VII International Telecommunications Symposium

This article presents an adaptive cross-layer solution for wireless networks. The main objective is to estimate the impact that different physical layer variations and approaches can have on the network layer. The data loss probability obtained directly from physical layer will provide the routing protocol enough information to choose routes with the...

In this paper, we present an analysis of the resonant behavior of modified bowtie nanoparticles with polynomial sides. The method of moments is used to solve numerically the scattering problem. With this model, we investigate the variation of the spectral response and near field distribution in function of the length and polynomial order of the...

Least Absolute Shrinkage and Selection Operator (LASSO) is a useful method to achieve coefficient shrinkage and data selection simultaneously. The central idea behind LASSO is to use the L1-norm constraint in the regularization step. In this paper, we propose an alternative complex version of the LASSO algorithm applied to beamforming aiming...

This paper presents the results of a comparative tests between rain attenuation prediction methods for terrestrial links. To perform the tests, experimental data from measurements available in the ITU-R data bank have been used. Results indicate that the method currently recommended by the ITU-R significantly underestimates the measured attenuation....

Self-organized wireless networks comprise different devices cooperating among themselves to provide network services. These networks support critical applications in different domains requesting simultaneously robustness, security and availability. Hence, it is essential to develop mechanisms for steering nodes’ cooperation in order to preserve...

This paper presents theorems showing how to obtain a binary nonlinear code from a p-ary linear constacyclic maximum distance separable code, where p is a prime number, by using a representation of GF(p) as binary ptuples. Two asymptotically optimum classes of binary constantweight codes are constructed. Binary cyclic codes are derived for a...

It is developed a case study, unifying theoretical and practical aspects, concerning planning and implementation of orthogonal frequency division multiplexing (OFDM) point-tomultipoint (PtMp) links at Industrial, Scientific and Medical (ISM) 5 GHz band. The proposed design methodology is validated using analytical results and field measurements.

This paper presents a novel approach for deciding on the appropriateness or not of an acquired fingerprint image into a given database. The process begins with the assembly of a training base in an image space constructed by combining Principal Component Analysis (PCA) and edge detection. Then, the parameter value (H) – a new feature that helps in...

This paper proposes a network protocol that relies on cross-layer interaction between the Medium Access Control (MAC), Network and Application layers for wireless sensor networks (WSN). The protocol uses Time Division Multiple Access (TDMA) with varying time intervals, which, in conjunction with a routing protocol, defines the operation of network...

This paper analyzes the performance of voice encoders used for digital communications, especially in VoIP calls, for Brazilian Portuguese phonemes. The focus is the adaptation capacity of encoders to vocal tract changes in these intervals during the signal processing. Short sentences containing all the basic Portuguese phonemes were used....