Adaptive nonlinearity predistortion schemes with application to OFDM system

In this paper, an identification-based adaptive predistorter scheme is proposed to compensate nonlinearity of high power amplifier (HPA) in OFDM system. A Wiener model is adopted to describe the input-output relationship of HPA, where a linear dynamics is followed by a memoryless nonlinear static element approximated by using complex power series expression. In order to compensate the nonlinear distortions in the HPA, a predistorter is constructed as an inverse system of the HPA by using a Hammerstein model, and adaptive identification algorithm for the predistortion is developed in the time-domain, some results obtained by using least square (LS) algorithm in the frequency-domain are also shown. Numerical simulations validate the effectiveness of the proposed adaptive schemes.