Uplink carrier configuration and selection with supplementary uplink

1. A user equipment (UE) for wireless communication, the UE comprising:

one or more non-transitory computer-readable media having executable instructions embodied thereon; and

at least one processor coupled to the one or more non-transitory computer-readable media and configured to execute the executable instructions to cause the UE to:

receive, from a base station, configuration information for at least two uplink carriers associated with the base station, the at least two uplink carriers including a supplementary uplink carrier (SUL) and a normal uplink carrier (NUL);

select one of the at least two uplink carriers if a power of a first downlink reference signal received from the base station, as measured by the UE, is below a first threshold value;

select, on the selected uplink carrier, a contention-free random access (CFRA) resource associated with a second downlink reference signal received from the base station if a power of the second downlink reference signal, as measured by the UE, is above a second threshold value; and

perform a random access procedure with the base station by using the selected CFRA resource over the selected uplink carrier.

2. The UE of claim 1 , wherein the first threshold value is carried in the configuration information.

3. The UE of claim 2 , wherein a portion of the configuration information that carries the first threshold value is structured with a SetupRelease structure.

4. The UE of claim 1 , wherein the configuration information is received through system information broadcast by the base station or through dedicated signaling.

5. The UE of claim 4 , wherein the at least one processor is further configured to execute the executable instructions to cause the UE to:

remove an existing uplink carrier configuration, in response to the configuration information having a null value when received through the system information.

6. The UE of claim 4 , wherein frequency information for the selected uplink carrier is received in a synchronization reconfiguration through the dedicated signaling.

7. The UE of claim 1 , wherein:

the second downlink reference signal is a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS), wherein;

the second threshold value is associated with a signal quality of the SSB and the CFRA resource is associated with the SSB if the second downlink reference signal is the SSB; and

the second threshold value is associated with a signal quality of the CSI-RS and the CFRA resource is associated with the CSI-RS if the second downlink reference signal is the CSI-RS.

8. The UE of claim 1 , wherein the at least one processor is further configured to execute the executable instructions to cause the UE to:

select a contention-based random access (CBRA) resource on the selected uplink carrier if the random access procedure using the selected CFRA resource fails.

9. The UE of claim 1 , wherein the CFRA resource is configured in a primary cell configuration information element carried in a Radio Resource Control (RRC) message.

10. A method of operating a user equipment (UE) for wireless communication, the method comprising:

receiving, from a base station, configuration information for at least two uplink carriers associated with the base station, the at least two uplink carriers including a supplementary uplink carrier (SUL) and a normal uplink carrier (NUL);

selecting one of the at least two uplink carriers if a power of a first downlink reference signal from the base station, as measured by the UE, is below a first threshold value;

selecting, on the selected uplink carrier, a contention-free random access (CFRA) resource associated with a second downlink reference signal from the base station if a power of the second downlink reference signal, as measured by the UE, is above a second threshold value; and

performing a random access procedure with the base station by using the selected CFRA resource over the selected uplink carrier.

11. The method of claim 10 , wherein the first threshold value is carried in the configuration information.

12. The method of claim 11 , wherein a portion of the configuration information that carries the first threshold value is structured with a SetupRelease structure.

13. The method of claim 10 , wherein the configuration information is received through system information broadcast by the base station or through dedicated signaling.

14. The method of claim 13 , further comprising:

removing an existing uplink carrier configuration in response to the configuration information having a null value when received through the system information.

15. The method of claim 13 , wherein frequency information for the selected uplink carrier is carried received in a synchronization reconfiguration through the dedicated signaling.

16. The method of claim 10 , wherein:

the second downlink reference signal is a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS), wherein

the second threshold value is associated with a signal quality of the SSB and the CFRA resource is associated with the SSB if the second downlink reference signal is the SSB; and

the second threshold value is associated with a signal quality of the CSI-RS and the CFRA resource is associated with the CSI-RS if the second downlink reference signal is the CSI-RS.

17. The method of claim 10 , further comprising:

selecting a contention-based random access (CBRA) resource on the selected uplink carrier if the random access procedure using the selected CFRA resource fails.

18. The method of claim 10 , wherein the CFRA resource is configured in a primary cell configuration information element carried in a Radio Resource Control (RRC) message.