Link Allocation, Routing, and Scheduling for Hybrid FSO/RF Wireless Mesh Networks

Abstract

A hybrid free space optics/radio frequency (FSO/RF) technology has recently been proposed as a means of significantly increasing the throughput and reliability of wireless mesh networks (WMNs) for broadband communication. Current network control approaches assume quasi-static communication channels and use the simple protocol model to handle RF network interference. Depending on the application, these assumptions may not be sufficient for optimizing hybrid FSO/RF networks. In this paper, we present network control algorithms based on both nonfading and fading communication channels using the physical interference model for the RF portion of the network. We study the throughput improvement achievable by augmenting the RF WMN with FSO links. We address two questions: given a fixed number of FSO links, where should they be installed to maximize the throughput for given traffic demands, and how should the traffic be routed and scheduled in the hybrid FSO/RF network to achieve this throughput? We formulate these problems as one mixed integer linear program and provide a computationally efficient heuristic for scheduling and routing traffic demands through the hybrid FSO/RF network. The results show that the throughput of the original RF network can be increased dramatically by properly adding FSO links.