Avaliação do sistema M-QAM OFDM sem e com tempo de guarda em um canal PLC com os ruídos Gaussiano e impulsivo e múltiplas reflexões

Abstract

This article present an evaluation of the M-QAM OFDM system over PLC channel with effects of Gaussian and impulsive noises, and multiple reflections. Some tests with the PLC adaptor were made, and by analyzing the result, it was observed that the data transmission rate decreases in a nosy channel. Therefore, a model of combined “Bernoulli-Gaussian”, impulsive, and Gaussian noises was developed. It was analyzed the effect of this model in the designed equations for the calculus of the symbolic error probability for M-QAM modulation, with square and cross-nonsquare constellation. The results obtained for the simulation showed that the addition of impulsive noise increases the M-QAM symbolic error probability. A different equation design was proposed for the calculus of the symbolic error probability, however adding multiple carriers this time. The results for this simulation exposed that the MQAM OFDM noisy composition decreases the symbolic error probability. Another problem of the PLC channel is the multiple reflections effect, which causes a signal delay. In order to analyze this effect, two equations were proposed for the M-QAM OFDM system, with and without guard interval. By evaluating the obtained results using guard interval, it was detected a dropped of symbolic error probability. The guard interval reduced the intersymbolic effect.