Análise da codificação wavelet em sistemas sujeitos ao desvanecimento Rayleigh plano.

Abstract

This thesis concerns the design, the study and the performance analysis of digital communications systems based on the coding with wavelet matrices, considering Rayleight plane fading channel models. Currently, several approaches are employed to combat the severe effects of these channels on wireless transmission systems. The wavelet coding appears as one more approach in this scenario, due to its low decoding complexity and its good performance, obtained in channels with fading. However, this coding technique requires unconventional modulation schemes so that its full potential can be exploited. This work presents a performance analysis of systems coded by wavetes matrices in time-varying channels characterized by fading Rayleight plane. Based on this analysis, new modulation schemes are specially designed to map the symbols encoded by the wavelet matrices. Specifically, signal constellations are obtained using a Genetic Algorithm (GA) guided by the analytical tools derived therefrom. In addition, a new system based on the integration of a temporal diversity transmission scheme to the wavelet coding is evaluated in this work. The performance of this new system is also investigated through an analytical formulation, derived specifically to consider the new characteristics of this system, coming from the integration of the coding with wavelets matrices with the transmission diversity scheme.