Method and apparatus for performing random access procedure for beam failure recovery

1. A method performed by a User Equipment (UE) for Beam Failure Recovery (BFR), the method comprising:

detecting a beam failure event on a serving cell;

determining whether the serving cell is a Special Cell (SpCell) or a Secondary Cell (SCell) to initiate a Random Access (RA) procedure for an SpCell BFR procedure or to trigger an SCell BFR procedure;

triggering the SCell BFR procedure in a case that the serving cell is the SCell; and

initiating the RA procedure on a Bandwidth Part (BWP) on the serving cell in a case that the serving cell is the SpCell, the RA procedure BFR including:

performing an RA type selection after determining that the UE is not configured with any Contention-Free RA (CFRA) resource, the RA type selection including determining one of a 2-step RA type and a 4-step RA type as an RA type of the RA procedure based on a Reference Signal Received Power (RSRP) value of a Downlink (DL) pathloss reference;

determining the RA type as the 2-step RA type in the RA type selection in a case that the RSRP value is larger than a threshold configured by a 2-step RA configuration;

not performing the RA type selection after determining that the UE is configured with a CFRA resource;

determining the RA type as the 4-step RA type after not performing the RA type selection in a case that the CFRA resource is a 4-step RA type RA resource; and

determining that the SpCell BFR procedure is completed when the RA procedure is completed.

2. The method of claim 1 , further comprising:

determining the RA type as the 2-step RA type in the RA type selection in a case that the BWP is not configured with any 4-step RA type RA resource and is configured with at least one 2-step RA type RA resource.

3. The method of claim 1 , wherein the UE is not configured with any CFRA resource, and the RA procedure further includes:

transmitting an RA preamble via a Contention-Based RA (CBRA) resource after performing the RA type selection.

4. The method of claim 1 , wherein the UE is configured with the CFRA resource, and the RA procedure further includes:

transmitting an RA preamble via one of a Contention-Based RA (CBRA) resource and the CFRA resource after not performing the RA type selection.

5. The method of claim 1 , wherein the UE is not allowed to select the 2-step RA type as the RA type of the RA procedure in a case that the UE does not perform the RA type selection.

6. The method of claim 1 , wherein the RA procedure further includes:

selecting a carrier before performing the RA type selection, wherein the carrier is a Normal Uplink (NUL) or a Supplementary UL (SUL).

7. The method of claim 1 , wherein the RA type selection is performed in an initialization phase of the RA procedure.

8. A User Equipment (UE) for Beam Failure Recovery (BFR), the UE comprising:

a memory; and

at least one processor coupled to the memory, the at least one processor being configured to:

detect a beam failure event on a serving cell;

determine whether the serving cell is a Special Cell (SpCell) or a Secondary Cell (SCell) to initiate a Random Access (RA) procedure for an SpCell BFR procedure or to trigger an SCell BFR procedure;

trigger the SCell BFR procedure in a case that the serving cell is the SCell; and

initiate the RA procedure on a Bandwidth Part (BWP) on the serving cell in a case that the serving cell is the SpCell, the RA procedure including:

performing an RA type selection after determining that the UE is not configured with any Contention-Free RA (CFRA) resource, the RA type selection including determining one of a 2-step RA type and a 4-step RA type as an RA type of the RA procedure based on a Reference Signal Received Power (RSRP) value of a Downlink (DL) pathloss reference;

determining the RA type as the 2-step RA type in the RA type selection in a case that the RSRP value is larger than a threshold configured by a 2-step RA configuration;

not performing the RA type selection after determining that the UE is configured with a CFRA resource;

determining the RA type as the 4-step RA type after not performing the RA type selection in a case that the CFRA resource is a 4-step RA type RA resource; and

determine that the SpCell BFR procedure is completed when the RA procedure is completed.

9. The UE of claim 8 , wherein the at least one processor is further configured to:

determine the RA type as the 2-step RA type in the RA type selection in a case that the BWP is not configured with any 4-step RA type RA resource and is configured with at least one 2-step RA type RA resource.

10. The UE of claim 8 , wherein the UE is not configured with any CFRA resource, and the at least one processor is further configured to:

transmit an RA preamble via a Contention-Based RA (CBRA) resource after performing the RA type selection.

11. The UE of claim 8 , wherein the UE is configured with the CFRA resource, and the at least one processor is further configured to:

transmit an RA preamble via one of a Contention-Based RA (CBRA) resource and the CFRA resource after not performing the RA type selection.

12. The UE of claim 8 , wherein the UE is not allowed to select the 2-step RA type as the RA type of the RA procedure in a case that the UE does not perform the RA type selection.

13. The UE of claim 8 , wherein the at least one processor is further configured to:

select a carrier before performing the RA type selection, wherein the carrier is a Normal Uplink (NUL) or a Supplementary UL (SUL).

14. The UE of claim 8 , wherein the RA type selection is performed in an initialization phase of the RA procedure.