Brincando com Blocos: Uma Nova Combinação da Transmissão em Blocos com a Técnica de Múltiplo Acesso CDMA

Leonel Arévalo, Raimundo Sampaio Neto, César A. Medina

DOI: 10.14209/sbrt.2012.118

Keywords: Block Transmission Single Carrier CDMA Fre- quency Selective Channel Ideal User Decoupling

Abstract

This paper addresses a new possible combination of the single carrier (SC) block transmission and the Code Division Multiple Access (CDMA) techniques. Performance comparisons with the traditional SC CDMA block transmission system are presented. A key feature of the proposed transmission technique is that, differently from what occurs with SC CDMA, the original code orthogonality between users is preserved despite propagation through multipath frequency selective channels, thus ideally allowing the decoupling of the signals at the receiver side. Beyond this advantage, and mostly due to it, the performance results indicate a clear superiority of the proposed system over the traditional SC CDMA. The simulation results consider frequency domain ZF (Zero Forcing) and MMSE (Minimum Mean Squared Error) equalization and assume perfect knowledge of the transmission channels.

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Algoritmo de CAC para Redes IEEE 802.16e Baseado em Reservas de Largura de Banda com Ajuste Dinâmico de Limiares

Sílvio Martins Reis, Paulo Roberto Guardieiro

DOI: 10.14209/sbrt.2012.116

Keywords: CAC dynamic threshold adjustment QoS IEEE 802.16e WiMAX

Abstract

In this paper, we present a Connection Admission Control (CAC) algorithm for the IEEE 802.16e standard, based on dynamic bandwidth reservation. These reserves are obtained by segmenting the amount of the available channel’s bandwidth by thresholds, which are dynamically adjusted according to the admissions of handoff and new connections. Studies based on modeling and simulation have shown that the proposed algorithm can avoid the waste of network resources, increase its efficiency and provide QoS, in terms of bandwidth, for applications.

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Melhoria da técnica de redução da PAPR baseada na transformada de Walsh-Hadamard.

Guilherme Pedro Aquino, Luciano Leonel Mendes, Leonardo Silva Resende

DOI: 10.14209/sbrt.2012.119

Keywords: PAPR reduction OFDM Walsh-Hadamard Transform WHT-OFDM non-linear channel

Abstract

The aim of this paper is to propose a new PAPR reduction technique for OFDM system based on the permutations of the lines of the Walsh Hadamard Transform. This new technique is called SLM-WHT. The PAPR reduction efficiency and the reduction of the symbol error rate in non- linear channels have been evaluated using computational simulation, allowing one to conclude that this approach enables the use of WHT with OFDM in amplitude clipping channel.

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Pathological Voice Classification Based on Recurrence Quantification Measures

Washington C. de A. Costa, F. M. de Assis, B. G. Aguiar Neto, Silvana C. Costa, Vinı́cius J. D. Vieira

DOI: 10.14209/sbrt.2012.120

Keywords: Speech signal analysis laryngeal pathologies re- currence quantification measures

Abstract

This paper presents an analysis of speech signals based on quantification measures of recurrence plots. A com- parison between healthy voices and voices affected by laryngeal pathologies (Reinke’s edema, nodule and vocal fold paralysis) is made. In order to classify these signals as pathological or healthy, seven recurrence quantification measures are used: Determinism, maximum length of the diagonal structures, Shannon entropy of line distribution, slope of line of best fit, laminarity, length of longest vertical line segment and mean vertical line length or trapping time. Discriminant analysis methods (linear and qua- dratic) are applied to each feature individually, and to the vectors formed by feature combination with cross-validation classification rates up to 95.71±4.94% (95% confidence interval). Results show that the employed measures present a significant discriminative potential to distinguish healthy voices from pathological ones.

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Algorithms for Joint Optimization of Link Capacity and Regenerators Placement in Optical Networks

Renan V. B. Carvalho, Carmelo J. A. Bastos-Filho, Daniel A. R. Chaves, Joaquim F. Martins-Filho

DOI: 10.14209/sbrt.2012.121

Keywords: Translucent optical networks Regenerator place- ment Link capacity optimization

Abstract

In this paper we compare two different approaches to tackle the regenerator placement and link capacity optimiza- tion joint problem in translucent optical networks. The former and simpler proposal imposes the same number of wavelengths to all links, whereas the number of wavelengths can be defined for each link in the second proposal. We used the SPEA2 algorithm to perform the multi-objective optimization process in both cases. We compared some of the solutions of the Pareto Fronts found by both proposals and we observed that the constrain on the number of wavelengths in the links leads to more expensive and/or less efficient solutions.

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Uma nova classe de mensagens para redes IEEE 802.15.4

Odilson T. Valle, André V. Milack, Carlos Montez, Paulo Portugal, Francisco Vasques

DOI: 10.14209/sbrt.2012.110

Keywords: Wireless Sensor Networks Reliability Industrial Networks

Abstract

Wireless Sensor Networks are being increasingly recommended for use in noisy industrial environment. An interes- ting standard to be used is IEEE 802.15.4, but it does not have the appropriate mechanisms to meet all requirements of industrial communications. Thus, this paper presents an expansion in the use of this standard, and presents three proposals that minimize the impact of message loss due to electromagnetic noise, enabling different approaches to retransmit messages. To prove the effectiveness of the proposed approaches, a comparative analysis is made with mechanism of guaranties provided by the standard.

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Kriging Method Applied to Predict the Coverage Area of Digital TV

Amaury Ferreira, Allan Braga, Gervásio Cavalcante, Hermínio Gomes

DOI: 10.14209/sbrt.2012.122

Keywords: Kriging Digital TV Propagation

Abstract

This paper proposes a method to estimate the signal propagation behavior of a digital TV. A measurement campaign was carried out in the metropolitan region of Belém for digital TV signal study. The proposed method uses a well- known geological tool, the kriging method. This method has the statistical robustness as its main feature.

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Análise da vazão em redes de rádios cognitivos usando Slotted Aloha

Afonso José de Faria, José Marcos Câmara Brito

DOI: 10.14209/sbrt.2012.123

Keywords: Cognitive Radio Multiple Access Throughput Performance analisys

Abstract

This paper introduces an extension of a methodology for calculating the throughput in cognitive radio networks with infrastructure and using the technique Slotted Aloha for medium access. This extension to the model includes the effects of packet error rate due to interference on the network, an effect not considered in the original model.

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Compressão de Sinais de EEG com JPEG2000 e H.264

Heitor J. Savino, Eddie B. Lima Filho, Waldir S. Silva Júnior

DOI: 10.14209/sbrt.2012.124

Keywords: Electroencephalography Data Compression H.264 JPEG2000 Preprocessing

Abstract

Recently, some authors have addressed the encoding of biological signals as two-dimensional arrays, in such a way that intra and intersegment dependencies are exploited by off- the-shelf image encoders. However, the rearrangement in a 2-d array itself provides a poor correlation across signal segments, which has the potential to reduce the compression efficiency. In order to correct this behavior, preprocessing techniques have been applied to matrices generated from different biological signals, with the goal of increasing the correlation of the arrangement, which favors the exploitation of signal features. The present work addresses this issue, by using the H.264 and JPEG2000 as image compressors. The simulation results show that the proposed methodology is competitive and constitutes a viable alternative for electroencephalogram compression.

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Atributos Acústicos Baseados na Simetria Glotal e no Classificador α -GMM para Identificação de Emoções e Locutor

D. Cavalcante, R. Coelho

DOI: 10.14209/sbrt.2012.125

Keywords: automatic speaker recognition identification pri- mary emotions TEO glottal symmetry source excitation MFCC α-GMM

Abstract

This paper presents a study of acoustic emotion recognition and its effects on speaker recognition systems. Mul- tistyle emotion identification experiments were performed using a feature based on the glottal pulse symmtery, which is estimated from the source excitation signal, and compared with the results achieved by the CB-TEO-Auto-Env feature. Speaker and emotion dual identification experiments were also performed through feature fusion with Mel-frequency cepstral coefficients (MFCC). The degration on the accuracy allowed the discrimination of emotions along with the α value of the α-GMM classifier.

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