Time-domain equalizer training for ADSL

In discrete multitone (DMT) a time domain equalizer is used to shorten the length of the channel to less than the length of the cyclic prefix. The weights of this equalizer are set during initialization using a training sequence. Current techniques that rely on a version of on-line frequency domain LMS show low and uncertain convergence. Here, we show that off-line techniques that estimate the channel first, have much lower complexity, while providing much better performance. We describe a solution that requires a minimum eigenvalue to be found and show that this can be done with relatively low complexity. We also describe an off-line technique based on time domain LMS.