Resilient Backhaul Network Design Using Hybrid Radio/Free-Space Optical Technology

TL;DR

This paper presents a cost-effective hybrid RF/FSO backhaul network design that ensures resilience through multiple link-disjoint paths, optimizing deployment costs while meeting data rate and reliability requirements.

Contribution

It introduces a novel graph-theoretic approach to jointly optimize link types and redundancy for resilient backhaul networks using hybrid RF/FSO technology.

Findings

Heuristic solution achieves near-optimal cost performance.

Hybrid RF/FSO links reduce overall deployment costs.

Resilience is ensured with multiple link-disjoint paths.

Abstract

The radio-frequency (RF) technology is a scalable solution for the backhaul planning. However, its performance is limited in terms of data rate and latency. Free Space Optical (FSO) backhaul, on the other hand, offers a higher data rate but is sensitive to weather conditions. To combine the advantages of RF and FSO backhauls, this paper proposes a cost-efficient backhaul network using the hybrid RF/FSO technology. To ensure a resilient backhaul, the paper imposes a given degree of redundancy by connecting each node through $K$ link-disjoint paths so as to cope with potential link failures. Hence, the network planning problem considered in this paper is the one of minimizing the total deployment cost by choosing the appropriate link type, i.e., either hybrid RF/FSO or optical fiber (OF), between each couple of base-stations while guaranteeing $K$ link-disjoint connections, a data rate target, and a reliability threshold. The paper solves the problem using graph theory techniques. It reformulates the problem as a maximum weight clique problem in the planning graph, under a specified realistic assumption about the cost of OF and hybrid RF/FSO links. Simulation results show the cost of the different planning and suggest that the proposed heuristic solution has a close-to-optimal performance for a significant gain in computation complexity.