The Internet of Things (IoT) is an umbrella term for smart things connected to the Internet. Connected sensors may be used to the benefit of smart building management systems. This thesis describes the development of a sensor based building management system prototype, lightweight enough to run on a single network camera. The focus of the research was investigating if the system prototype was scalable, and capable of storing and analyzing data gathered from a large amount of sensors relevant to the field of building management. The prototype was developed through a five-stage systems development process, and evaluated using simulations and case studies. The finished prototype was able to gather and store data from a few hundred real-time sensors using limited hardware. Tests showed that the network camera should be capable of managing at least 100 sensors. The system itself is scalable with the use of more powerful hardware. However, using a distributed architecture would be preferable if more sensors are required. This could be achieved by creating a distributed network of cameras, where each camera manages its own set of sensors. This could both increase scalability and make the system more robust and reliable.

Ocean-surface Wireless Sensor Networks (WSN) are essential in various thalassic applications, such as maritime communication, ocean monitoring, seawater examination, pollution detection, etc. Formed by simple structured sensor nodes, ocean-surface WSN can improve the data transmission rate, enhance the monitoring resolution, expand the geographical coverage, extend the observation period, and lower the cost compared to the vessel-based monitoring approaches. Despite the importance and the broad applications of ocean-surface WSNs, little is known about the stability of the wireless links among the sensors. Especially, research suffers from the lack of an accurate model that describes the environmnetal effects, including the ocean surface movements and the wind speed on the link stability. The inappropriate understanding of link stability can result in network protocols that are not robust to environmental interruptions. Such a shortcoming decreases the network reliability and degrades the accuracy of the network planning. To compensate for this shortcoming, in this dissertation, we provide a thorough analysis on the stability of the wireless links over the ocean. In particular, we investigate and capture the effects of ocean waves on the link stability through the following steps. First, we use the linear wave theory and obtain a novel stochastic model of Line-of-Sight (LoS) links over the ocean based on the realistic behavior of ocean waves. Second, we present and prove an important theorem on the level-crossing of Wide Sense Stationary (WSS) random processes, and combine that with our stochastic model of LoS links to study two important indicators of link stability, i.e., the blockage probability and the blockage and connectivity periods. The former indicates the probability that a LoS link is blocked by the ocean waves while the latter determines the duration of on/off periods of the LoS links over the ocean. The aforementioned stability parameters directly affect different stages of network design, such as choosing the antenna height, planning the sensors' deployment distances, determining the packet length, designing the retransmission and scheduling strategies in the Medium Access Control (MAC) protocols and transport layer protocols, selecting the fragmentation threshold in Internet Protocol (IP), etc., which will be discussed in the respective chapters. In the last part of our dissertation, we investigate the problem of linear prediction of ocean waves, which has special importance in the design of ocean-surface WSNs. In this regard, we first introduce a low-complexity metric for effectiveness of k-step-ahead linear prediction, which we refer to as efficiency curve. The significance of efficiency curve becomes evident when we decide upon the number of previous samples in the linear prediction model, and determine the extent to which the predictor forecasts the future. After efficiency curve, we formulate an adaptive Wiener filter to predict the ocean waves and adapt the prediction model according to the environmental changes. / Doctor of Philosophy / Covering almost three quarters of the earth and supplying half of its oxygen, oceans are vital to the support of life on our planet. It is important to continuously monitor different parts of the ocean environment for tracking climate changes, detecting pollution, etc. However, the existing monitoring approaches have serious weaknesses, which prevent us from constantly monitoring the state of ocean, and drastically limit the geographical coverage. For instance, the traditional ocean monitoring system using oceanographic research vessels is time-consuming and expensive. Besides, it has low resolution in time and space, which poses serious challenges to oceanographers by providing under-sampled records of the ocean. To compensate for these defects, one of the promising alternatives is to employ Wireless Sensor Networks (WSN) which has many advantages, such as real-time access to data for a longer period of time and a larger geographical coverage of the ocean, higher resolution of monitoring, faster processing of collected data and instantaneous transmission to onshore monitoring centers. With the benefit of simple structure sensor nodes, ocean-surface WSNs can also decrease the cost by at least one order of magnitude compared to the conventional approaches. Despite the advantages that ocean surface WSN have over traditional ocean monitoring methods, ocean surface WSN research suffers from the lack of an accurate model that describes the stability of wireless links among sensor nodes. While some of the existing literature has developed accurate models of the electromagnetic wave propagation over the ocean surface, they have failed to consider the environmental effects, such as ocean waves on the stability of the links. To fill this void, in this dissertation, we investigate ocean surface waves' effects on the Line-of-Sight (LoS) link between the sensors in an ocean-surface WSN. Specifically, we derive the blockage probability, and the blockage and connectivity periods of LoS links between a transmitter and receiver pair due to wave movements. In addition to the link stability analysis, we dedicate the last part of this dissertation to look into the problem of linear prediction of ocean waves, which has special importance in the design process of ocean-surface WSNs. In this regard, we present a low-complexity metric for effectiveness of k-step-ahead linear prediction, and formulate an adaptive Wiener filter to predict the ocean waves and adapt the prediction model according to the environmental changes.

[ES] La industria se encuentra inmersa de pleno en la cuarta revolución industrial, y es gracias a la capacidad de digitalización y de procesamiento de grandes cantidades de datos, que se consigue mejorar y optimizar el rendimiento de los sistemas industriales actuales. Son muchos los paradigmas y conceptos que están dando forma a lo que se conoce como Industria 4.0, y uno de ellos ha sido el Internet de las Cosas (IoT: Internet of Things) o más concretamente el Internet Industrial de las Cosas (IIoT: Industrial Internet of Things), como se ha llamado al subconjunto con determinados requisitos orientados al sector industrial. Las redes de sensores inalámbricos (WSN: Wireless Sensor Networks) son tecnologías habilitadoras para estos sistemas IoT, ya que gracias a su fácil escalabilidad ofrecen gran capacidad de sensorización con un coste energético reducido. En el ámbito industrial, estas redes de sensores deben cumplir con requisitos estrictos de fiabilidad, y su aceptación está siendo lenta debido a que su robustez y facilidad de configuración no han podido rivalizar con las tecnologías clásicas. Con el desarrollo de esta tesis, se pretende hacer frente a determinados aspectos de mejora de las redes industriales de sensores inalámbricos. Para ello, se diseñan nuevos mecanismos para la sincronización, evaluando metodologías alternativas de enrutamiento y proponiendo modelos analíticos que permitan caracterizar fielmente el proceso de despliegue de estas redes, con el objetivo de cubrir aquellas lagunas que dejan los estándares y protocolos bajo estudio. Los mecanismos propuestos por el estándar IEEE 802.15.4e, en concreto el método de acceso al medio mediante TSCH (Time-Slotted Channel Hopping), presentan las bases sobre las que construir una red WSN fiable y robusta, y mediante los desarrollos propuestos en esta tesis se facilita su implantación en sistemas de Industria 4.0. / [CA] La indústria es troba de ple en la quarta revolució industrial, i és gràcies a la capacitat de digitalització i de processament de grans quantitats de dades, que s'aconsegueix millorar i optimitzar el rendiment dels sistemes industrials actuals. Són moltes els paradigmes i conceptes que estan donant forma al que es coneix com a Indústria 4.0, i una d'elles ha sigut la Internet de les Coses (IoT: Internet of Things) o més concretament la Internet Industrial de les Coses (IIoT: Industrial Internet of Things), com s'ha anomenat al subconjunt amb determinats requisits orientats al sector industrial. Les xarxes de sensors sense fils (WSN: Wireless Sensor Networks) són tecnologies habilitadores per a sistemes IoT, ja que gràcies a la seua fàcil escalabilitat ofereixen gran capacitat de digitalització amb un cost energètic reduït. En l'àmbit industrial, aquestes xarxes de sensors han de complir amb requisits estrictes, i la seua acceptació està sent lenta a causa de factors que fan que aquests sistemes no substituïsquen a les tecnologies clàssiques. Amb el desenvolupament d'aquesta tesi, es pretén fer front a determinats aspectes de millora de les xarxes industrials de sensors sense fils. Per a això, es dissenyen nous mecanismes per a la sincronització, avaluant metodologies alternatives d'encaminament i proposant models analítics que permeten caracteritzar fidelment el procés de desplegament d'aquestes xarxes, amb l'objectiu de cobrir aquelles llacunes que deixa l'estàndard. Els mecanismes proposats per l'estàndard IEEE 802.15.4, en concret el mètode d'accés al mitjà TSCH, presenten les bases sobre les quals construir una xarxa WSN fiable i robusta, i mitjançant els desenvolupaments proposats en aquesta tesi es facilita la seua implantació en sistemes d'Indústria 4.0. / [EN] The industry is fully engaged in the fourth industrial revolution. Due to digital transformation and the processing of large amounts of data, it is possible to improve the value chain and provide a real-time optimization for the current industrial systems. There are many paradigms and concepts that that fall under the umbrella of Industry 4.0, and one of them is the Internet of Things (IoT) or more specifically the Industrial Internet of Things (IIoT), as the subset with certain industry-oriented requirements is known. Wireless Sensor Networks (WSN) are an enabling technology for IoT systems, since its easy scalability offers a great sensorization capacity with a reduced energy cost. In the industrial field, these sensor networks must meet strict reliability requirements, so growth in the industrial market is slow as these systems fail to replace legacy technologies. This thesis addresses different aspects of improving industrial wireless sensor networks. To that end, new mechanisms for synchronization have been designed, evaluating alternative routing methodologies and proposing analytical models that allow a comprehensive characterization of the deployment process of these networks, aiming of covering those gaps left by the standard. The mechanisms proposed by the IEEE 802.15.4 standard, specifically the medium access control method Time-Slotted Channel Hopping (TSCH), present the bases to deploy a reliable and robust WSN network, and through the developments proposed in the thesis, it is possible smooth the way for its implementation in Industry 4.0 systems. / Vera Pérez, J. (2021). Diseño y evaluación de mecanismos de optimización en redes de sensores inalámbricas industriales [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/179700

[EN] The study, monitoring and control of environmental phenomena such as the air pollution, climate control or homogenization temperature and humidity indoors, or understanding and extinguishing forest fires pose a constant challenge to the personnel responsible and especially to the researchers. Compete this problematic economic sectors where greenhouse crops, post-harvest cameras, chillers tractor ruminant farms, smart buildings, urban environmental studies, among many others used. In all of them there is a concern for consistency in production, for energy efficiency and environmental impact generated. It is for this homogenization, dispersion and stratification of climate variables and gases, closely related to the ventilation of outdoor spaces and venues of interest. For the understanding of physical phenomena that are generated and subsequent improvement in the structural design and automatic systems, we need a modeling and energy analysis, there are currently several methods: tracer gas techniques, intensive data collection accompanied with box-empirical modeling Black and resolution simulation of physical laws that govern the behavior of study spaces. Previous techniques independently are insufficient to provide practical solutions and are costly or highly particularized to the case study. That is why the technique Fluid Dynamics Computer (CFD), as a tool that is used to numerically solve the equations of continuity and momentum that govern energy exchange system in order to obtain the fields of speed and direction airflow, the distribution of temperature, humidity and specific gases, becomes viable for later models were used with advanced control systems. However, the CFD technique requires a validation of the results with intensive shooting (space-time) data. Most published studies refer in their conclusions to the need for such validation of the data produced and how it is done. This document, by means of case studies, seeks to address the complexity of some environmental phenomena using models with the technique of CFD, whose validation also requires a protocol systematically executed a System Data Acquisition (DAS) spatially distributed and temporally controlled, which is achieved with the design and installation of a Wireless Sensor Network (WSN). Then it finds a first justification case where having the need to study the homogenization of the microclimate of a greenhouse, a DAS is created through the integration of different technologies wired. It shows in addition to extensive technical development, an urgent need to move to a non-wired technology to achieve the spatial coverage required in rooms or spaces with greater volume. It is followed by a case study in the laboratory, which seeks to understand the distribution and stratification of a gas in a chamber with controlled ventilation. Using a CFD model, which in turn feeds and validated with a database generated from a gas sensor WSN becomes. Then, a case study where space analysis moves to a real environment and highly complex, as it is a street in the city of Valencia, Spain. / [ES] El estudio, monitoreo y control de fenómenos ambientales como lo es la contaminación atmosférica, el control del clima o la homogenización de la temperatura y la humedad en recintos cerrados, o el entendimiento y extinción de incendios forestales, plantean un reto constante a el personal responsable y especialmente a los investigadores. Compete esta problemática a sectores económicos donde se utilice cultivos bajo invernadero, cámaras de pos-cosecha, cámaras de refrigeración de tractores, explotaciones de rumiantes, edificaciones inteligentes, estudios ambientales urbanos, entre muchos otros. En todas ellas existe una preocupación por la uniformidad en la producción, por una eficiencia energética y por el impacto ambiental que se genera. Se encuentra pues dicha homogenización, dispersión y estratificación de las variables climáticas y de los gases, íntimamente relacionada con la ventilación de los espacios exteriores y los recintos de interés. Para la comprensión de los fenómenos físicos que se generan y posterior mejora del diseño estructural y de los sistemas automáticos, es necesario un modelado y estudio energético, existiendo actualmente varias metodologías: Técnicas con gas trazador, toma intensiva de datos acompañada con modelado empírico tipo caja negra, y simulación por resolución de las leyes físicas que gobiernan el comportamiento de los espacios de estudio. Las anteriores técnicas de forma independiente resultan insuficientes para dar soluciones prácticas, y resultan costosas o altamente particularizadas al caso de estudio. Es por ello que la técnica de Dinámica de Fluidos Computacionales (CFD), como herramienta que se emplea para resolver numéricamente las ecuaciones de continuidad y de momento que rigen los intercambios energéticos de un sistema con el fin de obtener los campos de velocidad y de dirección del flujo de aire, la distribución de la temperatura, de la humedad y de gases específicos, se hace viable para obtener los modelos que posteriormente se utilizaran con sistemas de control avanzado. Sin embargo, la técnica CFD requiere de una validación de los resultados con una toma (espacio-tiempo) intensiva de datos. La mayoría de los trabajos publicados hacen referencia en sus conclusiones a la necesidad de dicha validación de los datos arrojados y la forma en la que se hace. El presente documento, por medio de unos casos de estudio, busca abordar la complejidad de algunos fenómenos ambientales haciendo uso de modelos con dicha técnica de CFD, cuya validación exige además de un protocolo sistemáticamente ejecutado, un Sistema de Adquisición de Datos (DAS) espacialmente distribuido y temporalmente controlado, lo cual se alcanza con el diseño e instalación de una Red Inalámbrica de Sensores (WSN). Se encuentra entonces un primer caso justificativo, donde teniendo la necesidad del estudio de la homogenización del microclima de un invernadero, se genera un DAS gracias a la integración de diferentes tecnologías cableadas. Demuestra además de un extenso desarrollo técnico, una imperiosa necesidad de pasar a una tecnología no cableada para lograr la cobertura espacial requerida en recintos o espacios con mayor volumen. Le sigue un caso de estudio a nivel de laboratorio, donde se busca entender la distribución y estratificación de un gas en un recinto con ventilación controlada. Se hace uso de un modelo con CFD, que a su vez se alimenta y valida con un banco de datos generado gracias a una WSN con sensores de gases. Luego, un caso de estudio donde el espacio de análisis se traslada a un ambiente real y con alta complejidad, como lo es una calle de la ciudad de Valencia, España. / [CA] L'estudi, monitoratge i control de fenòmens ambientals com és la contaminació atmosfèrica, el control del clima o l'homogeneïtzació de la temperatura i la humitat en recintes tancats, o l'enteniment i extinció d'incendis forestals, plantegen un repte constant al personal responsable i especialment als investigadors. Competeix aquesta problemàtica a sectors econòmics on s'utilitza cultius sota hivernacle, càmeres de pos-collita, cambres de refrigeració de tractors, explotacions de remugants, edificacions intel ligents, estudis ambientals urbans, entre molts altres. En totes elles hi ha una preocupació per la uniformitat en la producció, per una eficiència energètica i per l'impacte ambiental que es genera. Es troba doncs aquesta homogeneïtzació, dispersió i estratificació de les variables climàtiques i dels gasos, íntimament relacionada amb la ventilació dels espais exteriors i els recintes d'interès. Per a la comprensió dels fenòmens físics que es generen i posterior millora del disseny estructural i dels sistemes automàtics, cal un modelatge i estudi energètic, existint actualment diverses metodologies: Tècniques amb gas traçador, presa intensiva de dades acompanyada amb modelatge empíric tipus caixa negra, i simulació per resolució de les lleis físiques que governen el comportament dels espais d'estudi. Les anteriors tècniques de forma independent resulten insuficients per donar solucions pràctiques, i resulten costoses o altament particularitzades al cas d'estudi. És per això que la tècnica de dinàmica de fluids Computacionals (CFD), com a eina que s'uilitilza per resoldre numèricament les equacions de continuïtat i de moment que regeixen els intercanvis energètics d'un sistema per tal d'obtindre els camps de velocitat i de direcció del flux d'aire, la distribució de la temperatura, de la humitat i de gasos específics, es fa viable per obtindre els models que posteriorment s'utilitzaran amb sistemes de control avançat. No obstant això, la tècnica CFD requereix d'una validació dels resultats amb una presa (espai-temps) intensiva de dades. La majoria dels treballs publicats fan referència en les seves conclusions a la necessitat d'aquesta validació de les dades llançats i la forma en què es fa. El present document, per mitjà d'uns casos d'estudi, busca abordar la complexitat d'alguns fenòmens ambientals fent ús de models amb aquesta tècnica de CFD, la validació exigeix a més d'un protocol sistemàticament executat, un Sistema d'Adquisició de Dades (DAS) espacialment distribuït i temporalment controlat, la qual cosa s'aconsegueix amb el disseny i instal lació d'una Xarxa Sense fil de Sensors (WSN). Es troba llavors un primer cas justificatiu, on tenint la necessitat de l'estudi de l'homogeneïtzació del microclima d'un hivernacle, es genera un DAS gràcies a la integració de diferents tecnologies cablejades. Demostra a més d'un extens desenvolupament tècnic, una imperiosa necessitat de passar a una tecnologia no cablejada per aconseguir la cobertura espacial requerida en recintes o espais amb més volum. El segueix un cas d'estudi a nivell de laboratori, on es busca entendre la distribució i estratificació d'un gas en un recinte amb ventilació controlada. Es fa ús d'un model amb CFD, que al seu torn s'alimenta i valida amb un banc de dades generat gràcies a una WSN amb sensors de gasos. Després, un cas d'estudi on l'espai d'anàlisi es trasllada a un ambient real i amb alta complexitat, com ho és un carrer de la ciutat de València, Espanya. / Marulanda Tobón, A. (2016). MODELOS EN DINÁMICA DE FLUIDOS COMPUTACIONAL PARA APLICACIONES AMBIENTALES Y SU VALIDACIÓN CON SISTEMAS DE ADQUISICIÓN DE DATOS BASADOS EN REDES DE SENSORES INALÁMBRICAS [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/63461

Durant ces dernières années, de nombreux travaux de recherches ont été menés dans le domaine des réseaux multi-sauts sans fil à contraintes (MWNs: Multihop Wireless Networks). Grâce à l'évolution de la technologie des systèmes mico-electro-méchaniques (MEMS) et, depuis peu, les nanotechnologies, les MWNs sont une solution de choix pour une variété de problèmes. Le principal avantage de ces réseaux est leur faible coût de production qui permet de développer des applications ayant un unique cycle de vie. Cependant, si le coût de fabrication des nœuds constituant ce type de réseaux est assez faible, ces nœuds sont aussi limités en capacité en termes de: rayon de transmission radio, bande passante, puissance de calcul, mémoire, énergie, etc. Ainsi, les applications qui visent l'utilisation des MWNs doivent être conçues avec une grande précaution, et plus spécialement la conception de la fonction de routage, vu que les communications radio constituent la tâche la plus consommatrice d'énergie.Le but de cette thèse est d'analyser les différents défis et contraintes qui régissent la conception d'applications utilisant les MWNs. Ces contraintes se répartissent tout le long de la pile protocolaire. On trouve au niveau application des contraintes comme: la qualité de service, la tolérance aux pannes, le modèle de livraison de données au niveau application, etc. Au niveau réseau, on peut citer les problèmes de la dynamicité de la topologie réseau, la présence de trous, la mobilité, etc. Nos contributions dans cette thèse sont centrées sur l'optimisation de la fonction de routage en considérant les besoins de l'application et les contraintes du réseau. Premièrement, nous avons proposé un protocole de routage multi-chemin "en ligne" pour les applications orientées QoS utilisant des réseaux de capteurs multimédia. Ce protocole repose sur la construction de multiples chemins durant la transmission des paquets vers leur destination, c'est-à-dire sans découverte et construction des routes préalables. En permettant des transmissions parallèles, ce protocole améliore la transmission de bout-en-bout en maximisant la bande passante du chemin agrégé et en minimisant les délais. Ainsi, il permet de répondre aux exigences des applications orientées QoS.Deuxièmement, nous avons traité le problème du routage dans les réseaux mobiles tolérants aux délais. Nous avons commencé par étudier la connectivité intermittente entre les différents et nous avons extrait un modèle pour les contacts dans le but pouvoir prédire les future contacts entre les nœuds. En se basant sur ce modèle, nous avons proposé un protocole de routage, qui met à profit la position géographique des nœuds, leurs trajectoires, et la prédiction des futurs contacts dans le but d'améliorer les décisions de routage. Le protocole proposé permet la réduction des délais de bout-en-bout tout en utilisant d'une manière efficace les ressources limitées des nœuds que ce soit en termes de mémoire (pour le stockage des messages dans les files d'attentes) ou la puissance de calcul (pour l'exécution de l'algorithme de prédiction).Finalement, nous avons proposé un mécanisme de contrôle de la topologie avec un algorithme de routage des paquets pour les applications orientés évènement et qui utilisent des réseaux de capteurs sans fil statiques. Le contrôle de la topologie est réalisé à travers l'utilisation d'un algorithme distribué pour l'ordonnancement du cycle de service (sleep/awake). Les paramètres de l'algorithme proposé peuvent être réglés et ajustés en fonction de la taille du voisinage actif désiré (le nombre moyen de voisin actifs pour chaque nœud). Le mécanisme proposé assure un compromis entre le délai pour la notification d'un événement et la consommation d'énergie globale dans le réseau. / Great research efforts have been carried out in the field of challenged multihop wireless networks (MWNs). Thanks to the evolution of the Micro-Electro-Mechanical Systems (MEMS) technology and nanotechnologies, multihop wireless networks have been the solution of choice for a plethora of problems. The main advantage of these networks is their low manufacturing cost that permits one-time application lifecycle. However, if nodes are low-costly to produce, they are also less capable in terms of radio range, bandwidth, processing power, memory, energy, etc. Thus, applications need to be carefully designed and especially the routing task because radio communication is the most energy-consuming functionality and energy is the main issue for challenged multihop wireless networks.The aim of this thesis is to analyse the different challenges that govern the design of challenged multihop wireless networks such as applications challenges in terms of quality of service (QoS), fault-tolerance, data delivery model, etc., but also networking challenges in terms of dynamic network topology, topology voids, etc. Our contributions in this thesis focus on the optimization of routing under different application requirements and network constraints. First, we propose an online multipath routing protocol for QoS-based applications using wireless multimedia sensor networks. The proposed protocol relies on the construction of multiple paths while transmitting data packets to their destination, i.e. without prior topology discovery and path establishment. This protocol achieves parallel transmissions and enhances the end-to-end transmission by maximizing path bandwidth and minimizing the delays, and thus meets the requirements of QoS-based applications. Second, we tackle the problem of routing in mobile delay-tolerant networks by studying the intermittent connectivity of nodes and deriving a contact model in order to forecast future nodes' contacts. Based upon this contact model, we propose a routing protocol that makes use of nodes' locations, nodes' trajectories, and inter-node contact prediction in order to perform forwarding decisions. The proposed routing protocol achieves low end-to-end delays while using efficiently constrained nodes' resources in terms of memory (packet queue occupancy) and processing power (forecasting algorithm). Finally, we present a topology control mechanism along a packet forwarding algorithm for event-driven applications using stationary wireless sensor networks. Topology control is achieved by using a distributed duty-cycle scheduling algorithm. Algorithm parameters can be tuned according to the desired node's awake neighbourhood size. The proposed topology control mechanism ensures trade-off between event-reporting delay and energy consumption.

A l’avenir, l'agriculture et l'environnement vont pouvoir bénéficier de plus en plus de données hétérogènes collectées par des réseaux de capteurs sans fil (RCSF). Ces données alimentent généralement des outils d’aide à la décision (OAD). Dans cette thèse, nous nous intéressons spécifiquement aux systèmes sensibles et adaptatifs au contexte basés sur un RCSF et un OAD, dédiés au suivi de phénomènes naturels. Nous proposons ainsi une formalisation pour la conception et la mise en œuvre de ces systèmes. Le contexte considéré se compose de données issues du phénomène étudié mais également des capteurs sans fil (leur niveau d’énergie par exemple). Par l’utilisation des ontologies et de techniques de raisonnement, nous visons à maintenir le niveau de qualité de service (QdS) des données collectées (en accord avec le phénomène étudié) tant en préservant le fonctionnement du RCSF. Pour illustrer notre proposition, un cas d'utilisation complexe, l'étude des inondations dans un bassin hydrographique, est considéré. Cette thèse a produit un logiciel de simulation de ces systèmes qui intègre un système de simulation multi-agents (JADE) avec un moteur d’inférence à base de règles (Jess). / In the future, agriculture and environment will rely on more and more heterogeneous data collected by wireless sensor networks (WSN). These data are generally used in decision support systems (DSS). In this dissertation, we focus on adaptive context-aware systems based on WSN and DSS, dedicated to the monitoring of natural phenomena. Thus, a formalization for the design and the deployment of these kinds of systems is proposed. The considered context is established using the data from the studied phenomenon but also from the wireless sensors (e.g., their energy level). By the use of ontologies and reasoning techniques, we aim to maintain the required quality of service (QoS) level of the collected data (according to the studied phenomenon) while preserving the resources of the WSN. To illustrate our proposal, a complex use case, the study of floods in a watershed, is described. During this PhD thesis, a simulator for context-aware systems which integrates a multi-agent system (JADE) and a rule engine (Jess) has been developed.Keywords: ontologies, rule-based inferences, formalization, heterogeneous data, sensors data streams integration, WSN, limited resources, DSS, adaptive context-aware systems, QoS, agriculture, environment.

La motivation principale de cette thèse est de faire face à l'accroissement de la complexité des systèmes informatiques, qui, dans un futur proche ( de l'ordre de quelques années) risque fort d'être le principal frein à leur évolution et à leur développement. Aujourd'hui la tendance s'inverse et le coût de gestion humaine dépasse le coût des infrastructures matérielles et logicielles. De plus, l'administration manuelle de grands systèmes (applications distribuées, réseaux de capteurs, équipements réseaux) est non seulement lente mais aussi sujette à de nombreuses erreurs humaines. Un des domaines de recherche émergent est celui de l'informatique autonomique qui a pour but de rendre ces systèmes auto-gérés. Nous proposons une approche qui permet de décrire des politiques de gestion autonomiques de haut niveau. Ces politiques permettent au système d'assurer quatre propriétés fondamentales de l'auto-gestion: l'auto-guérison, l'auto-configuration, l'auto-protection et l'auto-optimisation. Nos contributions portent sur la spécification de diagrammes de description de politiques de gestion autonomiques appelés (S)PDD "(Sensor) Policy Description Diagrams". Ces diagrammes sont implémentés dans le gestionnaire autonomique TUNe et l'approche a été validée sur de nombreux systèmes: simulation électromagnétique répartie sur grille de calcul, réseaux de capteurs SunSPOT, répartiteur de calcul DIET. Une deuxième partie présente une modélisation mathématique de l’auto-optimisation pour un « datacenter ». Nous introduisons un problème de minimisation d’un critère intégrant d’une part la consommation électrique des équipements du réseau du « datacenter » et d’autre part la qualité de service des applications déployées sur le « datacenter ». Une heuristique permet de prendre en compte les contraintes dues aux fonctions de routage utilisées. / The main challenge of this thesis is to cope with the growing complexity of IT systems. In a near future (mainly the next few years) this complexity will prevent new developments and system evolutions. Today the trend is reversing and the managing costs are overtaking the hardware and software costs. Moreover, the manual administration of large systems (distributed applications, sensor networks, and network equipment) is not only slow but error-prone. An emerging research field called autonomic computing tries to bring up self-managed systems. We introduce an approach that enable the description of high level autonomic management policies. These policies allow the system to ensure four fundamental properties for self-management: self-healing, self-self-configuring, self-protecting and self-optimizing. We specify autonomic management Policy Description Diagrams (PDD) and implement them in Toulouse University Network (TUNe). We validated our approach on many systems: electromagnetic simulations distributed on computer grids (grid’5000), wireless sensor networks with SunSPOTs and the computing scheduler DIET. A second part of this thesis presents a mathematical modeling for self-optimizing datacenters. We introduce a minimization problem with a criterion integrating both the electrical consumption of the datacenter networking equipment and the quality of service of the deployed applications. A heuristic takes into account the routing functions used on the network.

Chaque année en Europe, 1.300.000 accidents de la route ont comme conséquence 1.700.000 blessés. Le coût financier d’accidents de la route est évalué à 160 milliards d’euros (approximativement le même coût aux Etats-Unis). VANET (Vehicular Ad-hoc NETwork) est une des technologies clés qui peut permettre de réduire d’une façon significative le nombre d’accidents de la route (e.g. message d’urgence signalant la présence d’un obstacle ou d’un véhicule en cas de brouillard). En plus de l’amélioration de la sécurité et du confort des conducteurs et des passagers, VANET peut contribuer à beaucoup d’applications potentielles telles que la prévision et la détection d’embouteillages, la gestion d’infrastructure de système de transport urbain (e.g. système de transport intelligent multimodal) etc. Dans cette thèse, je présenterai un système embarqué dédié à la communication inter-véhicule particulièrement pour les applications sécuritaires de passagers et de conducteurs. Nos efforts de recherche et de développement sont centrés sur deux principaux objectifs : minimiser le temps de latence intra-noeud et le délai de communication inter-véhicule en prenant en compte le changement dynamique du VANET. De ce fait pour atteindre ces objectifs, des nouvelles approches (e.g. inter-couche ‘Cross-layering’) ont été explorées pour respecter les contraintes de ressource (QoS, mémoire, CPU et énergie de la communication inter-véhicule) d’un système embarqué à faible coût. Le système de communication embarqué proposé comporte deux composants logiciels principaux : un protocole de communication dénommé CIVIC (Communication Inter Véhicule Intelligente et Coopérative) et un système d’exploitation temps réel appelé HEROS (Hybrid Event-driven and Real-time multitasking Operating System). CIVIC est un protocole de communication géographique à faible consommation énergétique et à faible temps de latence (délai de communication). HEROS gère contextuellement l’ensemble du système (matériel et logiciel) en minimisant le temps de latence et la consommation des ressources (CPU et mémoire). En outre, le protocole de communication CIVIC est équipé d’un système de localisation LCD-GPS (Low Cost Differential GPS). Pour tester et valider les différentes techniques et théories, la plateforme matérielle LiveNode (LImos Versatile Embedded wireless sensor NODE) a été utilisée. En effet, la plateforme LiveNode permet de développer et de prototyper rapidement des applications dans différents domaines. Le protocole de communication CIVIC est basé sur la technique de ‘broadcast’ à un saut ; de ce fait il est indépendant de la spécificité du réseau. Pour les expérimentations, seule la norme d’IEEE 802.15.4 (ZigBee) a été choisie comme médium d’accès sans fil. Il est à noter que le médium d’accès sans fil ZigBee a été adopté comme le médium standard pour les réseaux de capteurs sans fil (RCSFs) et le standard 6LoWPAN ; car il est peu coûteux et peu gourmand en énergie. Bien que le protocole de communication à l’origine soit conçu pour répondre aux exigences de VANET, ses domaines d’application ne sont pas limités à VANET. Par exemple il a été utilisé dans différents projets tels que MOBI+ (système de transport urbain intelligent) et NeT-ADDED (projet européen FP6 : agriculture de précision). Les VANETs et les RCSFs sont les réseaux fortement dynamiques, mais les causes de changement topologique de réseau sont différentes : dans le réseau VANET, il est dû à la mobilité des véhicules, et dans le RCSF, il est dû aux pannes des noeuds sans fil. Il est à noter que le VANET et le RCSF sont généralement considérés comme un sous-ensemble du réseau MANET (réseau ad-hoc mobile). Cependant, ils sont réellement tout à fait différents du MANET classique, et leurs similitudes et différences seront expliquées en détail dans la thèse. La contribution principale de mes travaux est le protocole CIVIC, qui échange des messages en basant sur l’information géographique des noeuds (position). (...) / Each year in Europe, 1,300,000 vehicle accidents result in 1,700,000 personal injuries. The financial cost of vehicle accidents is evaluated at 160 billion Euros (approximately the same cost in the USA). VANET (Vehicular Ad-Hoc NETwork) is a key technology that can enable hazard alarming applications to reduce the accident number. In addition to improve the safety for drivers and passengers, VANET can contribute to many potential applications such as detecting and predicting traffic jams, auto-optimizing the traffic flow, and helping disabled passengers to access public transports.This thesis will present an embedded communication system dedicated to VANET especially for the safety-related applications. Our design mainly tries to achieve two requirements: as one can imagine, the embedded communication system for VANET requires extra effort to deal with the highly dynamic network topology caused by moving vehicles, thus to shorten the intra-node system latency and inter-node network delay is essential requirement for such embedded communication system. Besides, a fundamental requirement for any practical embedded system is resource-awareness. Although the embedded communication system on vehicles may gain better hardware supports, the characteristics of embedded hardware still have to cope with resource constraints in terms of QoS, memory, CPU and energy. The embedded communication system involves two major software components: a routing protocol called CIVIC (Communication Inter Véhicule Intelligente et Coopérative) and an embedded operating system called HEROS (Hybrid Event-driven and Real-time multitasking Operating System). The former is a quick reaction and low resource consumption geographic protocol for inter-vehicle message transmissions; and the latter controls the whole system and assures intra-node resource awareness. In addition, the system can use a localization software solution called LCD-GPS (Low Cost Differential GPS) to improve the accuracy of locations. The hardware platform is LiveNode (LImos Versatile Embedded wireless sensor NODE), which is a versatile wireless sensor node enabling to implement rapidly a prototype for different application domains. The communication system is based on the one-hop broadcast, thus it does not have a strict limitation on network specification. For the experiments only, the IEEE 802.15.4 standard is chosen as the underlying wireless access medium. The standard is well known as a low-power consumption standard requiring low-cost devices. Notice that the IEEE 802.15.4 standard is also the wireless access medium of 6LoWPAN. Although the embedded communication system is originally designed to meet the requirements of VANET, but its application domains are not limited to VANET. For example, another network which can use the embedded communication system is WSN (Wireless Sensor Network). CIVIC was used to implement different real-world projects such MOBI+ (intelligent urban transportation system) and EU-FP6 NeT-ADDED (precision agriculture). Both VANET and WSN are highly dynamic networks, but the causes of changing network topology are different: the former is because of the high-mobility feature of vehicles, and the latter is because of the fault of wireless sensors. Note that, although VANET and WSN are both commonly considered as the subset of MANET (Mobile Ad-hoc NETwork), they are actually quite different from the classical MANET, and the similarities and differences will be further explained in the thesis. The major contribution of my works relates to the CIVIC protocol, which routes messages based on the geographic information. The related works of the thesis will focus on the geographic routing techniques, problems and solutions, but other related techniques will also be addressed. Note that, although some related projects were investigated but their implementation and experiment aspects were not detailed. (...)

Advances in wireless communication and microelectronics have led to the development of low-power compact sensor nodes (popularly called motes) that are capable of sensing, computing, and communication. A large number of these nodes can be deployed over some area of interest to form a multi-hop network, commonly referred to as a wireless sensor network (WSN). Typical applications of WSNs include, environment and process monitoring in industrial installations, forest fire detection, structural health monitoring, etc. In such applications where the variables to be measured are slowly varying, or the events to be monitored are rare, continuous sensing is unnecessary. Instead, the nodes, in order to conserve their battery power, can sleep-wake cycle whereby each node is allowed to independently alternate between an ON state and a low power OFF state. Sleep-wake cycling, while increasing the network lifetime, renders the network disconnected a large fraction of the time; however, connectivity can be established over time by transporting packets in a store-and-forward manner, whereby packets are held by a forwarding node until a suitable node wakes up in its neighborhood that can serve to forward the packet towards the destination. We are concerned with sleep-wake cycling multi-hop wireless networks whose main task is to carry sporadic alarms packets from sensing nodes to a sink node. Our objective is to design simple local-information based routing solutions for such networks. With this in mind, we propose a relay selection problem that arises at a forwarding node (which is currently holding the alarm packet) while choosing a next-hop relay node. The forwarder, as and when the relays wake-up, evaluating the goodness of a relay based on a “reward” metric (e.g., a function of the relay’s progress towards sink, and the power required to get the packet across), has to decide whether to forward to this relay or to wait for future ones (i.e., to stop or continue). The forwarder’s objective is to choose a relay so as to minimize a combination of the average delay incurred and the average reward achieved. A basic version of our relay selection problem is equivalent to the basic asset selling problem studied in the operations research literature. After reviewing the solution to the basic problem we will proceed to study a model with full information, referred to as the completely observable (CO) model, where the number of relays is exactly known to the forwarder. Formulating the problem as a Markov decision process (MDP) we will characterize the solution to the CO model in terms of recursively-computable threshold functions. Next, we consider the partially observable (PO) model where only a belief (probability mass function) on the number of relays is known. Hence, the PO model falls within the realm of partially observable MDPs. After incorporating our model into this framework we will characterize the solution in terms of stopping sets, which is the set of all belief states where it is optimal to stop. Our main contribution here is to obtain inner and outer bounds for the stopping sets. We next propose a variant where the relays, upon waking up, do not reveal their rewards immediately, but instead the forwarder can choose to probe the relay to know its reward, incurring a probing cost. Thus, to the existing set of stop and continue actions, we have added a new probe action. This model is motivated by the efforts required to learn the channel gains (by probing) in a wireless system. A key result we prove here is that the solution is characterized in terms of stage independent thresholds. Finally, we study a model comprising two forwarders which are competing against each other to choose a next-hop relay (one for each). Here, a relay is allowed to offer possibly different reward to each forwarder. We will first consider a complete information case where the reward pair of a relay is known to both the forwarders. Using stochastic game theory we will characterize the solution to this model in terms of Nash equilibrium policy pairs (NEPPs). We obtain results illustrating the structure of NEPPs. Next, we study a partial information model where each forwarder gets to observe only its reward value. Towards obtaining the solution for this model, we will first formulate a Bayesian game which is effectively played by both the forwarders at each stage. Next, for this Bayesian game we prove the existence of Nash equilibrium strategies within the class of threshold strategies. This result will enable us to construct NEPPs for the partial information model. Although our primary contribution from the thesis is the theoretical study of the above mentioned variants of the basic relay selection model, we have also conducted extensive simulations to study the end-to-end performance obtained by applying the solution to these models at each hop en-route to the sink in a sleep-wake cycling WSN.

This thesis presents the development of a Sensor Tower Platform (STP) comprised of an array of Passive Infra-Red (PIR) sensors along with a classification algorithm that enables the STP to distinguish between human intrusion, animal intrusion and clutter arising from wind-blown vegetative movement in an outdoor environment. The research was motivated by the aim of exploring the potential use of wireless sensor networks (WSNs) as an early-warning system to help mitigate human-wildlife conflicts occurring at the edge of a forest. While PIR sensors are in commonplace use in indoor settings, their use in an outdoor environment is hampered by the fact that they are prone to false alarms arising from wind-blown vegetation. Every PIR sensor is made up of one or more pairs of pyroelectric pixels arranged in a plane, and the orientation of interest in this thesis is one in which this plane is a vertical plane, i.e., a plane perpendicular to the ground plane. The intersection of the Field Of View (FOV) of the PIR sensor with a second vertical plane that lies within the FOV of the PIR sensor, is called the virtual pixel array (VPA). The structure of the VPA corresponding to the plane along which intruder motion takes place determines the form of the signal generated by the PIR sensor. The STP developed in this thesis employs an array of PIR sensors designed so as to result in a VPA that makes it easier to discriminate between human and animal intrusion while keeping to a small level false alarms arising from vegetative motion. The design was carried out in iterative fashion, with each successive iteration separated by a lengthy testing phase. There were a total of 5 design iterations spanning a total period of 14 months. Given the inherent challenges involved in gathering data corresponding to animal intrusion, the testing of the SP was carried out both using real-world data and through simulation. Simulation was carried out by developing a tool that employed animation software to simulate intruder and animal motion as well as some limited models of wind-blown vegetation. More specifically, the simulation tool employed 3-dimensional models of intruder and shrub motion that were developed using the popular animation software Blender. The simulated output signal of the PIR sensor was then generated by calculating the area of the 3-dimensional intruder when projected onto the VPA of the STP. An algorithm for efficiently calculating this to a good degree of approximation was implemented in Open Graphics Library (OpenGL). The simulation tool was useful both for evaluating various competing design alternatives as well as for developing an intuition for the kind of signals the SP would generate without the need for time-consuming and challenging animal-motion data collection. Real-world data corresponding to human motion was gathered on the campus of the Indian Institute of Science (IISc), while animal data was recorded at a dog-trainer facility in Kengeri as well as the Bannerghatta Biological Park, both located in the outskirts of Bengaluru. The array of PIR sensors was designed so as to result in a VPA that had good spatial resolution. The spatial resolution capabilities of the STP permitted distinguishing between human and animal motion with good accuracy based on low-complexity, signal-energy computations. Rejecting false alarms arising from vegetative movement proved to be more challenging. While the inherent spatial resolution of the STP was very helpful, an alternative approach turned out to have much higher accuracy, although it is computationally more intensive. Under this approach, the intruder signal, either human or animal, was modelled as a chirp waveform. When the intruder moves along a circular arc surrounding the STP, the resulting signal is periodic with constant frequency. However, when the intruder moves along a more likely straight-line path, the resultant signal has a strong chirp component. Clutter signals arising from vegetative motion does not exhibit this chirp behavior and an algorithm that exploited this difference turned in a classification accuracy in excess of 97%.