Zero-forcing receiver in uplink massive MIMO

This paper studies an uplink massive MIMO system that employs zero-forcing (ZF) receiver and pilot reuse. Although with infinity number of antennas it has been shown that maximum ratio combining (MRC) attains the same throughput as ZF, we find that for antenna number as large as 100, ZF attains significant throughput gain over MRC. A tight lower bound is derived for cell throughput attained by ZF, characterizing three interference terms: intra-cell interference, inter-cell interference, and interference due to pilot contamination, where the three interference regimes of ZF are compared against with MRC. Numerical simulations are conducted to gain insight for the relation among the optimal cell throughput, pilot reuse number, number of base station antennas and the network topology. Extension to arbitrary network typologies are briefly discussed.