Grandmaster Reselection in Time Synchronization After Reconnection

Solution Overview

Problem

The grandmaster arbitration process in existing time-synchronization systems using the Best Master Clock Algorithm (BMCA) can cause time-synchronization abnormalities when the grandmaster device is disconnected and reconnected, particularly in networks with a large number of devices, leading to time discontinuities and synchronization issues.

Innovation Solution

A time-synchronization device that includes a grandmaster selector to identify and select a new grandmaster without performing the BMCA when a disconnected device reconnects, using stored identification information to determine if the reconnected device is the previous grandmaster, thereby avoiding the BMCA process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the grandmaster arbitration process using BMCA is performed when a device reconnects, then the system ensures proper grandmaster selection through standardized procedures, but time-synchronization abnormalities occur due to time discontinuities and large time differences among devices

Engineering Contradiction:

Improvegrandmaster selection reliabilityVSAvoidtime synchronization precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The system performs preliminary actions by storing identification information of the detached grandmaster before disconnection occurs. When the grandmaster reconnects, this pre-stored information enables immediate recognition and avoidance of the BMCA arbitration process, preventing time discontinuities before they can occur.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses stored identification information (a form of data copy) to recognize the returning grandmaster device. This copy of the grandmaster's ID allows the system to identify the device without requiring full arbitration, maintaining synchronization continuity while ensuring proper grandmaster selection.

Inventive Principle:

Principle #26Copying

2Adaptability or versatility

If the BMCA grandmaster arbitration process is performed repeatedly when grandmaster devices disconnect and reconnect, then the system follows standardized procedures for grandmaster selection, but the time differences among devices increase leading to time-synchronization abnormalities

Engineering Contradiction:

Improvegrandmaster replacement adaptabilityVSAvoidtime difference accumulation

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The system performs preliminary actions by storing identification information of the detached grandmaster before disconnection occurs. When the grandmaster reconnects, this pre-stored information enables immediate recognition and avoidance of the BMCA arbitration process, preventing time discontinuities before they can occur.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system skips the time-consuming BMCA arbitration process by using stored identification information to immediately recognize the returning grandmaster. This allows the system to rush through the reconnection event without performing unnecessary arbitration, thereby minimizing time difference accumulation.

Inventive Principle:

Principle #21Skipping (Rushing through)

3Reliability

If the BMCA priority information is compared repeatedly during grandmaster arbitration, then the system ensures proper grandmaster selection, but the process takes longer time as the number of devices increases causing larger time differences

Engineering Contradiction:

Improvegrandmaster selection reliabilityVSAvoidgrandmaster selection speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system extracts only the essential identification information from the grandmaster device and stores it locally. This extracted ID is sufficient for recognition purposes, eliminating the need to repeatedly compare comprehensive BMCA priority information from all devices during reconnection events.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The system performs preliminary actions by storing identification information of the detached grandmaster before disconnection occurs. When the grandmaster reconnects, this pre-stored information enables immediate recognition and avoidance of the BMCA arbitration process, preventing time discontinuities before they can occur.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20260012276A1Time-synchronization device, time-synchronization system, and program

Publication Date: 2026.01.08 MITSUBISHI ELECTRIC CORP

AI summary

In a time-synchronization device, a grandmaster selector selects a first time-synchronization device as a grandmaster by performing a grandmaster arbitration process. A time synchronizer performs time synchronization as the grandmaster when the first time-synchronization device is selected as the grandmaster and performs time synchronization as a follower device when the first time-synchronization device is not selected as the grandmaster. An identification information storage stores identification information for identifying the first time-synchronization device selected as the grandmaster. In a time-synchronization device, when the first time-synchronization device is detached, the grandmaster selector selects a second time-synchronization device as a new grandmaster by performing the grandmaster arbitration process. When a new time-synchronization device is connected and the grandmaster selector identifies the new time-synchronization device as the detached first time-synchronization device based on the identification information, the grandmaster selector reselects the first time-synchronization device as the grandmaster without performing the grandmaster arbitration process.