Reconfigurable Intelligent Surface Empowered Rate-Splitting Multiple Access for Simultaneous Wireless Information and Power Transfer

TL;DR

This paper explores the integration of reconfigurable intelligent surfaces with rate-splitting multiple access to enhance simultaneous wireless information and power transfer, optimizing beamformers and RIS coefficients for improved spectral and energy efficiency.

Contribution

It introduces a novel RIS empowered RSMA framework for SWIPT, jointly optimizing transmit and RIS parameters to improve the tradeoff between data rate and energy harvesting.

Findings

Achieves better WSR and energy harvesting tradeoff.

Proposes an alternating optimization and SCA-based solution.

Demonstrates the effectiveness through numerical results.

Abstract

Rate-splitting multiple access (RSMA) and reconfigurable intelligent surface (RIS) have been both recognized as promising techniques for 6G. The benefits of combining the two techniques to enhance the spectral and energy efficiency have been recently exploited in communication-only networks. Inspired by the recent advances on RIS empowered RSMA, in this work we investigate the use of RIS empowered RSMA for simultaneous wireless information and power transfer (SWIPT) with one transmitter concurrently sending information to multiple information receivers (IRs) and transferring energy to multiple energy receivers (ERs). Specifically, we jointly optimize the transmit beamformers and the RIS reflection coefficients to maximize the weighted sum-rate (WSR) of IRs under the harvested energy constraint of ERs and the transmit power constraint. An alternating optimization and successive convex approximation (SCA)-based optimization framework is then proposed to solve the problem. Numerical results show that by marrying the benefits of RSMA and RIS, the proposed RIS empowered RSMA achieves a better tradeoff between the WSR of IRs and energy harvested at ERs. Therefore, we conclude that RIS empowered RSMA is a promising strategy for SWIPT.