Optimization of Free Space Optical Wireless Network for Cellular Backhauling

TL;DR

This paper develops an integer linear programming model and a column generation method to design cost-effective, reliable FSO-based cellular backhaul networks with multiple disjoint paths, balancing cost and reliability.

Contribution

It introduces a novel optimization framework for FSO backhaul design that guarantees multiple disjoint paths and improves computational scalability.

Findings

The proposed model achieves near-optimal solutions in realistic scenarios.

The column generation method enhances computational efficiency for large networks.

The approach effectively balances cost and reliability in FSO backhaul planning.

Abstract

With densification of nodes in cellular networks, free space optic (FSO) connections are becoming an appealing low cost and high rate alternative to copper and fiber as the backhaul solution for wireless communication systems. To ensure a reliable cellular backhaul, provisions for redundant, disjoint paths between the nodes must be made in the design phase. This paper aims at finding a cost-effective solution to upgrade the cellular backhaul with pre-deployed optical fibers using FSO links and mirror components. Since the quality of the FSO links depends on several factors, such as transmission distance, power, and weather conditions, we adopt an elaborate formulation to calculate link reliability. We present a novel integer linear programming model to approach optimal FSO backhaul design, guaranteeing $K$-disjoint paths connecting each node pair. Next, we derive a column generation method to a path-oriented mathematical formulation. Applying the method in a sequential manner enables high computational scalability. We use realistic scenarios to demonstrate our approaches efficiently provide optimal or near-optimal solutions, and thereby allow for accurately dealing with the trade-off between cost and reliability.