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IEEE Transactions on Wireless Communications

Proactive Eavesdropping With Full-Duplex Relay and Cooperative Jamming

Jihwan Moon, Hoon Lee, Changick Song, Sunho Lee, Inkyu Lee

Published Aug 13, 2018• 59 citations
Publisher

Abstract

In this paper, we consider a proactive eavesdropping scenario, where a central monitor tries to intercept the information exchanged between a pair of suspicious entities through amplify-and-forward full-duplex relays and a cooperative jammer. Specifically, the eavesdropping relays simultaneously listen to the suspicious transmitter and forward the eavesdropped information to the central monitor. At the same time, the jammer broadcasts jamming signals to maintain the data rate of the suspicious users below the channel capacity of the central monitor so that the eavesdropped information can be successfully decoded by the central monitor. In this system, we jointly design the receive combining vector at the central monitor, the relay precoders at the eavesdropping relays and the transmit covariance matrix at the jammer to maximize the eavesdropping rate. First, we examine the case of a single eavesdropping relay equipped with a single antenna and provide some useful insights. Also, an effective two-layer optimization method is proposed to obtain the globally optimal solution. Then, we study a general case of multiple eavesdropping relays with multiple antennas, and solve a semi-definite relaxation problem. Numerical results verify the efficiency of our proposed solutions for both single and multiple relay cases and show considerable performance gains over conventional schemes.

DOI
10.1109/twc.2018.2863287

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In this paper, we consider a proactive eavesdropping scenario, where a central monitor tries to intercept the information exchanged between a pair of suspicious entities through amplify-and-forward full-duplex relays and a cooperative jammer. Specifically, the eavesdropping relays simultaneously listen to the suspicious transmitter and forward the eavesdropped information to the central monitor. At the same time, the jammer broadcasts jamming signals to maintain the data rate of the suspicious users below the channel capacity of the central monitor so that the eavesdropped information can be successfully decoded by the central monitor. In this system, we jointly design the receive combining vector at the central monitor, the relay precoders at the eavesdropping relays and the transmit covariance matrix at the jammer to maximize the eavesdropping rate. First, we examine the case of a single eavesdropping relay equipped with a single antenna and provide some useful insights. Also, an effective two-layer optimization method is proposed to obtain the globally optimal solution. Then, we study a general case of multiple eavesdropping relays with multiple antennas, and solve a semi-definite relaxation problem. Numerical results verify the efficiency of our proposed solutions for both single and multiple relay cases and show considerable performance gains over conventional schemes.
In this paper, we consider a legitimate proactive eavesdropping scenario where a central monitor tries to intercept the information exchanged between a pair of suspicious entities through amplify-and-forward full- duplex relays and a cooperative jammer. Specifically, the eavesdropping relays simultaneously listen to the suspicious transmitter and forward the eavesdropped information to the central monitor. At the same time, the jammer broadcasts the jamming signal to maintain the suspicious data rate below the channel capacity of the central monitor so that the eavesdropped information can be successfully decoded by the central monitor. In this system, we jointly design the relay precoders at the eavesdropping relays and the transmit covariance matrix at the jammer to maximize the eavesdropping rate by a two-layer semi-definite relaxation approach. Simulation results verify the efficiency of our proposed solution and show considerable performance gains over conventional schemes.
In this paper, we consider a legitimate proactive eavesdropping scenario where a distant central monitor covertly wiretaps the communication between a pair of suspicious users via several multi-antenna full-duplex spoofing relays and a multi-antenna cooperative jammer. Assuming an adaptive transmission policy at the suspicious users, the spoofing relays not only intercept but also forward the manipulated information to control the data rate of the suspicious users in collaboration with the jammer. We provide a technique which jointly optimizes the receive combining vector at the central monitor, the precoders at the relays, and the transmit covariance matrix at the jammer for maximizing the eavesdropping rate. To reveal some fundamental properties of the optimal operation, we first study a single-relay system. It is shown that when the central monitor experiences a poor eavesdropping channel link, the spoofing relay and the jammer should transmit destructive signals and jamming signals, respectively. In this case, the suspicious users are forced to decrease their data rate, while the intercepted information can be successfully decoded by the central monitor. On the other hand, when the eavesdropping channel condition is favorable, the spoofing relay forwards constructive signals to further increase the data rate at the suspicious users in a way that more information can be intercepted from the suspicious users. We then formulate a general eavesdropping rate maximization problem for multiple relays and present a semi-definite relaxation approach. A low-complexity design is also proposed based on our analysis for the single-relay system. Simulation results verify the efficiency of the proposed solutions compared to other baseline schemes in various practical setups.
This paper studies a legitimate proactive eavesdropping scenario where a central monitor covertly wiretaps the communications between suspicious users through a full-duplex multi-antenna relay. Specifically, the suspicious information is intercepted by the eavesdropping relay, and then encoded and forwarded to the central monitor. At the same time, the relay sends jamming signals to the suspect destination to reduce the quality of suspicious communication. To minimize the suspicious secrecy rate, the optimal forwarding and jamming beamforming vectors of the eavesdropping relay are first designed. Based on this optimized result, the best power allocation ratio is obtained. To this end, the optimal beamforming vectors and power allocation ratio are derived in closed-form. The simulation results verify the existence of the optimal forwarding power of the relay and show that the proposed scheme achieves better performance than the conventional schemes.
This article considers a proactive eavesdropping scenario, where two suspicious nodes exchange their information via one suspicious relay in two phases, the process of which is under the supervision of one legitimate monitor. Specifically, these two suspicious nodes broadcast their suspicious data in phase 1 and the relay forwards the amplified version of its received signal in phase 2, according to which two proactive eavesdropping strategies, i.e., “passive eavesdropping first” and “jamming first,” are designed. Using the former strategy, the monitor proceeds eavesdropping with a minimum-mean-squar-error (MMSE) receiver in phase 1 and implements eavesdropping or simultaneous assisting and jamming in phase 2. Using the latter strategy, the monitor implements jamming in phase 1 and performs eavesdropping in phase 2. For these strategies, we provide the detailed analysis and formulate the corresponding optimization problems of sum eavesdropping rate maximization subject to finite transmit power of the monitor, each of which is then solved by carefully designing the power allocation scheme or the assisting/jamming beamformer at the legitimate monitor. In addition, for the “passive eavesdropping first” strategy, we also consider a more advanced MMSE with a successive interference cancellation (SIC) receiver and concurrently exploit the time-sharing (TS) technique to further improve the eavesdropping rate. Finally, simulation results indicate that the “passive eavesdropping first” strategy is more preferable compared to the “jamming first” strategy, and the SIC and TS are preferable for promoting the more effective eavesdropping.
In this paper, we study a legitimate proactive eavesdropping scenario where a central monitor covertly wiretaps the communications between a pair of suspicious users via multiple intermediate nodes. For this system, it is necessary to ensure the eavesdropping channel capacity higher than the data rate of the suspicious users so that the central monitor can reliably decode the intercepted information. To this end, the intermediate nodes operate in either eavesdropping or jamming modes. The eavesdropping nodes forward the intercepted data from the suspicious users to the central monitor, while the jamming nodes transmit jamming signals to control the data rate of the suspicious users if necessary. We optimize the mode selection and transmit power of each intermediate node to achieve the maximum eavesdropping rate. Two different scenarios are investigated, in which the intermediate nodes communicate with the central monitor through wired links or wireless channels. For both configurations, globally optimal solutions are developed for joint mode selection and transmit power optimization problems. We also propose low-complexity methods which achieve near-optimal performance with reduced computational complexity. The numerical results validate the efficiency of our proposed algorithms.
Wireless information surveillance, by which suspicious wireless communications are closely monitored by legitimate agencies, is an integral part of national security. To enhance the information surveillance capability, we propose in this paper a new proactive eavesdropping approach via a spoofing relay, where the legitimate monitor operates in a full-duplex manner with simultaneous eavesdropping and spoofing relaying to vary the source transmission rate in favor of the eavesdropping performance. To this end, a power splitting receiver is proposed, where the signal received at each antenna of the legitimate monitor is split into two parts for information eavesdropping and spoofing relaying, respectively. We formulate an optimization problem to maximize the achievable eavesdropping rate by jointly optimizing the power splitting ratios and relay precoding matrix at the multiantenna monitor. Depending on the suspicious and eavesdropping channel conditions, the optimal solution corresponds to three possible spoofing relay strategies, namely constructive relaying, jamming, and simultaneous jamming and destructive relaying. Numerical results show that the proposed technique significantly improves the eavesdropping rate of the legitimate monitor as compared to the existing passive eavesdropping and jamming-assisted eavesdropping schemes.