一种峰值功率控制的带限数字预失真算法

Band-limited digital predistortion algorithm based on peak power control

针对宽带无线通信系统中数字预失真技术反馈回路存在模数转换器ADC的采样速率高、预失真后信号峰均比(PAPR)增大的问题,提出一种结合峰值功率控制的带限数字预失真算法。通过设置阈值门限,对预失真后的信号幅度进行控制以减小其PAPR;运用带通滤波器限制ADC采样带宽并通过频谱外推方法完成对带限输出信号的完整估计,实现ADC采样速率的降低。实验结果表明,该算法不仅能降低系统采样速率,而且能有效提升功放的线性度,相对于传统预失真技术,功放输出信号的邻道功率比改善约5dB。

As the analog to digital converter(ADC) needed in feedback circuit based on digital predistortion(DPD) technology in broadband wireless communication system has high sampling rate and increasing PAPR after predistortion,a band-limited digital predistortion algorithm based on peak power control is proposed. The threshold is set to control the signal amplitude after predistortion to reduce the PAPP. The band-pass filter is used to limit the sampling bandwidth of ADC,and the spectral extrapolation method is used to accomplish the integrated estimation for the band-limited output signal,so as to reduce the ADC sampling rate. The experimental results demonstrate that the algorithm can reduce the system sampling rate and improve the linearization of the power amplifier. In comparison with the traditional predistortion technology,the adjacent channel power ratio of the power amplifier′s output signal is reduced by about 5dB.