摘要无线移动通信技术目前已经成为了通信技术研究中的重点，而OFDM技术因其优质的性能而被广泛使用，拥有极为广阔的应用前景。为使OFDM系统在实际应用中能拥有最佳性能，有必要对OFDM系统进行仿真。80395

本文简述了OFDM技术的历史背景和应用现状，介绍了其基本原理及主要特点，并利用MATLAB完成了对OFDM调制解调的仿真，对其在不同信噪比和不同调制方式下的误码率做了进一步仿真分析，最后简述了多普勒频移对系统的影响及其克服方法。

仿真结果显示，OFDM技术大幅度降低了系统的误码率，文中定性分析了误码率与调制方式和信噪比之间的关系。通过对OFDM系统的MATLAB仿真可有效发现实际应用中潜在的缺陷，为实际应用提供参考。

毕业论文关键词  OFDM  正交频分复用   多普勒频移  MATLAB

毕业设计说明书外文摘要

Title  Research on simulation technology of OFDM modulation and demodulation                                   

Abstract Wireless mobile communication technology has become the focus of the research of communication technology。 At the same time, OFDM has been widely used for its high quality performance and also has a very broad application prospects。 In order to enable the OFDM system to have the best performance in the practical application, it is necessary for us to simulate the OFDM system。

The paper briefly introduces the historical background, application status, basic principle and main features of OFDM technology。 I also completed the simulation of OFDM modulation and demodulation by using MATLAB。 The bit error rate under different signal to noise ratio and different modulation methods are further simulated and analyzed。 Finally, the influence of Doppler shift on the system and the way to overcome it are briefly described in the paper。

The simulation results show that OFDM technology not only greatly reduces the bit error rate of the system, but also qualitatively explains the relationship between the bit error rate and the other two aspects----signal to noise ratio and modulation modes。 Through the MATLAB simulation of the OFDM system, we can effectively find potential defects of the actual application to provide a reference for the practical application。

Keywords  OFDM  orthogonal frequency pision multiplexing   Doppler shift  MATLAB

目   次

1  绪论 3

2  OFDM概述 4

2。1  OFDM的产生和发展 4

2。2  OFDM的主要特点 4

2。3  OFDM的应用现状与前景 6

3  OFDM调制解调信号的产生 8

3。1  MATLAB简介 8

3。2  OFDM系统组成 8

3。3  随机信号产生 9

3。4  串并变换 10

3。5  子载波的调制与解调 11

3。5。1  QPSK调制 15

3。5。2  QPSK解调 17

3。6  DFT/IDFT的实现 18

3。7  保护间隔与循环前缀 19

3。8  并串变换 23

3。9  信道特性