Security threats and countermeasures of MAC layer in cognitive radio networks

Cognitive radio is a promising technology proposed to solve the scarcity of the radio spectrum by opportunistically allocating the idle channels of the licensed users to unlicensed ones. The effectiveness of the cognitive radio is highly dependent on fair and efficient management of the access to the unused portion of the frequency channels, which is performed by the media access control layer. Therefore, any malicious activities disrupting operation of this layer result in significant performance degradation of the cognitive radio networks. As a result, it is necessary to understand functions of the media access control layer of the cognitive radio and analyze the impacts of possible attacks these functions might encounter. This paper provides an overview of different attacks that target the media access control layer of cognitive radio and analyzes them based on this layer's functions. In addition, the paper describes and compares recent defense strategies related to each attack.