XXXV Simpósio Brasileiro de Telecomunicações e Processamento de Sinais

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Compressão de Imagens Baseada em Quantização Vetorial e Transformada Discreta do Cosseno
Fellipe André Lucena de Oliveira, Waslon Terllizzie Araújo Lopes

DOI: 10.14209/sbrt.2017.11
Keywords: Vector Quantization Discrete Cosine Transform Image Compression.
Abstract
This paper discusses the use of Vector Quantization (QV) and Discrete Cosine Transform (DCT) in image compression, in order to evaluate the performance of the combination of these techniques. Simulation results concerning the quantization of the DCT coefficients show that the joint use of the techniques leads, in average, to a smaller distortion when compared to the use of QV in the spatial domain, for most part of the considered coding rates.

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Circularly Polarized Aperture-Coupled Microstrip Antenna for Nano-Satellites
Filipe G. Ferreira, Juner M. Vieira, Diego P. Fumagalli, Lucas S. Pereira, Marcos V. T. Heckler

DOI: 10.14209/sbrt.2017.12
Keywords: Microstrip Antenna Aperture-Coupled Antenna Satellite Communications.
Abstract
In this paper, the design of an aperture-coupled microstrip antenna to be installed onto a nano-satellite is described. The proposed antenna has been optimized to operate at 2.26 GHz (S-Band), which is the operating frequency of the downlink channel of the Brazilian System for Meteorological Data Acquisition. The electromagnetic analysis is done by using HFSS software. For the design validation, prototypes were manufactured and the comparison between simulations and measurements indicates good performance of the proposed antenna.

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Effects of diversity on the sum rate of a multiuser M-FSK system over fast Rayleigh fading channel
Manish Sharma

DOI: 10.14209/sbrt.2017.13
Keywords: MFSK Multiuser system diversity fading channel.
Abstract
This paper shows how spatial diversity affects multiuser system rate when a multilevel frequency shift keying modulation signal is transmitted over a fast Rayleigh fading channel with additive white Gaussian noise. No specific multiple access method is used. The channel’s short coherence time precludes the system from estimation or tracking channel parameters. Results show that, in this situation, transmitter diversity is ineffective while receiver diversity has a considerable influence on system rate, as well as increasing the optimum number of users that can share the channel at the same time. It is also shown that in this scenario spectral efficiency can be improved by increasing the number of frequency slots, in opposition to the single user Gaussian noise case.

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Nova Abordagem de Redes Neurais de Função de Base Radial de Valores Complexos para Modelagem Comportamental de Amplificadores de Potência
Walter Bastos Pfeffer, Eduardo Gonçalves de Lima

DOI: 10.14209/sbrt.2017.14
Keywords: Modeling neural networks power amplifier radio frequency wireless communication systems
Abstract
This work deals with the behavioral modeling of power amplifiers for wireless communication systems based on complex-valued radial basis function neural network (CVRBFNN). In this work, modifications on the CVRBFNN input and output are proposed with the purpose of optimizing its usage for low-pass equivalent modeling. In comparison with a previous approach of same computational complexity, results from a case study show an improvement in modeling accuracy of up to 8.74 dB in normalized mean square error by the adoption of the proposed configuration

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Mitigação do Ruído Impulsivo em Sistemas de Comunicações Digitais
Hugerles S. Silva, Marcelo S. de Alencar, Wamberto J. L. de Queiroz, Rodrigo de A. Coelho

DOI: 10.14209/sbrt.2017.15
Keywords: Wiener Filter Impulsive Noise Digital Signal.
Abstract
This paper presents a new strategy for the mitigation of gaussian impulsive gated noise and double gated binary, using optimal linear systems theory applied to digital communication systems. For the analyzed impulsive noise models, the mean square errors were calculated through signal to noise ratio for different values of and .

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Knowledge-Aided Parameter Estimation Based on Conjugate Gradient Algorithms
Silvio Fernando Bernardes Pinto, Rodrigo C. de Lamare

DOI: 10.14209/sbrt.2017.16
Keywords:
Abstract
The performance of many parameter estimation algorithms used for direction finding and localization techniques depends on the accuracy of the signal covariance matrix estimate. For a small number of sensors, the commonly used sample covariance matrix estimation procedure may only provide a poor estimate of the unknown true covariance matrix. In scenarios with low signal-to-noise ratio, stationary and non-stationary signal sources, a more accurate estimate of the signal covariance matrix can be achieved by incorporating a priori knowledge about the direction of arrival (DOA) of dominant signals. In this paper, we combine the weighted sample covariance matrix and a weighted knowledge-aided (KA) covariance matrix. We present a KA-Conjugate Gradient (KA-CG) algorithm that processes the enhanced covariance matrix estimate. Simulation results show that the proposed KA-CG algorithm substantially improves the probability of resolution of unknown close sources in the system, especially at middle low signal-to-noise ratios (SNR), requiring a reasonable number of samples for this aim.

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Método de Concepção de Sistema de Transmissão Ponto Multiponto com Enfoque na Ocupação Espectral, Potência Recebida e Probabilidade de Outage
Theoma Muriel Sanches Otobo, Horácio Tertuliano Filho

DOI: 10.14209/sbrt.2017.17
Keywords: Transmission System Spectral Occupancy Received Power Outage Probability.
Abstract
Much is written about the process of conception of a communication system, considering the different types of modulation, transmission rates as well as the possible services in it Transported. However, the operationalization of the stages of conception of a system of Transmission (which is the fundamental for communication exist in the future) has little updated bibliography making it difficult therefore the macro understanding of functioning of the system. The motivation of this work is based on the idea of analyzing transmission systems with a more detailed precision of these three aspects considered important: Spectral Occupation, Power and Probability of Outage.

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Desenvolvimento de antenas de microfita de padrão elíptico e retangular em 28 GHz aplicadas ao 5G
Jose Bruno O. de Araújo, Vanessa P. R. Magri Souza, Tadeu N. Ferreira, Leni J. Matos

DOI: 10.14209/sbrt.2017.19
Keywords: 5G Printed antenna Microstrip antenna Insertion loss.
Abstract
This paper presents the development, analyzis and comparison between elliptical and rectangular microstrip patch antennas in order to apply them to the 5th generation technology of wireless communication at the frequency of 28 GHz. The software High Frequency Structure Simulator (HFSS) was used for the simulations and the performance was analysed over the gain, return loss, insertion loss and radiation pattern. The antennas were manufactured using RT/Duroid 5880LZ laminates with the lowest dielectric constant available, equals to 1.96. Measurements of return loss with the developed prototype show good adjustment to the simulated results, presenting 27.78 dB of return loss for the rectangular microstrip patch and 15.75 dB for the elliptical one, both around 28 GHz.

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Filtro de ressonância de modo guiado feito de FSS dielétrica: Caracterização e projeto.
Domingos Marcos Canga, Felipe Beltrán Mejía

DOI: 10.14209/sbrt.2017.20
Keywords: Superfícies seletivas em frequência (FSS) Filtro de ressonância de modo guiado Projeto do filtro Análise de tolerância Estruturas dielétricas.
Abstract
Neste trabalho apresentamos o desenvolvimento de um filtro de ressonância monolítico. O filtro projetado apresenta uma atenuação na ordem de 36 dB na frequência de ressonância de 1.5 GHz e alta transmissão no resto da faixa de frequência. Este filtro também apresenta um bom desempenho quando submetido a potências elevadas. Além disso, o filtro pode ser impresso a baixo custo usando impressoras 3D convencionais.

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Interferência de White Space Devices em receptores de TV Digital
Mauro Vieira de Lima, José Mauro P. Fortes

DOI: 10.14209/sbrt.2017.21
Keywords: White space device interferência agregada rádio cognitivo.
Abstract
O órgão regulador de telecomunicações do Reino Unido, Ofcom, publicou um regulamento que estabelece a potência de transmissão máxima para White Space Devices (WSDs) que operam, em caráter secundário, em uma célula de 100m x 100m do sistema primário de TV digital. A metodologia Ofcom é baseada em uma interferência de entrada única e não impõe restrições à interferência agregada gerada por múltiplos WSDs. Um artigo anterior investigou os limites nos quais a interferência agregada ultrapassa os limiares regulatórios da metodologia Ofcom. No artigo, as potências de transmissão dos WSDs são obtidas utilizando uma abordagem determinística na qual os WSDs em uma célula dividem igualmente a potência de transmissão máxima desta célula. No presente trabalho, as potências de transmissão dos WSDs são modeladas como variáveis aleatórias estatisticamente independentes, refletindo uma situação mais realista, uma vez que a tecnologia atual permite o uso de potências de transmissão que dependem do tipo e da qualidade do serviço. Este novo método probabilístico é comparado ao método determinístico investigado anteriormente.

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