A ew Multifractal Traffic Model and Its Impacts on Buffer Queueing Performances

Jeferson Wilian de Godoy Stênico, Lee Luan Ling

DOI: 10.14209/sbrt.2010.14

Keywords: Multiscale Traffic Modeling Loss Probability Network Traffic

Abstract

In this paper, we propose a new analytical expression for estimating byte loss probability at a single server queue with multi-scale traffic arrivals using Pareto distribution. In order to make the estimation procedure numerically tractable without losing the accuracy, we assume and demonstrate that an exponential model is adequate for representing the relation between mean square and variance of Pareto distributed traffic processes under different time scale aggregation. Extensive experimental tests validate the efficiency and accuracy of the proposed loss probability estimation approach and its superior performance for applications in network connection with respect to some wellknown approaches suggested in the literature

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A Robust MERRY Channel Shortening Technique for OFDM Systems in PLC Environment Corrupted by Impulsive Noise

Alam Silva Menezes, Moisés Vidal Ribeiro

DOI: 10.14209/sbrt.2010.15

Keywords:

Abstract

This contribution introduces a robust version of the multicarrier equalization by restoration of redundance (MERY) algorithm for data communication through power line communication (PLC) channel corrupted by impulsive noise. The novelty is the introduction of a nonlinear and differentiable function into the cost function of MERRY algorithm. As a result, the proposed and named robust (R)-MERRY algorithm is less sensitive to the presence and hardness of impulsive noise. Simulation results reveal that bit error rate (BER) performance improvements can be attained in PLC scenarios

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Modulations for Large Signal Constellations Coming from Embedding of Complete Graph

João de Deus Lima, Luana Priscilla R. C. de Lima, Wilken Charles Dantas de Melo

DOI: 10.14209/sbrt.2010.16

Keywords:

Abstract

The integrated system of data transmission, encoding, modulation and block channels are projected in dependent ways with the purpose of getting an integrated action from those elements, and the elimination of additional devices with incompatibility treatment, caused by inadequate choice of some those components. In this system, the modulation and encoding projects take place in topological spaces (Ω; d), where Ω is Riemannian manifolds and d is a metric on Ω, which the discrete memoryless channel Cm, like a graph, is embedded. For each embedding Cm ,! Ω, it’s possible to determine accurately a topological modulation project on Ω, in the sense of knowing the decision regions (or Voronoi’s regions) of each constellation signal. The paper’s purpose is to identify topological projects of modulation on surfaces for large constellations, mainly the regular modulations. The procedures to obtain these projects are based on the method of the current graph developed by Gustin and Youngs and used in the proof of Color Graph Conjecture by Heawood.

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Synchronization of Legacy 802.11a/g Devices Operating in IEEE 802.11n Networks

Roger Pierre Fabris Hoefel, André Michielin Câmara

DOI: 10.14209/sbrt.2010.17

Keywords: 802.11n 802.11a/g synchronization

Abstract

It is investigated the performance of legacy IEEE 802.11a time synchronization algorithms when the synchronization preamble is transmitted by IEEE 802.11n devices with multiple transmitting antennas using cyclic shift diversity. It is concluded that the backward compatibility is achieved when the time synchronization is implemented using an auto-correlation maximum normalization metric.

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A Packet Distribution Traffic Model for Computer Networks

Ewerton Castro, Ajey Kumar, Marcelo S. Alencar, Iguatemi E. Fonseca

DOI: 10.14209/sbrt.2010.18

Keywords: Self-similar Computer Network Internet Traffic File Size Distribution

Abstract

The traditional traffic models which are based on conventional telephone traffic are not suitable for modeling selfsimilar traffic on computer networks. Therefore, emphasis has been put on self-similarity characteristics. This paper presents a model which can be used to compare, simulate and estimate the packet traffic distribution on computer networks.

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COLOR IMAGE QUALITY EVALUATION USING GRAYSCALE METRICS IN CIELAB COLOR SPACE

Renata Caminha C. Souza, Lisandro Lovisolo

DOI: 10.14209/sbrt.2010.102

Keywords: Image quality evaluation Color images Full-Reference metrics SSIM VIF Just Noticeable Difference CIELAB

Abstract

In many image applications the measurement of visual quality is of special importance. Most of the Full-Reference metrics proposed address the evaluation of grayscale images. This paper investigates an application of two grayscale metrics for the evaluation of color images using CIELAB color space. It also proposes the utilization of an important feature of this space, the possibility to measure the distance between colors, to improve the performance of the metric, i.e. affording a higher correlation between the objective metric and the subjective measurement. The results indicate that the use of color distance with a FR image quality evaluation metric improves its correlation with the subjective scores.

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Nanophotonics in Modern Communication Systems – Feasibility of Plasmon-Polariton Waveguides in Optical Networks

Anderson O. Silva, Jorge A. Macedo, Victor Dmitriev, André Lages

DOI: 10.14209/sbrt.2010.19

Keywords: Nanophotonics surface-plasmon-polaritons subwavelength waveguiding structures

Abstract

Use of surface-plasmons-polaritons has become a potential way to develop optical components below the diffraction limit. This paper reports the feasibility of some plasmonpolariton waveguides in optical communication systems. Combinations of metal elements of different geometry are theoretically analyzed. They can serve as building blocks in future nanophotonic systems. The spectral responses of these structures show they can be used as frequency selective components in optical communication windows for wavelength division multiplex applications.

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On Indoor Coverage Models for Industrial Facilities

Cassio Bento Andrade, Roger Pierre Fabris Hoefel

DOI: 10.14209/sbrt.2010.20

Keywords: industrial WLANs 802.11 coverage

Abstract

It is shown analytical and measurement results in order to compare five different indoor path loss propagation models in industrial environments: one-slope; dual-slope; partitioned; Cost-231 multi-wall model and average walls. It is concluded that the dual slope propagation model allows a better estimation among the selected models because the propagation loss rate increases abruptly beyond a certain distance from the transmitter in large industrial environments.

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Ambient Noise Classification for Automatic Speaker Identification

R. Santana, L. Zão, R. Coelho

DOI: 10.14209/sbrt.2010.98

Keywords: Automatic Speaker Recognition ambient noises noises classification

Abstract

This paper proposes two methods for acoustic ambient noises classification. The classification is based on the Kurtosis coefficient and the Bhattacharyya distance. Five colored acoustic noises, some captured in different environments and a White artificially generated, were used to perform the classification methods. These noises were obtained from NOISEX-92 database. Automatic speaker identification experiments were conducted using TIMIT speech database, corrupted with the acoustic noises. Mismatch conditions (SNR of 10 dB, 15 dB and 20 dB) were also examined in the experiments. The performances presented considerable variations among the different acoustic noises. The results show that the noise classification obtained with the proposed methods could detect the differences in the speaker identification accuracies. The MFCC (Mel-Frequency Cepstrum Coefficients) and GMM (Gaussian Mixture Models) were applied for the identification experiments.

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Prediction-Based Coding of Speech Signals Using Multiscale Recurrent Patterns

Frederico S. Pinagé, Murilo B. de Carvalho, Eduardo A. B. da Silva, Sergio L. Netto

DOI: 10.14209/sbrt.2010.105

Keywords:

Abstract

This paper investigates the performance of the multidimensional multiscale parser (MMP) algorithm for speech coding. A new prediction-based scheme is considered, where the MMP algorithm operates on the associated prediction-error signal instead of the original speech signal. Other features are considered, such as: nonuniform quantization of MMP initial dictionary, use of auxiliary dictionary of recent past samples, and quantization/normalization during the dictionary updating stage. It is verified that the resulting MMP scheme, combining all these techniques, at 8 kbps can achieve perceptual objective scores comparable to the ITU-T G.729 codec.

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