Resilient topology design for free space optical cellular backhaul networking

With cellular networks´ densification, backhaul solutions tend to go wireless to reduce costs. Free space optic (FSO) links are becoming an appealing, secure and high rate alternative to RF. To ensure a reliable cellular backhaul, redundancy provisions for disjoint paths between the nodes must be made in the network design phase. This paper presents cost-effective solutions, using FSO links and mirrors, that can be employed to upgrade a cellular backhaul with pre-deployed optical fibers. An integer programming model is introduced to approach optimal FSO backhaul design, guaranteeing K-disjoint paths between each node pair. We use realistic scenarios to demonstrate some optimal backhaul topologies by solving the model. We also illustrate the impact of K and the number of optical fibers on optimal solutions.