Switch degree distribution: an improved degree distribution for LT digital fountain code
开关度分布：一种改进的LT数字喷泉编码度分布

The degree distribution applied in the LT digital fountain code encoder is a key factor to the decoding efficiency. This paper presents an improved degree distribution which is called Switch Distribution. It combines the advantages of binary exponential distribution and robust soliton degree distribution. When the degree of the coded packets is chosen from Switch Distribution, it can generate enough encoded packets with small degrees. This distribution decreases the number of encoded packets when the decoding process firstly starts and decreases the number of source transmitted packets for recovering the source information successfully at the distination. We obtain the best switch point by simulation. Compared with using Robust Soliton Distribution and Binary Exponential Distribution, using Switch Distribution can greatly increase the decoding efficiency.