Contribution to the publish/subscribe communication model for the development of ubiquitous services in wireless sensor networks

Advances in wireless technologies and the rapid development of integrated electronics have made wireless sensor networks (WSN) one of the key technologies of the Internet of Things (IoT). Thanks to the ability of these networks to measure the physical phenomena of their environment, process and communicate this information using wireless technologies, they have excelled in the development of applications that respond or adapt to the context of a user, as is the case of ubiquitous environments such as smart cities, industrial automation, e-health among others. In addition, the IoT has opened the possibility that intelligent objects or devices are also capable of exchanging status information, conditions and capacity in order to interact with each other, in the same way that human beings have done through systems based on presence. These systems require information of an event in real time to react in a timely manner to the conditions or context of the user or device. These applications open new challenges in the management of WSN resources, since these networks operate in environments that are generally prone to packet loss and consist of generally small nodes with limited resources in memory, processing, bandwidth and power. The main objective of this thesis is the development of several mechanisms that allow the adaptation of the Publish/Subscribe protocols to the characteristics and limitations of the WSN for the provision of ubiquitous services in the context of the IoT. In addition, QoS support is supplied through mechanisms that provide reliability and timeliness in the delivery of packets and data aggregation techniques are applied to be efficient in the power consumption and the WSN bandwidth. Our research proposes an architecture to provide a presence service for WSN based on a Publish/ Subscribe model distributed and focused on mechanisms such as the aggregation of data and the publication of messages on demand to achieve energy efficiency and bandwidth. All these mechanisms have been applied in the design of a system called PASH aimed at home control based on the concept of Ambient Assisted Living (AAL). The reliability provided by Publish/Subscribe protocols in WSN is of great importance in the design of applications that require receiving a message to react on time or in real time to an event. Initially, we focused our study on increasing the proportion of packet delivery (PDR) in the destination node through the improvement of reliability mechanisms. We evaluated the reliability mechanism of the MQTT-SN protocol and several proposed mechanisms of the CoAP protocol. From this evaluation, we propose a new and simple adaptive retransmission mechanism to respond to packet loss in the most appropriate way. Finally, we consider that applications such as: e-health, critical infrastructure control and monitoring, among others, must meet different QoS requirements, such as reliability and timeliness for each type of message received. In addition, data aggregation techniques play an important role in WSN to reduce power consumption and bandwidth. In this thesis, we propose a mechanism that provides the application with three different levels of QoS: we provide an improvement of our previous relay mechanism for reliability, we include the data aggregation in our reliability mechanism and we provide a timeliness mechanism in the delivery of packets.Els avenços en les tecnologies sense fils i al ràpid desenvolupament de l'electrònica integrada, ha convertit les xarxes de sensors sense fils (WSN) en una de les tecnologies claus de l'Internet de les Coses (Iot). Gràcies a la capacitat que tenen aquestes xarxes de mesurar els fenòmens físics del seu entorn, processar i comunicar aquesta informació utilitzant tecnologies sense fils, s'han destacat en el desenvolupament d'aplicacions que responguin o s'adaptin al context d'un usuari, com és el cas dels entorns ubics com a ciutats intel·ligents, automatització industrial, salut electrònica entre d'altres. A més, el IOT ha obert la possibilitat que els objectes o dispositius intel·ligents també siguin capaços d'intercanviar informació d'estat, condicions i capacitat per tal d'interactuar entre si, de la mateixa manera que els éssers humans ho han fet a través de sistemes basats en presència. Aquests sistemes requereixen informació d'un esdeveniment en temps real per reaccionar de manera oportuna a les condicions o al context de l'usuari o dispositiu. Aquestes aplicacions obren nous desafiaments en l'administració dels recursos de WSN, ja que aquestes xarxes operen en entorns que generalment són propensos a la pèrdua de paquets i consten de nodes generalment petits amb recursos limitats en memòria, processament, ample de banda i alimentació. El principal objectiu d'aquesta tesi és el desenvolupament de diversos mecanismes que permetin l'adequació dels protocols d'Publish / Subscribe a les característiques i limitacions de la WSN per a la provisió de serveis ubics en el context de la IOT. A més, es brinda suport de QoS a través de mecanismes que proporcionen fiabilitat i puntualitat en el lliurament de paquets i s'apliquen tècniques d'agregació de dades per a ser eficients en el consum d'energia i l'ample de banda de la WSN. La nostra investigació proposa una arquitectura per a proporcionar un servei de presència per WSN basat en un model de Publish / Subscribe distribuït i centrat en mecanismes com ara l'agregació de dades i la publicació de missatges en demanda per aconseguir eficiència en l'energia i l'ample de banda . Tots aquests mecanismes han estat aplicats en el disseny d'un sistema anomenat Pash dirigit al control de la llar basat en el concepte de Vida Assistida (AAL). La fiabilitat proporcionada pels protocols de Publish / Subscribe WSN és de gran importància en el disseny d'aplicacions que requereixen rebre un missatge per reaccionar a temps o en temps real davant un esdeveniment. Inicialment enfoquem el nostre estudi en augmentar la proporció de lliurament de paquets (PDR) en el node de destinació a través de la millora dels mecanismes de fiabilitat. Avaluem el mecanisme de fiabilitat del protocol MQTT-SN i diversos mecanismes proposats del protocol COAP. A partir d'aquesta avaluació, proposem un nou i senzill mecanisme de retransmissió adaptable per respondre a la pèrdua de paquets de la manera més adequada. Finalment, considerem que les aplicacions com: salut electrònica, control d'infraestructura crítica i monitoratge, entre d'altres, han de complir diferents requisits de QoS, com la fiabilitat i la puntualitat per a cada tipus de missatge rebut. A més, les tècniques d'agregació de dades tenen un paper important en WSN per reduir el consum d'energia i l'ample de banda. En aquesta tesi, proposem un mecanisme que proporciona a la aplicació tres nivells de QoS diferents: proporcionem una millora del nostre mecanisme de retransmissió anterior per a la fiabilitat, incloem l'agregació de dades en el nostre mecanisme de fiabilitat i proporcionem un mecanisme de puntualitat en el lliurament de paquets.Postprint (published version

Contribution to the publish/subscribe communication model for the development of ubiquitous services in wireless sensor networks

Advances in wireless technologies and the rapid development of integrated electronics have made wireless sensor networks (WSN) one of the key technologies of the Internet of Things (IoT). Thanks to the ability of these networks to measure the physical phenomena of their environment, process and communicate this information using wireless technologies, they have excelled in the development of applications that respond or adapt to the context of a user, as is the case of ubiquitous environments such as smart cities, industrial automation, e-health among others. In addition, the IoT has opened the possibility that intelligent objects or devices are also capable of exchanging status information, conditions and capacity in order to interact with each other, in the same way that human beings have done through systems based on presence. These systems require information of an event in real time to react in a timely manner to the conditions or context of the user or device. These applications open new challenges in the management of WSN resources, since these networks operate in environments that are generally prone to packet loss and consist of generally small nodes with limited resources in memory, processing, bandwidth and power. The main objective of this thesis is the development of several mechanisms that allow the adaptation of the Publish/Subscribe protocols to the characteristics and limitations of the WSN for the provision of ubiquitous services in the context of the IoT. In addition, QoS support is supplied through mechanisms that provide reliability and timeliness in the delivery of packets and data aggregation techniques are applied to be efficient in the power consumption and the WSN bandwidth. Our research proposes an architecture to provide a presence service for WSN based on a Publish/ Subscribe model distributed and focused on mechanisms such as the aggregation of data and the publication of messages on demand to achieve energy efficiency and bandwidth. All these mechanisms have been applied in the design of a system called PASH aimed at home control based on the concept of Ambient Assisted Living (AAL). The reliability provided by Publish/Subscribe protocols in WSN is of great importance in the design of applications that require receiving a message to react on time or in real time to an event. Initially, we focused our study on increasing the proportion of packet delivery (PDR) in the destination node through the improvement of reliability mechanisms. We evaluated the reliability mechanism of the MQTT-SN protocol and several proposed mechanisms of the CoAP protocol. From this evaluation, we propose a new and simple adaptive retransmission mechanism to respond to packet loss in the most appropriate way. Finally, we consider that applications such as: e-health, critical infrastructure control and monitoring, among others, must meet different QoS requirements, such as reliability and timeliness for each type of message received. In addition, data aggregation techniques play an important role in WSN to reduce power consumption and bandwidth. In this thesis, we propose a mechanism that provides the application with three different levels of QoS: we provide an improvement of our previous relay mechanism for reliability, we include the data aggregation in our reliability mechanism and we provide a timeliness mechanism in the delivery of packets.Els avenços en les tecnologies sense fils i al ràpid desenvolupament de l'electrònica integrada, ha convertit les xarxes de sensors sense fils (WSN) en una de les tecnologies claus de l'Internet de les Coses (Iot). Gràcies a la capacitat que tenen aquestes xarxes de mesurar els fenòmens físics del seu entorn, processar i comunicar aquesta informació utilitzant tecnologies sense fils, s'han destacat en el desenvolupament d'aplicacions que responguin o s'adaptin al context d'un usuari, com és el cas dels entorns ubics com a ciutats intel·ligents, automatització industrial, salut electrònica entre d'altres. A més, el IOT ha obert la possibilitat que els objectes o dispositius intel·ligents també siguin capaços d'intercanviar informació d'estat, condicions i capacitat per tal d'interactuar entre si, de la mateixa manera que els éssers humans ho han fet a través de sistemes basats en presència. Aquests sistemes requereixen informació d'un esdeveniment en temps real per reaccionar de manera oportuna a les condicions o al context de l'usuari o dispositiu. Aquestes aplicacions obren nous desafiaments en l'administració dels recursos de WSN, ja que aquestes xarxes operen en entorns que generalment són propensos a la pèrdua de paquets i consten de nodes generalment petits amb recursos limitats en memòria, processament, ample de banda i alimentació. El principal objectiu d'aquesta tesi és el desenvolupament de diversos mecanismes que permetin l'adequació dels protocols d'Publish / Subscribe a les característiques i limitacions de la WSN per a la provisió de serveis ubics en el context de la IOT. A més, es brinda suport de QoS a través de mecanismes que proporcionen fiabilitat i puntualitat en el lliurament de paquets i s'apliquen tècniques d'agregació de dades per a ser eficients en el consum d'energia i l'ample de banda de la WSN. La nostra investigació proposa una arquitectura per a proporcionar un servei de presència per WSN basat en un model de Publish / Subscribe distribuït i centrat en mecanismes com ara l'agregació de dades i la publicació de missatges en demanda per aconseguir eficiència en l'energia i l'ample de banda . Tots aquests mecanismes han estat aplicats en el disseny d'un sistema anomenat Pash dirigit al control de la llar basat en el concepte de Vida Assistida (AAL). La fiabilitat proporcionada pels protocols de Publish / Subscribe WSN és de gran importància en el disseny d'aplicacions que requereixen rebre un missatge per reaccionar a temps o en temps real davant un esdeveniment. Inicialment enfoquem el nostre estudi en augmentar la proporció de lliurament de paquets (PDR) en el node de destinació a través de la millora dels mecanismes de fiabilitat. Avaluem el mecanisme de fiabilitat del protocol MQTT-SN i diversos mecanismes proposats del protocol COAP. A partir d'aquesta avaluació, proposem un nou i senzill mecanisme de retransmissió adaptable per respondre a la pèrdua de paquets de la manera més adequada. Finalment, considerem que les aplicacions com: salut electrònica, control d'infraestructura crítica i monitoratge, entre d'altres, han de complir diferents requisits de QoS, com la fiabilitat i la puntualitat per a cada tipus de missatge rebut. A més, les tècniques d'agregació de dades tenen un paper important en WSN per reduir el consum d'energia i l'ample de banda. En aquesta tesi, proposem un mecanisme que proporciona a la aplicació tres nivells de QoS diferents: proporcionem una millora del nostre mecanisme de retransmissió anterior per a la fiabilitat, incloem l'agregació de dades en el nostre mecanisme de fiabilitat i proporcionem un mecanisme de puntualitat en el lliurament de paquets.Postprint (published version

Vehicle as a Service (VaaS): Leverage Vehicles to Build Service Networks and Capabilities for Smart Cities

Smart cities demand resources for rich immersive sensing, ubiquitous communications, powerful computing, large storage, and high intelligence (SCCSI) to support various kinds of applications, such as public safety, connected and autonomous driving, smart and connected health, and smart living. At the same time, it is widely recognized that vehicles such as autonomous cars, equipped with significantly powerful SCCSI capabilities, will become ubiquitous in future smart cities. By observing the convergence of these two trends, this article advocates the use of vehicles to build a cost-effective service network, called the Vehicle as a Service (VaaS) paradigm, where vehicles empowered with SCCSI capability form a web of mobile servers and communicators to provide SCCSI services in smart cities. Towards this direction, we first examine the potential use cases in smart cities and possible upgrades required for the transition from traditional vehicular ad hoc networks (VANETs) to VaaS. Then, we will introduce the system architecture of the VaaS paradigm and discuss how it can provide SCCSI services in future smart cities, respectively. At last, we identify the open problems of this paradigm and future research directions, including architectural design, service provisioning, incentive design, and security & privacy. We expect that this paper paves the way towards developing a cost-effective and sustainable approach for building smart cities.Comment: 32 pages, 11 figure

Vehicular Ad Hoc Networks: Growth and Survey for Three Layers

A vehicular ad hoc network (VANET) is a mobile ad hoc network that allows wireless communication between vehicles, as well as between vehicles and roadside equipment. Communication between vehicles promotes safety and reliability, and can be a source of entertainment. We investigated the historical development, characteristics, and application fields of VANET and briefly introduced them in this study. Advantages and disadvantages were discussed based on our analysis and comparison of various classes of MAC and routing protocols applied to VANET. Ideas and breakthrough directions for inter-vehicle communication designs were proposed based on the characteristics of VANET. This article also illustrates physical, MAC, and network layer in details which represent the three layers of VANET. The main works of the active research institute on VANET were introduced to help researchers track related advanced research achievements on the subject

Cooperative mobility maintenance techniques for information extraction from mobile wireless sensor networks

Recent advances in the development of microprocessors, microsensors, ad-hoc wireless networking and information fusion algorithms led to increasingly capable Wireless Sensor Networks (WSNs). Besides severe resource constraints, sensor nodes mobility is considered a fundamental characteristic of WSNs. Information Extraction (IE) is a key research area within WSNs that has been characterised in a variety of ways, ranging from a description of its purposes to reasonably abstract models of its processes and components. The problem of IE is a challenging task in mobile WSNs for several reasons including: the topology changes rapidly; calculation of trajectories and velocities is not a trivial task; increased data loss and data delivery delays; and other context and application specific challenges. These challenges offer fundamentally new research problems. There is a wide body of literature about IE from static WSNs. These approaches are proved to be effective and efficient. However, there are few attempts to address the problem of IE from mobile WSNs. These attempts dealt with mobility as the need arises and do not deal with the fundamental challenges and variations introduced by mobility on the WSNs. The aim of this thesis is to develop a solution for IE from mobile WSNs. This aim is achieved through the development of a middle-layer solution, which enables IE approaches that were designed for the static WSNs to operate in the presence of multiple mobile nodes. This thesis contributes toward the design of a new self-stabilisation algorithm that provides autonomous adaptability against nodes mobility in a transparent manner to both upper network layers and user applications. In addition, this thesis proposes a dynamic network partitioning protocol to achieve high quality of information, scalability and load balancing. The proposed solution is flexible, may be applied to different application domains, and less complex than many existing approaches. The simplicity of the solutions neither demands great computational efforts nor large amounts of energy conservation. Intensive simulation experiments with real-life parameters provide evidence of the efficiency of the proposed solution. Performance experimentations demonstrate that the integrated DNP/SS protocol outperforms its rival in the literature in terms of timeliness (by up to 22%), packet delivery ratio (by up to 13%), network scalability (by up to 25%), network lifetime (by up to 40.6%), and energy consumption (by up to 39.5%). Furthermore, it proves that DNP/SS successfully allows the deployment of static-oriented IE approaches in hybrid networks without any modifications or adaptations

Diagnostic Applications for Micro-Synchrophasor Measurements

This report articulates and justifies the preliminary selection of diagnostic applications for data from micro-synchrophasors (µPMUs) in electric power distribution systems that will be further studied and developed within the scope of the three-year ARPA-e award titled Micro-synchrophasors for Distribution Systems

On the use of IEEE 802.15.4/Zigbee for time-sensitive wireless sensor network applications

Mestrado em Engenharia Electrotécnica e de ComputadoresRecent advancements in information and communication technologies are paving the way for new paradigms in embedded computing systems. This, allied with an increasing eagerness for monitoring and controlling everything, everywhere, is pushing forward the design of new Wireless Sensor Network (WSN) infrastructures that will tightly interact with the physical environment, in a ubiquitous and pervasive fashion. Such cyber-physical systems require a rethinking of the usual computing and networking concepts, and given that the computing entities closely interact with their environment, timeliness is of increasing importance. This Thesis addresses the use of standard protocols, particularly IEEE 802.15.4 and ZigBee, combined with commercial technologies as a baseline to enable WSN infrastructures capable of supporting the Quality of Service (QoS) requirements (specially timeliness and system lifetime) that future large-scale networked embedded systems will impose. With this purpose, in this Thesis we start by evaluating the network performance of the IEEE 802.15.4 Slotted CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) mechanism for different parameter settings, both through simulation and through an experimental testbed. In order to improve the performance of these networks (e.g. throughput, energyefficiency, message delay) against the hidden-terminal problem, a mechanism to mitigate it was implemented and experimentally validated. The effectiveness of this mechanism was also demonstrated in a real application scenario, featuring a target tracking application. A methodology for modelling cluster-tree WSNs and computing the worst-case endto-end delays, buffering and bandwidth requirements was tested and validated experimentally. This work is of paramount importance to understand the behaviour of WSNs under worst-case conditions and also to make the appropriate network settings. Our experimental work enabled us to identify a number of technological constrains, namely related to hardware/software and to the Open-ZB implementation in TinyOS. In this line, a new implementation effort was triggered to port the Open-ZB IEEE 802.15.4/ZigBee protocol stack to the ERIKA real-time operating system. This implementation was validated experimentally and its behaviour compared with the TinyOS–based implementation.Os últimos avanços nas tecnologias de informação e comunicação (ICTs) estão a abrir caminho para novos paradigmas de sistemas computacionais embebidos. Este facto, aliado à tendência crescente em monitorizar e controlar tudo, em qualquer lugar, está a alimentar o desenvolvimento de novas infra-estruturas de Redes de Sensores Sem Fios (WSNs), que irão interagir intimamente com o mundo físico de uma forma ubíqua. Este género de sistemas ciber-físicos de grande escala, requer uma reflexão sobre os conceitos de redes e de computação tradicionais, e tendo em conta a proximidade que estas entidades partilham com ambiente envolvente, o seu comportamento temporal é de acrescida importância. Esta Tese endereça a utilização de protocolos normalizados, em particular do IEEE 802.15.4 e ZigBee em conjunto com tecnologias comerciais, para desenvolver infraestruturas WSN capazes de responder aos requisitos de Qualidade de Serviço (QoS) (especialmente em termos de comportamento temporal e tempo de vida do sistema), que os futuros sistemas embebidos de grande escala deverão exigir. Com este propósito, nesta Tese começamos por analisar a performance do mecanismo de Slotted CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) do IEEE 802.15.4 para diferentes parâmetros, através de simulação e experimentalmente. De modo a melhorar a performance destas redes (ex. throughput, eficiência energética, atrasos) em cenários que contenham nós escondidos (hidden-nodes), foi implementado e validado experimentalmente um mecanismo para eliminar este problema. A eficácia deste mecanismo foi também demonstrada num cenário aplicacional real. Foi testada e validada uma metodologia para modelizar uma WSN em cluster-tree e calcular os piores atrasos das mensagens, necessidades de buffering e de largura de banda. Este trabalho foi de grande importância para compreender o comportamento deste tipo de redes para condições de utilização limite e para as configurar a priori. O nosso trabalho experimental permitiu identificar uma série de limitações tecnológicas, nomeadamente relacionadas com hardware/software e outras relacionadas com a implementação do Open-ZB em TinyOS. Isto desencadeou a migração da pilha protocolar IEEE 802.15.4/ZigBee Open-ZB para o ERIKA, um sistema operativo de tempo-real. Esta implementação foi validada experimentalmente e o seu comportamento comparado com o da implementação baseada em TinyOS