A Novel MRR-UAV-Based Relay With Optical Network Coding: A Comparative Study With Optical IRS and Conventional UAV Relaying

Combining free-space optical (FSO) technology with uncrewed aerial vehicles (UAVs) introduces dynamic, rapidly deployable relay systems, overcoming line-of-sight (LoS) constraints and extending high-speed communication networks’ reach, albeit with critical considerations of weight and power consumption. There are two main types of optical communication technologies for relays: conventional optical relays, such as amplify-and-forward (AF)/decode-and-forward (DF) systems, and intelligent reflecting surface (IRS)-based relays, each facing significant challenges. To this end, this paper introduces a novel hybrid two-way free-space optical (FSO) relay system utilizing modulating retro-reflector (MRR) technology to address specific challenges in UAV-based optical communication. Unlike traditional amplify-and-forward (AF) and decode-and-forward (DF) relay systems, which struggle with power consumption and IRS-based systems that suffer from sensitivity to angular fluctuations, the proposed MRR-based approach offers a strategic compromise. The proposed system combines MRR technology with conventional lens-based systems and network coding to enhance stability against UAV’s angular movements. Performance evaluations reveal that while the proposed MRR-based relay system offers significant advantages under conditions of high angular instability, it achieves comparable or superior performance relative to AF/DF and IRS-based systems within certain operational parameter ranges. This study thus advances the discussion on UAV-based relay solutions by offering an in-depth analysis of the proposed system’s application potential and its specific constraints.