OFDM系统中记忆非线性功放基带预失真技术

研究了OFDM系统的自适应基带预失真技术。针对OFDM信号的高峰值平均功率比对非线性功率放大器敏感的特点,并考虑OFDM的宽带特性引起的功放记忆非线性效应,提出了一种基于辨识方案的非直接学习结构的自适应基带预失真技术,给出了自适应算法。仿真结果表明,该方案能有效抑制带外频谱扩散,减小带内失真,实现有记忆非线性大功率放大器(HPA)的自适应预失真。

Base-band Pre-distortion Techniques of Nonlinear Power Amplifiers with Memory in OFDM Systems

The OFDM system is characterized by the Gaussian-like signal behavior with a relatively high peak-to-average power ratio(PAPR).As a result,the performance of OFDM system is very sensitive to nonlinear distortions,which arise mainly from the high power amplifier(HPA).In addition,the wideband characteristics of transmitted signals cause the nonlinear distortions to be frequency-dependent.This paper proposes an identification-based adaptive pre-distortion scheme,which is constructed by using the indirect learning architecture,to compensate nonlinearity of the HPA with memory effects.Simulation results show that the proposed adaptive pre-distortion scheme can effectively suppress spectral re-growth and reduce in-band distortion for HPA with memory.