Reduced-Complexity and Robust Uplink Signal Processing for Large-Scale MIMO

The large number of individually controlled antennas in large-scale MIMO systems makes the complexity of uplink receive combining a serious challenge. This is why simple methods, such as maximum ratio combining, are often considered, even if lower spectral efficiency is attained. In this paper, we investigate the performance of a reduced-complexity combining scheme that exploits second-order statistics of the channel. Compared to maximum ratio combining, substantial improvements are achieved, especially when the number of active terminals increases. This is attained with limited computational cost and remarkable robustness to the imperfect channel statistics knowledge.