The Spectrum Allocation Scheme Based On Graph Coloring In Cognitive Radio System

Nowadays, spectrum scarcity has become a bottleneck in the development of wireless communication technology, then the cognitive radio technology is proposed to make better use of existing spectrum resources and improve the utilization of spectrum resources, and the research on spectrum allocation policy is closely related with the condition whether the cognitive radio can achieve its fundamental objectives.The thesis mainly researches spectrum resource allocation algorithm of cognitive radio system. This paper first briefly introduces the basic concept, key technologies, system model and the existing classical spectrum allocation model of cognitive radio. In chapter 3 and chapter 4 the graph coloring spectrum allocation model is further analyzed and researched, the spectrum allocation algorithm that better meet the users'needs and spectrum allocation adjustment programs for different dynamic scenes are proposed.Chapter 3 of this paper describes the principle of the graph coloring spectrum allocation model, analyzes the latest spectrum allocation algorithms of graph coloring model , based on the shortage of the cognitive users'requirement not being satisfied, user-satisfaction is proposed, according to it, the authors set the spectrum allocation priority function. And the users, whose need is not well satisfied, were preferentially assigned. A graph coloring spectrum allocation algorithm based on the requirement is obtained. Simulation results show that the proposed algorithm can enhance the system's channel efficiency, meet the needs of multiple users'bandwidth requirements better, and improve the spectrum efficiency.Chapter 4 describes the dynamics of cognitive wireless network, the various situations that cause changes in the topology structure of cognitive wireless networks are analyzed, and then focused on the three scenes of the network topology's minor changes, corresponding spectrum allocation adjustment programs are proposed, the program is mean to simplify the re-allocation of spectrum, in order to avoid larger overhead of time caused by the redistribution of resources across the network, we only adjust and allocate the secondary users who are affected. Simulation results show that the proposed scheme can drop the complexity of spectrum re-allocation after the topology's subtle changes, reduce the overhead of time used for adjusting spectrum allocation, and make the allocation of the system's resource be adjusted quickly.