O objetivo deste trabalho foi o desenvolvimento de um sistema de aquisição, processamento e armazenamento de sinais adquiridos de um arranjo de sensores embasado na norma IEE 1451.4 , resultando num sistema de sensores plug&play. O sistema de aquisição de sinais proposto permitirá monitorar diversos tipos de sensores para as mais variadas aplicações nos campos da área biomédica, automação industrial, monitoramento ambiental dentre outras. O sistema de aquisição proposto é constituído por um módulo chamado de STIM (\"Smart Transducer Interface Module\") cujo elemento principal é um microcontrolador com arquitetura RISC de propósito geral, [Johnson 2001]. O módulo STIM é conectado a um computador via interface serial (RS232) para transmitir dados dos sensores e receber comandos de controle. Os sensores analógicos aqui utilizados foram adequados ao sistema utilizando-se da técnica chamada MMI (Mixed Mode Interface) em conformidade com a norma IEEE 1451.4, transformando os sensores em um sistema plug&play. O módulo STIM é monitorado por um software residente no computador PC permitindo que os dados adquiridos dos sensores sejam visualizados e gravados em arquivo para posterior estudo. A obtenção de um sistema de sensores plug&play foi desenvolvida utilizando a estrutura TEDS (Transducer Electronic Data Sheet) gravada em uma memória serial não volátil. O TEDS possui informações e especificações técnicas do transdutor de acordo com um modelo (template) conforme a norma IEEE 1451.4, tal que, quando um sensor é conectado, o sistema exibe na tela do computador informações tais como, o canal conectado, o tipo de sensor, o modelo, número de série, nome do fabricante e a data de fabricação. Neste trabalho foram implementados três módulos MMI utilizando três sensores analógicos, temperatura, pressão e pH. Estes três módulos MMI possibilitaram realizar medidas comparativas que fundamentam o funcionamento do sistema. / The purpose of this work was the development of an acquisition, processing and storage system of a signal from an arrangement of sensors based on IEEE 1451.4 standard, resulting in a plug&play sensors system. The acquisition signal system proposed will permit to monitoring several kinds of sensors for a variety application in the fields of biomedical, industrial automation and environment and many others. The system proposed is formed by a module, called STIM (Smart Transducer Interface Module) that the main element is a general purpose microcontroller with RISC architecture, [Johnson 2001]. The STIM module is connected with a PC computer by serial interface (RS232) to transmit the data from sensors and to receive the control commands. The analog sensors here utilized was adapted to the system utilizing a technique called MMI (Mixed Mode Interface) attending the IEEE 1451.4 standard, transforming the sensors in a plug&play system. The STIM module is assisted by a PC via resident software that will permit the acquired data viewing and recording in file for further study. The plug&play sensors system was developed utilize the TEDS structure (Transducer Electronic Data Sheet) recorded in a non volatile serial memory. The TEDS has specifications and technical information from the transducer according a model (template) in conformity of IEEE 1451.4 standard , as well, when a sensor is connected , the system shows information on the PC screen, as the connected channel , the kind of the sensor , the model , serial number, producer name and produced date. In this work three MMI modules were implemented utilizing three analog sensors; temperature, pressure and pH. These three MMI modules let\'s realize comparative measurements that grounds the system operation.

O projeto de malhas de aterramento requer o cálculo da resistência de aterramento e dos potenciais na superfície do solo. Quando o método das imagens é utilizado para este cálculo o modelo típico do solo é uma estratificação horizontal em 2 camadas. A extensão do método das imagens para solos com múltiplas camadas horizontais apresenta problemas numéricos importantes, de forma que a técnica de imagens complexas foi utilizada para permitir este cálculo, porém restringindo a posição dos eletrodos à primeira camada. Este trabalho objetiva a aplicação do método de imagens complexas a eletrodos situados em qualquer camada de solos com estratificação horizontal, deduzindo as funções kernel para posições arbitrárias da fonte e do objeto e determinando os resíduos e pólos das imagens utilizando a decomposição em autovalores e autovetores. Foi desenvolvido um programa que calcula a resistência de aterramento e os potenciais na superfície do solo para solos com até 4 camadas. Foram realizadas comparações com outros trabalhos publicados e os resultados obtidos permitem validar o uso do programa para esta aplicação. / Grounding grid design requires both ground resistance and surface potential. Traditional method of images restricts this calculation to two layer soils. Complex image method allows calculation of both resistance values and potentials at the soil surface, in multilayer soils with horizontal stratification, without grounding grid position limitation. This work presents a complete methodology for calculation of safety aspects of grounding grid design, validating results by comparison with published previous work.

Made available in DSpace on 2016-04-04T18:31:32Z (GMT). No. of bitstreams: 1 Aturo Jose Fenile Peris.pdf: 4348655 bytes, checksum: 34479e7af136c0f06a1b46d21b30c1c4 (MD5) Previous issue date: 2012-06-22 / The design of the IEEE 802.11 standard allows, in certain situations, competition for access to the transmission medium results in an anomaly. As a result of this anomaly, mobile stations that should achieve high rates of transmission are impaired and don t get those rates. The consequence is the transmission capacity low utilization of the wireless system and the natural increasing of the time mobile stations stays on (and consuming energy); because of this, the increase in energy consumption is another effect of this anomaly. From this scenario, one way to deal with this anomaly is to have a better utilization of the wireless transmission medium. In this context, this work proposes a bench for studies of flow control in IEEE 802.11; this bench allows the management of bandwidth and the collection of traffic statistics from users sessions connected to the wireless network. As a resulting study from the bench using, there is a proposal to mitigate the anomaly through the user traffic management. The results indicate that the controlling the traffic from users who are in poor wireless transmission may produce a better utilization of transmission capacity of an IEEE 802.11 access point. / A concep??o do padr?o IEEE 802.11 permite que, em determinadas situa??es, a competi??o pelo acesso ao meio de transmiss?o resulte em uma anomalia. Como resultado dessa anomalia, esta??es m?veis que deveriam conseguir altas taxas de transmiss?o s?o prejudicadas e acabam por n?o conseguir essas taxas. A consequ?ncia ? o baixo aproveitamento da capacidade de transmiss?o do sistema sem fio e o natural aumento do tempo em que as esta??es m?veis permanecem ligadas e consumindo energia; por conta disso, o aumento no consumo de energia ? outro efeito dessa anomalia. A partir desse cen?rio, uma forma de combater essa anomalia ? a melhoria da utiliza??o do meio de transmiss?o sem fio. Nesse contexto, este trabalho apresenta uma proposta de bancada para estudos de controle de vaz?o em redes IEEE 802.11; essa bancada permite gerenciar a largura de banda e coletar dados estat?sticos relativos ao tr?fego das sess?es dos usu?rios conectados ? rede sem fio. Como estudo resultante da utiliza??o da bancada, h? uma proposta de mitiga??o da anomalia por meio da gest?o do tr?fego dos usu?rios. Os resultados indicam que o controle do tr?fego de usu?rios que est?o em m?s condi??es de transmiss?o sem fio pode melhorar o aproveitamento da capacidade de transmiss?o de um ponto de acesso IEEE 802.11.

A busca constante por soluções mais eficientes, tanto no âmbito técnico como econômico, tem levado à crescente adoção de sistemas de automação baseados em redes de controle e transdutores inteligentes. A fragmentação desse mercado, no entanto, decorrente da proliferação de inúmeros protocolos e especificações para as redes de controle, impõe restrições e entraves ao desenvolvimento dos transdutores e dos sistemas de automação. A família de normas IEEE 1451 procura atenuar esse problema propondo interfaces padronizadas entre os transdutores e as redes, permitindo separar o projeto do transdutor da escolha da rede de controle. Neste trabalho foi desenvolvido um transdutor inteligente baseado na norma IEEE 1451.2 (STIM) e sua interface para a rede de controle LonWorks (NCAP). Através do desenvolvimento e avaliação dos protótipos foi verificada a aplicabilidade da norma e dos conceitos gerais da IEEE 1451, comprovando ainda seu uso em uma rede para a qual, no presente momento, não se tem conhecimento de solução similar. Constatou-se também que um transdutor inteligente baseado na IEEE 1451.2 pode ser desenvolvido com ferramentas e componentes comerciais de fácil acesso e baixo custo, e que é possível agregar os benefícios da IEEE 1451 às qualidades presentes nas redes LonWorks. Verificou-se ainda que a aceitação da IEEE 1451 no mercado é ainda incipiente, sendo imprescindível a publicação das demais normas que compõe a família para facilitar e incentivar sua adoção e disseminação. / The need for more efficient and cost-effective solutions in the control and automation market drives the increasing demand for systems based on control networks and smart transducers. However, the fragmented nature of the control network market hinders the development of solutions based on such technologies. The IEEE 1451 family of standards tries to solve this problem by specifying a common set of interfaces between the transducers and the control networks, isolating the transducer\'s project from the choice of networks. In this work, a smart transducer based on the IEEE 1451.2 standard (STIM) and its interface module to a LonWorks network (NCAP) were developed. Through the development and evaluation of the prototypes, the applicability of the standard and the concepts involved in the IEEE 1451 were verified. It was confirmed that a smart transducer based on the IEEE 1451.2 standard can be developed with low-cost, off-the-shelf components and software tools, and that it is possible to combine the benefits of the IEEE 1451 with the qualities of the LonWorks system. It was also perceived that the acceptance of the IEEE 1451 in the market is quite low, and that the release of the remaining standards that make up the IEEE 1451 family is essential for its success.

Le développement du transport partout dans le monde a fourni un grand nombre d'avantages pour de nombreux aspects de la vie humaine. Les systèmes de transport intelligents (ITS) sont des applications avancées qui visent à rendre les réseaux de transport plus sûrs, plus pratiques et plus intelligents. Selon leurs usages, ils peuvent être classés en deux types d'applications ITS, qui sont des applications de sûreté et des applications non-sûreté. Le réseau de véhicules ad hoc (VANET) est un élément clé des systèmes ITS, car il permet la communication entre les unités de transport. Ces communications prennent en charge différentes applications ITS avec différentes propriétés. Parmi les deux types d'applications, nous nous intéressons aux applications de sûreté qui ont des contraintes de qualité de service et des contraintes de sécurité plus strictes. Selon le scénario considéré et l'application de sûreté donnée, les informations échangées entre les véhicules doivent être diffusé localement dans une communication à un seul saut et / ou également notifiées aux véhicules à large dimension. L'objectif principal de cette thèse est d'améliorer les performances des applications de sûreté en termes de qualité de service et de sécurité, à la fois dans une communication à un saut et dans une communication multi-sauts. Nous nous intéressons à la fiabilité, la connectivité et le déni de service (DoS). Nous étudions et proposons des solutions techniques provenant de couches inférieures (Physique, Liaison et Réseaux) qui jouent un rôle fondamental dans l'atténuation des défis créés par la nature de l'environnement des véhicules. Tout d'abord, nous introduisons une nouvelle méthode efficace pour fiabiliser la radiodiffusion. Dans notre système, les messages de sécurité sont rediffusés lorsque l'expéditeur est sollicité. Cela augmente le pourcentage de véhicules qui reçoivent les messages alors que le nombre de messages dupliqués reste limité. En second lieu, en tenant compte de la fragmentation du réseau, nous étudions des solutions qui permettent de pallier la déconnexion temporaire du réseau pour apporter l'information de sécurité aux destinataires. Basé sur les propriétés sociales des réseaux de véhicules, nous proposons un protocole de transfert basé sur des relations sociales pour relayer la communication entre les véhicules et des points d'intérêt qui fournissent des services de sécurité avec des contraintes de temps plus souples, telles que la recherche et le sauvetage. Troisièmement, nous étudions l'attaque de brouillage, une sorte d'attaques DoS, qui est cruciale pour les applications de sûreté et qui et facilement réalisable au niveau des couches inférieures. Nous modélisons l'attaque de brouillage afin d'étudier la dégradation causée par l'attaque sur les performances du réseau. La dégradation à un certain niveau dans les performances du réseau est une indication de présence d'attaques de brouillage dans le réseau; donc les résultats de cette analyse nous permettent de déterminer les seuils de performance du réseau pour distinguer entre les scénarios normaux et les scénarios attaqués. Toutefois, selon cette analyse, le procédé utilisant la dégradation comme une indication pour détecter une attaque de brouillage est impossible pour des applications temps réel. Par conséquent, nous proposons des nouvelles méthodes afin de détecter les attaques de brouillage temps réel. Nos méthodes permettent la détection en temps réel avec une grande précision, non seulement chez le moniteur central mais aussi au niveau de chaque véhicule. Par conséquent, les véhicules sont avertis sur l'attaque assez tôt pour récupérer la communication et réagir à ces attaques. / The development of transportation all over the world has been providing a lot of benefits for many aspects of human life. Intelligent Transportation Systems (ITS) are advanced applications that aim to make the transport networks safer, more convenient and smarter. According to their usages, they can be classified into two types of ITS applications, which are safety applications and non-safety applications. Vehicular ad hoc network (VANET) is a key component of ITS since it enables communications among transportation units. These communications support different ITS applications with various properties. Between two types of applications, we are interested in safety applications which have tighter quality and security constraints. Depending on an applied scenario of a given safety application, the exchanged information among vehicles must be broadcast locally within one-hop communication and/or also be notified to vehicles in large range. The main objective of this thesis is to improve the performance of safety applications in term of the quality of service and security, in both one-hop communication and multi-hop communication. We focus on reliability, connectivity and Denial of Services (DoS) attack. We study and propose technical solutions coming from lower layers (Physical, MAC and network layers) which play a fundamental role in mitigation to challenges created by the nature of the vehicular environment. Firstly, we introduce a reliable scheme to achieve the reliability for broadcasting. In our scheme, the safety messages are rebroadcast when the sender is solicited. This increases the percentage of vehicles receiving the messages while duplicated messages are limited. Secondly, with consideration of the fragmentation of the network, we study solutions that overcome the temporary disconnection in the network to bring the safety information to the recipients. Based on the social properties of vehicular networks, we propose a social-based forwarding protocol to support the communication between vehicles to points of interest that provide safety services with looser time constraints, such as search and rescue. Thirdly, we investigate jamming attack, a kind of DoS attacks, which is crucial for safety applications because of the adequate condition of the attack at the lower layers. We model jamming attack on broadcasting in order to study the degradation caused by the attack on network performance. The degradation at a certain level in network performance is an indication of a jamming attack presence in the network; therefore results from this analysis will allow us to determine network performance thresholds to distinguish between normal and attacked scenarios. However, according to our analysis, the method using the degradation as an indication to detect a jamming attack is not feasible for real-time applications. Hence, we propose methods to detect jamming attacks in real-time. Our methods allow real-time detection with high accuracy, not only at the central monitor but also at each vehicle. Therefore, vehicles are noticed about the attack soon enough to recover the communication and react to these attacks.

Vehicular Ad hoc Network (VANET) is a special kind of Mobile Ad hoc Network (MANET) and is a key enabling technology for Intelligent Transportation Systems (ITS). It plays an important role in the deployment of a large scale of both safety and non-safety applications. Among non-safety applications, an important and challenging area is the provision of information about roadside services advertisement and discovery. In this work, we adopted the beaconing strategy and opportunistic vehicular communications to address the problem of roadside services advertisement and discovery on the highways. Our approach offers several advantages over the traditional billboard method, e.g., low cost, targeting a large number of customers in a real time, more control over the advertisement campaign, dynamic content updating, and discovery of services far ahead of the business region. For advertising roadside services, we followed the push-based advertisement strategy and relied on Infrastructure-to-Vehicle (I2V) communications only. On the other hand, for discovering these services by the drivers, we used pull-based advertisement strategy and opportunistic Vehicle-to-Vehicle (V2V) communications. In order to contribute to the advertisement campaign, we used the store-carry-and-response mechanism. Our first contribution is the Extended Opportunistic Service Discovery Protocol (EOSDP). EOSDP implements and extends the original version of Opportunistic Service Discovery Protocol (OSDP) via simulation experiments. We used Simulation of Urban Mobility (SUMO), Objective Modular Network Testbed in C++ (OMNET++), and Vehicles in network simulation (Veins) simulators. Our second contribution is Service Advertisement Protocol (SADP). SADP is a lightweight beaconing-based services advertisement protocol for VANETs. It does not require the Internet connection for advertising the roadside services. Moreover, SADP modeling is based on VANETs standard protocols. The performance of SADP was evaluated in a congested highway scenario with varying speed of vehicles and under different broadcast frequencies. Our last contribution is Commercial Services Discovery Protocol (CSDP). Like the previous protocol, CSDP is a lightweight beaconing-based services discovery protocol for VANETs. CSDP is infrastructureless protocol which only depends on opportunistic V2V communications for roadside services discovery. The protocol was implemented in congested highway scenario and extensive set of simulation experiments were performed to evaluate its performance under different parameters, e.g., Query Interval (QI), Query Attempts (QA), and Time to Live (TTL). / Vehicular Ad hoc Network (VANET) é um tipo especial de Mobile Ad hoc Network (MANET) e é uma tecnologia chave para apoiar os Sistemas Inteligentes de Transporte (ITSs). Ela desempenha um papel importante na implantação em grande escala das aplicações do tipo safety e non-safety. Dentre as aplicações non-safety, uma área importante e desafiadora é descoberta e divulgação de informação sobre serviços. Neste trabalho, nós adotamos a estratégia de beaconing e as comunicações veiculares oportunistas para resolver o problema da descoberta e divulgação de serviços ao longo de rodovias. Nossa abordagem oferece várias vantagens em relação aos métodos tradicionais usando painéis, painéis eletrônicos digitais e outdoors, por exemplo. Baixo custo, atinge um grande número de clientes em tempo real, maior controle sobre a campanha de propaganda, atualização dinâmica de conteúdo e descoberta de serviços antes de alcançar a região de negócio são algumas delas. Para a divulgação de serviços ao longo de rodovias, seguimos a estratégia de publicidade push-based e usamos somente comunicações do tipo Infrastructure-to-Vehicle (I2V). Por outro lado, para a descoberta destes serviços pelos motoristas, utilizamos a estratégia de publicidade pull-based e comunicações oportunistas do tipo Vehicle-to-Vehicle (V2V). A fim de contribuir para a campanha de propagandas, foi utilizado o mecanismo store-carry-and-response. Nossa primeira contribuição é o Extended Opportunistic Service Discovery Protocol (EOSDP). O EOSDP implementa e estende a versão original do Opportunistic Service Discovery Protocol (OSDP) via experimentos por simulação. Nós utilizamos os simuladores Simulation of Urban Mobility (SUMO), Objective Modular Network Testbed in C++ (OMNET++) e o Vehicles in network simulation (Veins). Nossa segunda contribuição é o Service Advertisement Protocol (SADP). SADP é um protocolo leve baseado na estratégia de beaconing para divulgação de serviços em VANETs. Ele não requer conexão com a Internet para anunciar os serviços nas margens das rodovias. Além disso, a modelagem do SADP é baseada no padrão de protocolos VANETs. O desempenho do SADP foi avaliado em um cenário de rodovia congestionada, com velocidades variáveis dos veículos e sob diferentes frequências de comunicação broadcast. Por fim, apresentamos o nosso último protocolo chamado Commercial Services Discovery Protocol (CSDP). Como o protocolo anterior, o CSDP é um protocolo leve para descoberta de serviços baseado em beaconing para VANETs. O CSDP depende somente de comunicações V2V oportunistas para a descoberta de serviços ao longo de rodovias. O protocolo foi implementado no cenário de uma rodovia congestionada e avaliado com um extenso conjunto de experimentos de simulação, sob diferentes parâmetros como, por exemplo, Query Interval (QI), Query Attempts (QA) e Time to Live (TTL).

A busca constante por soluções mais eficientes, tanto no âmbito técnico como econômico, tem levado à crescente adoção de sistemas de automação baseados em redes de controle e transdutores inteligentes. A fragmentação desse mercado, no entanto, decorrente da proliferação de inúmeros protocolos e especificações para as redes de controle, impõe restrições e entraves ao desenvolvimento dos transdutores e dos sistemas de automação. A família de normas IEEE 1451 procura atenuar esse problema propondo interfaces padronizadas entre os transdutores e as redes, permitindo separar o projeto do transdutor da escolha da rede de controle. Neste trabalho foi desenvolvido um transdutor inteligente baseado na norma IEEE 1451.2 (STIM) e sua interface para a rede de controle LonWorks (NCAP). Através do desenvolvimento e avaliação dos protótipos foi verificada a aplicabilidade da norma e dos conceitos gerais da IEEE 1451, comprovando ainda seu uso em uma rede para a qual, no presente momento, não se tem conhecimento de solução similar. Constatou-se também que um transdutor inteligente baseado na IEEE 1451.2 pode ser desenvolvido com ferramentas e componentes comerciais de fácil acesso e baixo custo, e que é possível agregar os benefícios da IEEE 1451 às qualidades presentes nas redes LonWorks. Verificou-se ainda que a aceitação da IEEE 1451 no mercado é ainda incipiente, sendo imprescindível a publicação das demais normas que compõe a família para facilitar e incentivar sua adoção e disseminação. / The need for more efficient and cost-effective solutions in the control and automation market drives the increasing demand for systems based on control networks and smart transducers. However, the fragmented nature of the control network market hinders the development of solutions based on such technologies. The IEEE 1451 family of standards tries to solve this problem by specifying a common set of interfaces between the transducers and the control networks, isolating the transducer\'s project from the choice of networks. In this work, a smart transducer based on the IEEE 1451.2 standard (STIM) and its interface module to a LonWorks network (NCAP) were developed. Through the development and evaluation of the prototypes, the applicability of the standard and the concepts involved in the IEEE 1451 were verified. It was confirmed that a smart transducer based on the IEEE 1451.2 standard can be developed with low-cost, off-the-shelf components and software tools, and that it is possible to combine the benefits of the IEEE 1451 with the qualities of the LonWorks system. It was also perceived that the acceptance of the IEEE 1451 in the market is quite low, and that the release of the remaining standards that make up the IEEE 1451 family is essential for its success.

Vehicular Ad hoc Network (VANET) is a special kind of Mobile Ad hoc Network (MANET) and is a key enabling technology for Intelligent Transportation Systems (ITS). It plays an important role in the deployment of a large scale of both safety and non-safety applications. Among non-safety applications, an important and challenging area is the provision of information about roadside services advertisement and discovery. In this work, we adopted the beaconing strategy and opportunistic vehicular communications to address the problem of roadside services advertisement and discovery on the highways. Our approach offers several advantages over the traditional billboard method, e.g., low cost, targeting a large number of customers in a real time, more control over the advertisement campaign, dynamic content updating, and discovery of services far ahead of the business region. For advertising roadside services, we followed the push-based advertisement strategy and relied on Infrastructure-to-Vehicle (I2V) communications only. On the other hand, for discovering these services by the drivers, we used pull-based advertisement strategy and opportunistic Vehicle-to-Vehicle (V2V) communications. In order to contribute to the advertisement campaign, we used the store-carry-and-response mechanism. Our first contribution is the Extended Opportunistic Service Discovery Protocol (EOSDP). EOSDP implements and extends the original version of Opportunistic Service Discovery Protocol (OSDP) via simulation experiments. We used Simulation of Urban Mobility (SUMO), Objective Modular Network Testbed in C++ (OMNET++), and Vehicles in network simulation (Veins) simulators. Our second contribution is Service Advertisement Protocol (SADP). SADP is a lightweight beaconing-based services advertisement protocol for VANETs. It does not require the Internet connection for advertising the roadside services. Moreover, SADP modeling is based on VANETs standard protocols. The performance of SADP was evaluated in a congested highway scenario with varying speed of vehicles and under different broadcast frequencies. Our last contribution is Commercial Services Discovery Protocol (CSDP). Like the previous protocol, CSDP is a lightweight beaconing-based services discovery protocol for VANETs. CSDP is infrastructureless protocol which only depends on opportunistic V2V communications for roadside services discovery. The protocol was implemented in congested highway scenario and extensive set of simulation experiments were performed to evaluate its performance under different parameters, e.g., Query Interval (QI), Query Attempts (QA), and Time to Live (TTL). / Vehicular Ad hoc Network (VANET) é um tipo especial de Mobile Ad hoc Network (MANET) e é uma tecnologia chave para apoiar os Sistemas Inteligentes de Transporte (ITSs). Ela desempenha um papel importante na implantação em grande escala das aplicações do tipo safety e non-safety. Dentre as aplicações non-safety, uma área importante e desafiadora é descoberta e divulgação de informação sobre serviços. Neste trabalho, nós adotamos a estratégia de beaconing e as comunicações veiculares oportunistas para resolver o problema da descoberta e divulgação de serviços ao longo de rodovias. Nossa abordagem oferece várias vantagens em relação aos métodos tradicionais usando painéis, painéis eletrônicos digitais e outdoors, por exemplo. Baixo custo, atinge um grande número de clientes em tempo real, maior controle sobre a campanha de propaganda, atualização dinâmica de conteúdo e descoberta de serviços antes de alcançar a região de negócio são algumas delas. Para a divulgação de serviços ao longo de rodovias, seguimos a estratégia de publicidade push-based e usamos somente comunicações do tipo Infrastructure-to-Vehicle (I2V). Por outro lado, para a descoberta destes serviços pelos motoristas, utilizamos a estratégia de publicidade pull-based e comunicações oportunistas do tipo Vehicle-to-Vehicle (V2V). A fim de contribuir para a campanha de propagandas, foi utilizado o mecanismo store-carry-and-response. Nossa primeira contribuição é o Extended Opportunistic Service Discovery Protocol (EOSDP). O EOSDP implementa e estende a versão original do Opportunistic Service Discovery Protocol (OSDP) via experimentos por simulação. Nós utilizamos os simuladores Simulation of Urban Mobility (SUMO), Objective Modular Network Testbed in C++ (OMNET++) e o Vehicles in network simulation (Veins). Nossa segunda contribuição é o Service Advertisement Protocol (SADP). SADP é um protocolo leve baseado na estratégia de beaconing para divulgação de serviços em VANETs. Ele não requer conexão com a Internet para anunciar os serviços nas margens das rodovias. Além disso, a modelagem do SADP é baseada no padrão de protocolos VANETs. O desempenho do SADP foi avaliado em um cenário de rodovia congestionada, com velocidades variáveis dos veículos e sob diferentes frequências de comunicação broadcast. Por fim, apresentamos o nosso último protocolo chamado Commercial Services Discovery Protocol (CSDP). Como o protocolo anterior, o CSDP é um protocolo leve para descoberta de serviços baseado em beaconing para VANETs. O CSDP depende somente de comunicações V2V oportunistas para a descoberta de serviços ao longo de rodovias. O protocolo foi implementado no cenário de uma rodovia congestionada e avaliado com um extenso conjunto de experimentos de simulação, sob diferentes parâmetros como, por exemplo, Query Interval (QI), Query Attempts (QA) e Time to Live (TTL).

Le Wi-Fi est omniprésent dans les villes, que ce soit par le nombre grandissant de point d'accès public, ou la déploiement massif de points d'accès privés, sous la forme de boxes d'opérateurs notamment. Si nous supposons que l'ensemble de ces points d'accès soient utilisables afin de permettre à n'importe quel appareil d'accéder à Internet, alors nous aurions potentiellement une couverture réseau sur l'ensemble de la ville. Ce postulat nous a conduit à nous demander si le Wi-Fi pouvait être utilisé comme réseau à l'échelle urbaine. Ce réseau pourrait plus particulièrement être utilisé dans un contexte de mobilité. Or, le Wi-Fi n'a pas été conçu dans le but de gérer des utilisateurs mobiles,et les appareils doivent régulièrement changer de points d'accès lorsqu'ils n'ont plus de connectivité. Ce mécanisme, appelé handover, peut être long car les appareils doivent d'abord constater leurs pertes de connectivité avant de commencer à chercher le prochain point d'accès auquel s'associer. Il peut être particulièrement long pour des appareils comme les smartphones car ces derniers sont contraint en énergie et n'appliquent donc pas une politique de handover aggressive. Dans ce contexte nous avons cherché à caractériser les applications possible sur le Wi-Fi lorsqu'un utilisateur est mobile, en fonction de la durée de handover de son équipement, de sa vitesse et de la densité des points d'accès présents dans la ville. Nous avons constaté que pour les utilisateurs se déplaçant à faible allure, l'impact de la durée de handover est faible au regard de la connectivité totale, ce qui leur permet d'utiliser des applications gourmandes en terme de bande passante tant que celles-ci possèdent un certain degré de tolérances aux déconnexions. Cependant lorsque la vitesse de déplacement augmente, la durée de handover dégrade progressivement la connectivité des utilisateurs, de telle sorte que ceux ayant une allure élevée ne peuvent plus espérer utiliser les différents points d'accès. En effet, les équipements passent alors plus de temps à effectuer des handovers qu'à échanger des données applicatives. Les retransmissions jouant un rôle important dans la durée de handover, nous avons étudié finement leurs fonctionnement en 802.11.Pour cela nous avons mis en place un banc d'essai nous permettant d'observer les séquences de messages retransmis par différentes implémentations de 802.11lorsque l'on fait subitement disparaitre le point d'accès. Nous avons comparé ces séquences avec celle décrite dans le standard, et nous avons constaté que le nombre de retransmissions maximal ainsi que l'augmentation de la fenêtre de contention n'étaient pas respectés. De plus, ces implémentations passent beaucoup de temps à tenter de retransmettre avant d'initier leurs procédures de handover. Les retransmissions sont aussi utilisées dans les algorithmes d'adaptation de débits afin de déterminer si le lien se dégrade. Or, lors de la contention, le nombres de pertes augmente avec la plus forte probabilité de collisions. Afin d'observer l'impact des retransmissions sur les algorithmes d'adaptation de débits lors de la contention, nous avons mis en place un banc d'essai composé d'une trentaine de stations identiques. Nous avons constaté que l'algorithme de contrôle de débit utilisé est sous optimal par rapport à l'utilisation d'une modulation unique. Enfin, nous nous sommes intéressés à l'utilisation d'un tel réseau à l'échelle de la ville afin d'acheminer des données ayant une forte validité spatiale. Nous avons alors proposé un schéma d'adressage géographique exploitant l'infrastructure d'Internet. Il permet à la fois d'obtenir un découpage hiérarchique du monde, et d'avoir un préfixe hiérarchique des adresses, similaire à celui de CIDR. Nous montrons que ce schéma d’adressage peut être utilisé dans des adresses multicast pour envoyer des messages à destination de zones géographiques précises (surface minimale d'un mètre carré). / Wi-Fi is everywhere in cities, whether through the growing number of publicaccess points, or the massive private access points deployment, in the formof set-top boxes for the major part.If we assume that all these access points are usable in order to allow anydevice to access the Internet, then we would potentially have network coveragethroughout the city.This assumption led us to wonder if Wi-Fi could be used as a city-wide network.This network could, more specifically, be used in a context of mobility.However, Wi-Fi was not designed to manage mobile users, and devices have tooften change their access points when they no longer have connectivity.This mechanism, called handover, can be long because devices must first detecttheir connectivity losses before they can start looking for the next accesspoint to associate with.It can be particularly long for devices such as smartphones because they areenergy constrained and therefore do not apply an aggressive handover policy.In this context we tried to characterize the possible Wi-FI applications for amoving user, considering the handover duration, the user speed and the accesspoints density in the city.We found that for slow-moving users, the impact of the handover is smallcompared to the their overall connectivity.This allows them to use bandwidth-intensive applications as long as they areto some extend delay-tolerant.However, when the user’s speed increases, the impact of handover’s durationgradually degrades the user’s connectivity, so that high speed users can nolonger expect to use different access points.Fast moving devices spend more time performing handovers with new access pointsthan transmitting application data.Retransmissions play an important role in the duration of handover.In order to study in detail the retransmissions in 802.11, we have set up atestbed allowing us to observe the sequences of retransmitted messages usingdifferent implementations of 802.11 when we suddenly make the access pointdisappear.We compared these sequences with the one described in the standard, and we wefound that the maximum number of retransmissions as well as the growth in thecontention window were not respected.In addition, these implementations spend a lot of time trying to retransmitbefore initiating their handover procedures.Retransmissions are also used in the rate control algorithms to determine ifthe link is deteriorating.However, during contention, the number of losses increases with the higherprobability of collisions.In order to observe the impact of retransmissions on the rate controlalgorithms during contention, we have set up a testbed composed of about thirtyidentical stations.We found that the rate control algorithm used underperforms compared to theuse of a single modulation.Finally, we proposed a geographical addressing scheme compliant with theInternet infrastructure.It allows to obtain both a hierarchical division of the world, and ahierarchical prefix for the addresses, similar to the one used in the CIDRformat.We show that this addressing scheme can be used in multicast addresses to sendmessages to specific geographical areas (minimum area of one square meter).

De nouveaux protocoles ont été standardisés afin d'intégrer les réseaux de capteurs sans fil (WSN) dans l'Internet. Parmi eux, RPL pour la couche routage et IEEE 802.15.4 pour la couche MAC. L'objectif de cette thèse est d'améliorer ces protocoles en prenant compte des contraintes énergétiques des dispositifs du WSN. Tout d'abord, nous avons conçu une nouvelle méthode de diffusion dans la norme IEEE 802.15.4, afin d'assurer une livraison fiable des paquets de contrôle des couches supérieures. Ensuite, nous avons fourni une évaluation exhaustive de RPL, en soulignant un problème d'instabilité qui génère une surcharge d'énergie importante. Compte tenu que la durée de vie des WSN est très limitée, nous avons aussi proposé une nouvelle métrique de routage qui identifie les goulets d'étranglement énergétiques afin de maximiser la durée de vie du réseau. Enfin, en couplant cette mesure avec une version multiparent de RPL, nous avons résolu le problème d'instabilité souligné précédemment. / New protocols have been standardized in order to integrate Wireless Sensor Networks (WSN) in the Internet. Among them, the IEEE 802.15.4 MAC layer protocol, and RPL, the IPv6 Routing Protocol for Low-power and Lossy Networks. The goal of this thesis is to improve these protocols, considering the energy constraints of the devices that compose the WSN. First, we proposed a new MAC layer broadcast mechanism in IEEE 802.15.4, to ensure a reliable delivery of the control packets from the upper layers (especially from RPL). Then, we provided an exhaustive evaluation of RPL and highlighted an instability problem. This instability generates a large overhead, consuming a lot of energy. Since the lifetime of WSN is very limited, we proposed a new routing metric that identifies the energy bottlenecks and maximizes the lifetime of the network. Finally, by coupling this metric with a multipath version of RPL, we are able to solve the instability problem previously highlighted.