Vectored DSL Alien Interference Cancellation
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Solution Overview
Problem
Vectored DSL systems struggle to effectively cancel alien interference from sources outside the system, such as RFI and electrical noise, which reduces performance gains and limits the data transmission rates.
Innovation Solution
The use of inactive lines and common-mode voltage signals to generate pseudo signals, which are processed to identify and integrate alien interference into the FEXT cancellation coefficients matrix, allowing for the reduction or elimination of correlated alien interference affecting active DSL lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vectored DSL systems use traditional FEXT cancellation methods, then in-domain crosstalk is removed, but correlated alien interference from external sources remains and reduces performance
Solution Approach 1:
The patent collects pseudo signals from inactive lines that contain alien interference, processes these signals through the vectoring engine to extract alien interference characteristics, and then uses this extracted information to cancel the harmful alien interference from active lines. This converts the previously useless inactive lines into a beneficial resource for interference cancellation.
Solution Approach 2:
The vectoring engine is extended to perform multiple functions: it continues to cancel in-domain FEXT from active lines while simultaneously processing pseudo signals from inactive lines to cancel correlated alien interference. This multi-functional approach allows a single system component to address multiple interference sources.
2Reliability
If inactive lines are used to collect pseudo signals for alien interference cancellation, then alien interference removal capability is improved, but system complexity increases
Solution Approach 1:
The system uses its own inactive lines as the source of pseudo signals containing alien interference, rather than requiring external monitoring equipment or additional hardware. The vectoring engine processes these internally-generated pseudo signals to extract and cancel alien interference, making the system self-sufficient.
Solution Approach 2:
Previously discarded inactive lines that were considered useless for data transmission are now recovered and utilized as a resource for collecting pseudo signals. These lines are repurposed to provide alien interference information that enhances the performance of active transmission lines.
3Productivity
If correlated alien interference is integrated into FEXT cancellation coefficients, then data transmission rates improve, but processing requirements increase
Solution Approach 1:
The system performs preliminary processing of pseudo signals from inactive lines during training periods to extract alien interference characteristics and integrate them into the FEXT cancellation coefficient matrix. This preliminary action prepares the interference cancellation parameters in advance, allowing faster data transmission during active communication periods without continuous heavy processing.
Data Source
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AI summary
A vectored DSL system reduces or eliminates correlated alien interference in active DSL lines in the vectored system by collecting pseudo signals from inactive lines that do not carry upstream DSL transmissions and/or from common-mode voltage signals from active lines. The collected pseudo signals contain in-domain interference, such as FEXT interference from the active DSL lines in the vectored system, and correlated alien interference. After removing the in-domain interference from the pseudo signals, the remaining alien interference data can be used to generate FEXT cancellation coefficients or the like that are used in DSL vectoring to remove the correlated alien interference from upstream DSL user signals from the active DSL lines. The generated FEXT cancellation coefficients are used in a manner analogous to in- domain FEXT data collected from the active lines during training, tracking, etc. The vectored DSL system can include modems coupled to a private vectoring data routing apparatus to one or more vectoring modules The vectoring modules can employ vector processors that include processing units configured to process collected user data on the basis of all modems' data for a given DSL tone grouping, thus removing FEXT effects from the user data and returning vectored user data to the modems using the routing apparatus, which can be a specialized data transmission network utilizing one or more vector routers.