Abstract: There is disclosed a multi-carrier transceiver system for use in echo cancellation. The transceiver system is arranged to generate from input data a multicarrier transmit signal comprising a plurality of multi-carrier data blocks. The transceiver system also has a multi-carrier signal receiver responsive to an input multi-carrier receive signal received from a remote signal transmitter. An echo canceller is arranged to generate from a pair of multi-carrier data blocks (u) a set of frequency-domain echo parameters for use in generating an echo signal, to generate the echo signal using the frequency-domain echo parameters, and to input the echo signal to the multi-carrier signal receiver for use in generating an echo-cancelled receive signal from the input receive signal and the echo signal.

Abstract: A method controls performance of modem arrangements wherein a plurality of tones having associated gains with a maximum reachable value are used for carrying respective bitstreams. The method includes at least one of selectively swapping bits between the tones in the plurality and selectively changing the tone gains to optimized an error parameter. The method also includes: determining the current values for the associated gain, determining the gain margins between the maximum reachable values and the current values, and performing, to optimize the error parameter as a function of the margins, at least one of: varying the number of bits allocated to the tones, and performing a transmitted power variation by varying the gains.

Abstract: An equalizer for a multi carrier transmission system, converts a transmitted multi carrier signal into sampled frequency domain signals, and suppresses time domain delay dispersion, on the sampled frequency domain signals. It exploits circulant decomposition of a Toeplitz matrix to enable the computationally heavy evaluation of a matrix multiplied by a vector, to be avoided. Increased precision arises from the frequency domain processing being equivalent to a longer time domain FIR filter than is normally practical. The amount of compensation for different carriers can be adjusted, which can lead to increased precision.

Abstract: A method controls performance of modem arrangements wherein a plurality of tones having associated gains with a maximum reachable value are used for carrying respective bitstreams. The method includes at least one of selectively swapping bits between the tones in the plurality and selectively changing the tone gains to optimized an error parameter. The method also includes: determining the current values for the associated gain, determining the gain margins between the maximum reachable values and the current values, and performing, to optimize the error parameter as a function of the margins, at least one of: varying the number of bits allocated to the tones, and performing a transmitted power variation by varying the gains.

Abstract: There is disclosed a multi-carrier transceiver system for use in echocancellation. The transceiver system is arranged to generate from input data (1) a multicarrier transmit signal (u) comprising a plurality of multicarrier data blocks. The transceiver system also has a multi-carrier signal receiver responsive to an input multi-carrier receive signal (Yi) received from a remote signal transmitter. An echo canceller (2000) is arranged to generate from a pair of multi-carrier data blocks (u) a set of frequency-domain echo parameters (W) for use in generating an echo signal, (Y), to generate the echo signal using the frequency-domain echo parameters (W), and to input the echo signal (Y) to the multi-carrier signal receiver for use in generating an echo-cancelled receive signal (Ei) from the input receive signal (Yi) and the echo signal (Y).

Abstract: An equalizer for a multi carrier transmission system, converts a transmitted multi carrier signal into sampled frequency domain signals, and suppresses time domain delay dispersion, on the sampled frequency domain signals. It exploits circulant decomposition of a Toeplitz matrix to enable the computationally heavy evaluation of a matrix multiplied by a vector, to be avoided. Increased precision arises from the frequency domain processing being equivalent to a longer time domain FIR filter than is normally practical. The amount of compensation for different carriers can be adjusted, which can lead to increased precision.

Abstract: A method for cancelling the Echo part of a received DMT signal in presence of Far-End signal in a ADSL modem, in particular Central Office modem, where an adaptive filtration of the received signal is performed by means of a FIR Filter having multiple taps for implementing a full Least Mean Square error procedure. The procedure includes an estimation of the impulse response (w(k)) of the FIR filter and evaluating an update (w(k+1)) of the estimation in function of a correction increment parameter (?k). The method provides for performing a per-tone compensation step involving an evaluation of a per-tone increment correction (?k) that depends on the mask of tones (RT) used. The method also provides for performing a low taps compensation step reducing the number of modes to be compensated in the update to a subset (NLM) limited to the lower modes for efficiency with respect to computational complexity.