Base Station Timestamping for Mobile Unit Sensor Data
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Solution Overview
Problem
Existing methods for time synchronization in vehicle communication systems, such as GPS and NTP, face uncertainties and availability issues due to processing delays and limitations in infrastructure access, leading to inaccuracies in data interpretation and unreliable timestamp availability, especially in blocked areas or during power outages.
Innovation Solution
A method that determines the roundtrip time between a mobile unit and a base station, using terrestrial communication systems, to add a timestamp to messages containing sensor data, allowing for accurate temporal alignment and interpretation of data across mobile units, even in areas without satellite access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS timestamp is used for time synchronization, then high precision timestamp can be obtained, but processing time delay and uncertainty increase
Solution Approach 1:
The patent introduces a base station as an intermediary between the mobile unit and the time synchronization system. The base station receives the uplink signal, determines the roundtrip time, and uses this information to calculate the timestamp. This intermediary approach eliminates the need for the mobile unit to directly process GPS signals, thereby reducing processing time delay while maintaining timestamp precision through the base station's calculation capabilities
2Reliability
If NTP-based time synchronization is used, then infrastructure availability is improved, but time delay and uncertainty increase
Solution Approach 1:
The patent extracts the time synchronization function from the NTP protocol stack and implements it directly at the base station level using radio signal propagation time measurements. By taking out the time synchronization mechanism from the higher-level NTP application layer and implementing it at the physical/link layer through roundtrip time measurement, the system achieves both infrastructure availability and reduced time delay
3Measurement precision
If GPS receiver is used in blocked areas, then time synchronization is achieved, but availability drops due to signal blockage
Solution Approach 1:
The base station acts as an intermediary that receives signals from the mobile unit and uses these signals to determine the roundtrip time. Since the mobile unit's uplink signal can be received by the base station even when GPS satellites are blocked, this intermediary approach enables timestamp generation in blocked areas where direct GPS reception is unavailable
4Measurement precision
If roundtrip time determination is implemented in base station, then timestamp precision is improved, but device complexity increases
Solution Approach 1:
The base station uses its existing uplink signal reception capability to determine the roundtrip time. The same receiver that is already used for normal communication purposes is leveraged to measure the time of arrival of the mobile unit's signal. This self-service approach allows the base station to perform timestamp calculation without adding dedicated measurement hardware, thereby improving timestamp accuracy while minimizing increases in device complexity
Data Source
AI summary
A mobile unit as well as a method for time-stamping a first message of the first mobile unit to a second mobile unit are provided. The method includes the steps of: determining a roundtrip time between the first mobile unit and a base station, receiving the first message sent by the first mobile unit in the base station, adding a timestamp to the first message in the base station while taking into account the roundtrip time, and sending the time-stamped first message to the second mobile unit.