Sum rates for regularized multi-user MIMO vector perturbation precoding

In this paper, we analyze the sum rate performance of multiuser multi-antenna downlink channel. We consider Rayleigh fading environment when regularized vector perturbation precoding (R-VPP) method is used at the transmitter. The sum rate characterization of R-VPP is difficult because of the correlation between the multiuser interference and the data symbols. We derive expressions for the sum rate in terms of the variance of the received signal. We also provide a closed form approximation for the mean squared error (MSE) which is shown to work well for the whole range of SNR. Further, we also propose a simpler expression for R-VPP sum rate based on MSE. The simulation results show that the proposed expressions for R-VPP sum rate closely match the sum rate found by the entropy estimation, and also confirm that R-VPP performs very close to dirty paper coding (DPC) for all SNR values.