Downlink Performance of Massive MIMO under General Channel Aging Conditions

Massive multiple-input multiple-output (MIMO) is a promising technology aiming at achieving high spectral efficiency by deploying a large number of base station (BS) antennas using coherent combining. Channel aging due to user mobility is a significant degrading factor of such systems. In addition, cost efficiency of massive MIMO is a prerequisite for their deployment, that leads to low cost antenna elements inducing high phase noise. Since phase is time-dependent, it contributes to channel aging. For this reason, we present a novel joint channel-phase noise model, that enables us to study the downlink of massive MIMO with maximum ratio transmission (MRT) precoder under these conditions by means of the deterministic equivalent of the achievable sum- rate. Among the noteworthy outcomes is that the degradation due to user mobility dominates over the effect of phase noise. Nevertheless, the impact of phase noise can be eliminated as we increase the number of separate independent local oscillators, i.e., massive MIMO can be robust regarding phase noise.