Slave Machine Time Control Apparatus for Network Congestion
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Solution Overview
Problem
High-capacity data transmission on networks causes network congestion, leading to non-uniform network delays, which complicates accurate frequency and time synchronization between a PTP master and slave machine using existing IEEE 1588 PTP methods.
Innovation Solution
A time control apparatus and method in the slave machine that calculates multiple time difference candidates and network delays based on various message transmission and reception times, selects the appropriate time difference based on these calculations, and adjusts the slave's time information to achieve high-precision synchronization with the master machine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-capacity data transmission is performed on the network, then network throughput is improved, but network delay becomes non-uniform due to congestion
Solution Approach 1:
The patent segments the time difference calculation into multiple candidates (first time difference candidate from Sync message, second time difference candidate from Delay_req/Delay_res messages). Each candidate is calculated independently and then selected based on network delay conditions, allowing the system to handle non-uniform network delays by choosing the most reliable calculation path.
Solution Approach 2:
The patent changes the parameter selection strategy by calculating multiple time difference candidates using different message types and selection criteria. Instead of relying on a single fixed calculation method, the system dynamically selects among multiple candidates based on measured network delay characteristics, adapting to varying network conditions.
2Reliability
If conventional IEEE 1588 PTP method is used for time synchronization, then time synchronization is achieved, but synchronization precision deteriorates under network congestion due to non-uniform delays
Solution Approach 1:
The patent implements feedback by measuring network delay characteristics and using this information to select the appropriate time difference candidate. The system continuously monitors network conditions and adjusts its time synchronization calculation approach accordingly, feeding back into the selection process to maintain precision under varying network conditions.
Solution Approach 2:
The patent introduces dynamic selection among multiple time difference calculation methods. Instead of using a static, fixed calculation approach, the system dynamically chooses which time difference candidate to use based on real-time network delay measurements, allowing it to adapt to changing network conditions and maintain synchronization precision.
3Measurement precision
If multiple time difference candidates are calculated and selected based on network delays, then synchronization precision is improved, but calculation complexity increases
Solution Approach 1:
The patent applies local quality by calculating time difference candidates using different message types (Sync, Delay_req, Delay_res) that have different characteristics and reliability under various network conditions. Each candidate is calculated with appropriate local assumptions about network delay uniformity, and the most suitable candidate is selected based on measured delay characteristics.
Data Source
AI summary
A time control apparatus provided in a slave machine and synchronizing time information with time information of a master machine connected over a network includes: calculation units respectively calculating time difference candidates of the slave machine with respect to the master machine and network delays indicative of an average of times necessary for communication of first and second messages over the network based on transmission and reception times of the first messages which are transmitted from the master machine and received using the slave machine and transmission and reception times of the second messages which are transmitted from the slave machine and received using the master machine; a selection unit selecting one of the calculated time difference candidates as a time difference based on the calculated network delays; and an adjustment unit adjusting the time information of the slave machine based on the selected time difference.