PARAFAC Receiver for Uplink Cooperative Relay-Assisted DS-CDMA Systems

André L. F. de Almeida, C. Alexandre R. Fernandes, Daniel Benevides da Costa

DOI: 10.14209/sbrt.2012.126

Keywords: Cooperative diversity multiuser communications DS-CDMA PARAFAC blind receiver

Abstract

In this paper, we consider the uplink of a multiuser cooperative DS-CDMA communication system, where each user communicates with the base station with the help of R relays. A cooperative DS-CDMA configuration with direct-sequence spreading at the relays is proposed and for this cooperative scenario we formulate a new trilinear model for the received signal that combines source-destination (SD) and relay-destination (RD) wireless links. Based on this trilinear model, we propose a blind receiver for the joint estimation of antenna array responses, channel gains and transmitted symbols of all the users. Numerical results are provided to illustrate the performance of the proposed blind receiver. Our results also corroborate the benefits of exploiting spreading diversity for blind multiuser detection in the considered cooperative relay-assisted DS-CDMA scenario

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Análise de uma rede Smart Grid usando a norma IEC 61850 e dados de medições

Fernando Petenel, Cristiano Panazio

DOI: 10.14209/sbrt.2012.127

Keywords: IEC 61850 Smart Grid GOOSE NS2

Abstract

This article presents an analysis of a Smart Grid network based on IEC 61850 standard and the data obtained through measurements of parameters from equipments used in such network. The main objective is to explore the operational limits of the network, i.e., determine the latency and congestion scenarios that affect the reliability of such network, through different and practical scenarios.

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Controle de Admissão de Chamadas e de Fluxo Fuzzy com Tráfego Multi-Classes para Ambientes de Redes Sem Fio 3G

Ana Gloria M. Chipana, Jeferson Wilian de Godoy Stênico, Lee Luan Ling

DOI: 10.14209/sbrt.2012.128

Keywords: CAC Flow Control Fuzzy Logic Multi-Cclass Traffic

Abstract

CAC, Flow Control, Fuzzy Logic, Multi-Cclass Traffic

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Análise comparativa entre as Transformada Discreta de Fourier e a Transformada Discreta Cosseno na compressão e recuperação espectral de sinais de voz.

Priscila Lima Rocha, Washington Luís Santos Silva, Ginalber Luiz de Oliveira Serra

DOI: 10.14209/sbrt.2012.117

Keywords: Digital processing of signals Composition of signals Discrete transform

Abstract

In this paper is proposed a comparative practice analysis between the Discrete Fourier Transform (DFT) and the Discrete Cosine Transform (DCT) in application of digital processing of speech signals. The analysis is based in to check which of two Transform is more efficient, as regard use of fewer samples of the spectrum for reconstruct a given signal. The experiment results are presented in form of graphs. It was used for the simulation and obtain of the results, example of speech signal of spoken words and digits with added of white noise.

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Strong Self-Phase Modulation in Data Erasing Beyond 20 Gb/s Using Saturated Ultra-Long SOA

Napoleão S. Ribeiro, Cristiano M. Gallep, Evandro Conforti

DOI: 10.14209/sbrt.2012.4

Keywords: Optical Carrier reuse Optical Data Processing Semiconductor Optical Amplifier

Abstract

Optical data extinction using ultra-long SOA is evaluated up to 56 Gb/s. The analysis of the deleterious effects such as spectral broadening and imperfect erasing predicts useful carrier wavelength reuse up to 20 Gb/s.

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QoS de serviços IPTV baseados em arquiteturas IMS

Marcos Paulo Carozza, Paulo Roberto de Lira Gondim

DOI: 10.14209/sbrt.2012.129

Keywords: QoS IPTV IMS OPNET® Modeler

Abstract

IPTV is a technology that has been developed over the last years and is gaining recognition worldwide as a viable alternative to offer audiovisual contents by telecommunications operators. IMS architecture is a framework developed to deliver IP-based multimedia services and the key to fixed-mobile convergence of next generation networks. This work aims to evaluate possibilities and limitations related to IPTV services based on the integration between IMS architecture and WiMAX wireless broadband access network. To this end, an integration architecture is considered and the OPNET® Modeler simulation tool is used, allowing to evaluate aspects of quality of service (QoS) such as delay, jitter and throughput. The results obtained in our simulations are compared with the Recommendation ITUT Y.1541 of International Telecommunication Union, which addresses the network performance objectives for IP-based services.

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Space-time codes based on quaternion algebras of small volume

Carina Alves, Jean-Claude Belfiore

DOI: 10.14209/sbrt.2012.5

Keywords: Algebraic reduction maximal order cyclic division algebra space-time codes

Abstract

We have seen in [13] a new reduction method for the decoding of 2×2 algebraic space-time codes, called algebraic reduction as been introduced. Algebraic codes such that the volume of the Dirichlet’s polyhedron of its units group is small are better suited for decoding using the method of algebraic reduction. In this paper, we propose a new framework for constructing a space-time code whose algebraic reduction behaves better than the one of the Golden code.

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Desempenho do Algoritmo Paralelo CORDIC em Implementac¸ao em FPGA

Diego Barragán G., Karlo G. Lenzi, Luís G. P. Meloni

DOI: 10.14209/sbrt.2012.20

Keywords: CORDIC digital IC design FPGA Module Phase

Abstract

This article presents a design in digital hardware for transcendental function computation (magnitude and phase of a complex number) using vector coordinates in the CORDIC algorithm in vectoring mode. The code was synthesized for FPGA using Xilinx development tools for the Spartan-3E xc3s500e family. Besides, performance analysis is realized changing algorithm parameters and the number of iterations. The results are at state of art for present practice with 16 word width requiring 16 interactions. These results validate the proposed architecture for the CORDIC algorithm

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Estudo de Entrelaçadores para Códigos Convolucionais Não-Unicamente Decodificáveis no Canal Aditivo com Dois Usuários Binários

Romero de A. Braga, Márcio J. de C. Lima, Maria de Lourdes M.G. Alcoforado, Valdemar C. da Rocha Jr

DOI: 10.14209/sbrt.2012.220

Keywords: Convolutional codes 2-user binary adder channel turbo codes interleavers iterative decoder

Abstract

This paper presents a comparative study among distinct classes of interleavers, applied to non-uniquely decodable convolutional code pairs, over a two-user binary adder channel (2-BAC), in the presence of additive white Gaussian noise. Performance curves are presented with results of computer simulations, when using convolutional encoders for each user in the turbo structure, making use of different types of interleavers. It is observed that for two users a bit error probability around Pb = 10−4 interleavers as DRP, S-random and polynomial presented a gain of approximately 1, 0 dB in signal to noise ratio with respect to the rectangular interleaver of Berrou and Glavieux

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Transporte óptico de sinais WiMAX

Ísis de A. Lima, Raphael T. de Alencar, José Ewerton P. de Farias

DOI: 10.14209/sbrt.2012.130

Keywords: Ísis de A. Lima Raphael T. de Alencar e José Ewerton P. de Farias

Abstract

A short review on the current status of the deployment of optical access networks for several regions is presented. The concept of hybrid (optical-wireless) access networks, focusing on the physical transport of RF signals over optical fibers is introduced. Numerical results obtained through simulations for the physical layer of optical access networks and for RoF links are included and discussed

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