Mobility Management Strategy Research In Cognitive Radio Networks Based On CPN Model

With the rapid development of wireless communication network, the diversification of the new radio business and the growth of the user demands are showing an increasing trend. Cognitive Radio(CR) technology can make full use of limited spectrum resources to meet the growing communication needs of users, relieving the spectrum resource scarcity problem from the fixed spectrum allocation policy. The spectrum access and handoff action in CR system may cause the communication time delay, packet loss, even the communication interrupt and system congestion, therefore the research about the spectrum mobility management(SMM) under the random access and handoff condition becomes very important to improve the overall performance of the system.A scientific and reasonable random service model is necessity to describe the random properties of the business and the quantitative analysis of the reliability for a qualified mobility management strategy based on the knowledge background of the cognitive radio. In this thesis, the corresponding system models are set up using Colored Petri Nets(CPN) to investigate the spectrum access strategies in CR and handover strategies in multi-business system. The main work is:The corresponding CPN models are established based on the analysis about the opportunity spectrum access strategy and the spectrum access strategy based on the secondary users waiting mechanism. The influence of the CPN model are compared with the traditional Markov analysis method through the analysis of the users’ arrival rate and system channel number to the blocking probability. The results showed that the CPN model can not only implement the Markov semantic analysis method, but also the layered structure is able to deal with the state space explosion problem of complex systems. The study about the CPN statistical properties of the unsteady system shows the advantage that CPN can overcome the constraints in obtaining the Markov steady state solution.For the researches about the spectrum mobility dealing with the kinds of businesses, the CPN model is used to analyze the four different spectrum handover strategies. The hierarchical structure in CPN model shows the strong flexible adaptability to both complex systems and strategies from the studies. Furthermore, CPN can overcome the memory-less quality from the traditional Markov model, realizing the analysis of the non-Markov mathematical model.