New Stopping Criterion for Fast Low-Density Parity-Check Decoders

Low-density parity-check (LDPC) codes are favorable in low bit-error-rate and high code-rate applications. However, the decoding complexity for LDPC codes is quite large, especially for nonbinary LDPC codes. In this paper, we propose a new T-tolerance stopping criterion for LDPC decoders by exploiting the fact that the total aposteriori probability (APP) should increase across iterations when message passing (MP) algorithms are employed. Simulation results demonstrate that our proposed new T-tolerance criterion can greatly reduce the average iteration number (complexity) while the decoding performance degradation is controlled within 0.1 dB in the low bit-energy-to-noise-spectral-density ratio (E_b/N₀) scenarios.