Uplink Timestamping with Global Time Reference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In 3GPP LTE systems, the short system frame number wraparound time limits the accuracy of timing information for uplink transmissions, particularly for position measurements and events reported after logging, and there is a lack of a globally meaningful external time reference, making it difficult to disambiguate timing.
Innovation Solution
A method involving a mobile entity receiving a global time value with a longer wraparound time from an overhead message, calculating its alignment with a local time reference, and including this global time as a timestamp in uplink messages to enable accurate timing disambiguation, which can be extrapolated over intervals shorter or longer than the eNB wraparound time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the system uses the system frame number (SFN) as the time reference, then the timing reference is available within the LTE system, but the wraparound time is too short (on the order of ten seconds) to provide accurate timing information for position measurements and events reported after logging
Solution Approach 1:
The patent introduces an external time reference (such as GPS time) as an intermediary to bridge the gap between the LTE system's short SFN wraparound time and the need for long-term unambiguous timing. The external reference acts as a mediator that provides a longer time baseline, allowing the system to disambiguate timestamps that would otherwise wrap around within 10 seconds. This resolves the contradiction by importing a time reference from outside the system that has the desired property of long wraparound time while maintaining compatibility with the internal SFN structure.
2Reliability
If the system adopts a longer wraparound time reference, then timing disambiguation is improved, but the system requires an external time reference (such as GPS or UTC) that may not be directly interoperable with existing radio access technologies
Solution Approach 1:
The patent resolves the interoperability contradiction by adding a new dimension to the time reference system. Instead of replacing the existing SFN-based time reference, the system layersthe external time reference (GPS/UTC) above it, creating a two-dimensional time structure. The internal SFN provides fine-grained timing within the LTE system, while the external reference provides the long-term disambiguation layer. This dimensional approach allows the system to maintain full compatibility with existing radio access technologies while simultaneously gaining access to long wraparound time for improved timing reliability.
3Measurement precision
If the system includes global time in uplink messages, then position determination and event reporting accuracy is improved, but the complexity of time synchronization and alignment between global and local time references increases
Solution Approach 1:
The patent applies preliminary action by having the network provide the current global time value to mobile entities in advance through overhead messages (such as system information blocks). This allows mobile entities to pre-synchronize their internal clocks with the global time reference before needing to report position or events. By performing the time alignment preparation beforehand, the system reduces the real-time computational burden and complexity when actually generating timestamps for uplink messages. The mobile entity simply needs to record the provided global time value and use it with its local SFN counter, rather than performing complex real-time synchronization calculations.
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
Methods and devices are provided for disambiguating the timing of uplink transmissions. In one embodiment, the method may involve receiving from a wireless network a global time value having a wraparound time longer than that of a system frame number for the network, the global time value being based at least in part on an overhead message conveying at least one parameter of a first radio access technology (RAT) different from a second RAT used by the network. The method may involve determining a current global time based on the received global time value, and sending an uplink message that includes the current global time as a global timestamp.