Abstract: An optimization method has recently been presented by Brink to design the degree distribution of irregular LDPC codes using EXIT chart. Brink’s method is easier to visualize and program compared to density evolution, but it is unable to choose degree distribution automatically. An improved optimization algorithm based on EXIT curve fitting, DE EXIT, is proposed in this paper to overcome the drawback. The proposed algorithm can automatically choose an optimization degree distribution and obtain a corresponding ensemble threshold. Simulation results show that DE EXIT has a good performance and can be applied under different conditions to achieve optimal code structures.

Key words: EXIT chart, optimization of irregular LDPC codes, DE EXIT algorithm