Method and device for managing control information in NR V2X

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

receiving, from a second device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling a physical sidelink shared channel (PSSCH);

receiving, from the second device through the PSSCH, second SCI and data;

determining that the second SCI has a first type SCI format among at least a first type SCI format and a second type SCI format;

wherein the first type of SCI format includes (i) information representing that hybrid automatic repeat request (HARQ) feedback is enabled, (ii) a zone ID, and (iii) a communication range requirement;

wherein the second type of SCI format includes (i) information representing that HARQ feedback is enabled (ii) a CSI request (iii) a cast type indicator; and

wherein the HARQ feedback mode is negative-only feedback mode and cast type is groupcast due to the second SCI having the first type SCI format; and

transmitting, to the second device through a physical sidelink feedback channel (PSFCH), negative acknowledgement (NACK) feedback in response to the PSSCH not being successfully decoded, based on the determined HARQ feedback mode.

2. The method of claim 1 ,

wherein a format size budget of the first SCI or a format size budget of the second SCI is pre-configured based on at least one of a cast type or a resource pool, and

wherein the number of format sizes of the second SCI is determined within the format size budget of the second SCI.

3. The method of claim 1 , wherein at least one of a configuration of the second SCI or a size of the second SCI is determined differently based on a value included in the first SCI.

4. The method of claim 1 , wherein a plurality of candidate sizes for the second SCI are pre-configured.

5. The method of claim 4 , wherein padding bits are added to a selected one of the candidate sizes for the second SCI until it is equal to a size of the first SCI, based on the number of the plurality of candidate sizes exceeding a format size budget of the second SCI.

6. The method of claim 4 , wherein padding bits are added until a size of any one selected among the plurality of candidate sizes is equal to the largest candidate size among the plurality of candidate sizes, based on the number of the plurality of candidate sizes exceeding a format size budget of the second SCI.

7. The method of claim 1 , wherein transmission of acknowledgment (ACK) feedback is skipped, based on the data being successfully decoded.

8. The method of claim 1 , wherein the cast type indicator is 2 bits.

9. The first device of claim 1 , wherein the cast type indicator is configured to indicate one of a plurality of cast types and HARQ feedback mode combinations including a first combination of Groupcast and ACK/NACK feedback mode, and a second combination of Groupcast and negative-only acknowledgment (NACK) feedback mode.

10. The first device of claim 1 , wherein at least one of a size of the first type of SCI format or a size of the second type of SCI format is determined differently based on a value included in the first SCI.

11. 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 control the one or more transceivers to:

receive, from a second device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling a physical sidelink shared channel (PSSCH);

receive, from the second device through the PSSCH, second SCI and data;

determine that the second SCI has a first type SCI format among at least a first type SCI format and a second type SCI format;

wherein the first type of SCI format includes (i) information representing that hybrid automatic repeat request (HARQ) feedback is enabled, (ii) a zone ID, and (iii) a communication range requirement;

wherein the second type of SCI format includes (i) information representing that HARQ feedback is enabled (ii) a CSI request (iii) a cast type indicator; and

wherein the HARQ feedback mode is negative-only feedback mode and cast type is groupcast due to the second SCI having the first type SCI format; and

transmit, to the second device through a physical sidelink feedback channel (PSFCH), a negative acknowledgement (NACK) feedback in response to the PSSCH not being successfully decoded, based on the determined HARQ feedback mode.

12. A device configured to control a first user equipment (UE), the device comprising:

one or more processors; and

one or more memories operably connectable to the one or more processors and storing instructions,

wherein the one or more processors execute the instructions to:

receive, from a second UE through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling a physical sidelink shared channel (PSSCH);

receive, from the second UE through the PSSCH, second SCI and data;

determine that the second SCI has a first type SCI format among at least a first type SCI format and a second type SCI format;

hybrid automatic repeat request (HARQ) feedback wherein the first type of SCI format includes (i) information representing that hybrid automatic repeat request (HARQ) feedback is enabled, (ii) a zone ID, and (iii) a communication range requirement;

wherein the second type of SCI format includes (i) information representing that HARQ feedback is enabled (ii) a CSI request (iii) a cast type indicator; and

wherein the HARQ feedback mode is negative-only feedback mode and cast type is groupcast due to the second SCI having the first type SCI format; and

transmit, to the second device through a physical sidelink feedback channel (PSFCH), a negative acknowledgement (NACK) feedback in response to the PSSCH not being successfully decoded, based on the determined HARQ feedback mode.