An echo canceller reduces an echo signal produced when the transmitted
signal leaks back into the receiver via a hybrid. The echo canceller
estimates the echo signal from the transmitted signal, and then
subtracting the estimated echo signal from the received signal. In
practice, the echo path channel in a DMT-modem is much longer than the
cyclic prefix, and therefore, the received echo signal will be subjected
to both ISI (inter-symbol-interference) and ICI
(inter-carrier-interference). A traditional echo canceller, designed for
a xDSL-modem, uses either a time domain adaptive FIR-filter or a combined
echo canceller implemented in both time and frequency domain. A
matrix-based adaptive echo canceller is implemented in the frequency
domain. Various example embodiments are disclosed.