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This paper investigates the impact of misbehaviors, due to either device malfunctioning or malicious attacks, in cooperative spectrum sensing (SS) for cognitive radio networks. Our work emphasizes on two typical misbehaviors: Always Free (AF) and Always Busy (AB) attacks. We first derive the false alarm and miss detection probabilities of cooperative SS under each misbehavior scenario, based on which the impact of misbehaviors on the optimal combination threshold is then studied. Through the analysis and simulation, it is shown that, compared with the scenario without misbehaviors, the false alarm probability becomes lower and the miss detection probability becomes higher for AF attack's presence, while the influence of AB attack is opposite. Furthermore, the presence of AF misbehavior will lower the originally optimal combination threshold while the presence of AB misbehavior will increase it. One of the most important insights we learned from our discussion is that a cooperative SS system possesses some resistance to the misbehaviors by adjusting the threshold at local users or the combination threshold at the fusion center.
Date of Conference: 23-25 Sept. 2011