基于QAM与时变信道下的OFDM同步技术研究

发布时间：2018-01-11 23:10

本文关键词：基于QAM与时变信道下的OFDM同步技术研究　出处：《电子科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着信息传输的高效与高速化,正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)技术成为新一代通信系统和标准的调制技术之一。而对于在时变信道下进行的OFDM传输,还存在很多的技术瓶颈。因此本文主要就时变信道下OFDM系统中的同步在以下四个方面进行了较全面而深入的研究。第一,无线信道的衰减作用和同步误差的影响。论文对OFDM应用的无线信道特性进行了分析,主要分析多径信道各个参数的具体影响,并具体分析两种典型衰落信道。然后是同步误差对OFDM系统性能的影响。论文对OFDM系统中符号定时误差、载波频率误差与相位误差、采样定时偏差与采样时钟偏差等多种同步偏差对系统产生的影响通过推导进行了详细而全面的分析。第二,OFDM系统下典型同步算法的研究。论文仔细分析了已有的典型的各种同步算法,包括SC算法、基于CP以及联合ML算法进行符号定时同步,基于训练序列方法和典型的Moose算法进行小数倍载波频偏估计,同时针对载波相偏进行了同步研究及算法改进,最后分析一种采样时钟同步算法。本章主要研究对比各个算法的同步估计性能,在AWGN信道下进行基础的算法性能仿真,为时变信道的同步分析作对比。第三,时变信道下OFDM系统的同步研究。本章先分析时变信道下同步算法的变化,然后前一章中典型算法分析的基础上,分别就符号定时同步、载波频率同步上做出算法的改进策略。分析与仿真表明,这些算法应对多径衰落及多普勒频移,有较好的性能,提高了估计精度。第四,同步算法的实现。本文首先利用数值原理分析同步实现方案,并改进在算法中各个部分实现结构,优化资源消耗;其次,联合Matlab、ModelSim等仿真工具验证算法开发的有效性。
[Abstract]:With the high efficiency and high speed of information transmission, orthogonal Frequency Division Multiplexing is realized by orthogonal Frequency Division Multiplexing (OFDM). OFDM (OFDM) technology has become one of the new generation communication systems and standard modulation techniques, and for the OFDM transmission in time-varying channels. There are still a lot of technical bottlenecks. So this paper mainly focuses on the synchronization of OFDM systems in time-varying channels in the following four aspects of a more comprehensive and in-depth study. First. The attenuation of wireless channel and the effect of synchronization error. This paper analyzes the characteristics of wireless channel of OFDM application, mainly analyzes the specific influence of each parameter of multipath channel. Then, the effect of synchronization error on the performance of OFDM system is analyzed. The symbol timing error, carrier frequency error and phase error in OFDM system are discussed in this paper. The effects of sampling timing deviation and sampling clock deviation on the system are analyzed in detail and comprehensively. Research on typical synchronization algorithms in OFDM system. This paper carefully analyzes the existing typical synchronization algorithms, including SC algorithm, symbol timing synchronization based on CP and joint ML algorithm. Based on the training sequence method and the typical Moose algorithm, the carrier frequency offset is estimated, and the synchronization of carrier phase offset is studied and the algorithm is improved. Finally, a sampling clock synchronization algorithm is analyzed. This chapter mainly studies and compares the synchronization estimation performance of each algorithm, and simulates the performance of the algorithm based on AWGN channel. Compare the synchronization analysis of time-varying channels. Thirdly, the synchronization of OFDM systems in time-varying channels. This chapter first analyzes the changes of synchronization algorithms in time-varying channels, and then on the basis of the analysis of typical algorithms in the previous chapter. The improved algorithms for symbol timing synchronization and carrier frequency synchronization are made respectively. The analysis and simulation show that these algorithms have better performance and improve the estimation accuracy. 4th for multipath fading and Doppler frequency shift. The realization of synchronization algorithm. Firstly, this paper analyzes the implementation scheme of synchronization by numerical principle, and improves the structure of each part of the algorithm to optimize the resource consumption. Secondly, the simulation tools such as Matlab Model Sim are used to verify the validity 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】：TN929.53

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