Performance of Vector Perturbation Multiuser MIMO Systems over Correlated Channels

This paper considers the performance of the multiuser multi-antenna downlink where N_T base station antennas transmit to K non-collocated, single antenna users over correlated channels. A practical and near-capacity multi-user technique called vector perturbation precoding (VPP) is considered. For these scenarios, we derive a lower bound to the average energy of the precoded vector. We use this to approximate the effective noise gain at the receivers due to the presence of transmit side correlation. Furthermore, we obtain simple approximations for the noise gain for constant and exponential transmit correlation models. Simulation results show that our approximations predict the performance loss due to correlation remarkably well regardless of the correlation parameter.