Esquemas Cooperativos Incrementais para Canais Relay de Múltiplo Acesso

Dimas Irion Alves, Crístian Müller, Renato Machado, Bartolomeu F. Uchôa-Filho

DOI: 10.14209/sbrt.2015.33

Keywords: MARC relay station multiple antennas cooperative communications

Abstract

In this work, a novel cooperative scheme is presented and an optimization is proposed for wireless communications systems with multiple relay channels (MARC ). The scheme aims at making the MARC systems more compatible with the current ones, by rendering its presence transparen t to the source nodes, thus significantly reducing the complexit y of the cooperative network synchronism. The optimization exp loits the context of multiple signal constellations, aiming at in creasing the robustness against transmission errors. A comparison w ith a reference scheme is carried out by computer simulations, and the results reveal that the proposed scheme matches well with cooperative networks with single-antenna relay stati on, presenting a small signal-to-noise ration (SNR) loss but a g ain in transmission rate. On the other hand, the proposed optimiza tion yields an SNR gain.

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Análise da coexistência do LTE com ISDB - TB em 700 MHz

Luiz A. R. da Silva Mello, Marta P. C. de Almeida, Danielle M. Okamoto

DOI: 10.14209/sbrt.2015.34

Keywords: Interference measurements interference simulation LTE ISDB - TB Digital TV

Abstract

This paper presents the results of field measurements and computer simulation of the interference from LTE system in the Digital TV in the 700 MHz band. The measurement s campaign results were used to validate the use of SEAMCAT software to simulate this interference problem. The software tool was then used for the characterization of the measurement scenarios aiming the evaluation of the coexistence of these services

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Aproximações para Somas de Envoltórias Nakagami- m e α -μ via Casamento de Assíntotas

José David Vega Sánchez, Victor Gonçalves de Carvalho Feitosa Perim, José Cândido Silveira Santos Filho

DOI: 10.14209/sbrt.2015.36

Keywords: α - μ distribution approximation methods asymp- totic analysis fading channels Nakagami- m distribution sum distributions.

Abstract

In this work, we introduce a new method for approximating the probability density function of sums of positive random variables. In addition, as important application examples in wireless communications, we specialize the new method to sums of Nakagami- m and α - μ envelopes. In the proposed approach, the parameters of the approximate distribution are calibrated by matching its asymptotic behavior to that of the exact sum distribution. As a result, the new method is strikingly accurate at medium to high signal-to-noise ratio, outperforming existing solutions in the literature.

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FPGA Implementation of Farrow Structure for Time Interleaved Analog to Digital Converter Clock Skew Compensation

Andre Mariano, Maicon Bruno Hofmann, Sibilla B. L. França

DOI: 10.14209/sbrt.2015.38

Keywords:

Abstract

In modern wireless communication systems, TIADC arises as a good candidate for applications with high sampling rate and moderate power consumption requirements. However the performance of TIADC is impaired due to clock skew between the various ADCs. Clock skew performance degradation can be mitigated by fractional delay filters. Focusing on the clock skew mitigation this paper presents a fractional delay filter implemented in FPGA, based on Farrow structure. The procedure used for TIADC modeling and implementation of digital filter in FPGA is presented in detail.

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Integration of a Smart Meter with the Brazilian Broadband PLC System

Felipe A. Santos, Luã M. F. Da Silveira, Diogo Fernandes, Leonardo de M. B. A. Dib, Fabrício P. V. De Campos, Moisés V. Ribeiro

DOI: 10.14209/sbrt.2015.39

Keywords: Smart Metering Power Line Communication Electric Power Grids

Abstract

This work outlines the integration of a smart metering device with the novel Brazilian broadband powerline communication (PLC) system, which was recently developed t o fulfill the needs and demands related to smart grid communication and digital divide. With this regards, we discuss the developed hardware for interfacing with the smart metering device as well as the programs designed to collect the data which was transmitted by the smart meter using a PLC modem. A field trial was carried out in a low-income gated community and the attained results show that this integration can effectively fulfill throughput demands related to smart metering.

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Sobre a Modelagem Estocástica do Algoritmo NLMS em Ambientes Não Estacionários para Filtros Adaptativos e Plantas do Sistema com Ordens Diferentes

Marcos Vinicius Matsuo, Rui Seara

DOI: 10.14209/sbrt.2015.35

Keywords: NLMS algorithm adaptive filtering stochastic modeling

Abstract

This paper presents a stochastic model describing the behavior of the normaliz ed least-mean-square (NLMS) algorithm in a context for estimating time-varying systems. In particular, the proposed model is valid for white input data with Gaussian distribution and take into account scenarios in which the order of the adaptive filter is different from that of the system to be identified. Specifically, model expressions are derived describing the mean weight behavior, the mean-square error (MSE), and the optimum step size that minimizes the steady-state MSE. Simulation results confirm the accuracy of the proposed stochastic model

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Design for Multi-Vehicle Roadside Tracking Based on Radio Tomographic Imaging

Jarmo Theodore Wilkens, Anilton Salles Garcia

DOI: 10.14209/sbrt.2015.41

Keywords: Radio Tomographic Imaging Wireless Sensor Net- works Vehicle Traffic Surveillance Received Signal Strength

Abstract

With the increasing amount of vehicles on the road, traffic jams pose a growing global problem. Traffic surveillance is a crucial step into improving traffic flow. This paper proposes a design and methodology for the estimation of occupancy and velocity of multiple vehicles on a single lane road segment using Radio Tomographic Imaging (RTI). RTI is an emerging technol- ogy that produces images of the change in the electromagnetic field of a monitored area, making it possible to track device- free objects such as humans and cars. The proposal is based on the analysis of three works discussed in this paper, together with a newly introduced vehicle detection method. To the best of our knowledge, this paper is the first to propose the surveillance of multiple vehicles simultaneously using RTI sub-networks. We also propose a novel car detection and speed estimation method. The contribution of this paper is to stimulate research of the possibility of using RTI networks as being part of an Intelligent Transport System (ITS).

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Análise do Uso de Bloqueadores em Sistemas Power Line Communication

Darlene Engelender, Mateus L. Filomeno, Felipe A. Santos, Thiago R. Oliveira, Moises V. Ribeiro, Eduardo P. de Aguiar

DOI: 10.14209/sbrt.2015.42

Keywords: Power Line Communication Equipments Attenuation

Abstract

This paper presents an analysis of signal blockers that minimize the interference between power line communication systems which operate on the same frequency in external and internal low voltage power grids.

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Um Novo Modelo com Memória baseado em Aproximações Polinomiais Bidimensionais para Transmissores de Sistemas de Comunicações sem Fio

Elton John Bonfim, Eduardo Gonçalves de Lima

DOI: 10.14209/sbrt.2015.43

Keywords: Modeling nonlinear systems with memory p ower amplifier radio frequency wireless communication systems

Abstract

This article proposes a nonlinear model with memory, based on bi-dimensional polynomial approxim ations, for the behavioral modeling of wireless transmitter s. Using experimental data measured on a GaN-based class AB transmitter, the accuracies of the proposed model a nd the generalized memory polynomial (GMP) are compared. T he GMP is a particular instance of the proposed model, onc e the GMP includes only a subset of the contributions present at the proposed model. In a scenario where the polynomial order and memory length truncations are identical, it is obse rved that the proposed model reduces the normalized mean square e rror by up to 1.8 dB

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Representação de imagens em espaço suporte hiperbólico

Laís Bássame Rodrigues, Edson Agustini, Sueli I. R. Costa

DOI: 10.14209/sbrt.2015.24

Keywords: Hyperbolic geometry support space of pixels mathematical morphology Fisher distance.

Abstract

This is a conceptual approach of a work where we propose a support space of pixels to circular images from spherical surfaces using hyperbolic spaces. We work with three projections of this space on a hemisphere of a sphere and an image model that treat grey tones as Gaussian distribution considered in the Poincare half-plane H 2 with the Fisher metric. Through a partial ordering in H 2 we propose an opening morphological operation.

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