Primary exclusive region and optimality of the link-level throughput of cognitive terminals

A cognitive network consists of primary nodes, which have priority access to the spectrum, and cognitive (also referred to as secondary) nodes, which access the spectrum provided that the interference they generate in the primary system remains limited. In practice, it means that the cognitive terminals must remain outside of a region surrounding the primary receiver: the primary exclusive region. The focus of this paper is on the definition of this region and the analysis of the achievable throughput of cognitive terminals under the constraints imposed by the primary network. More precisely, we establish the fundamental limits of the terminal probability of transmission and under what conditions this throughput can still be optimal (in a network throughput sense) for the secondary network.