Performance analysis of RIS-assisted wireless systems with channel aging and spatial correlation

Reconfigurable Intelligent Surfaces (RISs) have caught wide attention for their advantages in dealing with the blocking obstacles in wireless communications. In this paper, we present a detailed analysis of RIS-assisted multiple-input single-output systems taking into account the joint effects of spatial correlation of the RIS elements and channel aging caused by users' relative movements. More specifically, a novel closed-form expression for the Spectrum Efficiency (SE) with maximum ratio transmission precoding is given. Monte Carlo simulation results verify the accuracy of the analytical results. It is proved that the channel aging phenomenon degrades the system performance while the application of a RIS can compensate for the loss, and the longer transmission time results in the more severe effect of channel aging on the system performance. Moreover, the spatial correlation of the RIS elements degrades communication quality and the SE. In addition, increasing the size of the RIS elements can improve the SE.