This paper investigates UAV secure communication against multiple UAV active eavesdroppers (Eves). The active eavesdropper (Eve)can act adaptively as passive Eve or active jammer based on transmitting source power. In order to safeguard system security, we formulate the secure communication problem as a non-cooperative Stackelberg game and derive the equilibrium. Then Q-Learning algorithm is used to devise a Stackelberg equilibrium strategy in order to maximize the utility of the transmitter and optimize the secrecy rate. Simulation results indicate that the proposed scheme can enhance the security of the UAV communication in the presence of multiple UAV active Eves. Moreover, the impact of the distance between UAV Eves and legitimate transmitter-receiver on the secrecy rate and attack mode probabilities of Eves are also revealed.
This paper investigates UAV secure communication against multiple UAV active eavesdroppers (Eves). The active eavesdropper (Eve)can act adaptively as passive Eve or active jammer based on transmitting source power. In order to safeguard system security, we formulate the secure communication problem as a non-cooperative Stackelberg game and derive the equilibrium. Then Q-Learning algorithm is used to devise a Stackelberg equilibrium strategy in order to maximize the utility of the transmitter and optimize the secrecy rate. Simulation results indicate that the proposed scheme can enhance the security of the UAV communication in the presence of multiple UAV active Eves. Moreover, the impact of the distance between UAV Eves and legitimate transmitter-receiver on the secrecy rate and attack mode probabilities of Eves are also revealed.
In this paper, we investigate the secrecy performance of cooperative wireless communication networks, where a source (Alice) intends to transmit information to a legitimate user (Bob) with an unmanned aerial vehicle (UAV) enabled friendly jammer in the presence of a passive eavesdropper (Eve). In order to maximize the secrecy rate of the system under a certain secrecy outage probability, we design a scheme utilizing artificial-noise (AN) beamforming and cooperative jamming to determine the optimal power allocation factor with only location and statistical channel state information of the Eve. Numerical results validate that the proposed scheme can significantly improve the secrecy rate and secure energy efficiency (EE) performance.
In this paper, we study how to defend against full-duplex active eavesdropping attacks in the cooperative communication system. Unlike passive eavesdropping attackers, a full-duplex active eavesdropper acts as both a jammer and a classical eavesdropper in full-duplex mode, and seeks to maximize eavesdropping. Furthermore, in a real-world network, the relays may be selfish and have their own objectives due to competing/limited resources. This may lead to the failure of cooperative communication if there is no incentive to stimulate relays to participate in forwarding the transmitter's messages. Therefore, in this paper, we propose a three-stage Stackelberg game approach to model the behaviors of attacker, and the competitions among the transmitter, relays and attacker. Through finding the Stackelberg equilibrium of our scheme, the legitimate users can achieve cooperative communication to improve the secrecy capacity and to defend against full-duplex active eavesdropping attacks. Findings from the evaluations demonstrate that with an increasing number of channels, our scheme can significantly reduce the intercept probability; therefore, the security performance is improved. It is shown that our scheme can greatly improve the utilities of both the transmitter and multiple relays over the results of the Nash equilibrium scheme and rand power control scheme, which means that the relays are more willing to participate in the cooperative communication, and the transmitter can achieve better secure transmission in our scheme. We also demonstrate that our scheme outperforms other existing schemes, i.e., power control with smart jamming game in a single-channel model/multiple-channel model.
In this paper, we study secure cooperative transmission for the multiple-input-single-output multiple-eavesdropper (MISOME) systems, where a source (Alice) aims to send confidential messages to a legitimate user (Bob) with the aid of an unmanned aerial vehicle (UAV) enabled friendly jammer (Charlie) in the presence of multiple eavesdroppers (Eves). To further guarantee the secrecy performance, artificial noise (AN) beamforming together with cooperative Jamming (CJ) has been utilized in this considered system with only location and statistical channel state information of the Eves. Specifically, taking imperfect channel state information (CSI) between Charlie and Bob into account, we derive the exact closed-form expression of the secrecy outage probability (SOP) and develop an efficient scheme to solve the secrecy rate maximization (SRM) problem which has been verified as a convex one under certain SOP. Moreover, we propose an optimal UAV placement strategy to further enhance secrecy performance. The numerical results are provided to validate that the system security would seriously degenerate with channel uncertainty. Besides, the proposed scheme is verified to outperform the terrestrial CJ scheme in improving the secrecy rate and secure energy efficiency (EE) performance under perfect CSI or tolerable channel estimation errors. Finally, the effectiveness of the proposed UAV placement strategy in enhancing transmission security and the applicability of the proposed scheme has also been demonstrated.
This paper investigates the jointly transmit power and unmanned aerial vehicle (UAV)/jammer deployment optimization problem for UAV enabled jammer-assisted secure communication systems, where a jammer is exploited to assist transmitting data from a source node to a legitimate destination node in the presence of multiple eavesdroppers. To increase the secrecy energy efficiency, which is defined as the achievable secrecy rate per energy consumption unit, we formulate a secrecy energy efficiency maximization problem by jointly optimizing the transmit power and UAV/jammer deployment. The resulting optimization problem is shown to be a non-convex and fractional optimization problem, which is challenging to solve. As such, we decompose the original problem into two sub-problems, and then, an efficient iterative algorithm is proposed by leveraging the extensive search method and Dinkelbach method in combination with successive convex approximation (SCA) techniques. Numerical simulation results show that the proposed scheme significantly improves the secrecy energy efficiency of the system.
The broadcast nature of air-to-ground line-of-sight (LoS) wireless channel imposes a great challenge in secure unmanned aerial vehicle (UAV) communications. To address this issue, this paper investigates UAV-ground communications from the physical-layer security perspective. Specifically, the investigated scenario includes a UAV serving as the base station (BS) that transmits confidential signals to a legitimate ground user, and there are multiple eavesdroppers on the ground with unknown position information. To further enhance the secrecy performance of the UAV-ground communications, an idle UAV can be employed to serve as a friendly jammer, which can transmit jamming signals to confuse the eavesdroppers. In our proposed strategy, the flying trajectory and the transmit power for both the UAVs are jointly optimized by maximizing the worst-case secrecy rate (WCSR) of the system. Considering the intractability of the formulated non-convex problem, we further provide a block coordinate descent-based iterative optimization method. Simulations verify that our proposed algorithm can significantly improve the average WCSR in comparison with the existing works.
In this paper, we examine the security issue of unmanned aerial vehicle (UAV)-aided communication systems. We consider the scenario where a source communicates with a legitimate UAV in the presence of a full-duplex eavesdropper. We assume that the full-duplex eavesdropper performs both eavesdropping and malicious jamming simultaneously. In order to safeguard data transmissions against such an eavesdropper, the source transmits artificial noise (AN) signals together with information signals. We adopt the hybrid outage probability as the performance metric, which combines the transmission outage probability and the secrecy outage probability. We derive a compact expression for the hybrid outage probability. Using the derived expression, we determine the optimal power allocation factor between information signals and AN signals that minimizes the hybrid outage probability. In addition, we examine the impact of the operating height of UAV on the secrecy performance, showing that the optimal secrecy performance can be achieved by judiciously controlling the height of UAV.