基于导频辅助的OFDM无线信道估计模型研究

发布时间：2018-03-12 15:01

本文选题：导频辅助　切入点：正交频分复用　出处：《江西理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：正交频分复用技术(OFDM)作为移动通信技术领域内的核心技术之一,以其独有的传输速率快、抗多径衰落能力强以及频带利用率高等特点被众多专家学者认为是未来通信发展方向的研究重点。而信道估计作为OFDM技术内的重要构成部份,目的是为了保证能够较为精确地在接收端还原出信道的状态信息,以提升系统的整体通信质量。本文主要是围绕基于导频辅助的OFDM无线信道估计模型而进行的研究,主要的研究工作与创新点如下:(1)对信号在无线信道内的传输特性进行了研究,详细地介绍了多径衰落的统计特性,并给出了信道的冲激响应模型。对OFDM相关核心技术进行了研究,重点讨论了它的基本工作原理、系统结构模型及其重要组成部份,围绕OFDM技术内基于导频辅助的无线信道估计模型进行了深入地探讨,分析了块状、梳状以及散状三类导频的结构,重点对LS、MMSE、LMMSE与SVD-LMMSE四类较为典型的导频位置处信道估计方式进行了研究,并介绍了几类子载波位置处较为常见的插值方案。(2)对传统的LMMSE算法进行了细致地研究,由于其在对信道响应进行估计的过程中,必须要对繁复的矩阵进行求解计算,并且需要提前知道信道的统计特性,针对这一问题文中基于信道能量分布的稀疏性特征引入了加权系数平均法来解决,在此基础上联合小波对符号进行处理,并进行实验仿真设计。结果表明,改进信道估计模型的整体性能要优于传统的LS算法、SVD-LMMSE算法、LMMSE算法以及仅通过加权系数平均法改进的LMMSE算法。(3)对传统的SVD-LMMSE算法进行了深入地研究,虽然其对传统的LMMSE算法做出了简化地处理,但是却存在着信道估计误差较大的问题,针对这一缺陷文中联合引入小波与经验模态分解法来进行克服,在此基础上再加入阈值门限对符号进行处理。最后,进行实验的仿真设计,结果表明,改进信道估计模型的整体性能要优于传统的LS算法、LMMSE算法以及目前较为流行的SVD-LMMSE信道估计算法。
[Abstract]:OFDM (orthogonal Frequency Division Multiplexing) is one of the core technologies in the field of mobile communication. The characteristics of strong anti-multipath fading ability and high bandwidth efficiency are considered by many experts and scholars to be the focus of future communication development. Channel estimation is an important part of OFDM technology. The purpose of this paper is to ensure that the channel state information can be accurately restored at the receiver to improve the overall communication quality of the system. This paper mainly focuses on the pilot assisted OFDM wireless channel estimation model. The main research work and innovation are as follows: (1) the transmission characteristics of signals in wireless channels are studied, and the statistical characteristics of multipath fading are introduced in detail. The impulse response model of the channel is given. The core technologies of OFDM are studied, and its basic working principle, system structure model and its important components are discussed. The pilot-assisted wireless channel estimation model in OFDM technology is discussed, and the structure of block, comb and scattered pilot is analyzed. In this paper, four typical channel estimation methods at pilot position are studied, including LSS-MMSE and SVD-LMMSE, and several common interpolation schemes at sub-carriers are introduced. The traditional LMMSE algorithm is studied in detail. In the process of estimating the channel response, the complex matrix must be solved and calculated, and the statistical characteristics of the channel must be known in advance. To solve this problem, the weighted coefficient averaging method is introduced to solve this problem based on the sparse characteristic of channel energy distribution. Based on this, the symbol is processed by joint wavelet, and the experimental simulation is carried out. The results show that, The overall performance of the improved channel estimation model is better than that of the traditional LS algorithm / SVD-LMMSE algorithm and the traditional SVD-LMMSE algorithm, which is only improved by the weighted coefficient averaging method. Although the traditional LMMSE algorithm is simplified, the channel estimation error is large. In this paper, wavelet and empirical mode decomposition are combined to overcome this defect. On the basis of this, threshold threshold is added to deal with the symbol. Finally, the simulation design of the experiment is carried out, and the results show that, The overall performance of the improved channel estimation model is better than that of the traditional LS algorithm and the current popular SVD-LMMSE channel estimation algorithm.
【学位授予单位】：江西理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.53

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