Outage Probability and Optimal Power Splitting Ratio Analysis for RIS-Aided SWIPT System

This paper considers a simultaneous wireless information and power transfer (SWIPT) system with the aid of reconfigurable intelligent surface (RIS) and amplify-and-forward (AF) relay. The relay consumes no external power, it only harvests energy from its received signal transmitted from the source (S), and forwards the information signal to the destination (D) after power-splitting (PS) process. To minimize the overall outage probability of this system, we first give an approximate closed-form outage probability expression by using Newton-Cotes formula, and then we derive the optimal PS ratio based on the approximate expression, both the expression and the PS ratio is under a high signal-to-noise ratio (SNR) condition. Simulation results testify the accuracy of the approximate outage probability expression and the derived optimal PS ratio. It also shows that the deployment of RIS can significantly decrease the outage probability of SWIPT system.