Hybrid FSO/RF communications system demonstrated across degraded 30 km link with integrated commercial radio

Abstract

Radio frequency (RF) communication, while reliable, is capacity limited and faces heavy spectrum regulation. In contrast, free space optical (FSO) communication provides multi-Gbit/s rates without spectrum allocation. Yet, FSO communication experiences link degradation due to clouds, fog, beam misalignment, and line of sight blockages. This paper reviews the development of a layer 2 modem that combines both RF and FSO links seamlessly with error-free transmission and quality of service (QoS) capabilities. Test data collected on a 30 km terrestrial link demonstrates mode m integration with a commercial RF link and provides insight on the QoS system performance.