Zero-Forcing Beamforming With Signal Space Diversity

Abstract

We integrate zero-forcing beamforming (ZFBF) with signal space diversity (SSD) and investigate its performance. The beamforming is applied at the transmitter assuming a closed-loop scenario. First, a dual-stream transmission scheme with M (M >= 2) transmit and two receive antennas is studied. Then, a generalization for any number of simultaneous substreams is established based on the previous results. A statistical analysis of the proposed scheme is provided and an exact closed-form expression on the average bit error probability is derived. We also present a high signal-to-noise ratio analysis for gaining further insight into diversity level and coding gain of the proposed system. It is shown that the error performance of a ZFBF system can be improved by making use of SSD with only a negligible increase in complexity and no extra use of bandwidth/time resources.