Feedback processing techniques in wireless transmissions

1. A method for wireless communication, comprising:

identifying a processing timeline for a user equipment (UE) to transmit a hybrid acknowledgment repeat request (HARQ) feedback transmission in response to a downlink transmission, the processing timeline comprising a number of transmission time intervals (TTIs) between the downlink transmission and an uplink transmission that includes the HARQ feedback;

determining a configuration establishing a number of HARQ processes for use by the UE, the number of HARQ processes based at least in part on the processing timeline, a timing advance (TA) of the UE, and a duration of the TTIs associated with the HARQ feedback transmission, and wherein the number of HARQ processes is set to be greater than or equal to twice the number of TTIs; and

transmitting the configuration to the UE.

2. The method of claim 1 , wherein the determining the configuration further comprises:

identifying a processing capability of the UE, and

determining the number of HARQ processes based at least in part on the processing capability of the UE and the TA of the UE.

3. The method of claim 1 , wherein the determining the configuration further comprises:

identifying a threshold TA value for setting the number of HARQ processes at the UE;

comparing the TA of the UE to the threshold TA value; and

setting a first number of HARQ processes or a second number of HARQ processes for use by the UE based at least in part on whether the TA of the UE is less than or greater than the threshold TA value, wherein the first number of HARQ processes is less than the second number of HARQ processes.

4. The method of claim 1 , wherein the determining the configuration further comprises:

identifying the TA of the UE based on a first TA value for transmissions between the UE and a baseband unit and a second TA value for transmissions between the baseband unit and a central network node, and wherein the number of HARQ processes is based at least in part on the second TA value, the first TA value, or any combination thereof.

5. The method of claim 4 , wherein the determining the configuration further comprises:

comparing the second TA value to a threshold TA value, and wherein the number of HARQ processes is further determined based at least in part on the comparing.

6. The method of claim 1 , wherein the identifying the processing timeline further comprises:

determining a maximum TA value for the UE; and

determining the processing timeline based at least in part on the maximum TA value.

7. The method of claim 6 , wherein the processing timeline is further based at least in part on a processing capability of the UE.

8. The method of claim 1 , wherein the HARQ feedback transmission is associated with a four-bit HARQ ID.

9. The method of claim 1 , further comprising:

configuring a round trip time (RTT) for the HARQ feedback transmission and an associated retransmission of the downlink transmission, the RTT based on the processing timeline irrespective of the number of HARQ processes.

10. The method of claim 1 , wherein the transmitting the configuration to the UE comprises transmitting radio resource control (RRC) signaling to the UE or downlink control information (DCI) to the UE that includes configuration information.

11. A method for wireless communication, comprising:

identifying, at a UE, a timing advance (TA) for transmissions between the UE and a base station;

transmitting an indication of the TA to the base station; and

receiving configuration information from the base station that indicates a number of hybrid acknowledgment repeat request (HARQ) processes that are to be configured at the UE based at least in part on the TA and a duration of transmission time intervals (TTIs) associated with the HARQ processes, wherein a processing timeline between a downlink transmission from the base station and an uplink transmission to the base station that includes HARQ feedback for the downlink transmission corresponds to a number of TTIs, and the number of HARQ processes is set to be greater than or equal to twice the number of TTIs.

12. The method of claim 11 , further comprising:

receiving the processing timeline in the configuration information, and wherein the processing timeline is based at least in part on the duration of the TTIs.

13. The method of claim 12 , wherein the processing timeline is further based at least in part on a processing capability of the UE.

14. The method of claim 12 , further comprising:

receiving the downlink transmission from the base station;

processing the downlink transmission according to a first HARQ process to generate acknowledgment/negative-acknowledgment (ACK/NACK) feedback, the first HARQ process associated with a four-bit HARQ ID; and

transmitting the ACK/NACK feedback according to the processing timeline.

15. The method of claim 11 , further comprising:

transmitting an indication of a processing capability of the UE to the base station, and wherein the number of HARQ processes is further based at least in part on the processing capability.

16. The method of claim 11 , wherein the configuration information comprises a threshold TA value for setting the number of HARQ processes at the UE, and wherein the method further comprises:

comparing the TA to the threshold TA value; and

setting a first number of HARQ processes or a second number of HARQ processes based at least in part on whether the TA is less than or greater than the threshold TA value, wherein the first number of HARQ processes is less than the second number of HARQ processes.

17. The method of claim 11 , further comprising:

configuring a plurality of soft buffers for buffering received transmissions associated with one or more of the HARQ processes, a number of the soft buffers based at least in part on the number of TTIs in the processing timeline or the number of HARQ processes.

18. The method of claim 11 , wherein the configuration information further comprises an indication of a round trip time (RTT) for HARQ feedback transmissions and associated retransmissions, the RTT based on a processing timeline for HARQ feedback and irrespective of the number of HARQ processes.

19. An apparatus for wireless communication, comprising:

a processor;

memory in electronic communication with the processor; and

instructions stored in the memory and operable, when executed by the processor, to cause the apparatus to:

identify a processing timeline for a UE to transmit a HARQ feedback transmission in response to a downlink transmission, the processing timeline comprising a number of transmission time intervals (TTIs) between the downlink transmission and an uplink transmission that includes the HARQ feedback;

determine a configuration establishing a number of HARQ processes for use by the UE, the number of HARQ processes based at least in part on the processing timeline, a TA of the UE, and a duration of TTIs associated with the HARQ feedback transmission, and wherein the number of HARQ processes is set to be greater than or equal to twice the number of TTIs; and

transmit the configuration to the UE.

20. The apparatus of claim 19 , wherein the instructions are further executable by the processor to cause the apparatus to:

identify a processing capability of the UE, and

determine the number of HARQ processes based at least in part on the processing capability of the UE and the TA of the UE.

21. The apparatus of claim 19 , wherein the instructions are further executable by the processor to cause the apparatus to:

identify a threshold TA value for setting the number of HARQ processes at the UE;

compare the TA of the UE to the threshold TA value; and

set a first number of HARQ processes or a second number of HARQ processes for use by the UE based at least in part on whether the TA of the UE is less than or greater than the threshold TA value, wherein the first number of HARQ processes is less than the second number of HARQ processes.

22. The apparatus of claim 19 , wherein the instructions are further executable by the processor to cause the apparatus to:

identify the TA of the UE based on a first TA value for transmissions between the UE and a baseband unit and a second TA value for transmissions between the baseband unit and a central network node, and wherein the number of HARQ processes is based at least in part on the second TA value, the first TA value, or any combination thereof.

23. The apparatus of claim 19 , wherein the instructions are further executable by the processor to cause the apparatus to:

determine a maximum TA value for the UE; and

determine the processing timeline based at least in part on the maximum TA value.

24. An apparatus for wireless communication, comprising:

a processor;

memory in electronic communication with the processor; and

instructions stored in the memory and operable, when executed by the processor, to cause the apparatus to:

identify, at a UE, a TA for transmissions between the UE and a base station;

transmit an indication of the TA to the base station; and

receive configuration information from the base station that indicates a number of HARQ processes that are to be configured at the UE based at least in part on the TA and a duration of transmission time intervals (TTIs) associated with the HARQ processes, wherein a processing timeline between a downlink transmission from the base station and an uplink transmission to the base station that includes HARQ feedback for the downlink transmission corresponds to a number of TTIs, and the number of HARQ processes is set to be greater than or equal to twice the number of TTIs.

25. The apparatus of claim 24 , wherein the instructions are further executable by the processor to cause the apparatus to:

receive the processing timeline in the configuration information, and wherein the processing timeline is based at least in part on the duration of the TTIs.

26. The apparatus of claim 25 , wherein the instructions are further executable by the processor to cause the apparatus to:

receive the downlink transmission from the base station;

process the downlink transmission according to a first HARQ process to generate acknowledgment/negative-acknowledgment (ACK/NACK) feedback, the first HARQ process associated with a four-bit HARQ ID; and

transmit the ACK/NACK feedback according to the processing timeline.

27. The apparatus of claim 24 , wherein the instructions are further executable by the processor to cause the apparatus to:

transmit an indication of a processing capability of the UE to the base station, and wherein the number of HARQ processes is further based at least in part on the processing capability.

28. The apparatus of claim 24 , wherein the instructions are further executable by the processor to cause the apparatus to:

configure a plurality of soft buffers for buffering received transmissions associated with one or more of the HARQ processes, a number of the soft buffers based at least in part on the number of TTIs in the processing timeline or the number of HARQ processes.