Performance analysis of an opportunistic CSMA scheme in cognitive radio networks

We consider a cognitive radio network where both primary and secondary networks share the same spectrum resources. The secondary network is assumed to operate via a random access and to be composed of multiple secondary stations (transmitters) and a single secondary access point (receiver). At a primary receiver, an allowable interference-level p is predefined as an interference constraint. In this paper, we propose a cognitive opportunistic p-persistent carrier sense multiple access (COpCSMA) scheme for the spectrum sharing network. The proposed scheme efficiently exploits the channel opportunity existing in both primary and secondary networks and yields nearly the optimal performance of the secondary network. We mathematically analyze the performance of the proposed scheme and the numerical examples illustrate that the analytical results match well with the simulation results.