Research On Channel Assignment Strategy Based On Cross-layer Design In Wireless Mesh Network

Wireless mesh networks are comprised of a number of wireless routers and wireless access points. It has emerged as one of the promising solutions for next generation wireless networks because it could provide, enlarge wireless service coverage area and reduce the network installation cost. The transfer rate of wireless links could be decreased by interference, so using non-overlapped channels for data transfer is an efficient way to lessen link interference. Different numbers of non-overlapped channels are defined in IEEE 802.11 a/b/g standards and the network throughput could be increased effectively by utilizing those channels. Research on how to increase the throughput of wireless mesh network is of great significance.More research about channel assignment is based on single-channel MAC protocol which focuses on hidden terminals and exposed terminals. Most protocols use RTS/CTS packets for solving the problem. But with the number of node increasing, the competition between two nodes and the conflict of delivering packets increase. It reduces network capacity and channel utilization. Equipping multiple radios on each node and assigning channels to the wireless links properly can effectively reduce network interference and thus increase network capacity.Based on IEEE 802.11 MAC protocol, the research work presented in this dissertation is mainly focused on how to improve the throughputs of wireless mesh networks.The problems of the multi-interface multi-channel network and the present channel assignment algorithms are analyzed and the network model and interference model of static wireless mesh network are summarized.Considering that it is very difficult to obtain the information of the whole network and the channel assignment algorithms on all information of the network is complex, a channel assignment algorithm which combines with routing protocols is proposed. Algorithm uses the idea of cross-layer design. MAC information is added into routing protocols. To use these informations, a link can be allocated no interference channels as much as possible according to the channel used status around itself. It makes a best appropriate path and improves the network capacity.Finally, wireless module of NS-2 is extended, and multi-channel wireless network simulation model is built under NS-2, based on which, simulation compares the performance among using Hyacinth, algorithm this paper proposed and in single-radio enviroment. Simulation result shows that new algorithm can achieve higher throughput and higher packet delivery rate.