Sum Rate Analysis for Precoder Design in Distributed MIMO Systems Over Composite Fading Channels

In this paper, we consider the distributed multiple-input multiple-output systems which experience both the small-scale and large-scale fading. By employing the Rayleigh-lognormal model to characterize the composite fading channels, we derive the uplink sum rate in terms of the signal-to-noise ratio for zero forcing (ZF) and ZF decision feedback receivers, respectively. Afterwards, we propose an optimal power loading strategy by constructing an optimization problem that maximizes the dominant term of the sum rate. Then on this basis, a two-stage precoder is designed to further improve the performance, where only the first and second order statistics of the channels are needed at the transmitters. Numerical simulations testify the effectiveness of the analytical sum rates and present the superiority of our optimal power loading strategy as well as the two-stage precoder.