Cooperative game-theoretic approach to spectrum sharing in cognitive radios

In this paper, a framework for modeling multi-user, multi-band, spectrum sensing and sharing problem in cognitive radios as a cooperative game (CG) in a characteristic form is proposed. Secondary users (SUs) jointly sense the spectrum and cooperatively detect primary user (PU) activity for identifying unoccupied spectrum bands. A CG is formulated to quantify and share the benefits of cooperation by accessing identified idle channels in a fair manner. The characteristic function describing the CG is based on the worth of SUs, which is calculated according to amount of work done for coalition by increasing awareness about state of spectrum that may also be seen as reduction in uncertainty about PU activity. Such CGs are balanced and super-additive, making resource allocation possible and providing SUs with an incentive to cooperate and form the grand coalition. Based on their worth, SUs get payoffs that are computed using singleton solutions. SUs use payoffs earned from sensing to bid for idle channels through a scheduling mechanism, in particular, the socially optimal Vickrey-Clarke-Groves auction. Simulation results show that, in comparison with other resource allocation models, the proposed CG model provides the best balance among fairness, cooperation and performance in terms of data rates obtained by SUs.