Abstract: In the linear programming decoding based on ADMM,the Euclidean projection calculation of the projection vector to the check multi-cellular body is the most complex and time-consuming part.The ADMM-LDPC decoding algorithm based on look-up tables replace the time complexity of algorithm with simple table look-up operations to simplify the projection process and improve the efficiency of the algorithm,however it expends much memory consumption.La-ter,the researchers proposed the nonuniform quantization method,which can decrease the memory consumption effectively,but the computation complexity of the quantitative method is too high,so that the way is difficult to achieve when the number of segments is too much.For this problem,this paper proposed a new nonuniform quantization method.Firstly,for different code-words,the distribution characteristics of elements in the vector are calculated to be projected under different SNRs conditions by experiment,its distribution rules are explored and the corresponding function is designed as the quantitative mapping relation.Then,differential evolution algorithm is used to optimize the parameters of the function,the optimal quantization schema under the function is obtained,and the quantization function is finally determined.The simulation results show that,compared with the existing quantitative methods,the nonuniform method proposed in this paper has the advantage of not being affected by the number of quantization segment,precision and otherfactors.What’s more,it achieves about 0.05dB performance improvement for different code words in high SNRs.

Key words: LDPC codes, Look-up tables, Nonuniform quantization, Penalized ADMM decoder