A performance-analysis and optimization framework for a STAR-RIS-aided cell-free massive MIMO system operating over spatially correlated fading with imperfect hardware. It contributes a linear-MMSE cascaded channel estimator under pilot contamination and hardware impairments, a closed-form downlink ergodic spectral-efficiency expression for maximum-ratio precoding with finite access points and STAR-RIS elements, and a max-min-fairness alternating-optimization scheme - adaptive particle swarm optimization for the non-convex passive beamforming and bisection for power control - shown to outperform a conventional RIS-aided system.
This IEEE TWC paper analyzes and optimizes a simultaneously-transmitting-and-reflecting reconfigurable intelligent surface (STAR-RIS)-aided cell-free massive MIMO system operating over spatially corr…