对基于EXIT图的LDPC码优化算法的改进

就Brink方法不能自动搜索的不足，文中提出了一种基于EXIT曲线匹配的改进优化算法：DE EXIT算法.该算法构造了衡量EXIT曲线匹配程度的代价函数，利用差分进化技术由初始的矢量集开始，迭代更新集合中的每一个矢量，直至监督矢量发现最优的代价函数值.算法在给定码率的情况下，可以进行优化次数分布对的自动搜索，同时获得相应的码集噪声门限.仿真结果表明，提出的优化算法在码结构优化方面有着很好的性能，并且可以用于不同情况下的结构优化.

Improved Optimization Algorithm Based on EXIT Chart for LDPC Codes

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.