Hybrid precoding for multi-user mmWave systems based on MMSE criterion

Abstract

Millimeter wave (mmWave) communication has been considered as a key technology for future 5G or beyond wireless communication systems due to its huge spectrum bandwidth and great potential when combined with the large scale antenna technology. Considering the new challenge of high hardware cost and huge power consumption with the increase of bandwidth and number of antennas, hybrid digital and analog signal processing has been receiving a lot of interest recently. This paper investigates the hybrid precoding for multi-user communication in a downlink mmWave system, aiming at minimizing the sum of the users' mean square errors (sum-MSE) with the constraints of maximum transmit power and constant modulus for the phase shifters in the radio frequency precoding block. A two-stage optimization scheme is proposed to obtain a near-optimal solution. Simulation results show that the proposed hybrid precoding scheme performs closely to the fully digital precoding scheme.