Joint Transmit and Receive Beamforming for Multiuser MIMO Downlinks With Channel Uncertainty

摘要

In this paper, we develop a novel joint transmit and receive design for multiuser multiple-input-multiple-output (MU-MIMO) systems. By exploiting channel temporal correlations, the proposed scheme incorporates a matched-filter (MF) combining vector into the beamformer design and enhances the performance of conventional signal-to-leakage-plus-noise ratio (SLNR) beamforming. With imperfect channel state information (CSI) available at the transmitter, we then focus on improving the robustness of the proposed algorithm against the mismatched CSI. The feedback delay effect is considered in the beamformer design first. We design a statistically robust beamforming design by maximizing the conditional expectation of the SLNR, hence alleviating the performance degradation due to CSI errors. Following that, we further encompass the imperfection caused by the quantized feedback into the beamforming design. Moreover, we also develop efficient power allocation techniques to further improve the sum-rate performance. Finally, we extend the proposed robust joint transmit and receive design to multicell MIMO systems. Simulation results verify the effectiveness of our algorithm under various scenarios.