A Multicast Technique for Fixed and Mobile Optical Wireless Backhaul in 5G Networks

The data demand for 5G networks is expected to be much higher than current throughput requirements. To meet this demand, a dense topology of interlinked small cells is needed. Laying new copper and fiber in such a dense network would be cost prohibitive. There is, therefore, an urgent need for high capacity wireless point-to-multipoint backhaul solutions. In this paper, we provide a compendium of solutions for ultrahigh data rate physical-layer broadcast and multicast using free space optics in 5G backhaul networks. We show that the problem of optimal multicast in mobile scenarios with highly directional optical links is a time-dependent prize collecting traveling salesman problem which is NP-hard. In formulating our problem, we develop a novel prize assignment strategy that guarantees the selection of mutually non-disjoint multicast sets. Due to the problem being NP-hard, we provide several potential heuristics for multicast in fixed and mobile scenarios, and present a comprehensive performance evaluation of the developed schemes.