Next cancellation in xDSL systems using variable-length cancellers

An algorithm that reduces the computational load in near-end crosstalk (NEXT) cancellation in xDSL systems is proposed. The algorithm adjusts the length of each adaptive filter according to the strength of the NEXT and thus results in a minimum usage of filter taps. The algorithm starts the NEXT cancellation by using adaptive filters with minimum filter lengths. As the adaptation progresses, the algorithm adjusts the filter length of each adaptive filter according to the magnitude of the NEXT. When all the adaptive filters have fully converged, another algorithm is used to readjust the filter length of those adaptive filters that might be too long or too short.