ISAC Hybrid Beamforming With Low-Resolution DACs

Next generation wireless communications demands for the effective use of the power spectrum to save cost and reduce power consumption. In this respect, integrated sensing and communications (ISAC) has emerged to employ a shared spectrum on a common hardware for radar sensing and wireless communications. Besides, the use of low resolution analog-to-digital digital-to-analog converters also useful to reduce power consumption. Therefore, this paper presents the design of hybrid analog/digital beamformers with low resolution digital-to-analog converters (DACs) for ISAC scenario, wherein the base station generates multiple beams toward both radar targets and communication user. We propose an alternating optimization approach, wherein the quantization distortion is taken into account in order to design the baseband beamformer with low resolution DACs. Then, the analog beamformer is obtained such that the overall design simultaneously generates multiple beams toward both communication user and the radar targets. We evaluated performance of the proposed technique in terms of both spectral efficiency and sensing beampattern, providing a satisfactory sensing and communication performance for both one-bit and few-bit designs.