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.
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.
In this paper, we study a novel approach to eavesdrop the messages of suspicious users for a surveillance purpose. In particular, we consider a scenario in which the legitimate monitor can act as a jamming source and a decode-and-forward relay station that can force the suspicious users to reveal their exchanged messages. Accordingly, the power allocation policies for the jamming signal of the legitimate monitor subject to deterministic and non-deterministic interference channels are considered. On this basis, we derive a closed-form expression for the successful eavesdropping probability to evaluate the system performance. More importantly, our results reveal that the successful eavesdropping probability of the non-deterministic interference channel from the legitimate monitor to the suspicious receiver outperforms the one of the deterministic interference channel.
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.
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.
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.
This paper studies the performance of multi-antenna proactive eavesdropping in 5G uplink systems with spatially correlated Rayleigh fadings, where the base station (BS) serves an illegal user and a multi-antenna legitimate monitor eavesdrops the suspicious link with the help of jamming attack. Based on a practical assumption of channel state information (CSI) in 5G uplink, i.e., imperfect instantaneous CSI of the suspicious link at the BS and that of eavesdropping link at the monitor, and only jamming channel statistics at the monitor, we first give a statistical jamming beamforming design. Then, semi-closed form expressions of eavesdropping non-outage probability and relative average eavesdropping rate are, respectively, derived for delay-sensitive and delay-tolerant scenarios. Via reasonable approximations and asymptotic analysis, we gain many insights on the effect of key system parameters, e.g., location-dependent channel path loss and angular spread, jamming energy and the number of antennas. Further, we provide the optimal energy allocation between pilot and data jamming and the optimal antenna allocation between jamming and eavesdropping under total energy constraint and total antenna number, respectively, which are both explicit functions of system parameters. Finally, simulation results validate our analytical results.
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.