Cognitive Radio Network Routing Technology

Cognitive radio (CR) technique is an intelligent spectrum sharing technology which can detect the wireless environment. Cognitive radio users can exploit the licensed but underutilized spectrum when they don't cause harmful interference to primary users, thus to realize the multi-dimensional spectrum utilization and improve the spectrum efficiency. Because of the unique characteristic of spectrum using, the topology and available spectrum of cognitive radio networks vary dramatically. In cognitive radio systems, routing technology in network layer should consider the spectrum information from other layers. In order to realize the spectrum-aware routing algorithm which can meet the requirements of network characteristics and the actual traffic business, this thesis investigates the routing technique in different cognitive radio network architectures, especially in distributed and hybrid cognitive radio networks.The first chapter of this thesis introduces research background of cognitive radio technology and analyzes the research status of routing technique. The differences between traditional wireless networks and cognitive radio networks are pointed; meanwhile, based on the characteristics and problems of routing in cognitive radio networks, the research meaning is indicated.The second chapter starts from architectures of cognitive radio networks and describes three kinds of networks, centralized, distributed and hybrid networks. Through the analysis of routing technique in different networks, this thesis mainly investigates routing in distributed network and hybrid network.The third chapter proposes a QoS-based fair routing protocol in distributed cognitive radio networks. According to the spectrum properties, the spectrum channels can be classified into two types, constant channels and intermittent channels. In addition, QoS and fairness indexes and system model are defined. With the purpose of satisfying QoS requirements and fairness of traffic flows, a new routing metric and protocol process are designed. Simulation results show that this routing protocol can increase network fairness while not hurt the QoS satisfaction, especially appropriate to the multi-flow scenario. Based on Hierarchical Spectrum Shared Network (HSSN), the fourth chapter of this thesis proposes a price-based spectrum allocation relay routing algorithm. Since the method and rule of available spectrum identification and classification implement the communication mechanism how to use different spectrum categorizes for different service requirement, this part uses economic model to price the spectrum resource in one HSSN cell. The algorithm designs the price factors, utility functions and revenue functions, and combines spectrum allocation with routing selection. Simulation results show that this routing algorithm tends to choose distributed routing in order to maximize the network revenue, thus it can mitigate the interference to primary users and promote the network throughput.In the last part, the research results of this thesis are concluded and the future research plans are proposed.