V2X Time Synchronization for Incorrect Road User System Clocks
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Solution Overview
Problem
Existing vehicle-to-X (V2X) communication systems face challenges in accurately determining and synchronizing system time among road users, which is crucial for reliable information exchange, especially in automated vehicles, due to potential discrepancies in time bases that can lead to safety-critical issues.
Innovation Solution
A method and apparatus for road users to receive and compare system time information from other users, correcting discrepancies exceeding a limit value to ensure time synchronization, using global satellite navigation signals and sensor data for accurate time alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If V2X messages are transmitted with time information from each road user's system time, then the information exchange between road users is enabled, but time discrepancies may occur leading to incorrect sequencing and safety-critical issues
Solution Approach 1:
The system implements a feedback mechanism where road users compare their local system time with the time information received from V2X messages. When a time discrepancy exceeding a threshold is detected, the system generates feedback signals to correct the time error. This continuous feedback loop ensures that time synchronization is maintained without requiring centralized control, thereby improving both reliability and measurement precision.
Solution Approach 2:
Each road user autonomously performs time synchronization by comparing their own system time with received V2X message timestamps. The correction process is self-service oriented, where each participant independently detects and corrects time discrepancies using their own processing units, eliminating the need for external time authority intervention and enhancing both reliability and precision.
2Measurement precision
If the system time is continuously updated using GNSS time signals, then the time basis accuracy is improved, but the system complexity and dependency on external signals increases
Solution Approach 1:
The patent introduces an intermediary mechanism where road users exchange time information through V2X messages as a mediator between their local systems and the external GNSS time source. This intermediary approach allows indirect time synchronization without requiring direct GNSS signal processing, reducing system complexity while maintaining accuracy through peer-to-peer time verification.
Solution Approach 2:
The V2X communication system serves multiple functions: it enables information exchange between road users, provides time synchronization, and facilitates error detection and correction. By making the communication system multi-functional, the patent avoids adding separate dedicated time synchronization hardware, thereby improving time basis accuracy without proportionally increasing system complexity.
3Loss of time
If road users independently determine and correct their own system time, then the response time is reduced, but the measurement precision may be compromised due to lack of centralized coordination
Solution Approach 1:
The system merges individual road users' time correction actions into a coordinated network-wide synchronization process. By combining the independent time determination actions of multiple road users through V2X communication, the system achieves both rapid local response and improved overall precision through collective verification and cross-validation of time corrections.
Data Source
AI summary
A method for execution by an apparatus belonging to a first road user comprises receiving a vehicle-to-X (V2X) message by a V2X communication apparatus, wherein the V2X message comprises time information for determining a system time of a second road user, determining a system time of the first road user, comparing the system times of the first road user and the second road user, wherein, if a determined discrepancy between the system times of the first road user and the second road user is equal to or exceeds a limit value, it is determined whether the system time of the first road user or of the second road user is incorrect, and correcting the system time of the first road user if the system time of the first road user is incorrect, or outputting a control signal for communicating that the system time of the second road user is incorrect.