Estimativa de Banda Efetiva para Tráfego de Rede Multifractal

Jeferson Wilian de Godoy Stênico, Lee Luan Ling

DOI: 10.14209/sbrt.2013.189

Keywords: Multifractal Traffic Global Scaling Parameter Effective Bandwidth.

Abstract

Multifractal Traffic, Global Scaling Parameter, Effective Bandwidth.

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Dynamic Bandwidth Allocation Mechanism Based on Loss Probability

Jeferson Wilian de Godoy Stênico, Lee Luan Ling

DOI: 10.14209/sbrt.2013.190

Keywords: Loss Probability Admission Control Dynamic Bandwidth Allocation

Abstract

In this paper, we propose an analytical expression for estimating byte loss probability at a single server queue with multifractal traffic arrivals. The obtained expression is robust, stable and accurate in comparison with some existing methods in literature. Next we evaluate the potentiality of applying the proposed method in connection admission control by comparing with some other widely used admission control approaches. Finally we present a dynamic bandwidth allocation mechanism based on our multifractal based loss probability estimation method. Extensive experimental tests validate the efficiency and accuracy of the proposed loss probability estimation approach, its superior performance for admission control and link resource allocation applications with respect to some well-known approaches suggested in the literature.

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Plataforma Matlab/FPGA com Otimização de Desempenho para Simulação de Sistemas MIMO

Matias A. Bortoluzzi, Renato Machado

DOI: 10.14209/sbrt.2013.191

Keywords: FPGA Matlab MIMO quantization simulator

Abstract

In this paper, we present a Matlab/FPGA platform with performance optimization for multiple-input multipleoutput (MIMO) systems simulation. This simulator combines the flexibility of high-level Matlab language with the FieldProgrammable Gate Array (FPGA) power processing. The variables involved in the simulation are generated in Matlab and sent to the FPGA RAM memories where they are used to quick analyze the bit error rate (BER) × SNR performance. These floating point quantities handled by Matlab are quantized to fixed point representation, suitable for processing on FPGA. An analysis of the performance loss in floating point quantization is performed in order to obtain the optimal size of the RAM memories depending on the BER requirements. Finally, we use the proposed plataform to a case study on a single-input singleoutput (SISO) which is a reference of MIMO techniques.

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Compressão de Dados em Redes de Sensores sem Fio Usando Codificação de Huffman

Marcos Costa Maciel, Henry Ponti Medeiros, Richard Demo Souza, Marcelo Eduardo Pellenz

DOI: 10.14209/sbrt.2013.196

Keywords: Wireless Sensor Networks Data Compression

Abstract

This work presents a lightweight data compression method for wireless sensor networks. Instead of attempting to devise novel ad-hoc mechanisms to solve the problem, we attempt to show that, given previous general knowledge of the parameters that must be monitored, it is possible to efficiently employ conventional Huffman coding to represent the same phenomenon when measured at a different location and time period. The statistics of the parameter which must be monitored can be inferred, for example, from public datasets. The Huffman dictionary computed using those statistics is shown to approach the entropy of the data difference. Experimental results with temperature datasets show that the proposed method outperforms one of the most popular compression mechanisms for sensor networks.

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Implementação em FPGA de algoritmos de sincronismo temporal para OFDM

Diego Barragán Guerrero, Luís Geraldo P. Meloni

DOI: 10.14209/sbrt.2013.201

Keywords: OFDM detecção do pacote sincronismo de tempo VHDL FPGA

Abstract

A técnica OFDM tem sido empregada em muitos esquemas de modulação da atualidade. No entanto, esta técnica é bastante sensível a erros de sincronismo de tempo e frequência. Neste trabalho, apresenta-se a implementação, verificação e síntese em hardware digital de vários algoritmos de sincronismo temporal e de detecção do pacote usando símbolos do preâmbulo definidos no padrão IEEE 802.11a. É feita uma análise da implementação em termos de consumo de recursos, frequência de operação e variância de detecção. As arquiteturas propostas foram projetadas empregando-se VHDL na parte de implementação e sintetizadas em uma FPGA Xilinx Spartan 3E no ambiente de desenvolvimento ISE e ISim em modo de linha de comando. Os resultados obtidos constituem um instrumento importante na escolha de implementação de algoritmos de sincronismo em FPGA.

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Reconhecimento de Voz Contínua com Atributos PNCC e Métodos de Robustez WD e MAP

Christian Dayan Arcos, Marco Antonio Grivet, Abraham Alcaim

DOI: 10.14209/sbrt.2013.210

Keywords: Signal degradation enhancement compensation attributes

Abstract

The degradation of the speech signal due to adverse conditions generates low accuracy rates in speech recognition systems. The authors propose mixing two methods: pre-extraction of attributes for speech enhancement and post-extraction of attributes for features compensation. According to their main focus, they are fundamentally oriented to minimize the misfit caused by noise insertion in the speech signal. These methods will be applied before and after the extraction of attributes, respectively, therefore allowing the best possible estimation of the clear signal from its degraded version.

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Simulação da Transformada Quântica de Fourier

Francisco R. F. Pereira, Elloá B. Guedes, Francisco M. de Assis

DOI: 10.14209/sbrt.2013.211

Keywords: Quantum Fourier Transform Simulation Quantum Algorithms

Abstract

The quantum Fourier Transform is an important algorithm in Quantum Information Theory due to its capabilities to solve some Quantum Computation and Communication problems. However, so far, no practical quantum computer has been build neither its simulation is efficient on classical computers. Given these difficulties, this paper presents a software able to simulate the quantum Fourier transform – called FTSimulator – and also an analysis of its time performance

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Escalonamento Baseado em Algoritmos Genéticos para Roteadores de Alto Desempenho

José Ricardo Hoffmann, Emilio Carlos Gomes Wille

DOI: 10.14209/sbrt.2013.202

Keywords: Router Input-Queued switches Scheduling algorithms Genetic Algorithms

Abstract

Modern routers employ input-queued crossbar switches that require sophisticated scheduling techniques for packet transmission. The performance of the router then directly depends on the scheduling algorithm, considering its throughput and complexity. In this paper, a new genetic-based scheduling algorithm is developed and tested for high-performance Internet router operation. The proposed algorithm, called GENIUS, presents low complexity and the results show a performance close to the optimal

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Análise da Propagação ao em Redes de Sensores Sem Fio Aplicadas à Agricultura Irrigada

Eziom Alves de Oliveira, Fabrício Braga Soares de Carvalho, Brauliro Gonçalves Leal

DOI: 10.14209/sbrt.2013.212

Keywords: Wireless Sensor Networks RSSI Performance Analysis ZigBee

Abstract

This article analyzes propagation characteristics of a wireless sensor network applied to precision agriculture. The evaluation performance of the networks is obtained through the RSSI (Received Signal Strength Indication), in a grape plantation. Experimental results showed that the distance between the sensor modules and the vegetation density affect directly the quality of the transmitted signal

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Codificação de Rede Aplicada a Rede Cooperativa com Múltiplo Acesso Simultâneo

João Luiz Rebelatto, Bartolomeu F. Uchôa-Filho

DOI: 10.14209/sbrt.2013.213

Keywords: Network coding cooperation multiple access channel

Abstract

In this work, we elaborate on the recently proposed generalized dynamic network coding (GDNC), relaxing the orthogonal constraint during the cooperative phase. By allowing the parity packets to be transmitted simultaneously, we show that it is possible to decrease the system outage probability (increase the diversity order) and/or increase the network code rate, without harming the system performance. The outage probability is obtained analytically, and confirmed by numerical results.

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