Method and apparatus for performing PSFCH transmission in NR V2X

1. A method for performing wireless communication by a first device, the method comprising:

receiving at least one physical sidelink control channel (PSCCH);

receiving at least one physical sidelink shared channel (PSSCH) related to the at least one PSCCH;

determining a resource related to at least one physical sidelink feedback channel (PSFCH) based on an index of a slot and an index of a subchannel related to the at least one PSSCH;

determining N PSFCHs from among the at least one PSFCH based on a sum of power required to transmit the at least one PSFCH being greater than a maximum transmit power of the first device,

wherein N is an integer that satisfies N 1 ≤N≤N MAX , where N 1 denotes a number of PSFCH transmissions with priorities higher than or equal to a priority, and N MAX denotes a maximum number of PSFCH transmissions of the first device, and

wherein the priority is determined such that a total transmit power related to the PSFCH transmissions with priorities higher than or equal to the priority does not exceed the maximum transmit power of the first device;

determining a transmit power for the N PSFCHs; and

transmitting the N PSFCHs based on the transmit power.

2. The method of claim 1 , wherein, based on a number of PSFCHs scheduled to the first device being greater than a maximum number of PSFCHs that the first device can transmit, the maximum number of PSFCH transmissions is the maximum number of PSFCHs that the first device can transmit.

3. The method of claim 1 , wherein, based on a number of PSFCHs scheduled to the first device being smaller than a maximum number of PSFCHs that the first device can transmit, the maximum number of PSFCH transmissions is a number of PSFCHs scheduled to the first device.

4. The method of claim 1 , wherein the priority is a lowest priority among priorities of the PSFCH transmissions with priorities higher than or equal to the priority.

5. The method of claim 1 , wherein, based on parameters related to Open Loop Power Control (OLPC) that determines a transmit power for a PSFCH being not configured to the first device, the transmit power for the PSFCH is configured to the maximum transmit power of the first device.

6. The method of claim 5 , wherein the transmit power of each of the N PSFCHs is a value in which the maximum transmit power of the first device is equally shared.

7. The method of claim 1 , wherein, based on the at least one PSSCH overlapping with a first channel and a second channel in a time domain, at least one of the at least one PSSCH, the first channel, or the second channel is omitted,

wherein the first channel leads the most in the time domain and the second channel trails the most in the time domain, and

wherein, among priorities related to channels, the priority related to the first channel is the lowest, and the priority related to the second channel is the highest.

8. The method of claim 7 , wherein, based on the priority related to the second channel not being identified, the first channel and the second channel are omitted regardless of the priority related to the channels.

9. The method of claim 7 , wherein, based on the priority related to the second channel not being identified by a medium access control (MAC) layer, information on the priority related to the second channel is transmitted from a physical (PHY) layer to the MAC layer, and

wherein the at least one PSSCH is omitted based on the information on the priority related to the second channel.

10. The method of claim 1 , wherein the at least one PSSCH includes at least one sidelink control information (SCI),

wherein a number of Resource Elements (REs) used to map the at least one SCI is calculated, and

wherein the calculation of the number of REs is performed without considering an overhead related to a pre-configured sidelink (SL) channel state information (CSI)-reference signal (RS).

11. The method of claim 10 , wherein a size of a transport block related to the at least one PSSCH is determined based on an indicator related to a PSFCH overhead, and

wherein a Cyclic Redundancy Check (CRC) related to the at least one SCI includes the indicator.

12. The method of claim 1 , wherein an overhead related to at least one PSFCH resource is not used for derivation of sidelink channel state information (CSI) information.

13. The method of claim 12 , wherein the sidelink CSI information is derived on a reference resource related to sidelink CSI,

wherein the reference resource related to the sidelink CSI is a sidelink slot in which at least one of a PSCCH or a PSSCH triggering a sidelink CSI report is received, and

wherein the reference resource related to the sidelink CSI is a Physical Resource Block (PRB) related to the PSSCH triggering the sidelink CSI report.

14. A first device configured to perform wireless communication, the first device comprising:

one or more memories storing instructions;

one or more transceivers; and

one or more processors connected to the one or more memories and the one or more transceivers, wherein the one or more processors execute the instructions to:

receive at least one physical sidelink control channel (PSCCH);

receive at least one physical sidelink shared channel (PSSCH) related to the at least one PSCCH;

determine a resource related to at least one physical sidelink feedback channel (PSFCH) based on an index of a slot and an index of a subchannel related to the at least one PSSCH;

determine N PSFCHs from among the at least one PSFCH based on a sum of power required to transmit the at least one PSFCH being greater than a maximum transmit power of the first device,

wherein N is an integer that satisfies N 1 <N<N MAX , where N 1 denotes a number of PSFCH transmissions with priorities higher than or equal to a priority, and N MAX denotes a maximum number of PSFCH transmissions of the first device, and

wherein the priority is determined such that a total transmit power related to the PSFCH transmissions with priorities higher than or equal to the priority does not exceed the maximum transmit power of the first device;

determine a transmit power for the N PSFCHs; and

transmit the N PSFCHs based on the transmit power.

15. An apparatus configured to control a first device, the apparatus comprising:

one or more processors; and

one or more memories operably connected to the one or more processors and storing instructions, wherein the one or more processors execute the instructions to:

receive at least one physical sidelink control channel (PSCCH);

receive at least one physical sidelink shared channel (PSSCH) related to the at least one PSCCH;

determine a resource related to at least one physical sidelink feedback channel (PSFCH) based on an index of a slot and an index of a subchannel related to the at least one PSSCH;

determine N PSFCHs from among the at least one PSFCH based on a sum of power required to transmit the at least one PSFCH being greater than a maximum transmit power of the first device,

wherein N is an integer that satisfies N 1 <N<N MAX , where N 1 denotes a number of PSFCH transmissions with priorities higher than or equal to a priority, and N MAX denotes a maximum number of PSFCH transmissions of the first device, and

wherein the priority is determined such that a total transmit power related to the PSFCH transmissions with priorities higher than or equal to the priority does not exceed the maximum transmit power of the first device;

determine a transmit power for the N PSFCHs; and

transmit the N PSFCHs based on the transmit power.