EFFICIENT FEEDBACK FOR MIMO CHANNELS WITH TIME AND SPATIAL CORRELATION

Abstract

In this paper, we consider limited feedback for MEMO channels that have time and spatial correlation. The bit loading is dynamically assigned according to the channel condition and fed hack to the transmitter to achieve an adaptive rate. To take advantage of the time correlation of the channel, the bit loading is predictively coded for feedback. The precoder is designed according to the statistics of the channel and it requires no feedback. We derive the optimal predictor of bit loading that minimizes the mean squared prediction error in this case and present a practical feedback scheme based on the optimal predictor. With a small feedback rate the proposed statistical preceding and predictive quantization of bit loading can achieve a performance very close to the case when there is no quantization on bit loading.