Crosstalk Control Device for DSL Line Transient Noise
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Solution Overview
Problem
Current solutions for mitigating transient crosstalk between DSL lines, such as FEC, retransmission mechanisms, and Dynamic Rate Adaptation, are insufficient in reducing errors during the transition phase when a new subscriber line is powered on, as they either fail to correct lengthy noise bursts or permanently affect the throughput of victim lines.
Innovation Solution
A crosstalk controlling device that delays the start-up of a new subscriber line until active lines have successfully executed a crosstalk anticipation algorithm, allowing them to prepare for the upcoming crosstalk, and then enables the new line to start up, with optional features including recalculating bit rates or crosstalk cancellation coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If FEC and retransmission mechanisms are used to correct errors, then error correction capability is improved, but they fail to effectively handle lengthy transient crosstalk noise bursts that last several minutes
Solution Approach 1:
The system performs preliminary rate adaptation or crosstalk cancellation coefficient calculation on victim lines before the new subscriber line becomes fully operational. This advance preparation allows the victim lines to be pre-configured to handle the upcoming transient crosstalk, reducing errors during the transition phase when FEC and retransmission mechanisms would otherwise be insufficient
2Object-affected harmful factors
If DRA or SRA is used to reduce bit rates on victim lines, then crosstalk noise tolerance is improved, but the throughput of victim lines is permanently affected
Solution Approach 1:
The system dynamically adjusts the bit rates or crosstalk cancellation coefficients of victim lines temporarily during the transient phase when a new subscriber line is becoming operational. After the new line is successfully established and the transient crosstalk period ends, the system restores the original higher bit rates, thus maintaining high throughput while providing temporary noise tolerance during the critical transition period
Solution Approach 2:
The rate adaptation or crosstalk cancellation coefficient calculation is performed periodically or temporarily only during the transient phase, rather than continuously. This allows the system to maintain high throughput during stable operation while providing protective measures only when needed during line transitions
3Speed
If the new subscriber line is allowed to start up immediately, then service deployment speed is improved, but transient crosstalk generates large amounts of errors on other subscriber lines
Solution Approach 1:
The system executes rate adaptation or crosstalk cancellation coefficient calculation on victim lines before allowing the new subscriber line to start up. This preliminary preparation ensures that victim lines are ready to handle the upcoming crosstalk, enabling the new line to be deployed quickly without causing excessive errors on existing lines
4Reliability
If the start-up of the new subscriber line is delayed, then crosstalk errors on victim lines are reduced, but service deployment time increases
Solution Approach 1:
The system performs rate adaptation or crosstalk cancellation coefficient calculation as a brief preliminary step that does not require significant time delay. This allows the new subscriber line to start up almost immediately after the quick preparation, minimizing deployment time while still protecting victim lines from transient crosstalk errors
Data Source
Figure 1
AI summary
The crosstalk controlling device (121) according to the invention receives information indicative for a newly upcoming subscriber line (162), and thereupon triggers a crosstalk anticipating algorithm on other, active subscriber lines (161). The crosstalk controlling device (121) enables the newly upcoming subscriber line (162) to become active only after successful crosstalk anticipation on at least part of the other, active subscriber lines (161).