DSL Vectoring Precoder Update via Partial Channel Estimation
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Solution Overview
Problem
In DSL vectoring systems, Disorderly Shutdown Events (DSEs) lead to significant Signal to Noise Ratio (SNR) drops and potential retraining of other lines due to outdated precoders, which is not desired as it causes interruptions in services like IP-TV, and current standards conflict on how to manage such events.
Innovation Solution
A method for fast channel tracking that involves error sample requests and feedback through a robust embedded operations channel (ROC) to quickly update the precoder, estimating only the changed channel coefficients associated with the affected line, allowing for rapid adaptation without retraining other lines in the vectored group.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If transmission is continued on the line subject to DSE to avoid retraining, then service interruption is minimized, but SNR drops significantly and other lines may retrain due to outdated precoder
Solution Approach 1:
The system performs preliminary channel tracking by continuously monitoring error samples from the affected line even after DSE occurs. This allows the precoder to be updated with current channel characteristics before other lines experience significant SNR degradation, preventing retraining and maintaining service continuity.
Solution Approach 2:
The system uses error samples from the affected line as feedback to continuously update the channel estimate and precoder. This feedback mechanism ensures the precoder remains optimized for current channel conditions despite the disorderly shutdown, preventing SNR drops on other lines and avoiding retraining events.
2Productivity
If precoder is not updated after DSE to maintain original channel optimization, then computation is reduced, but SNR drops and other lines retrain causing service interruption
Solution Approach 1:
The system performs preliminary channel tracking by continuously monitoring error samples from the affected line even after DSE occurs. This allows the precoder to be updated with current channel characteristics before other lines experience significant SNR degradation, preventing retraining and maintaining service continuity.
Solution Approach 2:
The system uses error samples from the affected line as feedback to continuously update the channel estimate and precoder. This feedback mechanism ensures the precoder remains optimized for current channel conditions despite the disorderly shutdown, preventing SNR drops on other lines and avoiding retraining events.
3Measurement precision
If full channel estimation is performed after DSE to update precoder accurately, then precoder optimization is improved, but processing time and complexity increase significantly
Solution Approach 1:
The system extracts only the necessary information for channel tracking from error samples after DSE, rather than performing complete channel estimation. By utilizing the existing channel knowledge and updating only the affected components with new error sample information, the system achieves accurate precoder updates with minimal processing time.
Solution Approach 2:
The system performs partial channel estimation by using only error samples from the affected line to update the channel characteristics, rather than performing full channel estimation on all lines. This partial action is sufficient to maintain precoder accuracy for the vectored group while significantly reducing processing time and complexity.
Data Source
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AI summary
Method and arrangement in a Vectoring Control Entity, VCE, for handling disorderly events in a Digital Subscriber Line, DSL, system. The method involves a number of actions, to be performed when a disorderly event occurs on line m in a vectored group of DSL lines, and the transmission on line m is continued. The method comprises obtaining error samples from Customer Premises Equipments, CPEs, connected to other lines in the vectored group of DSL lines. The method further comprises calculating a partial channel estimate comprising an estimate of the channel coefficients changed due to the disorderly event, based on the error samples. The arrangement is adapted to enable the performance of the above described method.