| 摘要 |
A power amplifier pre-distorter is formed by a FIR filter structure which includes an individual look-up table for each filter tap, where each look-up table represents a sampled polynomial in a variable representing signal amplitude, and means for selecting, from each filter tap look-up table, a filter coefficient that depends on the amplitude of a corresponding complex signal value to be multiplied by the filter tap. A training method for such a pre-distorter determines (S 1 ) a first estimate of a first look-up table assigned to a first filter tap, assuming a second look-up table assigned to a second filter tap is set to predetermined table values. Thereafter the method determines (S 2 ) a second estimate of the second look-up table, assuming the first look-up table is set to the determined first estimate. If deemed necessary, the method includes the further steps (a) refining (S 3 ) the first estimate refined, assuming the second look-up table is set to the latest determined second estimate, and (b) refining (S 4 ) the second estimate, assuming the first look-up table is set to the latest determined first estimate. Steps (a) and (b) may be repeated (S 5 ) until convergence is reached.
|
