Threshold-based design of quantized decoder for LDPC codes

The effects of quantization on the sum-product (SP) algorithm for iteratively decoding low-density parity-check (LDPC) codes are investigated. Two threshold-based designs of the quantized sum-product (Q-SP) algorithm are presented together with the results of the 4-bit decoding for several known regular codes over the additive white Gaussian noise channel. Nonuniform quantization can significantly improve the Q-SP decoding performance without increase in implementation complexity.