Outage probability analysis of cognitive radio networks under self-coexistence constraint

Cognitive radio networks (CRNs) are envisioned to eradicate the artificial scarcity caused by today´s stringent spectrum allocation policy. In this article, we develop a statistical framework to model the outage probability at any arbitrary primary/licensed user, while operating in the presence of a collocated secondary network/CRN. A system model based on stochastic geometry (utilizing the theory of a Poisson point process) is introduced to model the transmission/reception/detection uncertainty due to the random locations and topology of both primary and secondary users. The primary beacon enabled interweave spectrum sharing model is utilized for evaluating outage and interference at a typical primary receiver. It is shown that the self-coexistence constraint ignored in past studies plays a vital role in the determination of outage and interference. A statistical model for interference is developed to incorporate the self-coexistence constraint in terms of medium access probability (MAP). Our study also indicates that under the availability of multiple channels/sub-channels, outage probability also depends on the probability of picking the same channel. Optimal selection of MAP and channel selection probability is briefly discussed. Our analytical and simulation results further consolidate the argument that past studies which do not cater for the self-coexistence constraint, over-estimate the interference.