Deployment of Hybrid FSO/RF Links in Backhaul of Relay-Based Rural Area Cellular Networks: Advantages and Performance Analysis

In this letter, we consider a rural area cellular framework in which a relay-based free space optical (FSO) configuration is assumed for the backhaul. We assume orthogonal frequency division multiple access setting for both optical and radio frequency (RF) links. In this system, the rural users communicate with base station (BS) through several relays, while the links between BS and relays are assumed to be hybrid FSO/RF. We then propose a resource allocation scheme to maximize the system throughput and compare the performance against a similar system that uses only an FSO link in the backhaul. Simulation results show that deploying hybrid FSO/RF communication considerably improves the performance. The improvement is more pronounced in foggy conditions. As far as the number of deployed relays to maintain a certain performance is concerned, we observe that a hybrid FSO/RF system needs considerably smaller number of relays, as few as half in our case, than an FSO system.