Power Control Research Based On Game Theory For Cognitive Radio

With rapid development&wide application of radio communication technology and more and more business models, available wireless spectrum resource becomes increasingly scarce. The current fixed wireless spectrum allocation method gets valuable spectrum resource used inefficiently. Cognitive radio technology is widely regarded as the best solution to resolve this contradiction. It enables authorized users to share spectrum with non-authorized users, but it brings interference among users. So power control is very important for cognitive radio.The algorithm of power control in cognitive radio system needs to meet four requirements:1. Ensure normal communication of authorized users;2. Minimize transmission powers of cognitive users to reduce the interference to others users and increase the life of terminal battery;3. Meet QoS requirements of cognitive users;4. The algorithm should be simple to calculate quickly and analyze so that it can adapt the time-varying characteristic of cognitive radio network.Game theory is a powerful mathematics tool which can rationally select strategy to maximize utility in the problem of interest conflict. It has been used widely in the aspect of power control. Based on the above four points, the paper will study the power control of cognitive radio based on game theory. The main research contents include:1. The non-cooperative game power control model of cognitive radio. The utility function of cognitive radio can be optimized by using Nash equilibrium as the basic design standard. This paper presents the power control algorithm based on non-linear SINR pricing function. This algorithm reduces the vicious competition and the interference. With the precondition of ensuring fairness among cognitive users and the normal communications of authorized users, it makes Nash equilibrium Pareto optimal and follows the principle of wireless spectrum resource optimum use. In addition, the algorithm facilitates rapid calculation and analysis when improving the performance of power control.2. The authorized-cognitive user dynamic spectrum trading power control model based on Stackelberg game. The authorized user is considered to participate in the game and the benefit mechanism is introduced. The algorithm arouses the authorized user’s enthusiasm to share the spectrum with the cognitive users. By dynamically adjusting unit interference price, the authorized user can limit the total interference caused by the cognitive users. Also, the authorized user can gain maximum benefit when ensuring normal communication.3. Joint transmission rate and power control model in Stackelberg game. Joint rate and power control is good for the development of various rate businesses of next generation wireless communication system. In the framework of Stackelberg game, the joint rate and power control algorithm in this paper provides various transmission rates. And also, by the effective control of rate, it can reduce power loss and the interference to other users.4. The spectrum resource optimization model based on network utility. From the viewpoint of social optimum, this paper presents cognitive network utility function. It not only makes the cognitive users share spectrum resource fairly but also effectively enhances the cognitive network throughput and energy efficiency. In addition, by introducing maximum interference threshold elasticity, a flexible and autonomous decision-making program is provided for authorized-cognitive user dynamic spectrum trading. From an economic point of view, it maximizes the utilization of spectrum resource and realizes the win of two sides.