The issue of physical layer security of the wireless single-input multiple-output (SIMO) system is addressed in this paper. We proposed a two-step transmission approach to improve the secrecy rate with perfect knowledge of channel state information. In the first step, the destination which has multiple antennas generates a random message and transmits it to the source which has a single antenna. The message is transmitted in a system of multiple-input single-output (MISO) in this step, and it is encoded under the secrecy capacity of the MISO system and thus can be securely transmitted to the source without leaking to the eavesdropper. In the second step, the message of the source is encrypted to a new message by using the received random message in the first step. The new message is then transmitted to the destination under the capacity of the SIMO system without considering the security. The secrecy of the source's message is guaranteed by the first random message, thus it is unknown for the eavesdropper. The information-theoretic security of the two-step transmission approach is proven in this paper, and the optimal power allocation is also proposed by solving an equation. The performance of the two-step transmission approach is analyzed in theory and evaluated by numerical simulations, and the results show that the proposed approach outperforms the traditional approach when the transmit power is great.
The issue of physical layer security of the wireless single-input multiple-output (SIMO) system is addressed in this paper. We proposed a two-step transmission approach to improve the secrecy rate with perfect knowledge of channel state information. In the first step, the destination which has multiple antennas generates a random message and transmits it to the source which has a single antenna. The message is transmitted in a system of multiple-input single-output (MISO) in this step, and it is encoded under the secrecy capacity of the MISO system and thus can be securely transmitted to the source without leaking to the eavesdropper. In the second step, the message of the source is encrypted to a new message by using the received random message in the first step. The new message is then transmitted to the destination under the capacity of the SIMO system without considering the security. The secrecy of the source's message is guaranteed by the first random message, thus it is unknown for the eavesdropper. The information-theoretic security of the two-step transmission approach is proven in this paper, and the optimal power allocation is also proposed by solving an equation. The performance of the two-step transmission approach is analyzed in theory and evaluated by numerical simulations, and the results show that the proposed approach outperforms the traditional approach when the transmit power is great.
In this paper, we investigate the secure transmission in the single-input multiple-output (SIMO) wireless systems. Motivated by the existing destination-feedback schemes, and the utilization of artificial noise, a novel destination-feedback based two-phase transmission strategy is proposed to secure the SIMO communications. In the first phase, the multiple-antenna destination transmits both artificial interference and artificial noise on the backhaul links. In the second phase, the source utilizes the received interference signals to mask the confidential messages and emits the mixed signals to the destination. In the high signal-to-noise ratio (SNR) region, the lower bound of the worst-case ergodic secrecy rate is derived. Then we obtain the closed-form optimal power allocations that maximize the above lower bound. Moreover, we derive an analytical high-SNR approximation of the worst-case secrecy outage probability. Simulations are demonstrated to verify the secrecy performance analysis and corroborate the effectiveness of our scheme.
The issue of physical layer security for wireless communication with uncoordinated cooperative jamming (UCJ) is addressed in this paper, and we focus on the secrecy rate maximization (SRM) for single-input multiple-output (SIMO) wiretap channel with a multi-antenna intended receiver and a single-antenna eavesdropper. Differing from the existing schemes, we propose a new scheme for SRM by using multiple single-antenna helpers, where each helper transmits artificial noise independently to confound the eavesdropper. Our purpose is to design the jamming power of the helpers under individual or sum power constraints to maximize the secrecy rate with the assumption that global channel state information (CSI) is available. A robust iterative optimization method for power allocation is given to solve the SRM problem, and numerical results are finally provided to illustrate the performance of the proposed method in comparison with the existing works.
Physical layer security is a promising technique for information security. In multi-antenna systems, secure transmission designs are of crucial importance for physical layer security. In this thesis, our research focuses on the secure transmission designs for jamming signal aided multi-antenna systems. We first investigate robust secure transmission designs for a cooperative jamming aided multiple-input-single-output (MISO) system. Two scenarios are considered: (a) eavesdroppers' channel state information (ECSI) is available and (b) ECSI is unavailable. In scenario (a), a quality-of-service (QoS)-based design is considered to minimize the worst case signal-to-interference-and-noise ratio at the eavesdroppers. A secrecy rate based design is also studied. In scenario (b), a QoS-based design is considered to maximize the power of jamming signals, and the secrecy rate based design is not applicable. We propose an algorithm for each design problem through semidefinite relaxation. Our analysis shows that, even though the beamforming scheme in our designs is fixed as single stream beamforming, this does not cause any loss of optimality. We further consider secure transmission designs for a simultaneous wireless information and power transfer enabled MISO heterogeneous cellular network. In the considered system, all base stations (BSs) send confidential messages to information receivers and energy signals to energy receivers (ERs). BSs collaboratively utilize the energy signals as jamming signals to cripple ERs' interceptions. We propose a sum logarithmic secrecy rate maximization design problem. To tackle the design problem, we propose a semidefinite relaxation and successive convex approximation based centralized secure transmission design algorithm. Moreover, an alternating direction method of multipliers based distributed secure transmission design is also proposed. Simulation results demonstrate the effectiveness of the proposed algorithms. Secure transmission is designed for a cooperative jamming aided MISO non-orthogonal multiple access system. We consider an outage constrained secure transmission design problem under the assumption that only statistical ECSI is available. In the design problem, the minimum probabilistic secrecy rate is maximized. Based on 0-norm and the path-following approach, we develop an algorithm to find a solution to the design problem. Simulation results demonstrate that the secrecy outage probability can be guaranteed through the proposed secure transmission design algorithm.
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.
Cooperative jamming is a widely used approach for improving the security of wireless networks. In this approach, a friendly jammer sends jamming signals to disrupt the reception of the eavesdropper, which inevitably interferes with the legitimate receiver. In this paper, we propose a novel approach, namely, information jamming, to exceed the secrecy rate achieved by the traditional cooperative jamming approach in a multiple-input single-output (MISO) wiretap channel. We propose that multiple multi-antenna information jammers (iJammers) transmit the source signals of the legitimate transmitter rather than independent noise signals for simultaneously enhancing the signal strength at the legitimate receiver and canceling the received signal at the eavesdropper. Specifically, we aim at maximizing the achievable secrecy rate by jointly optimizing the beamforming vectors at Alice and iJammers, subject to the individual transmit power constraints. We first propose a semi-definite relaxation based approach to solve the original non-convex problem optimally. For ease of implementation, we then provide a suboptimal distributed information beamforming scheme, whose optimal solution is obtained in closed-form. Finally, we extend our study to the imperfect channel state information case. Simulation results show that our proposed information jamming approach significantly outperforms the traditional cooperative jamming approach in terms of achievable secrecy rate.
This paper investigates the secrecy rate maximization problem for the multiple-input-single-output multiple-antenna-eavesdropper (MISOME) wiretap channel with multiple randomly located jammers. The multi-antenna base station (BS) transmits information signals along with artificial noise (AN) to disturb the eavesdropper. Moreover, the friendly jammers are properly selected to assist the legitimate link for better secure transmission with some payoffs. With this system model, we first formulate a Stackelberg game between the BS and the assisting jammers with full channel state information. Stackelberg equilibriums, including optimal fraction of transmit power for AN, optimal transmit power, and asking prices of assisting jammers, are first proved to exist and then analytically derived. A policy iterative algorithm is also proposed to obtain the optimal solutions. We then extend the Stackelberg game to the case of MISOME broadcast wiretap channel with channel distribution information of eavesdropper. Numerical results verify the accuracy of the derived results and the efficiency of the proposed algorithm. The results reveal that the proposed jammer-assisted secure transmission can greatly improve the secrecy performance and meanwhile save more energy for information signals, which is significant for future wireless communication.