This paper studies cooperative-jamming (CJ)-aided beamforming design under Gaussian channel uncertainties to reduce the secrecy loss due to reception correlation. In light of the difficulty of maximizing the outage-probability-constrained secrecy rate, a novel quality-of-service (QoS)-based optimization is considered. By employing the Bernstein-type inequality to approximate the probabilistic constraints, we seek to maximize the target outage signal-to-noise ratio (SNR) at the destination under transmit power and SNR outage constraints. Simulation results verify the designed CJ-aided beamforming substantially enhances the secrecy from a QoS perspective.
This paper studies cooperative-jamming (CJ)-aided beamforming design under Gaussian channel uncertainties to reduce the secrecy loss due to reception correlation. In light of the difficulty of maximizing the outage-probability-constrained secrecy rate, a novel quality-of-service (QoS)-based optimization is considered. By employing the Bernstein-type inequality to approximate the probabilistic constraints, we seek to maximize the target outage signal-to-noise ratio (SNR) at the destination under transmit power and SNR outage constraints. Simulation results verify the designed CJ-aided beamforming substantially enhances the secrecy from a QoS perspective.
This article studies robust artificial noise-aided beamforming for correlated multiple-input-single-output eavesdropping channels under Gaussian channel uncertainties. In the case of high reception correlation, under a secrecy outage probability constraint, the achievable secrecy rate is very small and does not satisfy the requirements of some high-rate applications. In view of this, optimization designs on the premise of quality-of-service (QoS) assurance are considered. By exploiting the correlation and employing a novel QoS criterion of the signal-to-noise ratio (SNR) outage probability, two optimization problems, namely minimization of the target SNR at eavesdroppers and maximization of the loose secrecy rate, are formulated. Despite less rigorous secrecy, a much lower target SNR at eavesdroppers and a higher loose secrecy rate are achieved. Compared with the conventional SNR-QoS, SNR-outage-QoS is a more flexible criterion that can be applied to Gaussian channel uncertainties, although challenging probabilistic constraints are introduced into the optimization problems. To make the optimization problems feasible, two approaches, namely, the Bernstein-type inequality approach and ellipsoid bounding approach, are applied to approximate the probabilistic constraints. Simulation results show that the robust transmit designs contribute to a secrecy performance gain from the perspective of SNR-outage-QoS.
Correlation between the main and eavesdropping channels damages secrecy, the achievable secrecy rate under high correlation is small not to satisfy some high-rate applications. This paper optimizes an artificial noise (AN)-aided beamformer by employing a novel quality-of-service criterion, namely signal-to-interference-plus-noise-ratio outage-probability (SINR-OP), and seeks to maximize the target outage SINR under transmit power and SINR-OP constraints. Under Gaussian channel state information uncertainties, a robust ellipsoid-bounding-based approach is employed to approximate the probabilistic constraints; then, a suboptimal solution is obtained. The simulation results verify the proposed AN-aided beamforming achieves the high target outage SINR at the destination.
Robust quality-of-service (QoS)-based and secrecy rate-based secure transmission designs are investigated for a multiple-input single-output system with multiple eavesdroppers and a cooperative jammer. Two scenarios are considered: (a) eavesdroppers' channel state information (ECSI) is available and (b) ECSI is unavailable. In scenario (a), a QoS-based design is considered to minimize the worst case signal-to-interference-and-noise ratio at the eavesdroppers and to guarantee the QoS of the legitimate receiver. A secrecy rate-based design is also studied where the worst case secrecy rate is maximized. In scenario (b), a QoS-based design is considered to maximize the power of jamming signals under the QoS constraint of the legitimate receiver, and the secrecy rate-based design is not applicable. In all these designs, we jointly optimize the transmit beamforming vector and the covariance matrix of jamming signals under individual power constraints. As the optimization problems are non-convex, we propose an algorithm for each problem through semidefinite relaxation. Our analysis and simulation results show that, even though the linear precoding scheme in our designs is transmit beamforming rather than the general rank transmit covariance, this does not cause any loss of optimality.
In this paper, a robust quality-of-service (QoS) based secret transmit beamforming design problem is discussed for a multiple-input single-output (MISO) system which works under cooperative jamming (CJ) scheme with a helper transmitting jamming signals to confuse the eavesdropper. For the channel state information (CSI), we assume that the CSI for the legitimate link is available and the CSI for the wiretap channel is imperfect. Our system design goal is to optimize the worst-case performance of the network under the situation: minimizing the signal-to-interference-and-noise ratio (SINR) at the eavesdropper and meanwhile guaranteeing the SINR at legitimate receiver. Thus the spatial distribution of jamming signals and the beamforming vector of source are jointly optimized under a total power constraint. As this optimization problem is difficult to tackle, a method is proposed with proofs to obtain exact solver of it. Our analysis reveals that optimizing the beamforming vector of source is a better strategy compared to optimizing the spatial covariance matrix of information signals. Numerical results affirm this and show the advantage of robust transmit designs compared to a non-robust approach in lowering the SINR at the eavesdropper in the presence of channel uncertainties.
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.
This paper investigates a joint robust scheme in a secrecy relay network where distributed relays perform cooperative beamforming and a friendly jammer transmits jamming signal to enhance the information security. Specifically, we consider the outage constraint secrecy rate maximization design with imperfect channel state information. Through semidefinite relaxation and one-dimensional search, we propose a two-layer optimization method to solve the nonconvex problem. In addition, the Bernstein-type inequality and large deviation inequality are utilized to convert the probabilistic constraint. Simulation results demonstrate the performance of the proposed design.