Gain adaptation for downstream vectoring systems

A communication controller for controlling communications over a plurality of subscriber lines, the communications making use of communication signals that are jointly processed through a linear precoder for crosstalk pre-compensation, the communication controller comprising:

• at least one processor;
• and
• at least at least one memory including computer program code,
• the at least one memory and the computer program code configured to, with the at least one processor, cause the communication controller
• to update one or more coupling coefficients of the linear precoder for mitigating crosstalk from a subscriber line into one or more victim lines, to send signal adjustment information to a receiver remotely coupled to the subscriber line indicative of a signal compensation factor to be applied to a receive communication signal to compensate for a channel equalization bias caused by crosstalk pre-compensation signals superimposed over the one or more victim lines and corresponding to the respective one or more updated coupling coefficients of the linear precoder, after joint processing of the communication signals through an updated precoder, the updated precoder being the linear precoder after a precoder update, and to time-coordinate the precoder update with an enforcement of the signal compensation factor at the receiver, and the sending the signal adjustment information to the receiver being in response to a determination that the precoder update results in the channel equalization bias at the receiver.

A communication controller for controlling a communication over a subscriber line out of a plurality of subscriber lines, the communications over the plurality of subscriber lines making use of communication signals that are jointly processed through a linear precoder for crosstalk pre-compensation, the communication controller comprising:

• at least one processor;
• and
• at least one memory including computer program code,
• the at least one memory and the computer program code configured to, with the at least one processor, cause the communication controller to
• receive signal adjustment information from a transmitter remotely coupled to the subscriber line indicative of a signal compensation factor to be applied to a receive communication signal to compensate for a channel equalization bias caused by crosstalk pre-compensation signals superimposed over one or more victim lines and corresponding to respective one or more updated coupling coefficients of the linear precoder after joint processing of the communication signals through an updated precoder, the updated precoder being the linear precoder after a precoder update,
• send adjusted bit loading values in response to receiving the signal adjustment information,
• time-coordinate an enforcement of the signal compensation factor with a corresponding transmit signal scaling and the linear precoder update from a data symbol index received from the transmitter, and
• compensate for the channel equalization bias resulting from the linear precoder update based on enforcing the signal compensation factor with the corresponding transmit signal scaling and the linear precoder update.

A communication controller for controlling a communication over a subscriber line out of a plurality of subscriber lines, the communications over the plurality of subscriber lines making use of communication signals that are jointly processed through a linear precoder for crosstalk pre-compensation, wherein

• the communication controller is configured to receive signal adjustment information from a transmitter remotely coupled to the subscriber line indicative of a signal compensation factor to be applied to a receive communication signal to compensate for a channel equalization bias caused at least by a corresponding transmit signal scaling to be applied at the transmitter to scale down a transmit communication signal for conformance to a transmit Power Spectral Density (PSD) mask after joint processing of the communication signals through an updated linear precoder, the updated linear precoder being the linear precoder after a linear precoder update, and
• the communication controller is configured to
• time-coordinate an enforcement of the signal compensation factor with the corresponding transmit signal scaling and the linear precoder update, and
• compensate for the channel equalization bias resulting from the linear precoder updated based on the enforcement of the signal compensation factor with the corresponding transmit signal scaling and the linear precoder update,
• wherein the communication controller is configured to time-coordinate the enforcement of the signal compensation factor with the corresponding transmit signal scaling and the linear precoder update by sending an acknowledgment signal to the transmitter.