Hybrid Beamforming With Discrete Phase Shifters for Millimeter-Wave Massive MIMO Systems

Hybrid digital and analog beamforming design has been the focus of considerable interest in the context of millimeter-wave massive multiple-input multiple-output systems because such a design can provide a flexible compromise between hardware complexity and system performance. However, most existing hybrid beamforming designs usually assume that infinite resolution phase shifters (PSs) are available to produce analog beamformers. In a practical sense, the employment of such shifters with arbitrary phase is infeasible or, at least, is expensive because of hardware limitations. We propose an iterative hybrid transceiver design algorithm, where PSs can only supply discrete phase adjustments, to facilitate low-cost implementation of the analog beamformers via finite resolution PSs while maximizing spectral efficiency. Simulation results reveal that the performance of the proposed algorithm with low-resolution PSs is close to that of the state-of-the-art algorithm with infinite resolution PSs.