Desempenho da Técnica de Modulação Adaptativa sob o Enfoque da Geração de Surtos de Erros

The performance of communications systems and networks over time-varying fading channels is significantly affected not only by the average bit error rate (BER), but also by the occurrence of burst errors that may seriously degrade the operation of upper-layer communication protocols. Several recent works have shown that the adaptive modulation technique is an effective tool to maximize the spectral efficiency subjected to BER constraints in this kind of channel. However, the impact of this technique in the generation of burst errors has not been addressed so far, to the best of our knowledge. A performance comparison between the adaptive modulation technique and conventional fixed modulations in time-varying flat-fading channels is presented in this work, with focus on the burst-error generation. Several statistics usually applied in the analysis of burst-error discrete channels are obtained by simulation, under different transmission conditions. The obtained results show that the adaptive modulation technique significantly reduce the occurrence of burst errors and can provide to the upper-layer protocols an error process that has several statistical parameters close to that of a memoryless channel.