Research Of Power Allocation Algorithm In Cognitive Radio Networks

Cognitive Radio (CR) technology is proposed as a new spectrum sharing technology to fully utilize the scarce spectrum resource. It provides cognitive user a new method to share spectrum resource allocated to authority users, thus increase efficiency of spectrum usage. This paper aims at investigate the impact of interference power at authority user caused by cognitive users, and applies game theory to power allocation issue among cognitive users.Through the research of power allocation, power control and the application of game theory in cognitive radio, this paper selects proper mathematical model to model the interference power at a primary user generated by secondary users, and studies the distribution of the interference power using a characteristic function based numerical approach. Based on the system model in which multiple secondary users coexist in cognitive radio network, this paper proposes a game-based distributed power allocation algorithm by designing an effective cost function. The existence and uniqueness of the Nash Equilibrium was proved for the algorithm. In addition, considering the network topology is rapidly changing in practical cognitive radio networks, we improve the power allocation algorithm and present a iterative distributed power allocation algorithm. The algorithm can rapidly converge to Nash Equilibrium within a few iterative steps in order to shorten the power reallocation time. The simulation results show that the proposed algorithm can achieve the maximal profits of operators for cognitive radio networks. The algorithm can adapt to dynamic change of cognitive radio network topology and is suitable for cognitive radio network in dynamic topology.