180 research outputs found
Hardware Impairments Aware Transceiver Design for Full-Duplex Amplify-and-Forward MIMO Relaying
In this work we study the behavior of a full-duplex (FD) and
amplify-and-forward (AF) relay with multiple antennas, where hardware
impairments of the FD relay transceiver is taken into account. Due to the
inter-dependency of the transmit relay power on each antenna and the residual
self-interference in an FD-AF relay, we observe a distortion loop that degrades
the system performance when the relay dynamic range is not high. In this
regard, we analyze the relay function in presence of the hardware inaccuracies
and an optimization problem is formulated to maximize the signal to
distortion-plus-noise ratio (SDNR), under relay and source transmit power
constraints. Due to the problem complexity, we propose a
gradient-projection-based (GP) algorithm to obtain an optimal solution.
Moreover, a nonalternating sub-optimal solution is proposed by assuming a
rank-1 relay amplification matrix, and separating the design of the relay
process into multiple stages (MuStR1). The proposed MuStR1 method is then
enhanced by introducing an alternating update over the optimization variables,
denoted as AltMuStR1 algorithm. It is observed that compared to GP, (Alt)MuStR1
algorithms significantly reduce the required computational complexity at the
expense of a slight performance degradation. Finally, the proposed methods are
evaluated under various system conditions, and compared with the methods
available in the current literature. In particular, it is observed that as the
hardware impairments increase, or for a system with a high transmit power, the
impact of applying a distortion-aware design is significant.Comment: Submitted to IEEE Transactions on Wireless Communication
Optimal Power Allocation by Imperfect Hardware Analysis in Untrusted Relaying Networks
By taking a variety of realistic hardware imperfections into consideration,
we propose an optimal power allocation (OPA) strategy to maximize the
instantaneous secrecy rate of a cooperative wireless network comprised of a
source, a destination and an untrusted amplify-and-forward (AF) relay. We
assume that either the source or the destination is equipped with a large-scale
multiple antennas (LSMA) system, while the rest are equipped with a single
antenna. To prevent the untrusted relay from intercepting the source message,
the destination sends an intended jamming noise to the relay, which is referred
to as destination-based cooperative jamming (DBCJ). Given this system model,
novel closed-form expressions are presented in the high signal-to-noise ratio
(SNR) regime for the ergodic secrecy rate (ESR) and the secrecy outage
probability (SOP). We further improve the secrecy performance of the system by
optimizing the associated hardware design. The results reveal that by
beneficially distributing the tolerable hardware imperfections across the
transmission and reception radio-frequency (RF) front ends of each node, the
system's secrecy rate may be improved. The engineering insight is that equally
sharing the total imperfections at the relay between the transmitter and the
receiver provides the best secrecy performance. Numerical results illustrate
that the proposed OPA together with the most appropriate hardware design
significantly increases the secrecy rate.Comment: 29 pages, 7 figures, Submitted to IEEE Transactions on Wireless
Communication
A Survey of Physical Layer Security Techniques for 5G Wireless Networks and Challenges Ahead
Physical layer security which safeguards data confidentiality based on the
information-theoretic approaches has received significant research interest
recently. The key idea behind physical layer security is to utilize the
intrinsic randomness of the transmission channel to guarantee the security in
physical layer. The evolution towards 5G wireless communications poses new
challenges for physical layer security research. This paper provides a latest
survey of the physical layer security research on various promising 5G
technologies, including physical layer security coding, massive multiple-input
multiple-output, millimeter wave communications, heterogeneous networks,
non-orthogonal multiple access, full duplex technology, etc. Technical
challenges which remain unresolved at the time of writing are summarized and
the future trends of physical layer security in 5G and beyond are discussed.Comment: To appear in IEEE Journal on Selected Areas in Communication
Full-duplex wireless communications: challenges, solutions and future research directions
The family of conventional half-duplex (HD) wireless systems relied on transmitting and receiving in different time-slots or frequency sub-bands. Hence the wireless research community aspires to conceive full-duplex (FD) operation for supporting concurrent transmission and reception in a single time/frequency channel, which would improve the attainable spectral efficiency by a factor of two. The main challenge encountered in implementing an FD wireless device is the large power difference between the self-interference (SI) imposed by the device’s own transmissions and the signal of interest received from a remote source. In this survey, we present a comprehensive list of the potential FD techniques and highlight their pros and cons. We classify the SI cancellation techniques into three categories, namely passive suppression, analog cancellation and digital cancellation, with the advantages and disadvantages of each technique compared. Specifically, we analyse the main impairments (e.g. phase noise, power amplifier nonlinearity as well as in-phase and quadrature-phase (I/Q) imbalance, etc.) that degrading the SI cancellation. We then discuss the FD based Media Access Control (MAC)-layer protocol design for the sake of addressing some of the critical issues, such as the problem of hidden terminals, the resultant end-to-end delay and the high packet loss ratio (PLR) due to network congestion. After elaborating on a variety of physical/MAC-layer techniques, we discuss potential solutions conceived for meeting the challenges imposed by the aforementioned techniques. Furthermore, we also discuss a range of critical issues related to the implementation, performance enhancement and optimization of FD systems, including important topics such as hybrid FD/HD scheme, optimal relay selection and optimal power allocation, etc. Finally, a variety of new directions and open problems associated with FD technology are pointed out. Our hope is that this treatise will stimulate future research efforts in the emerging field of FD communication
Reconfigurable Intelligent Surface for Physical Layer Security in 6G-IoT: Designs, Issues, and Advances
Sixth-generation (6G) networks pose substantial security risks because
confidential information is transmitted over wireless channels with a broadcast
nature, and various attack vectors emerge. Physical layer security (PLS)
exploits the dynamic characteristics of wireless environments to provide secure
communications, while reconfigurable intelligent surfaces (RISs) can facilitate
PLS by controlling wireless transmissions. With RIS-aided PLS, a lightweight
security solution can be designed for low-end Internet of Things (IoT) devices,
depending on the design scenario and communication objective. This article
discusses RIS-aided PLS designs for 6G-IoT networks against eavesdropping and
jamming attacks. The theoretical background and literature review of RIS-aided
PLS are discussed, and design solutions related to resource allocation,
beamforming, artificial noise, and cooperative communication are presented. We
provide simulation results to show the effectiveness of RIS in terms of PLS. In
addition, we examine the research issues and possible solutions for RIS
modeling, channel modeling and estimation, optimization, and machine learning.
Finally, we discuss recent advances, including STAR-RIS and malicious RIS.Comment: Accepted for IEEE Internet of Things Journa
Optimal Power Allocation by Imperfect Hardware Analysis in Untrusted Relaying Networks
CCBY By taking a variety of realistic hardware imperfections into consideration, we propose an optimal power allocation (OPA) strategy to maximize the instantaneous secrecy rate of a cooperative wireless network comprised of a source, a destination and an untrusted amplify-and-forward (AF) relay. We assume that either the source or the destination is equipped with a large-scale multiple antennas (LSMA) system, while the rest are equipped with a single-antenna. To prevent the untrusted relay from intercepting the source message, the destination sends an intended jamming noise to the relay, which is referred to as destination-based cooperative jamming (DBCJ). Given this system model, novel closed-form expressions are presented in the high signal-to-noise ratio (SNR) regime for the ergodic secrecy rate (ESR) and the secrecy outage probability (SOP). We further improve the secrecy performance of the system by optimizing the associated hardware design. The results reveal that by beneficially distributing the tolerable hardware imperfections across the transmission and reception radio-frequency (RF) front ends of each node, the system & #x2019;s secrecy rate may be improved. The engineering insight is that equally sharing the total imperfections at the relay between the transmitter and the receiver provides the best secrecy performance. Numerical results illustrate that the proposed OPA together with the most appropriate hardware design significantly increases the secrecy rate
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