In this article, we develop an alternate-jamming-aided wireless physical-layer surveillance protocol where two devices (M1and M2) work cooperatively to eavesdrop on and intervene in a suspicious transmission link from a source (S) to a destination (D). Unlike existing approaches which rely on the use of a multi-antenna full-duplex radio as the monitor, in our protocol, M1and M2are both single-antenna nodes operating in half-duplex mode, which alternately perform proactive eavesdropping and jamming to mimic the behavior of a full-duplex monitor. Within any time slot, M1sends a jamming signal to deteriorate the signal reception at D and M2eavesdrops on the transmission from S. During the next slot, M1overhears the signal sent from S, and M2forwards its received signal during the previous slot to realize jamming. In this manner, the jamming signal received at M1can be perfectly removed after self-interference cancellation, and the signals from S during the two consecutive slots are jointly decoded with high reliability, thus enabling successful surveillance. On the other hand, the detection performance at D is heavily degraded due to the injection of the jamming signal, thereby preventing information leakage from S to D. The performance of the proposed protocol is analyzed in terms of the eavesdropping non-outage probability, the surveillance success probability, as well as the symbol error probability. Theoretical analysis and simulation results demonstrate the superiority of our design compared to competing solutions in the literature.
In this article, we develop an alternate-jamming-aided wireless physical-layer surveillance protocol where two devices (M1and M2) work cooperatively to eavesdrop on and intervene in a suspicious transmission link from a source (S) to a destination (D). Unlike existing approaches which rely on the use of a multi-antenna full-duplex radio as the monitor, in our protocol, M1and M2are both single-antenna nodes operating in half-duplex mode, which alternately perform proactive eavesdropping and jamming to mimic the behavior of a full-duplex monitor. Within any time slot, M1sends a jamming signal to deteriorate the signal reception at D and M2eavesdrops on the transmission from S. During the next slot, M1overhears the signal sent from S, and M2forwards its received signal during the previous slot to realize jamming. In this manner, the jamming signal received at M1can be perfectly removed after self-interference cancellation, and the signals from S during the two consecutive slots are jointly decoded with high reliability, thus enabling successful surveillance. On the other hand, the detection performance at D is heavily degraded due to the injection of the jamming signal, thereby preventing information leakage from S to D. The performance of the proposed protocol is analyzed in terms of the eavesdropping non-outage probability, the surveillance success probability, as well as the symbol error probability. Theoretical analysis and simulation results demonstrate the superiority of our design compared to competing solutions in the literature.
In this paper, we develop a wireless physical-layer surveillance scheme where two devices (M1and M2) work cooperatively to eavesdrop on and intervene in a suspicious transmission link from a source (S) to a destination (D). Unlike existing approaches which rely on the use of a multi-antenna fullduplex radio as the monitor, in our scheme, M1and M2are both single-antenna nodes operating in half-duplex mode. Within any odd time slot, M1sends a jamming signal to deteriorate the signal reception at D and M2eavesdrops on the transmission from S. During the next (even) slot, M1overhears the signal sent from S, and M2forwards its received signal during the previous slot to realize jamming. In this manner, the jamming signal received at M1can be perfectly removed after self-interference cancellation, and the signals from S during the two consecutive slots are jointly decoded with high reliability, thus enabling successful surveillance. On the other hand, the detection performance at D is heavily degraded due to the injection of the jamming signal, thereby preventing information leakage from S to D.
In this paper, we consider a wireless surveillance system, where two single-antenna legitimate devices work cooperatively to monitor a suspicious link between a source (S) and a destination (D). A rotated-jamming aided proactive eavesdropping scheme is proposed. In our scheme, one device acts as a legitimate eavesdropper (E) to perform information interception while the other works as a helping jammer (J) to interfere with the suspicious link. The proposed scheme is based on the fact that the received information- bearing signal at E can be totally represented by its projection onto a specific direction u. If node J's jamming signal is adaptively rotated to be restricted in the direction orthogonal to u, the detection of S's information at E can be free-of-interference, and the legitimate eavesdropping is successfully realized. Meanwhile, since the jamming signal arrives at E and D through different channels, the orthogonality does not hold at D and the jamming signal cannot be eliminated, thereby causing an irreducible error floor at the suspicious destination. We present a detailed description of the proposed scheme, and develop a criterion of choosing the optimal direction u* such that the symbol error probability (SEP) at E can be minimized. Finally, simulation results verify the effectiveness of the proposed scheme.
In this paper, we consider a wireless surveillance system, where two single-antenna legitimate devices work cooperatively to monitor a suspicious link between a source (S) and a destination (D). A rotated-jamming based proactive eavesdropping scheme is proposed. In our scheme, one device acts as a legitimate eavesdropper (E) to perform information interception while the other works as a helping jammer (J) to interfere with the suspicious link. The proposed scheme is based on the fact that the received information-bearing signal at E can be totally represented by its projection onto a specific direction u. If node J's jamming signal is adaptively rotated to be restricted in the direction orthogonal to u, the detection of S's information at E can be free-of-interference, and the legitimate eavesdropping is successfully realized. Meanwhile, since the jamming signal arrives at E and D through different channels, the orthogonality does not hold at D and the jamming signal cannot be eliminated, thereby causing an irreducible error floor at the suspicious destination. We develop a criterion of choosing the optimal direction u* such that the symbol error probability (SEP) at E can be minimized. Moreover, the performance of our scheme is analyzed in terms of SEP, relative eavesdropping rate, as well as surveillance success probability. Finally, simulation results verify the effectiveness of the proposed scheme.
To improve national security, government agencies have long been committed to enforcing powerful surveillance measures on suspicious individuals or communications. In this paper, we consider a wireless legitimate surveillance system, where a full-duplex multi-antenna legitimate monitor aims to eavesdrop on a dubious communication link between a suspicious pair via proactive jamming. Assuming that the legitimate monitor can successfully overhear the suspicious information only when its achievable data rate is no smaller than that of the suspicious receiver, the key objective is to maximize the eavesdropping non-outage probability by joint design of the jamming power, receive and transmit beamformers at the legitimate monitor. Depending on the number of receive/transmit antennas implemented, i.e., single-input single-output, single-input multiple-output, multiple-input single-output, and multiple-input multiple-output (MIMO), four different scenarios are investigated. For each scenario, the optimal jamming power is derived in a closed form and efficient algorithms are obtained for the optimal transmit/receive beamforming vectors. Moreover, low-complexity suboptimal beamforming schemes are proposed for the MIMO case. Our analytical findings demonstrate that by exploiting multiple antennas at the legitimate monitor, the eavesdropping non-outage probability can be significantly improved compared with the single-antenna case. In addition, the proposed suboptimal transmit zero-forcing scheme yields similar performance as the optimal scheme.
Surveillance performance is studied in this paper for a wireless eavesdropping system, where a full-duplex legitimate monitor eavesdrops a suspicious link efficiently with the artificial noise (AN) assistance. Different from the existing work, the suspicious receiver is assumed to be capable of detecting the presence of AN. Once such receiver detects the AN, the suspicious user will stop transmission, which degrades the surveillance performance. Hence, to improve the surveillance performance, AN should be transmitted covertly with a low detection probability. Under these assumptions, an optimization problem is formulated to maximize the eavesdropping non-outage probability under a covert constraint. Based on the detection ability at the suspicious receiver, a novel scheme is proposed to solve the optimization problem using an iterative search. Moreover, we investigate the impact of both the suspicious and the jamming links uncertainties on the covert surveillance performance. Simulations are performed to verify the analyses. We show that the suspicious link uncertainty enhances the surveillance performance, while the jamming link uncertainty can degrade the surveillance performance.
From the perspective of national security, legitimate government agencies have long been committed to enforcing powerful surveillance measures on suspicious individuals or communications. This paper investigates a wireless legitimate surveillance system, where a full-duplex multi-antenna legitimate monitor aims to eavesdrop on a dubious communication link between a suspicious pair via proactive jamming. It is assumed that the legitimate monitor can successfully eavesdrop the suspicious information only when its achievable data rate is no smaller than that of the suspicious receiver. To maximize the eavesdropping non-outage probability, optimal joint design of the jamming power, receive and transmit beamformers at the legitimate monitor is presented. Moreover, two low-complexity suboptimal beamforming schemes are proposed and the corresponding analytical results are obtained. Our outcomes demonstrate that by exploiting multiple antennas at the legitimate monitor, the eavesdropping non-outage probability exhibits a significant improvement compared to the single antenna case. In addition, the proposed suboptimal transmit zero-forcing scheme yields similar performance as the optimal scheme.