Study on the Physical Layer Security of Cognitive Radio Networks and Its Robustness Design

This paper studies on the issue of physical layer security of MISO Cognitive Radio Networks (CRN) from the Quality of Service (QoS) perspective. By adding a suitable amount of artificial noise into the transmitting signal of the Secondary User Transmitter (SU-Tx), the security performance could be enhanced apparently. Through some appropriate transformations, the optimization problem is converted into a semi-definite programming, which can be easily solved. Furthermore, a robust optimal transmitter is designed by using the worst-case optimization approach on the premise of knowing the region of uncertainties of Channel State Information (CSI). Therefore, all the constraints can still be satisfied even with the maximal CSI errors. Simulation results verify the effectiveness of the proposed approach.