A multi user beamforming scheme for downlink MIMO channels based on maximizing signal-to-leakage ratios

Multi-user multiple-input multiple-output (MU-MIMO) wireless systems can provide a substantial gain in network downlink throughput by allowing multiple users to communicate in the same frequency and time slots. The challenge is to design transmit beamforming vectors for every user while limiting the co-channel interference (CCI) from other users. One approach is to perfectly cancel the CCI at every user, which requires a relatively large number of transmit antennas. In this paper, we consider an alternative approach based on maximizing the signal-to-leakage ratio (SLR) for designing transmit beamforming vectors in a multi-user system. One advantage of the proposed scheme is that it does not impose a restriction on the number of available transmit antennas; it also outperforms the conventional beamforming scheme.