Performance of a baseband adaptive predistorter in presence of orthogonal multicarrier modulation

The performance of a baseband adaptive predistortion system to linearize memoryless high power amplifier (HPA) are analyzed in the presence of an Orthogonal Frequency Division Multiplexing (OFDM) signal. The predistortion scheme adopted is based on a digital signal processing microprocessor and a memory look-up table to predistort the baseband drive signal. Stability of the adaptation algorithm, rate of convergence and effect of quantization are assessed through simulation. The curves of Total Degradation versus the Output Back-off have been calculated for QPSK, 16QAM and 64QAM constellations, Starting from these results, the improvement brought by the use of the predistorter and the degradation caused by the quantization has been assessed.