Limited transmitter cooperation in adjacent broadcast channels

We discuss the scenario of two interfering broadcast channels that are not able to jointly precode the data symbols, but are allowed to cooperate in choosing their precoders. The multiplexing gain achievable by zero-forcing with this type of limited cooperation is derived. When the transmitters do not cooperate at all, but compete for the resources, the system is shown to be interference limited and the multiplexing gain is always zero. We furthermore present a distributed algorithm based on exchanging interference prices, that achieves the full multiplexing gain, but also performs well if the additive noise is not asymptotically low. It is numerically shown that limited cooperation yields great performance gains over competitive behavior if the interference is strong compared to the additive noise.