Sistemas de transmissão com codificação wavelet com aumento da eficiência espectral.

Abstract

Since its advent, wavelet coding has been recognized as a promising technique for wireless transmission systems over white noisy and fading channels, especially due to its low decoding complexity and “natural” transmission rate adaptation. Notice that the last feature is very convenient with adaptive digital transmission systems. But, what are the main obstacles impairing a more general utilization of wavelet coding? Two aspects are in order: the requirement to project “special” constellations and its limited spectral efficiency. These two problems are attacked and solved in this thesis; being these solutions its main contributions. The first problem is solved with the introduction of simpler methods to building special constellations and, the second problem is solved by creating blocks of wavelet symbols prior their transmission over the channel. Since the a priori block probabilities are crucial to decoding, they are computed by means of an specially adapted probability generating function. Finally, the results obtained are advantageable compared with space-time encoded systems of similar spectral efficiency.