NTN Handover Timing Using Preconfigured Commands and Time Offsets

The patent introduces a terrestrial network cell as an intermediary for transmitting the handover command. Instead of the source NTN cell directly commanding handover to the target NTN cell (which causes excessive RTT), the handover command is routed through a terrestrial cell that has lower propagation delay. This intermediary approach allows the handover to be initiated and coordinated with reduced timing constraints, solving the contradiction between maintaining connectivity and reducing handover time.

The patent applies different timing configurations to different user equipment based on their specific needs. User equipment experiencing NTN handover is provided with an extended maximum allowed time through dedicated RRC messages, while other user equipment maintains the standard timing configuration. This localized adjustment ensures that only the affected UE receives timing extensions, preventing synchronization issues for other UEs while still enabling successful NTN handover for the specific UE that requires it.

The network uses existing RRC message structures (RRCReconfiguration and RRCRelease) that are already part of the standard protocol stack to convey UE-specific maximum allowed time configurations. Rather than introducing new complex signaling mechanisms, the patent leverages existing self-service capabilities of the RRC layer to carry the extended timing parameters. This approach enables UE-specific optimization while minimizing additional network complexity by reusing established message formats and procedures.