Semantic Gateway as a Service architecture for IoT Interoperability

The Internet of Things (IoT) is set to occupy a substantial component of future Internet. The IoT connects sensors and devices that record physical observations to applications and services of the Internet. As a successor to technologies such as RFID and Wireless Sensor Networks (WSN), the IoT has stumbled into vertical silos of proprietary systems, providing little or no interoperability with similar systems. As the IoT represents future state of the Internet, an intelligent and scalable architecture is required to provide connectivity between these silos, enabling discovery of physical sensors and interpretation of messages between things. This paper proposes a gateway and Semantic Web enabled IoT architecture to provide interoperability between systems using established communication and data standards. The Semantic Gateway as Service (SGS) allows translation between messaging protocols such as XMPP, CoAP and MQTT via a multi-protocol proxy architecture. Utilization of broadly accepted specifications such as W3C's Semantic Sensor Network (SSN) ontology for semantic annotations of sensor data provide semantic interoperability between messages and support semantic reasoning to obtain higher-level actionable knowledge from low-level sensor data.Comment: 16 page

A holistic approach to ZigBee performance enhancement for home automation networks

Wireless home automation networks are gaining importance for smart homes. In this ambit, ZigBee networks play an important role. The ZigBee specification defines a default set of protocol stack parameters and mechanisms that is further refined by the ZigBee Home Automation application profile. In a holistic approach, we analyze how the network performance is affected with the tuning of parameters and mechanisms across multiple layers of the ZigBee protocol stack and investigate possible performance gains by implementing and testing alternative settings. The evaluations are carried out in a testbed of 57 TelosB motes. The results show that considerable performance improvements can be achieved by using alternative protocol stack configurations. From these results, we derive two improved protocol stack configurations for ZigBee wireless home automation networks that are validated in various network scenarios. In our experiments, these improved configurations yield a relative packet delivery ratio increase of up to 33.6%, a delay decrease of up to 66.6% and an improvement of the energy efficiency for battery powered devices of up to 48.7%, obtainable without incurring any overhead to the network.Postprint (published version

Secure Certificate Management and Device Enrollment at IoT Scale.

The Internet of Things (IoT) is expected to comprise of over 20 billion devices connected to the Internet by the year 2020, and support mission critical applications such as health care, road safety and emergency services to name a few. This massive scale of IoT device deployment, heterogeneity of devices and applications, and the autonomous nature of the decision making process introduces new security requirements and challenges. The devices must be securely bootstrapped in to the network to provide secure inter--device communication and also, the applications must be able to authenticate and authorize these devices to provide the relevant services. In today's Internet, Public Key Infrastructure (PKI) is widely used to provide authenticity, encryption and data integrity during network communication through the use of digital certificates. This thesis investigates the key aspects for deploying a PKI security solution in an IoT ecosystem, ranging from deploying certificates on new devices (bootstrapping) to complete life cycle management of these certificates. We believe that the current PKI can be, with suitable enhancements, used to provide the efficiency, scalability and flexibility needed for IoT security. This thesis provides a survey of key aspects for deploying PKI security solution in IoT ecosystem. We investigate different certificate management protocols and motivate the applicability of enhanced security over transport (EST) protocol for IoT PKI solution. In addition, we propose a PKI deployment model and the bootstrap mechanism to bring up an IoT device and provision it with a digital certificate. Furthermore, we provide a prototype implementation to demonstrate certificate enrollment procedure with an EST server

New Architectures for ubiquitous networks : use and adaptation of internet protocols over wireless sensor networks

This thesis focuses on the study of low-resource demanding protocols, communication techniques and software solutions to evaluate, optimise and implement Web service in WSNs. We start analysing the Web service architectures in order to choose the most appropriate for the constraints of WSNs, which is REST. Based on this analysis, we review the state-of-the-art of protocols that allows implementing REST Web services. To this end, we adopt the IEEE 802.15.4 standard for the physical and data-link layers, 6LoWPAN for the network layer and CoAP for the application layer. 6LoWPAN defines two forwarding techniques, which are called mesh under (MU) and route over (RO). It also provides a mechanism to fragment packets, which is called 6LoWPAN fragmentation. In part of the thesis, we study the effects that MU and RO have on communications using 6LoWPAN fragmentation. In particular, MU does not prevent forwarding unnecessary fragments and out-of-order delivery, which could lead to an inefficient use of bandwidth and a growth of energy consumption. We propose, then, a novel technique able to improve the performance of MU with fragmented packets, which we refer to as controlled mesh under (CMU). The results of a performance evaluation in a real WSN show that CMU is able to enhance the performance of MU by reducing its packet loss and end-to-end delay. In 6LoWPAN fragmentation, the loss of a fragment forces the retransmission of the entire packet. To overcome this limitation, CoAP defines blockwise transfer. It splits the packet into blocks and sends each one in reliable transactions, which introduces a significant communication overhead. We propose a novel analytical model to study blockwise and 6LoWPAN fragmentation, which is validated trough Monte Carlo simulations. Both techniques are compared in terms of reliability and delay. The results show that 6LoWPAN fragmentation is preferable for delay-constrained applications. For highly congested networks, blockwise slightly outperforms 6LoWPAN fragmentation in terms of reliability. CoAP defines the observe option to allow a client to register to a resource exposed by a server and to receive updates of its state. Existing QoS in the observe option supports partially timeliness. It allows specifying the validity of an update but it does not guarantee its on-time delivery. This approach is inefficient and does not consider applications, i.e. e-health, that requires the delivery of an update within a deadline. With this limitation in mind, we design and evaluate a novel mechanism for update delivery based on priority. The evaluation proves that implementing a delivery order improves the delay and delivery ratio of updates. Our proposal is also able to reduce the energy consumption allowing clients to express the class of updates that they wish to receive. In part of this thesis, we present our original library for TinyOS, which we referred to as TinyCoAP, and the design and implementation of a CoAP proxy. We compare TinyCoAP to CoapBlip, which is the CoAP implementation distributed with TinyOS. TinyCoAP proves to be able to reach a high code optimization and to reduce the impact over the memory of WSN nodes. The evaluation includes also the analysis of the CoAP reliability mechanism, which was still uncovered in the literature. As a novelty, we also compare CoAP with HTTP considering different solutions for the transport layer protocol such as UDP and persistent TCP connections. The CoAP proxy enables Web applications to transparently access the resources hosted in CoAP devices. It supports long-lived communications by including the WebSocket protocol. It also supports Web applications that use the traditional HTTP long-polling technique. Finally, one of the main contributions of the proxy design is the proposal of a standard URI path format to be used by Web applications to access to a CoAP resource.Esta tesis se enfoca en el estudio de protocolos de bajo consumo, técnicas de comunicación y software con el fin de evaluar, optimizar y desarrollar servicios Web en WSNs. Empezamos analizando la arquitectura de servicios Web con el objetivo de elegir la arquitectura más apropiada debido a las limitaciones de WSNs. Ésta se denomina REST. En base a este análisis, revisamos el estado del arte de los protocolos que permiten desarrollar servicios Web. Con este objetivo adoptamos el estándar IEEE 802.15.4 por la capa física y de enlace, 6LoWPAN por la de red y CoAP por la capa de aplicación. 6LoWPAN define dos técnicas de enrutamiento, denominadas 'Mesh Under' (MU) y 'Route Over' (RO). Asimismo ofrece un mecanismo para fragmentar paquetes, llamado 6LoWPAN fragmentation. En parte de la tesis estudiamos los efectos que MU y RO tienen sobre la comunicación que utiliza 6LoWPAN fragmentation. En particular, MU no previene enrutar fragmentos innecesarios y la entrega fuera de orden, lo cual podría provocar un uso ineficiente de ancho de banda y un crecimiento del consumo energía. Proponemos entonces nueva técnica capaz de mejorar las prestaciones de MU con paquetes fragmentados que denominamos 'Controlled Mesh Under' (CMU). Los resultados de una evaluación en una WSN real demuestran que CMU es capaz de mejorar las prestaciones de MU reduciendo la pérdida de paquetes y el retraso end-to-end. En 6LoWPAN fragmentation, la pérdida de un fragmento causa la retransmisión del paquete entero. Para evitar esta limitación CoAP define blockwise transfer. Esto divide el paquete en bloques y los envía en comunicaciones fiables provocando overhead. Proponemos un nuevo modelo analítico para estudiar blockwise y 6LoWPAN fragmentation cuya validación se realiza mediante simulaciones de Monte Carlo. Ambas técnicas se comparan en términos de fiabilidad y retraso. Los resultados muestran que es preferible usar 6LoWPAN fragmentation para las aplicaciones con restricciones en retraso. Para las redes mas congestionadas, blockwise mejora ligeramente 6LoWPAN fragmentation en términos de fiabilidad. CoAP define la opción observe para permitir a un cliente registrarse a un recurso proporcionado por un servidor y recibir actualizaciones de su estado. La QoS ofrecida por la opción observe proporciona soporte parcial por el timeliness. Esta permite especificar la validez de una actualización pero no garantiza su entrega a tiempo. Este enfoque es ineficiente y no incluye aplicaciones, como por ejemplo e-health que requieren la entrega de las actualizaciones en un plazo determinado. Teniendo en cuenta esta limitación, diseñamos y evaluamos un mecanismo novedoso para la entrega de actualizaciones basada en la prioridad. La evaluación demuestra que la implementación de una orden de entrega mejora la tasa de llegada y el retraso de las actualizaciones. Nuestra propuesta es capaz de reducir el consumo de energía permitiendo a los clientes expresar el tipo de actualización que desean recibir. En parte de esta tesis presentamos nuestra librería original pro TinyOS a la que nos referimos como TinyCoAP, así como el diseño y desarrollo de un Proxy CoAP. Comparamos TinyCoAP a CoapBlip, que es la aplicación distribuida con TinyOS. TinyCoAP demuestra ser capaz de alcanzar una alta optimización de código y reducir el impacto sobre la memoria de nodos de WSNs. La evaluación también incluye el análisis de la fiabilidad de CoAP que no había sido estudiada en la literatura. Como novedad también comparamos CoAP con HTTP, considerando diferentes soluciones para el protocolo de transporte como UDP y conexiones TCP persistentes. El Proxy CoAP permite a las aplicaciones Web acceder de manera transparente a los recursos almacenados en dispositivos CoAP. Éste incluye el protocolo WebSocket, que permite el establecimiento de conexiones long-lived. También permite el uso de aplicaciones Web con la tradicional técnica HTTP long-pollin

Aplicaciones de SWE en entornos industriales

[EN] This thesis has been created within the framework of the interoperability of the networks of sensors in industrial environments, using standard SWE (Sensor Web Enablement). It has developed from the participation in different research projects, within the research group SATRD (Distributed Real Time Systems and Applications) of the Communications Department of the UPV. Has gone a long time since the appearance of the first sensors that were only able to respond to a stimulus, to the concept of sensor web, where sensors can be remotely configured, perform actions and process and integrate data from other sensors. Nowadays, the use of networks of sensors or WSN (Wireless Sensor Networks) is widespread in several fields, to gather information, which can then be used by other applications. As it increases its use, it is necessary to combine or add data from sensors of different WSN, which is not always possible, due to the lack of interoperability between different manufacturers. That is why OGC (Open Geospatial Consortium) founded SWE, in order to develop standards for access to sensors via the Internet and thus improve the interoperability. For these reasons, in this thesis is specified an IoT architecture (Internet of Things) generically, so that it can be extended to multiple environments. The I3WSN architecture is designed for monitoring and control systems, ensuring interoperability between the different elements through the integration of SWE standards. After the design, the application of the architecture is carried out in three different contexts, associated with three research projects. The first of them, in order to monitor and manage the workers' health in industrial environments, based on environmental and medical data, within the project FASyS (Fabrica Absolutamente Segura y Saludable). Secondly, to ensure the level of assurance of a smart grid environment, from the capture of the security information of all its elements, in the UniverSEC project. Finally, to manage efficiently and intelligently transport freight containers, from traffic data in real time, in the project STIMULO.[ES] Esta tesis se ha creado en el marco de la interoperabilidad de las redes de sensores en entornos industriales, mediante la utilización del estándar SWE (Sensor Web Enablement). Se ha desarrollado a partir de la participación en diferentes proyectos de investigación, dentro del grupo de investigación SATRD (Sistemas y Aplicaciones de Tiempo Real Distribuidos) del Departamento de Comunicaciones de la UPV. Ha pasado mucho tiempo desde la aparición de los primeros sensores que únicamente eran capaces de responder frente a un estímulo, hasta el concepto de sensor web, donde los sensores pueden ser configurados de forma remota, realizar acciones y procesar e integrar datos de otros sensores. Hoy en día, la utilización de redes de sensores o WSN (Wireless Sensor Networks) está ampliamente extendida en diversos ámbitos, para recopilar información, que luego pueda ser utilizada por otras aplicaciones. A medida que aumenta su utilización, surge la necesidad de combinar o agregar datos de sensores de distintas WSN, lo cual no siempre es posible, debido a la falta de interoperabilidad entre los distintos fabricantes. Es por ello que OGC (Open Geospatial Consortium) fundó SWE, con el fin de desarrollar estándares para el acceso a sensores a través de Internet y así mejorar la interoperabilidad. Por estos motivos, en esta tesis se ha especificado una arquitectura IoT (Internet of Things) de forma genérica, para que se pueda extender a múltiples entornos. La arquitectura I3WSN se ha diseñado para la monitorización y el control de sistemas, garantizando la interoperabilidad entre los distintos elementos gracias a la integración de los estándares de SWE. Tras el diseño, se ha llevado a cabo la aplicación de la arquitectura en tres contextos distintos, asociados a tres proyectos de investigación. El primero de ellos, con el objetivo de monitorizar y gestionar la salud de los trabajadores en entornos industriales, a partir de datos del entorno y datos médicos, dentro del proyecto FASyS (Fabrica Absolutamente Segura y Saludable). El segundo, para garantizar el nivel de aseguramiento de un entorno smart grid, a partir de la captura de la información de seguridad de todos sus elementos, en el proyecto UniverSEC. Y por último, para gestionar de forma eficiente e inteligente el transporte de contenedores de mercancías, a partir de los datos de tráfico en tiempo real, en el proyecto STIMULO.[CA] Aquesta tesi ha estat creada en el marc de la interoperabilitat de les xarxes de sensors en entorns industrialitzats, utilitzant l'estàndard SWE (Sensor Web capacitació). S'ha desenvolupat des de la participació en diversos projectes d'investigació, dins del grup d'investigació SATRD (Sistemes i Aplicacions de Temps Real Distribuïts) del Departament de Comunicació de la UPV. Ha passat molt temps des de l'aparició dels primers sensors que només eren capaços de respondre a un estímul, fins al concepte de sensor web, on els sensors es poden configurar remotament, realitzar accions i processar i integrar les dades d'altres sensors. Avui en dia, l'ús de xarxes de sensors o WSN (Wireless Sensor Networks) està àmpliament estesa en diversos àmbits, per a recollir informació, que desprès puga ser utilitzada per altres aplicacions. A mesura que augmenta el seu ús, sorgeix la necessitat de combinar o afegir dades de sensors de diferents WSN, que no sempre és possible, degut a la falta d'interoperabilitat entre els diferents fabricants. És per això que OGC (Open Geospatial Consortium) va fundar SWE, per desenvolupar estàndards per l'accés de sensors a Internet i així millorar la interoperabilitat. Per aquests motius, en aquesta tesi s'ha especificat una arquitectura IoT (Internet of Things) de forma genèrica, per tal que es puga estendre a múltiples entorns. L'arquitectura I3WSN s'ha dissenyat per la monitorització i el control de sistemes, garantint la interoperabilitat entre els diferents elements gràcies a la integració dels estàndards de SWE. Després el disseny, s'ha dut a terme l'aplicació de l'arquitectura en tres contextos diferents, associats amb tres projectes d'investigació. El primer d'ells, amb la finalitat de monitoritzar i gestionar la salut dels treballadors en entorns industrials, a partir de dades ambientals i dades mèdiques, dins del projecte FASyS (Fabrica Absolutamente Segura y Saludable). El segon, per garantir el nivell d'assegurament d'un entorn de smart grid, a partir de la captura de la informació de seguretat de tots els seus elements, en el projecte UniverSEC. I finalment, per gestionar de manera eficient i intel·ligent el transport de contenidors de mercaderies, a partir de les dades de trànsit en temps real, en el projecte STIMULO.Giménez Salazar, P. (2015). Aplicaciones de SWE en entornos industriales [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/51282TESI

Improvements to end-to-end performance of low-power wireless networks

Over the last decades, wireless technologies have become an important part of our daily lives. A plentitude of new types of networks based on wireless technologies have emerged, often replacing wired solutions. In this development, not only the number and the types of devices equipped with wireless transceivers have significantly increased, also the variety of wireless technologies has grown considerably. Moreover, Internet access for wireless devices has paved the way for a large variety of new private, business, and research applications. Great efforts have been made by the research community and the industry to develop standards, specifications, and communication protocols for networks of constrained devices, we refer to as Wireless Sensor Networks (WSNs). The Institute of Electrical and Electronics Engineers (IEEE) defined the 802.15.4 standard for Personal Area Networks (PANs). With the introduction of an adaptation layer which makes IEEE 802.15.4 networks IPv6-capable, interconnecting billions of constrained devices has become possible and is expected to become a reality in the near future. The vision that embraces the idea of interweaving Internet technology with any type of smart objects, such as wearable devices or sensors of a WSN, is called the Internet of Things (IoT). The main goal of this thesis is the improvement of the performance of low-power wireless networks. Given the wide scope of application scenarios and networking solutions proposed for such networks, the development and optimization of communication protocols for wireless low-power devices is a challenging task: The hardware restrictions of constrained devices, specific application scenarios that may vary from one network to another, and the integration of WSNs into the IoT require new approaches to the design and evaluation of communication protocols. To face these challenges and to find solutions for them, research needs to be carried out. Mechanisms and parameter settings of communication protocol stacks for WSNs that are crucial to the network performance need to be identified, optimized, and complemented by adding new ones. The first contribution of this thesis is the improvement of end-to-end performance for IEEE 802.15.4-based PANs, where default parameter settings of common communication protocols are analyzed and evaluated with regard to their impact on the network performance. Physical evaluations are carried out in a large testbed, addressing the important question of whether the default and allowed range settings defined for common communication protocols are efficient or whether alternative settings may yield a better performance. The second contribution of this thesis is the improvement of end-to-end performance for ZigBee wireless HA networks. ZigBee is an important standard for low-power wireless networks and the investigations carried out address the crucial lack of investigation the ZigBee HA performance evaluations through physical experiments and potential ways to improve the network performance based on these experiments. Eventually, this thesis focuses on the improvement of the congestion control (CC) mechanism applied by the Constrained Application Protocol (CoAP) used in IoT communications. For the handling of the possible congestion in the IoT produced by the plethora of the devices and/or link errors innate to low-power radio communications, the default CC mechanism it lacks an advanced CC algorithm. Given CoAP's high relevance for IoT communications, an advanced CC algorithm should be capable of adapting to these particularities of IoT communications. This thesis contributes to this topic with the design and optimization of the CoAP Advanced Congestion Control/Simple (CoCoA) protocol, an advanced CC mechanism for CoAP.The investigations of advanced CC mechanisms for CoAP involve extensive performance evaluations in simulated networks and physical experiments in real testbeds using different communication technologies.En les últimes dècades, les tecnologies sense fils s'han convertit en una part important de la nostra vida quotidiana. Una àmplia varietat de nous tipus de xarxes basades en tecnologies sense fils han sorgit, sovint reemplaçant solucions cablejades. En aquest desenvolupament, no només el nombre i els tipus de dispositius equipats amb transceptors sense fils han augmentat significativament, també la varietat de tecnologies sense fils ha crescut de manera considerable. D'altra banda, l'accés a Internet per als dispositius sense fils ha donat pas a una gran varietat de noves aplicacions privades, comercials i d'investigació. La comunitat científica i la indústria han fet grans esforços per desenvolupar normes, especificacions i protocols de comunicació per a xarxes de sensors sense fils (WSNs). L'Institut d'Enginyeria Elèctrica i Electrònica (IEEE) defineix l'estàndard 802.15.4 per a xarxes d'àrea personal (PAN). Amb la introducció d'una capa d'adaptació que possibilita les IEEE 802.15.4 xarxes compatibles amb IPv6, la interconnexió de milers de milions de dispositius restringits s'ha fet possible. La idea d'entreteixir la tecnologia d'Internet amb qualsevol tipus d'objectes intel·ligents, com els dispositius o sensors d'una WSN és coneguda com la Internet de les Coses (IoT). L'objectiu principal d'aquesta tesi és la millora del rendiment de les WSNs. Donada l'àmplia gamma d'escenaris d'aplicacions i solucions de xarxes proposats per a aquest tipus de xarxes, el desenvolupament i l'optimització dels protocols de comunicació per a dispositius de WSNs és una tasca difícil: les limitacions de capacitats dels dispositius restringits, escenaris d'aplicació específics que poden variar d'una xarxa a l'altra, i la integració de les WSNs a la IoT requereixen nous enfocaments per al disseny i avaluació de protocols de comunicació. Cal identificar mecanismes i configuracions de paràmetres de les piles de protocols de comunicació per a WSNs que són elementals per al rendiment de la xarxa, optimitzar-los, i complementar-los amb l'addició d'altres de nous. La primera contribució d'aquesta tesi és la millora del rendiment extrem a extrem per PANs basat en IEEE 802.15.4, on s'analitza la configuració de paràmetres que es fan servir per defecte en protocols de comunicació comuns i s'avalua el seu impacte en el rendiment de la xarxa. Avaluacions físiques en una xarxa de sensors permeten fer front a la important qüestió de si els valors estàndards dels paràmetres són eficients o si ajustant-los es pot proporcionar un millor rendiment. La segona contribució d'aquesta tesi és l'optimització del rendiment extrem a extrem de xarxes ZigBee domòtiques (HA) sense fils. ZigBee és un estàndard important per a WSNs. Els estudis duts a terme cobreixen la important falta d'investigació d'avaluacions de rendiment de xarxes HA de ZigBee mitjançant experiments físics i mostrant formes per millorar el rendiment de la xarxa en base d'aquests experiments. Finalment, aquesta tesi es centra en la millora del mecanisme bàsic de control de congestió (CC) aplicada pel Constrained Application Protocol (CoAP) utilitzat en les comunicacions de la IoT. És necessari un algoritme de CC avançat per al control de la possible congestió en la IoT produïda per la plètora de dispositius i/o errors d'enllaç naturals per a les comunicacions de ràdio de baixa potencia. Donada l'alta rellevància de CoAP per a les comunicacions en la IoT, un algoritme CC avançat ha de ser capaç d'adaptar-se a les particularitats de les comunicacions de la IoT. Aquesta tesi contribueix al problema amb el disseny i l'optimització Control de Congestió Avançat / Simple del CoAP (CoCoA), un mecanisme de CC avançat per CoAP. Les investigacions de mecanismes de CC avançats per CoAP impliquen avaluacions extenses en xarxes simulades i experiments físics en xarxes reals utilitzant diferents tecnologies de comunicacions