177 research outputs found

    Reliable Communication in Wireless Networks

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    Wireless communication systems are increasingly being used in industries and infrastructures since they offer significant advantages such as cost effectiveness and scalability with respect to wired communication system. However, the broadcast feature and the unreliable links in the wireless communication system may cause more communication collisions and redundant transmissions. Consequently, guaranteeing reliable and efficient transmission in wireless communication systems has become a big challenging issue. In particular, analysis and evaluation of reliable transmission protocols in wireless sensor networks (WSNs) and radio frequency identification system (RFID) are strongly required. This thesis proposes to model, analyze and evaluate self-configuration algorithms in wireless communication systems. The objective is to propose innovative solutions for communication protocols in WSNs and RFID systems, aiming at optimizing the performance of the algorithms in terms of throughput, reliability and power consumption. The first activity focuses on communication protocols in WSNs, which have been investigated, evaluated and optimized, in order to ensure fast and reliable data transmission between sensor nodes. The second research topic addresses the interference problem in RFID systems. The target is to evaluate and develop precise models for accurately describing the interference among readers. Based on these models, new solutions for reducing collision in RFID systems have been investigated

    Performance Assessment of Routing Protocols for IoT/6LoWPAN Networks

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    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 – 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 autĂłnomos ou inteligentes, troquem dados entre eles buscando alcançar um objetivo comum. Os cenĂĄrios de aplicação do IoT sĂŁo muito variados e podem abranger desde um simples sistema de iluminação para casa atĂ© o controle total de uma linha de produção industrial. Na maioria das instalaçÔes IoT, as “coisas” 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 serĂŁo 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 Ă s necessidades de diferentes aplicaçÔes, apresenta algumas falhas e fraquezas (principalmente relacionadas com a sua alta complexidade e necessidade de memĂłria) que limitam sua adoção em cenĂĄrios IoT. Em alternativa ao RPL, o Lightweight On-demand Ad hoc Distance-vector Routing Protocol – Next Generation (LOADng) emergiu como uma solução de encaminhamento menos complexa para as LLNs. Contudo, o preço da simplicidade Ă© pago com a falta de suporte adequado para um conjunto de recursos essenciais necessĂĄrios em muitos ambientes IoT. Assim, inspirado pelas desafiadoras questĂ”es 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 cenĂĄrios 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 sĂŁo propostas para incluir um suporte confiĂĄvel e eficiente capaz atender Ă s necessidades das aplicaçÔes IoT relacionadas com suporte Ă  mobilidade, heterogeneidade dos dispositivos e diferentes padrĂ”es de trĂĄfego. AlĂ©m disso, sĂŁo introduzidos mecanismos para melhorar o desempenho da rede em cenĂĄrios IoT que integram dispositivos com diferentes tecnologias de comunicação. Os vĂĄrios 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 mĂ©tricas 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

    An energy-efficient routing protocol for Hybrid-RFID Sensor Network

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    Radio Frequency Identification (RFID) systems facilitate detection and identification of objects that are not easily detectable or distinguishable. However, they do not provide information about the condition of the objects they detect. Wireless sensor networks (WSNs), on the other hand provide information about the condition of the objects as well as the environment. The integration of these two technologies results in a new type of smart network where RFID-based components are combined with sensors. This research proposes an integration technique that combines conventional wireless sensor nodes, sensor-tags, hybrid RFID-sensor nodes and a base station into a smart network named Hybrid RFID-Sensor Network (HRSN)

    Energy efficiency in short and wide-area IoT technologies—A survey

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    In the last years, the Internet of Things (IoT) has emerged as a key application context in the design and evolution of technologies in the transition toward a 5G ecosystem. More and more IoT technologies have entered the market and represent important enablers in the deployment of networks of interconnected devices. As network and spatial device densities grow, energy efficiency and consumption are becoming an important aspect in analyzing the performance and suitability of different technologies. In this framework, this survey presents an extensive review of IoT technologies, including both Low-Power Short-Area Networks (LPSANs) and Low-Power Wide-Area Networks (LPWANs), from the perspective of energy efficiency and power consumption. Existing consumption models and energy efficiency mechanisms are categorized, analyzed and discussed, in order to highlight the main trends proposed in literature and standards toward achieving energy-efficient IoT networks. Current limitations and open challenges are also discussed, aiming at highlighting new possible research directions

    Intelligent Sensor Networks

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    In the last decade, wireless or wired sensor networks have attracted much attention. However, most designs target general sensor network issues including protocol stack (routing, MAC, etc.) and security issues. This book focuses on the close integration of sensing, networking, and smart signal processing via machine learning. Based on their world-class research, the authors present the fundamentals of intelligent sensor networks. They cover sensing and sampling, distributed signal processing, and intelligent signal learning. In addition, they present cutting-edge research results from leading experts

    Energy Management in RFID-Sensor Networks: Taxonomy and Challenges

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    Ubiquitous Computing is foreseen to play an important role for data production and network connectivity in the coming decades. The Internet of Things (IoT) research which has the capability to encapsulate identification potential and sensing capabilities, strives towards the objective of developing seamless, interoperable and securely integrated systems which can be achieved by connecting the Internet with computing devices. This gives way for the evolution of wireless energy harvesting and power transmission using computing devices. Radio Frequency (RF) based Energy Management (EM) has become the backbone for providing energy to wireless integrated systems. The two main techniques for EM in RFID Sensor Networks (RSN) are Energy Harvesting (EH) and Energy Transfer (ET). These techniques enable the dynamic energy level maintenance and optimisation as well as ensuring reliable communication which adheres to the goal of increased network performance and lifetime. In this paper, we present an overview of RSN, its types of integration and relative applications. We then provide the state-of-the-art EM techniques and strategies for RSN from August 2009 till date, thereby reviewing the existing EH and ET mechanisms designed for RSN. The taxonomy on various challenges for EM in RSN has also been articulated for open research directives
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