中文摘要：

为了得到更优的度分布，提出一种带梯度的粒子群优化（PSO）算法的Luby传输（LT）码度分布设计方法．利用重要抽样方法构建目标函数，并通过目标函数得到梯度估计；使用带梯度的PSO算法优化设计；用所提算法分别对2种度分布形式进行优化设计．仿真结果表明，采用带梯度的PSO算法得到的度分布使短码长LT码的头部开销更少，得到了比鲁棒孤子分布和重要抽样方法更好的度分布．

英文摘要：

Based on the particle swarm optimization （PSO） algorithm with gradient, a new design is proposed to optimize the degree distribution in the procedure of Luby transform（LT） encoding. The importance sampling approach is employed to construct an objective function. The estimation for the gradient is obtained by the objective function. And then, the degree distribution can be optimized by PSO with gradient. At last, forms with sparse degree distributions and soliton distributions are optimized with the pro- posed method respectively. Simulations show that the degree distributions obtained by the proposed method are more efficient compared with that of Robust soliton distribution and importance sampling approach, it can reduce the overhead packets in LT codes with short code-length.