On the Performance Analysis of Different Link to Path Restoration Schemes for All-Optical Networks

Rodrigo C. de Freitas, Nayane F. Aragão, Lucas B. Costa, Rodrigo C. L. Silva, Carmelo J. A. Bastos-Filho, Joaquim F. Martins-Filho, Daniel A. R. Chaves, Helder A. Pereira

DOI: 10.14209/sbrt.2012.55

Keywords: All-optical networks physical layer impairments restoration single link failure

Abstract

In this paper we compare the performance of three different restoration schemes for all-optical networks (link, subpath and path) upon a single link failure considering physical layer impairments. In addition, we propose two strategies for link or subpath restoration. Although the strategies based on subpath restoration present a better performance when compared to the strategies based on link restoration, the path restoration scheme far outperforms these other schemes. From the results, there is an indication that the path restoration is the best reactive scheme for all-optical network without wavelength conversion.

Download

A Full-Diversity Scheme for Four Transmit Antennas and Quantized Feedback Channel

Samuel T. Valduga, José C. Menezes Jr., Renato Machado, Natanael R. Gomes, Andrei P. Legg

DOI: 10.14209/sbrt.2012.60

Keywords: Coding gain MIMO systems quantized feedback transmit diversity

Abstract

In this paper we propose a spatial diversity scheme for four transmit antennas and quantized feedback channel systems. We present a preprocessor design that enables this scheme to achieve full diversity order as well as a coding advantage. A quantized feedback analysis of the proposed scheme for quasi-static flat Rayleigh fading channels is also performed. Through simulation results, we show that the proposed scheme has a performance improvement of about 1.6dB and 2dB over ACBS scheme for 3 and 4 feedback bits, respectively.

Download

Métrica objetiva para avaliação do conforto na visualização de vídeos estereoscópicos

Marcelo A. Miguel, Eduardo A. B. Silva, Carla L. Pagliari

DOI: 10.14209/sbrt.2012.81

Keywords: Stereoscopy Quality Assessment Visual Comfort

Abstract

This article presents a method for automatically assessing the comfort associated with viewing stereoscopic videos based on the stereo vision geometry, to assist the camera stereo rig adjustment. The proposed method estimates, using SIFT and segmentation techniques, the extent of the frame on each scene which causes eye strain to the viewer.

Download

Radiation and Absorption Properties of Gold Nanodipoles in Transmitting Mode

K. Q. Costa, V. Dmitriev, T. L. T. Santos, N. W. P. Souza, J. L. Souza, and G. L. Silvano

DOI: 10.14209/sbrt.2012.83

Keywords: Optical antennas cylindrical dipoles plasmonics radiation

Abstract

This paper presents an analysis of radiation and absorption properties of cylindrical gold nanodipoles in the transmitting mode. The conventional antenna theory and the linear method of moments are used for the theoretical analysis of these antennas in the near-infrared and lower optical frequencies (100−500THz). Radiation and absorption parameters, such as input impedance, efficiency, radiation and loss resistance are calculated in function of frequency for different dipole’s lengths and radii. The presented results can be useful to design efficient nanodipoles and to perform the input impedance matching of these antennas with plasmonic optical transmission lines.

Download

Realce de Sinais de Voz em Presença de Ruídos Acústicos Não-Estacionários utilizando o Método EMD

L. Zão, R. Coelho

DOI: 10.14209/sbrt.2012.84

Keywords: Speech enhancement nonstationary noises empirical mode decomposition

Abstract

This paper presents a speech enhancement technique based on the empirical mode decomposition method. The EMD-based filtering is evaluated in speech utterances corrupted with six acoustic noises and six different signal-to-noise ratios. The noises present different values of INS (index of nonstationarity). For comparison, another speech enhancement technique, based on the use of IMCRA and OMLSA estimators, is used in the experiments. The comparison among the techniques considers two different measures: the segmental signal-to-noise ratio and the accuracies in a speaker identification task. The results show that the enhancement performance is strongly dependent on the INS of the noises.

Download

Underwater Acoustic Noise Model for Shallow Water Communications

José S. G. Panaro, Fábio R. B. Lopes, Leonardo M. Barreira, Fidel E. Souza

DOI: 10.14209/sbrt.2012.85

Keywords: Underwater Communications Underwater Acoustic Noise Noise Distribution

Abstract

This article presents an empirical model for the noise of the acoustic underwater channel in shallow water from the analysis of field data measurements. A probability density function for the noise amplitude distribution is proposed and the associated likelihood functions are derived. As a result, an expression to the probability of symbol error for binary signaling is presented for the channel. Additionally, the results of simulations conducted using the field collected noise samples are presented, in order to verify the noise effect on the performance of underwater acoustic communication binary signaling systems.

Download

Modelo Estocástico do Algoritmo NLMS para Sinais de Entrada Gaussianos Complexos

Eduardo Vinicius Kuhn, Rui Seara

DOI: 10.14209/sbrt.2012.82

Keywords: NLMS algorithm adaptive filtering stochastic modeling

Abstract

This paper presents the stochastic modeling of a well-known adaptive algorithm from the literature, the normalized least-mean-square (NLMS) algorithm. Considering a system identification problem with stationary plant and complex Gaussian input data, an accurate model obtained analytically is derived here. Such accuracy is mainly due to the form how the calculus of the normalized moments is performed. Simulation results for different operation scenarios are presented, showing that the proposed model predicts satisfactorily the algorithm behavior for both transient and steady-state phases.

Download

Limiting the statistical behavior of interference: the concept of equivalent limiting masks

Alexander Beremiz Hilario Tacuri, José Mauro P. Fortes

DOI: 10.14209/sbrt.2012.86

Keywords: Interference Masks satellite communications

Abstract

The use of masks to limit the statistical behavior of interference is very common in communications. The ITU- R Radio Regulations has a number of examples of interference masks that are used to guarantee that the external interferences reaching a communication system would not prevent it from meeting its performance requirements. Each of these masks refers to a specific situation that depends on the characteristics of the interfering and the interfered-with systems. Currently, for each specific situation there is only a single mask to be applied. This paper presents a new concept in which, instead of a single mask, a set of equivalent masks is used to guarantee that, even in the presence of interference, a given communication link meets its performance requirements.

Download

Cooperative Transmission Scheme with Two Relay Stations and Phase Feedback Channels

Bruno Fontana da Silva, Renato Machado, Andrei P. Legg

DOI: 10.14209/sbrt.2012.10

Keywords: Cooperative systems phase feedback relay channel transmit diversity

Abstract

In this paper, we propose a new transmission scheme with two relay stations and phase feedback channels between the relays and the destination node. The preprocessor use in the relay stations is managed to achieve a full diversity order and also an array gain at the destination node. A phase feedback investigation for the proposed scheme is presented assuming quasi-static flat Rayleigh fading channels. An analysis of the relay spatial allocation design is also performed.

Download

Spectrum Sensing for Powering Power Line Communications

Laryssa R. Amado, Eduarda S. C. Losqui, Moises V. Ribeiro, Fabricio P. V. de Campos, Alvaro Augusto M. de Medeiros

DOI: 10.14209/sbrt.2012.218

Keywords: power line communication spectrum sensing signal processing

Abstract

The use of electric grids for communication pur- poses may interfere with radio communication services. To offer new directions to avoid electromagnetic interference that reduces the effectiveness of electric power grids as a green and low- cost communication channel, this paper discusses and introduces spectrum sensing techniques for cognitive power line communi- cation (PLC) systems. Additionally, a measurement campaign for monitoring the radio spectrum in the range from 1.7 to 100 MHz is discussed as well as attained results with the spectrum sensing technique. The numerical results indicate the proposed spectrum sensing technique can offer good performance in a cognitive PLC systems.

Download