QC-LDPC码的截短技术研究

摘要

Rate-compatible code is a key technique of modern wireless communication sys- tem. Shortening is one of the techniques to achieve this goal. It obtains codes of shorter length and lower rate from a given LDPC code by putting infinite reliability on some variable nodes, whose positions are assumed to be available to both encoder and decoder. With this method, codes of shorter length, lower rate and better performance can be obtained. A shortening algorithm suitable for irregular QC-LDPC codes is proposed, with the assistance of PEXIT analysis. The efficiency of the proposed algorithm is verified by both theoretical analysis and simulation.%可变码率编码是现代移动通信系统的一项关键技术。在分组码中,截短（short-ening）技术是实现这一目的主要方法之一。截短是一种通过将一些信息比特用预先约定好的值置换,从而将这些比特的置信度设为无限大的技术。通过该技术,可以缩短码长并降低码率,同时提高码字的性能。针对非规则QC-LDPC码,结合PEXIT分析方法,给出了一种优化地选取截短比特的方法。仿真结果和分析表明,本文的方法使得截短后的码字取得良好的译码性能。