On-line Joint QoS Routing and Channel Assignment in Multi-Channel Multi-Radio Wireless Mesh Networks ✩ Bahador Bakhshi a , Siavash Khorsandi a,∗ , Antonio Capone b a Computer Engineering and Information Technology Department, Amirkabir University of Technology, Hafez Avenue, Tehran, Iran b Department of Electronics and Information, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan, Italy Abstract We study the problem of on-line joint QoS routing and channel assignment for performance optimization in multi-channel multi-radio wireless mesh networks, which is a fundamental issue in supporting quality of service for emerging mul- timedia applications. To our best knowledge, this is the first time that the problem is addressed. Our proposed solution is composed of a routing algo- rithm that finds up to k but not necessarily feasible paths for each demand and an on-demand channel (re)assignment algorithm that adapts network re- sources to maintain feasibility of one of the paths. We also study the problem of obtaining an upper bound on the network performance. First, we consider an artificial version of the problem, in which all demands arrive at the same time, and formulate it as a mixed integer linear programming model. To tackle the complexity of the model, it is relaxed that provides a tight upper bound while improves solution time up to 3.0e+5 times. Then, we model the original problem by extending the relaxed model to consider dynamic demands, it leads to a huge model; thus, we develop another model, which is equivalent to the first one and is decomposable. It is broken down by a decomposition algorithm into subproblems, which are solved sequentially. Our extensive simulations show that the proposed solution has comparable performance to the bound obtained from the decomposition algorithm; it efficiently exploits available channels, and needs very few radios per node to achieve high network performance. Keywords: Joint QoS Routing and Channel Assignment, Optimization Model, Decomposition, Upper Bound, Multi-Channel Multi-Radio Wireless Mesh Networks 1. Introduction QoS of Service (QoS) support, which is entailed by emerging multimedia ser- vices, is an essential component in broadband Wireless Mesh Networks (WMN). ✩ This work was done while Bahador Bakhshi was a visiting PhD student at Politecnico di Milano and was supported through funds provided by Iran Telecommunication Research Center (ITRC) and the Italian PRIN project SESAME. ∗ Corresponding author Email addresses: bbakhshi@aut.ac.ir (Bahador Bakhshi), khorsandi@aut.ac.ir (Siavash Khorsandi), capone@elet.polimi.it (Antonio Capone) Preprint submitted to Computer Communications February 19, 2011