Hybrid Radio/Free-Space Optical Design for Next Generation Backhaul Systems

TL;DR

This paper proposes a hybrid RF/FSO backhaul network design that optimizes cost, data rate, and reliability by combining radio-frequency and free-space optical technologies, solving the problem efficiently with near-optimal results.

Contribution

It introduces a novel hybrid RF/FSO backhaul solution and formulates the cost minimization as a maximum weight clique problem, providing an efficient solution approach.

Findings

Hybrid RF/FSO links reduce costs compared to pure optical solutions.

The proposed method achieves near-optimal performance in simulations.

The problem formulation allows for practical implementation with moderate complexity.

Abstract

The deluge of date rate in today's networks imposes a cost burden on the backhaul network design. Developing cost efficient backhaul solutions becomes an exciting, yet challenging, problem. Traditional technologies for backhaul networks include either radio-frequency backhauls (RF) or optical fibers (OF). While RF is a cost-effective solution as compared to OF, it supports lower data rate requirements. Another promising backhaul solution is the free-space optics (FSO) as it offers both a high data rate and a relatively low cost. FSO, however, is sensitive to nature conditions, e.g., rain, fog, line-of-sight. This paper combines both RF and FSO advantages and proposes a hybrid RF/FSO backhaul solution. It considers the problem of minimizing the cost of the backhaul network by choosing either OF or hybrid RF/FSO backhaul links between the base-stations (BS) so as to satisfy data rate, connectivity, and reliability constraints. It shows that under a specified realistic assumption about the cost of OF and hybrid RF/FSO links, the problem is equivalent to a maximum weight clique problem, which can be solved with moderate complexity. Simulation results show that the proposed solution shows a close-to-optimal performance, especially for practical prices of the hybrid RF/FSO links.