Coalition Formation Game Based Cooperative Communication In Cognitive Radio Network

For the modern wireless communication with broadband and intelligentialize, the high-speed and high-quality services has emerged, which will inevitably lead to severe scarcity of spectrum resources. Cognitive Radio (CR) has been proposed as a useful technology in relieving the scarcity challenge on spectrum resources. Spectrum sharing, one of the most important technique in Cognitive Radio Network (CRN), can improve the utilization of spectrum through the cooperation among Primary Users (PUs) and Secondary Users (SUs). In the scenario where PUs coexistence with SUs, the throughput of Secondary Networks will be constrained if the Quality of Service (QoS) of PU is high. To deal with this problem, we design a cooperative communication scheme among PUs and SUs to improve communication performance. Accordingly, the different strategies, forming a game among nodes inside network, will have various influences on the benefit of network. As an effective mathematical tool in analyzing the competition and cooperation among players, game theory we use in this paper is to study the cooperation among SUs, for the purpose of improving the throughput of Secondary Network through optimizing the cooperative strategies. The highlights of my work are as following:Firstly, for the purpose of improving the communication performance both of Primary Network and of Secondary Network, we study the relay-based cooperation mechanism between PUs and SUs for the Cooperative Cognitive Radio Network (CCRN). In the system model, the source node PBS will choose several SUs as its relay nodes to improve its own communication performance, while those selected SUs can obtain some slots to transmit their own data via the licensed channel. Accordingly, the cooperation model can improve both the communication performance of PU and throughput of Secondary Network.Secondly, we put forward a relay selection algorithm on the basis of coalition formation game in order to optimize the throughput of Secondary Network when considering QoS of Primary Network. After studying the relationship of PUs and SUs, we present a mechanism to encourage SUs to participate in the relay communication cooperatively, aiming at improving relay performance. Moreover, we also prove the advantage of the proposed algorithm through simulation.Finally, to further increase the throughput of secondary network and improve the efficiency of spectrum utilization, a frequency division cooperative communication protocol is proposed, which exploits adaptive OFDM (Orthogonal Frequency Division Multiplexing, OFDM) resource allocation system to achieve the optimal matching between nodes and channels. Accordingly, we design a cooperative relay selection combining coalitional formation game and OFDM-based mechanism. The simulation results demonstrate that the scheme with frequency division structure not only improves the throughput of Secondary Network but also enhances the transmission reliability.