Soft-Bit Decoding of Regular Low-Density Parity-Check Codes

Sheryl L. Howard, Vincent C. Gaudet, Christian Schlegel

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


A novel representation, using soft-bit messages, of the belief propagation (BP) decoding algorithm for low-density parity-check codes is derived as an alternative to the log-likeli-hood-ratio (LLR)-based BP and min-sum decoding algorithms. A simple approximation is also presented. Simulation results demonstrate the functionality of the soft-bit decoding algorithm. Floating-point soft-bit and LLR BP decoding show equivalent performance; the approximation incurs 0.5-dB loss, comparable to min-sum performance loss over BP. Fixed-point results show similar performance to LLR BP decoding; the approximation converges to floating-point results with one less bit of precision.

Original languageEnglish (US)
Pages (from-to)646-650
Number of pages5
JournalIEEE Transactions on Circuits and Systems II: Express Briefs
Issue number10
StatePublished - Oct 2005


  • Belief propagation (BP)
  • iterative decoding algorithms
  • low-density parity-check (LDPC) codes
  • soft output decoding

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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