A quantization schema with negligible degradation for LDPC decoder

A quantization schema with negligible degradation for LDPC decoder is proposed. It´s based on the decoding algorithm deduced from Belief Propagation algorithm on LLR. The schema offers a quantization criterion for iteration decoder, based on the study of channel outputs. The schema is adaptable for different channel status and quantization scale. Static step lengths for hardware implementation are selected according to the proposed criterion. The performance of the proposed schema is illustrated by both structured and random codes. In simulations for 6-bits quantization, performance loss is negligible. And the schema produces less than 0.01dB degradation for 5-bits quantization above 10⁻⁵ BER and about 0.1dB for 4-bits quantization. There is no error floor of BER even around 10⁻⁷. Simulations show the coverage plays an important role in quantization process. The results of static step lengths are as good as or even better than those of the variable step lengths.