摘要LTE系统作为4G无线通信的重要指标，在未来无线通信系统的地位已经得到了广泛的认可，LTE链路接收技术的研究意义重大。OFDM是LTE系统的关键技术，而信道估计作为OFDM链路接收技术的核心环节，其重要性毋庸置疑。84513

本文首先分析了无线信道的特性，再介绍了OFDM系统的原理、优缺点以及为了提高系统传输性能OFDM采取的一些措施。然后主要研究了基于OFDM系统的信道估计算法，简要说明了信道估计分为基于导频的信道估计方法，盲信道估计方法和半盲信道估计方法这三种。基于导频的信道估计由于计算复杂度较小，而且实时性高获得广泛的应用。本文主要研究的是基于导频的信道估计技术，分别描述了块状和梳状两种导频插入方式下信道估计的算法过程，再比较了各自的适用环境，在此研究了最小平方误差（LS）估计、最小均方误差（MMSE）和线性最小均方误差（LMMSE）估计，使用MATLAB对这三种估计算法性能的比较作出仿真，根据仿真结果作出分析，提出自己的看法和改善意见。

毕业论文关键词：OFDM；信道估计；导频 

ABSTRACT LTE system has been widely recognized in the future wireless communication system as an important indicator of wireless communications,Therefore, the research of LTE link receiving technology is of great significance。OFDM is the key technology of LTE system, and channel estimation is the key link of the OFDM link receiving technology, and its importance is beyond doubt。

In this paper, we first analyze the characteristics of the wireless channel，and then introduces the principle, advantages and disadvantages of the OFDM system。and some measures to improve the transmission performance of OFDM system are introduced。 Then, the channel estimation algorithm based on OFDM system is studied, and the channel estimation is pided into three kinds, which are channel estimation method based on pilot channel estimation, blind channel estimation and semi blind channel estimation。 Channel estimation based on pilot channel estimation is widely used because of its low computational complexity and high real-time performance。 The main research of this paper is based on pilot frequency channel estimation technique, which describes the block and comb two pilot insertion under channel estimation algorithm, and then compare the different application conditions, in this study the least square (LS) estimation, minimum mean square error (MMSE) and linear minimum mean square error (LMMSE) estimation, using MATLAB to the three estimation algorithm performance comparison is made between the simulation, according to the simulation results, an analysis, put forward its own views and suggestions for improvement。

Keywords:  OFDM；Channel estimation；Pilot

目录

第一章  绪论 1

1。1 研究背景 1

1。2 LTE系统概述 2

1。3 OFDM系统概述 3

1。4信道估计的研究意义和发展现状 6

1。4。1信道估计的研究意义 6

1。4。2信道估计的发展现状 6

1。5本文主要内容 7

第二章  无线通信信道分析 8

2。1无线信道分析 8

2。2信道衰落特点 9

第三章  OFDM系统原理 10

3。1 OFDM系统的优缺点 10

3。2 OFDM系统的调制和解调