Distributed Detection in Cognitive Radio Networks with Unknown Primary User's Traffic

Abstract

We consider a distributed Cognitive Radio Network (CRN) in which a number of secondary users (SUs) cooperatively sense the spectrum holes in a channel whose occupancy by the primary user (PU) follows a discrete time Markov chain. We consider a problem where the transition probability matrix (TPM) of the channel occupancy process followed by the PU is unknown. For this problem, we first propose a procedure to estimate the TPM. We then seek a distributed detection procedure with the estimated TPM. We show that our estimate of the TPM is very close to that of the actual TPM in the case of perfect sensing; in the case of imperfect sensing, the estimate has a little bias. This bias can be used to correct the estimate further. We study the detection and the false alarm characteristics of the distributed detection procedure that we propose (which uses the estimates on the channel occupancy probabilities). The proposed distributed detection procedure achieves a good Receiver Operating Characteristic (ROC) performance which is close to that of the centralised CRN.