Weighted Sum-Rate Maximization for RIS-Assisted MU-MIMO Communication Systems with Low-Resolution ADCs/DACs

This paper focuses on maximizing the weighted sum-rate (WSR) in downlink communication systems that uti-lize reconfigurable intelligent surfaces (RIS) to enhance MU-MIMO transmission. To reduce implementation costs and power consumption, low-resolution ADCs/DACs are configured at the BS. Unlike the traditional design that predicated on perfect channel state information (CSI), we establish a WSR optimization problem given imperfect estimated CSI. Specifically, based on imperfect statistical CSI, we propose a robust weighted minimum mean square error (WMMSE) algorithm to maximize the beam-forming matrix, and then use riemann conjugate gradient (RCG) algorithm to optimize the phase shift vector with the aim of maximizing the WSR for all users. Numerical examples indicate that the proposed scheme improves system's robustness as well as achieves optimal WSR performance using three quantization bits.