Performance of LDPC codes under faulty iterative decoding

Research output: Contribution to journalArticlepeer-review


Departing from traditional communication theory where decoding algorithms are assumed to perform without error, a system where noise perturbs both computational devices and communication channels is considered here. This paper studies limits in processing noisy signals with noisy circuits by investigating the effect of noise on standard iterative decoders for low-density parity-check (LDPC) codes. Concentration of decoding performance around its average is shown to hold when noise is introduced into message-passing and local computation. Density evolution equations for simple faulty iterative decoders are derived. In one model, computing nonlinear estimation thresholds shows that performance degrades smoothly as decoder noise increases, but arbitrarily small probability of error is not achievable. Probability of error may be driven to zero in another system model; the decoding threshold again decreases smoothly with decoder noise. As an application of the methods developed, an achievability result for reliable memory systems constructed from unreliable components is provided.

Original languageEnglish (US)
Article number5895097
Pages (from-to)4427-4444
Number of pages18
JournalIEEE Transactions on Information Theory
Issue number7
StatePublished - Jul 2011
Externally publishedYes


  • Communication system fault tolerance
  • decoding
  • density evolution
  • low-density parity-check (LDPC) codes
  • memories

ASJC Scopus subject areas

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


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