Amplifier predistortion using unscented Kalman filtering

Abstract

Bandwidth efficient modulation schemes like M-ary quadrature amplitude modulation (M-QAM) and orthogonal frequency division multiplexing (OFDM) suffer from amplifier nonlinearities when operated near saturation. The high power amplifier (HPA) characteristics could be memoryless or with memory, as experienced in wideband CDMA (W-CDMA). Digital baseband predistortion is an efficient technique to compensate for the amplifier nonlinearities. In this paper, an unscented Kalman filter (UKF) is used to design an adaptive predistorter (PD) for the general case of a nonlinear amplifier with memory. Simulation results are shown to verify the performance of the proposed method.