Line-of-Sight and Pilot Contamination Effects on Correlated Multi-Cell Massive MIMO Systems

This work considers the uplink (UL) of a multicell massive MIMO system with L cells, having each K monoantenna users communicating with an N-antennas base station (BS). The channel model involves Rician fading with distinct per-user Rician factors and channel correlation matrices and takes into account pilot contamination and imperfect CSI. The objective is to evaluate the performances of such systems with different single-cell and multi-cell detection methods. In the former, we investigate MRC and single-cell MMSE (S-MMSE); as to the latter, we are interested in multi-cell MMSE (MMMSE) that was recently shown to provide unbounded rates in Rayleigh fading. The analysis is led assuming the infinite N limit and yields informative closed-form approximations that are substantiated by a selection of numerical results for finite system dimensions. Accordingly, these expressions are accurate and provide relevant insights into the effects of the different system parameters on the overall performances.