Nonparametric CUSUM based cooperative spectrum sensing in cognitive radio networks

In cognitive radio (CR) networks, it is crucial for secondary users to quickly detect spectrum holes when prior information of primary users is unknown. This paper proposes a new cooperative spectrum sensing (CSS) scheme based on nonparametric cumulative sum (NCUSUM) to reduce the mean detection delay under the condition of unknown prior information. The proposed scheme consists of secondary users and fusion center. Secondary users preprocess the observation data of spectrum to get positive drifts and negative drifts and only transmit positive drifts to fusion center. Fusion center uses the NCUSUM to accumulate positive drifts to make a fast decision about whether the primary signal is present or not. To ensure the false alarm probability low enough, this scheme notes that the decision can be made in certain time interval. The simulation results show that the proposed cooperative spectrum sensing scheme has better performance in reducing mean detection delay with respect to conventional soft combination schemes.