一种宽带OFDM系统中记忆非线性功放的预失真方法

摘要

针对宽带OFDM系统中功放的记忆非线性失真问题,提出一种新的频域预失真方案.该方案在频域建立具有自适应更新的幅度、相位预失真矩阵,对信号幅度和相位分别进行多次预失真处理.为提高自适应预失真收敛速度,提出一种新的预失真矩阵自适应更新算法,即linear convergence算法.仿真结果表明,发送信号频谱旁瓣较二维查表法压低6 dB.误码率为10-4时,该方法比二维查表法约有2 dB的信噪比增益.此外,linear convergence更新算法收敛速度比二维查表法中的更新算法提高75％.提出的频域预失真方案能够有效提高收敛精度和收敛速度.%To solve memory noulinear distortion problem of power amplifier in wideband OFDM system,this paper proposed a new frequency domain predistortion scheme.This scheme built the adaptive updating amplitude and phase predistortion matrices in the frequency domain respectively,which did amplitude and phased predistortion repeatedly.Furthermore,to improve convergence speed of the adaptive predistortion,this paper developed a novel algorithm of the adaptive predistortion matrices,called linear convergence algorithm.Simulation results show that,the transmission signal's spectral side lobes are 6 dB lower than those of the two-dimensional look-up table method.And when the BER is 10-4,the proposed method also has about 2 dB gain of SNR.In addition,the convergence speed of linear convergence algorithm is increased by 75％.Thus,the proposed frequency domain predistortion scheme can improve the convergence accuracy and convergence speed effectively.