Probabilidade de Erro de Bit em Sistemas de Comunicação Digital na Presença de Ruı́do Impulsivo Gaussiano Gatilhado

Évio da Rocha Araújo, Wamberto José de Lira Queiroz, Marcelo Sampaio de Alencar

DOI: 10.14209/sbrt.2012.90

Keywords: Impulsive noise GAWGN G 2 AWGN error pro- bability BPSK QPSK MPAM MPSK MQAM R-MQAM

Abstract

This article presents a mathematical analysis of some models for the AWGN impulsive noise. The two main classes are the gated AWGN (GAWGN) and the gated gated AWGN (G 2 AWGN), and it is also assessed their influence on some systems of digital modulation. This assessment is made by the average probability of error bit and the equations are obtained from the average probability of bit error for digital communication systems BFSK, BPSK, QPSK, MPAM, MPSK, MQAM and R-MQAM.

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Estimação Empírica da Distribuição da Estatística de Teste para o Sensoriamento Espectral por Máximo Autovalor sob a Hipótese H 1

João S. Neto, Dayan A. Guimarães, Rausley A. A. de Souza

DOI: 10.14209/sbrt.2012.91

Keywords: Cognitive radio eigenvalue-based sensing maximum eigenvalue detection

Abstract

In this paper it is showed that the Log-Pearson 3P is a good approximation of the probability density function of the maximum eigenvalue detection (MED) test statistic for cooperative spectrum sensing in cognitive radio applications, under the hypothesis that the primary transmitted signal is present. This result complements those already available in the literature, which consider the hypothesis that the transmitted signal is not present. Jointly, these results are useful for the design and performance assessment of the MED technique in terms of the false alarm and detection probabilities.

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EFEITO DA INICIALIZAÇÃO NO MODELO DO COMPORTAMENTO DOS COEFICIENTES DO ALGORITMO DE PROJEÇÕES AFINS

Márcio H. Costa, Sérgio J. M. de Almeida, José C. M. Bermudez, Rodrigo B. Barcelos

DOI: 10.14209/sbrt.2012.92

Keywords: Adaptive filter Affine Analytical model Mean weight behavior

Abstract

This paper presents a new analytical model for the mean weight behavior of the Affine Projection adaptive algorithm for autoregressive inputs and unity step-size. Deterministic recursive equations are derived considering an initial transient previously not accounted for. This phase occurs at the beginning of the adaptation process, and is due to the arbitrary initialization of the coefficients. It is a deterministic process that prevents the correct orthogonalization of the coefficient vector with respect to the subspace defined by the past input vectors. Monte Carlo simulations show improvements in the accuracy of the presented model when compared to a previously one.

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Sensoriamento Espectral Cooperativo Baseado em Autovalores para Sinais de Banda Larga

Carlos R. N. da Silva, Dayan A. Guimarães, Rausley A. A. de Souza

DOI: 10.14209/sbrt.2012.94

Keywords: Cognitive radio Eigenvalue-based cooperative spectrum sensing Energy detection GLRT RLRT OFDMA

Abstract

A new spectrum sensing approach for the spectrum sensing of wideband signals in cognitive radio (CR) systems is proposed. Eigenvalue detection techniques are combined with two data fusion schemes, where i) the samples collected by each CR are combined at the fusion center (FC) and ii) the eigenvalues of received covariance matrices in each CR are combined at the FC. Simulation results unveil that the eigenvalue combining strategy suggested in this paper can overcome the performance attained with samples combining, also reducing the data traffic in the reporting control channel.

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Transformada Wavelet Aplicada ao Tratamento de Sinais de Descargas Parciais

Oeslle A. S. Lucena, Euler C. T. Macêdo, Waslon T. A. Lopes, Edson G. Costa

DOI: 10.14209/sbrt.2012.95

Keywords: Descargas parciais Transformada Wavelet De-noising

Abstract

As descargas parciais (DP) levam a degradação do isolamento de equipamentos de alta tensão. Logo, a identificação dos padrões de ocorrência destes sinais se torna útil na avaliação da vida útil dos equipamentos. A Transformada Wavelet é uma poderosa técnica que pode ser usada na rejeição/atenuação dos ruídos presentes nos sinais de DP. Este artigo apresenta resultados da aplicação da Transformada Wavelet para rejeição/atenuação de ruídos (de-noising) em sinais de descargas parciais.

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Avaliação da Transferência de Fluxos Multimídia em uma Rede em Malha Sem Fio

Dalbert Matos Mas arenhas, Felipe da Ro ha Henriques, Glau o Fiorott Amorim, Luis Carlos dos Santos Coutinho Retondaro

DOI: 10.14209/sbrt.2012.93

Keywords: Appli ation lo ation mesh network

Abstract

In this work, we evaluate the transfer of multimedia ows in a wireless mesh network. For this aim, an appli ation is used, and based on the IP address of a lient devi e, one an identify the subnet where it is inserted, and spe i ows are transmitted to it, based on the lo ation of this AP. In order to evaluate the network used, UDP and TCP ows are transmitted and metri s su h as the per entual pa kets loss, the throughput and the jitter are onsidered.

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A Bidirectional Processing Receiver for Layered

D.C. Araújo, W. C. Freitas Jr., A. L. F. de Almeida

DOI: 10.14209/sbrt.2012.96

Keywords: MIMO systems bidirectional processing successive interference cancelation space-time multiplexing

Abstract

In this paper, we present a new receiver structure for layered space-time multiple-input multiple-output (MIMO) systems based on non-linear interference cancelation. The main idea of the proposed receiver is to use a bidirectional processing approach, where spatial filtering and interference subtraction start simultaneously at the first and last layers and proceed successively towards the central layer in a parallelized manner. The proposed bidirectional processing receiver has two main advantages compared to traditional successive interference cancelation (SIC) detectors: i) the processing delay can be reduced by a factor of two at the expense of a parallel processing unit and ii) the bit-error-rate performance can be considerably improved due to the increased diversity gain obtained across the detection layers. Moreover, our bidirectional processing receiver exhibits the same performance as the recently proposed backward recursion based receiver [6] at a reduced processing time. Simulation results are provided to confirm the merits of the proposed receiver in terms of uncoded bit-error-rate.

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Comparação entre Esquemas de Detecção Distribuída e Mensagens Quantizadas

Rodrigo Pereira David, Raimundo Sampaio Neto, César A. Medina

DOI: 10.14209/sbrt.2012.97

Keywords: Distributed Detection Quantization Wireless Sensor Networks

Abstract

The distributed detection problem in wireless sensor networks using versions of been the subject of many studies over the last decade. This paper presents a performance comparison of two strategies for distributed detection which were results of these surveys. The first one uses identical sensors and majority rule in the fusion center and the second one is named universal distributed detection which operates without knowledge of the probability distribution of the observations of the sensors. The comparison is made with observations disturbed by Gaussian noise and the channel with no distortion between the sensors and fusion center. Subsequently, the comparison is made using non-ideal channel between the sensors and fusion center.The results obtained via simulation proved the superiority of the scheme using majority rule for both ideal and non-ideal channels between the sensors and fusion center.

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Otimização de rede de sensores sem fio através de algoritmo de codificação de rede

Jéssica Bartholdy Sanson, Natanael Rodrigues Gomes, Renato Machado, Andrei Legg, Dimas Irion Alves

DOI: 10.14209/sbrt.2012.98

Keywords: Network Coding Wireless Sensor Network Data Transmission

Abstract

A wireless sensor network is a kind of ad hoc network that can be used to monitor a variety of environmental characteristics in various fields with, for instance, military purposes, environmental purposes, etc. A typical problem of these networks is how to collect and send historical information from all network sensor nodes to the base station. In this work are compared two techniques using network coding to reduce the total number of transmissions in sensor networks and the transmission time, resulting in a more efficient network. Two network coding configurations are implemented and the results are compared to those of a network that uses a simple broadcast transmission.

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Algoritmo Adaptativo DCLMS Modificado Aplicado em Sistemas de Comunicações Móveis

Ciro André Pitz, Rui Seara

DOI: 10.14209/sbrt.2012.99

Keywords: Constrained adaptive algorithms antenna array beamforming with power control mobile communication systems

Abstract

This paper presents a modified version of the duality constrained least-mean-square (DCLMS) algorithm, which performs both beamforming and power control in mobile communication systems. In the original DCLMS algorithm, the transmission power update occurs only after the convergence of the beamforming process, implying successive convergence tests and loss of performance in non-stationary environment. Aiming to obtain a more robust algorithm, a modification in the transmission power update process is proposed, giving rise to a new algorithm, termed here modified DCLMS (M-DCLMS) algorithm. The effectiveness of the proposed algorithm is verified through the simulation results.

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