Navegando por Autor "CASTRO, Bruno Souza Lyra"

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Acesso aberto (Open Access)
Comparison between known propagation models using least squares tuning algorithm on 5.8 GHz in Amazon region cities
(2011-06) CASTRO, Bruno Souza Lyra; PINHEIRO, Márcio Rodrigues; CAVALCANTE, Gervásio Protásio dos Santos; GOMES, Igor Ruiz; CARNEIRO, Oziel de Oliveira
This paper presents a performance comparison between known propagation Models through least squares tuning algorithm for 5.8 GHz frequency band. The studied environment is based on the 12 cities located in Amazon Region. After adjustments and simulations, SUI Model showed the smaller RMS error and standard deviation when compared with COST231-Hata and ECC-33 models.
Acesso aberto (Open Access)
Modelagem Cross-Layer da qualidade de experiência para transmissões de vídeo em sistemas sem fio OFDM
(Universidade Federal do Pará, 2014-02-28) CASTRO, Bruno Souza Lyra; CAVALCANTE, Gervásio Protásio dos Santos; http://lattes.cnpq.br/2265948982068382
This work presents a study about video transmission in wireless systems. The applied methodology aims to prove the existence of a direct relationship between BER and quality loss (PSNR loss) on video streams in OFDM (Orthogonal Frequency Division) systems. The results were obtained from simulations, developed in MatlabTM environment, and, measurements in real scenarios, held on university campus and inside the research laboratory in an controlled environment. From the comparison between simulated and measured data it was possible to prove the relationship between BER and PSNR loss, which led to the formulation of an empirical Cross-Layer Model with exponential characteristic. The modeling has obtained a RMS error and standard deviation close to 1.65 dB when compared to simulations. Moreover, its validation was performed from data obtained from real-world scenarios, which were not used to adjust the parameters of the proposed equation. This Cross-Layer model does not depend on the type of channel or coding in FEC (Forward Error Correction), allowing future integration with commercial or open-source network planning softwares.
Acesso aberto (Open Access)
Modelo de propagação para redes sem fio fixas na banda de 5,8 GHZ em cidades típicas da região amazônica
(Universidade Federal do Pará, 2010-05-07) CASTRO, Bruno Souza Lyra; GOMES, Hermínio Simões; http://lattes.cnpq.br/0696136066497209; CAVALCANTE, Gervásio Protásio dos Santos; http://lattes.cnpq.br/2265948982068382
The study of propagation loss in the Amazon region cities involves an environment characterized by tropical climate and suburban environments densely arborous. Based in the importance of ISM band 5.8 GHz, this work presents a propagation model for this frequency band, combining the characteristics of attenuation experienced by a radio wave when it propagates in typical environments found in Amazon region cities. For such purpose, measurements of the received power were carried out in 335 fixed customers distributed in 12 towns in northern Brazil, which are served by digital inclusion program in the state of Pará, Navega Pará. Measurements with mobility were also carried out on the Federal University of Pará (UFPA) area. Still, it is presented the performance of the proposed model over other models (SUI model and COST231-Hata), described in the literature, when in fixed and mobile networks. Performance metrics such as RMS error and standard deviation were applied taking as reference the measured data. Tuning procedure of the model parameters is performed by the method of linear least squares, applied in two steps to reduce uncertainty about the parameters set. The proposed model achieved an RMS error of 3.8 dB and standard deviation of 2.3 dB, surpassing all other models that had RMS errors above 10 dB and standard deviations over 5 dB. The results show its efficiency on other models to predict losses in the range of 5.8 GHz in stationary and mobile systems.