Physical Layer Security in Underlay CCRNs with Fixed Transmit Power

• Songqing Wang,
• Xiaoming Xu,
• Weiwei Yang,

Vol. 9, No. 1, January 30, 2015
10.3837/tiis.2015.01.014, Download Paper (Free):

• Cooperative cognitive radio networks
• fixed transmit power
• physical layer security
• relay selection
• secrecy outage probability

Abstract

In this paper, we investigate physical layer security for multiple decode-and-forward (DF) relaying underlay cognitive radio networks (CRNs) with fixed transmit power at the secondary network against passive eavesdropping attacks. We propose a simple relay selection scheme to improve wireless transmission security based on the instantaneous channel information of all legitimate users and the statistical information about the eavesdropper channels. The closed-form expressions of the probability of non-zero secrecy capacity and the secrecy outage probability (SOP) are derived over independent and non-identically distributed Rayleigh fading environments. Furthermore, we conduct the asymptotic analysis to evaluate the secrecy diversity order performance and prove that full diversity is achieved by using the proposed relay selection. Finally, numerical results are presented to verify the theoretical analysis and depict that primary interference constrain has a significant impact on the secure performance and a proper transmit power for the second transmitters is preferred to be energy-efficient and improve the secure performance.

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