Double Thresholds Based Cooperative Spectrum Sensing Against Untrusted Secondary Users in Cognitive Radio Networks

Spectrum sensing is an essential mechanism in a cognitive radio network. However, the detection performance will be greatly degraded when few untrusted secondary users exist which can be identified as ´Always Yes´ users and ´Always No´ users. In this paper, we propose an energy detector with double thresholds combined with revised data fusion rules to find these untrusted users and counteract their malicious effects. Probabilities of detection and false alarm of three kinds of revised data fusion rules are derived. Compared with the conventional cooperative methods, our method can get a better detection performance.