An adaptive pre-distortion method based on orthogonal polynomials

Wideband signals without pre-distortion are distorted by memory and nonlinear effect of high power amplifier. To compensate these distortions, we propose an adaptive pre-distorter based on orthogonal polynomials. Based on orthogonal criterion, we derive a series of orthogonal polynomials under circular symmetric complex Gaussian distribution. Indirect learning architecture is used for pre-distorter identification and recursive least square algorithm is introduced for parameters estimation. At last using two power amplifier models, we simulate the performance of the proposed pre-distorter in an OFDM system. Simulation results show that the proposed pre-distorter can effectively compensate the distortions produced by high power amplifier.