Spatial Uplink Power Control for Massive MIMO

This paper proposes a novel uplink power control scheme in a single cell for massive MIMO (Multiple-Input-Multiple-Output). The proposed algorithm exploits the spatial degrees of freedom provided by massive MIMO to achieve the highest signal to interference-plus-noise ratio (SINR) for each user by considering the mutual spatial correlation arising from other users. It also minimizes the required uplink transmit power to achieve the highest possible uplink SINR per user without increasing the complexity at the user equipment. The base station (BS) controls the user transmit power using only two bits in a Transmission Power Control (TPC) command and the newly introduced algorithm is expected to increase both the energy efficiency (EE) and single cell spectral efficiency (SE) with reduced transmission overhead, latency and complexity in the receiver. Through recent preliminary trials, a 0.9 dB average SINR increase was achieved, and transmit power was decreased by up to 2.5 dB in the uplink. The proposed algorithm supports several popular linear MIMO decoders and precoders including Minimum Mean Square Error (MMSE), Zero-Forcing (ZF) and Matched Filtering (MF).