System and methods for fast power headroom reporting

1. A method of wireless communications, comprising:

determining, at a user equipment (UE), to change one or more beamforming parameters for transmissions on a new beam;

determining a power headroom applicable to a transmission from the UE on the new beam; and

transmitting, in response to the change, a power headroom report based on the power headroom, the power headroom report being transmitted on resources assigned for the power headroom report, wherein the transmitting comprises transmitting the power headroom report as a physical layer signal, wherein the power headroom report is multiplexed with a scheduling request as a selected sequence from a plurality of sequences for the scheduling request, multiplexed with a sounding reference signal as a selected sequence from a plurality of sequences for the sounding reference signal, or transmitted with uplink control information (UCI) using a grant for the UCI on a physical uplink control channel (PUCCH).

2. The method of claim 1 , wherein determining to change the one or more beamforming parameters is based on the UE autonomously changing among a set of preconfigured beams.

3. The method of claim 1 , wherein determining to change the one or more beamforming parameters is based on the UE receiving a command to change the one or more beamforming parameters.

4. The method of claim 3 , wherein the command indicates the resources assigned for the power headroom report.

5. The method of claim 3 , further comprising selecting a scheduled transmission during a time period after the command is implemented as the resources assigned for the power headroom report.

6. The method of claim 5 , wherein selecting the scheduled transmission is based on a priority of a transmission type of the scheduled transmission.

7. The method of claim 1 , wherein the resources assigned for the power headroom report are also assigned to another uplink transmission.

8. The method of claim 1 , wherein transmitting the power headroom report comprises:

encoding the power headroom report along with the UCI; and

transmitting the power headroom report and the UCI using the grant for the UCI on the PUCCH.

9. The method of claim 1 , wherein transmitting the power headroom report comprises:

separately encoding the power headroom report; and

transmitting the power headroom report and the UCI using the grant for the UCI on the PUCCH.

10. The method of claim 1 , wherein transmitting the power headroom report comprises transmitting the power headroom report that is multiplexed with the scheduling request as the selected sequence from a plurality of sequences for the scheduling request.

11. The method of claim 1 , wherein transmitting the power headroom report comprises transmitting the power headroom report that is multiplexed with the sounding reference signal as the selected sequence from a plurality of sequences for the sounding reference signal.

12. The method of claim 1 , wherein the power headroom report includes a quantized change in beamforming gain or power headroom value caused by the change of beamforming parameters.

13. The method of claim 12 , wherein the quantization of the change is based on a capability of the UE.

14. The method of claim 1 , wherein determining the power headroom is based on a transmission waveform of a physical uplink shared channel (PUSCH).

15. A user equipment (UE), comprising:

a memory; and

a processor in communication with the memory;

wherein the processor is configured to:

determine, at the UE, to change one or more beamforming parameters for transmissions on a new beam;

determine a power headroom applicable to a transmission from the UE on the new beam; and

transmit, in response to the change, a power headroom report based on the power headroom, the power headroom report being transmitted on resources assigned for the power headroom report, wherein the processor is configured to transmit the power headroom report as a physical layer signal, wherein the power headroom report is multiplexed with a scheduling request as a selected sequence from a plurality of sequences for the scheduling request, multiplexed with a sounding reference signal as a selected sequence from a plurality of sequences for the sounding reference signal, or transmitted with uplink control information (UCI) using a grant for the UCI on a physical uplink control channel (PUCCH).

16. The UE of claim 15 , wherein the processor is configured to determine to change the one or more beamforming parameters based on the UE autonomously changing among a set of preconfigured beams.

17. The UE of claim 15 , wherein the processor is configured to determine to change the one or more beamforming parameters based on the UE receiving a command to change the one or more beamforming parameters.

18. The UE of claim 17 , wherein the command indicates the resources assigned for the power headroom report.

19. The UE of claim 17 , wherein the processor is configured to select a scheduled transmission during a time period after the command is implemented as the resources assigned for the power headroom report.

20. The UE of claim 19 , wherein the processor is configured to select the scheduled transmission based on a priority of a transmission type of the scheduled transmission.

21. The UE of claim 15 , wherein the resources assigned for the power headroom report are also assigned to another uplink transmission.

22. The UE of claim 15 , wherein the processor is configured to transmit the power headroom report multiplexed with the scheduling request as the selected sequence from the plurality of sequences for the scheduling request.

23. The UE of claim 15 , wherein the processor is configured to transmit the power headroom report multiplexed with the sounding reference signal as the selected sequence from the plurality of sequences for the sounding reference signal.

24. The UE of claim 15 , wherein the power headroom report includes a quantized change in beamforming gain or power headroom value caused by the change of beamforming parameters.

25. A user equipment, comprising:

means for determining, at a user equipment (UE), to change one or more beamforming parameters for transmissions on a new beam;

means for determining a power headroom applicable to a transmission from the UE on the new beam; and

means for transmitting, in response to the change, a power headroom report based on the power headroom, the power headroom report being transmitted on resources assigned for the power headroom report as a physical layer signal, wherein the power headroom report is multiplexed with a scheduling request as a selected sequence from a plurality of sequences for the scheduling request, multiplexed with a sounding reference signal as a selected sequence from a plurality of sequences for the sounding reference signal, or transmitted with uplink control information (UCI) using a grant for the UCI on a physical uplink control channel (PUCCH).

26. A non-transitory computer-readable medium storing computer code executable by a processor of a user equipment (UE) for wireless communications, comprising code to:

determine, at the UE, to change one or more beamforming parameters for transmissions on a new beam;

determine a power headroom applicable to a transmission from the UE on the new beam; and

transmit, in response to the change, a power headroom report based on the power headroom, the power headroom report being transmitted on resources assigned for the power headroom report as a physical layer signal, wherein the power headroom report is multiplexed with a scheduling request as a selected sequence from a plurality of sequences for the scheduling request, multiplexed with a sounding reference signal as a selected sequence from a plurality of sequences for the sounding reference signal, or transmitted with uplink control information (UCI) using a grant for the UCI on a physical uplink control channel (PUCCH).