Throughput of precoded broadcast transmission with noisy feedback

Transmitter precoding strategies achieve a large portion of the capacity promised in broadcast MIMO systems. However, these schemes generally require perfect channel information at the transmitter. In this paper, the impact of Gaussian additive noise in the channel information is investigated for a downlink system where the transmitter uses a zero forcing precoding strategy. It is shown that noise in the channel state information (CSI) induces T-distributed multiplicative noise at the receiver. The multiplexing gain and power offset of the scheme are calculated and compared against the corresponding perfect feedback system.