长期演进论文：LTE系统下行链路的信道估计研究.doc

长期演进论文：LTE系统下行链路的信道估计研究【中文摘要】LTE是未来10年内最具影响力的宽带移动通信标准之一,为了提高数据传输效率和频谱利用率,LTE系统下行链路采用了正交频分复用(OFDM)技术。信道估计是OFDM系统的关键技术,估计的精度直接影响整个系统的性能,本文主要研究常见的信道估计算法在LTE下行链路的应用。首先对LTE的启动背景和物理层做了一个简单的介绍,讲述了OFDM和MIMO技术的基本原理。接下来讨论了无线信道的基本特性和一些重要的物理参数,并且分析了它们对无线通信系统的影响。然后对常见的导频位置信道估计算法做了理论推导,包括LS估计算法,基于DFT的信道估计算法和LMMSE信道估计算法,同时介绍了一些常见的插值算法,并对这些常见的信道估计算法做了仿真分析。本文把重点放在基于DFT的信道估计算法在LTE下行链路的应用研究上,也就是第四章的内容。第四章首先提出了一种基于DFT的信道估计算法在LTE下行链路的应用方案,然后对基于DFT的信道估计算法的不足之处做了分析和改进。比较了适用于LTE系统的两种抑制边缘效应的算法重复边缘值法和部分子载波替换法。通过仿真得出重复边缘值法性能更好,并将其应用到LTE下行链路中。接下来提出了一种改进的时域加窗算法,仿真结果表明改进算法有一定的性能提升,而且算法实现简单,适合LTE下行链路。最后对LTE下行多天线系统做了性能仿真分析,仿真结果进一步验证了本文所提出方案的可行性。【英文摘要】LTE is one of the most influential broadband mobile communication standards in the next 10 years. In order to increase data transmission efficiency and spectral efficiency, LTE systems adopted orthogonal frequency division multiplexing (OFDM) technology as the downlink transmission technology. Channel estimation is the key technology of OFDM systems, the estimated accuracy directly affects the system performance. This paper mainly studied the application of common channel estimation algorithm in LTE downlink.Firstly, the start background and the physical layer of LTE are introduced briefly, and the basic principles of OFDM and MIMO technologies are described. The discussion of the basic characteristics and some important parameters of wireless channel are made in this paper, and their impact on the wireless communication systems is analyzed. Then a detailed description of the common channel estimation is made, including the LS estimation algorithm, DFT-based channel estimation algorithm and LMMSE estimation algorithm. Some common interpolation algorithms are also introduced in this paper. The performance of these common channel estimation algorithms is analyzed through computer simulation.The application of DFT-based channel estimation algorithm in downlink of LTE systems is the focus of this paper, that is, the contents of Chapter 4.An application of DFT-based channel estimation algorithm in the downlink of LTE systems is devised in chapter 4, then the analysis and improvement about the shortcomings of DFT-based channel estimation algorithm is made. Two methods to reduce edge effect (edge value repetition method and part of subcarriers replacement method) are compared by computer simulation, the result shows edge value repetition is better, and it is applied to the downlink of LTE. Then an algorithm for time domain windowing operation is improved. The simulation results show that the performance of the improved algorithm is better than traditional algorithm. The improved algorithm is easy to implement by hardware, and is suitable for the downlink of LTE systems. Finally, the performance of multi-antenna systems of LTE is analyzed through computer simulation, and the simulation results further verify the feasibility of the proposed scheme.【关键词】长期演进 正交频分复用 信道估计 边缘效应 时域加窗【英文关键词】LTE OFDM Channel estimation Edge effect Time domain windowing operation【目录】LTE系统下行链路的信道估计研究摘要6-7Abstract7-8第1章 绪论11-211.1 LTE项目的启动背景11-121.2 LTE物理层协议和关键技术简介12-181.2.1 LTE帧结构12-131.2.2 资源单元和资源块13-141.2.3 LTE中OFDM技术简介14-171.2.4 LTE中MIMO技术简介17-181.3 信道估计的意义和研究现状18-191.4 本文的主要工作和章节安排19-21第2章 无线信道21-282.1 无线信道的特性21-242.1.1 大尺度衰落21-222.1.2 小尺度衰落22-242.2 无线信道的输入/输出模型24-252.3 空间信道模型25-28第3章 信道估计技术28-383.1 参考信号位置的信道估计算法28-333.1.1 LS算法29-303.1.2 LMMSE算法30-313.1.3 基于DFT降噪的信道估计算法31-333.2 数据位置的信道估计33-343.2.1 常值插值法333.2.2 线性插值算法333.2.3 基于DFT的插值算法33-343.2.4 阶插值算法343.3 信道估计算法仿真分析34-38第4章 LTE下行信道估计算法研究38-604.1 LTE下行参考信号图案及序列生成38-414.2 基于DFT降噪的信道估计算法在LTE下行链路中的应用研究41-514.2.1 一种基于DFT的信道估计算法在LTE