11 research outputs found
Seamless Mobility under a Dedicated Distributed Antenna System for High-Speed Rail Networks
High-speed railway (HSR) has demonstrated a tremendous growth worldwide, and currently is attaining a maximum velocity of 575 km/h. Such a high speed makes the mobile wireless communications a challenging task for HSR to sustain since the handover (HO) rate increases with speed which might result in a high loss of link connectivity. By employing a dedicated distributed antenna system (DAS) along with the two-hop network architecture for HSR wireless communications, this thesis aims to attain a high system capacity, a more transmission reliability, and consequently a superior mobile wireless communication quality-of-service (QoS) for commuters on HSR.
First, this thesis proposes a frequency switch (FSW) scheme to mitigate the persistent HO issue in conventional HSR wireless communication systems. The proposed scheme significantly alleviates the interruption time and the dense signalling overhead associated with the traditional HO process, providing a much more convenient scheme, i.e. fast and soft which suits the remote antenna unit (RAU) small coverage area and the train's high moving speed. Therefore, FSW scheme provides mobility robustness signalling process that guarantees a more successful frequency switch instead of HO, thereby, reduces the probability of a radio link failure (RLF) compared with HO process in traditional HSR systems.
Second, an enhanced fast predictive HO mechanism is proposed by starting the HO process earlier, when moving from one RAU coverage area to the next where these two RAUs are controlled by different central units (CUs). It shows that the proposed fast HO scheme achieves a lower HO command failure probability than the traditional HO. This leads to a lower HO failure probability which consequently can considerably enhance the end-users' quality-of-service (QoS) experience. Analytical results verify that the proposed schemes can improve the system performance substantially by delivering ultra-reliable low-latency communications.
Finally, with the aim of providing an ultra-reliable low-latency wireless communications, this thesis also proposes an onboard frequency switch scheme to further simplify our previously proposed FSW scheme
Failure Analysis in Next-Generation Critical Cellular Communication Infrastructures
The advent of communication technologies marks a transformative phase in
critical infrastructure construction, where the meticulous analysis of failures
becomes paramount in achieving the fundamental objectives of continuity,
security, and availability. This survey enriches the discourse on failures,
failure analysis, and countermeasures in the context of the next-generation
critical communication infrastructures. Through an exhaustive examination of
existing literature, we discern and categorize prominent research orientations
with focuses on, namely resource depletion, security vulnerabilities, and
system availability concerns. We also analyze constructive countermeasures
tailored to address identified failure scenarios and their prevention.
Furthermore, the survey emphasizes the imperative for standardization in
addressing failures related to Artificial Intelligence (AI) within the ambit of
the sixth-generation (6G) networks, accounting for the forward-looking
perspective for the envisioned intelligence of 6G network architecture. By
identifying new challenges and delineating future research directions, this
survey can help guide stakeholders toward unexplored territories, fostering
innovation and resilience in critical communication infrastructure development
and failure prevention
On the energy efficiency of spatial modulation concepts
Spatial Modulation (SM) is a Multiple-Input Multiple-Output (MIMO) transmission technique
which realizes low complexity implementations in wireless communication systems. Due the
transmission principle of SM, only one Radio Frequency (RF) chain is required in the transmitter.
Therefore, the complexity of the transmitter is lower compared to the complexity of
traditional MIMO schemes, such as Spatial MultipleXing (SMX). In addition, because of the
single RF chain configuration of SM, only one Power Amplifier (PA) is required in the transmitter.
Hence, SM has the potential to exhibit significant Energy Efficiency (EE) benefits. At
the receiver side, due to the SM transmission mechanism, detection is conducted using a low
complexity (single stream) Maximum Likelihood (ML) detector. However, despite the use of a
single stream detector, SM achieves a multiplexing gain.
A point-to-point closed-loop variant of SM is receive space modulation. In receive space modulation,
the concept of SMis extended at the receiver side, using linear precoding with Channel
State Information at the Transmitter (CSIT). Even though receive space modulation does not
preserve the single RF chain configuration of SM, due to the deployed linear precoding, it
can be efficiently incorporated in a Space Division Multiple Access (SDMA) or in a Virtual
Multiple-Input Multiple-Output (VMIMO) architecture.
Inspired by the potentials of SM, the objectives of this thesis are the evaluation of the EE of
SM and its extension in different forms of MIMO communication. In particular, a realistic
power model for the power consumption of a Base Station (BS) is deployed in order to assess
the EE of SM in terms of Mbps/J. By taking into account the whole power supply of a BS and
considering a Time Division Multiple Access (TDMA) multiple access scheme, it is shown that
SM is significantly more energy efficient compared to the traditional MIMO techniques. In
the considered system setup, it is shown that SM is up to 67% more energy efficient compared
to the benchmark systems. In addition, the concept of space modulation is researched at the
receiver side. Specifically, based on the union bound technique, a framework for the evaluation
of the Average Bit Error Probability (ABEP), diversity order, and coding gain of receive space
modulation is developed. Because receive space modulation deploys linear precoding with
CSIT, two new precoding methods which utilize imperfect CSIT are proposed. Furthermore, in
this thesis, receive space modulation is incorporated in the broadcast channel. The derivation of
the theoretical ABEP, diversity order, and coding gain of the new broadcast scheme is provided.
It is concluded that receive space modulation is able to outperform the corresponding traditional
MIMO scheme. Finally, SM, receive space modulation, and relaying are combined in order
to form a novel virtual MIMO architecture. It is shown that the new architecture practically
eliminates or reduces the problem of the inefficient relaying of the uncoordinated virtual MIMO
space modulation architectures. This is undertaken by using precoding in a novel fashion. The
evaluation of the new architecture is conducted using simulation and theoretical results
Recent Trends in Communication Networks
In recent years there has been many developments in communication technology. This has greatly enhanced the computing power of small handheld resource-constrained mobile devices. Different generations of communication technology have evolved. This had led to new research for communication of large volumes of data in different transmission media and the design of different communication protocols. Another direction of research concerns the secure and error-free communication between the sender and receiver despite the risk of the presence of an eavesdropper. For the communication requirement of a huge amount of multimedia streaming data, a lot of research has been carried out in the design of proper overlay networks. The book addresses new research techniques that have evolved to handle these challenges
Advanced Trends in Wireless Communications
Physical limitations on wireless communication channels impose huge challenges to reliable communication. Bandwidth limitations, propagation loss, noise and interference make the wireless channel a narrow pipe that does not readily accommodate rapid flow of data. Thus, researches aim to design systems that are suitable to operate in such channels, in order to have high performance quality of service. Also, the mobility of the communication systems requires further investigations to reduce the complexity and the power consumption of the receiver. This book aims to provide highlights of the current research in the field of wireless communications. The subjects discussed are very valuable to communication researchers rather than researchers in the wireless related areas. The book chapters cover a wide range of wireless communication topics
Demystifying Internet of Things Security
Break down the misconceptions of the Internet of Things by examining the different security building blocks available in Intel Architecture (IA) based IoT platforms. This open access book reviews the threat pyramid, secure boot, chain of trust, and the SW stack leading up to defense-in-depth. The IoT presents unique challenges in implementing security and Intel has both CPU and Isolated Security Engine capabilities to simplify it. This book explores the challenges to secure these devices to make them immune to different threats originating from within and outside the network. The requirements and robustness rules to protect the assets vary greatly and there is no single blanket solution approach to implement security. Demystifying Internet of Things Security provides clarity to industry professionals and provides and overview of different security solutions What You'll Learn Secure devices, immunizing them against different threats originating from inside and outside the network Gather an overview of the different security building blocks available in Intel Architecture (IA) based IoT platforms Understand the threat pyramid, secure boot, chain of trust, and the software stack leading up to defense-in-depth Who This Book Is For Strategists, developers, architects, and managers in the embedded and Internet of Things (IoT) space trying to understand and implement the security in the IoT devices/platforms