Journal of Systems Engineering and Electronics ›› 2009, Vol. 31 ›› Issue (2): 300-304.

• 电子技术 • 上一篇    下一篇

Tanner码不存在四环的充要条件

赵莹, 肖扬   

  1. 北京交通大学信息科学研究所, 北京, 100044
  • 收稿日期:2008-01-04 修回日期:2008-07-07 出版日期:2009-02-20 发布日期:2010-01-03
  • 作者简介:赵莹(1975- ),男,博士研究生,主要研究方向为信号处理,信道编码.E-mail:droing@163.com
  • 基金资助:
    国家自然科学基金(60572093)资助课题

Necessary and sufficient condition for Tanner codes without girth 4

ZHAO Ying, XIAO Yang   

  1. Inst. of Information Science, Beijing Jiaotong Univ., Beijing 100044, China
  • Received:2008-01-04 Revised:2008-07-07 Online:2009-02-20 Published:2010-01-03

摘要: 现有准循环LDPC码(QC LDPC码)的设计未考虑如何避免短环(四环)问题,而短环的存在导致QCLDPC码的误码率性能远低于随机LDPC码.为解决这一问题,提出在一类重要的准循环LDPC码—Tanner码中避免四环的定理,这些定理可作为构造Tanner码的约束条件.根据提出的定理调整校验矩阵中循环矩阵的维数和移位因子,可以构造无四环的QC LDPC码,同时扩展了Tanner码的定义.最后以实例验证了所提定理,仿真结果表明设计的Tanner码具有良好的误码率性能.

Abstract: To solve the problem of the girth 4 which will lead to a serious decrease in the performance of quasi-cyclic low-density parity-check(QC LDPC) codes,this paper presents the necessary and sufficient conditions of Tanner codes without girth 4 in the form of several theorems.These theorems can be used as the constraint conditions for the construction of Tanner codes.To construct the Tanner codes without girth 4 needs to adjust the dimension and the shift factors of the circulant matrices of the given sparse parity-check matrices according to the proposed theorems.Examples are provided to verify the theorems,and computer simulation results show that the Tanner codes obtained by proposed constructions achieve good BER performance compared with that of randomly constructed LDPC codes.

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