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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

On Forward Error Correction in IEEE 802.15.4 Wireless Sensor Networks

Li, Wei, Guo, Zhiyuan January 2012 (has links)
Wireless Sensor Networks (WSN) are used in many applications, for example industrial applications, automatic control applications, monitoring applications, to name but a few. Although WSN can employ different standards in order to achieve short range wireless communication, the mainstream of the market is toadopt the low-power, low-rate IEEE 802.15.4 standard. However, this standard does not specify any block codes on the Physical layer (PHY) and the MAC sublayer. Reliability and energy efficiency are two important metrics used to evaluate the WSN performance. In order to enhance the reliability of the WSN performance, schemes such as Forward Error Correction (FEC) and HybridAutomatic Repeat-reQuest (HARQ) can be introduced on the PHY and MACsublayer when transmitting signals. However, this will reduce the energy efficiency of the WSN. In order to investigate what does affect the reliability and energy efficiency, this thesis has been conducted with the assistance of Matlab simulations, which simulate different transmission schemes proposed by the authors. Based on the simulations, both the reliability and energy efficiency can be evaluated and the results are illustrated for both metrics. The objective of this thesis is to determine a scheme that is able to meet these metric requirements.
2

Simple Distributed Multihop Diversity Relaying Based on Repetition for Low-Power-Low-Rate Application

Li, Yanwen Unknown Date
No description available.
3

Monitoramento de temperatura em edifica??es usando redes sem fio / Temperature monitoring in buildings using wireless networks.

Oliveira, Everton Dias de 14 December 2015 (has links)
Made available in DSpace on 2016-04-04T18:25:00Z (GMT). No. of bitstreams: 1 Everton Dias de Oliveira.pdf: 3326034 bytes, checksum: 1cbd1cf1a33f81db24d9e630a5cddb94 (MD5) Previous issue date: 2015-12-14 / This paper presents the development of a system for monitoring surfasse temperature and air temperature in buildings in urban areas, using wireless data transmission with the IEEE 802.11 and IEEE 802.15.4 standards. This monitoring system includes the development of low sensors that can monitor the temperature of non-destructively, i.e. without the need to reform the building. Deals with the analysis of the use of wireless transmission networks with the IEEE 802.11 standard and the IEEE 802.15.4 standard, as a possible solution for temperature monitoring in buildings using wireless networks. Discusses the development of a technological application capable of performing the monitoring of the air temperature and surface buildings using standard wireless networks IEEE 802.15.4. It also presents a solution for temperature monitoring in intelligent buildings, using the IEEE 802.11 standard. / O presente trabalho apresenta, o desenvolvimento de um sistema para o monitoramento da temperatura de superf?cie e da temperatura do ar em edifica??es no meio urbano, utilizando transmiss?o de dados sem fio com os padr?es IEEE 802.11 e IEEE 802.15.4. Esse sistema de monitoramento compreende o desenvolvimento de sensores de baixo que possam monitorar a temperatura de forma n?o destrutiva, ou seja, sem a necessidade de reformas na edifica??o. Trata da an?lise da utiliza??o das redes de transmiss?o sem fio com o padr?o IEEE 802.11 e com o padr?o IEEE 802.15.4, como possibilidade de solu??o para o monitoramento da temperatura em edifica??es usando redes sem fio. Discorre sobre o desenvolvimento de uma aplica??o tecnol?gica capaz de realizar o monitoramento da temperatura do ar e de superf?cie em edifica??es usando redes sem fio padr?o IEEE 802.15.4. E tamb?m apresenta uma solu??o para o monitoramento da temperatura em edif?cios inteligentes, utilizando o padr?o IEEE 802.11.
4

Desenvolvimento de um software de comunica??o sem fio aplicado ? instrumenta??o de unidade de eleva??o de petr?leo tipo Plunger Lift

Oliveira, Felipe Denis Mendon?a de 13 February 2009 (has links)
Made available in DSpace on 2014-12-17T14:55:35Z (GMT). No. of bitstreams: 1 FelipeDMO.pdf: 2614728 bytes, checksum: fd69e303891800912ab5260562a5545d (MD5) Previous issue date: 2009-02-13 / This dissertation aims to develop a software applied to a communication system for a wireless sensor network (WSN) for tracking analog and digital variables and control valve of the gas flow in artificial oil s elevation units, Plunger Lift type. The reason for this implementation is due to the fact that, in the studied plant configuration, the sensors communicate with the PLC (Programmable and Logic Controller) by the cables and pipelines, making any changes in that system, such as changing the layout of it, as well as inconveniences that arise from the nature of the site, such as the vicinity s animals presence that tend to destroy the cables for interconnection of sensors to the PLC. For software development, was used communication polling method via SMAC protocol (Simple Medium Access ControlIEEE 802.15.4 standard) in the CodeWarrior environment to which generated a firmware, loaded into the WSN s transceivers, present in the kit MC13193-EVK, (all items described above are owners of Freescale Semiconductors Inc.). The network monitoring and parameterization used in its application, was developed in LabVIEW software from National Instruments. The results were obtained through the observation of the network s behavior of sensors proposal, focusing on aspects such as: indoor and outdoor quantity of packages received and lost, general aspects of reliability in data transmission, coexistence with other types of wireless networks and power consumption under different operating conditions. The results were considered satisfactory, which showed the software efficiency in this communication system / Este trabalho tem por finalidade desenvolver um software aplicado a um sistema de comunica??o de uma rede de sensores sem fio (RSSF), para monitoramento de vari?veis anal?gicas, digitais e comando de v?lvulas de passagem do fluxo de g?s em unidades de eleva??o artificial de petr?leo e g?s natural do tipo Plunger Lift. A raz?o desta implementa??o deve-se ao fato que, na configura??o da planta estudada, os sensores comunicam-se com o CLP (Controlador L?gico Program?vel) atrav?s de cabos e dutos, dificultando eventuais modifica??es nesse sistema, tais como mudan?a de layout do mesmo, al?m de inconveni?ncias que venham a surgir da pr?pria natureza do local, como a presen?a de animais nas redondezas que tendem a destruir os cabos de interconex?o dos sensores ao CLP. Para o desenvolvimento do software, foi utilizado o m?todo de comunica??o polling, atrav?s do protocolo SMAC (Simple Medium Access Control - padr?o IEEE 802.15.4), no ambiente CodeWarrior, ao qual gerou um firmware, carregado nas placas de monitoramento da RSSF, presentes no kit MC13193-EVK, (todos os itens descritos acima s?o propriet?rios da Freescale Semiconductors Inc.). O monitoramento e parametriza??o da rede utilizou uma aplica??o, desenvolvida no software LabVIEW, da National Instruments. Os resultados foram obtidos atrav?s da observa??o do comportamento da rede de sensores proposta, focando aspectos, tais como: quantidade de pacotes recebidos e perdidos em ambientes externos (Outdoor) e internos (Indoor), aspectos gerais de confiabilidade na transmiss?o dos dados, coexist?ncia entre outros tipos de redes sem fio e consumo de energia sob diferentes condi??es de opera??o. Os resultados obtidos foram considerados satisfat?rios, o que comprovou a efici?ncia do software neste sistema de comunica??o
5

Estudo e especifica??o de um sistema de instrumenta??o para unidades de eleva??o de petr?leo utilizando tecnologia sem fio

Campos, Carlo Frederico Pereira de Siqueira 27 November 2006 (has links)
Made available in DSpace on 2014-12-17T14:56:21Z (GMT). No. of bitstreams: 1 CarloFPSC.pdf: 941846 bytes, checksum: 5fe2e2c9851039018a0653de693d001c (MD5) Previous issue date: 2006-11-27 / Wireless sensor networks are reality nowadays. The growing necessity of connectivity between existing industrial plant equipments pushes the research and development of several technologies. The IEEE 802.15.4 LR-WPAN comes as a low-cost and powersaving viable solution, which are important concerns while making decisions on remote sensoring projects. This study intends to propose a wireless communication system which makes possible the monitoring of analogic and/or digital variables (i. e., the pressure studied) involved on the artificial methods for oil and gas lifting. The main issues are: To develop a software based on SMAC Standard in order to create a wireless network to monitoring analogic and/or digital variables; To evaluate the communication link based on the number of lost packets tested in different environments (indoor and outdoor) and To propose an instrumentation system consisting of wireless devices / As redes de sensores sem fio (RSSS) j? s?o uma realidade hoje em dia, pois a grande necessidade de conectividade entre os equipamentos existentes numa planta industrial impulsiona a pesquisa e o desenvolvimento de diversas tecnologias. O padr?o LR-WPAN IEE 802.15.4 apresenta-se como uma solu??o vi?vel, com baixo custo e baixo consumo de energia, requisitos importantes para a implanta??o de um sistema de sensoriamento remoto. A contribui??o deste trabalho consiste em propor um sistema de comunica??o sem fio, que possa monitorar vari?veis anal?gicas e/ou digitais (no caso do estudo em quest?o, a press?o) nos m?todos de eleva??o artificial de petr?leo e g?s natural. Os pontos principais deste estudo s?o: Desenvolver um software baseado no Padr?o SMAC com intuito de criar uma rede sem fio com fins de monitoramento de vari?veis anal?gicas e/ou digitais; Avaliar o enlace de comunica??o com rela??o a quantidade de pacotes perdidos em diferentes ambientes (ambientes internos (Indoor) e externos (Outdoor)) e, Propor um sistema de instrumenta??o utilizando tecnologia sem fio

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