码率兼容低密度奇偶校验码构造算法研究

发布时间：2018-01-13 05:29

本文关键词：码率兼容低密度奇偶校验码构造算法研究　出处：《国防科学技术大学》2014年硕士论文　论文类型：学位论文

【摘要】：现代无线通信系统对于高吞吐量需求的与日俱增,促使码率兼容技术应运而生。相较于传统固定码率传输模式,结合了码率兼容差错控制编码的混合自动重传请求系统能够有效提高数据的传输效率。在现有诸多类别的差错控制编码中,LDPC(Low-Density Parity-Check)码最有可能在多种信道条件下迫近香农容量,因此受到了越来越广泛的关注。鉴于LDPC码的诸多优点,构造性能良好、复杂度低的码率兼容LDPC码并将其应用于混合自动重传请求系统,是一项具有意义的研究工作。论文围绕码率兼容LDPC码的构造展开研究,对母码构造、扩展算法设计、删除算法设计等多个方面进行深入分析探讨,构造实现了一类理想的码率兼容LDPC码,主要工作和创新点总结如下:1、分析影响LDPC码性能的几类因素,提出了基于ACE(Approximate Cycle Extrinsic message degree)优化的类IRA(Irregular Repeat Accumulate)码构造算法,实现了一类结构化、低复杂度和低存储的LDPC码构造,为速率兼容算法的实现奠定了基础。2、基于类IRA码的一致校验矩阵结构,分别针对奇偶节点和信息节点扩展算法展开研究。在对奇偶节点扩展时,采用高斯近似理论分析了度为1的节点在扩展时的作用,选择以度为1的节点进行奇偶节点扩展;在对信息节点扩展时,提出了基于M-PEG(Modified Progressive Edge Growth)算法的扩展算法,在最大化围长的同时增强了扩展矩阵与原始矩阵间的依赖关系。3、基于类IRA码的双对角线结构,提出一类高效的删除算法。该算法以降低删除节点恢复步数为原则,采用先假设全部删除、再逐一恢复的方法逆向确定节点删除顺序,能够有效降低节点删除对码性能的影响。4、与现有的几种码率兼容LDPC码性能进行对比,根据影响LDPC码性能的几个主要因素,结合校验矩阵扩展和节点删除需要遵循的几点原则,对本文所构造的码率兼容LDPC码存在性能优势的原因进行分析研究。根据仿真中得到的数据,结合Ⅱ型HARQ(Hybrid Automatic Repeat Request)系统数据传输机制,对基于码率兼容LDPC码的Ⅱ型HARQ系统吞吐性能进行对比与分析。
[Abstract]:In modern wireless communication system for high throughput requirements grow with each passing day, the rate compatible technology is proposed. Compared with the traditional fixed rate transmission mode, combined with the error control encoding rate compatible hybrid automatic retransmission request system can effectively improve the efficiency of data transmission rate. In many existing categories of error control encoding, LDPC code (Low-Density Parity-Check) the most likely close to Shannon capacity under different channel conditions. So it has attracted more and more attention. In view of the advantages of LDPC code structure, good performance, low degree of complex rate compatible LDPC code and its application in hybrid automatic repeat request system, it is a significant research work. The rate of compatible with the LDPC code structure is studied, the mother code structure, extended algorithm design, a deletion algorithm design in-depth analysis to explore, construct To achieve an ideal rate compatible LDPC code, the main work and innovation points are summarized as follows: 1, analysis of several factors affect the performance of LDPC codes, is proposed based on ACE (Approximate Cycle Extrinsic message degree IRA (Irregular) optimization Repeat Accumulate) code construction algorithm, implement a structured, low complexity and low storage LDPC codes, laid the foundation for the realization of the.2 algorithm for rate compatible, the parity check matrix structure of IRA codes based on the research on parity nodes and information node expansion algorithm respectively. In the expansion of the parity node, approximate theory to analyze the degree of 1 nodes in the expansion of the Gauss, with 1 degrees of nodes of the parity node expansion; in the expansion of information nodes, is proposed based on M-PEG (Modified Progressive Edge Growth) algorithm is extended, in the maximum girth at the same time Enhanced the extension matrix and the original matrix dependency between.3 and dual diagonal structure IRA codes based on a kind of efficient delete algorithm. The proposed algorithm to reduce the number of steps to restore deleted nodes using the first principle, the assumption that all deleted, then the reverse recovery method to determine the node deletion sequence, can effectively reduce the node remove the influence on the performance of.4 code, compatible with the existing several rate compared to the performance of LDPC codes, according to several main factors affecting the performance of LDPC codes, with the parity check matrix expansion and node delete several principles to follow, compatible LDPC code performance advantage of the proposed rate were analyzed according to the simulation. The data obtained, combined with type II HARQ (Hybrid Automatic Repeat Request) data transmission system, the throughput rate compatible type HARQ system based on LDPC code comparison And analysis.

【学位授予单位】：国防科学技术大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN911.22

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