Secrecy Performance Enhancement for Underlay Cognitive Radio Networks Employing Cooperative Multi-Hop Transmission with and without Presence of Hardware Impairments

• Published in: Entropy (Basel, Switzerland) Vol. 21; no. 2; p. 217
• Main Authors: Tran Tin, Phu, The Hung, Dang, Nguyen, Tan N, Duy, Tran Trung, Voznak, Miroslav
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 24-02-2019; MDPI
• Subjects: Cognitive radio; cooperative multi-hop transmission; Data transmission; Hardware; hardware impairments; Impairment; Interference; physical-layer security; Protocol; Random variables; Receivers & amplifiers; Recursive methods; secrecy outage probability; Transmitters; underlay cognitive radio; Wireless communications; Wireless networks; underlay cognitive radio; hardware impairments; secrecy outage probability; physical-layer security; cooperative multi-hop transmission
• ISSN: 1099-4300; 1099-4300
• DOI: 10.3390/e21020217

In this paper, we consider a cooperative multi-hop secured transmission protocol to underlay cognitive radio networks. In the proposed protocol, a secondary source attempts to transmit its data to a secondary destination with the assistance of multiple secondary relays. In addition, there exists a secondary eavesdropper who tries to overhear the source data. Under a maximum interference level required by a primary user, the secondary source and relay nodes must adjust their transmit power. We first formulate effective signal-to-interference-plus-noise ratio (SINR) as well as secrecy capacity under the constraints of the maximum transmit power, the interference threshold and the hardware impairment level. Furthermore, when the hardware impairment level is relaxed, we derive exact and asymptotic expressions of end-to-end secrecy outage probability over Rayleigh fading channels by using the recursive method. The derived expressions were verified by simulations, in which the proposed scheme outperformed the conventional multi-hop direct transmission protocol.