In the current work we deal with the problem of base station cooperation in the downlink of infinite wireless cellular networks.The positions of base stations are modeled by a Poisson point process. Each base station can choose to cooperate or not with exactly oneof its Delaunay neighbours 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.We analytically derive closed form expressions for the coverage probability and we determine the optimal cooperation zones in the network.Numerical evaluation shows benefits in coverage, compared to the common cellular architecture. These however are not very high due to thedeterioration in SINR caused by increased outer-cell total interference. Joint work with F. Baccelli.