Uplink performance analysis of multicell MU-MIMO with zero-forcing receivers and perfect CSI

We consider the uplink of a multicell multiuser MIMO system. The data detection is done by using the zero-forcing (ZF) technique, assuming the base station has perfect channel state information. We derive an exact closed-form expression for the uplink rate per user. We further study the asymptotic performance of the system. We show that, at high signal-to-noise ratio, the system is interference-limited and hence, we cannot improve the system performance by increasing the transmit power at each user. Instead, by increasing the number of base station antennas, the effects of interference and noise can be reduced, thereby improving the system performance. In particular, we show that, with very large antenna arrays at the base station, the transmit power of each user can be made inversely proportional to the number of base station antennas while maintaining a desired quality-of-service. Numerical results verify our analysis.