Construction of Low-Rate LDPC Codes from Rate-1/2 CCSDS Standard LDPC Codes
Semira Galijasevic, Linfang Wang, Jon Hamkins, Richard D. Wesel, D. Divsalar · 2025
The existing Consultative Committee for Space Data Systems (CCSDS) standard uses low-density parity-check (LDPC) codes for higher code rates including 1/2, 2/3, and 4/5, supporting message block lengths of 1024,4096, and 16384. For lower code rates, the CCSDS standard uses turbo codes, providing rates of 1/3, 1/4 and 1/6 and supporting message block lengths of 1784, 3568, and 16384. However, the frame error rate (FER) performance of the turbo codes shows an error floor where the slope of frame error rate curve begins to flatten between FERs of 10–3and 10-5. The resulting FER performance is undesirable for certain space applications. This paper uses the Protograph-Based Raptor-Like (PBRL) approach to provide new lower LDPC code rates of 1/3,1/4 and 1/6 for the existing LDPC message lengths of 1024,4096, and 16384 that are rate-compatible with the existing CCSDS rate-1/2 LDPC codes and do not suffer from an error floor (at least above FER 10–7).