Abstract
This paper investigates the secrecy performance of amplify-and-forward (AF)-relaying cooperative cognitive radio networks (CCRNs) over Rayleigh-fading channels. Specifically, we consider practical passive eavesdropping scenarios, where the channel state information of the eavesdropper’s link is not available at the secondary transmitter. In order to avoid interfering with the primary receiver and enhance the secrecy performance, collaborative distributed beamforming is adopted at the secondary relays. Closed-form and asymptotic expressions for the secrecy outage probability of CCRNs in the presence of single and multiple non-colluding eavesdroppers are derived. The asymptotic analysis reveals that the achievable secrecy diversity order of collaborative distributed beamforming with M AF relays is M−1 regardless of the number of eavesdroppers. In addition, simulations are conducted to validate the accuracy of our analytical results.
Highlights
1 Introduction Cognitive radio has been regarded as a potential means to improve spectral efficiency by allowing secondary users (SUs) to share the spectrum originally allocated to the primary users (PUs), as long as the generated interference aggregated at the primary receivers is below acceptable levels [1]
The main contributions of our work are summarized as follows: 1) Compared with [11,12,13,14] that only considered the relay selection for DF-relaying cooperative cognitive radio networks (CCRNs) and [15] that only considered the intercept probability for single AF-relaying CCRNs, we investigate the physical layer security in terms of the probability of non-zero secrecy capacity, the secrecy outage probability, the secrecy array gain, and the secrecy diversity order for multiple AF-relaying CCRNs with collaborative distributed beamforming in the presence of single and multiple non-colluding eavesdroppers, respectively, where distributed zero-forcing beamforming (D-ZFB) is employed at the relays without interfering with the primary users
It is worth mentioning that we focus on a passive eavesdropper scenario, where the instantaneous channel state information (CSI) of the eavesdropper’s link hRE is not known at the secondary source
Summary
Cognitive radio has been regarded as a potential means to improve spectral efficiency by allowing secondary users (SUs) to share the spectrum originally allocated to the primary users (PUs), as long as the generated interference aggregated at the primary receivers is below acceptable levels [1]. The main contributions of our work are summarized as follows: 1) Compared with [11,12,13,14] that only considered the relay selection for DF-relaying CCRNs and [15] that only considered the intercept probability for single AF-relaying CCRNs, we investigate the physical layer security in terms of the probability of non-zero secrecy capacity, the secrecy outage probability, the secrecy array gain, and the secrecy diversity order for multiple AF-relaying CCRNs with collaborative distributed beamforming in the presence of single and multiple non-colluding eavesdroppers, respectively, where distributed zero-forcing beamforming (D-ZFB) is employed at the relays without interfering with the primary users.
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