal software upgrades and guaranteeing transparentinterconnection with existing IP networks.
Secondly, the thesis focuseson the problem of deploying ICN at the network endpoints, namely at theend host, by designing a transport framework and a socket API that can beused in several ICN architectures such as NDN, CCN and hICN. The frameworkfosters cutting-edge technologies aiming at providing performance andefficiency to applications. An extensive benchmarking at the end of thechapter will present the performance of the transportframework.
Subsequently, the benefits that hICN network and transportservices can bring to applications will be assessed, by considering twomain use cases: HTTP and WebRTC. The former represents the de-factoprotocol of the Web, while the latter is a new emerging technologyincreasingly adopted for real time services.
At last, the thesis proposesa solution for programmatically deploying, configuring and managing ICNnetworks and applications: Virtualized ICN (vICN), a programmableunified framework for network configuration and management that uses recentprogresses in resource isolation and virtualization techniques. It offers asingle, flexible and scalable platform to serve different purposes, inparticular the real deployments of ICN in existing IP networks.

Thesis Defense : Optimization and control of energy storage insmart grid
2019-12-06 14:00 - 16:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
This thesis is motivated by the electric power systemtransformations due to more renewable integration and changing consumptionpatterns. Energy storage is one possible solution to facilitate a smoothtransition, ensuring the stability of the power system. In this thesisLi-Ion battery is used both at the level of individual consumers,minimizing the cost of electricity by performing energy arbitrage undertime-varying electricity price, power factor correction, peak demandshaving and energy backup, and at the grid level for increasingreliability and stability of the power network by performing dynamicregulation and phase balancing. The cost of the batteries being stillhigh, the importance is also given to the health of the battery takinginto account its degradation in optimization and control formulations.Several case studies using real data are conducted to evaluate theperformance of the storage control and optimization algorithms. We observethat the ever-decreasing prices of batteries and the growing share ofintermittent renewables will only increase the relevance of this work forfuture power networks.

Introduction to Python (3)
2019-12-04 10:30 - 12:00 | Doctoral Training Center (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
We’ll cover basics of Python and design aspects.

Do nothesitate to come even if you did not attend the first and secondsessions.

Download the notebook.

Random walks on simplicial complexes
2019-11-27 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
The Laplacian of a graph is a key object in the theory ofgraphs and can be viewed as the generator of a continuous time Markov chainon the graph.
Simplicial complexes, or hypergraphs, are combinatorialobjects which generalizes graphs for which there also exist a notion ofLaplacian. We investigate the notion of random walk on such objects withthe goal to find a link between this generalized Laplacian and thegenerator of the Markov process.

Laurent Decreusefond is a Professor atTelecom Paris and have recently joined the LINCS lab.

False Discovery Rate
2019-11-27 10:30 - 12:00 | Doctoral Training Center (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
The false discovery rate (FDR) is a statistical approach usedin multiple hypothesis testing to correct for multiple comparisons. It istypically used in high-throughput experiments in order to correct forrandom events that falsely appear significant. When testing a nullhypothesis to determine whether an observed score is statisticallysignificant, a measure of confidence, the p-value, is calculated andcompared to a confidence threshold ?. When k hypotheses are testedsimultaneously with a confidence level ?, the chances of occurrence offalse positives (i.e., rejecting the null hypothesis when in fact it istrue) is equal to 1 ? (1 ? ?)k, which can lead to a high error rate in theexperiment. Therefore, a multiple testing correction, such as the FDR,is needed to adjust our statistical confidence measures based on the numberof tests performed.

References: False Discovery Rate(https://doi.org/10.1007/978-1-4419-9863-7_223), Computer Age StatisticalInference (By Bradley Efron, Trevor Hastie).

Introduction to Python (2)
2019-11-20 10:30 - 12:00 | Doctoral Training Center (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
We’ll cover basics of Python and design aspects.

Do nothesitate to come even if you did not attend the first session.

Downloadthe notebook.

Utility-maximising properties of some service-rates allocations inwireless communication networks
2019-11-13 14:00 | Doctoral Training Center (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
We consider wireless communication networks where service ratesof nodes depend the loads of their neighbours. We demonstrate that theserates are utility-maximising in a certain sense. Using this observation,we prove stability of single-hop networks under natural assumptions. Wealso obtain bounds on some moments of the stationary workload.

In orderto obtain these results, we consider a framework of utility-optimisingrate allocations which is much more general than the well-known$\alpha$-fairness, and prove general results on stability and bounds forsome stationary workload distributions in networks with these rateallocations.

We also discuss stability of infinite networks.

This isa joint work with Sasha Stolyar (UIUC).

Vsevolod "Seva"Shneer is a professor at Heriot-Watt University (Edimburg, Scotland)

Exact digraph enumeration
2019-11-06 10:30 - 12:00 | Doctoral Training Center (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
We present exact formulas for the number of digraphs in variousinteresting families: acyclic digraphs (dags), strongly connecteddigraphs, digraphs with constraints on their strongly connectedcomponents. They are obtained through generating function manipulations andwere first discovered by Wright, Liskovets and Robinson.

Rational vs Byzantine Players in Consensus-based Blockchains
2019-10-30 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
In this presentation, we will analyse from the gametheoretical point of view Byzantine Fault Tolerant (BFT) blockchains whenprocesses exhibit rational or Byzantine behaviour. Our work modelscommittee/consensus-based blockchains, such as as a committee coordinationgame.We provide a game-theoretical methodology to analyse equilibriuminteractions between Byzantine and rational committee members in BFTblockchains.Byzantine players seek to inflict maximum damage to thesystem, while rational players best-respond to maximise their expected netgains.We then derive conditions under which consensus properties aresatisfied or not in equilibrium.

Bio

YackolleyAmoussou-Guenou is a PhD student in LIP6, the computer science lab ofSorbonne Université, and in CEA List.He received his master degree fromUniversité Paris-Diderot and his undergraduate degree from UniversitéParis-Est Créteil.His research focuses on distributed systems andblockchains, and in particular on the application of game theory onblockchains.

Parallel Computing with Joblib and Plotting with Seaborn
2019-10-30 10:30 - 12:00 | Doctoral Training Center (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
When in need of benchmarking an algorithm, running saidalgorithm on a given - likely wide - range of parameters is usuallyrequired. In order to speed up this process, parallel computing may beused. I will detail how Joblib enables such computations for CPU-only taskswith minimal overhead to the code.

Once those computations are over,visualisation follows. To this end, I will introduce Seaborn, aPyPlot-based alternative to Matplotlib featuring refreshed visuals andenhanced interoperability with the Pandas package.

Download the files.

Cache Subsidies for an Optimal Memory for Bandwidth Tradeoff in theAccess Network
2019-10-23 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Authors: Mahdieh Ahmadi, James Roberts, EmilioLeonardi, and Ali Movaghar

While the cost of the access networkcould be considerably reduced by the use of caching,this is not currentlyhappening because content providers (CPs), who alone have the detaileddemand data required for optimal content placement, have no naturalincentive to use them to minimize access network operator (ANO)expenditure. We argue that ANOs should therefore provide such an incentivein the form of directsubsidies paid to the CPs in proportion to therealized savings. We apply coalition game theory to design the requiredsubsidy framework and propose a distributed algorithm, based on Lagrangiandecomposition, allowing ANOs and CPs to collectively realize the optimalmemory for bandwidth tradeoff. The considered access network is a cachehierarchy with per-CP central office caches, accessed by all ANOs, at theapex,and per-ANO dedicated bandwidth and storage resources at the lowerlevels, including wireless base stations, that must be shared by multipleCPs.

Deep Q-Learning: From Theory to Practice
2019-10-23 10:30 - 12:00 | Doctoral Training Center (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
After a brief presentation of Reinforcement Learning ingeneral, I give the theoretical bases for a particular reinforcementalgorithm, Q-Learning, and its neural-network-powered version, DeepQ-Learning. Then I show some difficulties that can be encountered duringimplementation and I suggest solutions to overcome them, drawn from mypersonal experience.

Reference: the slides and videos from DavidSilver's online course on Reinforcement Learning(http://www0.cs.ucl.ac.uk/staff/d.silver/web/Teaching.html).

Multi-cell MIMO Transceiver design for Mission-CriticalCommunication
2019-10-16 14:00 - 14:30 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Business and Mission critical communication (MCC) is a majorcommunication paradigm that is used by public agencies, e.g., duringemergency situations, or critical infrastructure companies, e.g.,airports, transportation, etc. MCC has very stringent requirements interms of reliability, coverage and should offer group communications.Coordinated Multimedia Multicast/Broadcast single frequencynetwork (MBSFN) is considered as a potential technology for MCC as itbenefits from increased coverage and inter-cell interference mitigation. Inthis paper, we propose multi-input-multi-output (MIMO) multimedia MBSFNsystem design wherein each base station (BS) of a coordinated clustermulticasts a common message to all the users in a group. We use a greedyalgorithm to dynamically form the cluster of synchronized BSs for optimalutilization of resources within an MBSFN. We assume the availability ofperfect channel state information (CSI) knowledge and jointly obtain theoptimal precoder and receive filters by minimizing the overallsum-mean-square-error (sum-MSE) constrained over the total transmit power.We further extend the proposed design to a robust case by considering theimperfections in available channel knowledge and obtain the transceivermatrices that are resilient to channel errors. We also present both thejoint and robust system design for Single-Cell point-to-multipoint (SC-PTM)which is an alternative solution to MBSFN in MCC. Numerical results showthe effectiveness of the proposed network architecture for future missioncritical communication. Furthermore, the comparison results show that theproposed robust design demonstrate better performance and is resilient tothe presence of CSI errors.

Bio

Deepa Jagyasi received theBachelor of Engineering degree in electronics and telecommunicationengineer from Pune University, Pune, India, in 2010, the Master ofEngineering degree in electronics and communication engineering from MumbaiUniversity, Mumbai, India, in 2013 and the Ph.D degree fromInternational Institute ofInformation Technology, Hyderabad, India in2019. She is currently working as post-doc at DépartementInformatique et Réseaux, Telecom-Paristech, Paris, France. Herresearch interests include robust transceiver-design, millimeter-wave communications, multiple-input-multiple-output precoding, machinelearning and physical layer security.

Introduction to CherryPy
2019-10-16 10:30 - 12:00 | Doctoral Training Center (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
For most daily research tasks, a Jupyter Notebook is morethan enough to do anything one wants. Yet, there are situations where itcan be useful to turn your Python programs into a Website:

Sharingresults with someone that does not know Python or Notebooks,
Preparing ademo,
Having a program in Computer A that starts and retrieve computationresults from computer B.

During this tutorial, we'll show you howto easily deploy Python code on http by using CherryPy.
Download thefiles.

OFDMA Dimensioning
2019-10-09 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
This presentation will cover different models for thedimensioning of OFDMA air interfaces. In a first part, models that rely onclassical stochastic geometry results and on concentration inequalities,will be introduced. The adopted approach is to obtain an upper bound of theoutage probability in terms of Resource Blocks (RB) and to derive thenumber of RB required to provide a QoS target.The second part of the talkwill deal with modeling of city maps via random tessellations (CrackSTIT/PLT). This modeling provides a way to generate city maps as an outcomeof a random tesselation.By using a ray launcher simulator on these maps,it becomes possible to obtain coverage maps and SINR by simulation. Theimpact of the geometry of the city on the OFDMA dimensioning can then beinvestigated.

Bio

Philippe Martins is professor in thenetworking and computer science department, at Telecom ParisTech since2010. Before he held a position of associate professor in the samedepartment since 2000. He obtained his PhD from Telecom ParisTech in 2000(with honors) for his work on the design and performance evaluation ofsignaling protocols for B-ISDN networks. In 2000, he started working oncellular networks. Since then, his main research interests lie inperformance evaluation, planning, algorithms and protocols design. He haspublished several papers on different international journals andconferences. He is an IEEE senior member since 2010 and is co-author ofseveral books and chapter books on cellular systems. He worked in severalnational research projects (ANR, RNRT, URC competitivity cluster oncognitive radio, FUI projects) and European research programs (ITEA). Heinvestigated on 3G and 4G systems (scheduling, radio resourcesmanagement, handover algorithms, planning and dimensionning) incollaboration with several companies (Alcatel, Nokia, Orange, SFR,Bouygues Telecom,TDF). He was also involved in standardization activitesas a scientific consultant for companies such as EADS, ESA and Airbusdefence.In 2008/2008 (one year), 2010 (July-Aug) and 2011 (July-Aug), hewas invited professor at NCRL (National mobile Communication ResearchLaboratory), in Nanjing. In December 2013 he became guest professor at SEU(South East University), Nanjing, China. Since then, he is regularlyinvolved in common research cooperations with NCRL on IoT and 5G.

Transformer models in Artificial Intelligence for Natural LanguageProcessing
2019-10-09 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
We'll explore recent Deep Learning models for NaturalLanguage Processing based on the ("post-Recurrent NeuralNetwork") Transformer architecture described in AttentionIs All You Need (Vaswani et al., 2017). We'll understandthe intuition behind this architecture and how it was applied to supervisedSeq2Seq tasks. Then we'll see how Devlin etal. (2018) pre-trained a deep bidirectional transformercalled BERT, a model producing state-of-the-art results on severalNatural Language Understanding tasks.If time permits, we'll dig intoderived models of transformer such as Open AI GPT-2 (Radford etal., 2019). GPT-2 achieves astounding results in NaturalLanguage Generation and has been reported as "the text generator performingtoo well to be released" in the press...
Slides to the presentation

Introduction to Python
2019-10-02 10:30 - 12:00 | LINCS Meeting Room 26, 23, avenue d'Italie, Paris, 75013,France
We'll cover basics of Python and design aspects.
Downloadthe notebook.

Introduction to Quantum Computing (2)
2019-09-25 15:00 - 16:30 | LINCS Meeting Room 26, 23, avenue d'Italie, Paris, 75013,France
When I was student, I was interested in quantum optics: myfirst paper was about quantum non-linear optics. Quantum computing hasbecome a new hype in telecommunication and computing. So I wanted tounderstand by myself how quantum computing works (thanks Wikipedia!).Starting with a reminder of quantum mechanics principles, I will explainwhat is a "quantum computer", what are "qubits", "quantum registers","quantum logical gates" and give some examples of "quantum algorithms" suchas quantum "teleportation", Shor's algorithm for integer factorization andseveral other ones. I will also show how we can play with quantum computers(python libraries, LaTeX packages, web sites). In terms of knowledgerequirement, you just need to know a bit of linear algebra (calculationwith square matrices on complex numbers) and accept the quantum physicalrules as they are (maybe the most difficult aspect!): a quantum computer isjust a system that processes unitary transformations on complex vectors(i.e., multiplications by unitary complex matrices)!

The materialof the two sessions will be availableat:
http://www.ludovic-noirie.fr/sciences/quantum-computing/

Distributed Reconfiguration of Graph Problems
2019-09-25 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
In Graph Theory, a reconfiguration problem is as following:given two solutions of a problem and a transition definition, is there apath of acceptable solutions from the first to the second using atransition one after another? What is the length of the shortestreconfiguration path? What complexities are involved? For example, arecoloration problem asks if we can go from a coloration to another, bychanging the color of a node at each transition (with the coloring stillvalid in the intermediate steps).In this talk, the goal would be toconsider distributed version of two reconfiguration problems: recoloring,and reconfiguring independent sets. To parallelise the process, we willaccept to change the state of different nodes at once, under certainhypothesis (for example, we will recolor an independent set of nodes). Thequestions will be, using the LOCAL model, how much communication isneeded (i.e. how much a node needs knowledge of its neighborhood) in orderto produce a reconfiguration schedule of a given length.For the distributedrecoloring (DISC 2019), we prove that the addition of colors for theintermediate steps is needed for some cases in order to have a solution. Iwill provide the analysis of trees, where we want to go from a 3-coloringto another with the use of a 4th color. II will show that a constantschedule can be found after O(D+log* n) communications. For thereconfiguration of independent sets (ICALP 2019 Best Paper), we willpresent different transitions from the centralized settings, to thenjustify the one we use. We prove that a constant schedule can be foundafter O(D +log* n) communications, and a linear schedule can be foundafter a constant number of communications.

Those works are theresult of collaborations with Marthe Bonamy, Keren Censor-Hillel, PaulOuvrard, Jara Uitto and Jukka Suomela

Thesis Defense : Resource management in computer clusters:algorithm design and performance analysis
2019-09-24 14:00 - 16:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
The growing demand for cloud-based services encouragesoperators to maximize resource efficiency within computer clusters. Thismotivates the development of new technologies that make resource managementmore flexible. However, exploiting this flexibility to reduce the numberof computers also requires efficient resource-management algorithms thathave a predictable performance under stochastic demand. In this thesis, wedesign and analyze such algorithms using the framework of queueingtheory.

Our abstraction of the problem is a multi-server queue withseveral customer classes. Servers have heterogeneous capacities and thecustomers of each class enter the queue according to an independent Poissonprocess. Each customer can be processed in parallel by several servers,depending on compatibility constraints described by a bipartite graphbetween classes and servers, and each server appliesfirst-come-first-served policy to its compatible customers. We first provethat, if the service requirements are independent and exponentiallydistributed with unit mean, this simple policy yields the same averageperformance as balanced fairness, an extension to processor-sharing knownto be insensitive to the distribution of the service requirements. A moregeneral form of this result, relating order-independent queues to Whittlenetworks, is also proved. Lastly, we derive new formulas to computeperformance metrics.

These theoretical results are then put intopractice. We first propose a scheduling algorithm that extends theprinciple of round-robin to a cluster where each incoming job is assignedto a pool of computers by which it can subsequently be processed inparallel. Our second proposal is a load-balancing algorithm based on tokensfor clusters where jobs have assignment constraints. Both algorithms areapproximately insensitive to the job size distribution and adaptdynamically to demand. Their performance can be predicted by applying theformulas derived for the multi-server queue.

Résumé :

Lademande croissante pour les services de cloud computing encourage lesopérateurs à optimiser l’utilisation des ressources dans les grappesd’ordinateurs. Cela motive le développement de nouvelles technologiesqui rendent plus flexible la gestion des ressources. Cependant, exploitercette flexibilité pour réduire le nombre d’ordinateurs nécessite aussides algorithmes de gestion des ressources efficaces et dont la performanceest prédictible sous une demande stochastique. Dans cette thèse, nousconcevons et analysons de tels algorithmes en utilisant le formalisme de lathéorie des files d’attente.

Notre abstraction du problème estune file multi-serveur avec plusieurs classes de clients. Les capacitésdes serveurs sont hétérogènes et les clients de chaque classe entrentdans la file selon un processus de Poisson indépendant. Chaque client peutêtre traité en parallèle par plusieurs serveurs, selon des contraintesde compatibilité décrites par un graphe biparti entre les classes et lesserveurs, et chaque serveur applique la politique premier arrivé,premier servi aux clients qui lui sont affectés. Nous prouvons que, si lademande de service de chaque client suit une loi exponentielleindépendante de moyenne unitaire, alors la performance moyenne sous cettepolitique simple est la même que sous l’équité équilibrée, uneextension de processor-sharing connue pour son insensibilité à la loi dela demande de service. Une forme plus générale de ce résultat, reliantles files order-independent aux réseaux de Whittle, est aussi prouvée.Enfin, nous développons de nouvelles formules pour calculer desmétriques de performance.

Ces résultats théoriques sont ensuitemis en pratique. Nous commençons par proposer un algorithmed’ordonnancement qui étend le principe de round-robin à une grappe oùchaque requête est affectée à un groupe d’ordinateurs par lesquelselle peut ensuite être traitée en parallèle. Notre seconde propositionest un algorithme de répartition de charge à base de jetons pour desgrappes où les requêtes ont des contraintes d’affectation. Ces deuxalgorithmes sont approximativement insensibles à la loi de la taille desrequêtes et s’adaptent dynamiquement à la demande. Leur performancepeut être prédite en appliquant les formules obtenues pour la filemulti-serveur.

Harnessing the Difficulties of Synchronization
2019-09-19 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
We are well into the era of multi-core architecturesand as the applications demands are still growing, we soon expect to seethe first many-cores which will feature many hundreds or thousands ofcores.
Refactoring software to introduce as much parallelism as possibleis therefore of crucial importance in order to take advantage of themassively parallel nature of current and future multi-core and many-coremachines. A major obstacle in this direction comes from the difficulty ofachieving efficient synchronization and communication between threads thatrun concurrently. This lecture aims to alleviate this difficulty bypresenting state-of-the-art synchronization mechanisms and highly-efficientfundamental concurrent data structures.

Bio

PanagiotaFatourou is an Associate Professor of Computer Science at the University ofCrete and at the Foundation of Research and Technology-Hellas (FORTH ICS),Greece. She has worked as a visiting Professor at EPFL in Switzerland, asa full-time faculty member at the University of Ioannina in Greece, and asa postdoc researcher at Max-Planck Institut fuer Informatik in Germany andat the University of Toronto in Canada. She is an elected member of the ACMEurope Council (currently serving as the treasurer) and an ACMDistinguished Speaker.

She has served as the editor of theDistributed Computing Column of the Bulletin of EATCS, as the GeneralChair of ACM PODC 2013, as the PC chair of OPODIS 2016 and SSS 2017(distributed computing track), and as a member of the steering committeesof PODC and OPODIS. She has participated in the PC of more than 35conferences. She has been the coordinator of a Marie-Curie Initial TrainingNetwork and she has participated in many additional research anddevelopment projects mostly funded by the European Commission. Her researchinterests focuses on the theory of Parallel and Distributed Computing.

Backtrack bandit algorithms for cloud computing
2019-09-18 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Unimodal functions arise whenever the expected value f(x) ofthe metric to be optimized has a single peak as a function of the availablecontrol variable x.

The exact shape of f is often not known inadvance, hence it can only be learned via sampling.

For thispurpose, we exploit the formalism of multi-armed bandits to design alearning algorithm that i) converges in probability to the optimal armmaximizing f and ii) does not require to know the learning horizon inadvance, i.e., it is “anytime”. Moreover, it adapts naturally to thescenario where iii) prior knowledge on the location of the peak isavailable, even if the prior is inaccurate.

We also present anefficient heuristic that can use explicitly the prior belief on thelocation of the optimal arm. We demonstrate the applicability of ourapproaches to a basic resource allocation problem for cloud computing,where the orchestrator aims at adapting the resources allocated to a clientto its unknown and dynamic requests.

Introduction to Quantum Computing
2019-09-18 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
When I was student, I was interested in quantum optics: myfirst paper was about quantum non-linear optics. Quantum computing hasbecome a new hype in telecommunication and computing. So I wanted tounderstand by myself how quantum computing works (thanksWikipedia!).Starting with a reminder of quantum mechanics principles, Iwill explain what is a "quantum computer", what are "qubits", "quantumregisters", "quantum logical gates" and give some examples of "quantumalgorithms" such as quantum "teleportation", Shor's algorithm for integerfactorization and several other ones.I will also show how we can play withquantum computers (python libraries, LaTeX packages, web sites).In termsof knowledge requirement, you just need to know a bit of linear algebra(calculation with square matrices on complex numbers) and accept thequantum physical rules as they are (maybe the most difficult aspect!): aquantum computer is just a system that processes unitary transformations oncomplex vectors (i.e., multiplications by unitary complexmatrices)!

The material of the two sessions will be availableat:http://www.ludovic-noirie.fr/sciences/quantum-computing/

Tractable reliable communication in static and dynamic compromisednetworks
2019-09-04 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Many solutions to fault tolerant distributed systemproblems, such as state machine replication, safe broadcast oragreement, rely on reliable communication primitives which guarantee thecorrect messages exchange between processes even in case offailures.Although considering quite strong system assumptions (completecommunication network, digitally signed messages, knowledge oncommunication network topology) a reliable communication service can beefficiently implemented, especially under the message complexity point ofview, it may become intractable to provide under the weaker and moregeneral assumption of an incomplete and unknown communication network.Inthis talk, we review and improve the state-of-art solutions implementingreliable communication in multi-hop networks and we discuss their possibleemployment on dynamic networks.

Towards theoretically-founded structure learning
2019-07-10 15:00 - 16:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Solving most inference tasks, such as denoising andlinear regression, relies on exploiting the structure of the desiredclass of signals (e.g. images). Traditionally, such structures arediscovered by domain experts after extensive studies. This hasto a great extent limited the discovery and application of complexstructures that exist in many signals of interest. Learning-basedmethods that automatically recover the structure of the source fromavailable training datasets provide a promising alternative solution. However, for continuous-valued signals, learning the sourcedistribution is extremely challenging, and theoretically-foundedcomputationally-feasible approaches are yet to be found. Inthis talk, I will discuss recently-proposed structure learningmethods that, instead of learning the full distribution of thesource, learn its key features that are relevant to solvinginference problems. As I will discuss, this method, whilesubstantially reducing the computational complexity of the structurelearning task, leads to asymptotically optimallearning-based estimators.

Channel Estimation in Visible Light Communications
2019-07-10 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
In visible light communications (VLC), LEDs are used for notonly illumination but also communications. LEDs can further be used tosupport indoor positioning with high accuracy. Together with advantagessuch as high data rates, free from radio frequency interference and energyefficiency, VLC would be crucial for Internet-of-Things (IoT) applicationsas diverse as autonomous vehicles, robotics & sensing and smart home& office. In the first part of this talk, a brief overview of ourvisible light positioning systems for IoT applications will begiven.

It is essential to obtain accurate estimates of the channelgains between receiver and multiple light sources in VLC networks. Whenthere are multiple transmitters, time-division multiple access (TDMA) istypically used in the channel estimation phase of radio frequency systems.However, the estimation performance of TDMA-based schemes in VLC networksis substantially impacted by the maximum power constraint and desiredaverage power constraint that are unique to visible light systems. Underthese constraints, this talk shows a fundamental lower bound on thetotal noise variance at the receiver. The necessary and sufficientconditions for the bound to hold with equality are derived. This talk alsoillustrates a one-to-one correspondence between a balanced incomplete blockdesign and an optimal pilot design with minimal total noise variance.Methods for constructing pilot sequences, which satisfy an arbitraryaverage power constraint, are shown.

Structural and Temporal Information
2019-07-03 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Shannon's information theory has served as a bedrock foradvances in communication and storage systems over the past five decades.However, this theory does not handle well higher order structures (e.g.,graphs, geometric structures), temporal aspects (e.g., real-timeconsiderations), or semantics. We argue that these are essential aspectsof data and information that underly a broad class of current and emergingdata science applications.In this talk, we present some recent results onstructural and temporal information. We first show how to extract temporalinformation in dynamic networks (arrival of nodes) from its structure(unlabeled graphs).We then proceed to establish fundamental limits oninformation content for some data structures, and present asymptoticallyoptimal lossless compression algorithms achieving these limits for variousgraph models.

Bio

Wojciech Szpankowski is Saul RosenDistinguished Professor of Computer Science at Purdue University where heteaches and conducts research in analysis of algorithms, informationtheory, analytic combinatorics, network science, random structures, andstability problems of distributed systems.He held several VisitingProfessor/Scholar positions, including McGill University, INRIA,France, Stanford, Hewlett-Packard Labs, Universite de Versailles,University of Canterbury, New Zealand, Ecole Polytechnique, France, theNewton Institute, Cambridge, UK, ETH, Zurich, and Gdansk University ofTechnology, Poland.He delivered several plenary talks including atISIT'11, WITMSE'14, CPM'15, AofA16, Knuth80'18, and SODA'19. He hasbeen on editorial boards on many journals including IEEE Trans. InformationTheory, TCS, CPC, and ACM Trans. on Algorithms.Szpankowski is a Fellowof IEEE, and the Erskine Fellow.In 2010 he received the Humboldt ResearchAward and in 2015 the Inaugural Arden L. Bement Jr. Award.He published twobooks: "Average Case Analysis of Algorithms on Sequences", John Wiley& Sons, 2001, and "Analytic Pattern Matching: From DNA to Twitter",Cambridge, 2015.In 2008 he launched the interdisciplinary Institute forScience of Information, and in 2010 he became the Director of the NSFScience and Technology Center for Science of Information.

Mirai and the Current State of IoT Security
2019-06-26 15:00 - 16:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
The Mirai botnet, composed primarily of embedded and IoTdevices, took the Internet by storm in late 2016 when it overwhelmed andcensored high-profile websites with the largest distributeddenial-of-service (DDoS) attacks on public record. In this talk, I'llpresent what actually happened based on a retrospective analysis byacademic researchers, the companies attacked, and independentjournalists, as well discuss the current state of IoT deployment in homes.I'll cover how the botnet emerged, what classes of devices were affected,who the botnet attacked, and how variants evolved and competed forvulnerable hosts. I'll also discuss the types of types of IoT devices wesee deployed today and their security weaknesses that could lead to similarattacks in the future. I'll conclude with a discussion of the implicationsfor the Internet community including IoT manufacturers, network and siteoperators, and policy makers.

Tags : Mirai and the Current Stateof IoT Security , Zakir Durumeric, Stanford University

Leveraging Quantum Annealing for Large MIMO Processing inCentralized Radio Access Networks
2019-06-26 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Conventional thinking treats the wireless channel as agiven constraint, so wireless networks to date center on the problemoptimizing the communication endpoints. We instead explore whether it ispossible to reconfigure the environment itself to facilitate wirelesscommunication. In this work, we instrument the environment with a largearray of inexpensive antennas (LAIA) and design algorithms to configurethem in real time. We design and deploy a 36-element passive array in areal indoor home environment. Experiments with this prototype show that,by reconfiguring the wireless environment, we can achieve a 24% TCPthroughput improvement on average and a median improvement of 51.4% inShannon capacity over the baseline single-antenna links. Over the baselinemulti-antenna links, LAIA achieves an improvement of 12.23% to 18.95% inShannon capacity.

User demand for increasing amounts of wirelesscapacity continues to outpace supply, and while 5G Massive MIMO wirelessdesigns begin to address this, even higher-performance systems now remainimpractical largely only because their algorithms are extremelycomputationally demanding. The base station's computational capacity isthus becoming one of the key limiting factors on wireless capacity. I willdiscuss work in large MIMO centralized radio access network designs backedby quantum computation. We have implemented one such design, QuAMax, onthe 2,031 qubit D-Wave 2000Q quantum annealer, the state-of-the-art inthe field. Our experimental results evaluate that implementation on realand synthetic MIMO channel traces, showing that 30 ?s of compute time onthe 2000Q can enable 48 user, 48 AP antenna BPSK communication at 20 dBSNR with a bit error rate of 1 ppm and a 1,500 byte frame error rate of0.01%.

Introduction to the K-Nearest Neighbors problem
2019-06-24 10:30 - 12:00 | Telecom Paristech, I338 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
Definition and motivation.Standard algorithms.A new approach.

Fine-grained analysis of wireless networks: Spatial outage capacityand rate control
2019-06-19 15:00 - 16:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Modern wireless networks should be able to accommodate a highdensity of users. But serving more users usually generates higherinterference which leads to more failed transmissions. This trade-off givesrise to a natural and fundamental question that surprisingly remainedunanswered: What is the maximum density of concurrently active links thatmeet an outage (reliability) constraint? We answer this question byintroducing a new notion of capacity, termed spatial outage capacity(SOC). Using the mathematical tools from stochastic geometry, we formulateand analyze the SOC based on the meta distribution framework which allowsus to evaluate per-link reliability in a wireless network. We also provethe duality between the per-link reliability and the rate control, wherethe latter offers a key advantage of guaranteeing target reliability foreach link in the network.

Tags : Fine-grained analysis of wirelessnetworks: Spatial outage capacityand rate control , Sanket Kalamkar,Inria, ERC NEMO

Function Computation in Networks
2019-06-19 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
This talk describes a new perspective on cloud/fogcomputing, by distributing computation in order to handle the large volumeof data with growing computational demand. Our goal is to devise codingtechniques for functional compression in networks, by employing theconcepts of graph entropy, common information, and exploiting functionsurjectivity and role of a helper in encoding of functions. Thesetechniques suit different applications such as caching, classification,federated learning, quantization, and compressed sensing. Our unifiedinsights suggest to distribute computation by making use of underlyingredundancy both in data and functions, in order to recover a sparserepresentation, or labeling.

Tags: Function Computation inNetworks , Derya Malak , MIT ,

Learning regular sets from queries and counterexamples
2019-06-17 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
The problem of identifying an unknown regular set fromexamples of its members and nonmembers is addressed. It is assumed that theregular set is presented by a minimally adequate Teacher, which can answermembership queries about the set and can also test a conjecture andindicate whether it is equal to the unknown set and provide acounterexample if not. (A counterexample is a string in the symmetricdifference of the correct set and the conjectured set.) A learningalgorithm L* is described that correctly learns any regular set from anyminimally adequate Teacher in time polynomial in the number of states ofthe minimum dfa for the set and the maximum length of any counterexampleprovided by the Teacher. It is shown that in a stochastic setting theability of the Teacher to test conjectures may be replaced by a randomsampling oracle, EX( ). A polynomial-time learning algorithm is shown fora particular problem of context-free languageidentification.

Reference: Learning regular sets from queries andcounterexamples (Dana Angluin, 1987)

Stable Coin
2019-06-12 18:00 - 18:30 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Tags: Stable Coin , Nadia Filali , Caisse des dépôts

Slides Marianna Belotti & Nadia Filali - Stable Coin, Caissedes dépôtsDownload

Cooperative games for Atomic Crosschain Swaps
2019-06-12 17:45 - 18:00 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Tags: Cooperative games for Atomic Crosschain Swaps ,Marianna Belotti , CNAM , Caisse des Dépots , Sorbonne-Université ,Dauphine

Slides Marianna Belotti - Cooperative games for AtomicCrosschain SwapsDownload

Blockchains and applications to the smart grids
2019-06-12 17:30 - 17:45 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Tags : Blockchains and applications to the smart grids , José Horta , Telecom Paris & EDF , BlockchainDay

Slides JoseHorta - Blockchains and applications to the smart gridsDownload

Polygraph : Accountable Byzantine Agreement
2019-06-12 17:15 - 17:30 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Polygraph Accountable Byzantine Agreement , Pierre Civit ,Nexeo , BlockChainDay

Slides Pierre Civit - PolygraphDownload

Stakecube: Combining Sharding and Proof-of-Stake to build Fork-free Secure Permissionless Distributed Ledgers
2019-06-12 17:00 - 17:15 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Tags: Stakecube: Combining Sharding and Proof-of-Stake tobuild Fork- free Secure Permissionless Distributed Ledgers , AntoineDurand , IRT SystemX , BlockchainDay

Slides Antoine Durand -StakecubeDownload

Non cooperative games and BFT-based blockchains
2019-06-12 16:45 - 17:00 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Non cooperative games and BFT-based blockchains , YackolleyAmoussou-Guenou , Sorbonne-Université CEA , BlockChainDay

Slides Yackolley Amoussou-Guenou - Non cooperative games andBFT-based blockchainsDownload

G-IOTA & E-IOTA
2019-06-12 16:30 - 16:45 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Tags: Bu Gewu , Sorbonne Université , Lip6 , UPMC ,G-IOTA & E-IOTA , BlockChain Day

Slides Gewu Bu - G-IOTA& E-IOTADownload

Game theoretical analysis of competition between miners
2019-06-12 16:00 - 16:30 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Tags: Game theoretical analysis of competition betweenminers, Eitan Altman, Inria, BlockChain Day

Slides Eitan Altman -Game theoretical analysis of competition between minersDownload

Green Mining, Toward a less energetical impact ofcryptocurrencies
2019-06-12 15:30 - 16:00 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Tags: Green Mining, Toward a less energetical impact ofcryptocurrencies, Philippe Jacquet, Nokia Bell Labs France, BlockChainDay

Slides Philippe Jacquet - Green Mining, Toward a lessenergetical impact of cryptocurrenciesDownload

Blockchain Communication Protocol
2019-06-12 15:00 - 15:30 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Tags: Antoine Herzog & Karim Ganem, BlockchainCommunication Protocol, IOV

Slides Antoine Herzog & KarimGanem - Blockchain Communication ProtocolDownload

Analysis of financial transactions with link streams
2019-06-12 14:30 - 15:00 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Tags: Analysis of financial transactions with link streams,Matthieu Latapy, Sorbonne Université, UPMC, Lip6,BlockChainDay

Slides Matthieu Latapy - Analysis of financialtransactions with link streamsDownload

IOTA
2019-06-12 14:00 - 14:30 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Tags: IOTA, Quentin Bramas, Université de Strasbourg,BlockChain Day

Slides Quentin Bramas - IOTADownload

Lightning Networks
2019-06-12 13:45 - 14:15 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Slides Bastien Teinturier - Lightning NetworksDownload

Sycomore
2019-06-12 13:00 - 13:30 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Tag: Sycomore, Emmanuelle Anceaume, CNRS, Irisa Rennes,BlockChain Day

Slides Emmanuelle Anceaume - SycomoreDownload

Veolia blockchain projects
2019-06-12 12:00 - 12:30 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Veolia blockchain projects, Olivier Tridon,Véolia

Slides Olivier Tridon - Veolia blockchain projectsDownload

Lifestyle Authentication
2019-06-12 12:00 - 2019-07-12 12:30 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Tags : Lifestyle Authentification, Rie Yamaguchi, TokyoUniversity, Université de Tokyo, Blockchain Day

Slides RieYamaguchi - Lifestyle AuthenticationDownload

Multi Signatures for Blockchains
2019-06-12 11:30 - 12:00 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Tags: Multi Signatures for Blockchains, Yannick Seurin,ANSSI, BlockChain Day

Slides Yannick Seurin - Multi-Signatures forBlockchainsDownload

Blockchain Abstract Data Type
2019-06-12 10:30 - 11:00 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Tags : Blockchain Abstract Data Type, Antonella de Pozzo,CEA

Slides Antonella del Pozzo - Abstract Data TypeDownload

The Consensus Number of a Cryptocurrency
2019-06-12 10:15 - 10:45 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Tags : The Consensus Number of a Cryptocurrency, PetrKouznetsov, Telecom Paris, BlockChain Day

Slides Petr Kouznetsov -The Consensus Number of a CryptocurrencyDownload

Dissection of a public Blockchain in Banque de France
2019-06-12 10:00 - 10:30 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Tags: BlockChain Day, Jean-Baptiste Baraton, Banque deFrance, Dissection of a public Blockchain in Banque de France

Cross chain Deals and Adversarial Commerce
2019-06-12 09:15 - 10:00 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France

Blockchain Day
2019-06-12 09:00 - 18:30 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
Program

9:00 Reception 9:15-9:20 Opening(Fabio + Maria) 9:20-10:00 Maurice Herlihy (Brown University) Cross-chain Deals and Adversarial Commerce 10:00-10:20 Jean-BaptisteBaraton (Banque de France) Dissection of a public blockchain in Banque deFrance 10:20-10:40 Petr Kouznetsov (Telecom Paris) The Consensus Numberof a Cryptocurrency 10:40-11:00 Antonella del Pozzo (ex Sorbonne -CEA) Blockchain abstract data type 11:10-11:20 Coffee Break 11:20-11:40 11:40-12:00 Yannick Seurin (ANSSI) Crypto tools forBlockchains 12:00-12:20 Olivier Tridon (Veolia Nova) Veoliablockchain projects 12:20-12:40 Rie Yamaguchi (Tokyo University) Lifestyle Authentication 12:40-13:30 Lunch Buffet 13:30-13:50 Emmanuelle Anceaume (CNRS&Irisa Rennes) Sycomore 13:50-14:10 Bastien Teinturier (ACINQ) Lightning Networks 14:10-14:30 QuentinBramas (Université de Strasbourg) IOTA 14:30-14:50 Matthieu Lattapy(CNRS/Lip6) Analysis of financial transactions with link streams14:50-15:00 Coffee Break 15:00-15:20 Philippe Jacquet (Nokia BellLabs) Green Mining: Toward a less energetical impact of cryptocurrencies15:20-16:00 Antoine Herzog & Karim Ganem (IOV) BlockChainCommunication Protocol 16:00-16:20 Eitan Altman (Inria) Gametheoretical analysis of competition between miners 16:20-16:30 Break 16:30-16:45 Gewu Bu (SU/Lip6) G-IOTA & E-IOTA: Improvements ofIOTA 16:45-17:00 Yackolley Amoussou-Guenou (SU&CEA Noncooperative games and BFT-based blockchains 17:00-17:15 AntoineDurand (IRT SystemX) Stakecube: Combining Sharding and Proof-of-Stake tobuild Fork-free Secure Permissionless Disistributed Ledgers 17:15-17:30 Pierre Civit (Nexeo) Polygraph 17:30-17:45 Jose Horta (TelecomParis) Blockchain and Electrical Networks 17:45-18:00 MarianneBellotti (CNAM&CDD&SU&Dauphine) Cooperative games forAtomic Crosschain Swaps 18:00-18:20 Nadia Filali (Caisse desdépôts) Stable Coin

Transparent remote connectivity to short-range IoT devices
2019-06-05 14:00 - 15:00 | Doctoral Training Center (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Short-range wireless communication technologies such asBluetooth or ZigBee represent an important part of the Internet of Thingsecosystem.By design, this category of smart devices has physically limitedreachability inside their Wireless Personal Area Network (WPAN) and are notdirectly compatible with the TCP/IP stack.However, users may need toaccess them from anywhere at any moment.To address this problem, we designa new application-agnostic approach called RCM (Remote Connection Manager)enabling transparent communication between an application and out-of-rangedevices.It creates new IoT use cases by seamlessly mixing remote and localdevices.We implemented an open-source prototype for Bluetooth Low Energy(BLE) technology on top of Linux and Android BLE stacks and demonstratedits efficiency through experiments performed on real devices.

Tags: Transparent remote connectivity to short-range IoT devices, NatalyaRozhnova, Nokia Bell Labs France, IoT, no video

Stability and Metastability of Traffic Dynamics in Uplink RandomAccess Networks
2019-05-29 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
This talk is about the characterization of thestability, metastability, and the stationary regime of traffic dynamicsin a single-cell uplink wireless system. The traffic is represented interms of spatial birth-death processes, in which users arrive as a Poissonpoint process in time and space, each with a file to transmit to the basestation. The service rate of each user is based on its signal tointerference plus noise ratio (SINR), where the interference is from otheractive users in the cell. Once the file is fully transmitted, the userleaves the cell. We derive the necessary and sufficient condition fornetwork stability, which is independent of the specific path loss functionas long as it satisfies mild boundedness conditions. A novel observation,shown through mean-field analysis and simulations, is that for a certainrange of arrival rates, the network appears stable for possibly a longtime, but can suddenly become unstable. This property is calledmetastability which is widely known in statistical physics but rarelyobserved in wireless communication. Finally, using mean-field analysis,we propose a heuristic characterization of the network steady-state regimewhen it exists, and demonstrate that it is tight for the whole range ofarrival rates.

Manipulating and analyzing data with pandas
2019-05-20 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
The Python Data Analysis Library (pandas) provides datastructures and tools for manipulating and analyzing data. It is built ontop of NumPy, the core package for numerical computations in theScientific Computing Tools for Python (SciPy) ecosystem. The objective ofthis presentation is threefold: explain when one can benefit from usingpandas, describe its fundamental data structures, and give an overview ofthe data analysis tools it provides.

Slides:Download

Notebook :https://gist.github.com/ccomte/41b78e562552db683b1d855629afc9e0.

Real-time identification of IoT device types
2019-05-15 14:00 - 15:00 | Doctoral Training Center (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Identifying IoT devices types as they connect to thenetwork enables better devices and services management. However, real-timeidentification is very challenging in such heterogeneous environments. Wepresent a real-time classification approach, based on network featuresthat are extracted both from network communication characteristics and frompackets payload, to discriminate device types. Our solution automaticallyidentifies a newly connected device to the home network. Furthermore, weevaluate the performance of our method using a representative andheterogeneous real IoT devices set.

Community Structures in Social (Information) Networks
2019-04-24 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Communities play an important role in social networks.However while there exists a large body of work that formally models andstudies macroscopic properties of social networks such as the degreedistribution and diameter, less work is available on mathematical modelsfor microscopic properties of communities in social networks. Creating sucha model is the topic of this paper. Ideally this model should be simpleenough to allow a formal analysis, yet be expressive enough to provideinsights into important microscopic properties of communities in socialnetworks. For the talk we focus on a particular type of social networks,to which we refer to as information networks, where agents (individuals)share/exchange information. Sharing/exchanging of information is animportant aspect of the social networks, both for social networks that weform in our everyday lives, as well as for online social networks such asfor example Twitter. The model that we use to characterize informationnetworks has three important components: 1) the space of content that isbeing produced and consumed in the, 2) agent's interests and ability toproduce content, and 3) the utility that agents obtain for consuming andproducing content. An interesting outcome of the analysis of this model isthat albeit being very simple, indeed seems to be able to provideinteresting insights into the microscopic structure of informationcommunities. For example, the characterization of how content is beingproduced, i.e. which content each agent in a community produces, indeedmatches what has been experimentally observed in real-life social networks.It also provides insight into how to design efficient community detectionalgorithm.

Bio:

Peter Marbach was born inLucerne, Switzerland. He received the Eidg. Dipl. El.-Ing. (1993) from theETH Zurich, Switzerland, the M.S. (1994) in electrical engineering fromthe Columbia University, NY, U.S.A, and the Ph.D. (1998) in electricalengineering from the Massachusetts Institute of Technology (MIT),Cambridge, Massachusetts, U.S.A. He has been since 2000 with theDepartment of Computer Science of the University of Toronto. He has alsobeen a visiting professor at Microsoft Research, Cambridge, UK, at theEcole Polytechnique Federal at Lausanne (EPFL), Switzerland, and at theEcole Normale Supérieure, Paris, France, and a post-doctoral fellow atCambridge University, UK.His research interests are in the fields ofcommunication networks, in particular in the area of wireless networks,peer-to-peer networks, and social networks.

Communication Modeling in Wireless Body Area Networks (WBAN)
2019-04-17 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Wireless body area network has received a lot of attentionin the medical monitoring domain because of its wireless convenience.Considering the safety of user, the energy saving of WBAN devices, thesignals occlusion from human body and the effects of human mobility on theconnection between sensors, efficient and secure communication is still achallenge for intra WBAN communication. In this talk, we willpresent the basic model of the WBAN system we studied and its performanceanalysis. From that, we propose a Continuous-time Markov chain based modelrepresenting the broadcast communication in WBAN. This model allow uscompute varying kinds of performances of WBAN system. In addition, weexpand WBAN system to a theoretical model, and we studied efficientbroadcasting with the help of Labelling scheme.

Combatting toxicity in on-line conversations
2019-04-17 10:30 - 11:30 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Abusive behaviour in online social mediaplatforms (a.k.a. hate speech, toxicity, cyberbullying) hasforced major companies to hire hundreds of moderators, oreven buy a whole company to deal with the problem. Toxicitydetection (i.e., classify a post as toxic or not) has recently gainedpopularity, with two very successful workshops being organizedand an international challenge attracting thousands of systems.In previous work, it was shown that Recurrent Neural Networks (RNNs)achieve state of the art performance for the task of automatic toxicitydetection (Pavlopoulos et al. 2017a), while incorporatingclassification-specific attention mechanisms and user embeddings improvedfurther the overall performance of the RNNs (Pavlopoulos et al.2017b). Interestingly, the classification-specific attentionmechanism highlights suspicious words for free, without includinghighlighted words in the training data (Pavlopoulos et al.2017c). Despite this recent work, toxicity detection systems sufferfrom two major shortcomings. First, although most abusive posts appearwithin conversations (e.g., utterances, posted as replies to other postedutterances), the structure of the conversation is currently ignored andsystems are solely based on the text of each single post, in isolation,for their decisions. Second, systems only detect abusive posts;that is, current technology does not help users modify their poststhemselves to avoid being abusive. Such systems are primarily used tocensor online conversations on a platform, which often results in abusiveusers migrating to another platform (Chandrasekharan et al.2018). Instead, it has been argued, in both academic (Zhang et al.2018) and industrial circles that a more fruitfulapproach is to help users improve their posts in on-line conversations(e.g., by suggesting non-abusive rewrites). To address the firstproblem current research investigates a) the compilation of taxonomies ofcontext-aware toxicity and b) the creation of datasets of toxic utterances(context aware). To address the second problem we investigatethe creation of datasets with annotations on the word level to studydeeper the various forms of toxicity and the difficulty of itsrephrasing.

Introduction to Conda and Jupyter notebooks
2019-04-15 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
In this tutorial, we will see how to install the condapackage manager and use it to create a Jupyter environment. We’ll then gothrough various aspects of the Jupyter notebooks among which: usefulfeatures, notebook extensions, fundamental keyboard shortcuts and use ondistant machines (AWS or Hyperion).Prerequisite: your computer.
Link tothe notebook.

Hackathon Report
2019-04-10 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
On March 27th 2019, students from LINCS hosted a Hackathonsession on public data. The event gathered 20 participants from variousinstitutions.

In this talk, emceed by Celine Comte and Nathan deLara, participants will present their findings.

Journée d'exposé Inria-IMT sur les réseaux de communicationradio
2019-04-08 09:00 - 18:00 | Doctoral Training Center (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
09:30-10:15 L. DecreusefondBreak10:30-11:15 B. BlaszczyszynBreak11:30-12:15 M.Coupechoux

12:15-14:00 Lunchbreak

14:00-14:45 S. KalamkarBreak15:00-15:45 P.MartinsBreak16:00-16:45 F. BaccelliDiscussion

The effect of ramp constraints on coalitional storage games
2019-04-03 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Energy storage systems (ESS) are envisaged as a solution toa vast number of problems in Smart Grids, yet their prices are hindering amassive adoption at residential level. To facilitate such massivedeployments, we propose the shared investment in a battery among a groupof consumers. This is achieved by modeling the investment problem usingcooperative game theory. For an extensive class of relevant games, weprovide theoretical results guaranteeing the existence of a non-emptycore, i.e., a set of payoffs across consumers that are stable against theformation of sub-coalitions.

Tags: The effect of ramp constraintson coalitional storage games, Diego Kiedanski, Telecom ParisTech

Organizing a Python Package with Cookiecutter
2019-04-03 10:30 - 12:00 | Nice Room (EIT Digital), 23, avenue d'Italie, Paris, France
In this tutorial, we will see how to create and maintain aPython package, especially relying on Cookiecutter, by Audrey RoyGreenfeld, and PyCharm. Even for those who do not plan to create packagesin a near future, this tutorial is useful to learn how to structure aPython project, document it with Sphinx, test it with doctest, etc.Reference: https://my-toy-package.readthedocs.io/ . Prerequisite: yourcomputer + a Python distribution (e.g. Anaconda) + PyCharm.

Efficient Production of Training Data for Classification SupervisedLearning
2019-04-01 10:30 - 12:00 | LINCS Meeting Room 26, 23, avenue d'Italie, Paris, 75013,France
Supervised learning relies on the existence of trainingdata, typically labeled by human experts. The size and quality of thisdata has a critical impact on the quality of the learned inferred function.But human experts are expensive. We consider the particular case of aclassification problem. At each question, an expert is given two elementsand tells whether they belong to the same class, with a small probabilityof error. We propose a scheme ensuring the quality of the finalclassification while minimizing the number of questions asked to theexperts.

Thesis Defense : Smart grid-aware radio engineering in 5G mobilenetworks
2019-03-21 14:00 - 16:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
The energy demand in mobile networks is increasing due tothe emergence of new technologies and new services with higher requirements(data rates, delays, etc). In this context, the Mobile Network Operator(MNO) has to provide more radio and processing resources in its networkleading for higher financial costs. The MNO has no choice but to implementenergy saving strategies in all the parts of its infrastructure andespecially at the Radio Access Network (RAN).At the same time, theelectrical grid is getting smarter including new functionalities to balancesupply and demand by varying the electricity prices, allowing someaggregators to be part of the supply process and signing demand responseagreements with its clients. In the context of reliable smart grid, theMNO having thousands of evolved NodeB (eNB) spread over all the country,has to play major role in the grid by acting as a prosumer able to sellelectricity. In African Sub-Saharan countries however, the grid may be notreliable or even non existent, the MNO has no choice but to deploy aVirtual Power Plant (VPP) and rely partially or totally on it.In thisthesis, we study the interactions between the network operator and thegrid either reliable or not in both developed and developing countries. Weinvestigate both long term and short term optimal energy relatedmanagement, with the aim of minimising the operator's Total Cost ofOwnership (TCO) for energy per base station which is the sum of its CapitalExpenditure (CAPEX) and Operational Expenditure (OPEX) while satisfying thegrowing needs of its user traffic in the cell.The long term study enablesus to make semestral based investment decisions for the battery andrenewable energy sources dimensioning considering equipment performancedegradation, predictions on users traffic growth and electricity marketevolution over a long period of time counted in years. In thecase of being powered by a reliable smart grid, the short term policyhelps the operator to set on a daily basis, an optimal battery managementstrategy by performing electricity arbitrage or trading that takesadvantage of the electricity prices hourly fluctuations in order tominimize the MNO daily energy bill while respecting some rules on the usageof its equipments. In the case of a non reliable or off-gridenvironment, the operator is powered by hybrid sources coupling storage,diesel generators, solar power and the grid if the latter is operational.Here, we define a fixed order of priority on the use of these sources thatextends the battery lifetime and maintain its performance.

Tags:Thesis Defense : Smart grid-aware radio engineering in 5G mobile networks,Wael Labidi, Telecom SudParis, IMT, Samovar

Multiparametric Boltzmann sampling and applications
2019-03-13 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
I will describe the problem of multiparametric generation(which is #P-complete) and a relaxation of this problem (multiparametricBoltzmann sampling) for which we construct a fully polynomial algorithm.Our algorithm relies on the convex optimisation techniques, namely on theExponential Conic Solver (ECOS) constructed in 2013 by Domahidi, Chu andBoyd.The implementation of our algorithm is available on github. As apractical benchmark, we perform the tuning of regular grammars with over1k tuning parameters, 19k states and 357k transitions in about 2 hours(the previously known algorithm was exponential in the number ofparameters).In order to give impression of the numerous applications ofmultiparametric sampling, I will present six different examples:I.Software testing and code generation using lambda calculus;II. Non-uniformsparse random graphs;III. Belief propagation in tree decomposition for RNAdesign (Ponty, Will, Hammer);IV. Bose-Einstein condensate in quantumharmonic oscillator represented by integer partitions;V. Multiclassqueuing networks (Buši? , Bouillard, Rovetta);VI. CombinatorialLearning problems and connection with Maximum Likelihood approach.Theimplementation of our algorithm can be foundat https://github.com/maciej-bendkowski/boltzmann-brain

An information-theoretic perspective of tf–idf measures.
2019-03-11 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
Reference: Aizawa, Akiko. "An information-theoreticperspective of tf–idf measures." Information Processing & Management39.1 (2003): 45-65.

A simple discrete-time model for complex NFV accelerators
2019-03-06 14:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Network Functions Virtualization (NFV) is among thelatest network revolutions, bringing flexibility and avoiding networkossification. At the same time, all-software NFV implementations oncommodity hardware raise performance issues with respect to ASIC solutions.To address these issues, numerous software acceleration frameworks forpacket processing have appeared in the last few years. Common among theseframeworks is the use of batching techniques. In this context, packets areprocessed in groups as opposed to individually, which is required athigh-speed to minimize the framework overhead, reduce interrupt pressure,and leverage instruction-level cache hits. Whereas several systemimplementations have been proposed and experimentally benchmarked, thescientific community has so far only to a limited extent attempted to modelthe system dynamics of modern NFV routers exploiting batching acceleration.We fill this gap by proposing a simple generic model for suchbatching-based mechanisms, which allows a very detailed prediction ofhighly relevant performance indicators. These include the distribution ofthe processed batch size as well as queue size, which can be used toidentify loss-less operational regimes or quantify the packet lossprobability in high-load scenarios. We contrast the model prediction withexperimental results gathered in a high-speed testbed including an NFVrouter, showing that the model not only correctly captures systemperformance under simple conditions, but also in more realistic scenariosin which traffic is processed by a mixture of functions.

Processing of Aggregations over Big Data Streams
2019-02-27 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Online analytics and real-time data processing in mostadvanced IoT, scientific, business, and defense applications, relyheavily on the efficient execution of large numbers of Aggregate ContinuousQueries (ACQs). ACQs continuously aggregate streaming data and periodicallyproduce results such as max or average over a given window of the latestdata. Low operational cost and timely processing are of paramountimportance in these applications. To meet these requirements underfixed resources, we have developed incremental evaluation algorithms aswell as scheduling, stream partitioning and load shedding techniques forwindow-based aggregations. In this talk, we will first overview ouraforementioned contributions and then focus on two recent ones,(1) SlickDeque that optimizes the execution of multi-ACQs and(2) Concept-driven load shedding that adapts groupedaggregations to changing workloads.

Bio

Panos K. Chrysanthisis a Professor of Computer Science and the founding director of theAdvanced Data Management Technologies Laboratory in the School of Computingand Information at the University of Pittsburgh. He is also anAdjunct Professor at the Carnegie Mellon University and University ofCyprus. His research interests lie at the intersection of datamanagement (Big Data, Databases, Data Streams & Sensornetworks), distributed & mobile computing, operating and real-timesystems. He is a recipient of the NSF CAREER Award for hispioneer work on mobile data management, and he is an ACMDistinguished Scientist and a Senior Member of IEEE. He is also a recipientof the University of Pittsburgh Provost Award for Excellence in Mentoring(doctoral students). He is currently the Special Issues Coordinator for theDistributed and Parallel Databases Journal and on the editorial boardof several journals, and has repeatedly served as a program committeechair and member in all major data management conferences. He earnedhis BS degree from the University of Athens, Greece and his MS and PhDdegrees from the University of Massachusetts at Amherst.

Tropical Geometry of Deep Neural Networks 🌴 (continued)
2019-02-25 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
Reference: “Tropical geometry of deep neuralnetworks” (Liwen Zhang, Gregory Naitzat, Lek-Heng Lim, 2018)

Ending the Era of Information Overload and Cognitive Fatigue
2019-02-21 14:00 - 15:00 | Paris-Rennes-Nice Room (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
In the post-digital era we face the risk of cognitiveinsufficiency in the attempt of dealing with the increasing exposure tolarge volume of data like chats, emails, multimedia, etc. Today, BigData systems are still far from human level understand and so inadequate torescue our cognitive needs. State-of-art Natural Language Processingsystems are mostly successful in the understanding and linking of keyentities and concepts to external knowledge repositories in specificdomains. However, a higher level understanding of unstructured data isrequired to unveil the shades of meanings for a deeper semanticinterpretation.

In order to understand and interpret the growingvolume of unstructured data, we must go deeper to uncover the real meaningof content while doing it at scale and in real time. Towards this vision,this talk will present advanced machine learning algorithms to understandunstructured multi-modal contents (e.g., social posts, emails,multimedia) at a deep semantic level. This research enables users tounderstand, organize and absorb the ever-growing amount of informationalong with the different viewpoints therein. Our results are proved to behighly accurate with scalable training, to work with real-time queries,and to support fast dynamic updates. The output of this research is meantto change the way we interact, learn, teach - revolutionizing the way wecommunicate.

Bio

Alessandra Sala is the Head of the Bell-LabsAnalytics Research. In her prior appointment, she was the technicalmanager for the Data Analytics and Operations Research group in BellLabs Ireland. Before that, she held a research associate position in theDepartment of Computer Science at University of California Santa Barbara.During this appointment, she was a key contributor of several fundedproposals from National Science Foundation in USA and her research wasawarded with the Cisco Research Award in 2011. She focused her research onmodeling massive graphs with an emphasis on mitigating privacy threats forOnline Social Network users. Before that, she worked for two years aspost-doctoral fellow with the CurrentLab research group led by Prof. BenY.Zhao. Before UCSB, she completed her Ph.D in Computer Science atUniversity of Salerno, Italy.

Her research focus lies ondistributed algorithms and complexity analysis with an emphasis on graphalgorithms and privacy issues in large scale networks. In her previousresearch she has developed efficient distributed systems that supportrobust and flexible application level services such as scalable search,flexible data dissemination, and reliable anonymous communication.

Optimally Gathering Two Robots
2019-02-20 14:00 - 15:00 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
We present a self-stabilizing algorithm that ensures infinite time the gathering of two robots in the non-rigid ASYNC model. Tocircumvent established impossibility results, we assume robots areequipped with 2-colors lights and are able to measure distances between oneanother. Aside from its light, a robot has no memory of its past actions,and its protocol is deterministic. Since, in the same model, gathering isimpossible when lights have a single color, our solution is optimal withrespect to the number of used colors.

Tropical Geometry of Deep Neural Networks 🌴
2019-02-18 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
Reference: "Tropical geometry of deep neural networks" (LiwenZhang, Gregory Naitzat, Lek-Heng Lim, 2018)

Human Behavior is Low Dimensional
2019-02-13 14:00 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
Every person is unique and complex. But can wepredict anything about how large groups of people will behave? Inthe 1950s the writer Isaac Asimov imagined a field called“Psychohistory” that could mathematically describe the actions of largegroups. I will argue that in a certain way, aspects of that visionare in wide use today. To illustrate, I will describe examples frommy own work in which the “low dimensionality” of aggregate humanbehavior gives us leverage on a range of problems, from predicting networktraffic to detecting anomalous or malicious behavior in socialnetworks.

Fully Dynamic k-center Clustering
2019-02-06 14:00 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
Static and dynamic clustering algorithms are afundamental tool in any machine learning library. Most of the effortsin developing dynamic machine learning and data mining algorithmshave been focusing on the sliding window model (where at any givenpoint in time only the most recent data items are retained) or moresimplistic models. However, in many real-world applications onemight need to deal with arbitrary deletions and insertions. Forexample, one might need to remove data items that are notnecessarily the oldest ones, because they have been flagged ascontaining inappropriate content or due to privacyconcerns. Clustering trajectory data might also require to deal withmore general update operations. We develop a (2+?)-approximationalgorithm for the k-center clustering problem with "small" amortizedcost under the fully dynamic adversarial model. In such a model,points can be added or removed arbitrarily, provided that theadversary does not have access to the random choices of ouralgorithm. The amortized cost of our algorithm is poly-logarithmicwhen the ratio between the maximum and minimum distance between anytwo points in input is bounded by a polynomial, while k and epsilonare constant. Our theoretical results are complemented with anextensive experimental evaluation on dynamic data from Twitter,Flickr, as well as trajectory data, demonstrating the effectivenessof our approach.

This talk will mainly present ourwork published at TheWebConf 2018 which was nominated for the bestpaper award.

Limit distributions and Laplace's method
2019-02-04 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
I will present some tools based on generating functions inorder to study the limit distributions of some random variables.References:

Analytic Combinatorics (Flajolet & Sedgewick),available online for free, Asymptotic Methods in Analysis (de Bruijn).

Resource Allocation in Cloud Radio Access Networks: A CombinatorialOptimization Point of View
2019-01-30 14:00 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
In this presentation, we would like to focus on two wellknown NP-Hard problems and then provide a combinatorial optimizationview before proposing new and efficient solutions. Thus, we willfocus on two main topics: constrained resource allocation and full coveragehole in C-RAN. The first topic consists in determining the beststrategies to assign antennas (Remote Radio Head - RRH) demands toavailable edge data centers (pool of BaseBand Units - BBU) when jointlyoptimizing communication latency and resource consumption. The second topicaddresses the full coverage hole problem in C-RAN when reducing existinginterference. A deep Branch-and-Cut algorithm will be proposed anddiscussed. This approach is based on the description of new cutting planesto accelerate the convergence time even for large problem instances.

Algebra for Quantum Information
2019-01-28 15:00 - 16:30 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France

Thesis Defense : Auction-based Dynamic Resource Orchestration inCloud-based Radio Access Networks
2019-01-23 14:00 - 16:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
The paradigm of a Cloud-based RAN (C-RAN) is a key technologythat combines the enabling solutions for the 5G requirements in terms ofdata rate, scalability and cost savings. A C-RAN architecture is based ontwo key features namely, Centralization, wherein computational resourcesof base stations, namely Base Band Units (BBUs), are pooled together in acentral Cloud, and Virtualization, with the possibility that severalMobile Virtual Network Operators (MVNOs) share the radio resources and theBBU pool in order to reduce operational expenditure costs. In this thesis,we develop a theoretical framework for dynamic resource management in theC-RAN and derive the fundamental performance limits as well as the tradeoffs among various system parameters.

We specifically propose 3different resource allocation mechanisms that suit the C-RAN technology andhelp boost resource utilization efficiency. For each allocation mechanism,we set an auction framework to help generate high revenues.

We design atwo-level auction for the allocation of radio resources, in a scenariowith a central C-RAN operator, a set of MVNOs and their subscribed users.We tackle the problem of calendaring for radio resource reservation in theC-RAN, a natural context in which bandwidth calendaring can be appliedowing to its centralized architecture. An auction-based framework istailored so as to guarantee profit maximization and a market proof tomanipulation. We address joint radio and processing allocation in thecontext of C-RAN as a combinatorial auction.

Our approaches satisfyfundamental economic properties: truthfulness, individual rationality andcomputational efficiency. Numerical results demonstrates the performance ofour proposal in various network settings and show that our proposals canguarantee efficient outcomes.

Keywords: C-RAN, resource management,auctions

Internet Video Quality Inference from Encrypted Network Traffic
2019-01-16 14:00 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
Accurately monitoring application performance is becomingmore important for Internet Service Providers (ISPs), as usersincreasingly expect their networks to consistently deliver acceptableapplication quality. At the same time, the rise of end-to-end encryptionmakes it difficult for network operators to determine video stream quality--- including metrics such as startup delay, resolution, rebuffering,and resolution changes --directly from the traffic stream. In this talk wepresent general methods to infer streaming video quality metrics fromencrypted traffic using lightweight features. Our evaluation shows that ourmodels are not only as accurate as previous approaches, but they alsogeneralize across multiple popular video services, including Netflix,YouTube, Amazon Instant Video, and Twitch. The ability of our models torely on lightweight features points to promising future possibilities forimplementing such models at a variety of network locations along theend-to-end network path, from the edge to the core.Stemming from theoutcomes of this analysis, in the second part of the talk we presentNetwork Microscope, a novel lightweight system running at the home getawaythat analyzes traffic generated by DASH on-demand and live video streams.By first separating video flows from other sources of traffic by mappingDNS requests, the system tracks traffic patterns to infer key videoquality metrics such as average bitrate and re-buffering events. Moreover,the system exploits novel algorithms that use simple probing techniques,i.e. lightweight pings and traceroutes, to take advantage of the homenetwork vantage point to pinpoint where potential root causes hampering thestreaming process might be located.

Bio

FrancescoBronzino is a Research Scientist in the Network Protocol and SystemsResearch department at Bell Labs Paris-Saclay. Francesco received his Ph.D.in Electrical and Computer Engineering from WINLAB (Wireless InformationNetwork Lab) at Rutgers University, working on designing and developingname-based services for future Internet and mobile network architectures.For his thesis work he was awarded the "Graduate Program AcademicAchievement Award” from the department. Before joining Bell Labs,Francesco spent two years as a Post-Doctoral research fellow in the MiMovegroup at Inria, Paris, where worked on developing network systems aimedat supporting and enhancing network services from home and access networks.Francesco's research interests broadly focus on the Internet infrastructureand the services that populate it, with interest in understandingsystems, protocols and new technologies that can enhance servicedevelopment and performance.

https://youtu.be/9A8XSBQYIC0

Multi-armed bandits: Bayesian vs frequentist (2)
2019-01-07 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
Lorenzo Maggi will present two approaches of multi-armedbandits: Bayesian and frequentist, based on the papers:

Tsitsiklis, J. N. (1994). A short proof of the Gittins index theorem.The Annals of Applied Probability, 194-199.
J. C. Gittins, BanditProcesses and Dynamic Allocation Indices, Journal of the Royal StatisticalSociety (1979)

Link to the slides: MAB - Bayesian_vs_Frequentist

Thesis Defense
2018-12-19 10:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France

Protecting encrypted data against key exposure
2018-12-12 14:00 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
Hardening data protection using multiple methods rather thansolely encryption is of paramount importance when considering continuousand powerful attacks to spy private and confidential information. Ourresearch focuses on reinforcing data protection using a combination of datafragmentation, encryption, and dispersion. Each operation participates inthe increasing of the protection level. We aim at minimizing the additionalprocessing costs due to data fragmentation and dispersion.

Ranking online social users by their influence
2018-12-05 14:00 - 15:00 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
TBA

https://youtu.be/QA8ON74zvag

Too Many SDN Rules, Compress Them Using Minnie
2018-11-28 14:00 - 15:00 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
Software Defined Networking (SDN) is gaining momentum with thesupport of major manufacturers. While it brings flexibility in themanagement of flows within the data center fabric, this flexibility comesat the cost of smaller routing table capacities. Indeed, the TernaryContent Addressable Memory (TCAM) needed by SDN devices has smallercapacities than CAMs used in legacy hardware. To solve this problem, weinvestigated compression techniques to maximize the utility of SDN switchesforwarding tables and created MINNIE. MINNIE dynamically compresses SDNrules without a noticeable impact on quality of service. We validate oursolution, with intensive simulations for well-known data centertopologies, to study its efficiency and compression ratio for a largenumber of forwarding rules. Our results indicate that MINNIE scales well,being able to deal with around a million of different flows with less than1000 forwarding entry per SDN switch, requiring negligible computationtime. To assess the operational viability of MINNIE in real networks, wedeployed it on a k = 4 fat-tree data center topology emulated testbed. Wedemonstrate on one hand, that even with a small number of clients, thelimit in terms of number of rules is reached if no compression isperformed, increasing the delay of new incoming flows. MINNIE, on theother hand, reduces drastically the number of rules that need to bestored, with no packet losses, nor detectable extra delays if routinglookups are done in ASICs. Hence, both simulations and experimentalresults suggest that MINNIE can be safely deployed in real networks,providing compression ratios between 70% and 99%.

Multi-armed bandits: Bayesian vs frequentist
2018-11-26 10:30 - 12:00 | Telecom Paristech, I338 (3rd floor), 23, avenue d'Italie,Paris, 75013, France

Thesis Defense : Hyperfractals for the Modelling of WirelessNetworks
2018-11-21 16:00 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
We are on the verge of an industrial revolution that will makecities smarter, industries more efficient and people’s life easier.Urban communication will place a critical role in this revolution yet dueto their heterogeneity and the particularities of the urban environment,the chosen models for representation can no longer be ones specific tocellular networks.
This thesis proposes a new model for wirelesscommunications in urban setting by exploiting stochastic geometry andfractal geometry. It designs a model in two options, the hyperfractalmodel for vehicles and the hyperfractal model for infrastructure. Throughout the thesis, we derive tools that allow the manipulation of thismodel, provide data fitting techniques and demonstrate its utility andease of use through two applications in wireless metricscomputation.

https://youtu.be/eOp35QVnGKc

Canopus: Scalable Consensus for Permissioned Blockchains
2018-11-19 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
A critical problem with the consensus protocols underlyingblockchains is that they do not scale well. As the number of participantstrying to achieve consensus increases, increasing network traffic fromtopology-oblivious broadcasts can quickly overwhelm the network, or, whenusing centralized consensus protocols, overwhelm the central coordinator.Thus, achieving strong consensus is typically restricted to a handful ofparticipants, or systems must resort to weaker forms of consensus, suchas those using proof of work. To address this problem, we proposeCanopus, a highly-parallel consensus protocol that exploits modern datacenter network topology, parallelism, and consensus semantics to achievescalability. Our key insight is to make network communication patternstopology-aware. In our prototype implementation, Canopus achieves rates ashigh as 5m linearizable transactions/second over 27 nodes distributedacross 7 datacenters. I will also discuss a recent extension, ResilientCanopus, that makes Canopus Byzantine Fault Tolerant.
(Joint work withSajjad Rizvi and Bernard Wong at the University of Waterloo)

The Forward-Backward Embedding of Directed Graphs
2018-11-14 14:00 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
We introduce a novel embedding of directed graphs derived fromthe singular value decomposition (SVD) of the normalized adjacency matrix.Specifically, we show that, after proper normalization of the singularvectors, the distancesbetween vectors in the embedding space areproportional to the mean commute times between the corresponding nodes by aforward-backwardrandom walk in the graph, which follows the edgesalternately in forward and backward directions. In particular, two nodeshaving many commonsuccessors in the graph tend to be represented by closevectors in the embedding space. More formally, we prove that ourrepresentation of thegraph is equivalent to the spectral embedding of someco-citation graph, where nodes are linked with respect to their common setof successors in the original graph. The interest of our approach is thatit does not require to build this co-citation graph, which is typicallymuch denser than the original graph. Experiments on real datasets show theefficiency of the approach.

SlidesThe_Forward_Backward_Embedding_of_Directed_Graphs__beamer_Download

A tutorial on hidden Markov models
2018-11-12 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
Achille Salaün will present a tutorial on Hidden MarkovModels based on the reference:

Lawrence R. Rabiner, A Tutorial onHidden Markov Models and Selected Applications in Speech Recognition,1989

Some Recent Advances on the Application of Game Theory toNetworking
2018-11-07 14:00 - 15:00 | Doctoral Training Center (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
In the first part of the talk we shall consider game theory asa tool for analyzing and predicting the evolution of the Internet topology.We study the structure and evolution of the Internet's Autonomous System(AS) interconnection topology as a game with heterogeneous players thatincorporate reliability considerations. We also consider the case whereutility (or monetary) transfers are allowed between the players. In thisnetwork formation game, the utility of a player depends on the networkstructure, e.g., the distances between nodes and the cost of links. Weanalyze static properties of the game, such as the prices of anarchy andstability, as well as the (novel) price of reliability, and provideexplicit results concerning the generated topologies. Furthermore, weprovide dynamical analysis of topological quantities, demonstrate linearconvergence rate and explain the prevalence of some “network motifs”,i.e., sub-graphs that are expected to appear frequently in the network.Through real-world data, we provide encouraging support to ourpredictions.
Research on the application of game theory in the context ofnetworking has focused on non-cooperative games, where the selfish agentscannot reach a binding agreement on the way they would share theinfrastructure. Many approaches have been proposed for mitigating thetypically inefficient operating points. However, in a growing number ofnetworking scenarios, selfish agents are able to communicate and reach anagreement. Hence, the degradation of performance should be considered atan operating point of a cooperative game, e.g., the Nash bargainingsolution, core or nucleolus. In the second part of the talk weshall describe a body of work that attempts to lay foundations for theapplication of cooperative game theory to fundamental problems innetworking, with a focus on routing. Depending on the scenario, we willreach conclusions on how cooperation among agents affects their ownperformance as well as that of the system. We will discuss network designguidelines that follow from our findings.
Bio:
Ariel Orda is the Herman& Gertrude Gross Professor of Communications at the Technion. Hereceived his BSc (summa cum laude), MSc and PhD at the Technion. He is anIEEE Fellow. During 1.1.2014-12.31.2017, he served as the Dean of theViterbi Faculty of Electrical Engineering at the Technion. His researchinterests include network routing, the application of game theory tonetworking, survivability, QoS provisioning and wireless networks. Hereceived several awards for research, teaching, and service.

Belief Propagation in Bayesian Networks
2018-11-05 10:30 - 12:00 | Telecom ParisTech (Main Building), 46, rue Barrault, Paris,75013, France
Céline Comte will present Belief Propagation in BayesianNetworks based on the two references:

J. Pearl, Reverend Bayes onInference Engines: A Distributed Hierarchical Approach. 1982.
J. Pearl,Fusion, propagation, and structuring in belief networks. 1986.

Slides: Network Theory - Belief propagation in Bayesian Networks

Two new methods for graph classification
2018-10-24 14:00 - 15:00 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
Graph classification has recently received a lot of attentionfrom various fields of machine learning e.g. kernel methods, sequentialmodeling or graph embedding. We address the problem of graph classificationbased only on structural information. Most standard methods require eitherthe pairwise comparisons of all graphs in the dataset or the extraction ofad-hoc features to perform classification. Those methods respectively raisescalability issues when the number of samples in the dataset is large, andflexibility issues when discriminative information is characterized byexotic features. We propose two approaches for graph classification. Firstwe propose a simple baseline algorithm that uses spectral information asgraph representation. Second, we propose a new sequential approach usingrecurrent neural networks to offer new possibilities for graphanalysis in terms of scalability and feature learning.

Some Architectural Considerations for Algorithms in Python
2018-10-24 10:00 - 11:30 | Doctoral Training Center (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
In this talk, we address a very common and practical questionfor the programmer: what should be the general architecture of our code? Inparticular, when we plan to implement an algorithm, should we write it asa function that takes arguments and parameters as input, and gives itsresult as output? Or should we write a dedicated class? If so, how shouldwe organize this class? How to ensure compatibility, easiness to implementand to maintain the code, rapidity to implement new functionalities? Howto design the architecture in order to facilitate the composition ofseveral algorithms?
After presenting the problem and its challenges, wepresent an architecture inspired from the package Scikit-learn, then avariant with a more functional-style flavor. Lastly, we show how to use"properties" and especially "cached properties" to ensure a lazy evaluationwhile keeping the code very easy to write, maintain andextend.

The notebook for the presentation is herehttps://gist.github.com/francois-durand/08590af1228ed5c62adb02cb9ef4b9f4.

The Physics of Spectral Graph Embedding
2018-10-17 14:00 - 15:00 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
Learning from data strutured as a graph usually requires toembed this graph in some vector space of low dimension. The most populartechnique relies on the spectral decomposition of the Laplacian. The focusof this talk will be on the ``physics" of this spectral graph embedding,in various fields like thermodynamics, mechanics and electricity. Thesephysical interpretations both suggest natural extensions to existingapproaches and shed light on the crucial question of the choice of theLaplacian.

Part of this work was presented at the Allertonconference:
T. Bonald, A. Hollocou, M. Lelarge, Weighted SpectralEmbedding of Graphs, Allerton conference, 2018

The Roaming Edge
2018-10-10 14:00 - 15:00 | Doctoral Training Center (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Edge computing provides a new way to implement services withmany unique advantages. While many edge computing solutions have beenimplemented within different network infrastructures, in this talk, wewill explore the "roaming" edge of the Internet --- in vehicles -- wherecomputing services are increasingly important, and appropriate edgecapabilities need to be rolled out. We will describe a few vehicularapplications often with significant needs of audio-visual processing, anddescribe an edge platform for vehicles to meet such goals.

Finding structure with randomness: Probabilistic algorithms forconstructing approximate matrix decompositions
2018-10-08 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
Nathan de Lara will present the article

Halko, N.,Martinsson, P. G., & Tropp, J. A. (2011).
Finding structure withrandomness: Probabilistic algorithms for constructing approximate matrixdecompositions. SIAM review, 53(2), 217-288.

Of Kernels and Queues: when network calculus meets analyticcombinatorics
2018-10-03 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Stochastic network calculus is a tool for computing errorbounds on the performance of queueing systems. However, deriving accuratebounds for networks consisting of several queues or subject tonon-independent traffic inputs is challenging. In this paper, weinvestigate the relevance of the tools from analytic combinatorics,especially the kernel method, to tackle this problem. Applying the kernelmethod allows us to compute the generating functions of the queue statedistributions in the stationary regime of the network. As a consequence,error bounds with an arbitrary precision can be computed. In thispreliminary work, we focus on simple examples which are representative ofthe difficulties that the kernel method allows us to overcome.
(Joint workwith Anne Bouillard)

Irrational Agents and the Power Grid
2018-09-26 14:00 - 15:00 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
For decades power systems academics have proclaimed the needfor real time prices to create a more efficient grid. The rationale iseconomics 101: proper price signals will lead to an efficient outcome. Inthis talk we argue that competitive equilibrium theory does support thereal-time price paradigm, provided we impose a particular model ofrationality. However that this standard model of consumer utility does notmatch reality: the products of interest to the various "agents" are complexfunctions of time. The product of interest to a typical consumer is onlyloosely related to electric power -- the quantity associated with pricesignals. There is good news: an efficient outcome is easy todescribe, and we have the control technology to achieve it. We needsupporting market designs that respect dynamics and the enormous fixedcosts that are inherent in power systems engineering, recognizing that weneed incentives on many time-scales. Most likely the needed economic theorywill be based on an emerging theory of efficient and robust contractdesign.

The lecture will focus on the “efficient outcome”, obtainedthrough the distributed control approaches of Busic & Meyn. Itis hoped that the economic solutions will be identified in real-time by theend of the lecture!

Convex Optimization and Duality
2018-09-24 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
The talk is based on the Online Course Convex Optimization byStephen Boyd
and the Book Convex Optimization by Stephen Boyd and LievenVandenberghe.

Slides

Regular Inference on Artificial Neural Networks
2018-09-19 14:00 - 15:00 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
This lecture explores the general problem of explaining thebehavior of Artificial Neural Networks (ANN). The goal is to construct arepresentation which enhances human understanding of an ANN as a sequenceclassifier, with the purpose of providing insight on the rationale behindthe classification of a sequence as positive or negative, but also toenable performing further analyses, such as automata-theoretic formalverification. In particular, a probabilistic algorithm for constructing adeterministic finite automaton which is approximately correct with respectto an artificial neural network is proposed.

Asymptotic Optimal Control of Markov-Modulated Restless Bandits
2018-09-12 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
In this talk we will discuss optimal control subject tochanging conditions (a changing environment). This is an area that recentlyreceived a lot of attention as it arises in numerous situations inpractice. Some applications being cloud computing systems with fluctuatingarrival rates, or the time-varying capacity as encountered in power-awaresystems or wireless downlink channels. To study this, we focus on arestless bandit model, which has proved to be a powerful stochasticoptimization framework to model scheduling of activities. This work is afirst step to its optimal control when restless bandits are subject tochanging conditions.

We consider the restless bandit problem in anasymptotic regime, which is obtained by letting the population of banditsgrow large, and letting the environment change relatively fast. We presentsufficient conditions for a policy to be asymptotically optimal and showthat a set of priority policies satisfies these. Under an indexabilityassumption, an averaged version of Whittle's index policy is proved to beinside this set of asymptotic optimal policies. The performance of theaveraged Whittle's index policy is numerically evaluated for a multi-classscheduling problem.

JiT acceleration in Python: introduction to Numba
2018-09-10 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
This tutorial will explain how to easily turn slow Python intofast Python with the numba package. Speed up of X2000 will be demonstratedon hyperion, Lincs' brand new machine. A notebook will be provided forthose who want to try on their own machine. Quick guide to notebookinstallation:

https://github.com/balouf/JupTricks/blob/master/NoteBookGuide.ipynb

Protecting privacy in dynamic decision making
2018-08-29 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Motivated by the increasing ubiquity of large-scaledata
collection infrastructures, we investigate how to protectsensitive
information in dynamic resource allocation problems. The centralquestion
is: how should one make resource allocation decisions such thatthese
decisions, if observed and analyzed by an adversary, do notinadvertently
reveal private information of the decision maker? In thistalk we will
examine two well known decision problems, path planning andactive learning,
and in each case provide tight information-theoreticupper and lower bounds
on the amount of additional resources required fora given level of privacy.

Bio: Kuang Xu was born in Suzhou,China. He received the B.S. degree in
Electrical Engineering (2009) fromthe University of Illinois at
Urbana-Champaign, Urbana, Illinois, USA,and the Ph.D. degree in Electrical
Engineering and Computer Science (2014)from the Massachusetts Institute of
Technology, Cambridge,Massachusetts, USA. He was a postdoctoral fellow at
the MicrosoftResearch-Inria Joint Center in Paris, France (2014-2015),
hosted byLaurent Massoulié. His research interests lie in the fields of
appliedprobability theory, optimization, and operations research, seeking
tounderstand fundamental properties and design principles oflarge-scale
stochastic systems, with applications in queueing networks,healthcare,
privacy and statistical learning theory. He has receivedseveral awards
including a First Place in INFORMS George E. NicholsonStudent Paper
Competition, a Best Paper Award, as well as a Kenneth C.Sevcik Outstanding
Student Paper Award from ACM SIGMETRICS.

On Network Connectivity for Distributed Machine Learning
2018-08-02 14:00 - 15:00 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
Abstract:
Many learning problems are formulated asminimization of some loss function on a training set of examples.Distributed gradient methods on a cluster are often used to this purpose.In this talk we discuss how the variability of task execution times atcluster nodes affects the system throughput. In particular, a simple butaccurate model allows us to quantify how the time to solve the minimizationproblem depends on the network of information exchanges among the nodes.Interestingly, we show that, even when communication overhead may beneglected, the clique is not necessarily the most effective topology, ascommonly assumed in previous works.

Biography:
Giovanni Neglia receiveda Ph.D. degree in Computer Science, Electronics and Telecommunicationsfrom the University of Palermo, Italy, respectively in 2005. In 2005 hewas a research scholar at the University of Massachusetts Amherst,visiting the Computer Networks Research Group. Since 2006 he worksat Inria Sophia Antipolis, France. He is associate editor for ElsevierComputer Communications journal and recipient of several best paper awards(ITC, Greencomm, NetSciCom, VTC, Valuetools, Bionetics). His currentresearch interests include cache networks and distributed optimization.

In the wild Sensing for Smarter Cities and Healthcare
2018-06-27 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Modern cities are alive with sensors, such as smartphones,wearables, vehicles, and cameras. Realizing our plans for smartenvironments of the future necessitates a radical transformation in the waythese devices perceive and interact with our highly mobile environments.Smart city services are dependent on large-scale and low-cost dataacquisition. To achieve this, we rehash these city-wide devices in anattempt towards developing a mobility-aware multimodal sensing framework.Cities contain many moving objects and we show that being aware of thismobility enables efficient sensor reuse even when monitoring movingobjects/people. Such a synergy has the potential to change the way ourcities function; from optimizing transportation to provisioning cityservices, and further to legal and economic framework, and regulations.My research leverages existing ubiquitous devices and expands their role toinnovate new services, ranging from large-scale video analytics topedestrian safety. We innovate on smartphone sensors and fitness trackersfor in-street detection. Through unobtrusive in-the-wild sensing we gaugepedestrian risk and enable city-scale pedestrian safety services.Infrastructure cameras, often mounted for surveillance and trafficmonitoring, are among other prevalent devices in our cities that areunderutilized. We devise mobility-aware scheduling for steerableinfrastructure cameras to capture views for multiple concurrent analyticsapplications. We show how commonplace sensors can be used beyond theirintended purpose. In building a framework involving widespreadheterogeneous sensors and mobility-awareness, we introduce new avenues forsmart city analytics. We expand this vision of sensor reuse to healthcaretechnology to enable continuous monitoring of physical performance duringworkouts. We also explore novel sensors for early diagnosis of lung and eyedisorders.

2018 LINCS Workshop
2018-06-19 00:00 - 2018-06-20 00:00 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
Workshop

LINCS and its Scientific Committee

June 19th and20th, 2018

LINCS - 23 avenue d’Italie, 4th floor – 75013Paris

Agenda

June 19th

Welcome
09:00 / 09:15

Opening -Prof. Daniel Kofman
09:15 / 09:30

Invited talk from ScientificCommittee-1

Pricing and Bidding Strategies for Cloud Computing SpotInstances

Prof. Roch Guerin – Washington University
09:30 /10:15

Talks from LINCS – 1:

Novel market approach for locallybalancing renewable energy production and flexible demand

Dr. Jose Horta(joint work TPT, Nokia, EDF)

Deep Representation for PatientVisits from Electronic Health Records

Dr. Marc Lelarge - INRIA
10:15 /10:45

Coffee break
10:45 /11:15

Invited talk from the Scientific Committee -2

ElasticCorporate WAN as a Service over Public Clouds

Prof. Israel Cidon -Technion
11:15 / 12:00

Talks from LINCS – 2

Hierarchical graphclustering through edge sampling

Prof. Thomas Bonald – (joint workTPT-IMT and INRIA)

Performance of Balanced Fairness in ResourcePools: A Recursive Approach

Dr. Fabien Mathieu – (joint work Nokia andTPT)
12:00 / 12:30

Lunch
12:30 / 14:15

Talks from LINCS 3 –PhDs and PostDocs’ presentations: 3mn for presenting the thesis /work.
14:15 / 16:00

Coffee break
16:00 / 16:30

Invited talkfrom the Scientific Committee -3

Title TBC

Prof. PeterDruschel
16:30 / 17:15

Invited talk from the Scientific Committee-4

Dictionary Learning Based on Sparse Distribution Tomography

Prof.Patrick Thiran - EPFL
17:15 / 18:00

Social Event (Diner)

directions to social event
19:30 / 22:00

June20th

Welcome
09:00/ 09:30

Invited talk from the ScientificCommittee -5

Title TBC

Prof. Nick Bambos – StanfordUniversity
09:30 / 10:15

Coffee break
10:15 / 10:45

Talks fromLINCS -4

Digital assistance for IoT service recommendation toend-users

Dr. Ludovic Noirie (Joint Work Nokia -UMPC)

Multilevel Multipath Paris Traceroute

Prof. TimurFriedman (Joint Work UPMC-INRIA)
10:45 / 11:15

Poster Session
11:15/ 12:15

Lunch
12:15 / 14:00

Talks from LINCS -5

Narrowingthe gap between QoS metrics and Web QoE using Above-the-Fold metrics

Dr.Diego Da Hora (Joint Work INRIA-TPT)

Beyond Surveys and SocialMedia: Understanding Online News Consumption Habits from Usage Data

Dr.Zied Ben Houidi (Joint Work INRIA-Nokia)

ClickNF: a Modular Stackfor Custom Network Functions

Dr. Massimo Gallo (Joint WorkNokia-TPT)
14:00 / 14:45

Poster Session
14:45 / 15:45

Coffeebreak
15:45 / 16:15

Invited talk 1 -

Wi-Fi Goes to Town:Techniques for Rapid Picocell Switching for Extreme Mobility

Prof. KyleJamieson – Princeton University
16:15 / 16:45

Invited talk2

Title TBC

Prof. Nick Feamster - Princeton University
16:45 /17:15

Invited talk 3

Robust Inference of Inter-ASInterconnections

Prof. Reza Rejaie –University of Oregon
17:15 /17:45

Conclusion and End of event
17:45 /18:00

Wrap-up

- Scientific Committee and ExecutiveCommittee
18:15 / 18:45

On the notion of Dimension of Unimodular Random Graphs
2018-06-07 14:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
In this talk we will define notions of dimension on unimodularrandom
graphs. The key point in this definition is unimodularity which isused indispensably and distinguishes this view point from the previousnotions which are defined in the literature. Other notions which arerelated to the notion of dimension such as volume growth are discussedwhich provide a toolset to calculate the dimension. Several examples ofsuch graphs will be discussed in relation with the theory of pointprocesses and that of unimodular graphs. Different methods for findingupper bounds and lower bounds on the dimension will also bepresented and illustrated through these examples.

On Mapping the Interconnections in Today’s Internet
2018-06-06 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Internet interconnections are the means by which networksexchange traffic between one another. These interconnections are typicallyestablished in facilities that have known geographic locations, and areowned and operated by so-called colocation and interconnection serviceproviders (e.g., Equinox, CoreSite, and EdgeConneX). These previouslyunder-studied colocation facilities and the critical role they play insolving the notoriously difficult problem of obtaining a comprehensive viewof the structure and evolution of the interconnections in today’sInternet are the focus of this talk.

We present mi2, a new approach formapping Internet interconnections inside a given colocation facility. Weinfer the existence of interconnections from localized traceroutes and usethe Belief Propagation algorithm on a specially defined Markov Random Fieldgraphical model to geolocate them to a target facility. We evaluate mi2 byapplying it to a diverse set of US-based colocation facilities. In theprocess, we compare our results against those obtained by two recentlydeveloped related techniques, and discuss observed discrepancies thatresult from how the different techniques determine the ownership of(border) routers. We also report on drastic changes in today’s Internetinterconnection ecosystem (e.g., new infrastructures in the form of cloudexchanges that offer new types of interconnections) and reflect upon theirfar-reaching implications for obtaining an accurate and comprehensive mapof the Internet’s interconnections.

This is joint work with RezaMotamedi, Bahador Yeganeh (University of Oregon), BalakrishnanChandrasekaran (Technische Universität Berlin), Bruce M. Maggs (DukeUniversity/Akamai Technologies) and Walter Willinger (NIKSUN, Inc.)

Machine Learning approaches for Computer Vision applications
2018-05-23 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Machine Learning, as the most successful paradigm ofArtificial Intelligence to date, has shown its great potential inrestructuring all aspects in our everyday life, e.g. through decisionmaking support, autonomous agents/vehicles, intelligent manufacturing andweb-scale/social network analysis, to name a few. In this talk, I willgive an overview of my recent work on kernel-based learning and neuralnetworks as generic approaches for pattern classification. Applicationsrelated to Computer Vision problems will also be presented, as well asextensions to time series data analysis.

Slides of the presentation

Online influence maximization
2018-05-14 17:00 - 17:30 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
We will talk about the online influence maximization problem insocial networks under the independent cascade model. Specifically, we aimto learn the set of “best influencers" in a social network online withunknown influence probabilities while repeatedly interacting with thenetwork. We address the challenges of (i) combinatorial action space,since the number of feasible influencer sets grows exponentially with themaximum number of influencers, and (ii) limited feedback, since only theinfluenced portion of the network is observed. Under a stochasticsemi-bandit feedback, we propose and analyze IMLinUCB, acomputationally
efficient UCB-based algorithm. Our bounds on thecumulative regret are polynomial in all quantities of interest, achievenear-optimal dependence on the number of interactions and reflect thetopology of the network and the activation probabilities of its edges,thereby giving insights on the problem complexity. To the best of ourknowledge, these are the first such results. Our experiments show that inseveral representative graph topologies, the regret of IMLinUCB scales assuggested by our upper bounds. IMLinUCB permits linear generalization andthus is both statistically and computationally suitable for large-scaleproblems. Our experiments also show that IMLinUCB with lineargeneralization can lead to low regret in real-world online influencemaximization.

Topic detection and classification in Twitter
2018-05-14 16:30 - 17:00 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
In this talk we introduce a novel information propagationmethod in Twitter, while maintaining a low computational complexity. Theproposed method first employs Joint Complexity, which is defined as thecardinality of a set of all distinct factors of a given string representedby suffix trees, to perform topic detection. Then based on the nature ofthe data, we apply the theory of Compressive Sensing to perform topicclassification by recovering an indicator vector, while reducingsignificantly the amount of information from tweets. Based on the spatialcorrelation of tweets and the score matrices, we apply a framework tocomplete matrices from a small number of random sample scores. We exploitdatasets in various languages collected by using the Twitter streaming APIand achieve better classification accuracy when compared withstate-of-the-art methods.

On finding dense subgraphs and events in social media
2018-05-14 16:00 - 16:30 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
Social media contain information shared by hundreds of millionsof users across the world and provide one of the richest dataset created byhuman activity. Social media distinguish themselves from traditional mediaas users can follow news channels, but they can also be the ones reportingupdates on events.
In our research, we focus on the detection of disasterevents, such as earthquakes, terrorist attacks, mass shootings, airstrikes, etc. We develop tools to extract a useful description of an eventvia a graph-based approach and we show that our algorithm can incorporateinformation from several sources, such as both social and mainstreammedia.
Complementary to our work on event detection, we study severaldefinitions of meaningful subgraphs in a graph. Density is a very goodmeasure of importance and cohesiveness in graphs and dense subgraphs havebeen found to represent communities in social networks, or to indicate thepresence of real-world events in a graph-of-words. We investigate bothsemantic and structural properties of dense subgraphs and we developalgorithms that can successfully scale to real-world graphs.

Hierarchical clustering: Objective functions and algorithms
2018-05-14 15:00 - 15:30 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
Hierarchical clustering is a recursive partitioning of adataset into clusters at an increasingly finer granularity. Motivated bythe fact that most work on hierarchical clustering was based on providingalgorithms, rather than optimizing a specific objective, Dasgupta framedsimilarity-based hierarchical clustering as a combinatorial optimizationproblem, where a `good' hierarchical clustering is one that minimizes somecost function. He showed that this cost function has certain desirableproperties.
We take an axiomatic approach to defining `good' objectivefunctions for both similarity and dissimilarity-based hierarchicalclustering. We characterize a set of “admissible” objective functions(that includes Dasgupta's one) that have the property that when the inputadmits a `natural' hierarchical clustering, it has an optimalvalue.
Equipped with a suitable objective function, we analyze theperformance of practical algorithms, as well as develop better algorithms.For similarity-based hierarchical clustering, Dasgupta showed that thedivisive sparsest-cut approach achieves an O(log^{3/2} n)-approximation. Wegive a refined analysis of the algorithm and show that it in fact
achievesan O(\sqrt{log n})-approx. (Charikar and Chatziafratis independentlyproved that it is a O(\sqrt{log n})-approx.). This improves upon theLP-based O(logn)-approx. of Roy and Pokutta. For dissimilarity-basedhierarchical clustering, we show that the classic average-linkagealgorithm gives a factor 2 approx., and provide a simple and betteralgorithm that gives a factor 3/2 approx..
Finally, we consider`beyond-worst-case' scenario through a generalisation of the stochasticblock model for hierarchical clustering. We show that Dasgupta's costfunction has desirable properties for these inputs and we provide a simple1 + o(1)-approximation in this setting.

Joint work with Varun Kanade,Frederik Mallmann-Trenn, and Claire Mathieu.

On graph reconstruction via empirical risk minimization
2018-05-14 14:30 - 15:00 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
The problem of predicting connections between a set of datapoints finds many applications, in systems biology and social networkanalysis among others. We focus on the graph reconstruction problem, wherethe prediction rule is obtained by minimizing the average error over alln(n-1)/2 possible pairs of the n nodes of a training graph. Our firstcontribution is to derive learning rates of order O(log n / n) for thisproblem, significantly improving upon the slow rates of order O(1/?n)established in the seminal work of Biau & Bleakley (2006).Strikingly, these fast rates are universal, in contrast to similarresults known for other statistical learning problems (e.g.,classification, density level set estimation, ranking, clustering) whichrequire strong assumptions on the distribution of the data. Motivated byapplications to large graphs, our second contribution deals with thecomputational complexity of graph reconstruction. Specifically, weinvestigate to which extent the learning rates can be preserved whenreplacing the empirical reconstruction risk by a computationally cheaperMonte-Carlo version, obtained by sampling with replacement B << n2pairs of nodes. Finally, we illustrate our theoretical results bynumerical experiments on synthetic and real graphs.

Building and exploiting large graphs connecting images
2018-05-14 14:00 - 14:30 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
In this talk, I will present recent works on large-scalesimilarity search, and show that it is possible to build a graphconnecting up to one billion of images on a regular server, assuming thata vector representation is provided for each image. In particular, I willintroduce a new method based on hierarchical navigable small words graph,which explicitly exploits the graph structure in the encoding stage(compression) of each vector so that the indexing structure can fit intomemory. I will then discuss applications involving large graphs, includingsemi-supervised classification and unsupervised learning.

Modularity for soft-graph clustering
2018-05-14 12:00 - 12:30 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
Clustering is a central problem in machine learning for whichgraph-based approaches have proven their efficiency. In this paper, westudy a relaxation of the modularity maximization problem, well-known inthe graph partitioning literature. A solution of this relaxation gives toeach element of the dataset a probability to belong to a given cluster,whereas a solution of the standard modularity problem is a simplepartition. We introduce an efficient optimization algorithm to solve thisrelaxation, that is both memory efficient and local, and show that ourmethod includes the Louvain algorithm, a state-of-the-art technique tosolve the traditional modularity problem. Experiments on both synthetic andreal-world data show that our approach provides meaningful information onvarious types of data.

The many facets of community detection
2018-05-14 11:30 - 12:00 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
In this talk, I will present a collection of results focusingon the presence of inhomogeneities in networks: from the detection of denseclusters (community detection) to their impact on
dynamical processes,the definition of disassortative communities and the design of localmetrics on networks.

Collective insurance fraud detection via network analysis
2018-05-14 11:00 - 11:30 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France

On the Performance of a Canonical Labeling for Matching CorrelatedErdos-Renyi Graphs
2018-05-14 10:00 - 10:30 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
Recent results have characterized the exactinformation-theoretic threshold for graph matching in correlatedErd?s-Rényi graphs. However, very little is known about the existence ofefficient algorithm to achieve graph matching without seeds. In this work,we identify a region in which a straightforward and efficient canonicallabeling algorithm, initially introduced in the context of graphisomorphism, succeeds in matching correlated Erd?s-Rényi graphs. Thealgorithm has two steps. In the first step, all vertices are labeled bytheir degrees and a trivial minimum distance matching (i.e., simplysorting vertices according to their degrees) matches the a fixed number ofhighest degree vertices in the two graphs. Having identified this subset ofvertices, the remaining vertices are matched using a noisy variant of abipartite matching algorithm.

Joint work with Osman Dai, Daniel Cullinaand Negar Kiyavash

Analysis of temporal interactions with link streams
2018-05-14 09:30 - 10:00 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France
Money or data transfers, contacts between individuals, orproduct sales, may all be modeled as temporal interactions. Studying thestructure and dynamics of interactions is therefore crucial for manyfundamental and applied questions (like event detection in traffic, fraudfighting, recommender systems, network optimisation, and the interplaybetween relations and interactions). Their structure is studied with graphsand networks (sets of nodes and links); their dynamics is studied withsignals and time series (variations of a property over time); to study thedynamics of their structure, one uses graph sequences. However, theseapproaches poorly capture the both structural and temporal nature ofinteractions, that calls for a dedicated formalism. I will present ageneralization of graphs, that we call link streams, and that makes itpossible to consistently handle both aspects. We thus obtain a language forthe study of interactions over time, similar to the one provided by graphsfor the study of relations.

Multimodal graph clustering for music recommendation
2018-05-14 09:00 - 09:30 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France

Workshop on Graph Learning
2018-05-14 | Paris-Rennes Room (EIT Digital), 23 avenue d'Italie, 75013Paris, France
This workshop will bring together researchers from bothindustry and academia for presenting and discussing learning techniquesfrom/with graphs, from both theoretical and practical perspectives.

The program is available here.

Thesis Defense : Innovative paradigms and architectures for futuredistribution electricity networks supporting the energy transition
2018-04-16 14:00 | LINCS / EIT Digital, 23 avenue d'Italie, 75013 Paris, France

Network fingerprinting: TTL-based router signatures
2018-04-12 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Fingerprinting networking equipment has many potentialapplications and benefits in network management and security. Moregenerally, it is useful for the understanding of network structures andtheir behaviors. In this paper, we describe a simple fingerprintingmechanism based on the initial TTL values used by routers to reply tovarious probing messages. We show that main classes obtained using thissimple mechanism are meaningful to distinguish routers platforms. Besides,it comes at a very low additional cost compared to standard active topologydiscovery measurements. As a proof of concept, we apply our method to gainmore insight on the behavior of MPLS routers and to, thus, moreaccurately quantify their visible/invisible deployment.

Open Web Proxies: analysis, threats and opportunities
2018-04-11 14:00 - 15:00 | Doctoral Training Center (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Open web proxies promise anonymity and censorship circumventionat no cost. Several websites publish lists of free proxies organized bycountry, anonymity level, and performance. These lists index hundreds ofthousand of hosts discovered via automated tools and crowd-sourcing. Acomplex free proxy ecosystem has been forming over the years, of whichvery little is known. In this talk we shed light on this ecosystem via adistributed measurement platform that leverages both active and passivemeasurements. Active measurements are carried out by an infrastructure wename ProxyTorrent that discover free proxies, assess their performance,and detect potential malicious activities. Passive measurements relate toproxy performance and usage in the wild are accomplished by means of aChrome plugin named Ciao. ProxyTorrent has been running since January2017, monitoring up to 200,000 free proxies. Ciao was launched in March2017 and has thus far served roughly 3,000 users and generated 3 TB oftraffic. Our analysis shows that less than 2% of the proxies announced onthe Web indeed proxy traffic on behalf of users; further, only half ofthese proxies have decent performance and can be used reliably. Around 10%of the working proxies exhibit malicious behaviors, e.g., ads injectionand TLS interception, and these proxies are also the ones providing thebest performance. Through the analysis of more than 3 TB of proxiedtraffic, we show that web browsing is the primary user activity.Geo-blocking avoidance is not a prominent use-case, with the exception ofproxies located in countries hosting popular geo-blocked content. Inaddition to those findings, Open Web proxies, and more generally openresources on the internet, provide several opportunities. We will discussfew use cases we are addressing and focus on one of them, i.e. FreeLab:A Free Experimentation Platform. The key idea of FreeLab is thatexperiments run directly at its user machines, while traffic is relayed byfree vantage points in the Internet (web and SOCKS proxies, and DNSresolvers).

The Cascade-Correlation Learning Architecture
2018-04-09 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
Marc-Olivier Buob will present a paper of Scott E. Fahlman andChristian Lebiere about

The Cascade-Correlation Learning Architecture,August 29, 1991 CMU-CS-90-100

Vehicular networks in hyperfractal setup
2018-04-04 14:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Confinement of human settlement in areas limited in size is thefoundation of the long-standing Central Place Theory which assumes theexistence of regular spatial patterns in regional human organization. Forexample, a department has rural areas, with low density of population,and urban areas, with high density of population, namely cities andtowns. Similarly, cities reflect a statistical self-similarity orhierarchy of clusters. Towns are split in neighborhoods; each neighborhoodis organized in quarters then blocks separated by streets. Blocks are madeof buildings that are themselves split in apartments and so on. Vehiclesand devices are deployed where human activities occur and therefore inheritthe self-similarity of the environment where they are deployed.
This talkwill present our macro level model for the topology of vehicularcommunication entities in cities by exploiting self-similarity. The modelis called hyperfractal and presents two variations: the hyperfractal modelfor density of vehicles and the hyperfractal model for road-side units(RSU). The model exploits the self-similarity of the density map of thevehicular communications entities and avoids the extremes of regularity andrandomness.
Furthermore, we introduce a method for computing thehyperfractal dimension on cities. Using this fitting procedure applied toopen data sets, we prove the validity of the model and show how it can beextended to cities that do not follow a regular hierarchicalpattern.
Next, we study the information propagation speed of a broadcastin an urban delay tolerant network which is disconnected at all time,i.e., where end-to-end multihop paths may not exist (requiring astore-carry-and-forward routing model). We prove bounds on the averagebroadcast time in a hyperfractal setup and show that the performance is duein part to an interesting self-similar phenomenon, that we denote asinformation teleportation, that arises as a consequence of the topologyand allows an acceleration of the broadcast time.

User-Centric Personal Data Analytics on the Edge
2018-03-28 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Abstract: In this talk, I present our ongoing work onutilising edge-computing to improve the scalability and privacy ofuser-centred analytics in the context of personal/IoT data. I present anarchitecture where devices and resources centred around the user,collectively referred to as the edge, can complement the cloud forproviding privacy-aware, yet accurate and efficient analytics. I thenpresent the evaluations of the proposed framework for applyingprivacy-preserving deep learning techniques on a number of exemplarapplications, and discuss the broader implications of such approaches forfuture systems such as the Databox platform.

Bio: Hamed is aSenior Lecturer (~Associate Professor) and the Deputy Director of Researchin the Dyson School of Design Engineering, and an Academic Fellow of theData Science Institute, at The Faculty of Engineering at Imperial CollegeLondon. He is interested in User-Centered Systems, IoT, Applied MachineLearning, and Data Security & Privacy. He enjoys designing andbuilding systems that enable better use of our digital footprint, whilerespecting users' privacy. He is also broadly interested in sensingapplications and Human-DataInteraction.

https://haddadi.github.io/

Ergodic control and polyhedral approaches to PageRank optimization
2018-03-26 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
In this session of the reading group, Anastasios Giovanidiswill present the paper

O. Fercoq, M. Akian, M. Bouhtou, S. Gaubert.“Ergodic control and polyhedral approaches to PageRank optimization”,
IEEE Trans. on Automatic Control, vol. 58, no. 1, Jan. 2013

Knowledge graph embeddings
2018-03-12 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
Nathan De Lara will introduce the knowledge graph embeddings,based on the following references:

Bordes, A., Usunier, N.,Garcia-Duran, A., Weston, J., and Yakhnenko, O. (2013). Translatingembeddings for modeling multi-relational data. In Advances in neuralinformation processing systems (pp. 2787-2795).
Wang, Z., Zhang, J.,Feng, J., and Chen, Z. (2014, July). Knowledge Graph Embedding byTranslating on Hyperplanes. In AAAI (Vol. 14, pp. 1112-1119).
Bordes,A., Weston, J., Collobert, R., and Bengio, Y. (2011, August).Learning Structured Embeddings of Knowledge Bases. In AAAI (Vol. 6, No.1, p. 6).
Wang, Q., Mao, Z., Wang, B., and Guo, L. (2017).Knowledge graph embedding: A survey of approaches and applications. IEEETransactions on Knowledge and Data Engineering, 29(12),2724-2743.

A Sliding-Resolution Algorithm for Hierarchical Graph Clustering
2018-03-07 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
We propose a novel algorithm for the hierarchical clustering ofgraphs. The algorithm is a simple but key modification of the Louvainalgorithm based on some sliding-resolution scheme. In particular, the mostrelevant clusterings, corresponding to different resolutions, areidentified. The algorithm is parameter-free, fast and memory efficient.Numerical experiments on both synthetic and real datasets show theperformance of the algorithm.

Joint work with Thomas Bonald (TelecomParisTech), Alexandre Hollocou (Inria), Alexis Galland (Inria)

Étude des sous-graphes typiques des graphes aléatoires par lacombinatoire analytique
2018-02-26 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
Orateur : Élie de Panafieu

La question qui guideral'exposé est l'étude de la loi limite du
nombre de triangles dans ungraphes aléatoire à n sommet et m = O(n)
sommets. C'est aussi unprétexte pour présenter quelques outils de
combinatoire analytique(manipulation de séries génératrices). Les
résultats présentés sontclassiques et ont été démontrés par Erdös et
Rényi en 1960 par destechniques probabilistes (méthodes du premier et
du second moment).L'intérêt de la preuve analytique est sa robustesse
: elle s'étendnaturellement à des familles de graphes plus complexes,
notamment auxgraphes dont la distribution des degrés suit une loi de
puissance("power-law" ou "scale-free networks" selon les auteurs), et
qui serencontrent dans de nombreuses applications -- mais nous
n'aurons sansdoute pas le temps d'aborder ces extensions...

Insensitivity of the Hydrodynamic Limit of PS under RandomizedSQ(d) Algorithms
2018-02-21 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
In many applications such as cloud computing, managing serverfarm resources etc. an incoming task or job has to be matched with anappropriate server in order to minimise the latency associated with theprocessing. Ideally the best choice would be to match a job to the fastestavailable server. However when there are thousands of servers requiring theinformation on all server tasks is an overkill.
Pioneered in the 1990’sthe idea of randomised sampling of a few servers was proposed by Vve-denskaya and Dobrushin in Russia and Mitzmenmacher in the US andpopularised as the “power of two” schemes which basically means thatsampling two servers randomly and sending the job to the “better”server (i.e. with the shortest queue, or most resources) provides most ofthe benefits of sampling all the servers.

In the talk I will discussmulti-server processor sharing models under power-of-d routing scheme whenservice time distributions are general with finite mean. Previous works onthese models as- sume that the service times are exponentially distributedand insensitivity was suggested through simulations. Showing insensitivityto service time distributions has remained an open problem. The difficultyis that for general service times the underlying Markovian model is morecomplex. Indeed it can be viewed as a Markov process on Z+ × R?+ . Using ameasure valued process approach we first derive the hydrodynamic limit ormean field equation (MFE) for the empirical measure. The MFE is nowcharacterized by a pde whose stationary point coincides with the fixedpoint in the case with exponential service times. This establishes theinsensitivity of the fixed point. The techniques developed in this paperare applicable to study mean field limits for Markov processes on generalstate spaces and insensitivity properties of other queueing models.

Thisis joint work with Thirupathiah Vasantam (UW) and Arpan Mukhopadhyay(EPFL).

Network Slicing Games: Enabling Statistical Multiplexing ofMulti-tenant Spatial Loads
2018-02-14 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Next generation wireless architectures are expected to enableslices of shared wireless infrastructure which are customized to specificmobile operators/services. Given infrastructure costs and the stochasticnature of mobile services' spatial loads, it is highly desirable toachieve efficient statistical multiplexing amongst network slices. Thistalk will introduce a simple dynamic resource sharing policy whichallocates a `share' of a pool of (distributed) resources to each slice--Share Constrained Proportionally Fair (SCPF). We give a characterization ofthe achievable performance gains over static slicing, showing higher gainswhen a slice's spatial load is more 'imbalanced' than, and/or 'orthogonal'to, the aggregate network load. Under SCPF, traditional networkdimensioning translates to a coupled share dimensioning problem,addressing the existence of a feasible share allocation given slices'expected loads and performance requirements. We provide a solution torobust share dimensioning for SCPF-based network slicing. Slices may wishto unilaterally manage their users' performance via admission control whichmaximizes their carried loads subject to performance requirements. We showthis can be modeled as a ``traffic shaping" game with an achievable Nashequilibrium. Under high loads the equilibrium is explicitly characterized,as are the gains in the carried load under SCPF vs. static slicing.Detailed simulations of a wireless infrastructure supporting multipleslices with heterogeneous mobile loads show the fidelity of our models andrange of validity of our high load equilibrium analysis.

Joint work withPablo Caballero, Jiaxiao Zheng, Albert Banchs, Xavier Costa, Seung JunBaek

Sequence to sequence learning
2018-02-12 14:00 - 15:30 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
For the next reading group, Édouard Pineau will talk aboutsequence-to sequence learning, based on the two followingreferences:

Sutskever Ilya, Oriol Vinyals, and Quoc V. Le."Sequence to sequence learning with
neural networks." Advances in neuralinformation processing systems. (2014)
Bahdanau Dzmitry, KyunghyunCho, and Yoshua Bengio. "Neural machine translation by
jointly learningto align and translate." arXiv preprint arXiv:1409.0473(2014).

Apple vs. Samsung: a Mathematical Battle
2018-02-02 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Abstract:
Apple and Samsung have been fighting patentbattles around the world. Come learn about the mathematics at the heart ofone of these battles, the error correcting codes used in 3G communication.We will give a gentle introduction to coding theory, explain why thiscaused a legal battle, and we will conclude by describing why PresidentObama ultimately vetoed the ruling by the court (the first time a presidenthad used that veto power in nearly 30 years!).

Biography:
Jim Davis,Professor of Mathematics at the University of Richmond since 1988, doesresearch in combinatorics and error correcting codes. He spent two yearsworking for Hewlett-Packard and he has 15 patents stemming from that work.He has published more than 50 papers, including several withundergraduates as coauthors (one of those also has Sihem Mesnager ascoauthor). Outside of mathematics, he is an avid squash and bridgeplayer.

An Efficient Data Protection Architecture Based on Fragmentationand Encryption
2018-01-31 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
In this presentation, a completely revisited secure datastorage and transmission scheme ispresented. This new scheme is based on anagnostic selective encryption methods combinedwith fragmentation anddispersion. Discrete Wavelet Transform (DWT) is used as thepreprocessingmethod to determine the selection process before encryption and toguaranteethe agnostic property of the protection. Also, General Purpose GraphicProcessingUnit (GPGPU) is deployed to allow performance to be veryefficient compared with fullencryption algorithms. During the protectionprocess, the data is fragmented to be privatefragments with small storagespace and public fragments with large storage space. Then thedispersionstep will distribute the fragments to different storage environments aimingatutilizing the convenient and inexpensive cloud storage space whileprovide security for thedata. This design, with practical experimentationson different hardware configurations,provides strong level of protectionand good performance at the same time plus flexiblestorage dispersionschemes.

Queuing or not Queuing? (in large systems)
2018-01-29 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
Fabien Mathieu will talk about
Queuing or not Queuing? (inlarge systems), and will mainly use the following reference :

Loadbalancing in large-scale systems with multiple dispatchers (Mark van derBoor, Sem Borst, Johan van Leeuwaarden, 2017)

Performance of Balanced Fairness in Resource Pools: A RecursiveApproach
2018-01-24 14:00 - 16:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Understanding the performance of a pool of servers is crucialfor proper dimensioning. One of the main challenges is to take into accountthe complex interactions between servers that are pooled to process jobs.In particular, a job can generally not be processed by any server of thecluster due to various constraints like data locality. In this paper, werepresent these constraints by some assignment graph between jobs andservers. We present a recursive approach to computing performance metricslike mean response times when the server capacities are shared according tobalanced fairness. While the computational cost of these formulas can beexponential in the number of servers in the worst case, we illustratetheir practical interest by introducing broad classes of pool structuresthat can be exactly analyzed in polynomial time. This extends considerablythe class of models for which explicit performance metrics areaccessible.This is a joint work with Thomas Bonald and Fabien Mathieu.

Empirical Evaluation of Gated Recurrent Neural Networks on SequenceModeling
2018-01-15 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
Achille SalaÃ¼n will talk about Recurrent Neural Networks andpresent the paper

Empirical Evaluation of Gated Recurrent NeuralNetworks on Sequence Modeling by Chung, Gulcehre, Cho, and Bengio (NIPS2014).

Reinforcement Learning for Efficient Access Control with M2M/H2Htraffic in LTE-A networks
2018-01-03 14:00 - 16:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Although many advantages are expected from the provision ofservices for M2M communications in cellular networks such as extendedcoverage, security, robust management and lower deployment costs,coexistence with a large number of M2M devices is still an importantchallenge, in part due to the difficulty in allowing simultaneous access.Although the random access procedure in LTE-A is adequate for H2Hcommunications, it is necessary to optimize this mechanism when M2Mcommunications are considered. One of the proposed methods in 3GPP isAccess Class Barring (ACB), which is able to reduce the number ofsimultaneous users contending for access. However, it is still not clearhow to adapt its parameters in dynamic or bursty scenarios, such as thosethat appear when M2M communications are introduced.We propose a dynamicmechanism for ACB based on reinforcement learning, which aims to reducethe impact that M2M communications have over H2H communications, while atthe same time ensuring that the KPIs for all users are in acceptablelevels.

Analyzing the M/G/1 queue with a branching process
2017-12-18 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
For the next session of the reading group,

CÃ©line Comtewill talk about
Analyzing the M/G/1 queue with a branching process, andwill mainly use the following references:

- Some Problems in the Theoryof Queues, D.G. Kendall, 1951.
- Stochastic processes occurring in thetheory of queues and their analysis by the method of the imbedded Markovchain, D.G. Kendall, 1953.

Slides of the presentation

Random Fixed Points, Limits and Systemic risk
2017-12-13 14:00 - 15:00 | Doctoral Training Center (EIT Digital), 23, avenue d'Italie,Paris, 75013, France
Abstract: We consider vector fixed point (FP) equations inlarge
dimensional spaces involving random variables, and studytheir
realization-wise solutions. We have an underlying directedrandom
graph, that defines the connections between various components ofthe
FP equations. Existence of an edge between nodes i,j implies thei-th
FP equation depends on the j-th component. We consider a specialcase
where any component of the FP equation depends upon anappropriate
aggregate of that of the random ``neighbor'' components. Weobtain
finite dimensional limit FP equations (in a much smallerdimensional
space), whose solutions approximate the solution of therandom FP
equations for almost all realizations, in the asymptotic limit(number
of components increase). Our techniques are different fromthe
traditional mean-field methods, which deal with stochastic FPequations
in the space of distributions to describe the stationarydistributions
of the systems. In contrast our focus is on realization-wiseFP
solutions. We apply the results to study systemic risk in alarge
financial heterogeneous network with many small institutions andone
big institution, and demonstrate some interestingphenomenon.
Biography: Kavitha Veeraruna completed my PhD with IndianInstitute of
Science in 2007. I have done two postdocs, one at TIFRBangalore and
then with Prof. Eitan Altman at INRIA. Currently I amworking as an
Assistant Professor at IIT Bombay Mumbai.

The real fuss with quantum mechanics
2017-12-06 14:00 - 16:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Many foundational issues in quantum mechanics frustrate theexperts and keep them up at night. Unfortunately, when these conceptsreach the greater public, they are often misrepresented andoversimplified. I want to share with you some bewildering tales of quantummechanics, unabridged, straight from the source. In this talk: Themeasurement problem, delayed-choice erasure, interaction-freemeasurements, non-locality, non-contextuality. This is not the usualcat-in-the-box talk. Get ready for the real s**t!

Predicting user QoE from QoS metrics for internet applications
2017-11-29 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Predicting the user Quality-of-Experience (QoE) for an internetapplication is a highly desirable feature in a number of situations.However, directly measuring user QoE is extremely challenging, due to itssubjective nature. One common approach is to measure Quality-of-Service(QoS) metrics and use it to predict user QoE. In this presentation, weshow our efforts into understanding and predicting user QoE. First, wewill discuss state-of-the-art quality assessment methodologies. Then, wewill present several approaches to model user QoE from QoS metrics.Finally, we show a few examples where we model user QoE from QoS metrics.

Optimal flow segmentation in SDN with memory constraints: areinforcement learning approach
2017-11-22 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Datacenter flow routing relies on packet-in messages generatedby switches and directed to the controller upon new flows arrivals. The SDNcontroller reacts to packet-in events by installing forwarding rules in thememory of all switches along an optimized path. Since flow arrival ratescan peak to millions per second, a relevant constraint is represented bythe scarce amount of TCAM memory on switches. We assume that if a routingtable is full, a flow will be routed on a default, sub-optimal path. Aviable solution is to restrict the optimized traffic to critical flows:this corresponds to performing traffic segmentation, prioritizing largerflows over smaller flows. However, choosing the optimal threshold todiscriminate optimized flows from non-optimized flows is not a trivialtask. This work focuses on learning the optimal flow segmentation policyunder memory constraints. We formulate this task as a Markov decisionproblem. Based on the structure of the optimal stationary policy, wepropose a reinforcement learning algorithm tailored to the problem at hand.We prove it is adaptive, correct and has a polynomial time complexity.Finally, numerical experiments characterize the performance of thealgorithm.Joint work with Francesco de Pellegrini (Fondazione BrunoKessler), Lorenzo Maggi (Huawei Algorithmic and Mathematical SciencesLab, Paris)

Non-negative matrix factorization
2017-11-20 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
Thomas Bonald will talk about non-negative matrixfactorization.

Optimal Joint Subcarrier and Power Allocation in Power-Domain NOMAis Strongly NP-Hard: Complexity Analysis
2017-11-15 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Non-orthogonal multiple access (NOMA) is a promising radioaccess technology for 5G. It allows several users to transmit on the samefrequency and time resource by performing power-domain multiplexing. At thereceiver side, successive interference cancellation (SIC) is applied tomitigate interference among the multiplexed signals. In this way, NOMA canoutperform orthogonal multiple access schemes used in conventional cellularnetworks in terms of spectral efficiency and allows more simultaneoususers. We investigate the computational complexity of joint subcarrier andpower allocation problems in multi-carrier NOMA systems. In this talk, wewill show that these problems are strongly NP-hard for a large class ofobjective functions, namely the weighted generalized means of theindividual data rates. This class covers the popular weighted sum-rate,proportional fairness, harmonic mean and max-min fairness utilities. Thisresult implies that the optimal power and subcarrier allocation cannot becomputed in polynomial time in the general case, unless P = NP.Nevertheless, we present some heuristics and show their performancethrough numerical results.

One-dimensional non-deterministic random walks
2017-11-06 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
Ã‰lie de Panafieu will present some current work aboutone-dimensional, non-deterministic, random walks.

Will productivity growth return in the new digital era?
2017-10-25 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
It is increasingly acknowledged that we are on the verge of thenext technological and industrial revolution, driven by the digitizationand interconnection of physical elements and infrastructure under thecontrol of advanced intelligent systems. Therefore, there will be a newera of automation that should result in enhanced productivity. However,such productivity enhancements have been anticipated before, e.g, therevolution commonly known as the â€˜information ageâ€™, and havefailed to materialize. Were the productivity increases observed followingthe earlier industrial revolutions a one-time aberration that will not berepeated in the new digital age? In this paper, we attempt to address thisquestion by a quantitative analysis of the prior productivity jumps andtheir physical technological origins, and extend this analysis to thelatent set of analogous digital technologies. This approach leverages acorrelation we observe between the diffusion of key infrastructuretechnologies and productivity jumps. We use data from 1875 to 1985 fromthe US and data from 1950 to 2015 in China and India to demonstrate thisnon-linear correlation. Amongst the predictions of the model, we see apossible productivity jump in the United States in the 2030s timeframe whenthe aggregate of the constituent digital technologies passes the tippingpoint of 50-60 percent penetration.
Joint work with Marcus Weldon, SanjayKamat, Subra Prakash

Poisson games
2017-10-23 10:30 - 12:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
FranÃ§ois Durand will present an introduction to Poissongames based on the two following articles:

R. Myerson. Large PoissonGames. Journal of Economic Theory, 94:7â€“45, 2000.M
R. Myersonand R.J. Weber. A Theory of Voting Equilibria. American Political ScienceReview, 87:102â€“114, 1993.

Slides of the presentation

Multi-Area Interchange Scheduling under Uncertainty
2017-10-11 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Large interconnected power systems are often operatedby
independent system operators, each having its own operatingregion
within which internal resources are used economically. Theoperating
regions are connected physically by tie lines that allow oneoperator
to import from or export to its neighbors for better utilizationof
overall system resources.In this talk, we present some recentresults
on the optimal scheduling of interchange among independentlyoperated
power systems in the presence of uncertainty. Based on the ideaof
classic coordinate descent method, we propose aninterface-by-interface
scheduling algorithm which is compatible to thecurrent industrial
practice in the electric grid of U.S. and applied tosynchronous and
asynchronous scheduling schemes

Adaptive Video Streaming: Towards a systematic comparison of ICNand TCP/IP
2017-10-04 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Streaming of video contents over the Internet isexperiencing anunprecedented growth. While video permeatesevery application, it also putstremendous pressure in the network --to support users having heterogeneousaccesses and expectinghigh quality of experience, in a furthermorecost-effectivemanner. In this context, Future Internet (FI) paradigms,suchas Information Centric Networking (ICN), are particularly wellsuitedto not only enhance video delivery at the client (as in theDASH approach),but to also naturally and seamlessly extendvideo support deeper in thenetwork functions.In this talk, we contrast ICN and TCP/IP with anexperimentalapproach, where we employ several state-of-the-artDASHcontrollers (PANDA, AdapTech, and BOLA) on an ICN vsTCP/IP network stack.Our campaign, based on tools which wedeveloped and made available asopen-source software, includesmultiple clients (homogeneous vsheterogeneous mixture, synchronousvs asynchronous arrivals), videos (upto 4K resolution),channels (e.g., DASH profiles, emulated WiFi and LTE,real3G/4G traces), and levels of integration with an ICN network(i.e.,vanilla NDN, wireless loss detection and recovery at theaccess point,load balancing). Our results clearly illustrate, aswell as quantitativelyassess, benefits of ICN-based streaming,warning about potential pitfallsthat are however easy to avoid. Overall, our work constitutes a firstmilestonetowards a fair and complete assessment of fully fledged NDNvideodistribution systems, and their comparison with state ofthe art CDNtechnologies implemented over a classic TCP/IPstack, which is part of ourongoing work and that we briefly discuss. Part of this work will appear inIEEE Transactions on Multimedia, October 2017 issue.

Active Hypothesis Testing: Learning to Match in Expert Systems
2017-09-27 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
We study adaptive matching in expert systems, as an instanceof adaptive sequential hypothesis testing. Examples of such systems includeQ&A platforms, crowdsourcing, image classification. Consider asystem that receives tasks or jobs to be classified into one of a set ofgiven types. The system has access to a set of workers, or experts, andthe expertise of a worker is defined by the jobs he is able to classify andthe error in his response. This active sequential hypothesis testingproblem was first addressed by Chernoff in 1959, whereby experts to bequeried are selected according to how much information they provide. Inthis talk we will begin with an overview of past work on this topic, thenconsider our model where we assume access to less fine-grained informationabout the expertise of workers. We propose a gradient-based algorithm,show its optimality and through numerical results show that it outperformsthe Chernoff-like algorithms.

Why deep neural networks ?
2017-09-21 16:00 - 17:30 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
Anne Bouillard will present the paper Why deep neural networks?, by Shiyu Liang and R. Srikant, 2016.

QoE-Aware Service and Network Management for Video Streaming
2017-09-20 14:00 - 15:15 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Today's consumer Internet traffic is transmitted on a besteffort basis without taking into account any quality requirements. Thebackbone and the wireless access networks lack service guarantees for thepredominant consumer Internet traffic, with video streaming beingresponsible for 60% of the traffic share. As services rely oninterconnected networks, service performance and thus user satisfactiondepend on network performance. Consequently, it is of utmost importance tounderstand the relationships between user-perceived Quality of Experience(QoE), and network performance as described by Quality of Service (QoS)parameters.However, in general the network does neither know whichInternet applications it is carrying nor which quality requirements have tobe met. To be able to meet the demands of applications and users in thenetwork, QoE-aware service and network management is proposed whichrequires an information exchange between applications and network. From aconceptual perspective, this requires three basic research steps:modeling, monitoring, and optimization of QoE. The first part of thistalk covers QoE management and monitoring approaches, while the secondpart highlights concrete examples in order to demonstrate how QoE-awarenetwork and service management may improve the user-perceived quality ofvideo streaming.

Learning the Network of a Linear Dynamical System from AmbientFluctuations
2017-09-06 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Linear Dynamical Systems are used to model several evolvingnetwork processes in biology, physical systems as well as financialnetworks. Estimation of the topology of a linear dynamical system is thusof interest for learning and control in diverse domains. This talk presentsa useful framework for topology estimation for general linear dynamicalnetworks (loopy or radial) using time-series measurements of nodal states.The learning framework utilizes multivariate Wiener filtering to unravelthe interaction between fluctuations in states at different nodes andidentifies operational edges by considering the phase response of theelements of the multivariate Wiener filter. The benefit derived byconsidering samples from ambient dynamics v/s steady state measurementswill be described along with extensions, discussion of sample andcomputational complexity and open questions. In particular, we discuss oneapplication related to topology estimation in power grids using samples ofnodal voltage phase angles collected from the swing equations.

Economic models for wireless sensor network-based services
2017-07-12 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
The Internet of Things is one of the hottest topics beingdebated today across industries worldwide. Successful IoT deployment needssustainable business models that are well understood. This seminar willpresent such business models, its rationale and the analytical models usedfor their discussion. The proposals are drawn from the research conductedrecently by the speaker.The business models are based on service providersthat intermediate between wireless sensor networks that sense data andusers that benefit from enhanced service build around the sensed data.Scenarios where the service provider operates without and with competitionare modelled, analyzed and discussed. The modelling and analysis tools areborrowed from microeconomics, optimization and game theory.The seminarwill present some scenarios and the models employed for the analysis ofeach one. Then it will proceed to present the analysis performed and,finally, it will discuss the results of the analysis.

Incentive Mechanism Design for Public Cryptocurrencies
2017-07-10 14:30 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Presentation for the Working Group on BitCoin.

Fairness in block-chain systems
2017-07-10 14:00 - 14:30 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Abstract: Formal security analyses for block-chains derived thefamous
"honest majority" assumption: the system well-behaves only ifthe
majority of the hashing power is in the hands of honest miners.This
result has been proven without taking into considerationeconomic
aspects related to miner's incentives and their rationalbehavior.
Other works analyzed selfish mining with respect to incentivesand
concluded that the majority assumption is not enough undercertain
conditions. All these studies make the implicit assumption thatthe
health of the system is only in the hands of miners, but what aboutif
all the users leave the system. Since the system is composed ofminers
and users and since these two sets are disjoint in practice,block
chain's health strictly relates to the capacity of promotinghonest
participation both for miners and users. In this talk we explorethe
relationship between participation and the notion of fairness.In
general terms, fairness can be defined as the overall satisfactionof
justified expectations of the participants. If a block-chain systemis
fair, then its participants will tend to stay in the system,otherwise
they may leave. We analyze user and miner strategies that arecurrently
possible in BitCoin-like implementations, and we show thatexisting
block-chain systems are not fair for their users. We finallydiscuss
new ways for improvement arguing that novel redistributionmechanisms
are needed to promote participation of all nodes.

Global Measurements of Internet Censorship
2017-07-05 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Abstract:
Internet users in many countries around theworld are subject to various forms of censorship and information control.Despite its widespread nature, however, measuring Internet censorship ona global scale has remained an elusive goal. Internet censorship is knownto vary across time and within regions (and Internet Service Providers)within a country. To capture these complex dynamics, Internet censorshipmeasurement must be both continuous and distributed across a large numberof vantage points. To date, gathering such information has requiredrecruiting volunteers to perform measurements from within countries ofinterest; this approach does not permit collection of continuousmeasurements, and it also does not permit collection from a large numberof measurement locations; it may also put the people performing themeasurements at risk. Over the past four years, we have developed acollection of measurement techniques to surmount the limitations of theseconventional approaches. In this talk, I will describe three suchtechniques: (1) Encore, a tool that performs cross-origin requests tomeasure Web filtering; (2) Augur, a tool that exploits side-channelinformation in the Internet Protocol (IP) to measure filtering usingnetwork-level access control lists; and (3) a tool to measure DNSfiltering using queries through open DNS resolvers. These three tools allowusÃ¢â‚¬â€for the first time everÃ¢â‚¬â€tocharacterize Internet censorship continuously, from hundreds of countriesaround the world, at different layers of the network protocol stack. eachof these techniques involves both technical and ethical challenges. I willdescribe some of the challenges that we faced in designing and implementingthese tools, how we tackled these challenges, our experiences withmeasurements to date, and our plans for the future. Long term, our goalis to collaborate with social scientists to bring data to bear on a widevariety of questions concerning Internet censorship and informationcontrol; I will conclude with an appeal to cross-disciplinary work in thisarea and some ideas for how computer scientists and social scientists mightwork together on some of these pressing questions going forward.Thisresearch is in collaboration with Sam Burnett, Roya Ensafi, Paul Pearce,Ben Jones, Frank Li, and Vern Paxson.

Biography:
Nick Feamster is aprofessor in the Computer Science Department at Princeton University andthe Deputy Director of the Princeton University Center for InformationTechnology Policy (CITP). Before joining the faculty at Princeton, he wasa professor in the School of Computer Science at Georgia Tech. He receivedhis Ph.D. in Computer science from MIT in 2005, and his S.B. and M.Eng.degrees in Electrical Engineering and Computer Science from MIT in 2000 and2001, respectively. NickÃ¢â‚¬â„¢s research focuses on improvingthe security and performance of communications networks with systems thatdraw on advanced Internet measurement, data analytics, and machinelearning. Nick is an ACM Fellow. Among other awards, he received thePresidential Early Career Award for Scientists and Engineers (PECASE) forhis contributions to cybersecurity, the Technology Review 35 "Top YoungInnovators Under 35" award, and the ACM SIGCOMM Rising Star Award.

Competitive Caching of Contents in 5G Edge Cloud Networks
2017-06-28 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
The surge of mobile data traffic forces network operators tocope with capacity shortage. The deployment of small cells in 5G networksis meant to increase radio access capacity. Mobile edge computingtechnologies, in turn, can be used in order to manage dedicated cachespace memory inside the radio access network, thus reducing latency andbackhaul traffic. Mobile network operators will be able to provisioncontent providers with new caching services to enhance the quality ofexperience of their customers on the move. Cache memory in the mobile edgenetwork will become a shared resource.We study a competitive caching schemewhere contents are stored at given price set by the mobile networkoperator. We first formulate a resource allocation problem for a taggedcontent provider seeking to minimize the expected missed cache rate. Theoptimal caching policy is derived accounting for popularity andavailability of contents, the spatial distribution of small cells, andthe caching strategies of competing content providers. It is showed toinduce a specific order on contents to be cached based on their popularityand availability.Next, we study a game among content providers in the formof a generalized Kelly mechanism with bounded strategy sets andheterogeneous players. Existence and uniqueness of the Nash equilibrium areproved. Numerical results validate and characterize the performance of thesystem and the convergence to the Nash equilibrium.

Kleinberg's Grid Unchained
2017-06-23 14:15 - 14:45 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Talk from the LINCS Workshop.

Toward automated recommendation of IoT services
2017-06-23 11:00 - 11:15 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France

Massively-Parallel Feature Selection for Big Dimensionality Data
2017-06-23 10:45 - 11:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Talk from the LINCS Workshop

Studying large networks and graphical data via local weak limittheory
2017-06-23 09:30 - 10:15 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France

Future Directions in Wireless Networking
2017-06-22 17:30 - 18:15 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France

Stream processing for monitoring of real-time network services
2017-06-22 17:15 - 17:30 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France

Blockchains and incentives
2017-06-22 17:00 - 17:15 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France

Understanding Performance of Large Cellular Networks â€” Dataand Models
2017-06-22 16:30 - 17:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France

PhDs and PostDocs' Presentations
2017-06-22 14:30 - 16:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
LINCS younglings present their work in a few minutes for theLINCS workshop

Adaptive Matching in Expert Systems
2017-06-22 12:15 - 12:30 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France

WeBrowse: a passive crowdsourced content discovery platform forcommunities of a place
2017-06-22 10:15 - 10:45 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France

Traveling Salesman in Reverse: Conditional Markov Entropy forMobility Trajectory Segmentation
2017-06-22 09:30 - 10:15 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France

Perennial and Personalized Sensing through Wireless Energy
2017-06-21 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
In a future where implanted and wearable sensors continuouslyreport physiological data, how to power such sensors without batteryreplacement and developing new communication methods that are safe forhuman tissues remain as unexplored frontier. This talk describes recentadvances in designing systems and protocols for contactless wirelesscharging using using RF waves and the use of weak electrical currents fordata transfer among body implants. It explores the fundamental tradeoffsthat exist between achieving high data and recharging rates, constructivemixing of radiated signals through beamforming, MAC protocols that allowdifferential data/energy access, and the promise of simultaneous transferof data over energy. The talk shall also cover some latest results incharging sensors purely from ambient cellular signals in Boston city. Onthe implant side, advances in channel modeling and topology placementstrategies are discussed with experimental results on low-overhead datatransfers from an embedded implant to an on-skin relay node.

Mechanism Design
2017-06-13 16:00 - 17:30 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France
Continuation of last week's presentation

Distributed coordination of air-conditioning loads to providedemand-side flexibility to the power grid
2017-06-07 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
As we move away from fossil fuels toward renewableenergy
sources such as solar and wind, inexpensive energy storagetechnologies
are required. This is so since renewable energy sources,such as solar
and wind, are intermittent. An alternative to batteries--which are
quite expensive-- is "smart loads". With appropriateintelligence, the
power consumption of air conditioning --and many otherloads-- can be
varied around a baseline. This variation is analogous tothe charging
and discharging of a battery. Loads equipped with suchintelligence
have the potential to provide a vast and inexpensive sourceof energy
storage. Two principal challenges in creating a reliablevirtual
battery from millions of consumer loads include (1)maintaining
consumers' Quality of Service (QoS) within strict bounds, and(2)
coordinating the actions of loads with minimal communication toensure
accurate reference tracking by the aggregate. This talk summarizesour
work in addressing these two challenges. In particular, I willpresent
in some detail a method for ensuring reliable coordination inthe
presence of uncertainty without inter-load communication, which isa
frequently used method for coordination. In contrast, ourapproach
achieves reliable coordination by using a combination ofone-way
broadcast from the grid operator, and locally obtainedfrequency
measurements at the loads that provide valuable globalinformation.
Web

Introduction to mechanism design
2017-06-06 16:00 - 17:30 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France

Hybrid Energy Harvesting Wireless Systems: Performance Evaluationand Insights
2017-05-29 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Abstract:
Energy harvesting (EH) is an attractive andgreen solution to the problem of limited lifetime of wireless sensornetworks. Unlike a conventional node that dies once it runs out of energy,an EH node harvests energy from the environment and replenishes itsrechargeable battery. We investigate a new class of hybrid networks thatcomprise both EH and conventional nodes and differ from conventional andall-EH wireless sensor networks. We argue that the performance criteriathat are used to evaluate conventional and all-EH networks are no longersuitable to evaluate this new class of networks. We propose two new andinsightful performance criteria called k-outage duration and n-transmissionduration to evaluate these networks. They overcome the pitfalls associatedwith defining lifetime, which arise because the EH nodes never die but canoccasionally run out of energy, and capture the dynamic time evolution,which occurs because the conventional nodes irreversibly drain theirbatteries. They also account for the inability of the nodes to transmitdata due to insufficient battery energy and channel fading. We presentcomputationally efficient novel bounds for evaluating these criteria andgain several insights about the behavior of thesenetworks.

Biography:
Neelesh B. Mehta received his B. Tech degree inElectronics and Communications Engineering from the Indian Institute ofTechnology (IIT) Madras, in 1996, and M.S. and Ph.D. degrees inElectrical Engineering from the California Institute of Technology,Pasadena, USA, in 1997 and 2001, respectively. He is a Professor in theDepartment of Electrical Communication Engineering at the Indian Instituteof Science (IISc), Bangalore. Prior to joining IISc in 2009, he served asa research scientist in USA from 2001 to 2007 in companies such as AT&TResearch Labs, Broadcom Corporation, and Mitsubishi Electric ResearchLabs (MERL).
His research focuses on wireless communications. He hasworked on topics related to 3G, 4G, and 5G cellular communicationstandards, energy harvesting and green wireless sensor networks,cognitive radio, cooperative communications, multi-antenna technologies,and multiple access protocols. He has published 60+ papers in IEEEjournals, 3 book chapters, and 70+ conference papers. He is a co-inventorof 30+ issued US patents on these topics.
He served on the Board ofGovernors of the IEEE Communications Society from 2012-15. He is a Fellowof the Indian National Academy of Engineering (INAE) and the NationalAcademy of Sciences India (NASI). He is a recipient of the SwarnajayantiFellowship, NASI-Scopus Young Scientist award, Hari Om Ashram PreritVikram Sarabhai Research Award, and the INAE Young Engineer award. Heserves as an editor of the IEEE Transactions on Communications and as anExecutive Editor of the IEEE Transactions on Wireless Communications.

What Can be Achieved in Energy Efficiency for Cellular WirelessCommunications
2017-05-24 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Abstract:
Conventional cellular wireless networks weredesigned with the purpose of providing high throughput for the user andhigh capacity for the service provider, without any provisions of energyefficiency. As a result, these networks have an enormous Carbon footprint.For example, only in the United States, the Carbon footprint of thecellular wireless industry is equal to that of about 3/4 million cars. Inaddition, the cellular network is highly inefficient and therefore a largepart of the energy dissipated is wasted.In this presentation, we firstanalyze the energy dissipation in cellular wireless networks and point tosources of major inefficiency. We also discuss how much more mobile trafficis expected to increase so that this Carbon footprint will increasetremendously more. We then discuss potential sources of improvement at thephysical layer as well as at higher layers of the communication protocolhierarchy. For the physical layer, we discuss new modulation formats andnew device technologies and what they may bring in terms of energyefficiency gain. At higher layers, considering that most of the energyinefficiency in cellular wireless networks is at the base stations, wediscuss multi-tier networks and point to the potential of exploitingmobility patterns in order to use base station energy judiciously. Wediscuss link adaptation and point to why energy efficiency, and not powerefficiency should be pursued and what it means for the choice of linkrates. We show how much gain is possible by energy-efficient link rateadaptation. We describe the gains due to the exploitation of nonuniformtraffic in space, relays and cooperation, device-to-devicecommunications, multiple antenna technques, and in particular coordinatedmultipoint and massive MIMO, sleeping modes for the base stations, thetechniques of cell breathing and cell zooming, the energy trap problem forthe mobile terminals, and the potential approaches for video that provideenergy efficiency. We also review several survey papers and books publishedon this topic. By a consideration of the combination of all potentialgains, we conclude that an improvement in energy consumption in cellularwireless networks by orders of magnitude is possible. The lecture willpresent in detail where to concentrate research to achieve the largestgains.

Biography:
Ender Ayanoglu received the M.S. and Ph.D. degreesfrom Stanford University, Stanford, CA in 1982 and 1986, respectively,in electrical engineering. He was with the Communications Systems ResearchLaboratory, part of AT&T Bell Laboratories, Holmdel, NJ until1996, and Bell Labs, Lucent Technologies until 1999. From 1999 until2002, he was a Systems Architect at Cisco Systems, Inc., San Jose, CA.Since 2002, he has been a Professor in the Department of ElectricalEngineering and Computer Science, University of California, Irvine,Irvine, CA, where he served as the Director of the Center for PervasiveCommunications and Computing and held the Conexant-Broadcom Endowed Chairduring 2002-2010. His past accomplishments include invention of the 56Kmodems, characterization of wavelength conversion gain in WavelengthDivision Multiplexed (WDM) systems, and diversity coding, a technique forlink failure recovery in communication networks employing erasure coding in1990, prior to the publication of the first papers on network coding.During 2000-2001, he served as the founding chair of the IEEE-ISTOBroadband Wireless Internet Forum (BWIF), an industry standardsorganization which developed and built a broadband wireless systememploying Orthogonal Frequency Division Multiplexing (OFDM) and a MediumAccess Control (MAC) algorithm that providesQuality-of-Service (QoS)guarantees. This system is the precursor of todayÃ¢â‚¬â„¢s FourthGeneration (4G) cellular wireless systems such as WiMAX, LTE, andLTEAdvanced. From 1993 until 2014 Dr. Ayanoglu was an Editor, and sinceJanuary 2014 is a Senior Editor of the IEEE Transactions on Communications.He served as the Editor-in-Chief of the IEEE Transactions onCommunicationsfrom 2004 to 2008. From 1990 to 2002, he served on the Executive Committeeof the IEEE Communications Society Communication Theory Committee, andfrom 1999 to 2001, was its Chair. Currently, he is serving as thefounding Editor-in-Chief of the IEEE Transactions on Green Communicationsand Networking. Dr. Ayanoglu is the recipient of the IEEE CommunicationsSociety Stephen O. Rice Prize Paper Award in 1995 and the IEEECommunications Society Best Tutorial Paper Award in 1997. He has been anIEEE Fellow since 1998.

Ukkonen algorithm and Co
2017-05-23 16:00 - 17:00 | Telecom Paristech, I304 (3rd floor), 23, avenue d'Italie,Paris, 75013, France

High capacity wireless networks architectures through collaborationand intelligent information storage
2017-05-17 15:00 - 16:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Abstract:
A significant portion of today's networktraffic is due to recurring downloads of popular content (e.g., movies,video clips and daily news). It has been observed that replicating thelatter in caches installed at the network edge -close to the users- candrastically reduces network bandwidth usage and improve content accessdelay. The key technical issues in emergent caching architectures relate tothe following questions: where to install caches, what content and for howlong to cache, and how to manage the routing of content within thenetwork. In this talk, an overview of caching is provided, starting withgeneric architectures that can be applied to different networkingenvironments, and moving to emerging architectures that enable caching inwireless networks (e.g., at cellular base stations and WiFi accesspoints). Novel challenges arise in the latter due to the inadequacy ofwireless resources and their broadcast nature, the frequent hand-offsbetween different cells for mobile users, as well as the specificrequirements of different types of user applications, such as videostreaming. We will present our recent results on innovative cachingapproaches that (i) harvest idle user-owned cache space and bandwidth,(ii) leverage the broadcast nature of the wireless medium to serveconcurrent requests for content (iii) exploit the regularity of usermobility patterns, and (iv) apply advanced video encoding techniques tosupport multiple video qualities (e.g., screen sizes, frame rates, orsignal-to-noise ratio (SNR) qualities). These are cutting-edge approachesthat can achieve significant performance and cost-reduction benefits overthe state-of-the-art methods.

Biography:
Leandros Tassiulas is theJohn C. Malone Professor of Electrical Engineering at Yale University. Hisresearch interests are in the field of computer and communication networkswith emphasis on fundamental mathematical models and algorithms of complexnetworks, architectures and protocols of wireless systems, sensornetworks, novel internet architectures and experimental platforms fornetwork research. His most notable contributions include the max-weightscheduling algorithm and the back-pressure network control policy,opportunistic scheduling in wireless, the maximum lifetime approach forwireless network energy management, and the consideration of joint accesscontrol and antenna transmission management in multiple antenna wirelesssystems. Dr. Tassiulas is a Fellow of IEEE (2007). His research has beenrecognized by several awards including the IEEE Koji Kobayashi computer andcommunications award 2016, the inaugural INFOCOM 2007 Achievement Award"for fundamental contributions to resource allocation in communicationnetworks," the INFOCOM 1994 best paper award, a National ScienceFoundation (NSF) Research Initiation Award (1992), an NSF CAREER Award(1995), an Office of Naval Research Young Investigator Award (1997) and aBodossaki Foundation award (1999). He holds a Ph.D. in ElectricalEngineering from the University of Maryland, College Park (1991). He hasheld faculty positions at Polytechnic University, New York, University ofMaryland, College Park, and University of Thessaly, Greece.

Burstable Instances in the Public Cloud
2017-05-17 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Amazon EC2 and Google Compute Engine (GCE) have recentlyintroduced a new class of virtual machines called "burstable" instancesthat are cheaper than even the smallest traditional/regular instances.These lower prices come with reduced average capacity and increasedvariance. Using measurements from both EC2 and GCE, we identify keyidiosyncrasies of resource capacity dynamism for burstable instances thatset them apart from other instance types. Most importantly, certainresources for these instances appear to be regulated by deterministic,though in one case unorthodox, token bucket like mechanisms. We findwidely different types of disclosures by providers of the parametersgoverning these regulation mechanisms: full disclosure (e.g., CPU capacityfor EC2 t2 instances), partial disclosure (e.g., CPU capacity and remotedisk IO bandwidth for GCE shared-core instances), or no disclosure(network bandwidth for EC2 t2 instances). A tenant modeling thesevariations as random phenomena (as some recent work suggests) might makesub-optimal procurement and operation decisions. We present modelingtechniques for a tenant to infer the properties of these regulationmechanisms via simple offline measurements. We also present two casestudies of how certain memcached workloads might benefit from our modelingwhen operating on EC2 by: (i) temporal multiplexing of multiple burstableinstances to achieve the CPU or network bandwidth (and thereby throughput)equivalent of a more expensive regular EC2 instance, and (ii) augmentingcheap but low availability in-memory storage offered by spot instances withbackup of popular content on burstable instances. Work in collaborationwith Cheng Wang, Bhuvan Urgaonkar and Neda Nasiriani

Communication Protocols in Wireless Body Area Networks (WBAN)
2017-05-10 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
The rapid advances in sensors and ultra-low power wirelesscommunication has enabled a new generation of wireless sensor networks:Wireless Body Area Networks (WBAN). WBAN is a recent challenging area inthe health monitoring domain. There are several concerns in this arearanging from energy efficient communication to designing delays efficientprotocols that support nodes dynamic induced by human body mobility. WBANis a promising technology and shall be increasingly necessary formonitoring, diagnosing and treating populations.In this work we areinterested in WBAN where sensors are placed on the body. In this type ofnetworks sensors performances are tremendously influenced by the human bodymobility. Thus, we investigate different communication primitives using arealistic human body mobility and channel models issued from a recentresearch on biomedical and health informatics.

Cloud RAN for Mobile Networksâ€”A Technology Overview
2017-05-09 16:00 - 17:30 | Telecom ParisTech (Main Building), 46, rue Barrault, Paris,75013, France
Cloud Radio Access Network (C-RAN) is a novel mobile networkarchitecture which can address a number of challenges the operators facewhile trying to support growing end userâ€™s needs. The main ideabehind C-RAN is to pool the Baseband Units (BBUs) from multiple basestations into centralized BBU Pool for statistical multiplexing gain,while shifting the burden to the high-speed wireline transmission ofIn-phase and Quadrature (IQ) data. C-RAN enables energy efficient networkoperation and possible cost savings on baseband resources. Furthermore, itimproves network capacity by performing load balancing and cooperativeprocessing of signals originating from several base stations.

5G Network Architecture and the Future Mobile Internet
2017-05-03 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Abstract:
This talk provides a discussion of one of thecentral design challenges associated with next-generation 5G wirelesssystems - that of effectively converging 3GPP-based mobile networks withthe global Internet. Although the trend towards "flat" IP-basedarchitectures for cellular networks is well under way with LTE,significant architectural evolution will be needed to achieve the goal ofsupporting the needs of mobile devices and applications as "first-class"services on the Internet. Several emerging mobility service scenariosincluding hetnet/small cell, multi-network access, mobile cloud, IoT(Internet-of-Things) and V2V (vehicle-to-vehicle) are examined and relatednetwork service requirements such as user mobility, disruption tolerance,multi-homing, content/service addressability and context-aware deliveryare identified. Drawing from our experience with the ongoing NSF-sponsoredMobilityFirst future Internet architecture project, we outline anamed-object protocol solution based on the GUID (Globally UniqueIdentifier) Service Layer which enables a clean separation of naming andaddressing, and provides intrinsic support for a wide variety of mobilityservices. The talk concludes with a brief outline of the MobilityFirstproof-of-concept prototype currently being deployed on the GENI meso-scalenetworking testbed.

Biography:
Dipankar Raychaudhuri is DistinguishedProfessor, Electrical & Computer Engineering and Director, WINLAB(Wireless Information Network Lab) at Rutgers University. As WINLAB'sDirector, he is responsible for an internationally recognizedindustry-university research center specializing in wireless technology. Heis also PI for several large U.S. National Science Foundation fundedprojects including the ORBIT wireless testbed and the MobilityFirst futureInternet architecture.Dr. Raychaudhuri has previously held corporateR&D positions including: Chief Scientist, Iospan Wireless (2000-01),AGM & Dept Head, NEC Laboratories (1993-99) and Head, BroadbandCommunications, Sarnoff Corp (1990-92). He obtained the B.Tech (Hons) fromIIT Kharagpur in 1976 and the M.S. and Ph.D degrees from SUNY, Stony Brookin 1978, 79. He is a Fellow of the IEEE.

scikit learn demo session
2017-04-27 10:00 - 12:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
The next talk in the ML workgroup will be given by OlivierGrisel on scikit learn as a demo session.

It also possible to attendwithout a laptop and just follow what Olivier will present on the videoprojector.

Attendees who want to follow the demo in a hands on fashion,should install anaconda https://www.continuum.io/downloads

Make sure youcan start a jupyter notebook and execute a cell with the following pythonstatements:
import numpy as np
import matplotlib.pyplot as plt
importsklearn
print(sklearn.__version__)
You can also git clone the followingrepository: https://github.com/ogrisel/notebooksThere will be an update byOlivier Grisel the week of April 27, so be sure to update at the lastminute!

High-Performance Modeling and Simulation of Computer Networks
2017-04-26 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Abstract:

Modeling and simulation (M&S) plays animportant role in the design analysis and performance evaluation of complexsystems. Many of these systems, such as computer networks, involve alarge number of interrelated components and processes. Complex behaviorsemerge as these components and processes inter-operate across multiplescales at various granularities. M&S must be able to providesufficiently accurate results while coping with the scale andcomplexity.

My talk will focus on two novel techniques inhigh-performance network modeling and simulation. The first is aGPU-assisted hybrid network traffic modeling method. The hybrid approachoffloads theÂ computationally intensive bulk traffic calculations to thebackground onto GPU, while leaving detailed simulation of networktransactions in the foreground on CPU. Our experiments show that theCPU-GPU hybrid approach can achieve significant performanceÂ improvementover the CPU-only approach.

The second technique isÂ a distributednetwork emulation method based on simulation symbiosis.Â Mininet is acontainer-based emulation environment that can study networks consisted ofvirtual hosts and OpenFlow-enabled virtual switches on Linux. It iswell-known, however, that experiments using Mininet may lose fidelity forlarge-scale networks and heavy traffic load. The proposed symbioticapproach uses an abstract network model to coordinate distributed Mininetinstances with superimposed traffic to represent large-scale networkscenarios.

Short Bio:

Dr. Jason Liu is currently an AssociateProfessor at the School of Computing and Information Sciences, FloridaInternational University (FIU). He received a B.A. degree from BeijingUniversity of Technology in China in 1993, an M.S. degree from College ofWilliam and Mary in 2000, and a Ph.D. degree in from Dartmouth College in2003. He was also a postdoctoral researcher at University of Illinois,Urbana-Champaign in 2003-2004 and also an Assistant Professor at ColoradoSchool of Mines during 2004-2007. His research focuses on parallelsimulation and performance modeling of computer systems and communicationnetworks.Â He served both as General Chair and Program Chair for severalconferences, and Â is currently on the steering committee ofSIGSIM-PADS, and on the editorial board of ACM Transactions on Modelingand Computer Simulation (TOMACS) and SIMULATION, Simulation Transactionsof the Society for Modeling and Simulation International.Â He is an NSFCAREER awardee (2006) and an ACM Distinguished Scientist (2014). Hisresearch has been funded by various US federal agencies, including NSF,DOE, DOD, and DHS.

Load Balancing in Heterogeneous Networks Based onDistributedLearning in Near-Potential Games
2017-04-19 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
We present a novel approach for distributed load balancingin
heterogeneous networks that use cell range expansion (CRE) foruser
association and almost blank subframe (ABS) forinterference
management. First, we formulate the problem as aminimisation of an
alphaÃ¢fairness objective function with load andoutage constraints.
Depending on alpha, different objectives in terms ofnetwork
performance or fairness can be achieved. Next, we modelthe
interactions among the base stations for load balancing asa
near-potential game, in which the potential function isthe
alphaÃ¢fairness function. The optimal pure Nash equilibrium (PNE) ofthe
game is found by using distributed learning algorithms. Wepropose
log-linear and binary log-linear learning algorithms for completeand
partial information settings, respectively. We give a detailed proofof
convergence of learning algorithms for a near-potential game.We
provide sufficient conditions under which the learningalgorithms
converge to the optimal PNE. By running extensive simulations,we show
that the proposed algorithms converge within few hundredsof
iterations. The convergence speed in the case of partialinformation
setting is comparable to that of the complete informationsetting.
Finally, we show that outage can be controlled and a betterload
balancing can be achieved by introducing ABS.Joint work withPierre
Coucheney, and Marceau Coupechoux, in IEEE Transactions onWireless
Communications (Vol. 15, No. 7, 2016).

Load Balancing in Heterogeneous Networks Based onDistributedLearning in Near-Potential Games
2017-04-19 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
We present a novel approach for distributed load balancing inheterogeneous networks that use cell range expansion (CRE) for userassociation and almost blank subframe (ABS) for interference management.First, we formulate the problem as a minimisation of analphaÃ¢Ë†â€™fairness objective function with load and outageconstraints. Depending on alpha, different objectives in terms of networkperformance or fairness can be achieved. Next, we model the interactionsamong the base stations for load balancing as a near-potential game, inwhich the potential function is the alphaÃ¢Ë†â€™fairnessfunction. The optimal pure Nash equilibrium (PNE) of the game is found byusing distributed learning algorithms. We propose log-linear and binarylog-linear learning algorithms for complete and partial informationsettings, respectively. We give a detailed proof of convergence oflearning algorithms for a near-potential game. We provide sufficientconditions under which the learning algorithms converge to the optimal PNE.By running extensive simulations, we show that the proposed algorithmsconverge within few hundreds of iterations. The convergence speed in thecase of partial information setting is comparable to that of the completeinformation setting. Finally, we show that outage can be controlled and abetter load balancing can be achieved by introducing ABS.Joint work withPierre Coucheney, and Marceau Coupechoux, in IEEE Transactions onWireless Communications (Vol. 15, No. 7, 2016).

Random walks on graphs
2017-04-18 16:00 - 17:00 | Telecom ParisTech (Main Building), 46, rue Barrault, Paris,75013, France
A sample of the results of Lovasz' paper

Wireless Node Cooperation with Resource Availability Constraints
2017-04-12 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Base station cooperation is a promising scheme to improvenetwork performance for next generation cellular networks. Up to this pointresearch has focused on station grouping criteria based solely ongeographic proximity. However, for the cooperation to be meaningful, eachstation participating in a group should have sufficient available resourcesto share with others. In this work we consider an alternative groupingcriterion based on a distance that considers both geographic proximity andavailable resources of the stations. When the network is modelled by aPoisson Point Process, we derive analytical formulas on the proportion ofcooperative pairs or single stations, and the expected sum interferencefrom each of the groups. The results illustrate that cooperation gainsstrongly depend on the distribution of available resources over thenetwork. Joint work with Anastasios Giovanidis, Philippe Martins, LaurentDecreusefond, to appear at SpaSWiN 2017.

Stateful programmable data planes
2017-04-05 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Abstract:
In Software Defined Networking (SDN) thecontrol plane is physically separate from the forwarding plane. Controlsoftware programs the forwarding plane (e.g., switches and routers) usingan open interface, such as OpenFlow. SDN envisions smart centralizedcontrollers governing the forwarding behaviour of dumb low-costswitches.Even if this approach presents several benefits (scalability,vendor independence, easiness of deployment etc.) it is often limited bythe continuous intervention of the logically centralized controller (defacto complex distributed systems) to take decisions just based on localstates (versus network-wide knowledge), which could be in principledirectly handled at wire speed inside the device itself. Stateful dataplaneprocessing is recently emerged as a enabling technology to supersede thislimitation and to deploy virtual network functions at wire-speed.This talkwill present Open Packet Processor (OPP), a stateful programmabledataplane abstraction that extend the OpenFlow match-action model addingthe concept of a per-flow content that is used to represent the history ofeach flow travelling into the switch. OPP extracts a (configurable)flow-key from the incoming packet and update the flow content (and theassociated forwarding decision) using some OpenFlow-like rules that definean Extended Finite State Machine (EFSM). The EFSM reads the current state,the value of the flow-registers and the content of the packet and decidethe next state, update the flow-register values and set the action toapply to the packet.The talk will show an high-speed hardwareimplementation of a OPP based switch realized on an FPGA board with 4x10GbE ports and some use cases that leverage the features of the OPPabstraction. A comparison with the most relevant work in the field ofstateful dataplane processing will be presented and compared with the OPPabstraction. Finally the talk will discuss the OPP limitations andextensions.

Biography:
Salvatore Pontarelli received the masterDegree at university of Bologna in 2000. In 2003 takes its PhD degree inmicroelectronics and telecommunications from the University of Rome TorVergata. Currently, he works as Researcher at CNIT (Italian Consortium oftelecommunication), in the research unit of University of Rome TorVergata. In the past Dott. Pontarelli has worked with the National ResearchCouncil (CNR), the Department of Electronic Engineering of University ofRome Tor Vergata, the Italian Space Agency (ASI), the University ofBristol.He also works as consultant for various Italian and Internationalcompanies for design of hardware for high speed networking. He participatesin several national and EU funded research program (ESA, FP7 and H2020).In 2011 he was recipient of a CISCO research Award for the study on thecombined use of Bloom filters and Ternary CAM. His main research activitiesare hash based structures for networking applications, use of FPGA forhigh speed network monitoring, hardware design of software defined networkdevices, stateful programmable data planes.

Stable matchings: roommates, marriage and kidneys
2017-04-04 16:00 - 17:30 | Telecom ParisTech (Main Building), 46, rue Barrault, Paris,75013, France
Fabien Mathieu will present Stable matchings: roommates,marriage and kidneys

Starting point to learn about stable matchings: Mariages stables (Dominique Dumont)

Sensing spatial structures in online social networks
2017-03-29 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
More details coming soon

Research Overflow: pre-KickOff
2017-03-28 14:00 - 16:00 | Salle 26, 23, avenue d'Italie, Paris, 75013, France
An early, informal meeting, to discuss the whereabouts of theResearch Overflow working group.

Tentative ordre du jour

Link withthe Lincs Upgrade Yourself Academy: train in the art of writing articlesand reviews

Only pointers to biblio?
Give a few courses? ([FM] afew ideas: Correctness/Impact/Flow classification, learn from the best)
Shepherded reviews: group reviews / senior+Phd review?

Design of aResearch Overflow approach
List of Lincs scientific research that couldbe made using RO as a possible use case
Parsing the earlybibliography.

Application of the Mellin transform to suffix trees and tries
2017-03-21 16:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Anne Bouillard will present

Average size of a suffix treefor Markov sources, Jacquet, Szpankowaki, 2016

ResearchOverflow
2017-03-15 11:30 - 11:45 | Meudon, Best Western Meudon, Meudon, France
Research is broken. We can rebuild it. We have the technology.

Meeting IoT #03
2017-03-13 16:00 - 18:00 | LINCS room 26, 23, avenue d'Italie, Paris, 75013, France
3 short presentations:

Overview of a survey about IoT(Nesrine Ammar);
Presentation about Wireless Body Area Networks (GewuBu);
Presentation of issues on transparency and privacy in IoT(Vassilis Christophides).

Wi-Fi Direct-based Device-to-Device Communications for DenseWireless Networks
2017-03-08 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Wi-Fi Direct is a popular wireless technology which isintegrated in most of today's smartphones and tablets. This technologyallows a set of devices to dynamically negotiate and select a group ownerwhich plays the role of access point. We demonstrate that Wi-FiDirect-based Device-to-Device (D2D) communications can be used to offloadWi-Fi access points in a dense wireless network. Clustering, power controland transmission scheduling techniques are applied to optimize the networkperformances and reduce the file download time up to 30%.

Mellin transform and asymptotics: harmonic sums
2017-03-07 16:00 - 17:30 | Telecom ParisTech (Main Building), 46, rue Barrault, Paris,75013, France
Anne Bouillard will present

Mellin transform andasymptotics: harmonic sums, Flajolet, Gourdon and Dumas, 1995

Bits of Machine Learning, Part 2
2017-03-06 13:30 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
A second introduction to Machine Learning.

Bits of Machine Learning, Part 1
2017-03-03 13:30 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
A first introduction to Machine Learning.

Joint Cyber Insurance and Security-as-a-Service Provisioning inCloud Computing
2017-03-03 11:00 - 12:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
As computing services are increasinglycloud-based, corporations are investing in cloud-based security measures.The Security-as-a-Service (SECaaS) paradigm allows customers to outsourcesecurity to the cloud, through the payment of a subscription fee.However, no security system is bulletproof, and even one successfulattack can result in the loss of data and revenue worth millions ofdollars. To guard against this eventuality, customers may also purchasecyber insurance to receive recompense in the case of loss. To achieve costeffectiveness, it is necessary to balance provisioning of security andinsurance, even when future costs and risks are uncertain. Thispresentation introduces a stochastic optimization model to optimallyprovision security and insurance services in the cloud. Since the model isa mixed integer problem, we also introduce a partial Lagrange multiplieralgorithm that takes advantage of the total unimodularity property to findthe solution in polynomial time. We show the effectiveness of thesetechniques using numerical results based on real attack data to demonstratea realistic testing environment, and find that security and insurance areinterdependent.

Biography:
Dusit Niyato is currently an associateprofessor in the School of Computer Science and Engineering, at theNanyang Technological University, Singapore. He received B.E. from KingMongkukÃ¢â‚¬â„¢s Institute of Technology Ladkrabang (KMITL),Thailand in 1999 and Ph.D. in Electrical and Computer Engineering from theUniversity of Manitoba, Canada in 2008. He has published more than 300technical papers in the area of wireless and mobile networking and authoredthe books "Resource Management in Multi-Tier Cellular Wireless Networks","Game Theory in Wireless and Communication Networks: Theory, Models, andApplications" and "Dynamic Spectrum Access and Management in CognitiveRadio Networks". He won the Best Young Researcher Award of IEEECommunications Society (ComSoc) Asia Pacific (AP) and The 2011 IEEECommunications Society Fred W. Ellersick Prize Paper Award. He is adistinguished lecturer of the IEEE Communications Society. His works havereceived more than 13,000 citations (Google Scholar).Currently, he servesas an area editor of IEEE Transactions on Wireless Communications (RadioManagement and Multiple Access), an associate editor of IEEE Transactionson Communications, an editor of IEEE Communications Surveys and Tutorials(COMST), and IEEE Transactions on Cognitive Communications and Networking(TCCN). He was a guest editor of IEEE Journal on Selected Areas onCommunications, special issue on Cognitive Radio Networking &Communications, and Recent Advances in Heterogeneous Cellular Networks. Heis a Fellow of IEEE.

Named-Object Based Services in the Future Internet Architecture
2017-03-01 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
After many years of constant evolution, the Internet hasapproached a historic inflection point where mobile platforms,applications and services are poised to replace the fixed-host/server modelthat has dominated the Internet since its inception. Driven by thestrikingly different Internet population of mobile devices and services,new fundamental communication abstractions are required and the current IPbased Internet fails to meet their requirement in a satisfying fashion.Starting from these key considerations, this talk aims to introduce theaudience to a new approach to networking, that centers around the centralarchitectural concept of Named-Object based networking and the power thatlies behind it. Looking at the different architectures presented over theyears, a set of new fundamental abstractions are defined, providing acomprehensive analysis of their properties and how they could be met. Thisstudy leads to the presentation of the MobilityFirst architecture in whichthe "narrow waist" of the protocol stack is based on Named-Objects whichenable a broad range of capabilities in the network.As an example of thepotential of the Named-Object abstraction, an analysis of how advancedcloud services can be supported in the proposed architecture is presented.In particular, the concept of naming is extended to natively supportvirtual network identifiers. It is shown that the virtual networkcapability can be designed by introducing the concept of a "Virtual NetworkIdentifier (VNID)" which is managed as a Named-Object. Further, the designsupports the concept of Application Specific Routing (ASR) which enablesnetwork routing decisions to be made with awareness of applicationparameters such as cloud server workload. Experimental results show thatthe new framework provides a clean and simple logic for defining andmanaging virtual networks while limiting the performance impact produced bythe additional overhead generated by running such system. Moreover, usinga prototype of the architecture deployed on a nation-wide testbed, thepotential of ASR is demonstrated in a cloud service scenario.

Meeting IoT #02
2017-02-27 16:00 - 18:00 | LINCS room 26, 23, avenue d'Italie, Paris, 75013, France
Consolidation of the future activities of the working group.

Insensitivity of Loss Systems under Randomized SQ(d) Algorithms
2017-02-22 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
In many applications such as cloud computing,managing server farm resources etc. an incoming task or job has to bematched with an appropriate server in order to minimise the latencyassociated with the processing. Ideally the best choice would be to match ajob to the fastest available server. However when there are thousands ofservers obtaining the information on server tasks is expensive. Pioneeredin the 1990's the idea of randomised sampling of a few servers was proposedby Vvedenskaya and Dobrushin in Russia and Mitzmenmacher in the US andpopularised as the "power of two" schemes which basically means thatsampling two servers randomly and sending the job to the "better" server(i.e. with the shortest queue, or most resources) provides most of thebenefits of sampling all the servers.In the talk I will discussmulti-server loss models under power-of-d routing scheme when service timedistributions are general with finite mean. Previous works on these modelsassume that the service times are exponentially distributed andinsensitivity was suggested through simulations. Showing insensitivity toservice time distributions has remained an open problem. We address thisproblem by considering service time distributions as Mixed-Erlangdistributions that are dense in the class of general distributions on (0,infty). We derive the mean field equations (MFE) of the empiricaldistributions for the system and establish the existence and uniqueness ofthe fixed point of the MFE. Furthermore we show that the fixed point of theMFE corresponds to the fixed point obtained from the MFE corresponding to asystem with exponential service times showing that the fixed point isinsensitive to the distribution. We provide numerical evidence of theglobal asymptotic stability of the fixed point, which would then implythat the fixed point is indeed the stationary distribution. We concludewith a brief discussion of the case of the MFE with general service timesshowing that the MFE is now characterized by a pde whose stationary pointcoincides with the fixed point in the case with exponential servicetimes.The techniques developed in this paper are applicable to study meanfield limits for Markov processes on general state spaces and insensitivityproperties of other queueing models.

Biography:
The speaker waseducated at the Indian Institute of Technology, Bombay (B.Tech, 1977),Imperial College, London (MSc, DIC, 1978) and obtained his PhD under A.V. Balakrishnan at UCLA in 1983.He is currently a University Research ChairProfessor in the Dept. of ECE at the University of Waterloo,Ont., Canadawhere he has been since September 2004. Prior to this he was Professor ofECE at PurdueUniversity, West Lafayette, USA. He is a D.J. GandhiDistinguished Visiting Professor at the Indian Institute of Technology,Bombay. He is a Fellow of the IEEE and the Royal Statistical Society. He isa recipient of the Best Paper Awards at INFOCOM 2006, the InternationalTeletraffic Congress 2015, Performance 2015, and was runner-up for theBest Paper Award at INFOCOM 1998.His research interests are in modeling,control, and performance analysis of both wireline and wirelessnetworks,and in applied probability and stochastic analysis with applications toqueueing, filtering, and optimization.

The formal Theory of Birth-and-death processes, lattice pathcombinatorics and continuous fractions
2017-02-21 16:00 - 17:30 | Telecom ParisTech (Main Building), 46, rue Barrault, Paris,75013, France
CÃ©line Comte and Ã‰lie de Panafieu will present

Theformal Theory of Birth-and-death processes, lattice path combinatorics andcontinuous fractions, Flajolet and Guillemin, 2000

Meeting IoT #01
2017-02-20 16:00 - 18:00 | LINCS room 26, 23, avenue d'Italie, Paris, 75013, France
Kick-off meeting. Initial discussions about interests of peoplein IoT and about objective of this group at LINCS

Real option game theoretic framework for investment decisions inmobile TV
2017-02-15 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We present a strategic investment framework for mobile TVdelivery by two potential operators: broadcaster (DVB) and cellular (MNO),in the presence of demand and operating cost uncertainties. We consider twosettings: a cooperative one where the two operators run a convergent hybridnetwork, and a competitive one in which each operator builds its ownnetwork, if it decides to enter the market. We define a real option gametheoretic framework and propose a new bi-level dynamic programmingalgorithm that solves the optimal profit maximization problem and yieldsthe optimal investment decisions of both players.

Data Protection by Means of Fragmentation
2017-02-08 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Although symmetric ciphers may provide strongcomputational security, a key leakage makes the encrypted data vulnerable.In a distributed storage environment, reinforcement of data protectionconsists of dispersing data over multiple servers in a way that noinformation can be obtained from data fragments until a defined thresholdof them has been collected. A secure fragmentation is usually enabled bysecret sharing, information dispersal algorithms or data shredding.However, these solutions suffer from various limitations, like additionalstorage requirement or performance burden. Therefore, we introduce a novelflexible keyless fragmentation scheme, balancing memory use andperformance with security. It could be applied in many different contexts,such as dispersal of outsourced data over one or multiple clouds or inresource-restrained environments like sensor networks.

QoE Management for Internet Applications: Technologies andChallenges
2017-02-03 10:00 - 11:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
The talk starts by presenting the currentapproaches for a QoE-aware service management in the Internet, i.e.,application oriented or network management, which are mostly characterizedby the tools available by the stakeholders implementing the process andalso by their own interests. Then, the current limits and issues of theseapproaches are highlighted, together with the current directions ofdevelopment in the field. These are mostly characterized by a strongevolution towards the virtualization of the services through theintroduction of the SDN and NFV paradigms. These allow for a more flexiblemanagement of the services with a better control of the QoE and for apotential stronger cooperation among the different actors involved in theservice provisioning chain.

Biography:
Luigi Atzori (SM'09) isAssociate Professor at the Department of Electrical and ElectronicEngineering at the University of Cagliari (Italy), where he leads thelaboratory of Multimedia and Communications with around 15 affiliates(http://mclab.diee.unica.it). L. Atzori research interests are inmultimedia communications and computer networking (wireless and wireline),with emphasis on multimedia QoE, multimedia streaming, NGN servicemanagement, service management in wireless sensor networks, architectureand services in the Internet of Things. He is the coordinator of the MarieCurie Initial Training Network on QoE for multimedia services(http://qoenet-itn.eu), which involves ten European Institutions in Europeand one in South Korea. He has been the editor for the ACM/SpringerWireless Networks Journal and guest editor for many journals, includingthe IEEE Communications Magazine, the Springer Monet and the ElsevierSignal Processing: Image Communications Journals. He is member of thesteering committee for the IEEE Trans. on Multimedia, member of theeditorial board of the IEEE IoT, the Elsevier Ad Hoc Networks and theElsevier Digital Communications and Networks journals. He served as atechnical program chair for various international conferences andworkshops. He served as a reviewer and panelist for many funding agencies,including H2020, FP7, Cost and Italian MIUR.

The FUTEBOL project - experimentation on the optical/wirelessnetwork frontier
2017-02-01 15:00 - 16:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
This talk will present the FUTEBOL project, which is a jointEU-Brazilproject focused on the creation of experimental testbeds.TheprojectÃ¢â‚¬â„¢s goal is to allow the access to advancedexperimentalfacilities in Europe and Brazil for research and educationacross thewireless and optical domains. To accomplish this, we willdevelop aconverged control framework to supportoptical/wirelessexperimentation on the federated research infrastructurefrom allassociated partners/institutions. Further, industry-driven usecaseswill be demonstrated using this testbed to produce advances inresearchat the optical/wireless boundary. The talk will provide anoverview of theproject, presenting the proposed testbeds as well asthe experiments thatwe will perform to showcase the importance ofoptical/wireless integrationon todayÃ¢â‚¬â„¢s networks. Those use casesinvolve topics such asC-RAN and radio over fiber and low latencynetworking for real-timeapplications on IoT and immersive services.

PEERING: An AS for Us
2017-02-01 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
PEERING is a testbed that provides safe and easy access forresearchers to the Internet's BGP routing system, enabling and inspiringtransformational research. Traditionally, the barriers to conduct Internetrouting experiments hindered progress. Most research on interdomain routingis either based on passive observation of existing routes, which cannotcapture how the Internet will respond to changes in protocols or policies,or based on simulations, whose fidelity is restricted by known limitationsin our understanding of Internet topology and policy. To move beyond theselimited experimental approaches, the PEERING testbed connects (via BGP)with real networks at universities and Internet exchange points around theworld. Instead of being observers of the Internet ecosystem, researchersbecome participants, running experiments that announce/select routes andsend/receive traffic directly with these networks. In this talk, wepresent an introduction to the testbed and a sample of the research it hasenabled.

Towards a Networking ``Characteristica Universalis''
2017-01-25 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Most unwritten languages today have no known grammar, and arerather governed by "unspoken rules". Similarly, we think that the youngdiscipline of networking is still a practice that lacks a deepunderstanding of the rules that govern it. This situation results in a lossof time and efforts. First, since the rules are unspoken, they are notsystematically reused. Second, since there is no grammar, it isimpossible to assert if a sentence is correct. Comparing two networkingapproaches or solutions is sometimes a synonym of endless religiousdebates. Drawing the proper conclusion from this claim, we advocate thatnetworking research should spend more efforts on better understanding itsrules as a first step to automatically reuse them. To illustrate ourclaim, we focus in this work on one broad family of networkingconnectivity problems. We show how different instances of this problem,which were solved in parallel with no explicit knowledge reuse, can bederived from a small set of facts and rules implemented in aknowledge-based system.

Summarizing Performance Samples with Extrema rather than Averages:A Lesson from Practitioners
2017-01-18 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
The notion of performance seems crucial to many fields ofscience and engineering. Some scientists are concerned with the performanceof algorithms or computing hardware, others evaluate the performance ofcommunication channels, of materials, of chemicals, psychologistsinvestigate the performances of experimental participants, etc. Yet,rather surprisingly, the performance notion is generally used without anyexplicit definition. I propose this: a performance is a quantitativebehavioral measure that an agent deliberately tries to either minimize ormaximize. The scope of the performance concept seems impressively large:the agent whose behavioral performance is being scored may be a human, acoalition of humans (e.g., an enterprise, an academic institution), oreven a human product (e.g., a chemical, an algorithm, a marketshare).Performance measures are random variables of a very special sort:their distributions are strongly skewed as a direct consequence of theextremization (minimization or maximization) pressure that constitutestheir defining characteristic. Mainstream statistics takes it for grantedthat any distribution needs to be summarized by means of somerepresentative central-tendency indicator (e.g., an arithmetic mean, amedian), and so the asymmetry of performance distributions has beentraditionally considered an unfortunate complication. In fact I will arguethat when it comes to statistics of performance, averages becomeessentially irrelevant. The point is easy to make with the example ofspirometry testing: practitioners of spirometry never compute an average,they retain the best measure of respiratory performance (i.e., the samplemax) and flatly discard all other measures. And they are quite right to doso, as a simple model will help explain. The important general lesson tobe learned from spirometry is that the better a sample measure ofperformance, the more valid as an estimate of the capacity ofperformance---the theoretical upper limit whose estimation is in fact thegoal of most performance testing in experimental science. One likely reasonwhy experimenters of many fields have recourse to the measurement ofperformances is because non-extremized behavior tends to be random,whereas performance capacities can abide by quantitative laws. This is easyto illustrate with empirical data from human experimental psychology(Hick's law, George Miller's magic number, Fitts' law). An experimentermyself, I can only conclude with a question to statisticians: i.e.,donÃ¢â‚¬â„¢t we need a brand new sort of statistics to fullyacknowledge and accommodate the rather special nature of all theseperformance measures that these days we encounter everywhere, not just invirtually every sector of society but also in many field of scientificresearch

The many faces of fault-tolerant and Byzantine tolerant distributedcomputing
2017-01-11 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
The tolerance to faults and Byzantine behaviors has a longtradition in distributed computing. Now, more than ever, fault-tolerantand Byzantine tolerant distributed computing finds its application invarious emergent areas raging from sensor networks to distributed storageand blockchains. This talk presents recent results on how distributedcomputing deals with various incarnations of faults and Byzantine behaviorswith case studies taken from body area networks, mobile robots networks,distributed storage and blockchains.

Modeling and algorithms for IoT service characterization andrecommendation
2016-12-14 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Connected devices, as key constituent elements of the Internetof Things (IoT), are flooding our real world environment. This digitalwave paves the way for a major technological breakthrough called to deeplychange our daily lives. Nevertheless, some strong issues remain to beaddressed. The most dominant one relates to our ability to leverage thewhole IoT service space and, more specifically, to our ability to composeIoT services from multiple connected devices by cleverly selecting themwith the required software functions, whatever our technical skills. Insuch a challenging context, we first propose a rich and flexibleabstraction framework relying on Attributed Typed Graphs, which enables torepresent how known IoT services are composed from different perspectives.Then, capitalizing on this modeling tool and focusing on the way IoTservices interact with the physical environment, lightweight servicesignatures are computed by using a physical-interfaced-based algorithm inorder to characterize IoT services. Finally, we discuss how leveraging thecomputed signatures can allow for autonomously recommending IoT services toend-users.

IRT SystemX: le programme "Internet de Confiance" et leprojet "Cloud et virtualisation"
2016-12-07 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Presentation du programme IRT SystemX qui comprend lesthÃ©matiques CybersÃ©curitÃ© et Ã©volutionsdes architecturesrÃ©seaux.

Granger Causality Networks: Causal Inference for Time Series Data
2016-12-06 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Identifying causal (rather thanmerely
correlative)relationships in physical systems is a difficulttask,
particularly ifit is not feasible to perform controlledexperiments.
Granger'snotion of causality was developed first in economicsbeginning
in the1960s and can be used to form a network of"plausible
causalrelations" given only the opportunity to observe thesystem.
Thismethod is applied, for example, in neuro-imagingto
identifyrelationships amongst brain regions, and in biostatisticsto
exploregene regulatory networks. In this talk, we provide anoverview
of thenotion of Granger Causality, some methods forlearning
GrangerCausality Networks in practice, and our currentdirections
forresearch.

A BILEVEL MODEL OF FACILITY LOCATION THAT INVOLVESâ€¨COMPETITION, SELFISH USERS AND QUEUES
2016-12-01 11:00 - 12:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
In a competitive setting, we consider the problem faced by afirm that makes decisions concerning both the location and service levelsof its facilities, taking into account that users patronize the facilitythat maximizes their individual utility, expressed as the sum of traveltime, queueing delay, and a random term. This situation can be modelledas a mathematical program with equilibrium constraints that involvesdiscrete and continuous variables, as well as linear and nonlinearfunctions. This program is reformulated as a standard bilevel program thatcan be approximated, through the linearization of the nonlinear functionsinvolved, as a mixed integer linear program that yieldsâ€˜quasi-optimal' solutions. Since this approach does not scale well,we have in parallel developed heuristic procedures that exploit the verystructure of the problem. Based on theoretical and computation resultspertaining to this application, we will discuss further developments inthe area of nonlinear facility location.

Variable neighborhood prediction of temporal collective profiles inweb services usage
2016-11-30 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Temporal collective profiles generated by mobile network userscan be used to predict network usage, which in turn can be used to improvethe performance of the network to meet user demands. This presentation willtalk about a prediction method of temporal collective profiles which issuitable for online network management. Using weighted graphrepresentation, the target sample is observed during a given period todetermine a set of neighboring profiles that are considered to behavesimilarly enough. The prediction of the target profile is based on theweighted average of its neighbors, where the optimal number of neighborsare selected through a form of variable neighborhood search. This method isapplied to two datasets, one provided by a mobile network service providerand the other from a Wi-Fi service provider. The proposed prediction methodcan conveniently characterize user behavior via graph representation,while outperforming existing prediction methods. Also, unlike existingmethods that utilize categorization, it has a low computationalcomplexity, which makes it suitable for online network analysis.

Pinpointing Delay and Forwarding Anomalies Using Large-ScaleTraceroute Measurements
2016-11-23 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Understanding network health is essential to improvingInternet reliability. For instance, detecting disruptions in peer andprovider networks identifies fixable connectivity problems. Currently thistask is time consuming as it involves a fair amount of manual observationbecause operators have little visibility into other networks.Here weleverage existing public RIPE Atlas measurement data to monitor and analyzenetwork conditions; creating no new measurements. We demonstrate a set ofcomplementary methods to detect network disruptions using traceroutemeasurements. A novel method of detecting changes in delay is used toidentify congested links, and a packet forwarding model is employed topredict traffic paths and to identify faulty routers and links in cases ofpacket loss. In addition, aggregating results from each method allows usto easily monitor a network and identify coordinated reports manifestingsignificant network disruptions, reducing uninteresting alarms.Ourcontributions consist of a statistical approach to providing robustestimation or Internet delays and the study of hundreds of thousands linkdelays. We present three cases demonstrating that the proposed methodsdetect real disruptions and provide valuable insights, as well assurprising findings, on the location and impact of identifiedevents.

WalkSCAN: Improving PageRank for local community detection
2016-11-16 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Community detection is a fundamental problem in the field ofgraph mining. The objective is to find densely connected clusters ofnodes, so-called communities, possibly overlapping. While most existingalgorithms work on the entire graph, it is often irrelevant in practice tocluster all nodes. A more practically interesting problem is to detect thecommunity to which a given set of nodes, the so-called "seed nodes",belong. Moreover, the exploration of the whole network is generallycomputationally expensive, if not impossible, and algorithms that onlytake into account the local structure of the graph around seed nodesprovide a big advantage. For these reasons, there is a growing interest inthe problem of "local" community detection, also known as "seed setexpansion". We solve this problem through a low-dimensional embedding ofthe graph based on random walks starting from the seed nodes.

Prototyping IoT-Cloud Services over Multisite Edge Clouds based onAffordable SmartX K-Clusters
2016-11-08 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Recently we are in the middle of structural changes towardsoftware-defined ICT infrastructure, which attempts to transform theexisting silo-based infrastructure intoÂ futuristicÂ composable one byintegrating IoT-based smart/mobile things, SDN-coordinated interconnectedges, and NFV-assisted and software-driven cloud core. Thisend-user-driven infrastructure transform can be supported by diverseopen-source community projects (e.g., Linux Foundation'sOVS/OpenSwitch/ONOS/CORD/ODL/OPNFV/Open-O/..., Facebook-initiated OCP,and others). Aligning with this upcoming transition, in this talk, theprototyping experience of OF@KOREN & OF@TEIN SmartX playgrounds willbe shared by focusing on the hyper-convergent SmartX Boxes. Then, formultisite edge clouds,Â the on-going design trials of affordable SmartXK-Cluster will be explained. Finally, by leveraging DevOps-basedautomation, preliminaryÂ prototyping for IoT-Cloud services will bediscussed by taking an example service scenario for smart energy.

LibertÃ©, sans fraternitÃ©, est la mort del'Ã©galitÃ© pour video dans l'Internet(Network-layerQoE-fairness for Encrypted Adaptive Video Streams)
2016-11-02 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Netflix, YouTube, and the like, are now the dominant sourcesof traffic on the Internet. Recent studies observe that competing adaptivevideo streams generate flows that lead to instability, under-utilization,and unfairness behind bottleneck links. Additional measurements suggestthere may also be a negative impact on users' perceived quality ofexperience as a consequence. Intuitively, application-generated issuesshould be resolved at the application layer. In this presentation I shalldemonstrate that fairness, by any definition, can only be solved in thenetwork. Moreover, that in an increasingly HTTP-S world, some form ofclient interaction is required. In support, a new network-layer'QoE-fairness' metric will be be introduced that reflects user experience.Experiments using our open-source implementation in the home environmentreinforce the network-layer as the right place to attack the generalproblem. For further reference see:[1]http://dl.ifip.org/db/conf/networking/networking2015/1570066341.pdf [2]https://dl.acm.org/citation.cfmLinks:back to the list item, list top orsummary top

Maximum Coloring of Random Geometric Graphs
2016-10-26 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We have examined maximum vertex coloring of random geometricgraphs, in an arbitrary but fixed dimension, with a constant number ofcolors, in a recent work with S.~Borst. Since this problem is neitherscale-invariant nor smooth, the usual methodology to obtain limit lawscannot be applied. We therefore leverage different concepts based onsubadditivity to establish convergence laws for the maximum number ofvertices that can be colored. For the constants that appear in theseresults, we have provided the exact value in dimension one, and upper andlower bounds in higher dimensions.In an ongoing work with B. Blaszczyszy,we study the distributional properties of maximum vertex coloring of randomgeometric graphs. Moreover, we intend to generalize the study overweakly-$mu$-sub-Poisson processes.

Hands-on series: Jupyter Notebook
2016-10-19 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
The Jupyter Notebook is a web application that allows you tocreate and share documents that contain live code, equations,visualizations and explanatory text. Uses include: data cleaning andtransformation, numerical simulation, statistical modeling, machinelearning and much more. In this hands-on talk, we will learn how to use anotebook, how to use plugins (as well
as a set of useful ones), and howto make online-presentations.

Additional resources available on GitHub.

Caching Games between Content Providers and Internet ServiceProviders
2016-10-12 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We consider a scenario where an Internet Service Provider (ISP)serves users that choose digital content among M Content Providers (CP). Inthe status quo, these users pay both access fees to the ISP and contentfees to each chosen CP; however, neither the ISP nor the CPs share theirprofit. We revisit this model by introducing a different business modelwhere the ISP and the CP may have motivation to collaborate in theframework of caching. The key idea is that the ISP deploys a cache for a CPprovided that they share both the deployment cost and the additional profitthat arises due to caching. Under the prism of coalitional games, ourcontributions include the application of the Shapley value for a fairsplitting of the profit, the stability analysis of the coalition and thederivation of closed-form formulas for the optimal caching policy.Our modelcaptures not only the case of non-overlapping contents among the CPs, butalso the more challenging case of overlapping contents; for the lattercase, a non-cooperative game among the CPs is introduced and analyzed tocapture the negative externality on the demand of a particular CP whencaches for other CPs are deployed.

Joint work with S. Elayoubi, E.Altman, and Y. Hayel to be presented at the 10th EAI InternationalConference on Performance Evaluation Methodologies and Tools (Valuetools2016). The full version of the paper has been selected to be published in aspecial issue of the Elsevier journal of Performance Evaluation (PEVA).

Generalized Threshold-Based Epidemics in Random Graphs: the Powerof Extreme Values
2016-10-05 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Bootstrap percolation is a well-known activation process in agraph,in which a node becomes active when it has at least $r$ activeneighbors.Such process, originally studied on regular structures, hasbeen recentlyinvestigated also in the context of random graphs, where itcan serve as a simplemodel for a wide variety of cascades, such asthespreading of ideas, trends, viral contents, etc. over large socialnetworks.In particular, it has been shown that in $G(n,p)$ the finalactive setcan exhibit a phase transition for a sub-linear number ofseeds.In this paper, we propose a unique framework to studysimilarsub-linear phase transitions for a much broader class of graphmodelsand epidemic processes. Specifically, we consider i) a generalizedversionof bootstrap percolation in $G(n,p)$ with random activationthresholdsand random node-to-node influences; ii) different random graphmodels,including graphs with given degree sequence and graphswithcommunity structure (block model). The common thread of our work istoshow the surprising sensitivity of the critical seed set sizeto extremevalues of distributions, which makes some systems dramaticallyvulnerableto large-scale outbreaks. We validate our results running simulation onbothsynthetic and real graphs.

Joint work with M. Garetto and G. Torrisi,appeared at ACM SIGMETRIC 2016.

Data and Algorithmic Bias in the Web - Amphi Jade (Barrault)
2016-10-03 11:00 - 12:00
Abstract:
The Web is the largest public big datarepository that humankind hascreated. In this overwhelming data ocean, weneed to be aware of thequality and, in particular, of the biases thatexist in this data. Inthe Web, biases also come from redundancy and spam,as well as fromalgorithms that we design to improve the user experience.This problemis further exacerbated by biases that are added by thesealgorithms,specially in the context of search and recommendation systems.Theyinclude selection and presentation bias in many forms, interactionbias,social bias, etc. We give several examples and their relation tosparsityand privacy, stressing the importance of the user context to avoidthesebiases.

Biography:
Ricardo Baeza-Yates areas of expertise areweb search and data mining,information retrieval, data science andalgorithms. He is CTO of NTENT, a semantic search technology company.Before he was VP of Research at Yahoo Labs, based in Barcelona, Spain,and later in Sunnyvale, California, from January 2006 to February 2016.He also is part time Professor at DTIC of the Universitat Pompeu Fabra, inBarcelona, Spain, as well as at DCC of Universidad de Chile in Santiago.Until 2004 he was Professor and founding director of the Center for WebResearch at the later place. He obtained a Ph.D. in CS from the Universityof Waterloo, Canada, in 1989. He is co-author of the best-seller ModernInformation Retrieval textbook published by Addison-Wesley in 2011 (2nded), that won the ASIST 2012 Book of the Year award. From 2002 to 2004 hewas elected to the board of governors of the IEEE Computer Society and in2012 he was elected for the ACM Council. Since 2010 is a founding member ofthe Chilean Academy of Engineering. In 2009 he was named ACM Fellow and in2011 IEEE Fellow, among other awards and distinctions.

n-Backtracking Spectrum of Degree-Corrected Stochastic Block Models
2016-09-28 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Motivated by community detection, we characterise the spectrumof the non-backtracking matrix $B$ in the Degree-Corrected Stochastic BlockModel.Specifically, we consider a random graph on $n$ vertices partitionedinto two equal-sized clusters. The vertices have i.i.d. weights $ phi_u_u=1^n$ with second moment $PHItwo$. The intra-cluster connectionprobability for vertices $u$ and $v$ is $ phi_u phi_v a/b$ and theinter-cluster connection probability is $phi_u phi_v b/n$. We show thatwith high probability, the following holds: The leading eigenvalue of thenon-backtracking matrix $B$ is asymptotic to $rho = (a+b)/2 PHItwo$. Thesecond eigenvalue is asymptotic to $mu_2 = (a+b)/2 PHItwo$ when $mu_2^2> rho$, but asymptotically bounded by $sqrtrho$ when $mu_2^2 leq rho$.All the remaining eigenvalues are asymptotically bounded by $sqrtrho$. As aresult, a clustering positively-correlated with the true communities canbe obtained based on the second eigenvector of $B$ in the regime where$mu_2^2 > rho.$In a previous work we obtained that detection isimpossible when $mu_2^2 < rho,$ meaning that there occurs aphase-transition in the sparse regime of the Degree-Corrected StochasticBlock Model. As a corollary, we obtain that Degree-Corrected Erdos-Renyigraphs asymptotically satisfy the graph Riemann hypothesis, aquasi-Ramanujan property.A by-product of our proof is a weak law of largenumbers for local-functionals on Degree-Corrected Stochastic Block Models,which could be of independent interest.

Network Function Virtualization; Techno-Economics
2016-09-07 14:30 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Network Function Virtualization (NFV) is an emergingapproach
that has received attention from both academia and industry as away to
improve flexibility, efficiency, and manageability of networks.NFV
enables new ways to operate networks and to provide compositenetwork
services, opening the path toward new business models. As incloud
computing with the Infrastructure as a Service model, clients willbe
offered the capability to provision and instantiate VirtualNetwork
Functions (VNF) on the NFV infrastructure of the networkoperators. In
this paper, we consider the case where leftover VNFcapacities are
offered for bid. This approach is particularly interestingfor clients
to punctually provision resources to absorb peak orunpredictable
demands and for operators to increase their revenues. Wepropose a game
theoretic approach and make use of Multi-Unit CombinatorialAuctions to
select the winning clients and the price they pay. Such aformulation
allows clients to express their VNF requests according totheir
specific objectives. We solve this problem with a greedy heuristicand
prove that this approximation of economic efficiency is theclosest
attainable in polynomial time and provides a payment systemthat
motivates bidders to submit their true valuations. Simulationresults
show that the proposed heuristic achieves a market valuation closeto
the optimal (less than 10 % deviation) and guarantees that animportant
part of this valuation is paid as revenue to the operator. Jointwork
with Jean-Louis Rougier, Luigi Iannone, Mathieu Bouet and VaniaConan,
to appear at ITC28 [21]https://itc28.org/

Dynamic Cache Partitioning for Encrypted Content Delivery
2016-09-07 14:00 - 14:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
In-network caching is an appealing solution to cope withthe
increasing bandwidth demand of video, audio and data transfer overthe
Internet. Nonetheless, an increasing share of content deliveryservices
adopt encryption through HTTPS, which is not compatiblewith
traditional ISP-managed approaches like transparent and proxycaching.
This raises the need for solutions involving both InternetService
Providers (ISP) and Content Providers (CP): by design, thesolution
should preserve business-critical CP information (e.g.,content
popularity, user preferences) on the one hand, while allowingfor a
deeper integration of caches in the ISP architecture (e.g., in5G
femto-cells) on the other hand. In this paper we address this issueby
considering a content-oblivious ISP-operated cache. The ISPallocates
the cache storage to various content providers so as to maximizethe
bandwidth savings provided by the cache: the main novelty lies inthe
fact that, to protect business-critical information, ISPs only needto
measure the aggregated miss rates of the individual CPs. We proposea
cache allocation algorithm based on a perturbed stochasticsubgradient
method, and prove that the algorithm converges to theallocation that
maximizes the overall cache hit rate. We use extensivesimulations to
validate the algorithm and to assess its convergence rateunder
stationary and non-stationary content popularities. Our results(i)
testify the feasibility of content-oblivious caches and (ii) showthat
the proposed algorithm can achieve within 15% from the globaloptimum
in our evaluation. Joint work with Gyorgy Dan and Dario Rossi,to
appear at ITC28 [17]https://itc28.org/

Data-Driven Design and Simulation of Future Mobile Networks (withapplications in Vehicular Networks, Transportation, Mobile Health)
2016-07-13 15:00 - 16:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
The future of social networking is in the mobile world. Futurenetwork services are expected to center around human activity and behavior.Wireless networks (including ad hoc, sensor networks and DTNs) areexpected to grow significantly and accommodate higher levels of mobilityand interaction. In such a highly dynamic environment, networks need toadapt efficiently (performance-wise) and gracefully (correctness andfunctionality-wise) to growth and dynamics in many dimensions, includingbehavioral and mobility patterns, on-line activity and load. Understandingand realistically modeling this multi-dimensional space is essential to thedesign and evaluation of efficient protocols and services of the futureInternet. This level of understanding to drive the modeling and protocoldesign shall be developed using data-driven paradigm. The design philosophyfor the proposed paradigm is unique in that it begins by intensive analysisof measurements from the target contexts, which then drive the modeling,protocol and service design through a systematic framework, called TRACE.Components of TRACE include: 1. Tracing and monitoring of behavior, 2.Representing and Analyzing the data, 3. Characterizing behavioral profilesusing data mining and clustering techniques, and finally 4. Employing theunderstanding and insight attained into developing realistic models ofmobile user behavior, and designing efficient protocols and services forfuture mobile societies.Tracing at a large scale represents the nextfrontier for sensor networks (sensing the human society). Our latestprogress in that field (MobiLib) shall be presented, along with datamining and machine learning tools to meaningfully analyze the data. Severalchallenges will be presented and novel use of clustering algorithms will beprovided. Major contributions to modeling of human mobility; the timevariant community model, TVC and Community Mobility (COBRA) will also bediscussed. In addition, a novel framework for measuring vehicular mobilityat planet scale, using thousands of webcams around the world, shall bepresented.Insights developed through analysis, mining and modeling will beutilized to introduce and design a novel communication paradigm, calledprofile-cast, to support new classes of service for interest-aware routingand dissemination of information, queries and resource discovery, trustand participatory sensing (crowd sourcing) in future mobile networks.Unlike conventional - unicast, multicast or directory based - paradigms,the proposed paradigm infers user interest using implicit behavioralprofiling via self-monitoring and mining techniques. In order to captureinterest, a spatio-temporal representation is introduced to capture usersbehavioral-space. Users can identify similarity of interest based on theirposition in such space. The proposed profile-cast paradigm will act asenabler to new classes of service, ranging from mobile social networking,and navigation of mobile societies and spaces, to computational healthcare, mhealth (mobile health), emergency management and education, amongothers. The ideas of similarity-based support groups will be specificallyhighlighted for potential applications in disease-self management,collaborative education, and emergency response.

Biography:

Dr.Ahmed Helmy is a Professor and Graduate Director at the Computer andInformation Science and Engineering (CISE) Department at the University ofFlorida (UF). He received his Ph.D. in Computer Science 1999 from theUniversity of Southern California (USC), M.Sc. in Electrical Engineering(EE) 1995 from USC, M.Sc. in Engineering Mathematics in 1994 and B.Sc. inElectronics and Communications Engineering 1992 from Cairo University,Egypt. He was a key researcher in the Network Simulator NS-2 andProtocol-Independent Multicast (PIM) projects at USC/ISI from 1995 to 1999.Before joining UF in 2006, he was on the Electrical Engineering-SystemsDepartment faculty at USC starting Fall 1999, where he founded anddirected the Wireless and Sensor Networks Labs. In 2002, he received theNSF CAREER Award for his research on resource discovery and mobilitymodeling in large-scale wireless networks (MARS). In 2000 he received theZumberge Award, and in 2002 he received the best paper award from theIEEE/IFIP MMNS Conference. In 2003 he was the Electrical Engineeringnominee for the USC Engineering Jr. Faculty Research Award, and a nomineefor the Sloan Fellowship. In 2004 and 2005 he got the best faculty meritranking at the Electrical Engineering department at USC. He was a winner inthe ACM MobiCom 2007, a finalist in 2008 SRC competitions, a 2nd placewinner in ACM MobiCom WiNTECH demo competition 2010, and afinalist/runner-up in the 2012 ACM MobiCom SRC competition. In '13 he wonthe best paper award from ACM SIGSPATIAL IWCTS. In 2014 he won the EpilepsyFoundation award for innovation, and the ACM MobiCom Mobile AppCompetition (1st place) and startup pitch competition (2nd place). In 2015he won the Internet Technical Committee (ITC) best paper award by for sevenIEEE ComSoc conferences/symposia of 2013. He is leading (or has led)several NSF funded projects including MARS, STRESS, ACQUIRE, AWARE andMobiBench. His research interests include design, analysis and measurementof wireless ad hoc, sensor and mobile social networks, mobilitymodeling, multicast protocols, IP mobility and network simulation. He haspublished over 150 journal articles, conference papers and posters, bookchapters, IETF RFCs and Internet drafts. His research is (or has been)supported by grants from NSF, KACST, Aalto University, USC, Intel,Cisco, DARPA, NASA, Nortel, HP, Pratt & Whitney, Siemens andSGI. He has over 12,200 citations with H-index=48 (Google Scholar). Dr.Helmy is an editor of the IEEE Transactions on Mobile Computing (TMC), anarea editor of the Ad hoc Networks Journal - ElSevier (since 2004), and anarea editor of the IEEE Computer (since 2010). He was the finance chair ofACM MobiCom '13, co-chair ofÃ‚Â ACM MobiSys HotPlanetÃ‚Â '12,program co-chair for ACM MSWiM 2011, and ACM MobiCom CHANTS workshop2011, co-chair of AdhocNets 2011, honorary program chair of IEEE/ACMIWCMC 2011, general chair of IWCMC 2010, vice-chair of IEEE MASS 2010,plenary panel chair of IEEE Globecom 2010, co-chair of IEEE Infocom GlobalInternet (GI) workshop 2008, and IFIP/IEEE MMNS 2006, vice-chair for IEEEICPADS 2006, IEEE HiPC 2007, and local & poster chair for IEEE ICNP2008 and 2009. He is ACM SIGMOBILE workshop coordination chair (forMobiCom, Mobihoc, Mobisys, Sensys) (since 2006). He has served onnumerous committees of IEEE and ACM conferences on networks. He is a seniormember of the IEEE and an ACM Distinguished Scientist.

The Effects of Mobility on the Hit Performance of Cached D2DNetworks
2016-07-13 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
In this talk we will deal with problems arising indevice-to-device (D2D) wireless networks, where user devices also have theability to cache content. In such networks, users are mobile andcommunication links can be spontaneously activated and dropped depending onthe users' relative position. Receivers request files from transmitters,these files having a certain popularity and file-size distribution. In ourwork a new performance metric is introduced, namely the Service SuccessProbability, which captures the specificities of D2D networks. For thePoisson Point Process case for node distribution and the $mathrmSNR$coverage model, explicit expressions are derived. Simulations support theanalytical results and explain the influence of mobility and file-sizedistribution on the system performance, while providing intuition on howto appropriately cache content on mobile storage space. Of particularinterest is the investigation on how different file-size distributions(Exponential, Uniform, or Heavy-Tailed) influence the performance.

Mining usage patterns in residential intranet of things
2016-07-06 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Ubiquitous smart technologies gradually transform modern homesinto Intranet of Things, where a multitude of connected devices allow fornovel home automation services (e.g., energy or bandwidth savings,comfort enhancement, etc.). Optimizing and enriching the Quality ofExperience (QoE) of residential users emerges as a critical differentiatorfor Internet and Communication Service providers (ISPs and CSPs,respectively) and heavily relies on the analysis of various kinds of data(connectivity, performance,usage) gathered from home networks. In thispaper, we are interested in new Machine-to-Machine data analysistechniques that go beyond binary association rule mining for traditionalmarket basket analysis considered by previous works, to analyze individualdevice logs of home gateways. Based on multidimensional patterns miningframework, we extract complex device co-usage patterns of 201 residentialbroadband users of an ISP, subscribed to a triple-play service. Suchfine-grained device usage patternsprovide valuable insights for emerginguse cases such as an adaptive usage of home devices, and also ``things''recommendation.

A Minimax Optimal Algorithm for Crowdsourcing
2016-06-29 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We consider the problem of accurately estimating thereliability of workers based on noisy labels they provide, which is afundamental question in crowdsourcing. We propose a novel lower bound onthe minimax estimation error which applies to any estimation procedure. Wefurther propose Triangular Estimation (TE), an algorithm for estimatingthe reliability of workers. TE has low complexity, may be implemented in astreaming setting when labels are provided by workers in real time, anddoes not rely on an iterative procedure. We further prove that TE isminimax optimal and matches our lower bound. We conclude by assessing theperformance of TE and other state-of-the-art algorithms on both syntheticand real-world data sets.Joint work with Thomas Bonald (Telecom ParisTech)

Finding Very Damaging Needles in Very Large Haystacks
2016-05-18 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
Many of the most costly security compromisesthat enterprises suffer manifest as tiny trickles of behavior hidden withinan ocean of other site activity. This talk exams design patterns applicableto developing robust detectors for particular forms of such activity. Thethemes include research pitfalls, the crucial need to leverage domainknowledge in an apt fashion, and why machine learning is very difficult toeffectively apply for such detection.

Biography:
Vern Paxson is aProfessor of Electrical Engineering and Computer Sciences at UC Berkeley.He also leads the Networking and Security Group at the InternationalComputer Science Institute in Berkeley, and has an appointment as a StaffScientist at the Lawrence Berkeley National Laboratory. His researchfocuses heavily on measurement-based analysis of network activity andInternet attacks. He works extensively on high performance networkmonitoring, detection algorithms, cybercrime, and counteringcensorship.In 2006 he was inducted as a Fellow of the Association forComputing Machinery (ACM). In 2011 he received ACM's SIGCOMM Award, whichrecognizes lifetime contribution to the field of communication networks,"for his seminal contributions to the fields of Internet measurement andInternet security, and for distinguished leadership and service to theInternet community." His measurement work has also been recognized by ACM'sGrace Murray Hopper Award and by the 2015 IEEE Internet Award. In 2013 heco-founded Broala, a startup that provides commercial-grade support andproducts for the "Bro" network monitoring system that he created and hasadvanced through his research for many years.

Networks of multi-server queues with parallel processing
2016-05-11 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We consider a network of multi-server queues wherein eachjob can be processed in parallel by any subset of servers within apre-defined set that depends on its class. Each server is allocated in FCFSorder at each queue. Jobs arrive according to Poisson processes, haveindependent exponential service requirements and are routed independentlyat random. We prove that the network state has a product-form stationarydistribution, in the open, closed and mixed cases. From a practicalperspective, we propose an algorithm on this basis to allocate theresources of a computer cluster.

Where are the anycasters
2016-04-20 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Use of anycast IP addresses has increased in the last fewyears: once relegated to DNS root and top-level domain servers, anycast isnow commonly used to assist distribution of general purpose content by CDNproviders. Yet, most anycast discovery methodologies rely so far on DNS,which limits their usefulness to this particular service. This raises theneed for protocol agnostic methodologies, that should additionally be aslightweight as possible in order to scale up anycast service discovery.Ouranycast discovery method allows for exhaustive and accurate enumeration andcity-level geolocation of anycast replicas, with the constraints of onlyleverages a handful of latency measurements from a set of known probes. Themethod exploits an iterative workflow to enumerate (optimization problem)and geolocate (classification problem) anycast instances. The method is solightweight and protocol agnostic that we were able to perform severalcensuses of the whole IPv4 Internet, recollecting all anycast deployments.Finally, we carry on a passive study of anycast traffic to refine thepicture of services currently served over IP anycast. All our code,dataset and further information are availableathttp://www.enst.fr/~drossi/anycast

Data Cleaning in the Big Data era @ Barrault (Amphi Rubis)
2016-04-18 15:00 - 16:00
Abstract:
In the Ã¢â‚¬Å“big dataÃ¢â‚¬Âera, data is often dirty in nature because of several reasons, such astypos, missing values, and duplicates. The intrinsic problem with dirtydata is that it can lead to poor results in analytic tasks. Therefore,data cleaning is an unavoidable task in data preparation to have reliabledata for final applications, such as querying and mining. Unfortunately,data cleaning is hard in practice and it requires a great amount of manualwork. Several systems have been proposed to increase automation andscalability in the process. They rely on a formal, declarative approachbased on first order logic: users provide high-level specifications oftheir tasks, and the systems compute optimal solutions without humanintervention on the generated code. However, traditionalÃ¢â‚¬Ëœtop-downÃ¢â‚¬â„¢ cleaning approaches quicklybecome unpractical when dealing with the complexity and variety found inbig data.In this talk, we first describe recent results in tackling datacleaning with a declarative approach. We then discuss how this experiencehas pushed several groups to propose new systems that recognize the centralrole of the users in cleaning big data.

Biography:
Paolo Papotti isan Assistant Professor of Computer Science in the School of Computing,Informatics, and Decision Systems Engineering (CIDSE) at Arizona StateUniversity. He got his Ph.D. in Computer Science atUniversitaÃ¢â‚¬â„¢ degli Studi Roma Tre (2007, Italy) and beforejoining ASU he had been a senior scientist at Qatar Computing ResearchInstitute. His research is focused on systems that assist users incomplex, necessary tasks and that scale to large datasets with efficientalgorithms and distributed platforms. His work has been recognized with twoÃ¢â‚¬Å“Best of the ConferenceÃ¢â‚¬Â citations (SIGMOD2009, VLDB 2015) and with a best demo award at SIGMOD 2015. He is groupleader for SIGMOD 2016 and associate editor for the ACM Journal of Data andInformation Quality (JDIQ).

Webstrates : Shareable Dynamic Media
2016-04-18 12:00 - 13:00
I present our ACM UIST'15 Best Paper Award-winning research onWebstrates: Shareable Dynamic Media. In this work, we revisit Alan Kay'searly vision of dynamic media, which blur the distinction between documentand application. We introduce shareable dynamic media, which are malleableby users, who may appropriate them in idiosyncratic ways; shareable amongusers, who can collaborate on multiple aspects of the media; anddistributable across diverse devices and platforms. We present Webstrates,an environment for exploring shareable dynamic media. Webstrates augmentweb technology with real-time sharing. They turn web pages intosubstrates, i.e. software entities that act as applications or documentsdepending upon use. We illustrate Webstrates with two implemented casestudies: users collaboratively author an article with functionally andvisually different editors that they can personalize and extend atrun-time; and they orchestrate its presentation and audience participationwith multiple devices.

This talk will take place at Telecom Paristechrue Barrault,(Room TBD)

A Study of the Impact of DNS Resolvers on CDN Performance Using aCausal Approach
2016-04-13 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Resources such as Web pages or videos that are published in theInternet are referred to by their Uniform Resource Locator (URL). If a useraccesses a resource via its URL, the host name part of the URL needs to betranslated into a routable IP address. This translation is performed by theDomain Name System service (DNS). DNS also plays an important role whenContent Distribution Networks (CDNs) are used to host replicas of popularobjects on multiple servers that are located in geographically differentareasA CDN makes use of the DNS service to infer client location and directthe client request to optimal server. While most Internet Service Providers(ISPs) offer a DNS service to their customers, clients may instead use apublic DNS service. The choice of the DNS service can impact theperformance of clients when retrieving a resource from a given CDN. In thispaper we study the impact on download performance for clients using eitherthe DNS service of their ISP or the public DNS service provided by GoogleDNS. We adopt a causal approach that exposes the structural dependencies ofthe different parameters impacted by the DNS service used and we show howto model these dependencies with a Bayesian network. The Bayesian networkallows us to explain and quantify the performance benefits seen by clientswhen using the DNS service of their ISP. We also discuss how the furtherimprove client performance. Joint work with Hadrien Hours, PatrickLoiseau, Alessandro Finamore and Marco Mellia

Passive Wi-Fi link Capacity Estimation on Commodity Access Points
2016-03-30 14:00 - 14:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Wi-Fi is the preferred way of accessing the internet for manydevices at home, but it is vulnerable to performance problems due tosharing an unlicensed medium. In this work, we propose a method toestimate the link capacity of a Wi-Fi link, using physical layer metricsthat can be passively sampled on commodity access points. We build a modelthat predicts the maximum UDP throughput a device can sustain, extendingprevious models that do not consider IEEE 802.1n optimizations such asframe aggregation. We validate our method through controlled experiments inan anechoic chamber and artificially create different link qualityconditions. We estimate the link capacity using our method and compare itto the state of the art. Over 95% of the link capacity predictions presenterrors below 5% when using our method with reference data. We show how thelink capacity estimation enables Wi-Fi diagnosis in two case studies wherewe predict the available bandwidth under microwave interference and in anoffice environment.

Dynamic Resource Allocation for C-RAN systems
2016-03-30 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
Cloud-Radio Access Network (C-RAN) is a newemerging technology that holds alluring promises for Mobile networkoperators regarding capital and operation cost savings. However, manychallenges still remain before full commercial deployment of C-RANsolutions. Dynamic resource allocation algorithms are needed to cope withsignificantly fluctuating traffic loads. Those algorithms must target notonly a better quality of service delivery for users, but also less powerconsumption and better interference management, with the possibility toturn off RRHs that are not transmitting. To this end, we propose a dynamictwo-stage design for downlink OFDMA resource allocation and BBU-RRHassignment in C-RAN. Simulation results show that our proposal achieves notonly a high satisfaction rate for mobile users, but also minimal powerconsumption and significant BBUs savings, compared to state-of-the-artschemes.

Biography:
Yazid LÃ¢â‚¬â€¹yazidi received hisDiploma in Computer Science and Telecommunications Engineering from INPT,Rabat, Morocco, in 2014 and the M.S. degree in Advanced Wireless Systemsfrom Ãƒâ€°cole supÃƒÂ©rieure d'ÃƒÂ©lectricitÃƒÂ©SUPELEC, Gif sur Yvette, France the same year. He is now a PhD candidatein LIP6, University Pierre and Marie Curie, Paris, under the advisory ofProf. Rami Langar and Dr. Nadjib AITSAADI. His research topics includeenergy minimization and resource management in Cloud RAN.

Power Control for Non-Orthogonal Multiple Access in 5G CellularSystems
2016-03-25 11:00 - 12:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
Non-orthogonal multiple access (NOMA) is apromising candidate for wireless access in 5G cellular systems, and hasrecently received considerable attentions from both academia and industry.In a NOMA system, multiple users share the same carrier frequency at thesame time, and their messages are decoded via successive interferencecancellation (SIC). While the idea of SIC was proposed a long time ago, itis now regarded as a practical solution to wireless networks. For SIC towork properly, the signal-to-interference ratio of each user needs to behigh enough for successful decoding and subsequent cancellation. To meetsuch a requirement, transmitter power control becomes indispensable. Thistalk focuses on power control for inter-cell interference management inNOMA systems. The classical power control results based on Perron-Frobeniustheory of non-negative matrices will be reviewed, and how they can beapplied to multi-cell NOMA systems will be presented. For practicalapplication to 5G systems, it is desirable to have distributed algorithmsfor power control, which will also be discussed.

Biography:
Dr. ChiWan Sung is an Associate Professor in the Department of ElectronicEngineering at City University of Hong Kong. He received the BEng, MPhil,and PhD degrees in information engineering from the Chinese University ofHong Kong in 1993, 1995, and 1998, respectively. He has served as editorfor the ETRI journal and for the Transactions on EmergingTelecommunications Technologies. His research interests include powercontrol and resource allocation, cooperative communications, networkcoding, and distributed storage systems.

iBGP2: a scalable iBGP redistribution mechanism leading to optimalrouting
2016-03-23 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
The Internet is made of almost 50,000 ASes exchanging routinginformationthanks to BGP. Inside each AS, information is redistributed viaiBGP sessions.This allows each router to map a destination exterior to theAS with a givenegress point. The main redistribution mechanisms usedtoday, (iBGP full mesh, RouteReflectors and BGP confederations), eitherguarantee selection of the bestegress point or enhance scalability, butnot both. In this paper, we propose a new wayto perform iBGPredistribution in an AS based on its IGP topology, conciliatingoptimalityin route selection and scalability. Our contribution is threefold.First,we demonstrate the tractability of our approach and its benefits.Second,we provide an open-source implementation of our mechanism based onQuagga.Third, we illustrate the feasibility of our approach throughsimulationsperformed under ns-3 and compare its performance with full meshand RouteReflection. Joint work with Anthony Lambert (Orange Labs) Steve Uhlig(Queen Mary University of London), to appear at IEEE INFOCOM 2016,

Bandwidth calendaring: a new SDN service
2016-03-09 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
Software Defined Networking paves the way fornew services that enable better utilization of network resources. BandwidthCalendaring (BWC) is a typical such example that exploits knowledge aboutfuture traffic, to optimally pack the arising demands over the network. Weconsider a generic BWC instance, where a network operator has toaccommodate at minimum cost demands of predetermined, but time-varying,bandwidth requirements that can be scheduled within a specific time window.By exploiting the structure of the problem, we propose low complexitymethods for the decomposition of the original Mixed integer problem intosimpler ones. Our numerical results reveal that the proposed solutionapproach is near-optimal and outperforms standard methods based on linearprogramming relaxations and randomized rounding by more than20%.

Biography:
Lazaros Gkatzikis(SÃ¢â‚¬â„¢09Ã¢â‚¬â€œMÃ¢â‚¬â„¢13) obtained thePh.D. degree in computer engineering and communications from the Universityof Thessaly, Volos, Greece. Currently, he is a Research Staff Member atHuawei France Research Center, Paris, France. In the fall of 2011, hewas a Research Intern at the Technicolor Paris Research Laboratory. He hasbeen a Postdoctoral Researcher in the team of Prof. L. Tassiulas in Volos,Greece (2013) and at the KTH Royal Institute of Technology, Stockholm,Sweden (2014) working with Associate Prof. C. Fischione. His researchinterests include network optimization, mechanism design, and networkperformance analysis.

An Opportunistic Blanking SubFrame (OBS) solution for 5G networks
2016-03-02 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
Telco operators view network densification asa viable solution for the challenging goals set for the next generationcellular networks. Among other goals, network densification would helpaccomodating the always increasing mobile demand or would allow toconsiderably reduce connection latency. Nevertheless, along with networkdensification, many issues arise. For example, sever inter-cellinterference (ICI) may considerably limit network capacity if coordinationamong base stations is not used. To tackle such a problem, we focus on thewell-known Almost Blank Sub-Frame (ABS or ABSF) solution. With ABSF, inorder to reduce interference, not all the base stations are allowed totransmit at the same time. In this talk, we question the ability of ABSFof improving both aggregate system throughput and transmission efficiencyand we show how ABSF may purse some other different objectives. Incontrast, we show that a better way of improving system throughput isenabling Device-to-Device communications among UEs and opportunisticforwarding. Therefore, we propose a novel mechanism (OBS) that exploitsand coordinates simultaneously ABSF and opportunistic forwarding to improvesystem throughput and user fairness. Our approach has been validatedagainst state of the art approaches through an extensive simulationcampaign, even using real data from a network operator.

On the Whittle Index for Restless Multi-armed Hidden Markov Bandits
2016-02-26 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
We consider a restless multi-armed bandit inwhich each armcan be in one two states. When an arm is sampled, the stateof the armis not available to the sampler. Instead, a binary signal with aknownrandomness that depends on the state of the arm is made available.Nosignal is displayed if the arm is not sampled. An arm-dependent rewardisaccrued from each sampling. In each time step, each arm changesstateaccording to known transition probabilities which in turn dependonwhether the arm is sampled or not sampled. Since the state of the armisnever visible and has to be inferred from the current belief andapossible binary signal, we call this the hidden Markov bandit.Ourinterest is in a policy to select the arm(s) in each time stepthatmaximises the infinite horizon discounted reward. Specifically, weseekthe use of WhittleÃ¢â‚¬â„¢s index in selecting the arms.Wefirst analyze the single-armed bandit and show that it admits anapproximatethreshold-type optimal policy when theÃ¢â‚¬Ëœno-sampleÃ¢â‚¬â„¢ actionis subsidised. Next, weshow that this also satisfies an approximate-indexability property.Numerical examples support the analytical results

Lattice network codes based on Barnes-Wall lattices
2016-02-24 15:00 - 16:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
Lattice network coding is employed inphysical-layer network coding, with applications to two-way relay networksand multiple-access channels. The receiver wants to compute a linearcombination of the source symbols, which are drawn from a finite alphabetequipped with some algebraic structure. In this talk, we construct latticenetwork codes from lattices such as the E8 lattice and the Barnes-Walllattice, which have the best known packing density and shaping gain indimension 8 and 16, respectively. Simulation results demonstrate thatthere is a significant performance gain in comparison to the baselinelattice network code with hyper-cube shaping.

Biography:
Kenneth Shumreceived the B.Eng. degree in Information Engineering from the ChineseUniversity of Hong Kong in 1993, and the M.S. and Ph.D. degree inElectrical Engineering from University of Southern California in 1995 and2000 respectively. He is now a research fellow in the Institute of NetworkCoding, CUHK. His research interests include information theory, codingtheory and cooperative communication in wireless network. He is also amember of Composers and Authors Socity of Hong Kong (CASH) and has Erdosnumber 2.

Logic-Based Integrative Causal Discovery with Business Applications
2016-02-24 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Computational Causal Discovery aims to inducecausal models,causal networks, and causal relations from observationaldata withoutperforming or by performing only few interventions(perbutations,manipulations) of a system. While predictive analyticscreate models thatpredict customer behavior for example, causal analyticscreate models thatdictate how to affect customer behavior. A recentapproach to causaldiscovery, which we call logic-based integrative causaldiscovery, will bepresented. This approach is more robust to statisticalerrors, makes morerealistic and less restrictive assumptions (e.g.,admits latent confoundingfactors and selection bias in the data) andaccepts and reasons withmultiple heterogeneous datasets that are obtainedunder different samplingcriteria, different experimental conditions(perbubations, interventions),and measuring different quantities(variables). The approach significantlyextends causal discovery based onBayesian Networks, the simplest causalmodel available, and is much moresuitable for real business or scientificdataanalysis.

Prof. Ioannis Tsamardinos is AssociateProfessor at the ComputerScience Department of University of Crete andco-founder of Gnosis DataAnalysis IKE. Prof. Tsamardinos has over 70publications in internationaljournals, conferences, and books. He hasparticipated in several national,EU, and US funded research projects.Distinctions with colleagues andstudents include the best performance inone of the four tasks in therecent First Causality Challenge Competition,ISMB 2005 Best Poster Winner,a Gold Medal in the Student Paper Competitionin MEDINFO 2004, theOutstanding Student Paper Award in AIPS 2000, theNASA Group AchievementAward for participation in the Remote Agent team andothers. He is aregular reviewer for some of the leading Machine Learningjournals andconferences. Statistics on recognition of work include morethan 4500citations, and h-index of 28 (as estimated by the Publish orPerish tool).Prof. Tsamardinos has recently been awarded the European andGreek nationalgrants of excellence, the ERC Consolidator and the ARISTEIAII grantsrespectively (the equivalent of the NSF Young Investigator Award).Prof.Tsamardinos has pioneered the integrative causal analysis andthelogic-based approach to causal discovery. The ERC grant inparticularregards the development of novel integrative causal discoverymethods andtheir application to biological mass cytometrydata.

That's the end of the Web as we know it
2016-02-10 14:00 - 16:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
HTTP is one crucial element of nowadays Internet, almost tothe point of being nowadays that ``thin waits'' that used to be identifiedwith the IP protocol not so long ago. Yet HTTP is changing, with recentproposals such as SPDY, HTTP2 and QUIC, that aims at addressing some ofthe long-standing shortcoming of the HTTP/1 protocol family. In this talk,we will be exposing ongoing work to assess the impact that HTTP evolutionis expected to have on the quality of user experience (QoE), based onexperiments where we collect feedback (i.e., Mean Opinion Scores) from apanel of users on real webpages, as well as define and automaticallycollect QoE metrics on the same experiments.

Centralized Content Delivery Infrastructure Exploiting ResourcePools: Performance Models and Asymptotics
2016-02-03 14:00 - 16:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We consider a centralized content delivery infrastructure wherea large number of storage-intensive files are replicated across severalcollocated servers. To achieve scalable delays in file downloads understochastic loads, we allow multiple servers to work together as a pooledresource to meet individual download requests. In such systems importantquestions include: How and where to replicate files; How significant arethe gains of resource pooling over policies which use single server perrequest; What are the tradeoffs among conflicting metrics such as delays,reliability and recovery costs, and power; How robust is performance toheterogeneity and choice of fairness criterion; etc.In this talk weprovide a simple performance model for large systems towards addressingthese basic questions. For large systems where the overall system load isproportional to the number of servers, we establish scaling laws amongdelays, system load, number of file replicas, demand heterogeneity,power, and network capacity.

Model-Graft: Accurate, Scalable and Flexible Analysis of CacheNetworks
2016-01-27 14:00 - 16:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Large scale deployments of general cache networks, such asContent Delivery Networks or Information Centric Networking architectures,arise new challenges regarding their performance prediction and networkplanning. Analytical models and MonteCarlo approaches are already availableto the scientific community. However, complex interactions betweenreplacement, replication, and routing on arbitrary topologies make theseapproaches hardly configurable. Additionally, huge content catalogs andlarge networks sizes add non trivial scalability problems, making theirsolution computationally demanding. We propose a new technique for theperformance evaluation of large scale caching systems that intelligentlyintegrates elements of stochastic analysis within a MonteCarlo approach.Our method leverages the intuition that the behavior of realistic networksof caches, being them LRU or even more complex caches, can be wellrepresented by means of much simpler Time-To-Live (TTL)- based caches. ThisTTL can be either set with the guidance of a simple yet accurate stochasticmodel (e.g., the characteristic time of the Che approximation), or can beprovided as very rough guesses, that are iteratively corrected by afeedback loop to ensure convergence. Through a thorough validationcampaign, we show that the synergy between modeling and MonteCarloapproaches has noticeable potentials both in accurately predicting steadystate performance metrics within 2% accuracy, while significantly scalingdown simulation time and memory requirements of large scale scenarios by totwo orders of magnitude. Furthermore, we demonstrate the flexibility andefficiency of our hybrid approach in simplifying fine-grained analyses ofdynamic scenarios.

Virtualization techniques in the design of 5G networks
2016-01-20 14:00 - 16:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We describe in this talk the new possibilities offered byvirtualization techniques in the design of 5G networks. We preciselyintroduce a convergent gateway realizing fixed/mobile convergence. Such afunctional element is based on modules instantiated on virtual machines (ordockers), each module implementing specific tasks for convergence. Aconvergent gateway can be instantiated by a network operating system(GlobalOS) in charge of managing the network. One important component ofGlobalOS is the orchestration of resources. We introduce some algorithmsfor resource orchestration in the framework of GlobalOS. We finally focuson the specific case of virtualized base band unit (BBU) functions.

Dynamic control of stochastic and fluid resource-sharing systems
2015-12-16 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We study the dynamic control of resource-sharing systems thatarise in various domains: e.g. inventory management, healthcare andcommunication networks. We aim at efficiently allocating the availableresources among competing projects according to a certain performancecriteria. These type of problems have a stochastic nature and may be verycomplex to solve. We therefore focus on developing well-performingheuristics. Firstly, we consider the framework of Restless BanditProblems, which is a general class of dynamic stochastic optimizationproblems. Relaxing the sample-path constraint in the optimization problemenables to define an index-based heuristic for the original constrainedmodel, the so-called Whittle index policy. We derive a closed-formexpression for the Whittle index as a function of the steady-stateprobabilities for the case in which bandits (projects) evolve in abirth-and-death fashion. This expression requires several technicalconditions to be verified, and in addition, it can only be computedexplicitly in specific cases. In the particular case of a multi-classabandonment queue, we further prove that the Whittle index policy isasymptotically optimal in the light-traffic and heavy-traffic regimes.Secondly, we derive heuristics by approximating the stochasticresource-sharing systems with deterministic fluid models. We firstformulate a fluid version of the relaxed optimization problem, and wedevelop a fluid index policy. The fluid index can always be computedexplicitly and hence overcomes the technical issues that arise whencalculating the Whittle index. We apply the Whittle index and the fluidindex policies to several systems: e.g. power-aware server-farms,opportunistic scheduling in wireless systems, and make-to-stock problemswith perishable items. We show numerically that both index policies arenearly optimal.

Finding dense subgraphs and interesting events in social networks
2015-12-02 14:00 - 14:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Algorithms for finding dense subgraphs are an importantsubroutine in many data mining tasks, in particular, community and eventdetection in social networks. Huge amount of data is produced daily byFacebook and Twitter users, calling for efficient algorithms being able tohandle large amount of data evolving over time. In this talk, we shallpresent algorithms for efficiently finding dense subgraphs in an evolvinggraph and discuss some preliminary results on how they can be used forautomatically finding interesting events in social networks.

An overview of scheduling resources in a public cloud
2015-11-25 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

CrowdSurf: Empowering Transparency in the Web
2015-11-18 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract: Individuals lack proper means to supervise theservices they contact and the information they exchange when surfing theweb. Thissecurity task has become challenging due to the complexity of themodern web, of the data delivering technology, and even to the adoptionof encryption, which, while improving privacy, makes in-network servicesineffective. The implications are serious, from a person contactingundesired services or unwillingly exposing private information, to acompany being unable to control the flow of its information to the outsideworld.To empower transparency and the capability of taking informed choicesin the web, we propose CROWDSURF, a system for comprehensive andcollaborative auditing of data exchanged with Internet services. Similarlyto crowdsourced efforts, we enable users to contribute in buildingawareness, supported by the semi-automatic analysis of data offered by acloud-based system. The result is the creation ofÃƒÂ¢suggestionsÃƒÂ¢ that individuals can transform in enforceableÃƒÂ¢rulesÃƒÂ¢ to customize their web browsing policy. CROWDSURFprovides the core infrastructure to let individuals and enterprises regainvisibility and control on their web activity. Preliminary results obtainedexecuting a prototype implementation demonstrate the feasibility andpotential of CROWDSURF.

Trimming Sparse Random Graphs: Bounds, Algorithms, andExperiments
2015-10-28 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
Viral spread on large graphs has manyreal-life applications such asmalware propagation in computer networks andrumor (or misinformation)spread in Twitter-like online social networks.Although viral spreadon large graphs has been intensively analyzed onclassical models suchas Susceptible-Infectious-Recovered, there stillexits a deficit ofeffective methods in practice to contain epidemic spreadonce itpasses a critical threshold. Concretely, we consider a randomedgeweighted graph $G$ on a fixed degree sequence, where edge weightsarei.i.d. non-negative random variables. Given a budget $B>0$,theproblem is to find a subset of edges $E' subset E(G)$ whose sum oftheedge weights is at most $B$ and the number of nodes in the largestcomponentof the remaining graph $(V(G),E(G)setminus E')$ isminimized. We provebounds on the edge budget: (i) a lower bound on$B$, necessary to break theoriginal graph $G$ into components of atmost constant size $Theta(1)$;(ii) an upper bound on $B$, sufficientsuch that for any choice of removaledges $E'$, with high probabilitythere exist a component of size linear inthe number of nodes$Theta(|V(G)|)$. Our bounds depend on the weight of themaximumspanning forest. We furthermore propose and numericallyestimateheuristic-based approaches to decompose $G$. Joint work with MikeMolloy and Guanhua Yan

Biography:
Milan Bradonjic is a researcher atBell Labs, Murray Hill, USA. Priorto that, he was as a postdoctoralresearch fellow in the AppliedMathematics and Plasma Physics Group, andCenter for NonlinearStudies, at Los Alamos National Laboratory. Heobtained his Ph.D. atthe University of California, Los Angeles and Dipl.Eng. at theUniversity of Belgrade. His research focuses on random graphtheory,and the limiting behavior and percolation of randomdiscretestructures.

Multi-Resource Fairness: Objectives, Algorithms and Performance
2015-10-22 11:00 - 12:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Presentation of their paper "Multi-Resource Fairness:Objectives, Algorithms and Performance":http://dl.acm.org/citation.cfm?doid=2745844.2745869

Modeling and Performance Evaluation of Resource Allocation Problemsin TV White Space and NFV-based Networks
2015-10-14 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
In this talk, we focus on the resource allocation problems incommunication networks. More specifically, we will first consider a TVWhite Space (TVWS) network and introduce a distributed dynamic spectrummanagement mechanism, which allows TV bands (unlicensed) devices tochoose, in a dynamic/mobile TVWS scenario, the available TV channelsmaximizing their data rates. Then, in the second part of the talk, wewill present some resource orchestration mechanisms for congestionmitigation in Network Function Virtualization (NFV)-based networks. Thecongestion mitigation issue will be investigated and modeled using mixedinteger-linear programming tools. Finally, we will conclude the talk bypresenting some open problems and the most promising research directions.

Optimal Investment in Social Signals.
2015-10-07 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
This study is an attempt to determine how muchindividuals should invest in communication in a social context. Two simplemodels of social relationships are considered, depending on the symmetryor asymmetry of links. In both models, individuals emit costly signals toadvertise their â€œqualitiesâ€ as potential friends (e.g. byposting relevant messages). The study shows that costly communication canbe a profitable strategy, and not only for the most successfulindividuals. It also reveals interesting phenomena, such as the collectivelimitation of signaling investment in the high intensity range. Thesemodels may be relevant to several aspects of social communication, ineveryday life and on virtual social networks.

Advanced Demand Response Solutions for Capacity Markets
2015-09-30 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
The Internet of Things (IoT) paradigm brings an opportunity foradvanced Demand Response (DR) solutions. Indeed, it enables visibility andcontrol on the various appliances that may consume, store or generateenergy within a home. It has been shown that a centralized control on theappliances of a setof households leads to efficient DR mechanisms;unfortunately, such solutions raise privacy and scalability issues. Inthis talk we propose an IoT-based DR approach that deals with these issues.Specifically, we propose and analyze a scalable two levels control systemwhere a centralized controller allocates power to each house on one sideand, each household implements an IoTbasedDR local solution on the otherside. A limited feedback to the centralized controller allows to enhancethe performance with little impact on privacy. The solution is proposed forthegeneral framework of capacity markets.

Big Data Integration
2015-09-23 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
The Big Data era is upon us: data isbeing generated, collected and analyzed at an unprecedented scale, anddata-driven decision making is sweeping through all aspects of society.Since the value of data explodes when it can be linked and fused with otherdata, addressing the big data integration (BDI) challenge is critical torealizing the promise of Big Data. BDI differs from traditional dataintegration in many dimensions: (i) the number of data sources, even for asingle domain, has grown to be in the tens of thousands, (ii) many of thedata sources are very dynamic, as a huge amount of newly collected dataare continuously made available, (iii) the data sources are extremelyheterogeneous in their structure, with considerable variety even forsubstantially similar entities, and (iv) the data sources are of widelydiffering qualities, with significant differences in the coverage,accuracy and timeliness of data provided. This talk explores the progressthat has been made by the data integration community in addressing thesenovel challenges faced by big data integration, and identifies a range ofopen problems for the community

Biography:
Divesh Srivastava is thehead of Database Research at AT&T Labs-Research. He is an ACM fellow,on the board of trustees of the VLDB Endowment, the managing editor of theProceedings of the VLDB Endowment (PVLDB) and an associate editor of theACM Transactions on Database Systems (TODS). His research interests andpublications span a variety of topics in data management.

Towards a Software-Defined Network Operating System for the IoT
2015-09-16 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
The heterogeneity characterizing the Internetof Things (IoT) landscape can be addressed by leveraging network operatingsystems (NOS)s. Current NOS solutions have been developed for traditionalinfrastructured networks: they do not take the specific features offundamental IoT components such as wireless sensor and actor networks intoaccount. In this talk an innovative integrated network operating system forthe IoT which is obtained as the evolution of theOpen Network OperatingSystem (ONOS) will be presented. This has been appropriately extended toenhance the recently proposed SDN-WISE platform for supporting SDN inwireless sensor networks and let it interact with standard OpenFlow (OF)switches. The proposed integrated system has been prototyped andtested.

Biography:
Giacomo Morabito was born in Messina, Sicily(Italy) on March 16, 1972. He received the laurea degree in ElectricalEngineering and the PhD inElectrical, Computer and TelecommunicationsEngineering from the Istituto di Informatica e Telecomunicazioni,University of Catania , Catania (Italy), in 1996 and 2000, respectively.From November 1999 to April 2001, he was with the Broadband and WirelessNetworking Laboratory of the Georgia Institute of Technology as a ResearchEngineer. Since April 2001 he is with the Dipartimento di IngegneriaInformatica e delle Telecomunicazioni of the University of Catania where heis currently Associate Professor. His research interests focus on analysisand solutions for wireless networks.

Least Recently Used caches under the ShotNoise Model
2015-09-09 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Talk:
Least Recently Used caches under the ShotNoiseModel

Abstract:
In this paper we develop an analytical framework,based on the Che approximationfor the analysis of Least Recently Used (LRU)caches operating under the Shot Noise requests Model (SNM).The SNM wasrecently proposed to better capture the main characteristics of today Videoon Demand (Vod) traffic.In this context, the Che approximation is derivedas the application of a mean field principle to the cache eviction time. Weinvestigate the validity of this approximation through an asymptoticanalysisof the cache eviction time. Particularly, we provide a largedeviation principle and a central limit theorem for the cache evictiontime, as the cache size grows large. Furthermore, we obtain anon-asymptotic analytical upper bound on the error entailed by Che'sapproximation of the hit probability. This work appeared at IEEEINFOCOM'15

Modeling, optimization and control in wireless networks
2015-09-07 09:00 - 18:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We are organizing a Seminar on modeling, optimization andcontrol in wireless networks, notably 5G, on September 7, 2015, inTelecom ParisTech, rue Barrault, Paris 13eme, Amphi B312. This seminaris a joint action between RT2 and ANR projects Idefix et Netlearn.

Theprogram includes plenary talks as well as Poster sessions.

Confirmedspeakers include

Marceau Coupechoux, Telecom ParisTech
Salah-EddineElayoubi, Orange Labs
Xavier Lagrange, Telecom Bretagne
OlivierMarcÃ©, Alcatel-Lucent
Loutfi Nuaymi, Telecom Bretagne
ThrasyvoulosSpyropoulos, Eurecom
We are soliciting submissions for Posters, untilSeptember 1, 2015. Poster proposals can be sent to patrick (dot) loiseau(at) eurecom (dot) fr

Attendance is free of charge but, for logisticpurposes, we kindly invite prospective attendees to write an email totijani(dot)chahed(at)telecom-sudparis(dot)eu

We look forward to seeingyou on September 7 in Paris

Learning to Rank: Regret Lower Bounds and Efficient Algorithms
2015-07-15 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Algorithms for learning to rank Web documents, display ads,or other types of items constitute a fundamental component of searchengines and more generally of online services. In such systems, when auser makes a request or visits a web page, an ordered list of items (e.g.documents or ads) is displayed; the user scans this list in order, andclicks on the first relevant item if any. When the user clicks on an item,the reward collected by the system typically decreases with the position ofthe item in the displayed list. The main challenge in the design ofsequential list selection algorithms stems from the fact that theprobabilities with which the user clicks on the various items are unknownand need to be learned. We formulate the design of such algorithms as astochastic bandit optimization problem. This problem differs from theclassical bandit framework: (1) the type of feedback received by the systemdepends on the actual relevance of the various items in the displayed list(if the user clicks on the last item, we know that none of the previousitems in the list are relevant); (2) there are inherent correlationsbetween the average relevance of the items (e.g. the user may be interestedin a specific topic only). We assume that items are categorized accordingto their topic and that users are clustered, so that users of the samecluster are interested in the same topic. We investigate several scenariosdepending on the available side-information on the user before selectingthe displayed list: (a) we first treat the case where the topic the user isinterested in is known when she places a request; (b) we then study thecase where the user cluster is known but the mapping between user clustersand topics is unknown. For both scenarios, we derive regret lower boundsand devise algorithms that approach these fundamental limits.

Being Greedy is Good : Approximating the FDMA Capacity
2015-07-08 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
We consider the classical problem ofapproximating the FDMA capacity,where the problem is to allocate disjointresources (frequencies) tomultiple users so as to maximize the sum-utility(data rate). Manyheuristic approaches, such as convex relaxation etc,.are known to solvefor the FDMA capacity, however, fail to give anytheoretical guarantees.We approach this problem via results on greedyalgorithms for sub-modularfunctions. The main result is to show that thecapacity of parallelGaussian channels is a sub-modular function. Followingthis result, we geta 2-approximation (which is at least 1/2 times equal)to the optimalFDMA capacity.

Biography:
Rahul Vaze received his Ph.D.from The University of Texas at Austin in 2009. SinceOct. 2009 he is aReader at the School of Technology and ComputerScience, Tata Institute ofFundamental Research, Mumbai, India. Hisresearch interest are in multipleantenna communication, ad hoc networks,combinatorial resource allocation.He is a co-recipient of the Eurasipbest paper award for year 2010 for theJournal of Wireless Communication and Networking, and recipient of IndianNational Science Academy's young scientist award for the year 2013 andIndian National Academy of Engineering's young engineer award for the year2013.

Approximations for stochastic graph rewriting
2015-07-07 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We present a method to compute approximate descriptions of aclass of stochastic systems. For the method to apply, the system must bepresented as a Markov chain on a state space consisting in graphs orgraph-like objects, and jumps must be described by transformations whichfollow a finite set of local rules. The method is a form of staticanalysis. The output is a system of coupled ordinary differential equations(ODE) which tracks the mean evolution of the number of (typically small)subgraphs. In some cases, these ODEs form an exact and finite descriptionof these mean numbers. But even when the ODE description is only anapproximation, it can often reveal interesting properties of the originalsystem.

Online network optimization with SDN
2015-07-01 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
Software-Defined Networking (SDN) is anemerging network architecture decoupling the network control and forwardingfunctions, and it enables the network elements to become directlyprogrammable and the underlying infrastructure to be abstracted forapplications and network services. SDN is ideal for the bandwidth hungryand dynamic nature of today's applications, since it permits through alogically centralized controller to reconfigure instantaneously thenetwork, thus exploiting the network capacity more efficiently thandistributed routing protocols. Looking at classical networking problemsthrough the angle of centralization brings very challenging and new onlinenetwork optimization problems. These problems were not considered wheneverything was done at network planning phase with no hard timeconstraints. This talk gives an introduction to this new domain andpresents a few contributions on fast connection setup and networkre-optimization.

Biography:
Dr. JÃ©rÃ©mie Leguay received his aPh.D. degree from Pierre & Marie Curie University in Paris on ad hocand delay tolerant networks. He was awarded the Thales Ph.D Prize for thiswork in 2007. From 2007 to 2009, he worked as a Research Engineer atThales Communications and extended his research activities to vehicular andwireless sensor networks. From 2009 to 2014, he was responsible for theResearch & Technology lab on networked systems at ThalesCommunications & Security where he especially developed activities onmobile wireless networks and software-defined networks. He joinedHuaweiâ€™s French research Center in November 2014 to lead the trafficand network optimization team. His current research interests are protocoldesign and network optimization for fix and mobile environments.

New MAC Protocol, Multiple Packet Reception and Smart Wireless
2015-07-01 11:00 - 12:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Massey and Mathys proposed protocol sequences as a new designapproach to media access control protocol without feedback that deliversthroughput performance that can asymptotically converge to systems withfeedback.Â Â In this talk, we present recent research results onprotocol sequences that have potential application to future wirelessnetworks.Â These protocol sequence results relate to multiple-packetreception networks, frequency hoping and successive interferencecancellation MIMO systems.

Identity based network architecture
2015-06-25 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Posting behavior in Social Networks and Content Active Filtering
2015-06-24 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
In this talk, first we describe a model ofthe posting behavior in Social Networks in topics which have negativeexternalities, and the second objective of it is to provide a contentactive filtering control such that the content diversity increase. Bynegative externalities, we mean that when the quantity of posted contentsabout some topic increases the popularity of posted contents decreases. Weintroduce a dynamical model to describe the posting behavior of userstaking into account these externalities. Our model is based on stochasticapproximations and sufficient conditions are provided to ensure itsconvergence to a unique rest point. We provide a close form of this restpoint. Content Active Filtering (CAF) are actions taken by theadministrator of the Social Network in order to promote some objectivesrelated to the quantity of contents posted in various topics. As objectiveof the CAF we shall consider maximizing the diversity of postedcontents.

Biography:
Alexandre Reiffers is a third year PHD studentat INRIA and LIA. His supervisors are Eitan Altman and Yezekael Hayel. Hiscurrent research interests include routing games, bi-level problem anddifferential games; all applied to Social Networks and InternetEconomics.

Rethinking Competitive-Ratio: Two Case Studies
2015-06-24 11:00 - 12:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
Competitive ratio is traditionally defined byasking the question: â€œHow much service can a policy deliver with afixed amount of resourceâ€. This definition requires applications toadapt to their perceived service. However, many emerging applications,such as multimedia and safety-critical applications, have strict servicerequirements. In order to accommodate these applications, we redefinecompetitive ratio by asking: â€œHow much resource does a policy need toprovide a fixed degree of service.â€ By studying two differentapplications, we demonstrate that answering the second question revealssome surprising results.

Biography:
I-Hong Hou is an assistantprofessor in the ECE Department of the Texas A&M University. Hereceived his Ph.D. from the Computer Science Department of the Universityof Illinois at Urbana-Champaign. His research interests include wirelessnetworks, wireless sensor networks, and real-time systems. He receivedthe C.W. Gear Outstanding Graduate Student Award from the University ofIllinois at Urbana-Champaign, and the Silver Prize in the Asian PacificMathematics Olympiad.

Small Cells for 5G: Fundamentals and Recent Theory
2015-06-17 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
With 4G cellular technologies now beginning tobe deployed widely around the world, the fifth generation (5G) mobile andwireless communication technologies are emerging into research fields. Newservices, applications and devices will drive requirements on data rate,ubiquity of data services, latency, cost, and reliability and furtherdrive data traffic growth. Networks, services, and devices will be moreheterogeneous and the need to connect billions of devices to the networkwill emerge. To meet the above challenges, small cell networks will becrucial to meet the requirements in terms of spectral efficiency and energyefficiency. In this talk, we will discuss some of our recent work in smallcell networks that can potentially help us to meet suchchallenges.

Biography:
Tony Q.S. Quek received the B.E. and M.E.degrees in Electrical and Electronics Engineering from Tokyo Institute ofTechnology, Tokyo, Japan, respectively. At Massachusetts Institute ofTechnology (MIT), Cambridge, MA, he earned the Ph.D. in ElectricalEngineering and Computer Science. Currently, he is an Assistant Professorwith the Singapore University of Technology and Design (SUTD). He is also aScientist with the Institute for Infocomm Research. His current researchtopics include sensor networks, heterogeneous networks, smart grid,green communications, wireless security, big data processing, compressedsensing, IoT, and cognitive radio.Dr. Quek has been actively involved inorganizing and chairing sessions, and has served as a TPC member in anumerous international conferences. He served as the Co-Chair of theCommunication Theory Symposium for IEEE ICC in 2015, the PHY &Fundamentals Track for IEEE WCNC in 2015, the PHY & FundamentalsTrack for IEEE EuCNC in 2015, the Communications Track for IEEE ATC in2015, and the Communication and Control Theory Symposium for IEEE ICCC in2015. He is currently an Executive Editorial Committee Member for the IEEETransactions on Wireless Communications, an Editor for the IEEETransactions on Communications and the IEEE Wireless CommunicationsLetters. He was Guest Editor for the IEEE Signal Processing Magazine(Special Issue on Signal Processing for the 5G Revolution) in November 2014and the IEEE Wireless Communications Magazine (Special Issue onHeterogeneous Cloud Radio Access Networks) in June 2015.Dr. Quek receivedthe 2008 Philip Yeo Prize for Outstanding Achievement in Research, theIEEE Globecom 2010 Best Paper Award, the 2011 CAS Fellowship for YoungInternational Scientists, the 2012 IEEE William R. Bennett Prize, theIEEE SPAWC 2013 Best Student Paper Award, and the IEEE WCSP 2014 BestPaper Award.

The Capacity of Wireless Networks for Emerging Applications
2015-06-17 11:00 - 12:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
Future wireless traffic is going to bedominated by emerging applications such as VoIP, video conferencing,video/audio streaming, etc. These applications have their unique trafficpatterns, performance metrics, and service requirements. Traditionalnetwork performance metrics, such as throughput, delay, and delayjitter, can no longer provide a precise characterization for theseemerging applications. In this talk, we discuss two different kinds ofemerging applications. We introduce an analytical framework to model theseapplications and practical characteristics of wireless channels. We derivethe capacity regions of wireless networks for serving these applications,and develop tractable scheduling policies for achieving the capacityregions.

Biography:
I-Hong Hou is an assistant professor in the ECEDepartment of the Texas A&M University. He received his Ph.D. from theComputer Science Department of the University of Illinois atUrbana-Champaign. His research interests include wireless networks,wireless sensor networks, and real-time systems. He received the C.W. GearOutstanding Graduate Student Award from the University of Illinois atUrbana-Champaign, and the Silver Prize in the Asian Pacific MathematicsOlympiad.

A novel spectral algorithm for the identification of overlappingcommunities
2015-06-10 14:00 - 14:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Spectral algorithms are popular methods for finding a partitionof a network into groups of nodes that are densely connected, calledcommunities. However, the structure of many real world networks is betterexplained by a set of overlapping communities than by a partition. In thistalk, I will present combinatorial spectral clustering (CSC), a simplespectral algorithm designed to identify overlapping communities. Thealgorithm is motivated by a random graph model called stochastic blockmodelwith overlap (SBMO), under which it is proved to be consistent. Joint workwith Thomas Bonald and Marc Lelarge.

Timelines Analysis and competition over popularity, influence andvisibility in social networks.
2015-06-03 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
The major social networks use timelines to display content thata user receives from those sources that he follows. A content that arrivesat a timeline is placed at the top of the list and each other content ispushed down by one step. If the timeline is finite (as in twitter) thenthis causes the last element in the timeline to be pushed out. Moreover,the lower the content is on the timeline the smaller its influence is. Inthis talk we shall first present analysis of the timeline process and ofthe probability to be visible on the timeline. We shall further describethe influence process of content which takes into account not only thelocation on the timeline but also aging of content. We shall then study theimpact of the burstiness of the arrival of contents on the timelineprocess. We shall finally introduce game theoretical models to describe thecompetition over popularity and over visibility of content in the timeline.We shall study two specific game theoretic problems. The first is a timinggame: when is it best to send a content. The second is a resourceallocation game for optimal control of the flow of content.The workdescribes ongoing collaborative work with many woauthors: AlexandreReiffers, Nahum Shimkin, Anurag Kumar, Yezekael Hayel and others.

Compressive Sensing, Opportunistic Network Coding and RepetitionMAC for Connected Cars
2015-06-03 10:00 - 11:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
Recently we are witnessing the emergence ofsituation-aware vehicles, equipped with plurality of sensors that can helpdriver with vehicle control and maneuvering. Cars that can parkthemselves, provide lane-departure warning, and monitor the driveralertness are marketed with affordable prices. The sensing and processingpower of cars are increasing, enabling various safety-enhancing features,such as blind-spot warning, adaptive headlights, adaptive cruisecontrol, and so on. In this talk, we will discuss the next steps forautonomous vehicles. In particular, we will project the path forward bytransitioning from autonomous cars to cognitive and intelligent vehicles.Future cars will be enabled with car-to-car and car-to-infrastructurecommunication capabilities. We will review such enhancement and will focuson two recent research directives that will make future cars intelligent.The two enablers are compressive sensing and network coding. We will showthat cooperative compressive sensing can reduce the wireless channelcongestion, which is the main challenge in dense vehicular networks. Todiscuss the communications aspects of vehicular networks, we willintroduce a repetition-based medium access control method using positiveorthogonal codes, and then propose an opportunistic network-coding schemeto enhance the reliability of communication. We will finally discuss someopen research issues.

Biography:
Shahrokh Valaee is with the EdwardS. Rogers Sr. Department of Electrical and Computer Engineering,University of Toronto, where he is a Professor and the Associate Chair forUndergraduate Studies. He is the Founder and the Director of the Wirelessand Internet Research Laboratory (WIRLab) at the University of Toronto.Professor Valaee recently served as the TPC Co-Chair of ICT 2015. He wasthe Track Chair of the IEEE Wireless Communications and NetworkingConference (WCNC) 2014, the TPC Co-Chair and the Local Organization Chairof IEEE Personal Mobile Indoor Radio Communication (PIMRC) Symposium 2011,and the Co-Chair for Wireless Communications Symposium of IEEE GLOBECOM2006. From December 2010 to December 2012, he was the Associate Editor ofthe IEEE Signal Processing Letters. Currently, he serves as an Editor ofIEEE Transactions on Wireless Communications. Since Feb 2015 he has been anEditor of the Elsevier Journal of Computer and System Science. ProfessorValaee is a Fellow of the Engineering Institute of Canada.

Learning WiFi Performance
2015-05-27 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Accurate prediction of wireless network performance isimportant when performing link adaptation or resource allocation. However,the complexity of interference interactions at MAC and PHY layers, as wellas the vast variety of possible wireless configurations make it notoriouslyhard to design explicit performance models.In this work, we advocate anapproach of ``learning by observation'', where we use machine learningtechniques to learn implicit performance models, from a limited number ofreal-world measurements. While our model does not use information on theWiFi mechanism itself, our results show that the accuracy of performanceprediction is significantly improved as compared to measurement-seededmodels based on SINR. To demonstrate that learned models can be useful inpractice, we build a new algorithm that uses such a model as an oracle tojointly allocate spectrum and transmit power. Our algorithm isutility-optimal, distributed, and it produces efficient allocations thatsignificantly improve performance and fairness.Joint work with JulienHerzen (EPFL) and Henrik Lundgren (Technicolor)

Sampling Node Pairs in Large Graphs
2015-05-27 11:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
Characterizing user pair relationships isimportant for applications such as friend recommendation and interesttargeting in online social networks (OSNs). Due to the large scale natureof such networks, it is infeasible to enumerate all user pairs and sosampling is necessarily used. In this talk I focus on this problem from twoperspectives, from an OSN service provider with access to the completenetwork and from a suspicious BBN summer intern with limited access to thenetwork. Characterizing pair relationships poses a great challenge to anOSN provider even when it possesses the complete topology. The reason isthat when sampling techniques, e.g., uniform vertex sampling (UVS) arenaively applied, they can introduce large biases, in particular, forestimating similarity distribution statistics of user pairs such as networkhomophily. Estimating statistics of user pairs is more challenging in theabsence of the complete topology information, since an unbiased samplingtechnique such as UVS is usually not allowed, and exploring the OSNtopology is expensive. To address these challenges, we present unbiasedsampling methods to characterize user pair properties based on UVS andrandom walks (RWs) respectively. We evaluate our methods to show theiraccuracy and efficiency. Finally, we apply our methods to several OSNs andcharacterize the homophily present in each.

Biography:
Don Towsleyholds a B.A. in Physics (1971) and a Ph.D. in Computer Science (1975) fromUniversity of Texas. He is currently a Distinguished Professor at theUniversity of Massachusetts in the Department of Computer Science. He hasheld visiting positions at numerous universities and research labsincluding University of Paris VI, IBM Research, AT&T Research,Microsoft Research, and INRIA. His research interests include networks andperformance evaluation.He currently serves as Co-Editor-in-Chief of the newACM Transactions on Modeling and Performance Evaluation of ComputingSystems (ToMPECS). He served as Editor-in-Chief of the IEEE/ACMTransactions on Networking and as an associate editor of numerous journals.He has served as Program Co-chair of INFOCOM 2009, Performanceâ€™02,and the joint 1992 ACM SIGMETRICS/Performance Conference as well as GeneralChair of COMSNETS 2012. He is a member of ACM and IEEE.He has receivednumerous IEEE and ACM awards including the 2007 IEEE Koji Kobayashi Awardand several achievement award. He has also received numerous best paperawards including the IEEE Communications Society 1998 William Bennett PaperAward, several test of time awards and conference best paper awards.Last, he has been elected Fellow of both the ACM and IEEE.

The Power of Online Learning in Stochastic Network Optimization
2015-05-22 10:30 - 11:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
We investigate the power of online learning instochastic network optimization with unknown system statistics a priori. Weare interested in understanding how information and learning can beefficiently incorporated into system control techniques, and what are thefundamental benefits of doing so. We propose two Online Learning-AidedControl techniques, OLAC and OLAC2, that explicitly utilize the pastsystem information in current system control via a learning procedurecalled dual learning. We prove strong performance guarantees of theproposed algorithms: OLAC and OLAC2 achieve the near-optimal O(epsilon),O([log(1/epsilon)^2)]$ utility-delay tradeoff and OLAC2 possesses an$O(epsilon^-2/3)$ convergence time. OLAC and OLAC2 are probably the firstalgorithms that simultaneously possess explicit near-optimal delayguarantee and sub-linear convergence time. Simulation results also confirmthe superior performance of the proposed algorithms in practice. To thebest of our knowledge, our attempt is the first to explicitly incorporateonline learning into stochastic network optimization and to demonstrate itspower in both theory and practice.

Biography:
Dr. Longbo Huangreceived his Ph.D. from the EE department at the University of SouthernCalifornia in August 2011. He was then a postdoctoral researcher in theEECS department at UC Berkeley from July 2011 to August 2012. Since then hehas been an assistant professor at the Institute for InterdisciplinaryInformation Sciences (IIIS) at Tsinghua University. Dr. Huang was avisiting scholar at the LIDS lab at MIT in summer 2012 and 2014, at theEECS department at UC Berkeley in summer 2013, and at Bell-labs France inApril 2013. He was also a visiting professor at the Institute of NetworkCoding at CUHK in winter 2012. Dr. Huang was selected into China'sYouth1000-talent program in 2013. Dr. Huang's research interests lie in theareas of stochastic learning and optimization for networked systems,delay-efficient network control, mobile networks, data centernetworking, energy management and smart grid.

Understanding Online Video Users: A Key to the Future of theInternet
2015-05-20 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Online video is the killer application of the Internet.It is predicted that more than 85% of the consumer traffic on the Internetwill be video-related by 2016. Yet, the future economic viability ofonline videos rest squarely on our ability to understand how viewersinteract with video content. For instance: (i) If a video fails to start upquickly, would the viewer abandon (ii) If a video freezes in the middle,would the viewer watch fewer minutes (iii) If a video fails to load, isthe viewer less likely to return to the same site (iv) if a video plays athigher quality, will the viewer watch more minutes, etc.In this talk, weoutline scientific answers to these and other such questions, establishinga causal link between video performance and viewer behavior. One of thelargest such studies, our work analyzes the video viewing habits of over65 million viewers who in aggregate watched almost 367 million videos. Togo beyond correlation and to establish causality, we develop a noveltechnique based on Quasi-Experimental Designs (QEDs). While QEDs are wellknown in the medical and social sciences, our work represents its firstuse in network performance research and is of independent interest. Ourwork also a played key role in the recent net neutrality debate inassessing the likely impact of a "fast-lane" on the Internet.This talk isof general interest and is accessible to a broad audience

Ramesh K.Sitaraman is a professor of computer science at the University ofMassachusetts at Amherst and is Akamaiâ€™s chief consulting scientist.His research focuses on all aspects of Internet-scale distributed systems,including algorithms, architectures, performance, energy efficiency,user behavior, and economics. As a principal architect, he helped createthe Akamaiâ€™s distributed delivery networks and was an Akamai Fellow.He is best known for his role in pioneering the first major contentdelivery networks (CDNs) that currently deliver a significant fraction ofthe worldâ€™s web content, streaming videos, and onlineapplications. He received a PhD in Computer Science from PrincetonUniversity and a B. Tech from the Indian Institute of Technology,Madras.

Analyzing Interference from Static Cellular Cooperation using theNearest Neighbour Model
2015-04-15 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
The problem of base station cooperation has recently been setwithin the framework of Stochastic Geometry. Existing works consider that auser dynamically chooses the set of stations that cooperate for his/herservice. However, this assumption often does not hold. Cooperation groupscould be predefined and static, with nodes connected by fixedinfrastructure. To analyse such a potential network, in this work wepropose a grouping method based on proximity. It is a variation of the socalled Nearest Neighbour Model. We restrict ourselves to the simplest casewhere only singles and pairs of base stations are allowed to be formed. Forthis, two new point processes are defined from the dependent thinning of aPoisson Point Process, one for the singles and one for the pairs.Structural characteristics for the two are provided, including theirdensity, Voronoi surface, nearest neighbour, empty space and J-function.We further make use of these results to analyse their interference fieldsand give explicit formulas to their expected value and their Laplacetransform. The results constitute a novel toolbox towards the performanceevaluation of networks with static cooperation.

A Flow-Level Performance Model for Mobile Networks CarryingAdaptive Streaming Traffic
2015-04-15 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
As the adaptive streaming technology becomes the mainstreamsolution for online video service and 4G broadband service becomes veryaccessible, for mobile service providers, having a performance modelintegrating adaptive streaming and elastic traffic becomes a necessity. Weaim to build an adaptive streaming model by using flow-dynamics and toexamine the streaming performance. Our model takes both the codeclimitation and integration of elastic data into account, which assist theoperators to understand the trade-offs among different metrics such asdeficit rate, mean codec rate and mean elastic throughput when differentconfigurations and prioritization factors are chosen. The simulationresults obtained with the real statistics of Orange mobile networkdemonstrated the maximum traffic intensity under certain QoS constraintsand its corresponding optimal prioritization factor.

BASIC regenerating codes for distributed storage systems
2015-04-08 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Reliability in disk arrays is provisioned by storing the datawith redundancy. For example, in RAID-6, we protect the data from beinglost by introducing parity-check disks, so that any failure of two diskscan be restored. In a large-scale distributed storage system, diskfailures and repairs are common day-to-day event, and incur excessiveamount of traffic for the recovery of failed disks. A class of codes,called regenerating codes, was introduced by Dimakis et al. for thepurpose of reducing the required repair traffic. Like Reed-Solomon codes,most of the existing regenerating codes rely on the arithmetic of finitefields. The computational complexity of encoding and decoding may renderthe system impracticable if the size of the finite field is large. In thistalk, we discuss a construction of regenerating codes called BinaryAddition and Shift Implementable Convolutional (BASIC) codes, in whichfinite field additions and multiplications are replaced by bit-wiseexclusive OR and bit-wise shifting. The advantage of regenerating code isthereby attained with lower computational cost. This is a joint work withMinghua Chen, Hanxu Hou and Hui Li.

Optimal Geographic Caching in Cellular Networks
2015-04-01 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We consider the problem of an optimal geographic placement ofcontent in wireless cellular networks modelled by Poisson point processes.Specifically, for the typical user requesting some particular content andwhose popularity follows a given law (e.g. Zipf), we calculate theprobability of finding the content cached in one of the base stations.Wireless coverage follows the usual signal-to-interference-and noise ratio(SINR) model, or some variants of it. We formulate and solve the problemof an optimal randomized content placement policy, to maximize the user'shit probability. The result dictates that it is not always optimal tofollow the standard policy "cache the most popular content, everywhere".In fact, our numerical results regarding three different coveragescenarios, show that the optimal policy significantly increases thechances of hit under high-coverage regime, i.e., when the probabilitiesof coverage by more than just one station are high enough.

A Synchronous View of Loosely Time-Triggered Architectures
2015-03-25 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
Loosely Time-Triggered Architectures (LTTAs)are a proposal forconstructing distributing embedded control systems. Theybuild onquasi-periodic systems, where computing units executealmostperiodically, by adding a thin layer of middleware thatfacilitatesthe deployment of synchronous applications.In this paper, weshow how the deployment of a synchronous applicationon a quasi-periodicarchitecture can be modeled using a synchronousformalism. Then we detailtwo LTTA protocols, Back-PressureLTTA reminiscent of elastic circuits,and a new class ofTime-Based LTTA. Finally, we compare the LTTA approachto clocksynchronization protocols which are becoming more an morecommonnowadays. Joint work with Albert Benveniste (INRIA)

VANET Services and Mobile Vehicle Clouds
2015-03-18 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
New vehicle applications have recently emergedin several areas ranging from navigation safety to location aware contentdistribution, urban surveillance and intelligent transport. A new impulseis given by autonomous vehicle with plenty of sensors, memory andprocessing power. The richness of on board resources and the diversity ofapplications sets the Vehicular ad Hoc Network (VANET) apart fromconventional MANETs and does introduce new challenges in the services theycan provide. A representative service scenario is urban sensing: vehiclesmonitor the environment, classify the events, e.g., license plates,chemical readings etc, and support forensic service requests fromAuthorities. This notion of service suggests that the VANET can be viewedas a Mobile Computing Cloud (MCC) where vehicles interact and collaborateto sense the environment, process the data, V2V propagate the results andshare resources to provide mobile services. This talk will revisit VANETapplications and services in light of the Mobile Cloud model. It will thenpropose a Vehicular Cloud platform and will address the cooperation withEdge Cloud and Internet Cloud.

Biography:
Dr. Mario Gerla is aProfessor in the Computer Science Dept at UCLA. He holds an Engineeringdegree from Politecnico di Milano, Italy and the Ph.D. degree from UCLA.He became IEEE Fellow in 2002. At UCLA, he was part of the team thatdeveloped the early ARPANET protocols under the guidance of Prof. LeonardKleinrock. He joined the UCLA Faculty in 1976. At UCLA he has designednetwork protocols including ad hoc wireless clustering, multicast (ODMRPand CODECast) and Internet transport (TCP Westwood). He has lead the ONRMINUTEMAN project, designing the next generation scalable airborneInternet for tactical and homeland defense scenarios. He is now leadingseveral advanced wireless network projects under Industry and Governmentfunding. His team is developing a Vehicular Testbed for safe navigation,content distribution, urban sensing and intelligent transport. Parallelresearch activities are wireless medical monitoring using smart phones andcognitive radios in urban environments.He has served as a Technical ProgramCommittee member of many international conferences, and is active in theorganization of conferences and workshops, including MedHocNet and WONS.He serves on the IEEE TON Scientific Advisory Board. He was recentlyrecognized with the annual MILCOM Technical Contribution Award for 2011 andthe IEEE Ad Hoc and Sensor Network Society Achievement Award in2011.

Game-theoretic statistics: Learning from data generated bystrategic agents
2015-03-11 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Statistical learning methods developed in the last decades haveproved very useful for many applications. However, most algorithms weredeveloped under the assumption that the data is independent from thealgorithm. This is no longer true in applications where data is generatedor provided by (human) strategic agents. As more and more modernapplications indeed learn from data provided by external parties, itbecomes increasingly crucial to account for the data-provider's incentivesin order to design well-performing learning algorithms in practice.In thistalk, we use game theory to model explicitly the economic incentives ofthe learner and of the agents generating data. We show how, by analyzingthe game, it is possible to design learning algorithms that work betterbecause they account for the agents' incentives. Specifically, weillustrate this in two examples with applications in security and privacy:(i) Classification of malicious behavior: In this example, a defender runsa classification algorithm to detect malicious behavior while an attackerchooses his attack strategy to balance the utility of the attack and theprobability of being detected. We obtain analytic results that show how tooptimally perform the classification given the attacker's utility. (ii)Linear regression from agents-provided data: In this example, we study thecase of an analyst who tries to infer a model through linear regressionfrom data provided by individuals who add noise to protect their privacy(this technique is called "local privacy"). We again derive results onoptimal linear regression and on the price of anarchy of the system thatprovide methods to better learn from privacy-conscious users byincentivizing them to provide higher-quality data.

On the Design of Integrated Forwarding and Caching Policies inNamed-Data Networking
2015-03-11 11:00 - 12:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
Current IP-based networks are unable to fullyexploit the capabilities ofthe increasing number of multi-homed mobileterminals. We argue thatNamed-Data Networking (NDN) can fill the gap.First, we elaborate on therequirements for NDN packet forwarding tomulti-homed mobile terminalsand categorize forwarding strategies accordingto their ability to fulfill theserequirements. Further, we describe theinitial design of an advanced multi-path forwarding strategy that isderived from performance insights gainedby a CCNx implementation.Secondly, we investigate the performance of aLRU cache replacement policyin the related tree structure. We start withthe performance approximationof Che et al. and assume Zipf-distributedfrequencies of object requeststhat constitute associated Poisson streams.Then we derive new explicitformulae regarding the hit and miss ratios in thiscascade of LRU caches.Considering adaptive or cooperative cache policies insuch an access networkwith multi-homed mobile clients, the sketched resultsprovide a basis foran integrated design of efficient forwarding schemes withoptimal cacheplacement.

The Cirrus Cloud Project: Opportunistic Mobile Cloud Computing
2015-03-04 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Mobile devices are increasingly being relied on for tasks thatgo beyond simple connectivity and demand more complex processing. In caseswhere such processing exceeds a deviceÃ¢â‚¬â„¢s capability,remote cloud resources can be used to off-load the Ã¢â‚¬Å“heavyliftingÃ¢â‚¬Â needed by mobile computation tasks. The Cirrus Cloudproject focuses on the design and analysis of techniques that enable theprovision of cloud computation services to mobile devices. The project isdistinguished by 1) its consideration of specific challenges of thewireless and mobile environment and 2) its focus on leveraging thecomputational capability of a variety of entities present in a mobiledeviceÃ¢â‚¬â„¢s environment in an opportunistic manner. In thistalk we will first give an overview of the Cirrus Cloud project and itsaims. We will then discuss two specific directions of work that representtwo points on a spectrum of mobile cloud computing scenarios. In the firstwe design and evaluate the COSMOS system which enables mobile computationrequirements to map seamlessly to traditional cloud computing services. Inthe second we consider how clusters of mobile devices may be configured asa powerful compute resource. We will conclude with a discussion of ourplans for future research.

Biography:
Mostafa Ammar is aRegents' Professor with the School of Computer Science at the GeorgiaInstitute of Technology. He has been with Georgia Tech since 1985. Dr.Ammar received the S.B. and S.M. degrees from the Massachusetts Instituteof Technology in 1978 and 1980, respectively and the Ph.D. degree from theUniversity of Waterloo, Ontario, Canada in 1985. Dr. Ammar's researchinterests are in network architectures, protocols and services. He hascontributions in the areas of multicast communication and services,multimedia streaming, content distribution networks, network simulation,disruption-tolerant networks, virtual network design, and most recentlyin mobile cloud computing. He has published extensively in these areas. Todate, 33 PhD students have completed their degrees under his supervision;many have gone on to distinguished careers in academia and industry. Dr.Ammar has served the research community in multiple roles. Most notably,he served as the Editor-in-Chief of the IEEE/ACM Transactions on Networking(ToN) from 1999 to 2003, and he was the co-TPC Chair for the IEEE ICNP1997, ACM CoNEXT 2006 and ACM SIGMETRICS 2007 conferences. His awardsinclude the IBM Faculty Partnership Award (1996), Best Paper Award at the7th WWW conference (1998), the Georgia Tech Outstanding Doctoral ThesisAdvisor Award (2006), the Outstanding Service Award from the IEEETechnical Committee on Computer Communications (2010), and the ACM MobihocBest Paper Award (2012). Dr. Ammar was elected Fellow of the IEEE in 2002and Fellow of the ACM in 2003.

A Hitchhiker's guide to ontology
2015-02-25 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
In this talk, I will present our recent work in the areaofknowledge bases. It covers 4 areas of research around ontologiesandknowledge bases: The first area is the construction of the YAGOknowledgebase. YAGO is now mulitlingual, and has grown into a largerproject at theMax Planck Institute for Informatics and TÃƒÂ©lÃƒÂ©comParisTech.The second area is the alignment of knowledge bases. Thisincludes thealignment of classes, instances, and relations acrossknowledge bases. Thethird area is rule mining. Our project findssemantic correlations in theform of Horn rules in the knowledge base.I will also talk aboutwatermarking approaches to trace the provenanceof ontological data.Finally, I will show applications of theknowledge base for mining newscorpora.

Perfect sampling for closed queueing networks
2015-02-11 14:30 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We investigate coupling from the past (CFTP) algorithmsforclosed queueing networks. The stationary distribution has a productformonly in a very limited number of particular cases when queue capacityisfinite, and numerical algorithms are intractable due to the cardinalityofthe state space. Moreover, closed networks do not exhibit any mono-tonicproperty enabling ecient CFTP. We derive a bounding chain forthe CFTPalgorithm for closed queueing networks. This bounding chainis based on acompact representation of sets of states that enables exactsampling fromthe stationary distribution without considering all initialconditions inthe CFTP. The coupling time of the bounding chain is al-most surelyfinite, and numerical experiments show that it is close to thecouplingtime of the exact chain.

Exploiting User Movement for Position Detection
2015-02-11 14:00 - 14:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
The major issue of indoor localization system is the trade-offbetween implementation cost and accuracy. A low-cost system which demandsonly few hardware devices could save the cost but often it turns out to beless reliable. Aiming at improving classical triangulation method thatrequires several reference points, this paper proposes a new method,called Two-Step Movement (2SM), which requires only one reference point(RP) by exploiting useful information given by the position change of amobile terminal (MT), or the user movement. This method can minimize thenumber of reference points required in a localization system or navigationservice and reduce system implementation cost. Analytical result shows thatthe user position can be thus derived and given in simple closed-formexpression. Finally, simulation is conducted to demonstrate itseffectiveness under noisy environment.

Optimal content prefetching for cloud assisted content delivery
2015-02-04 15:30 - 16:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Motivated by improved models for content workload prediction,in this paper we consider the problem of dynamic content allocation for ahybrid content delivery system that combines cloud-based storage with lowcost dedicated servers that have limited storage and unmetered uploadbandwidth. We formulate the problem of allocating contents to the dedicatedstorage as a finite horizon dynamic decision problem, and show that adiscrete time decision problem is a good approximation forpiecewisestationary workloads. We provide an exact solution to the discrete timedecision problem in the form of a mixed integer linear programmingproblem, propose computationally feasible approximations, and give boundson their approximation ratios. Finally, we evaluate the algorithms usingsynthetic and measured traces from a commercial music on-demand service andgive insight into their performance as a function of the workloadcharacteristics.

A New Perspective on Distributed Scheduling in Wireless MultihopNetworks
2015-01-21 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
One vision for wireless networks has been the creation ofwireless multihop networks that are formed and operate in a fullydecentralized manner using cheap commodity hardware. One of the mainchallenges to achieve this vision is the design of scheduling protocols fordata transmissions that are throughput and delay optimal, and can beimplemented in a fully distributed manner.In the talk, we present resultsthat provide a new perspective on the design of distributed schedulingalgorithms. In particular, our results suggest that it is possible tocreate protocols that throughput and delay order-optimal, and can beimplemented in a fully distributed manner. We will first discuss theintuition behind the performance limitations of traditional distributedscheduling protocols, and present the main idea behind our approach. Wewill then provide a more detail discussion of our results as well as futurework.An interesting aspect of the work is that the underlying mathematicalmodels and results may be of independent interest and might be applicableto more general combinatorial optimization problem.

Platforms and Applications for "Big and Fast" DataAnalytics
2015-01-14 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Recently there has been a significant interest in building bigdata systems that can handle not only "big data" but also "fast data" foranalytics. Our work is strongly motivated by recent real-world case studiesthat point to the need for a general, unified data processing framework tosupport analytical queries with different latency requirements. Towardsthis goal, our project is designed to transform the popular MapReducecomputation model, originally proposed for batch processing, intodistributed (near) real-time processing. In this talk, I start byexamining the widely used Hadoop system and presenting a thorough analysisto understand the causes of high latency in Hadoop. I then present a numberof necessary architectural changes, as well as new resource configurationand optimization techniques to meet user-specified latency requirementswhile maximizing throughput. Experiments using typical workloads in clickstream analysis and twitter feed analysis show that our techniques reducethe latency from tens or hundreds of seconds in Hadoop to sub-second in oursystem, with 2x-7x increase in throughput. Our system also outperformsstate-of-the-art distributed stream systems, Twitter Storm and SparkStreaming, by a wide margin. Finally, I will show some initial resultsand challenges of supporting big and fast data analytics in the emergingdomain of genomics.

Biography: Yanlei Diao is Associate Professor ofComputer Science at the University of Massachusetts Amherst. Her researchinterests are in information architectures and data management systems,with a focus on big data analytics, data streams, uncertain datamanagement, and RFID and sensor data management. She received her PhD inComputer Science from the University of California, Berkeley in 2005, herM.S. in Computer Science from the Hong Kong University of Science andTechnology in 2000, and her B.S. in Computer Science from Fudan Universityin 1998. Yanlei Diao was a recipient of the 2013 CRA-W Borg Early CareerAward (one female computer scientist selected each year), IBM ScalableInnovation Faculty Award, and NSF Career Award, and she was a finalist ofthe Microsoft Research New Faculty Award. She spoke at the DistinguishedFaculty Lecture Series at the University of Texas at Austin. Her PhDdissertation "Query Processing for Large-Scale XML Message Brokering" wonthe 2006 ACM-SIGMOD Dissertation Award Honorable Mention. She is currentlyEditor-in-Chief of the ACM SIGMOD Record, Associate Editor of ACM TODS,Area Chair of SIGMOD 2015, and member of the SIGMOD Executive Committeeand SIGMOD Software Systems Award Committee. In the past, she has servedas Associate Editor of PVLDB, organizing committee member of SIGMOD,CIDR, DMSN, and the New England Database Summit, as well as on theprogram committees of many international conferences and workshops. Herresearch has been strongly supported by industry with awards from Google,IBM, Cisco, NEC labs, and the Advanced Cybersecurity Center.

Cooperation between LTE and emergent DVB technologies for anefficient delivery of mobile TV
2015-01-07 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
The broadcast/cellular cooperation for a common delivery ofMobile TV is at the heart of the emerging mobile broadcast technologies,namely the mobile extension of the second generation digital videobroadcasting for terrestrial reception (DVB-T2Lite) and its followerDVB-Next Generation Handheld (DVB-NGH). These broadcasttechnologies aim tocooperate with the Long Term Evolution (LTE), as the latter is intended tobe the bearer of Mobile TV thanks to its enhanced-Multimedia BroadcastandMulticast Service feature (e-MBMS).Even though the 3GPP/DVB cooperation isnot a new topic and was investigate dwith the introduction of the previousDVB technology, known as DVB-Handheld(DVB-H), most of the worksaddressing this issue considered a common service area covered by both DVBand cellular systems and focused solely on the impact of such cooperationin terms of capacity gains brought by 3GPP and error repair gains broughtby DVB. This strategy was judged to be expensive since a new and very denseDVB network was needed. In order to overcome this problem and decrease asmuch as possible the need for a new broadcast network, we propose in thisthesis a hybrid DVB/LTEnetwork with a coverage extension strategy, wherethe LTE system, planned for almost a universal coverage, is used todeliver Mobile TV in areas not covered by recent DVB-T2 Lite (or eventuallyDVB-NGH) network. In this context, we explore twomain issues:1. Mobile TVservices have to share LTE resources with other higher priority servicessuch as voice traffic. The dynamicity of the latter will impact the Qualityof Service (QoS) of Mobile TV. We propose a new QoS-based planning1for thehybrid DVB/LTE so as to guarantee an acceptable watching experience withoutover-dimensioning the LTE system. We derive using Markov chain analysis andhitting time theory, several QoS metrics pertaining to mobile TVperformance, such as interruption frequency and duration.2. A new businessmodel which clarifies the relationships between the different factors ofthe ecosystem namely DVB and LTE operators as well as the TVchannelproviders and constructs the service area from an economic point of view isneeded. In fact, the absence of a clear and viable economic model thatresolves the monetary conflicts between cellular and broadcast operatorswas one of the main drawbacks behind the failure of the first attempt ofmobile TVd elivery by cooperating UMTS/DVB-H. We develop in this thesis aprofit sharing strategy for the cooperative network, using coalition gameconcept Shapley value and Nash equilibrium for a self-enforcing strategy.We further develop anew framework using real option theory coupled withcoalition games for investment decision in mobile TV networks (whether anoperator should enter the mobile TV market and, if yes, when to do so)and show how operators canin corporate the uncertainties related to demandand network operation costs.We propose a bi-level dynamic programmingalgorithm to solve numerically the developed real option game.

Cloud 2020: The Emergence of Micro Datacenter for Mobile Computing
2014-12-17 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Resource poverty is a fundamental constraint that severelylimits the types of applications that can be run on mobile devices. Thisconstraint is not just a temporary limitation of current technology but isintrinsic to mobility. In this talk, I will put forth a vision of thecloud that breaks free of this fundamental constraint. In this vision,mobile users seamlessly utilize nearby computers to obtain the resourcebenefits of cloud computing without incurring WAN delays and jitter. Ratherthan relying on a distant cloud the client connects and uses a nearby microdatacenter (mDC). Crisp interactive response for immersive applicationsthat augment human cognition are then easier to achieve. While muchengineering and research remains, the concepts and ideas introduced openthe door to a new world of disaggregated computing in which seamlesscognitive assistance for users can be delivered at any time and anyplace.

Victor Bahl is a Principal Researcher and the Director of theMobility & Networking Research (MNR) group in Microsoft Research.MNR's mission is to invent & research technologies that makeMicrosoft's networks, services, and devices indispensable to the world.In addition to shepherding brilliant researchers, Victor helps shapeMicrosoft's long-term vision related to networking technologies by advisingthe CEO and senior executive team, and by executing on this vision throughresearch, technology transfers, and associated policy engagements withgovernments and industries around the world. He and his group have hadfar-reaching impact on the research community, government policy, andMicrosoft products through numerous significant publications and technologytransfers. His personal research spans a variety of topics in mobile &cloud computing, wireless systems & services, and datacenter &enterprise networking. Over his career he has built many highly citedseminal systems, published prolifically in top conferences and journals,authored 115 patents, given over three dozen keynote talks, won numerousprestigious awards and honors including ACM SIGMOBILE's LifetimeAchievement Award and IEEE Outstanding Leadership and Professional ServiceAward. Victor received his PhD from the University of Massachusetts Amherstin 1997. He is a Fellow of the ACM, IEEE and AAAS.

Is there a case for mobile phone content pre-staging
2014-12-10 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Content caching is a fundamental building block of theInternet. Caches are widely deployed at network edges to improveperformance for end-users, and to reduce load on web servers and thebackbone network. Considering mobile 3G/4G networks, however, thebottleneck is at the access link, where bandwidth is shared among allmobile terminals. Assuch, per-user capacity cannot grow to cope with thetraffic demand. Unfortunately, caching policies would not reduce the loadon the wireless link which would have to carry multiple copies of the sameobject that is being downloaded by multiple mobile terminals sharing thesame access link.In this paper we investigate if it is worth to push thecaching paradigm even farther. We hypothesize a system in which mobileterminals implement a local cache, where popular content can bepushed/pre-staged. This exploits the peculiar broadcast capability of thewireless channels to replicate content "for free" on all terminals, savingthe cost of transmitting multiple copies of those popular objects. Relyingon a large data set collected from a European mobile carrier, we analysethe content popularity characteristics of mobile traffic, and quantify thebenefit that the push-to-mobile system would produce. We found that contentpre-staging, by proactively and periodically broadcasting "bundles" ofpopular objects to devices, allows to both greatly i) improve users'performance and ii) reduce up to 20% (40%) the downloaded volume (number ofrequests) in optimistic scenarios with a bundle of 100 MB. However, sometechnical constraints and content characteristics could question the actualgain such system would reach in practice..

The Cost of the "S" in HTTPS
2014-12-10 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Increased user concern over security and privacy on theInternet has led towidespread adoption of HTTPS, the secure version ofHTTP. HTTPS authenticatesthe communicating end points and providesconfidentiality for the ensuingcommunication. However, as with anysecurity solution, it does not come forfree. HTTPS may introduce overheadin terms of infrastructure costs,communication latency, data usage, andenergy consumption. Moreover, given theopaqueness of the encryptedcommunication, any in-network value added servicesrequiring visibilityinto application layer content, such as caches and virusscanners, becomeineffective.This paper attempts to shed some light on these costs. First,taking advantageof datasets collected from large ISPs, we examine theaccelerating adoption ofHTTPS over the last three years. Second, wequantify the direct and indirectcosts of this evolution. Our results showthat, indeed, security does not comefor free. This work thus aims tostimulate discussion on technologies that canmitigate the costs of HTTPSwhile still protecting the user's privacy.

Evaluating user-perceived performance in FTTH access networks
2014-12-03 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We evaluate the performance perceived by end-users connected toa backhaul link that aggregates the traffic of multiple access areas. Wemodel, at flowlevel, the way a finite population of users withheterogeneous access rates and traffic demands shares the capacity ofthiscommon backhaul link. We then evaluate several practically interestinguse cases, focusing particularly on the performance of users subscribingto recent FTTH offers in which the user access rates are in the same orderof magnitude as the backhaul link capacity. We show that, despite suchhigh access rates, reasonable performance can be achieved as long as thetotal offered traffic iswell below the backhaul link capacity. The obtainedperformance results are used to derive simple dimensioning guidelines.

Catalog Dynamics: Impact of Content Publishing and Perishing on thePerformance of a LRU Cache
2014-11-19 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
:
The Internet heavily relies on Content DistributionNetworks and transparent caches to cope with the ever-increasing trafficdemand of users. Content, however, is essentially versatile: oncepublished at a given time, its popularity vanishes over time. All requestsfor a given document are then concentrated between the publishing time andan effective perishing time. In this paper, we propose a new model for thearrival of content requests, which takes into account the dynamical natureof the content catalog. Based on two large traffic traces collected on theOrange network, we use the semi-experimental method and determineinvariants of the content request process. This allows us to define asimple mathematical model for content requests; by extending the so-calledChe approximation, we then compute the performance of a LRU cache fed withsuch a request process, expressed by its hit ratio. We numericallyvalidate the good accuracy of our model by comparison to trace-basedsimulation. Joint work with Felipe Olmos, Alain Simonian and YannickCarlinet

Controlling Adaptive Video Streaming Systems: One Knob is Enough
2014-11-12 14:00 - 14:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
The video part of Internet traffic is booming due to the everincreasing availability of video content from sitessuch as YouTube (videosharing), Netflix (movie on demand), Livestream(live streaming).Adaptivevideo streaming systems dynamically change the video contentbitrate andresolution to match thenetwork available bandwidth and user screenresolution.The mainstream approach employed by adaptive streaming systems,employed byNetflix and Youtube, is touse two controllers: one is thestream-switching algorithm that selects thevideo level, the otherregulates theplayout buffer length to a set-point.In this talk we show thatsuch an approach is affected by a fundamentaldrawback: the video flows arenot able to get thebest possible video quality when competing with TCPflow. We then design anadaptive video streaming system which fixesthisissue by only using one controller. An experimental evaluation showsthebenefits of the proposed control system.

Unimodal Bandits without Smoothness
2014-11-05 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Â Abstract:
In this talk we present new results on thestochastic bandit problems with a continuum set of arms and where theexpected reward is a continuous and unimodal function of the arm. Oursetting for instance includes the problem considered in (Cope, 2009) and(Yu, 2011). No assumption beyond unimodality is made regarding thesmoothness and the structure of the expected reward function. Our firstresult is an impossiblity result: without knowledge of the smoothness ofthe reward function, there exists no stochastic equivalent to Kiefer'sgolden section search (Kiefer, 1953). Further, we propose StochasticPentachotomy (SP), an algorithm for which we derive finite-time regretupper bounds. In particular, we show that, for any expected rewardfunction $mu$ that behaves as $mu(x)=mu(x^star)-C|x-x^star|^xi$ locallyaround its maximizer $x^star$ for some $xi, C>0$, the SP algorithm isorder-optimal, i.e., its regret scales as $O(sqrtTlog(T))$ when the timehorizon $T$ grows large. This regret scaling is achieved without theknowledge of $xi$ and $C$. Our algorithm is based on asymptotically optimalsequential statistical tests used to successively prune an interval thatcontains the best arm with high probability. To our knowledge, the SPalgorithm constitutes the first sequential arm selection rule that achievesa regret scaling as $O(sqrtT)$ up to a logarithmic factor for non-smoothexpected reward functions, as well as for smooth functions with unknownsmoothness. This is a joint work with Alexandre ProutiÃ¨re available at :http://arxiv.org/abs/1406.7447

Biography:
Bio: Richard Combesreceived the Engineering degree from Telecom ParisTech (2008), theMaster's degree in mathematics from university of Paris VII (2009) and thePh.D. degree in mathematics from university of Paris VI (2012). He was avisiting scientist in INRIA (2012) and a post-doc in KTH (2013). He iscurrently an Assistant Professor in SupÃ©lec. He received the best paperaward at CNSM 2011. His current research interests include communicationnetworks, stochastic systems and their control and machinelearning.

On the spatial reuse on large random wireless networks
2014-10-29 14:00 - 14:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
In this work we analyze the estimation of the spatial reuse ofa wirelessnetwork equiped witha Medium Access Control (MAC) mechanism basedon 802.11's DistributedCoordination Function (DCF). Moreover we assume thatthe RTS/CTS handshakeis enabled in order to avoid the hidden nodeproblem.Our analysis is based on the definition of Parking Process over arandomgraph (the interference graph of the network) for which onlymildassumptions over the distribution of the nodes's degree are assumed.Then alarge graph limit when the number of nodes goes to infinity is provedwhichresults in a system of differential equations representing theevolutionof the nodes'degree. From the solution of this system we cancalculate thespatial reuse (or equivalently the jamming constant associatedto theparking process).Joint work of Paola Bermolen, Matthieu Jonckheere,Federico Larroca andPascal Moyal

Simplicial homology and wireless networks
2014-10-22 14:00 - 14:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Simplicial complex representation gives a mathematicaldescription ofthe topology of a wireless sensor network, i.e., itsconnectivity andcoverage. In these networks, sensors are randomly deployedin bulk inorder to ensure perfect connectivity and coverage. We proposeanalgorithm to discover which sensors are to be switched off,withoutmodification of the topology, in order to reduce energyconsumption.Our reduction algorithm can be applied to any type ofsimplicialcomplex and reaches an optimal solution.In a second part, weconsider a damaged wireless network, presentingcoverage holes ordisconnected components, wepropose a disaster recovery algorithm repairingthe network. Itprovides the list of locations where to put new nodestopatch the coverage holes and mend the disconnected components. Inorder todo this we first consider the simplicial complexrepresentation of thenetwork, then the algorithm adds supplementarynodes in excessive number,and afterwards runs the reduction algorithmin order to reach a unimprovableresult. We use a determinantal pointprocess for the addition of nodes: theGinibre point process which hasinherent repulsion betweenvertices.

Caesar: a content router for high-speed forwarding on contentnames.
2014-10-15 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Today, Internet users are mostly interested to consumecontent, information and services independently from the servers wherethese are located.Information Centric Networking (ICN) is a recentnetworking vein which proposes to enrich the network layer with name-basedforwarding, a novel communication primitive centered around contentidentifiers rather than their location.Despite several name-basedforwarding strategies have been proposed, few have attempted to build acontent router. Our work fills such gap by designing and prototypingCaesar, a content router for high-speed forwarding on content names.Caesarhas several innovative features: (i) a longest prefix matching algorithmthat efficiently supports
content names, (ii) an incremental design whichallows for easy integration with existing network equipments, (iii)support for packet processing offload to graphics processing units (GPUs),and (iv) a forwarding engine distributed across multiple line cards. Webuild Caesar as a small scale router, and show that it sustains up to 10Gbps links and over 10 million content prefixes.In addition, GPU offloadfurther speeds up the forwarding rate by an order of magnitude, whiledistributed forwarding augments the amount of content prefixes servedlinearly with the number of line cards, with a small penalty in terms ofpacket processing latency.The full design of a content router also includesa Pending Interest Table and a Content Store. The former is adata-structure used to store pending requests not served yet, while thelatter is a packet-level cache used to temporary store forwarded data toserve future requests.We will discuss current and future work on theintegration of Pending Interest Table and Content Store in our contentrouter.

Analyzing Cacheable Traffic in ISP Access Networks for Micro CDNApplications via Content-Centric Networking
2014-10-08 14:30 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Web content coming from outside the ISP is today skyrocketing,causing significant additional infrastructure costs to network operators.The reduced marginal revenues left to ISPs, whose business is almostentirely based on declining flat rate subscriptions, call for significantinnovation within the network infrastructure, to support new servicedelivery.In this paper, we suggest the use of micro CDNs in ISP access andback-haul networks to reduce redundant web traffic within the ISPinfrastructure while improving user's QoS.With micro CDN we refer to acontent delivery system composed of (i) a high speed caching substrate,(ii) a content based routing protocol and (iii) a set of data transfermechanisms made available by content-centric networking.The contribution ofthis paper is twofold. First, we extensively analyze more than one monthof web traffic via continuous monitoring between the access and back-haulnetwork of Orange in France. Second, we characterize key properties ofmonitored traffic, such as content popularity and request cacheability,to infer potential traffic reduction enabled by the introduction of microCDNs.Based on these findings, we then perform micro CDN dimensioning interms of memory requirements and provide guidelines on design choices.

DROiD: Adapting to Individual Mobility Pays Off in Mobile DataOffloading
2014-10-08 14:00 - 14:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Cellular operators count on the potentials of offloadingtechniques to relieve their overloaded data channels. Beyond standardaccess point-based offloading strategies, a promising alternative is toexploit opportunistic direct communication links between mobile devices.Nevertheless, achieving efficient device-to-device offloading ischallenging, as communication opportunities are, by nature, dependent onindividual mobility patterns. We propose, design, and evaluate DROiD(Derivative Re-injection to Offload Data), an original method to finelycontrol the distribution of popular contents throughout a mobile network.The idea is to use the infrastructure resources as seldom as possible. Tothis end, DROiD injects copies through the infrastructure only whenneeded: (i) at the beginning, in order to trigger the dissemination, (ii)if the evolution of the opportunistic dissemination is below some expectedpace, and (iii) when the delivery delay is about to expire, in order toguarantee 100% diffusion. Our strategy is particularly effective in highlydynamic scenarios, where sudden creation and dissolution of clusters ofmobile nodes prevent contents to diffuse properly. We assess theperformance of DROiD by simulating a traffic information service on arealistic large-scale vehicular dataset composed of more than 10,000nodes.DROiD substantially outperforms other offloading strategies, savingmore than 50% of the infrastructure traffic even in the case of tightdelivery delay constraints. DROiD allows terminal-to-terminal offloading ofdata with very short maximum reception delay, in the order of minutes,which is a realistic bound for cellular user acceptance.

Maintenance et Evolution des logiciels
2014-09-18 14:00 - 15:00
Rue Barrault, Amphi Opale

A unified approach to the performanceanalysis of caching systems
2014-09-17 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We propose a unified methodology to analyse the performance ofcaches (both isolated and interconnected), byextending and generalizing adecoupling technique originally knownas Che's approximation, whichprovides very accurate results at low computational cost.We considerseveral caching policies, taking into account the effects of temporallocality. In the case of interconnected caches, our approach allows us todo better than the Poisson approximation commonly adopted in prior work.Our results,validated against simulations and trace-driven experiments,provide interesting insights into the performance of cachingsystems.

Joint work with Valentina Martina and Michele Garetto,appeared at IEEE INFOCOM'14

Energy management of demand in the cloud
2014-09-10 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We formulate optimization problems to study how data centersmight modulate their power demands for cost-effective operation taking intoaccount various complexities exhibited by real-world electricity pricingschemes. For computational tractability reasons, we work with a fluidmodel for power demands which we imagine can be modulated using twoabstract knobs of demand dropping and demand delaying (each with itsassociated penalties or costs). We consider both stochastically known andcompletely unknown inputs, which are likely to capture different datacenter scenarios. Using empirical evaluation with both real-world andsynthetic power demands and real-world prices, we demonstrate the efficacyof our techniques.

Work in collaboration with B. Urgaonkar, G.Kesidis, U. Shanbhag, Q. Wang, A. Sivasbramaniam

Semantic-based IoT service discovery mechanism for dynamicenvironments
2014-07-16 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
The adoption of Service Oriented Architecture (SOA) andsemantic Web technologies in the Internet of Things (IoT) enables toenhance the interoperability of devices by abstracting their capabilitiesas services and to enrich their descriptions with machine-interpretablesemantics. This facilitates the discovery and composition of IoT services.The increasing number of IoT services, their dynamicity and geographicaldistribution require mechanisms to enable scalable and efficient discovery.We propose, in this paper, a semantic based IoT service discovery systemthat supports and adapts to the dynamicity of IoT services. The discoveryis distributed over a hierarchy of semantic gateways. Within a semanticgateway, we implement mechanisms to dynamically organize its content overtime, in order to minimize the discovery cost. Results show that ourapproach enables to maintain a scalable and efficient discoveryand limitsthe number of updates sent to a neighboring gateway.

Tout ce que vous aimerez avoir su sur la 5G quand elle existera
2014-07-09 00:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Organic Computing: Adaptivity and Self-organization at Runtime @rue Barrault room E200
2014-07-04 15:00 - 16:00
Organic Computing has emerged almost 10 years ago as achallenging vision for future in-formation processing systems, based onthe insight that already in the near future we will be surrounded by largecollections of autonomous systems equipped with sensors and actuators to beaware of their environment, to communicate freely, and to organizethemselves. The presence of networks of intelligent systems in ourenvironment opens fascinating application areas but, at the same time,bears the problem of their controllability. Hence, we have to constructthese systems - which we increasingly depend on - as robust, safe,flexible, and trustworthy as possible. In order to achieve these goals,our technical systems will have to act more independently, flexibly, andautonomously, i.e. they will have to exhibit life-like properties. We callthose systems organic. Hence, an Organic Computing System is a technicalsystem, which adapts dynamically to the current conditions of itsenvironment. It will be self-organizing, self-configuring, self-healing,self-protecting, self-explaining, and context-aware.First steps towardsadaptive and self-organizing computer systems have already been undertaken.Adaptivity, reconfigurability, emergence of new properties, andself-organisation are topics in a variety of research projects. From 2005until 2011 the German Science Foundation (DFG) has funded a priorityresearch program on Organic Computing. It has addressed fundamentalchallenges in the design of complex computing systems; its ojective was adeeper understanding of emergent global behaviour in self-organisingsystems and the design of specific concepts and tools to support theconstruction of Organic Computing systems for technical applications.Thispresentation will briefly recapitulate the basic motivation for OrganicComputing, explain key concepts, and illustrate these concepts with someproject examples. We will then look into possible future directions of OCresearch concentrating on (1) Online optimization and (2) Social OrganicComputing.

Biography: Christian MÃ¼ller-Schloer studied EE at theTechnical University of Munich and received the Diploma degree in 1975,the Ph. D. in semiconductor physics in 1977. In the same year he joinedSiemens Corporate Technology where he worked in a variety of researchfields, among them CAD for communication systems, cryptography,simulation accelerators and RISC architectures.From 1980 until 1982 he wasa member of the Siemens research labs in Princeton, NJ, U.S.A. In 1991 hewas appointed full professor of computer architecture and operating systemsat the University of Hannover. His institute, later renamed to Instituteof Systems Engineering

Approximately Synchronous Distributed Systems
2014-07-02 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Applications hosted within the datacenter often rely ondistributed services such as Zookeeper, Chubby, and Spanner forfault-tolerant storage, distributed coordination, and transactionsupport. Â These systems provide consistency and availability in thepresence of limited failures by relying on sophisticated distributedalgorithms such as state machine replication. Â Unfortunately, thesedistributed algorithms are expensive, accrue additional latency, sufferfrom bottlenecks, and are difficult to optimize. Â This state of affairsis due to the fact that distributed systems are traditionally designedindependently from the underlying network and supporting protocols, makingworst-case assumptions (e.g., complete asynchrony) about itsbehavior.

While this is reasonable for wide-area networks, manydistributed applications are however deployed in datacenters, where thenetwork is more reliable, predictable, and extensible. Â Our positionis that codesigning networks and distributed systems in order to operateunder an "approximately synchronous" execution model can have substantialbenefits in datacenter settings. Â We will illustrate this using two casestudies in this talk: Speculative Paxos -- a distributed coordinationservice for datacenters that relies on the network to exhibit approximatelysynchronous behavior in the normal case, while still remaining correct ifthe network exhibits weaker properties, and Optimistic ReplicatedTwo-Phase Commit (OR-2PC) -- a new distributed transaction protocol thatuses a new optimistic ordering technique, based on loosely synchronizedclocks in order to improve both throughput and latency.

Randomness, Everlasting Security, and Undetectability
2014-06-25 15:00 - 16:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Security and privacy are fundamental concerns in today's world.These concerns have become particularly prominent with Snowden'srevelationsof the presence of the NSA in our daily lives. These revelationshave shown that traditional cryptographic techniques do not provide as wasexpected. This has called into question how security and privacy can beprovided. In this talk we investigate how randomness in the environment canbe used to provide everlasting security and undetectability(privacy) inwireless communications. In the first part of the talk we describe apractical way to harness this randomness to provide and improve thesecurity of wireless communications. We introduce the notion of "dynamicsecrets", information shared by two parties, Alice and Bob, engaged incommunication and not available to an adversary, Eve. The basic idea is todynamically generate a series of secrets from randomness present in the inwireless environment. These dynamic secrets exhibit interesting securityproperties and offer a robust alternative to cryptographic securityprotocols. We present a simple algorithm for generating these secrets andusing them to ensure secrecy.In some situations, Alice and Bob may wantnot only to secure their communications but to keep it private. In thesecond part of our talk we focus on the use of randomness to conceal thecommunications. Here the challenge is for Alice to communicate with Bobwithout an adversary, Willie the warden, ever realizing that thecommunication is taking place. Specifically, we establish that Alice cansend O(t) bits (and no more) to Bob in time t over a variety of wirelessand optical channels. Moreover, we report experimental results thatcorroborate the theory.

The art of packet format design
2014-06-25 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
TBA

Incentive Mechanisms for User-provided Networks
2014-06-19 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
The increasing mobile data demand and the proliferation ofadvanced handheld devices place the user-provided networks (UPNs) at aconspicuous position in next-generation network architectures. There hasbeen growing consensus that UPNs can play a crucial role both inself-organizing and in operator-controlled wireless networks, as theyenable the exploitation of the diverse communication needs and resources ofdifferent users. Today, many innovative startups such as Open Garden,M-87, and Karma, as well as major network operators such as DeutscheTelekom, Telefonica, Comcast, and China Mobile Hong Kong, propose oreven implement such models. However, in UPNs both the availability and thedemand for Internet access rely on user-owned network equipment.Therefore, the success of this type of networks depends on theparticipation of users. In this talk, we analyze the design challenges ofincentive mechanisms for encouraging user engagement in user-providednetworks. Motivated by recently launched business models, we focus onmobile UPNs where the energy consumption and data usage costs arecritical, and have a large impact on users' decisions both for requestingand offering UPN services. We outline two novel incentive schemes that havebeen recently proposed for such UPNs, and discuss the open issues thatmust be further addressed.

Biography: George Iosifidis holds anEngineering Degree in Telecommunications (Greek Air Force Academy, 2000),a M.Sc. and a Ph.D. degree in communication networks (University ofThessaly, 2007 and 2012). Currently, he is a post-doc researcher atCERTH/ITI and University of Thessaly, Volos. His research interests lie atthe nexus of network optimization and network economics, with emphasis onspectrum economics, autonomous networks, small cell networks,user-centric networks and mobile data offloading. More information can befound at www.georgeiosifidis.net

How user throughput depends on the traffic demand in large cellularnetworks
2014-06-18 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We assume a space-time Poisson process of call arrivals on theinfinite plane, independently marked by data volumes and served by acellular network modeled by an infinite ergodic point process of basestations. Each point of this point process represents the location of abase station that applies a processor sharing policy to serve usersarriving in its vicinity, modeled by the Voronoi cell, possibly perturbedby some random signal propagation effects.Using ergodic arguments and thePalm theoretic formalism, we define a global mean user throughput in thecellular network and prove that it is equal to the ratio of mean trafficdemand to the mean number of users in the steady state of the "typicalcell" of the network. Here, both means account for double averaging: overtime and network geometry, and can be related to the per-surface trafficdemand, base-station density and the spatial distribution of thesignal-to-interference-and-noise ratio. This latter accounts for networkirregularities, shadowing and cell dependence via some cell-loadequations.We validate our approach comparing analytical and simulationresults for Poisson network model to real-network measurements. Little'slaw allows expressing the mean user throughput in any region of the networkas the ratio of the mean traffic demand to the steady-state mean number ofusers in this region. Corresponding statistics are usually collected inoperational networks for each cell.

Modelling system behaviour subject to changing conditions
2014-06-17 10:30 - 11:45 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Quantitative evaluation plays a key role in the design of abroad range of systems, where functional and non-functional propertieshave to be carefully analysed in order to meet the requirements. In thistalk, an analytical framework that enables the study of a class ofphenomena where different working conditions alternate by changing thestochastic behaviour of the observed system but still preserving thecontinuity of the quantities to investigate is presented. The proposedsolution technique is based on phase type distributions and on an ad-hocfitting algorithm.
It allows to derive important metrics able tocharacterize the transient behaviour of the system and it is shown theimpact of such a feature on the evaluated metrics with respect moresimplistic (and classical) assumptions. On the other hand, the solutiontechnique allows to extend the semantic of some modelling formalism, suchas Petri nets, to represent new timing classes. Different cross-domainexamples are provided to show the usefulness and wide applicability of theframework.

http://mdslab.unime.it/specialvispeople.php?id=7

Convex relative entropy decay in Markov chains
2014-06-11 15:30 - 16:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Consider an irreducible continuous time Markov chain with afinite or a countably infinite number of states and admitting a uniquestationary probability distribution. The relative entropy of thedistribution of the chain at any time with respect to the stationarydistribution is a monotonically decreasing function of time. It isinteresting to ask if this function is convex. We discuss this question forfinite Markov chains and for Jackson networks, which are a class ofcountable state Markov chains of interest in modeling networks of queues.(Joint work with Varun Jog.)

Smart Cites, Smart things...and Smart Citizens: designing the cityas platform
2014-06-11 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
This paper asks how can we better design urban environments,leveraging networked technologies to facilitate rich engagement by itsinhabitants. It discussed the recent history of Smart City design as atop-down application, the emergence of Civic Hackers, and the effect ofubiquitous computing on Information Communication Technologies.

Dr. BethColeman, director City as Platform Lab (Games Institute), and Co-directorCritical Media Lab at the University of Waterloo, Ontario Canada.<www.cityasplatform.org> She is a Faculty Fellow at Berkman Centerfor Internet & Society, Harvard University. Coleman works with newtechnology and art to create transmedia forms of engagement. Her researchaddresses issues of network society, subjectivity, and the contemporarycity, as well as philosophy of technology, critical race studies, andmedia design. She is the co-founder of SoundLab Cultural Alchemy, aninternationally acclaimed multimedia performance platform. As an artist,she has a history of international exhibition including venues such as theWhitney Museum of American Art, New Museum of Contemporary Art, andMusÃ©e d'Art moderne Paris. She has worked with research consortiums thatinvolve academic, industry and arts collaborators. She is a foundingmember of the Microsoft Research Fellow Social Media Collective and anexpert consultant for the European Union Digital Futures Initiative. Herwork has been presented as part of the TEDx East conference, on NationalPublic Radio, and reviewed in The Guardian (UK) and Washington Postnewspapers.She works internationally with collaborators in Africa,Europe, and Asia. Her book Hello Avatar is published by the MIT Press andwas recently translated into Turkish.

Howard Goldkrand is an artist andinnovations director who works on transmedia design, immersiveengagement, and networked media strategy across industries. He is Head ofInnvation Design for the global digital media creative agency SapientNitro(http://www.sapient.com/en-us/sapientnitro.html). In his recent workhistory, GoldkrandÂ has been executive producer of a future ofstorytelling project for CondÃ© Nastâ€™s Ideactive. He wasInnovations Director and Cultural Engineer at Modernista! where he lead theteam for the Alternate Reality Game for the Dexter TV show (Showtime) forwhich he won a Webby award, best marketing piece at ComicCon, andnominated for an Emmy Award. He also led the work on TOMS with the launchof their eyewear product and continues to do innovation work for thecompany. From the perspective of strategy, creative, media, productionand innovations, he has worked with clients that include GM, TIAA-CREF,Palm, Napster, Food Should Taste Good, Product(RED),TOMS,Nickelodeon, HTC, NIKE, Starbucks, SCION, Samsung. He continues towork with Neverstop, a group out of Seattle founded by Alex Calderwood ofAce Hotel fame. As an artist, he began an experimental studio practice atWesleyan University, creating conceptual work that spanned sculpture andperformance. He is the codirector of SoundLab Cultural Alchemy, anexperimental electronic music and art platform. He has had a longinternational art career exhibiting at venues such as PS 1 MOMA, ChinatiFoundation, Marfa, Texas, Recollets, Paris, Art Museum of Vancouver,Castil de Rivoli, Turin Italy, and the WAAG Society Amsterdam. Goldkrandspeaks internationally at workshops, panels, and conferences on art andculture.

Adaptive transmission protocols for a random multiple accesschannel
2014-06-11 11:00 - 12:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
There are known two "ALOHA-type" models, (a) with a finitenumber of queues and with messages ahead of each queue being potentially"active", and (b) without queues and all "active" messages. I'll talkabout model (b), introduce a number of new protocols for their stability,and discuss some open problems.

Invited talk from the SC-4 A From Gossip to Voting
2014-06-06 14:00 - 14:45 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Short presentations of papers representative of PhDsâ€™research work
2014-06-06 11:30 - 12:15 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Passive Content Curation Based on HTTP Logs
2014-06-06 10:45 - 11:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

The Network is a Database
2014-06-06 10:45 - 11:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Talk from LINCS -4 (3 short talks on new covered topics) EnhancedCluster Computing Performance through Proportional Fairness
2014-06-06 10:45 - 11:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Invited talk from the SC-3 Overcoming the Challenges of NetworkTechnology Adoption
2014-06-06 09:30 - 10:15 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

An overview of recent results on network theory, with a focus ondense wireless network modeling and analysis
2014-06-05 17:30 - 18:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Industry Panel: Trends in ICT and the role of research
2014-06-05 16:30 - 17:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Israel Cidon â€“ Sookasa, Vania Conan â€“ Thales,Dohy Hong â€“ Samsung, Robert Plana â€“ Alstom, Krishan Subnaniâ€“ Alcatel-Lucent, Dirk Trossen - Interdigital, ClaireWaast-Richard â€“ EDF.

Lingering issues in distributed scheduling
2014-06-05 12:15 - 12:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

NDN for the support of advanced applications in vehicular Networks
2014-06-05 12:00 - 12:15 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Some Thoughts on Loc/ID Separation
2014-04-23 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Locator(Loc)/identifier(ID) Separation(LIS) was conceived tomitigate the explosion of the DFZ routing table. To be literally exact,every host would be given a Loc in addition to an ID. The talk asserts thatprovision of Locs in this fashion does not help combat the problem at all;it would only inherit the same fate with the current IP address.What wouldreally help would be use of two-tier Locs, with one set local to a siteand another globally relevant. That is to day, use of localaddressing(Loc) would be the only exit. Some LIS proposals like ILNP andLISP achieve this by their own tricky definition of Locs. The talk assertswhat they really implement is adoption of local addressing, rather thanLIS.In LISP, EID(endpoint ID) is also used for routing within a site,thus is semantically overloaded in the same way as IP address is. This alsoimplies semantic overloading isn't the real problem from the start, thusthere'd be no rationale for LIS. Semantic overloading (for bothidentification and location) of an address is rather an intrinsic nature ofnetworking. What people really need is local addressing.If time permits,the talk also would suggest use of ISIS to make the best use of EID inLISP.

Biography: DY is a professor of CNU(Chungnam National University)in South Corea, in the department of Information CommunicationsEngineering, since 1983. He got a bachelor degree from SNU(Seoul NationalUniversity) and a MS and a PhD degree, both from KAIST(Korea AdvancedInstitute of Science and Technology), before joining CNU. He's beenworking on various fields of networking, with recent focus on FutureInternet. He's also been active in standardization and REN(research andeducational networking) activities, and is current Chair of ISO/IEC JTC1/SC 6, where OSI once was made, and Chair of APAN(Asia-Pacific AdvancedNetwork), a non-profit consortium similar to Internet 2 (US) and Terena(EU).

Tandem Jackson Networks, Asymmetric Inclusion Processes andCatalan Numbers
2014-04-30 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
The Tandem Jackson Networkis a system of n sites (queues)inseries, where single particles (customers, jobs, packets, etc.) move,one by one anduni-directionally,from one site to the next until they leavethe system. (Think, for example, on aproduction line, or on a line in acafeteria).When each site is a M/M/1 queue, the Tandem Jackson Network isfamous for its product-form solution of the multi-dimensional ProbabilityGenerating Function of the site occupancies. In contrast, the AsymmetricInclusion Process (ASIP) is a series of n Markovian queues (sites), eachwith unbounded capacity, but with unlimited-size batch service. That is,when service is completed at site k, all particles present there movesimultaneously to sitek+1,and form a cluster with the particles present inthe latter site. We analyze the ASIP and show that its multi-dimensionalProbability Generating Function(PGF) does notposses a product-formsolution. We then present a method to calculate this PGF. We further showthat homogeneous systems are optimal and derive limit laws (when the numberof sites becomes large) for various variables (e.g. busy period, drainingtime, etc.). Considering the occupancies of the sites (queue sizes) weshow that occupation probabilities in the ASIP obey a discretetwo-dimensional boundary value problem. Solving this problem we findexplicit expressions for the probability that site k is occupied by mparticles (m=0,1,2,..).Catalan's numbersare shown to naturally arise inthe context of these occupation probabilities. This is a joint work withShlomiReuveni and Iddo Eiazar.

Invited talk from SC-1 Evaluating Mobility in Next-generationNetwork Architectures
2014-06-05 09:30 - 10:15 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Presentation of the LINCS
2014-06-05 09:00 - 09:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Workshop 2014

2014 LINCS Workshop
2014-06-05 08:45 - 2014-06-06 19:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Workshop LINCS - agenda 2014-2

Workshop
LINCS and itsScientific Committee
June 5th and 6th, 2014
LINCS - 23 avenuedâ€™Italie, 4th floor â€“ 75013 Paris

Agenda
June5th
Welcome 8:45 / 09:00

Presentation of the LINCS â€“ summary ofrecent achievements Prof. Daniel Kofman 9:00 / 09:30
Invited talk fromSC-1 Evaluating Mobility in Next-generation Network
Architectures, Prof.Jim Kurose, University of Massachusetts 9:30 / 10:15
Talk from LINCSâ€“ 1: An overview of recent results on Information-centric networkingwith a focus on traffic control and caching, Luca Muscariello/DiegoPerino/Dario Rossi 10:15 / 10:45

Coffee break 10:45 / 11:15

Invitedtalk from the SC-2 The Road for Enabling Consumer Cloud Services at theEnterprise - Prof. Israel Cidon, Technion 11:15 / 12:00
Talks from LINCSâ€“ 2 (2 short talks on new covered topics)
NDN for the support ofadvanced applications in vehicular Networks, Dr Giovanni Pau
Lingeringissuesin distributed scheduling, Florian Simatos 12:00 / 12:30

Lunch12:30 / 14:00

Poster Session by PhD students 14:00 / 16:00

Coffeebreak 16:00 / 16:30

Industry Panel: Trends in ICT and the role ofresearch
Israel Cidon â€“ Sookasa, Vania Conan â€“ Thales,Dohy Hong â€“ Samsung, Robert Plana â€“ Alstom, Krishan Sabnaniâ€“ Alcatel-Lucent, Dirk Trossen - Interdigital, ClaireWaast-Richard â€“ EDF. 16:30 / 17:30
Talk from LINCS -3
An overviewof recent results on network theory, with a focus on dense wirelessnetwork modeling and analysis - Marc Lelarge 17:30 / 18:00

Social Event(Diner) 19:30 / 22:00

June 6th
Welcome 09:00/09:30

Invited talk from the SC-3 Overcoming the Challenges of NetworkTechnology Adoption, Prof. Roch Guerin, Washington University Saint-Louis09:30 / 10:15

Coffee break 10:15 / 10:45

Talk from LINCS -4 (3 shorttalks on new covered topics)
Enhanced Cluster Computing Performancethrough Proportional Fairness, Jim Roberts
The Network is a Database,Jordan AugÃ©/Marc-Olivier Buob
Passive Content Curation Based on HTTPLogs, Zied Ben-Houidi 10:45 / 11:30
Talk from LINCS 5 â€“ AwardedPhD paper 11:30 / 12:00

Lunch 12:00 / 14:00

Invited talk from theSC-4 A From Gossip to Voting â€“ Prof. Patrick Thiran, EPFL 14:00 /14:45

Discussions:
- graduate studentsâ€™ experience at LINCS
-graduate studentsâ€™ exchange with the Scientific Committee 14:45 /15:15
Coffee break 15:15 / 15:45

In parallel:
- Meeting of theScientific Committee
- Poster session (to continue the discussion on theposters presented on June 5th) 16:00 / 17:30
The view of the ScientificCommittee 17:30 / 18:00

Conclusion and End of event 18:00 /18:15
Wrap-up
- Scientific Committee and Executive Committee 18:15 /19:15

Characterizing bufferbloat from end-hosts
2014-04-02 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
While, on routers and gateways, buffers on forwarding devicesare required to handle bursty Internet traffic, overly large or badlysized buffers can interact with TCP in undesirable ways. This phenomenon iswell understood and is often called bufferbloat. Although a number ofprevious studies have shown that buffering (particularly, in home) candelay packets by as much as a few seconds in the worst case, there is lessempirical evidence of tangible impacts on end-users. In this paper, wedevelop a modified algorithm that can detect bufferbloat at individualend-hosts based on passive observations of traffic. We then apply thisalgorithm on packet traces collected at 55 end- hosts, and acrossdifferent network environments. Our results show that 45 out of the 55users we study experience bufferbloat at least once, 40% of these usersexperience bufferbloat more than once per hour. In 90% of cases, bufferingmore than doubles RTTs, but RTTs during bufferbloat are rarely over onesecond. We also show that web and interactive applications, which areparticularly sensitive to delay, are the applications most often affectedby bufferbloat.

Gold mining in a River of Internet Content Traffic
2014-04-02 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
With the advent of Over-The-Top content providers(OTTs),Internet Service Providers (ISPs) saw their portfolio of services shrink tothe low margin role of data transporters. In order to counter this effect,some ISPs started to follow big OTTslike Facebook and Google in trying toturn their data into avaluable asset. In this paper, we explore thequestions of whatmeaningful information can be extracted from networkdata, andwhat interesting insights it can provide. To this end, wetacklethe first challenge of detecting user-URLs, i.e., those linksthatwere clicked by users as opposed to those objectsautomaticallydownloaded by browsers and applications. We devisealgorithmsto pinpoint such URLs, and validate them on manually collectedground truth traces. We then apply them on a three-day long traffic tracespanning more than 19,000 residential users that generated around 190million HTTP transactions. We find that only 1.6% of these observed URLswere actually clicked by users. As a first application for our methods, weanswer the questionof which platforms participate most in promoting theInternetcontent. Surprisingly, we find that, despite its notoriety, only11%of the user URL visits are coming from Google Search.

Making mobile access networks green: from research tostandardization
2014-03-26 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Energy efficiency in mobile networks is gaining in importancefrom both environmental and business points of view. In particular, sitesleep mode techniques are being introduced along with self organizingprocedures that enable a dynamic activation/deactivation of sites withoutcompromising Quality of Service (QoS). As the research is progressivelybroadening towards increased energy efficiency, green concepts are beingintroduced in standardization. For instance, 3GPP and ETSI are introducingenergy efficiency enablers within their mobile networks standards. Thistalk gives an overview on the latest theoretical advances in optimalcontrol for energy efficiency in mobile networks and the relatedstandardization activities.

Opportunistic Channel Selection by Cognitive Radios Under ImperfectObservations and Limited Memory: A Repeated Game Model
2014-03-20 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
To help mitigate the critical stress on spectrum resourcesspurred by the more powerful and the more capable smart devices, a recentpresidential advisory committee report and also a FCC report recommend theuse of spectrum sharing technologies. One such technology addressed inthese reports is cognitive radio (CR), in which a network entity is ableto adapt intelligently to the environment through observation, explorationand learning. In this talk, we discuss the problem of coexistence,competition andÂ fairness among autonomous cognitive Radios (CRs) inmultiple potentially available channels that may be non-homogeneous interms ofÂ primary user (PU) occupancy. Moreover, the real spectrumoccupancy data collected at RWTH Aachen confirms Â that the spectrumresources are in general non-homogeneous in terms of PU occupancy. Â Wepresent a model in which a CR that is able to adapt to the environmentthrough observation and exploration is limited in two ways. First, as inpractical CR networks, CRs have imperfect observations (such as due tosensing and channel errors) of their environment. Second, CRs haveimperfect memory due to limitations in computational capabilities. Forefficient opportunistic channel selection, we discuss efficient strategiesand utilize the framework of repeated games (with imperfect observationsand memory) to analyze their stability in the presence of selfishdeviations.

Quantun Information
2014-03-19 14:00 - 14:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Information is something encoded in physical systems'sproperties. Hence the study of information and computation is linked to theunderlying physical processes. Quantum Information is the study ofinformation encoded in the state of quantum system. Quantum phenomena suchas the superposition principle and entanglement give rise to a otherapproach and opportunities in all the sub-fields of Information Theory. Thegoal of this seminar, by giving some basic concepts of quantuminformation, is to give a very naive approach which will permit to theaudiance Â to have an overview of the Quantum Information field.

Network Fingerprinting: TTL-Based Router Signatures
2014-03-12 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Fingerprinting networking equipment has many potentialapplications and benefits in network management and security. Moregenerally, it is useful for the understanding of network structures andtheir behaviors. In this paper, we describe a simple fingerprintingmechanism based on the initial TTL values used by routers to reply tovarious probing messages. We show that main classes obtained using thissimple mechanism are meaningful to distinguish routers platforms. Besides,it comes at a very low additional cost compared to standardactive topologydiscovery measurements. As a proof of concept, we apply our method to gainmore insight on the behavior of MPLS routers and to, thus, moreaccurately quantify their visible/invisible deployment. This work has beenpublished in IMC 2013.

On the resiliency of the French Internet
2014-03-05 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
This presentation focuses on the resiliency of the FrenchInternet, studied from thepoint of view of network interconnectivity. Wedefine a model for representing theBGP-level topology of the Internet whichtakes into account the businessrelationships between ASes, and implementan algorithm to construct such a map from publicly available routinginformation.The portion of the Internet responsible for the connectivity ofFrench ASes is thenestablished, and the risk of disconnection is assessed.To this end, we identify asset of critical ASes whose suppression woulddisconnect other ASes from the Internet. Finally, we give some insight asto how the model could be expanded and thedifficulties this wouldintroduce. We also give an example of how a BGP-level map ofthe Internetcan be used to actively monitor the network.

Impact of the electronic architecture of optical slot switchingnodes on latency in ring networks
2014-02-26 14:30 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
An optical slot switching node network called POADM (packetoptical add-drop multiplexers) has formerly been proposed as a flexiblesolution for metropolitan ring networks to carry data traffic with asub-wavelength switching granularity and with a good energy efficiency,which is enabledby optical transparency. In this paper, for the first timewe propose several architectures for the electronic side of optical slotswitching nodes to increase flexibility through the addition of electronicswitches, working either at client packet granularity or at slotgranularity; such electronic switches can be located at eithertransmitter, receiver, or both sides of a node, thereby decreasingtraffic latency, at the expense of increased node cost and/or energyconsumption. This paper focuses on the latency aspect. We investigate theimpact of a timer that can be used to upper bound the slots insertion timeon the medium. We also propose, for the first time, a queuing model foroptical slot switching ring and assess and compare the latency of thesenode architectures analytically using queuing theory, and withsimulations.

Energy-Aware Computing with Application Processors
2014-02-26 14:00 - 14:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Energy aware computing is as ubiquitous as ubiquitous computingitself. The user experience and up-time of hand-held devices are affecteddirectly by the squander of battery resources. We will focus on embeddedsystems, e.g., smartphones, or tables, and highlight the most prominentsources of power consumption in application processors. The temperaturedependency of the power consumption is also discussed. This implies theimportance of thermal models for passively cooled devices, used by DVFScontrollers, process schedulers, and thermal management units. Passivelycooled devices show substantially different thermal behavior compared toactively cooled devices. Our latest developments on this topic are brieflypresented. Furthermore, common energy optimization techniques, bothsoftware and hardware based, are discussed. The referenced material coverspractical, industrial and academic solutions to the energy optimizationproblem.

On Recovering Causality Information from Time Series Data
2014-02-20 14:00 - 16:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Suppose we have N time series available where one time-seriescould be causally dependent on others. For example, such dependence can befound in economic data or weather data. The goal is to recover the directedcausality graph that links these time series. As is well known causalityand correlation are not the same and thus one of the important questions ishow to address this issue. There are several frameworks such as directedinformation, the notion of Granger causality, etc. However working withdirected information requires too much a priori knowledge about thestructure of the time series that is unavailable.

In this talk I willshow how the notion of Granger causality can be tied to Wiener filteringthat allows us to recover a directed random graph whose edges arerepresented by the innovations filters. This approach as well as thedirected information approach assuming Gaussianity however are not verypractical and so a pairwise approach is taken. This suffers from overestimation of directed edges of the causality graph. To address this issuewe show how it is possible to consider a sparse problem based on a mixed L1- H1 norm that leads to an approach for selecting edges characterized bycomplex polynomials. This results in a convex optimization problem. We showthat such an approach provides satisfactory results on synthetic examplesand uncovers interesting causal dependencies when used on real time seriesdata.

Joint work with S. Datta Gupta (University of Waterloo, Canada).

Optimal cache allocation for content-centric networking
2014-02-19 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Content-Centric Networking (CCN) is a promis-ing framework forevolving the current network architecture,advocating ubiquitous in-networkcaching to enhance contentdelivery. Consequently, in CCN, each router hasstorage spaceto cache frequently requested content. In this work, wefocuson the cache allocation problem: namely, how to distribute thecachecapacity across routers under a constrained total storage budget for thenetwork. We formulate this problem as a content placement problem andobtain the exact optimal solution by a two-step method. Throughsimulations, we use this algorithm to investigate the factors that affectthe optimal cache allocation in CCN, such as the network topology and thepopularity ofcontent. We find that a highly heterogeneous topology tendstoput most of the capacity over a few central nodes. On the otherhand,heterogeneous content popularity has the opposite effect, by spreadingcapacity across far more nodes. Using our findings, wemake observations onhow network operators could best deployCCN caches capacity

Be fair to flows: a fair network is attractive and trustworthy andfar more than just adequate
2014-02-05 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
The subject of active queue management is again highly topicalwith the recent creation of a new IETF working group. Regained interest hasarisen notably from the observed failings of traditional approaches tocongestion control in environments as diverse as the data centerinterconnect and the home network subject to "bufferbloat". In this contextit is opportune to remake the case for implementing per-flow fair queueingas the standard packet scheduling algorithm in router buffers. Though flowfairness as the basis of congestion control was proposed by Nagle as earlyas 1985 and feasibility was demonstrated at least 15 years ago in Bell Labswork on PacketStar, the networking research community has largely remainedfocused on designing new TCP versions and AQM algorithms as if the FIFObuffer were an unavoidable technological constraint. We show how per-flowfairness realizes implicit service differentiation and greatly facilitatesnetwork engineering with the notion of "fair networks" appearing as anatural parallel to that of "loss networks". Accounting for the stochasticnature of traffic, simple fairness is generally seen to be preferable
toweighted fairness or size-based priority scheduling while longest queuedrop is likely the only AQM required.

Biography: Jim Roberts veryrecently joined the French research institute IRT-SystemX to work on aproject on Cloud computing and network architecture. He was previously withInria from September 2009 after spending more than thirty years with FranceTelecom research labs. He received a degree in Mathematics from theUniversity of Surrey in 1970 and a doctorate in computer science in 1987from the University of Paris VI. His research is centered on theperformance evaluation and
design of traffic controls for communicationnetworks. In a long career, he has published around 100 papers, chairedseveral program committees and been associate editor for a number ofjournals. He gave the Keynote at Infocom 2013. He is a Fellow of theSociÃ©tÃ© des Ã©lectriciens et Ã©lectroniciens (SEE) and recipientof the Arne Jensen lifetime achievement award from the InternationalTeletraffic Congress (ITC).

Protecting Privacy While Providing Utility in Published NetworkMobility Traces Using Differential Privacy
2014-01-29 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Those who design, develop and deploy computer and networkedsystems, have a vital interest in how these systems perform in"real-world" scenarios. But real-world conditions and data sets are oftenhard to come by-companies treat scenario data as a confidential asset andpublic institutions are reluctant to release data for fear of compromisingindividual privacy. This challenge is particularly acute in mobile wirelessnetworks, where many have noted the need for realistic mobility andwireless network datasets. But assuring privacy is difficult. Severalwell-known examples have shown how anonymized data sets can be combinedwith other data to compromise individuals' personal privacy. The relativelyrecent model of differential privacy (DP) provides an alternate approach tomeasuring and controlling the disclosure of personal information, addingsufficient random "noise" (in a precisely quantifiable manner) to anyoutput computed from a sensitive collection of data, so that a precisestatistical privacy condition is met. In this talk we outline ongoingresearch to produce trajectory traces, and results derived from trajectorytraces, for public release from original "real-world" mobility traces(e.g., from our 802.11 campus network) while providing both well-defineddifferential privacy guarantees and demonstrably high accuracy when thesepublicly-released data sets are used for a number of common network andprotocol design and analysis tasks. We describe a DP technique using aconstrained trajectory-prefix representationof the original data, usingknown network topology and human mobility constraints, to determinetheunderlying representation of the original data and judiciously allocaterandom noise needed tosatisfy DP constraints. We will also discussalternative representations of mobility data that we conjecture willprovide better accuracy for specific analysis tasks, and discuss thetradeoff between generality/specificity and accuracy.This is a "workin-progress" talk, so ideas are still being "baked" andcomments/discussion are particularly welcome. This is joint research withGerome Miklau and Jennie Steshenko at the University of MassachusettsAmherst

Biography: Jim Kurose is a Distinguished Professor of ComputerScience at the University of Massachusetts Amherst. His research interestsinclude network protocols and architecture, network measurement, sensornetworks, multimedia communication, and modeling and performanceevaluation. He has served as Editor-in-Chief of the IEEE Transactions onCommunications and was the founding Editor-in-Chief of the IEEE/ACMTransactions on Networking. He has been active in the program committeesforIEEE Infocom, ACM SIGCOMM, ACM SIGMETRICS and ACM Internet Measurementconferences for a number of years, and has served as Technical ProgramCo-Chair for these conferences.He has received a number of research andteaching awards including the IEEE Infocom Award, the ACM Sigcomm Test ofTime Award and the IEEE Taylor Booth Education Medal. With Keith Ross, heis the co-author of the textbook, Computer Networking, a top downapproach (6th edition).He has been a visiting researcher at Technicolor'sParis Research Lab and at the LINCS (where is also a member of the LINCSScientific Advisory Board) in 2012.

COBRA: Lean Intra-domain Routing in NDN
2014-01-22 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Named Data Networking (NDN) is an emerging In-formation CentricNetworking architecture based on hierarchicalcontent names, in-networkcaching mechanisms, receiver-driven operations, and content-levelsecurity schema. NDN networkingprimitives and routing are based on contentnames and thereforeefficient content discovery of permanent as well astemporarilyavailable cached copies is a key problem to address. This paperex-amines current NDN approaches and proposes a fullydistributed,content-driven, bloom filter-based intra-domain routingalgorithm(COBRA), which outperforms previous solutions in this area.COBRAcreates routes based on paths used previously for contentretrieval, andmaintains routing information up-to-date with outthe need for extensivesignaling between nodes. We evaluate COBRA using simulation and compare itsperformance with other established routing strategies over the Europeanresearch network GEANT topology as an example of a ndnSIM core network. Ourresults illustrate that COBRA can significantly reduce overhead withrespect to flood-based routing while ensuring hit distancesof thesame
order as when using Dijkstra's algorithm.joint work with L.A.Grieco, G. Boggia, and K. Pentikousis, appering in the Procedings ofIEEE Consumer Communications & Networking Conf. (CCNC), 2014

Community detection in stochastic block models via spectral methods
2014-01-15 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Community detection consists in identification of groups ofsimilar items within a population. In the context of online socialnetworks, it isa useful primitive for recommending either contacts or newsitems tousers. We will consider a particular generative probabilistic modelforthe observations, namely the so-called stochastic block model,andgeneralizations thereof. We will describe spectral transformationsandassociated clustering schemes for partitioning objects intodistinctgroups. Exploiting results on the spectrum of random graphs, wewillestablish consistency of these approaches under suitableassumptions,namely presence of a sufficiently strong signal in theobserved data. Wewill also discuss open questions on phase transitions forclusterdetectability in such models when the signal becomes weak. Inparticularwe will introduce a novel spectral method which provably allowsdetectionof communities down to a critical threshold, thereby settling anopenconjecture of Decelle, Krzakala, Moore and ZdeborovÃ¡.

Presentation du PPP 5G
2014-01-08 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Brigitte CARDINAEL Head of Cooperative Research France TelecomOrange

Brigitte Cardinael graduated from INT in 1987. She joined MatraCommunication in 1987,where she was involved during 6 years in theresearch and development for GSM. Then she joined France Telecom Researchand Development (FTRD) in 1993 where she worked first on mobile satellitecomponent in context of IMT-2000. After France Telecom investment inGlobalstar she was the coordinator of Globalstar activities at FTR&Dfrom 1995 to 1999. Shejoined in 2002 the management team of the R&DDivision on Mobile Services and Radio Systems as Innovation and Strategymanager. She was also in charge from 2001 till 2005 of coordinating Beyond3G activities which includes France Telecom involvement in FP6 (Winner,E2R, Ambient Network, Daidalos, SPICE, MAGNET and 4MORE) and ininternational bodies (WWRF, SDRF, IEEE, 3GPP, IETF,...). She is sinceJanuary 2006 headof cooperative research at France Telecom R&D. Shehas been eMobility Vice Chairman in 2006 and 2007. She is chairing the ETNOR&D group and the eMobility Testing Facilities WG.

Combating Internet Attacks Via Infiltration
2013-12-11 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Far and away the most energetic driver of modern Internetattacks is the ability of attackers to financially profit from theirassaults. Many of these undertakings however require attackers to operateat a scale that necessitates interacting with unknown parties - renderingtheir activities vulnerable to *infiltration* by defenders. This talk willsketch research that has leveraged such infiltration to strikingeffect.

Vern Edward Paxson is a Professor of Computer Scienceat the University of California, Berkeley. He also works as an Internetresearcher based at the International Computer Science Institute inBerkeley, California. His interests range from transport protocols tointrusion detection and worms. He is an active member of the InternetEngineering Task Force (IETF) community and served as the chair of the IRTFfrom 2001 until 2005. From 1998 to 1999 he served on the IESG as TransportArea Director of the IETF.

In 2006 Paxson was inducted as a Fellow ofthe Association for Computing Machinery (ACM). The ACM's Special InterestGroup on Data Communications (SIGCOMM) gave Paxson its 2011 award, "forhis seminal contributions to the fields of Internet measurement andInternet security, and for distinguished leadership and service to theInternet community." The annual SIGCOMM Award recognizes lifetimecontribution to the field of communication networks.[1]

Paxson is alsothe original author of the flex lexical analyzer and the Bro intrusiondetection system. Backscatter is a term coined by Vern Paxson to describeInternet background noise resulting from a DDoS attack using multiplespoofed addresses

http://www.icir.org/vern/

Convergence Speed of Asymptotic Consensus Algorithms
2013-12-10 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Asymptotic consensus is a phenomenon observed in birdflocking, firefly synchronization, opinion spreading, or synchronizationof coupled oscillators. Algorithms that achieve asymptotic consensus areused in systems like sensor networks, dynamic load balancing protocols,robot formation protocols, or rendezvous in space.

These algorithmshave a simple form: At every step of the algorithm, each agent forms anaverage of values observed from neighboring agents. These algorithmsguarantee asymptotic consensus among agents even under very lightconditions on the (dynamic) communication topology and the weights used inthe calculation of the averages.

Equivalently, asymptotic consensus canbe seen as convergence of not necessarily reversible and not necessarilytime-homogeneous Markov chains to their limiting distributions.

Thistalk introduces asymptotic consensus and presents new upper bounds on itsconvergence speed, generalizing recent results by Cao et al., Oshevskyand Tsitsiklis, and Chazelle.

Understanding the Dynamic Behaviour of the Google Congestion
2013-12-04 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
This is a joint with G. Carlucci and S. Mascolo, and will bepresented at Packet Video Workshop, San Jose, CA, USA, December 2013.Real-time communication over the Internet is of ever increasing importancedue the diffusion of portable devices, such as smart phones or tablets,with enough processing capacity to support video conferencing applications.The RTC Webworking group has been established with the goal ofstandardizing a set of protocols for inter-operable real-time communicationamong Web browsers. In this paper we focus on the Google Congestion Control(GCC), recently proposed in such WG, which is based on a loss-basedalgorithm run at the sender and a delay-based algorithm executed at thereceiver. In a recent work we have shown that a TCP flow can starve a GCCflow. In this work we show that this issue is due to a threshold mechanismemployed by the delay-based controller. By carrying out an extensiveexperimental evaluation in a controlled testbed, we have found that, whenthe threshold is small, the delay-based algorithm prevails over theloss-based algorithm, which contains queuing delays and losses. However,a small threshold may lead to starvation of the GCC flow when sharing thebottleneck with a loss-based TCP flow.

Adaptive Internet Governance: Innovation in the Ecosystem
2013-11-27 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract: The years following the United Nation's World Summiton the
Information Society (WSIS) have seen much technological changerelated
to the Internet as well as significant innovation related tothe
discussion of Internet policy issues. Reporting on aninstitutional
innovation in the Internet governance ecosystem, theresearch to be
discussed examines the approximately eight-year-oldInternet
Governance Forum, highlights the growing roles of civilsociety
including academics and technical experts, and tracksespecially
recent tensions among ecosystem actors. It also highlightsthe
ecosystem's evolution and the roles of Multistakeholderism.Finally,
it analyzes recent developments and identifies futuredirections.
Biography: Nanette S. Levinson is Associate Professor ofInternational
Relations, School of International Service, AmericanUniversity and
Academic Director of the SIS- Sciences-Po Exchange. She isa past
Chair of the Global Internet Governance Academic Network (GigaNet)and
Editor of the International Communication Section in RobertDenemark,
Editor,The International Studies Compendium Project.Oxford:
Wiley-Blackwell. From 1988-2005 she served as Associate Dean ofthe
School of International Service.Recipient of awards includingthose
for outstanding teaching, program development, academicaffairs
administration, multicultural affairs and honors programming,she has
designed co-curricular collaborative learning opportunitiesincluding
the Freshman Service Experience and the Graduate PortalProgram.
Additionally, she has crafted and implemented research-basedtraining
programs for the private and public sectors. In 2011, theAshoka
Foundation presented her with an "Award for OutstandingContributions
to Social Entrepreneurship Education" and included herpeer-reviewed
syllabus in its list and publication of the top ten syllabiin the
field. Her research and teaching focus on knowledge transfer,culture,
and innovation in a range of settings includingcross-national
alliances; internet and global governance;cross-national, virtual
collaboration; and social entrepreneurship. Alsoincluded is work
centering on interorganizational learning andinstitutional change
with special focus on new media and technology policyissues in the
developing world. Prof. Levinson's writings appear onlineand in
journals ranging from Information Technologies andInternational
Development to International Studies Perspectives. Shereceived her
bachelor's, masters and doctoral degrees from HarvardUniversity.

Providing Incentives for Wireless Peer-to-Peer Networks
2013-11-27 11:00 - 12:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Wireless Peer-to-Peer (P2P) systems allow mobile users toobtain data
from nearby peers instead of the far away base station. It hasthe
benefits of reducing power consumption, increasing capacity, etc.An
important challenge for P2P networks is to incentivize usersto
contribute by sharing the data that others need. Due tothe
broadcasting nature of wireless transmissions, existing solutionsfor
wireline P2P networks cannot be applied. In this talk, we presenttwo
non-monetary protocols for wireless P2P networks. We assume thateach
mobile user aims to increase its download rate and to decreaseits
transmission rate. We propose a fully distributed protocolwhere
mobile users determine which one to transmit through randombackoff.
We derive a closed-form formulation for the Nash Equilibrium,and
propose a distributed mechanism under which strategies of mobileusers
converge to the Nash Equilibrium. Next, we consider systems wherea
centralized broker schedules transmissions for all mobile users.We
propose a scheduling policy for the broker, and demonstrate thatthe
policy is truthful in the sense that all mobile users maximizetheir
own utilities by reporting their true values to the broker.

Briefbiography:

I-Hong Hou received the B.S. in Electrical Engineering fromNational
Taiwan University in 2004, and his M.S. and Ph.D. in ComputerScience
from University of Illinois, Urbana-Champaign in 2008 and2011,
respectively. He is currently an Assistant Professor atthe
Department of Electrical and Computer Engineering of the TexasA&M
University. His research interests include wireless networks,wireless
sensor networks, real-time systems, distributed systems, andvehicular
ad hoc networks. URL: http://cesg.tamu.edu/faculty/ihong-hou/

Feature Selection for Neuro-Dynamic Programming
2013-11-26 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Neuro-Dynamic ProgrammingÂ encompasses techniques from bothreinforcement learning and approximateÂ dynamic programming. Featureselection refers to the choice of basis that defines the function classthat isÂ required in the application of these techniques. This talkreviews two popular approaches to neuro-dynamicÂ programming,TD-learning and Q-learning. The main goal of this work is to demonstratehow insight fromÂ idealized models can be used as a guide for featureselection for these algorithms. Several approaches areÂ surveyed,including fluid and diffusion models, and the application of idealizedmodels arising from mean-fieldÂ game approximations. The theory isillustrated with several examples.

Reliable and Scalable Account Correlation Across Large SocialNetworks
2013-11-13 14:00 - 14:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
There is lot of interest and concern, both in research andindustry, about the potential for correlating user accountsacross
multiple online social networking sites. In this paper, we focuson the challenge of designing account correlation schemes thatachieve
high reliability, i.e., low error rates, in matching accounts,even when applied in large-scale networks with hundreds of millions ofuser
accounts. We begin by identifying four important properties Ã¢Availability, Consistency, non-Impersonability, andDiscriminability
(ACID) Ã¢ that features used for matching accounts needto satisfy inorder to achieve reliable and scalable account correlation.Even
though public attributes like name, location, profile photo, andfriends do not satisfy all the ACID properties, we show how itis
possible to leverage multiple attributes to build SCALABLE- LINKER, areliable and scalable account correlator. We evaluate the performance
ofSCALABLE-LINKER in correlating accounts from Twitter and Facebook, two ofthe largest real-world social networks. Our tests using ground
truth dataabout correlated accounts, show that while SCALABLE-LINKER can correlateas high as 89% of accounts (true positive rate) with
less than 1% falsepositive rate, when evaluated over small thousand node subsets of Facebookaccounts, the true positive rate drops to 21%
(keeping the 1% falsepositive rate), when the evaluation scale to include all the more thanbillion Facebook accounts. Our findings
reflect the potential as well asthe limits of reliably correlating accounts at scale using only publicattributes of accounts.

Détecteurs de défaillances
2013-11-06 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Les détecteurs de défaillances ont été introduit parChandra et Toueg en 1996 et ont été l'objet d'une recherche active depuiscette date. On présentera les détecteurs de défaillances, les notionsde réduction et de plus faible détecteur de défaillances pour résoudreun problème en présence de panne. On fera ensuite un état de l'art surles résultats obtenus ainsi que sur les implémentations des détecteursde défaillances.

Adaptive traffic light control using a wireless sensor network
2013-10-23 14:00 - 14:30 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
We consider the problem of controlling traffic lights inan
urban environment composed of multiple adjacent intersections byusing
an intelligent transportation system to reduce congestion anddelays.
Traditionally, each intersection is managed statically: the orderand
durations of the green lights are pre-determined and do notadapt
dynamically to the traffic conditions. Detectors are sometimes usedto
count vehicles on each lane of an intersection but the datathey
report is generally used only to select between a few staticsequences
and timings setups. Here, we detail and study TAPIOCA, adistribuTed
and AdaPtIve intersectiOns Control Algorithm that decides of atraffic
light schedule. After a review of relevant related works, wefirst
expose and evaluate the TAPIOCA algorithm, using the SUMOsimulator
and the TAPAS Cologne dataset. We then study the use of ahierarchical
wireless sensor network deployed at intersections and theconsequences
of losses and delays it induces on TAPIOCA. Last but notleast, we
propose a prediction mechanism that alleviates these issues andshow,
using co-simulation between SUMO and OMNeT++, that suchinterpolation
mechanisms are effectively able to replace missing oroutdated data.
Biography: Sébastien Faye obtained a master degree incomputer
science from the university of Picardie Jules Verne (Amiens,France)
in 2011. He is currently a PhD student at the Computer Scienceand
Networking Department (INFRES) of Telecom ParisTech (Paris,France).
His research interests include Intelligent Transportation Systemsand
sensor networks.

Randomized Load Balancing in Large Processor Sharing Systems
2013-10-15 11:30 - 12:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Processor sharing models occur in a wide variety of situations.They are good models forbandwidth sharing as well as being solutions to NUMfor logarithmic utilities. In addition theypossess the desirable stochasticproperty of the stationary distribution being insensitive to the servicetime distribution. In this talk I will discuss new advances inunderstanding and characterizingthe behavior of randomized routing to PSservers that are heterogeneous in terms of their servercapacities.Inparticular, starting with the identical server case we will rst discussthe so-called Power-of-two rule where by a combination of routing to theleast occupied server amongst two randomlychosen servers results in a verylow server occupancy and a so-called propagation of chaos orasymptoticindependence. Using these insights we analyze the case of heterogeneousservers wherethe server capacity can be one of M. We provide a completecharacterization of the stationarydistribution and prove that the limitingsystem is insensitive. We then consider a modied criterionbased on routingto the server with lower Lagrange costs. We compare these dynamicroutingstrategies with an optimal static state independent scheme. We showthat the dynamic schemesare much better in terms of average delay with theLagrange cost based being the best.The techniques are based on a mean eldanalysis and an ansatz based on propagation of chaos.Joint work with ArpanMukhopadhyay (Waterloo).

Locator/ID split: Analysis of the caching system
2013-10-09 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract: Locator/Identifier splitting is a paradigm proposedto helpInternet scalability. At the same time, the separation of thelocatorand the identifier name spaces allows for a more flexible managementof traffic engineering, mobility and multi.homing. A mapping system isrequire for the binding of locators and identifiers. This mapping is helpedby the use of a cache where ongoing associations are kept. The managementand dimensioning of this cache is a critical aspect of this newarchitecture for its future deployment. We present a model for the cachingsystem and and evaluation of its behaviour using real traffic traces.Thetalk will present the recent research work on LOC/ID splittingarchitectures.

Violation of interdomain routing assumptions
2013-09-18 14:00 - 15:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We challenge a set of common assumptions that are frequentlyused tomodel interdomain routing in the Internet. We draw assumptions fromthescientific literature and confront them with routing decisions thatareactually taken by ASes, as seen in BGP feeds. We show that theassumptions aretoo simple to model real-world Internet routing policies. Wealso show thatASes frequently route in ways that are inconsistent withsimple economicmodels of AS relationships. Our results should introduce anote of cautioninto future work that makes these assumptions and shouldprompt attempts tofind more accurate models.

Tolerating Byzantine failures in sparse networks
2013-09-18 14:00 - 15:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
As network grow larger and larger, they become more likely tofail locally. Indeed, the nodes may be subject to attacks, failures,memory corruption... In order to encompass all possible types of failures,we consider the more general model of failure: the Byzantine model, wherethe failing nodes have an arbitrary malicious behavior. In other words,tolerating Byzantine nodes implies to ensure that there exists no strategy(however unlikely it may be) for the Byzantine nodes to destabilize thenetwork.We thus consider the probleme of reliably broadcasting a message ina multihop network that is subject to Byzantine failures. Solutions exist,but require a highly-connected network. In this talk, we present ourrecent solutions for Byzantine-resilient broadcast in sparse networks,where each node has a very limited number of neighbors. A typical exampleis the grid, where each node has at most 4 neighbors. We thus show thetradeo-ff between connectivity and reliability.

Locator/ID split: Analysis of the caching system
2013-09-04 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Locator/Identifier splitting is a paradigm proposed to helpInternet scalability. At the same time, the separation of the locator andthe identifier name spaces allows for a more flexible management of trafficengineering, mobility and multi.homing. A mapping system is require forthe binding of locators and identifiers. This mapping is helped by the useof a cache where ongoing associations are kept. The management anddimensioning of this cache is a critical aspect of this new architecturefor its future deployment. We present a model for the caching system andand evaluation of its behaviour using real traffic traces. The talk willpresent the recent research work on
LOC/ID splitting architectures.

Peeking Behind the NAT: An Empirical Study of Home Networks
2013-08-28 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We present the first empirical study of home networkavailability, infrastructure, and usage, using data collected fromhome networks around the world. In each home, we de- ploy a routerwith custom firmware to collect information about the availability ofhome broadband network connectivity, the homenetwork infrastructure (including the wireless connectivity in each homenetwork and the number of devices connected to the network), and howpeople in each home network use the network. Outages are more frequentand longer in developing countries sometimes due to the network, and inother cases because they simply turn their home router off. We also findthat some portions of the wire- less spectrum are extremelycrowded, that diurnal patterns are more pronounced during the week, andthat most traffic in home networks is exchanged over a few connectionsto a small number of domains. Our study is both a preliminaryview into many home networks and an illustration of how measurements froma home router can yield significant information about homenetworks.
This is joint work with Mi Seon Park, Srikanth Sundaresan,Sam Burnett, Hyojoon Kim, Nick Feamster. It will appear at IMC2013.

POMDP Approach for Pilot Allocation and Receive Antenna Selection
2013-07-17 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
This talk considers antenna selection (AS) at a receiverequipped with multiple antenna elements but only a single radio frequencychain for packet reception. As information about the channel state isacquired using training symbols (pilots), the receiver makes its ASdecisions based on noisy channel estimates. Additional information thatcan be exploited for AS includes the time-correlation of the wirelesschannel and the results of the link-layer error checks upon receiving thedata packets. In this scenario, the task of the receiver is tosequentially select (a) the pilot symbol allocation, i.e., how todistribute the available pilot symbols among the antenna elements,for channel estimation on each of the receive antennas; and (b) theantenna to be
used for data packet reception. The goal is to maximize theexpected throughput, based on the past history of allocation andselection decisions, and the corresponding noisy channel estimates anderror check results. Since the channel state is only partially observedthrough the noisy pilots and the error checks, the joint problem of pilotallocation and AS is modeled as a partially observed Markov decisionprocess (POMDP). The solution to the POMDP yields the policy thatmaximizes the long-term expected throughput. Using the Finite State MarkovChain (FSMC) model for the wireless channel, the performance of the POMDPsolution is compared with that of other existing schemes, and it isillustrated through numerical evaluation that the POMDP solutionsignificantly outperforms them.

Toward an Enhanced Internet Architecture: the Locator/IdentifierSeparation Protocol (LISP)
2013-07-10 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
The Locator/ID Separation Protocol (LISP), proposed byCiscoand currently under standardization at the IETF (Internet EngineeringTask Force), is an instantiation of the paradigm separating locators andidentifiers. LISP improves Internetu2019s scalability, also providingadditional benefits (e.g., support for multi- homing, trafficengineering, mobility, etc.) and having good incremental deployabilityproperties. The talk will overview the principles of LISP, its use incontext different from Internet scalability, and some of the ongoing workin Telecom ParisTech.

Point-Map Palm Measures
2013-07-04 11:00 - 12:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
In this talk, we speak about a framework for studyingpoint-map invariant measures. A compatible point-map on the set of countingmeasures is a mapping on discrete multi-subsets of Rd: to each point of thediscrete set, it associates another point of the same set, carrying themultiplicity; compatibility means that the image of a point depends onlyon the support of the counting measure (the counting measure after removingthe multiplicities) "seen from" (i.e. shifted to) this point.
It is a wellknown fact in the literature that whenever a compatible point-map isbijective on all simple counting measures, the Palm version of anystationary simple point process is left invariant by the action of such acompatible and bijective point-map.
We focus on the case of a notnecessarily bijective point-map f. Its goal is to associate, to anystationary point process , a companion point process with an almost suremass at zero and with a law which is invariant under the action of f. Weintroduce the notion of Point-map Palm (or here f-Palm) version of thepoint process , which satises the desired invariance property when itexists and we give sucient conditions for it to exist.

Joint work withF. Baccelli.

Optimizing QoS in Wireless Sensor Networks Using a Caching Platform
2013-07-03 14:30 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
This paper addresses monitoring and surveillanceapplications using Wireless Sensors Networks (WSN). In thiscontext, several remote clients are interested in receivingthe information collected by the nodes in a WSN. As WSN devicesare most of the time constrained in energy and processing, wepresent a caching architecture that will helpreducing unnecessary communications and adapting the network toapplication needs.Our aim here is to cache information in order toimprove the overall network lifetime, while meetingequirements of external application in terms informationfreshness. We first describe and evaluate the performance ofour caching system within the framework of a ConstrainedApplication Protocol (CoAP) proxy. We then extend this work byshowing how the cache could be enriched and exploitedwith cross-layer data. Based on information from routingpackets and estimation updates of nodes power consumption, wederive an optimization strategy which allows to meet requirements onthe freshness of the cached values.

Efficient IP-level network topology capture
2013-07-03 14:00 - 14:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Large-scale distributed traceroute-based measurementsystems are used to obtain the topology of the Internet at theIP-level and can be used to monitor and understand the behaviour ofthe network. However, existing approaches to measuring thepublic IPv4 network space often require several days to obtain a fullgraph, which is too slow to capture much of the network's dynamics.This paper presents a new network topology capture algorithm, NTC,which aims to better capture network dynamics through acceleratedprobing, reducing the probing load while maintaining good coverage.There are two novel aspects to our approach: it focuses on obtainingthe network graph rather than a full set of individual traces, andit uses past probing results in a new, adaptive, way to guidefuture probing. We study the performance of our algorithm on realtraces and demonstrate outstanding improved performance compared toexisting work. More info at http://ntc.top-hat.info/index.html.

Nash equilibrium structure of a class of blocking games arising innetwork security
2013-06-19 11:00 - 12:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We study a game-theoretic model for security/availabilityin a networking context. To perform some desired task, a defender needsto choose a subset from a set of resources. To perturb the task,an attacker picks a resource to attack.We model this scenario asa 2-player game and are interested in describing its set ofNash equilibrium. The games we study have a particular structure, forwhich we can use the theory of blocking pairs of polyhedral, pioneeredby Fulkerson, to arrive a reasonably satisfactory understanding of theNash equilibrium. The subsets of resources that support Nashequilibrium strategies of the attacker,called "vulnerability sets", areof particular interest, and we identify them in several specific gamesof this type. An example of a game of this sort is when the set ofresources is the set of edges of a connected graph,the defender choosesas its subset the edges of a spanning tree,and the attacker chooses anedge to attack with the aim of breaking the spanning tree.
(joint workwith Assane Gueye, Aron Laszka, and Jean Walrand)

Traffic redundancy elimination for cellular systems and clouds
2013-06-13 11:15 - 12:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

On the integration of name-based functionality in high-speednetwork equipment
2013-06-13 10:30 - 11:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Integer programming models for transmission scheduling in wirelessnetworks
2013-06-12 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
In the presentation, we will discuss exactinteger programming models for transmission scheduling in wirelessnetworks based on the notion of compatible set. A compatible set isdefined as a subset of radio links that can transmit simultaneouslywith acceptable interference. The issue is to find a set of compatiblesets that, when properly interlaced in the transmission slots, willmaximize a traffic objective. We will present integer programmingformulations of the underlying optimization problem and discusstheir computational effectiveness.

Biography: Michal Pioro is aprofessor and Head of the Computer Networks and Switching Division at theInstitute of Telecommunications, Warsaw University of Technology,Poland. At the same time he is a professor at Lund University, Sweden.He received a Ph.D. degree in telecommunications in 1979, and aD.Sc. degree (habilitation) in 1990, both from the Warsaw Universityof Technology. In 2002 he received a Polish State Professorship.His research interests concentrate on modeling, optimizationand performance evaluation of telecommunication networks and systems. Heis an author of four books and more than 150 technical papers presentedin the telecommunication journals and conference proceedings. He hasled many research projects for telecom industry in the fieldof network modeling, design, and performance analysis. He is deeplyinvolved in international research projects including the FP7, Celticand COST projects.

From Gossip to Distributed Optimization (and back again)
2013-06-04 11:00 - 12:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Consensus in a network is a fundamental, thoroughly,studied problem. It is well known that the main obstacles to it areunreliability and asynchronism as stated by the celebrated "FLPimpossibility result". However under smoother assumptions, several worksin the past decade have shown that consensus can be reached using verysimple algorithms known as Gossip. Interestingly enough, these gossipalgorithms turned out essential in the more complex setting of distributedoptimization wherethe sought consensus has to solve an optimizationproblem.

The first part of this talk will introduce the mainconcepts and tools: distributed algorithms, gossip, distributedoptimization. In a second part of the talk, I will discuss how to rely ondistributed optimization to build more robust gossip schemes.

SMOOTH: A Simple and Realistic Way to Model Human Mobility
2013-05-22 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Simulation is the research tool of choice for a majority of themobile ad hoc network (MANET) community; however, while the use ofsimulation has increased, the credibility of the simulation results asdecreased. Since mobility patterns can significantly affect the performanceof a protocol, choosing a realistic mobility model is one
importantaspect to consider in the development of a credible MANET simulationscenario.In addition to being realistic, a mobility model should be easyto understand and use. Unfortunately, most of the simple mobility modelsproposed thus far are not realistic and most of the realistic mobilitymodels proposed thus far are not simple to use. In this seminar, I willpresent SMOOTH, a new mobility model that is realistic (e.g., SMOOTH isbased on several known features of human movement) and is simple to use(e.g., SMOOTH does not have any complex input parameters). In addition topresenting SMOOTH, I will show results that validate SMOOTH imitates humanmovement patterns present in real mobility traces collected from a range ofdiverse scenarios and I will compare SMOOTH with other mobility models thathave been
developed on similar mobility traces. Lastly, I will discusstools that my group has created to aid the development of more rigoroussimulation studies. While this work focuses on the MANET field, thetakeaway message in regards to credible simulation is applicable to othercomputing fields.
Biography: Tracy Camp is a Full Professor of ComputerScience in the Department of Electrical Engineering and Computer Science atthe Colorado School of Mines. She is the Founder and Director of theToilers ([23]http://toilers.mines.edu), an active ad hoc networks researchgroup. Her current research interests include the credibility
of ad hocnetwork simulation studies and the use of wireless sensor networks ingeosystems. Dr. Camp has received over 20 grants from the National ScienceFoundation, including a prestigious NSF CAREER award. In total, herprojects have received over $20 million dollars in external funding. Thisfunding has produced 12 software packages that have been requested from(and shared with) more than 3000 researchers in 86 countries (as of October2012). Dr. Camp has published over
80 refereed articles and 12 invitedarticles, and these articles have been cited almost 4,000 times (perMicrosoft Academic Search) and over 7,000 times (per Google Scholar) as ofDecember 2012.Dr. Camp is an ACM Fellow, an ACM Distinguished Lecturer,and an IEEE Senior Member. She has enjoyed being a Fulbright Scholar in NewZealand (in 2006), a Distinguished Visitor at the University of Bonn inGermany (in 2010), and a keynote presenter at several venues, e.g., atthe 7th International Conference on Intelligent Sensors, Sensor Networksand Information Processing (ISSNIP 2011) in Adelaide, Australia, and the3rd International Conference on Simulation Tools and Techniques (SIMUTools2010) in Malaga, Spain. In December 2007, Dr. Camp received the Board ofTrustees Outstanding Faculty Award at the Colorado School of Mines; thisaward was only given five times between 1998-2007. She shares her life withMax (born in 2000), Emma (born in 2003), her husband (Glen), and threepets (two cats and a dog). The four humans are vegetarians who tremendouslyenjoy living in the foothills of the Rockies.

Design of a Survivable VPN Topology over a Service Provider Network
2013-05-14 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Survivability in IP-over-WDM networks has already beenextensively discussed in a series of studies. Up to date,most of thestudies assume single-hop working routing of trafficrequests. In thispaper, we study the multi layer survivable designof a virtual topology inthe context of multiple-hop workingrouting for IP layer traffic requests.The design problem iscomposed of two problems which are simultaneouslysolved:( i ) Finding the most efficient or economical multi-hop routingofthe IP traffic flows with different bandwidth granularitiesover the virtualtopology, which involves some traffic grooming,( ii ) Ensuring that thevirtual topology is survivable throughout an appropriate mapping of thevirtual links over the physicaltopology, if such a mapping exists.In orderto solve such a complex multi layer resilient networkdesign problem, wepropose a column generation ILP model. Itallows exploiting the naturaldecomposition of the problem andhelps devising a scalable solutionscheme.We conducted numerical experiments on a German networkwith 50 nodesand 88 physical links. Not only we could solve muchlarger data instancesthan those published in the literature, butalso observe than multi-hoprouting allows a saving of up to 10%of the number of lightpaths, dependingon the traffic load.

CLIPS: Infrastructure-free Collaborative Indoor Positioning Scheme
2013-05-03 10:30 - 11:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Indoor localization has attracted muchÂ attentionrecentlydueÂ to its potential for realizingindoorÂ location-awareapplicationÂ services. This talk considersaÂ time-criticalscenario with a team ofÂ soldiers or firstrespondersÂ conductingemergency mission operations inÂ a large buildinginÂ whichinfrastructure-based localization is notÂ feasible (e.g.,dueÂ tomanagement/installation costs, power outage,Â terroristattacks). In thisÂ talk, I will present a collaborative
indoorpositioning scheme called CLIPSÂ that requires nopreexistingÂ indoorinfrastructure. Assuming that each userÂ has areceivedÂ signalstrength map for the area in reference, anapplicationÂ canÂ compare and select a set of feasible positions,whentheÂ deviceÂ receives actual signal strength values at runtime.Then,Â deadÂ reckoning is performed to removeinvalidcandidateÂ coordinatesÂ eventually leaving only the correctonewhich can be shared
amongst theÂ team. The evaluation resultsfrom anAndroid-based testbed showÂ thatÂ CLIPS converges toan accurate set ofcoordinates much faster
thanÂ existing non-collaborativeschemes (morethan 50% improvementÂ underÂ theconsideredscenarios).

Biography: Dr. Uichin Lee is anassistantÂ professor in the DepartmentÂ of Knowledge ServiceEngineering at KAIST, Korea.Â He received hisÂ Ph.D. degree inComputer Science from UCLA in 2008. BeforeÂ joiningÂ KAIST, he workedfor Alcatel-Lucent Bell Labs at Holmdel as aÂ member
of technical staff.His research interests includeÂ mobile/pervasiveÂ computing and socialcomputing systems.

Control of the grid in 2020, and how economics can help us
2013-04-30 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
In this talkÂ we survey control issues in the grid, andhowÂ the introduction of renewablesÂ brings new and interestingcontrolÂ problems. We also explain the need forÂ economic theory toguide theÂ formulation of contracts for resources neededÂ for reliablereal-timeÂ control. Control of the grid takes place onmanyÂ time-scales, and isÂ analogous to many other control problems,such asÂ confronted inÂ aviation. There is decision making on timesscales of days, weeks, orÂ months; much like the planning that takesplace for ticket sales for aÂ commercial airline. Hourly decision makingof energy supplyÂ is
analogous to the chatter between pilot and airtraffic controllerÂ toÂ re-adjust a route in response to an approachingthunderstorm.Â Then,Â there is regulation of the grid on time-scalesof seconds toÂ minutes;Â consider the second-by-second movement of theailerons on the wingsÂ ofÂ an airplane, in response to disturbancesfrom wind and rain hittingÂ theÂ moving plane. There are also transientcontrol problems: TheÂ recovery of theÂ grid following one generatoroutage is much like theÂ take-off or landing ofÂ an airplane. It isimportant to keep theseÂ analogies in mind so that we canÂ have aninformed discussion about howÂ to manage the volatility introducedtoÂ the grid through renewableÂ energy sources such as wind and solar.The new
control problems in theÂ grid will be solved by engineers, aswe have solvedÂ many similarÂ control problems.

Biography: Sean Meynreceived the B.A.Â degree in mathematics from theÂ University ofCalifornia, Los Angeles (UCLA),Â in 1982 and the Ph.D.Â degree inelectrical engineering from McGillÂ University, Canada, inÂ 1987(with Prof. P. Caines, McGill University). He isÂ now ProfessorÂ andRobert C. Pittman Eminent Scholar Chair in theDepartmentÂ ofÂ Electrical and Computer Engineering at the Universityof Florida, andÂ director of the Laboratory for Cognition &Control. HisÂ researchÂ interests include stochastic processes,optimization, andÂ informationÂ theory, with applications to powersystems.

Real-time Monitoring of Physical Phenomena and their Dynamics withQuality Guarantees via Wireless Sensor Networks
2013-04-24 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Wireless sensor networks (WSN) are a powerful type ofinstrument with thepotential of remotely observing the physical world athigh resolution and scale.However,
to be an efficacious tool WSNmonitoring systems must provideguarantees on the quality of theobservations and mechanisms for real-timedata analysis. These problems aremade challenging by the WSN limited resourcesand the high volume of sensordata. In this talk I will address both challenges and illustrate twomonitoring solutions, which are built on top of statistical modelsandoffer dynamic trade-offs between resource efficiency and quality ofservice.More precisely, I will present an energy-efficient system, calledSAF, for answeringon-line queries with quality guarantees, detecting atreal-time anomalies, and clustering similar nodes. The system relies on aclass of simple time series models built at sensors, which are cheap tolearn and dynamically adapt to variations in thedata distribution toaccurately predict sensor values and improve resource utilization.SAF alsoprovides an integrated fault detection system and a hierarchical scheme toimprove scalability in case of large-scale WSN.SAF limited capabilities toface complex dynamics and data instability are overcome by the SmartEnvreal-time monitoring system. It remarkably improves SAF and previousworkfor providing probabilistic guarantees on the service quality even in caseof sensormalfunctioning, data instability and temporal communicationdisruption, and for automatically analyzing sensor data (e.g., trends,temporal-spatial correlations). SmartEnv is also ableto analyze anomalies,thus distinguishing between sensor malfunctioning and unexpectedvariationsin the phenomenon.I will conclude my talk with an outline of some SmartEnvapplications and
future work,particularly in the context of smartcities/grids.

Biography: Daniela Tulone holds a Ph.D. in ComputerScience from University of Pisajointly with MIT, a M.S. in ComputerScience from NYU, and a B.S. and M.S. degree in Mathematics fromUniversity of Catania. She has worked in academia and researchlabs(e.g.,Bell-Labs,MIT, AT&T Labs, NYU, University of Pisa,C.N.R.), in R&D
industry,and recently at the Joint Research Centerof the European Commission.Her interests include wireless sensor networks,algorithms, secure distributed systems, thedesign of dynamic trade-offs,smart grids, data analysis, and whatever involves a blendof theory andapplications

A Benes Packet Network
2013-04-23 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Benes networks are constructed with simple switch modules andhave many advantages, including small latency and requiring only analmost linear number of switch modules. As circuit-switches,Benes networks are rearrangeably non-blocking, which implies that theyare full-throughput as packet switches, with suitable routing. Routingin Benes networks can be done by time-sharing permutations. However,this approach requires centralized control of the switchmodules and statistical knowledge of the traffic arrivals. Wepropose a backpressure-based routing scheme for Benes networks,combined with end-to-end congestion control. This approach achievesthe maximal utility of the network and requires only four queuesper module,
independently of the size of the network.
Biography: LongboHuang is currently an assistant professor in the Institute forInterdisciplinary Information Sciences (IIIS) at Tsinghua University,Beijing, China. He received his Ph. D. degree from the ElectricalEngineering department at the University of Southern California in August2011, and worked as a postdoctoral researcher in the ElectricalEngineering and Computer Sciences department at the University ofCalifornia at Berkeley from July 2011 to August 2012. He was also avisiting professor at the Institute of Network Coding at the ChineseUniversity of Hong Kong from December
2012 to February 2013. Prior to hisPh.D., Longbo received his B.E. degree from Sun Yat-sen (Zhongshan)University, Guangzhou, China, and his M.S. degree from ColumbiaUniversity, New York City, both in EE. His research interests are inthe areas of Stochastic Network Optimization, Data Center Networking,Smart Grid, Processing Networks and Queueing Theory.

Controlling Electric Loads to Manage Energy Imbalances in Power
2013-04-17 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Increasing the share of energy produced by wind turbines,solar photovoltaics, and solar thermal power plants helps society addressmany key energy challenges including climate change, environmentaldegradation, and energy security. However, these renewable energyresources present new challenges, notably that their
power production isintermittent u2013 they produce when the wind is blowing and the sun isshining, not necessarily when we need it.

In this talk, I willdescribe how distributed flexible resources such as commercial buildings,residential electric loads, and distributed storage units can support highpenetrations of intermittent renewables and provide other services thatmake the grid run more efficiently and make power less expensive. As anexample, I will show how one can use Markov models and linear/nonlinearfiltering techniques to centrally control aggregations of air conditionersto provide power system services with high accuracy, but low requirementsfor sensing and communications. Importantly, the approach ensures thatcontrol actions are non-disruptive to the consumer. I find that, dependingon the performance required, loads may not need to provide stateinformation to the central controller in real time or at all, which keepsinstallation and operation costs low. Additionally, I will discuss anumber of practical issues including estimates of the resource size andrevenue potential. Finally, I will describe several new researchdirections including modeling load aggregations as uncertain reserves forday-ahead power system planning and real-time security.

Biography:Johanna Mathieu is a postdoctoral researcher in the Power SystemsLaboratory at ETH Zurich,Switzerland. In May 2012 she received her PhD inmechanical engineering from the University of California at Berkeley. Shehas a BS from MIT in ocean engineering and an MS from UC Berkeley inmechanical engineering.

NDN Reaching 3: Results and Challenges -- A Personal Perspective
2013-04-15 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
In this talk I plan to do a quick walk-through for partof the works we have done over the last 2.5 years. Morespecifically I will discuss what we have learned in packet forwardingarea and a new perspective on the relation between routing and forwardingplanes (or control and data planes, as they are called today). Iwill also describe a few new applications we have developed over NDN andwhat we have learned in the process.

Robust Mobile Wireless Networking
2013-04-10 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Cellular wireless networks are expanded to support ultra highspeed multimedia applications and incorporate the use of next generationenergy efficient micro base stations in supporting much higher density ofmobile stations. The operations of neighborhood base station nodes arecoordinated in a cross-layer manner to mitigate interference, adapt totraffic rate fluctuations and autonomously react to failure events. Inturn, mobile ad hoc networking mechanisms are investigated for multitudeof applications, when the involved networking systems do not make use ofa permanent
backbone infrastructure. Hybrid architectures include systemsthat require dynamically adaptive multi hop access to backbone systems,and such
that demand resilient access and rapid adaptationsto communications system degradations. Applications are planned forhybrid systems that
include vehicular networks that combine the use ofmulti hop ad hoc routing techniques, WiFi, cellular wireless accesstechnologies, and cloud computing architectures. We will review ourrecent research developments and studies of such network systems,selecting from the following topics:

1. For cellular wireless networks: adaptive rate/power scheduling for multicasting and unicasting;micro base station aided resilient failover.; heterogeneous operationsunder the use of micro and macro base station layouts; designof resilient public safety network systems.

2. Vehicular ad hocnetworks (VANETs): Location aware multicast packet distributions tohighway vehicles using inter-vehicular wireless networkingprotocols.

3. Mobile ad hoc networks: mobile backbone networking(MBN).

Biography:

Izhak Rubin received the B.Sc. and M.Sc. from theTechnion, Israel, and the Ph.D. degree from Princeton University,Princeton, NJ, USA, in Electrical Engineering. Since 1970, he hasbeen on the faculty of the UCLA School of Engineering and Applied Sciencewhere he is currently a Distinguished Professor in the ElectricalEngineering Department. Dr. Rubin has had extensiveresearch, publications, consulting, and industrial experience in thedesign and analysis of commercial and military computer communicationsand telecommunications systems and networks. Recent R&D projectsinclude network design, simulation, management, and planning tools fornetwork modeling and analysis, multi-task resource allocation, unmannedvehicle aided multi-tier ad hoc wireless communicationsnetworks; cross-layer adaptive power, rate and routing for mobilewireless cellular and ad hoc networks. He serves as co-director of theUCLA Public Safety Network Systems Laboratory. During 1979-1980, heserved as Acting
Chief Scientist of the Xerox Telecommunications Network.He served as co-chairman of the 1981 IEEE International Symposiumon Information
Theory; as program chairman of the 1984 NSF-UCLA workshopon Personal Communications; as program chairman for the 1987IEEE INFOCOM
conference; and as program co-chair of the IEEE 1993workshop on Local and Metropolitan Area networks. Dr. Rubin is a LifeFellow of IEE.
He has served as an editor of the IEEE Transactionson Communications, Wireless Networks journal, Optical Networksmagazine, IEEE JSAC issue
on MAC techniques, Communications Systemsjournal, Photonic Networks Communications journal, and has contributedchapters to texts and encyclopedia on telecommunications systems andnetworks.

Optimization of Decentralized Partially Observable Systems inCognitive Radio Networks
2013-03-29 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We consider a non-cooperative Dynamic Spectrum Access (DSA)game where Secondary Users (SUs) access opportunistically the spectrumlicensed for Primary Users (PUs). As SUs spend energy for sensing licensedchannels, they may choose to be inactive during a given time slot in orderto save energy. Then, there exists a tradeoff
between large packetdelay, partially due to collisions between SUs, and high-energyconsumption spent for sensing the occupation of licensed channels. Toovercome this problem, we take into account packet delay and energyconsumption into our framework. Due to the partial spectrum sensing, weuse a Partial Observable Stochastic Game (POSG) formalism, and we analyzethe existence and some properties of the Nash equilibrium using a LinearProgram (LP). We identify a paradox:
when licensed channels are moreoccupied by PUs, this may improve the spectrum utilization by SUs. Basedon this observation, we propose a Stackelberg formulation of our problemwhere the network manager may increase the occupation of licensed channelsin order to improve the SUs average throughput. We prove the existence of aStackelberg equilibrium and we provide some simulations that validate ourtheoretical findings.

Capturing the SINR in cellular networks with Poisson processes
2013-03-20 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
The steady rise of user-traffic in wirelesscellularÂ networks has resulted inÂ the need for developing robust andaccurateÂ models of various performance metrics. A key metric of thesenetworksÂ is theÂ signal-to-interference-and-noise-ratio (SINR)experienced by aÂ typical user.Â For tractability, often the positionsof base stationsÂ in such networks areÂ modelled by Poisson pointprocesses whereasÂ actual deployments often moreÂ resemble lattices(e.g. hexagonal).Â Strikingly, under log-normal shadowing itÂ has beenobserved that theÂ SINR experienced by a typical user is more accurate ina Poisson modelÂ than a hexagonal model. In this talk we seektoÂ explain thisÂ interesting observation by way of a convergenceresult.Â Furthermore,Â we present numerically tractable, explicitintegral expressionsÂ forÂ the distribution of SINR of a cellularnetwork modelled byÂ PoissonÂ process. Our model incorporates apower-law path-loss modelÂ withÂ arbitrarily distributed shadowing. Theresults are valid in theÂ wholeÂ domain of SINR and, unlike previousmethods, do not requireÂ theÂ inversion of Laplace transforms.Based onjoint work inÂ collaborationÂ with B. Blaszczyszyn and M.K. Karray.

Lingering issues in distributed scheduling
2013-03-19 15:00 - 16:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Le prochain sÃ©minaire DYOGEN

Recent advances haveresulted in queue-based algorithms for medium access control which operatein a distributed fashion, and yet achieve the optimal throughputperformance of centralized scheduling algorithms. However, fundamentalperformance bounds reveal that the "cautious" activation rules involved inestablishing throughput optimality tend to produce extremely large delays,typically growing exponentially in 1/(1-r), with r the load of thesystem, in contrast to the usual linear growth.
Motivated by that issue,I will discuss in this talk the extent to which more "aggressive" schemescan improve the delay performance. In the simplest possible scenario, Iwill show how aggressive activation rules induce a lingering effect, whereindividual nodes retain possession of a shared resource for excessivelengths of time even while a majority of other nodes idle. Using centrallimit theorem type arguments, it can be proved that the idleness inducedby the lingering effect may cause the delays to grow with 1/(1-r) at aquadratic rate.

Fluid limit approximations of bandwidth-sharing networks withrateconstraints
2013-03-13 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Bandwidth-sharing networks, asÂ introduced by Massoulie&Â Roberts (1998), model the dynamic interactionÂ among anevolvingÂ population of elastic flows that compete for several links. ThemainÂ area of application of such models is telecommunicationsmedia,Â e.g.Â Internet congestion control. With policies basedonÂ optimizationÂ procedures, bandwidth-sharing networks are ofinterest both fromÂ aÂ Queueing Theory and Operations Researchperspective.In this work,Â weÂ focus on the regime when linkcapacities and arrival rates are ofÂ aÂ large order of magnitudecompared to transfer rates of individualÂ flows,Â which is standard inpractice. Bandwidth-sharing networks areÂ ratherÂ complicated systems(we operate with measure-valued processes toÂ study them),Â and undergeneral structural and stochastic assumptionsÂ they resistexactÂ analysis. So we resort to fluid limit approximations.Â UndergeneralÂ assumptions, we derive the fluid limit for thenetworkÂ evolution in theÂ entire time horizon (extending thecorrespondingÂ result by Reed and Zwart
(2010) for Markovianassumptions). Also, for aÂ wide class of networks, weÂ developpolynomial-time computableÂ fixed-point approximations fortheir
stationary distributions.

V-NDN: Vehicular Named Data
2013-03-06 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
In near future, a car will be equipped with a variety sensorsand wireless interfaces such as 3G/LTE, WiMAX, WiFi, or DSRC/WAVE. Ourvision is to enable vehicles to communicate with each other and with theinfrastructure over any and all physical communication channels, as soonas any channel comes into existence and as long as it is available.Although over the years many research papers have been published forautomotive research, in reality by and large today's vehicles areconnected only through cellular networks to centralized servers. Automotiveresearch such as ad-hoc networking and delay tolerant networking are stillfar from completion and less likely to deploy. We believe the root cause ofthis insoluble problem in networking vehicles is IP's communication model,where IP creates its own name space, the IP address space, assigns IPaddresses to every communicating end point, and then encapsulates eachpiece of application data into an IP packet. This whole process
insulatesapplications from data delivery layer. Taking the named-data networking(NDN) as the starting point, we are developing V-NDN, a
single frameworkto realize our vision. NDN identifies named data as the focal point incommunication. Utilizing the fact that all data communications
happenwithin established application context, and that nodes running the sameapplications decide what data they want to get, NDN lets individual
nodesto request the desired data using application data names directly. Datanames are from applications, they identify data directly; they existonce
applications are running, independent from time-varying connectivityin an ad hoc environment. This enable data to exist in the absence ofconnectivity, and to be exchanged over any physical connectivity once itcomes into existence.We have designed and developed V-NDN and demonstratedthat our design indeed allowed vehicles to utilize all available channelsto communicate; they can effectively communicate with
centralized serversas well as with each other to exchange application data in completely adhoc manner. In this talk we will go over the design
choices and thepreliminary results from our deployment.

Algorithms on evolving graphs.
2013-03-05 14:00 - 16:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Algorithms on evolving graphs. Aris Anagnostopoulos,Ravi Kumar, Mohammad Mahdian, Eli Upfal, and Fabio Vandin. InProceedings of the 3rd Innovations in Theoretical Computer ScienceConference (ITCS '12). ACM, New York, NY, USA, 149-160.
Sorting andselection on dynamic data. Aris Anagnostopoulos, Ravi Kumar, MohammadMahdian, Eli Upfal, Theoretical Computer Science, Volume 412, Issue24, 27 May 2011, Pages 2564-2576.

On the design of architectures and algorithms to supportcontent-oriented functionalities in high speed network equipments
2013-02-27 14:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
The integration of content orientedfunctionalitiesÂ inÂ network equipments is of critical importance forthe deploymentÂ ofÂ future content delivery infrastructures. However,asÂ todayu2019sÂ high-speed network equipments are mostly designed tocarryÂ trafficÂ from one location of the network to another by means ofIPÂ addressÂ information, this integration imposes severe changes tohardwareÂ andÂ software technologies. In this talk we focus on systemdesignÂ andÂ evaluation of the basic building blocksenablingÂ content-orientedÂ communication primitives in networkequipments.Â Specifically, weÂ present challenges and solutions torealize name-basedÂ forwarding,Â packet-level storage management andcontent-based temporary stateÂ atÂ high speed. Finally, we brieflyintroduce our on-going work onÂ theÂ implementation of our solutions onhigh-speed hardware andÂ softwareÂ platforms, and on the evolution ofour designs to supportÂ enhancedÂ content-oriented mechanisms.

Universality and Phase Transition in Compressed Sensing.
2013-02-13 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract: I willÂ start with an introduction on compressedsensing.Â Then I will talk aboutÂ approximate message passingalgorithms andÂ their connection to theÂ universality of a certainphase transitionÂ arising in polytope geometry andÂ compressed sensing.Joint work withÂ M. Bayati and A. MontanariÂ (Stanford)

IPv6 Migration and Carrier-Grade NAT (CGN)
2013-02-06 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:
IPv4 address exhaustion triggered two parallelefforts: theÂ migration toÂ IPv6, and the deployment of IPv4 servicecontinuityÂ technologies, for theÂ most part based on Carrier-GradeNAT. This talkÂ will provide a broad overviewÂ of the current situationwith IPv6Â migration, will explain what the major actors are currentlydoing, andÂ will try to provide some insight about theÂ future. Inparticular, CGNÂ and its impacts will be examined.RelatedÂ standardization efforts willÂ be discussed aswell.

Biography: SimonÂ Perreault is a network engineering consultantwithÂ ViagÃ©nie, a CanadianÂ firm.

A Pricing Mechanism and Revenue Sharing in Network ServiceProviders Alliances
2013-01-30 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Date:
30/01/2013,Â 14h - 15h

Room:
LINCS,salle de conseil

Speaker:
Isabel Amigo (TelecomBretagne)

Talk:
A Pricing Mechanism and Revenue Sharing in NetworkService Providers Alliances

Abstract:
Network Service Providersalliances are envisioned to emerge in the near future as a means of sellingend-to-end quality assured services through interdomain networks. Severalaspects of such a community must be discussed in order to assure itseconomical and technical viability.Â Within the economic ones, pricingand revenue sharing are key aspects on which all alliance's members mustagree. In this context, we present a framework where services are sold viafirst-price auctions and incomes are formulated as the solution ofÂ aNetwork Utility Maximization problem. Then, we discuss the revenue sharingproblem in such context, express the desirable properties of a revenuesharing method, argue why the existing methods are not suitable, andpropose a family of solutions.

Biography:
Isabel Amigo was born inJanuary 23th, 1984 in Montevideo, Uruguay. Since 2007 she holds a degreein Electrical Engineering from Universidad de la RepÃºblica, Uruguay.Since 2006 she is a Research and Teaching assistant at the ElectricalEngineering department of the School of Engineering, Universidad de laRepÃºblica, Uruguay. In late 2007 she joins the technical team of theNationalÂ digital inclusion plan Plan Ceibal , where she is later on incharge of the Projects department and the Research and Development area. OnMarch 2010 she leaves Plan Ceibal in order to pursue a PhD thesis. She iscurrently a PhD candidate at Telecom Bretagne (France) and Universidad dela RepÃºblica (Uruguay), in a co-advised program, under the advisory ofProf. Sandrine Vaton and Prof. Pablo Belzarena.

French Internet resilience
2013-01-16 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract:The FrenchNetwork and Information Security Agency (FNISA) and theFrench NetworkInformation Center (AFNIC) have recently published adetailed report on theFrench Internet resilience. This documentis based on measures performed fortwo key protocols for the Internet :Border Gateway Protocol (BGP) andDomain Name System (DNS).In order to evaluate the resilience of BGP,several indicators have beenused:(i) the correct declaration of routinginformation to regional informationregistries which is necessary to checkmessages received by routers;(ii) the connectivity between operators inorder to evaluate the risk ofa full disconnection;(iii) the frequency ofprefix hijacking by which an operator announces orrelays illegitimaterouting information.In order to estimate this indicators, the FNISA hasanalyzed all BGPmessages of four major French network operators over aperiod of 11 months.Concerning the DNS protocol, the considered indicatorsare:(i) the distribution of name servers among countries andoperators;(ii) the number of unpatched servers still vulnerable to theKaminskyvulnerability;(iii) the deployment of protocols such as IPv6 andDNS Security Extensions(DNSSEC).Measures have been performed in two ways:active measures on DNS serversof .fr domains and passive measures byobserving the traffic onauthoritative servers of .fr administrated byAFNIC.The aim of this talk is to present the results of this first reportandto introduce the new indicators and results which have beenobtainedsince then. In the same time, we will introduced severalopentheoritical problems linked to this study.

Better routing with hyperbolic geometry
2012-12-19 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Date:
19/12/2012,Â LINCS Salle deConseil

Room:
14h-15h

Speaker:
Marc Crovella (BostonUniversity)

Talk:

Abstract:
In the constant search forsimple and efficient routing algorithms,a particularly attractive approachis greedy routing:Â every nodeis assigned a coordinate, and routingconsists of simply forwarding tothe neighbor closest to thedestination.Â Â Unfortunately, in our(Euclidean) world, thisstrategy is prone to failure.Â Â In this talkI will describe how asmall change -- working in Hyperbolic space insteadof Euclidean space --allows one to guarantee that greedy routing is alwayssuccessful.I willreview the properties of hyperbolic space for this problem, andthendescribe how to use it for provably successful greedy routing on astaticgraphs.Next I will describe how to extend this approach to growinggraphs.Finally,I will discuss strategies to make this sort of routingefficient -- that,toensure that paths through the network are short.Thisis joint work with Andrej Cvetkovski

Next Steps towards IP-optical Service Convergence: A NetworkManagement Perspective
2012-12-05 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Despite the steady and significant increase in Internettraffic, today's Internet topologies are stable, reliable, and -underutilized. This is mainly due to the proven ISP practice tooverprovision IP links, - often up to seventy percent, thus allowing foraccommodation of unpredictable flows, while keeping the network stable andresilient against attacks and failures. Even with major benefits, thepractice of overprovision leads to high capital and operational expenses,as well as higher energy consumption. At first glance, dynamic opticalcircuits can address the downsides: optical circuits can be setup to bypassany congested or faulty IP links and are one of the "greenest"technologies. However, the two networks -- optical and Internet, haveevolved as two fundamentally different and separately managed systems, andcannot easily operate in harmony. In this talk, I will discuss why pastapproaches to deploy dynamic optical circuits have not been widely adoptedfor IP routing, - from the point of view of network management, andpresent our research ideas on how Internet can effectively use opticalcircuits. I will talk about the importance of new systems research andpresent new directions in theoretical studies in this field, and also givea practical outlook from our EU Project ONE(http://www.ict-one.eu).

Biography:
Admela Jukan received the M.Sc.degree in Information Technologies from the Politecnico di Milano, Italy,and the Dr. techn. degree (cum laude) in Electrical and ComputerEngineering from the Technische UniversitÃ¤t Wien, Austria. She receivedher Dipl. -Ing. degree from the Fakultet Elektrotehnike i Racunarstva(FER), in Zagreb, Croatia.She is Chair Professor of CommunicationNetworks in Electrical and Computer Engineering Department at theTechnische UniversitÃ¤t Braunschweig in Germany. Prior to coming to TUBraunschweig, she was research faculty at the Institut National de laRecherche Scientifique (INRS), University of Illinois at Urbana Champaign(UIUC) and Georgia Tech (GaTech). In 1999 and 2000, she was a visitingscientist at Bell Labs, Holmdel, NJ. From 2002-2004, she served asProgram Director in Computer and Networks System Research at the NationalScience Foundation (NSF) in Arlington, VA.Â Dr. Jukan serves asAssociate Technical Editor for IEEE Communications Magazine and IEEENetwork. She is a co-Editor in Chief of the Elsevier Journal on OpticalSwitching and Networking (OSN). She is an elected Vice Chair of the IEEEOptical Network Technical Committee, ONTC (Chair in 2014).Â Shecurrently coordinates a collaborative EU project ONE, focusing on networkmanagement convergence of optical networks and the Internet. She isrecipient of an Award of Excellence for the BMBF/CELTIC project "100GbEthernet" and was also awarded the IBM Innovation Award for applications ofparallel computing for rich digital media distribution over opticalnetworks.

A network-centric point of view on Smart Grids
2012-11-28 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Date:
28/11/2012,Â LINCS Salle deConseil

Room:
14h-15h

Speaker:
Alexander Pelov (TelecomBretagne)

Talk:
A network-centric point of view on SmartGrids

Abstract:
The Smart Grid is the evolution of this complexnetwork, with one of the major factors being the integration ofMachine-to-Machine type communications in every element of this network.This talk will concentrate on presenting the ongoing and future projectsrelated to Smart Grids in Telecom Bretagne, such as networking protocolsfor Home Area Networks (HAN) and Neighborhood Area Networks(NAN).

Biography:
Alexander Pelov is an Associate Professor ofComputer Networks in the "Networking, Multimedia and Security" departmentat the Graduate Engineering School Telecom Bretagne, France. His researchfocuses on networking protocols for Machine-to-Machine communications,energy efficiency in wireless networks, and protocols and algorithms forSmart Grid applications, most notably related to Smart Meters,sub-metering and Electrical Vehicles. He received his M.Sc. (2005) from theUniversity of Provence, France and Ph.D. (2009) from the University ofStrasbourg, France, both in Computer Science.

Iterative Power Packing for Distributed Multiple Access in WirelessNetworks
2012-11-21 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We address the problem of designing distributed Multiple AccessControl algorithms for wireless networks under the SINR interference model.In the proposed framework, time is divided into frames consisting of afixed number of slots, and transmitters may adapt the power levels used inthe various slots. We aim at developing fully distributed multiple accessalgorithms that are throughput-optimal in the sense that they perform aswell as centralized scheduling algorithms. These algorithms based on asimple power control mechanism, referred to as Power Packing. Thismechanism allows each transmitter to tune their power levels in thedifferent slots so as to achieve a target rate while minimizing the numberof slots actually used. The proposed algorithms are throughput-optimal,simple and do not require any message passing: each transmitter adapts itspower levels depending on the observed interference levels in the variousslots. We illustrate the efficiency of our algorithms using numericalexperiments.

Auctions of Licensed vs Unlicensed Use of Spectrum
2012-11-14 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Auctions have regained interest from researchers due to itsdifferentnew applications (Google AdWords auctions, cloud computingauctions,privacy auctions, and white spaces spectrum auctions). In thiswork inparticular we explore auctions for spectrum that can beallocatedeither to a Abstract single bidder (for licensed use) or to acollection ofbidders (for unlicensed use). In this auction, a number ofindividualbidders all try to get the spectrum for their exclusive use andagroup of other bidders try to get the spectrum for their collectiveuse.The objective is to study these auctions and compare theirdifferentproperties.

A Browser-based Network Measurement Platform
2012-10-24 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
For analyzing network performance issues, there can be greatutility in having the capability to measure directly from the perspectiveof end systems. Because end systems do not provide any external programminginterface to measurement functionality, obtaining this capability todaygenerally requires installing a custom executable on the system, which canprove prohibitively expensive. In this work we leverage the ubiquity of webbrowsers to demonstrate the possibilities of browsers themselves offeringsuch a programmable environment. We present Fathom, a Firefox extensionthat implements a number of measurement primitives that enable websites orother parties to program network measurements using JavaScript. Fathom islightweight, imposing < 3.2% overhead in page load times for popularweb pages, and often provides 1 ms timestamp accuracy. We demonstrateFathom's utility with three case studies: providing a JavaScript version ofthe Netalyzr network characterization tool, debugging web accessfailures, and enabling web sites to diagnose performance problems of theirclients.

Sequential Anomaly Detection in a Batch with Growing Number ofTests: Application to Network Intrusion Detection
2012-10-17 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
For high (N)-dimensional feature spaces, we consider detectionof an unknown, anomalous class of samples amongst a batch of collectedsamples (of size T), under the null hypothesis that all samples follow thesame probability law. Since the features which will best identify theanomalies are a priori unknown, several common detection strategiesare:

1) evaluating atypicality of a sample (its p-value) based on thenull distribution defined on the full N-dimensional feature space;

2)considering a (combinatoric) set of low order distributions, e.g., allsingletons and all feature pairs, with detections made based on thesmallest p-value yielded over all such low order tests.

The firstapproach relies on accurate estimation of the joint distribution, whilethe second may suffer from increased false alarm rates as N and T grow.Abstract Alternatively, inspired by greedy feature selection commonly usedin supervised learning, we propose a novel sequential anomaly detectionprocedure with a growing number of tests. Here, new tests are (greedily)included only when they are needed, i.e., when their use (on currentlyundetected samples) will yield greater aggregate statistical significanceof (multiple testing corrected) detections than obtainable using theexisting test cadre. Our approach thus aims to maximize aggregatestatistical significance of all detections made up until a finite horizon.Our method is evaluated, along with supervised methods, for a networkintrusion domain, detecting Zeus bot command-and-control (i.e.,intrusion) packet flows embedded amongst (normal) Web flows. It is shownthat judicious feature representation is essential for discriminating Zeusfrom Web.

This work in collaboration with D.J. Miller and F.Kocak.

Biography

George Kesidis received his M.S. and Ph.D. in EECSfrom U.C. Berkeley in 1990 and 1992 respectively. He was a professor in theE&CE Dept of the University of Waterloo, Canada, from 1992 to 2000.Since 2000, he has been a professor of CSE and EE at the PennsylvaniaState University. His research, including several areas ofcomputer/communication networking and machine learning, has Biography beenprimarily supported by NSERC of Canada, NSF and Cisco Systems URP. Heserved as the TPC co-chair of IEEE INFOCOM 2007 among other networking andcyber security conferences. He has also served on the editorial boards ofthe Computer Networks Journal, ACM TOMACS and IEEE Journal onCommunications Surveys and Tutorials. Currently, he is an IntermittentExpert for the National Science Foundation's Secure and TrustworthyCyberspace (SaTC) program.

His home page ishttp://www.cse.psu.edu/~kesidis

Joint complexity of short texts or how to spy Twitter
2012-10-10 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Twitter produces several millions of short texts perhour. Monitoring information tendencies has become a key business. Inparticular the content provider can detect in advance which movie will bepopular and move it toward proxies before it is too late (ie causes anetwork/server congestion). In this talk we present the analysis ofshort texts via joint complexity. The joint complexity of two textsis the number of distinct factors common to both Abstract texts. When thesource models of the texts are close then the joint complexity ishigher. This technique is applied to DNA sequence analysis because ithas a very low overhead. It can now be applied to short textanalysis thanks to more accurate theoretical estimate. In particularwe show new theoretical results when the sources that generatethe texts are Markovian of finite order, a modelthat particularly fits well with text generation.

Joint workwith W.Szpankowski, D. Milioris, B. Berde.

How much do we benefit from cooperation between pairs ofneighbouring base stations?
2012-10-03 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
In the current work we deal with the problem of base stationcooperation in the downlink of infinite wireless cellular networks.Thepositions of base stations are modeled by a Poisson point process. Eachbase station can choose to cooperate or not with exactly oneof its Delaunayneighbours in order to provide service to a user located within its cell.The cooperation protocol uses a variation of the so-called Willems'encoderand a fixed total transmission power per user is considered.Weanalytically derive closed form expressions for the coverage probabilityand we determine the optimal cooperation zones in the network.Numericalevaluation shows benefits in coverage, compared to the common cellulararchitecture. These however are not very high due to thedeterioration inSINR caused by increased outer-cell total interference. Joint work with F.Baccelli.

Towards less Manipulable Voting Systems
2012-09-19 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Voting systems can be used in any situation where severalentities are to make a decision together. However, the sincere vote maylead to a situation that is not a generalized Nash equilibrium: a group ofelectors can hide their sincere preferences in order to change the outcometo a candidate they prefer. In that case, we say that the situation ismanipulable (i.e. susceptible to tactical voting). Gibbard-Satterthwaitetheorem (1973) states that for 3 candidates and more, all voting systemsbut dictatorship are vulnerable to manipulation. So we would like to know,amongst "reasonable" voting systems, which ones are manipulable with aprobability as little as possible. We show that, under quite weakassumptions on the meaning of "reasonable", such optimal voting systemscan be found in the class of systems that depend only on the electors'preorders of preferences over the candidates and meet Condorcet criterion.

Error Free Perfect Secrecy Systems
2012-09-12 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Shannon's fundamental bound for perfect secrecy stated that theentropy of the secret message U cannot be larger than the entropy of thesecret key R shared by the sender and the legitimated receiver. Massey gavean information-theoretic proof of this result and the proof did not requireU and R to be independent. By adding an extra assumption that I(U.R) = 0,we show a tighter bound on H(R) in this talk. Our bound states that thelogarithm of the message sample size cannot be larger than the entropy ofthe secret key. We also consider the case that a perfect secrecy system isused multiple times. A new parameter, namely expected key consumption, isdefined and justified. We show the existence of a fundamental trade-offbetween the expected key consumption and the number of channel uses fortransmitting a cipher-text. A coding scheme, which is optimal undercertain conditions, is introduced.

Evolving Internet into the Future via Named Data Networking
2012-09-10 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
While the Internet has succeeded far beyond expectations, thesuccess has also stretched its initial design assumptions. Sinceapplications operate in terms of data and more end points become mobile,it becomes increasingly difficult and inefficient to satisfy IP'srequirement of determining exactly where (at which IP address) to finddesired data. The Named Data Networking project aims to carry the Internetinto the future through a conceptually simple yet transformationalarchitecture shift, from today's focus on where -- addresses and hosts --to what -- the data that users and applications care about. Â In thistalk I will present the basic design of NDN and our initial results.

NSF Center for Science of Information
2012-09-05 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
"Information is the distinguishing mark of our era, permeatingevery facet of our lives. An ability to understand and harness informationhas the potential for significant advances. Our current understanding ofinformation dates back to Claude Shannon's revolutionary work in 1948,resulting in a general mathematical theory of reliable communication thatnot only formalized the modern digital communication and storage principlesbut also paved the way for the Internet, DVDs and iPods of today. WhileShannon's information theory has had profound impact, its applicationbeyond storage and communication poses foundational challenges. In 2010 theNational Science Foundation established the Science & TechnologyCenter for the Science of Information to meet the new challenges posed bythe rapid advances in networking, biology and knowledge extraction. Itsmission is to advance science and technology through a new quantitativeunderstanding of the representation, communication and processing ofinformation in biological, physical, social and engineering systems.Purdue University leads nine partner institutions: Berkeley, Bryn Mawr,Howard, MIT, Princeton, Stanford, Texas A&M, UCSD, and UIUC (cf.http://cacm.acm.org/magazines/2011/2/104389-information-theory-after-shannon/fulltext).

In this talk, after briefly reviewing main results ofShannon, (cf.http://cacm.acm.org/magazines/2011/2/104389-information-theory-after-shannon/fulltext) we attempt to identify some features of informationencompassing structural, spatio-temporal, and semantic facets ofinformation. We present two new results: One on a fundamental lower boundfor structural compression and a novel algorithm achieving this lower boundfor graphical structures. Second, on the problem of deinterleaving Markovprocesses over disjoint finite alphabets, which have been randomlyinterleaved by a finite-memory switch.

Biography: Wojciech Szpankowskiis Saul Rosen Professor of Computer Science and (by courtesy) Electricaland Computer Engineering at Purdue University where he teaches and conductsresearch in analysis of algorithms, information theory, bioinformatics,analytic combinatorics, random structures, and stability problems ofdistributed systems. He received his M.S. and Ph.D. degrees in Electricaland Computer Engineering from Gdansk University of Technology. He heldseveral Visiting Professor/Scholar positions, including McGillUniversity, INRIA, France, Stanford, Hewlett-Packard Labs, Universitede Versailles, University of Canterbury, New Zealand, EcolePolytechnique, France, and the Newton Institute, Cambridge, UK. He is aFellow of IEEE, and the Erskine Fellow. In 2010 he received the HumboldtResearch Award. In 2001 he published the book Average Case Analysis ofAlgorithms on Sequences, John Wiley & Sons, 2001. He has been aguest editor and an editor of technical journals, including TheoreticalComputer Science, the ACM Transaction on Algorithms, the IEEETransactions on Information Theory, Foundation and Trendsin Communicationsand Information Theory, Combinatorics, Probability, and Computing, andAlgorithmica. In 2008 he launched the interdisciplinary Institute forScience of Information, and in 2010 he became the Director of the newlyestablished NSFScience and Technology Center for Science of Information.

ACM SIGCOMM Information Centric Networking (ICN) preview talks
2012-09-01 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
About 4 talks, more details will follow.

Controlling queue delay
2012-07-20 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Nearly three decades after it was first diagnosed, thepersistently full buffer problem, recently exposed as part of bufferbloatis still with us and made increasingly critical by two trends. First,cheap memory and a more is better mentality have led to the inflation andproliferation of buffers. Second, dynamically varying path characteristicsare much more common today and are the norm at the consumer Internet edge.Reasonably sized buffers become extremely oversized when link rates andpath delays fall below nominal values.The solution for persistently fullbuffers, AQM (active queue management), has been known for two decadesbut has not been widely deployed because of implementation difficulties andgeneral misunderstanding about Internet packet loss and queue dynamics.Unmanaged buffers are more critical today since buffer sizes are larger,delay-sensitive applications are more prevalent, and large (streaming)downloads common. The continued existence of extreme delays at the Internetedge can impact its usefulness and hamper the growth of newapplications.This article aims to provide part of the bufferbloatsolution, proposing an innovative approach to AQM suitable for todayInternet called CoDel (for Controlled Delay,). This is a no-knobs AQM thatadapts to changing link rates and is suitable for deployment andexperimentation in Linux-based routers (as well as silicon).

Talk byDave Taht on a recent ACM Queue paper by Kathleen Nichols, Pollere Inc.VanJacobson, PARC (just google for the link)

SINR diagrams and their application to interference cancellation
2012-07-18 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
In this talk we will first present what a SINR diagram is andwhy it is important to the design of efficient algorithms for wirelessnetworks. Then we will discuss the reception zones of a wireless network inthe SINR model with receivers that employ interference cancellation (IC).IC is a recently developed technique that allows a receiver to decodeinterfering signals, and cancel them from the received signal in order todecode its intended message. We first derive the important topologicalproperties of the reception zones and their relation to high-order Voronoidiagrams and other geometric objects. We then discuss the computationalissues that arise when seeking an efficient description of the zones. Ourmain fundamental result states that although potentially there areexponentially many possible cancellation orderings, and as a result,reception zones, in fact there are much fewer nonempty such zones. Weprove a linear bound (hence tight) on the number of zones and provide apolynomial time algorithm to describe the diagram. Moreover, we introducea novel parameter, the Compactness Parameter, which influences thetightness of our bounds. We then utilize these properties to devise alogarithmic time algorithm to answer point-location queries for networkswith IC.

This work was published in the Proceedings of the 23rd AnnualACM-SIAM Symposium on Discrete Algorithms (SODA'12).

Biography: YoramHaddad received his BSc, Engineer diploma and MSc (Radiocommunications)from SUPELEC in 2004 and 2005, and his PhD in computer science andnetworks from Telecom ParisTech in 2010. Since 2010 he is a tenure-tracksenior lecturer (Assistant Professor) at the Jerusalem College ofTechnology (JCT) in Jerusalem, Israel. In parallel, since 2011 he is apost-doctoral research associate at the Ben- Gurion University (BGU) inBeer-Sheva, Israel. Yoram's main research interests are in the area ofWireless Networks and Algorithms for networks. He is specificallyinterested in energy efficient wireless deployment, Femtocell, modelingof wireless networks, wireless application to Intelligent TransportationSystems (ITS) and more recently Wireless Software Defined Networks (SDN).

Netmap
2012-07-04 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Many applications (routers, traffic monitors, firewalls,etc.) need to send and receive packets at line rate even on very fastlinks. In this paper we present netmap, a novel framework that enablescommodity operating systems to handle the millions of packets per secondtraversing 1..10 Gbit/s links, without requiring custom hardware orchanges to applications. In building netmap, we identified andsuccessfully reduced or removed three main packet processing costs:per-packet dynamic memory allocations, removed by pre-allocatingresources. system call overheads, amortized over large batches. and memorycopies, eliminated by sharing buffers and metadata between kernel and userspace, while still protecting access to device registers and other kernelmemory areas. Separately, some of these techniques have been used in thepast. The novelty in our proposal is not only that we exceed theperformance of most of previous work, but also that we provide anarchitecture that is tightly integrated with existing operating systemprimitives, not tied to specific hardware, and easy to use and maintain.netmap has been implemented in FreeBSD and Linuxfor several 1 and 10 Gbit/snetwork adapters. In our prototype,a single core running at 900 MHz cansend orreceive 14.88 Mpps (the peak packet rate on 10 Gbit/slinks). This ismore than 20 times faster than conventional APIs. Large speed ups (5x andmore) are also achieved on user-space Click and other packet forwardingapplications using a libpcap emulation library running on top ofnetmap.

This work received the Best paper award at USENIX ATC 201.

Scientific Workshop 2012 Conclusionary Remarks
2012-06-19 18:00 - 18:15 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Alcatel-Lucent Vision and the Relevance of the LINCS
2012-06-19 16:00 - 16:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Towards Sybil-tolerant Systems
2012-06-19 15:30 - 16:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Super-scalable P2P Networks
2012-06-19 15:00 - 15:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Platforms and TestBeds
2012-06-19 14:30 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Internet of Things
2012-06-19 14:00 - 14:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Design and Analysis of Content Caching Networks
2012-06-19 12:00 - 12:45 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Diffusion and Cascading Behavior in Random Networks
2012-06-19 11:45 - 12:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Asynchronous Packet Switching
2012-06-19 11:15 - 11:45 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Big Data and Page Ranking
2012-06-19 10:30 - 11:45 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
An introduction to DIteration.

Wireless Networks
2012-06-18 12:15 - 13:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Metrology
2012-06-18 11:45 - 12:15 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Real-time Wireless Networking
2012-06-18 11:15 - 11:45 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Content Distribution and Information Centric Networking Overview ofactivities and main results
2012-06-18 10:15 - 10:45 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Network on Chip
2012-06-18 09:45 - 10:45 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

OpenFlow and Software Defined Networking
2012-06-18 09:30 - 10:15 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France

Introduction of LINCS
2012-06-18 09:00 - 09:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Daniel Kofman, the director of LINCS, introduces the lab.

Scaling Analysis of a Transient Stochastic Network (TREC seminar)
2012-06-07 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
In this talk, we consider a simple transient Markov processwith an absorbing point to investigate the qualitative behavior of a largescale storage network of non reliable file servers where files can beduplicated. When the size of the system goes to infinity we show that thereis a critical value for the maximum number of files per server such thatbelow this quantity, the system stays away from the absorbing state, allfiles lost, in a quasi-stationary state where most files have a maximumnumber of copies. Above this value, the network looses a significantnumber of files until some equilibrium is reached. When the network isstable, we prove that, with Â convenient time scales, the evolution ofthe network towards the absorbing state can be described via a stochasticaveraging principle. Some extensions of this model will be discussed.

Bipartite graph structures for efficient balancing of heterogeneousloads
2012-06-06 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
ACM SIGMETRICS'12 Preview Talk

This paper considers largescale distributed content serviceplatforms, such as peer-to-peervideo-on-demand systems.Such systems feature two basic resources, namelystorageand bandwidth. Their efficiency critically depends on twofactors:(i) content replication within servers, and (ii) howincoming servicerequests are matched to servers holding requestedcontent. To inform thecorresponding design choices,we make the following contributions.We firstshow that, for underloaded systems, so-called pro-portional contentplacement with a simple greedy strategyfor matching requests to serversensures full system efficiencyprovided storage size grows logarithmicallywith the systemsize. However, for constant storage size, this strategyundergoesa phase transition with severe loss of efficiency assystem loadapproaches criticality.To better understand the role of the matchingstrategy inthis performance degradation, we characterize theasymptoticsystem efficiency under an optimal matching policy.Our analysisshows that -in contrast to greedy matching-optimal matching incurs aninefficiency that is exponentiallysmall in the server storage size, evenat critical systemloads. It further allows a characterization of contentreplicationpolicies that minimize the inefficiency. These optimalpolicies,which differ markedly from proportional placement,have a simple structurewhich makes them implementablein practice.On the methodological side, ouranalysis of matching performanceuses the theory of local weak limits ofrandomgraphs, and highlights a novel characterization of matchingnumbersin bipartite graphs, which may both be of independentinterest.

Jointwork by Mathieu Leconte (Technicolor - INRIA), Marc Lelarge (INRIA - EcoleNormale SupÃ©rieure) and Laurent MassouliÃ© (Technicolor)

Mobile web acceleration challenges
2012-05-30 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Abstract to be added.

Distributed scheduling algorithm for asynchronous input-queuedswitches
2012-05-16 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Input-queued (IQ) switches are one of thereferencearchitectures for the design of high-speed packet switches.Classical results in this field refer to the scenario in which the wholeswitch transfers the packets in a synchronous fashion, in phase with asequence of fixed-size timeslots, selected to transport aminimum-sizepacket. However, for switches with large numberof ports and highbandwidth, maintaining an accurate global synchronization and transferringall the packets in a synchronousfashion is becoming more and morechallenging. Furthermore,variable size packets (as in the traffic presentin the Internet) require rather complex segmentation and reassemblyprocesses and some switching capacity is lost due to partial filling oftime slots. Thus, we consider a switch able to natively transfer packetsin an asynchronous fashion thanks to a simple and distributed packetscheduler. We investigate the performance of synchronous IQ switches andshow that, despite their simplicity, their performance is comparable oreven better than those of synchronous switches. These partly unexpectedresults highlight the great potentiality of the asynchronous approach forthe design of high-performance switches.

D-iteration: asynchronous distributed computation
2012-05-09 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We present a first evaluation of the potential of anasynchronous distributed computation associated to the recently proposedapproach, D-iteration: the D-iteration is a fluid diffusion basediterative method, which has the advantage of being natively distributive.It exploits a simple intuitive decomposition of the matrix-vector productas elementary operations of fluid diffusion associated to a new algebraicrepresentation. We show through experiments on real datasets how much thisapproach can improve the computation efficiency when the parallelism isapplied: with the proposed solution, when the computation is distributedover K virtual machines (PIDs), the memory size to be handled by eachvirtual machine decreases linearly with K and the computation speedincreases almost linearly with K with a slope becoming closer to one whenthe number N of linear equations to be solved increases.

Game-theoretic resource management in cellular networks
2012-05-02 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We pose a few resource management problems in cellularnetworks, and propose solutions based on game theory. First, weinvestigate cooperation among cellular service providers. We considernetworks in which communications involving different base stations do notinterfere. If providers jointly deploy and pool their resources, such asspectrum and BSs, and agree to serve each others customers, theiraggregate payoff substantially increases. The potential of such cooperationcan, however,be realized only if the providers intelligently determinewho they would cooperate with, how they would deploy and share theirresources, and howthey would share the aggregate payoff. We assume thatthe providers can arbitrarily share the aggregate payoff . Then,developing a rational basis for payoff sharing is imperative for thestability of the coalition. We address these issues by formulatingcooperation using the theory of transferable utility coalitional games. Iwill briefly discuss two other resource allocation problems in cellularnetworks which are in the context of joint power control, BS associationand BS placement in the uplinks of cellular networks.

Privacy preference expression
2012-04-25 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
As we browse the web we are tracked by ad-networks, socialnetworks and other third parties that build (supposedly) anonymized andincomplete records of users' browsing histories. This talk will firstdiscuss the threats resulting from web-tracking by describing how theserecords can be de-anonymized. Then, we will overview existing solutions toprevent tracking with a focus on the work done in the W3C TrackingProtection group. We will also quickly overview privacy-preservingmechanisms that could be used to support behavioral targeting. In the lastpart of the talk we will discuss another type of threat: photo tagging onsocial networks. We will quickly overview the proposed mechanism to protectprivacy of pictured persons. Finally we will present Photo-TaggingPreference Enforcement (Photo-TaPE) which helps users to control how theirpictures are published on the web.

Wire-speed statistical classification of network traffic oncommodify hardware
2012-04-18 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
In this paper, we present a software-based trafficclassification engine running on off-the-shelf multi-core hardware, ableto process in real-time aggregates of up to 15 million packet per secondover a single 10Gbps interface.This significant advance with respect toachievable classification rates with respect to the current state of theart is possible due to: (i) the use of Packet Shading to efficiently movebatches of packet headers from the NIC to the main CPU. (ii) the use oflightweight statistical classification techniques expoiting the size of thefirst few packets of a flow. (iii) a careful tuning of several aspects ofthe software application and of the hardware environment.Using both realTier-1 traces and synthetic traffic, we demonstrate that trafficclassification of more than 10Gbps traffic aggregates is feasible withopen-source sofware on common hardware.

Towards all-optical packet networks using optical switch-combiners
2012-04-11 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We propose a novel manner to perform optical packet switchingwhich does not require any prior electronicsignaling or header processing.The proposed packet switchingscheme can be implemented by means of a newoptical deviceable to handle packet contention in the optical domainbyimplementing a first-come first-served policy. This simple deviceis basedexclusively on off-the-shelf components and can be usedto build opticalpacket switches, that we refer to as switch-combiners. The latter can inturn be used to build all-opticalpacket networks. Using variants of theEngset model, we analysethe impact of network load on the performance ofdata traffic.The results are illustrated on the practically interestingcases ofaccess and data center networks.

Joint work with T. Bonald, D.Cuda and L. Noirie

Routing in equilibrium
2012-04-04 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Some path problems cannot be modelled using semirings becausethe associated algebraic structure is not distributive. Rather thanattempting to compute globally optimal paths with such structures, it maybe sufficient in some cases to find locally optimal paths - paths thatrepresent a stable local equilibrium.For example, this is the type ofrouting system that has evolved to connect Internet Service Providers(ISPs) where link weights implement bilateral commercial relationshipsbetween them.Previous work has shown that routing equilibria can becomputed for some non-distributive algebra susing algorithms in theBellman-Ford family.However, no polynomial time bound was knownfor suchalgorithms. In this talk, we show thatrouting equilibria can be computedusing Dijkstra's algorithm for one class of non-distributivestructures.This provides the first polynomial time algorithm for computing locallyoptimal solutions to path problems.

This is joint work with JoÃ£oLuÃs Sobrinho (http://www.lx.it.pt/~jls/) presented at the 19thInternational Symposium on Mathematical Theory of Networks and Systems(MTNS 2010).

You can find the paper here:http://www.cl.cam.ac.uk/~tgg22/publications/routing_in_equilibrium_mtns_2010.pdf

Biography: Timothy G. Griffin is currently on sabbatical in Parisat PPS/INRIA-pi-r2, http://www.pps.jussieu.fr

This filehttp://www.cl.cam.ac.uk/~tgg22/metarouting/rie-1.0.v is a first cut atformalizing these results using Coq (http://coq.inria.fr) with ssreflect(http://www.msr-inria.inria.fr/Projects/math-components)

Opportunities and challenges for ICN experimentation and deploymentin software defined networks
2012-03-28 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
The Information-Centric Networking (ICN) paradigm is expectedto be one of the major innovations of the Future Internet. An ICN systemcan be characterized by some key components like: (i) the content-centricrequest/reply paradigm for data distribution, (ii) route-by-nameoperations, and (iii) in-network caching.A crucial problem for all ICNsolutions is to identify policies forits experimentation in a realnetworking environment and its actua ldeployment in operating networkinfrastructures. Software Defined Networking (SDN), which is another topiccurrently attracting increasing attention, may represent a valid solutiontosuch a problem. SDN serates the forwarding operations from the networkcontrol operations which may be defined dynamically through software. Inthis way, it is extremely simple to introduce novel networkingsolutions,in operating communication infrastructures, thus increasingnetwork evolvability. We are currently implementing and testing an ICNapproach, named CONET (COntent NETwork), in OFELIA - a pan-European SDNnetwork platform, based on the OpenFlow technology. This talk will coverour motivations, our expectations and our frustrations. in other words thelessons we are learning in such a process.

On sizing CCN content stores by exploiting topological information
2012-03-21 15:15 - 15:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Preview of talk at INFOCOM 2012 and associated workshop.

Inthis work, we study the caching performance of Content Centric Networking(CCN), with special emphasis on thesize of individual CCN router caches.Specifically, we consider several graph-related centrality metrics (e.g.,betweenness, closeness, stress, graph, eccentricity and degreecentralities) to allocate content store space heterogeneously across theCCN network, and contrast the performance to that of an homogeneousallocation. To gather relevant results, we study CCN caching performanceunder large cache sizes (individual content stores of 10 GB), realistictopologies (up to 60 nodes), a YouTube-like Internet catalog (10^8 filesfor 1PB video data). A thorough simulation campaign allow us to concludethat

the gain brought bycontent store size heterogeneity is verylimited, and that
the simplest metric, namely degree centrality,already proves to be a sufficiently good allocation criterion.

On theone hand, this implies rather simple rules of thumb forthe content storesizing (e.g., if you add a line card to a CCN router, add some contentstore space as well). On the other hand, we point out that technologicalconstraints, such as line speed operation requirement, may however limitthe applicabilityof degree-based content store allocation.

Joint workwith D. Rossi

An effective hop-by-hop interest shaping mechanism for CCNcommunications
2012-03-21 15:00 - 15:15 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Preview of talk at INFOCOM 2012 and associated workshop.

Weintroduce a rate-based congestion control mechanism for Content-CentricNetworking (CCN). It builds on the fact that one Interest retrieves at mostone Data packet. Congestion can occur when aggregate conversations arrivein excess and fill up the transmission queue of a CCN router. We computethe available capacity of each CCN router in a distributed way in order toshape their conversations Interest rate and therefore adjust dynamicallytheir data rate and transmission buffer occupancy. We demonstrate theconvergence properties of this Hop-by-hop Interest Shaping mechanism(HoBHIS) and provide a performance analysis based on various scenariosusing our ns-2 simulation environment.

Joint work with Serge Fdida.

ICP: design and evaluation of an interest control protocol forcontent-centric networking
2012-03-21 14:45 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Preview of talk at INFOCOM 2012 and associatedworkshop

.Content-centric networking (CCN) brings aparadigm shift in thepresent Internet communication modelby addressing named-data instead ofhost locations. With respect to TCP/IP, the transport model isconnectionless witha unique endpoint at the receiver, driving a retrievalprocess natively point to multi-point. Another salient feature of CCN isthe possibility to embed storage capabilities into the network, adding anew dimension to the transport problem. The focus of this work is on thedesign of a receiver-driven Interestcontrol protocol for CCN, whosedefinition, to the best of our knowledge, still lacks in literature. ICPrealizes a window-based interest flow control, achieving full efficiencyand fairness under proper parameters setting. In this paper, we provide ananalytical characterization of average rate, expected datatransfer delayand queue dynamics in steady state on a single and multi-bottleneck networktopology. Our model accounts for the impact of on-path caches. Protocolperformance is also assessed via packet-level simulations and designguidelines are drawn from previous analysis.

Joint work with G.Carofiglio and L. Muscariello.

Characterizing end-host application performance across multiplenetworking environments
2012-03-21 14:30 - 14:45 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Preview of talk at INFOCOM 2012 and associatedworkshop.

Users today connect to the Internet everywhere - from home,work, airports, friend's homes, and more. This paper characterizes howthe performance of networked applications varies across networkingenvironments. Using data from a few dozen end-hosts, we compare thedistributions of RTTs and download rates across pairs of environments. Weillustrate that for most users the performance difference is statisticallysignificant. We contrast the influence of the application mix andenvironmental factors on these performance differences.

Joint work withOana Goga, Renata Teixeira, Jaideep Chandrashekar and Nina Taft.

Stochastic geometry based medium access games
2012-03-21 14:15 - 14:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Preview of talk at INFOCOM 2012 and associated workshop.
Thispaper studies the performance of Mobile Ad hoc Networks (MANETs) when thenodes, that form a Poisson point process, selfishly choose their MediumAccess Probability (MAP). We consider goodput and delay as the performancemetric that each node is interested in optimizing taking into account thetransmission energy costs. We introduce a pricing scheme based on thetransmission energy requirements and compute the symmetric Nash equilibriaof the game in closed form. It is shown that by appropriately pricing thenodes, the selfish behavior of the nodes can be used to achieve the socialoptimum at equilibrium. The Price of Anarchy is then analyzed for thesegames. For the game with delay based utility, we bound the price ofanarchy and study the effect of the price factor. For the game with goodputbased utility, it is shown that price of anarchy is infinite at the pricefactor that achieves the global optima.
Joint work with E. Altman and F.Baccelli.Full paper is available at http://arxiv.org/pdf/1112.3741.pdf

On the spatial modeling of wireless networks by random packingmodels
2012-03-21 14:00 - 14:15 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Preview of talk at INFOCOM 2012 and associated workshop.

Inorder to represent the set of transmitters simultaneously accessing awireless network using carrier sensing based medium access protocols, oneneeds tractable point processes satisfying certain exclusion rules. Suchexclusion rules forbid the use of Poisson point processes within thiscontext. It has been observed that Matern point processes, which have beenadvocated in the past because of their exclusion based definition, arerather conservative within this context. The present paper confirms that itwould be more appropriate to use the point processes induced by the RandomSequential Algorithm in order to describe such point patterns. It alsoshows that this point process is in fact as tractable as the Matern model.The generating functional of this point process is shown to be the solutionof a differential equation, which is the main new mathematical result ofthe paper. In comparison, no equivalent result is known for the Maternhard-core model. Using this differential equation, a new heuristic methodis proposed, which leads to simple bounds and estimates for severalimportant network performance metrics. These bounds and estimates areevaluated by Monte Carlo simulation.

Joint work with Francois Baccelli

A fine-grained distance metric for analyzing Internet topology
2012-03-20 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
One of the defining properties of small worlds is theprevalence of short paths connecting node pairs. Unfortunately, as aresult the usual notion of distance is not particularly helpful indistinguishing neighborhoods in such graphs. This is the case, forexample, when analyzing the interdomain routing system of the Internet. Wedescribe a motivating problem that requires a finer-grained notion ofdistance. The problem is quite simple to state: how can any given networkoperator in the Internet determine which paths pass through its network.Surprisingly, the nature of Internet routing makes this question ratherhard to answer. To address this problem, we define a new distance metricon graph nodes. This metric has useful and interesting properties: it iseasy to compute and understand, it can be used to sharply distinguishneighborhoods in networks, and it remains useful even in small-worldnetworks. We show how we use this metric to address our motivatingproblem, and more generally how it can be used for visualization anddimensionality reduction of complex networks.

D-iteration method or how to improve the Gauss-Seidel method
2012-03-14 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
The aim of this paper is to present the recently proposed fluiddiffusion based algorithm in the general context of the matrix inversionproblem associated to the Gauss-Seidel method. We explain the simpleintuitions that are behind this diffusion method and how it can outperformexisting methods. Then we present some theoretical problems that areassociated to this representation as open research problems. We alsoillustrate some connected problems such as the graph transformation and thePageRank problem.

Measurement-based admission control for flow-aware implicit servicedifferentiation
2012-03-07 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
It has previously been shown that the combined use of fairqueuing and admission control would allow the Internet to providesatisfactory quality of service for both streaming and elastic flowswithout explicitly identifying traffic classes. In this paper we discussthe design of the required measurement based admission control (MBAC)scheme. The context is different to that of previous work on MBAC in thatthere is no prior knowledge of flow characteristics and there is a twofoldobjective: to maintain adequate throughput for elastic flows and to ensurelow packet latency for any flow whose peak rate is less than a giventhreshold. In this talk, we consider the second objective assumingrealistically that most elastic and streaming flows are rate limited. Weintroduce a MBAC algorithm and evaluate its performance by simulation underdifferent stationary traffic mixes and in a flash crowd scenario. Thealgorithm is shown to offer a satisfactory compromise between flowperformance and link utilization.

Joint work with Sara Oueslati, JamesRoberts, 23rd International Teletraffic Congress (ITC 2011), SanFrancisco (CA), Sep 6-8, 2011

Probe and pray: using UPnP for home network measurements
2012-02-29 15:30 - 16:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Preview of talk/ workshop at PAM 2012.

Network measurementpractitioners increasingly focus their interest on understanding anddebugging home networks. The Universal Plug and Play (UPnP) technologyholds promise as a highly efficient way to collect and leverage measurementdata and configuration settings available from UPnP-enabled devices foundin home networks. Unfortunately, UPnP proves less available and reliablethan one would hope. In this paper, we explore the usability of UPnP as ameans to measure and characterize home networks. We use data from 120,000homes, collected with the HomeNet Profiler and Netalyzr troubleshootingsuites. Our re- sults show that in the majority of homes we could notcollect any UPnP data at all, and when we could, the results werefrequently inaccurate or simply wrong. Whenever UPnP-supplied data provedaccurate, however, we demonstrate that UPnP provides an array of usefulmeasurement techniques for inferring home network traffic and losses, foridentifying home gateway models with configuration or implementationissues, and for obtaining ground truth on access link capacity.

Jointwork with Renata Teixeira (UPMC Sorbonne Universites and CNRS), Martin May(Technicolor), and Christian Kreibich (ICSI).

Experimental assessment of BitTorrent completion time inheterogeneous TCP/uTP swarms
2012-02-29 15:00 - 15:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Preview of talk/ workshop at PAM 2012.

BitTorrent, one ofthe most widespread used P2P application for file-sharing, recently gotrid of TCP by introducing an application-level congestion control protocolnamed uTP. The aim of this new protocol is to efficiently use the availablelink capacity, while minimizing its interference with the rest of usertraffic (e.g., Web, VoIP and gaming) sharing the same access bottleneck.In this paper we perform an experimental study of the impact of uTP on thetorrent completion time, the metric that better captures the userexperience. We run BitTorrent applications in a flash crowd scenario over adedicated cluster platform, under both homogeneous and heterogeneous swarmpopulation. Experiments show that an all-uTP swarms have shorter torrentdownload time with respect to all-TCP swarms. Interestingly, at the sametime, we observe that even shorter completion times can be achieved undermixtures of TCP and uTP traffic, as in the default BitTorrentsettings.

Joint work with D. Rossi (Telecom ParisTech), A. Rao (INRIA)and A. Legout (INRIA).

Speed measurements of residential Internet access
2012-02-29 14:30 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Preview of talk/ workshop at PAM 2012.

The spread ofresidential broadband Internet access is raising the question of how tomeasure Internet speed. We argue that available bandwidth is a key metricof access link speed. Unfortunately, the performance of availablebandwidth estimation tools has rarely been tested from hosts connected toresidential networks. This paper compares the accuracy and overhead ofstate-of-the-art available bandwidth estimation tools from hosts connectedto commercial ADSL and cable networks. Our results show that, when usingdefault settings, some tools underestimate the available bandwidth by morethan 60%. We demonstrate using controlled testbeds that this happensbecause current home gateways have a limited packet forwardingrate.

Joint work with Renata Teixeira (UPMC Sorbonne Universite andCNRS, LIP6, Paris, France).

An end-host view on local traffic at home and work
2012-02-29 14:00 - 14:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Preview of talk/ workshop at PAM 2012.

Our work compareslocal and wide-area traffic from end-hosts connected to different home andwork networks. We base our analysis on network and application tracescollected from 47 end-hosts for at least one week. We compare trafficpatterns in terms of number of connections, bytes, duration, andapplications. Not surprisingly, wide-area traffic dominates local trafficfor most users. Local connections are often shorter and smaller thanInternet connections. Moreover, we find that name services (DNS) andnetwork file systems are the most common local applications, whereas websurfing and P2P, which are the most popular applications in thewide-area, are not significant locally.

Joint work with FabianSchneider (NEC Laboratories Europe, Heidelberg, Germany), RenataTeixeira (UPMC Sorbonne Universite and CNRS, LIP6, Paris, France).

Self-optimization of radio resources in small and macro cellnetworks
2012-02-22 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
We propose and analyze a class of distributed algorithmsperforming the joint optimization of radio resources in heterogeneouscellular networks made of a juxtaposition of macro and small cells. We seethat within this context, it is essential to use algorithms able tosimultaneously solve the problems of channel selection, user associationand power control. In such networks, the unpredictability of the cell anduser patterns also requires self-optimized schemes. The proposed solutionis inspired from statistical physics and is based on Gibbs sampler. It canbe implemented in a distributed way and nevertheless achieves minimalsystem-wide potential delay. Simulation results have shown itseffectiveness.

Fock space representation and variational analysis of Poissonfunctionals
2012-02-21 14:30 - 15:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We consider a Poisson process Phi on a general phase space. Theexpectation of a function of Phi can be considered as a functional of theintensity measure lambda of Phi. Extending ealier results of Molchanov andZuyev (2000) on finite Poisson processes, we will study the behaviour ofthis functional under signed (possibly infinite) perturbations of lambda. Akey ingredient of our approach is the explicit Fock space representationobtained in Last and Penrose (2011). As an application we will discuss theinfinite cluster in a supercitical Boolean model.
This part of the talk isbased on joint work with Sergei Zuyev.

Bit flipping models
2012-02-21 14:00 - 14:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
In many areas of engineering and science one faces with anarray of devices which possess a few states. In the simplest case thesecould be on-off or idle-activated states, in other situations broken or`dead' states are added. If the activation-deactivation (flipping) orbreakage cycles produce in a random fashion, a natural question to ask iswhen, if at all, the system of devices, which we call bits, recovers tosome initial or ground state. By this we usually mean the state when allthe bits are not active, allowing only for idling and/or broken bits to beseen. When the number of bits is infinite, the time to recover may assumefinite or infinite values when the system actually does not recover. In thelatter case we speak of transient behaviour of the system. In the formercase, depending of whether the mean of the recover time exists or not, wespeak of positive or null-recurrence of the system. The terminology isborrowed from Markov chains setting and the above classification is tightlyrelated to the exact random mechanism governing the change of bits' states.The main result for models involving infinite number of bits is theexistence of the critical decay of flipping intensities, at which themodel changes from transient to the recurrent behaviour. We show that therecurrence is always null recurrence and estimate which moments of therecover time exist. Besides, a central limit theorem can be establishedfor the exact way the system behaves in the transient regime.

Design and analysis of content caching networks
2012-02-15 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Today's Internet architecture, nearly 40 years old now, isgrounded in a model of host-to-host communication. More recently, a numberof researchers have begun to focus on Content Networking - a model in whichhost-to-content (rather than host-to-host) interaction is the norm. Here,content distribution and retrieval, rather than host-to-host packetdelivery, is the core function supported in each and every network node. Acentral component of proposals for such content delivery is the routing ofcontent to requestors through a large-scale interconnected network ofcaches. In this talk we focus on this cache network.

We begin with aquick overview of Content Networking. We then describe Breadcrumbs - asimple content caching, location, and routing system that uses a smallamount of information regarding cache history/routing in a simple,best-effort approach towards caching. In the second part of this talk weconsider the broad challenge of analyzing networks of interconnectedcaches. We describe an iterative fixed-point algorithm for approximatingcache network performance, evaluate the accuracy of the approximation,and identify the sources of approximation error. We also consider thesteady state behavior of cache networks. We demonstrate that certain cachenetworks are non-ergodic in that their steady-state characterizationdepends on the initial state of the system. We describe sufficientconditions (based on topology, admission control, and cache replacementpolicy) for ergodicity and ergodicity equivalence classes among policies.Last, we describe current work on developing a network calculus for cachenetwork flows.

Joint work with Elisha Rosensweig, Daniel Menasche, DonTowsley.

VNEXT: Virtual NEtwork management for Xen-based Testbeds
2012-02-08 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Network testbeds strongly rely on virtualization that allowsthe simultaneous execution of multiple protocol stacks but also increasesthe management and control tasks. This talk presents a system to controland manage virtual networks based on the Xen platform. The goal of theproposed system is to assist network administrators to performdecision-making in this challenging virtualized environment. The systemmanagement and control tasks consist of defining virtual networks, turningon, turning off, migrating virtual routers, and monitoring the virtualnetworks within few mouse clicks thanks to a user-friendly graphicalinterface. The administrator can also perform high-level decisions, suchas redefining the virtual network topology by using the plane-separationand loss-free live migration functionality, or saving energy by shuttingdown physical routers. Performance tests assure the system has low responsetime.

Biography: Miguel Elias Mitre Campista was born in Rio deJaneiro, Brazil, on May 8th, 1980. He received the TelecommunicationsEngineer degree from the Fluminense Federal University (UFF), Rio deJaneiro, Brazil, in 2003 and the M.Sc. and D.Sc. degrees in ElectricalEngineering from the Federal University of Rio de Janeiro (UFRJ), Rio deJaneiro, Brazil, in 2005 and 2008, respectively. Currently, Miguel iswith GTA Laboratory in COPPE/UFRJ. His major research interests are inmultihop wireless networks, quality of service, wireless routing,wireless mesh networks, and home networks.

Modeling data transfer in content-centric networks
2012-02-01 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
The move towards a future Internet is today hindered by themismatch between the host-oriented model, at thefoundation of the currentnetwork architecture, and the dominant content-oriented usage, centeredon data dissemination and retrieval. Content-centric networking (CCN)brings a paradigm shift in the present Internet communication model byaddressing named-data instead of host locations. Important features of suchnetworks are the availability of built-in network storage and ofreceiver-driven chunk level transport, whose interaction significantlyimpacts overall system and user performance. In the talk, I will focus onthe performance evaluation of CCN networks and present an analytical modelof bandwidth and storage sharing under fairly general assumption on totaldemand, topology, content popularity and limited network resources.Further, an overview of the ongoing activities and the main researchchallenges in this area will be provided.

Robustesse temporelle dans les systèmes embarqués mono etmultiprocesseur
2012-01-26 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Le respect de contraintes temporelles strictes dans unsystème temps réel peut être garanti par l’établissement deconditions de faisabilité pires cas. Ces conditions de faisabilité sontétablies pour un système temps réel spécifié par différents modèles(modèle de taches exécutées, modèle d’ordonnancement, modèled’architecture,…). Nous nous intéressons dans cette présentation aumodèle sporadique et aux ordonnancements préemptifs Ã priorités fixeset dynamiques (Earliest Deadline First) pour des architectures mono etmultiprocesseur. Le modèle sporadique est défini par ses hypothèsespires cas (pire durée d’exécution, inter-arrivée minimale etéchéance minimale de terminaison au plus tard associées aux tâches).Les conditions de faisabilité permettant de garantir la ponctualité destraitements sont parfois jugées restrictives car elles se basent sur desmodèles de systèmes pessimistes. Nous nous intéressons dans cetteprésentation Ã la robustesse temporelle d’un système en cas dedéviation de ses spécifications (hors-ligne dans une phase dedimensionnement ou en-ligne). Nous nous focalisons sur la sensibilié despires durées d’exécution (WCETs) et montrons comment caractériserleurs déviations maximales acceptables ne remettant pas en causel’ordonnancabilité des tâches. Les causes de déviation sontmultiples, elle proviennent soit de problèmes de conception (fauteslogicielles ou matérielles), de l’imprécision du modèle de système(pas de prise en compte du coÃ‹Å¡t système, du coÃ‹Å¡t de lapréemption ou de migration), ou de l’adaptation du système auxconditions opérationnelles de son utilisation : changement des paramètrespour obtenir plus de précision, contraintes d’énergie conduisant Ã changer la fréquence du processeur ou Ã augmenter les périodes. Unsystème temps réel, dans ce contexte, se doit d’être beaucoup plusrobuste Ã ces variations. Nous étudions dans cet exposé la robustessetemporelle des systèmes temps réel en contexte monoprocesseur puis encontexte multiprocesseur selon l’approche semi-partitionnée, approchehybride entre l’approche partitionnée et l’approche globale. Nousterminons cette présentation par des perspectives d’applications de cestravaux aux systèmes distribués pour des modèles de tâches dont lesdurées d’exécution sont probabilistes.

The Fleming Viot process driven by subcritical branching: aselection principle
2012-01-25 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We consider Fleming Viot processes having the followingdynamics: N particles move independently according to the dynamics of asubcritical branching process until they hit 0, at which point, theyinstantaneously and uniformly choose the position of one of the otherparticles. We first establish a coupling between the FV processes(associated to any one-dimensional dynamics) and multitype branchingprocesses. This allows us to prove convergence of scaled version of the FVprocesses and ergodicity for fixed N. Using large deviations estimate forsubcritical branching processes, this coupling further allows to obtainuseful drift inequalities for the maximum of the Fleming Viot process.These inequalities imply in turn tightness of the family of empiricalmeasures under measure of the branching process when N tends to infinity.the stationary measure of the FV process. Finally, we prove a selectionprinciple: the empirical measures converge to the extremal quasi-stationarymeasure of the branching process when N tends to infinity.

Performance of P2P networks with spatial interactions of peers
2011-12-07 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
We propose a new model for peer-to-peer networking which takesthenetwork bottlenecks into account beyond the access. This model allowsoneto cope with the fact that distant peers often have a smaller ratethannearby peers. We show that the spatial point process describingpeers intheir steady state exhibits an interesting repulsionphenomenon. We studythe implications of this phenomenon by analyzingtwo asymptotic regimes ofthe peer-to-peer network: the fluid regimeand the hard--core regime. We getclosed form expressions for the mean(and in some cases the law) of the peerlatency and the download rateobtained by a peer as well as for the spatialdensity of peers in thesteady state of each regime. The analytical resultsare based on a mixof mathematical analysis and dimensional analysis andhave importantdesign implications.

This is a joint work with FranÃ§oisBaccelli and Ilkka Norros

Future Internet: An information-centric perspective
2011-11-30 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Although the Internet has been designed as a network for thepairwise communication between end hosts, the current traffic-mix revealsthat it is currently used for the massive distribution of information.Based on a host-centric architecture, the Internet serves as acommunication infrastructure interconnecting requests to the informationitself. In view of this model mismatch, the networking community hasstarted to investigate architectures for a Future Internet many of whichrevolve around information-centrism. In this talk, we will provide anoverview of the emerging Information-Centric Networking (ICN) paradigm,highlighting its main features and discussing the ways it offers apromising alternative to the current Internet architecture. We will take aclose look at the current ICN research efforts, including our work in thefield, and point out their commonalities and key differences. Finally, wewill identify key research challenges in the area, fostering furtherdiscussion on the topic.

Biography: Konstantinos Katsaros received hisB.Sc., M.Sc. and Ph.D. degrees in 2003, 2005 and 2010 respectively fromthe Department of Computer Science, Athens University of Economics andBusiness, Greece. His PhD thesis was on content distribution and mobilitysupport in the context of the Information-Centric Networking (ICN)paradigm. His current research is also in the area of ICN, focusing onscalable information discovery and name resolution, policy compliantrouting, packet-level caching and multipath routing. He has also worked inthe areas of multicast and broadcast service provision over next generationcellular networks, mobile grid computing and cognitive radio.

Manipulability of voting systems
2011-11-16 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Voting systems allow competing entities to decide amongdifferent options. In order to ensure fairness between the competingentities, a strong requirement is to avoid manipulability by voters.Unfortunately, strong theoretical results show that, unless using somedegenerated and a priori non-acceptable voting systems such as thedictatorial ones, any other voting system is susceptible to be manipulatedby a single voter! However, very little is know about how much a votingsystem is manipulable. We evaluate different voting systems by quantifyingtheir probability of manipulability on various kinds of voter populations.The results are very general and can be applied in any context where votingsystems can be used.

Practicing interoperability: technical and scientific challenge
2011-11-02 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
A technical and scientific understanding of interoperabilityhas been available for years in the telecom industry. But the practice ofinteroperability needs to evolve because of the speed with which ICTecosystems are created.

This talk will present the reasons why this isthe case and subsequently call for further technical and scientificresearch. The presentation will include the following points. Practice ofinteroperability today Research (e.g. DIEM and ARTEMIS projects) Businesspractices (Handling IPR, Standardisation) Practice of interoperability inthe future ICT ecosystems needs Societal aspects (legal, business,ethical) Technical aspects (platform viewpoint, deployment viewpoint)Engineering aspects (interoperability by design, interoperabilityassurance) Business practices and consensus building (Harvard roadmap)Discussion

Biography: Antonio Kung has 30-year experience in embeddedsystems. He was initially involved in the development of real-timekernels, before co-founding Trialog in 1987, where he now serves as CTO.He heads the company product development (kernels, protocols, tools) aswell as collaborative projects with a focus on embedded systems, securityprivacy trust and ICT for ageing. He is involved in the promotion ofinitiatives towards common platforms and interoperability. He holds aMaster's degree from Harvard University and an Engineering degree fromEcole Centrale Paris.

Resilient networking and resource management in IP networks
2011-10-21 10:30 - 11:30 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Resilience analysis in packet-based communication networksquantifies the risk of link overload due to rerouted traffic and the riskof disconnectivity. Proactive optimization of routing and rerouting mayreduce the first risk, improvement of the network topology the second one.Recently, IP fast reroute mechanisms have been suggested by the IETF.Loop-free alternates (LFAs) are simple, but they may not cover all singleelement failures. The IETF has recently defined Pre-Congestion Notification(PCN) for Differentiated Services networks. It uses simple load-dependentpacket re-marking to communicate load conditions to edge. This informationis used for admission control and flow termination. The latter is useful toremove overload that occurs in spite of admission control due unexpectedevents. However, termination can be avoided if admissible rate thresholdsare set low enough, which is the principle of resilient admission control.Today's access networks suffer from a minority of heavy users who areresponsible for most traffic and compromise the quality of experience for amajority of light users. Some ISPs rate-limit the user access, others usedeep packet inspection to classify and downgrade some traffic whichviolates network neutrality. To tackle that problem, the IETF definesCongestion Exposure (ConEx). It makes congestion visible to any IP devicealong a flow's path. This information may be used to throttle the useraccess to achieve per-user fairness rather than per-flow fairness, toimprove traffic engineering, and to enhance SLAs.

Biography:Michael Menth is a full professor at the Department of Computer Science atthe University of Tuebingen/Germany and head of the Communication Networkschair. He received a Diploma and PhD degree in 1998 and 2004 from theUniversity of Wuerzburg/Germany. Prior he was studying computer science atthe University of Texas at Austin and worked at the University ofUlm/Germany. His special interests are performance analysis andoptimization of communication networks, resource management, resilienceissues, and Future Internet. He holds numerous patents and receivedvarious scientific awards for innovative work.

Bufferbloat
2011-10-19 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Bufferbloat - Identification, analysis, tools for analyzingoverly deep buffering across the (mostly wireless) internet, with somepotential for solutions. For an introduction to the bufferbloat problem,see Jim Gettys'talk:

http://gettys.wordpress.com/2011/06/02/google-techtalk-video-is-up/

This talks reportes latest update of work in progress, more informationis available online at http://lwn.net/Articles/458625/ orhttp://www.bufferbloat.net/

How can the Internet help smarten the grid
2011-09-29 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
This seminar presents the research activities on Smart Grids ofthe Information Systems and Sciences for Energy (ISS4E) laboratoryco-founded by Professors Rosenberg and Keshav at University of Waterloo.After a brief introduction on smart grids and their similarities with theInternet, two research projects will be presented. The first is ondimensioning transformers and storage using probabilistic analysis. Thesecond one, on demand response, proposes a solution to take advantage ofthe elasticity inherent to most of the major home appliances. All theseprojects are conducted in collaboration with Prof. Keshav and graduatestudents.

Biography: Catherine Rosenberg is a Professor in Electricaland Computer Engineering at the University of Waterloo. Since June 2010,she holds the Canada Research Chair in the Future Internet. She started hercareer in ALCATEL, France and then at AT&T Bell Labs., USA. From1988-1996, she was a faculty member at the Department of Electrical andComputer Engineering, Ecole Polytechnique, MontrÃ©al, Canada. In1996, she joined Nortel Networks in the UK where she created and headedthe R&D Department in Broadband Satellite Networking. In August 1999,Dr. Rosenberg became a Professor in the School of Electrical and ComputerEngineering at Purdue University where she co-founded in May 2002 theCenter for Wireless Systems and Applications (CWSA). She joined Universityof Waterloo on Sept 1st, 2004 as the Chair of the Department of Electricaland Computer Engineering for a three-year term. Catherine Rosenberg is onthe Scientific Advisory Board of France-Telecom and is a Fellow of theIEEE.

On leveraging social informatics for cyber security
2011-08-05 10:00 - 11:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
A fundamental challenge of trustworthy computing is to developa systematic and yet practical/usable approach on determining whether ornot, and how much a piece of information (e.g., software program orinformation content) should be trusted. The focus of this talk is our trustmanagement architecture, called DSL (Davis Social Links) based on socialinformatics, i.e., information about human social relationships and theinteractions based on those relationships. Under the DSL architecture, wewill discuss how to enhance the trustworthiness of distributed applicationsrunning on top of today's Internet, and furthermore, how to re-design abrand new trustworthy Internet architecture based on social informatics.The speaker will perform some small demos during his talk.

Mutual impact of traffic correlation and regenerator concentrationin translucent WDM networks
2011-06-30 15:00 - 16:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Since the early 2000s, a real attention is paid to physicalimpairments arising in large-scale optical networks. One cost-effectivesolution to cope with transmission impairments is to deploy 3R(re-amplifying, re-shaping, and re-timing) regenerators in a limitednumber of network nodes (i.e., translucent networks). Taking into accountthe simultaneous effect of four transmission impairments (amplifiedspontaneous emission, chromatic dispersion, polarization modedispersion, and nonlinear phase shift), we propose a novel exact approachfor impairment-aware network planning. In contrast with previous works, weinvestigate the problem under pre-planed dynamic traffic. Our proposaltakes advantage of the dynamics of the traffic pattern so that regenerationresources may be shared among non-concurrent requests. Given a networktopology and a set of pre-planned requests, we target the minimum numberof regenerators or/and regeneration sites. Thanks to an ILP formulation ofthis problem, we outline through the obtained numerical results the mutualimpact between the time-correlation of the requests and the level ofregenerators' concentration.

Joint work with E. Doumith and S. Al Zahr

Modeling and blocking probability evaluation for multi-prioritycircuit switched optical networks
2011-06-30 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
It is expected that circuit switching (CS) will play animportant major role in future optical networks. CS normally does notrequire buffering which is very costly in the optical domain. If thetraffic on a CS network is well managed CS networks can guarantee qualityof service (QoS) to customers in a way that can even lead to efficient linkutilization and low consumption of energy per bit. In the core Internet,where traffic is heavily multiplexed, it is easier to achieve highutilization and therefore the role of CS at the core is clearly important.However, CS can also lead to a green and efficient operation end-to-endfor large bursts of data. Accurate, robust and scalable blockingprobability evaluation is an important element in CS traffic management. Weconsider an optical network that uses various circuit-switching basedtechnologies such as OCS and OFS. We model it as two-prioritycircuit-switched network with non-hierarchical alternate routing. Weevaluate the blocking probability using algorithms based on the ErlangFixed-point Approximation (EFPA) and the Overflow Priority ClassificationApproximation (OPCA). For a particular example of a 6-node fully meshednetwork with alternate routing, we compare numerically between OPCA overEFPA and discuss traffic implications.

Biography: Moshe Zukermanreceived his B.Sc. in Industrial Engineering and Management and his M.Sc.in Operation Research from Technion-Israel Institute of Technology and aPh.D. degree in Engineering from The University of California Los Angelesin 1985.During 1986-1997 he served in Telstra Research Laboratories (TRL).During 1997-2008 he was with The University of Melbourne. In Dec 2008,hejoined City University of Hong Kong where he is a Chair Professor ofInformation Engineering. He has served on the editorial boards of variousjournals such as IEEE JSAC, IEEE/ACM Transactions on Networking, IEEECommunications Magazine, Computer Networks and Computer Communications.Prof. Zukerman has over 300 publications in scientific journals andconference proceedings, has been awarded several national andinternational patents, two conference best paper awards and honoraryProfessorships at CCNU, Wuhan. CityU, Hong Kong and BJTU, Beijing. He isa Fellow of the IEEE and has served as a member and Chair of the IEEE KojiKobayashi Computers and Communications Award Committee.

Recursive quantum repeater networks
2011-03-31 14:00 - 15:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Internet-scale quantum repeater networks will be heterogeneousin physical technology, repeater functionality, and management. Theclassical control necessary to use the network will therefore face similarissues as Internet data transmission. Many scalability and managementproblems that arose during the development of theInternet might have beensolved in a more uniform fashion, improving flexibility and reducingredundant engineering effort. Quantum repeater network development iscurrently at the stage where we risk similar duplication when separatesystems are combined. We propose a unifying framework that can be used withall existing repeater designs. We introduce the notion of a QuantumRecursive Network Architecture, developed from the emerging classicalconcept ofRECURSIVE NETWORKS, extending recursive mechanisms from a focuson data forwarding to a more general distributed computing requestframework. Recursion abstracts independent transit networks as single relaynodes, unifies software layering, and virtualizes the addresses ofresources to improve information hiding and resource management. Ourarchitecture is useful for building arbitrary distributed states,including fundamental distributed states such as Bell pairs and GHZ, W,and cluster states.

Biography: Rodney VAN METER received aB.S. in engineering and applied science from the California Institute ofTechnology in 1986, an M.S. in computer engineering from the University ofSouthern California in1991, and a Ph.D. in computer science from KeioUniversity in 2006.His research interests include storage systems,networking, andpost-Moore's Law computer architecture. He has heldpositions in both industry and academia in the U.S. and Japan. He is now anAssociate Professor of Environment and Information Studies at KeioUniversity's Shonan Fujisawa Campus. Dr. Van Meter is a member of AAAS,ACM and IEEE.

Seeking simplicity in complex systems
2011-02-10 11:00 - 12:00 | LINCS Meeting Room 40, 23, avenue d'Italie, Paris, 75013,France
Queueing network models are an important tool in the evaluationof the performance of computer systems and networks. Explicit analyticalsolutions exist for a class of such models, but features such as realisticglobal dependencies, priorities, or simple commonly used servicedisciplines, preclude their direct application. Additionally, even whensuch solutions are known, their numerical computation may still bechallenging due to the size of the state space of classical queueingmodels.

In this talk, we try to show that the use of conditionalprobabilities may be valuable in exposing simple properties hidden fromview by classical state descriptions. Examples include tandem networks withblocking, multiclass models, multi-server systems with priorities, aswell as guided state sampling in large systems.

Spanners de graphes
2011-01-12 14:00 - 15:00 | LINCS Seminars room, 23, avenue d'Italie, Paris, 75013,France
Etant donné un graphe G, un spanner est un sous graphe H quicouvre tous les sommets de G. On s’intéresse alors à deuxparamètres: la distance dans H par rapport à la distance dans G, et lataille de H en nombre d'arêtes. L'optimisation simultanée de ces deuxparamètres conduit à des compromis que nous mettrons enévidence.

Tags : Laurent Viennot, Inria, Spanners de graphes,spanner
