On Phase Precoding and Feedback Design for ML-Detected V-BLAST Systems

The maximum-likelihood (ML)-detected vertical bell-labs layered space-time (V-BLAST) architecture over a Nakagami-m fading channel is considered. This fading model encompasses many fading scenarios as special cases (e.g., Rayleigh). The ML detection of BLAST systems waives the requirement of not having smaller number of receive antennas than transmit antennas: a primary limitation using other sub-optimal linear processing receivers. Using exact BER expressions, a two-by-one antipodal V-BLAST system is optimized by phase precoding requiring only a single bit of feedback from the receiver. Numerical results demonstrate that the proposed single-bit feedback scheme improves the BER performance dramatically.