Adaptive pre-distortion techniques based on orthogonal polynomials
Adaptive pre-distortion techniques based on orthogonal polynomials
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基于正交多项式的自适应预失真技术
DOI：
10.1109/acssc.2010.5757879
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
M. Rupp
中科院分区：
文献类型：
--
作者：
R. Dallinger;Henri Ruotsalainen;R. Wichman;M. Rupp
数字基带中的预失真是使频谱高效通信系统的发射功率放大器线性化的一种经济有效的方法。从信号处理的角度来看，预失真器的功能结构主要由选择哪个模型的决定以及所选择的自适应算法来确定。在过去的二十年中，在文献中，已经提出并分析了大量的预失真器结构。在这项工作中，我们专注于简单和常用的模型（维纳模型和Hammerstein模型）组成的线性滤波器和静态非线性。后者表示使用正交多项式的基础。首先，应用实际的传输信号，不同的正交多项式基的最小二乘估计的数值条件，并就梯度方法的收敛行为进行了比较。在第二步中，采用正交多项式的预失真器分别通过间接学习结构、非线性滤波-x最小均方算法来适应。基于仿真和突发测量与商业功率放大器，这种预失真系统的实际性能进行了研究。
Pre-distortion in digital baseband is a cost-effective method to linearise the transmit power amplifiers of spectrally efficient communication systems. From a signal processing point of view, the functional structure of the pre-distorter is primarily determined by the decision which model to choose, as well as by the selected adaptive algorithm. During the last two decades, in literature, a multitude of pre-distorter structures has been proposed and analysed. In this work, we focus on simple and commonly employed models (the Wiener model and the Hammerstein model) consisting of a linear filter and a static nonlinearity. The latter is represented using a basis of orthogonal polynomials. First, applying practical transmission signals, different orthogonal polynomial bases are compared with respect to the numerical condition of least squares estimation, and with respect to the convergence behaviour of gradient methods. In a second step, pre-distorters which employ orthogonal polynomials are adapted by the indirect learning structure, respectively, the nonlinear filtered-x least mean squares algorithm. Based on simulations and burst measurements with a commercial power amplifier, the real-world performance of such pre-distortion systems is investigated.