Enhancements on synchronization, random access, and HARQ operation for non-terrestrial networks

1. A user equipment (UE) in a wireless communication system, the UE comprising:

at least one transceiver configured to receive downlink control information (DCI) in a physical downlink control channel (PDCCH); and

at least one processor operably connected to the at least one transceiver, the at least one processor configured to:

determine, based on a first field in the DCI, whether a hybrid automatic repeat request (HARQ) feedback is disabled, and

upon determination that the HARQ feedback is disabled, determine:

that a second field in the DCI is a reserved field if a format of the DCI is a first format, and

that the second field in the DCI is a zero bitwidth field if the format of the DCI is a second format.

2. The UE of claim 1 , wherein the first field is one of a dedicated field for indication of disabling the HARQ feedback using reserved bits in the format of the DCI or an existing field in the format of the DCI, and wherein the existing field can be interpreted for disabling the HARQ feedback.

3. The UE of claim 1 , wherein to determine the second field in the DCI, the at least one processor is configured to determine that the second field is the reserved field when the format of the DCI is one of a DCI format 0_0 or a DCI format 1_0.

4. The UE of claim 1 , wherein to determine the second field in the DCI, the at least one processor is configured to determine that the second field is the zero bitwidth field when the format of the DCI is one of a DCI format 0_1 or a DCI format 1_1.

5. The UE of claim 1 , wherein when the format of the DCI is one of a DCI format 0_0 or a DCI format 0_1, the second field is one of a HARQ feedback number field or transmit power control (TPC) command field for scheduled physical uplink shared channel (PUSCH).

6. The UE of claim 1 , wherein when the format of the DCI is one of a DCI format 1_0 or DCI format 1_1, the second field is one of a HARQ feedback number field, a transmit power control (TPC) command field for scheduled physical uplink control channel (PUCCH), a PUCCH resource indicator field, or a PDSCH-to-HARQ feedback timing indicator field.

7. The UE of claim 1 , wherein:

the at least one processor is further configured to generate a higher layer parameter that comprises assistance information related to HARQ operation, wherein the assistance information includes at least one of soft buffer information for reception, a request for disabling the HARQ feedback, a request for enabling the HARQ feedback, a request for increasing a number of the HARQ feedback, or a request for decreasing the number of the HARQ feedback, and

the at least one transceiver is further configured to transmit the higher layer parameter over an uplink channel.

8. A base station (BS) comprising:

a transceiver configured to transmit downlink control information (DCI) in a physical downlink control channel (PDCCH); and

a processor operably connected to the transceiver, the processor configured to:

determine whether a hybrid automatic repeat request (HARQ) feedback is disabled, and

generate the DCI with a first field indicating that the HARQ feedback is disabled,

wherein, for the HARQ feedback being disabled, the DCI includes a second field that is:

a reserved field if a format of the DCI is a first format, and

a zero bitwidth field if the format of the DCI is a second format.

9. The BS of claim 8 , wherein the first field is one of a dedicated field for indication of disabling the HARQ feedback using reserved bits in the format of the DCI or an existing field in the format of the DCI, and wherein the existing field can be interpreted for disabling the HARQ feedback.

10. The BS of claim 8 , wherein the second field is determined to be the reserved field when the format of the DCI is one of a DCI format 0_0 or a DCI format 1_0.

11. The BS of claim 8 , wherein the second field is determined to be the zero bitwidth field when the format of the DCI is one of a DCI format 0_1 or a DCI format 1_1.

12. The BS of claim 8 , wherein when the format of the DCI is one of a DCI format 0_0 or a DCI format 0_1, the second field is one of a HARQ feedback number field or transmit power control (TPC) command field for scheduled physical uplink shared channel (PUSCH).

13. The BS of claim 8 , wherein when the format of the DCI is one of a DCI format 1_0 or DCI format 1_1, the second field is one of a HARQ feedback number field, a transmit power control (TPC) command field for scheduled physical uplink control channel (PUCCH), a PUCCH resource indicator field, or a PDSCH-to-HARQ feedback timing indicator field.

14. The BS of claim 8 , wherein the transceiver is further configured to receive a higher layer parameter over an uplink channel, the higher layer parameter comprising assistance information related to HARQ operation, and wherein the assistance information includes at least one of soft buffer information for reception, a request for disabling the HARQ feedback, a request for enabling the HARQ feedback, a request for increasing a number of the HARQ feedback, or a request for decreasing the number of the HARQ feedback.

15. A method for managing hybrid automatic repeat request (HARQ) transmissions in a wireless communication system, the method comprising:

receiving downlink control information (DCI) in a physical downlink control channel (PDCCH);

determining, based on a first field in the DCI, whether a hybrid automatic repeat request (HARQ) feedback is disabled; and

upon determination that the HARQ feedback is disabled, determining

that a second field in the DCI is a reserved field if a format of the DCI is a first format, and

that the second field in the DCI is a zero bitwidth field if the format of the DCI is a second format.

16. The method of claim 15 , wherein the first field is one of a dedicated field for indication of disabling the HARQ feedback using reserved bits in the format of the DCI or an existing field in the format of the DCI, and wherein the existing field can be interpreted for disabling the HARQ feedback.

17. The method of claim 15 , wherein determining whether HARQ feedback is disabled comprises determining that the second field is the reserved field when the format of the DCI is one of a DCI format 0_0 or a DCI format 1_0, and that the second field is the zero bitwidth field when the format of the DCI is one of a DCI format 0_1 or a DCI format 1_1.

18. The method of claim 15 , wherein when the format of the DCI is one of a DCI format 0_0 or a DCI format 0_1, the second field is one of a HARQ feedback number field or transmit power control (TPC) command field for scheduled physical uplink shared channel (PUSCH).

19. The method of claim 15 , wherein when the format of the DCI is one of a DCI format 1_0 or DCI format 1_1, the second field is one of a HARQ feedback number field, a transmit power control (TPC) command field for scheduled physical uplink control channel (PUCCH), a PUCCH resource indicator field, or a PDSCH-to-HARQ feedback timing indicator field.

20. The method of claim 15 , comprising:

generating a higher layer parameter that comprises assistance information related to HARQ operation, wherein the assistance information includes at least one of soft buffer information for reception, a request for disabling the HARQ feedback, a request for enabling the HARQ feedback, a request for increasing a number of the HARQ feedback, or a request for decreasing the number of the HARQ feedback; and

transmitting the higher layer parameter over an uplink channel.