Distributed Spectrum Sensing and Access with Secondary Channel Quality in Cognitive Radio Networks

We consider a cognitive radio network where many secondary users compete with each other for a primary spectrum. The design objective is to determine, in each frame, which secondary user (SU) transmits data when primary user (PU) is idle. We propose a sensing and access scheme which is adopted in a fully distributed manner. First we assume that there is no sensing error and compare the average throughput of the proposed scheme with that of optimum. The performance of the proposed scheme if there is no sensing error has a feature similar to optimal case. And the performance is improved in a large network with much more secondary users. Next we analyze the performance of the proposed scheme if there is sensing error. Under imperfect sensing, the average throughput of the proposed scheme shows a different feature. The numerical examples show that there exists the optimal number of SUs and sensing duration to maximize the average throughput for a given target detection probability.