Ethernet Message Time Stamp Validation Using Local Clock Comparison
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Solution Overview
Problem
Current Ethernet time synchronization protocols, such as IEEE 802.1AS and PTP, do not provide a reliable method to validate the integrity of time stamps in Ethernet messages, which can lead to incorrect or falsified time information, especially in critical applications like automated driving where accurate time synchronization is essential.
Innovation Solution
A method and control unit that detect and replace incorrect time stamps in Ethernet messages by determining a time difference between the global time stamp and a local clock time, using the local time if the difference exceeds a limit value, ensuring reliable processing and forwarding of messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Ethernet time synchronization protocols (IEEE 802.1AS, PTP) are used to synchronize time across control units, then time synchronization is achieved, but the integrity and reliability of time stamps cannot be validated
Solution Approach 1:
The control unit continuously monitors the time stamps received from Ethernet messages and compares them against its local clock time. This feedback mechanism allows the system to detect when a time stamp does not correspond to the expected time range, enabling validation of time stamp integrity while maintaining synchronization.
Solution Approach 2:
The patent replaces the trust-based mechanical time synchronization system with a verification system that uses local clock comparison. Instead of blindly accepting time stamps from the network, the control unit substitutes the verification process with local time reference comparison to detect falsified or incorrect time stamps.
2Productivity
If time stamps are used to synchronize data from multiple sensors and control units, then coordinated processing is enabled, but incorrect or falsified time information can compromise data accuracy
Solution Approach 1:
The control unit receives time stamps from multiple sensors and control units, then provides feedback by comparing each timestamp against its local clock. This allows the system to maintain high data processing efficiency while ensuring time measurement accuracy by rejecting outliers that do not match the expected time range.
3Reliability
If the control unit validates each time stamp by comparing with local clock time, then time stamp integrity is improved, but processing complexity increases
Solution Approach 1:
The control unit uses its own integrated local clock to validate incoming time stamps, making the validation process self-service rather than requiring external validation infrastructure. This approach improves time stamp reliability while minimizing added complexity by leveraging the control unit's existing timekeeping capability.
Data Source
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AI summary
The invention relates to a method for identifying an incorrect time stamp (5) of an Ethernet message (4), in which the following steps are carried out: an Ethernet message (4) with a time stamp (5) is received by a control unit (2) of a motor vehicle (1); a time difference between a global time (6) of the time stamp (5) and a local time (9) of a clock (8) of the control unit (2) is determined; and the time stamp (5) of the Ethernet message (4) is identifed as being incorrect. If the time stamp (5) is identified as being incorrect, the global time (6) of the time stamp (5) is replaced by the local time (6) of the clock (8) of the control unit (2).