Transmission Design for Active RIS-Aided Simultaneous Wireless Information and Power Transfer

TL;DR

This paper proposes an active RIS-aided SWIPT system that enhances spectral and energy efficiency by addressing the limitations of passive RIS, using optimization techniques to improve system performance under practical constraints.

Contribution

It introduces a novel active RIS-aided SWIPT system and develops an optimization framework to maximize sum rate while satisfying power constraints, demonstrating performance gains.

Findings

Active RIS improves system performance over passive RIS.

Optimization achieves higher sum rate within power constraints.

Simulation confirms performance gains with same power budget.

Abstract

Reconfigurable intelligent surface (RIS) is a revolutionary technology to enhance both the spectral efficiency and energy efficiency of wireless communication systems. However, most of the existing contributions mainly focused on the study of passive RIS, which suffers from the ``double fading'' effect. On the other hand, active RIS, which is equipped with amplifiers, can effectively address this issue. In this paper, we propose an active RIS-aided simultaneous wireless information and power transfer (SWIPT) system. Specifically, we maximize the weighted sum rate of the information receivers, subject to the minimum power received at all energy receivers, amplification power constraint at the active RIS, and the maximum transmit power constraint at the base station (BS). By adopting alternating optimization framework, suboptimal solutions are obtained. Simulation results show that the active RIS-aided SWIPT system has higher performance gain with the same power budget.