Polyblock Algorithm-Based Robust Beamforming for Downlink Multi-User Systems With Per-Antenna PowerConstraints

摘要

In this paper, we investigate the robust beamforming for multi-user multiple-input single-output systems underquantized channel direction information (CDI) with per-antenna power constraints. The robustness of the consideredbeamforming design is achieved in the sense that the stochastic interference leakage is below a certain level by a givenprobability. Our design objective is to maximize the expectation of the weighted sum-rate performance. From thediscussion of the non-robust optimal beamforming based on the polyblock algorithm, we propose a robust beamformingscheme for the quantized CDI case with per-antenna power constraints. In the proposed beamforming scheme, we useJensen's inequality to generate a tractable feasibility problem for the polyblock algorithm and apply the semi-definiteprogramming relaxation, as well as the randomization technique to find its approximate rank-one matrix solution and userequipments' beamforming vectors. Simulation results show that substantial gains can be achieved by the proposed schemecompared with the existing schemes in terms of the average weighted sum-rate performance. Although very high complexityis required for the implementation of the proposed scheme, it stands as a good benchmark for robust beamformingdesigns.