Spectrum leasing via cooperation with multiple primary users

Within the paradigm of spectrum leasing via cooperation, primary (licensed) nodes can lease some of the owned spectral resources to secondary (unlicensed) users in exchange for cooperation. Secondary users, in turn, set a minimal quality-of-service (QoS) requirement on the spectrum leased as a precondition for cooperation. Previous work assumed that a single primary user makes spectrum-leasing decisions in the presence of possibly multiple secondary users. In this paper, the analysis is extended to accommodate multiple primary users by adopting the framework of generalized Nash equilibrium (GNE) problems. Accordingly, multiple primary users, each owning its own spectral resource, compete for the cooperation of the available secondary users under a shared constraint on all spectrum-leasing decisions set by the secondary QoS requirements. A general formulation of the problem is given, and solutions are proposed with different signaling requirements among the primary users. Then, application of the framework is discussed for a practical example that includes communication over fading channels with retransmissions. Numerical results bring insight into the advantages of spectrum leasing and of the effectiveness of the proposed solutions.