Vehicle Clock Synchronization via Latency Statistics
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Solution Overview
Problem
Existing vehicle-to-infrastructure (V2I) and vehicle-to-vehicle (V2V) communication systems face challenges in synchronizing messages without a common reference clock, particularly in scenarios where GPS or external clocks are unavailable, leading to processing and bandwidth inefficiencies.
Innovation Solution
A method for synchronizing clocks between vehicles and infrastructure elements by adjusting the clock based on differences between sent and received message timestamps, using statistical measures like average, standard deviation, or maximum latency to determine when to synchronize, allowing for timestamp assignment and vehicle component actuation without relying on external clocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS or external clocks are used for synchronization, then clock accuracy is improved, but system dependency on external infrastructure increases and processing overhead increases
Solution Approach 1:
The system performs self-synchronization by having vehicles exchange timestamps and calculate communication latencies autonomously without relying on external GPS or infrastructure clocks. Each vehicle acts as both client and server, mutually adjusting its clock based on received timestamps and calculated latencies, thereby eliminating external infrastructure dependency while maintaining synchronization accuracy.
Solution Approach 2:
Timestamps serve as intermediaries carrying time reference information between vehicles. By embedding sent_time and receipt_time stamps in exchanged messages, the system creates a portable time reference that enables synchronization without external infrastructure, with the timestamp acting as the mediating element that transfers timing information across the communication channel.
2Measurement precision
If frequent clock synchronization is performed, then timestamp accuracy is improved, but message bandwidth consumption increases and processing demands increase
Solution Approach 1:
The system implements feedback-based synchronization where vehicles monitor the stability of communication latency over time. By calculating statistical measures (average, standard deviation, maximum) of latencies from exchanged timestamps, the system determines whether conditions warrant synchronization adjustments, thereby avoiding unnecessary frequent synchronizations while maintaining accuracy when needed.
Solution Approach 2:
Instead of continuously synchronizing clocks, the system performs partial synchronization actions only when latency statistics indicate instability or when threshold conditions are met. This selective approach uses less than full synchronization frequency, reducing bandwidth and processing demands while maintaining sufficient timestamp accuracy for safe operation.
Data Source
AI summary
A plurality of messages can be received from a remote device, each of the messages including a respective sent time from the remote device. A receiver can store a respective receipt time of each of the messages. A computer clock can be adjusted based on a first difference between respective sent times and a second difference between respective receipt times.