Recent studies on secure wireless communication have shed light on a scenario where interference has a desirable impact on network performance. Particularly, assuming independent interference power fluctuations at the eavesdropper and the receiver, opportunistic secure information transfer can occur on the legitimate link. However, interference is spatially correlated due to the common set of interfering sources, which may diminish the opportunistic secure spectrum access (OSSA) probability. We study and quantify the effect of spatial interference correlation on OSSA in cellular-networks and investigate the potential of full-duplex jamming (FDJ) solutions. The results highlight the scenarios where FDJ improves OSSA performance.
Recent studies on secure wireless communication have shed light on a scenario where interference has a desirable impact on network performance. Particularly, assuming independent interference power fluctuations at the eavesdropper and the receiver, opportunistic secure information transfer can occur on the legitimate link. However, interference is spatially correlated due to the common set of interfering sources, which may diminish the opportunistic secure spectrum access (OSSA) probability. We study and quantify the effect of spatial interference correlation on OSSA in cellular-networks and investigate the potential of full-duplex jamming (FDJ) solutions. The results highlight the scenarios where FDJ improves OSSA performance.
Full-duplex (FD) jamming transceivers recently have been shown to enhance the information security of wireless communication systems by simultaneously transmitting artificial noise (AN) while receiving information. In this paper, we investigate whether FD jamming can also improve the system's secrecy energy efficiency (SEE) in terms of securely communicated bits per Joule when considering the additional power used for jamming and self-interference (SI) cancellation. Moreover, the degrading effect of the residual SI is also taken into account. In this regard, we formulate a set of SEE maximization problems for a FD multiple-input-multiple-output multiple-antenna eavesdropper (MIMOME) wiretap channel, considering both cases where exact or statistical channel state information (CSI) is available. Due to the intractable problem structure, we propose iterative solutions in each case with a proven convergence to a stationary point. Numerical simulations indicate only a marginal SEE gain, through the utilization of FD jamming, for a wide range of system conditions. However, when SI can efficiently be mitigated, the observed gain is considerable for scenarios with a small distance between the FD node and the eavesdropper, a high signal-to-noise ratio (SNR), or for a bidirectional FD communication setup.
In this paper, we investigate secure short packet transmission from a legitimate transmitter to a receiver in the presence of an active eavesdropper. The aim is to gain more insights into how an active eavesdropper affects the secrecy throughput of short packet communications. The eavesdropper is assumed to have full-duplex (FD) capability, which enables performing eavesdropping and jamming simultaneously. All the communication links in the wiretap channel are assumed to be Rayleigh fading. An approximation of the average achievable secrecy throughput is proposed to measure the security of the system. The proposed approximation is examined and analysed in two different topology scenarios, which are triangular and line topologies. Then, Monte-Carlo simulations are performed to get an understanding of how good the approximation is. The results show that the closed-form expressions have a good match with Monte-Carlo simulations. We also investigate the impact of the eavesdropper's distance to the legitimate nodes as well as the different jamming power levels. Furthermore, self-interference influence on the eavesdropper is discussed.
The capacity of wireless networks is fundamentally limited by interference.A few research has focused on the study of the simultaneous effect of interference and correlation, and less attention has been paid to the topic of canceling simultaneous effect of interference and correlation until recently.This paper considers a secure wireless multicasting scenario through multicellular networks over spatially correlated Nakagami-m fading channel in the presence of multiple eavesdroppers.Authors are interested to protect the desired signals from eavesdropping considering the impact of perfect channel estimation (PCE) with interference and correlation.The protection of eavesdropping is also made strong reducing the simultaneous impact of interference and correlation on the secrecy multicast capacity employing opportunistic relaying technique.In terms of the signal-to-interference plus noise ratio (SINR), fading parameter, correlation coefficient, the number of multicast users and eavesdroppers and the number of antennas at the multicast users and eavesdroppers, the closed-form analytical expressions are derived for the probability of non-zero secrecy multicast capacity and the secure outage probability for multicasting to understand the insight of the effects of aforementioned parameters.The results show that the simultaneous effects of correlation and interference at the multicast users degrade security in multicasting.Moreover, the security in multicasting degrades with the intensity of fading and the number of multicast users, eavesdroppers and antennas at the eavesdroppers.The effects of these parameters on the security in multicasting can be significantly reduced by using opportunistic relaying technique with PCE.Finally, the analytical results are verified via Monte-Carlo simulation to justify the validity of derived closed-form analytical expressions.
This paper studies secrecy rate optimization in a wireless network with a single-antenna source, a multi-antenna destination and a multi-antenna eavesdropper. This is an unfavorable scenario for secrecy performance as the system is interference-limited. In the literature, assuming that the receiver operates in half duplex (HD) mode, the aforementioned problem has been addressed via use of cooperating nodes who act as jammers to confound the eavesdropper. This paper investigates an alternative solution, which assumes the availability of a full duplex (FD) receiver. In particular, while receiving data, the receiver transmits jamming noise to degrade the eavesdropper channel. The proposed self-protection scheme eliminates the need for external helpers and provides system robustness. For the case in which global channel state information is available, we aim to design the optimal jamming covariance matrix that maximizes the secrecy rate and mitigates loop interference associated with the FD operation. We consider both fixed and optimal linear receiver design at the destination, and show that the optimal jamming covariance matrix is rank-1, and can be found via an efficient 1-D search. For the case in which only statistical information on the eavesdropper channel is available, the optimal power allocation is studied in terms of ergodic and outage secrecy rates. Simulation results verify the analysis and demonstrate substantial performance gain over conventional HD operation at the destination.
Security issue is of paramount importance yet significant challenge for wireless communications, and this problem can be even more intricate when facing with a full-duplex adversary. In this paper, we investigate the physical layer security of a legitimate transmission link in the presence of a full-duplex active eavesdropper, who is capable to perform eavesdropping and jamming simultaneously. The legitimate user aims at a target secrecy rate while the eavesdropper intends to maximize its wiretap rate. To this end, the eavesdropper imposes a jamming signal at the legitimate receiver to stimulate higher-power legitimate transmissions and thus facilitates its eavesdropping. This, however, generates residual self-interference at the eavesdropper itself and is subject to a linear price for the jamming power. The problem is then formulated within a game-theoretic framework, where the closed-form strategies of both the legitimate user and active eavesdropper are obtained. Moreover, we analyze the performance in terms of secrecy outage probability for the legitimate link in such a hostile situation. Also provided are the simulation results which validate our theoretical analysis.
Motivated by recent developments in wireless communication, this thesis aims to characterize the secrecy performance in several types of typical wireless networks. Advanced techniques are designed and evaluated to enhance physical layer security in these networks with realistic assumptions, such as signal propagation loss, random node distribution and non-instantaneous channel state information (CSI). The first part of the thesis investigates secret communication through relay-assisted cognitive interference channel. The primary and secondary base stations (PBS and SBS) communicate with the primary and secondary receivers (PR and SR) respectively in the presence of multiple eavesdroppers. The SBS is allowed to transmit simultaneously with the PBS over the same spectrum instead of waiting for an idle channel. To improve security, cognitive relays transmit cooperative jamming (CJ) signals to create additional interferences in the direction of the eavesdroppers. Two CJ schemes are proposed to improve the secrecy rate of cognitive interference channels depending on the structure of cooperative relays. In the scheme where the multiple-antenna relay transmits weighted jamming signals, the combined approach of CJ and beamforming is investigated. In the scheme with multiple relays transmitting weighted jamming signals, the combined approach of CJ and relay selection is analyzed. Numerical results show that both these two schemes are effective in improving physical layer security of cognitive interference channel. In the second part, the focus is shifted to physical layer security in a random wireless network where both legitimate and eavesdropping nodes are randomly distributed. Three scenarios are analyzed to investigate the impact of various factors on security. In scenario one, the basic scheme is studied without a protected zone and interference. The probability distribution function (PDF) of channel gain with both fading and path loss has been derived and further applied to derive secrecy connectivity and ergodic secrecy capacity. In the second scenario, we studied using a protected zone surrounding the source node to enhance security where interference is absent. Both the cases that eavesdroppers are aware and unaware of the protected zone boundary are investigated. Based on the above scenarios, further deployment of the protected zones at legitimate receivers is designed to convert detrimental interference into a beneficial factor. Numerical results are investigated to check the reliability of the PDF for reciprocal of channel gain and to analyze the impact of protected zones on secrecy performance. In the third part, physical layer security in the downlink transmission of cellular network is studied. To model the repulsive property of the cellular network planning, we assume that the base stations (BSs) follow the Mat´ern hard-core point process (HCPP), while the eavesdroppers are deployed as an independent Poisson point process (PPP). The distribution function of the distances from a typical point to the nodes of the HCPP is derived. The noise-limited and interference-limited cellular networks are investigated by applying the fractional frequency reuse (FFR) in the system. For the noise-limited network, we derive the secrecy outage probability with two different strategies, i.e. the best BS serve and the nearest BS serve, by analyzing the statistics of channel gains. For the interference-limited network with the nearest BS serve, two transmission schemes are analyzed, i.e., transmission with and without the FFR. Numerical results reveal that both the schemes of transmitting with the best BS and the application of the FFR are beneficial for physical layer security in the downlink cellular networks, while the improvement due