NTN Cell Re-Synchronization Across Same-ID Satellite Handover
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In scenarios where a satellite switch occurs without a cell identity change, the terminal device fails to synchronize with the cell due to maintaining ephemeris information of the source satellite, as timer T430 restarts with outdated information.
Innovation Solution
The terminal device receives NTN assistance information of both the first and second satellites, where the cell identities are the same, and restarts the timer with the start time and duration set to the second satellite's NTN assistance information to ensure synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If timer T430 is restarted upon reception of SIB19 or reconfiguration message, then the terminal device can maintain ephemeris information for cell synchronization, but in satellite switch scenarios without cell identity change, the terminal device maintains outdated ephemeris information of the source satellite and fails to synchronize with the target satellite
Solution Approach 1:
The network side performs preliminary action by indicating satellite switch information in advance through SIB19 or reconfiguration messages before the actual satellite switch occurs. This allows the terminal device to proactively update its ephemeris information from the source satellite to the target satellite, ensuring synchronization reliability without maintaining outdated information.
Solution Approach 2:
The system implements feedback mechanism where the network side monitors satellite switch scenarios and provides timely updates to terminal devices through system information blocks or reconfiguration messages. This feedback loop ensures that terminal devices receive accurate ephemeris information corresponding to currently serving satellites, resolving the contradiction between maintaining synchronization and avoiding outdated information.
2Measurement precision
If the terminal device continuously updates ephemeris information upon receiving system information, then synchronization accuracy is maintained, but in satellite switch scenarios without cell identity change, unnecessary updates occur causing information inconsistency
Solution Approach 1:
The network side performs preliminary action by indicating satellite switch information in advance through SIB19 or reconfiguration messages before the actual satellite switch occurs. This allows the terminal device to proactively update its ephemeris information from the source satellite to the target satellite, ensuring synchronization reliability without maintaining outdated information.
Solution Approach 2:
The system implements feedback mechanism where the network side monitors satellite switch scenarios and provides timely updates to terminal devices through system information blocks or reconfiguration messages. This feedback loop ensures that terminal devices receive accurate ephemeris information corresponding to currently serving satellites, resolving the contradiction between maintaining synchronization and avoiding outdated information.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
This application relates to a communication method and apparatus. A terminal device may receive first information from a first cell, to obtain NTN assistance information of a first satellite and NTN assistance information of a second satellite. When the first information is received, the first satellite corresponds to the first cell, and a cell identity corresponding to the second satellite is the same as a cell identity of the first cell. This means that after the first satellite stops serving the first cell, the second satellite is to take over from the first satellite. Further, when the terminal device re-synchronizes with the first cell or before the terminal device re-synchronizes with the first cell, the terminal device restarts a timer. Start time of the timer is start time of the NTN assistance information of the second satellite, and duration of the timer is validity duration of the NTN assistance information of the second satellite. This means that the timer maintains the NTN assistance information of the second satellite. In this way, the terminal device can successfully re-synchronize with the first cell.