Uplink beam management using mixed downlink and uplink reference signals

1. A method of wireless communication performed by a user equipment (UE), comprising:

transmitting, to a base station, a report that includes measurements associated with one or more downlink reference signals, wherein the one or more downlink reference signals are received using a set of candidate downlink beams;

transmitting one or more uplink reference signals, wherein the one or more uplink reference signals are transmitted using a set of candidate uplink beams;

receiving, from the base station, indicator indexing information that indicates a mapping among a set of indicators, the set of candidate downlink beams used to receive the one or more downlink reference signals, and the set of candidate uplink beams used to transmit the one or more uplink reference signals; and

receiving, from the base station, information that indicates, among the set of candidate downlink beams and the set of candidate uplink beams, a best uplink beam to use for one or more uplink transmissions based at least in part on the measurements associated with the one or more downlink reference signals and measurements associated with the one or more uplink reference signals.

2. The method of claim 1 , wherein the one or more downlink reference signals and the one or more uplink reference signals used to select the best uplink beam are within a time window prior to or after a downlink message received from the base station or an uplink message transmitted by the UE.

3. The method of claim 1 , wherein one or more of resources or configuration information associated with the one or more downlink reference signals and the one or more uplink reference signals used to select the best uplink beam are indicated in a downlink message received from the base station.

4. The method of claim 1 , wherein at least one beam included in the set of candidate downlink beams is also included in the set of candidate uplink beams.

5. The method of claim 1 , further comprising:

identifying the best uplink beam indicated by the base station based at least in part on an indicator used to indicate the best uplink beam and the indicator indexing information; and

setting an uplink spatial filter for the one or more uplink transmissions based at least in part on the best uplink beam mapped to the indicator.

6. The method of claim 1 , further comprising:

receiving a single downlink control information (DCI) message to configure reception of the one or more downlink reference signals and transmission of the one or more uplink reference signals, wherein the single DCI message further configures one or more of a switching gap between the reception of the one or more downlink reference signals and the transmission of the one or more uplink reference signals, or settings associated with the report that includes the measurements associated with the one or more downlink reference signals.

7. The method of claim 1 , wherein the one or more downlink reference signals and the one or more uplink reference signals are associated with one or more of a common transmit receive point (TRP), different TRPs that have a common physical cell identity (PCI), different TRPs that have different PCIs, different component carriers, or a switching time that is based at least in part on one or more downlink or uplink demodulation reference signals.

8. A method of wireless communication performed by a base station, comprising:

receiving, from a user equipment (UE), a report that includes measurements associated with one or more downlink reference signals that are received by the UE using a set of candidate downlink beams;

determining measurements associated with one or more uplink reference signals that are transmitted by the UE using a set of candidate uplink beams;

transmitting, to the UE, indicator indexing information that indicates a mapping among a set of indicators, the set of candidate downlink beams used to receive the one or more downlink reference signals, and the set of candidate uplink beams used to transmit the one or more uplink reference signals; and

transmitting, to the UE, information that indicates, among the set of candidate downlink beams and the set of candidate uplink beams, a best uplink beam to use for one or more uplink transmissions based at least in part on the measurements associated with the one or more downlink reference signals and the measurements associated with the one or more uplink reference signals.

9. The method of claim 8 , wherein the one or more downlink reference signals and the one or more uplink reference signals used to select the best uplink beam are within a time window prior to or after a downlink message transmitted to the UE or an uplink message transmitted by the UE.

10. The method of claim 8 , further comprising:

transmitting, to the UE, a downlink message indicating one or more of resources or configuration information associated with the one or more downlink reference signals and the one or more uplink reference signals used to select the best uplink beam.

11. The method of claim 8 , wherein at least one beam included in the set of candidate downlink beams is also included in the set of candidate uplink beams, and wherein the method further comprises:

determining the best uplink beam based at least in part on a delta between a first measurement associated with a downlink reference signal received by the UE using the at least one beam and a second measurement associated with an uplink reference signal transmitted by the UE using the at least one beam.

12. The method of claim 8 , wherein an uplink spatial filter for the one or more uplink transmissions is based at least in part on an indicator used to indicate the best uplink beam and the indicator indexing information.

13. The method of claim 8 , further comprising:

transmitting, to the UE, a single downlink control information (DCI) message to configure reception of the one or more downlink reference signals by the UE and transmission of the one or more uplink reference signals by the UE, wherein the single DCI message further configures one or more of a switching gap between the reception of the one or more downlink reference signals and the transmission of the one or more uplink reference signals, or settings associated with the report that includes the measurements associated with the one or more downlink reference signals.

14. The method of claim 8 , wherein the one or more downlink reference signals and the one or more uplink reference signals are associated with a common transmit receive point (TRP), different TRPs that have a common physical cell identity (PCI), or different TRPs that have different PCIs, different component carriers, or a switching time that is based at least in part on one or more downlink or uplink demodulation reference signals.

15. A user equipment (UE) for wireless communication, comprising:

a memory; and

one or more processors coupled to the memory, the memory and the one or more processors configured to:

transmit, to a base station, a report that includes measurements associated with one or more downlink reference signals, wherein the one or more downlink reference signals are received using a set of candidate downlink beams;

transmit one or more uplink reference signals, wherein the one or more uplink reference signals are transmitted using a set of candidate uplink beams;

receive, from the base station, indicator indexing information that indicates a mapping among a set of indicators, the set of candidate downlink beams used to receive the one or more downlink reference signals, and the set of candidate uplink beams used to transmit the one or more uplink reference signals; and

receive, from the base station, information that indicates, among the set of candidate downlink beams and the set of candidate uplink beams, a best uplink beam to use for one or more uplink transmissions based at least in part on the measurements associated with the one or more downlink reference signals and measurements associated with the one or more uplink reference signals.

16. The UE of claim 15 , wherein the one or more downlink reference signals and the one or more uplink reference signals used to select the best uplink beam are within a time window prior to or after a downlink message received from the base station or an uplink message transmitted by the UE.

17. The UE of claim 15 , wherein one or more of resources or configuration information associated with the one or more downlink reference signals and the one or more uplink reference signals used to select the best uplink beam are indicated in a downlink message received from the base station.

18. The UE of claim 15 , wherein at least one beam included in the set of candidate downlink beams is also included in the set of candidate uplink beams.

19. The UE of claim 15 , wherein the memory and the one or more processors are further configured to:

identify the best uplink beam indicated by the base station based at least in part on an indicator used to indicate the best uplink beam and the indicator indexing information; and

set an uplink spatial filter for the one or more uplink transmissions based at least in part on the best uplink beam mapped to the indicator.

20. The UE of claim 15 , wherein the memory and the one or more processors are further configured to:

receive a single downlink control information (DCI) message to configure reception of the one or more downlink reference signals and transmission of the one or more uplink reference signals, wherein the single DCI message further configures one or more of a switching gap between the reception of the one or more downlink reference signals and the transmission of the one or more uplink reference signals, or settings associated with the report that includes the measurements associated with the one or more downlink reference signals.

21. A base station for wireless communication, comprising:

a memory; and

one or more processors coupled to the memory, the memory and the one or more processors configured to:

receive, from a user equipment (UE), a report that includes measurements associated with one or more downlink reference signals that are received by the UE using a set of candidate downlink beams;

determine measurements associated with one or more uplink reference signals that are transmitted by the UE using a set of candidate uplink beams;

transmit, to the UE, indicator indexing information that indicates a mapping among a set of indicators, the set of candidate downlink beams used to receive the one or more downlink reference signals, and the set of candidate uplink beams used to transmit the one or more uplink reference signals; and

transmit, to the UE, information that indicates, among the set of candidate downlink beams and the set of candidate uplink beams, a best uplink beam to use for one or more uplink transmissions based at least in part on the measurements associated with the one or more downlink reference signals and the measurements associated with the one or more uplink reference signals.

22. The base station of claim 21 , wherein the one or more downlink reference signals and the one or more uplink reference signals used to select the best uplink beam are within a time window prior to or after a downlink message transmitted to the UE or an uplink message transmitted by the UE.

23. The base station of claim 21 , wherein the memory and the one or more processors are further configured to:

transmit, to the UE, a downlink message indicating one or more of resources or configuration information associated with the one or more downlink reference signals and the one or more uplink reference signals used to select the best uplink beam.

24. The base station of claim 21 , wherein at least one beam included in the set of candidate downlink beams is also included in the set of candidate uplink beams, and wherein the memory and the one or more processors are further configured to:

determine the best uplink beam based at least in part on a delta between a first measurement associated with a downlink reference signal received by the UE using the at least one beam and a second measurement associated with an uplink reference signal transmitted by the UE using the at least one beam.

25. The base station of claim 21 , wherein an uplink spatial filter for the one or more uplink transmissions is based at least in part on an indicator used to indicate the best uplink beam and the indicator indexing information.

26. The base station of claim 21 , wherein the memory and the one or more processors are further configured to:

transmit, to the UE, a single downlink control information (DCI) message to configure reception of the one or more downlink reference signals by the UE and transmission of the one or more uplink reference signals by the UE, wherein the single DCI message further configures one or more of a switching gap between the reception of the one or more downlink reference signals and the transmission of the one or more uplink reference signals, or settings associated with the report that includes the measurements associated with the one or more downlink reference signals.