Handoff-Aware Channel Assignment for Multi-Radio Wireless Mesh Networks

Channel assignment schemes in Multi-Radio Wireless Mesh Networks (MR-WMNs) usually leave several links sharing the same channel within overlapped transmissions or interference ranges; this is especially true when only one radio is used or when the number of radios is very small compared to the number of orthogonal channels. In order to further improve MR-WMN performance, especially for mobile multimedia users, we propose a new assignment scheme that takes into account the presence of non uniform handoff traffic besides the non uniform traffic load. In fact, following handoffs of a large number of mesh clients (MCs), several ongoing flows associated to these clients need to be re-routed along other paths through other mesh routers (MRs). Re-routing that involves MRs (e.g., second-hop MR) further first-hop MRs will result in a much higher service disruption (i.e., data losses), during handoff, than one that involves only first-hop MR due to much bigger re-routing latency. This is not acceptable for real-time multimedia flows. Therefore, in this paper, we propose a dynamic scheme that carefully re-assigns channels to interfaces with the purpose of limiting the re-routing overhead/latency during client handoffs. The proposed scheme chooses a channel re-assignment that achieves a better load balancing among MRs. Therefore, it increases the capacity of MR-WMNs by accepting more users while satisfying their QoS requirements. Simulation results show that our proposed approach achieves good performance in terms of delay, loss rate and overall throughput.