Maximum expected achievable rate combining for limited feedback block-diagonalization

We consider downlink multi-user MIMO transmission based on block-diagonalization precoding with quantized channel state information at the transmitter, obtained through limited feedback. We assume that users are equipped with excess receive antennas, i.e., the number of receive antennas is larger than the number of data streams per user, and propose a novel receive antenna combining method that maximizes an estimate of the expected achievable user rate. By means of simulations, we validate our assumptions and demonstrate significant rate gains compared to existing combiners of similar complexity.