BERT Chart Analysis of Adaptive and Non-Adaptive Turbo Frequency Domain Equalization

This paper analyzes the performance of turbo frequency domain equalization (TFDE) with 16-QAM by bit error rate transfer (BERT) chart. We derive the BERT chart for the two cases in which the equalizer adapts or does not adapt from iteration to iteration. In the first case, the equalizer parameters change during iterations based on the feedback information and in the latter case they do not change. In the BERT chart analysis of TFDE, we theoretically find the mean and variance of the Gaussian-like distribution of the equalizer output. The mean and variance of the equalizer output depend on the channel parameters, channel signal to noise ratio and the decoder bit error rate in the previous iteration. Finally we compare the BERT chart results with simulation results and show that the predicted results are fairly accurate.