Quality Performance of LD, SD and HD Video Encoded with Dirac and H.264/AVC

Wyllian B. da Silva, Keiko V. O. Fonseca, Alexandre de A. P. Pohl

DOI: 10.14209/sbrt.2010.103

Keywords: Dirac H.264/AVC Digital TV

Abstract

This paper compares the video quality performance of low definition (LD), standard definition (SD) and high definition (HD) video signals encoded with H.264/AVC and Dirac using full-reference (PSNR and SSIM) and no-reference metrics (JPEG-NR) for different bit rates. It is shown that H.264 outperforms Dirac concerning quality for all resolutions.

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Burst-Error Statistics Obtained by ML Estimation of a New Structured Markov Channel Model

M. Vinicius dos Santos, Ernesto L. Pinto, Marco Grivet

DOI: 10.14209/sbrt.2010.76

Keywords: Markov model ML estimation burst simulation

Abstract

A new Markovian model (MM) for burst-error generation has been recently presented by the authors. This model is conveniently structured, with the double purpose of reproducing the generation of some typical patterns of burst error sequences and facilitating the maximum-likelihood (ML) estimation of the its parameters. In the present work we show that this model also turns out to be useful for obtaining simple expressions for several statistics of great interest in the context of modeling and performance evaluation of communications systems degraded by burst-errors. So we propose to use these analytical expressions fulfilled with ML estimates of the model parameters in order to obtain good models for the above mentioned statistics. Some numerical results are presented that illustrate the effectiveness of this approach.

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Self-similar QoS Manager: a bio-inspired approach

Alessandro Vivas, Luciana Assis, Luciano de Errico

DOI: 10.14209/sbrt.2010.120

Keywords: QoS MPLS path allocation problem traffic engineering self-similar traffic bio-inspired optimization

Abstract

This work presents a Self-similar QoS Manager using a immunological algorithm to optimize a MPLS network. The system receives a set of requirements, imposed by many different client applications, and creates a set of paths that satisfy all the capacity constraints necessary for each specific traffic. The solution also keeps the load balance in the network and considers the self-similar characteristics of the traffic, which lead to improved results. The ns2 (network simulator 2), working with real traffic traces injected in source nodes, was used to validate the approach. Results showed that all simultaneous client application requirements were satisfied, while optimizing the traffic allocation in the MPLS network. The paper also analyzes the influence of different bio-inspired algorithms (genetic and immunological) in the solution of the MPLS path allocation problem.

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SIMTON: A Simulator for Transparent Optical Networks

Daniel A. R. Chaves, Joaquim F. Martins-Filho, Helder A. Pereira, Carmelo J. A. Bastos-Filho

DOI: 10.14209/sbrt.2010.77

Keywords:

Abstract

In this article we present a software to simulate Transparent Optical Networks (SIMTON). SIMTON is an eventdriven simulation software implemented in C++ which takes into account optical device characteristics for the evaluation of network blocking probability in wavelength routed transparent optical networks. The simulator uses a physical layer model that considers the following effects: device losses, fiber attenuation, four wave mixing, residual chromatic dispersion and polarization mode dispersion in optical fibers, gain saturation in optical amplifiers (Erbium Doped Fiber Amplifier), dependence of the amplified spontaneous emission noise with the input power in EDFA, in-band crosstalk in optical switches, and source spontaneous emission noise of the laser transmitter. By using SIMTON it is possible to adjust the parameters of the optical devices, as well as to choose the routing and wavelength assignment algorithm. Moreover, the tool has a graphical interface. We also present some examples of network analysis results obtained from SIMTON.

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Analysis of DOP in the Presence of PMD and PDL for RZ/RZ-DPSK Signals in High-Rate Optical Transmission Link

Raymundo Nogueira de Sá Netto, Fátima Regina Caldeira Barroso, João Batista Rosa Silva

DOI: 10.14209/sbrt.2010.78

Keywords: DOP DPSK PDL PMD

Abstract

This work analyzed numerically the relationship between DOP, PMD and PDL dispersion effects in high-rate optical communication systems for differential phase-shiftkeying modulation. It was considered 10 Gb/s and 20 Gb/s transmission rates for RZ-DPSK and RZ-DPSK (duty cycle 50% and 33%) signals.

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Application of Security Metrics in a Metropolitan Network : A Case Study

Rodrigo Sanches Miani, Bruno Bogaz Zarpelão, Leonardo de Souza Mendes

DOI: 10.14209/sbrt.2010.79

Keywords: Communication systems Computer network management Computer network security Security metrics Open access metropolitan area network

Abstract

The information security issues in the current communication networks demand the development of efficient methods to find security vulnerabilities and facilitate the decision making process. Security metric is a widely used concept in this area. The metrics can indicate the actual level of a specific security target and may determine the actions that should be taken. This work presents a case study about the security metrics implementation in the Open Access MAN (Metropolitan Area Network) of Pedreira, a city located on southeast of Brazil. The paper also presents a methodology for data gathering and analysis to support the security metrics implementation, the security metrics that were used in the case study, the metrics program results and some discussions about the benefits and disadvantages of the security metrics usage.

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On Super-Resolution versus Image Interpolation

Guilherme H. Costa, Jose C. M. Bermudez

DOI: 10.14209/sbrt.2010.82

Keywords:

Abstract

This work presents a discussion about multi-frame Super-Resolution Reconstruction (SRR) and single-frame interpolation. SRR has been extensively studied in the last decades but it is not yet as popular as image interpolation. Since both methods are directed to improve image quality, comparisons are inevitable and desirable. However, fundamental misunderstandings can still be found in the literature on the choice between these two approaches. Recently, some mistaken conclusions have been reached regarding the SRR performance. This paper clarifies important SRR issues in image reconstruction, in contrast to interpolation. For reasons further discussed, two algorithms are considered: bicubic interpolation and LMS-SRR.

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A Reinforcement Learning Based Joint Call Admission Control for Heterogeneous Wireless Networks

Rennan J. M. Silva, João C. W. A. Costa, Gláucio H. S. Carvalho

DOI: 10.14209/sbrt.2010.83

Keywords: Joint call admission control JCAC resource allocation reinforcement learning heterogeneous networks

Abstract

Currently, there are many wireless networks based on different radio access technologies (RATs). Despite this, new kind of networks will be developed to complement those already existing today. As there will be no RAT able to give users full service requirements with universal coverage, the next generation wireless networks will integrate multiple technologies, working jointly on a heterogeneous way. Heterogeneous networks necessitate joint radio resource management (JRRM) mechanism to enhance better resource utilization and give users better quality of service. Joint call admission controls (JCAC) are a kind of JRRM mechanisms. In this paper, we present a JCAC approach to heterogeneous wireless network management based on reinforcement learning to treat call admission and technology selection, enhancing the network’s performance. The effectiveness of this approach is assessed in terms of blocking rate results obtained by two simulation scenarios.

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Capacity Issues for Cognitive Radio Systems

Heloisa P. B. Pimentel, Paulo Cardieri

DOI: 10.14209/sbrt.2010.121

Keywords: cognitive radio capacity interference wireless communication multiple user spectrum sharing

Abstract

The development of software radio toward the cognitive radio brought the hope that the spectrum scarcity would be finally an issue of the past. Due to the characteristics of the cognitive operation and environment (including spectrum sharing), the operation of such a system has to take into account the interference to and from other wireless systems. Interference exploited via cognition could also improve spectral utilization and end-to-end performance, and the interference channel model could provide a good choice when evaluating these systems. However, the determination of the capacity region for the interference channel has been an open problem for more than 30 years, showing that the fundamental questions about networks and interference is not well understood until now. In spite of that, some researchers have already presented capacity analysis for cognitive radio systems under certain conditions.

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An Open Source HMM-based Text-to-Speech System for Brazilian Portuguese

Igor Couto, Aldebaro Klautau, Ranniery Maia, Nelson Neto, Vincent Tadaiesky

DOI: 10.14209/sbrt.2010.84

Keywords: Text-to-speech systems HMM-based speech synthesis text analysis

Abstract

Text-to-speech (TTS) is currently a mature technology that is used in many applications. Some modules of a TTS depend on the language and, while there are many public resources for English, the resources for some underrepresented languages are still limited. This work describes the development of a complete TTS system for Brazilian Portuguese which expands the already available resources. The system uses the MARY framework and is based on the hidden Markov model (HMM) speech synthesis approach. Some of the contributions of this work consist in implementing syllabification, determination of stressed syllable and grapheme-tophoneme (G2P) conversion. This work also describes the steps for organizing the developed resources and implementing a Brazilian Portuguese voice within the MARY. These resources are made available and facilitate the research in text analysis and HMM-based synthesis for Brazilian Portuguese.

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