Performance Analysis of Uplink Optical Wireless Communication System in Presence of STAR-RIS

TL;DR

This paper investigates the use of STAR-RIS in visible light communication systems, deriving achievable rates, formulating sum-rate optimization, and comparing energy-splitting and mode-switching modes through numerical analysis.

Contribution

First to analyze STAR-RIS in VLC systems, deriving achievable rates, formulating optimization problems, and comparing operating modes with numerical results.

Findings

Energy-splitting and mode-switching modes perform similarly.

Numerical results show the impact of STAR-RIS on spectral and energy efficiency.

Comparison with benchmarking schemes highlights performance gains.

Abstract

Recently, reconfigurable intelligent surface (RIS) has gained research and development interests to modify wireless channel characteristics in order to improve performance of wireless communications, especially when quality of the line-of-sight channel is not that good. In this work, for the first time in the literature, we have used simultaneously transmitting and reflecting RIS (STAR-RIS) in non-orthogonal multiple-access visible light communication system to improve performance of the system. Achievable rates of the users are derived for two data recovery schemes, single-user detection (SUD) and successive interference cancellation (SIC). Then, sum-rate optimization problem is formulated for two operating modes of STAR-RIS, namely energy-splitting and mode-switching cases. Moreover, a sequential parametric convex approximation method is used to solve the sum-rate optimization problems. We have also compared energy-splitting and mode-switching cases and showed that these two modes have the same performance. Finally, numerical results for SUD and SIC schemes and two benchmarking schemes, time-sharing and max-min fairness, are presented and spectral- and energy-efficiency, number of STAR-RIS elements, position of users and access point are discussed.