论文编号:TX318论文字数:10938,页数:27
摘要
正交频分复用（Orthogonal Frequency Division Multiplex，OFDM）是一种高效并行多载波传输技术，是把高速的数据流通过串/并变换，分配到速率相对较低的若干个子信道中进行传输。OFDM技术很好的利用了控制方法，使频谱利用率有所提高。在OFDM信号内的所有子载波都在时间和频率上同步，使子载波之间的干扰被严格控制。这些复用的子载波在频域中交错重叠，但因为调制的正交性且采用循环前缀作为保护间隔，所以不会发生载波间干扰（ICI）。由于信道衰落特性的影响，传输的信息在某些区域往往会出现成片的差错，即所谓的突发错误。交织是一种非常有效且简单的对付突发差错的技术。
本文分别介绍了OFDM和交织的原理，利用C语言在VC++环境搭建了一个OFDM系统，在瑞利衰落信道下，设计不同的交织器来对该OFDM系统进行仿真和分析。通过对比误码率曲线，得出了比较理想的结果。
关键词：正交频分复用，交织，通信系统仿真
ABSTRACT
OFDM(Orthogonal Frequency Division Multiplex) is an high efficient technique of Multi-Carrier parallel transmission. Through the Serial/Parallel transform, the high-speed data streams will be assigned to a number of sub-channels which have a relatively low rate for transmission. OFDM technology can improve the utilization of spectrum by a better use of the Control Methods. All the sub-carriers in OFDM signals are synchronized in time and frequency, so that the interference between the subcarriers can be strictly controlled. These multiplexing sub-carriers staggered overlap in the frequency domain, but because of the orthogonal modulation and the use of cyclic prefix as guard interval, there will be no inter-carrier interference (ICI). As a result of the channel asthenia characteristics, the information are errors in some areas always, the so-called burst errors. Intertleaver is a very effective and simple technique to deal with burst errors.
This paper introduced the principle of OFDM and intertleaver respectively, and structures a OFDM system in a VC++ environment by the C language, design the different interleavers to simulate and analyse the OFDM system over Rayleigh fading channel. Ideal results can be obtained by better the bit error rate curves.
Keywords: Orthogonal Frequency Division Multiplexing, Interleaver, Communication System Simulation
目录
摘要I
ABSTRACTII
第1章 引言1
1.1 背景1
1.2 研究内容2
第2章 OFDM系统的基本原理3
2.1 OFDM基本原理3
2.2 OFDM中的串/并变换5
2.3 FFT在OFDM中的实现6
2.4 OFDM中的保护间隔和循环前缀6
2.5 OFDM系统的优缺点7
2.5.1 OFDM的优点7
2.5.1 OFDM的不足之处8
第3章 交织技术的原理9
3.1 交织技术的概念9
3.2 几种典型的交织器9
第4章 OFDM中的交织器设计13
4.1 OFDM中的交织13
4.2 设计与编写13
第5章 仿真和结果分析17
5.1 仿真平台17
5.2 参数设置与仿真流程17
5.3 仿真结果及分析18
第6章 结束语22
致谢23
参考文献24
交织器在编码OFDM通信系统中的应用......