Performance of a predistorter based on Saleh model for OFDM systems in HPA nonlinearity

Orthogonal Frequency Division Multiplexing (OFDM) is an attractive technique for wireless communication applications. However, it suffers from high nonlinear distortion in nonlinear devices such as high power amplifiers (HPA) due to large peak to average power ratio (PAPR) of the OFDM signals. A predistorter based on inverse of the Saleh model is proposed to compensate for the nonlinearity. In this paper, we investigate the BER performance of an OFDM system in a nonlinear environment with and without the use of the proposed predistorter. Optimum values of amplifier output back off (OBO) are calculated for different scenarios and effect of modulation order and number of subcarriers on system performance are studied. Results show that use of predistorter can significantly enhance the system performance by reducing the needed OBO and increasing HPA power efficiency. Other simulations were performed to investigate the effect of modulation order and number of subcarriers on the system performance.