User equipment and method of hybrid automatic repeat request option configuration of same

1. A user equipment, comprising:

a memory;

a transceiver; and

a processor coupled to the memory and the transceiver, wherein the processor is configured to derive at least one hybrid automatic repeat request (HARQ) feedback option based on at least one of the following:

group-related information from an upper layer;

a radio resource control (RRC) state of the user equipment; or

a coverage status of the user equipment;

wherein the at least one HARQ feedback option comprises at least one of the following:

a first option, wherein the transceiver is configured to transmit a hybrid automatic repeat request negative acknowledgement (HARQ-NACK) on a physical sidelink feedback channel (PSFCH) if the processor fails to decode a corresponding transport block (TB) after decoding an associated physical sidelink control channel (PSCCH) and the transceiver is configured to transmit no signal on the PSFCH otherwise; or

a second option, wherein the transceiver is configured to transmit a hybrid automatic repeat request acknowledgement (HARQ-ACK) on the PSFCH if the processor successfully decodes the corresponding TB, and the transceiver is configured to transmit the HARQ-NACK on the PSFCH if the processor does not successfully decode the corresponding TB after decoding the associated PSCCH which targets the user equipment;

wherein when the processor derives the at least one HARQ feedback option based on the group-related information from the upper layer, the processor is configured to follow a rule that when a number of user equipments is unknown or known, the processor is configured to select an option of the at least one HARQ feedback option;

wherein when the number of user equipments is unknown, the processor is configured to select the first option.

2. The user equipment of claim 1 , wherein the group-related information comprises whether a number of user equipments in a group-cast communication is known or not.

3. The user equipment of claim 2 , wherein the group-related information comprises the number of user equipments in the group-cast communication if the number of user equipments in the group-cast communication is known.

4. The user equipment of claim 1 , wherein when the number of the user equipments is known, the processor is configured to select the second option.

5. The user equipment of claim 1 , wherein when the processor derives the at least one HARQ feedback option based on the group-related information from the upper layer, the processor is configured to follow a rule that when a number of user equipments is known and is for a value, the processor is configured to select an option of the at least one HARQ feedback option.

6. The user equipment of claim 5 , wherein if the number of user equipments is known and ranges between a first value and a second value, the processor is configured to select the second option, or otherwise the processor is configured to select the first option.

7. The user equipment of claim 1 , wherein the processor is further configured to combine with a quality of service (QOS) characteristic to decide on the HARQ feedback option.

8. The user equipment of claim 7 , wherein the QoS characteristic comprises at least one of the following:

a quasi co-location indicator (PQI);

a resource type;

a priority level;

a packet delay budget;

a packet error rate;

an averaging window; or

a maximum data burst volume.

9. The user equipment of claim 8 , wherein the resource type comprises a guaranteed bit rate (GBR), a delay critical GBR, or a non-GBR.

10. The user equipment of claim 8 , wherein the averaging window is for GBR and delay-critical GBR resource type only.

11. The user equipment of claim 8 , wherein the maximum data burst volume is for delay-critical GBR resource type only.

12. The user equipment of claim 8 , wherein when a POI value is a specific value, the processor is configured to select the first option; or when the PQI value is not the specific value, the processor is configured to select the second option.

13. The user equipment of claim 8 , wherein when the priority level is a specific level, the processor is configured to select the first option; or when the priority level is not the specific value, the processor is configured to select the second option.

14. The user equipment of claim 1 , wherein when the processor derives the at least one HARQ feedback option based on the group-related information from the upper layer, the processor is configured to follow a rule specified in a specification, in a pre-configuration, or in a system information block (SIB).

15. The user equipment of claim 1 , wherein when the processor derives the at least one HARQ feedback option based on the RRC state of the user equipment or the coverage status of the user equipment, the processor is configured to follow a rule that when a number of user equipments is unknown or known, the processor is configured to select an option of the at least one HARQ feedback option.

16. The user equipment of claim 15 , wherein when the user equipment is in out of coverage case, the processor is configured to select the first option.

17. A method for hybrid automatic repeat request (HARQ) option configuration, comprising deriving, by a user equipment, at least one HARQ feedback option based on at least one of the following:

group-related information from an upper layer;

a radio resource control (RRC) state of the user equipment; or

a coverage status of the user equipment;

wherein the at least one HARQ feedback option comprises at least one of the following:

a first option, wherein the user equipment transmits a hybrid automatic repeat request negative acknowledgement (HARQ-NACK) on a physical sidelink feedback channel (PSFCH) if the user equipment fails to decode a corresponding transport block (TB) after decoding an associated physical sidelink control channel (PSCCH) and transmits no signal on the PSFCH otherwise; or

a second option, wherein the user equipment transmits a hybrid automatic repeat request acknowledgement (HARQ-ACK) on the PSFCH if the user equipment successfully decodes the corresponding TB, and the transceiver is configured to transmit the HARQ-NACK on the PSFCH if the processor does not successfully decode the corresponding TB after decoding the associated PSCCH which targets the user equipment;

wherein when the processor derives the at least one HARQ feedback option based on the group-related information from the upper layer, the user equipment follows a rule that when a number of user equipments is unknown or known, and the user equipment selects an option of the at least one HARQ feedback option;

wherein when the number of user equipments is unknown, the user equipment selects the first option.

18. A non-transitory machine-readable storage medium having instructions stored thereon that when executed by a user equipment, cause the user equipment to perform deriving at least one hybrid automatic repeat request (HARQ) feedback option based on at least one of the following:

group-related information from an upper layer;

a radio resource control (RRC) state of the user equipment; or

a coverage status of the user equipment;

wherein the at least one HARQ feedback option comprises at least one of the following:

a first option, wherein the user equipment transmits a hybrid automatic repeat request negative acknowledgement (HARQ-NACK) on a physical sidelink feedback channel (PSFCH) if the user equipment fails to decode a corresponding transport block (TB) after decoding an associated physical sidelink control channel (PSCCH) and transmits no signal on the PSFCH otherwise; or

a second option, wherein the user equipment transmits a hybrid automatic repeat request acknowledgement (HARQ-ACK) on the PSFCH if the user equipment successfully decodes the corresponding TB, and the transceiver is configured to transmit the HARQ-NACK on the PSFCH if the processor does not successfully decode the corresponding TB after decoding the associated PSCCH which targets the user equipment;

wherein when the processor derives the at least one HARQ feedback option based on the group-related information from the upper layer, the user equipment follows a rule that when a number of user equipments is unknown or known, and the user equipment selects an option of the at least one HARQ feedback option;

wherein when the number of user equipments is unknown, the user equipment selects the first option.