9. An apparatus comprising:
an access node configured to control crosstalk between an activating channel"
associated with a first network terminal of a communication system and a plurality of active
channels associated with respective other network terminals of the communication system;
5 wherein the access node further comprises:
a plurality of transceivers;
a vector control entity; and
a vectoring signal processing module;
wherein a control signal sent by the first network terminal over the activating
10 channel in a designated phase of an initialization process of the first network terminal is detected
by one of the transceivers, an error signal is determined from the detected control signal, and the
error signal is correlated with one or more corresponding signals sent by respective ones of the
other network terminals over the active channels;
where the control signal sent by the first network terminal comprises a value that
15 is selected by the first network terminal from a set of two or more values and prior to said
detection the particular selected value is unknown to the access node;
wherein the vector control entity estimates crosstalk from one or more of the
active channels into the activating channel based on the correlation; and
wherein the vectoring signal processing module is configured to control the
20 estimated crosstalk.
10. A communication system comprising the access node of claim 9.