Optimal Sensing Time Strategy Under Primary Outage Constraint in Cognitive Radio Networks

With the underlay approach, Secondary users (SUs) can utilize the same frequency bands simultaneously with Primary users (PUs) in Cognitive radio networks (CRNs). How to choose the appropriate transmission power of SUs under the influence caused by other cells is a problem. To solve this problem, spectrum sensing is introduced to identify the existence of interference which using pilot signal to perform coherent processing. Consider the probability of detection of SUs, there exists a trade-off between the sensing time and the achievable throughput of CRNs. When the prior probability of other cells' activity is unknown to SUs, throughput of the CRNs can be viewed as a concave function. According to solving the optimization problem, the optimal sensing time is obtained. Simulation results show the feasibility and correctness.