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Thesis (M.Phil.)--City University of Hong Kong, 2009. / "Submitted to Department of Electronic Engineering in partial fulfillment of the requirements for the degree of Master of Philosophy." Includes bibliographical references.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 96-104). Also available via the Internet.

M.Ing. (Electrical And Electronic Engineering) / In-vehicle Power Line Communication (PLC) is an emerging technology that can easily bene t the automotive industry by reducing the amount of wires (and hence cost, weight and complexity) for vehicle wire harnesses. The reduction in weight would also lead to less fuel consumption. This dissertation aims at taking the research of this technology a step towards fully understanding the vehicle's power line as a communication medium. We investigate the bit error characteristics of a readily available transceiver on the vehicle's power bus. To do so, we develop and perform bit error recording over the medium to get experimental results with the battery line under di ferent operating conditions. Using the rst set of these results, we parametrise di erent kinds of Markov models to see which one simulates the channel best. Using the preferred model, we then model the rest of the sets of results so that we can simulate the channel's bit error characteristics under these di erent conditions. Using these models, we demonstrate how these simulations can be used to evaluate the performance of di erent error detection and correction techniques. In particular, we evaluate the error detection mechanisms used in the popular in-vehicle Local Intercon- nect Network (LIN) protocol, in addition to some simple error correction techniques.

M.Phil. / The advantages offered by power line communications (hereon after called PLC) cannot be over-emphasized neither can the inherent problems affecting its commercial takeover be underestimated. This research work creates a background study for experimental measurement and eventual implementations on power lines. It explains those salient aspects of commercially available communication modules that are rather not straight forward to understand from reading the Comblocks user manual. Especially, addressing those shortcomings of Comblocks that were not indicated in the documentation, we o er solutions to those we could nd our way around. M-ary frequency shift keying was implemented. This implementation tested the ro- bustness of the scheme against noises, attenuation and other power line channel char- acteristics as encountered practically. Based on our results, we nally recommend an optimal set of frequencies; we believe to be good for use in most PLC application pur- poses. Pseudo random bits of information were generated, encoded and modulated; the signals were transmitted over power line channels. The impact of noise sources, impulse noise especially was observed at di erent distances along the channel. Coupling and decoupling circuits used for this research, with associated issues sur- rounding the use of coupling circuitry are also presented. The CENELEC norm for PLC communication was adhered to, hence only frequencies that fall within the CENELEC speci cation for low voltage power distribution network were considered for MFSK use. Signal-to-noise ratio and other factors that a ect signal transmission over PLC was also measured. A complete communication system comprises of the transmitter, the channel and the receiver. This work however did not cover the receiver part of the system. Future work can now be done on this aspect which amongst others can take care of synchronization issues, in which a coding system as well as bit error rates can be determined.

D.Ing. / The technique of using a live power cable to simultaneously transport a communication signal, has been practiced since the early 1900’s. In most cases, power-line communications has been implemented as a retrofit technology, with its main benefit being the utilization of a ‘free’ existing network. This driving force of power-line communications is typical for high-, medium-, and low-voltage distribution networks, as well as intra-building networks currently targeted for home automation and home networking. Researchers have thus focused on the optimum use of these existing power-line channels, often accepting the inherent drawbacks of this hostile communication channel. Apart from unpredictable noise sources, two main disadvantages of the low-voltage powerline network as a communication channel, are i) the unknown power cable characteristics and topology and ii) time-dependent fluctuation of the power-line impedance level as loads are unpredictable switched into, and out of the network. These two factors have obscured the requirements for proper coupling and impedance adaptation to the degree that most researchers and manufacturers have merely accepted this typical ≈ 20-dB coupling loss as one of the inherited disadvantages of the power-line channel. Most researchers and manufacturers have thus defaulted to a guessed power-line impedance level, and have used one fixed coupler winding ratio under all circumstances, regardless of power-line conditions. This study has shown that proper coupling and impedance adaptation can yield significant transmission gains even with limited (qualitative) knowledge of a power-line channel and its topology. After formulating design steps for an impedance-adapting coupler that facilitates bidirectional transmission, the impact of the fluctuating power-line impedance on coupler bandwidth was investigated. Next, impedance adaptation strategies were considered and the tradeoff between series cable requirements and parallel load requirements was explored. A model of sufficient simplicity was developed to facilitate qualitative description and classification of power outlets – functioning as communication nodes. Very interesting simulation results were obtained and these were verified using a laboratory setup of characterized power cables and calibrated loads. Next, these simulation results were employed to improve power-line transmission over a live, uncharacterized 220-V residential network by means of i) classifying typical residential rooms qualitatively in order to choose proper coupler winding ratios and ii) using an innovative dual coupler for dedicated on-off switching with harsh loads, thereby mitigating the fluctuating impact of said loads on low-voltage power-line communications.

Power line carrier (PLC) is one of the communication and load control (C&LC) techniques employed in direct load control. A PLC is, within itself, a communication system. It utilizes power transmission line as a medium of transmitting control functions, and relaying. High frequencies, in the order of 30 to 300 kHz, are used. Power line carrier systems are, at present, the most attractive C&LC systems. Recently, dispersed generation - photovoltaics, wind energy, small scale hydro - is introduced to power systems. The introduction of small scale dispersed generation sources degrades the performance of PLC systems by injecting dc-ac inverter related harmonics into the distribution lines. These harmonics interfere with PLC signals. Thus load control functions assigned to PLC systems are affected. It is the purpose of this research to study how a PLC signal propagates through the transmission line and how it is affected by the harmonic interference. An experiment is conducted using a distribution network provided by the Jet Propulsion Laboratory discussions, and conclusions are presented. / M.S.

A thesis submitted in ful lment of the requirements for the degree of Doctor of Philosophy in the School of Electrical and Information Engineering Faculty of Engineering and Built Environment June 2017 / The realization of robust, reliable and e cient data transmission have been the theme of recent research, most importantly in real channel such as the noisy, fading prone power line communication (PLC) channel. The focus is to exploit old techniques or create new techniques capable of improving the transmission reliability and also increasing the transmission capacity of the real communication channels. Multi-carrier modulation scheme such as Orthogonal Frequency Division Multiplexing (OFDM) utilizing conventional single-carrier modulation is developed to facilitate a robust data transmission, increasing transmission capacity (e cient bandwidth usage) and further reducing design complexity in PLC systems. On the contrary, the reliability of data transmission is subjected to several inhibiting factors as a result of the varying nature of the PLC channel. These inhibiting factors include noise, perturbation and disturbances. Contrary to the Additive White Gaussian noise (AWGN) model often assumed in several communication systems, this noise model fails to capture the attributes of noise encountered on the PLC channel. This is because periodic noise or random noise pulses injected by power electronic appliances on the network is a deviation from the AWGN. The nature of the noise is categorized as non-white non-Gaussian and unstable due to its impulsive attributes, thus, it is labeled as Non-additive White Gaussian Noise (NAWGN). These noise and disturbances results into long burst errors that corrupts signals being transmitted, thus, the PLC is labeled as a horrible or burst error channel. The e cient and optimal performance of a conventional linear receiver in the white Gaussian noise environment can therefore be made to drastically degrade in this NAWGN environment. Therefore, transmission reliability in such environment can be greatly enhanced if we know and exploit the knowledge of the channel's statistical attributes, thus, the need for developing statistical channel model based on empirical data. In this thesis, attention is focused on developing a recon gurable software de ned un-coded single-carrier and multicarrier PLC transceiver as a tool for realizing an optimized channel model for the narrowband PLC (NB-PLC) channel. First, a novel recon gurable software de ned un-coded single-carrier and multi-carrier PLC transceiver is developed for real-time NB-PLC transmission. The transceivers can be adapted to implement di erent waveforms for several real-time scenarios and performance evaluation. Due to the varying noise parameters obtained from country to country as a result of the dependence of noise impairment on mains voltages, topology of power line, place and time, the developed transceivers is capable of facilitating constant measurement campaigns to capture these varying noise parameters before statistical and mathematically inclined channel models are derived. Furthermore, the single-carrier (Binary Phase Shift Keying (BPSK), Di erential BPSK (DBPSK), Quadrature Phase Shift Keying (QPSK) and Di erential QPSK (DQPSK)) PLC transceiver system developed is used to facilitate a First-Order semi-hidden Fritchman Markov modeling (SHFMM) of the NB-PLC channel utilizing the e cient iterative Baum- Welch algorithm (BWA) for parameter estimation. The performance of each modulation scheme is evaluated in a mildly and heavily disturbed scenarios for both residential and laboratory site considered. The First-Order estimated error statistics of the realized First- Order SHFMM have been analytically validated in terms of performance metrics such as: log-likelihood ratio (LLR), error-free run distribution (EFRD), error probabilities, mean square error (MSE) and Chi-square ( 2) test. The reliability of the model results is also con rmed by an excellent match between the empirically obtained error sequence and the SHFMM regenerated error sequence as shown by the error-free run distribution plot. This thesis also reports a novel development of a low cost, low complexity Frequency-shift keying (FSK) - On-o keying (OOK) in-house hybrid PLC and VLC system. The functionality of this hybrid PLC-VLC transceiver system was ascertained at both residential and laboratory site at three di erent times of the day: morning, afternoon and evening. A First and Second-Order SHFMM of the hybrid system is realized. The error statistics of the realized First and Second-Order SHFMMs have been analytically validated in terms of LLR, EFRD, error probabilities, MSE and Chi-square ( 2). The Second-Order SHFMMs have also been analytically validated to be superior to the First-Order SHFMMs although at the expense of added computational complexity. The reliability of both First and Second-Order SHFMM results is con rmed by an excellent match between the empirical error sequences and SHFMM re-generated error sequences as shown by the EFRD plot. In addition, the multi-carrier (QPSK-OFDM, Di erential QPSK (DQPSK)-OFDM) and Di erential 8-PSK (D8PSK)-OFDM) PLC transceiver system developed is used to facilitate a First and Second-Order modeling of the NB-PLC system using the SHFMM and BWA for parameter estimation. The performance of each OFDM modulation scheme in evaluated and compared taking into consideration the mildly and heavily disturbed noise scenarios for the two measurement sites considered. The estimated error statistics of the realized SHFMMs have been analytically validated in terms of LLR, EFRD, error probabilities, MSE and Chi-square ( 2) test. The estimated Second-Order SHFMMs have been analytically validated to be outperform the First-Order SHFMMs although with added computational complexity. The reliability of the models is con rmed by an excellent match between the empirical data and SHFMM generated data as shown by the EFRD plot. The statistical models obtained using Baum-Welch to adjust the parameters of the adopted SHFMM are often locally maximized. To solve this problem, a novel Metropolis-Hastings algorithm, a Bayesian inference approach based on Markov Chain Monte Carlo (MCMC) is developed to optimize the parameters of the adopted SHFMM. The algorithm is used to optimize the model results obtained from the single-carrier and multi-carrier PLC systems as well as that of the hybrid PLC-VLC system. Consequently, as deduced from the results, the models obtained utilizing the novel Metropolis-Hastings algorithm are more precise, near optimal model with parameter sets that are closer to the global maxima. Generally, the model results obtained in this thesis are relevant in enhancing transmission reliability on the PLC channel through the use of the models to improve the adopted modulation schemes, create adaptive modulation techniques, develop and evaluate forward error correction (FEC) codes such as a concatenation of Reed-Solomon and Permutation codes and other robust codes suitable for exploiting and mitigating noise impairments encountered on the low voltage NB-PLC channel. Furthermore, the recon gurable software de ned NB-PLC transceiver test-bed developed can be utilized for future measurement campaign as well as adapted for multiple-input and multiple-output (MIMO) PLC applications. / MT2018

Thesis (M.S.)--University of Missouri--Rolla, 2007. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed November 26, 2007) Includes bibliographical references (p. 112-113).

Thesis (Ph.D.)--University of Wollongong, 2007. / Typescript. Includes bibliographical references: leaf 189-204.