NTN Cell Re-Synchronization Across Same-ID Satellite Switching
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Solution Overview
Problem
In scenarios where a satellite switch occurs without a change in cell identity, the terminal device fails to synchronize with the cell due to maintaining ephemeris information of the source satellite, as timer T430 continues to operate with outdated information.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 aligned with the second satellite's assistance information duration 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, but the terminal device cannot synchronize with the cell when satellite switch occurs without cell switch
Solution Approach 1:
The patent changes the triggering parameters for timer restart from simple reception events (SIB19, reconfiguration message) to a more sophisticated set of conditions that include satellite identity verification. The timer is restarted only when the second satellite's cell identity matches the first satellite's cell identity, ensuring ephemeris information remains accurate during satellite switches.
Solution Approach 2:
The patent introduces cell identity as an intermediary verification mechanism between satellite switch events and timer restart actions. By checking whether the cell identity remains unchanged during satellite transition, the system determines whether to restart the timer, preventing premature timer restarts that would cause synchronization failures.
2Duration of action of stationary object
If the terminal device maintains ephemeris information of the source satellite, then the timer can continue running, but the terminal device fails to synchronize with the target cell
Solution Approach 1:
The patent makes the timer operation dynamic by adjusting its restart behavior based on satellite switch conditions. Instead of a fixed restart rule, the timer dynamically adapts its operation based on whether the cell identity is preserved during satellite transition, ensuring both continuous operation when appropriate and synchronization when needed.
Solution Approach 2:
The patent implements a feedback mechanism where the terminal device monitors cell identity changes during satellite switches and uses this information to control timer restart behavior. The synchronization status and cell identity verification provide feedback that determines whether the timer should be restarted, creating a closed-loop control system.
Data Source
AI summary
This application relates to a communication method and apparatus. A terminal device may receive first information from a first cell, to obtain non-terrestrial network (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. 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.