【正文】 .......................................................... 24 加循環(huán)前后綴與升采樣 ............................................................................................................... 24 數(shù)字上變頻 ................................................................................................................................... 24 接收機設(shè)計 ............................................................................................................................................ 25 系統(tǒng)仿真參數(shù) ........................................................................................................................................ 25 系統(tǒng)性能仿真 ........................................................................................................................................ 26 七、總 結(jié) 關(guān)鍵詞： 正交頻分復(fù)用 （ OFDM） ； MATLAB；快速傅里葉變換；仿真 西南大學(xué)本科畢業(yè)論文 II Study On Key Technologies and Design and Simulation of OFDM Communication System Wang Yang School of Electronics and Information Engineering, Southwest University, Chongqing 400175, China Abstract:Orthogonal Frequency Division Multiplexing(OFDM) is a multicarrier modulation ’s principal thought is that transmitting data simultaneously over multiple equally spaced carrier frequencies and using Fast Fourier Transform processing for modulation and main advantages of OFDM versus other types of modulation are better use of the available bandwidth and better performance in multipath environments,so it has been widely used in highdatarate wireless munication systems,such as wireless localarea works and digital video broadcasting and high distinction television. This paper firstly introduces the development and applications and the theory of OFDM key technologies,then presents a implementation scheme of OFDM munication system based on ,I make use of MATLAB to simulate the transmission performance of order to pare OFDM to a traditional single carrier munication syetem,a Quadrature Amplitude Modulation (16QAM) simulation has also been performed,the result shows that OFDM has better performance in multipath environments . Key words: OFDM； MATLAB； FFT； Simulation 西南大學(xué)本科畢業(yè)論文 III 目 錄 一、緒論 與普通的通信系統(tǒng)相比 ， OFDM通信系統(tǒng)的優(yōu)點表現(xiàn)為 頻帶利用率 高和抗多 徑干擾能力強等，因此 在 很多無線環(huán)境下 應(yīng)用 廣泛，例如 WLAN（ 無線局域網(wǎng) ） 、 DVB（ 數(shù)字視頻廣播 ） 、 HDTV（高清晰度電視）。 本科畢業(yè)論文（設(shè)計） 題 目 OFDM關(guān)鍵技術(shù)的研究及其通信系統(tǒng)仿真設(shè)計 西南大學(xué)本科畢業(yè)論文 I OFDM 關(guān)鍵技術(shù)的研究及其通信系統(tǒng)仿真設(shè)計 摘 要： OFDM（ Orthogonal Frequency Division Multiplex） 意為 正交頻分復(fù)用技術(shù)，是多載波（ MCM,MultiCarrier Modulation） 調(diào)制技術(shù)之一。其主要思想是： 利用 相互正交的 多個 子載波 進行數(shù)據(jù)的 并行傳輸， 調(diào)制與解調(diào) 由 快速傅里葉變化 （ FFT） 實現(xiàn) 。 文章首先介紹了 OFDM 技術(shù)的發(fā)展 過程 、應(yīng)用及 其 關(guān)鍵技術(shù)原理，接著提出了一個基于MATLAB 的 OFDM 通信系統(tǒng)實現(xiàn)方案，最后 利用 MATLAB 軟件對 OFDM 傳輸性能進行仿真并與 16QAM（正交振幅調(diào)制，一種 傳統(tǒng)的單載波調(diào)制方式）的性能進行了比較， 仿真 結(jié)果表明 OFDM技術(shù)的抗多徑干擾能 較強。 1 二、 OFDM系統(tǒng)的基本原理 2 正交調(diào)制解調(diào) ...........................................................................................................................................2 系統(tǒng)組成 ....................................................................................................................................................5 串并轉(zhuǎn)換 ...........................................................................................................................................5 信道編碼 ............................................................................................................................................6 子載波調(diào)制 .......................................................................................................................................6 保護間隔 ............................................................................................................................................6 OFDM 技術(shù)的優(yōu)點 ...................................................................................................................................7 抗干擾能力強 ...................................................................................................................................7 頻譜利用率高 ..................................................................................................................................7 系統(tǒng)結(jié)構(gòu)簡單 ...................................................................................................................................8 OFDM 技術(shù)的缺點 ...................................................................................................................................8 PAPR（峰均功率比）值較高 .........................................................................................................8 對載波相位噪聲和頻率偏移敏感 ..................................................................................................8 OFDM 的 關(guān)鍵技術(shù) ...................................................................................................................................8 時域和頻域同步 ..............................................................................................................................8 信道估計 ............................................................................................................................................9 降低峰均功率比 ...............................................................................................................................9 三、 OFDM系統(tǒng)的 PAPR抑制算法設(shè)計 9 OFDM 信號的 PAPR 概述 .......................................................................................................................9 降低峰均功率比（ PAPR）常用的方法 ............................................................................................. 10 信號預(yù)畸變技術(shù) .....................................................................................................................