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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Identidades do tipo MacWilliams para métricas de Lee

Jerry Pinheiro, Marcelo Firer

DOI: 10.14209/sbrt.2017.7

Keywords: MacWilliams-type Identities Lee Metric.

Abstract

MacWilliams-type identities for linear codes over Zl endowed with the Lee metric are identities relating the Lee weight distributions of codes and its duals. In this work we analyze the smallest instance: Z5, for which the existence of MacWilliamstype identities is an open problem. We show that when restricted to unidimensional codes over Z5, MacWilliams-type identities can be obtained. However, we conclude, using a 2-dimensional example, that Z5 does not admit such identities

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Application of Pattern Recognition Method in a Linguistic Experiment with Unsupervised Classification

Ali Kamel Issmael Junior, Aline Gesualdi Manhães, José Vicente Calvano

DOI: 10.14209/sbrt.2017.18

Keywords: ERP EEG Pattern Recognition Linguistics.

Abstract

Event-Related Potentials (ERP) are biological electrical signals synchronized with sensory, cognitive or motor stimuli and measured by electroencephalographs (EEG). ERP technique allows non-invasive analysis of brain functions. Based on the results obtained by Soto [1], this work extracts ERP parameters using EEGLAB® and ERPLAB® tools based on Matlab® software [6], [7], [8], [9]. The result of the research was the obtaining of supervised and unsupervised classification scenarios for the classes proposed in the mentioned experiment and the comparative study and discussion of the classification results found, using the methodology proposed by Webb [2]. This article presents the results obtained with unsupervised classification scenarios only and the supervised classification scenarios will be presented in future. The results achieved accuracies very near from the equiprobability, indicating that the use of unsupervised classifiers approaches considered are not adequate to classify Soto’s data [1]. This study is innovative in the area of Neurolinguistics, since, at least until now, there are no similar previously published works on the subject found in research databases such as: IEEExplorer; Web of Science; Elesevier and Spring. The results open the possibility of analyzing signals from individuals with this ERP methodology associated to Pattern Recognition, with the possible application of this type of analysis in diagnostic tools, assessment of language learning, among others.

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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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Secure Switch-and-Stay Combining with Multiple Antennas in Cognitive Radio Relay Networks

Guilherme Oliveira, Samuel Mafra, Evelio Fernández

DOI: 10.14209/sbrt.2017.22

Keywords: Cognitive Relay Networks Secure Switch-and-Stay Combining Multiple Antennas Physical Layer Security

Abstract

— Eavesdropping is a major concern in Cognitive Radio relay systems, due to the broadcast nature of these systems. Physical Layer Security (PLS) has been seen as a good alternative to enhance the secrecy performance of these networks. Based on the concept of perfect secrecy, PLS uses an information-theoretic approach to prevent secondary transmissions from malicious attacks. In this paper, the Secure Switch-and-Stay Combining (SSSC) protocol is extended to a multiple antenna scenario, namely Secure Switch-and-Stay Combining with Multiple Antennas (SSSC-MA) protocol. To choose the best out of two relays, the SSSC-MA is adopted, and the whole transmission process is subject to a multiple antenna eavesdropper attack. Using a Transmit Antenna Selection/Maximal Ratio Combining scheme within the SSSC-MA, the secrecy performance of the extended protocol is compared to three relaying protocols, the single relay Selective Decode-and Forward, the two relay Opportunistic Relaying and the original SSSC. Results show that the proposed SSSC-MA outperforms the other protocols, achieving satisfying secrecy performance even when the eavesdropper has more antennas than the relays.

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Super-Resolução de Imagens de Tomografia por Impedância Elétrica

Ricardo Augusto Borsoi, Julio Cesar C. Aya, Guilherme Holsbach Costa, Jose Carlos M. Bermudez

DOI: 10.14209/sbrt.2017.28

Keywords: Tomografia resolução de imagens reconstrução de imagens.

Abstract

A Tomografia por Impedância Elétrica (EIT) tem se tornado popular por apresentar diversas vantagens quando comparada a outros métodos de tomografia. Porem, a resolução de imagens adquiridas através de EIT é bastante pobre. Além disso, a característica não-uniforme das imagens resultantes do uso de técnicas de elementos finitos impede a aplicação direta de técnicas tradicionais de reconstrução com super-resolução (SRR). Neste trabalho, um método para a super-resolução de imagens de EIT baseado em reamostragem e proposto. Resultados preliminares indicam que a técnica apresentada pode levar a ganhos substanciais na qualidade das imagens de EIT, o que pode ajudar a tornar a EIT mais competitiva com outros métodos de tomografia.

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