Predistortion 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 signals are sensitive to the nonlinearity of the channel. The predistortion, which aims at compensating for the nonlinear distortion caused by the power amplifier, has a good performance in eliminating the nonlinear distortion of AM/AM & AM/PM, improving the ACI and spectrum efficiency.The rationale of the OFDM and the nonlinear effect of the power amplifier on the OFDM signals are presented in this paper, the principle of the adaptive digital predistortion is also introduced. On the basis of the Rascal algorithm, this paper puts forward an improved algorithm that converges fast with low computing load and the related simulation. Analysis on the quantity of the predistortion in the OFDM is also given. At last, the tendency of the linearization development in the future is pointed out.