26 research outputs found
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
IRS-assisted UAV Communications: A Comprehensive Review
Intelligent reflecting surface (IRS) can smartly adjust the wavefronts in
terms of phase, frequency, amplitude and polarization via passive reflections
and without any need of radio frequency (RF) chains. It is envisaged as an
emerging technology which can change wireless communication to improve both
energy and spectrum efficiencies with low energy consumption and low cost. It
can intelligently configure the wireless channels through a massive number of
cost effective passive reflecting elements to improve the system performance.
Similarly, unmanned aerial vehicle (UAV) communication has gained a viable
attention due to flexible deployment, high mobility and ease of integration
with several technologies. However, UAV communication is prone to security
issues and obstructions in real-time applications. Recently, it is foreseen
that UAV and IRS both can integrate together to attain unparalleled
capabilities in difficult scenarios. Both technologies can ensure improved
performance through proactively altering the wireless propagation using smart
signal reflections and maneuver control in three dimensional (3D) space. IRS
can be integrated in both aerial and terrene environments to reap the benefits
of smart reflections. This study briefly discusses UAV communication, IRS and
focuses on IRS-assisted UAC communications. It surveys the existing literature
on this emerging research topic and highlights several promising technologies
which can be implemented in IRS-assisted UAV communication. This study also
presents several application scenarios and open research challenges. This study
goes one step further to elaborate research opportunities to design and
optimize wireless systems with low energy footprint and at low cost. Finally,
we shed some light on future research aspects for IRS-assisted UAV
communication
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
A Survey on the Security and the Evolution of Osmotic and Catalytic Computing for 5G Networks
The 5G networks have the capability to provide high compatibility for the new
applications, industries, and business models. These networks can tremendously
improve the quality of life by enabling various use cases that require high
data-rate, low latency, and continuous connectivity for applications pertaining
to eHealth, automatic vehicles, smart cities, smart grid, and the Internet of
Things (IoT). However, these applications need secure servicing as well as
resource policing for effective network formations. There have been a lot of
studies, which emphasized the security aspects of 5G networks while focusing
only on the adaptability features of these networks. However, there is a gap in
the literature which particularly needs to follow recent computing paradigms as
alternative mechanisms for the enhancement of security. To cover this, a
detailed description of the security for the 5G networks is presented in this
article along with the discussions on the evolution of osmotic and catalytic
computing-based security modules. The taxonomy on the basis of security
requirements is presented, which also includes the comparison of the existing
state-of-the-art solutions. This article also provides a security model,
"CATMOSIS", which idealizes the incorporation of security features on the basis
of catalytic and osmotic computing in the 5G networks. Finally, various
security challenges and open issues are discussed to emphasize the works to
follow in this direction of research.Comment: 34 pages, 7 tables, 7 figures, Published In 5G Enabled Secure
Wireless Networks, pp. 69-102. Springer, Cham, 201
Practical Secrecy at the Physical Layer: Key Extraction Methods with Applications in Cognitive Radio
The broadcast nature of wireless communication imposes the risk of information leakage to adversarial or unauthorized receivers. Therefore, information security between intended users remains a challenging issue. Currently, wireless security relies on cryptographic techniques and protocols that lie at the upper layers of the wireless network. One main drawback of these existing techniques is the necessity of a complex key management scheme in the case of symmetric ciphers and high computational complexity in the case of asymmetric ciphers. On the other hand, physical layer security has attracted significant interest from the research community due to its potential to generate information-theoretic secure keys. In addition, since the vast majority of physical layer security techniques exploit the inherent randomness of the communication channel, key exchange is no longer mandatory. However, additive white Gaussian noise, interference, channel estimation errors and the fact that communicating transceivers employ different radio frequency (RF) chains are among the reasons that limit utilization of secret key generation (SKG) algorithms to high signal to noise ratio levels. The scope of this dissertation is to design novel secret key generation algorithms to overcome this main drawback. In particular, we design a channel based SKG algorithm that increases the dynamic range of the key generation system. In addition, we design an algorithm that exploits angle of arrival (AoA) as a common source of randomness to generate the secret key. Existing AoA estimation systems either have high hardware and computation complexities or low performance, which hinder their incorporation within the context of SKG. To overcome this challenge, we design a novel high performance yet simple and efficient AoA estimation system that fits the objective of collecting sequences of AoAs for SKG.
Cognitive radio networks (CRNs) are designed to increase spectrum usage efficiency by allowing secondary users (SUs) to exploit spectrum slots that are unused by the spectrum owners, i.e., primary users (PUs). Hence, spectrum sensing (SS) is essential in any CRN. CRNs can work both in opportunistic (interweaved) as well as overlay and/or underlay (limited interference) fashions. CRNs typically operate at low SNR levels, particularly, to support overlay/underlay operations. Similar to other wireless networks, CRNs are susceptible to various physical layer security attacks including spectrum sensing data falsification and eavesdropping. In addition to the generalized SKG methods provided in this thesis and due to the peculiarity of CRNs, we further provide a specific method of SKG for CRNs. After studying, developing and implementing several SS techniques, we design an SKG algorithm that exploits SS data. Our algorithm does not interrupt the SS operation and does not require additional time to generate the secret key. Therefore, it is suitable for CRNs
Reconfigurable Intelligent Surfaces for Smart Cities: Research Challenges and Opportunities
The concept of Smart Cities has been introduced as a way to benefit from the
digitization of various ecosystems at a city level. To support this concept,
future communication networks need to be carefully designed with respect to the
city infrastructure and utilization of resources. Recently, the idea of 'smart'
environment, which takes advantage of the infrastructure for better performance
of wireless networks, has been proposed. This idea is aligned with the recent
advances in design of reconfigurable intelligent surfaces (RISs), which are
planar structures with the capability to reflect impinging electromagnetic
waves toward preferred directions. Thus, RISs are expected to provide the
necessary flexibility for the design of the 'smart' communication environment,
which can be optimally shaped to enable cost- and energy-efficient signal
transmissions where needed. Upon deployment of RISs, the ecosystem of the Smart
Cities would become even more controllable and adaptable, which would
subsequently ease the implementation of future communication networks in urban
areas and boost the interconnection among private households and public
services. In this paper, we describe our vision of the application of RISs in
future Smart Cities. In particular, the research challenges and opportunities
are addressed. The contribution paves the road to a systematic design of
RIS-assisted communication networks for Smart Cities in the years to come.Comment: Submitted for possible publication in IEEE Open Journal of the
Communications Societ
Towards an enhanced noncoherent massive MU-MIMO system
PhD ThesisMany multiple-input multiple-output (MIMO) downlink transmission schemes assume
channel state information (CSI) is available at the receiver/transmitter. In
practice, knowledge of CSI is often obtained by using pilot symbols transmitted
periodically. However, for some systems, due to high mobility and the cost of
channel training and estimation, CSI acquisition is not always feasible. The problem
becomes even more difficult when many antennas are used in the system and
the channel is changing very rapidly before training is completed. Moreover, as
the number of transmit/receive antennas grows large, the number of pilot symbols,
system overheads, latency, and power consumption will grow proportionately
and thereby the system becomes increasingly complex. As an alternative, a noncoherent
system may be used wherein the transmitter/receiver does not need any
knowledge of the CSI to perform precoding or detection. This thesis focuses on
the design of a noncoherent downlink transmission system to jointly improve the
performance and achieve a simple low complexity transmission scheme in three
MIMO system scenarios: low rate differential spacetime block coding (STBC) in a
downlink multiuser (MU-MIMO) system; high rate differential algebraic STBC in
a downlink MU-MIMO system; and differential downlink transmission in a massive
MU-MIMO system. Three novel design methods for each of these systems are
proposed and analysed thoroughly.
For the MIMO system with a low rate noncoherent scheme, a differential STBC
MU-MIMO system with a downlink transmission scheme is considered. Specifically,
downlink precoding combined with differential modulation (DM) is used
to shift the complexity from the receivers to the transmitter. The block diagonalization
(BD) precoding scheme is used to cancel co-channel interference (CCI) in
addition to exploiting its advantage of enhancing diversity. Since the BD scheme
requires channel knowledge at the transmitter, the downlink spreading technique
along with DM is also proposed, which does not require channel knowledge neither
at the transmitter nor at the receivers. The orthogonal spreading (OS) scheme is
employed to have similar principle as code division multiple access (CDMA) multiplexing
scheme in order to eliminate the interference between users. As a STBC
scheme, the Alamouti code is used that can be encoded/decoded using DM thereby
eliminating the need for channel knowledge at the receiver. The proposed schemes
yield low complexity transceivers while providing good performance.
For the MIMO system with a high rate noncoherent scheme, a differential STBC
MU-MIMO system that operates at a high data rate is considered. In particular,
a full-rate full-diversity downlink algebraic transmission scheme combined with a
differential STBC systems is proposed. To achieve this, perfect algebraic space
time codes and Cayley differential (CD) transforms are employed. Since CSI is
not needed at the differential receiver, differential schemes are ideal for multiuser
systems to shift the complexity from the receivers to the transmitter, thus simplifying
user equipment. Furthermore, OS matrices are employed at the transmitter to
separate the data streams of different users and enable simple single user decoding.
In the OS scheme, the transmitter does not require any knowledge of the CSI to
separate the data streams of multiple users; this results in a system which does not
need CSI at either end. With this system, to limit the number of possible codewords,
a sphere decoder (SD) is used to decode the signals at the receiving end.
The proposed scheme yields low complexity transceivers while providing full-rate
full-diversity system with good performance.
Lastly, a differential downlink transmission scheme is proposed for a massive MIMO
system without explicit channel estimation. In particular, a downlink precoding
technique combined with a differential encoding scheme is used to simplify the
overall system complexity. A novel precoder is designed which, with a large number
of transmit antennas, can effectively precancel the multiple access interference
(MAI) for each user, thus enhancing the system performance. Maximising the worst
case signal-to-interference-plus-noise ratio (SINR) is adopted to optimise the precoder
for the users in which full power space profile (PSP) knowledge is available to
the base station (BS). Also, two suboptimal solutions based on the matched and the
orthogonality approach of PSP are provided to separate the data streams of multiple
users. The decision feedback differential detection (DFDD) technique is employed
to further improve the performance.
In summary, the proposed methods eliminate MAI, enhance system performance,
and achieve a simple low complexity system. Moreover, transmission overheads
are significantly reduced, the proposed methods avoid explicit channel estimation
at both ends.King Fahad Security Collage at the Ministry of Interior - Saudi Arabia