Physical Layer Techniques for High Frequency Wireline Broadband Systems

This thesis collects contributions to wireline and wireless communication systems with an emphasis on multiuser and multicarrier physical layer technology. To deliver increased capacity, modern wireline access systems such as G.fast extend the signal bandwidth up from tens to hundreds of MHz. This ambitious development revealed a number of unforeseen hurdles such as the impact of impedance changes in various forms. Impedance changes have a strong effect on the performance of multi-user crosstalk mitigation techniques such as vectoring. The first part of the thesis presents papers covering the identification of one of these problems, a model describing why it occurs and a method to mitigate its effects, improving line stability for G.fast systems.A second part of the thesis deals with the effects of temperature changes on wireline channels. When a vectored (MIMO) wireline system is initialized, channel estimates need to be obtained. This thesis presents contributions on the feasibility of re-using channel coefficients to speed up the vectoring startup procedures, even after the correct coefficients have changed, e.g., due to temperature changes. We also present extensive measurement results showing the effects of temperature changes on copper channels using a temperature chamber and British cables. The last part of the thesis presents three papers on the convergence of physical layer technologies, more specifically the deployment of OFDM-based radio systems using twisted pairs in different ways. In one proposed scenario, the idea of using the access copper lines to deploy small cells inside users' homes is explored. The feasibility of the concept, the design of radio-heads and a practical scheme for crosstalk mitigation are presented in three contributions

Mitigation of impulsive noise for SISO and MIMO G.fast system

To address the demand for high bandwidth data transmission over telephone transmission lines, International Telecommunication Union (ITU) has recently completed the fourth generation broadband (4GBB) copper access network technology, known as G.fast. Throughout this thesis, extensively investigates the wired broadband G.fast coding system and the novel impulsive noise reduction technique has been proposed to improve the performance of wired communications network in three different scenarios: single-line Discrete Multiple Tone (DMT)- G.fast system; a multiple input multiple-output (MIMO) DMTG.fast system, and MIMO G.fast system with different crosstalk cancellation methods. For each of these scenarios, however, Impulsive Noise (IN) is considered as the main limiting factor of performance system. In order to improve the performance of such systems, which use higher order QAM constellation such as G.fast system, this thesis examines the performance of DMT G.fast system over copper channel for six different higher signal constellations of M = 32, 128, 512, 2048, 8192 and 32768 in presence of IN modelled as the Middleton Class A (MCA) noise source. In contrast to existing work, this thesis presents and derives a novel equation of Optimal Threshold (OT) to improve the IN frequency domain mitigation methods applied to the G.fast standard over copper channel with higher QAM signal constellations. The second scenario, Multi-Line Copper Wire (MLCW) G.fast is adopted utilizing the proposed MLCW Chen model and is compared to a single line G-fast system by a comparative analysis in terms of Bit-Error-Rate(BER) performance of implementation of MLCW-DMT G.fast system. The third scenario, linear and non-linear crosstalk crosstalk interference cancellation methods are applied to MLCW G.fas and compared by a comparative analysis in terms of BER performance and the complexity of implementation.University of Technology for choosing me for their PhD scholarship and The Higher Committee For Education Development in Iraq(HCED

Transmission lines, quantum graphs and fluctuations on complex networks

High-frequency devices are commonplace and at their foundations often lie cable networks forming fundamental sub-systems with the primary role of transferring energy and information. With increasing demand for ”more electric” systems, the emerging trends in Internet of Things (IoT), as well as the surge in global mobile data traffic, the complexities of the underlying networks become more challenging to model deterministically. In such scenarios, statistical approaches are best suited because it becomes daunting to accurately model details of such networks. In this thesis, I present a quantum graph (QG) approach of modelling the transfer of energy and information through complex networks. In its own right, the graph model is used to predict the scattering spectrum in wired communications, as well as statistical predictions in wireless communication systems. I derive a more generalised vertex scattering matrix that takes into account cables of different characteristics connected at a common node. This is significant in real applications where different kinds of cables are connected. For example, in digital subscriber line (DSL) networks, the final loop drop may consist of cables with different characteristics. The proposed graph model is successfully validated both with a Transmission Line (TL) approach, and with laboratory experiments. The model agrees well with the universal predictions of Random Matrix Theory (RMT). In particular, the statistics of resonance is compared with the predictions of Weyl's law, while the level-spacing distribution is compared with the Wigner's surmise, which is a telltale signature of chaotic mixing of the underlying waves. In addition, I propose an analogue of the so-called random coupling model (RCM), which is important in the study of electromagnetic waves propagating in chaotic cavities. To achieve this, I present a procedure for symmetrising the transfer operator, which we use to modify the QG model in order for it to be comparable to RCM. Unlike the RCM which depends on Gaussian random variables, the graph model works for both Gaussian and non-Gaussian statistics. We use the analogue model to investigate the impact of different boundary conditions on the distribution of energy in networks with different topologies and connectivities. I further present a novel technique of using quantum graphs to predict the statistics of multi-antenna wireless communication systems. In this context, I present three different ways of calculating the probability density function of Shannon channel capacity. The analytical calculations compare favourably with numerical simulations of networks of varying complexities. In the area of wired communications, the graph model is used to model the distribution of data in G.fast networks (the fourth-generation Digital Subscriber Line (DSL) networks), using realistic cable parameters from the so-called TNO-Ericsson model. In particular, we show that quantum graph formalism can be used to simulate the in-premises distribution network at G.fast frequencies. The parameters of CAD$55$ (or B$05$a) cables and the in-house distribution network reported in the International Telecommunication Union documentation were used in the simulations

Transmission lines, quantum graphs and fluctuations on complex networks

High-frequency devices are commonplace and at their foundations often lie cable networks forming fundamental sub-systems with the primary role of transferring energy and information. With increasing demand for ”more electric” systems, the emerging trends in Internet of Things (IoT), as well as the surge in global mobile data traffic, the complexities of the underlying networks become more challenging to model deterministically. In such scenarios, statistical approaches are best suited because it becomes daunting to accurately model details of such networks. In this thesis, I present a quantum graph (QG) approach of modelling the transfer of energy and information through complex networks. In its own right, the graph model is used to predict the scattering spectrum in wired communications, as well as statistical predictions in wireless communication systems. I derive a more generalised vertex scattering matrix that takes into account cables of different characteristics connected at a common node. This is significant in real applications where different kinds of cables are connected. For example, in digital subscriber line (DSL) networks, the final loop drop may consist of cables with different characteristics. The proposed graph model is successfully validated both with a Transmission Line (TL) approach, and with laboratory experiments. The model agrees well with the universal predictions of Random Matrix Theory (RMT). In particular, the statistics of resonance is compared with the predictions of Weyl's law, while the level-spacing distribution is compared with the Wigner's surmise, which is a telltale signature of chaotic mixing of the underlying waves. In addition, I propose an analogue of the so-called random coupling model (RCM), which is important in the study of electromagnetic waves propagating in chaotic cavities. To achieve this, I present a procedure for symmetrising the transfer operator, which we use to modify the QG model in order for it to be comparable to RCM. Unlike the RCM which depends on Gaussian random variables, the graph model works for both Gaussian and non-Gaussian statistics. We use the analogue model to investigate the impact of different boundary conditions on the distribution of energy in networks with different topologies and connectivities. I further present a novel technique of using quantum graphs to predict the statistics of multi-antenna wireless communication systems. In this context, I present three different ways of calculating the probability density function of Shannon channel capacity. The analytical calculations compare favourably with numerical simulations of networks of varying complexities. In the area of wired communications, the graph model is used to model the distribution of data in G.fast networks (the fourth-generation Digital Subscriber Line (DSL) networks), using realistic cable parameters from the so-called TNO-Ericsson model. In particular, we show that quantum graph formalism can be used to simulate the in-premises distribution network at G.fast frequencies. The parameters of CAD$55$ (or B$05$a) cables and the in-house distribution network reported in the International Telecommunication Union documentation were used in the simulations

An Examination of the Evolution of Broadband Technologies in the UK

The aim of this thesis is to examine the reasons due to which Digital Subscriber Line (DSL) became the most widely used technology to deliver broadband connectivity in the United Kingdom (UK). The research examines the outcome starting with events in 1960s when broadband as it is defined today did not exist. The research shows that a combination of factors involving regulatory decisions, changing market conditions, and unexpected technological breakthroughs contributed to the current day mix of broadband technologies in the last mile access in the UK. To interpret the events that have shaped the development, deployment, and adoption of broadband technologies in the UK, the thesis draws from various theoretical ideas related to Science and Technology Studies (STS) to understand and analyse the events. In order to discover and establish the historical context, the thesis employs original, unpublished interviews along with the extensive use of archival material and secondary sources. Influenced by some of the core ideas of social constructionist studies, this research combines concepts from economic studies of technological change along with themes involving maintenance of technology, path dependence, and the role of bandwagon effect. These research threads are combined to understand the way development, deployment, and adoption of broadband technologies took place in the UK. The research is intended to contribute to the understanding of technology in a constantly changing regulatory and socio-economic environment and how it is shaped by multiple factors. The targeted readership is researchers, analysts, and decision makers working with broadband technology, telecommunications policy, and STS. Further research is suggested in the form of studies of wireless broadband technologies and the role of regulatory policies in the development of the UK communications market

Simple and Causal Twisted-Pair Channel Models for G.fast Systems

The use of a hybrid copper and fiber architecture is attractive in both fixed access and mobile backhauling scenarios. This trend led the industry and academia to start developing the fourth generation broadband system, which aims at achieving bitrates of 1 Gbps over short copper loops. In this context, accurate models of short twisted-pair cables operating at relatively high frequencies are key elements. This work describes new parametric cable models that incorporate four important characteristics: support of frequencies up to 200 MHz, few parameters, causal impulse responses and require relatively easy fitting procedures. The results show that the models achieve good accuracy for single segments, which are the expected topology for G.fast deployments