832 resultados para filtro passivo stripline passa-banda, ricetrasmissione wireless UWB, parametri S


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Incluye bibliografía

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Incluye bibliografía

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Banda ancha y sociedad del conocimiento: Interconectando América del Sur, Jorge Atton Palma.Despliegue de la banda ancha e integración digital, Sergio Scarabino. “Se puede llegar a más del 50% de reducción de las tarifas de banda ancha”, entrevista a Cezar Alvarez. Cooperación interregional para el impulso de la banda ancha Escuela de gestores de políticas públicas y Diálogo Regional. “Es importante que las comparaciones se hagan sobre características cuantificables y comparables”, entrevista a Omar de León. “El ORBA ha ayudado a generar mecanismos de cooperación entre países”, entrevista a Fernando Rojas. “Es ideal que la región armonice el uso del espectro radioeléctrico”, entrevista a René Bustillo. La banda ancha móvil impulsará una nueva ola de innovación en América Latina Sebastián Cabello.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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The increased demand for using the Industrial, Scientific and Medical (ISM) unlicensed frequency spectrum has caused interference problems and lack of resource availability for wireless networks. Cognitive radio (CR) have emerged as an alternative to reduce interference and intelligently use the spectrum. Several protocols were proposed aiming to mitigate these problems, but most have not been implemented in real devices. This work presents an architecture for Intelligent Sensing for Cognitive Radios (ISCRa), and a spectrum decision model (SDM) based on Artificial Neural Networks (ANN), which uses as input a database with local spectrum behavior and a database with primary users information. For comparison, a spectrum decision model based on AHP, which employs advanced techniques in its spectrum decision method was implemented. Another spectrum decision model that considers only a physical parameter for channel classification was also implemented. Spectrum decision models evaluated, as well as ISCRa's architecture were developed in GNU-Radio framework and implemented on real nodes. Evaluation of SDMs considered metrics of: delivery rate, latency (Round Trip Time - RTT) and handoff. Experiments on real nodes showed that ISCRa architecture with ANN based SDM increased packet delivery rate and presented fewer frequency variation (handoff) while maintaining latency. Considering higher bandwidth as application's Quality of Service requirement, ANN-SDM obtained the best results when compared to other SDM for cognitive radio networks (CRN).

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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En la presente publicación se analiza de manera comparativa el grado de difusión de internet en América Latina y el Caribe y se plantean algunos desafíos de política pública para acortar la brecha digital con los países desarrollados y entre los países de la región.