The conventional digital signature schemes widely used today may have their security threatened with the possibility of the rising of a large quantum computer. Moreover, such schemes are not entirely suitable for utilization on very constrained-resource platforms. Therefore, there is a need to look at alternatives that present reasonable security in the medium and long term, in addition to attaining acceptable performance when few resources are available. This work provides more efficient multivariate and hash-based post-quantum digital signatures and targets the deployment in scenarios like Internet of Things and Wireless Sensor Networks where the typical devices are very resource-constrained. In the context of multivariable quadratic digital signatures we describe a new technique that attempts to minimize the main drawbacks of these schemes, the large key sizes. The new technique explores certain structures compact matrix rings. Some of the analyzed matrix rings are not secure (one of the attacks runs in polynomial time). Other less compact matrix rings are investigated and they apparently do not suffer a polynomial time attack, but unfortunately are still far from deployment on very constrained platforms. On the other hand, this work describes a method for hash-based signatures providing a 2/3 reduction of the signature sizes in the Merkle-Winternitz multi-time signature scheme. In fact, the signature sizes constitute the main bottleneck of these schemes. The improvement also leads to a 2/3 reduction in the run times (key generation, signing and verifying) and in energy consumption for all these operations on an AVR ATmega128L microcontroller, typically found in Wireless Sensor Networks. This result is much more promising for the deployment in an IoT scenario. / Os esquemas convencionais de assinatura digital mais usados na atualidade têm sua segurança ameaçada com a possibilidade da construção de um computador quântico de grande porte. Ademias, tais esquemas não têm se mostrado completamente adequados para uso em plataformas com recursos computacionais extremamente escassos. Surge então a necessidade da busca por alternativas que satisfaçam as condições de segurança a médio e longo prazo, além de apresentarem desempenho razoável quando poucos recursos computacionais estão disponíveis. Este trabalho obtém assinaturas digitais pós-quânticas multivariadas quadráticas e baseadas em hash mais eficientes e tem o intuito de torna-las práticas em cenários como Internet das Coisas e Redes de Sensores Sem Fio (RSSF), caracterizados por apresentarem dispositivos com recursos computacionais limitados. No contexto de assinaturas multivariadas quadráticas, descreve-se uma nova técnica que tenta minimizar o principal gargalo desses esquemas, o grande tamanho de chaves. A nova técnica explora certos anéis matriciais com estrutura compacta. Mostra-se que alguns dos anéis analisados não são seguros (um dos ataques apresenta tempo polinomial), enquanto outros anéis menos compactos aparentam não sofrer ataque polinomial, mas infelizmente ainda não são adequados para uso em dispositivos muito restritos. Por outro lado, descreve-se um método para obter assinaturas digitais baseadas em hash que fornece redução das assinaturas para 2/3 do tamanho original do esquema multi-time Merkle-Winternitz. De fato, o tamanho das assinaturas constitui o principal gargalo desses esquemas, A melhoria também acarreta uma redução em 2/3 nos tempos de execução (geração de chave, geração de assinaturas e verificação de assinatura) e no consumo de energia para essas operações quando executadas em um microcontrolador AVR tipicamente usado em Redes de Sensores Sem Fio, o AT-mega 128L. Este resultado torna-se promissor para implantação de assinaturas baseadas em hash no cenário de Internet das Coisas.

Diversas aplicações de redes de sensores sem fio necessitam de serviços de segurança, como confidencialidade, integridade e autenticação de origem de dados. Contudo, dadas as limitações de processamento, memória e suprimento de energia dos dispositivos, os mecanismos de segurança tradicionais podem causar efeitos indesejáveis na rede, como atraso na comunicação e aumento no consumo de energia, impondo obstáculos para seu uso na tecnologia em questão. Muitas propostas de esquemas de segurança baseados em criptografia simétrica projetados especificamente para redes de sensores sem fio são encontradas na literatura. Contudo, essas soluções são focadas na segurança salto-a-salto. Tal abordagem é adequada para garantir a segurança dos enlaces deste tipo de rede, mas não garante a segurança na comunicação fim-a-fim. Neste trabalho são apresentados cenários e desafios de implementação de segurança neste tipo de rede, e a concepção, o projeto e a implementação de uma arquitetura de segurança para redes de sensores sem fio, que tem como objetivos: prover segurança na comunicação fim-a-fim; permitir a interoperabilidade entre diferentes sistemas; e possibilitar uma maior flexibilidade em relação à utilização de chaves criptográficas em diferentes cenários e topologias. Adicionalmente, a solução proposta suporta ativação e desativação de seus serviços em tempo de execução. O projeto da referida arquitetura, atuante na camada de aplicação da pilha de protocolos de rede, foi construído com base na análise das características de arquiteturas encontradas na literatura, bem como de estratégias adotadas por estas. Para a construção da implementação foram selecionados mecanismos e algoritmos criptográficos a partir da avaliação de desempenho que considerou assimétricas de uso de memória, tempo de execução e consumo de energia. Como resultados são apresentados a especificação da arquitetura, a avaliação qualitativa da mesma e a avaliação de desempenho da implementação desenvolvida como prova de conceito. Além disso, é apresentada uma análise do impacto de diferentes topologias e características de disposição na tarefa de distribuição de chaves criptográficas em redes de sensores sem fio. / Many wireless sensor networks applications need security services, such as confidentiality, data integrity and data source authentication. On the other hand, because of device limitations, security mechanisms may affect the network energy consumption and communication delay, which impose a great challenge for practical implementation of security mechanisms in such scenario. Many solutions based on symmetric cryptography were proposed for the specific challenges of wireless sensor networks. Nevertheless, they are focused on hop-by-hop security. Such approach is suited to provide link-layer security, but it cannot guarantee end-to-end security. This work presents scenarios and challenges to implement security in wireless sensor networks, and the conception, design and implementation of a security architecture, which aims to provide: security in end-to-end communication; interoperability between different systems, and enable greater flexibility in cryptographic keys distribution in different scenarios and topologies. Additionally, the proposed solution supports on-the-y adjustment of its security services. The architecture design, which targets the application layer of the network protocol stack, was based on the main properties of the architectures found in literature as well as adopted strategies. For the implementation, mechanisms and cryptographic algorithms were selected through the performance evaluation that considers memory usage, execution time and power consumption as metrics. The results were the architecture specification and its qualitative analysis, and the performance evaluation of the implementation developed as proof of concept. Furthermore, we present an analysis of topology and deployment impact on key distribution task.

A aplicação eficiente de agrotóxicos é um desafio na produção agrícola, mesmo considerando os avanços com a agricultura de precisão. O efeito deriva é o principal responsável pela ineficiência no controle das pragas ou doenças, pelo desperdício de recursos e pela contaminação ambiental. Para minimizar a deriva é essencial conhecer as condições ambientais como vento, temperatura e umidade. Esta pesquisa propõe o uso das redes de sensores sem fio como sistema de monitoramento ambiental e de suporte ao processo de pulverização agrícola, especialmente a pulverização executada por aeronave. São propostas três funcionalidades para o sistema: avaliação das condições ambientais, verificando se as condições estão apropriadas para a pulverização, buscando minimizar a ocorrência da deriva; suporte na definição e manutenção da rota do veículo pulverizador por meio dos dados do vento, de modo a efetuar ajustes na rota de pulverização e manter a aplicação do defensivo agrícola na área alvo; e a avaliação da eficácia da pulverização por meio dos dados da deposição do produto pulverizado coletados pela rede de sensores. Para viabilizar a utilização das redes de sensores sem fio no controle da deriva é proposto um protocolo de roteamento de dados que visa garantir a coleta dos dados pelos nós e a entrega para o veículo pulverizador, mesmo sendo ele um avião e se deslocando em alta velocidade. Para demonstrar a viabilidade do sistema proposto, foi desenvolvido um sistema de simulação computacional que considera os aspectos das redes de sensores sem fio e as características do protocolo de roteamento proposto. Os resultados demonstraram sua viabilidade, demonstrando que as redes de sensores sem fio podem ser utilizadas como suporte em um sistema de controle da deriva, incrementando a qualidade da pulverização, reduzindo custos e a contaminação ambiental. / The efficient application of low cost pesticides is a challenge for agricultural production. Pesticide drift is the major cause of money loss, inefficiency in crop disease control, and environmental contamination in the crop spraying process. At the time of application, it is essential to know the environmental conditions, such as wind, temperature and humidity to minimize contamination by pesticide drift. This study proposes the use of wireless sensor networks in a support and control system for crop spraying, especially in aircraft application methods. Three system functionalities are proposed: In the first case, the sensor network evaluates environmental data at the time of application to notify the user if the environmental conditions are suitable for continuing with the application. The second case evaluates the wind speed and its direction to suggest corrections in the path of a spray vehicle. Due to this alteration in the vehicle path, the pesticide will be applied only in the appropriate area. The final case involves collecting data samples and analyzing the quality of the spraying operation by evaluating the deposition of pesticide over the crop. This work proposes a new routing data protocol to make possible the use of wireless sensor networks in aerial crop spraying. It ensures that the sensor node data will be delivered to the sink node. Through computer simulations, wireless sensor networks are shown to be useful in crop spraying to minimize and to control pesticide drift, to improve the quality of application, to reduce environmental contamination and to reduce costs and the duration of the application operation.

Este trabalho apresenta um estudo da instrumentalização de software em Redes de Sensores Sem Fio, complementado pela aplicação, em um estudo de caso, de uma instrumentalização. A proposta da instrumentalização visa ampliar o conhecimento sobre essas redes em termos de desempenho, permitindo ao usuário tomar decisões suportadas pelo instrumento. Nesse sentido, foi realizada a abordagem conceitual em termos de Redes de Sensores Sem Fio, da tendência de padronização para essas redes e de instrumentalização por meio de software. Para a comprovação dos benefícios da adoção da utilização do conceito de instrumentalização de software nessas redes, foi desenvolvida uma rede de sensores utilizando esses conceitos, na qual foi possível avaliar o perfil dos aspectos temporais e da manutenção da qualidade da conexão. Os resultados obtidos evidenciam que é possível conhecer, com maiores detalhes, o comportamento da rede, o que melhora a qualidade da tomada de decisão do usuário em relação à sua utilização em aplicações com restrições temporais, nas quais os tempos de resposta envolvidos devem respeitar os limites máximos permitidos. / This thesis aims at the study of software instrumentation handling in terms of wireless sensor networks which is supplemented with the its application in a case study. The instrumentation purposes go towards the networks knowledge extension concerning its performance by allowing the user to make decisions based on software instrument reading. In this sense, a conceptual approach was performed which takes the wireless sensor network into account as well as the trend of standardization for these networks and the software instrumentation itself. In order to confirm the benefits on adopting the usage of software instrumentation concept on these networks, a wireless sensor network was developed using these concepts. In this sense, it was possible to evaluate the timing aspects profile and the link quality maintenance. The results show that is possible to know about the behavior of the network in details. By doing this, the quality of the users decision-making regarding their use in applications with time constraints, in which response time involved should respect the maximum allowable limits, has been improved.

Submitted by Maria Aparecida (cidazen@gmail.com) on 2017-08-01T14:53:33Z No. of bitstreams: 1 Higo Felipe.pdf: 3289455 bytes, checksum: 294f49f96fd41d35ca0024df16006292 (MD5) / Made available in DSpace on 2017-08-01T14:53:33Z (GMT). No. of bitstreams: 1 Higo Felipe.pdf: 3289455 bytes, checksum: 294f49f96fd41d35ca0024df16006292 (MD5) Previous issue date: 2017-01-26 / CAPES / Lately, there has been a significant advance in several technologies directly or indirectly related to Ubiquitous Computing. Among them, the technology of Wireless Sensor Networks (WSNs) can be mentioned. Having its space in the current scenario, the use of wireless sensors extends into various branches of human activity: industrial monitoring, smart houses, medical and military applications. However, several shortcomings and limitations in wireless sensors can be noted: limited hardware, energy and computational capacity are points that are always treated by those who work with such devices. As for these devices, there is, besides the factors already mentioned, an important concern regarding their safety. As with other devices, for these threats to be at least mitigated, it is necessary to create layers of security. One of these layers may be formed by Intrusion Detection Systems (IDS). However, due to the aforementioned hardware restriction of the sensors, the development of IDSs - as well as any other application - for such devices should assume such characteristics. As for IDSs, there are some aspects that need to be taken into account, especially flexibility, efficiency and adaptability to new situations. A paradigm that facilitates the implementation of such capabilities is the Intelligent Agents. Therefore, this paper describes the proposition of a framework for intrusion detection in WSNs based on intelligent agents. / Ultimamente, houve um avanço significativo em várias tecnologias direta ou indiretamente correlatas à Computação Ubíqua. Entre elas, pode-se citar a tecnologia das Redes de Sensores sem Fio (WSN s). Tendo já o seu espaço no atual cenário, o uso dos sensores sem fio se estende em vários ramos da atividade humana: monitoramento industrial, smart houses, aplicações médicas e militares. Entretanto, várias deficiências e limitações em sensores sem fio podem ser notadas: recursos limitados de hardware, energia e capacidade computacional são pontos a sempre serem tratados por quem trabalha com tais dispositivos. Quanto a esses dispositivos há, além dos fatores já citados, uma preocupação importante referente á sua segurança. Assim como em outros dispositivos, para que essas ameaças sejam, ao menos, mitigadas é necessário criar camadas de segurança. Uma dessas camadas pode ser formada pelos Sistemas de Detecção de Intrusão (IDS). No entanto, devido à já mencionada restrição de hardware dos sensores, o desenvolvimento de IDSs bem como qualquer outra aplicação para esses dispositivos deve supor tais características. No que se refere, ainda, aos IDSs, há alguns aspectos que devem ser levados em conta, sobretudo flexibilidade, a eficiência e a capacidade de adaptação a novas situações. Um paradigma que facilita a implementação de tais capacidades são os Agentes Inteligentes. Sendo assim, este trabalho descreve a proposta de um framework para detecção de intrusões em WSNs baseado em agentes inteligentes.

A irrigação é considerada uma das mais importantes tecnologias empregadas para aumentar a produtividade e permitir maior eficiência e estabilidade na produção agrícola. A sua adoção deve ser baseada na viabilidade técnica e econômica do projeto, obtida por meio da análise detalhada e cuidadosa dos fatores climáticos, agronômicos e econômicos envolvidos. O manejo eficiente pode ser definido como o uso criterioso dos recursos disponíveis para se atingir um determinado objetivo. No caso da irrigação, o manejo eficiente objetiva maximizar a produção vegetal com o menor custo possível, tanto em quesitos ambientais quanto econômicos. Para tanto, necessita-se do desenvolvimento de um sistema tecnologicamente eficiente, de reduzido custo e de facilidade de instalação e manutenção. Assim, uma rede inteligente de estações meteorológicas, capaz de monitorar o ambiente em tempo real, de adaptar-se aos diversos estágios fenológicos da planta, aos diversos solos e culturas e de comunicar-se entre si e com um servidor torna-se necessário. Este projeto teve como objetivo o desenvolvimento e emprego de uma rede de estações meteorológicas sem fio, de baixo custo e de fácil manutenção e implantação, para a determinação da evapotranspiração de referência, e do conteúdo de água no solo para o eficiente manejo de irrigação. Para que tal rede de sensores seja implantada, há a necessidade de que os módulos eletrônicos possuam microcontroladores de baixo consumo energético, uma vez que eles serão alimentados por baterias e painéis solares, e com capacidade para executar os algoritmos de inferência das variáveis de medida, de calibração e correção de tais medidas, de comunicação com os demais elementos da rede e de executar o controlador de irrigação, baseado em Redes Neurais Artificiais. A abordagem da inteligência artificial utilizada possui a capacidade de aprender e estimar parâmetros a partir de sua base de treinamento e das condições que a cercam. Além das capacidades do microcontrolador, o módulo dos sensores deverá possuir elementos para aferir a temperatura e a umidade do ambiente, a radiação solar, a temperatura e o conteúdo de água no solo, além de um módulo de comunicação sem fio. O sistema desenvolvido foi testado nas estufas do INCT-EI/ESALQ/USP manejando a irrigação da cultura do pimentão vermelho Capsicum annuum L. cv. All Big, durante o período de 25/01/2018 a 31/07/2018. Após o treinamento da rede neural artificial, o sistema desenvolvido determinou a evapotranspiração de referência com um coeficiente de determinação de 0,968, com um erro médio absoluto de 0,055 mm e com um valor-P de 1,02 10-45 para um intervalo de confiança de 95%. Sendo assim, verificou-se que a rede de estações meteorológicas desenvolvida é capaz de estimar a evapotranspiração de referência a partir de dados provenientes de sensores de reduzido custo financeiro e com dados meteorológicos faltantes. / Irrigation is considered one of the most important technologies used to increase productivity and to allow greater efficiency and stability in agricultural production. Its adoption must be based on technical and economic feasibility of the project, obtained by means of a detailed and careful analysis of the climatic, agronomic and economic factors involved. Efficient management can be defined as the judicious use of available resources to achieve a given goal. In the case of irrigation, efficient management aims to maximize plant production at the lowest possible cost, both in environmental and economic aspects. This requires the development of a technologically efficient system, which is low cost and ease of installation and maintenance. Thus, an intelligent network of weather stations capable of monitoring the environment in real time, adapting to the plant\'s various phenological stages, diverse soils and cultures and communicating with each other and with a server becomes necessary. This project aimed at the development and use of the wireless station network which is low cost, easy maintenance, and deployment for the determination of reference evapotranspiration and soil water content for efficient irrigation management. In order for such a sensor network to be implemented, there is a need for such modules to have low energy microcontrollers, since they will be powered by batteries and solar panels, and capable of performing the inference algorithms of the measurement, calibration, and correction of such measures, of communication with the other elements of the network and of executing the irrigation controller, based on Artificial Neural Networks. The artificial intelligence approach used has the capacity to learn and estimate parameters based on its training base and the conditions surrounding it. In addition to the capabilities of the microcontroller, the sensor module must have elements to measure ambient temperature and humidity, brightness, temperature and soil water content, as well as a wireless communication module. The developed system was tested in the greenhouses of INCT-EI/ESALQ/USP managing the irrigation of the red bell pepper crop Capsicum annuum L. cv. All Big, during the days of 01/25/2018 to 31/07/2010. After the artificial neural network training, the developed system determined reference evapotranspiration with a determination coefficient of 0.968, with an absolute mean error of 0.055 mm and a P-value of 1.02 10-45 for a confidence interval of 95%. Thus, it was verified that the developed weather-station network is able to estimate the reference evapotranspiration with low-cost sensors and with missing meteorological data.

La technologie des réseaux de capteurs sans fil (RCSF) est l’un des éléments constitutifs de l’Internet des objets (IoT). En raison de leurs caractéristiques de déploiement facile et de leur flexibilité, ils sont utilisés dans de nombreux domaines d’application. Les réseaux à faible consommation et à perte (LLN) sont un type spécial de WSN dans lequel les noeuds sont largement limités en ressources. Convergecast est l’un des modes de communication de base, dans lequel tout le trafic du réseau est destiné à une destination prédéfinie appelée collecteur. Tout en prenant en compte les domaines d’applications IoT, convergecast n’est pas le seul mode de communication sur le réseau. Le récepteur doit envoyer des commandes à certains capteurs pour effectuer des actions. Dans cette application, anycast est un autre mode de communication de base. Dans anycast, le trafic provenant du récepteur est destiné à tout membre d’un groupe de récepteurs potentiels du réseau.Les LLN sont formés de noeuds de capteurs statiques et changent rarement de position. En raison des contraintes de ressources strictes imposées au calcul, à l’énergie et à la mémoire des LLN, la plupart des protocoles de routage ne prennent en charge que les réseaux statiques. Cependant, la mobilité est devenue une exigence importante pour de nombreuses applications émergentes. Dans ces applications, certains noeuds sont libres de se déplacer et de s’organiser dans un réseau connecté. La topologie changerait continuellement en raison du mouvement des noeuds et de l’instabilité des liaisons radio. Il s’agit d’une tâche difficile pour la plupart des protocoles de routage des réseaux LLN afin de s’adapter rapidement au mouvement et de reconstruire la topologie en temps voulu. Le but de cette thèse est de proposer un support de mobilité efficace pour les protocoles de routage dans les réseaux LLN. Nous nous concentrons sur convergecast et anycast, qui sont les modes de communication les plus utilisés dans les réseaux LLN, dans les scénarios de réseau mobile. Nous proposons un mécanisme d’amélioration, nommé RL (RSSI and Level),pour prendre en charge les protocoles de routage dans les réseaux LLN convergecast en mobilité. Ce mécanisme aide le protocole de routage à prendre des décisions plus rapides pour la détection de la mobilité et la mise à jour des voisins du saut suivant,mais souffre d’une surcharge importante. Nous proposons une gestion dynamique des messages de contrôle pour améliorer les performances de RL et l’implémentons en plus du protocole de routage pour réseau à faible consommation (RPL) et nous l’avons nommé RRD (RSSI, Rank and Dynamic). Après une prise en compte de l’hystérésis de la zone de couverture de la plage de transmission des noeuds, nousavons optimisé RRD. Cette version améliorée s’appelle RRD +. Sur la base de RRD+, nous avons proposé MRRD + (Multiple, RSSI, Rank et Dynamic) pour prendre en charge plusieurs puits dans les réseaux LLN convergecast en mobilité. ADUP (Adaptive Downward / Upward Protocol) est une solution de routage prenant en charge simultanément convergecast et anycast dans les réseaux LLN. Nous avons évalué les performances de nos contributions à la fois en simulation avec le simulateur Cooja et en expérience (uniquement pour ADUP) sur des motosTelosB. Les résultats obtenus en simulation et en expérience confirment l’efficacité de nos protocoles de routage. / Wireless Sensor Networks (WSNs) technology is one of the building blocks ofthe Internet of Things (IoT). Due to their features of easy deployment and flexibility,they are used in many application domains. Low-Power and Lossy Networks(LLNs) are a special type of WSNs in which nodes are largely resources constrained.For LLNs, convergecast is one of the basic traffic modes, where all traffic in the networkis destined to a predefined destination called the sink. While considering theIoT application domains, convergecast is not the only traffic mode in the network.The sink needs to send commands to certain sensors to perform actions. In this application,anycast is another basic traffic mode. In anycast, the traffic from the sinkis destined to any member of a group of potential receivers in the network.Traditionally LLNs are formed by static sensor nodes and rarely change positions.Due to the strict resource constraints in computation, energy and memory ofLLNs, most routing protocols only support static network. However, mobility hasbecome an important requirement for many emerging applications. In these applications,certain nodes are free to move and organize themselves into a connectednetwork. The topology would continuously change due to the movement of nodesand radio links instability. This is a hard task for most routing protocols of LLNs toadapt rapidly to the movement and to reconstruct topology in a timely manner.The goal of this thesis is to propose an efficient mobility support for routingprotocols in LLNs. We focus on convergecast and anycast, which are the most usedtraffic modes in LLNs, in mobile network scenarios.We propose an enhancement mechanism, named RL (RSSI and Level), to supportrouting protocols in convergecast LLNs in mobility. This mechanism helps routingprotocol make faster decisions for detecting mobility and updating next-hop neighborsbut suffers from high overhead. We propose a dynamic control message managementto enhance the overhead performance of RL and implement it on top ofRouting Protocol for Low-power and Lossy network (RPL) and we named it RRD(RSSI, Rank and Dynamic). After taking into account hysteresis of the coveragezone of the transmission range of nodes, we optimized RRD. This enhanced versionis called RRD+. Based on RRD+, we proposed MRRD+ (Multiple, RSSI, Rankand Dynamic) to support multiple sinks in convergecast LLNs in mobility. ADUP(Adaptive Downward/Upward Protocol) is a routing solution that supports bothconvergecast and anycast in LLNs concurrently.We evaluated the performance of our contributions in both simulation usingCooja simulator and experiment (only for ADUP) on TelosB motes. The resultsobtained in both simulation and experiment confirm the efficiency of our routingprotocols.

Face à la limitation de la modélisation paramétrique, nous avons proposé dans cette thèse une procédure standard pour combiner les données reçues a partir de Réseaux de capteurs sans fils (WSN) pour modéliser a l'aide de Réseaux de Neurones Artificiels (ANN). Des expériences sur la modélisation thermique ont permis de démontrer que la combinaison de WSN et d'ANN est capable de produire des modèles thermiques précis. Une nouvelle méthode de formation "Multi-Pattern Cross Training" (MPCT) a également été introduite dans ce travail. Cette méthode permet de fusionner les informations provenant de différentes sources de données d'entraînements indépendants (patterns) en un seul modèle ANN. D'autres expériences ont montré que les modèles formés par la méthode MPCT fournissent une meilleure performance de généralisation et que les erreurs de prévision sont réduites. De plus, le modèle de réseau neuronal basé sur la méthode MPCT a montré des avantages importants dans le multi-variable Model Prédictive Control (MPC). Les simulations numériques indiquent que le MPC basé sur le MPCT a surpassé le MPC multi-modèles au niveau de l'efficacité du contrôle. / A Wireless Sensor Network (WSN) consisting of autonomous sensor nodes can provide a rich stream of sensor data representing physical measurements. A well built Artificial Neural Network (ANN) model needs sufficient training data sources. Facing the limitation of traditional parametric modeling, this paper proposes a standard procedure of combining ANN and WSN sensor data in modeling. Experiments on indoor thermal modeling demonstrated that WSN together with ANN can lead to accurate fine grained indoor thermal models. A new training method "Multi-Pattern Cross Training" (MPCT) is also introduced in this work. This training method makes it possible to merge knowledge from different independent training data sources (patterns) into a single ANN model. Further experiments demonstrated that models trained by MPCT method shew better generalization performance and lower prediction errors in tests using different data sets. Also the MPCT based Neural Network Model has shown advantages in multi-variable Neural Network based Model Predictive Control (NNMPC). Software simulation and application results indicate that MPCT implemented NNMPC outperformed Multiple models based NNMPC in online control efficiency.

<p>In this thesis centralized routing methods for wireless sensor networks have been studied. The aim has been to prolong network lifetime by reducing the energy consumed by sensor-node communication.</p><p>Wireless sensor networks are rapidly becoming common in application areas where information from many sensors is to be collected and acted upon. The use of wireless sensor networks adds flexibility to the network, and the cost of cabling can be avoided.</p><p>Wireless sensor networks may consist of several hundreds of small devices, equipped with sensors (e.g. acoustic, seismic or image) that form a wireless network. Each sensor node collects information from its surroundings and sends it to a base station, either from sensor node to sensor node, or directly to the base station.</p><p>We have made simulations that show that asymmetric communication with multihop extends the lifetime of large wireless sensor networks. We have also investigated the usefulness of enforcing a minimum separation distance between cluster heads in a cluster based wireless sensor network. The results show that our sensor network performs up to 150% better when introducing a minimum separation distance between cluster heads. The simulations also show that the minimum separation distance resulting in the lowest energy consumption in our network varies with the number of clusters. We have also made an initial study of maximum lifetime routing in sparse wireless sensor networks to be able to see how different heuristic routing algorithms influence the energy consumption of individual sensor nodes, and thus the lifetime of a sparse sensor network. We have also compared the maximum lifetime of the heuristic algorithms to the maximum lifetime of an optimal routing solution. These simulations showed that for some types of applications the choice of heuristic algorithm is more important to prolong network lifetime, than for other types of applications.</p>

Most computing and communicating devices have been personal computers that were connected to Internet through a fixed network connection. It is believed that future communication devices will not be of this type. Instead the intelligence and communication capability will move into various objects that surround us. This is often referred to as the "Internet of Things" or "Wireless Embedded Internet". This thesis deals with video processing and communication in these types of systems. One application scenario that is dealt with in this thesis is real-time video transmission over wireless ad-hoc networks. Here a set of devices automatically form a network and start to communicate without the need for any previous infrastructure. These devices act as both hosts and routers and can build up large networks where they forward information for each other. We have identified two major problems when sending real-time video over wireless ad-hoc networks. One is the reactive design used by most ad-hoc routing protocols. When nodes move some links that are used in the communication path between the sender and the receiver may disappear. The reactive routing protocols wait until some links on the path breaks and then start to search for a new path. This will lead to long interruptions in packet delivery and does not work well for real-time video transmission. Instead we propose an approach where we identify when a route is about to break and start to search for new routes before this happen. This is called a proactive approach. Another problem is that video codecs are very sensitive for packet losses and at the same time the wireless ad-hoc network is very error prone. The most common way to handle lost packets in video codecs is to periodically insert frames that are not predictively coded. This method periodically corrects errors regardless there has been an error or not. The method we propose is to insert frames that are not predictively coded directly after a packet has been lost, and only if a packet has been lost. Another area that is dealt with in this thesis is video sensor networks. These are small devices that have communication and computational capacity, they are equipped with an image sensor so that they can capture video. Since these devices in general have very limited resources in terms of energy, computation, communication and memory they demand a lot of the video compression algorithms used. In standard video compression algorithms the complexity is high for the encoder while the decoder has low complexity and is just passively controlled by the encoder. We propose video compression algorithms for wireless video sensor networks where complexity is reduced in the encoder by moving some of the image analysis to the decoder side. We have implemented our approach on actual low-power sensor nodes to test our developed algorithms. Finally we have built a "Digital Zoo" that is a complete system including a large scale outdoor video sensor network. The goal is to use the collected data from the video sensor network to create new experiences for physical visitors in the zoo, or "cyber" visitors from home. Here several topics that relate to practical deployments of sensor networks are addressed.