Multiuser MISO Interference Channels With Single-User Detection: Optimality of Beamforming and the Achievable Rate Region

For a multiuser interference channel with multi-antenna transmitters and single-antenna receivers, by restricting each transmitter to a Gaussian input and each receiver to a single-user detector, computing the largest achievable rate region amounts to solving a family of nonconvex optimization problems. Recognizing the intrinsic connection between the signal power at the intended receiver and the interference power at the unintended receiver, the original family of nonconvex optimization problems is converted into a new family of convex optimization problems. It is shown that, for such interference channels with each receiver implementing single-user detection, transmitter beamforming can achieve all boundary points of the achievable rate region.