User equipment and method for FBE operation in unlicensed band

1. A user equipment (UE) for frame-based equipment (FBE) operation in an unlicensed band, the UE comprising:

at least one processor; and

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

receive, from a base station (BS), a first parameter indicating a first periodicity of a first plurality of fixed frame periods (FFPs) used when the BS acts as an initiating device for the FBE operation in a cell;

receive, from the BS, a first Radio Resource Control (RRC) configuration, the first RRC configuration including a second parameter indicating a second periodicity of a second plurality of FFPs used when the UE acts as the initiating device for the FBE operation in the cell;

receive, from the BS, an indication for enabling the UE to act as the initiating device for the FBE operation for a first one of the second plurality of FFPs in the cell;

perform a clear channel assessment (CCA) on a channel of the unlicensed band immediately before a start of the first one of the second plurality of FFPs in response to receiving the indication; and

perform an uplink (UL) transmission on the channel to initiate the first one of the second plurality of FFPs after determining that the channel is clear, wherein:

the UL transmission ends before an idle period of the first one of the second plurality of FFPs determined based on the second parameter,

in a case that the UL transmission is scheduled by a UL grant, the indication is indicated by a ChannelAccess-CPext-CAPC field in a Downlink Control Information (DCI) format carrying the UL grant, and the DCI format is received in one of the first plurality of FFPs.

2. The UE of claim 1 , wherein the first parameter and the second parameter are received via dedicated RRC signaling.

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

transmit, to the BS, UE capability information indicating one or more FFP periodicity values,

wherein the second periodicity is configured based on the UE capability information.

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

receive, from the BS, a third parameter indicating a third periodicity of a third plurality of FFPs used when the UE acts as the initiating device for the FBE operation in the cell, wherein:

the second parameter is specific to a first bandwidth part (BWP); and

the third parameter is specific to a second BWP.

5. The UE of claim 1 , wherein:

in a case that the UL transmission is scheduled by a configured grant (CG) configuration and a DCI format 2_0 is received, the indication is indicated by the CG configuration, a time division duplex (TDD) configuration, and the DCI format 2_0,

the CG configuration indicates the UL transmission within a number of symbols in front of the first one of the second plurality of FFPs,

the TDD configuration indicates the number of symbols as UL symbols or flexible symbols, and

the DCI format 2_0 indicates the number of symbols as UL symbols.

6. The UE of claim 5 , wherein

the DCI format 2_0 includes a slot format indication that indicates a slot format for multiple FFPs of the second plurality of FFPs including the first one of the second plurality of FFPs.

7. The UE of claim 1 , wherein the indication is received via a second RRC configuration that includes a bitmap, each bit of the bitmap indicating whether a corresponding FFP is initiated by the UE or the BS.

8. The UE of claim 1 , wherein the indication is received via a second RRC configuration that indicates at least one of a bandwidth part (BWP) and the cell on which the UE acts as the initiating device for the FBE operation.

9. The UE of claim 1 , wherein:

in a case that the UL transmission is scheduled by a random access response (RAR), the indication is indicated by the RAR.

10. The UE of claim 1 , wherein:

in a case that the UL transmission is scheduled by a configured grant (CG) configuration and a DCI format 2_0 is not received, the indication is indicated by the CG configuration and a time division duplex (TDD) configuration,

the CG configuration indicates the UL transmission within a number of symbols in front of the first one of the second plurality of FFPs, and

the TDD configuration indicates the number of symbols as UL symbols or flexible symbols.

11. A method performed by a user equipment (UE) for frame-based equipment (FBE) operation in an unlicensed band, the method comprising:

receiving, from a base station (BS), a first parameter indicating a first periodicity of a first plurality of fixed frame periods (FFPs) used when the BS acts as an initiating device for the FBE operation in a cell;

receiving, from the BS, a first Radio Resource Control (RRC) configuration, the first RRC configuration including a second parameter indicating a second periodicity of a second plurality of FFPs used when the UE acts as the initiating device for the FBE operation in the cell;

receiving, from the BS, an indication for enabling the UE to act as the initiating device for the FBE operation for a first one of the second plurality of FFPs in the cell;

performing a clear channel assessment (CCA) on a channel of the unlicensed band immediately before a start of the first one of the second plurality of FFPs in response to receiving the indication; and

performing an uplink (UL) transmission on the channel to initiate the first one of the second plurality of FFPs after determining that the channel is clear, wherein:

the UL transmission ends before an idle period of the first one of the second plurality of FFPs determined based on the second parameter,

in a case that the UL transmission is scheduled by an UL grant, the indication is indicated by a ChannelAccess-CPext-CAPC field in a Downlink Control Information (DCI) format carrying the UL grant, and the DCI format is received in one of the first plurality of FFPs.

12. The method of claim 11 , wherein the first parameter and the second parameter are received via dedicated RRC signaling.

13. The method of claim 11 , further comprising:

transmitting, to the BS, UE capability information indicating one or more FFP periodicity values,

wherein the second periodicity is configured based on the UE capability information.

14. The method of claim 11 , further comprising:

receiving, from the BS, a third parameter indicating a third periodicity of a third plurality of FFPs used when the UE acts as the initiating device for the FBE operation in the cell, wherein:

the second parameter is specific to a first bandwidth part (BWP); and

the third parameter is specific to a second BWP.

15. The method of claim 11 , wherein:

in a case that the UL transmission is scheduled by a configured grant (CG) configuration and a DCI format 2_0 is received, the indication is indicated by the CG configuration, a time division duplex (TDD) configuration, and the DCI format 2_0,

the CG configuration indicates the UL transmission within a number of symbols in front of the first one of the second plurality of FFPs,

the TDD configuration indicates the number of symbols as UL symbols or flexible symbols, and

the DCI format 2_0 indicates the number of symbols as UL symbols.

16. The method of claim 15 , wherein

the DCI format 2_0 includes a slot format indication that indicates a slot format for multiple FFPs of the second plurality of FFPs including the first one of the second plurality of FFPs.

17. The method of claim 11 , wherein the indication is received via a second RRC configuration that includes a bitmap, each bit of the bitmap indicating whether a corresponding FFP is initiated by the UE or the BS.

18. The method of claim 11 , wherein the indication is received via a second RRC configuration that indicates at least one of a bandwidth part (BWP) and the cell on which the UE acts as the initiating device for the FBE operation.

19. The method of claim 11 , wherein:

in a case that the UL transmission is scheduled by a random access response (RAR), the indication is indicated by the RAR.

20. The method of claim 11 , wherein:

in a case that the UL transmission is scheduled by a configured grant (CG) configuration and a DCI format 2_0 is not received, the indication is indicated by the CG configuration and a time division duplex (TDD) configuration,

the CG configuration indicates the UL transmission within a number of symbols in front of the first one of the second plurality of FFPs, and

the TDD configuration indicates the number of symbols as UL symbols or flexible symbols.