Method and apparatus for handling validity timer for handover in a wireless communication system
Methods, systems, and apparatuses can comprise a User Equipment (UE) receiving a system information including at least a first Non-terrestrial Network (NTN) configuration for a serving cell, starting or restarting a validity timer for the serving cell in response to receiving the system information, receiving a Radio Resource Control (RRC) reconfiguration message with ReconfigurationWithSync for a target cell, stopping, in response to receiving the RRC reconfiguration message, the validity timer that is running based on the first NTN configuration, and starting the validity timer based on a second NTN configuration for the target cell.
1. A method for a User Equipment (UE), comprising:
receiving a system information including at least a first Non-terrestrial Network (NTN) configuration for a serving cell;
starting or restarting a validity timer for the serving cell in response to receiving the system information;
receiving a Radio Resource Control (RRC) reconfiguration message with ReconfigurationWithSync for a target cell;
stopping, in response to receiving the RRC reconfiguration message, the validity timer that is running based on the first NTN configuration; and
starting the validity timer based on a second NTN configuration for the target cell.
2. The method of claim 1 , further comprising:
triggering a handover procedure to the target cell in response to receiving the RRC reconfiguration message; and/or
transmitting an RRC reconfiguration complete message in response to receiving the RRC reconfiguration message.
3. The method of claim 1 , further comprising acquiring another system information if the validity timer expires.
4. The method of claim 1 , wherein the second NTN configuration is included in a serving cell configuration of the ReconfigurationWithSync in the RRC reconfiguration message, and/or wherein the second NTN configuration is included in a neighbor cell list of the system information and/or not included in the RRC reconfiguration message.
5. The method of claim 1 , wherein the first NTN configuration includes at least a first validity duration and/or a first epoch time, and wherein the second NTN configuration includes at least a second validity duration and/or a second epoch time.
6. The method of claim 1 , wherein the UE starts or restarts the validity timer with a timer value set to a first validity duration from a subframe indicated by a first epoch time.
7. The method of claim 1 , wherein the UE starts the validity timer with a timer value set to a second validity duration from a subframe indicated by a second epoch time.
8. The method of claim 1 , wherein the validity timer is a validity timer for NTN Uplink (UL) synchronization and/or the validity timer is T430.
9. The method of claim 1 , wherein stopping the validity timer is at a first timing and starting the validity timer based on a second NTN configuration for the target cell is at a second timing.
10. The method of claim 9 , wherein the second timing is a timing after the first timing.
11. A User Equipment (UE), comprising:
a memory; and
a processor operatively coupled to the memory, wherein the processor is configured to execute program code to:
receive a system information including at least a first Non-terrestrial Network (NTN) configuration for a serving cell;
start or restart a validity timer for the serving cell in response to receiving the system information;
receive a Radio Resource Control (RRC) reconfiguration message with ReconfigurationWithSync for a target cell;
stop, in response to receiving the RRC reconfiguration message, the validity timer that is running based on the first NTN configuration; and
start the validity timer based on a second NTN configuration for the target cell.
12. The UE of claim 11 , wherein the processor is further configured to execute program code to:
trigger a handover procedure to the target cell in response to receiving the RRC reconfiguration message; and/or
transmit an RRC reconfiguration complete message in response to receiving the RRC reconfiguration message.
13. The UE of claim 11 , wherein the processor is further configured to execute program code to acquire another system information if the validity timer expires.
14. The UE of claim 11 , wherein the second NTN configuration is included in a serving cell configuration of the ReconfigurationWithSync in the RRC reconfiguration message; and/or wherein the second NTN configuration is included in a neighbor cell list of the system information and/or not included in the RRC reconfiguration message.
15. The UE of claim 11 , wherein the first NTN configuration includes at least a first validity duration and/or a first epoch time, and wherein the second NTN configuration includes at least a second validity duration and/or a second epoch time.
16. The UE of claim 11 , wherein the UE starts or restarts the validity timer with a timer value set to a first validity duration from a subframe indicated by a first epoch time.
17. The UE of claim 11 , wherein the UE starts the validity timer with a timer value set to a second validity duration from a subframe indicated by a second epoch time.
18. The UE of claim 11 , wherein the validity timer is a validity timer for NTN Uplink (UL) synchronization and/or the validity timer is T430.
19. The UE of claim 11 , wherein stopping the validity timer is at a first timing and starting the validity timer based on a second NTN configuration for the target cell is at a second timing.
20. The UE of claim 19 , wherein the second timing is a timing after the first timing.