The Relay Selection Research Based On Game Theory In Cooperative Cognitive Radio Networks

Cognitive Radio(CR)technology is an emerging technology which is to solve the scarcity of spectrum resources.It improves the spectrum utilization by optimizing and allocating the spectrum resources.Meanwhile,the integration of cooperative communication makes it have more research value.In cooperative cognitive radio network(CCRN),licensed users and unlicensed users share the same frequency band,that is to say,unlicensed users help licensed user to forward data in order to obtain the access opportunity to frequency band.However in reality,node locations and channel aspects will dramatically affect the tot al system performance,so how to select a suitable set from the CUs and enable it to cooperate with the PUs is a fundamental issue for CCRN.Because individuals are selfish and rational among users,they can compet e for spectrum each other,and game theory can effectively solve the confrontation and selection among decision-making bodies,therefore,the knowledge of Game Theory in CCRN can relatively well analysis spectrum allocation and sharing.Based on the above background,we study and analyze the relay selection among unlicensed users under the environment of CCRN.This paper first puts forward a relay selection algorithm based on Nash equilibrium,which combined with the model of spectrum leasing.In which,the spectrum price is jointly determined by primary user and cognitive users.A non-cooperative power game was built among cognitive users,and optimal cooperative power allocation was obtained.Based on which,an iterative algorithm to choose an appropriate relay set was designed in order to maximize the primary user utility.In the end,a suitable relay set is chose which can make primary user and cognitive users' utilities maximization.Consider the above algorithm based on single game in the distribution model,another algorithm combined with duopoly between primary user and cognitive users was proposed,which is relay selection based on Stackelberg.Here,the primary user acts as the decision function,while the cooperative power of cognitive users should change with the primary user.The selected cognitive users optimize their cooperative power level to maximize their utilities.Meanwhile,the idea of selection is that whether cognitive users satisfy the criteria or not.Primary user acts as maker to determine its time parameter while cognitive users' cooperative parameters depend on primary user.Simulation results show that this algorithm can select the optimal relay set to realize spectrum sharing.