Investigation of Primary User Emulation Attack in Cognitive Radio Networks

Cognitive radio technology (CR), as a key enabling functionality for the next generation (xG) mobile communication, can remarkably improve the performance of a wireless communication system by being aware of the changes of its surrounding and dynamically modifying its operating parameters to adapt such changes. Recently, the security issues of cognitive radio (CR) networks have drawn more and more research attentions. As the one of attacks against CR system, primary user emulation attack (PUEA) compromises the spectrum sensing of cognitive radio, where a malicious user forestalls vacant channels by impersonating the primary user to prevent other secondary users from accessing the idle frequency bands. In this thesis, we first introduce the background, motivation and advances of cognitive radio technology and summarize the security issues in the cognitive radio networks. After presenting the concept of spectrum sensing as well as its implementation approaches and current challenges, we propose a new cooperative spectrum sensing scheme, considering the existence of PUEA in CR networks. In the proposed scheme, the sensing information of different secondary users is combined at a fusion center and the combining weights are optimized with the objective of maximizing the detection probability of idle channels under the constraint of a required false alarm probability. We also investigate the impact of the channel estimation errors and multiple PUE attackers on the detection probability. Numerical and simulation results illustrate the advantages of the proposed scheme over the conventional maximal ratio combining (MRC) scheme in the cooperative spectrum sensing with the existence of PUEA.