Alcatel Lucent

Lucent Technologies Inc.

Alcatel-Lucent USA Inc.

Gerhard Guenter Theodor Kramer

Philip Alfred Whiting

Alexei Ashikhmin

Miroslav Zivkovic

Carl Jeremy Nuzman

Adriaan J De Lind Van Wijngaarden

Jochen Maes

Carl Robert Posthuma

Stephan Ten Brink

Jan Sylvia Verlinden

Hungkei Keith Chow

Danny Van Bruyssel

Jean Gerardus Leonardus Jennen

Michael Peeters

Jan Willem Hellenthal

Geert Bert Ysebaert

Mamoun Guenach

Harmanus Van Tellingen

Luc Vandendorpe

Jerome Louveaux

Techniques are disclosed for compensating for crosstalk using adaptation of data signals transmitted over respective channels of a communication network. In one example, a method comprises the following steps. Data is transmitted to a communication network device via a communication line during a sequence of periods. For each period of the sequence of periods, a separate value of a measure of crosstalk that was measured at the communication network device is received, each value being an average of measurements at the device of measures of crosstalk for a plurality of communication network signal subcarriers. For each individual signal subcarrier of the plurality, a matrix is updated based on the received values, the matrix being configured to precode data transmissions to the communication network device over the individual signal subcarrier. The communication network may be a DSL system, the signal subcarriers may be DSL tones, and the measure of crosstalk may be a SINR value.

Optimizing precoder settings using average SINR reports for groups of tones

At least one channel is joined to a group of active channels in a communication system by transmitting control signals to configure respective customer premises equipment (CPE) of the active channels into a joining mode of operation, and transmitting a joining signature sequence to CPE of the joining channel over a downstream data signal path of the joining channel. A central office (CO) or other access node of the system receives correlation results from respective active channel CPE, estimates crosstalk from the joining channel into the active channels based on the correlation results, configures a precoder based on the estimated crosstalk, and adds the joining channel to the group of active channels. The channels may comprise respective subscriber lines of a DSL communication system.

Fast seamless joining of channels in a multi-channel communication system

Techniques are disclosed that efficiently obtain channel crosstalk estimates in DSL systems and other communication systems that may include unsynchronized channels. For example, a method includes obtaining a first set of estimated measures of crosstalk for a first portion of a plurality of communication channels over which data signals are to be transmitted from a transmitter to a plurality of receivers, and interpolating a second set of estimated measures of crosstalk for a second portion of the plurality of communication channels based on the first set of estimated measures of crosstalk. The first portion of the plurality of communication channels may be a subset of the plurality of communication channels and the second portion of the plurality of communication channels is a remainder of the plurality of communication channels. Each estimated measure of crosstalk may relate to at least one tone associated with at least one of the plurality of communication channels.

Interpolation method and apparatus for increasing efficiency of crosstalk estimation

An access node of a communication system comprises a plurality of transmitters adapted for communication with at least one receiver. The access node is operative to simultaneously estimate channel coefficients between multiple ones of the transmitters and the receiver, and to utilize the estimated channel coefficients to control at least one data signal sent by at least one of the multiple transmitters to the receiver. In the process of simultaneously estimating the channel coefficients, the access node transmits a plurality of distinct probing signals generated based on respective ones of a plurality of different frequency expansions. For example, each of the distinct probing signals may be generated based on a distinct combination of a common probing sequence and a selected one of the plurality of different frequency expansions.

Simultaneous estimation of multiple channel coefficients using a common probing sequence

An access node of a communication system comprises a plurality of transmitters adapted for communication with at least one receiver. The access node is operative to simultaneously estimate channel coefficients between multiple ones of the transmitters and the receiver, and to utilize the estimated channel coefficients to control at least one data signal sent by at least one of the multiple transmitters to the receiver. In the process of simultaneously estimating the channel coefficients, the access node transmits a plurality of distinct probing signals, each of which is generated based on a distinct combination of a common probing sequence and a selected one of a plurality of different frequency expansions. The access node may comprise at least a portion of at least one central office of a DSL communication system.

Techniques are disclosed for compensating for crosstalk using adaptation of data signals transmitted over respective channels of a communication system. For example, a method includes the following steps. A first set of estimated measures of crosstalk is obtained for at least a selected portion of a plurality of communication channels over which data signals are to be transmitted from a transmitter to at least a selected portion of a plurality of receivers. A first set of data signals based on the first set of estimated measures of crosstalk is adapted to generate a first set of adjusted data signals. The first set of adjusted data signals is transmitted to corresponding ones of the plurality of receivers. A second set of estimated measures of crosstalk is obtained for the selected portion of the plurality of communication channels. A second set of data signals for transmission based on the second set of estimated measures of crosstalk is adapted to generate a second set of adjusted data signals. Iteration of the obtaining, adjusting and transmitting steps is performed so as to reduce an error between subsequent estimated measures of crosstalk and actual measures of crosstalk for the plurality of communication channels.

Method and apparatus for self-tuning precoder

A multi-channel processing module is arranged in series with multiple channels of a communication system. The processing module synchronizes downstream symbols among the channels, and synchronizes downstream symbols for at least a given one of the channels with upstream symbols for that channel. The synchronization of downstream symbols among the channels and the synchronization of downstream symbols for at least the given channel with upstream symbols for that channel are collectively achieved by adjusting downstream and upstream adjustable delay elements associated with respective downlink and uplink signal paths in the multi-channel processing module. The channels may comprise respective subscriber lines of a DSL communication system.

Methods and apparatus for providing synchronization in a multi-channel communication system

An apparatus includes a transmitter configured to transmit symbols to one or more receivers via a plurality of communication channels of a physical communication link. The transmitter is configured to estimate a phase of one or more off-diagonal elements of a channel matrix for the physical communication link based on values of signal-to-interference-plus-noise ratios at the one or more receivers.

Determining a channel matrix by measuring interference

A method involves performing a plurality of acts. The acts include transmitting a first signal stream to a first channel of a multi-channel communications medium while transmitting a second signal stream to a different second channel of the medium. The second signal stream is substantially temporally correlated to the first signal stream. The method includes receiving an SINR measured at a receiver configured to receive signals from the first channel. The SINR is measured while the receiver received the first signal stream. The method includes determining a channel matrix element between the first and second channels or a ratio of said channel matrix element to a diagonal element of the channel matrix. The act of determining is based on the received SINR.

Determining channel matrices by correlated transmissions to different channels

A modulation and coding scheme for a communication system is based on use of nonsystematic repeat-accumulate codes for encoding channel information for transmission, and for employing a combined detection and decoding arrangement to decode the coded channel information. The nonsystematic repeat-accumulate codes may be generated by an encoder at a transmitter and decoded by a composite detector/decoder arrangement at a receiver.

Nonsystematic repeat-accumulate codes for encoding and decoding information in a communication system

Techniques and systems for design and use of generalized LDPC codes. A generalized LDPC code comprises a set of codewords producing valid results when submitted to a validator comprising a set of variable nodes and a set of check nodes, with outputs of the variable nodes being connected to inputs of the check nodes by interleaver edges. Each check node and variable node is in the form of a code, with the output of a node being valid if its inputs form a valid codeword. An extrinsic information transfer function (EXIT) chart is used to form a check node curve and a variable node curve is matched to the check node curve. The variable nodes are then constructed so as to provide the information transfer properties indicated by the variable node curve.

Methods and apparatus for communication using generalized low density parity check codes

A method and apparatus for reducing the number of erred bits in the decoded signal by using a channel decoder whose transfer characteristic is matched to the transfer characteristic of the MIMO detector. This means that the curve of the transfer characteristic of the MIMO detector is 1) above the curve of the reflected transpose of the transfer characteristic of the channel decoder for about 95% of the curve, and 2) close to the reflected transpose of the curve of the transfer characteristic of the channel decoder. Particularly, an LDPCC decoder can be used as the channel decoder and can be matched to the MIMO detector by matching 1) the transfer characteristic of the LDPCC decoder's CND to 2) the transfer characteristic of a combination of the MIMO detector and the LDPCC VND. Furthermore, the LDPCC can be similarly matched to any appropriate detector in addition to or instead of the MIMO detector. Additionally, a receiver can re-match the transfer characteristics of the detector and the channel decoder when the channel characteristics and/or SNR of the received signals change.

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Chatham, NJ, United States of America

Gerhard Guenter Theodor Kramer