The Study Of Thead Hoc Routing Protocol Under Cognitive Radio Circumstances

With the boom of Wireless Network,the Ad-hoc network which is independent with infrastructure,has been also developed quickly. However, the spectrum they occupied has become more and more crowded respectively. The promotion of Cognitive Radio technology is right targeted on the challenge of limited spectrum resources. The fundamental point of departure for Cognitive Radio is: the unlicensed users (Secondary Users) can occupy the free spectrum with"Opportunistic Way"when the licensed users(Primary Users) is idle.This thesis introduces the development progress of Cognitive Radio technology and Cognitive Ad Hoc network, including their typical applications,key technologies like routing protocol , and we also analyze the multiple channel technique in Ad Hoc network to resolve the limitation of single channel network. The associate simulation results show that multiple channel technique will improve the system performance in large scale than the single channel.Against the problems in channel management of Cognitive Ad Hoc network, we proposed a new channel management mechanism. This mechanism focuses on several aspects: channel distribution, channel initialization, new Hello message, channel switch and channel information update. We analyzed the advantages of this mechanism logically, and then simulate with target metric specifically, which proves the channel management can work well.We proposed a new cross layer routing protocol named CLC-DSDV( Cross Layer Cognitive Destination Sequenced Distance Vector Routing Protocol ),which is the combination of former channel management mechanism and DSDV routing protocol. The main work done here are the implements of channel distribution, new route message, channel switch and route algorithm. The novel protocol considers the load of forward node in route search to make the route setting up process more balanced; distribute the data channel with the overall route table in pro-active route protocol; embed the channel information into the route message to make sure the neighbor node can be updated in time and have no stale information. This protocol can be proved by the simulation result that it will improve the spectrum utilization of the total system significantly and satisfy the need of Cognitive environment in throughput, delay, drop-ratio and route-load.