User Equipment Timing Advance Management for Non-Terrestrial Networks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In non-terrestrial networks, the high velocity of satellites and long round trip times lead to unaffordable signaling overhead and communication challenges, particularly in controlling timing advance for uplink transmissions, which are not effectively addressed by existing technologies.
Innovation Solution
A user equipment (UE) and base station method that determines and applies specific timing advances for downlink and uplink transmissions, accounting for feeder link propagation delays to reduce signaling overhead and ensure reliable communication performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the network controls timing advance via timing advance commands in NTN systems, then uplink synchronization is maintained, but signaling overhead becomes unaffordable due to high satellite velocity requiring frequent adjustments
Solution Approach 1:
The UE performs preliminary timing advance adjustments autonomously based on pre-configured parameters and satellite ephemeris data, before receiving network commands. This preliminary action reduces the frequency of network signaling by handling routine synchronization adjustments locally at the UE.
Solution Approach 2:
The UE autonomously calculates and applies timing advance values using locally stored satellite orbital parameters and measured propagation delays, serving its own synchronization needs without continuous network intervention. This self-service mechanism significantly reduces uplink signaling overhead while maintaining synchronization reliability.
2Reliability
If timing advance is used to compensate for long round trip time in NTN, then uplink-downlink timing alignment is achieved, but the timing advance value becomes extremely large requiring extended indication ranges
Solution Approach 1:
The timing advance compensation is segmented into multiple components: a first timing advance value compensating for feeder link propagation delay and a second timing advance value compensating for user equipment link propagation delay. This segmentation allows each component to be managed within standard indication ranges while achieving total compensation for the extremely long end-to-end delay.
Solution Approach 2:
The network introduces an intermediary reference point (such as a gateway or ground station) whose position and timing are known to both the satellite and UE. Timing advance values are calculated relative to this intermediary, breaking the direct long-distance timing relationship into manageable segments and avoiding the need for extremely large TA indication ranges.
3Area of stationary object
If satellite velocity is high relative to UE position, then coverage area is expanded, but timing synchronization becomes more difficult requiring more frequent adjustments
Solution Approach 1:
The system performs preliminary calculations of timing advance values based on predicted satellite positions using ephemeris data, allowing the UE to pre-adjust its timing before the satellite reaches positions that would require correction. This proactive approach handles high-velocity effects without requiring frequent reactive adjustments.
Solution Approach 2:
The UE continuously monitors downlink signal timing and provides feedback measurements to the network, which uses this feedback to update timing advance commands more efficiently. This closed-loop feedback mechanism adapts to satellite motion without requiring excessively frequent open-loop adjustments, reducing overall signaling overhead.
Data Source
AI summary
A wireless communication method and a user equipment (UE) are provided. The wireless communication method is performed by a UE and includes: determining, by the UE, a first information and/or a second information and applying, by the UE, the first information and/or the second information for a downlink reception and/or an uplink transmission.