Patent ID: 6987800
Filing Date: 2006-01-17
Classification: H04B

Abstract:
1. A far-end crosstalk canceling circuit for a digital subscriber line transmission system, said transmission system comprising a plurality of line termination modems adapted to receive discrete multitone signals from corresponding network termination modems over a plurality of transmission channels, each of the plurality of line termination modems comprising time/frequency transforming means for transforming said discrete multitone signals into a discrete multitone symbol of frequency components and demapping means for outputting for each frequency component a symbol of a constellation nearest to each frequency component and corresponding demodulated data, the far-end crosstalk canceling circuit comprising: estimation means, in at least one line termination modem, for estimating constellation symbols actually sent by the network termination modems from the frequency components of the discrete multitone symbols generated by the plurality of line termination modems; calculation means for calculating a linear combination of said estimated constellation symbols, subtracting said linear combination from the frequency components generated by said at least one line termination modem, and applying a resulting difference to the demapping means of the at least one line termination modem; error calculation means for calculating an error distance between the symbol of the constellation output from the at least one line termination modem and said resulting difference; and updating means for updating coefficients of said linear combination as a function of said error distance.