Les réseaux de capteurs sans fil contiennent de nombreux nœuds capables de recueillir et de transmettre des données de manière autonome. Optimiser la collecte de données est une tâche importante pour ces réseaux. Cette optimisation passe par trois axes: 1. L'agrégation des paquets pour réduire le trafic dans le réseau.2. Éviter les interférences et les collisions de paquets. 3. Une bonne stratégie de déploiement des nœuds. D'abord, nous avons travaillé sur l'agrégation de données dans les réseaux de capteurs. Cette technique permet au réseau de réduire la consommation d'énergie en éliminant les paquets redondants, et en combinant plusieurs paquets pour les envoyer en un seul paquet. Dans notre travail, nous avons considéré les applications temps réel dans les réseaux de capteurs. Nous avons proposé une solution qui combine un clustering multi-niveaux avec un mécanisme de transmission de données entre les clusterheads qui favorise l'agrégation. En outre, nous avons développé une nouvelle approche distribuée pour construire un backbone virtuel dans les réseaux de capteurs. Les nœuds du backbone sont les nœuds d'agrégation. Cette technique permet de réduire la consommation d'énergie et améliore la tolérance aux pannes et ainsi augmente la quantité de données qui atteint la station de base. Ensuite, nous nous sommes concentrés sur la façon dont les capteurs accèdent au canal de transmission via les protocoles MAC afin de diminuer le risque de collision des paquets. L'originalité de notre travail est lié à l'utilisation des nœuds mobiles et les applications temps réel dans les réseaux de capteurs sans fil. En effet, ces deux critères ont toujours été traités de façon séparée. Toute approche développée qui vise à améliorer la performance du réseau ne fonctionne bien qu'avec une bonne stratégie de déploiement sur le terrain. Par conséquent, nous proposons une nouvelle solution pour estimer les positions des différents composants du réseau et nous fournissons un nouvel outil pour aider les techniciens sur terrain lors de l'installation de ces composants. Notre solution de déploiement a été appliquée à un réseau de compteurs intelligents appelé EverBlu. Ce système est une solution de collecte de données sans fil développée par Itron. Il est adapté à tout type de compteur (eau, gaz et chaleur) et pour différentes topologies de sites, que ce soit en milieu urbain ou rural / Wireless sensor networks (WSNs) contain many nodes able to collect and transmit data autonomously. Optimizing data collection is an important issue in these networks. This optimization goes through three axis: 1. Packet aggregation to reduce the traffic in the network. 2. Avoiding interference and packets collision. 3. A good deployment strategy in field. We firstly worked on data aggregation in WSNs which enables the network to reduce energy consumption by removing redundant packets, and by combining packets together and sending them as one packet. In our research, we considered real-time applications in WSNs. For these networks, we proposed a solution that combines a multi-level clustering with a data transmission mechanism between cluster heads that promotes aggregation. In addition, we developed a new distributed approach to construct a virtual backbone in a WSN. The nodes inside the backbone are the aggregator nodes. This technique reduces the energy consumption and enhances fault tolerance which increases the amount of data that reaches the sink even when some nodes fail in the network. Then, we focus on how the sensors access to the transmission channel via Medium Access Control (MAC) protocols in order to decrease the risk of packets collision. The originality of our work is related to mobile nodes and real-time WSN applications. In fact, these two criteria were always treated independently. Any developed approach that aims to enhance the network performance works well only with a good deployment strategy in field. Therefore we propose a new solution to predict the different network components and we provide a new tool to assist the technicians in field while installing these components. Our deployment solution was applied to a smart metering network called EverBlu. This system is a wireless data collection solution developed by Itron. It is suitable for any meter type (Water, Gas and Heat) and for various site topologies, either in urban or rural environments

Com o crescimento e o desenvolvimento de aplicações para Redes de Sensores sem Fio (RSSF), os nós-sensores passaram a realizar o tratamento de eventos mais complexos, exigindo um maior desempenho de processamento e flexibilidade do hardware. Estas novas características visam atender os requisitos de diversas aplicações, assim como, apresentarem plataformas customizáveis que possuem somente os recursos necessários para atender estes requisitos. As RSSF, muitas vezes, necessitam de uma arquitetura flexível e que estejam aptas a adaptar-se a alterações de projeto ou do próprio ambiente em que se encontram inserido. A utilização de arquiteturas reconfiguráveis é uma solução que introduz esta flexibilidade e uma grande capacidade de processamento ao nó-sensor. Comparando com as arquiteturas ASICs (Application Specific Integrated Circuit), as arquiteturas reconfiguráveis apresentam um custo reduzido no desenvolvimento de aplicações, visto que a plataforma não fica fixa a somente uma aplicação. A reconfigurabilidade permite um ganho no custo e tempo de projeto, além de possibilitar o desenvolvimento de plataformas genéricas para atender um número maior de aplicações. A proposta destas plataformas é, não apenas oferecer uma plataforma eficiente e flexível, mas também potencializar a aplicação em sistemas mais complexos que necessitem de uma maior capacidade de processamento. Este trabalho apresenta o desenvolvimento de um nó-sensor reconfigurável e customizável para RSSF denominado FemtoNode. O FemtoNode possui em sua plataforma reconfigurável um processador especificado a partir de uma linguagem orientada a objetos Java e um módulo de comunicação sem fio para suportar comunicação entre os nós da rede. A arquitetura proposta foi validada com o estudo de caso de uma rede de sensores heterogênea composta por nós-sensores com plataformas distintas, sendo a análise realizada na presente dissertação. / With the growth and the development of new applications for Wireless Sensor Networks (WSN), sensors nodes are able to handle more complex events that require higher processing performance and hardware flexibility. These new features are intended to meet the requirements of various applications, as well to provide customized platforms that have only the resources needed to meet these requirements. WSNs often need a flexible architecture able to adapt to design and environment changes. The use of reconfigurable architectures is an alternative to bring more flexibility and more processing capability for the sensor-node. Compared with ASICs (Application Specific Integrated Circuit) architectures, which have a high cost in production setup, reconfigurable architectures enable a reduction in these costs because its architecture is not fixed to a single application. Reconfigurability allows a gain in the project costs and time development, and it enables the development of generic platforms to deal with a greater number of applications. Therefore, the proposal target architecture that aims to provide a flexible and efficient platform that require greater processing capacity which support the development of applications. In this work a reconfigurable and customizable sensor-node called FemtoNode is proposed. The FemtoNode has a reconfigurable platform and a wireless module to support applications for WSNs, using an object-oriented language Java as specification language of its architecture. The proposed concepts were validated with a case study of an heterogeneous wireless sensor composed of sensors nodes with different platforms, whose results are described in this work.

Este trabalho analisa as possibilidades de aplicação de redes de sensores sem-fio na agricultura, dentro do contexto da agricultura de precisão. É feita uma revisão bibliográfica genérica sobre redes de sensores sem-fio e específica sobre aplicação em agricultura. Oportunidades para aplicação real de redes de sensores neste ambiente são identificadas e caracterizadas. Uma investigação aprofundada do espaço de projeto de redes de sensores é apresentada. Com base em trabalhos publicados, é feita uma proposta de dimensões de espaço de projeto, como forma de caracterizar diferentes redes. Diversos trabalhos publicados são analisados através das dimensões propostas. Os requisitos para redes para uso agrícola são delineados e caracterizados nas dimensões de projeto. Em um segundo momento, a partir das dimensões propostas, é elaborado um modelo matemático para o funcionamento de redes de sensores. Este modelo permite explorar de forma rápida todas dimensões do espaço de projeto, verificando o impacto global na rede de decisões locais na implementação dos nós. Uma rede experimental foi implementada, sendo caracterizada segundo o modelo e posteriormente testada em condições próximas às reais de uso. Esta rede permitiu a obtenção de dados reais, auxiliou na identificação de oportunidade para uso em agricultura e contribuiu na analise de desempenho do modelo proposto. / This paper analyzes wireless sensor networks application possibilities in precision agriculture. A generic bibliographic review in the domain is done as well as a specific review about applications in agriculture. Real application opportunities in this domain were identified and characterized A deep investigation on wireless sensor networks design space is presented. A proposition of design space dimensions to characterize different networks is made based on published papers. Some previous works are analyzed using the proposed design dimensions. Requirements to the networks targeting agricultural use are delimited and characterized in these design dimensions. In a second moment a mathematical model to wireless sensor networks is proposed based on the design space dimensions. This model allows rapid design space exploration and also the verification of network impact of local node implementation decisions. A WSN was implemented and submitted to application tests. It was characterized according to the proposed model and also tested in conditions similar to the real ones. The experimental WSN allowed real data collection, helped to identified application opportunities in agriculture and contributed to analyze the behavior of the proposed model.

A presença da tecnologia da informação dentro do agronegócio tem avançado e contribuído para a obtenção de melhores resultados para a gestão e, consequentemente, para o proprietário rural. Uma área de pesquisa que tem avançado dentro do setor rural é o monitoramento e a coleta de dados dos animais, em tempo real, possibilitando ao proprietário rural gerenciar seu rebanho, sem a necessidade de se deslocar ao local monitorado ou ao ponto de coleta de dados. A utilização das redes de sensores sem fio para fins de monitoração ainda possui limitações, como por exemplo a limitação do alcance do sinal de transmissão entre os nós sensores. Atualmente as tecnologias de transmissão de dados sem fio em uma rede de sensores alcançam pequenas distâncias, limitando o processo de detecção e coleta dos dados às áreas de pastagem menores. Assim, esta pesquisa teve como objetivo avaliar, através de simulação computacional, dois tipos de protocolos de comunicação sem fio que têm potencial para serem utilizados no monitoramento de sistemas de produção animal em longas distâncias: o protocolo ZigBee e o IEEE 802.1ah. Para a realização das simulações foram utilizados os softwares OMNet++ 4.5 e uma ferramenta de extensão chamada Mixim. Para tanto, foram criados dois cenários (ambientes) para cada protocolo, onde foram definidos: a área de cobertura, em torno de 1.500 metros, topologia da rede sem fio do tipo estática, dois nós para comunicação (um coordenador e um receptor) e as características do cenário. Por meio dos resultados obtidos através de simulação computacional com aplicação das métricas: distância, latência e taxa de perda de pacotes de dados nas simulações, observou-se que o protocolo ZigBee obteve o melhor desempenho em relação à distância de cobertura do sinal e da confiabilidade dos dados transmitidos. / The presence of information technology within the agribusiness has advanced and contributed to better results for the management and, consequently, to the landowner. One area of research that has advanced into the rural sector is the monitoring and collection of animal data in real time, allowing the landowner to manage his herd, without the need to move to the monitored site or the data collection point. However the technology of wireless sensor networks used for this purpose, has limitations and one of them is the signals range factor because, in order to make the data collection is necessary to install sensors and antennas in the pasture to reach the signals. Currently, wireless data transmission technologies in a network of sensors reach short distances, limiting the detection process and data collect to smaller pasture areas. This study aimed to find a long-distance transmission solution to reach areas of larger proportions pastures, and offer the landowner new monitoring resources. The methodology used to find such a solution was through simulations, using two transmission technologies: ZigBee and IEEE 802.11ah. To perform the simulations it was used the OMNet++ software, version 4.5 and an extension tool, called the Mixim. It was created two scenarios (environments) for each protocol, where has been defined: the coverage area of about 1,500 meters, network topology wireless static type, two nodes for communication (a coordinator and a receiver) and the characteristics of the environment. Through the results obtained by computer simulation with application of the metrics: distance, latency and data packets loss rate in the simulations, it was observed that the ZigBee protocol had the best performance in relation to the signal coverage distance and the transmitted data reliability.

Orientador: Bárbara Janet Teruel Mederos / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-19T15:41:33Z (GMT). No. of bitstreams: 1 Alves_ElaineCangussudeSouza_M.pdf: 1610597 bytes, checksum: 9136ba250ed9462c6fbb4d8204f73a4a (MD5) Previous issue date: 2011 / Resumo: Este trabalho tem como objetivo coletar dados de qualidade de sinal transmitido entre uma estação base e um nó sensor localizado no interior de uma casa de vegetação, localizada no campo experimental da Faculdade de Engenharia Agrícola - UNICAMP, com o auxilio de ferramentas computacionais. No interior da casa de vegetação foi inserido um sistema hidropônico com bancadas que forneciam suporte para morangueiros da cultivar Albion. O conjunto de equipamentos e de nós sensores que foram utilizados para montar a rede é da marca Crossbow®. Após a implantação do nó sensor foram realizados experimentos com o objetivo de verificar alcance e qualidade do sinal de acordo com sua potência. Através desses ensaios foi possível concluir que uma Potência de Sinal com valor de -12,2 dBm seria suficiente para manter a transmissão entre Estação Base e Nó Sensor. Testes também foram realizados para uma Potência de Sinal de -9,2 dBm, e mostraram que a rede possuía qualidade classificada como "muito alta". Porém, através do teste de duração da bateria, nota-se que existe uma economia de energia ao utilizar a Potência de Sinal de -12,2 dBm. No geral, foi demonstrado que o valor da Potência de Sinal tem influência sobre a qualidade do sinal de transmissão e recepção, o gasto de bateria e o alcance do sinal. Assim, este é um importante parâmetro a ser considerado em um projeto de implantação de rede de sensores sem fio no meio agrícola / Abstract: This project aims to collect quality data signals transmitted between a base station and a sensor node located inside a greenhouse, which is a experimental field located in the College of Agricultural Engineering - UNICAMP, with help of computational tools. Inside the greenhouse, a hydroponic system with banks providing support for strawberry Albion was inserted. The set of sensor nodes and equipment that were used to assemble the network is the Crossbow® brand. After sensor node deployment, experiments were performed in order to check range and signal quality. Through these experiments, it was concluded that a RF power value of -12.2 dBm is sufficient to maintain transmissions between base station and the sensor. Tests were also performed to a RF power of -9.2 dBm, and showed that the network had quality rated as "very high". However, by testing the battery life, it is noted that there is an energy saving when the RF power of -12.2 dBm is used. Overall, it was shown that the value of the signal strength has an influence on the quality of signal transmission and reception, battery depletion and signal range. So, this is an important parameter to be considered in a project to establish network of wireless sensors in a agricultural environment / Mestrado / Maquinas Agricolas / Mestre em Engenharia Agrícola

The recent advancements in the communication area have enabled the Internet of Things, a paradigm which extends the Internet to everyday objects. The Internet of Things enables many new applications, but also comes with great challenges; effective communication under limited power supply being the perhaps most important one. This thesis presents the design, implementation, and evaluation of an energy-efficient handover algorithm for the main building block in the creation of the Internet of Things: wireless sensor networks. Our low-power handover design is based on a careful breakdown and analysis of the potential power consumption of different components of the handover process. With the scanning part of the process being identified as the main drain of energy, the algorithm is designed to place the majority of the scanning responsibility on the mains powered access points, rather than on the low-power mobile nodes. The proposed algorithm has been implemented and its functionality and low power consumption have been empirically evaluated. We show that the design can reduce the energy consumption by several orders of magnitude compared to existing handover algorithms for wireless sensor networks. In addition, interesting fading effects were discovered in a sparsely deployed network scenario with limited access point coverage; most likely due to multipath propagation. For this case the handover performance was greatly reduced, relative our more normal coverage scenario. While these results illustrate that the absolute energy savings will differ from scenario to scenario, the potential energy savings made possible by the proposed algorithm significantly reduce the battery requirements of the devices in the emerging landscape of the Internet of Things; potentially even opening the door for new devices to connect.

L’utilisation des réseaux de capteurs offre de nouvelles perspectives dans de nombreux domaines (médecine, militaire, etc.). Les données récoltées par ces capteurs circulent en clair sur les réseaux de capteurs et peuvent être interceptées par un espion. Selon le domaine d’utilisation, le niveau de sécurité souhaité peut être élevé, ce qui peut provoquer une hausse de la consommation d’énergie sur les nœuds. Ces deux contraintes, sécurité et énergie, sont difficilement conciliables. Il y a donc un compromis à trouver entre l’économie d’énergie qui va conditionner la durée de vie du réseau, et le niveau de sécurité souhaité par l’application. L’objectif de cette thèse est d’étudier les compromis à trouver entre ces deux contraintes, à la fois d’un point de vue théorique et d’un point de vue pratique (par une implémentation des algorithmes et des tests réels sur des réseaux de capteurs par choisissant les algorithmes DES et AES). L’algorithme de cryptographie symétrique DES a ´ et ´e choisi comme objet d’étude. Les résultats obtenus sur la plateforme académique Senslab ont permis de déterminer une relation précise entre la consommation d’énergie et le nombre de rondes de DES et donc le niveau de sécurité. Ces expériences ont été renouvelées avec l’algorithme AES, plus récent et plus sûr, mais aussi plus consommateur en énergie. Puis, à partir des résultats obtenus, un modèle générique de consommation pour les algorithmes cryptographiques a été construit pour un réseau complet. L’utilisation complémentaire de la compression des données a permis de réduire cet impact de manière intéressante. Enfin, l’utilisation de la mémoire et l’évaluation du temps de chiffrement et de compression ont été évalué de manière à rester dans des fourchettes réalistes d’utilisation réaliste. / Wireless sensor networks give us opportunities to improve many applications in many fields(medicine, military, etc.). The data collected by sensor node flies as plain text on sensor networkand can be intercepted by a spy. Depending on the importance of data, the wanted level of securitycould be high which may impact the energy consumption of sensor nodes. These two constraints,security and energy are difficult to combine. There is a trade-off between energy savings that willdetermine the lifetime of the network and the level of security desired by the application.The objective of this thesis is to study the trade-off between these two constraints, both from atheoretical perspective and from a practical point of view (with an implementation of algorithms andreal tests on sensor networks). The DES symmetric cryptographic algorithm was chosen as a casestudy. The results obtained on the academic platform Senslab have shown a clear relationshipbetween energy consumption and the number of rounds of DES and therefore the level of security.These experiments were repeated with the AES algorithm, newer and safer, but also more energyconsumer.Then, from the results, a generic model of consumption for cryptographic algorithms has been builtfor a complete network. The complementary use of data compression has reduced this impact ofenergy consumption in an interesting way. Finally, the memory usage and the time of encryption andcompression were evaluated in order to stay within realistic ranges of use.

Data collection by autonomous mobile sensor arrays can be coupled with the use of drones which provide a low-cost, easily deployable backhauling solution. These means of collection can be used to organize temporary events (sporting or cultural) or to carry out operations in difficult or hostile terrain. The aim of this thesis is to propose effective solutions for communication between both mobile sensors on the ground and on the edge-to-ground link. For this purpose, we are interested in scheduling communications, routing and access control on the sensor / drone link, the mobile collector. We propose an architecture that meets the constraints of the network. The main ones are the intermittence of the links and therefore the lack of connectivity for which solutions adapted to the networks tolerant to the deadlines are adopted. Given the limited opportunities for communication with the drone and the significant variation in the physical data rate, we proposed scheduling solutions that take account of both the contact time and the physical flow rate. Opportunistic routing is also based on these two criteria both for the selection of relay nodes and for the management of queues. We wanted to limit the overhead and propose efficient and fair solutions between mobile sensors on the ground. The proposed solutions have proved superior to conventional scheduling and routing solutions. Finally, we proposed a method of access combining a random access with contention as well as an access with reservation taking into account the aforementioned criteria. This flexible solution allows a network of dense mobile sensors to get closer to the performance obtained in an oracle mode. The proposed solutions can be implemented and applied in different application contexts for which the ground nodes are mobile or easily adapted to the case where the nodes are static.

Wireless sensor networks have arrived because of further developments of themodern Internet, and this has been considered to be one of the most importanttechnologies of the 21st century. Currently, the wireless sensor network has becomean important technology in a variety of areas and is widely used in thefield of national defense, national security, environmental monitoring, trafficmanagement, anti-terrorism, anti-disaster, and so on. The majority of these applicationsrequire real-time communication as the WSNs are required to sendthe data to the data center within a specified time. In order to meet the real-timedemand for wireless sensor networks, this work mainly focuses on the analysisand measurement of the end-to-end delay, including both single-hop and multihopdelays. This thesis first analyzes the composition of the end-to-end delayand then describes the end-to-end delay measurement algorithms and methods.The measurement is implemented in TelosB motes within TinyOS. Finally thereport will show the evaluation of the end-to-end delay in wireless sensor networks.

Wireless sensor networks (WSNs) have been used as an important tool inmany fields of science and industry. Time synchronization is also a criticalissue in wireless sensor networks and its aim is to synchronize the local timefor some or all nodes in the network, if necessary. However, wireless sensornetworks are limited in their accuracy, energy efficiency, scalability, and complexityand some traditional time synchronization algorithms such as NetworkTime Protocol (NTP) and Global Positioning System (GPS) are unsuitable forWSNs. This work surveys and evaluates state-of-art time synchronization protocolsbased on many factors including accuracy, energy efficiency, and complexity,and analyzes the effect that time synchronization has in a wirelesssensor network. IN ADDITION, more attention is paid to several time synchronizationalgorithms and their advantages and disadvantages. Also, the surveyprovides a valuable framework for comparing new and existing synchronizationprotocols. According to the evaluation for the performance of time synchronizationalgorithms, this thesis provides assistance in relation to further improvingthe performance of time synchronization. Finally, future research directionsin relation to time synchronization in wireless sensor networks are alsoproposed.