Journal of Systems Engineering and Electronics ›› 2011, Vol. 22 ›› Issue (2): 183-187.doi: 10.3969/j.issn.1004-4132.2011.02.001

• ELECTRONICS TECHNOLOGY •     Next Articles

Design of good QC-LDPC codes without small
girth in the p-plane

Lingjun Kong1, 2, * and Yang Xiao1   

  1. 1. Institute of Information Science, Beijing Jiaotong University, Beijing 100044, P. R. China
    2. Faculty of Information Engineering and Automation, Kunming University of Science and Technology,
    Kunming 650500, P. R. China
  • Online:2011-04-19 Published:2010-01-03

Abstract:

A construction method based on the p-plane to design
high-girth quasi-cyclic low-density parity-check (QC-LDPC) codes
is proposed. Firstly the good points in every line of the p-plane
can be ascertained through filtering the bad points, because the
designed parity-check matrixes using these points have the short
cycles in Tanner graph of codes. Then one of the best points from
the residual good points of every line in the p-plane will be found,
respectively. The optimal point is also singled out according to
the bit error rate (BER) performance of the QC-LDPC codes at
last. Explicit necessary and sufficient conditions for the QC-LDPC
codes to have no short cycles are presented which are in favor
of removing the bad points in the p-plane. Since preventing the
short cycles also prevents the small stopping sets, the proposed
construction method also leads to QC-LDPC codes with a higher
stopping distance.