Reconfigurable Intelligent Surface Assisted Free Space Optical Information and Power Transfer

TL;DR

This paper introduces a RIS-assisted resonant beam system for free space optical wireless power and data transfer, enabling NLOS transmission with high energy efficiency and positional sensitivity, advancing 6G communication technologies.

Contribution

It proposes a novel RIS-assisted resonant beam system for optical SWIPT, including an optical propagation model and NLOS transmission capabilities, which were not previously explored.

Findings

Maximum NLOS energy efficiency of 55% at 10m distance

NLOS performance depends on RIS position and orientation

System effectively detects LOS obstructions and enables NLOS transmission

Abstract

Free space optical (FSO) transmission has emerged as a key candidate technology for 6G to expand new spectrum and improve network capacity due to its advantages of large bandwidth, low electromagnetic interference, and high energy efficiency. Resonant beam operating in the infrared band utilizes spatially separated laser cavities to enable safe and mobile high-power energy and high-rate information transmission but is limited by line-of-sight (LOS) channel. In this paper, we propose a reconfigurable intelligent surface (RIS) assisted resonant beam simultaneous wireless information and power transfer (SWIPT) system and establish an optical field propagation model to analyze the channel state information (CSI), in which LOS obstruction can be detected sensitively and non-line-of-sight (NLOS) transmission can be realized by changing the phased of resonant beam in RIS. Numerical results demonstrate that, apart from the transmission distance, the NLOS performance depends on both the horizontal and vertical positions of RIS. The maximum NLOS energy efficiency can achieve 55% within a transfer distance of 10m, a translation distance of $\pm$4mm, and rotation angle of $\pm$50{\deg}.