Efficient uplink transmission in multiuser MIMO systems using uplink-downlink duality and hybrid optimization

We propose an efficient multiuser MIMO (MU-MIMO) uplink transmission scheme based on a two-stage iterative joint optimization process in the dual downlink, followed by an uplink transformation. The hybrid optimization consists of multiuser interference (MUI) mitigation complemented by sum mean-square error (SMSE) minimization under a sum-power constraint to enhance the average bit-error rate (BER) performance in the MU-MIMO uplink. The proposed algorithm is capable of providing high diversity gain when the transmitters are equipped with multiple antennas and converges exceptionally fast, requiring only a few iterations to achieve its maximum performance potential. We also consider a codebook based transmission mechanism for practical implementation of the proposed scheme.