170 research outputs found
Dynamic Role Switching Scheme with Joint Trajectory and Power Control for Multi-UAV Cooperative Secure Communication
Due to the high flexibility and mobility, unmanned aerial vehicles (UAVs) can be deployed as aerial relays touring to serve ground users (GUs), especially when the ground base station is temporally damaged. However, the broadcasting nature of wireless channels makes such communication vulnerable to be wiretapped by malicious eavesdropping users (EUs). Besides the collecting offloading data for legitimate GUs, UAVs are also expected to be friendly jammers, i.e., generating artificial noise (AN) to deteriorate the wiretapping of EUs. With this in mind, a novel role switching scheme (RSS) is proposed in the paper to guarantee the secure communication by the cooperation of multiple UAVs, where each UAV is allowed to switch its role as a collector or a jammer autonomously to explore a wider trajectory space. It’s worthy to be noticed that the joint optimization for the trajectory of UAVs and the transmission power of GUs and UAVs with role switching scheme is a non-convex mixed integer non-linear programming (MINLP) problem. Since the relaxation of binary variables will lead the solution dropping into local minimum, a deep reinforcement learning (DRL) combined successive convex approximate (SCA) algorithm is further designed to maximize the achievable secrecy rate (ASR) of GUs. Numerical results illustrate that compared with the role fixed scheme (RFS) and relaxation based SCA approaches, the proposed DRL-SCA algorithm endows UAVs the capacity to fly close enough to target users (both GUs and EUs) with less moving distance which brings better ASR and less energy consumption
Intelligent-Reflecting-Surface-Assisted UAV Communications for 6G Networks
In 6th-Generation (6G) mobile networks, Intelligent Reflective Surfaces
(IRSs) and Unmanned Aerial Vehicles (UAVs) have emerged as promising
technologies to address the coverage difficulties and resource constraints
faced by terrestrial networks. UAVs, with their mobility and low costs, offer
diverse connectivity options for mobile users and a novel deployment paradigm
for 6G networks. However, the limited battery capacity of UAVs, dynamic and
unpredictable channel environments, and communication resource constraints
result in poor performance of traditional UAV-based networks. IRSs can not only
reconstruct the wireless environment in a unique way, but also achieve wireless
network relay in a cost-effective manner. Hence, it receives significant
attention as a promising solution to solve the above challenges. In this
article, we conduct a comprehensive survey on IRS-assisted UAV communications
for 6G networks. First, primary issues, key technologies, and application
scenarios of IRS-assisted UAV communications for 6G networks are introduced.
Then, we put forward specific solutions to the issues of IRS-assisted UAV
communications. Finally, we discuss some open issues and future research
directions to guide researchers in related fields
Strategic Deployment of Swarm of UAVs for Secure IoT Networks
Security provisioning for low-complex and constrained devices in the Internet
of Things (IoT) is exacerbating the concerns for the design of future wireless
networks. To unveil the full potential of the sixth generation (6G), it is
becoming even more evident that security measurements should be considered at
all layers of the network. This work aims to contribute in this direction by
investigating the employment of unmanned aerial vehicles (UAVs) for providing
secure transmissions in ground IoT networks. Toward this purpose, it is
considered that a set of UAVs acting as aerial base stations provide secure
connectivity between the network and multiple ground nodes. Then, the
association of IoT nodes, the 3D positioning of the UAVs and the power
allocation of the UAVs are obtained by leveraging game theoretic and convex
optimization-based tools with the goal of improving the secrecy of the system.
It is shown that the proposed framework obtains better and more efficient
secrecy performance over an IoT network than state-of-the-art greedy algorithms
for positioning and association
A Tutorial on Environment-Aware Communications via Channel Knowledge Map for 6G
Sixth-generation (6G) mobile communication networks are expected to have
dense infrastructures, large-dimensional channels, cost-effective hardware,
diversified positioning methods, and enhanced intelligence. Such trends bring
both new challenges and opportunities for the practical design of 6G. On one
hand, acquiring channel state information (CSI) in real time for all wireless
links becomes quite challenging in 6G. On the other hand, there would be
numerous data sources in 6G containing high-quality location-tagged channel
data, making it possible to better learn the local wireless environment. By
exploiting such new opportunities and for tackling the CSI acquisition
challenge, there is a promising paradigm shift from the conventional
environment-unaware communications to the new environment-aware communications
based on the novel approach of channel knowledge map (CKM). This article aims
to provide a comprehensive tutorial overview on environment-aware
communications enabled by CKM to fully harness its benefits for 6G. First, the
basic concept of CKM is presented, and a comparison of CKM with various
existing channel inference techniques is discussed. Next, the main techniques
for CKM construction are discussed, including both the model-free and
model-assisted approaches. Furthermore, a general framework is presented for
the utilization of CKM to achieve environment-aware communications, followed by
some typical CKM-aided communication scenarios. Finally, important open
problems in CKM research are highlighted and potential solutions are discussed
to inspire future work
Trajectory and Power Design for Aerial Multi-User Covert Communications
Unmanned aerial vehicles (UAVs) can provide wireless access to terrestrial
users, regardless of geographical constraints, and will be an important part of
future communication systems. In this paper, a multi-user downlink dual-UAVs
enabled covert communication system was investigated, in which a UAV transmits
secure information to ground users in the presence of multiple wardens as well
as a friendly jammer UAV transmits artificial jamming signals to fight with the
wardens. The scenario of wardens being outfitted with a single antenna is
considered, and the detection error probability (DEP) of wardens with finite
observations is researched. Then, considering the uncertainty of wardens'
location, a robust optimization problem with worst-case covertness constraint
is formulated to maximize the average covert rate by jointly optimizing power
allocation and trajectory. To cope with the optimization problem, an algorithm
based on successive convex approximation methods is proposed. Thereafter, the
results are extended to the case where all the wardens are equipped with
multiple antennas. After analyzing the DEP in this scenario, a tractable lower
bound of the DEP is obtained by utilizing Pinsker's inequality. Subsequently,
the non-convex optimization problem was established and efficiently coped by
utilizing a similar algorithm as in the single-antenna scenario. Numerical
results indicate the effectiveness of our proposed algorithm.Comment: 30 pages, 9 figures, submitted to the IEEE journal for revie
Physical layer security in 5G and beyond wireless networks enabling technologies
Information security has always been a critical concern for wireless communications due
to the broadcast nature of the open wireless medium. Commonly, security relies on cryptographic
encryption techniques at higher layers to ensure information security. However,
traditional cryptographic methods may be inadequate or inappropriate due to novel improvements
in the computational power of devices and optimization approaches. Therefore,
supplementary techniques are required to secure the transmission data. Physical layer
security (PLS) can improve the security of wireless communications by exploiting the characteristics
of wireless channels. Therefore, we study the PLS performance in the fifth generation
(5G) and beyond wireless networks enabling technologies in this thesis. The thesis
consists of three main parts.
In the first part, the PLS design and analysis for Device-to-Device (D2D) communication
is carried out for several scenarios. More specifically, in this part, we study the
underlay relay-aided D2D communications to improve the PLS of the cellular network. We
propose a cooperative scheme, whereby the D2D pair, in return for being allowed to share
the spectrum band of the cellular network, serves as a friendly jammer using full-duplex
(FD) and half-duplex (HD) transmissions and relay selection to degrade the wiretapped
signal at an eavesdropper. This part aims to show that spectrum sharing is advantageous
for both D2D communications and cellular networks concerning reliability and robustness
for the former and PLS enhancement for the latter. Closed-form expressions for the D2D
outage probability, the secrecy outage probability (SOP), and the probability of non-zero
secrecy capacity (PNSC) are derived to assess the proposed cooperative system model. The
results show enhancing the robustness and reliability of D2D communication while simultaneously
improving the cellular network’s PLS by generating jamming signals towards the
eavesdropper. Furthermore, intensive Monte-Carlo simulations and numerical results are
provided to verify the efficiency of the proposed schemes and validate the derived expressions’
accuracy.
In the second part, we consider a secure underlay cognitive radio (CR) network in the
presence of a primary passive eavesdropper. Herein, a secondary multi-antenna full-duplex
destination node acts as a jammer to the primary eavesdropper to improve the PLS of the
primary network. In return for this favor, the energy-constrained secondary source gets
access to the primary network to transmit its information so long as the interference to the
latter is below a certain level. As revealed in our analysis and simulation, the reliability and
robustness of the CR network are improved, while the security level of the primary network
is enhanced concurrently.
Finally, we investigate the PLS design and analysis of reconfigurable intelligent surface
(RIS)-aided wireless communication systems in an inband underlay D2D communication
and the CR network. An RIS is used to adjust its reflecting elements to enhance the data
transmission while improving the PLS concurrently. Furthermore, we investigate the design
of active elements in RIS to overcome the double-fading problem introduced in the RISaided
link in a wireless communications system. Towards this end, each active RIS element
amplifies the reflected incident signal rather than only reflecting it as done in passive RIS
modules. As revealed in our analysis and simulation, the use of active elements leads to a
drastic reduction in the size of RIS to achieve a given performance level. Furthermore, a
practical design for active RIS is proposed
Physical layer security (PLS) solutions for passive eavesdropping in wireless communication
An absolute secured wireless communication is unattainable. Nevertheless, communication models must be secure and unique across each layer of the model. The
physical layer is the easiest layer through which information leaks, due to its broadcast nature. The security in the physical layer, measured as secrecy capacity, is
subdivided into keyed and keyless security models. In practice, the eavesdropper’s
evasive and obscure random wireless channel model makes it difficult to optimise
keyless security measure at the physical layer. Considering this practical challenge,
the objective of this work is to use novel keyless approaches to reduce the ability of
an illegitimate user to access the transmitted message via the physical layer. Physical layer security (PLS) was achieved through the deployment of unmanned aerial
vehicles (UAV), intelligent reflecting surfaces (IRS), and communication sensing as
security enablers in this thesis. The UAV operates with interfering signals while the
IRS and sensing techniques optimise respective inherent properties leading to higher
PLS performance. The thesis presents solutions to the parametric design of UAV,
IRS, and wireless sensing technologies for PLS functionality. Designs and analysis
herein follow from analytical derivations and numerical simulations. Specifically, the
thesis presents a novel average secrecy rate formulation for passive eavesdropping
with a reception rate upper bound by that of the legitimate receiver. The keyless
PLS assessed from the formulations guaranteed positive rates with the design of a
broadcast interfering signal delivered from a UAV. Based on the verification of the
positive secrecy rate with passive eavesdropping, a swarm of UAVs improved the
PLS of the communication system delivering more interfering signals. Furthermore,
the functionalities of the interference driven UAV swarm were miniaturised with a
system of aerial IRS. By harnessing inherent channel dynamics, a novel non-iterative
design of the aerial IRS system was presented as a panacea to PLS requirements.
Finally, the thesis presents the analysis of a legitimate receiver with a novel noise
and interference filter as a sensing mitigation technique. The filter enhanced PLS
by enabling the legitimate receiver to effectively extract desired information
Unmanned Aerial Vehicle (UAV)-Enabled Wireless Communications and Networking
The emerging massive density of human-held and machine-type nodes implies larger traffic deviatiolns in the future than we are facing today. In the future, the network will be characterized by a high degree of flexibility, allowing it to adapt smoothly, autonomously, and efficiently to the quickly changing traffic demands both in time and space. This flexibility cannot be achieved when the network’s infrastructure remains static. To this end, the topic of UAVs (unmanned aerial vehicles) have enabled wireless communications, and networking has received increased attention. As mentioned above, the network must serve a massive density of nodes that can be either human-held (user devices) or machine-type nodes (sensors). If we wish to properly serve these nodes and optimize their data, a proper wireless connection is fundamental. This can be achieved by using UAV-enabled communication and networks. This Special Issue addresses the many existing issues that still exist to allow UAV-enabled wireless communications and networking to be properly rolled out
IRS-Aided Uplink Security Enhancement via Energy-Harvesting Jammer
In this paper, we investigate the security enhancement by combining intelligent reflecting surface (IRS) and energy harvesting (EH) jammer for the uplink transmission. Specifically, we propose an IRS-aided secure scheme for the uplink transmission via an EH jammer, to fight against the malicious eavesdropper. The proposed scheme can be divided into an energy transfer (ET) phase and an information transmission (IT) phase. In the first phase, the friendly EH jammer harvests energy from the base station (BS) aided by IRS. We maximize the harvested energy of jammer by obtaining the closed-form solution to the phase-shift matrix of IRS. In the second phase, the user transmits confidential information to the BS while the jamming is generated to confuse the eavesdropper without affecting the legitimate transmission. The phase-shift matrix of IRS and time switching factor are jointly optimized to maximize the secrecy rate. To tackle the non-convex problem, we first decompose it into two sub-problems. The one of IRS can be approximated to convex with fixed time switching factor. Then, the time switching factor can be solved by Lagrange duality. Thus, the solution to the original problem can be obtained by alternately optimizing these two sub-problems. Simulation results show that the proposed Jammer-IRS assisted secure transmission scheme can significantly enhance the uplink security
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