On Efficient Resource Allocation Strategies for Multi-RIS Enhanced V2I SWIPT Systems

In this paper, we explore the utilization of multiple reconfigurable intelligent surfaces (RIS) for simultaneous wireless information and power transfer (SWIPT) in a Vehicle-to-Infrastructure (V2I) system. The selection of RIS from several options is determined by the end-to-end instantaneous signal-to-noise ratio (SNR). Specifically, our work focuses on the time-switching (TS) SWIPT protocol, integrating non-linear energy harvesting (EH). The primary goal is to maximize information rate and harvested energy at the receivers by jointly optimizing transmit power and time-switching factors. To address the non-convex nature of the problem, the formulation is relaxed and solved iteratively in an alternating manner. In addition, closed-form expressions for optimization problems are derived using the Karush-Kuhn-Tucker (KKT) conditions, and the accuracy of the analysis is validated through comprehensive Monte Carlo simulations. Results demonstrate the significant superiority of our proposed multi-RIS aided schemes over single RIS configurations in terms of both information rate and maximum energy harvesting requirements. The integration of multi-RIS assisted communication setups exhibits substantial potential for enhancing SWIPT performance in V2I systems.