Research On Opportunistic Routing Protocol In Wireless Mesh Networks

Wireless mesh network is an efficient and reliable "last mile" access solution owing to the low cost and ease of deployment. The wireless mesh network routing algorithm design is a major factor which determines the network performance, worthy of further study. Opportunistic routing is an important branch of the routing algorithm, in order to improve the one hop success rate of data transmission, opportunistic routing uses multiple next hop nodes set rather than specific next hop node during data packet transmission process, thereby to inhibit retransmission and improve network performance. In this paper, the opportunistic routing algorithm for wireless mesh network is studied, details are as follows:In the most of the existing opportunistic routing protocols, every node needes to master the weighted real-time topology of the entire network to calculate the alternative forwarding nodes set and the forwarding priority, which will result in heavy network overhead and reduce the network scalability. In addition, the calculation of the node forwarding capability based on iterative strategy will introduce large iterative computation. To solve these problems, this paper proposes a flooding based distributed opportunistic routing, FDOR, it determines alternative forwarding nodes set and prioritizes the forwarding nodes during the path-finding process. In addition, the efficiency of the existing forwarding nodes coordination mechanism is not high, and data packets may be repeatedly transmitted. To solve this problem, FDOR introduces a two-way acknowledgment mechanism in order to ensure efficient and reliable coordination of forwarding nodes. Simulation results show that, with FDOR, network throughput can be boosted by 8.6%, and end to end delay can be reduced by 8.0%, compared with classic opportunistic routing.In addition, for wireless mesh network in multi-gateway backhaul scenario, this paper proposes a load balancing based multi-gateway multi-rate opportunistic anycast routing, LBMGR-OAR. During the transmission of data packets, LBMGR-OAR exploits the opportunity forwarding feature of opportunistic routing, dynamically selects the optimal data transmission rate, next hop and gateway for nodes based on nodes’ forwarding capability, status of links and nodes’ load in order to adapt to the changing network circumstance, and balance the load of the network. In addition, by introducing the concept of control gateway, the announce period of each gateway node is treated differently, thereby reducing the cost of the protocol. Simulation results show that, with LBMGR-OAR, network throughput can be boosted by 18.7%, end to end delay can be reduced by 16.2%, and load balancing index can be improved by 5.2%, compared with the typical multi-gateway routing algorithm.Finally, a wireless mesh network testbed based on S3C2440 is set up. The opportunistic forwarding mechanism of data packets is implemented on the basis of the existing routing HWMP, and the performance is tested. Test results show that the opportunistic routing can indeed improve the performance of the network.