55 research outputs found
Secure Simultaneous Information and Power Transfer for Downlink Multi-User Massive MIMO
In this article, downlink secure transmission in simultaneous information and power transfer (SWIPT) system enabled with massive multiple-input multiple-output (MIMO) is studied. A base station (BS) with a large number of antennas transmits energy and information signals to its intended users, but these signals are also received by an active eavesdropper. The users and eavesdropper employ a power splitting technique to simultaneously decode information and harvest energy. Massive MIMO helps the BS to focus energy to the users and prevent information leakage to the eavesdropper. The harvested energy by each user is employed for decoding information and transmitting uplink pilot signals for channel estimation. It is assumed that the active eavesdropper also harvests energy in the downlink and then contributes during the uplink training phase. Achievable secrecy rate is considered as the performance criterion and a closed-form lower bound for it is derived. To provide secure transmission, the achievable secrecy rate is then maximized through an optimization problem with constraints on the minimum harvested energy by the user and the maximum harvested energy by the eavesdropper. Numerical results show the effectiveness of using massive MIMO in providing physical layer security in SWIPT systems and also show that our closed-form expressions for the secrecy rate are accurate
Physical Layer Security for Visible Light Communication Systems:A Survey
Due to the dramatic increase in high data rate services and in order to meet
the demands of the fifth-generation (5G) networks, researchers from both
academia and industry are exploring advanced transmission techniques, new
network architectures and new frequency spectrum such as the visible light
spectra. Visible light communication (VLC) particularly is an emerging
technology that has been introduced as a promising solution for 5G and beyond.
Although VLC systems are more immune against interference and less susceptible
to security vulnerabilities since light does not penetrate through walls,
security issues arise naturally in VLC channels due to their open and
broadcasting nature, compared to fiber-optic systems. In addition, since VLC is
considered to be an enabling technology for 5G, and security is one of the 5G
fundamental requirements, security issues should be carefully addressed and
resolved in the VLC context. On the other hand, due to the success of physical
layer security (PLS) in improving the security of radio-frequency (RF) wireless
networks, extending such PLS techniques to VLC systems has been of great
interest. Only two survey papers on security in VLC have been published in the
literature. However, a comparative and unified survey on PLS for VLC from
information theoretic and signal processing point of views is still missing.
This paper covers almost all aspects of PLS for VLC, including different
channel models, input distributions, network configurations,
precoding/signaling strategies, and secrecy capacity and information rates.
Furthermore, we propose a number of timely and open research directions for
PLS-VLC systems, including the application of measurement-based indoor and
outdoor channel models, incorporating user mobility and device orientation into
the channel model, and combining VLC and RF systems to realize the potential of
such technologies
Specific Absorption Rate-Aware Beamforming in MISO Downlink SWIPT Systems
This paper investigates the optimal transmit beamforming design of
simultaneous wireless information and power transfer (SWIPT) in the multiuser
multiple-input-single-output (MISO) downlink with specific absorption rate
(SAR) constraints. We consider the power splitting technique for SWIPT, where
each receiver divides the received signal into two parts: one for information
decoding and the other for energy harvesting with a practical non-linear
rectification model. The problem of interest is to maximize as much as possible
the received signal-to-interference-plus-noise ratio (SINR) and the energy
harvested for all receivers, while satisfying the transmit power and the SAR
constraints by optimizing the transmit beamforming at the transmitter and the
power splitting ratios at different receivers. The optimal beamforming and
power splitting solutions are obtained with the aid of semidefinite programming
and bisection search. Low-complexity fixed beamforming and hybrid beamforming
techniques are also studied. Furthermore, we study the effect of imperfect
channel information and radiation matrices, and design robust beamforming to
guarantee the worst-case performance. Simulation results demonstrate that our
proposed algorithms can effectively deal with the radio exposure constraints
and significantly outperform the conventional transmission scheme with power
backoff.Comment: to appear in TCO
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
Sensing-assisted Robust SWIPT for Mobile Energy Harvesting Receivers
Simultaneous wireless information and power transfer (SWIPT) has been
proposed to offer communication services and transfer power to the energy
harvesting receiver (EHR) concurrently. However, existing works mainly focused
on static EHRs, without considering the location uncertainty caused by the
movement of EHRs and location estimation errors. To tackle this issue, this
paper considers the sensing-assisted SWIPT design in a networked integrated
sensing and communication (ISAC) system in the presence of location
uncertainty. A two-phase robust design is proposed to reduce the location
uncertainty and improve the power transfer efficiency. In particular, each time
frame is divided into two phases, i.e., sensing and WPT phases, via
time-splitting. The sensing phase performs collaborative sensing to localize
the EHR, whose results are then utilized in the WPT phase for efficient WPT. To
minimize the power consumption with given communication and power transfer
requirements, a two-layer optimization framework is proposed to jointly
optimize the time-splitting ratio, coordinated beamforming policy, and sensing
node selection. Simulation results validate the effectiveness of the proposed
design and demonstrate the existence of an optimal time-splitting ratio for
given location uncertainty
Overview of RIS-Enabled Secure Transmission in 6G Wireless Networks
As sixth-generation (6G) wireless communication networks evolve, privacy
concerns are expected due to the transmission of vast amounts of
security-sensitive private information. In this context, a reconfigurable
intelligent surface (RIS) emerges as a promising technology capable of
enhancing transmission efficiency and strengthening information security. This
study demonstrates how RISs can play a crucial role in making 6G networks more
secure against eavesdropping attacks. We discuss the fundamentals, and
standardization aspects of RISs, along with an in-depth analysis of
physical-layer security (PLS). Our discussion centers on PLS design using RIS,
highlighting aspects like beamforming, resource allocation, artificial noise,
and cooperative communications. We also identify the research issues, propose
potential solutions, and explore future perspectives. Finally, numerical
results are provided to support our discussions and demonstrate the enhanced
security enabled by RIS.Comment: Accepted for Digital Communications and Networks(DCN
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