Performance analysis of spectrum monitoring for cognitive radios

In-band spectrum sensing protocols require that the secondary users (SU's) periodically suspend their transmission periods and sense the channel in order to determine whether the primary user (PU) has emerged or not. There is a tradeoff between the spectrum sensing period and the throughput of the SU, often referred to as sensing-throughput tradeoff. In this paper, using the receiver error count, we introduce a decision statistic to enable the SU to detect the emergence of the PU without having to interrupt its own communication. We derive closed form formulas for channel utilization of the SU and detection delay of the PU using two Markov chain models. The limits of performance for a system using the proposed decision statistic is derived and an optimization problem is solved to maximize channel utilization with a constraint on detection delay. Numerical results are presented from analysis and simulation which show the accuracy of the analysis and the proficiency of the proposed algorithm.