Optimized relaying and scheduling in cooperative Free Space Optical fronthaul/backhaul of 5G

The anticipated explosive growth of various Small Cells (SCs) urges the design of a high-rate, reliable and resource-efficient fronthaul/backhaul framework in the forthcoming fifth-generation (5G) mobile communication network, which has been attracting ever-increasing attentions and becoming a research hotspot. Motivated by the advances in Free Space Optical (FSO) and the growing interests in 5G, this paper investigates the feasibility of a SG fronthaul/backhaul framework based on FSO communication system. We consider a Decode-and-Forward (DF) cooperative FSO relay system, aiming at maximizing system throughput. In contrast to traditional fronthaul/backhaul framework with fixed connections, we propose a dynamic fronthaul/backhaul framework using a relay selection algorithm to adapt different weather conditions and employ the back-pressure theory to boost transmission quality. Then, a link scheduling algorithm is further put forward to increase the resource utilization by making the most of the idle FSO links. Simulation results demonstrate that the cooperative FSO fronthaul/backhaul system based on the proposed algorithms can significantly improve the network performance in reliability and resource utilization, especially for data-intensive transmission.