Channel and power amplifier nonlinearity estimation

1. A method for wireless communication at a user equipment (UE), comprising:

receiving a demodulation reference signal comprising a set of demodulation reference signal samples comprising a first subset of demodulation reference signal samples associated with a first power level and a second subset of demodulation reference signal samples associated with a second power level;

performing a digital post distortion operation based at least in part on the received demodulation reference signal comprising the first subset of demodulation reference signal samples associated with the first power level and the second subset of demodulation reference signal samples associated with the second power level; and

receiving the wireless communication based at least in part on performing the digital post distortion operation.

2. The method of claim 1 , further comprising:

receiving control signaling indicating a demodulation reference signal configuration, the demodulation reference signal configuration identifying different power levels for different demodulation reference signal samples,

wherein receiving the set of demodulation reference signal samples comprising the first subset of demodulation reference signal samples associated with the first power level and the second subset of demodulation reference signal samples associated with the second power level is based at least in part on the demodulation reference signal configuration.

3. The method of claim 2 , wherein receiving the control signaling comprises:

receiving one or more of a radio resource control message, a downlink control information, or a medium access control-control element, including the demodulation reference signal configuration identifying the different power levels for the different demodulation reference signal samples.

4. The method of claim 2 , further comprising:

receiving an indication in the control signaling a set of constellation points in a constellation distribution associated with a modulation scheme,

wherein performing the digital post distortion operation is based at least in part on the set of constellation points of the constellation distribution associated with the modulation scheme.

5. The method of claim 4 , wherein the modulation scheme comprises a quadrature amplitude modulation (QAM) scheme.

6. The method of claim 4 , wherein the modulation scheme comprises an amplitude and phase-shift keying (APSK) modulation scheme.

7. The method of claim 1 , further comprising:

estimating a channel associated with the wireless communication and a nonlinearity of a power amplifier based at least in part on the first subset of demodulation reference signal samples associated with the first power level and the second subset of demodulation reference signal samples associated with the second power level,

wherein performing the digital post distortion operation is based at least in part on estimating the channel associated with the wireless communication and the nonlinearity of the power amplifier.

8. The method of claim 1 , further comprising:

estimating a channel associated with the wireless communication based at least on the first subset of demodulation reference signal samples associated with the first power level,

wherein performing the digital post distortion operation is based at least in part on estimating the channel associated with the wireless communication.

9. The method of claim 8 , wherein estimating the channel comprises:

estimating the channel using a subset of constellation points of a set of constellation points associated with a modulation scheme, the subset of constellation points corresponding to inner constellation points of a constellation distribution.

10. The method of claim 8 , further comprising:

estimating a nonlinearity of a power amplifier associated with the UE based at least in part on the second subset of demodulation reference signal samples associated with the second power level,

wherein performing the digital post distortion operation is based at least in part on estimating the channel associated with the wireless communication and estimating the nonlinearity of the power amplifier associated with the UE.

11. The method of claim 10 , wherein estimating the nonlinearity of the power amplifier comprises:

estimating the nonlinearity of the power amplifier using a subset of constellation points of a set of constellation points associated with a modulation scheme, the subset of constellation points corresponding to outer constellation points of a constellation distribution.

12. The method of claim 1 , wherein the wireless communication comprises a single carrier waveform transmission.

13. A method for wireless communication at a base station, comprising:

transmitting a demodulation reference signal comprising a set of demodulation reference signal samples comprising a first subset of demodulation reference signal samples associated with a first power level and a second subset of demodulation reference signal samples associated with a second power level; and

transmitting the wireless communication based at least in part on the transmitted demodulation reference signal comprising the set of demodulation reference signal samples.

14. The method of claim 13 , further comprising:

transmitting control signaling indicating a demodulation reference signal configuration, the demodulation reference signal configuration identifying different power levels for different demodulation reference signal samples,

wherein transmitting the set of demodulation reference signal samples comprising the first subset of demodulation reference signal samples associated with the first power level and the second subset of demodulation reference signal samples associated with the second power level is based at least in part on the demodulation reference signal configuration.

15. The method of claim 14 , wherein transmitting the control signaling comprises:

transmitting one or more of a radio resource control message, a downlink control information, or a medium access control-control element, including the demodulation reference signal configuration identifying the different power levels for the different demodulation reference signal samples.

16. The method of claim 14 , further comprising:

determining a set of constellation points of a constellation distribution associated with a modulation scheme; and

transmitting an indication in the control signaling of the set of constellation points of the constellation distribution associated with the modulation scheme.

17. The method of claim 16 , wherein the modulation scheme comprises a quadrature amplitude modulation (QAM) scheme.

18. The method of claim 16 , wherein the modulation scheme comprises an amplitude and phase-shift keying (APSK) modulation scheme.

19. The method of claim 13 , wherein the wireless communication comprises a single carrier waveform transmission.

20. An apparatus for wireless communication, 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 a demodulation reference signal comprising a set of demodulation reference signal samples comprising a first subset of demodulation reference signal samples associated with a first power level and a second subset of demodulation reference signal samples associated with a second power level;

perform a digital post distortion operation based at least in part on the received demodulation reference signal comprising the first subset of demodulation reference signal samples associated with the first power level and the second subset of demodulation reference signal samples associated with the second power level; and

receive the wireless communication based at least in part on performing the digital post distortion operation.

21. The apparatus of claim 20 , wherein the instructions are further executable by the processor to cause the apparatus to:

receive control signaling indicating a demodulation reference signal configuration, the demodulation reference signal configuration identifying different power levels for different demodulation reference signal samples,

wherein the instructions to receive the set of demodulation reference signal samples comprising the first subset of demodulation reference signal samples associated with the first power level and the second subset of demodulation reference signal samples associated with the second power level are further executable by the processor based at least in part on the demodulation reference signal configuration.

22. The apparatus of claim 21 , wherein the instructions to receive the control signaling are executable by the processor to cause the apparatus to:

receive one or more of a radio resource control message, a downlink control information, or a medium access control-control element, including the demodulation reference signal configuration identifying the different power levels for the different demodulation reference signal samples.

23. The apparatus of claim 21 , wherein the instructions are further executable by the processor to cause the apparatus to:

receive an indication in the control signaling a set of constellation points in a constellation distribution associated with a modulation scheme,

wherein the instructions to perform the digital post distortion operation are further executable by the processor based at least in part on the set of constellation points of the constellation distribution associated with the modulation scheme.

24. The apparatus of claim 23 , wherein the modulation scheme comprises a quadrature amplitude modulation (QAM) scheme.

25. The apparatus of claim 23 , wherein the modulation scheme comprises an amplitude and phase-shift keying (APSK) modulation scheme.

26. 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:

transmit a demodulation reference signal comprising a set of demodulation reference signal samples comprising a first subset of demodulation reference signal samples associated with a first power level and a second subset of demodulation reference signal samples associated with a second power level; and

transmit the wireless communication based at least in part on the transmitted demodulation reference signal comprising the set of demodulation reference signal samples.

27. The apparatus of claim 26 , wherein the instructions are further executable by the processor to cause the apparatus to:

transmit control signaling indicating a demodulation reference signal configuration, the demodulation reference signal configuration identifying different power levels for different demodulation reference signal samples,

wherein the instruction to transmit the set of demodulation reference signal samples comprising the first subset of demodulation reference signal samples associated with the first power level and the second subset of demodulation reference signal samples associated with the second power level are further executable by the processor based at least in part on the demodulation reference signal configuration.

28. The apparatus of claim 27 , wherein the instructions to transmit the control signaling are executable by the processor to cause the apparatus to:

transmit one or more of a radio resource control message, a downlink control information, or a medium access control-control element, including the demodulation reference signal configuration identifying the different power levels for the different demodulation reference signal samples.

29. The apparatus of claim 27 , wherein the instructions are further executable by the processor to cause the apparatus to:

determine a set of constellation points of a constellation distribution associated with a modulation scheme; and

transmit an indication in the control signaling of the set of constellation points of the constellation distribution associated with the modulation scheme.

30. The apparatus of claim 29 , wherein the modulation scheme comprises a quadrature amplitude modulation (QAM) scheme.