Packet-Based Timing Measurement for Clock Synchronization
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Solution Overview
Problem
Current clock synchronization protocols in packet-switched communication networks face inefficiencies and accuracy issues in handling timing-related messages, which can interfere with other communication and lead to detrimental errors in delay measurements.
Innovation Solution
A method where a slave communication device calculates the time of transit by inserting an approximate transmission time into a packet, with the physical layer portion adding a correction value to account for the actual transmission time, and the master device responds with a receipt time and correction value, allowing the slave device to calculate the delay without retaining actual transmission times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If timing-related messages are handled using standard protocols (NTP, PTP), then clock synchronization is achieved, but interference with other communication and measurement errors occur
Solution Approach 1:
The patent segments the timing message handling into separate priority queues (high-priority timing messages and low-priority data messages) within the network device. This segmentation allows timing-critical packets to be processed separately from general data traffic, eliminating interference while maintaining accurate delay measurements.
2Measurement precision
If actual transmission times are retained for delay calculation, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by having the transmitting device insert an approximate transmission timestamp into the timing message before sending it. The receiving device then calculates the delay using this pre-inserted timestamp and its receipt timestamp, eliminating the need for either device to retain actual transmission times while maintaining measurement precision.
3Speed
If timing messages are processed with high priority, then synchronization speed is improved, but error handling capability deteriorates
Solution Approach 1:
The patent applies local quality by implementing different quality of service (QoS) handling for different parts of the communication system. Network devices prioritize timing messages in their queues, while end devices use hardware timestamping for precise timing. This localized optimization maintains both speed and reliability without requiring system-wide changes.
Data Source
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AI summary
A slave communication device may transmit a packet to the master communication device, with the packet including a transmission time field and a correction field. The transmission time field may contain a value indicative of an approximate time of transmission of the packet by the slave communication device, and the correction field may contain a value indicative of a difference between the approximate time of transmission and an actual time of transmission of the packet by the slave communication device.