Low Complexity Scheduling and Beamforming for Multiuser MIMO Systems

The problem of joint scheduling and beamforming for a multiple antenna broadcast channel with partial channel state information at the transmitter (CSIT) is considered. We show how long-term statistical channel knowledge can be efficiently combined with instantaneous low-rate feedback for user selection and linear beamforming. A low complexity algorithm based on an estimate (bound) of the multiuser interference is proposed. Our scheme is shown to exhibit significant throughput gain over opportunistic techniques, approaching the sum rate of full CSIT for small angle spreads