Navegando por Assunto "Perda de propagação"

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Estudo da tecnologia IEEE 802.11ac para o desenvolvimento de modelos empírico e cross-layer
(Universidade Federal do Pará, 2016-08-03) BATALHA, Lury da Silva; CASTRO, Bruno Souza Lyra; http://lattes.cnpq.br/1897829604434609; PELAES, Evaldo Gonçalves; http://lattes.cnpq.br/0255430734381362
Within the context of studies related to video streams, taking into account the wireless networks, this work presents two models where one makes the prediction of the propagation loss in the number of walls, distance and power in dB and another to measure value loss of video quality in relation to the number of walls, distance and power received in dB. measurement campaigns were conducted in a real scenario of classroom blocks the UFPA Institute of Technology (ITEC) and UFPA Telecommunication Laboratory (LCT) for the construction of the database. The planning of these measurement campaigns took into consideration some strategies: perform the tests using the variable distance regardless of the number of walls in the direct path between the server and the client, fixed distance between the client and the server and adding walls in your for path loss by obstacles and the other consists of building radial within the environment. For modeling data averages of data collected was used to obtain a better behavior database and thus get a better fit. It was also applied to wastes technique in conjunction with Linear Minimum Square technique to find the values of the constants in the equations. The propagation loss model showed satisfactory results in comparison with ITU and Keenan-Motley models for RMS metrics, absolute error and standard deviation related to the measured data. The models used for comparison purposes have RMS value above 6.5 dB above with absolute error of 6.2 dB and the standard deviation of 3 dB band, while the proposed model has obtained an RMS of 2.99 dB, with absolute error of 2.03 dB and a standard deviation of 3 dB. The model for loss of PSNR presented admissible results mainly in the absolute error of 2.61 dB with RMS value of 3.75 dB and a standard deviation of 3.9 dB.