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.
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.
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 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 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.
A wireless legitimate surveillance system is studied for a proactive eavesdropping scheme, where a full- duplex legitimate monitor eavesdrops a suspicious link by injecting artificial noise (AN) towards the suspicious receiver. 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, it stops transmission. Hence, to improve the surveillance performance, AN should be transmitted covertly with low detection probability by the suspicious receiver. To achieve this goal, an optimal problem is first formulated to maximize the eavesdropping rate under covert constraint. Then, according to the derived detection error probability, the optimal detection threshold is determined under Rayleigh fading channels. A novel scheme is proposed to solve the optimization problem under both perfect and imperfect channel state informations (CSIs). Finally, simulation is performed to verify the analyses. It is shown that the imperfect CSI of the suspicious link can benefit the surveillance performance.
This paper considers wireless information surveillance systems, in which one suspicious communication link is intercepted by a legitimate monitor to prevent possible criminal or terrorist attacks from the link. To enhance the information surveillance performance, a novel proactive eavesdropping mechanism is proposed with the help of a cooperative relay. It is assumed that the relay operates in full-duplex (FD) mode to assist monitor for information relaying and jamming transmission simultaneously. Based on the proposed mechanism, the joint relay beamforming and power allocation scheme is further proposed and the closed form optimal solutions are derived. Simulation results show that the proposed proactive eavesdropping mechanism can achieve better surveillance performance than both proactive eavesdropping schemes without the help of cooperative relay and cooperative surveillance with pure information forwarding. Simulation results also reveal that the proposed power allocation scheme boosts surveillance performance significantly compared with those equal power allocation scheme.
Recently, non-orthogonal multiple access (NOMA) has been considered as a promising technique in 5G network, and many investigations have addressed on the physical layer security to improve the security performance. In this paper, an alternative problem, where the eavesdropping process is considered as a legal activity, will be analyzed to track suspicious communications. More specifically, we study a wireless surveillance system in which the legitimate monitor is equipped with multi-antenna to overhear the messages between the suspicious receiver and the suspicious transmitter. Suspicious users are grouped into pairs and use the NOMA technique to transmit signals to a suspicious base station. Meanwhile, the legitimate monitor (LM) simultaneously transmits jamming signals, listens to suspicious links, decode-and-forward (DF) the eavesdropped information to the legitimate eavesdropper (LE). Based on the proposed mechanism, we investigate the power allocation policies for jamming signals of the legitimate monitor under deterministic and non-deterministic interference channel. Accordingly, we derive the closed-form expression of the successful eavesdropping probability for the best and the worst user to evaluate the system performance. Monte Carlo simulations are provided to verify our analytical results.