A Frequency Domain Resource Allocation Technique with Reduced Complexity for PLC System

Victor Fernandes, Moises V. Ribeiro, Guilherme R. Colen, Thiago M. Peixoto

DOI: 10.14209/sbrt.2015.44

Keywords: Bit-loading algorithm resource allocation tech- nique power line communication orthogonal frequency-division multiplexing

Abstract

The present work aims to suggest a resource allocation approach to reduce computational complexity of bitloading techniques applied to power line communication (PLC) based on multicarrier modulation. This approach is based on grouping adjacent subcarriers and using the same resource allocation in this group, but it results in a datarate degradation. Thus, there is a trade-off between computational complexity reduction and datarate degradation driven by the group length. With in home power line channels data, obtained from a measure campaign covering the frequency bands 1.7-30, 1.7-50 and 1.7-100 MHz , we have shown the trade-off performance. Our results show that the suggested technique is capable of giving priority to computational complexity in exchange for a little data-rate degradation.

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Caracterização e Análise de Modelos Estatísticos de Canais com Desvanecimento Rayleigh

Douglas Tanajura Barreto de Carvalho, Leocarlos Bezerra da Silva Lima

DOI: 10.14209/sbrt.2015.45

Keywords: Fading channels Rayleigh fading com- putational modeling channels multipath Doppler ef- fect

Abstract

This paper presents a general description of Rayleigh fading channel models for mobile com- munications. The channel models are analyzed and compared considering several statistical parameters.

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An Improved Rational Model with Memory for the Digital Baseband Predistortion of Power Amplifier

Victor Gerson Matoso Francisco, Eduardo Gonçalves de Lima

DOI: 10.14209/sbrt.2015.40

Keywords: Modeling power amplifier predistortion radio frequency rational model wireless communication systems

Abstract

The use of models described by the ratio of two polynomial approximations with memory has been rece iving particular attention by the wireless communication community. Rational models with memory require a lower number of coefficients and work better with extrapolation dat a than polynomial approximations. This work proposes a nov el rational model with memory that, in comparison with previous approaches having the same number of parameters, ca n increase the modeling accuracy. The novelties of the propose d rational model, in comparison with the best available ration al model, are the use of a larger set of truncation factors and t he inclusion of additional terms

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Tratamento de Imagens para ampliação Sem Perda de Localização de Pontos de Referência

João Cândido Lima Dovicchi, Wemerson Delcio Parreira

DOI: 10.14209/sbrt.2015.46

Keywords: Image magnification georeferencing Multi-Scale Resolution image upsampling.

Abstract

The use of high-definition images has, as a rule, high cost while the use of lower resolution images and more affordable cost requires magnification. This paper presents a methodology that involves some math- ematical tools applied to the processing of images, with the objective of enlarging them to avoid the displacement or the deformation of the points on a geo-referenced area in the ori ginal image. In this work, we intend to study multivariate interpo lation, combining the Fourier Series and the Chebyshev polynomials for filtering. In addition, the combination with color-brig htness- intensity correction algorithms show results that enable t he treatment of the problem.

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Posicionamento de Concentradores para uma Infraestrutura Avançada de Medição Inteligente em Redes Máquina a Máquina

Álisson A. Cardoso, Vinícius da C. M. Borges, Flávio H. T. Vieira, Sérgio G. de Araùjo, Marcelo S. Castro , Gustavo B. de C. Souza, Marcus V. G. Ferreira

DOI: 10.14209/sbrt.2015.49

Keywords: Redes Máquina a Máquina Medição Inteligente Posicionamento de Concentradores

Abstract

As restrições rigorosas de latência, custo e consumo de energia impostas pelo paradigma de comunicação Máquina a Máquina (M2M), requerem soluções que tentem otimizar ao máximo as características das redes sem fio. Um dos cenários de M2M mais empregados atualmente em cidades inteligentes e a Infraestrutura Avançada de Medição Inteligente (IAM) que pretende gerenciar de forma mais inteligente a energia elétrica através de um monitoramento preciso e imediato da rede elétrica das cidades. Neste contexto, o problema de otimização que objetiva minimizar a quantidade de concentradores enquanto mantendo a Qualidade de Serviço em nível aceitável tem um papel fundamental. Existem poucas abordagens que tratam a questão do posicionamento dos concentradores em uma IAM. Por esta razão, este artigo apresenta uma comparação dos algoritmos Kmeans-Dijkstra e Recursivo de posicionamento de concentradores em IAM realizada no Matlab, onde os parâmetros comparados mostram a superioridade do algoritmo Recursivo no posicionamento dos concentradores, onde limitações do algoritmo Kmeans-Dijkstra também são apresentadas

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Caracterizando o uso de canais de comunicação do Controle de Tráfego Aéreo

Denniel S. Z. Rossi, Mauro Fonseca, Anelise Munaretto

DOI: 10.14209/sbrt.2015.48

Keywords: Air Traffic Controller Voice model Distribution probability

Abstract

To Know the usage of the communication circuits used by the Air Traffic Services can aid the development of a statistical network able to carry out the critical applications of these Services. In that way, this work deals with a set of stored communications between Air Traffic Controller and aircrafts to identify the dynamic of the channel’s usage. The results obtained allowed to develop a conservative model of the usage of the channels and to recommend other works related to its dynamics.

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Transformadas do Cosseno sobre Corpos de Característica 2: Construções e Aplicação

Edmar S. da Silva, João Victor da Silva, Juliano B. Lima

DOI: 10.14209/sbrt.2015.51

Keywords: Cosine transform finite fields fast algorithms

Abstract

In this paper, cosine transforms over fields of characteristic 2 (FFCT) are constructed. A fast algorithm for computing a specific FFCT is developed and an application of such transforms in digital image processing is described

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BER Evaluation of OFDM Systems for Short Cyclic Prefix and Doppler Spread in Multipath Rayleigh Channels

Lucas Emerson dos Reis Garcia, Celso de Almeida

DOI: 10.14209/sbrt.2015.52

Keywords: OFDM systems Big Cells Short Cyclic Prefix BER Evaluation Channel Dispersion Linear and Non-linear Interference Doppler Effects

Abstract

The performance in terms of bit error rate for OFDM systems for short cyclic prefix and Doppler spread is obtained. In order to evaluate the effects of the short cyclic prefix and Doppler spread on system performance, expressions for the bit error rate are obtained through mathematical fitting to the results obtained by simulation. We have considered several scenarios with different parameters as bandwidth, number of sub-carriers, channel dispersion time, duration of the cyclic prefix, mobile speed for BPSK modulation. In the scenarios examined in this paper, we have observed linear and nonlinear regions that depend on how much the cyclic prefix is shorter than channel dispersion. We have observed that Doppler spread decreases the performance. This paper is an important tool to evaluate the performance of OFDM systems with short cyclic prefix that can occur in big cells and Doppler spread.

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Microstrip Antenna with Extended Ground Plane for Meteorological Nano-Satellites

Juner M. Vieira, Marcelo P. Magalhães, Marcos V. T. Heckler, João C. M. Mota, Antonio S. B. Sombra

DOI: 10.14209/sbrt.2015.47

Keywords: Microstrip antenna Antenna array Meteorologi- cal Nano-Satellite Circular polarization

Abstract

This paper presents the study of a microstrip antenna to be installed onto meteorological nano-satellit es. In order to increase the effective ground plane and to optimize the decoupling between the main and the cross polarizations, me tallic strips were attached to the antenna ground plane. The antenn a performance was evaluated using different types and sizes o f metallic strips. An improvement in the front-to-back ratio whilst keeping good axial ratio performance was observed.

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Parametric Image Reconstruction for ECT-like Sensor with Applications in Two-Phase Flow

Hector Lise de Moura, Daniel Rodrigues Pipa, Aluisio do Nascimento Wrasse, Marco Jose Da Silva

DOI: 10.14209/sbrt.2015.53

Keywords: ECT image reconstruction parametric methods alternate minimization two-phase flow stratified flow

Abstract

Electrical Capacitance Tomography (ECT) is a technique developed to estimate phase distribution in pipelines. Most ECT instruments, however, suffer from high peripheral / low central sensitivities. This ill conditioning causes the recon- struction to be unstable, producing low quality images. This paper presents a new method for an ECT inspired sensor that was developed in a previous work of our group. Although the sensor was designed with few electrodes for simplicity, this worsened general sensitivity, restricting the use of classical reconstruction methods. This paper addresses this issue by applying a parametric approach, improving overall quality of the reconstructed image.

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