Wireless Mesh Network Routing And Security Research

With the rapid development of wireless communication and electronic technology in recent years, WMN(Wireless Mesh Network) has been the concern of many researchers. WMN is a multi-hop distributed network which is dynamically self-organized and self-configured. WMN is usually composed of mesh routes and mesh clients. WMN has excellent scalability, robustness and self-organization to support quick deployment and installation and achieve high-bandwidth high-speed routing transmission. Therefore, WMN can be applied in various scenarios such as Metropolitan Area Network, Broadband LAN, and Transportation Medical Network. In WMN, high-efficient and high quality packet transmission protocol is the core to ensure the normal operation of the network. Routing algorithms for WMN have been researched a lot. Traditional network hierarchical design method is not efficient for WMN. Due to the openness of wireless channel and time-variation of channel parameter, traditional hierarchical design method cannot ensure the utilization of network resources and the Qo S requirements of user service. Traditional routing protocols based on the minimum number of hops cannot effectively control the congestion, have poor fairness and cannot achieve the load balancing result. Therefore, using cross-layer design idea to realize new routing protocols to improve the network performance of WMN is the main goal of this dissertation. In addition, the security of WMN is being seriously challenged. And due to the exposure of wireless communication and the frangibility of multi-hop transmission, WMN is prone to various attacks, such as Node Compromised Attack, Wormhole Attack, Route Attack and Sybil Attack. This dissertation focuses on Wormhole Attack and a simple and efficient method based on local neighbor is exploited to detect wormholes. This method avoids using time synchronization or extra hardware and effectively protects the network while reducing the cost.This dissertation focuses on the research of high-efficient routing and security of WMNs.The main work is summarized as follows:1. On the basis of analysis of the challenges faced by the Wireless Mesh Routing Protocol, combined with the performance requirements of WMN, a routing protocol based on link state good degree called LR-OLSR(Link Cognitive Optimized Link State Routing) is proposed which takes Optimized Link State Routing protocol as prototype and uses the theory of crosser-layer design. This protocol obtains link quality evaluation of the path between the nodes in the network through the perception reasoning of environment information: node load, link delivery rate and link availability which can optimize the route selection, improve the network throughput and achieve load balancing. Through the simulation results compared with OLSR, LR-OLSR can improve network packet delivery ratio, reduce the average end-to-end delay and achieve load balancing to certain extent.2. This thesis makes use of a brand-new routing metric CLM(Cross-Layer Metric) to design a cross-layer based proactive routing protocol CL-OLSR based on Optimized Link State Routing protocol(Cross-Layer based Optimized Link State Routing). CL-OLSR, which takes into account four link quality impact factors through cross-layer operation mechanism in route calculation: node available bandwidth, node load, link delivery rate and link interference, thus to greatly optimize the effect of route selection. CL-OLSR is a kind of hop-by-hop forwarding routing protocols. Compared with on-demand routing protocols, CL-OLSR is more suitable for the approximate static topological characteristics of WMN and can satisfy the low-latency requirements of service traffic. Moreover, it can be used with hop-by-hop routing protocols, and the algorithm is relatively simple and efficient. And a route damping mechanism is proposed to effectively avoid the route flapping problem easily induced by load-sensitive routing metric while fully using the network resources.The simulation results show that the proposed CL-OLSR protocol improves the network throughput to large extent, reduces the end-to-end delay, and achieves load balancing route results.3. In traditional multi-hop routing protocols, some certain paths with advantages can become congested due to the heavy traffic. In order to banlance the load, a cross-layer load balance routing protocol based on AODV(LBCL-AODV) is proposed. In this algorithm, the load is migrated from overloaded route to some empty nodes or routes which can effectively balance the traffic distribution. The simulation results show that LBCL-AODV can relieve the traffic congestion and improve the average end-to-end delay and throughput.4. In order to improve the efficiency of the wormhole detection, a wormhole detection method based on 2-Hop neighbor called WDNN(Wormhole Detection based on Neighbor’s Neighbor) is proposed. And a wormhole prevention scheme RWR(Random Walk Route Scheme) is proposed. Through comparing the nodes’ position geometric relation, different local network topology can be identified whether the network is under wormhole attack. Therefore, the fake topology in network with wormholes can be found out to detect the existence of wormholes. Simulation results indicate that WDNN and RWR can efficiently detect and prevent the wormhole attacks.