过高的峰均比（PAPR,peak-to-average power ratio）是正交频分复用技术（OFDM,Orthogonal Frequency-Di-vision Multiplexing）的一个主要缺陷。PAPR抑制技术的应用可以最大限度地减小的非线性失真,提高功率放大器（HPA,High Power Amplifier）的效率。在OFDM系统中,随着载波数的增加,PAPR性能会变差。本文使用了一种削波滤波（CF,Clipping＆Filtering）与星座图扩展（ACE,Active Constellation Extension）相结合的方法,可以在无数据率损失的情况下减小PAPR。在本方案中,计算出一个标准OFDM信号的PAPR数据作为参考。先对信号进行CF操作,把信号的PAPR值限制到很低的幅度,再用星座图扩展的方法恢复MER指标,就可以让信号进入非线性功放之前降低PAPR,并保证带外噪声符合发射机的要求。最后,把经过处理的OFDM信号和原始OFDM信号同时送入不同功率回退（IBO）参数的HPA进行了对比。实验结果表明,把信号送入功率回退为7dB的HPA,经过PAPR抑制算法处理的信号带肩比可以改善2dB以上,MER改善1dB以上。%High peak-to-average power ratio（PAPR） is one of the major drawbacks of Orthogonal Frequency-Division Multiplexing（OFDM）.PAPR reduction can be utilized to decrease the nonlinear distortion and to improve the power efficiency of the nonlinear HPA（high power amplifier）.In an OFDM system,as the frame size increases,the PAPR probability performance will get worse.In this paper,a novel approach,clipping-and-filtering（CF） scheme with the proposed active constellation extension（ACE） algorithm is presented to reduce the PAPR without any date rate loss.In our proposal,the target PAPR is firstly set and the level clipping is fundamentally used.ACE algorithm is then applied to improve be MER performance characteristics for the OFDM system.Finally,we analyze the PAPR reduction effects on HPA and show the performance variation in the HPA nonlinear characteristic according to change of IBO（input back off） value.By the results of proposed method,we can confirm that the proposed combined system shows better MER and shoulder level performance even in when the effect of HPA is considered.
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