Modeling spectrum sharing in cognitive radio networks by oligopolistic virtual market

In a cognitive radio network (CRN), primary (or licensed) users share their unoccupied frequency spectra with secondary (or unlicensed) users to improve the efficiency of spectrum usage. In this paper, we address the problem of dynamic spectrum sharing in a CRN consisting of multiple PUs that compete with each other to offer spectrum access to a single SU. This situation is formulated as an oligopoly market. For PUs, a new price function is proposed which is defined in order to maximize PUs´ profits in terms of the amount of spectrum demanded by the SU. Furthermore, SU uses the Cournot game model to define its spectrum demands from different PUs. Nash equilibrium is considered as the solution of this game. We consider two different cases: Static Game and Dynamic Game; the stability condition of the proposed dynamic game is investigated. We also compare our results with those of [5]. Simulation results show that our proposed model provides larger shared spectrum sizes, higher offered prices and profits for PUs and larger stability region.