Broadcast Information Validity Timing for NTN UE Synchronization
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Solution Overview
Problem
The challenge of long round-trip delay in non-terrestrial networks (NTN) for user equipment (UE) transmissions, particularly in scenarios where UE pre-compensation of estimated delays is unreliable, leading to inter-UE interference and reduced system performance.
Innovation Solution
Implementing a validity timer for system broadcasted information to ensure accurate timing and frequency compensation by monitoring the validity of GNSS information, allowing UEs to adjust their transmissions accordingly and preventing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If UE uses pre-compensation based on system broadcasted information for long round-trip delay in NTN, then transmission timing accuracy is improved, but the information may become invalid over time leading to inter-UE interference
Solution Approach 1:
The system triggers a validity timer when system broadcasted information is received, performing preliminary validation before the information becomes invalid. This ensures that pre-compensation calculations use only valid timing information, preventing inter-UE interference caused by using outdated broadcast data.
Solution Approach 2:
The system continuously monitors the validity timer status and provides feedback on whether system broadcasted information remains valid for pre-compensation. When the timer expires or validity is compromised, the system can request updated system information, ensuring continuous reliability of timing data.
2Reliability
If the system frequently updates system broadcasted information to maintain validity, then timing synchronization reliability is improved, but network overhead and complexity increase
Solution Approach 1:
The validity timer is triggered in advance when system broadcasted information is received, allowing the system to use the information for the entire valid period without frequent updates. This preliminary validation approach maintains synchronization reliability while minimizing network overhead by avoiding unnecessary re-transmissions.
Solution Approach 2:
The system uses periodic validity timer checks rather than continuous monitoring or frequent updates. This periodic validation mechanism maintains timing synchronization reliability while reducing network overhead compared to continuous update approaches.
Data Source
AI summary
Embodiments of the present disclosure propose a solution for availability of system broadcasted information such as GNSS information which can be used for deriving time and/or frequency domain compensation. According to embodiments of this present disclosure, a validity timer for system broadcasted information is introduced in both UE and network to guarantee the system broadcasted information availability status is synchronized in two nodes, and the system broadcasted information is valid to pre-compensate in time and/or frequency domain when the timer is running. In this way, the UE can be scheduled with correct timing and frequency estimation in UL transmission.