A dynamic threshold strategy against SSDF attack for cooperative spectrum sensing in cognitive radio networks

Cooperative spectrum sensing is an efficient way to improve the spectrum utilization in cognitive radio networks (CRNs), while the system performance of such CRNs is often degraded due to the spectrum sensing data falsification (SSDF) attack launched by malicious secondary users (SUs). Traditional static threshold-based decision strategy in the fusion center (FC) can be effective to defend against the deterministic SSDF attacks, but useless for the probability SSDF attacks. In this paper, based on the analysis of relationships between the threshold and the fusion value in the FC, a dynamic threshold-based strategy is proposed to defend against the probability SSDF attacks. In this method, the dynamic threshold is updated according to the fusion value´s upper and lower bounds, which are achieved by past observations of the fusion value. By this method, both the false alarm and the missed detection probabilities can be theoretically decreased. Simulation results show that our proposal outperforms the static threshold-based strategy in defending against all kind of SSDF attacks in CRNs.