Outer-loop feedback support for low error rates
Methods, systems, and devices for wireless communications are described which may enable a user equipment (UE) and a base station to use outer-loop feedback support to reach a desired error rate for low latency communications. For example, a base station may transmit a proxy acknowledgement feedback configuration to a UE for communications associated with a low target error rate. In some cases, after receiving the communications from the base station, the UE may receive secondary communications from the base station. The UE may then decode the first and/or second communications according to the proxy acknowledgement feedback configuration and/or a normal acknowledgement feedback configuration and may determine a proxy acknowledgement feedback based on the decoding. Further, the UE may transmit the proxy and/or normal acknowledgement feedback to the base station, which may update outer-loop power settings for the low latency communications based on the acknowledgement feedback.
1. A method for wireless communications at a user equipment (UE), comprising:
receiving, from a base station, a proxy acknowledgement feedback configuration for communications associated with a target error rate that is below a threshold target error rate;
receiving, from the base station, the communications associated with the target error rate;
transmitting, to the base station, a first acknowledgement feedback for the communications based at least in part on the target error rate and on decoding the communications; and
transmitting, to the base station, a second acknowledgement feedback for the communications based at least in part on the proxy acknowledgement feedback configuration, wherein the second acknowledgement feedback is associated with a proxy target error rate that is greater than the target error rate.
2. The method of claim 1 , further comprising:
receiving an indication that the UE is to determine the second acknowledgement feedback based on a subset of log likelihood ratios (LLRs) to be used for the communications.
3. The method of claim 2 , further comprising:
receiving, via the indication, a proxy down-sampling rate that is less than a down-sampling rate of the communications;
decoding the communications according to the proxy down-sampling rate, wherein the subset of LLRs includes LLRs decoded in accordance with the proxy down-sampling rate; and
determining the second acknowledgement feedback based at least in part on the decoding in accordance with the proxy down-sampling rate.
4. The method of claim 2 , further comprising:
decoding a random selection of LLRs of the communications, wherein the subset of LLRs includes the random selection of LLRs; and
determining the second acknowledgement feedback based at least in part on the decoding of the random selection of LLRs.
5. The method of claim 2 , wherein receiving the indication comprises:
receiving the indication as part of the proxy acknowledgement feedback configuration via radio resource control (RRC) signaling or as part of a downlink control information (DCI) message.
6. The method of claim 1 , further comprising:
receiving an indication that the UE is to determine the second acknowledgement feedback based on an intermediate decoding of the communications.
7. The method of claim 6 , further comprising:
receiving, via the indication, a number of decoding iterations to be used for the intermediate decoding, wherein the number of decoding iterations is less than a total number of decoding iterations to be used by the UE for decoding an entirety of the communications and is associated with the intermediate decoding;
decoding the communications according to the number of decoding iterations; and
determining the second acknowledgement feedback based at least in part on the decoding by the number of decoding iterations.
8. The method of claim 7 , wherein the number of decoding iterations corresponds to the proxy target error rate that is greater than the target error rate.
9. The method of claim 6 , wherein receiving the indication comprises:
receiving the indication as part of the proxy acknowledgement feedback configuration via radio resource control (RRC) signaling or as part of a downlink control information (DCI) message.
10. The method of claim 1 , further comprising:
multiplexing the first acknowledgement feedback with the second acknowledgement feedback.
11. The method of claim 10 , wherein the second acknowledgement feedback is transmitted less frequently than the first acknowledgement feedback.
12. The method of claim 1 , wherein the communications associated with the target error rate that is below the threshold target error rate comprise ultra-reliable low latency communications (URLLC).
13. An apparatus for wireless communications at a user equipment (UE), comprising:
a processor,
memory coupled with the processor; and
instructions stored in the memory and executable by the processor to cause the apparatus to:
receive, from a base station, a proxy acknowledgement feedback configuration for communications associated with a target error rate that is below a threshold target error rate;
receive, from the base station, the communications associated with the target error rate;
transmit, to the base station, a first acknowledgement feedback for the communications based at least in part on the target error rate and on decoding the communications; and
transmit, to the base station, a second acknowledgement feedback for the communications based at least in part on the proxy acknowledgement feedback configuration, wherein the second acknowledgement feedback is associated with a proxy target error rate that is greater than the target error rate.
14. The apparatus of claim 13 , wherein the instructions are further executable by the processor to cause the apparatus to:
receive an indication that the UE is to determine the second acknowledgement feedback based on a subset of log likelihood ratios (LLRs) to be used for the communications.
15. The apparatus of claim 14 , wherein the instructions are further executable by the processor to cause the apparatus to:
receive, via the indication, a proxy down-sampling rate that is less than a down-sampling rate of the communications;
decode the communications according to the proxy down-sampling rate, wherein the subset of LLRs includes LLRs decoded in accordance with the proxy down-sampling rate; and
determine the second acknowledgement feedback based at least in part on the decoding in accordance with the proxy down-sampling rate.
16. The apparatus of claim 14 , wherein the instructions are further executable by the processor to cause the apparatus to:
decode a random selection of LLRs of the communications, wherein the subset of LLRs includes the random selection of LLRs; and
determine the second acknowledgement feedback based at least in part on the decoding of the random selection of LLRs.
17. The apparatus of claim 14 , wherein the instructions to receive the indication are executable by the processor to cause the apparatus to:
receive the indication as part of the proxy acknowledgement feedback configuration via radio resource control (RRC) signaling or as part of a downlink control information (DCI) message.
18. The apparatus of claim 13 , wherein the instructions are further executable by the processor to cause the apparatus to:
receive an indication that the UE is to determine the second acknowledgement feedback based on an intermediate decoding of the communications.
19. The apparatus of claim 18 , wherein the instructions are further executable by the processor to cause the apparatus to:
receive, via the indication, a number of decoding iterations to be used for the intermediate decoding, wherein the number of decoding iterations is less than a total number of decoding iterations to be used by the UE for decoding an entirety of the communications and is associated with the intermediate decoding;
decode the communications according to the number of decoding iterations; and
determine the second acknowledgement feedback based at least in part on the decoding by the number of decoding iterations.
20. The apparatus of claim 18 , wherein the instructions to receive the indication are executable by the processor to cause the apparatus to:
receive the indication as part of the proxy acknowledgement feedback configuration via radio resource control (RRC) signaling or as part of a downlink control information (DCI) message.
21. The apparatus of claim 18 , wherein a number of decoding iterations corresponds to the proxy target error rate that is greater than the target error rate.
22. The apparatus of claim 13 , wherein the instructions are further executable by the processor to cause the apparatus to:
multiplex the first acknowledgement feedback with the second acknowledgement feedback.
23. The apparatus of claim 22 , wherein the second acknowledgement feedback is transmitted less frequently than the first acknowledgement feedback.
24. The apparatus of claim 13 , wherein the communications associated with the target error rate that is below the threshold target error rate comprise ultra reliable low latency communications (URLLC).
25. An apparatus for wireless communications at a user equipment (UE), comprising:
means for receiving, from a base station, a proxy acknowledgement feedback configuration for communications associated with a target error rate that is below a threshold target error rate;
means for receiving, from the base station, the communications associated with the target error rate;
means for transmitting, to the base station, a first acknowledgement feedback for the communications based at least in part on the target error rate and on decoding the communications; and
means for transmitting, to the base station, a second acknowledgement feedback for the communications based at least in part on the proxy acknowledgement feedback configuration, wherein the second acknowledgement feedback is associated with a proxy target error rate that is greater than the target error rate.
26. A non-transitory computer-readable medium storing code for wireless communications at a user equipment (UE), the code comprising instructions executable by a processor to:
receive, from a base station, a proxy acknowledgement feedback configuration for communications associated with a target error rate that is below a threshold target error rate;
receive, from the base station, the communications associated with the target error rate;
transmit, to the base station, a first acknowledgement feedback for the communications based at least in part on the target error rate and on decoding the communications; and
transmit, to the base station, a second acknowledgement feedback for the communications based at least in part on the proxy acknowledgement feedback configuration, wherein the second acknowledgement feedback is associated with a proxy target error rate that is greater than the target error rate.