Ambient intelligence in buildings : design and development of an interoperable Internet of Things platform

During many years, people and governments have been warned about the increasing levels of pollution and greenhouse gases (GHG) emissions that are endangering our lives on this planet. The Information and Communication Technology sector, usually known as the ICT sector, responsible for the computerization of the society, has been pinpointed as one of the most important sectors contributing to such a problem. Many efforts, however, have been put to shift the trend towards the utilization of renewable resources, such as wind or solar power. Even though governments have agreed to follow this path and avoid the usage of non-renewable energies, it is not enough. Although the ICT sector might seem an added problem due to the number of connected devices, technology improvements and hardware optimization enable new ways of fighting against global warming and GHG emissions. The aforementioned computerization has forced companies to evolve their work into a computer-assisted one. Due to this, companies are now forced to establish their main headquarters inside buildings for work coordination, connection and management. Due to this, buildings are becoming one of the most important issues regarding energy consumption. In order to cope with such problem, the Internet of Things (IoT) offers new paradigms and alternatives for leading the change. IoT is commonly defined as the network of physical and virtual objects that are capable of collecting surrounding data and exchanging it between them or through the Internet. Thanks to these networks, it is possible to monitor any thinkable metric inside buildings, and, then, utilize this information to build efficient automated systems, commonly known as Building Energy Management Systems (BEMS), capable of extracting conclusions on how to optimally and efficiently manage the resources of the building. ICT companies have foreseen this market opportunity that, paired with the appearance of smaller, efficient and more durable sensors, allows the development of efficient IoT systems. However, the lack of agreement and standardization creates chaos inside IoT, and the horizontal connectivity between such systems is still a challenge. Moreover, the vast amount of data to process requires the utilization of Big Data techniques to guarantee close to real-time responses. This thesis initially presents a standard Cloud-based IoT architecture that tries to cope with the aforementioned problems by employing a Cloud middleware that obfuscates the underlying hardware architecture and permits the aggregation of data from multiple heterogeneous sources. Also, sensor information is exposed to any third-party client after authentication. The utilization of automated IoT systems for managing building resources requires high reliability, resilience, and availability. The loss of sensor data is not permitted due to the negative consequences it might have, such as disruptive resource management. For this, it is mandatory to grant backup options to sensor networks in order to guarantee correct functioning in case of partial network disconnections. Additionally, the placement of the sensors inside the building must guarantee minimal energy consumption while fulfilling sensing requirements. Finally, a building resource management use case is presented by means of a simulation tool. The tool draws on occupants' probabilistic models and environmental condition models for actuating upon building elements to ensure optimal and efficient functioning. Occupants' comfort is also taken into consideration and the trade-off between the two metrics is studied. All the presented work is meant to deliver insights and tools for current and future IoT system implementations by setting the basis for standardization agreements yet to happen.Durant molts anys, s'ha alertat a la població i als governs sobre l'increment en els nivells de pol·lució i d'emissió de gasos d'efecte hivernacle, que estan posant en perill la nostra vida a la Terra. El sector de les Tecnologies de la Informació i Comunicació, normalment conegut com les TIC, responsable de la informatització de la societat, ha estat senyalat com un dels sectors més importants encarregat d'agreujar tal problema. Però, molt esforç s'està posant per revertir aquesta situació mitjançant l'ús de recursos renovables, com l'energia eòlica o solar. Tot i que els governs han acordat seguir dit camí i evitar l'ús d'energia no renovable tant com sigui possible, no és suficient per erradicar el problema. Encara que el sector de les TIC pugui semblar un problema afegit donada la gran quantitat i l'increment de dispositius connectats, les millores en tecnologia i en hardware estan habilitant noves maneres de lluitar contra l'escalfament global i l'emissió de gasos d'efecte hivernacle. La informatització, anteriorment mencionada, ha forçat a les empreses a evolucionar el seu model de negoci cap a un més enfocat a la utilització de xarxes d'ordinadors per gestionar els seus recursos. Per això, dites companyies s'estan veient forçades a establir les seves seus centrals dintre d'edificis, per tenir un major control sobre la coordinació, connexió i maneig dels seus recursos. Això està provocant un augment en el consum energètic dels edificis, que s'estan convertint en un dels principals problemes. Per poder fer front al problema, la Internet de les Coses o Internet of Things (IoT) ofereix nous paradigmes i alternatives per liderar el canvi. IoT es defineix com la xarxa d'objectes físics i virtuals, capaços de recol·lectar la informació per construir sistemes automatitzats, coneguts com a Sistemes de Gestió Energètica per Edificis, capaços d'extreure conclusions sobre com utilitzar de manera eficient i òptima els recursos de l'edifici. Companyies pertanyents a les TIC han previst aquesta oportunitat de mercat que, en sincronia amb l'aparició de sensors més petits, eficients i duradors, permeten el desenvolupament de sistemes IoT eficients. Però, la falta d'acord en quant a l'estandardització de dits sistemes està creant un escenari caòtic, ja que s'està fent impossible la connectivitat horitzontal entre dits sistemes. A més, la gran quantitat de dades a processar requereix la utilització de tècniques de Big Data per poder garantir respostes en temps acceptables. Aquesta tesi presenta, inicialment, una arquitectura IoT estàndard basada en la Neu, que tracta de fer front als problemes anteriorment presentats mitjançant l'ús d'un middleware allotjat a la Neu que ofusca l'arquitectura hardware subjacent i permet l'agregació de la informació originada des de múltiples fonts heterogènies. A més, la informació dels sensors s'exposa perquè qualsevol client de tercers pugui consultar-la, després d'haver-se autenticat. La utilització de sistemes IoT automatitzats per gestionar els recursos dels edificis requereix un alt nivell de fiabilitat, resistència i disponibilitat. La perduda d'informació no està permesa degut a les conseqüències negatives que podría suposar, com una mala presa de decisions. Per això, és obligatori atorgar opcions de backup a les xarxes de sensors per garantir un correcte funcionament inclús quan es produeixen desconnexions parcials de la xarxa. Addicionalment, la col·locació dels sensors dintre de l'edifici ha de garantir un consum energètic mínim dintre de les restriccions de desplegament imposades. Finalment, presentem un cas d'ús d'un Sistema de Gestió Energètica per Edificis mitjançant una eina de simulació. Dita eina utilitza com informació d'entrada models probabilístics sobre les accions dels ocupants i models sobre la condició ambiental per actuar sobre els elements de l'edifici i garantir un funcionament òptim i eficient. A més, el confort dels ocupants també es considera com mètrica a optimitzar. Donada la impossibilitat d’optimitzar les dues mètriques de manera conjunta, aquesta tesi també presenta un estudi sobre el trade-off que existeix entre elles. Tot el treball presentat està pensat per atorgar idees i eines pels sistemes IoT actuals i futurs, i assentar les bases per l’estandardització que encara està per arribar.Durante muchos años, se ha alertado a la población y a los gobiernos acerca del incremento en los niveles de polución y de emisión de gases de efecto invernadero, que están poniendo en peligro nuestra vida en la Tierra. El sector de las Tecnologías de la Información y Comunicación, normalmente conocido como las TIC, responsable de la informatización de la sociedad, ha sido señalada como uno de los sectores más importantes encargado de agravar tal problema. Sin embargo, mucho esfuerzo se está poniendo para revertir esta situación mediante el uso de recursos renovables, como la energía eólica o solar. A pesar de que los gobiernos han acordado seguir dicho camino y evitar el uso de energía no renovable tanto como sea posible, no es suficiente para erradicar el problema. Aunque el sector de las TIC pueda parecer un problema añadido dada la gran cantidad y el incremento de dispositivos conectados, las mejoras en tecnología y en hardware están habilitando nuevas maneras de luchar contra el calentamiento global y la emisión de gases de efecto invernadero. Durante las últimas décadas, compañías del sector público y privado conscientes del problema han centrado sus esfuerzos en la creación de soluciones orientadas a la eficiencia energética tanto a nivel de hardware como de software. Las nuevas redes troncales están siendo creadas con dispositivos eficientes y los proveedores de servicios de Internet tienden a crear sistemas conscientes de la energía para su optimización dentro de su dominio. Siguiendo esta tendencia, cualquier nuevo sistema creado y añadido a la red debe garantizar un cierto nivel de conciencia y un manejo óptimo de los recursos que utiliza. La informatización, anteriormente mencionada, ha forzado a las empresas a evolucionar su modelo de negocio hacia uno más enfocado en la utilización de redes de ordenadores para gestionar sus recursos. Por eso, dichas compañías se están viendo forzadas a establecer sus sedes centrales dentro de edificios, para tener un mayor control sobre la coordinación, conexión y manejo de sus recursos. Esto está provocando un aumento en el consumo energético de los edificios, que se están convirtiendo en uno de los principales problemas. Para poder hacer frente al problema, el Internet de las Cosas o Internet of Things (IoT) ofrece nuevos paradigmas y alternativas para liderar el cambio. IoT se define como la red de objetos físicos y virtuales, capaces de recolectar la información del entorno e intercambiarla entre los propios objetos o a través de Internet. Gracias a estas redes, es posible monitorizar cualquier métrica que podamos imaginar dentro de un edificio, y, después, utilizar dicha información para construir sistemas automatizados, conocidos como Sistemas de Gestión Energética para Edificios, capaces de extraer conclusiones sobre cómo utilizar de manera eficiente y óptima los recursos del edificio. Compañías pertenecientes a las TIC han previsto esta oportunidad de mercado que, en sincronía con la aparición de sensores más pequeños, eficientes y duraderos, permite el desarrollo de sistemas IoT eficientes. Sin embargo, la falta de acuerdo en cuanto a la estandarización de dichos sistemas está creando un escenario caótico, ya que se hace imposible la conectividad horizontal entre dichos sistemas. Además, la gran cantidad de datos a procesar requiere la utilización de técnicas de Big Data para poder garantizar respuestas en tiempos aceptables. Esta tesis presenta, inicialmente, una arquitectura IoT estándar basada en la Nube que trata de hacer frente a los problemas anteriormente presentados mediante el uso de un middleware alojado en la Nube que ofusca la arquitectura hardware subyacente y permite la agregación de la información originada des de múltiples fuentes heterogéneas. Además, la información de los sensores se expone para que cualquier cliente de terceros pueda consultarla, después de haberse autenticado. La utilización de sistemas IoT automatizados para manejar los recursos de los edificios requiere un alto nivel de fiabilidad, resistencia y disponibilidad. La pérdida de información no está permitida debido a las consecuencias negativas que podría suponer, como una mala toma de decisiones. Por eso, es obligatorio otorgar opciones de backup a las redes de sensores para garantizar su correcto funcionamiento incluso cuando se producen desconexiones parciales de la red. Adicionalmente, la colocación de los sensores dentro del edificio debe garantizar un consumo energético mínimo dentro de las restricciones de despliegue impuestas. En esta tesis, mejoramos el problema de colocación de los sensores para redes heterogéneas de sensores inalámbricos añadiendo restricciones de clustering o agrupamiento, para asegurar que cada tipo de sensor es capaz de obtener su métrica correspondiente, y restricciones de protección mediante la habilitación de rutas de transmisión secundarias. En cuanto a grandes redes homogéneas de sensores inalámbricos, esta tesis estudia aumentar su resiliencia mediante la identificación de los sensores más críticos. Finalmente, presentamos un caso de uso de un Sistema de Gestión Energética para Edificios mediante una herramienta de simulación. Dicha herramienta utiliza como información de entrada modelos probabilísticos sobre las acciones de los ocupantes y modelos sobre la condición ambiental para actuar sobre los elementos del edificio y garantizar un funcionamiento óptimo y eficiente. Además, el comfort de los ocupantes también se considera como métrica a optimizar. Dada la imposibilidad de optimizar las dos métricas de manera conjunta, esta tesis también presenta un estudio sobre el trade-off que existe entre ellas. Todo el trabajo presentado está pensado para otorgar ideas y herramientas para los sistemas IoT actuales y futuros, y asentar las bases para la estandarización que todavía está por llegar.Postprint (published version

A scalable multi-core architecture with heterogeneous memory structures for Dynamic Neuromorphic Asynchronous Processors (DYNAPs)

Neuromorphic computing systems comprise networks of neurons that use asynchronous events for both computation and communication. This type of representation offers several advantages in terms of bandwidth and power consumption in neuromorphic electronic systems. However, managing the traffic of asynchronous events in large scale systems is a daunting task, both in terms of circuit complexity and memory requirements. Here we present a novel routing methodology that employs both hierarchical and mesh routing strategies and combines heterogeneous memory structures for minimizing both memory requirements and latency, while maximizing programming flexibility to support a wide range of event-based neural network architectures, through parameter configuration. We validated the proposed scheme in a prototype multi-core neuromorphic processor chip that employs hybrid analog/digital circuits for emulating synapse and neuron dynamics together with asynchronous digital circuits for managing the address-event traffic. We present a theoretical analysis of the proposed connectivity scheme, describe the methods and circuits used to implement such scheme, and characterize the prototype chip. Finally, we demonstrate the use of the neuromorphic processor with a convolutional neural network for the real-time classification of visual symbols being flashed to a dynamic vision sensor (DVS) at high speed.Comment: 17 pages, 14 figure

The Chameleon Architecture for Streaming DSP Applications

We focus on architectures for streaming DSP applications such as wireless baseband processing and image processing. We aim at a single generic architecture that is capable of dealing with different DSP applications. This architecture has to be energy efficient and fault tolerant. We introduce a heterogeneous tiled architecture and present the details of a domain-specific reconfigurable tile processor called Montium. This reconfigurable processor has a small footprint (1.8 mm$^2$ in a 130 nm process), is power efficient and exploits the locality of reference principle. Reconfiguring the device is very fast, for example, loading the coefficients for a 200 tap FIR filter is done within 80 clock cycles. The tiles on the tiled architecture are connected to a Network-on-Chip (NoC) via a network interface (NI). Two NoCs have been developed: a packet-switched and a circuit-switched version. Both provide two types of services: guaranteed throughput (GT) and best effort (BE). For both NoCs estimates of power consumption are presented. The NI synchronizes data transfers, configures and starts/stops the tile processor. For dynamically mapping applications onto the tiled architecture, we introduce a run-time mapping tool

Adaptive multi-PHY IEEE802.15.4 TSCH in sub-GHz industrial wireless networks

To provide wireless coverage in challenging industrial environments, IEEE802.15.4 Time-Slotted Channel Hopping (TSCH) presents a robust medium access protocol. Using multiple Physical Layers (PHYs) could improve TSCH even more in these heterogeneous environments. However, TSCH only defines one fixedduration timeslot structure allowing one packet transmission. Using multiple PHYs with various data rates therefore does not yield any improvements because of this single-packet limitation combined with a fixed slot duration. We therefore defined two alternative timeslot structures allowing multiple packets transmissions to increase the throughput for higher data rate PHYs while meeting a fixed slot duration. In addition, we developed a flexible Link Quality Estimation (LQE) technique to dynamically switch between PHYs depending on the current environment. This paper covers a theoretical evaluation of the proposed slot structures in terms of throughput, energy consumption and memory constraints backed with an experimental validation, using a proof-of-concept implementation, which includes topology and PHY switching. Our results show that a 153% higher net throughput can be obtained with 84% of the original energy consumption and confirm our theoretical evaluation with a 99 % accuracy. Additionally, we showed that in a real-life testbed of 33 nodes, spanning three floors and covering 2550 m(2), a compact multi-PHY TSCH network can be formed. By distinguishing between reliable and high throughput PHYs, a maximum hop count of three was achieved with a maximum throughput of 219 kbps. Consequently, using multiple (dynamic) PHYs in a single TSCH network is possible while still being backwards compatible to the original fixed slot duration TSCH standard

Enabling Hardware Green Internet of Things: A review of Substantial Issues

Between now and the near future, the Internet of Things (IoT) will redesign the socio-ecological morphology of the human terrain. The IoT ecosystem deploys diverse sensor platforms connecting millions of heterogeneous objects through the Internet. Irrespective of sensor functionality, most sensors are low energy consumption devices and are designed to transmit sporadically or continuously. However, when we consider the millions of connected sensors powering various user applications, their energy efficiency (EE) becomes a critical issue. Therefore, the importance of EE in IoT technology, as well as the development of EE solutions for sustainable IoT technology, cannot be overemphasised. Propelled by this need, EE proposals are expected to address the EE issues in the IoT context. Consequently, many developments continue to emerge, and the need to highlight them to provide clear insights to researchers on eco-sustainable and green IoT technologies becomes a crucial task. To pursue a clear vision of green IoT, this study aims to present the current state-of-the art insights into energy saving practices and strategies on green IoT. The major contribution of this study includes reviews and discussions of substantial issues in the enabling of hardware green IoT, such as green machine to machine, green wireless sensor networks, green radio frequency identification, green microcontroller units, integrated circuits and processors. This review will contribute significantly towards the future implementation of green and eco-sustainable IoT

Joint optimization for wireless sensor networks in critical infrastructures

Energy optimization represents one of the main goals in wireless sensor network design where a typical sensor node has usually operated by making use of the battery with limited-capacity. In this thesis, the following main problems are addressed: first, the joint optimization of the energy consumption and the delay for conventional wireless sensor networks is presented. Second, the joint optimization of the information quality and energy consumption of the wireless sensor networks based structural health monitoring is outlined. Finally, the multi-objectives optimization of the former problem under several constraints is shown. In the first main problem, the following points are presented: we introduce a joint multi-objective optimization formulation for both energy and delay for most sensor nodes in various applications. Then, we present the Karush-Kuhn-Tucker analysis to demonstrate the optimal solution for each formulation. We introduce a method of determining the knee on the Pareto front curve, which meets the network designer interest for focusing on more practical solutions. The sensor node placement optimization has a significant role in wireless sensor networks, especially in structural health monitoring. In the second main problem of this work, the existing work optimizes the node placement and routing separately (by performing routing after carrying out the node placement). However, this approach does not guarantee the optimality of the overall solution. A joint optimization of sensor placement, routing, and flow assignment is introduced and is solved using mixed-integer programming modelling. In the third main problem of this study, we revisit the placement problem in wireless sensor networks of structural health monitoring by using multi-objective optimization. Furthermore, we take into consideration more constraints that were not taken into account before. This includes the maximum capacity per link and the node-disjoint routing. Since maximum capacity constraint is essential to study the data delivery over limited-capacity wireless links, node-disjoint routing is necessary to achieve load balancing and longer wireless sensor networks lifetime. We list the results of the previous problems, and then we evaluate the corresponding results

The Application of Ant Colony Optimization

The application of advanced analytics in science and technology is rapidly expanding, and developing optimization technics is critical to this expansion. Instead of relying on dated procedures, researchers can reap greater rewards by utilizing cutting-edge optimization techniques like population-based metaheuristic models, which can quickly generate a solution with acceptable quality. Ant Colony Optimization (ACO) is one the most critical and widely used models among heuristics and meta-heuristics. This book discusses ACO applications in Hybrid Electric Vehicles (HEVs), multi-robot systems, wireless multi-hop networks, and preventive, predictive maintenance