Application Of Dynamic Variable Channel Width Assignment Method In Wireless Mesh Networks

Wireless Mesh Network(WMN) is a last mile broadband wireless access technique, and it has been widely used in many areas. However, it is still an open issue of how to provide QoS for real-time multimedia traffics. In this paper, we propose a new Qos routing protocol called VCW-DSR(Variable Channel Width Dynamic Routing Protocol), which utilizes the advantages of variable channel width method.VCW-DSR is designed for infrastructure WMN with single gateway and multi-channel multi-radio backbone routers. VCW-DSR route algorithm is a centralized algorithm running on the gateway. It can allocate spectrum resource on the route according to the bandwidth QoS requirement, and avoid interference between active links at the same time. VCW-DSR routing protocol changes the route request and reply phases of DSR protocol. When a client sends a route request, it asks for a feasible route which meets its QoS demands. When the gateway returns route reply, it allocates and reserves bandwidth and spectrum resources for the data flow. A new phase called route cancelling phase is added. When a data flow ends, the client is in charge of requesting the gateway to take back resources allocated for the flow. On receiving the request, the gateway finds out resources needed for remaining flows on the route of the data flow, and then reallocates spectrum resources. We also present a route error mechanism which deals with situations when nodes or radios break down.We introduce how to change channel width on our test-bed and verify that the channel width is successfully changed. We study the impact of channel width on throughput, delay and delay variation. Experimental results show that variable channel width method outperforms fixed channel width method in concurrent transmission of two ad hoc links.