Channel Assignment and Routing in Multi-Radio Wireless Mesh Networks

CHANNEL ASSIGNMENT AND ROUTING FOR MULTI-RADIO WIRELESS MESH NETWORKS Ahmet Murat Özdemiray M.S. in Computer Engineering Supervisor: Assist. Prof. Dr. İbrahim Körpeoğlu September, 2008 Wireless Mesh Network is a promising technology since it extends the range of wireless coverage by multi-hop transmission between routers. However, in multihop networks the total throughput decreases with increasing number of nodes and hops. To increase the total throughput, some mesh routers are equipped with multiple radios to use the available bandwidth of multiple non-overlapping channels. However, channel assignment should be done carefully to effectively use this available bandwidth. Moreover, the optimal channel assignment algorithm is NP-hard. In this thesis, we propose a joint channel assignment and routing solution to effectively use the available bandwidth for multi-radio wireless mesh networks with given network topology and traffic profile. Initially, we predict the final routes of the flows and estimate the loads on the links using these path predictions and given traffic profile. Then three different heuristics determine the assignment order of the links. Then the least busy channel among the available channels is assigned to the link. Finally, our routing algorithm routes the flows such that the selected path is the least busy path among the alternatives. We evaluated our channel assignment and routing algorithm using ns-2 simulator which supports multiple channels and multiple radios per node and we compared our results with single channel WMNs, and different algorithms for multi-radio multi-channel WMNs. The results show that our joint algorithm successfully achieves up to 5 times more throughput than single channel WMN with using just 2 radios and 3 channels. Our algorithms also out-performs other compared channel assignment algorithms for multi-radio multi-channel WMNs.