Digital Fountain Code Coding And Decoding Design Optimization And Simulation Analysis

With the rapid development of mobile communication systems,users have put forward higher requirements for the reliable transmission of information in wireless channels.Fountain code,as a new channel coding technology with variable code rate,has the characteristics of low coding complexity,adaptive channel state change and no need for feedback,and can provide new solutions for many complex transmission paths.In recent years,fountain code has gradually become one of the research hotspots in the field of wireless transmission.In order to ensure the reliability of information transmission,and improve the quality of communication,especially in the channel coding complexity and how to strike a balance between the efficiency of signal transmission,this paper puts forward a new type of LT codes,fixed degree distribution function with the linear precoding LDPC code cascade to generate a new Raptor code,analyzes its performance advantages,and compared to verify the transmission performance in AWGN channel.This paper first introduces the coding and decoding theory of LT code,analyzed the performance and influence factors of LT code,carried out detailed analysis and research on the fixed degree distribution function of LT code,and proposed a new LT code coding scheme based on the fixed degree distribution function.Although the performance of LT code based on poisson degree distribution function is good,the performance of LT code gradually decreases with the increase of code length m.Compared with the LT codes of poisson's degree distribution function,LT codes based on the new fixed degree distribution function have good performance no matter when the code length is small or large,and retain the characteristic that the average degree of poisson's degree distribution function is a constant.Based on Raptor coding and decoding principle,an new Raptor code is generated by cascading LT code and LDPC based on the new fixed degree distribution function.In order to comprehensively verify the cascade scheme,AWGN channel model was selected to compare different code lengths with traditional Raptor.The result shows that the improved Raptor code has better decoding performance when the code length is short.