基帶OFDM系統(tǒng)的設計與仿真

電子信息工程論文編號:DZXX226  論文字數(shù):10043,頁數(shù):27

目錄

摘要 I
ABSTRACT II
第1章 引言 1
1.1 背景 1
1.2 研究內(nèi)容 2
第2章 OFDM系統(tǒng)的基本原理 3
2.1 OFDM基本原理 3
 2.2 FFT在OFDM系統(tǒng)中應用 5
 2.3 保護間隔和循環(huán)前綴 6
第3章 OFDM的主要技術(shù) 8
 3.1信道編碼和交織 8
3.1.1卷積碼 8
 3.1.2 交織 9
 3.2 同步問題研究 10
3.3 數(shù)字調(diào)制 11
3.3.1 QPSK 11
3.3.2 QAM 12
第4章 基于卷積碼的OFDM系統(tǒng)設計 14
4.1 系統(tǒng)模型及仿真流程 14
4.2  OFDM幀結(jié)構(gòu)設計 14
4.3信道 15
4.3.1 AWGN信道 15
 4.3.2 瑞利衰落信道 15
第5章 仿真及結(jié)果分析 16
5.1 仿真平臺 16
5.2 參數(shù)設置 17
5.3 仿真結(jié)果分析 17
5.3.1 不同信道下的誤碼率 18
5.3.2 加入交織技術(shù)的誤碼率 21
第6章 結(jié)束語 22
致謝 23
參考文獻 24

摘要

 正交頻分復用（Orthogonal Frequency Division Multiplex，OFDM）是一種高效并行多載波傳輸技術(shù)，將所傳送的高速串行數(shù)據(jù)分解并調(diào)制到多個并行的正交子信道中，從而使每個子信道的碼元寬度大于信道時延擴展，再通過加入循環(huán)擴展，保證系統(tǒng)不受多徑干擾引起的碼間干擾（ISI）的影響。他可以有效對抗多徑傳播。
 本文設計了一個基于卷積碼的OFDM系統(tǒng)，并在計算機上進行了仿真和結(jié)果分析。全文主要由三部分構(gòu)成：OFDM系統(tǒng)基本原理、基于卷積碼的OFDM系統(tǒng)設計、仿真及結(jié)果分析。
 本文完成了對一個完整的基帶OFDM系統(tǒng)的設計與仿真，用MATLAB語言實現(xiàn)了整個系統(tǒng)的計算機仿真并給出參考設計程序。最后分別比較了在AWGN信道與瑞利衰落信道,16QAM調(diào)制與QPSK調(diào)制條件下，加入卷積碼，加入交織對OFDM系統(tǒng)性能的影響,得出了較理想的結(jié)論。

關(guān)鍵詞：正交頻分復用，卷積編碼，四相相移鍵控，正交幅度調(diào)制，通信系統(tǒng)仿真

ABSTRACT
 Orthogonal Frequency Division Multiplexing is a highly efficient parallel multi-carrier transmission technology. It will decompose a high-speed serial data and modulate it to multiple parallel subchannels, so that the width of each subchannels Symbol is larger than the channel delay expansion .Than adds cycle of expansion to ensure that systems from multipath interference ,it will cause the interference between the Symbol (ISI) impact. It can be effective against multi-path transmission.
 In this thesis, basing on convolutional code ,a OFDM system is analyzed, designed and simulated on a computer. The thesis mainly consists of three parts: the basic principles of OFDM system, the design of OFDM system witch based on convolutional code, the system simulation and the analysis of the results.
 This paper has designed and simulated an intergrated baseband OFDM system, simulated the system with MATLAB language and given reference design process. Finally, in the conditions of AWGN channel and Rayleigh fading channel, 16 QAM modulation and QPSK modulation , adding convolution code, and by adding cutting , depicts the error rate OFDM system of comparison curve,and obtaines many satisfactory conclusion.
 
Keywords: OFDM, convolution encoding, QPSK, 16QAM, telecom system simulation