Methods and apparatus to facilitate spatial relation indication for uplink control channel and sounding reference signals
Apparatus, methods, and computer-readable media for facilitating spatial relation indication for uplink control channels and SRS are disclosed herein. An example method for wireless communication at a UE includes determining, based on a rule, a default uplink transmit beam for transmitting an uplink transmission when an uplink transmit beam is not configured by a base station for the uplink transmission. The example method also includes transmitting, to the base station, the uplink transmission on the default uplink transmit beam.
1. A method of wireless communication at a user equipment (UE), comprising:
determining a default uplink transmit beam for transmitting an uplink transmission,
the determining of the default uplink transmit beam including selecting an uplink beam corresponding to a lowest transmission configuration indication (TCI) state identifier of activated TCI states associated with a downlink shared channel; and
transmitting, to a base station, the uplink transmission on the default uplink transmit beam.
2. The method of claim 1 , wherein the uplink transmission comprises a sounding reference signal (SRS).
3. The method of claim 2 , wherein determining the default uplink transmit beam for transmitting the uplink transmission comprises determining a first default uplink transmit beam for transmitting an uplink control channel, the method further comprising:
determining a second default uplink transmit beam for transmitting the SRS.
4. The method of claim 3 , wherein the first default uplink transmit beam is a same uplink beam as the second default uplink transmit beam.
5. The method of claim 1 , wherein parameters for the default uplink transmit beam correspond to a beam for the downlink shared channel.
6. The method of claim 1 , wherein the UE communicates with a plurality of transmit-receive points (TRPs), and wherein for each TRP, determining the default uplink transmit beam is based on a corresponding beam used for receiving respective downlink shared channels.
7. An apparatus for wireless communication at a user equipment (UE), comprising:
a memory; and
at least one processor coupled to the memory and configured to:
determine a default uplink transmit beam for transmitting an uplink transmission,
the determination of the default uplink transmit beam including selecting an uplink beam corresponding to a lowest transmission configuration indication (TCI) state identifier of activated TCI states associated with a downlink shared channel; and
transmit, to a base station, the uplink transmission on the default uplink transmit beam.
8. The apparatus of claim 7 , wherein the uplink transmission comprises a sounding reference signal (SRS).
9. The apparatus of claim 8 , wherein the at least one processor is further configured to:
determine a first default uplink transmit beam for transmitting an uplink control channel; and
determine a second default uplink transmit beam for transmitting the SRS.
10. The apparatus of claim 9 , wherein the first default uplink transmit beam is a same uplink beam as the second default uplink transmit beam.
11. The apparatus of claim 7 , wherein parameters for the default uplink transmit beam correspond to a beam for the downlink shared channel.
12. The apparatus of claim 7 , wherein the UE is in communication with a plurality of transmit-receive points (TRPs), and wherein the at least one processor is configured to determine the default uplink transmit beam for each TRP based on a corresponding beam used for receiving respective downlink shared channels.
13. A method of wireless communication at a base station, comprising:
selecting a beam to monitor for receiving an uplink transmission based on a downlink beam, the selected beam for monitoring corresponding to a lowest transmission configuration indication (TCI) state identifier of activated TCI states associated with a downlink shared channel; and
receiving, from a user equipment (UE), the uplink transmission on the selected beam.
14. The method of claim 13 , wherein the uplink transmission comprises a sounding reference signal (SRS).
15. The method of claim 14 , wherein selecting the beam to monitor for receiving the uplink transmission includes selecting a first beam for monitoring for receiving an uplink control channel, the method further comprising:
selecting a second beam for monitoring for receiving the SRS.
16. The method of claim 15 , wherein the first beam is a same beam as the second beam.
17. The method of claim 13 , wherein parameters of the selected beam for monitoring correspond to the downlink beam for the downlink shared channel.
18. The method of claim 13 , wherein the base station communicates using a plurality of transmit-receive points (TRPs), and wherein for each TRP, selecting the beam to monitor for receiving the uplink transmission is based on a corresponding downlink beam.
19. An apparatus for wireless communication at a base station, comprising:
a memory; and
at least one processor coupled to the memory and configured to:
select a beam to monitor for receiving an uplink transmission based on a downlink beam, the selected beam for monitoring corresponding to a lowest transmission configuration indication (TCI) state identifier of activated TCI states associated with a downlink shared channel; and
receive, from a user equipment (UE), the uplink transmission on the selected beam.
20. The apparatus of claim 19 , wherein the uplink transmission comprises a sounding reference signal (SRS).
21. The apparatus of claim 20 , wherein the at least one processor is further configured to:
select a first beam for monitoring for receiving an uplink control channel; and
select a second beam for monitoring for receiving the SRS.
22. The apparatus of claim 21 , wherein the first beam is a same beam as the second beam.
23. The apparatus of claim 19 , wherein parameters of the selected beam for monitoring correspond to the downlink beam for the downlink shared channel.
24. The apparatus of claim 19 , wherein the base station communicates using a plurality of transmit-receive points (TRPs), and wherein the at least one processor is configured to select the beam for monitoring for receiving the uplink transmission for each TRP based on a corresponding downlink beam.
25. The method of claim 1 , wherein the UE determines the default uplink transmit beam based on an absence of a configuration of an uplink transmit beam by the base station for the uplink transmission, wherein the absence of the configuration of the uplink transmit beam comprises an absence of an explicit configuration of spatial relation information from the base station.
26. The apparatus of claim 7 , wherein the UE determines the default uplink transmit beam based on an absence of a configuration of an uplink transmit beam by the base station for the uplink transmission, wherein the absence of the configuration of the uplink transmit beam comprises an absence of an explicit configuration of spatial relation information from the base station.
27. The method of claim 13 , wherein the base station receives the uplink transmission on the selected beam based on an absence of a configuration of an uplink transmit beam by the base station for the uplink transmission, wherein the absence of the configuration of the uplink transmit beam comprises an absence of an explicit configuration of spatial relation information from the base station.
28. The apparatus of claim 19 , wherein the at least one processor is configured to receive the uplink transmission on the selected beam based on an absence of a configuration of an uplink transmit beam by the base station for the uplink transmission, wherein the absence of the configuration of the uplink transmit beam comprises an absence of an explicit configuration of spatial relation information from the base station.
29. The method of claim 1 , wherein the uplink transmission comprises at least one of an uplink control channel or a scheduling request (SR).
30. The apparatus of claim 7 , wherein the uplink transmission comprises at least one of an uplink control channel or a scheduling request (SR).