Technology Research, Game Theory-based Cognitive Radio Spectrum Allocation

In recent years, with the development of radio communication technology, spectrum resource has been more widely employed, after which very few of the whole radio spectrum space is left. However, according to some researches, the decrease of spectrum resource is largely caused by illegitimate radio spectrum allocation of different access techniques. Such circumstances give rise to cognitive radio technologies, which can automatically examine the employment of spectrum, self-adaptively change communication parameters, and opportunely switch to the bands which are not being used by the primary users. Good agility and high utilization are some of its merits.Yet, the flexible application of spectrum expects the cognitive radio system to precisely detect and dynamically allocate the spectrum resource, and, at the same time, to help retreat and switch when primary users present themselves. Therefore, spectrum allocation is one of the key issues of the radio resource management in cognitive radio. Nowadays, the spectrum allocation study in cognitive radio has become a hotspot, and some theories, such as the allocation model based on graph theory, have thrived this research field. However, they are still tiny progress.This dissertation, by applying game theory to analyze the issue of allocation of radio spectrum, proposes a scheme to analyze the cognitive radio by using game theory. The spectrum allocation model in cognitive radio based on game theory is proposed and there are two distributed spectrum assignment algorithms proposed based on game theory too. According to the simulation of the potential game algorithm, we find that the total SIR level of the system has been obviously promoted. And this algorithm can rapidly converge to a Nash equilibrium.Firstly the dissertation gives a brief introduction of cognitive radio techniques, explaining the concept and functions of the radio. Meanwhile, it elaborates the spectrum allocation techniques in cognitive radio, and describes the current analytic models.In the second chapter, attention is paid to introduce the theory of games. The origin and development of this theory and its applications to various fields will be set forth.The third chapter describes the framework of the games theory on cognitive radio. By describing the steps to analyze the algorithm based on game theory, a scheme to analyze the cognitive radio by using game theory is proposed too. In the dissertation, we particularize some important games theory models. And at last the spectrum allocation model in cognitive radio is proposed.The keystone of the dissertation is the fourth chapter, an algorithm based on potential game theory and an algorithm based on no-regret learning theory are proposed for the spectrum assignment problem. The designing process for the algorithm is described, and a qualitative analyze for the algorithm is given.In order to check the capability of the algorithm, in the fifth chapter, with the help of OPNET net simulation tool, we build a platform for the potential game algorithm, whose convergence and effects of improving system performance has been proved after simulation. Meanwhile, the coherence of theoretical deduction and simulative results also shows the practicality of this algorithm.The cognitive radio spectrum allocation technique based on the game theory has been regarded as a new path to the dynamic spectrum allocation study. Under the game theory framework of cognitive radio, the other critical issues in cognitive radio, such as power control and access control, will all face new techniques and algorithms respectively. The coming-together of cognitive radio and the game theory will definitely lay a more solid theoretic foundation for the development of cognitive radio, and inject more pushing power into this academic field.