Covert Communication Against a Full-Duplex Adversary in Cognitive Radio Networks

Covert communication is able to provide high-level security by protecting communication behavior. In this paper, we develop a covert cooperative cognitive radio (CCCR) network, where primary transmitter (PT) transmits information with the aid of multiple secondary transmitters (STs). In return, STs are able to transmit private information by exploiting PT's spectrum in presence of a powerful eavesdropper (Eve). Meanwhile, we propose a cognitive user scheduling scheme based on link information and maximum-minimum principle. Moreover, we derive Eve's expected detection error probability and evaluate the covert performance of the novel scheme. Numerical results show that joint impact of self-interference and jamming power of Eve can enable STs to achieve covert transmission. Furthermore, it can be found that the influence of the interference power on Eve's detection error probability and covert performance is significant when the self-interference cancellation coefficient is sufficient large.