Researches On Key Techniques Of Hierarchical Spectrum Sharing Network Based On Cognitive Radio

Cognitive radio technology, which is considered as a confined concept in coined stage, has become one of ten hotspot communication technologies in the future. Its researches involve network architecture and key technologies from PHY layer to network layer. From the perspective of characteristic in cognitive radio, this thesis proposes a network architecture based on cognitive radio, which is called as Hierarchical Spectrum Sharing Network (HSSN). Furthermore, some key technologies in such network are studied, such as spectrum management and allocation, and cross-layer design for performance optimization.In Chapter 1, background and significance of researching on cognitive radio is firstly investigated, then the research status and problems of researching on its network architecture and key techniques are reviewed and summarized, meanwhile, based on the impact of cognitive radio's characteristic on the network architecture and its key technologies, the main research motivation and startpoint of this thesis is also indicated.In Chapter 2, based on the spectrum heterogeneity and interference in cognitive radio network, hierarchical spectrum sharing network based on cognitive radio is proposed which involves the idea of hierarchical spectrum sharing, the method and rule of available spectrum identification and classification implementing such network, and the communication mechanism how to use different spectrum categorizes for different service requirement. Furthermore, the framework of protocol stack model for the HSSN is constructed, in which the function modules that is tightly related to characteristic of the HSSN are determinated. The HSSN can realize optimization for network architecture and be satisfied with requirement of dynamic spectrum allocaion, while it can significantly provide a considerable extension to the available spectrum.In Chapter 3, a cooperative spectrum etiquette based on game theory is proposed for ad hoc mode in the HSSN. By using shared information between cognitive radio users, the actions between them are coordinated to meet the requirement of communication. Simulation results indicate this etiquette can quickly converge while it has the ability of strong anti-interference.According to the communication mechanism proposed in Chapter 2, the selection rules corresponding to different spectrum types in the HSSN are also proposed in Chapter 4. Meanwhile, the spectrum allocation control mechanism for different spectrum categories under different service requirement is explored. It points out that decentralized control, centralized control or both is selected according to different network status and the corresponding communication mechanism in such network. Moreover, using the method of graph theory, two spectrum allocation algorithms considering user requirement are proposed. One algorithm only considers requirement, while another algorithm considers both user requirement and fairness. Simulation results indicate that the former are better satisfied with user requirement while the latter are better satisfied with user requirement and fairness.Finally, the cross-layer optimization in the HSSN is researched. The route selection strategy combined with spectrum characteristic, which adopts the rule of maximum the minimum interference margin for selecting high stability route, is also proposed. This strategy is better than random selection in effectively reducing the interference to primary users. Meanwhile, the algorithm of link scheduling joint with power control, which considers how to guarantee meeting requirement of directional link in short time under interference limited, is also presented. Simulation results show that throughout and the scheduling performance in the system can obviously be improved.