Comparison of practical feedback algorithms for multiuser MIMO

We consider the problem of channel state information (CSI) transmission on a fast feedback link for a multiuser MIMO system. We examine the relative merits of channel feedback schemes based on Shannon's source-channel separation theorem and non-separation based schemes and show that the latter are preferable in this application. For the non-separation based schemes, we first consider a simple analog transmission and then develop a hybrid digital-analog transmission scheme which quantizes the CSI using a few bits and sends these bits and also the quantization error using analog transmission. We show that the hybrid scheme achieves a higher throughput compared to both analog and digital transmissions and has a much lower computational complexity compared to a digital scheme.