Performance of hybrid-ARQ coding schemes over M-QAM equalized mobile radio channels

In this work, we focus on the performance of ARQ (automatic repeat request) error control strategies over mobile radio channels with M-QAM modulation. This type of error control is used to detect errors, asking for a retransmission when errors are detected. It is seen that single ARQ schemes are not suitable for mobile environments, making it necessary to consider other techniques for equalization in order to cope with ISI (intersymbol interference). Using an equalizer does not improve significantly the performance, so hybrid-ARQ (H-ARQ) schemes must be evaluated. The performance is obtained in terms of throughput versus signal-to-noise ratio.