| In recent years, the demand for wireless communications service is increasing, the requirement for the rate of wireless communication is increasing too. But our static spectrum allocation mechanism results in lot of free spectrum resource in space, the spectrum is wasted. The cognitive radio technology with smart looking and efficient use of idle spectrum resources just right provides the opportunity to use the free spectrum resource. Therefore, spectrum allocation technology of cognitive radio has also been more and more broadly concerned.Considering the principles of improving the cognitive radio network performance, two improved algorithms of spectrum allocation respectively based on graph theory and game theory are proposed in this paper.Firstly, graph theory is used to establish a mathematical model of spectrum allocation for cognitive radio spectrum allocation algorithm in order to avoid interference. According to the different network structures, spectrum allocation algorithms based on graph theory with different allocation objectives are studied. After describing the basic ideas and allocation processes of these algorithms, a spectrum allocation algorithm based on allocation sequence for centralized network is proposed. Simulation results show that the algorithm has significantly reduced the time overhead compared with existing algorithms under the same design criteria.Secondly, game theory is introduced to study the spectrum allocation for cognitive radio. Game theory and cognitive radio spectrum allocation problem is associated to build game theory based spectrum allocation model, then the existing spectrum allocation models are introduced. On this basis, a game theory based spectrum allocation algorithm with new utility function is proposed and the best response strategy is analyzed for the game process. The simulation results prove the superiority of the algorithm to improve the signal interference ratio performance compared with existing algorithm. |
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