Topology Control Schema for Better QoS in Hybrid RF/FSO Mesh Networks

摘要

The practical limitations and challenges of radio frequency (RF) basedcommunication networks have become increasingly apparent over the past decade,leading researchers to seek new hybrid communication approaches. One promisingstrategy that has been the subject of considerable interest is the augmentationof RF technology by Free Space Optics (FSO), using the strength of eachcommunication technology to overcome the limitations of the other. In thisarticle, we introduce a new scheme for controlling the topology in hybridRadio-Frequency/Free Space Optics (RF/FSO) wireless mesh networks. Our schemeis based on adaptive adjustments to both transmission power (of RF and FSOtransmitters) and the optical beam-width (of FSO transmitters) at individualnodes, with the objective of meeting specified Quality of Service (QoS)requirements, specifically end-to-end delay and throughput. We show how one caneffectively encode the instantaneous objectives and constraints of the systemas an instance of Integer Linear Programming (ILP). We demonstrate that thetechnique of Lagrangian Relaxation (LR), augmented with iterative repairheuristics, can be used to determine good (albeit sub-optimal) solutions forthe ILP problem, making the approach feasible for mid-sized networks. We makethe proposed scheme viable for large-scale networks in terms of number ofnodes, number of transceivers, and number of source-destination pairs bysolving the ILP problem using a Particle Swarm Optimization (PSO)implementation.