151 research outputs found
Achieving Covert Communication in Large-Scale SWIPT-Enabled D2D Networks
We aim to secure a large-scale device-to-device (D2D) network against
adversaries. The D2D network underlays a downlink cellular network to reuse the
cellular spectrum and is enabled for simultaneous wireless information and
power transfer (SWIPT). In the D2D network, the transmitters communicate with
the receivers, and the receivers extract information and energy from their
received radio-frequency (RF) signals. In the meantime, the adversaries aim to
detect the D2D transmission. The D2D network applies power control and
leverages the cellular signal to achieve covert communication (i.e., hide the
presence of transmissions) so as to defend against the adversaries. We model
the interaction between the D2D network and adversaries by using a two-stage
Stackelberg game. Therein, the adversaries are the followers minimizing their
detection errors at the lower stage and the D2D network is the leader
maximizing its network utility constrained by the communication covertness and
power outage at the upper stage. Both power splitting (PS)-based and time
switch (TS)-based SWIPT schemes are explored. We characterize the spatial
configuration of the large-scale D2D network, adversaries, and cellular network
by stochastic geometry. We analyze the adversary's detection error minimization
problem and adopt the Rosenbrock method to solve it, where the obtained
solution is the best response from the lower stage. Taking into account the
best response from the lower stage, we develop a bi-level algorithm to solve
the D2D network's constrained network utility maximization problem and obtain
the Stackelberg equilibrium. We present numerical results to reveal interesting
insights
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
Energy harvesting towards self-powered iot devices
The internet of things (IoT) manages a large infrastructure of web-enabled smart devices, small devices that use embedded systems, such as processors, sensors, and communication hardware to collect, send, and elaborate on data acquired from their environment. Thus, from a practical point of view, such devices are composed of power-efficient storage, scalable, and lightweight nodes needing power and batteries to operate. From the above reason, it appears clear that energy harvesting plays an important role in increasing the efficiency and lifetime of IoT devices. Moreover, from acquiring energy by the surrounding operational environment, energy harvesting is important to make the IoT device network more sustainable from the environmental point of view. Different state-of-the-art energy harvesters based on mechanical, aeroelastic, wind, solar, radiofrequency, and pyroelectric mechanisms are discussed in this review article. To reduce the power consumption of the batteries, a vital role is played by power management integrated circuits (PMICs), which help to enhance the system's life span. Moreover, PMICs from different manufacturers that provide power management to IoT devices have been discussed in this paper. Furthermore, the energy harvesting networks can expose themselves to prominent security issues putting the secrecy of the system to risk. These possible attacks are also discussed in this review article
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