Tackling the physical layer secrecy issue, existing studies on cooperative jamming generally assume the persistent jamming and perfect channel estimation at the receiver side. However, these two assumptions are incompatible since jamming signals can corrupt the pilot symbols. In addition, due to the energy budget limitation, persistent jamming is burdensome to the cooperative jammers. To address these issues, we propose a cooperative jamming strategy that designs the jamming symbols aiming only at the pilot signals to attain security improvement by manipulating the channel estimations at the authorized receiver and the eavesdropper simultaneously. Via computer simulations, we compare the performance of the proposed strategy with that of a conventional persistent artificial noise-aided strategy, and these results demonstrate that the proposed strategy achieves substantial secrecy rate gain in wide region, especially at the low data transmission power regime and at the rank-deficient environment.
Tackling the physical layer secrecy issue, existing studies on cooperative jamming generally assume the persistent jamming and perfect channel estimation at the receiver side. However, these two assumptions are incompatible since jamming signals can corrupt the pilot symbols. In addition, due to the energy budget limitation, persistent jamming is burdensome to the cooperative jammers. To address these issues, we propose a cooperative jamming strategy that designs the jamming symbols aiming only at the pilot signals to attain security improvement by manipulating the channel estimations at the authorized receiver and the eavesdropper simultaneously. Via computer simulations, we compare the performance of the proposed strategy with that of a conventional persistent artificial noise-aided strategy, and these results demonstrate that the proposed strategy achieves substantial secrecy rate gain in wide region, especially at the low data transmission power regime and at the rank-deficient environment.
In this paper, we consider the multiple-input single-output (MISO) wiretap channel with a cooperative jammer (CJ). Motivated by the fact that corrupting pilot signals can effectively degrade the channel estimation at the eavesdropper (Eve), we emphasize that the physical-layer security can be enhanced by introducing jamming signals in pilot phase. Therefore, we propose a cooperative jamming scheme which delivers artificial noise (AN) both in pilot and data phases, unlike the conventional schemes that transmit AN only in data phase. More specifically, we optimize the jamming power allocation between pilot phase and data phase, along with designing the beamforming vector at the CJ. Furthermore, considering the limitation of energy budget at the CJ, the energy efficiency of the proposed scheme is investigated based on the circuit power consumption model. Finally, numerical results verify the performance of the proposed scheme, in terms of secrecy rate and energy efficiency.
In this paper, we tackle the physical-layer security issue in MISO wiretap channel considering the pilot-assisted channel estimation at the receiver side. Unlike the conventional schemes, we introduce the cooperative jamming scheme that transmits artificial noise (AN) only on downlink pilot transmission phase. In order to disrupt the channel estimation at the eavesdropper (Eve) effectively, an optimal beamforming at the cooperative jammer (CJ) was obtained by means of difference-of-convex (DC) algorithm and rank relaxation. In addition, with focus on the energy budget limitation issue at the CJ, energy efficiency at the CJ is verified based on the circuit power consumption model. Numerical results provide a performance comparison with a conventional scheme, which transmits AN only in data transmission phase.
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.
Cooperative jamming approach has been commonly used in the field of physical layer security to achieve a good secrecy rate of wireless networks. In this approach, the Gaussian noise signal sent by a friendly jammer can disrupt the reception of the eavesdropper, however, it may also interfere with the legitimate receiver. In this paper, we propose a novel approach, namely, information jamming, to go beyond the secrecy rate achieved by the traditional cooperative jamming approach in a multiple-input single-output (MISO) wiretap channel. We propose that a multi-antenna friendly jammer transmits the source message rather than Gaussian noise signal for simultaneously enhancing the signal strength at the legitimate receiver and canceling the received signal at the eavesdropper. In particular, we aim to maximize the achievable secrecy rate by optimizing the information jammer's beamforming vector. Though the optimization problem is non-convex, we successfully solve it optimally via a two-stage based numerical approach. To gain more useful analytical results, we also propose two suboptimal jamming schemes with low computation, by targeting at improving the legitimate reception and avoiding the eavesdropping, respectively. Finally, numerical results show that the proposed information jamming approach significantly helps go beyond the secrecy rate of the existing cooperative jamming approach, especially when the transmit power of the jammer is large enough.
This paper studies secrecy rate optimization in a wireless network with a single-antenna source, a multi-antenna destination and a multi-antenna eavesdropper. This is an unfavorable scenario for secrecy performance as the system is interference-limited. In the literature, assuming that the receiver operates in half duplex (HD) mode, the aforementioned problem has been addressed via use of cooperating nodes who act as jammers to confound the eavesdropper. This paper investigates an alternative solution, which assumes the availability of a full duplex (FD) receiver. In particular, while receiving data, the receiver transmits jamming noise to degrade the eavesdropper channel. The proposed self-protection scheme eliminates the need for external helpers and provides system robustness. For the case in which global channel state information is available, we aim to design the optimal jamming covariance matrix that maximizes the secrecy rate and mitigates loop interference associated with the FD operation. We consider both fixed and optimal linear receiver design at the destination, and show that the optimal jamming covariance matrix is rank-1, and can be found via an efficient 1-D search. For the case in which only statistical information on the eavesdropper channel is available, the optimal power allocation is studied in terms of ergodic and outage secrecy rates. Simulation results verify the analysis and demonstrate substantial performance gain over conventional HD operation at the destination.
Internet of Things (IoT) is becoming an emerging paradigm to achieve ubiquitous connectivity, via massive deployment of physical objects, such as sensors, controllers, and actuators. However, concerns on the IoT security are raised due to the wireless broadcasting nature and the energy constraint of the physical objects. In this paper, we study secure downlink transmission from a controller to an actuator, with the help of a cooperative jammer to fight against multiple passive and noncolluding eavesdroppers. In addition to artificial noise aided secrecy beamforming for secure transmission, cooperative jamming (CJ) is explored to further enhance physical layer security. In particular, we provide a secrecy enhancing transmit design to minimize the secrecy outage probability (SOP), subject to a minimum requirement on the secrecy rate. Based on a strict mathematical analysis, we further characterize the impacts of the main channel quality and the minimum secrecy rate on transmit designs. Numerical results confirm that our design can enhance both security (in terms of SOP) and power efficiency as compared with the approach without CJ.