Game—theory Based Spectrum Sharing In Cognitive Wireless Networks

Cognitive radio technology has been considered as an efficient method to address the contradiction between supply and demand of wireless spectrum, and to improve spectrum utilization. Reasonable and efficient spectrum sharing technology is one of the important means to implementation. Wireless spectrum sharing mainly involves user access, spectrum allocation, service quality and power control. Game theory based spectrum sharing is aim at demanding imbalance, channel characteristics due to location and noise, use economic means allocating configuration and ensuring the primary users’ s economic benefit. Pirmary user allow cognitive user using idle spectrum to improve the spectrum utilization in cognitive network.Network capacity of conventional spectrum allocation remains relatively stable due to fixed spectrum. The primary user’s activities lead to randomly time-varying availabability for cognitive user. So, how to effectively manage spectrum resourses, improve the service quality and network performance, have become one of the highlight in the research direction of cognitive radio. Game theory based spectrum sharing dynamically optimize the spectrum utilization by allowing cognitive users to use the idle spectrum while bring the economic incomes of primary user in cognitive network.This thesis adopts the algorithm of the game theory to study cognitive wireless spectrum sharing strategies and methods, which involve the user access, spectrum allocation, service quality and power control. The main research contents and innovations are as follows:1) We study an underlaying model based power control problem for cognitive radio network, and propose a non-cooperative power control algorithm to jointly consider the service quality, power control, noise tolerance and interference suppression. By establishing a game model, we analyze the interference upbound for primary user, prove the existence and uniqueness of Nash equilibrium. Comparing with the conventional algorithms, our proposal require less transmission power to achieve a similar communication quality for cognitive user.2) By using the microeconomics theory, we study the power control of cognitive wireless networks, access number, channel quality, and other factors such as distance and efficiency, to improve the fairness and economic benefit of the network. Since the primary users have to incentive to participate in the spectrum sharing in the conventional power control algorithm, we put forword a kind of pricing model for interference rights by introducing power price to control the munber of cognitive users and transmission power. In this paper, we propose non-cooperative distributed power allocation algorithm based on the interference pricing. The algorithm using price lever to adjust the transmission power of cognitive users and primary users, which regulates the greedy power increase in cognitive users and incentive the primary users to share spectrum resources in order to get more economic benefits. Compare with conventional algorithm, our algorithm is more practical and has more application values.3) We propose a user coalition based spectrum sharing mechanism, where the users within the same coalition share the spectrum underlay while-the users in diffirent coalition. This strategy consider user collaboration and stable matching. We then put forword a matching algorithm based on coalition game theory. The coalition are formed, according to network status the user preference order, considering the network throughput and interests of coalitions. Using matching, we study the stability of the matching, Pareto optimally. Simulation results show throughput and fairness improvements comparing to the random pairing.