Abstract: An access node of a communication system is configured to control crosstalk between channels of the system. A set of L distinct and linearly independent pilot signals is generated, with each pilot signal having length n, where n>L such that n?L linearly independent n-tuples are available for use in detection and correction of impulse noise. In an illustrative embodiment, the L pilot signals are mutually orthogonal. The L pilot signals are transmitted over respective ones of the channels, and one or more of the pilot signals as received over their respective channels are processed to detect the presence of impulse noise. A crosstalk estimate corrected for the detected impulse noise is generated and utilized to control crosstalk between two or more of the channels.

Abstract: 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.

Abstract: An access node of a communication system comprises a plurality of transmitters adapted for communication with at least one receiver over a plurality of channels. The access node is operative to obtain estimated crosstalk coefficients between a joining channel and an active channel, and to set a power level of at least one signal transmitted over the joining channel based on the estimated crosstalk coefficients. The access node obtains the estimated crosstalk coefficients by first obtaining a subset of the estimated crosstalk coefficients and subsequently determining additional ones of the estimated crosstalk coefficients by applying an interpolation process to the estimated crosstalk coefficients in the subset. The access node sets the power level of the signal transmitted over the joining channel in a manner that ensures maintenance of a desired performance characteristic for the active channel.

Abstract: 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 transmit pilot signals from respective associated ones of the transmitters, to estimate channel coefficients between 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 transmitters. The pilot signals are partitioned into a plurality of sets of pilot signals such that pilot signals from the same set have respective subpilots that are orthogonal to one another and pilot signals from different sets have respective subpilots that are not orthogonal to one another but are instead quasi-orthogonal to one another. The pilot signals are associated with the respective transmitters based on the partitioning of the pilot signals into sets.

Abstract: An access node of a communication system is configured to control crosstalk between channels of the system. A set of L distinct and linearly independent pilot signals is generated, with each pilot signal having length n, where n>L such that L?n linearly independent n-tuples are available for use in detection and correction of impulse noise. In an illustrative embodiment, the L pilot signals are mutually orthogonal. The L pilot signals are transmitted over respective ones of the channels, and one or more of the pilot signals as received over their respective channels are processed to detect the presence of impulse noise. A crosstalk estimate corrected for the detected impulse noise is generated and utilized to control crosstalk between two or more of the channels.

Abstract: An access node of a communication system is configured to generate denoised crosstalk estimates for respective channels of the system and to adjust power levels of signals transmitted over one or more of the channels based on the denoised crosstalk estimates. The access node obtains crosstalk estimates for the respective channels. The access node is configured to convert the crosstalk estimate for a given channel to a discrete transform domain, to substantially eliminate in the discrete transform domain one or more designated portions of the crosstalk estimate for the given channel, and to convert remaining portions of the crosstalk estimate for the given channel back from the discrete transform domain to obtain the corresponding denoised crosstalk estimate for the given channel. The access node may comprise one or more central offices of a DSL communication system.

Abstract: The present invention relates to a crosstalk estimation device for estimating crosstalk between communication lines in a precoding group. The crosstalk estimation device comprises transmission means for transmitting a pilot sequence and reception means for receiving error feedback on one or more communication lines in the precoding group. The crosstalk estimation device further comprises crosstalk estimation means for combining the pilot sequence with the error feedback in order to obtain a crosstalk estimation between the communication lines. The device further comprises selection means for selecting a subset of one or more communication lines from the precoding group. The transmission means are adapted to transmit the pilot sequence only on the subset.

Abstract: An access node of a communication system receives signals over respective first and second channels of the system, processes the signal received over the second channel and an initialization signal associated with the first channel to obtain estimated crosstalk coefficients characterizing crosstalk from the first channel into the second channel, introduces respective predetermined delays into the respective signals received over the first and second channels, and utilizes the estimated crosstalk coefficients to adjust the signal received over the second channel as delayed by the corresponding predetermined delay in order to compensate for the crosstalk from the first channel into the second channel. The first and second channels may comprise respective joining and active subscriber lines of a DSL system.

Abstract: A multiple-input, multiple-output (MIMO) communication system is configured to perform user scheduling and associated precoding. The system includes multiple terminals and at least one base station configured to communicate with the terminals. The base station is operative to obtain channel vectors for respective ones of the terminals, to select a subset of the terminals based on magnitudes of the respective channel vectors, to compute a precoding matrix using the channel vectors of the selected subset of terminals, and to utilize the preceding matrix to control transmission to the selected subset of terminals. The system may be, for example, a time-division duplex (TDD) multi-user MIMO system in which the multiple terminals comprise autonomous single-antenna terminals.

Abstract: An access node of a communication system comprises a plurality of transmitters adapted for communication with at least one receiver over a plurality of channels. The access node is operative to obtain estimated crosstalk coefficients between a joining channel and an active channel, and to set a power level of at least one signal transmitted over the joining channel based on the estimated crosstalk coefficients. The access node obtains the estimated crosstalk coefficients by first obtaining a subset of the estimated crosstalk coefficients and subsequently determining additional ones of the estimated crosstalk coefficients by applying an interpolation process to the estimated crosstalk coefficients in the subset. The access node sets the power level of the signal transmitted over the joining channel in a manner that ensures maintenance of a desired performance characteristic for the active channel.

Abstract: 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.

Abstract: 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 transmit pilot signals from respective associated ones of the transmitters, to estimate channel coefficients between 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 transmitters. The pilot signals are partitioned into a plurality of sets of pilot signals such that pilot signals from the same set have respective subpilots that are orthogonal to one another and pilot signals from different sets have respective subpilots that are not orthogonal to one another but are instead quasi-orthogonal to one another. The pilot signals are associated with the respective transmitters based on the partitioning of the pilot signals into sets.

Abstract: An access node of a communication system is configured to generate denoised crosstalk estimates for respective channels of the system and to adjust power levels of signals transmitted over one or more of the channels based on the denoised crosstalk estimates. The access node obtains crosstalk estimates for the respective channels. The access node is configured to convert the crosstalk estimate for a given channel to a discrete transform domain, to substantially eliminate in the discrete transform domain one or more designated portions of the crosstalk estimate for the given channel, and to convert remaining portions of the crosstalk estimate for the given channel back from the discrete transform domain to obtain the corresponding denoised crosstalk estimate for the given channel. The access node may comprise one or more central offices of a DSL communication system.

Abstract: The present invention relates to a crosstalk estimation device for estimating crosstalk between communication lines in a precoding group. The crosstalk estimation device comprises transmission means for transmitting a pilot sequence and reception means for receiving error feedback on one or more communication lines in the precoding group. The crosstalk estimation device further comprises crosstalk estimation means for combining the pilot sequence with the error feedback in order to obtain a crosstalk estimation between the communication lines. The device further comprises selection means for selecting a subset of one or more communication lines from the precoding group. The transmission means are adapted to transmit the pilot sequence only on the subset.

Abstract: 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.

Abstract: A multiple-input, multiple-output (MIMO) communication system is configured to perform user scheduling and associated precoding. The system includes multiple terminals and at least one base station configured to communicate with the terminals. The base station is operative to obtain channel vectors for respective ones of the terminals, to select a subset of the terminals based on magnitudes of the respective channel vectors, to compute a precoding matrix using the channel vectors of the selected subset of terminals, and to utilize the preceding matrix to control transmission to the selected subset of terminals. The system may be, for example, a time-division duplex (TDD) multi-user MIMO system in which the multiple terminals comprise autonomous single-antenna terminals.

Abstract: 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.