VDSL Modem Bit Stream Resynchronization

Solution Overview

Problem

Existing methods for dynamically varying transmit power in VDSL modems to minimize interference in wired communications networks are inefficient, as they often result in synchronization loss and slow recovery in other devices due to sudden power changes and slow switching mechanisms.

Innovation Solution

A method for rapidly resynchronizing communication channels by adjusting bit streams based on synchronization loss indications, using bit-loading adjustments and constellation size changes to minimize power changes and maintain network stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If transmit power is dynamically varied to minimize interference, then interference with other devices is reduced, but synchronization is lost and devices must re-train

Engineering Contradiction:

ImproveinterferenceVSAvoidsynchronization

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies preliminary action by notifying other devices of upcoming power changes before they occur. The notifying device sends a notification message containing power change information (time, magnitude, direction) to affected devices, allowing them to prepare and maintain synchronization without losing sync when power levels change.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses feedback mechanisms where affected devices monitor power spectral density and detect when power changes occur. The system continuously monitors and adjusts based on feedback about actual power levels and synchronization status, allowing dynamic adaptation while maintaining communication reliability.

Inventive Principle:

Principle #23Feedback

2Adaptability or versatility

If power changes are made quickly to adapt to bandwidth demands and regulatory restrictions, then adaptability is improved, but synchronization loss occurs and recovery is slow

Engineering Contradiction:

Improvepower adaptationVSAvoidsynchronization recovery time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by notifying other devices of upcoming power changes before they occur. The notifying device sends a notification message containing power change information (time, magnitude, direction) to affected devices, allowing them to prepare and maintain synchronization without losing sync when power levels change.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements dynamic power adjustment where devices can quickly change transmit power levels based on bandwidth demands and regulatory requirements. The system dynamically modifies power spectral density while using notifications to prevent synchronization loss, enabling rapid adaptation without the traditional slow re-training process.

Inventive Principle:

Principle #15Dynamics

3Object-affected harmful factors

If full power mode is switched to no power mode to minimize interference, then interference is reduced, but other modems lose synchronization and must re-train

Engineering Contradiction:

ImproveinterferenceVSAvoidcommunication efficiency

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent applies preliminary action by notifying other devices of upcoming power changes before they occur. The notifying device sends a notification message containing power change information (time, magnitude, direction) to affected devices, allowing them to prepare and maintain synchronization without losing sync when power levels change.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies partial action by allowing modems to operate in intermediate power states rather than switching between full power and no power. Devices can adjust power spectral density to partial levels that reduce interference while maintaining sufficient signal strength to prevent synchronization loss, avoiding the need for complete power shutdowns.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS7787558B2Rapid re-synchronization of communication channels

Publication Date: 2010.08.31 TEXAS INSTRUMENTS INC

AI summary

A method of synchronizing a receiver with a transmitter. The method includes determining number of bits, j, for adjusting a bit stream, where the bit stream is generated from n tones and is dividable into codewords having a codeword length of N bytes, and the number of bits for adjusting the bit stream is determined based upon n and N. The method includes detecting a loss of synchronization indication. In response to detection of the loss of synchronization indication, the method includes adjusting the bit stream by j bits. The method includes determining whether synchronization has been regained. When synchronization has not been regained, the method includes adjusting the bit stream again by j bits. When synchronization has been regained, the method includes terminating adjustment of the bit stream.