User equipment and method for two-step random access procedure

1. A user equipment (UE) for a 2-step random access (RA) procedure, the UE comprising:

at least one processor; and

at least one memory coupled to the at least one processor and storing computer-executable instructions that, when executed by the at least one processor, cause the UE to:

perform a first Listen-Before-Talk (LBT) procedure on a Physical Random Access Channel (PRACH) occasion for transmitting a preamble of a message A (MSGA);

perform a second LBT procedure on a Physical Uplink Shared Channel (PUSCH) occasion for transmitting a payload of the MSGA, the payload including a Medium Access Control (MAC) Control Element (CE) including a Cell-Radio Network Temporary Identifier (C-RNTI);

monitor Physical Downlink Control Channel (PDCCH) candidates for a first random access response (RAR) identified by a message B (MSGB)-Radio Network Temporary Identifier (RNTI) in a MSGB window; and

monitor the PDCCH candidates for a second RAR identified by the C-RNTI in the MSGB window in a case that the second LBT procedure is successful.

2. The UE of claim 1 , wherein the UE determines not to monitor the PDCCH candidates for the second RAR identified by the C-RNTI in the MSGB window after determining that the second LBT procedure is unsuccessful.

3. The UE of claim 1 , wherein the computer-executable instructions, when executed by the at least one processor, further cause the UE to:

determine whether the second LBT procedure is successful based on whether a MAC entity of the UE receives an LBT failure indication from a lower layer.

4. The UE of claim 1 , wherein the UE is in a Radio Resource Control (RRC) Connected state.

5. The UE of claim 1 , wherein the computer-executable instructions, when executed by the at least one processor, further cause the UE to:

monitor the PDCCH candidates for a Downlink Control Information (DCI) format with Cyclic Redundancy Check (CRC) bits scrambled by the C-RNTI after determining that the second LBT procedure is successful, wherein the DCI format is one of a DCI format 0_0 and a DCI format 1_0.

6. The UE of claim 1 , wherein the computer-executable instructions, when executed by the at least one processor, further cause the UE to:

compute the MSGB-RNTI associated with the PRACH occasion,

wherein a Transport Block (TB) for the PUSCH occasion for transmitting the payload includes Cyclic Redundancy Check (CRC) bits scrambled by the MSGB-RNTI.

7. A method performed by a user equipment (UE) for a 2-step random access (RA) procedure, the method comprising:

performing a first Listen-Before-Talk (LBT) procedure on a Physical Random Access Channel (PRACH) occasion for transmitting a preamble of a message A (MSGA);

performing a second LBT procedure on a Physical Uplink Shared Channel (PUSCH) occasion for transmitting a payload of the MSGA, the payload including a Medium Access Control (MAC) Control Element (CE) including a Cell-Radio Network Temporary Identifier (C-RNTI);

monitoring Physical Downlink Control Channel (PDCCH) candidates for a first random access response (RAR) identified by a message B (MSGB)-Radio Network Temporary Identifier (RNTI) in a MSGB window; and

monitoring the PDCCH candidates for a second RAR identified by the C-RNTI in the MSGB window in a case that the second LBT procedure is successful.

8. The method of claim 7 , wherein the UE determines not to monitor the PDCCH candidates for the second RAR identified by the C-RNTI in the MSGB window after determining that the second LBT procedure is unsuccessful.

9. The method of claim 7 , further comprising:

determining whether the second LBT procedure is successful based on whether a MAC entity of the UE receives an LBT failure indication from a lower layer.

10. The method of claim 7 , wherein the UE is in a Radio Resource Control (RRC) Connected state.

11. The method of claim 7 , further comprising:

monitoring the PDCCH candidates for a Downlink Control Information (DCI) format with Cyclic Redundancy Check (CRC) bits scrambled by the C-RNTI after determining that the second LBT procedure is successful, wherein the DCI format is one of a DCI format 0_0 and a DCI format 1_0.

12. The method of claim 7 , further comprising:

computing the MSGB-RNTI associated with the PRACH occasion,

wherein a Transport Block (TB) for the PUSCH occasion for transmitting the payload includes Cyclic Redundancy Check (CRC) bits scrambled by the MSGB-RNTI.