Non-iterative multiuser MIMO coordinated beamforming with limited feedforward

This paper proposes non-iterative coordinated beamforming algorithms for a multiuser MIMO (multiple input multiple output) system with multiple antennas at the transmitter and multiple users, each with multiple receive antennas. The transmitter uses linear beamforming to convey information to each user, while each receiver uses a quantized combining vector, sent from the transmitter via a low-rate feedforward control channel. Two different algorithms for optimizing transmit beamformers and receive combining vectors are proposed: a joint optimization and a greedy search. Simulations show that the proposed methods using quantized codebooks approach the sum capacity of the MIMO broadcast channel.