Artificial Noise-Aided Secure Cognitive Radio Networks: Design and Performance Analysis
Abhilash Goswami, Shilpa Rao · 2024
Physical layer security (PLS) techniques are increasingly being employed to secure transmissions in wireless networks. Unlike traditional cryptography-based methods, PLS is advantageous because it does not require a shared key between the transmitter and receiver. We employ artificial noise (AN)- aided PLS technique to secure the secondary messages from an eavesdropper (ES) in an instantaneous interference-constrained underlay cognitive radio network (CRN). The relay forwards the message of the secondary source (SS) to the secondary destination (SD). ES eavesdrops on both the SS's and relay's messages. To degrade the reception of SS's message at ES, SD transmits AN during SS's transmission. Further, ES's interception of the relay's message is impaired as SS transmits AN concurrently with the relay's transmission. For this AN-aided secondary network, we study the secrecy outage probability (SOP), which is the probability that the capacity of the secondary network is below a given transmission rate, and the intercept probability (IP), which is the probability that the eavesdropper channel capacity exceeds the difference between the transmission and the secrecy rates. For Rayleigh fading links, we provide closed-form expressions for SOP and determine asymptotic SOP at high transmit power. Further, our simulations verify the theoretical SOP result and compute the IP. Our results highlight the effects of transmit power, primary interference threshold, and channel fading on SOP and IP. We observe that though high transmit powers reduce SOP, they increase IP of the system. We also find that for high SD-ES channel gains, AN reduces the IP.