Unified Performance Analysis of Reconfigurable Intelligent Surface Empowered Free Space Optical Communications

TL;DR

This paper provides a comprehensive performance analysis of RIS-empowered free-space optical systems under various atmospheric conditions, deriving exact statistical models and evaluating key performance metrics through simulations.

Contribution

It unifies multiple atmospheric turbulence models and derives exact statistical expressions for RIS-enabled FSO systems, including outage probability and BER, under diverse conditions.

Findings

Performance improves with more RIS elements.

RIS-empowered FSO outperforms traditional systems in foggy conditions.

Analytical results match Monte-Carlo simulations.

Abstract

Reconfigurable intelligent surface (RIS) is an excellent use case for line-of-sight (LOS) based technologies such as free-space optical (FSO) communications. In this paper, we analyze the performance of RIS-empowered FSO (RISE-FSO) systems by unifying Fisher-Snedecor (F), Gamma-Gamma (GG), and Malaga (M) distributions for atmospheric turbulence with zero-boresight pointing errors over deterministic as well as random path-loss in foggy conditions with heterodyne detection (HD) and intensity modulation/direct detection (IM/DD) methods. By deriving the probability density function (PDF) and cumulative distribution function (CDF) of the direct-link (DL) with the statistical effect of atmospheric turbulence, pointing errors, and random fog, we develop exact expressions of PDF and CDF of the resultant channel for the RISE-FSO system. Using the derived statistical results, we present exact expressions of outage probability, average bit-error-rate (BER), ergodic capacity, and moments of signal-to-noise ratio (SNR) for both DL-FSO and RISE-FSO systems. We also develop an asymptotic analysis of the outage probability and average BER and derive the diversity order of the considered systems. We validate the analytical expressions using Monte-Carlo simulations and demonstrate the performance scaling of the FSO system with the number of RIS elements for various turbulence channels, detection techniques, and weather conditions.