Com o aumento das aplicações e dispositivos para Internet das Coisas, muitos esforços para reduzir potência dissipada nos transceptores foram investidos. A maioria deles, entretanto, focam individualmente no rádio, nos conversores analógicos para digital e viceversa, e na arquitetura de banda base digital. Como consequência, há pouca margem para melhorias na potência dissipada nestes blocos isolados que compense o enorme esforço. Portanto, este trabalho propõe uma arquitetura adaptativa a nível de sistema focando em reduzir o consumo no conversor analógico para digital e no receptor digital. Ele utiliza um algoritmo robusto para o receptor banda base digital, um conversor analógico para digital topologia Sigma-Delta e um bloco de controle realimentado conforme a relação sinal ruído medida do pacote recebido. O sistema foi projetado para o protocolo IEEE 802.15.4. Para validação do sistema e estimar a potência consumida foi feito um modelo de sistema utilizando a ferramenta Matlab, uma descrição do hardware em linguagem Verilog e uma síntese lógica utilizando o processo da X-FAB XC018. As simulações mostram uma redução na potência consumida pelo sistema de até 13% e ainda atingindo os requisitos do protocolo. Os resultados deste trabalho foram publicados na conferência internacional em tecnologia de instrumentação e medidas de 2014 realizada na cidade de Montevidéu no Uruguai. / With the increase of Internet of Things applications and devices, many efforts to reduce power consumption in transceiver has been invested. Most of them targeted in RF frontend, converters, or in the digital baseband architecture individually. As result, there are few margins nowadays for power improvement in these blocks singly that compensates the huge hard work required. The next optimization step leads to a system level analysis seeking design space and new possibilities expansion. It is in this field that adaptive systems approaches are conquering ground recently. The solutions combines Radio Frequency (RF) and process variation techniques, Low Pass Filters (LPF) and Analog to Digital Converters (ADCs) adjustment for better performance, digital baseband bit width adaptive according to income packet SNR, configurable ADC resolution and topology, and others. In this scenario the current work proposes an adaptive system level architecture targeting ADC and digital receiver power reduction. It uses a robust algorithm for digital baseband receiver, a Sigma-Delta ADC, and suggests a feedback control block based on packet SNR measure. The system was designed for the IEEE 802.15.4 standard and required system modeling using Matlab tool, hardware description in Verilog language, and logic synthesis using X-FAB XC018 process for validation and power consumption estimation. Simulations show up to 15% of system power reduction and still meeting the standard requirements. The work results were published in the International Instrumentation and Measurement Technology Conference of 2014 occurred in Montevideo - Uruguay.

A segurança da informação, a diversidade de rotas entre os dispositivos da rede, o acesso ao meio de modo determinístico e isento de colisões e a mudança de canal frequente tornam a comunicação no protocolo WirelessHART robusta e confiável para utilização em meio industrial. Entretanto, para adoção crescente dessa tecnologia, é necessário que os fabricantes de sensores e atuadores industriais desenvolvam dispositivos WirelessHART. Disto surge a necessidade de criação de ferramentas capazes de auxiliar o desenvolvimento e depuração destes novos dispositivos de rede. O Analisador de rede WirelessHART é, sem dúvida, uma delas. Diversas abordagens são propostas para a análise de redes WirelessHART. Entretanto, em todas elas a utilização de um microcomputador como elemento do sistema inviabiliza sua utilização em campo. A presença de cabos, armazenamento local dos dados e exigência de baterias são alguns dos aspectos relevantes que devem ser levados em consideração quando o sistema precisa ser utilizado em campo. O presente trabalho propõe alternativas aos sistemas de análise de redes atuais apresentando duas propostas conceitualmente diferentes mas que cumprem os requisitos básicos para sua utilização em campo. Uma destas abordagens, baseada na proposta de integração entre um dispositivo de campo e o método inovador de captura de mensagens utilizando apenas um transceptor, é implementado como prova do conceito. / WirelessHART is a robust and reliable protocol for industrial environment usage because of its secure mechanism, the ability of programming several communication routes between network devices, and deterministic, free of collisions channel hopping medium access controller. However, in order to increase the adoption of this technology, it is necessary to increase the amount of WirelessHART manufacturers to develop industrial sensors and actuators devices. This leads to the necessity of create tools that will assist the development and debugging of new network compliant devices. The WirelessHART network analyzer is undoubtedly one of these tools. Various approaches are being proposed for the analysis of WirelessHART networks. However, all of them make use of a microcomputer as an element of the whole system and this difficults their use in real field applications. The presence of wires, lack of local data storage and other aspects such as batteries limitations must be considered when the users intend to use analysis systems in field. This work proposes alternatives to current analysis networks systems by presenting two conceptually different proposals that meet the basic requirements for the use in the field. One of them is based on the proposed integration between a field device and an innovative method of capturing messages using only one transceiver, which is implemented as proof of concept.

Made available in DSpace on 2014-06-12T17:35:16Z (GMT). No. of bitstreams: 2 arquivo2009_1.pdf: 3503480 bytes, checksum: 85d90aa1952ca122f373c0f061692038 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2010 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / O padrão zigbee foi utilizado na instrumentação de molas helicoidais de Ti-Ni utilizando, assim, a porta USB para comunicação de dados sem fio com o laptop e a mola utilizando a plataforma operacional Linux. Um estudo do comportamento da tensão elétrica da mola Ti-Ni sob a variação da corrente elétrica e distensão mecânica foi feito. Foi observado que para condições normais de temperatura e ambiente, o sistema apresentou variação linear na faixa analisada. E que uma análise estatística para uma faixa de operação de corrente e comprimentos constantes, a mola apresentou condições suficientes para a instrumentação. Foram desenvolvidos programas para que as tecnologias zigbee, microcontrolador, PIC16F877A e USB pudessem se comunicar entre si. A implementação do algoritmo sugerido mostrou-se, ao longo dos testes, um desempenho positivo. Uma análise do erro que o sistema de instrumentação sem fio poderia introduzir no monitoramento foi feita. Com isso, constatou-se que o erro absoluto do mesmo não apresentou nenhuma influência no monitoramento da distensão mecânica da mola. Os resultados mostraram-se favoráveis ao objetivo da dissertação e foi verificado que o monitoramento sem fio de distensão mecânica da mola Ti-Ni apresentou confiabilidade considerável

Autorizada por el autor, pero con restricción para ser publicada a texto completo hasta el año 2015 / Esta memoria de título se enmarca en un proyecto que busca ofrecer una solución completa de monitoreo remoto. El control está enfocado en distintos dispositivos de medición en el rubro minero. El objetivo general consiste en el desarrollo de un punto de acceso, el cual permite la integración de una red de sensores con diferentes tecnologías de comunicaciones inalámbricas, tales como telefonía celular u otras compatibles con el protocolo TCP/IP. El sistema electrónico desarrollado adquiere la información desde una malla de sensores. Se utiliza un microcontrolador que procesa los datos de acuerdo a cada modo de funcionamiento. El objetivo es enviar la información de manera serial a un módem GSM/GPRS, en el caso de comunicación con la red de celular, o directamente a un conversor TCP/IP para tecnologías que utilizan este protocolo. Otra importante función del circuito integrado es configurar y controlar el punto de acceso, posibilitando automatizar el diseño realizado. El resultado es un producto que permite enviar datos desde los sensores de medición, hacia una red de telefonía celular o con destino de alguna tecnología basada en el protocolo TCP/IP. El prototipo implementado se caracteriza por ser escalable de acuerdo a los requerimientos del usuario, resolviendo una necesidad de la industria minera. Se concluye que es factible transmitir la información adquirida en distintos dispositivos, ubicados en diferentes zonas de una faena, de manera confiable y con una baja inversión. La empresa patrocinante de esta memoria ha manifestado su interés en comercializarlo, al ser un desarrollo que no tiene símil en el mercado. El trabajo futuro de esta implementación es poner en funcionamiento un sistema de respaldo para los datos, en momentos que se pierda conexión con la red de celular.

Abstract The main objective of this thesis project is to implement a wireless vital signs monitoring system for measuring the ECG of a patient in the home environment. The research focuses on two specific research objectives: 1) the development of a distributed healthcare system for vital signs monitoring using wireless sensor network devices and 2) a practical test and performance evaluation for the reliability for such low-rate wireless technology in ubiquitous health monitoring applications. The first section of the thesis describes the design and implementation of a ubiquitous healthcare system constructed from tiny components for the home healthcare of elderly persons. The system comprises a smart shirt with ECG electrodes and acceleration sensors, a wireless sensor network node, a base station and a server computer for the continuous monitoring of ECG signals. ECG data is a commonly used vital sign in clinical and trauma care. The ECG data is displayed on a graphical user interface (GUI) by transferring it to a PDA or a terminal PC. The smart shirt is a wearable T-shirt designed to collect ECG and acceleration signals from the human body in the course of daily life. In the second section, a performance evaluation of the reliability of IEEE 802.15.4 low-rate wireless ubiquitous health monitoring is presented. Three scenarios of performance studies are applied through practical tests: 1) the effects of the distance between sensor nodes and base-station, 2) the deployment of the number of sensor nodes in a network and 3) data transmission using different time intervals. These factors were measured to analyse the reliability of the developed technology in low-rate wireless ubiquitous health monitoring applications. The results showed how the relationship between the bit-error-rate (BER) and signal-to-noise ratio (SNR) was affected when varying the distance between sensor node and base-station, through the deployment of the number of sensor nodes in a network and through data transmission using different time intervals.

Wireless Sensor Networks (WSNs) have enticed a strong attention in the research community due to the broad range of applications and services they support. WSNs are composed of intelligent sensor nodes that have the capabilities to monitor different types of environmental phenomena or critical activities. Sensor nodes operate under stringent requirements of scarce power resources, limited storage capacities, limited processing capabilities, and hostile environmental surroundings. However, conserving sensor nodes’ power resources is the top priority requirement in the design of a WSN as it has a direct impact on its lifetime. The IEEE 802.15.4 standard defines a set of specifications for both the PHY layer and the MAC sub-layer that abide by the distinguished requirements of WSNs. The standard’s MAC protocol employs an intelligent backoff algorithm, called the Binary Exponent Backoff (BEB), that minimizes the drainage of power in these networks. In this thesis we present an in-depth study of the IEEE 802.15.4 MAC protocol to highlight both its strong and weak aspects. We show that we have enticing opportunities to improve the performance of this protocol in the context of WSNs. We propose three new backoff algorithms, namely, the Standby-BEB (SB-BEB), the Adaptive Backoff Algorithm (ABA), and the Priority-Based BEB (PB-BEB), to replace the standard BEB. The main contribution of the thesis is that it develops a new design concept that drives the design of efficient backoff algorithms for the IEEE 802.15.4-based WSNs. The concept dictates that controlling the algorithms parameters probabilistically has a direct impact on enhancing the backoff algorithm’s performance. We provide detailed discrete-time Markov-based models (for AB-BEB and ABA) and extensive simulation studies (for the three algorithms) to prove the superiority of our new algorithms over the standard BEB.

A segurança da informação, a diversidade de rotas entre os dispositivos da rede, o acesso ao meio de modo determinístico e isento de colisões e a mudança de canal frequente tornam a comunicação no protocolo WirelessHART robusta e confiável para utilização em meio industrial. Entretanto, para adoção crescente dessa tecnologia, é necessário que os fabricantes de sensores e atuadores industriais desenvolvam dispositivos WirelessHART. Disto surge a necessidade de criação de ferramentas capazes de auxiliar o desenvolvimento e depuração destes novos dispositivos de rede. O Analisador de rede WirelessHART é, sem dúvida, uma delas. Diversas abordagens são propostas para a análise de redes WirelessHART. Entretanto, em todas elas a utilização de um microcomputador como elemento do sistema inviabiliza sua utilização em campo. A presença de cabos, armazenamento local dos dados e exigência de baterias são alguns dos aspectos relevantes que devem ser levados em consideração quando o sistema precisa ser utilizado em campo. O presente trabalho propõe alternativas aos sistemas de análise de redes atuais apresentando duas propostas conceitualmente diferentes mas que cumprem os requisitos básicos para sua utilização em campo. Uma destas abordagens, baseada na proposta de integração entre um dispositivo de campo e o método inovador de captura de mensagens utilizando apenas um transceptor, é implementado como prova do conceito. / WirelessHART is a robust and reliable protocol for industrial environment usage because of its secure mechanism, the ability of programming several communication routes between network devices, and deterministic, free of collisions channel hopping medium access controller. However, in order to increase the adoption of this technology, it is necessary to increase the amount of WirelessHART manufacturers to develop industrial sensors and actuators devices. This leads to the necessity of create tools that will assist the development and debugging of new network compliant devices. The WirelessHART network analyzer is undoubtedly one of these tools. Various approaches are being proposed for the analysis of WirelessHART networks. However, all of them make use of a microcomputer as an element of the whole system and this difficults their use in real field applications. The presence of wires, lack of local data storage and other aspects such as batteries limitations must be considered when the users intend to use analysis systems in field. This work proposes alternatives to current analysis networks systems by presenting two conceptually different proposals that meet the basic requirements for the use in the field. One of them is based on the proposed integration between a field device and an innovative method of capturing messages using only one transceiver, which is implemented as proof of concept.

This thesis describes the design of wireless sensor network (WSN) for monitoring of people and objects in a building. The work deals with issues of localization and tracking in sensor networks and algorithm implementation to sensor nodes. It also contains a description of the aplication requirements. These requirements form the basis for the proposal. The hardware part of the network consists of sensor nodes IRIS from Crossbow company. The work describes the properties of these nodes. Next part deals with of propagation model and design of the localization algorithm. The paper also describes the communication in the network. The thesis also includes a practical realization of the proposed network, the localization system and its testing. In the work is included a CD with the building schematic in AutoCAD and with source code of created applications.

This thesis deals with the issues 6LoWPAN protokolu and implementation of IPv6 on the specied platform. Introduction thesis deals with the explanation of wireless sensor networks. Next it was descibed 6LoWPAN protocol, which maps IPv6 on standard IEEE 802.15.4. The thesis further concentrates to exploration of possible operation systems, that are designed for sensor networks and then followed by comparison of their characteristics and advantages. The fth chapter is focused on he implementation of the operating system to the sensor node Iris, introduction Iris and with the structure of the operating system Contiki OS. At the end of thesis is description of the implementation of this system in the sensor node Iris.

The work deals with processing of radio received signal strength in IEEE 802.15.4 which communicates in 2.4 GHz ISM band. The signal is processed by the three approximation methods. They are tested for their effectiveness for measuring in different radio environments. Furthermore, the work deals with calculation of the most efficient coefficients for distance calculating by radio transmission fucntions. It defines the issues of such solutions on practical examples. The work also deals with the experimental algorithm for implementing dynamic calibration of the coefficients. It describes the design, processing and verification of this system in practice.