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In a cognitive radio (CR) network, frequency spectrum can be shared between primary (or licensed) users and secondary (or unlicensed) users, where the secondary users (SUs) pay the primary users (PUs) for radio resource usage. In this paper, we address the problem of spectrum sharing in a cognitive radio environment in which multiple PUs with spectrum opportunities compete with each other to offer spectrum access to the only one SU. Each of the PUs aims to attract more demands from SU so there is a competition among PUs. This situation is formulated as an oligopoly market. For the SU, we adopt Hackner utility function to obtain the demands for the frequency channels (which have fixed bandwidth sizes). SU's demand for each channel is a function of its price. The novelty of this paper is that each channel price is the average of all offered prices by the PUs which can provide that channel. PUs' price competition for maximizing their own profit is modeled by the Bertrand game. Nash equilibrium is considered as the solution of this game. We will consider two different cases: Static Game in which each PU can observe the adopted strategies and the profit of others and Dynamic Game in which the strategy of each PU is selected based on only the information obtained during the game. At the end, the stability condition for the dynamic spectrum sharing game is investigated.
Date of Conference: 23-25 Sept. 2010