NTN Timing Synchronization Using RA Fallback for Fresh TA Reports
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Solution Overview
Problem
Existing NTN systems face challenges in ensuring timely and reliable transmission of timing advance (TA) reports due to outdated information and unreliable HARQ processes, leading to potential UE scheduling failures and service interruptions.
Innovation Solution
Implementing a UE that receives satellite assistance information and timing information from a base station to determine the necessity of a RACH-less synchronization operation, and initiating a random access procedure only when RACH-less is not configured, ensuring fresh TA reports are transmitted using HARQ processes with feedback enabled.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If RACH-less synchronization operation is used, then transmission speed is improved, but reliability deteriorates due to outdated TA information and unreliable HARQ processes
Solution Approach 1:
The system changes the operational parameters by switching between RACH-less mode and RA procedure based on configuration and timing conditions. When RACH-less is configured and timing conditions are met, fast synchronization is enabled; otherwise, the system falls back to RA procedure to ensure reliable TA report transmission, thus dynamically adjusting parameters to balance speed and reliability.
Solution Approach 2:
The synchronization mechanism dynamically adapts its behavior based on received timing information and configuration. The UE determines whether to perform RACH-less synchronization or full RA procedure by evaluating dynamic conditions (timing information, RACH-less configuration), making the system flexible and adaptive to different operational scenarios to maintain both speed and reliability.
2Reliability
If RA procedure is performed, then TA report transmission reliability is improved, but transmission time increases
Solution Approach 1:
The system adjusts operational parameters by selecting between RACH-less mode and full RA procedure based on configuration and timing conditions. When RACH-less is configured and timing conditions are satisfied, the system uses the faster mode; otherwise, it performs the complete RA procedure, dynamically changing parameters to optimize the trade-off between time loss and reliability.
Solution Approach 2:
The base station provides timing information and RACH-less configuration in advance to the UE. This preliminary action allows the UE to determine the appropriate synchronization method before execution, enabling fast RACH-less synchronization when conditions permit and avoiding unnecessary time loss while ensuring reliability when needed.
3Device complexity
If RACH-less synchronization is configured, then device complexity is reduced, but scheduling reliability deteriorates
Solution Approach 1:
The system changes operational parameters by switching between RACH-less mode and full RA procedure based on configuration and timing conditions. When RACH-less is configured and timing conditions are met, simplified synchronization is used; otherwise, the system performs full RA procedure, dynamically adjusting parameters to balance complexity reduction with scheduling reliability.
Solution Approach 2:
The synchronization mechanism dynamically adapts its complexity based on configuration and timing conditions. The UE evaluates whether to use simple RACH-less synchronization or the more complex but reliable RA procedure, making the system dynamically adjustable to maintain scheduling reliability while reducing complexity when appropriate.
Data Source
AI summary
Methods and apparatuses for a timing advance report an NTN is provided. The method of UE comprises: receiving, from a BS, first information including satellite assistance information for a target satellite; receiving, from the BS, second information including timing information, wherein the timing information includes at least one of a start time and a time duration for a synchronization operation; determining whether a RACH-less synchronization operation is configured; and initiating, based on the satellite assistance information and the timing information, the synchronization operation by performing a RA procedure upon a determination that the RACH-less synchronization operation is not configured.