We investigate the spectrum sharing possibility as an incentive to enhancing the physical layer security. The concept behind this is that a legitimate source-destination pair, communicating in the presence of a passive eavesdropper, stimulates the help of another source-destination node looking for transmission opportunities, referred to as secondary network (SN). We thus propose a cooperative scheme, whereby the secondary transmitter will act as a friendly jammer to confound the eavesdropper and be granted to share the spectrum of the legitimate pair, referred to as primary network (PN), as a reward. To evaluate the performance of our cooperative scheme, we derive the closed-form expression of the secrecy outage probability (SOP). However, to assess its usefulness, we introduce the mutual outage probability (MOP) and we carry out analysis to derive its expression. We show that a satisfactory SOP is a necessary condition for triggering the cooperation, whereas a satisfactory MOP is a sufficient condition to guarantee that the PN-SN collaboration leads to a win-win situation. Results have been presented considering outdated channel state information, thus giving more insights for practical setups.
We investigate the spectrum sharing possibility as an incentive to enhancing the physical layer security. The concept behind this is that a legitimate source-destination pair, communicating in the presence of a passive eavesdropper, stimulates the help of another source-destination node looking for transmission opportunities, referred to as secondary network (SN). We thus propose a cooperative scheme, whereby the secondary transmitter will act as a friendly jammer to confound the eavesdropper and be granted to share the spectrum of the legitimate pair, referred to as primary network (PN), as a reward. To evaluate the performance of our cooperative scheme, we derive the closed-form expression of the secrecy outage probability (SOP). However, to assess its usefulness, we introduce the mutual outage probability (MOP) and we carry out analysis to derive its expression. We show that a satisfactory SOP is a necessary condition for triggering the cooperation, whereas a satisfactory MOP is a sufficient condition to guarantee that the PN-SN collaboration leads to a win-win situation. Results have been presented considering outdated channel state information, thus giving more insights for practical setups.
We investigate the spectrum sharing possibility as an incentive to enhance the physical layer security. The concept behind is that a legitimate source-destination pair, communicating in the presence of a passive eavesdropper, stimulates the help of another source-destination nodes looking for transmission opportunities, referred to as secondary network (SN). We thus propose a cooperative scheme, whereby the secondary transmitter (ST) will act as a friendly jammer to confound the eavesdropper and be granted to share the spectrum of the legitimate pair, referred to as primary network (PN), as a reward. Meanwhile, the ST has to secure its own secrecy communication and thus exploit the impact of the induced interference by the PN. To evaluate the performance of our cooperative scheme, we derive the closed-form expressions of the secrecy outage probability (SOP) for both cooperative networks. However, to assess its usefulness, we introduce the mutual outage probability (MOP) and we carry out analysis to derive its expression. We show that a satisfactory SOP is a necessary condition for triggering the cooperation, whereas a satisfactory MOP is a sufficient condition to guarantee that the PN-SN collaboration leads to a win-win situation. Furthermore, an asymptotic analysis is also carried out to derive the generalized secrecy diversity for the scheme under investigation, where it has been shown that the primary system achieves its full secrecy diversity order, equal to the number of antenna at the primary transmitter. Such results present useful insights for practical design and setups.
In this paper, we investigate the secrecy performance of an underlay spectrum sharing cognitive MIMO networks with the help of a cooperative jammer (Charlie), in which the secondary transmitter (Alice) aims to communicate with secondary receiver (Bob) in the presence of an eavesdropper (Eve). In order to analyze the impact of the imperfect channel state information (CSI), the CSI of the links between secondary network and primary network, Alice and Bob, Charlie and Eve are considered to be outdated, respectively. We propose the transmit antenna selection-maximal-ratio combining/zero forcing beamforming scheme (TAS-MRC/ZFB) to improve the secrecy performance of the considered networks. Furthermore, the exact and the asymptotic closed-form expressions of secrecy outage probability are provided to analyze the impacts of the outdated CSI and the proposed TAS-MRC/ZFB on the considered networks. The results reveal that the outdated CSI between secondary network and primary network has a significant impact on secrecy performance of the considered networks in the low signal-to-noise ratio (SNR) region, the outdated CSI between Charlie and Eve will significantly deteriorate the secrecy performance of the considered networks in high SNR region. Finally, Monte Carlo simulations are carried out to verify our analysis.
In this paper, an underlay spectrum sharing based cognitive wiretap channel with multiple primary users is considered. The secondary user transmitter communicates with a secondary user receiver in the presence of multiple eavesdroppers. The secondary transmitter is assumed to have multiple antennas and the secondary receiver and eavesdroppers are equipped with single antenna each. The eavesdroppers channel state information (CSI) is found to be outdated in our case. For the coordinated eavesdropping, we have derived the exact and asymptotic closed form expression for the secrecy outage probability.
This paper investigates cooperative security in wireless networks, where a source (Alice) intends to transmit a confidential message to a legitimate destination (Bob), with the help of a cooperative jammer (Charlie), coexisting with multiple passive eavesdroppers (Eves). In particular, by assuming knowledge of Bob's perfect channel state information (CSI) but only Eves’ statistical CSIs, secrecy beamforming with artificial noise (AN) is utilized for secure transmission, and cooperative jamming (CJ) is explored to further enhance secrecy. We first derive an accurate closed-form expression for the secrecy outage probability (SOP), and establish the condition under which positive secrecy rate is achievable. Then, we provide a secure transmit design for maximizing the SOP constrained secrecy rate. Moreover, based on a strict mathematical analysis, we characterize the impact of the main channel quality and the number of Eves on transmit design and secrecy performance. Specifically, optimal power allocation ratio between the information-bearing signal and the AN signal increases as the main channel quality improves, and decreases with the number of Eves. Numerical results confirm that our design achieves performance improvement in terms of both secrecy rate and secure energy efficiency, as compared to the approach without CJ.
In this paper, we investigate the secrecy outage probability (SOP) for the cooperative decode-and-forward (DF) underlay cognitive radio networks (CRNs). Duo to the spectrum sharing approach in underlay CRNs, the secondary transmitters (secondary source (SUS) and secondary relay (SUR)) are subjected to interference power constraint at primary user (PU), and the SU receivers (SURand secondary destination (SUD)) suffer from the co-channel interferences (CCIs) from PU. We focus on the practical scenario where the SU transmitter has no channel state information (CSI) of the eavesdropper's channel. Interference-power-confined selection scheme is proposed for the cooperative DF CRNs in the presence of an eavesdropper. The proposed scheme selects the “best” terminal (SUSor SUR) to enhance the secure performance which must firstly satisfy the interference power constraint. What's more, the effect of feedback delay on the selection scheme is studied. We derive an exact closed-form expression for the SOP. Simulation results validate our theoretical analysis and show that the proposed selection scheme determinately enhance the performance, and feedback delay decreases the SOP seriously, specially, the interference power constraint hugely confine the SOP.
In this paper, we examine the physical-layer security for a spectrum sharing system consisting of multiple source-destination pairs, which dynamically access their shared spectrum for data transmissions in the presence of an eavesdropper. We propose a source cooperation (SC) aided opportunistic jamming framework for protecting the transmission confidentiality of the spectrum sharing system against eavesdropping. Specifically, when a source node is allowed to access the shared spectrum for data transmissions, another source is opportunistically selected in the spectrum sharing system to transmit an artificial noise for disrupting the eavesdropper without affecting the legitimate transmissions. We present two specific SC aided opportunistic jamming schemes, namely the SC aided random jammer selection (RJS) and optimal jammer selection (OJS), which are referred to as the SC-RJS and SC-OJS, respectively. We also consider the conventional non-cooperation as a baseline. We derive closed-form intercept probability expressions for the non-cooperation, SC-RJS and SC-OJS schemes, based on which their secrecy diversity gains are determined through an asymptotic intercept probability analysis in the high signal-to-noise ratio (SNR) region. It is proved that the conventional non-cooperation exhibits a secrecy diversity of zero, whereas the proposed SC-RJS and SC-OJS achieve a higher secrecy diversity of one. This also surprisingly means that no additional secrecy diversity gain is achieved by the optimal jammer selection compared to the random selection strategy. In addition, numerical results show that the intercept probability performance of the SC-OJS is always better than that of the SC-RJS and non-cooperation, even when the legitimate channel is worse than the eavesdropping channel.