Collision Penalty-based Defense against Collusion Attacks in Cognitive Radio enabled Smart Devices

Cooperative spectrum sensing among cognitive radio (CR) enabled smart devices improves the sensing performance in deep fading environments. However, it is prone to attacks by malicious users. These attacks become more severe when they are launched in collusion. In this paper, a collision penalty-based attack prevention method is proposed to protect honest CR enabled smart devices from individual and collusion attacks. First, an optimal decision fusion rule which maximizes the throughput of each CR enabled smart device is proposed. Then, we identify the possible malicious strategies and prevent them with appropriate bounds on the penalty. Investigations are based on the malicious utility obtained by the attackers after playing malicious strategies, and the utility reduction capability of an attack prevention mechanism. Simulations demonstrate that the proposed mechanism can achieve up to 700% of malicious utility reduction as opposed to 150% and 100% in the cases of existing Moral Hazard Principal Agent (MHPA) and friendly jammer attack prevention schemes. A game theoretic analysis of the proposed method shows that a unique Nash Equilibrium is achieved when all the CR enabled smart devices are honest.