Rate Analysis and Optimization of IRS-Aided Hardware-Impaired Cell-Free Massive MIMO Systems Under Correlated Ricean Fading Channels

In this correspondence, we investigate a hardware-impaired uplink cell-free massive multiple-input multiple-output (MIMO) system with intelligent reconfigurable surfaces (IRSs) under correlated Ricean fading channels. Based on the imperfect channel knowledge, we derive tight closed-form expressions for the lower-bound achievable rate and study the achievable rate under various settings, such as different channel conditions, degrees of hardware impairment, and numbers of APs/IRS/elements per IRS. We also formulate the design of the IRS phase-shifts and power control factors as an optimization problem that maximizes the weighted sum-rate (WSR) and develop algorithms to solve it. All theoretical analyses and the effectiveness of the proposed algorithms are verified via extensive simulations.