对基于EXIT图的LDPC码优化算法的改进

Improved Optimization Algorithm Based on EXIT Chart for LDPC Codes

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.

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.