Research On Opportunistic Routing In Wireless Mesh Network

Wireless Mesh network is based on the traditional Ad hoc network and it contains various structural features of Ad hoc networks. As a new broadband access technology, wireless Mesh network has improved the traditional wireless local area network (WLAN)by breaking through the limitations in which every client is connected to the AP (Access Point) via a wireless link to access the network. Meanwhile the network node in wireless Mesh network has independent routing and host function just like the node in Ad hoc network, and a distributed control mode without center of control point is utilized. At the same time, wireless Mesh network is different from the Ad hoc networks. With stationary backbone nodes and high node bandwidth capacity, wireless Mesh network can provide users with more stable, reliable, high quality Internet access services. The research on wireless Mesh network routing technology is advantageous to improve the routing performance in wireless Mesh network and the quality of service. It is significant to promote the development and application of wireless Mesh network and to satisfy people’s demand for high performance of wireless networkBy broadcast, opportunistic routing transmits packets to multiple potential next hop nodes which constitute the next-hop node sets. By Competing, the next hop node set selects the best next hop node which would forward the packet to the next-hop, until the node is the destination. The opportunistic routing improves the network throughput and the reliability of transmission by making the most of network broadcast traits.In order to make full use of the broadcast characteristic of the wireless Mesh network, an opportunistic routing (CROR) protocol based on coding-revenue for wireless Mesh networks is proposed. The protocol codes multiple packets into one packet before transmission. And it uses the forward distance of the ETX (Expected Transmission Count) to define the coding-revenue and then uses coding-revenue to define the priority of the nodes in the next-hop forwarding nodes set. The highest priority node in the next-hop node set which decodes the source packet will forward the packet towards the destination in the same way. Simulation experiments show that the CROR improves network throughput and transmission performance, and increases the network coding transmission percentage.On account of the invariance of the metric of the opportunity routing, the choice of the best next-hop node is always the same. As a result, these best next hop nodes will affect the transfer efficiency of the whole link in the process of transmission, due to the local congestion caused by the heavy load. By balancing the load of links in the wireless Mesh network, the local congestion can be avoided. To balance the load of wireless Mesh and avoid partial congestion, the LBOR (the Link Load Balancing Opportunistic Routing) has been put forward, aiming at dealing with the local scope Link Load Balancing, using the combination of ETX(Expected Transmission Count) and Link Load measurement model to define the priorities in the jump forward node set, and to coordinate the nodes by monitoring each other. When the best next-hop node has been selected, it will forward the data to the next-hop until the destination node.