Capacity Analysis of Adaptive Combining for Hybrid FSO/RF Satellite Communication System

Abstract

Satellite communication (SATCOM) systems are generally used for broadcasting, disaster recovery, and navigation applications due to the large coverage area. Deployment of more SATCOM systems require a high data rate and large communication capacity. On the other hand, free space optics (FSO) technology has fulfilled the needs of the gigabit capacity due to its exemplary features. Nevertheless, the FSO link is vulnerable to atmospheric turbulence, pointing errors, weather conditions like fog, snow etc. Subsequently, the more reliable radio frequency (RF) link can be used in combination with the FSO link to counteract the limitations. Therefore, a hybrid FSO/RF system is a promising solution for next-generation satellite communication (SATCOM) systems. In this context, we investigate an adaptive-combining-based switching scheme for a hybrid FSO/RF system considering both uplink and downlink SATCOM scenarios. Adaptive combining involves switching of the FSO link to maximal ratio combining (MRC) of FSO and RF links provided the operating FSO link quality becomes unacceptable for transmission. Further, in this paper, the performance of the adaptive-combining-based hybrid FSO/RF system is examined through exact and asymptotic ergodic capacity analyses.