Coalitional Games With Intervention: Application to Spectrum Leasing in Cognitive Radio

We consider a spectrum leasing system in which secondary networks offer offload services to a primary network (PN) in exchange for temporary access to the PN's spectrum. When the coverage areas of several secondary access nodes (SANs) overlap, they compete for primary users (PUs), which benefits the PN, except when the SANs collude and coordinate their prices, forming a cartel. As a result, the PN obtains lower transmission rates for the serviced PUs. Our coalitional game analysis shows that stable cartels always exist and can form easily. To protect the spectrum owner's interests and enforce market regulation, we propose an intervention framework in which an intervention manager counteracts cartel formation. The specific features that make wireless systems different from conventional markets enable the manager to modify the set of achievable outcomes. The intervention capability is limited; thus, the objective is to design an intervention rule maximizing the PN transmission rate within the given constraints. Importantly, the intervention can solely act as a threat or a warning that does not need to be executed in practice. To reduce the computational effort, we also propose a low-complexity intervention rule that performs similarly to the optimal one in terms of assurable PN rate increment and outperforms other effective approaches.