Design And Simulation Of Power Control Schemes In Cognitive Radio Networks

With the fast development of communication technology and rapid expansion of wireless traffic, the shortage of spectrum resources has become increasingly prominent. At present, cognitive radio is the most popular technology to solve this problem. By reusing the licensed bands, it opened up a new way to overcome the contradiction between the growing wireless traffic and spectrum scarcity. As one of the key technologies in cognitive radio, power control can be used to protect the active primary users from harmful interference caused by secondary users and provide reliable transmission opportunities to secondary cognitive users, thus ensuring the purpose of increasing the throughput of the cognitive radio network (CRN) and the fairness of resource allocation. Taking into account the characteristics of the CRN, to combine power control and the utilization of the spectrum can further improve the bandwidth efficiency.This thesis studies the power control schemes in CRN, and proposes two schemes based on practical applications after a detailed analysis on the current research results. First, considering the requirements of fairness and effectiveness of resource allocation in the CRN, this thesis proposes a new power control algorithm based on a cooperative game theoretic framework. The existence, uniqueness, and fairness of this game solution are proved analytically. In order to obtain the global optimal solution, the differential evolution algorithm is used to solve the problem. The Nash bargaining solution is the optimal power allocation scheme for the secondary users. Then, to further increase the throughput, a joint power control and spectrum sensing algorithm is proposed after the research on the spectrum sensing problems in CRN from which we obtain spectrum sensing period and spectrum sensing time. The algorithm maximizes the CRN’s throughput through the utilization of the authorized band based on the interference constraint to the primary users.In order to prove the feasibility and effectiveness of the two proposed algorithms, this thesis performs simulations by Matlab. The results show that the two proposed algorithms can increase the CRN’s throughput and guarantee the fairness of the secondary users as well as maximum bandwidth utilization efficiency compared with the traditional power control algorithms.