955 resultados para Comunicação sem fio


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Pós-graduação em Engenharia Elétrica - FEIS

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Smart grids are the focus of major study today because of the necessity of modernization in electrical systems and reduction of greenhouse gas emissions that increases global warming. Reaching the best deployment method, you must first of all know the current electrical system and how to use them for the benefit of this new technology. Preparing the action plan we should be aware of the main points of smart grids in each step of the electricity system - generation, transmission and distribution. Analyzed these topics, this work will focus on the first step in the implementation of the smart grids: the smart meters, tool which is already being implemented in Brazil. The main characteristics and applications of these devices, as well as their communication structure with the core distributors will be showed during the paper. Finally, we present a case study which will be discussed and analyzed based in the results obtained with the implementation of smart meters in the city of Vancouver, Canada, where we have a considerable savings already in the first year, with fully paying the initial investment and still have a profit

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Wireless communications is a feature that has become indispensable for many people in the whole world. Through this feature, communication process can become much more efficient, allowing people to access information much more quickly wherever they are. The constant evolution of communication technologies allows the development of new unthinkable applications and services. This new range of possibilities brings greater mobility and efficiency for final users and also helps service providers and carriers to improve the quality of services offered by them. This study presents the principles of wireless communication and the Wi-Fi technology as well as its most modern applications, covering from the basics of computer networks to the procedures of planning a wireless network, concepts of radio frequency, antennas, patterns, regulatory agencies, network equipment, protocols and network monitoring

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This paper presents a technique dubbed WiMAX radio link, the IEEE 802.16 was completed in October 2001 and published on April 8, 2002 and is constantly updated, this technology specifies an interface for wireless metropolitan networks (WMAN) and is under control of the WiMAX Forum, which is a group of companies responsible for the dissipation of this technology in the world, the great benefit of this standard is to offer broadband Internet connection in areas where there is no infrastructure such as fiber optics that has a cost higher. The main purpose of this paper is to present the theoretical and technical characteristics of this technology for both the standard for fixed and mobile standard, regulation of frequency bands by the FCC and description of the physical layer, through to basic concepts are used in many other types of radio link and technologies have been adapted and updated for this little-known standard, allowing a greater range and speed, which are specified and differentiate these advancements is one of the contributions of the work done here. After the theoretical conceptualization stage, a real case study has been inserted in this work to demonstrate the effectiveness of this technology deployed. The idea of presenting this case study is linked to a better view of the use of standard in the market, nationwide

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In this paper expounds on the major phases or generations of the evolutionary process of wireless mobile communication, emphasizing their characteristics and changes over time. The main benefit of this process is the rate of data transfer remembering capacity spectral and methods of harnessing and improving its efficiency. The current network today is 4G and the technologies developed over the following requirements of the ITU are: Long Term Evolution Advanced (LTE-Advanced) and WirelessMAN-Advanced as part of the WiMAX IEEE 802.16m also described in this graduate work

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Pós-graduação em Engenharia Mecânica - FEG

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This paper presents a design and construct the system of data acquisition with wireless transmission of some important parameters like motor temperature, motor rotation and velocity of Unesp Racing´s formula car prototype from Universidade Estadual Paulista, Campus Guaratinguetá. This system development presents a contribution for the electrical technical features adding important points in the competition due car´s electric, in addition, enables preventive maintenance and fine adjustment of the car with the data obtained during training and racing

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Pós-graduação em Ciência da Computação - IBILCE

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The use of Information and Communication Technology has grown in most agricultural activities. As a consequence, it has changed the way of thinking and acting of the farmer who wants to establish a more and more competitive market. However, the high costs of acquisition and maintenance of those technologies may be a factor which can inhibit its spread and acceptance, mainly to a large number of small grain Brazilian farmers. In this context, there is a need for innovative solutions that are proper for this universe of farmers. Starting from this premise, this paper presents the development of a low cost prototype to the monitoring process of temperature and humidity values of grains stored in silos, using communication based on wireless technology by radio frequency. Therefore, the economic implications of cost/benefit ratio of innovative application of wireless transmission in the process of thermometry of grains were analysed. The prototype was made of two electronic units, one of acquisition and another one of data reception, as well as computational software, which offered the farmer more precise information for the control of aeration. By means of stability, integrity and reliability tests of data transmission via radio, using low cost electronic components, the development system can be considered as potentially viable. It presented the difference regarding the wireless communication via radio in the process of grains thermometry, providing mobility, reducing cabling costs and maintenance, and also offering an easy system expansion; it was also appropriate to temperature and humidity monitoring in grain silos; and revealed operational viability, besides the low cost development when compared to similar products available in the Brazilian market.

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Pós-graduação em Engenharia Elétrica - FEIS

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A pesquisa considera a difusão de celulares e smartphones e as consequências deste fato em possibilidades para o ensino-aprendizagem. Aparatos de comunicação sempre estiveram ligados ao processo de ensino-aprendizagem. Entretanto, com o desenvolvimento mais intenso, nas últimas décadas, das Tecnologias de Informação e Comunicação (TIC), essa relação vem ganhando novos contornos. Surge a Internet, a evolução das máquinas computacionais e, recentemente, a explosão dos dispositivos móveis, fornecendo novos produtos e serviços convergentes. Nesse contexto, celulares e smartphones tem sido utilizados e recomendados para apoio e complemento do processo de ensino-aprendizagem: a chamada Aprendizagem Móvel. Esse ramo cresce devido à rápida expansão e barateamento dessas tecnologias na sociedade. Para verificar cientificamente essa relação foi realizada uma pesquisa de natureza qualitativa, do tipo exploratória, com dois projetos de Aprendizagem Móvel em andamento no Brasil, o Palma – Programa de Alfabetização na Língua Materna e o Escola Com Celular – ECC. Assim, a partir dos dados provenientes da pesquisa, identificamos alguns aspectos relacionados ao uso de celulares e smartphones para o processo de ensino-aprendizagem que contribuem na compreensão desse campo ainda em construção no Brasil. O uso desses dispositivos como suporte para processos de ensino-aprendizagem nos projetos estudados é delineado pelos aspectos tecnologia, dispositivo, público e contexto e novas tecnologias e Aprendizagem Móvel. O aspecto dispositivo desdobra-se em dimensões como disseminação, multifuncionalidade e acessibilidade que embasam os projetos, ainda favorece características apontadas como importantes para o processo de ensino-aprendizagem na atualidade, como mobilidade e portabilidade. Os projetos pesquisados demonstram potencial e metodologia adequada aos contextos para os quais foram criados e aplicados. Entretanto, a pesquisa indicou que ao mesmo tempo em que celulares e smartphones representam o ápice da convergência tecnológica e são considerados extremamente populares e acessíveis na sociedade contemporânea, com possibilidades concretas como nos projetos estudados, não conseguiram conquistar uma posição sólida como suporte para o ensino-aprendizagem. Tal indicação se deve, de acordo com o corpus, à carência de alguns fatores, como: fomento, as práticas se mostram extremamente dependentes da iniciativa pública ou privada para sua extensão e continuidade; sensibilização para o uso de tecnologias disponíveis, não consideram o aparelho dos próprios alunos e um planejamento que inclua, capacite e incentive o uso desses dispositivos. Além disso, a pesquisa também destaca a necessidade de uma visão crítica do uso e papel da tecnologia nesses processos.

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Nowadays wireless communication has emerged as a tendency in industry environments. In part this interest is due to the ease of deployment and maintenance, which dispenses sophisticated designs and wired infrastructure (which in industrial environment often prohibitively expensive) besides enabling the addition of new applications when compared to their wired counterparts. Despite its high degree of applicability, an industrial wireless sensor network faces some challenges. One of the most challenging problems are its reliability, energy consumption and the environment interference. In this dissertation will discuss the problem of asset analysis in wireless industrial networks for the WirelessHART standard by implementing a monitoring system. The system allows to carry out various activities of independent asset management manufacturers, such as prediction of battery life, maintenance, reliability data, topology, and the possibility of creating new metrics from open and standardized development libraries. Through the implementation of this tool is intended to contribute to integration of wireless technologies in industrial environments.

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Information extraction is a frequent and relevant problem in digital signal processing. In the past few years, different methods have been utilized for the parameterization of signals and the achievement of efficient descriptors. When the signals possess statistical cyclostationary properties, the Cyclic Autocorrelation Function (CAF) and the Spectral Cyclic Density (SCD) can be used to extract second-order cyclostationary information. However, second-order cyclostationary information is poor in nongaussian signals, as the cyclostationary analysis in this case should comprise higher-order statistical information. This paper proposes a new mathematical tool for the higher-order cyclostationary analysis based on the correntropy function. Specifically, the cyclostationary analysis is revisited focusing on the information theory, while the Cyclic Correntropy Function (CCF) and Cyclic Correntropy Spectral Density (CCSD) are also defined. Besides, it is analytically proven that the CCF contains information regarding second- and higher-order cyclostationary moments, being a generalization of the CAF. The performance of the aforementioned new functions in the extraction of higher-order cyclostationary characteristics is analyzed in a wireless communication system where nongaussian noise exists.

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The communication in vehicular ad hoc networks (VANETs) is commonly divided in two scenarios, namely vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I). Aiming at establishing secure communication against eavesdroppers, recent works have proposed the exchange of secret keys based on the variation in received signal strength (RSS). However, the performance of such scheme depends on the channel variation rate, being more appropriate for scenarios where the channel varies rapidly, as is usually the case with V2V communication. In the communication V2I, the channel commonly undergoes slow fading. In this work we propose the use of multiple antennas in order to artificially generate a fast fading channel so that the extraction of secret keys out of the RSS becomes feasible in a V2I scenario. Numerical analysis shows that the proposed model can outperform, in terms of secret bit extraction rate, a frequency hopping-based method proposed in the literature.

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In this research work, a new routing protocol for Opportunistic Networks is presented. The proposed protocol is called PSONET (PSO for Opportunistic Networks) since the proposal uses a hybrid system composed of a Particle Swarm Optimization algorithm (PSO). The main motivation for using the PSO is to take advantage of its search based on individuals and their learning adaptation. The PSONET uses the Particle Swarm Optimization technique to drive the network traffic through of a good subset of forwarders messages. The PSONET analyzes network communication conditions, detecting whether each node has sparse or dense connections and thus make better decisions about routing messages. The PSONET protocol is compared with the Epidemic and PROPHET protocols in three different scenarios of mobility: a mobility model based in activities, which simulates the everyday life of people in their work activities, leisure and rest; a mobility model based on a community of people, which simulates a group of people in their communities, which eventually will contact other people who may or may not be part of your community, to exchange information; and a random mobility pattern, which simulates a scenario divided into communities where people choose a destination at random, and based on the restriction map, move to this destination using the shortest path. The simulation results, obtained through The ONE simulator, show that in scenarios where the mobility model based on a community of people and also where the mobility model is random, the PSONET protocol achieves a higher messages delivery rate and a lower replication messages compared with the Epidemic and PROPHET protocols.