Vector perturbation precoding and user scheduling for network MIMO

In this paper, we apply vector perturbation (VP) precoding to a network multiple-input multiple-output (MIMO) scheme, in which downlink transmissions from base stations are coordinated. We propose a multi-cell VP by introducing a common power scaling factor for all base stations in order to satisfy per base station power constraint. In our scenario, we consider multiple-antenna users with heterogeneous signal-to-noise ratios (SNRs). Our work is an extension of earlier work on VP to a multi-cell network with multiple-antenna users. The sum rate for the multi-cell VP in the case of uniformly distributed input is obtained and an asymptotic upper bound for it is proposed. The results show that the multi-cell VP is superior to the multi-cell block diagonalization (BD). By using the upper bound on the sum rate, we propose a user scheduling algorithm, which provides better performance and is less complex than semi-orthogonal user selection in the case of multiple-antenna users (SUS-MA).