Free Space Optical Mesh Networks: A Survey

Free space optical (FSO) communication, known for its high data rates and immunity to electromagnetic interference, encounters challenges such as weather dependency, misalignment issues, and line-of-sight (LoS) requirements. Mesh networks, with their inherent scalability and redundancy, can mitigate these limitations by providing multiple pathways for data transmission and robust network configurations. This paper investigates the key motivations for integrating FSO transmission within mesh structures. We review existing literature on both FSO and hybrid RF/FSO mesh networks, discussing technical studies aimed at maximizing network performance and minimizing delay and cost deployments. We equally explore some relaying approaches in FSO mesh networks and shed light on the advantages of some relaying solutions, mainly, flying platforms and reconfigurable intelligent surfaces (RIS). We discuss the use of FSO in satellite communication to establish two types of mesh networks: inter-satellite and satellite-aerial/ground mesh networks. Finally, some open issues and future research directions are explored.