基于DVR模型的低复杂度数字预失真方法

    Low Complexity Digital Predistortion Method Based on DVR Model

    • 摘要: 数字预失真技术是一种被广泛应用的功率放大器线性化技术。分解矢量旋转(DVR)数字预失真模型因其容易实现的硬件结构,良好的线性化性能,被广泛地用于功放非线性的改善。然而,DVR模型参数提取的计算复杂度与运算开销会随着算子矩阵项数和数据长度的增多而急剧增加。针对这一问题,本文提出了一种基于DVR模型的低运算复杂度数字预失真方法。所提方法包含低复杂度分解矢量旋转(LCDVR)数字预失真模型和非均匀选择采样(NSS)算法两个方面,共同减少模型参数提取时的运算开销。所提LCDVR模型通过增加算子矩阵中0项的数量,减少了所需的乘法运算操作;同时,根据信号幅度分布特点,采用NSS算法进行数据采样点选取,可以减少参数提取时所需的数据长度, 并使选择后的信号幅度分布相对均匀,便于分析LCDVR模型幅度分段值的选取。实验结果表明,当输入信号数据长度为70 000时,LCDVR模型的θmax为0.7,θmin为0.3;采用NSS算法后的数据长度为10 849时,本文所提方法的参数提取所需乘法运算量仅为DVR模型的2.24%,且能够保持相当的线性化效果。因此,本文所提方法可以在保持线性化精度的同时显著降低参数提取中的运算复杂度,具有较强的应用性和可实现性。

       

      Abstract: Digital predistortion is a widely used linearization technique for power amplifiers. The decomposed vector rotation (DVR) digital predistortion model is widely used to improve the non-linearity of power amplifier due to its easy-to-implement hardware structure and good linearization performance. However, the computational complexity and cost of parameter extraction of the DVR model will increase sharply with the increase of the number of operator matrix entries and data length. To address this issue, a digital predistortion method with low operational complexity is proposed based on the DVR model. The proposed method consists of two key components including a low complexity decomposition vector rotation (LCDVR) digital predistortion model and a non-uniform selection sampling (NSS) algorithm. These components aim to reduce the operational cost of model parameter extraction. The proposed LCDVR model reduces the multiplication operation by increasing the number of zero terms in the operator matrix. Simultaneously, according to the characteristics of signal amplitude distribution, the NSS algorithm is employed to select data sampling points. This selective sampling helps reduce the data length required in parameter extraction, leading to a relatively uniform signal amplitude distribution after selection. Such uniform distribution facilitates the analysis of the selection of amplitude segment values of the LCDVR model. The experimental results show that when the length of the input signal data is 70 000, the θmax of LCDVR model is 0.7 and θmin is 0.3, and when the length of the data after the NSS algorithm is 10 849, the multiplication computation required for parameter extraction of the proposed method is only 2.24 % of that of the DVR model, while still maintaining a substantial linearization effect. Consequently, the proposed method significantly reduces the operational complexity of parameter extraction while preserving linearization accuracy, thereby enhancing its applicability and feasibility.

       

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