Connectitity And Routing In Cognitive Radio AD HOC Networks

With the development of the society, people’s demands for communication are fast increasing. The traditional allocation of static spectrum cannot meet the demand of explosive growth of the business. Meanwhile, new technologies appear unceasingly, and network operators build different types of network to serve users. But each network is independent of one another and unable to realize resources sharing. The contradiction between static network mode and dynamic demands has become a critical factor restricting the development of communication industry. Therefore, scholars have proposed Cognitive Radio Network to add dynamics in network so that it can achieve a unified resources scheduling and an efficient usage.Cognitive radio Ad hoc network is a significant branch of Cognitive Radio Network; it is applied in many important occasions for its special flexibility, such as rescue and military affairs. Ad hoc have features of fast-changing network topology and valid spectrum resources. It has very high dynamics and the dynamics have obvious impacts on the status of network connection. Normal network communication appears on the premise of the network connectivity; therefore, it’s necessary to research on network connectivity. The academia has done some research on this subject, but the exact expression between the connectivity probability of secondary network and the three main parameters, namely, the density of PUs, the density of SUs and the transmission radius of SUs has not been characterized. This thesis deduced the connectivity of Cognitive Radio Network in detail, and derived the expression of closed form.On the other hand, ad hoc is a distributed network without central node. The nodes complete a communication through method of multi-hop relay, and each communication between two nodes needs to choose some relay nodes for routing, so the routing issue is very important. This thesis deeply analyzed the previous routing algorithms in ad hoc network firstly, and then proposed a routing algorithms base on connectivity according to high dynamics and previous research in ad hoc.When deploying users in ad hoc network with existing users, firstly, it is necessary to avoid the interference to the primary users. Meanwhile, the connectivity of the cognitive radio network must be guaranteed when deploying. This thesis proposed a set of deployment method so as to avoid interference to the primary users by adjusting network size, the density of SUs and the transmission radius of SUs. In addition, along with the increase of data services, service demands display the feature of uneven distribution. Therefore, future deployment architecture of the network must reflect this feature, and a mechanism should be designed in which the information can be delivered between different networks. To the above problems, this thesis researched the deployment architecture of Cognitive Radio Network, and proposed a hierarchical architecture of heterogeneous network based on the separation of cognitive information, control information and services, the separation of control and business covering.