基于编码的OFDM系统的C语言设计与实

文档编号:TX399  文档字数:11190,页数:34

 摘要

 在无线通信中对高速率和高质量的通信服务有所要求，OFDM技术因有高带宽利用率和强抗多径干扰的能力在近几年得到广泛的关注。OFDM是一种多载波调制技术，在20世纪60年代中期被提出，被用作发展有效的无线传输。OFDM技术被看作是一种高效的高速双向无线数据传输技术。OFDM的主要思想是把信道分成若干正交的子信道把高速的数据流转换成并行的低速数据流，调制到每个子信道进行传输。快速傅里叶算法和集成电路运算器在OFDM的幅度谱调制中发挥着重要作用。OFDM的基本应用包括DAB（Digital Audio Broadcasting，数字音频广播），WiMAX等等。
 本设计构基于C语言构建了一个完整的OFDM系统，调制和解调可以分别通过IFFT和FFT实现，通过加入卷积码提高系统性能，最后统计数据，分别画出在高斯信道和瑞利信道下的误码率曲线。
 
关键词：OFDM，卷积码，无线通信
 
ABSTRACT

In wireless communication, the high rate and high quality of communication service are required to be offered. And OFDM has the advantage of the high bandwidth efficiency and strong anti-multipath ability, so OFDM receives widespread attention in recent years. OFDM is described as a multi-carrier transmission technique which discovered in mid-1960s, and use for in developing effective wireless data transfer. It is recognized as an effective transmission technique for high speed bi-directional wireless data transfer. And the main idea of OFDM is that the Channel will be divided into several sub channels orthogonal, and then turn High-speed data signals into parallel low-speed data-flow, modulation in each of the sub channels on transmission. Fast Fourier transform (FFT) algorithm and integrated circuit implementation modulator play an influential role towards effective OFDM amplitude spectrum modulation. The basic use of the OFDM include DAB (Digital Audio Broadcasting), WiMAX and so on.
 The design constructs a complete OFDM system, and the basis property of OFDM. And the modulation or demodulation module can be achieved by IFFT and FFT respective. Add the Convolutional codes to improve the performance of the system. At last, by statistics the data, the curves of signal-to-noise ratio (SNR) - bit error in AWGN channel and Rayleigh channel is drawn.
 
Keyword：OFDM, Convolutional, Wireless communication
 
目录
 
摘要 I
ABSTRACT II
第1章 引言 1
 1.1 背景 1
 1.11 OFDM简介 1
 1.12 OFDM技术现状及其发展 1
 1.2 研究内容 3
第2章 OFDM原理及其特点 4
 2.1 OFDM原理 4
 2.11 OFDM的基本模型 4
 2.1.2 快速傅里叶变换在OFDM中的应用 5
 2.2 OFDM系统特点 5
 2.2.1 OFDM的优点 5
 2.2.2 OFDM的缺点 6
第3章 OFDM系统的设计 8
 3.1 系统设计原理 8
 3.2 FFT及IFFT的实现 8
 3.3 信道的实现 9
 3.3.2 高斯信道的产生 9
 3.3.3 瑞利信道的产生 9
 3.3 程序流程图 10
第4章 卷积码编译码的设计 11
 4.1 卷积码编码 11
 4.2 维特比译码 12
 4.2.1 维特比译码概述 12
 4.2.2 维特比译码设计思路 13
第5章 仿真结果分析 15
 5.1 信道编码及其性能分析 15
 5.2 循环前缀不同的情况下系统的性能分析 17
 5.3不同子信道数目下系统的性能 18
第6章 结束语 20
致谢 21
参考文献 22
附录 卷积码源代码 23

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