Enhancing Beyond-5G and 6G Network Backhaul through Hybrid RF-FSO Communication: An Examination of HAPS and LEO Satellite Integration

Abstract-As data demands increase with the evolution toward beyond-5G and 6G communication systems, achieving efficient network backhaul is crucial to support high data rates, minimized latency, and broad geographic coverage. Traditional backhaul networks, reliant on radio frequency (RF) communications, face limitations in scalability and bandwidth, particularly in dense urban and rural remote areas. This paper explores a hybrid RF-Free-Space Optical (FSO) communication model, integrating Low Earth Orbit (LEO) satellites with High Altitude Platform Stations (HAPS) to enhance backhaul network efficiency. The proposed HAPS-LEO cooperative model mitigates atmospheric disruptions and offers scalable, high-bandwidth solutions. We further examine Contact Graph Routing (CGR) as a protocol for optimized data routing in variable connectivity conditions, presenting simulated performance results that demonstrate the advantages of this architecture.