宽带接收机非线性补偿技术的研究

发布时间：2019-01-05 14:36

【摘要】：随着近三十年来通信行业的飞速发展,各种通信设备大量涌现,发射机和接收机作为通信系统中不可缺的环节,支撑着现代通信技术不断创新。但发射机和接收机自身的非线性特性,会大大降低整个系统的通信质量和通信效率。发射端常采用的多载波调制技术,如QPSK、QAM、OFDM会产生较高的峰均比(PAPR),使发射机中的功率放大器工作在饱和点以下,非线性失真严重。接收机前端由放大器、ADC、混频器等构成,其非线性特性会给信号带来严重的非线性失真,影响信号的正确接收。因而对线性化技术提出了高要求。在结合非线性系统模型和自适应算法基础上,本文主要针对数字接收机端非线性补偿技术做深入研究,主要工作为:1.对国内外现有的线性化技术做了分类,针对每种技术做了相应的介绍。2.归纳了非线性系统的基本理论。以放大器为例,分析了非线性特性、交调失真、记忆效应等;并列举出了无记忆非线性模型和记忆非线性模型,针对常见的记忆模型进行了建模对比;最后列出了衡量非线性失真的指标。3.考虑接收机中,强信号产生的非线性失真分量可能会淹没弱信号,导致接收终端无法正确解调出弱信号的情况,引入了先进的盲识别和补偿技术,同时对盲识别的准则及自适应补偿技术中非线性记忆补偿模型参数的更新做了全面的分析。最后通过多个测试信号,验证了自适应补偿算法的可行性。4.考虑接收机中,除了信号的自身非线性失真外,信号间相互作用产生的互调失真也会对有用信号的接收产生影响。同样采用自适应补偿技术,结合去嵌入线性项重建无记忆多项式模型,构建了非线性失真的补偿算法。仿真对比了信号补偿前后的功率谱和星座图,同时对信号在不同输入功率下,补偿前后的EVM值做了分析,说明了算法的有效性。
[Abstract]:With the rapid development of the communication industry in the past 30 years, a large number of communication devices have emerged. As an indispensable link in the communication system, transmitters and receivers support the continuous innovation of modern communication technology. But the nonlinear characteristics of transmitter and receiver will greatly reduce the communication quality and efficiency of the whole system. The multi-carrier modulation technology often used in transmitter, such as QPSK,QAM,OFDM, will produce a higher peak-to-average ratio (PAPR) than (PAPR), which makes the power amplifier in the transmitter work below the saturation point, and the nonlinear distortion is serious. The receiver front end consists of amplifiers, ADC, mixers and so on. The nonlinear characteristics of the receiver will bring serious nonlinear distortion to the signal and affect the correct reception of the signal. Therefore, a high requirement for linearization technology is put forward. Based on the nonlinear system model and adaptive algorithm, this paper mainly focuses on the digital receiver terminal nonlinear compensation technology, the main work is as follows: 1. The existing linearization technology at home and abroad is classified, and the corresponding introduction for each technology is given. 2. The basic theory of nonlinear system is summarized. Taking the amplifier as an example, the nonlinear characteristics, intermodulation distortion and memory effect are analyzed, and the memoryless nonlinear model and memory nonlinear model are given, and the common memory models are compared. Finally, the index of measuring nonlinear distortion is listed. 3. Considering that the nonlinear distortion component generated by the strong signal may drown the weak signal in the receiver, the receiver can not demodulate the weak signal correctly, so advanced blind recognition and compensation techniques are introduced. At the same time, the parameter updating of nonlinear memory compensation model in adaptive compensation technology and the criterion of blind recognition are analyzed. Finally, the feasibility of the adaptive compensation algorithm is verified by a number of test signals. 4. In the receiver, in addition to the nonlinear distortion of the signal itself, the Intermodulation distortion caused by the interaction between the signals will also affect the reception of the useful signal. The adaptive compensation technique is also used to reconstruct the memoryless polynomial model combined with the deembedding of the linear term, and a nonlinear distortion compensation algorithm is constructed. The power spectrum and constellation diagram before and after the signal compensation are compared, and the EVM values before and after compensation are analyzed under different input power, which shows the effectiveness of the algorithm.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN851

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