2002 International Telecommunications Symposium

"In this paper, we propose a systematic procedure for constructing good space-time trellis codes derived from cyclic BCH codes over local finite commutative rings. The procedure is based on finding a primitive element in the group of units of the Galois extension ring. For a given design distance, the polynomial generator of a BCH cyclic block code over...

"The aim of this paper is to establish some of the structural properties which are common to the classes of binary translation-invariant propelinear codes and binary G-linear codes. In general, the codes in these classes are nonlinear codes, however they are part of the same symmetry n group decomposition Γ(Z_2^n) of Z_2^2 . We show that binary G-linear...

"In this paper we investigate the problem of compressing and reliably transmitting multispectral imagery over binary symmetric channels. A novel source/channel multispectral image coding scheme is proposed. The basic engines of our scheme is a powerful de-correlating transform both in spectral and spatial domains, an optimal bit allocation procedure,...

"We provide a new method to evaluate the center density of ideals in the ring of algebraic integers of subfields of Q(Cpq), where p and q are distinct prime numbers. This method allows us to reproduce rotated versions of known dense lattices in some dimensions. For example, we obtain lattice E_8 from several fields Q(Cpq). Because of their high...

"This article describes a logic programmable audio switching matrix developed by this Center to substitute the old mechanical ones in some of the Brazilian Navy ships. With the purpose to switch audio signals only, this new system allows a fast, friendly and easy switching control by an IBM - PC compatible computer and a specific FPGA-based hardware."

"Intention of the paper is to show in reduced form the methods of suppression non-linearity products in terrestrial digital video transmitter with apply of digital precorrection unit and output filter unit. "

"Based on the spectral overlapping of two conventional m-QAM modulations, an {m-QAM}^2 modulation technique is performed. This architecture has shown to have better bit error performance than its equivalent M-QAM modulation. The object of this paper is to present a multilevel coding method based on a ring of integer modulo-q over an expanded trellis...

"The availability of line-of-sight (LOS) microwave digital systems which work at high transmission rates such as 155 Mbit/s, may be strongly limited by frequency selective fading effects. The main countermeasure techniques against the fading are equalization, diversity and error control coding. Under adverse geoclimatic conditions, the path length and/or...

"In this paper we investigate the use of adaptive minimum bit error rate (MBER) decision feedback (DFE) multiuser receivers (MUD) for DS-CDMA systems. We examine stochastic gradient adaptive algorithms for approximating the bit error rate (BER) from training data. Computer simulation experiments show that the DFE-MUD structure employing adaptive MBER...

"In this paper we investigate adaptive multiuser receivers for DS-CDMA systems using recurrent neural net- works (RNN). A comparative analysis of multiuser detec- tion (MUD) schemes employing linear and non-linear struc- tures is carried out. Adaptive minimum mean squared error (MMSE) linear MUD receivers are examined with the LMS algorithm and compared...