Uplink processing techniques for reduced uplink timelines in wireless communications
Methods, systems, and devices for wireless communications are described in which uplink timelines may be reduced by initiating, at a user equipment (UE), uplink transmission processing prior to receipt of an uplink grant for an uplink communication. A UE may identify one or more uplink transmission parameters associated with a reduced uplink transmission timeline for an uplink communication, and use the uplink transmission parameters to initiate processing of the uplink communication prior to receiving an uplink grant from a base station. The uplink transmission parameters may allow for packet preparation at a higher layers (e.g., at a medium access control (MAC) layer or radio link control (RLC) layer) to be started or completed prior to receipt of the uplink grant.
1. A method for wireless communication at a user equipment (UE), comprising:
identifying a first uplink transmission parameter for an uplink communication to a base station, the first uplink transmission parameter associated with an amount of data to be transmitted in the uplink communication;
receiving an uplink retransmission grant from the base station, the uplink retransmission grant indicating a second uplink transmission parameter associated with a reduced uplink retransmission timeline; and
transmitting, responsive to receiving the uplink retransmission grant, a retransmission of the uplink communication to the base station according to the reduced uplink retransmission timeline based at least in part on comparing the first uplink transmission parameter with the second uplink transmission parameter indicated in the uplink retransmission grant.
2. The method of claim 1 , further comprising:
receiving a feedback communication from the base station that indicates the uplink communication was unsuccessfully received at the base station; and
preparing the retransmission of the uplink communication responsive to the feedback communication.
3. The method of claim 2 , wherein transmission and the retransmission of the uplink communication are completed within a predetermined latency budget of 1 millisecond.
4. The method of claim 2 , wherein transmission of the uplink communication uses a first transport block size (TBS), and the retransmission of the uplink communication uses the first TBS, and wherein the first TBS is less than a TBS threshold value associated with the reduced uplink retransmission timeline.
5. The method of claim 2 , wherein transmission of the uplink communication uses a first modulation and coding scheme (MCS), and the retransmission of the uplink communication uses the first MCS.
6. The method of claim 2 , wherein a first time period between receiving an uplink grant and transmitting the uplink communication is longer than a second time period between receiving the feedback communication and retransmitting the uplink communication.
7. The method of claim 6 , wherein the feedback communication is a negative acknowledgment (NACK) feedback or the uplink retransmission grant from the base station.
8. The method of claim 1 , wherein the first uplink transmission parameter comprises one or more of a transport block size (TBS), a modulation order, a modulation and coding scheme (MCS), a fast Fourier transform (FFT) size, a physical uplink shared channel (PUSCH) allocation size in terms of number of resource blocks (RBs) or absolute bandwidth, a number of layers, or any combinations thereof.
9. The method of claim 8 , wherein transmission of the uplink communication uses a first FFT size or PUSCH allocation size that is less than a FFT size or PUSCH allocation size threshold value associated with the reduced uplink retransmission timeline.
10. The method of claim 9 , wherein the FFT size or PUSCH allocation size threshold value is based at least in part on one or more of a capability of the UE or a subcarrier spacing (SCS) associated with the uplink communication.
11. The method of claim 9 , wherein the FFT size or PUSCH allocation size threshold value is defined per component carrier or across an uplink allocation across two or more component carriers.
12. The method of claim 9 , wherein the FFT size or PUSCH allocation size threshold value is based at least in part on a service type associated with the uplink communication or an aggregated allocated bandwidth across two or more logical channels, and wherein the uplink communication is associated with one of the two or more logical channels.
13. The method of claim 8 , wherein the first uplink transmission parameter is known a priori at the UE, and packet preparation at one or more of a medium access control (MAC) layer or a radio link control (RLC) layer is initiated prior to the receiving the uplink retransmission grant.
14. The method of claim 1 , further comprising:
determining, after comparing the first uplink transmission parameter with the second uplink transmission parameter, that the second uplink transmission parameter is different than the first uplink transmission parameter;
reinitiating preparation of the retransmission of the uplink communication based at least in part on the second uplink transmission parameter; and
wherein the transmitting the retransmission of the uplink communication is based on the second uplink transmission parameter.
15. The method of claim 14 , further comprising:
determining that the second uplink transmission parameter exceeds a predetermined uplink transmission parameter threshold value.
16. The method of claim 15 , wherein the predetermined uplink transmission parameter threshold value is based at least in part on one or more of a capability of the UE, a specified threshold value, a configuration provided by the base station, or a retransmission threshold.
17. The method of claim 1 , wherein a first timing between the receiving the uplink retransmission grant and transmitting the retransmission of the uplink communication is reduced relative to a second timing associated with preparing the uplink communication after receiving an uplink grant.
18. A method for wireless communication at a base station, comprising:
identifying a first uplink transmission parameter for an uplink communication from a user equipment (UE) to the base station, the first uplink transmission parameter associated with an amount of data to be transmitted in the uplink communication;
determining an uplink resource allocation for a retransmission of the uplink communication and a second uplink transmission parameter, wherein a timing associated with the retransmission of the uplink communication is based at least in part on a reduced uplink retransmission timeline;
transmitting an uplink retransmission grant to the UE, the uplink retransmission grant indicating the uplink resource allocation and the second uplink transmission parameter; and
monitoring, responsive to transmitting the uplink retransmission grant, for the retransmission of the uplink communication from the UE according to the timing, based at least in part on comparing the first uplink transmission parameter with the second uplink transmission parameter indicated in the uplink retransmission grant.
19. The method of claim 18 , further comprising:
determining, based at least in part on the monitoring, that the uplink communication from the UE is not successfully decoded;
transmitting a feedback communication to the UE that indicates the uplink communication was unsuccessfully received at the base station; and
receiving the retransmission of the uplink communication from the UE, wherein transmission and the retransmission of the uplink communication are completed within a predetermined latency budget.
20. The method of claim 19 , wherein a first time period between transmitting an uplink grant and monitoring for the uplink communication is longer than a second time period between transmitting the feedback communication and receiving the retransmission of the uplink communication.
21. The method of claim 20 , wherein the feedback communication is a negative acknowledgment (NACK) feedback or the uplink retransmission grant.
22. The method of claim 18 , wherein the first uplink transmission parameter comprises one or more of a transport block size (TBS), a modulation order, a modulation and coding scheme (MCS), a fast Fourier transform (FFT) size, a physical uplink shared channel (PUSCH) allocation size in terms of number of resource blocks (RBs) or absolute bandwidth, a number of layers, or any combinations thereof.
23. The method of claim 22 , wherein the uplink communication uses a first FFT size or PUSCH allocation size that is less than a FFT size or PUSCH allocation size threshold value associated with the reduced uplink retransmission timeline.
24. The method of claim 23 , wherein the FFT size or PUSCH allocation size threshold value is based at least in part on one or more of a capability of the UE or a subcarrier spacing (SCS) associated with the uplink communication.
25. The method of claim 23 , wherein the FFT size or PUSCH allocation size threshold value is defined per component carrier or across the uplink resource allocation across two or more component carriers.
26. The method of claim 23 , wherein the FFT size or PUSCH allocation size threshold value is based at least in part on a service type associated with the uplink communication or an aggregated allocated bandwidth across two or more logical channels, and wherein the uplink communication is associated with one of the two or more logical channels.
27. The method of claim 22 , wherein the uplink communication uses a first transport block size (TBS), and the retransmission of the uplink communication uses the first TBS, and wherein the first TBS is less than a TBS threshold value associated with the reduced uplink retransmission timeline.
28. The method of claim 18 , wherein the uplink communication uses a first modulation and coding scheme (MCS), and the retransmission of the uplink communication uses the first MCS.
29. An apparatus for wireless communication 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:
identify a first uplink transmission parameter for an uplink communication to a base station, the first uplink transmission parameter associated with an amount of data to be transmitted in the uplink communication;
receive an uplink retransmission grant from the base station, the uplink retransmission grant indicating a second uplink transmission parameter associated with a reduced uplink retransmission timeline; and
transmit, responsive to receiving the uplink retransmission grant, a retransmission of the uplink communication to the base station according to the reduced uplink retransmission timeline based at least in part on comparing the first uplink transmission parameter with the second uplink transmission parameter indicated in the uplink retransmission grant.
30. An apparatus for wireless communication at a base station, comprising:
a processor,
memory coupled with the processor; and
instructions stored in the memory and executable by the processor to cause the apparatus to:
identify a first uplink transmission parameter for an uplink communication from a user equipment (UE) to the base station, the first uplink transmission parameter associated with an amount of data to be transmitted in the uplink communication;
determine an uplink resource allocation for a retransmission of the uplink communication and a second uplink transmission parameter, wherein a timing associated with the retransmission of the uplink communication is based at least in part on a reduced uplink retransmission timeline;
transmit an uplink retransmission grant to the UE, the uplink retransmission grant indicating the uplink resource allocation and the second uplink transmission parameter; and
monitor, responsive to transmitting the uplink retransmission grant, for the retransmission of the uplink communication from the UE according to the timing, based at least in part on comparing the first uplink transmission parameter with the second uplink transmission parameter indicated in the uplink retransmission grant.