Power adaptation avoidance during crosstalk measurements
In one embodiment, the access node includes a vectoring control unit for estimating crosstalk coefficients between a set of subscriber lines based on crosstalk measurements carried out over the set of subscriber lines during a crosstalk measurement phase, and a vectoring processing unit for jointly processing, for crosstalk mitigation, signals to be transmitted over, or received from, the set of subscriber lines based on the estimated crosstalk coefficients. The access node further includes a controller configured to either postpone the execution of power adaptation over a particular line out of the set of subscriber lines after the completion of the crosstalk measurement phase, or to postpone the crosstalk measurement phase after the completion of power adaptation over the particular line.
1. An access node configured to connect a plurality of subscriber devices through a loop plant, the access node comprising:
a memory having a computer readable instructions stored therein; and
a processor configured to execute the computer-readable instructions to,
estimate crosstalk coefficients between a set of subscriber lines based on crosstalk measurements carried out over the set of subscriber lines during a crosstalk measurement phase;
jointly process signals to be transmitted over, or received from, the set of subscriber lines based on the estimated crosstalk coefficients to mitigate crosstalk;
receive a power adaptation command from at least one of the plurality of subscriber devices coupled to a subscriber line of the set of subscriber lines; and
control execution of the power adaptation command and the estimation of the crosstalk coefficients over at least one subscriber line from the set of subscriber lines such that the execution of the power adaptation command and the estimation of the crosstalk coefficients do not overlap, the processor being configured to perform the controlling by exchanging at least one of a negative acknowledgement signal in response to the received power adaptation command and a suspend signal.
2. The access node according to claim 1 , wherein
the power adaptation command is a command for adjusting a transmit power and a bit loading of at least one downstream carrier is adjusted over the subscriber line,
the digital signal processor is further configured to, upon receipt of the power adaptation command, issue the negative acknowledgment signal to the subscriber device if the crosstalk measurement phase is on-going, and
the negative acknowledgment signal includes an error code for allowing the at least one of the plurality subscriber devices to request the bit loading adjustment.
3. The access node according to claim 2 , wherein the negative acknowledgment signal includes a time value to wait before resuming a downstream power adaptation over the subscriber line.
4. The access node according to claim 1 , wherein the digital signal processor is further configured to issue, to the at least one of the plurality of subscriber devices, the suspend signal before the crosstalk measurement phase takes place for requesting the at least one of the plurality of subscriber devices to suspend the downstream power adaptation over the subscriber line, and for allowing the at least one of the plurality of subscriber devices to request a bit loading adjustment.
5. The access node according to claim 4 , wherein the suspend signal includes a time value to wait before resuming the downstream power adaptation over the subscriber line.
6. The access node according to claim 4 , wherein the digital signal processor is further configured to issue, to the at least one of the plurality of subscriber devices, a resume signal after the crosstalk measurement phase, for allowing the at least one of the plurality of subscriber devices to resume the downstream power adaptation over the subscriber line.
7. The access node according to claim 1 , wherein the access node is a Digital Subscriber Line Access Multiplexer.
8. A subscriber device for connecting to an access node through a loop plant, the subscriber device comprising:
a memory having computer readable instructions stored thereon; and
a processor configured to execute the computer-readable instructions to,
connect to the access node through a subscriber line of the loop plant,
issue a power adaptation command to the access node for adjusting a transmit power and a bit loading of at least one downstream carrier over the subscriber line,
receive a negative acknowledgment signal from the access node if a crosstalk measurement phase is on-going over one or more subscriber lines, the negative acknowledgment signal including an error code for allowing the subscriber device to request a bit loading adjustment, and thereupon to issue another command to the access node for adjusting the bit loading of the at least one downstream carrier without altering the respective carrier gain.
9. The subscriber device according to claim 8 , wherein the negative acknowledgment signal comprises a time value,
and wherein the subscriber device is further configured to wait for the time value to expire before resuming downstream power adaptation over the subscriber line.
10. A method for connecting a plurality of subscriber devices through a loop plant, and the method comprising:
estimating crosstalk coefficients between a set of subscriber lines based on crosstalk measurements carried out over the set of subscriber lines during a crosstalk measurement phase;
processing, for crosstalk mitigation, signals to be transmitted over, or received from, the set of subscriber lines based on the estimated crosstalk coefficients;
receiving a power adaptation command from at least one of the plurality of subscriber devices coupled to one or more subscriber lines of the set of subscriber lines; and
exchanging at least one of a negative acknowledgement signal in response to the received power adaptation command and a suspend signal, to control an execution of the power adaptation command and the estimation of the crosstalk coefficients over at least one a subscriber line from the set of subscriber lines such that the execution of the power adaptation command and the estimation of the crosstalk coefficients do not overlap.