Uniform quantization of LDPC codes for 8PSK modulation

It´s common to use high-precision floating-point operations on theoretical study of the Low Density Parity Check (LDPC) codes, but it is difficult to implement it in practical application. Therefore, there is a great need to design effective quantitative method which enables us to implement it in hardware easily. In this paper, the min-sum decoding algorithm of LDPC codes for 8PSK modulation is studied in detail, and the method of the uniform quantization is analyzed and deduced. With this method to quantify the initial message, the variable messages and check messages are converted into integers after each iteration. Then the min-sum decoding algorithm based on integer arithmetic for 8PSK modulation is implemented. Simulation results demonstrate that the performance of the min-sum decoding algorithm with the uniform quantization is close to that of the high-precision floating-point sum-product decoding algorithm. Meanwhile, all the variables in the algorithm are fixed-length integers, so it is convenient for hardware implementation.