Hybrid Beamformer Design with Low-Resolution Phase Shifters in MU-MISO SWIPT Systems

Simultaneous wireless information and power transfer (SWIPT) is considered as a promising solution to offer convenient energy supplies to wireless devices. On the other hand, analog/digital hybrid beamforming, which can dramatically reduce power consumption, has been deemed as an energy efficient transceiver architecture. This paper investigates the problem of hybrid beamforming design with low-resolution PSs to achieve an energy efficient multi-user multi-input single-output (MUMISO) SWIPT system. Particularly, a base-station (BS), which is equipped with multiple antennas and hybrid beamforming architecture, simultaneously transfers information to one singleantenna information receiver (IR) and power to K distributed single-antenna energy receivers (ERs). While the IR has a target signal-to-noise ratio (SNR) requirement to assure the quality of service (QoS) of transmission, the K ERs have certain thresholds of receive signal power to guarantee the energy harvesting. We propose a novel iterative hybrid beamforming design algorithm to find the analog beamformer with constant amplitude and lowresolution phase constraints and the digital beamformer which can minimize the transmit power under both IR and ERs' requirements. Simulation results validate the effectiveness of the proposed hybrid beamforming design algorithm in the MU-MISO SWIPT systems.