Uplink Time Advance Grouping for Multi-TRP Timing Alignment
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Solution Overview
Problem
In wireless communication networks with multiple Transmission/Reception Points (mTRP), managing distinct Time Advances (TAs) for uplink transmissions is challenging, particularly when Time Alignment Timers (TATs) for some TRPs expire while others remain active.
Innovation Solution
The serving cell configures and signals associations between TA identifiers and TRPs to the wireless terminal, enabling it to manage initial and updated TAs, and provides procedures for handling TAT expirations differently based on the availability of TAs for each TRP.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple distinct TAs are maintained for different TRPs, then uplink transmission timing accuracy is improved, but device complexity and management overhead increase
Solution Approach 1:
The patent segments the TA management by introducing separate Time Alignment Timers (TATs) for different TAGs (Time Advance Groups). Each TAG can be associated with specific TRPs, allowing independent expiration and renewal of TATs per TAG. This segmentation enables precise control of uplink timing per TRP group while simplifying overall management through structured grouping.
Solution Approach 2:
The patent establishes preliminary associations between TAGs and TRPs through configuration signaling before actual uplink transmissions occur. The network configures multiple TAGs and their associations with TRPs in advance, so that when TAT expiration occurs, the wireless terminal can immediately determine which TRPs are affected and apply appropriate procedures without complex real-time decision-making.
2Ease of operation
If TAT expiration procedures are simplified, then ease of operation is improved, but reliability of uplink synchronization deteriorates
Solution Approach 1:
The patent introduces dynamic behavior in TAT expiration handling based on the configuration of TAG-TRP associations. When a TAT expires, the system dynamically determines the appropriate action: if the expired TAG is associated with only one TRP, resources are suspended; if associated with multiple TRPs, resources are released. This dynamic response ensures reliability while maintaining operational simplicity through rule-based automation.
Solution Approach 2:
The patent implements feedback mechanisms where the network monitors TAT expiration events and the resulting resource suspension/release actions. This feedback loop allows the network to maintain uplink synchronization reliability by detecting when TATs expire and coordinating appropriate TA updates or resource reconfigurations, ensuring that simplified procedures do not compromise synchronization quality.
3Device complexity
If resources are released upon TAT expiration, then device complexity is reduced, but loss of time occurs due to resource reconfiguration
Solution Approach 1:
The patent applies local quality by differentiating resource handling based on the specific TAG-TRP association structure. Instead of uniformly releasing all resources upon any TAT expiration, the system locally suspends resources only for the affected TAG's associated TRPs. This localized approach minimizes time loss by preserving resources for unaffected TRPs while still reducing complexity through automated suspension rather than full release and reconfiguration.
Data Source
AI summary
This disclosure is directed generally to wireless communication network and particularly to Time Advance (TA) management for multipoint transmission/reception in one cell. Various example implementations are described for the serving cell to configure and signal an association between TRPs of the serving cell with the multiple TAs managed by a wireless terminal and for the wireless terminal to obtain initial and updated TAs for these TRPs. Various additional embodiments are further disclosed, providing example procedures for handling uplink Time Alignment Timer (TAT) expiration when multiple TRPs are involved, particularly when TATs for some TRPs have expired whereas TATs for some other TRPs are still available.