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IEEE Transactions on Communications

UAV-Relayed Covert Communication Towards a Flying Warden

Xinying Chen, Min Sheng, Nan Zhao, Wei Xu, Dusit Tao Niyato

Published Aug 20, 2021• 121 citations
Publisher

Abstract

Owing to the ever increasing of information privacy requirement, covert communication has gained more and more attention, whose effective range is limited by the trade-off between the covertness and the transmit power. Benefiting from the high mobility and easy deployment, unmanned aerial vehicles (UAVs) can be utilized to expand the range of covert networks. Thus, we propose a UAV-relayed covert communication scheme with finite blocklength to maximize the effective transmission bits from the transmitter to the legitimate receiver against a flying warden. The transmitter adopts the maximum ratio transmission and the relay performs Gaussian signalling transmission to cause uncertainty at the warden. First, the optimal detection thresholds are derived at the warden towards the transmitter and the relay, respectively. Then, the hovering location of the warden is optimized to maximize the summation of relative entropies from the transmitter and the relay, which can greatly threaten the covertness. With this worst covert situation, the blocklength and transmit power at the transmitter and the relay are jointly optimized under the constraint of the end-to-end error detection probability to maximize the effective transmission rate from the transmitter to the legitimate receiver. Numerical results are provided to demonstrate the effectiveness of the proposed UAV-relayed covert communication scheme.

DOI
10.1109/tcomm.2021.3106354

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Owing to the ever increasing of information privacy requirement, covert communication has gained more and more attention, whose effective range is limited by the trade-off between the covertness and the transmit power. Benefiting from the high mobility and easy deployment, unmanned aerial vehicles (UAVs) can be utilized to expand the range of covert networks. Thus, we propose a UAV-relayed covert communication scheme with finite blocklength to maximize the effective transmission bits from the transmitter to the legitimate receiver against a flying warden. The transmitter adopts the maximum ratio transmission and the relay performs Gaussian signalling transmission to cause uncertainty at the warden. First, the optimal detection thresholds are derived at the warden towards the transmitter and the relay, respectively. Then, the hovering location of the warden is optimized to maximize the summation of relative entropies from the transmitter and the relay, which can greatly threaten the covertness. With this worst covert situation, the blocklength and transmit power at the transmitter and the relay are jointly optimized under the constraint of the end-to-end error detection probability to maximize the effective transmission rate from the transmitter to the legitimate receiver. Numerical results are provided to demonstrate the effectiveness of the proposed UAV-relayed covert communication scheme.
We propose a UAV-relayed covert communication scheme with finite blocklength to maximize the effective transmission rate from the transmitter to the legitimate receiver against a flying warden. The transmitter adopts the maximum ratio transmission and the relay performs Gaussian signaling transmission to cause uncertainty at the warden. First, the optimal detection thresholds are derived at the warden towards the transmitter and the relay, respectively. Then, the hovering location of the warden is optimized to maximize the summation of relative entropies from the transmitter and the relay, which can greatly threaten the covertness. With this worst covert situation, the blocklength and transmit power at the transmitter and the relay are jointly optimized under the constraint of the error detection probability to maximize the effective transmission rate from the transmitter to the legitimate receiver. Numerical results are provided to demonstrate the effectiveness of the proposed UAV-relayed covert communication scheme.
This paper studies the covert and secure communications in a UAV-aided untrust relay system composed of an unmanned aerial vehicle (UAV), a base station (BS), a user and a warden (Willie). The UAV collects data from underground users, and then uploads it to the BS. The BS forwards it to the remote user. The UAV attempts to perform covert communication with the BS in the presence of Willie, while the untrust BS serving as a relay also intercepts the message from the UAV. To ensure the covert and secure communications, we first derive the average minimum detection error rate (DEP) at Willie’s location using the noise uncertainty model. We then formulate the average covert transmission rate maximization as an optimization problem with the constraints of covertness and security requirements. We further solve the optimization problem using a search method. Numerical results are provided to validate our theoretical analysis and also to illustrate the impact of power allocation factors on the covert and secure rate. Finally, we achieve maximization of the covert transmission rate in different scenarios.
Covert communications can hide confidential signals in environmental noise to avoid being detected and provide comprehensive security for wireless transmissions. However, there still exist significant risks in wireless transmission once being detected. In this letter, we propose a more secure covert scheme, where a multiple antennas transmitter, assisted by a multi-antenna UAV jammer, maximizes the covert secrecy rate under the scenarios of both correct and incorrect detection by a warden with both error detection probability and eavesdropping rate limitations satisfied. The transmitter and jammer adopt maximum ratio transmission (MRT) and zero-forcing, respectively, to maximize the transmission rate and minimize the interference at the legitimate receiver. First, we analyze the monotonicity of error detection probability to determine the optimal power detection threshold and the corresponding smallest error detection probability. Then, under this worst case, we jointly optimize the transmit and jamming power to maximize the covert secrecy rate while guaranteeing the covert and eavesdropping limits meet their requirements, respectively. Finally, simulation results are presented to prove the correctness of the theoretical conclusion and evaluate the effectiveness of our proposed scheme.
To address the inherent openness of wireless communication environments, covert communication has emerged as a promising approach to protect legitimate transmissions from unauthorized detection. This paper investigates a UAVassisted wireless covert communication system, where channel uncertainty is exploited to enable covert information transmission in the presence of active wardens acting simultaneously as jamming sources. We first model the indirect communication strategy between legitimate parties and characterize the detection behavior of an active warden. To achieve both covertness and communication efficiency, the transmit power of the devices and the hovering positions of UAVs are jointly optimized, subject to the dual constraints of maintaining a sufficient covert communication rate and ensuring a high detection error probability at the warden. Closed-form expressions for the wardens detection error probability and the achievable covert communication rate are derived. Furthermore, numerical optimization is employed to maximize the achievable rate under covertness constraints. Simulation results corroborate the theoretical analysis and demonstrate the effectiveness of the proposed scheme in enabling covert communication in jamming-assisted active warden scenarios.
Wireless systems are of paramount importance in enabling ubiquitous data transmission for various Internet of Things (IoT) applications. However, due to the broadcast nature and openness of wireless channels, such systems face inherent security challenges. Covert communication is an enabling technology for secure wireless communications while the Unmanned Aerial Vehicle (UAV)-assisted covert communication is particularly promising for enhancing covert performance. This paper investigates joint covert and secure communications in a two-hop UAV-assisted wireless system, where a source S transmits a covert message to a destination D with the help of an untrusted UAV, while being subject to detection by a warden W. We first design a covert transmission scheme for the proposed system with the considerations of both covert and secure constraints. We then develop theoretical models for the warden1detection error probability and the covert-and-secure rate (CSR) from S to D. Based on these models, we further explore the optimal power control for CSR maximization under both covertness and security constraints. Finally, numerical results are presented to validate the theoretical models and demonstrate the performance of covert and secure communications in the UAV-assisted system.
Covert communication can hide confidential signals in environmental noise to avoid being detected and provide comprehensive security for wireless transmission. However, there still exists significant risks in the wireless transmission once being detected. In this paper, we propose a more secure covert scheme, where a multiple antennas transmitter assisted by a multi-antenna UAV jammer maximizes the covert secrecy rate under the scenarios of both correct and incorrect detection by a warden with both error detection probability and eavesdropping rate limitations satisfied. The transmitter and jammer adopt maximum ratio transmission (MRT) and zero-forcing to maximize the transmission rate and minimize the interference at the receiver, respectively. First, we analyze the monotonicity of error detection probability to determine the optimal power detection threshold and the corresponding largest error detection probability. Then, under this worst case, we jointly optimize the transmit and jamming power to maximize the covert secrecy rate while guaranteeing the covert and eavesdropping limits meet their respective requirements. Finally, simulation results are presented to prove the correctness of the theoretical conclusion and evaluate the effectiveness of our proposed scheme.