The Method Of Linearzation In OFDM System

The predistortion in the OFDM system is mainly concerned in this paper.OFDM, a high rate transmission with many outstanding advantages, has one disadvantage: its has a high PARA makes OFDM very sensitive to the nonlinearities of amplifier. To mitigate the nonlinearity disitortions to OFDM signal and improve PA's efficiency, it is necessary to compensate the nonlinearities introduced by the amplifier. For this purpose,a lot of linearization methods have been investigated including back-off, feed-forward,feedback , LINC and pre-distortion. This paper explores adaptive pre-distortion based on LUT and polynomial and HPA nonlinear characteristic curve in detail. Through computer simulation their performances is analyzed and compared; the results show their validity to compensate the nonlinearities of amplifier without memory. At last, pre-distortion of HPA with memory and the method of feed-forward combine with pre-distortions is mentioned and the tendency of the linearization development in the future is pointed out.