Time Synchronization via Propagation Delay Compensation
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Solution Overview
Problem
Current time synchronization methods in cellular network systems, such as LTE, fail to provide absolute time synchronization due to neglecting uplink and downlink propagation delays, resulting in time service errors.
Innovation Solution
The method involves determining specific moments for downlink and uplink messages to account for propagation delays, allowing for accurate time offset calculation and absolute time synchronization by using the first and second moments for downlink messages and the third and fourth moments for uplink messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If time alignment based on frame boundary is implemented for signal demodulation, then correct data demodulation is achieved, but absolute time synchronization is not supported and time service errors occur when delay exists
Solution Approach 1:
The patent introduces a timing advance mechanism as an intermediary parameter that mediates between the frame boundary alignment requirement and the propagation delay compensation need. The timing advance value acts as a mediator that adjusts the uplink transmission timing to account for propagation delays, enabling both correct demodulation and accurate time service
Solution Approach 2:
The patent changes the timing parameter from fixed frame boundary alignment to dynamic timing advance-based alignment. By adjusting the timing advance parameter based on measured propagation delays, the system adapts the synchronization mechanism to compensate for variable transmission delays, resolving the contradiction between fixed frame structure and variable delay conditions
2Reliability
If wired Ethernet technology is used for time sensitive network, then time service is provided, but construction and deployment becomes complex and maintenance becomes difficult
Solution Approach 1:
The patent replaces the mechanical wired Ethernet connection system with a wireless communication system. By substituting physical cable connections with wireless signals, the system eliminates the complexity of wired network construction and maintenance while maintaining time service functionality through propagation delay compensation mechanisms
3Reliability
If wired Ethernet cable connection is required, then TSN time service is achieved, but mobility of industrial robots is limited
Solution Approach 1:
The patent replaces the mechanical cable connection requirement with wireless communication, enabling industrial robots to maintain time synchronization services while moving freely without physical cable constraints. The wireless implementation removes the mobility limitation while preserving the time service through delay compensation
Data Source
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AI summary
Embodiments of the present invention provide a time service method, a terminal device, and a network device. The method includes: determining, by a terminal device, a first moment of a first downlink message, and determining a second moment of the first downlink message; determining, by the terminal device, a third moment of a first uplink message, and determining a fourth moment of the first uplink message; and determining, by the terminal device, a time offset between the terminal device and the network device based on the first moment, the second moment, the third moment, and the fourth moment. According to the method provided in the embodiment of the present invention, uplink and downlink propagation delays are considered for the terminal device, and a time service based on absolute time can be provided for the terminal device by using the first moment and the second moment of the first downlink message and the third moment and the fourth moment of the first uplink message, thereby effectively reducing a time service error.