Area performance of multi-cell massive MIMO system under Ricean fading

Wireless network design is characterized by multiple performance objectives. In this work, we consider the performance of downlink transmit beamforming in multi-cell massive MIMO systems under Ricean propagation. Deliberations are made on variation of Ricean factor in controlling the transmit beamforming for mitigating multi-cell contamination. We propose downlink Zero Forcing (ZF) beamforming scheme, that is user location-dependent especially at cell edge. The crux is to adjust the base station power for users close to cell edges. Exploiting random matrix theory, mathematical conclusions for the per cell area rate, Ricean factor and transmit power are established in closed form expressions. Simulation results show accuracy of the bounds and performance of the ZF beamforming with massive MIMO channels. The results demonstrate the proposed ZF beamforming outperforms the conventional ZF beamforming, hence resolves the impact of contaminations from neighboring cells. The rate gain is dependent on Ricean factor and user location, but independent of cell size.