Protograph-Based Raptor-Like LDPC Codes

Tsung-Yi Chen, Kasra Vakilinia, Dariush Divsalar, Richard D. Wesel
2015 IEEE Transactions on Communications  
This paper proposes protograph-based Raptor-like (PBRL) codes as a class of rate-compatible (RC) LDPC codes for binary-input AWGN channels. As with the Raptor codes, exclusive-OR operations on precoded bits produce additional parity bits providing extensive rate compatibility. Unlike Raptor codes, each additional parity bit in the protograph is explicitly designed to optimize the density evolution threshold. During the lifting process, ACE and CPEG constraints are used to avoid undesirable
more » ... ical structures. Some density-evolution performance is sacrificed to obtain lower error floors, especially at short blocklengths. Simulation results are shown for information block sizes of k = 1032 and 16384. For a target frame error rate of 10 −5 , at each rate the k = 1032 and 16384 code families perform within 1 dB and 0.4 dB of both the Gallager bound and the normal approximation, respectively. The 16384 code family outperforms the best known standardized code family, the AR4JA codes. The PBRL codes also outperform DVB-S2 codes that have the advantages of longer blocklengths and outer BCH codes. Performance is similar to RC code families designed by Nguyen et al. that do not constrain codes to have the PBRL structure and involve simulation in the optimization process at each rate.
doi:10.1109/tcomm.2015.2404842 fatcat:h7djghoqmvaivmptbbe2b6q5om