Density evolution method and threshold decision for irregular LDPC codes

Density evolution is a new method for analyzing the asymptotic performance of network capability approaching error-correcting codes. For irregular LDPC codes with message-passing decoding, the density evolution method can track the messages to find out the threshold, enabling optimization of the degree distribution. In this paper, the principle of density evolution combined with the decoding process is firstly explored. Then, two algorithms for programming the evolution proceeding are discussed: the discretized density evolution and the Gaussian approximation, as well as their application conditions. Finally, simulation results are presented.