摘要： 在介绍LT Code的基础上，进一步探讨了Raptor Code。预编码技术是Raptor Code采用的核心技术，该技术能够克服LT Code解码代价不固定的缺点，有鉴于该文分析了多层校验预编码技术，并以此为基础提出基于RS Code的改进方法。该方法具有解码率高等优点，适合解决网络传输的安全问题。

关键词: Raptor Code, LT Code, 预编码

Abstract: On the basis of the introduction of the LT Code, this paper explores the Raptor Code. Precoding method is the essential part in the Raptor Code and can overcome the deficiency that time and space overhead is not fixed in the LT Code. It puts forward improving method based on RS Code through the analysis of the multiple levels precoding method. The improving method has many advantages such as high decoding rate and provides appropriate solution to the problem of safe transmissions in the Internet.

Key words: Raptor Code, LT Code, Precoding