成对插入删减信道下的LDPC码编译码算法研究

发布时间：2018-06-28 02:33

本文选题：差错控制 + 同步错误　；参考：《西安电子科技大学》2014年硕士论文

【摘要】：信息传输过程中,由于噪声的影响和制造技术的限制,接收端在提取有效信息时难以同步或根本无法同步,这就导致了同步错误(synchronization error)的发生。同步错误,即在传输过程中插入(insert)或删除(delete)一些信息比特,这会对整个通信系统造成灾难性的后果。由于同步错误相互之间完全独立,所以接收方很难纠正这些错误。随着人们对信息传输速率和信息存储容量要求越来越高,同步错误也越来越频繁的发生在通信和存储系统中。会发生同步错误的信道就是同步信道。在一般的同步信道中,同步错误的出现是完全随机的,即插入错误和删除错误相互之间没有任何影响,但是在一些最新的通信系统中,如bit-patterned媒体记录格式系统中,经常会出现插入错误和删除错误成对出现的情况,纠同步错误以及纠成对插入删减错误的编译码算法研究已经引起了广泛的关注。低密度奇偶校验码(Low-density Parity Check,LDPC)是用稀疏校验矩阵定义的一类线性码,由于它拥有较低的译码复杂度和良好的纠错能力,因此被广泛应用在同步信道下的编解码技术中。本文对同步信道下的LDPC码译码算法进行了研究,给出了级联编码方案下的比特级同步和符号级同步两种译码方案的阐述和实现,并在此基础上提出了一种新的成对插入删减信道模型,随后通过仿真实现了该信道下的比特级和符号级译码方案。本文的主要工作概括如下:1.概述了信道编码理论的发展历程,详细介绍了LDPC码的基础理论,分别给出了比特级和符号级下求最大后验概率(Maximum a Posteriori,MAP)的仿真实现,仿真结果表明符号级译码算法相对于比特级译码算法拥有更好的性能。2.设计了一种新型的成对插入删减信道模型,分析了该信道的特点,给出了在该信道下的比特级MAP检测算法的仿真实现,仿真结果表明了在成对插入删减信道下比特级译码算法的有效性。3.详细分析了成对插入删减信道下使用符号级译码时信道状态的转移类型,给出了符号级下求最大后验概率的仿真实现,仿真结果表明了在成对插入信道下符号级译码算法的有效性,同时表明了该算法相对于此信道下的比特级译码算法拥有更好的性能。
[Abstract]:In the process of information transmission, due to the influence of noise and the limitation of manufacturing technology, it is difficult or impossible for the receiver to synchronize or not synchronize when extracting effective information, which leads to the occurrence of synchronization error (synchronization error). Synchronization errors, that is, inserting (insert) or deleting some (delete) bits during transmission, can have disastrous consequences for the entire communication system. Because synchronization errors are completely independent of each other, it is difficult for the receiver to correct them. With the increasing demand for information transmission rate and information storage capacity, synchronization errors occur more and more frequently in communication and storage systems. The channel where synchronization errors occur is the synchronization channel. In general synchronization channels, synchronization errors are completely random, that is, insert errors and delete errors do not affect each other, but in some of the latest communication systems, such as the bit-patterned media record format system, Insertion errors and deletion errors often occur in pairs. The research of encoding and decoding algorithms for correcting synchronous errors and correcting pair insertion and deletion errors has attracted much attention. Low-density parity check (LDPC) is a class of linear codes defined by sparse check matrix. Because of its low decoding complexity and good error-correcting ability, it is widely used in the coding and decoding techniques in synchronous channels. In this paper, the decoding algorithms of LDPC codes in synchronous channel are studied, and the decoding schemes of bit-level synchronization and symbol level synchronization under concatenated coding scheme are described and implemented. On this basis, a new channel model of pairwise insertion and deletion is proposed, and then the scheme of bit and symbol level decoding in this channel is realized by simulation. The main work of this paper is summarized as follows: 1. This paper summarizes the development of channel coding theory, introduces the basic theory of LDPC code in detail, and gives the simulation implementation of maximum a Posteriorion map at the bit and symbol levels, respectively. The simulation results show that the symbol level decoding algorithm has better performance than the special level decoding algorithm. In this paper, a novel pairwise insertion and deletion channel model is designed, and the characteristics of the channel are analyzed, and the simulation implementation of the bit-level map detection algorithm under the channel is given. The simulation results show that the algorithm is effective in pairwise insertion and deletion channel. The transition type of channel state when symbol level decoding is used in pairwise insertion and deletion channel is analyzed in detail, and the simulation realization of maximum posterior probability at symbol level is given. The simulation results show the effectiveness of the symbol level decoding algorithm in the pairwise insertion channel and show that the algorithm has better performance than the binary decoding algorithm in this channel.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN911.22

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