采用新型峰均比降低技术的OFDM功放线性化方案

OFDM power amplifier linearization with novel PAPR reduction technique

针对OFDM信号的高峰均比问题,提出了一种将新型峰均比降低技术与数字预失真技术相结合的功率放大器线性化方案.其中,峰均比降低技术由传统的削峰技术、新型的削谷技术和闲置载波技术组成,信号的峰值和谷值同时被削去,峰均比得到最大程度的压缩.传统削峰技术用于降低信号的峰值;新型的削谷技术采用基于切线原理的矢量孔调整法,同时改变信号的幅度和相位,使得信号谷值变大;闲置载波技术用于减少削峰削谷处理所产生的带内和带外失真.实测结果表明,基于记忆多项式模型的数字预失真技术可以将功放输出信号的ACPR值优化10.5 dB,而在结合了新型峰均比降低技术之后,本方案可以将ACPR值进一步优化18.5 dB.该方案适用于未来4G通信系统.

In order to combat high peak-to-average power ratio（PAPR） of orthogonal frequency-division multiplexing（OFDM） signals,a power amplifier linearization with a novel PAPR reduction technique is proposed.The PAPR reduction technique is composed of a traditional peak clipping,a novel valley clipping processing,and unused tones technique.Both peak and valley value of signal are clipped,and the PAPR can therefore be reduced to the minimum.Traditional peak clipping is employed to clip the peak of signal.The valley clipping is achieved through a vector hole punching technique of circle-tangent shifting,which changes both magnitude and phase of signal.And the use of unused tones is employed to reduce both the out-of-band and in-band distortion caused by the peak and valley clipping.Test results show that a 18.5 dB ACPR（adjacent channel power ratio） reduction for power amplifier output can be achieved by employing this technique,while a 10.5 dB reduction is attained by using only digital predistortion based on memory polynomial model.This technique can be applied to future 4G communication systems.