Methods and systems for selective crest factor reduction and digital pre-distortion in wireless transmitters

1. A method for wireless communication, comprising:

allocating a transmission bandwidth for transmission to a first user equipment (UE);

determining if the allocated transmission bandwidth is less than or equal to a first bandwidth threshold value;

if the allocated transmission bandwidth is less than or equal to the first bandwidth threshold value, digitally pre-distorting transmit signals and transmitting the digitally pre-distorted transmit signals to the first UE; and

if the allocated transmission bandwidth is not less than or equal to the first bandwidth threshold value, transmitting to the first UE without digitally pre-distorting the signals.

2. The method of claim 1 , wherein the first bandwidth threshold value is the maximum estimated BW DPD , wherein the maximum estimated BW DPD is the maximum estimated signal bandwidth a transmitter is configured to digitally pre-distort.

3. The method of claim 1 , further comprising applying digital crest factor reduction to the transmit signals if the allocated transmission bandwidth is less than or equal to a second bandwidth threshold value.

4. The method of claim 1 , further comprising:

scheduling a transmission to the first UE in a first transmission time interval (TTI);

transmitting the digitally pre-distorted transmit signals in the first TTI to the first UE if the allocated transmission bandwidth is less than or equal to the maximum estimated BW DPD ; and

transmitting to the first UE without digitally pre-distorting the transmit signals in the first TTI if the allocated transmission bandwidth is not less than or equal to the maximum estimated BW DPD .

5. The method of claim 1 , further comprising:

scheduling a transmission to a second UE in a second TTI;

allocating a transmission bandwidth for transmission to the second UE;

determining if the allocated transmission bandwidth to the second UE is less than or equal to the maximum estimated BW DPD , wherein the maximum estimated BW DPD is the maximum estimated signal bandwidth that a transmitter is configured to digitally pre-distort;

if the allocated transmission bandwidth is less than or equal to the maximum estimated BW DPD , digitally pre-distorting transmit signals and transmitting the digitally pre-distorted transmit signals to the second UE in the second TTI; and

if the allocated transmission bandwidth is not less than or equal to the maximum estimated BW DPD , transmitting to the second UE in the second TTI without digitally pre-distorting the signals.

6. The method of claim 1 , further comprising:

determining a non-linear coefficient of at least one power amplifier; and

digitally pre-distorting the transmit signals using the non-linear coefficient of the power amplifier.

7. The method of claim 1 , further comprising:

digitally pre-distorting the transmit signals using the non-linear coefficient; and

amplifying the digitally pre-distorted signals by a power amplifier, wherein digital pre-distortion modifies non-linear response of the power amplifier.

8. The method of claim 1 , wherein the transmit signals are in a millimeter wave band.

9. The method of claim 1 , wherein the transmit signals are in a sub-7 GHz frequency band.

10. The method of claim 1 , wherein the UE is a communication device.

11. The method of claim 1 , wherein the transmitter is a radio base station.

12. The method of claim 3 , wherein the second bandwidth threshold value is the maximum estimated BW CFR , wherein the maximum estimated BW CFR is the maximum estimated signal bandwidth on which a transmitter is configured to apply digital crest factor reduction.

13. A method for wireless communication, comprising:

scheduling transmissions to at least first and second user equipment (UEs) in a first transmission time interval (TTI);

allocating respective transmission bandwidths for transmission in the first TTI to the first and second UEs;

determining if the total allocated transmission bandwidth in the first TTI is less than or equal a maximum estimated BW DPD , wherein the maximum estimated BW DPD is the maximum estimated signal bandwidth that a transmitter is configured to digitally pre-distort;

if the total allocated transmission bandwidth in the first TTI is less than or equal to the maximum estimated BW DPD , digitally pre-distorting transmit signals and transmitting the digitally pre-distorted transmit signals to the first and second UEs in the first TTI; and

if the total allocated transmission bandwidth in the first TTI is not less than or equal to the maximum estimated BW DPD , transmitting to the first and second UEs without digitally pre-distorting the signals.

14. The method of claim 13 , further comprising:

scheduling a transmission to at least a third UE in a second TTI;

allocating a transmission bandwidth for transmission to the third UE;

determining if the allocated transmission bandwidth to the third UE is less than or equal to the maximum estimated BW DPD , wherein the maximum estimated BW DPD is the maximum estimated signal bandwidth that a transmitter is configured to digitally pre-distort;

if the allocated transmission bandwidth is less than or equal to the maximum estimated BW DPD , digitally pre-distorting transmit signals and transmitting the digitally pre-distorted transmit signals to the third UE in the second TTI; and

if the allocated transmission bandwidth is not less than or equal to the maximum estimated BW DPD , transmitting to the third UE in the second TTI without digitally pre-distorting the signals.

15. The method of claim 13 , further comprising:

determining a lower frequency edge (f LE ) and an upper frequency edge (f UE ) of the allocated transmission bandwidths for the UEs; and

determining the total allocated transmission bandwidth, wherein the total allocated transmission bandwidth is equal to (f UE −f LE ).

16. The method of claim 13 , further comprising applying digital crest factor reduction to the transmit signals if the allocated transmission bandwidth is less than or equal to the maximum estimated BW CFR , wherein the maximum estimated BW CFR is the maximum estimated signal bandwidth on which a transmitter is configured to apply digital crest factor reduction.

17. The method of claim 13 , further comprising:

determining a non-linear coefficient of at least one power amplifier; and

digitally pre-distorting the transmit signals using the non-linear coefficient of the power amplifier.

18. The method of claim 13 , further comprising:

digitally pre-distorting the transmit signals using the non-linear coefficient; and

amplifying the digitally pre-distorted signals by a power amplifier, wherein digital pre-distortion modifies non-linear response of the power amplifier.

19. The method of claim 13 , further comprising estimating the maximum estimated BW CFR using at least one parameter value of the transmitter.

20. The method of claim 13 , further comprising estimating the maximum estimated BW DPD using at least one parameter value of the transmitter.

21. The method of claim 13 , wherein the transmit signals are in a millimeter wave band.

22. The method of claim 13 , wherein the transmit signals are in a sub-7 GHz frequency band.

23. The method of claim 13 , wherein the UE is a communication device.

24. The method of claim 13 , wherein the UE is a mobile phone.

25. The method of claim 13 , wherein the transmitter is a radio base station.

26. A method for wireless communication, comprising:

scheduling transmission to at least a first user equipment (UE) in a first transmission time interval (TTI);

allocating a transmission bandwidth for transmission in the first TTI to the first UE;

determining if the total allocated transmission bandwidth in the first TTI is less than or equal to a maximum estimated BW DPD , wherein the maximum estimated BW DPD is the maximum estimated signal bandwidth that a transmitter is configured to digitally pre-distort;

if the total allocated transmission bandwidth in the first TTI is less than or equal to the maximum estimated BW DPD , digitally pre-distorting transmit signals and transmitting the digitally pre-distorted transmit signals to the first UE in the first TTI;

if the total allocated transmission bandwidth in the first TTI is not less than or equal to the maximum estimated BW DPD , transmitting to the first UE without digitally pre-distorting the signals;

scheduling a transmission to at least a second UE in a second TTI;

allocating a transmission bandwidth for transmission to the second UE;

determining if the total allocated transmission bandwidth in the second TTI is less than or equal to the maximum estimated BW DPD ;

if the allocated transmission bandwidth in the second TTI is less than or equal to the maximum estimated BW DPD , digitally pre-distorting transmit signals and transmitting the digitally pre-distorted transmit signals to the second UE in the second TTI; and

if the allocated transmission bandwidth is not less than or equal to the maximum estimated BW DPD , transmitting to the second UE in the second TTI without digitally pre-distorting the signals.

27. The method of claim 26 , further comprising applying digital crest factor reduction to the transmit signals if the total allocated transmission bandwidth is less than or equal to the maximum estimated BW CFR .

28. The method of claim 26 , further comprising estimating the maximum estimated BW DPD using at least one parameter value of the transmitter.

29. The method of claim 26 , further comprising estimating the maximum estimated BW CFR using at least one parameter value of the transmitter.

30. An apparatus configured for wireless communication, comprising:

means for allocating a transmission bandwidth for transmission to a first user equipment (UE);

means for determining if the allocated transmission bandwidth is less than or equal to a maximum estimated BW DPD , wherein the maximum estimated BW CFR/DPD is the maximum estimated signal bandwidth that a transmitter is configured to digitally pre-distort;

means for digitally pre-distorting transmit signals and transmitting the digitally pre-distorted transmit signals to the first UE, wherein the digitally pre-distorted signals are transmitted if the allocated transmission bandwidth is less than or equal to the maximum estimated BW DPD ; and

means for transmitting to the first UE without digitally pre-distorting the signals, wherein the signals are transmitted without digital pre-distortion if the allocated transmission bandwidth is not less than or equal to the maximum estimated BW DPD .

31. The apparatus of claim 30 , further comprising means for applying digital crest factor reduction to the transmit signals if the allocated transmission bandwidth is less than or equal to the maximum estimated BW CFR .

32. The apparatus of claim 30 , further comprising:

means for scheduling a transmission to the first UE in a first transmission time interval (TTI);

means for transmitting the digitally pre-distorted transmit signals in the first TTI to the first UE if the allocated transmission bandwidth is less than or equal to the maximum estimated BW DPD ; and

means for transmitting to the first UE without digitally pre-distorting the transmit signals in the first TTI if the allocated transmission bandwidth is not less than or equal to the maximum estimated BW DPD .

33. The apparatus of claim 30 , further comprising:

means for scheduling a transmission to a second UE in a second TTI;

means for allocating a transmission bandwidth for transmission to the second UE;

means for determining if the allocated transmission bandwidth to the second UE is less than or equal to the maximum estimated BW DPD , wherein the maximum estimated BW DPD is the maximum estimated signal bandwidth that a transmitter is configured to digitally pre-distort;

means for digitally pre-distorting transmit signals and transmitting the digitally pre-distorted transmit signals to the second UE in the second TTI if the allocated transmission bandwidth is less than or equal to the maximum estimated BW DPD ; and

means for transmitting to the second UE in the second TTI without digitally pre-distorting the signals if the allocated transmission bandwidth is not less than or equal to the maximum estimated BW DPD .

34. The apparatus of claim 30 , further comprising means for estimating the maximum estimated BW DPD using at least one parameter value of the transmitter.

35. The apparatus of claim 30 , further comprising means for estimating the maximum estimated BW CFR using at least one parameter value of the transmitter.