Performance Analysis and Optimization for RIS-Aided Communication Systems

Reconfigurable Intelligent Surface (RIS) stands out for its unique low-cost and low-energy characteristics, which is expected to break through the uncontrollability of wireless channels and build an intelligent programmable wireless environment. In this paper, we consider a RIS-aided downlink communication system including one access point serving a user terminal and derive closed-form expressions of ergodic achievable rate and outage probability. Then, we analyze the ergodic achievable rate in terms of high signal-to-noise ratio slope and power offset. A phase shift optimization scheme is also proposed to improve the ergodic achievable rate. Finally, simulation results are conducted to validate the accuracy of the analytical results. According to the simulation results, the proposed phase shift optimization scheme can improve the system performance, compared to the random phase shift scheme.