Various directional comparison bus protection methods including widely used superimposed directional element method need to have both voltages and currents from all feeders connected to the zone of protection to find the direction of current for detecting a bus fault or a line fault. The purpose of the thesis is to present a new technique for directional comparison bus protection to discriminate a bus fault from line fault and normal condition. The new technique, which is implementing superimposed directional element method to modify partial operating current characteristics (POC) method to superimposed POC (SPOC) method, does not use voltages from feeders, hence capacitor voltage transformers (CVTs) are no longer needed in the zone of protection. The proposed technique was implemented in 4-bus and IEEE 14-bus test system and was tested using different fault cases including CT saturation and high impedance fault. The proposed technique, SPOC method was compared with POC method with both methods implemented in same test systems and tested with same fault cases. The results show that the proposed technique is successful to detect bus faults with high accuracy and high speed.

Due to the rapid development of telecommunication devices, operating speeds are getting faster and more power is being consumed by those devices. Therefore, there is a big concern on how to prolong the battery life in order to fit consumers’ needs. Power amplifiers (PA) at the front end of wireless equipment have drawn a big concern from engineers because of their large power consumption in the system. There is a lot research conducted on PA solutions for improving power-added efficiency (PAE) of amplifiers. PAE is a figure of merit representing how efficient the PA converts DC power to RF power. With PAE increased, the device is able to output the same amount of power with less DC power consumed. Non-linear Class-F and Class-F-1 PAs have drawn the most attention among all different classes of PAs from engineers because of their capability of outputting high power and providing good PAE. Class-F boosts up PAE by controlling the harmonic content at the output. Advanced Design System (ADS) from Agilent is used for design and simulation based on the ADS model of Cree’s CGH40010 high electron mobility transistor (HEMT). A high efficiency power amplifier is fabricated on RT/duroid 5870 high frequency laminate board. In this design, the harmonics at the input are controlled as well as the harmonics at the output. An input wave-shaping network is designed to shape the waveforms at the gate. In this case, the PAE is boosted 30% higher than the PA with only the output wave-shaping network. By terminating harmonics with proper impedances at the output, a square voltage waveform and a half-sine current waveform are obtained at the transistor drain terminal. The overlapping area between the voltage and current waveforms can be reduced as well as the active device power consumption. The final design operating at 1GHz produced a PAE of 89% with 38.35dBm output power in simulation and PAE of 78% with 38.7dBm output power as the result of the IEEE PA design contest. The thesis has shown the effectiveness of the Class-F PA to boost up PAE by preventing the 2nd and 3rd harmonic power from delivering to the load and shaping the waveforms at the transistor terminals. It also shows the benefit of using radial stubs in wave-shaping networks over open-circuit stubs.

Les communications sans fil sont essentielles pour les nouveaux systèmes des transports. Ainsi, ces communications sans fil doivent être capables d'opérer sans interruption quelque soit l'environnement électromagnétique (EM) dans lequel elles se trouvent. Pour cette raison, nous nous étudions comment certains environnements EM affectent les systèmes de communication. Dans cette thèse, nous nous sommes intéressés aux trains à grande vitesse. Dans ce secteur, on peut trouver des interférences EM intentionnelles (IEMI) et des interférences EM non intentionnelles (EMI). Nous avons considéré comme EMI les signaux interférences électromagnétiques transitoires produites par les pertes de contact entre la caténaire et le pantographe. Pour les IEMI, nous avons utilisé des signaux d'interférence générés par des brouilleurs. Nous avons étudié la vulnérabilité du réseau de communication IEEE 802.11n face à ces différents types d'interférences. Par la suite nous avons identifié le mécanisme d'accès au canal comme un point potentiellement vulnérable aux deux types d'interférences. En effet, une interférence de faible puissance peut faire croire que le canal est occupé, empêchant toute communication. Concernant les IEMI, nous avons remarqué que la période de balayage de la bande de fréquence du signal du brouillage est un paramètre important pour que celui-ci soit efficace. Pour les signaux EMI, nous avons identifié la période DIFS comme étant un autre paramètre vulnérable de la norme, car à partir d'un certain niveau de puissance d'interférence et dès que l'intervalle de répétition entre les transitoires est inférieur au DIFS, la communication est systématiquement interrompue. / Wireless communications are essential for new transportation systems. Thus, these wireless communications must be able to operate without interruption, regardless of the electromagnetic (EM) environment. For this reason, we study how some EM environments affect communication systems. In this thesis, we are particularly interested in the transportation sector, especially high speed trains. In this sector, both unintentional EM interferences (EMI) and intentional EM interferences (IEMI) can be found. We considered unintentional EM interferences (EMI), such as transient EM interference signals produced by contact losses between the catenary and the pantograph. For intentional EM interferences (IEMI) we used interference signals as those generated by low power commercial jammers. We have studied the vulnerability of the IEEE 802.11n communication network facing these different interference types. We identified the channel access mechanism as a vulnerable feature of IEEE 802.11n. As a matter of fact, in the presence of low power interferences, the channel can be considered busy by the channel access mechanism, preventing any communication. With regard to the IEMI, we have noticed that the sweep period of the frequency band of the jamming signal is an important parameter on the jamming performance. For transient EM interference signals, we identified the DIFS period as another vulnerable parameter of the standard. Indeed, when the repetition interval between transients is lower than DIFS period, with a certain interference power level, the communication is systematically interrupted.

New generations of video surveillance systems are expected to possess a large-scale network of intelligent video cameras with built-in image processing capabilities. These systems need to be tethered for reasons of bandwidth and power requirements. To support economical installation of video cameras and to manage the huge volume of information flow in these networks, there is a need for new shared-medium daisy-chained physical and medium access control (bus arbitration) layer communication protocols. This thesis describes the design principles of Spatial reuse FireWire Protocol (SFP), a novel request/grant bus arbitration protocol, architected for an acyclic daisy-chained network topology. SFP is a new extension of the IEEE 1394b FireWire architecture. SFP preserves the simple repeat path functionality of FireWire while offering two significant advantages: 1) SFP supports concurrent data transmissions over disjoint segments of the network (spatial reuse of bandwidth), which increases the effective throughput and 2) SFP provides support for priority traffic, which is necessary to handle real-time applications (like packet video), and mission critical applications (like event notifications between cameras) that have strict delay and jitter constraints. The delay and throughput performance of FireWire and SFP were evaluated using discrete-event queuing simulation models built with the CSIM-18 simulation library. Simulation results show that for a homogeneous traffic pattern SFP improves upon the throughput of IEEE 1394b by a factor of 2. For a traffic pattern typical of video surveillance applications, throughput increases by a factor of 7. Simulation results demonstrate that IEEE 1394b asynchronous stream based packet transactions offer better delay performance than isochronous transactions for variable bit rate video like MPEG-2 and MPEG-4. SFP extends this observation by supporting priority traffic. QoS for packet video is provided in SFP by mapping individual asynchronous stream packets to the three priority classes.

Syftet med studien har varit att analysera produktionsrelaterad teknik för att utveckla en kostnadseffektiv lösning för dataöverföring mellan maskinens styrsystem och trådlösa enheter. Anledningen till att trådlösa metoder valdes för arbetet var att kunna reparera de olika givarnas fel och att ingripa i sensorerna i realtid. Vid användning av en bärbar enhet måste felet repareras och testas på maskinen. Undersökningen innefattar även att utveckla en lämplig metod för att trådlöst överföra uppsamlade mätdata till serverns miljö där mätdata ska lagras för att kunna presentera senare diagram, tabeller och använda mätdata för statistiska beräkningar. De rekommenderade metoderna som ska undersökas bör sedan appliceras i en produktionsmiljö med högkvalitativa säkerhetskrav. Anledningen till detta är att minimera produktionsstopp i samband med kvalificerad reparation. Många små och medelstora företag har inte råd att investera i dyr teknik, som i sin tur måste uppdateras regelbundet för att rymma ny utrustning, plattformar och utbilda underhållspersonal För dem kan det vara bra att installera ett billigt system som enkelt kan installeras och implementeras i sitt befintliga ekonomiskt styrsystem med minimikostnader med hjälp av oberoende varumärkesvaror. Resultaten av en systemundersökning har visat att dataöverföring med vissa metoder som kräver mindre säkerhetskrav och hög energiförbrukning blir mer instabila och mer mottagliga i framtiden. / The purpose of the study has been to analyze production-related tech-nology to develop a cost-effective solution for data transmission be-tween the machine's control systems and wireless devices. The reason why wireless methods were chosen for the work was to be able to repair the various donors' faults and to intervene in the sensors in real time. When using a portable device, the fault must be repaired and tested on the machine. The survey also involves developing a suitable method for wirelessly transmitting collected measurement data to the server's environment where measurement data is to be stored in order to present later charts, tables and use measurement data for statistical calculations. The recommended methods to be examined should then be applied in a production environment with high quality safety requirements. The reason for this is to minimize production stoppages in connection with qualified repair. Many SMEs cannot afford to invest in expensive technology, which in turn needs to be regularly updated to accommodate new equipment, platforms and training maintenance staff For them, it may be good to install a cheap system that can be easily installed and implemented in its existing financial control system with minimum costs using independent branded goods. The results of a system survey have shown that data transmission with certain methods that require less security requirements and high energy consumption becomes more unstable and more susceptible in the future.

Doctor of Philosopy (PhD) / Wireless communication always attracts extensive research interest, as it is a core part of modern communication technology. During my PhD study, I have focused on two research areas of wireless communication: IEEE 802.11 network performance analysis, and wireless cooperative retransmission. The first part of this thesis focuses on IEEE 802.11 network performance analysis. Since IEEE 802.11 technology is the most popular wireless access technology, IEEE 802.11 network performance analysis is always an important research area. In this area, my work includes the development of three analytical models for various aspects of IEEE 802.11 network performance analysis. First, a two-dimensional Markov chain model is proposed for analysing the performance of IEEE 802.11e EDCA (Enhanced Distributed Channel Access). With this analytical model, the saturated throughput is obtained. Compared with the existing analytical models of EDCA, the proposed model includes more correct details of EDCA, and accordingly its results are more accurate. This better accuracy is also proved by the simulation study. Second, another two-dimensional Markov chain model is proposed for analysing the coexistence performance of IEEE 802.11 DCF (Distributed Coordination Function) and IEEE 802.11e EDCA wireless devices. The saturated throughput is obtained with the proposed analytical model. The simulation study verifies the proposed analytical model, and it shows that the channel access priority of DCF is similar to that of the best effort access category in EDCA in the coexistence environment. The final work in this area is a hierarchical Markov chain model for investigating the impact of data-rate switching on the performance of IEEE 802.11 DCF. With this analytical model，the saturated throughput can be obtained. The simulation study verifies the accuracy of the model and shows the impact of the data-rate switching under different network conditions. A series of threshold values for the channel condition as well as the number of stations are obtained to decide whether the data-rate switching should be active or not. The second part of this thesis focuses on wireless cooperative retransmission. In this thesis, two uncoordinated distributed wireless cooperative retransmission strategies for single-hop connection are presented. In the proposed strategies, each uncoordinated cooperative neighbour randomly decide whether it should transmit to help the frame delivery depending on some pre-calculated optimal transmission probabilities. In Strategy 1, the source only transmits once in the first slot, and only the neighbours are involved in the retransmission attempts in the subsequent slots. In Strategy 2, both the source and the neighbours participate in the retransmission attempts. Both strategies are first analysed with a simple memoryless channel model, and the results show the superior performance of Strategy 2. With the elementary results for the memoryless channel model, a more realistic two-state Markov fading channel model is used to investigate the performance of Strategy 2. The simulation study verifies the accuracy of our analysis and indicates the superior performance of Strategy 2 compared with the simple retransmission strategy and the traditional two-hop strategy.

Master of Engineering (Research) / Educational standards are having a significant impact on e-Learning. They allow for better exchange of information among different organizations and institutions. They simplify reusing and repurposing learning materials. They give teachers the possibility of personalizing them according to the student’s background and learning speed. Thanks to these standards, off-the-shelf content can be adapted to a particular student cohort’s context and learning needs. The same course content can be presented in different languages. Overall, all the parties involved in the learning-teaching process (students, teachers and institutions) can benefit from these standards and so online education can be improved. To materialize the benefits of standards, learning resources should be structured according to these standards. Unfortunately, there is the problem that a large number of existing e-Learning materials lack the intrinsic logical structure required, and further, when they have the structure, they are not encoded as required. These problems make it virtually impossible to share these materials. This thesis addresses the following research question: How to make the best use of existing open learning resources available on the Internet by taking advantage of educational standards and specifications and thus improving content reusability?In order to answer this question, I combine different technologies, techniques and standards that make the sharing of publicly available learning resources possible in innovative ways. I developed and implemented a three-stage tool to tackle the above problem. By applying information extraction techniques and open e-Learning standards to legacy learning resources the tool has proven to improve content reusability. In so doing, it contributes to the understanding of how these technologies can be used in real scenarios and shows how online education can benefit from them. In particular, three main components were created which enable the conversion process from unstructured educational content into a standard compliant form in a systematic and automatic way. An increasing number of repositories with educational resources are available, including Wikiversity and the Massachusetts Institute of Technology OpenCourseware. Wikivesity is an open repository containing over 6,000 learning resources in several disciplines and for all age groups [1]. I used the OpenCourseWare repository to evaluate the effectiveness of my software components and ideas. The results show that it is possible to create standard compliant learning objects from the publicly available web pages, improving their searchability, interoperability and reusability.

IEEE 802.16標準中有所謂Mobile Multi-hop Relay（MMR）的概念，然而基地台覆蓋範圍不足及遮蔽效應等問題尚待解決，因此在IEEE 802.16j標準中提出Relay Station（RS）以提升網路傳輸量並增進無線通訊品質。在MMR中由於多了中繼傳輸站來傳遞資料，因此需要有較多的連線頻道，此外也不能保證所有頻道都處於良好狀態，所以會有很高的機率造成資料傳送失敗。混和自動重傳要求（Hybrid Automatic Repeat reQuest, HARQ）的提出便是用來保證資料傳遞成功的機制。HARQ在IEEE 802.16-2004就已被提出，然而我們發現該HARQ機制在802.16j中是不具效率的，而且也並無法確保QoS（Quality of Service）的要求。在本論文中我們改善Chen[4]所提出的Dynamic Pre-allocation HARQ（DP-HARQ）機制，藉由考慮slot分配不足及封包發生非連續錯誤時造成延遲時間增加等問題，並加入具服務品質感知（QoS aware）的機制，以降低整體延遲時間（delay）並能有效提高吞吐量（throughput）。最後，我們以具二個hop以上的模擬環境，證明我們所提出的方法優於802.16j的HARQ機制及Chen[4]的方法。 / Mobile Multihop Relay (MMR) had already been defined in IEEE 802.16 network. The major purpose of MMR is to efficiently extend the coverage of a base station and to solve the shadow fading problem. The Relay Station (RS) defined in IEEE 802.16j is thus proposed to fulfill these goals. Because of the MMR Relay Station, we need more channels to transmit packets. However we cannot guarantee that all chaneels are in good condtion, there might be a high probability of failure transmission. The Hybrid Automatically Repeat reQuest (HARQ) mechanism is therefor proposed to ensure the successful transmission. The HARQ proposed in IEEE 802.16-2004 is not sufficient in 802.16j. Besides it can not help to meet QoS (Quality of Service) requirements. In this reserch we improve Chen’s [4] Dynamic Pre-allocation HARQ (DP-HARQ) mechanism by considering some problems like lack of slot allocation and packet transmission failure with non-continuous error, etc. We add the QoS aware mechanism to reduce the overall delay time and improve the throughput effectively. Finally, we simulate three hops environment and show that our method outperforms both the standard IEEE 802.16j the HARQ mechanism and Chen’s [4] method.

La conception des systèmes mécatroniques, vu leur complexité, nécessite d'entreprendre une approche systémique qui implique l'utilisation d'une méthodologie permettant, en premier lieu, de considérer le système avec toutes ces composantes (mécanique, électronique, informatique, etc.), de concevoir et de spécifier ce système par la définition de ces composants et des liens qui existent entre eux. D'autre part, elle doit aussi donner la possibilité de décrire ces composants avec les outils existants des différents domaines technologiques. Nous nous sommes tournés vers des technologies orientées-objet, en l'occurence l'ingénierie guidée par les modèles MDE, pour construire une méthodologie permettant d'entreprendre cette approche systématique supportant les activités d'ingénierie décrites dans le standard ISO/IEC/IEEE 15288. Dans cette thèse, nous proposons une méthodologie qui répond à ces besoins intitulés MISSyM. Dans MISSyM, les activités de conception sont réalisées sur des modèles SysML étendus par des profils supportant le standard IEEE 15288. De plus, MISSyM intègre le support d'éléments de modélisation spécifiques aux systèmes mécatroniques. Nous avons aussi intégrer dans MISSyM une extension à SysML supportant les Bonds Graphs et permettant d'entreprendre une analyse énergétique. Nous avons par la suite enrichi la méthodologie MISSyM par une méthode de vérification de la qualité de l'architecture qui repose sur un algorithme utilisant des métriques et un algorithme de partitionnement de la matrice de dépendances ou DSM. Nous avons en plus ajouté la génération de codes vers le langage de simulation Modelica. Finalement, nous avons décrit le processus global de la méthodologie basé sur l'architecture de modèles MDA et en concordance avec le standard IEEE 15288. Nous avons fourni un exemple d'application pour permettre aux ingénieurs système de mieux utiliser le langage SysML à travers cette méthodologie.

La problématique de la qualité de service dans les réseaux locaux sans fils IEEE 802.11 demeure l'un des défis délicats à surmonter par la communauté scientifique. L'étude et l'évaluation des approches apportés pour le support de QoS dans ce type de réseaux que ce soit par des simulations, des modèles analytiques ou des mesures réelles montre que ces approches sont toujours insuffisantes pour apporter des vraies garanties de qualité de services aux utilisateurs sans fils. Suite à des travaux effectués au CRAN qui ont porté sur l'équilibrage des charges dans les réseaux Ethernet industriels nous avons opté pour une méthode d'équilibrage de charges dans le contexte des réseaux hotspots 802.11. L'objectif de cette approche étant d'équilibrer les charges des points d'accès pour satisfaire aux besoins en termes de qualité de service de l'ensemble des applications sans fils. Ces besoins sont exprimés en termes de disponibilité, de délais, de bande passante...Nous avons alors définis un algorithme d'équilibrage de charges pouvant établir dynamiquement des associations optimales entre les utilisateurs présents dans un hotspot et les points d'accès en service. Un protocole d'échanges entre les stations sans fils et les points d'accès et entre ces derniers et le serveur d'équilibrage de charges a été établi. Le fonctionnement de ce protocole a été vérifié et simulé en utilisant les outils SDL et MSC. Pour l'évaluation de la performance de l'approche d'équilibrage par rapport à la méthode d'accès de base du protocole, un ensemble de simulations ont été effectués. Ces simulations effectuées sur OPNET montrent que cette approche permet d'améliorer un ensemble de paramètres de qualité de service perçue par les utilisateurs d'un réseau Hotspot.