Multi-Cell mMIMO IRS Systems with Impairments and Aging: Phase Optimization and Receiver Design

We consider the uplink of a hardware-impaired intelligent reflective surfaces (IRS) aided multi-cell massive multiple-input multiple-output (mMIMO) system with mobile user equipments, whose channel age with time. For this system, we design a novel distortion-and-aging-aware MMSE (DAAMMSE) receiver that not only provides a higher spectral efficiency (SE) than conventional maximal ratio and distortionunaware MMSE (DU-MMSE) receivers, but also reduces the pilot overhead. We develop a novel low-complexity IRS phase optimization framework based on minorization-maximization (MM) technique, which requires only channel statistics to calculate the optimal phase. We also show that the SE gain of the DAA-MMSE receiver over DU-MMSE receiver increases with hardware impairments, and channel aging. Along with DAAMMSE receiver, the IRS is also shown to reduce the pilot overhead in a mMIMO system with channel aging.