Mitigating Disconnect Events in Vectoring DSL Systems
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Solution Overview
Problem
Vectoring-based DSL systems experience disconnect events, leading to increased noise and retrain issues due to unexpected line disconnections, which impair system performance and cause service interruptions.
Innovation Solution
A method and system for detecting signal losses and changes in crosstalk coefficients in DSLAM, determining the magnitude and location of disconnect events, and taking actions to mitigate their impact without triggering retrain, including fast tracking and adjusting precoding coefficients to reduce noise levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vectoring technology is implemented to cancel FEXT and maximize DSL system performance, then system performance and capacity are improved, but disconnect events cause noise increase and service interruption
Solution Approach 1:
The system performs preliminary detection of disconnect events by monitoring changes in downstream crosstalk coefficients before full service interruption occurs. By detecting the disconnect event early and determining its location (CO side or CPE side), the system can take preliminary mitigation actions to prevent noise increase and service retrain.
Solution Approach 2:
The system continuously monitors downstream crosstalk coefficients and uses this feedback to detect disconnect events. The monitoring of crosstalk coefficient changes provides real-time information about system state, enabling the system to respond dynamically to disconnect events and maintain service continuity.
2Reliability
If disconnect events are detected and mitigation actions are taken, then service interruption is reduced, but system complexity increases
Solution Approach 1:
The system extracts and isolates the disconnect event detection function from the overall DSLAM processing. By separately monitoring downstream crosstalk coefficients and identifying disconnect events as distinct phenomena, the system can handle mitigation logic independently, reducing the complexity burden on the main processing path.
Solution Approach 2:
The system applies different mitigation strategies based on the local characteristics of the disconnect event. By determining whether the disconnect occurred at the CO side or CPE side, the system can apply targeted actions specific to each scenario, avoiding the need for complex universal mitigation logic.
3Reliability
If retrain is avoided by implementing fast tracking and precoding coefficient adjustment, then service interruption is prevented, but processing time and computational load increase
Solution Approach 1:
The system dynamically adjusts precoding coefficients based on real-time detection of disconnect events. By making the precoding coefficients adaptive rather than static, the system can quickly respond to changing channel conditions without requiring full retrain, reducing processing time while maintaining service continuity.
Data Source
AI summary
There is provided mitigation of disconnect events in a vectoring based digital subscriber line, DSL, system. A method performed by a digital subscriber line access multiplexer, DSLAM, comprises detecting a loss of signal or disconnect event of a line in a vectored group of DSL lines, the loss of signal or disconnect event causing a negative impact on the DSL system. The method further comprises detecting a change in at least one downstream, DS, crosstalk coefficient of at least one line in said vectored group of DSL lines. The method further comprises determining a magnitude of said change. The method further comprises determining where the loss of signal or disconnect event has occurred by processing precoding coefficients of the vectored group of DSL lines. The method further comprises determining, on basis of the determined magnitude and where the loss of signal or disconnect event has occurred, an action to be performed by the DSLAM so as to mitigate for said negative impact.