Downstream Vectoring Gain Adaptation During Precoder Updates

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Solution Overview

Problem

Crosstalk interference becomes significant compared to direct channel gains in non-diagonally dominant channel matrices, leading to power spectral density mask violations and receiver misalignment in DSL communication systems, especially with broader transmit spectra.

Innovation Solution

A method and apparatus for controlling communications over subscriber lines using precoders for crosstalk pre-compensation, involving signal adjustment information to compensate for channel biases during precoder updates, and time-coordinating these updates with receiver adjustments to maintain system stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If signal scaling is applied to counter-balance excessive signal power from crosstalk pre-compensation, then transmit power spectral density mask compliance is improved, but channel equalization accuracy deteriorates due to induced channel bias

Engineering Contradiction:

Improvetransmit power spectral density mask complianceVSAvoidchannel equalization accuracy

Core Design Contradiction:

Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by proactively compensating for channel bias before it causes decoding errors. The transmitter determines signal compensation factors in advance to counter-balance the channel bias induced by signal scaling, and transmits these factors to the receiver before the precoder update takes effect, ensuring continuous accurate signal detection

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by having the transmitter determine signal compensation factors based on the channel bias induced by signal scaling, then transmitting these factors to the receiver. The receiver uses these feedback factors to adjust its signal detection, creating a closed-loop system that maintains channel equalization accuracy despite signal scaling operations

Inventive Principle:

Principle #23Feedback

2Reliability

If precoder update is performed to adapt to channel changes, then crosstalk mitigation performance is improved, but receiver tracking stability deteriorates due to sudden channel equalization bias

Engineering Contradiction:

Improvecrosstalk mitigation performanceVSAvoidreceiver tracking stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary action by transmitting signal compensation factors to the receiver before the precoder update takes effect. This allows the receiver to prepare its tracking algorithms in advance, preventing loss of track when the channel equalization bias suddenly changes due to precoder update

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent provides beforehand cushioning by sending signal compensation factors ahead of time to the receiver. This cushioning information protects the receiver tracking stability against the adverse effects of sudden channel bias changes caused by precoder updates, ensuring smooth transition without decoding errors

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Measurement precision

If signal compensation factors are transmitted to receivers, then channel bias compensation is improved, but system complexity increases due to additional signaling overhead

Engineering Contradiction:

Improvechannel bias compensation accuracyVSAvoidsystem signaling overhead

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies local quality by transmitting signal compensation factors selectively only to receivers that are affected by channel bias from precoder updates. Not all receivers receive these factors, which reduces the overall signaling overhead while maintaining channel bias compensation accuracy for those who need it

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS12627331B2Gain adaptation for downstream vectoring systems

Publication Date: 2026.05.12 ALCATEL LUCENT SA

AI summary

In accordance with an embodiment, the method includes detecting an update event whereupon a precoder needs to be updated, sending signal adjustment information to a receiver remotely coupled to a subscriber line out of the plurality of subscriber lines indicative of a signal compensation factor to be applied to a receive communication signal to compensate for a channel bias caused by the scheduled precoder update, and time-coordinating the precoder update with the enforcement of the signal compensation factor at the receiver.