A Beam Steering Based Hybrid Precoding for MU-MIMO mmWave Systems

We propose a hybrid precoding scheme for downlink multi-user multiple-input multiple-output (MU-MIMO) millimeter-wave (mmWave) systems. Firstly, the proposed precoder is designed by the beam steering condition and the zero-interference condition, which can be obtained with the information of angles of departure (AoDs) in frequency division duplex (FDD) systems. Then, the proposed precoder is decomposed into the radio frequency (RF) precoder and the baseband precoder without the loss of response. Also, array response vector selection algorithm is proposed to prevent the sum rate degradation in numerous users region. Simulation results show that the sum rate of the proposed hybrid precoder is higher than those of the block diagonalization (BD) based schemes in the region of more than 5 users and approaches the sum rate of the beam steering scheme without MU interference as the number of base station (BS) antennas increases.