Clock Distribution Offset Compensation for Seamless Switching

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Solution Overview

Problem

Clock distribution apparatuses in communication networks face challenges when switching between different transmission paths, leading to phase or time jumps that can disrupt communication and cause downstream devices to lose connection due to unmanaged phase offset differences.

Innovation Solution

A method and apparatus for calculating and compensating the offset difference between clock signals from different transmission paths, allowing the clock distribution apparatus to smoothly switch between clock sources by adjusting the local clock and adding offset information to the clock signal, thereby reducing the impact on downstream devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the clock distribution apparatus switches between different transmission paths to maintain network connectivity, then the reliability of clock signal distribution is improved, but phase jumps occur causing downstream apparatuses to lose connection

Engineering Contradiction:
Improveclock signal distribution reliabilityVSAvoidphase jump impact on downstream apparatuses
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary actions by calculating and compensating for phase offsets before the actual clock source switching occurs. The offset between the current and candidate clock sources is measured in advance, and compensation values are pre-computed and applied to ensure seamless transition without phase jumps that would disrupt downstream apparatuses.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

A phase offset compensation mechanism acts as an intermediary between different clock sources and the downstream apparatuses. This intermediary calculates the phase difference between clock sources and applies appropriate compensation to the switched clock signal, thereby isolating downstream apparatuses from the harmful phase jumps caused by switching.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If the clock distribution apparatus uses multiple transmission paths for redundancy, then the stability of clock signal distribution is improved, but the complexity of managing offset differences increases

Engineering Contradiction:
Improveclock signal distribution stabilityVSAvoidoffset management complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The system implements feedback by continuously monitoring the phase offset between multiple clock sources and automatically adjusting compensation values. The offset calculation unit regularly measures phase differences, and this feedback information is used to dynamically update compensation parameters, enabling the system to adapt to changing conditions without manual intervention while maintaining stability.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system manages complexity by dynamically changing compensation parameters based on the active clock source combination. When switching between different transmission paths, the system adjusts the offset compensation parameters accordingly, allowing flexible management of multiple paths without requiring complex permanent configurations for each possible path combination.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3918731B1Clock distribution method and apparatus in network
Publication Date: 2024.10.23 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP3918731B1 patent drawingFigure 1
  • EP3918731B1 patent drawingFigure 2
  • EP3918731B1 patent drawingFigure 3~4

AI summary

The present disclosure relates to a clock distribution method and apparatus in a network. A method performed at a clock distribution apparatus comprises: receiving a first clock signal; receiving a second clock signal; calculating an offset difference between the first clock signal and the second clock signal; compensating the second clock signal, based on the offset difference; and outputting a clock signal, based on the compensated second clock signal. The offset difference between the first clock signal and the second clock signal is calculated and used to compensate the second clock signal. The switching of the clock signal will be smoother for the downstream.