WLC11-5: Joint Power Control and Beamforming for Sum-Rate Maximization in Multiuser MIMO Downlink Channels

This paper addresses the problem of maximizing the sum-rate with a total power constraint for a multiuser multiple-input multiple-output (MIMO) antenna system in the downlink using generalized beamforming. Channel state information at the transmitter (CSIT) and the receivers (CSIR) is assumed available. An iterative approach is proposed which alternates between optimizing the power allocation, transmit antenna vectors and receive antenna vectors using a combination of geometric programming (GP), signomial programming (SP), uplink-downlink duality and minimum mean-square-error (MMSE) receiver optimization. It is proved that the sum-rate in the proposed scheme has a monotonic increasing property and hence the algorithm is convergent. Simulation results show that this algorithm can significantly increase the sum-rate compared with a zero-forcing solution.