摘要移动通信技术的发展随着人类社会的进步不断向前推进，新的技术发展孕育了移动通信技术的每一次。1980年左右1G模拟制式通信系统诞生， FDMA技术和大哥大是1G时代的重要标志。1990年左右2G通信系统诞生，GSM、CDMA两种模块技术扮演了主要的角色，使得发短信成为了可能。3G移动通信系统主要依托于WCDMA、CDMA2000、TD-SCDMA等模块技术，较之2G系统，数据传输速度显著提高，流媒体应用丰富了起来。但是，3G系统的发展仍然有很多不足：核心网络仍为电信网加部分IP网的构成；没有统一的全球化标准；数据传输速率还不足以满足日益多元化的需求。在第三代移动通信系统的发展进入瓶颈期之后，人们将希望寄托于新技术的发明，将目光转移到了第四代移动通信系统的研究。79006

    4G通信的关键技术有正交频分复用(OFDM)技术与多入多出（MIMO）天线技术。MIMO-OFDM系统将OFDM技术和MIMO技术相结合，合理的利用了Time、Frequency、Space三个域的分集技术，极大地提高了传输速率与信道容量，有效地增加了系统对干扰、噪声和多径衰落的容限。信道估计技术对于MIMO-OFDM系统非常关键，因此本文就该问题进行一系列研究。

    本文的第一部分首先阐述了无线通信的发展过程，交代了选题背景和意义，然后分析了无线信道的相关特性。接着分别介绍了OFDM技术和MIMO技术的基本原理、发展现状，分析了二者的优点与不足，阐明两者结合的重要意义，并建立MIMO-OFDM信道模型，用计算机对MIMO-OFDM系统性能进行仿真分析。79006

    本文的第二部分，在建立MIMO-OFDM系统模型的基础上，介绍了最小二乘（LS）估计算法和最小均方误差（MMSE）估计算法的基本原理，通过计算机仿真，比较了两种估计方法的性能。

毕业论文关键词  MIMO  OFDM  信道估计  最小二乘  最小均方误差

毕业设计说明书外文摘要

Title    Channel Estimation in MIMO-OFDM Systems         

Abstract Wireless telecommunication technology has been developed with human society, contributed to technological breakthroughs and conceptual innovation。 The first generation was originated in the 1980s, using mainly FDMA technology。 2G telecommunication system was originated around 1990, using mainly CDMA and GSM module technology。 Compared with 2G system, 3G telecommunication system can achieve highly enhanced data transmission rate and more stream media application。 However, the 3G telecommunication system has some drawbacks: No universal Standard, transmission rate not high enough, etc。 After 3G systems reach its technological limit, people turned to 4G system。

OFDM technology, which stands for orthogonal frequency pision multiplexing, and multiple-input multiple-output (MIMO) antenna technology are key technologies of 4G communication。 MIMO-OFDM system combining OFDM and MIMO make full use of time, frequency and space persity technology, which greatly improves the transmission rate and channel capacity, effectively increasing the system tolerance of interference, noise, and fading。 Channel estimation for MIMO-OFDM system is very critical, so this paper focuses on this topic。

The first part of the paper describes the development of wireless communications and explained the background and significance of the topic the paper chooses, then analyzed the wireless channel properties。 After that, the paper introduced the basic principles and current status of OFDM technology and MIMO technology, analyzing the advantages and disadvantages of both to clarify the importance of combining these two technologies。 After establishing a MIMO-OFDM channel model, performance of MIMO-OFDM Systems was simulated by computer。