An Adaptive Nonlinearity Compensation Scheme for OFDM Communication Systems

An adaptive predistortion linearization is proposed to compensate for the nonlinear distortions induced by high power amplifiers (HPAs) in orthogonal frequency division multiplexing (OFDM) systems. By expressing the uncertain nonlinear input-output dynamics of HPA by a new simplified Volterra series model (VSM), a predistorter (i.e., compensator) is constructed based on identification of inverse system of the HPA. Once predistorter´s parameters are obtained by RLS algorithm, 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 even if HPA is uncertain. The effectiveness of the proposed predistortion method is validated by numerical simulation for 64-ary quadrature amplitude modulation OFDM (64QAM-OFDM) transmission systems