User equipment and method for timing alignment
A method and a user equipment (UE) for timing alignment is provided. The method includes maintaining a Timing Advance (TA) value as a first TA value; receiving, from a Base Station (BS), a TA command during a Random Access (RA) procedure; applying the TA command to set the TA value to a second TA value included in the TA command in a case that a first timing alignment timer is not running; determining whether a contention resolution for the RA procedure is successful; and when the contention resolution is not successful, setting the TA value to the first TA value in a case that a Configured Grant-based Small Data Transmission (CG-SDT) procedure is ongoing.
1. A method performed by a User Equipment (UE) for timing alignment, the method comprising:
maintaining a Timing Advance (TA) value as a first TA value;
receiving, from a Base Station (BS), a TA command during a Random Access (RA) procedure;
applying the TA command to set the TA value to a second TA value included in the TA command in a case that a first timing alignment timer is not running;
determining whether a contention resolution for the RA procedure is successful; and
when the contention resolution is not successful, setting the TA value to the first TA value in a case that a Configured Grant-based Small Data Transmission (CG-SDT) procedure is ongoing.
2. The method of claim 1 , further comprising:
when the contention resolution is successful, starting or restarting a CG-SDT timing alignment timer in a case that the CG-SDT procedure is ongoing.
3. The method of claim 2 , wherein the CG-SDT timing alignment timer is configured by a Radio Resource Control (RRC) release message.
4. The method of claim 1 , further comprising:
when the contention resolution is successful, stopping the first timing alignment timer in a case that the CG-SDT procedure is ongoing.
5. The method of claim 1 , further comprising:
starting the first timing alignment timer in a case that the first timing alignment timer is not running.
6. The method of claim 1 , wherein the TA command is received in a Random Access Response (RAR).
7. The method of claim 1 , wherein the TA command is received in a Message B (MSGB).
8. The method of claim 1 , further comprising:
maintaining the TA value when a CG-SDT timing alignment timer expires.
9. The method of claim 1 , further comprising:
receiving, from the BS, a TA command Medium Access Control (MAC) Control Element (CE); and
in a case that the CG-SDT procedure is ongoing, starting or restarting a CG-SDT timing alignment timer in response to receiving the TA command MAC CE.
10. The method of claim 9 , further comprising:
in a case that the CG-SDT procedure is ongoing, further starting or restarting the first timing alignment timer in response to receiving the TA command MAC CE.
11. A User Equipment (UE) in a wireless communication system for timing alignment, the UE comprising:
at least one processor; and
at least one non-transitory computer-readable medium coupled to the at least one processor and storing one or more computer-executable instructions that, when executed by the at least one processor, cause the UE to:
maintain a Timing Advance (TA) value as a first TA value;
receive, from a Base Station (BS), a TA command during a Random Access (RA) procedure;
apply the TA command to set the TA value to a second TA value included in the TA command in a case that a first timing alignment timer is not running;
determine whether a contention resolution for the RA procedure is successful; and
when the contention resolution is not successful, set the TA value to the first TA value in a case that a Configured Grant-based Small Data Transmission (CG-SDT) procedure is ongoing.
12. The UE of claim 11 , wherein the one or more computer-executable instructions, when executed by the at least one processor, further cause the UE to:
when the contention resolution is successful, start or restart a CG-SDT timing alignment timer in a case that the CG-SDT procedure is ongoing.
13. The UE of claim 12 , wherein the CG-SDT timing alignment timer is configured by a Radio Resource Control (RRC) release message.
14. The UE of claim 11 , wherein the one or more computer-executable instructions, when executed by the at least one processor, further cause the UE to:
when the contention resolution is successful, stop the first timing alignment timer in a case that the CG-SDT procedure is ongoing.
15. The UE of claim 11 , wherein the one or more computer-executable instructions, when executed by the at least one processor, further cause the UE to:
start the first timing alignment timer in a case that the first timing alignment timer is not running.
16. The UE of claim 11 , wherein the TA command is received in a Random Access Response (RAR).
17. The UE of claim 11 , wherein the TA command is received in a Message B (MSGB).
18. The UE of claim 11 , wherein the one or more computer-executable instructions, when executed by the at least one processor, further cause the UE to:
maintain the TA value when a CG-SDT timing alignment timer expires.
19. The UE of claim 11 , wherein the one or more computer-executable instructions, when executed by the at least one processor, further cause the UE to:
receive, from the BS, a TA command Medium Access Control (MAC) Control Element (CE); and
in a case that the CG-SDT procedure is ongoing, start or restart a CG-SDT timing alignment timer in response to receiving the TA command MAC CE.
20. The UE of claim 19 , wherein the one or more computer-executable instructions, when executed by the at least one processor, further cause the UE to:
in a case that the CG-SDT procedure is ongoing, further start or restart the first timing alignment timer in response to receiving the TA command MAC CE.