Bit allocation and statistical precoding for correlated MIMO channels with limited feedback

Abstract—In this letter, we jointly consider statistical precoding and statistical bit allocation for correlated MIMO channels. Given the statistics of the channel, we derive statistical BER bounds for high and low SNR ranges. Based on the BER bounds, statistical precoder and statistical bit allocation are designed. The statistical precoder helps to expose the statistical difference among the sub-channels, which is then exploited by bit allocation. Moreover, we will incorporate bit allocation in determining detection ordering for the decision feedback receiver and present a suboptimal or-dering for minimizing the worst subchannel error rate. The subop-timal solution can be implemented efficiently bymodifying existing fast algorithms developed for uniform bit allocation. Although the statistical precoder and bit allocation are designed for high and low SNR ranges, very good performance can be achieved for all SNR. Simulations show that the performance of the proposed system is comparable to one that has instantaneous feedback rate of around 4 bits per channel. I