一种LT码度分布优化方法

作为一类码率不受限的纠删码，Luby变换(Luby transform, LT)码已成功地应用于无线通信，实现数据的可靠传输。度分布是影响LT码性能优劣的关键因素。然而，传统的鲁棒孤子分布(Robust soliton distribution, RSD)在LT码码长较短下的性能不够理想。针对该问题，提出一种适用于二进制删除信道(Binary erasure channel, BEC)的新型LT码度分布优化方法。基于度分布重要特性，采用人工鱼群算法(Artificial fish swarm algorithm, AFSA)对RSD中某些重要度数的比例进行寻优。仿真结果表明，与类似方法及传统的RSD相比，采用新度分布进行LT编码可降低译码开销，并节约编译码耗时。

An Optimization of Degree Distribution for LT codes

As a class of rateless erasure codes, Luby transform (LT) codes are successfully applied to the reliable data transmission in wireless communication. Degree distribution is critical to the performance of LT codes. However, the classical robust soliton distribution (RSD) is not suitable for short-length LT codes. To solve the problem, a method is proposed to optimize the degree distribution for LT codes over binary erasure channel (BEC). Based on the properties of degree distribution, the artificial fish swarm algorithm (AFSA) is used to optimize the proportions of some important degrees in RSD. Simulation results show that compared to other optimized degree distributions and RSD, the new degree distribution reduces the overhead, and saves the average consuming time per encoding/decoding process.