Strategic predistortion function selection

1. A method of controlling distortion in a signal having a range of power levels between a maximum power level and a minimum power level, comprising the steps of:

selecting a lift power level between the maximum power level and the minimum power level;

determining a current power level of the signal; and

applying a corrective predistortion function to the signal, the corrective predistortion function corresponding to the lift power level when the determined current power level is at or below the lift power level.

2. The method of claim 1 , comprising

applying a corrective predistortion function to the signal, the corrective predistortion function corresponding to the determined current power level when the determined current power level exceeds the lift power level.

3. The method of claim 1 , comprising

determining a corrective predistortion function for each of a plurality of power levels within the range of power levels;

storing each of the determined corrective predistortion functions in a table; and

selecting one of the corrective predistortion functions from the table based on the determined current power level.

4. The method of claim 3 , comprising

selecting the corrective predistortion function from the table that corresponds to the lift power level when the determined current power level is at or below the lift power level; and

selecting the corrective predistortion function from the table that corresponds to the determined current power level when the determined current power level is above the lift power level.

5. The method of claim 1 , comprising

selecting a level that is between about 2 dB and about 6 dB below the maximum power level as the lift power level.

6. The method of claim 1 , comprising

periodically updating the lift power level.

7. The method of claim 6 , comprising

determining whether the current power level has been below the lift power level for at least a preselected amount of time; and

setting an updated lift power level according to a current power level having a corresponding corrective predistortion function that meets a selected criteria.

8. The method of claim 7 , wherein the selected criteria comprises the corresponding corrective predistortion function being updated within a selected time of a time corresponding to the current power level.

9. The method of claim 6 , comprising

decreasing the lift power level when the current power level has been below the lift level for at least a selected number of sampling intervals; and

subsequently increasing the lift power level responsive to the current power level increasing.

10. A device for processing a signal, comprising

a component that tends to introduce distortion as a result of processing the signal; and

a predistortion function selector configured to select a corrective predistortion function to be applied to the signal based on a current signal power level, the predistortion function selector selecting a corrective predistortion function corresponding to a lift power level between a maximum signal power level and a minimum signal power level when the current signal power level is at or below the lift power level.

11. The device of claim 10 , wherein the predistortion function selector is configured to apply a corrective predistortion function corresponding to the determined current power level when the determined current power level exceeds the lift power level.

12. The device of claim 10 , wherein the predistortion function selector is configured to

determine a corrective predistortion function for each of a plurality of power levels within the range of power levels;

store each of the determined corrective predistortion functions in a table; and

select one of the corrective predistortion functions from the table based on the determined current power level.

13. The device of claim 12 , wherein the predistortion function selector is configured to

select the corrective predistortion function from the table that corresponds to the lift power level when the determined current power level is at or below the lift power level; and

select the corrective predistortion function from the table that corresponds to the determined current power level when the determined current power level is above the lift power level.

14. The device of claim 10 , wherein the predistortion function selector is configured to select a level that is between about 2 dB and about 6 dB below the maximum power level as the lift power level.

15. The device of claim 10 , wherein the predistortion function selector is configured to periodically update the lift power level.

16. The device of claim 10 , wherein the predistortion function selector is configured to

determine whether the current power level has been below the lift power level for at least a preselected amount of time; and

set an updated lift power level according to a current power level having a corresponding corrective predistortion function that meets a selected criteria.

17. The device of claim 16 , wherein the selected criteria comprises the corresponding corrective predistortion function being updated within a selected time of a time corresponding to the current power level.

18. The device of claim 10 , wherein the predistortion function selector is configured to

decrease the lift power level when the current power level has been below the lift level for at least a selected number of sampling intervals; and

subsequently increase the lift power level responsive to the current power level increasing.