This thesis presents the research carried out to investigate and achieve highly reliable and accurate navigation system of guidance for visually impaired pedestrians. The main aim with this PhD project has been to identify the limits and insufficiencies in utilising Network Real-Time Kinematic Global Navigation Satellite Systems (NRTK GNSS) and its augmentation techniques within the frame of pedestrian applications in a variety of environments and circumstances. Moreover, the system can be used in many other applications, including unmanned vehicles, military applications, police, etc. NRTK GNSS positioning is considered to be a superior solution in comparison to the conventional standalone Global Positioning System (GPS) technique whose accuracy is highly affected by the distance dependent errors such as satellite orbital and atmospheric biases. Nevertheless, NRTK GNSS positioning is particularly constrained by wireless data link coverage, delays of correction and transmission and completeness, GPS and GLONASS signal availability, etc., which could downgrade the positioning quality of the NRTK results. This research is based on the dual frequency NRTK GNSS (GPS and GLONASS). Additionally, it is incorporated into several positioning and communication methods responsible for data correction while providing the position solutions, in which all identified contextual factors and application requirements are accounted. The positioning model operates through client-server based architecture consisted of a Navigation Service Centre (NSC) and a Mobile Navigation Unit (MNU). Hybrid functional approaches were consisting of several processing procedures allowing the positioning model to operate in position determination modes. NRTK GNSS and augmentation service is used if enough navigation information was available at the MNU using its local positioning device (GPS/GLONASS receiver).The positioning model at MNU was experimentally evaluated and centimetric accuracy was generally attained during both static and kinematic tests in various environments (urban, suburban and rural). This high accuracy was merely affected by some level of unavailability mainly caused by GPS and GLONASS signal blockage. Additionally, the influence of the number of satellites in view, dilution of precision (DOP) and age corrections (AoC) over the accuracy and stability of the NRTK GNSS solution was also investigated during this research and presented in the thesis. This positioning performance has outperformed the existing GPS service. In addition, utilising a simulation evaluation facility the positioning model at MNU performance was quantified with reference to a hybrid positioning service that will be offered by future Galileo Open Service (OS) along with GPS. However, a significant difference in terms of the service availability for the advantage of the hybrid system was experienced in all remaining scenarios and environments more especially the urban areas due to surrounding obstacles and conditions. As an outcome of this research a new and precise positioning model was proposed. The adaptive framework is understood as approaching an integration of the available positioning technology into the context of surrounding wireless communication for a maintainable performance. The positioning model has the capability of delivering indeed accurate, precise and consistent position solutions, and thus is fulfilling the requirements of visually impaired people navigation application, as identified in the adaptive framework.

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Avanços nas tecnologias de comunicação e processamento de sinais além de mudar a forma de como realizar negócios em todo o mundo, têm motivado o surgimento de serviços e aplicações multimídia na Internet de forma crescente. Como conseqüência, é possível conceber, desenvolver, implantar e operar serviços de distribuição de vídeo digital na Internet, tanto na abordagem sob-demanda quanto ao vivo. Com o aumento das aplicações multimídia na rede, torna-se cada vez mais complexo e necessário definir um modelo eficiente que possa realizar o gerenciamento efetivo e integrado de todos os elementos e serviços que compõe um sistema computacional. Pensando assim, este trabalho propõe uma arquitetura de gerenciamento baseado em políticas aplicada à distribuição de conteúdo multimídia com controle de QoS (Quality of Service) em redes de sobreposição (overlay). A arquitetura é baseada nos padrões de gerenciamento por políticas definida pela IETF (Internet Engineering Task Force) que, através de informações contextuais (rede e clientes) administra os serviços disponíveis no sistema. Faz uso dos requisitos de QoS providos pela rede de distribuição e os compara com os requisitos mínimos exigidos pelos perfis das aplicações previamente mapeados em regras de políticas. Dessa forma é possível controlar e administrar os elementos e serviços do sistema, afim de melhor distribuir recursos aos usuários deste sistema. / Advances in communication technologies and signal processing have not only changed the way business is conducted around the world, but have also driven the development of services and multimedia applications on the Internet. As a result, it is possible to design, develop, deploy and operate services for digital video distribution on the Internet, both according to an on-demand approach and live. Because of the increase in multimedia applications on the network, it has become increasingly more complex and necessary to define an efficient architecture that can achieve the effective and integrated management of all the elements and services that compose a computer system. With this in mind, this study proposes developing a robust and efficient architecture based on IETF (Internet Engineering Task Force) policy management standards applied to multimedia distribution content with QoS (Quality of Service) control in Overlay Networks. This architecture makes use of QoS requirements provided by the distribution network and compares them to the minimum requirements demanded by each type of application previously mapped in the policy rules. This system makes it possible to control and manage system information and services and also to distribute resources to system users better.

Avanços nas tecnologias de comunicação e processamento de sinais além de mudar a forma de como realizar negócios em todo o mundo, têm motivado o surgimento de serviços e aplicações multimídia na Internet de forma crescente. Como conseqüência, é possível conceber, desenvolver, implantar e operar serviços de distribuição de vídeo digital na Internet, tanto na abordagem sob-demanda quanto ao vivo. Com o aumento das aplicações multimídia na rede, torna-se cada vez mais complexo e necessário definir um modelo eficiente que possa realizar o gerenciamento efetivo e integrado de todos os elementos e serviços que compõe um sistema computacional. Pensando assim, este trabalho propõe uma arquitetura de gerenciamento baseado em políticas aplicada à distribuição de conteúdo multimídia com controle de QoS (Quality of Service) em redes de sobreposição (overlay). A arquitetura é baseada nos padrões de gerenciamento por políticas definida pela IETF (Internet Engineering Task Force) que, através de informações contextuais (rede e clientes) administra os serviços disponíveis no sistema. Faz uso dos requisitos de QoS providos pela rede de distribuição e os compara com os requisitos mínimos exigidos pelos perfis das aplicações previamente mapeados em regras de políticas. Dessa forma é possível controlar e administrar os elementos e serviços do sistema, afim de melhor distribuir recursos aos usuários deste sistema. / Advances in communication technologies and signal processing have not only changed the way business is conducted around the world, but have also driven the development of services and multimedia applications on the Internet. As a result, it is possible to design, develop, deploy and operate services for digital video distribution on the Internet, both according to an on-demand approach and live. Because of the increase in multimedia applications on the network, it has become increasingly more complex and necessary to define an efficient architecture that can achieve the effective and integrated management of all the elements and services that compose a computer system. With this in mind, this study proposes developing a robust and efficient architecture based on IETF (Internet Engineering Task Force) policy management standards applied to multimedia distribution content with QoS (Quality of Service) control in Overlay Networks. This architecture makes use of QoS requirements provided by the distribution network and compares them to the minimum requirements demanded by each type of application previously mapped in the policy rules. This system makes it possible to control and manage system information and services and also to distribute resources to system users better.

Les cyber-attaques pourraient engendrer des pertes qui sont de plus en plus importantes pour les utilisateurs finaux et les fournisseurs de service. Ces attaques sont, en outre, élevées par une myriade des ressources infectées et comptent surtout sur les réseaux pour être contrôlées, se propager ou endommager. Face à ces risques, il y a un besoin essentiel qui se manifeste dans la réponse à ces nombreuses attaques par des stratégies de défense efficaces. Malgré les multitudes efforts dévouées pour mettre en œuvre des techniques de défense complètes afin de se protéger contre les attaques réseaux; les approches proposées n’ont pas parvenus à satisfaire toutes les exigences. Les stratégies de défense impliquent un processus de détection complété par des actions de mitigation. Parallèlement à l’importance accordée à la conception des stratégies de détection, il est essentiel de fermer la boucle de sécurité avec des techniques efficaces permettant d’atténuer les impacts des différentes attaques. Dans cette thèse, nous proposons une technique pour réagir aux attaques qui abusent les ressources du réseau, par exemple, DDoS, botnet, distribution des vers, etc. La technique proposée s’appuie sur des approches de gestion du trafic et utilise le standard Multiprotocol Label Switching (MPLS) pour gérer le trafic diagnostiqué comme abusant du réseau, tout en invoquant les processus de détection. Les objectifs de notre technique peuvent être résumés comme suit: d’une part, fournir les moyens — par la qualité de service et schémas de routage — à séparer les flux suspects des légitimes, et d’autre part de prendre le contrôle des flux suspects. Nous bénéficions de l’extension du MPLS au niveau d’inter-domaine pour permettre une coopération entre les fournisseurs, permettant par suite la construction d’un mécanisme de défense à grande échelle. Nous développons un système afin de compléter les aspects de gestion de la technique proposée. Ce système effectue plusieurs tâches telles que l’extraction de données d’alerte, l’adaptation de la stratégie et la configuration des équipements. Nous modélisons le système en utilisant une approche de regroupement et un langage de politiques de sécurité afin de gérer de manière cohérente et automatique le contexte et l’environnement dans lequel la technique de mitigation est exécutée. Enfin, nous montrons l’applicabilité de la technique et du système à travers des différentes simulations tout en évaluant la qualité de service dans des réseaux MPLS. L’application de la technique a démontré son efficacité dans non seulement la mitigation des impacts des attaques mais aussi dans l’offre des avantages financiers aux acteurs de la chaîne de sécurité, à savoir les fournisseurs de service / Cyber attacks cause considerable losses not only for end-users but also service providers. They are fostered by myriad of infected resources and mostly rely on network resources for whether propagating, controlling or damaging. There is an essential need to address these numerous attacks by efficient defence strategies. Researchers have dedicated large resources without reaching a comprehensive method to protect from network attacks. Defence strategies involve first a detection process, completed by mitigation actions. Research on detection is more active than on mitigation. Yet, it is crucial to close the security loop with efficient technique to mitigate counter attacks and their effects. In this thesis, we propose a novel technique to react to attacks that misuse network resources, e.g., DDoS, Botnet, worm spreading, etc. Our technique is built upon network traffic management techniques. We use the Multiprotocol Label Switching (MPLS) technology to manage the traffic diagnosed to be part of a network misuse by detection processes. The goals of our technique can be summarized as follows: first to provide the means — via QoS and routing schemes — to segregate the suspicious flows from the legitimate traffic; and second, to take control over suspicious flows. We profit from the enhancement on the inter-domain MPLS to permit a cooperation among providers building a large-scale defence mechanism. We develop a system to complete the management aspects of the proposed technique. This system performs tasks such as alert data extraction, strategy adaptation and equipments configurations. We model the system using a clustering method and a policy language in order to consistently and automatically manage the mitigation context and environment in which the proposed technique is running. Finally, we show the applicability of the technique and the system through simulation. We evaluate and analyse the QoS and financial impacts inside MPLS networks. The application of the technique demonstrates its effectiveness and reliability in not only alleviating attacks but also providing financial benefits for the different players in the mitigation chain, i.e., service providers

[pt] Este trabalho descreve uma ferramenta de simulação esenvolvida para analisar o gerenciamento dos recursos de rádio e parâmetros de QoS (Quality of Service) dos sistemas móveis celulares. Pela natureza de um sistema real de telefonia celular, é extremamente difícil que as variáveis de saída de um simulador sejam derivadas de um conjunto real de funções. Isso se deve à grande quantidade de parâmetros que devem ser considerados no comportamento da mobilidade, nas condições de tráfego, nas características geográficas e morfológicas da região, na modelagem complexa do canal rádio propagação móvel, entre outras. Visando a desenvolver uma ferramenta de simulação próxima da realidade, adotam-se modelos de propagação, de mobilidade e de tráfego que sejam satisfatoriamente adequados ao caso real. A contribuição deste trabalho é oferecer uma ferramenta de simulação flexível, aqui adequada ao sistema norte-americano TDMA (IS-136), que possibilite ao usuário, além de analisar a capacidade do sistema,também avaliar novos algoritmos de controle de potência, novas estratégias de handoff, novos esquemas de alocação de canal e modelos de propagação. A ferramenta será validada seguindo o processo de um projeto real de telefonia celular e ao final, será aplicada a um sistema celular com sobreposição macro-células/micro-células, analisando-se algumas estratégias de handoff dedicadas a esses sistemas. / [en] This work describes a simulation tool, which was developed to analyze the radio resources and QoS (Quality of Service) parameters in mobile systems. Because of the complex characteristics of an actual cellular network, it is extremely difficult having the outputs of the simulator being derived from a real set of functions, due to the large amount of parameters that have to be considered such as the mobility behavior, the traffic conditions, the geographic and morphologic characteristics of the region, the complex modeling of mobile radio propagation channel, and so on. In order to develop a simulation tool as near as possible to the reality, models that are satisfactorily adequate to the real case have been considered. So, propagation, mobility and traffic models were adapted from the IS-136 American system. The contribution of this work is to offer a flexible simulation tool that allows the user, in addition to analyzing the capacity of the system, to evaluate new algorithms of power control, handoff strategies, channel allocation schemes and propagation models. The tool will be validated following the process of a real project of cellular telephony and at the end, it will be applied to a cellular system with overlapped macro- cells/micro-cells, and some handoff strategies dedicated to those systems will be analyzed.

[pt] Com o advento dos sistemas celulares de segunda e terceira gerações é esperado que as operadoras se vejam obrigadas a enfrentar um aumento dramático na carga de sinalização que trafega sobre a parte fixa da rede móvel. Apesar disso, são raros os provedores de serviços de comunicações móveis que possuem atualmente a capacidade de prever com relativa precisão o montante desse aumento. Este trabalho apresenta as etapas do desenvolvimento de uma ferramenta de simulação para análise de desempenho de redes de comunicação móvel celular com base na carga de sinalização gerada pelos procedimentos que a mantém em operação. A plataforma de simulação inclui um modelo de mobilidade e teletráfego para caracterizar o processo de geração dos cenários típicos de uma rede móvel celular e um modelo de retardos para representação da rede de sinalização. Ao final do estudo,são apresentados exemplos de aplicação da ferramenta na obtenção de resultados sobre gerência de status, gerência de localização, avaliação da carga de sinalização,dimensionamento da rede de sinalização e análise de desempenho para diferentes configurações de rede. / [en] The advent of second and third generation cellular systems make cellular operators face dramatic increase in the signaling traffic over the fixed part of the mobile network. In spite of this, rare mobile communications service providers are able to forecast the above mention increase and quantify it with reasonable precision. This work describes the development process of a simulation tool for performance analysis of cellular mobile network based on the signaling load generated by the procedures that keeps it working. The simulation platform inlcudes a mobility and teletraffic model to describe the generation process of cellular mobile networks tipical scenarios and a delay model to represent the signaling network. At the end, examples showing the application of the simulation tool to obtain results about status and location management, signaling load evaluation, signaling network planning and performance analysis for different network configurations are presented.