A probabilistic-constrained leakage-based beamforming for downlink multiple stream MU-MIMO system

Multi-user multiple-input and multiple-output (MU-MIMO) wireless system has the potential to provide a substantial gain by using transmit beamforming. The main challenge for transmit beamforming design is to suppress the interference from other users/data with imperfect channel state information at transmitter (CSIT). We propose a probabilistic-constrained beamforming design that combines the SLNR criteria with Alamouti coding for the multiple-stream-per-user MU-MIMO system. The proposed beamformer maximizes the average system performance and exterminates inter-data-interference while guaranteeing a low outage probability of serious leakage power performance. Simulation results show that the proposed beamformer achieves the highest signal-to-interference-and-noise ratio (SINR) reliability and provides the strongest robustness against channel imperfections, among the state-of-art transmit beamformers.