卫星通信功率放大器的预失真算法研究

发布时间：2018-03-18 09:00

本文选题：卫星通信　切入点：预失真　出处：《北京交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着卫星通信行业的迅速发展,高效调制技术与功率放大器逐渐广泛应用于通信系统,而这些非恒包络、高均峰比的调制信号经过高效功率放大器后会发生严重的失真,如带内失真与带外失真。其中带内失真表现为信号幅度与相位的失真,会增加误码率;带外失真则会造成频谱扩展,产生邻道干扰,降低频谱利用率。如何通过预失真技术在保证功率放大器效率的同时,提高功率放大器的线性度是功放线性化技术研究的热点。本文着重对数字基带预失真系统中的自适应算法进行了研究与改进,论文工作如下:(1)基于记忆多项式的数字基带预失真技术,本文深入研究了传统的自适应算法,并在此基础上提出了一种新的自适应步长LMS算法,即GN-LMS算法。通过仿真验证了该算法在收敛速度与精度上都有所改善。(2)通过对传统的LMS算法与RLS算法的研究与对比,发现这两类算法的优缺点具有一定的互补性,所以本文通过判断切换的方式将GN-LMS算法与RLS算法结合,得到新的判断切换算法,该算法能较好的综合这两类自适应算法的优势,并在预失真系统仿真中验证了该算法的有效性。(3)对复数域自适应算法中经典的CNGD算法与CRTRL算法进行了研究,在此基础上提出了一种基于PRNN的N-AACRTRL算法,在该算法中使用PRNN网络模型可以有效降低计算过程中的矩阵维度、减少计算复杂度;引入自适应幅度提高算法收敛性能,同时在权值矩阵更新过程中引入的高斯牛顿迭代法,不仅加入了二阶导数,而且化简了矩阵求逆部分,一定程度上提高了算法的收敛速度。通过预失真仿真验证了基于PRNN的N-AACRTRL算法能较好的补偿系统的非线性,有效抑制邻道频谱扩展。
[Abstract]:With the rapid development of satellite communication industry, high efficiency modulation technology and power amplifier are widely used in communication system, but these non-constant envelope, high average peak ratio modulation signal will have serious distortion after high efficiency power amplifier. For example, in-band distortion and out-of-band distortion, in which the in-band distortion is the distortion of the amplitude and phase of the signal, will increase the bit error rate, while the out-of-band distortion will result in the spread of the spectrum and the adjacent channel interference. Reducing spectral efficiency. How to ensure the efficiency of power amplifier by predistortion technology, Improving the linearity of power amplifier is a hot topic in the research of power amplifier linearization technology. This paper focuses on the research and improvement of adaptive algorithm in digital baseband predistortion system. The main work of this paper is as follows: (1) based on the digital baseband predistortion technique based on memory polynomials, the traditional adaptive algorithm is studied in this paper, and a new adaptive step size LMS algorithm is proposed. That is, GN-LMS algorithm. The simulation results show that the convergence speed and precision of the algorithm are improved. (2) through the research and comparison of the traditional LMS algorithm and the RLS algorithm, it is found that the advantages and disadvantages of the two algorithms are complementary to each other. So this paper combines the GN-LMS algorithm with the RLS algorithm by the way of judging the handover, and obtains a new algorithm, which can integrate the advantages of the two kinds of adaptive algorithms. In the simulation of predistortion system, the validity of this algorithm is verified. (3) the classical CNGD algorithm and CRTRL algorithm in complex domain adaptive algorithm are studied, and a N-AACRTRL algorithm based on PRNN is proposed. In this algorithm, using PRNN network model can effectively reduce the matrix dimension and reduce the computational complexity, introduce adaptive amplitude to improve the convergence performance of the algorithm, and introduce Gao Si Newton iteration method in the updating process of weight matrix. Not only the second derivative is added, but also the inverse part of the matrix is simplified, the convergence speed of the algorithm is improved to a certain extent. The results of pre-distortion simulation show that N-AACRTRL algorithm based on PRNN can compensate the nonlinearity of the system well. The spectrum spread of adjacent channels is effectively suppressed.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN722.75;TN927.2

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