Impact of Phase Noise in Downlink STAR-RIS-Aided Massive MIMO Systems

In this work, we investigate the effect of phase noise in downlink simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS)-aided massive multiple-input multiple-output (mMIMO) systems, where users are located on both sides of the STAR-RIS panel. We assume that users only know the knowledge of statistical channel state information (CSI), and account for correlated Rayleigh fading to meet realistic conditions. The use-and-then-forget (UatF) bound of the sum-rate has been derived by assuming maximum ratio transmission (MRT) precoding. Notably, a projected gradient ascent method (PGAM) algorithm has been used to optimize the amplitudes and phase shifts of the STAR-RIS panel simultaneously. Our simulations show that the sum-rate can be improved as the noise concentration parameter of the Von Mises (VM) distribution increases.