Optical RIS-Based Coordinated FSO Relaying Networks

This paper proposes a novel framework for coordinated free-space optical (FSO) relaying networks utilizing optical reconfigurable intelligent surfaces (ORISs), aiming to enhance overall communication performance. By intelligently controlling both reflection and refraction properties, the ORIS enables dynamic beam steering to effectively mitigate the multiple-access limitations inherent in traditional FSO networks. Exploiting this capability, we investigate coordinated transmission schemes that maximize network resource utilization and enhance signal quality, which have been largely underexplored in the context of FSO networks due to access constraints. Analytical derivations and simulation results demonstrate that the proposed ORIS-assisted coordinated relaying network significantly outperforms conventional time-division multiple-access-based FSO networks, especially under moderate to high optical transmission power, where the sum ergodic capacity can be dramatically increased, potentially even doubled. Building on these findings, this study provides foundational insights for the development of next-generation optical wireless communication networks, where ORIS not only enables multiple-access but also improves link capacity and energy efficiency in mixed optical networks.