Percorrer por autor "Priem-Mendes, S."
A mostrar 1 - 2 de 2
Resultados por página
Opções de ordenação
- Orthogonal perfect DFT Golay codesPublication . Lanza-Gutierrez, J. M.; Ferreira, M.; Gomez-Pulido, J. A.; Priem-Mendes, S.; Pereira, J. S.; Silva, H. J. A.Deciding about which coding sequences should be used is an important issue in many communication systems, such as those employing Code Division Multiple Access (CDMA). In this paper, we propose a cascading electronic codec based on a recursive algorithm for the generation of perfect sequences, derived from an Inverse Discrete Fourier Transform (IDFT) of Golay codes. The sequences generated have a low Peak-to-Average Power Ratio (PAPR), around 3 dB, which is the PAPR of a sine wave. The proposal is compared to the original Golay codes, verifying that our codec provides better crosscorrelation and autocorrelation results, crucial to gain immunity to multi-path interference.
- Perfect Periodic Sequences with Low PAPRPublication . Ferreira, M.; Gasparovic, M.; Manjunath, G.; Priem-Mendes, S.; Pereira, J. S.Different coding sequences have huge effects on the performance of Code Division Multiple Access and Orthogonal Frequency Division Multiple Access communication systems. We propose new perfect sequences, derived from an Inverse Discrete Fourier Transform of Golay codes, and present both a mathematical and hardware-based direct/inverse generator for these new sequences. Our analysis reveals that these new sequences, named Orthogonal Perfect DFT Golay (OPDG) codes, have better autocorrelation and cross-correlation properties than the Golay codes. High Peak-to-Average Power Ratio (PAPR) is identified as one of the main practical problems involving Orthogonal Frequency Division Multiple Access power transmission. To minimize this problem, we introduce a bipolar decomposition of our new perfect sequences that permit the lowest PAPR (equal to 1) for each of the new bipolar codes. Additionally, this paper shows that the new bipolar codes derived from OPDG sequences outperform orthogonal Gold codes regarding error transmission probabilities.