An Optimization Method of Degree Distributions Based on EXIT Chart and APSO Algorithm

Based on EXIT chart and APSO algorithm, a new method to optimize the degree distributions of irregular LDPC codes is proposed in this paper. An overall cost function is first designed to measure the matching extent of EXIT curves. Then the degree distributions are optimized iteratively by using the Adaptive Particle Swarm Optimizer (APSO) algorithm. Such a procedure needs not to fasten the Check Nodes Decoder(CND) curve. And therefore, some new degree distributions with higher noise threshold are obtained. Simulation results show that APSO-EXIT algorithm has a good performance to achieve optimal code structures, and it is more effective than Gaussian Approximation in computation.