468 research outputs found
A critical analysis of research potential, challenges and future directives in industrial wireless sensor networks
In recent years, Industrial Wireless Sensor Networks (IWSNs) have emerged as an important research theme with applications spanning a wide range of industries including automation, monitoring, process control, feedback systems and automotive. Wide scope of IWSNs applications ranging from small production units, large oil and gas industries to nuclear fission control, enables a fast-paced research in this field. Though IWSNs offer advantages of low cost, flexibility, scalability, self-healing, easy deployment and reformation, yet they pose certain limitations on available potential and introduce challenges on multiple fronts due to their susceptibility to highly complex and uncertain industrial environments. In this paper a detailed discussion on design objectives, challenges and solutions, for IWSNs, are presented. A careful evaluation of industrial systems, deadlines and possible hazards in industrial atmosphere are discussed. The paper also presents a thorough review of the existing standards and industrial protocols and gives a critical evaluation of potential of these standards and protocols along with a detailed discussion on available hardware platforms, specific industrial energy harvesting techniques and their capabilities. The paper lists main service providers for IWSNs solutions and gives insight of future trends and research gaps in the field of IWSNs
IETF standardization in the field of the Internet of Things (IoT): a survey
Smart embedded objects will become an important part of what is called the Internet of Things. However, the integration of embedded devices into the Internet introduces several challenges, since many of the existing Internet technologies and protocols were not designed for this class of devices. In the past few years, there have been many efforts to enable the extension of Internet technologies to constrained devices. Initially, this resulted in proprietary protocols and architectures. Later, the integration of constrained devices into the Internet was embraced by IETF, moving towards standardized IP-based protocols. In this paper, we will briefly review the history of integrating constrained devices into the Internet, followed by an extensive overview of IETF standardization work in the 6LoWPAN, ROLL and CoRE working groups. This is complemented with a broad overview of related research results that illustrate how this work can be extended or used to tackle other problems and with a discussion on open issues and challenges. As such the aim of this paper is twofold: apart from giving readers solid insights in IETF standardization work on the Internet of Things, it also aims to encourage readers to further explore the world of Internet-connected objects, pointing to future research opportunities
QoS improvement in TCP/IP-based wireless sensor networks using cross-layer optimization
Dissertação de Mestrado, Engenharia InformĂĄtica, Faculdade de CiĂȘncias e Tecnologia, Universidade do Algarve, 2015Internet of Things (IoT) is becoming a reality and new and advanced applications are
expected to emerge. For applications with reliability needs to work well in IoT environments,
robust data transportation is required. Approaches like TCP are known for
not being adequate in sensor network environments, while UDP has been included in
the 6LoWPAN stack allowing low-power and limited processing devices to participate
in the IoT. However, UDP provides no reliability. One way of providing reliability is to
use link-layer acknowledgements but this mechanism may lead to an inefficient use of
resources if used unconditionally throughout all the network. Another way is to request
the confirmation of messages sent, done at the application layer, but this is an end-to-end
process that can only be applied for specific message type transactions. If used for all
data then there will be long delays and inefficient use of resources also. Here we address
the design of a cross-layer reactive mechanism that improves reliability of data delivery,
in order to support applications that require some reliability level when delivering data
notifications. This mechanism introduces link layer reliability at specific nodes, gradually
and only when needed, having no scaling problems. Results show that this mechanism
can improve data delivery and improve the use of network resources.Erasmus Mundus Iran Iraq Yemen (EMIIY
A New Objective Function Based on Additive Combination of Node and Link Metrics as a Mechanism Path Selection for RPL Protocol
Since its development by IETF, the IPv6 routing protocol for low power and lossy networks (RPL) remains the subject of several researches. RPL is based on objective function as a mechanism selection of paths in the network. However, the default objective functions standardized selects the routes according to a single routing metric that leads to an unoptimized path selection and a lot of parent changes. Thus, we propose in this paper weighted combined metrics objective function (WCM-OF) and non-weighted combined metrics objective function (NWCM-OF) that are based both on additive link quality and energy metrics with equal weights or not to achieve a tradeoff between reliability and saved energy levels. The proposed objective functions were implemented in the core of Contiki operating system and evaluated with Cooja emulator. Results show that the proposed objective functions improved the network performances compared to default objective functions
Performance Assessment of Routing Protocols for IoT/6LoWPAN Networks
The Internet of Things (IoT) proposes a disruptive communication paradigm that allows
smart objects to exchange data among themselves to reach a common goal. IoT application
scenarios are multiple and can range from a simple smart home lighting system to fully controlled
automated manufacturing chains. In the majority of IoT deployments, things are equipped with
small devices that can suffer from severe hardware and energy restrictions that are responsible
for performing data processing and wireless communication tasks. Thus, due to their features,
communication networks that are used by these devices are generally categorized as Low Power
and Lossy Networks (LLNs).
The considerable variation in IoT applications represents a critical issue to LLN networks,
which should offer support to different requirements as well as keeping reasonable
quality-of-service (QoS) levels. Based on this challenge, routing protocols represent a key issue
in IoT scenarios deployment. Routing protocols are responsible for creating paths among devices
and their interactions. Hence, network performance and features are highly dependent
on protocol behavior. Also, based on the adopted protocol, the support for some specific requirements
of IoT applications may or may not be provided. Thus, a routing protocol should be
projected to attend the needs of the applications considering the limitations of the device that
will execute them.
Looking to attend the demand of routing protocols for LLNs and, consequently, for IoT
networks, the Internet Engineering Task Force (IETF) has designed and standardized the IPv6
Routing Protocol for Low Power and Lossy Networks (RPL). This protocol, although being robust
and offering features to fulfill the need of several applications, still presents several faults and
weaknesses (mainly related to its high complexity and memory requirement), which limits its
adoption in IoT scenarios. An alternative to RPL, the Lightweight On-demand Ad Hoc Distancevector
Routing Protocol â Next Generation (LOADng) has emerged as a less complicated routing
solution for LLNs. However, the cost of its simplicity is paid for with the absence of adequate
support for a critical set of features required for many IoT environments. Thus, based on the
challenging open issues related to routing in IoT networks, this thesis aims to study and propose
contributions to better attend the network requirements of IoT scenarios. A comprehensive survey,
reviewing state-of-the-art routing protocols adopted for IoT, identified the strengths and
weaknesses of current solutions available in the literature. Based on the identified limitations,
a set of improvements is designed to overcome these issues and enhance IoT network performance.
The novel solutions are proposed to include reliable and efficient support to attend
the needs of IoT applications, such as mobility, heterogeneity, and different traffic patterns.
Moreover, mechanisms to improve the network performance in IoT scenarios, which integrate
devices with different communication technologies, are introduced.
The studies conducted to assess the performance of the proposed solutions showed
the high potential of the proposed solutions. When the approaches presented in this thesis
were compared with others available in the literature, they presented very promising results
considering the metrics related to the Quality of Service (QoS), network and energy efficiency,
and memory usage as well as adding new features to the base protocols. Hence, it is believed
that the proposed improvements contribute to the state-of-the-art of routing solutions for IoT
networks, increasing the performance and adoption of enhanced protocols.A Internet das Coisas, do inglĂȘs Internet of Things (IoT), propĂ”e um paradigma de
comunicação disruptivo para possibilitar que dispositivos, que podem ser dotados de comportamentos
autónomos ou inteligentes, troquem dados entre eles buscando alcançar um objetivo
comum. Os cenårios de aplicação do IoT são muito variados e podem abranger desde um simples
sistema de iluminação para casa até o controle total de uma linha de produção industrial. Na
maioria das instalaçÔes IoT, as âcoisasâ sĂŁo equipadas com um pequeno dispositivo, responsĂĄvel
por realizar as tarefas de comunicação e processamento de dados, que pode sofrer com severas
restriçÔes de hardware e energia. Assim, devido Ă s suas caracterĂsticas, a rede de comunicação
criada por esses dispositivos Ă© geralmente categorizada como uma Low Power and Lossy Network
(LLN).
A grande variedade de cenĂĄrios IoT representam uma questĂŁo crucial para as LLNs,
que devem oferecer suporte aos diferentes requisitos das aplicaçÔes, alĂ©m de manter nĂveis
de qualidade de serviço, do inglĂȘs Quality of Service (QoS), adequados. Baseado neste desafio,
os protocolos de encaminhamento constituem um aspecto chave na implementação de
cenĂĄrios IoT. Os protocolos de encaminhamento sĂŁo responsĂĄveis por criar os caminhos entre
os dispositivos e permitir suas interaçÔes. Assim, o desempenho e as caracterĂsticas da rede
sĂŁo altamente dependentes do comportamento destes protocolos. Adicionalmente, com base
no protocolo adotado, o suporte a alguns requisitos especĂficos das aplicaçÔes de IoT podem
ou nĂŁo ser fornecidos. Portanto, estes protocolos devem ser projetados para atender as necessidades
das aplicaçÔes assim como considerando as limitaçÔes do hardware no qual serão
executados.
Procurando atender Ă s necessidades dos protocolos de encaminhamento em LLNs e,
consequentemente, das redes IoT, a Internet Engineering Task Force (IETF) desenvolveu e padronizou
o IPv6 Routing Protocol for Low Power and Lossy Networks (RPL). O protocolo, embora
seja robusto e ofereça recursos para atender às necessidades de diferentes aplicaçÔes, apresenta
algumas falhas e fraquezas (principalmente relacionadas com a sua alta complexidade e
necessidade de memória) que limitam sua adoção em cenårios IoT. Em alternativa ao RPL, o
Lightweight On-demand Ad hoc Distance-vector Routing Protocol â Next Generation (LOADng)
emergiu como uma solução de encaminhamento menos complexa para as LLNs. Contudo, o
preço da simplicidade é pago com a falta de suporte adequado para um conjunto de recursos
essenciais necessårios em muitos ambientes IoT. Assim, inspirado pelas desafiadoras questÔes
ainda em aberto relacionadas com o encaminhamento em redes IoT, esta tese tem como objetivo
estudar e propor contribuiçÔes para melhor atender os requisitos de rede em cenårios IoT.
Uma profunda e abrangente revisĂŁo do estado da arte sobre os protocolos de encaminhamento
adotados em IoT identificou os pontos fortes e limitaçÔes das soluçÔes atuais. Com base nas debilidades
encontradas, um conjunto de soluçÔes de melhoria Ă© proposto para superar carĂȘncias
existentes e melhorar o desempenho das redes IoT. As novas soluçÔes são propostas para incluir
um suporte confiåvel e eficiente capaz atender às necessidades das aplicaçÔes IoT relacionadas
com suporte à mobilidade, heterogeneidade dos dispositivos e diferentes padrÔes de tråfego.
Além disso, são introduzidos mecanismos para melhorar o desempenho da rede em cenårios IoT
que integram dispositivos com diferentes tecnologias de comunicação.
Os vårios estudos realizados para mensurar o desempenho das soluçÔes propostas mostraram
o grande potencial do conjunto de melhorias introduzidas. Quando comparadas com
outras abordagens existentes na literatura, as soluçÔes propostas nesta tese demonstraram um aumento do desempenho consistente para métricas relacionadas a qualidade de serviço, uso de
memĂłria, eficiĂȘncia energĂ©tica e de rede, alĂ©m de adicionar novas funcionalidades aos protocolos
base. Portanto, acredita-se que as melhorias propostas contribuiem para o avanço do estado
da arte em soluçÔes de encaminhamento para redes IoT e aumentar a adoção e utilização dos
protocolos estudados
Latency Optimization in Smart Meter Networks
In this thesis, we consider the problem of smart meter networks with data collection to a central point within acceptable delay and least consumed energy. In smart metering applications, transferring and collecting data within delay constraints is crucial. IoT devices are usually resource-constrained and need reliable and energy-efficient routing protocol. Furthermore, meters deployed in lossy networks often lead to packet loss and congestion. In smart grid communication, low latency and low energy consumption are usually the main system targets. Considering these constraints, we propose an enhancement in RPL to ensure link reliability and low latency. The proposed new additive composite metric is Delay-Aware RPL (DA-RPL). Moreover, we propose a repeatersâ placement algorithm to meet the latency requirements. The performance of a realistic RF network is simulated and evaluated. On top of the routing solution, new asynchronous ordered transmission algorithms of UDP data packets are proposed to further enhance the overall network latency performance and mitigate the whole system congestion and interference. Experimental results show that the performance of DA-RPL is promising in terms of end-to-end delay and energy consumption. Furthermore, the ordered asynchronous transmission of data packets resulted in significant latency reduction using just a single routing metric
A Game Theoretic Optimization of RPL for Mobile Internet of Things Applications
The presence of mobile nodes in any wireless network can affect the performance of the network, leading to higher packet loss and increased energy consumption. However, many recent applications require the support of mobility and an efficient approach to handle mobile nodes is essential. In this paper, a game scenario is formulated where nodes compete for network resources in a selfish manner, to send their data packets to the sink node. Each node counts as a player in the noncooperative game. The optimal solution for the game is found using the unique Nash equilibrium (NE) where a node cannot improve its pay-off function while other players use their current strategy. The proposed solution aims to present a strategy to control different parameters of mobile nodes (or static nodes in a mobile environment) including transmission rate, timers and operation mode in order to optimize the performance of RPL under mobility in terms of packet delivery ratio (PDR), throughput, energy consumption and end-to-end-delay. The proposed solution monitors the mobility of nodes based on received signal strength indication (RSSI) readings, it also takes into account the priorities of different nodes and the current level of noise in order to select the preferred transmission rate. An optimized protocol called game-theory based mobile RPL (GTM-RPL) is implemented and tested in multiple scenarios with different network requirements for Internet of Things applications. Simulation results show that in the presence of mobility, GTM-RPL provides a flexible and adaptable solution that improves throughput whilst maintaining lower energy consumption showing more than 10% improvement compared to related work. For applications with high throughput requirements, GTM-RPL shows a significant advantage with more than 16% improvement in throughput and 20% improvement in energy consumption
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, tĂ©cnicas de comunicaciĂłn 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 mĂĄs apropiada debido a las limitaciones de WSNs. Ăsta se denomina REST. En base a este anĂĄlisis, revisamos el estado del arte de los protocolos que permiten desarrollar servicios Web. Con este objetivo adoptamos el estĂĄndar IEEE 802.15.4 por la capa fĂsica y de enlace, 6LoWPAN por la de red y CoAP por la capa de aplicaciĂłn. 6LoWPAN define dos tĂ©cnicas 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 comunicaciĂłn que utiliza 6LoWPAN fragmentation. En particular, MU no previene enrutar fragmentos innecesarios y la entrega fuera de orden, lo cual podrĂa provocar un uso ineficiente de ancho de banda y un crecimiento del consumo energĂa. Proponemos entonces nueva tĂ©cnica capaz de mejorar las prestaciones de MU con paquetes fragmentados que denominamos 'Controlled Mesh Under' (CMU). Los resultados de una evaluaciĂłn en una WSN real demuestran que CMU es capaz de mejorar las prestaciones de MU reduciendo la pĂ©rdida de paquetes y el retraso end-to-end. En 6LoWPAN fragmentation, la pĂ©rdida de un fragmento causa la retransmisiĂłn del paquete entero. Para evitar esta limitaciĂłn CoAP define blockwise transfer. Esto divide el paquete en bloques y los envĂa en comunicaciones fiables provocando overhead. Proponemos un nuevo modelo analĂtico para estudiar blockwise y 6LoWPAN fragmentation cuya validaciĂłn se realiza mediante simulaciones de Monte Carlo. Ambas tĂ©cnicas se comparan en tĂ©rminos 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 tĂ©rminos de fiabilidad. CoAP define la opciĂłn 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 opciĂłn observe proporciona soporte parcial por el timeliness. Esta permite especificar la validez de una actualizaciĂłn 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 limitaciĂłn, diseñamos y evaluamos un mecanismo novedoso para la entrega de actualizaciones basada en la prioridad. La evaluaciĂłn demuestra que la implementaciĂłn 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 energĂa permitiendo a los clientes expresar el tipo de actualizaciĂłn que desean recibir. En parte de esta tesis presentamos nuestra librerĂa original pro TinyOS a la que nos referimos como TinyCoAP, asĂ como el diseño y desarrollo de un Proxy CoAP. Comparamos TinyCoAP a CoapBlip, que es la aplicaciĂłn distribuida con TinyOS. TinyCoAP demuestra ser capaz de alcanzar una alta optimizaciĂłn de cĂłdigo y reducir el impacto sobre la memoria de nodos de WSNs. La evaluaciĂłn tambiĂ©n incluye el anĂĄlisis de la fiabilidad de CoAP que no habĂa sido estudiada en la literatura. Como novedad tambiĂ©n 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. Ăste incluye el protocolo WebSocket, que permite el establecimiento de conexiones long-lived. TambiĂ©n permite el uso de aplicaciones Web con la tradicional tĂ©cnica HTTP long-pollin
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