Orbital angular momentum signaling

1. A method for wireless communications at a base station, comprising:

receiving, from a user equipment (UE), a message indicating a UE capability to use orbital angular momentum beamforming;

determining, based at least in part on the UE capability and one or more communications parameters, to enable orbital angular momentum beamforming for communications with the UE;

transmitting, to the UE, control signaling including an indication that orbital angular momentum beamforming is enabled; and

transmitting a downlink transmission to the UE using a plurality of beams via orbital angular momentum beamforming.

2. The method of claim 1 , further comprising:

transmitting an orbital angular momentum configuration within a downlink control information message as part of the control signaling.

3. The method of claim 2 , wherein the orbital angular momentum configuration indicates a modulation and coding scheme for each beam of the plurality of beams, a resource allocation for each beam of the plurality of beams, a quantity of the plurality of beams, an orbital angular momentum index for each beam of the plurality of beams, or a combination thereof.

4. The method of claim 2 , wherein the orbital angular momentum configuration is for either a same slot in which the control signaling is transmitted or a subsequent slot, in accordance with one or more time offset values included in the control signaling.

5. The method of claim 4 , wherein the downlink control information message includes fields for configuring the same slot for orbital angular momentum beamforming.

6. The method of claim 4 , wherein a medium access control (MAC) control element (CE) includes information for configuring the subsequent slot for orbital angular momentum beamforming.

7. The method of claim 1 , wherein transmitting the control signaling comprises:

transmitting the indication in a preamble at a beginning of a slot that includes the downlink transmission.

8. The method of claim 7 , wherein transmitting the control signaling further comprises:

transmitting the control signaling which is indicative of an orbital angular momentum index for each beam of the plurality of beams, a radio network temporary identifier (RNTI) associated with the UE, or both.

9. The method of claim 1 , wherein the communications parameters include one or more channel conditions, a channel rank, a misalignment associated with the orbital angular momentum beamforming, a speed of the UE, a distance between the base station and the UE, a throughput of the UE, or a combination thereof.

10. The method of claim 9 , further comprising:

determining the misalignment associated with the channel based at least in part on receiving a misalignment report from the UE, estimating the misalignment, or a combination thereof.

11. The method of claim 1 , further comprising:

determining that a misalignment associated with the orbital angular momentum beamforming is correctable by the base station;

correcting the misalignment based at least in part on the determining; and

estimating a remaining misalignment associated with the orbital angular momentum beamforming, wherein determining to enable orbital angular momentum beamforming is based at least in part on the remaining misalignment.

12. The method of claim 1 , further comprising:

receiving, from the UE, a request message to enable orbital angular momentum beamforming, wherein determining to enable orbital angular momentum beamforming is based at least in part on receiving the request message.

13. The method of claim 1 , wherein the control signaling comprises radio resource control (RRC) signaling, a media access control control element (MAC-CE), downlink control information (DCI), or a combination thereof.

14. The method of claim 1 , wherein the control signaling is associated with an orbital angular momentum index of zero.

15. The method of claim 1 , further comprising:

determining to disable orbital angular momentum beamforming for communications with the UE;

transmitting, to the UE, additional control signaling that indicates that orbital angular momentum beamforming is disabled; and

communicating with the UE using non-orbital angular momentum beamforming.

16. The method of claim 1 , wherein the message further indicates an additional UE capability to perform digital beamforming.

17. A method for wireless communications at a user equipment (UE), comprising:

transmitting, to a base station, a message indicating a UE capability of the UE to use orbital angular momentum beamforming;

receiving, from the base station, control signaling including an indication that orbital angular momentum beamforming is enabled; and

receiving a downlink transmission from the base station using a plurality of beams via orbital angular momentum beamforming.

18. The method of claim 17 , further comprising:

receiving an orbital angular momentum configuration within a downlink control information message as part of the control signaling.

19. The method of claim 18 , wherein the orbital angular momentum configuration indicates a modulation and coding scheme for each beam of the plurality of beams, a resource allocation for each beam of the plurality of beams, a quantity of the plurality of beams, an orbital angular momentum index for each beam of the plurality of beams, or a combination thereof.

20. The method of claim 18 , wherein the orbital angular momentum configuration is for either a same slot in which the control signaling is transmitted or a subsequent slot, in accordance with one or more time offset values included in the control signaling.

21. The method of claim 20 , wherein the downlink control information message includes fields for configuring the same slot for orbital angular momentum beamforming.

22. The method of claim 20 , wherein a medium access control (MAC) control element (CE) includes information for configuring the subsequent slot for orbital angular momentum beamforming.

23. The method of claim 17 , wherein receiving the control signaling comprises:

receiving the indication in a preamble at a beginning of a slot that includes the downlink transmission.

24. The method of claim 23 , wherein receiving the control signaling further comprises:

receiving the control signaling which is indicative of an orbital angular momentum index for each beam of the plurality of beams, a radio network temporary identifier (RNTI) associated with the UE, or both.

25. The method of claim 17 , wherein the communications parameters include one or more channel conditions, a channel rank, a misalignment associated with the orbital angular momentum beamforming, a speed of the UE, a distance between the base station and the UE, a throughput of the UE, or a combination thereof.

26. The method of claim 25 , further comprising:

transmitting, to the base station, a misalignment report.

27. The method of claim 17 , further comprising:

transmitting, to the base station, a request message to enable orbital angular momentum beamforming.

28. The method of claim 17 , further comprising:

receiving, from the base station, additional control signaling that indicates that orbital angular momentum beamforming is disabled; and

communicating with the base station using non-orbital angular momentum beamforming.

29. An apparatus for wireless communications 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:

receive, from a user equipment (UE), a message indicating a UE capability to use orbital angular momentum beamforming;

determine, based at least in part on the UE capability and one or more communications parameters, to enable orbital angular momentum beamforming for communications with the UE;

transmit, to the UE, control signaling including an indication that orbital angular momentum beamforming is enabled; and

transmit a downlink transmission to the UE using a plurality of beams via orbital angular momentum beamforming.

30. 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:

transmit, to a base station, a message indicating a UE capability of the UE to use orbital angular momentum beamforming;

receive, from the base station, control signaling including an indication that orbital angular momentum beamforming is enabled; and

receive a downlink transmission from the base station using a plurality of beams via orbital angular momentum beamforming.