An adaptive predistortion for nonlinear amplifier in OFDM communication systems

An adaptive predistortion linearization is proposed to compensate for the linear and nonlinear distortions induced by high power amplifiers (HPAs) in orthogonal frequency division multiplexing (OFDM) systems. The uncertain HPA with memory is represented by the three-box model with a Wiener-Hammerstein structure. A simplified Volterra series model (VSM) is applied to approximate the input-output property of the HPA, and an adaptive predistorter is generated directly by using the VSM which need not to identify the inverse model of the HPA. When OFDM signals pass through the cascade system of the predistorter and the HPA, overall linearization from predistorter input to HPA output can be achieved. The effectiveness of the proposed predistortion method is validated by numerical simulation for 64-ary quadrature amplitude modulation OFDM (64QAM-OFDM) transmission systems.