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
