Estudo do ruído impulsivo gaussiano gatilhado para sistemas de modulação digital.

Abstract

This thesis presents a new approach for analysing Gaussian impulsive noise and double gated impulsive noise and its effects on digital modulation schemes like BFSK, BPSK, MPAM, MPSK and MQAM. In this approach, both the amplitude and varying duration of the pulses noise added can be characterized as an amplitude modulation of the impulsive noise by a discrete random process C(t), defined in continuous time. Are presented new models for Gaussian gated impulsive noise (Gated Additive White Gaussian Noise - GAWGN) and double gated (Gated Gated Additive White Gaussian Noise - G2 AWGN) as well as new expressions for the probability density function, autocorrelation function and power spectral density by using this new approach. From these results are calculated new expressions for bit error probability of schemes like BFSK, BPSK, MPAM, MPSK and MQAM for optimum maximum likelihood receiver a posteriori. The main advantage of this method is that parameters of the impulsive noise such as amplitude, duration, instants and intervals between noise ocurrences can be modeled by the process C(t). Are also presented two new models of impulsive noise for which the random states of C(t) are modeled by Markov and Poisson processes. For these models, new exact expressions are obtained for the bit error probability of MQAM modulation schemes. Besides these contributions are presented implementations in Simulink textregistered that allow simulating the effects of the proposed noise for different modulation schemes considered.