Asymptotic spectra of trapping sets in regular and irregular LDPC code ensembles

Olgica Milenkovic*, Emina Soljanin, Philip Whiting

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

87 Citations (Scopus)


We evaluate the asymptotic normalized average distributions of a class of combinatorial configurations in random, regular and irregular, binary low-density parity-check (LDPC) code ensembles. Among the configurations considered are trapping and stopping sets. These sets represent subsets of variable nodes in the Tanner graph of a code that play an important role in determining the height and point of onset of the error-floor in its performance curve. The techniques used for deriving the spectra include large deviations theory and statistical methods for enumerating binary matrices with prescribed row and column sums. These techniques can also be applied in a setting that involves more general structural entities such as subcodes and/or minimal codewords, that are known to characterize other important properties of soft-decision decoders of linear block codes.

Original languageEnglish
Pages (from-to)39-55
Number of pages17
JournalIEEE Transactions on Information Theory
Issue number1
Publication statusPublished - Jan 2007
Externally publishedYes


  • Asymptotic enumeration
  • Large deviations theory
  • Low-density parity-check (LDPC) codes
  • Trapping sets


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