Primary user emulation attack mitigation in cognitive radio networks.
The rapid progress in the number of users and applications in wireless communication have led to the problem of growing spectrum scarcity in recent years. This imminent spectrum scarcity problem is in part due to a rapidly increasing demand for wireless services and in part due to the inefficient usage of currently licensed spectrum bands. Cognitive radio (CR) is a new technology that is proposed to improve spectrum efficiency by allowing unlicensed secondary users to access the licensed frequency bands without interfering with the licensed primary users. A malicious secondary user can decide to exploit this spectrum access etiquette by mimicking the spectral characteristics of a primary user, and gain priority access to a wireless channel over other secondary users. This scenario is referred to in literature as Primary User Emulation Attack (PUEA). Though quite a lot of research efforts have been focused on the detection and defense strategy of PUEA in cognitive radio networks, less attention have been given to combating and mitigating PUEA in a cooperative spectrum sensing environment. This dissertation seeks to contribute to research in the field of cognitive radio networks through an investigation into the impacts of Primary User Emulation Attacks (PUEA) on cognitive radio networks, the problem of trust amongst users in the networks and also mitigating the activities of PUEA in the network. An analytical and system model for PUEA in cognitive radio networks is presented and its impacts are also studied using Neyman-Pearson Composite Hypothesis Test. The intention is to evict malicious users from the network and maximize spectrum utilization efficiency. To achieve this, techniques to verify that the source of spectrum occupancy information is from a genuine user are proposed. In a primary user emulation attack, malicious users tend to destruct the spectrum sensing process of a cognitive radio network by imitating the primary signal and deceive other secondary users from accessing vacant frequency bands. An energy detection cooperative spectrum sensing technique is proposed to mitigate this attack. This technique assists in the reduction of errors made by secondary users in detecting primary user signals in frequency bands considering the existence of PUEA in the network. The performance of our proposed method is compared to an existing energy detection spectrum sensing method that does not consider the existence of PUEA in the network. Simulated results show that the proposed method can effectively mitigate PUEA in a cognitive radio network.