Abstract: An apparatus comprising a receiver coupled to a digital subscriber line (DSL) between an exchange site and a customer premise equipment (CPE) and configured to send a feedback error message to train a precoder coupled to the exchange site, wherein the feedback error message comprises a plurality of error components and an indication of a quantity of bits per error component, a quantization accuracy per error component, or both. Included is a method comprising sending an error feedback message to a DSL crosstalk precoder to train the crosstalk precoder, wherein the error feedback message comprises an error vector and a quantization scaling factor of the error vector.

Abstract: An apparatus comprising an artificial noise (AN) controller coupled to a digital subscriber line (DSL) transmitter and configured to adjust an AN level for a signal transmitted by the DSL transmitter, wherein the AN level is adjusted based on an actual signal to noise ratio (SNR) of the signal from the receiver to achieve a desired SNR for the signal. Also disclosed is a method comprising maintaining a data rate in a line at about a desired level by adjusting an AN level in a transmitted signal based on a SNR of a received signal.

Abstract: A method and apparatus for creating a bivariate histogram with a plurality of variables using impulse noise data is disclosed. The bivariate histogram describes the joint statistics between at least two of the variables. Also disclosed is an impulse noise monitor (INM) in communication with an impulse noise sensor (INS). The INM receives error data from the INS and creates a bivariate histogram with a plurality of variables using the error data. Included is a method for providing a bivariate histogram with an impulse noise length (IL) and an impulse noise inter-arrival time (IAT) for a plurality of impulse noise events. The IL and the IAT are each measured in integer multiples of discrete multi-tone symbols, and the bivariate histogram is used to determine a minimum impulse noise protection.

Abstract: To reduce the ISDN crosstalk in an incoming DSL signal, a crosstalk canceller observes at least a portion of the crosstalk signal and reproduces an estimate of the crosstalk signal for at least a portion of that signal within the DSL band. The crosstalk canceller applies a canceling signal based on the estimated crosstalk signal to reduce the crosstalk in the received DSL signal.

Abstract: An apparatus comprising a transmitter configured to transmit a low power mode Discrete Multi-Tone (DMT) signal using a plurality of DMT tones, wherein at least some of the DMT tones comprise a low power mode (LPM) tone that carries data at a normal PSD level and a non-LPM tone that is transmitted at a reduced PSD level. Also disclosed is a network component comprising at least one processor configured to implement a method comprising detecting a plurality of signal to noise ratio (SNR) values for a plurality of LPM tone signals and a plurality of non-LPM tone signals, and handling crosstalk interference between lines using the detected SNR values.

Abstract: An apparatus comprising a transmitter configured to transmit a low power mode Discrete Multi-Tone (DMT) signal using a plurality of DMT tones, wherein a subset of the DMT tones are used for transmitting data, and wherein at least some of the remaining DMT tones are used for a Peak-to-Average Ratio (PAR) reduction is disclosed. Included is a network component comprising at least one processor configured to implement a method comprising promoting transmission of a plurality of data streams using a plurality of first digital tones, and promoting transmission of at least one second digital tone that reduces a peak of a signal generated by at least one of the first digital tones.

Abstract: Efficient implementation techniques of a low power mode, (i.e. L2 mode for ADSL2) for DSL transceivers are described. The techniques save memory space and reduce implementation complexity. A constellation mapper in a DSL transmitter determines the number of bits to be retrieved for an ith sub-carrier in the low power mode based on the number of bits allocated for this same sub-carrier in a normal transmission mode, (e.g. L0 mode in ADSL2) and a bit allocation threshold T. A constellation demapper in a DSL receiver determines the number of bits used for an ith sub-carrier in the low power mode based on the bit tables for the L0 mode and the bit threshold T.

Abstract: A method for managing a channel matrix is provided. The method includes: obtaining whether a user logs on or logs off; adding a history record of channel information of the user to a channel matrix when the user logs on; recording current channel information of the user in the channel matrix and deleting the channel information of the user from the channel matrix when the user logs off. The channel matrix may be timely updated based on when the user logs on or off. Accordingly, the channel crosstalk is eliminated timely and correctly according to the channel matrix, and the affection on the crosstalk eliminating capacity caused by the user logs on or logs off can be avoided.

Abstract: A network component comprising at least one processor configured to implement a method comprising creating a bivariate histogram using impulse noise data comprising a plurality of variables, wherein the bivariate histogram describes the joint statistics between at least two of the variables. Also disclosed is an apparatus comprising an impulse noise monitor (INM) in communication with an impulse noise sensor (INS), wherein the INM is configured to receive error data from the INS and create a bivariate histogram comprising a plurality of variables using the error data. Included is a method comprising providing a bivariate histogram comprising an impulse noise length (IL) and an impulse noise inter-arrival time (IAT) for a plurality of impulse noise events, wherein the IL and the IAT are each measured in integer multiples of discrete multi-tone symbols, and wherein the bivariate histogram is used to determine a minimum impulse noise protection.

Abstract: Techniques for establishing TTR indication in ADSL Annex C based communication systems are disclosed. The techniques enable, for example, hyperframe alignment and synchronized initialization procedures (e.g., G.hs).

Abstract: A system for realizing emergency rate reduction (SOS). A receiver initiates a short rate-reduction request, and communicates that request to a transmitter. The transmitter initiates an operational switch to an adjusted transmission reference (i.e., a new bit/gain table), by sending a signal to synchronize the operational switch for both the transmitter and the receiver. The adjusted transmission reference may be calculated using a formula, from a current bit/gain table, or may be a predefined bit/gain table. The parameters of the formula may be predefined, calculated during initialization, or determined in real time during SOS.

Abstract: Techniques for establishing TTR indication in ADSL Annex C based communication systems are disclosed. The techniques enable, for example, hyperframe alignment and synchronized initialization procedures (e.g., G.hs).

Abstract: A method for preventing false starts during a handshake session involves the use of service identifiers for modem devices. The identifications are provided to one another for subsequent communication. To commence communications, a local device generates a request signal to initiate a handshake session. The request signal includes an identification unique to the remote device. The remote device receives the request and verifies the identification. The remote device then sends a response, which may optionally include an identification unique to the local device. The local device receives the response and verifies the identification before completing the handshake session.

Abstract: Operation of a digital subscriber line system in a power saving quiescent mode is described. A quiescent mode (Q-mode) is entered into from a steady-state or normal operation mode in which payload data is transmitted when criteria indicates that the transmitter has stopped transmitting payload data for a certain time period but that the current transmission session has not ended. A Q-mode signal is generated that uses constellation points that are used in the payload carrying state. The peak-to-average ratio (PAR) of the signal is also minimized by a PAR minimization method to find a combination of these constellation points satisfying a PAR threshold.

Abstract: Symbol synchronization in a communication system is carried out as follows. A plurality of symbols corresponding to a transmitted signal is received, where the plurality of symbols include guard intervals. Peak correlation is obtained using the plurality of received symbols. The second derivative of the peak correlation is obtained, and one or more peaks within a corresponding guard interval are identified from the second derivative. A symbol start time for each received symbol is estimated based on the second derivative of the peak correlation.

Abstract: A method for channel estimation in a wireless communication system includes the following steps. Channel transfer function is computed at continual and scattered pilot cells using transmitted and received signals at the continual and scattered pilot cells. Time-domain adaptive interpolation is performed to obtain channel transfer function at non-pilot cells of the scattered pilot tones using the channel transfer function computed at continual and scattered pilot cells. Frequency-domain adaptive interpolation is performed to obtain channel transfer function at non-pilot cells of non-pilot tones using the channel transfer function computed at continual and scattered pilot cells.

Abstract: A system used to synchronize the clock frequency of a receiver with that of a transmitter, where both the receiver and transmitter communicate using the ADSL Annex C standard. The transmitter continuously transmits pilot tones to the receiver. The receiver determines the phase error between sequential pilot tone symbols to determine a phase error. The receiver uses the phase error to adjust the receiver clock frequency. However, if the most recently received symbol is subject to near end crosstalk or is subject to far end crosstalk and is a boundary symbol, the receiver ignores the phase error and does not adjust the receiver clock frequency.

Abstract: An echo cancellation (EC) system for use in a full-duplex communication system having asymmetric signal sampling rates, in particular an ADSL system, is described. The system performs the cancellation of local echo signal in digital or analog domain depending on the loop condition using a switching logic. The EC system further includes an EC unit that generates a digital echo estimate signal at the lower sampling rate of the transmitted signal and then interpolates the digital signal to higher sampling rate to cancel echo signal thereby reducing computation complexity. The digital interpolated echo estimate signal is converted to analog form for use in analog echo cancellation. The subtracted signal resulting from the analog echo cancellation is converted into digital domain and used as feedback for the EC unit to adaptively improve the accuracy of the echo estimate.

Abstract: Framing techniques for ADSL systems that allow programmable fixed overhead efficient framing and seamless rate changes.

Abstract: A system and method for selecting the operational mode in an ADSL Annex C environment during the handshake operation while increasing the accuracy of the determining the throughputs across the possible frequency spectrum while only having access to the power level of a small number of frequency bins during the handshake operation. In one embodiment of the present invention, the present invention receives signals in a multiple but small number of bins and estimates the loop length based upon the signal power in at least two of these bins. The present invention then identifies the noise profile over the relevant band of frequencies (or a subset thereof) to determine the bit rate. In one embodiment, the present invention selects the mode based upon a the bit rate in a single direction. In another embodiment, the present invention selects the mode based upon both the upstream and downstream bit rates.