Methods for updating timing advance and beam and bandwidth part switching for non-terrestrial networks

1. A method of performing a timing advance adjustment between a user equipment (UE) and a non-terrestrial network (NTN), the method comprising:

receiving and decoding a medium access control (MAC) control element (CE) including closed loop information;

receiving and decoding system information including open loop information;

determining a timing advance value based on either the closed loop information or the open loop information; and

controlling timing of an uplink transmission signal, transmitted from the UE, based on the timing advance value,

wherein determining the timing advance value comprises:

configuring a priority timer,

assigning a priority to either a closed loop method or an open loop method, and

using either the closed loop method or the open loop method to determine the timing advance value based on the assigned priority and a state of the priority timer.

2. The method of claim 1 , wherein the closed loop information comprises a timing advance command, and

wherein the open loop information comprises satellite ephemeris data and a common timing advance.

3. The method of claim 2 , wherein determining the timing advance value comprises:

determining a closed loop timing advance component based on the timing advance command; and

determining an open loop timing advance component, and

wherein determining the open loop timing advance component comprises:

calculating a UE-specific timing advance based on a UE's position and the satellite ephemeris data; and

determining the open loop timing advance component based on the UE-specific timing advance and the common timing advance.

4. The method of claim 1 , wherein determining the timing advance value comprises:

when using the closed loop method to determine the timing advance value, determining the timing advance value based on the closed loop information; and

when using the open loop method to determine the timing advance value, determining the timing advance value based on the open loop information.

5. The method of claim 4 , wherein determining the timing advance value comprises:

when the priority is assigned to the closed loop method, reverting to the open loop method if the priority timer has expired; and

when the priority is assigned to the open loop method, reverting to the closed loop method if the priority timer has expired.

6. The method of claim 5 , further comprising, when the priority is assigned to the closed loop method, restarting the priority timer when a timing advance command is received.

7. The method of claim 5 , further comprising, when the priority is assigned to the open loop method, restarting the priority timer when satellite ephemeris data and a common timing advance are available.

8. The method of claim 5 , further comprising, when priority is assigned to the open loop method, reverting to the closed loop method if the UE's position cannot be determined.

9. The method of claim 1 , wherein assigning the priority comprises assigning the priority to a plurality of UEs located within a cell.

10. The method of claim 1 , wherein determining the timing advance value based on either the closed loop information or the open loop information comprises:

determining a first timing advance value based on the closed loop information at a first time; and

determining a second timing advance value based on the open loop information at a second time, and

wherein controlling the timing of the uplink transmission signal further comprises:

controlling the timing of the uplink transmission signal based on the first timing advance value at the first time, and

controlling the timing of the uplink transmission signal based on the second timing advance value at the second time.

11. A user equipment (UE), comprising:

a memory; and

a processor configured to:

receive and decode a medium access control (MAC) control element (CE) including closed loop information,

receive and decoding system information including open loop information,

determine a timing advance value based on either the closed loop information or the open loop information,

control timing of an uplink transmission signal, transmitted from the UE, based on the timing advance value,

configure a priority timer,

assign a priority to either a closed loop method or an open loop method, and

use either the closed loop method or the open loop method to determine the timing advance value based on the assigned priority and a state of the priority timer.

12. The UE of claim 11 , wherein the closed loop information comprises a timing advance command, and

wherein the open loop information comprises satellite ephemeris data and a common timing advance.

13. The UE of claim 12 , wherein the processor is further configured to:

determine a closed loop timing advance component based on the timing advance command, and

determine an open loop timing advance component by:

calculating a UE-specific timing advance based on a UE's position and the satellite ephemeris data; and

determining the open loop timing advance component based on the UE-specific timing advance and the common timing advance.

14. The UE of claim 11 , wherein the processor is further configured to:

when using the closed loop method, determine the timing advance value based on the closed loop information, and

when using the open loop method, determine the timing advance value based on the open loop information.

15. The UE of claim 14 , wherein the processor is further configured to:

when the priority is assigned to the closed loop method, revert to the open loop method if the priority timer has expired, and

when the priority is assigned to the open loop method, revert to the closed loop method if the priority timer has expired.

16. The UE of claim 15 , wherein the processor is further configured to, when the priority is assigned to the closed loop method, restart the priority timer when a timing advance command is received.

17. The UE of claim 15 , wherein the processor is further configured to, when the priority is assigned to the open loop method, restart the priority timer when satellite ephemeris data and a common timing advance are available.

18. The UE of claim 15 , wherein the processor is further configured to, when priority is assigned to the open loop method, revert to the closed loop method if the UE's position cannot be determined.

19. The UE of claim 11 , wherein the processor is further configured to assign the priority to a plurality of UEs located within a cell.

20. The UE of claim 11 , wherein the processor is further configured to:

determine a first timing advance value based on the closed loop information at a first time,

determine a second timing advance value based on the open loop information at a second time,

control the timing of the uplink transmission signal based on the first timing advance value at the first time, and

control the timing of the uplink transmission signal based on the second timing advance value at the second time.