Eliminating trapping sets in low-density parity-check codes by using tanner graph covers

Miloš Ivković, Shashi Kiran Chilappagari, Bane Vasić

Research output: Contribution to journalArticlepeer-review

77 Scopus citations


We discuss error floor asympotics and present a method for improving the performance of low-density parity-check (LDPC) codes in the high SNR (error floor) region. The method is based on Tanner graph covers that do not have trapping sets from the original code. The advantages of the method are that it is universal, as it can be applied to any LDPC code/ channel/decoding algorithm and it improves performance at the expense of increasing the code length, without losing the code regularity, without changing the decoding algorithm, and, under certain conditions, without lowering the code rate. The proposed method can be modified to construct convolutional LDPC codes also. The method is illustrated by modifying Tanner, MacKay and Margulis codes to improve performance on the binary symmetric channel (BSC) under the Gallager B decoding algorithm. Decoding results on AWGN channel are also presented to illustrate that optimizing codes for one channel/decoding algorithm can lead to performance improvement on other channels.

Original languageEnglish (US)
Pages (from-to)3763-3768
Number of pages6
JournalIEEE Transactions on Information Theory
Issue number8
StatePublished - Aug 2008


  • Convolutional low-density parity-codes (LDPC) codes
  • Error floor
  • Gallager B
  • Low-density parity codes (LDPC) codes
  • Min-sum decoding algorithm
  • Tanner code
  • Trapping sets

ASJC Scopus subject areas

  • Information Systems
  • Computer Science Applications
  • Library and Information Sciences


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