46 research outputs found
Covert Communication in UAV-Assisted Air-Ground Networks
Unmanned aerial vehicle (UAV) assisted communication is a promising technique for future wireless networks due to its characteristics of low cost and flexible deployment. However, the high possibility of line-of-sight (LoS) air-ground channels may result in a great risk of being attacked by malicious users. Especially compared to the encryption and physical layer security that prevent eavesdropping, covert communication aims at hiding the existence of transmission, which is able to satisfy the more critical requirement of security. Thus, in this article, we focus on the covert communication issues of UAV-assisted wireless networks. First, the preliminaries of secure communications including encryption, physical layer security and covert communication are discussed. Then, current works and typical applications of UAV in covert communications are demonstrated. We then propose two schemes to enhance the covertness of UAV-assisted networks for some typical scenarios. Specifically, to improve the covert rate in UAV-assisted data dissemination, an iterative algorithm is proposed to jointly optimize the time slot, transmit power and trajectory. For the covertness of ground-air communication, a friendly jammer is employed to confuse the wardens, where the location of the jammer, the jamming power and the legitimate transmit power are jointly optimized. Numerical results are presented to validate the performance of these two proposed schemes. Finally, several challenges and promising directions are pointed out
Blockchain-Based Security Architecture for Unmanned Aerial Vehicles in B5G/6G Services and Beyond: A Comprehensive Approach
Unmanned Aerial Vehicles (UAVs), previously favored by enthusiasts, have
evolved into indispensable tools for effectively managing disasters and
responding to emergencies. For example, one of their most critical applications
is to provide seamless wireless communication services in remote rural areas.
Thus, it is substantial to identify and consider the different security
challenges in the research and development associated with advanced UAV-based
B5G/6G architectures. Following this requirement, the present study thoroughly
examines the security considerations about UAVs in relation to the
architectural framework of the 5G/6G system, the technologies that facilitate
its operation, and the concerns surrounding privacy. It exhibits security
integration at all the protocol stack layers and analyzes the existing
mechanisms to secure UAV-based B5G/6G communications and its energy and power
optimization factors. Last, this article also summarizes modern technological
trends for establishing security and protecting UAV-based systems, along with
the open challenges and strategies for future research work.Comment: 25 pages, 6 figures, 3 table
Graph Koopman Autoencoder for Predictive Covert Communication Against UAV Surveillance
Low Probability of Detection (LPD) communication aims to obscure the very
presence of radio frequency (RF) signals, going beyond just hiding the content
of the communication. However, the use of Unmanned Aerial Vehicles (UAVs)
introduces a challenge, as UAVs can detect RF signals from the ground by
hovering over specific areas of interest. With the growing utilization of UAVs
in modern surveillance, there is a crucial need for a thorough understanding of
their unknown nonlinear dynamic trajectories to effectively implement LPD
communication. Unfortunately, this critical information is often not readily
available, posing a significant hurdle in LPD communication. To address this
issue, we consider a case-study for enabling terrestrial LPD communication in
the presence of multiple UAVs that are engaged in surveillance. We introduce a
novel framework that combines graph neural networks (GNN) with Koopman theory
to predict the trajectories of multiple fixed-wing UAVs over an extended
prediction horizon. Using the predicted UAV locations, we enable LPD
communication in a terrestrial ad-hoc network by controlling nodes' transmit
powers to keep the received power at UAVs' predicted locations minimized. Our
extensive simulations validate the efficacy of the proposed framework in
accurately predicting the trajectories of multiple UAVs, thereby effectively
establishing LPD communication
Decentralized Covert Routing in Heterogeneous Networks Using Reinforcement Learning
This letter investigates covert routing communications in a heterogeneous
network where a source transmits confidential data to a destination with the
aid of relaying nodes where each transmitter judiciously chooses one modality
among multiple communication modalities. We develop a novel reinforcement
learning-based covert routing algorithm that finds a route from the source to
the destination where each node identifies its next hop and modality only based
on the local feedback information received from its neighboring nodes. We show
based on numerical simulations that the proposed covert routing strategy has
only negligible performance loss compared to the optimal centralized routing
scheme
Resource allocation and trajectory optimization for UAV-enabled multi-user covert communications
In this correspondence, covert air-to-ground communication is investigated to hide the wireless transmission from unmanned aerial vehicle (UAV). The warden's total detection error probability with limited observations is first analyzed. Considering the location uncertainty of the warden, a robust resource allocation and UAV trajectory optimization problem with worst-case covertness constraint is then formulated to maximize the average covert rate. To solve this optimization problem, we propose a block coordinate descent method based iterative algorithm to optimize the time slot allocation, power allocation and trajectory alternately. Numerical results demonstrate the effectiveness of the proposed algorithm in covert communication for UAVs
Covert communication in relay and RIS networks
Covert communication aims to prevent the warden from detecting the presence of communications, i.e. with a negligible detection probability. When the distance between the transmitter and the legitimate receiver is large, large transmission power is needed, which in turn increases the detection probability. Relay is an effective technique to tackle this problem, and various relaying strategies have been proposed for long-distance covert communication in these years. In this article, we first offer a tutorial on the relaying strategies utilized in covert transmission. With the emergence of reflecting intelligent surface and its application in covert communications, we propose a hybrid relay-reflecting intelligent surface (HR-RIS)-assisted strategy to further enhance the performance of covert communications, which simultaneously improves the signal strength received at the legitimate receiver and degrades that at the warden relying on optimizing both the phase and the amplitude of the HR-RIS elements. The numerical results show that the proposed HR-RIS-assisted strategy significantly outperforms the conventional RIS-aided strategy in terms of covert rate
Sensing Aided Covert Communications: Turning Interference into Allies
In this paper, we investigate the realization of covert communication in a
general radar-communication cooperation system, which includes integrated
sensing and communications as a special example. We explore the possibility of
utilizing the sensing ability of radar to track and jam the aerial adversary
target attempting to detect the transmission. Based on the echoes from the
target, the extended Kalman filtering technique is employed to predict its
trajectory as well as the corresponding channels. Depending on the maneuvering
altitude of adversary target, two channel models are considered, with the aim
of maximizing the covert transmission rate by jointly designing the radar
waveform and communication transmit beamforming vector based on the constructed
channels. For the free-space propagation model, by decoupling the joint design,
we propose an efficient algorithm to guarantee that the target cannot detect
the transmission. For the Rician fading model, since the multi-path components
cannot be estimated, a robust joint transmission scheme is proposed based on
the property of the Kullback-Leibler divergence. The convergence behaviour,
tracking MSE, false alarm and missed detection probabilities, and covert
transmission rate are evaluated. Simulation results show that the proposed
algorithms achieve accurate tracking. For both channel models, the proposed
sensing-assisted covert transmission design is able to guarantee the
covertness, and significantly outperforms the conventional schemes.Comment: 13 pages, 12 figures, submitted to IEEE journals for potential
publicatio