多种级联码纠错系统的研究与设计

【作者】 万慧琳；

【导师】 殷奎喜；

【作者基本信息】 南京师范大学 ， 电路与系统， 2007， 硕士

【摘要】 移动通信是当今通信领域内最为活跃、发展最为迅速的领域之一，在新世纪内对社会发展和人类生活产生了重大影响。然而，随着民用移动通信的用户数量的不断增加，业务范围不断扩大，频率资源和可用频道数之间的矛盾日益尖锐，这个时期的移动通信发展重点在于开发新的频段、论证新方案和有效利用频谱等方面的研究工作。信道编码是数字移动通信中的关键部分，它可以使得信号能够更好地抵抗如噪声和衰落等信道损耗的影响，从而改进通信系统的性能。信道编码的目的是为了降低所需要的信噪比，或者可以选择为给定的能够达到的信噪比降低误差概率。为了达到这个目标需要花费更大的带宽。本文引入级联码，目的是为了将它应用于信道编码以改进系统的纠错性能。本文对四种常用的纠错码如HAMMING码、BCH码、RS码、卷积码根据级联码的构成原理，引入交织器，讨论了五种级联码分别在BPSK、QPSK、π╱4-QPSK的调制方式下的蒙特卡罗仿真实验。仿真结果表明：在所要达到的误码率条件下，级联码与单个码相比，尤其与未编码的情况相比，获得了较大的编码增益，而系统的复杂度并没有增加。同时，我们也得出，在不同的调制方式下，误码率的性能也是存在一定的差别。此外，基于数字移动通信中编码及调制的特点，着重分析了在π／4-QPSK调制下的不同级联码的性能差别，旨在找出误码性能较好且频谱利用率较高的级联编码。以上的仿真实验为级联码能应用在移动通信系统的前向信道编码中提供了理论基础，具有一定的实际意义。更多还原

【Abstract】 Mobile communication is one of the most active and rapid development fields in the communication, it produces great influence on the society development and human life in the new century. However, with the increased number of users and extended operation areas, the contradiction between frequency resource and channels turns more acutely. During this period, the emphases of the mobile communication development is, that beginning the research work with developing new channels, new demonstration methods and using frequency spectrum effectively.Channel code is the key point of the digital mobile communication, it can make the signals withstand influence such as noise and fading more effectively, which can improves the performance of the communication system. The purpose of channel code is to make the SNR reduced, or reduce the BER for the given SNR. For this, we have to expend larger bandwidth.In the article, we introduce the concatenated code, which is used in channel code to improve the system correction ability. First, we make the simulation on four types of codes such as HAMMING code, BCH code, RS code, Convolution code. Second, according to the constitution principle of the concatenated code, we make five different kinds of concatenated codes simulation with interlace and three different ways of modulation such as BPSK, QPSK,π/4-QPSK. The results indicates, compared with the single coding, especially the un-encoding, the concatenated coding acquired much coding plus in the term of given BER, however, the system complexity is not increased. Meanwhile, we get different BER results on different modulation methods. Moreover, based on the characters of the mobile communication system, we also analyses the different performance between different concatenated coding withπ/4-QPSK modulation. The purpose is to split the difference between better BER and better use of frequency spectrum. Above of the simulation experiences provide theory basis for the concatenated coding, which is used in the mobile system, it is meaningful actually.更多还原