Multi-channel anypath routing in wireless mesh networks

Recently, wireless mesh networks have been proposed as a mechanism to provide alternative broadband wireless internet access. The usage of multiple radios transmitting at diverse frequency bands allows a significant increase in the capacity of such networks. However, popular Hybrid Channel Assignment strategies, which use a fixed interface for receiving and a switchable interface for transmitting to neighbor nodes, suffer from large delay and jitter due to the accumulated switching overhead over multiple hops. In this paper, we propose a novel routing mechanism for such hybrid multi-radio multichannel mesh networks based on the anypath paradigm. In our approach, the routing layer maintains for each destination at each hop a set of candidate forwarders, where each neighbor is tuned to a different channel. A novel layer 2.5 forwarding and scheduling algorithm decides then for each packet individually, which actual neighbor to forward the packet to, in order to minimize the overall delay. We implemented the selected approach using extensions to OLSR. An evaluation in KAUMesh test bed shows for specific scenarios that AP-OLSR reduces average delay with up to 70% compared to standard OLSR while also reducing both average and maximum jitter by 60% and 45% respectively.