Abstract: A method for adaptive-rate communication includes setting a first target signal margin with respect to an actual noise level and a second target signal margin with respect to a predetermined noise level. The actual noise level is measured at a receiver on a communication channel between a transmitter and the receiver. A transmission rate is selected at which to transmit a signal on the channel such that for the selected transmission rate, a first signal-to-noise ratio (SNR) of the signal relative to the measured actual noise level is greater than a baseline SNR level by at least the first target signal margin, and a second SNR of the signal relative to the predetermined noise level is greater than the baseline SNR by at least the second target signal margin.

Abstract: A method for transmitting a stream of data over a channel made up of a plurality of subchannels having respective subchannel rates. The method includes partitioning the data among the subchannels, such that successive words of the data are mapped to the subchannels in alternation responsive to the respective subchannel rates. The words of the data are transmitted over the subchannels to which they are mapped, and are then received and processed to recover the stream of data.

Abstract: A method for conveying digital data from a transmitter (20) to a receiver (40) includes specifying a spectral filtering profile to be applied in conveying the data. A sequence of input symbols is generated (22) at the transmitter, corresponding to the data to be conveyed. The input symbols are precoded at the transmitter using Tomlinson-Harashima precoding (25) responsive to the specified profile, so as to generate a corresponding sequence of precoded symbols. The precoded symbols are filtered (26) in accordance with the specified profile. The precoded and filtered symbols are decoded at the receiver so as to recover the data therefrom.

Abstract: An interpolation filter for processing a sequence of input samples provided at an input rate controlled by an input clock, so as to generate interpolants at an output rate controlled by an output clock, which is substantially independent of the input clock. The filter includes a plurality of stages arranged in a succession in which each of the stages, except for a first stage in the succession, is coupled respectively to a preceding one of the stages.

Abstract: A receiver, for receiving a signal transmitted over a channel by a transmitter that includes a Tomlinson-Harashima precoder. The receiver includes a feed-forward equalizer (FFE), adapted to apply a feed-forward equalization function to the signal, so as to generate a sequence of equalized samples. A decision block is coupled to receive the equalized samples from the FFE and to generate a sequence of decision output samples responsive thereto, the decision block comprising an adaptive filter, having coefficients determined adaptively responsive to a characteristic of the channel. A Tomlinson-Harashima decoder is coupled to receive and decode the decision output samples so as to reconstruct the sequence of input symbols.

Abstract: A method is provided for initiating communications over a channel between a transmitter and a receiver within a specified spectral range, subject to a mask to be applied at the transmitter so as to attenuate at least one segment of the spectral range. The method includes providing to the receiver a definition of the at least one segment and of a level of attenuation to be applied within the at least one segment during a training interval of the communications. A training signal is transmitted from the transmitter to the receiver while applying to the training signal the level of attenuation within the at least one segment. The receiver compensates for a response of the channel based on the received training signal and on the definition of the at least one segment and of the level of attenuation.

Abstract: A method for conveying digital data from a transmitter to a receiver includes specifying a spectral filtering profile to be applied in conveying the data. A sequence of input symbols is generated at the transmitter, corresponding to the data to be conveyed. The input symbols are precoded at the transmitter using Tomlinson-Harashima preceding responsive to the specified profile, so as to generate a corresponding sequence of precoded symbols. The precoded symbols are filtered in accordance with the specified profile. The precoded and filtered symbols are decoded at the receiver so as to recover the data therefrom.

Abstract: A driver for coupling a transceiver to a line, including a first amplifier having first and second inputs and a first output coupled to a first side of the line. The driver includes a second amplifier having a third input and a fourth input and a second output coupled to a second side of the line. The driver further includes a first voltage feedback resistor, connected between the first output and the second input, and a second voltage feedback resistor, substantially the same as the first voltage feedback resistor, connected between the second output and the fourth input. The driver also includes a series resistor, coupled between the first output and the second output; and a gain resistor connected between the second input and the fourth input. The driver further includes two substantially similar current feedback resistors, connected between the gain resistor and the series resistor.

Abstract: A method for decoding a sequence of symbols encoded by an encoding system with a plurality of possible states and transmitted over a channel, wherein the encoding system output can be represented by a trellis diagram. The method includes receiving a signal corresponding to the sequence of symbols transmitted over the channel and responsive to the signal, finding respective old state metrics for one or more of the possible states of the encoding system that correspond to a given symbol in the sequence. Respective transition metrics are determined for state transitions that link the one or more possible states for which the old state metrics were found to at least some of the possible states of the encoding system that correspond to a succeeding one of the symbols in the sequence.

Abstract: A method for providing Digital Subscriber Line (DSL) service to a group of subscribers over respective subscriber loops in the presence of another, existing digital network service provided on at least some of the subscriber loops. Lower, middle and upper frequency bands are assigned for transmission over the subscriber loops, such that the existing digital network service is provided on the lower band. DSL signals are transmitted downstream on the upper band and are received upstream on the middle band, generally without transmitting or receiving DSL signals on the lower band, over those subscriber loops on which the existing digital network service, is provided. Over those subscriber loops on which the existing digital network service is not provided, the DSL signals are transmitted downstream on the lower and upper bands and are received upstream on the lower and middle bands.

Abstract: A high-speed receiver, adapted to receive signals over an input line in the presence of narrowband radio frequency interference (RFI). The receiver includes a RFI canceller module, which is coupled to receive samples of the interference from the input line. The module includes an adaptive bandpass filter, which is adapted to track a dominant frequency of the interference, and to generate a filtered output in a narrow frequency range centered on the dominant frequency. A corrector is coupled to receive the filtered output from the adaptive bandpass filter and to generate, responsive thereto, an estimate of the interference in the signals received by the receiver. A subtractor is adapted to subtract the estimate of the interference from the signals received by the receiver so as to generate a corrected output signal.

Abstract: A method for transmitting a succession of input data samples over a channel having a given channel response includes generating a set of candidate signal point sequences responsive to the input data samples, such that the input data samples are recoverable from a final signal derived from the candidate sequences. The succession of input data samples is mapped into a succession of interim signal point sequences, selected from among the candidate signal point sequences according to a signal shaping criterion. The interim signal point sequences are precoded according to the given channel response and further according to a whitening transformation. The precoded sequences are filtered in accordance with the whitening transformation, thus generating the final signal to be transmitted over the channel to a receiver.

Abstract: A method for transmitting a stream of data over a channel made up of a plurality of subchannels having respective subchannel rates. The method includes partitioning the data among the subchannels, such that successive words of the data are mapped to the subchannels in alternation responsive to the respective subchannel rates. The words of the data are transmitted over the subchannels to which they are mapped, and are then received and processed to recover the stream of data.

Abstract: An interpolation filter for processing a sequence of input samples provided at an input rate controlled by an input clock, so as to generate interpolants at an output rate controlled by an output clock, which is substantially independent of the input clock. The filter includes a plurality of stages arranged in a succession in which each of the stages, except for a first stage in the succession, is coupled respectively to a preceding one of the stages.

Abstract: A receiver for high-speed data communications, which receives a differential signal through a pair of signal lines. The receiver includes a common-mode choke, which has first and second signal windings, which are respectively coupled in series to the pair of signal lines so as to attenuate common-mode interference in the differential signal. The choke also has a sampling winding, which is inductively coupled to the signal windings so as to generate a sampled signal responsive to current flowing in the signal windings. Signal processing circuitry is coupled to receive the sampled signal from the sampling winding and to receive the differential signal from the signal windings and to process the differential signal responsive to the sampled signal.

Abstract: A method is described for mapping digital input data, including a sequence of input samples, into an interim signal point sequence, for use in conjunction with a single carrier modulation transmitter. The method includes generating a set of candidate signal point sequences, for each input sample, selecting an interim signal point sequence, into which to map the sequence of input samples, from among the set of candidate signal point sequences, so as to obtain a low peak power value of a final signal generated from the interim signal point sequence, and using a single carrier modulation transmitter to transmit the final signal to a receiver.

Abstract: A high-speed transmitter, which generates an output signal stream having a specified spectral profile. The transmitter includes a Tomlinson-Harashima precoder, which is adapted to receive a sequence of input symbols having a given input constellation and to generate, responsive to the specified spectral profile, a corresponding sequence of precoded symbols. A transmit digital filter is adapted to apply a transmit filter response, in accordance with the specified spectral profile, to the precoded symbols so as to generate a corresponding sequence of output symbols, having a given output constellation, to be transmitted in the output stream.

Abstract: A method is provided for initiating communications over a channel between a transmitter and a receiver within a specified spectral range, subject to a mask to be applied at the transmitter so as to attenuate at least one segment of the spectral range. The method includes providing to the receiver a definition of the at least one segment and of a level of attenuation to be applied within the at least one segment during a training interval of the communications. A training signal is transmitted from the transmitter to the receiver while applying to the training signal the level of attenuation within the at least one segment. The receiver compensates for a response of the channel based on the received training signal and on the definition of the at least one segment and of the level of attenuation.

Abstract: A receiver, for receiving a signal transmitted over a channel by a transmitter that includes a Tomlinson-Harashima precoder. The receiver includes a feed-forward equalizer (FFE), adapted to apply a feed-forward equalization function to the signal, so as to generate a sequence of equalized samples. A decision block is coupled to receive the equalized samples from the FFE and to generate a sequence of decision output samples responsive thereto, the decision block comprising an adaptive filter, having coefficients determined adaptively responsive to a characteristic of the channel. A Tomlinson-Harashima decoder is coupled to receive and decode the decision output samples so as to reconstruct the sequence of input symbols.