The Study Of The Spectrum Sharing Algorithm Based On Game Theory

Cognitive radio is born which brings a promising future to solve the problem of spectrum shortage and improve the low efficiency of spectrum utilization. And spectrum sharing is always the and prosperity in the cognitive radio system. Since its concept was pioneered, the research method based on game theory emerges. Game theory, which based on the precise mathematical models, is a useful tool to solve the conflict problem between the decision makers and help them to make decisions in the real world. But the research is not much and the existing algorithm is limited. Therefore, to develop the new spectrum sharing models and the application of game algorithms is extremely meaningful both in theoretical and realistic aspects.In this thesis, firstly, the theoretical framework of spectrum sharing system in cognitive radio network is established and the game model for the spectrum sharing in cognitive radio network is proposed based on the analysis of the existing spectrum sharing models. Secondly, with the application of this model, three game theoretical algorithms are designed. The lending spectrum behavior of primary users in cognitive radio is analyzed using game theory. With the application of the game model for the spectrum sharing, the concept of spectrum diversity is introduced and the game theoretical algorithm is designed with the goal of improving its efficiency of spectrum utilization. The specific influences of vertical diversity on the positivity of primary system's spectrum sharing and the efficiency of spectrum utilization is presented.Aimed at the problem of spectrum sharing among a primary user and multiple secondary users based on Game Theory, an improved utility function of the second user is proposed. Not only the different spectrum requirements as a result of the different service among second users but also the influence of the shared spectrum on the spectrum demand have been taken into consideration in the spectrum demand parameter of the function, the more spectrum the second user shared, then the demand for spectrum will be relatively less severe. The demand degree in the utility function is a function of spectrum sharing, so it is a variable which can more accurately describes the cognitive radio system features in meeting the needs of users of the spectrum, and better reflect the spectrum allocation of the equity. This paper also analyzed the impact of the spectrum demand function on the spectrum sharing algorithm based on game theory. The theoretical analysis and simulation reveal the validity of the proposed algorithm and the existence of Nash equilibrium. A novel model based on the auction theory and the mechanism of compensation and motivation is proposed in this paper to characterize and analyze some inherent features in the problem of dynamic spectrum sharing for primary users and secondary users. In specific, just because spectrum auctions are different from traditional auctions studied by economists, we develop this co-operative competition model based on simplified VCG mechanism which is more suitable for this kind of spectrum auction framework, and by using the mechanism of monetary compensation and motivation, we introduce the cooperative relationship between secondary users into this scheme. Due to its special feature, this novel model showed not only the patterns of the non-cooperative game model which the decision-making can be automatically implemented, but also the fairness characteristics of the Oligopoly Joint Model. In addition, based on this model, we analyze how each primary user takes"precautions"to avoid the degradation of its own performance which can provide a better guarantee for the"peaceful"coexistence of primary users and secondary users. Theoretical analysis and simulation results evaluate the system performance and verify the correctness and fairness of the proposed algorithm.