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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Intelligent network manager for distributed multimedia conferencing

Al-Jarrah, Mohammad January 2000 (has links)
No description available.
2

Design and Implementation of a Network Manager for Industrial Automation Application in WirelessHART Networks

Shahid, Ayaz January 2014 (has links)
Wireless technology has been advancing a lot over the years and it has become mature enough to be used in industrial process control. Wireless sensor networks have overtaken the wired devices and are vastly adapted across the industry. Using wireless technologies in industrial process control results in easy installation and configuration of network and helps in reduction of overall cost. Applying wireless technologies has greater benefits but on the other hand it provides challenges due to harsh industrial environments. Nowadays, wireless sensor devices are smart enough to detect the problems within the network and are capable of producing health reports. To use the capabilities of these smart devices a centralized management is required.  A centralized network manager can manage these smart devices to improve the overall network. Network manager plays a pivotal role because it is a central part of the network and a bad network manager results in network performance degradation. This thesis work addresses the need of centralized network management and proposes a design for the network manager based on the WirelessHART standard. Several algorithms are developed based on the layered architecture of WirelessHART  and a user-friendly graphical user interface is designed for the network manager which is capable of displaying real-time performance and statistics of the network, adding and configuring the nodes, creating routes for the nodes, showing routing tables and neighbour tables and display the network topology. Any change in the network is reflected and displayed by the GUI at run time. The designed network manager is implemented and tested using both simulated packets and real hardware and the work is evaluated using Average Packet Delivery Ratio, Average End to End Delay and by comparing the work to already designed network managers.
3

Wi-Flow: uma arquitetura baseada em SDN para o gerenciamento e mobilidade em redes Wi-Fi com suporte à autenticação 802.1x

ALBUQUERQUE JÚNIOR, Edivaldo Cavalcante de 30 August 2016 (has links)
Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-04-19T14:37:00Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Proposta de dissertação - Completa - vFinal_entrega.pdf: 3978842 bytes, checksum: bfd74789ed1d6b8fb83c52919ed64fe3 (MD5) / Made available in DSpace on 2017-04-19T14:37:00Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Proposta de dissertação - Completa - vFinal_entrega.pdf: 3978842 bytes, checksum: bfd74789ed1d6b8fb83c52919ed64fe3 (MD5) Previous issue date: 2016-08-30 / As redes corporativas têm evoluído para um ambiente heterogêneo (rede sem fio e cabeada). Estas redes consideram a autenticação do usuário um elemento primordial para garantir níveis adequados de segurança no acesso aos serviços estratégicos da organização. Nas instituições de ensino e pesquisa, o sistema federado baseado na autenticação 802.1x chamado Eduroam (Education Roaming) permite que estudantes e pesquisadores obtenham conectividade sem fio utilizando as mesmas credenciais de suas instituições em qualquer lugar do mundo com suporte a este sistema. Contudo, a qualidade de serviço (QoS) percebida pelo usuário pode ser degradada quando da necessidade de mudança do ponto de acesso sem fio (handover) devido à mobilidade e necessidade de reautenticação de uma sessão em andamento. Apesar das inúmeras soluções existentes na literatura para o gerenciamento de mobilidade, o suporte à autenticação do usuário no processo de handover é um aspecto negligenciado. Esta dissertação propõe um arcabouço para o gerenciamento integrado de redes cabeadas e sem fio baseado em software de código aberto e de baixo custo. A proposta visa tornar o gerenciamento mais simples e centralizado utilizando o paradigma de redes definidas por software (SDN – Software Defined Networking) através do protocolo OpenFlow (OF). Via interface Web é possível obter informações da rede, gerenciar fluxos e controladores OF, criar slices de rede e aplicar políticas de QoS. No contexto do gerenciamento de mobilidade, a proposta implementa e avalia uma estratégia de cache de autenticação que otimiza a qualidade de experiência (QoE) durante o processo de handover e ambiente com autenticação 802.1x/Eduroam. A avaliação foi realizada num ambiente de experimentação e a proposta obteve como resultados os seguintes ganhos: 15,8% na vazão, 25% no atraso médio e 20,5% no PSNR em relação ao cenário de não utilização da proposta de cache de autenticação. Os resultados obtidos demonstram a aplicabilidade da proposta no gerenciamento mobilidade seguro, bem como sua eficácia no suporte aos requisitos de QoS/QoE para sessões de tráfego de vídeo de usuários móveis. / Corporate networks have evolved into a heterogeneous environment (wired and wireless networks). These networks consider user authentication as a key element to ensure adequate levels of security access to the organization's strategic services. In educational and research institutions, the federated system based on 802.1x authentication called Eduroam (Education Roaming) allows students and researchers to gain wireless connectivity using the same credentials of their institutions anywhere in the world that supports this system. However, the quality of service (QoS) perceived by the user can be degraded when they need to change the wireless access point (handover) due to mobility and re-authenticate a session in progress. Despite numerous existing solutions in the literature for mobility management, support for user authentication in the handover process is a neglected aspect. This dissertation proposes a framework for the integrated management of wired and wireless networks based on low cost and open source software. The proposal aims to make simpler and centralized management using the SDN (Software Defined Networking) paradigm via OpenFlow protocol (OF). Through web interface is possible to obtain information from the network, manage flows and OF controllers, create network slices, and apply QoS policies. In the mobility management context, this proposal implements and evaluates a strategy that improves the quality of experience (QoE) environment with 802.1x authentication / Eduroam. In the evaluated experimental environments, the proposed technique achieved gains up to 15.8% on throughput, 25% on average delay and 20.5% on PSNR in comparison to the baseline scenario without authentication cache. Thus, the obtained results demonstrate the applicability of the integrated network management, as well as its effectiveness in supporting of QoS / QoE requirements for video traffic sessions of the mobile users.
4

VALIDATION AND CONFORMITYTEST OF CGMES MODELS OFENTSO-E TEST NETWORKS

Zhao, Yiqi January 2016 (has links)
För att uppnå optimal resursdelning och öka hållbar energiförsörjning, stiger behovet av gränsöverskridande kraftöverföring ständigt. Därför frekventa utbyta information med detaljerade galler uppgifter krävs. För att standardisera sådant utbyte och därigenom främja gemensam kraftsystemstudier i Europa, Common Grid Model Exchange Standard (CGMES) grundar sig på IEC CIM (Common Information Models) utfärdats av ENTSO-E (European Network of Transmission Operators for Electricity) i 2013. En CGMES bedömning av överensstämmelse processen också inrättats att uppmuntra och undersöka antagandet av CGMES med relevanta kraftsystemtillämpningar. Huvudsyftet med denna avhandling är att validera att Network Manager produkten av ABB har genomfört CGMES ordentligt. Effektflödesberäkningar utförs baserat på ENTSO-Es provnäten och erhållna lösningarna jämförs med standard resultat samt resultaten från Power Factory (ett kraftsystem analysverktyg från DIgSILENT som redan har passerat bedömningen av överensstämmelse med framgång). Jämförelse resultaten analyseras alltså för att identifiera orsakerna till eventuella avvikelser från standardeffektflödeslösningar och ge förslag på framtida utveckling av Network Manager. / To achieve optimal resource sharing and enhance the sustainability of energy supply, the need for cross-border power transmission is continuously growing. Therefore, frequent information exchange with detailed grid data is required. To standardize such exchange and thus to facilitate common power system studies in Europe, the Common Grid Model Exchange Standard (CGMES) based on IEC CIM (Common Information Models) was issued by ENTSO-E (European Network of Transmission Operators for Electricity) in 2013. A CGMES conformity assessment process was also set up to encourage and examine the adoption of CGMES with relevant power system applications. The main purpose of this thesis is to validate that the Network Manager product of ABB has implemented CGMES properly. Power flow calculations are performed based on ENTSO-E’s test networks and the solutions obtained are compared with the standard results as well as the results from Power Factory (a power system analysis tool from DIgSILENT that has already passed the conformity assessment successfully).  The comparison results are analyzed thus to identify causes of any variation from the standard power flow solutions and to give suggestions for future development of Network Manager.
5

Les interconnexions électriques entre la France et ses voisins européens depuis 1970 : un vecteur méconnu de l'intégration européenne

Perrine, Christelle 12 1900 (has links)
Les ouvrages de transport d’électricité ont d’abord été pensés un par un, reliant un excédent de production à un besoin de consommation. Ils ont ainsi parfois très naturellement et dès l’origine traversé les frontières des États pour répondre à leur raison d’être. Les secteurs électriques se structurant fortement lorsque le virage électrique fut pris, les interconnexions entre pays furent conçues par les techniciens comme une mesure élémentaire de sûreté et d’équilibre de ce produit atypique qu’est l’électricité. En France plus particulièrement, lorsque la production électronucléaire se développa à partir des années 1970, ces interconnexions devinrent petit à petit sources de revenus pour l’entreprise nationale, et d’équilibre pour la balance commerciale nationale. L’intérêt grandissant porté au secteur électrique par les institutions européennes à la fin des années 1990 vient ébranler les acteurs économiques géographiques verticaux, et rebat les cartes des enjeux à adresser à une maille plus large que l’État nation. Dans ces transformations successives, les interconnexions aux frontières, et particulièrement aux frontières françaises, jouent ainsi un rôle tout à fait spécifique et de plus en plus structurant pour les économies ouvertes des pays européens. Les réseaux de transport électriques continuent ainsi une mutation entamée dans les années 1970 qui les a conduits de la condition de mal nécessaire à celle de vecteurs indispensables de transformation des économies européennes. L’objet de ce mémoire est d’illustrer la très grande capacité d’adaptation de ces organes industriels, économiques, sociétaux et politiques, dont on pourrait faussement penser qu’ils sont immobilisés par leur nature capitalistique, à travers les enjeux portés par les interconnexions aux frontières françaises. Les sources sont à la fois issues de données des opérateurs techniques, de la documentation – encore peu fréquente – sur ces sujets, ainsi que des statistiques officielles du ministère français. Cette capacité d’innovation et de développement de « couches de services » permet aujourd’hui aux grands réseaux de transport de traverser les époques et la variabilité des orientations de leurs environnements, durablement. / Transmission networks were first thought one by one, connecting a production surplus to a consumer need. They thus sometimes very naturally and from the outset crossed state boundaries to suit their purpose. The electrical sector reinforced itself strongly as the electric turn was taken. The interconnections between countries were thought by technicians as a basic security measure and balance of this unusual product that is electricity. In France especially, where nuclear power generation developed from the 1970s, these interconnections gradually became a source of revenue for the national company, and furnished surplus for the national trade balance. The growing interest in the electric power sector by the European institutions in the late 1990s challenged the vertical geographical economic players and shifted the stakes to a framework wider than the nation state. In these successive transformations, cross-border interconnections, especially across the French borders, play a specific and increasingly structuring rôle for open economies of European countries. The electrical transmission networks continue a transition that began in the 1970s, and took them from being a necessary evil to the status of essential factors of the European economies. The purpose of this thesis is to illustrate the wide adaptability of these industrial, economic, societal and political bodies, apparently immobilized by their capital-intensive nature. It does so by way of issues relating to interconnections at the French borders. Sources are technical data from operators, literature – although rare - on these topics, as well as official statistics from the French ministry. This strong capacity for innovation and development of "service layers " now allows major transportation networks to endure even as their environment changes.
6

Managing Mobility for Distributed Smart Cities Services

LUZURIAGA QUICHIMBO, JORGE ELOY 07 July 2017 (has links)
The IoT refers to the idea of internetworking physical devices, vehicles, buildings, and any other item embedded with the appropriate electronics, software, sensors, actuators, and network connectivity to allows them to interchange data and to provide highly effective new services. In this thesis we focus on the communications issues of the IoT in relation to mobility and we provide different solutions to alleviate the impact of these potential problems and to guarantee the information delivery in mobile scenarios. Our reference context is a Smart City where various mobile devices collaboratively participate, periodically sending information from their sensors. We assume that these services are located in platforms based in cloud infrastructures where the information is protected through the use of virtualisation ensuring their security and privacy. This thesis is structured into seven chapters. We first detail our objectives and identify the current problems we intend to address. Next, we provide a thorough review of the state of the art of all the areas involved in our work, highlighting how we improved the existing solutions with our research. The overall approach of the solutions we propose in this thesis use prototypes that encompasses and integrates different technologies and standards in a small infrastructure, using real devices in real scenarios with two of the most commonly used networks around the world: WiFi and 802.15.4 to efficiently solve the problems we originally identified. We focussed on protocols based on a producer/consumer paradigm, namely AMQP and particularly MQTT. We observed the behaviour of these protocols using in lab experiments and in external environments, using a mesh wireless network as the backbone network. Various issues raised by mobility were taken into consideration, and thus, we repeated the tests with different messages sizes and different inter-message periodicity, in order to model different possible applications. We also present a model for dimensioning the number of sources for mobile nodes and calculating the number of buffers required in the mobile node as a function of the number of sources and the size of the messages. We included a mechanism for avoiding data loss based on intermediate buffering adapted to the MQTT protocol that, in conjunction with the use of an alternative to the Network Manager in certain contexts, improves the connection establishment for wireless mobile clients. We also performed a detailed study of the jitter behaviour of a mobile node when transmitting messages with this proposal while moving through a real outdoor scenario. To emulate simple IoT networks we used the Cooja simulator to study and determine the effects on the probability of delivering messages when both publishers and subscribers were added to different scenarios. Finally we present an approach that combines the MQTT protocol with DTN which we specifically designed for constrained environments and guarantees that important information will never be lost. The advantage of our proposed solutions is that they make an IoT system more resilient to changes in the point of attachment of the mobile devices in an IoT network without requiring IoT application & service developers to explicitly consider this issue. Moreover, our solutions do not require additional support from the network through protocols such as MobileIP or LISP. We close the thesis by providing some conclusions, and identifying future lines of work which we unable to address here. / Internet de las cosas (IoT) se refiere a la idea de interconectar sensores, actuadores, dispositivos físicos, vehículos, edificios y cualquier elemento dotado de la electrónica, así como del software y de la conectividad de red que los hace capaces de intercambiar datos para proporcionar servicios altamente efectivos. En esta tesis nos centramos en temas relacionados con la comunicación de sistemas IoT, específicamente en situaciones de movilidad y en los problemas que esto conlleva. Con este fin ofrecemos diferentes soluciones que alivian su impacto y garantizan la entrega de información en estas situaciones. El contexto de referencia es una ciudad inteligente donde varios dispositivos móviles participan de forma colaborativa enviando periódicamente información desde sus sensores hacia servicios ubicados en plataformas en la nube (cloud computing) donde mediante el uso de virtualización, la información está protegida garantizando su seguridad y privacidad. Las soluciones propuestas en esta tesis se enfocan en probar sobre una pequeña infraestructura un prototipo que abarca e integra diferentes tecnologías y estándares para resolver eficientemente los problemas previamente identificados. Hemos enfocado nuestro esfuerzo en el uso de dispositivos sobre escenarios reales con dos de las redes más extendidas en todo el mundo: WiFi y enlaces 802.15.4. Nos enfocamos en protocolos que ofrecen el paradigma productor/consumidor como el protocolo avanzado de colas de mensajes (AMQP) y particularmente el protocolo de transporte de mensajes telemétricos (MQTT), observamos su comportamiento a través de experimentos en laboratorio y en pruebas al aire libre, repitiendo las pruebas con diferentes tamaños de mensajes y diferente periodicidad entre mensajes. Para modelar las diferentes posibles aplicaciones de la propuesta, se tomaron en consideración varias cuestiones planteadas por la movilidad, resultando en un modelo para dimensionar eficientemente el número de fuentes para un nodo móvil y para calcular el tamaño requerido del buffer, en función del número de fuentes y del tamaño de los mensajes. Proponemos un mecanismo adaptado al protocolo MQTT que evita la pérdida de datos en clientes móviles, basado en un buffer intermedio entre la producción y publicación de mensajes que, en conjunto con el uso de una alternativa al gestor de conexiones inalámbricas "Network Manager", en ciertos contextos mejora el establecimiento de las conexiones. Para la evaluación de esta propuesta se presenta un estudio detallado de un nodo móvil que se mueve en un escenario real al aire libre, donde estudiamos el comportamiento del jitter y la transmisión de mensajes. Además, hemos utilizado emuladores de redes IoT para estudiar y determinar los efectos sobre la probabilidad de entrega de mensajes, cuando se agregan tanto publicadores como suscriptores a diferentes escenarios. Finalmente, se presenta una solución totalmente orientada a entornos con dispositivos de recursos limitados que combina los protocolos MQTT con redes tolerantes a retardos (DTN) para garantizar la entrega de información. La ventaja de las soluciones que proponemos reside en el hecho de que los sistemas IoT se vuelven resilientes a la movilidad y a los cambios de punto de acceso, permitiendo así que los desarrolladores creen fácilmente aplicaciones y servicios IoT evitando considerar estos problema. Otra ventaja de nuestras soluciones es que no necesitan soporte adicional de la red como sucede con protocolos como MobileIP o el protocolo que separa el identificador del localizador (LISP). Se destaca cómo hemos mejorado las soluciones existentes hasta el momento de la escritura de esta disertación, y se identifican futuras líneas de actuación que no han sido contempladas. / Internet de les coses (IoT) es refereix a la idea d'interconnectar sensors, actuadors, dispositius físics, vehicles, edificis i qualsevol element dotat de l'electrònica, així com del programari i de la connectivitat de xarxa que els fa capaces d'intercanviar dades per proporcionar serveis altament efectius. En aquesta tesi ens centrem en temes relacionats amb la comunicació de sistemes IoT, específicament en situacions de mobilitat i en els problemes que això comporta. A aquest efecte oferim diferents solucions que alleugeren el seu impacte i garanteixen el lliurament d'informació en aquestes situacions. El context de referència és una ciutat intel·ligent on diversos dispositius mòbils participen de forma col·laborativa enviant periòdicament informació des dels seus sensors cap a serveis situats en plataformes en el núvol (cloud computing) on mitjançant l'ús de virtualització, la informació està protegida garantint la seva seguretat i privadesa. Les solucions proposades en aquesta tesi s'enfoquen a provar sobre una xicoteta infraestructura un prototip que abasta i integra diferents tecnologies i estàndards per a resoldre eficientment els problemes prèviament identificats. Hem enfocat el nostre esforç en l'ús de dispositius sobre escenaris reals amb dos de les xarxes més esteses a tot el món: WiFi i enllaços 802.15.4. Ens enfoquem en protocols que ofereixen el paradigma productor/consumidor com el protocol avançat de cues de missatges (AMQP) i particularment el protocol de transport de missatges telemètrics (MQTT), observem el seu comportament a través d'experiments en laboratori i en proves a l'aire lliure, repetint les proves amb diferents grandàries de missatges i diferent periodicitat entre missatges. Per a modelar les diferents possibles aplicacions de la proposta, es van prendre en consideració diverses qüestions plantejades per la mobilitat, resultant en un model per a dimensionar eficientment el nombre de fonts per a un node mòbil i per a calcular la grandària requerida del buffer, en funció del nombre de fonts i de la grandària dels missatges. Proposem un mecanisme adaptat al protocol MQTT que evita la pèrdua de dades per a clients mòbils, basat en un buffer intermedi entre la producció i publicació de missatges que en conjunt amb l'ús d'una alternativa al gestor de connexions sense fils "Network Manager'', en certs contextos millora l'establiment de les connexions. Per a l'avaluació d'aquesta proposta es presenta un estudi detallat d'un node mòbil que es mou en un escenari real a l'aire lliure, on estudiem el comportament del jitter i la transmissió de missatges. A més, hem utilitzat emuladors de xarxes IoT per a estudiar i determinar els efectes sobre la probabilitat de lliurament de missatges, quan s'agreguen tant publicadors com subscriptors a diferents escenaris. Finalment, es presenta una solució totalment orientada a entorns amb dispositius de recursos limitats que combina els protocols MQTT amb xarxes tolerants a retards (DTN) per a garantir el lliurament d'informació. L'avantatge de les solucions que proposem resideix en el fet que els sistemes IoT es tornen resilients a la mobilitat i als canvis de punt d'accés, permetent així que els desenvolupadors creuen fàcilment aplicacions i serveis IoT evitant considerar aquests problema. Un altre avantatge de les nostres solucions és que no necessiten suport addicional de la xarxa com succeeix amb protocols com MobileIP o el protocol que separa l'identificador del localitzador (LISP). Es destaca com hem millorat les solucions existents fins al moment de l'escriptura d'aquesta dissertació, i s'identifican futures línies d'actuació que no han sigut contemplades. / Luzuriaga Quichimbo, JE. (2017). Managing Mobility for Distributed Smart Cities Services [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/84744 / TESIS

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