Effects of Spectral Variations and Environmental Conditions on the Performance of Massive MIMO Systems

The paper is devoted to massive multiple-input multiple-output (MIMO) systems over a band of operation from 4.22 to 4.38 GHz. An investigation of the massive MIMO system performance is presented. The effect of rough surface boundaries, spectral fluctuations, and variable number of terminals onto the overall system performance is examined in terms of the throughput per user and the channel matrix singular value spread (SVS). It is found that as the rough surface height standard deviation increases, the obtained channel matrix SVS indicates ill-conditioning with more difficult situations for spatial separation of users' signals. In addition, significant reductions in the channel capacity and larger disparities of the power values designated for users' channels are noticed. When the operating frequency increases, the channel stability reduces due to phase variations. This is observed through considerable increases in the channel matrix SVS and remarkable degradations in the channel capacity since the electrical propagation distance is larger at higher frequencies. When the number of users grows, the channel matrix SVS increases due to the reduction in the per-user throughput. The adopted simulation results agree with the experimental results in literature.