中文摘要

交频分复用(OFDM, Orthogonal Frequency Division Multiplexing) 是一种特殊的多载波方案,它可以被看作一种调制技术,也可以被当作是一种复用技术｡选择OFDM的一个主要原因在于该系统能够很好地对抗频率选择性衰落或窄带干扰｡OFDM 由于其频谱利用率高,成本低等原因越来越受到人们的关注｡

本次毕业设计是利用MATLAB对OFDM进行仿真｡仿真实验是掌握系统性能的一种有效手段,它通过对仿真模型的实验结果来确定(或推断)实际系统的性能,从而为新系统的建立或原系统的改造提供可靠的参考｡

论文介绍了OFDM技术的研究意义和背景及发展趋势,还有其主要技术和对其的仿真｡具体如下:

首先介绍了OFDM的历史背景､发展现状及趋势､研究意义和研究目的及研究方法和OFDM的基本原理､基本模型､OFDM的基本传输技术及其应用,然后介绍了本课题所用的仿真工具软件MATLAB,并对其将仿真的OFDM各个模块包括信道编码､交织､调制方式､快速傅立叶变换及无线信道进行介绍,最后是对于OFDM的流程框图进行分析和在不影响研究其传输性的前提下进行简化,并且对其仿真出来的数据图形进行分析理解｡

关键词：正交频分复用,无线信道,多径效应,MATLAB,IFFT

Abstract

OFDM（Orthogonal Frequency Division Multiplexing）is one kind of special multi-carrier plan. It may be regarded as one kind of modulating technique, also can be regarded as one kind of multiplying technique. The primary cause of choosing OFDM in this project is that it can be able to resist the frequency selective declining well or the clipping interference. Due to the high frequency spectrum using OFDM, and the low cost, OFDM has been attached more and more people's attention.

This project is carried on the simulation using MATLAB for OFDM. The simulation experiment is one of effective method to understand a system and its performance. It can determine the system performance through the simulation model experiment. Therefore it can provide the reliable reference for the new system establishment or the original system updating.

The paper introduces the research significance ，the background and the trend of development of OFDM technology, and its primary technology and simulation. Specifically as follows:

Firstly, the paper introduces the historical background, the developing tendency of present situation, the research significance, the research goal, the research way of the OFDM ,and then the basic principle，basic model, basic transfer technology and application of OFDM. And then, the paper also introduces the simulation tool software MATLAB which is used in the project, and introduces each module of OFDM including the channel coding, interleaves, modulation, the fast Fournier transformation and the wireless channel in this simulation. Finally, the paper analyzes the flowing diagram of OFDM and carries on the simulations on the simplification module which does not affect the research of the transmission, and then discusses the results obtained from the simulation experiments.

Key words:  OFDM, Wireless channel, Multipart effect, MATLAB, IFFT