Research And Simulation For The Routing Protocols In The Mesh Wireless Networks

Wireless Mesh Network(WMN) is a kind of broadband wireless network structure. It has properties of multi-hop, self-organization and self-healing, which is distributed network of high-capacity and high-speed. It aims at exploring the combination between wireless mobile communication and IP technology. Researching on multi-networks coexistence in a mini-type area is another work of WMN. WMN is evolved from Ad hoc network, but it’s a static version of Ad hoc. We can treat it as a wireless pattern of Internet.AODV is an on-demand route protocol and it is widely used in Wireless Mesh Network. As a single-path route protocol, AODV will initiate the establishment request when a link break is found. That will lead to the delay increase of the network and the problem is an urgent agenda.The thesis first provides a comprehensive view of the existing research on WMN and then analyzes the route protocols in it. After that, the thesis presents a detailed analysis for AODV and explains the importance of the multi-path improvement. After making a comparison between the mainstream multi-path route protocols based on AODV, it proposes to make improvement on AODV-BR. In AODV-BR, when link break happens, the backup route will be launched for data transmission. And AODV-BR doesn’t add any new control packet, so it won’t lead to the increase of link load. Besides these advantages in this protocol, AODV-BR still has the following disadvantages.When backup route is used to transmit packets, destination nodes might receive duplicate packets. AODV-BR adopts the local repair scheme as AODV, so it still has some efficiency problems. The thesis proposes an improved protocol based on AODV-BR, which is named as AODV-BRS. The proposed protocol works as follows: filtering the duplicate data to ensure that every packet arriving at destination is unique and reducing the waste of link resource; Not only establishing backup route for the nodes on the main road but also for the ones on the alternative road; directly using the backup route restored in the main road instead of turning to neighbor when link breaks happen; when a procedure of local repair needs to be launched, AODV-BRS uses a lower cost RREQ broadcast to inform nearby nodes in a smaller range and chooses a proper node as the starting point of the local repair.We have done extensive simulation through NS2 simulation tool. The simulation result showes that AODV-BRS protocol has a lower delay and a higher delivery ratio compared to AODV and AODV-BR.