一种改进的（2，1，7）Viterbi 译码器设计方法

摘要

（2，1，7）卷积码已成为商业卫星通信系统中的标准编码方法，但译码器的译码速度和硬件资源消耗一直是制约问题。提出了一种改进的设计方法，采用步进式归一化的路径度量值、全并行ACS结构和回溯法，并在软件设计中对幸存路径存储和输出单元（ SMU and OUT ）做较大改进，减少对RAM的读写次数。该方法提高了译码速度并降低了功耗，通过ModelSim10．0c仿真证明了该方法在译码性能上的优越性。%(2,1,7) convolutional code has been the standard encoding method in the system of business satellite communication , but decoder ’ s decoding speed and hardware resources ’ application are the re-strict problems .This paper proposed a modified method of Viterbi decoder for the purpose of resolving them.There are three important parts in this paper as follow:The path metric values ( calculated through the way of normalization of step by step );completely parallel structure of ACS;backtracking;the method makes great improvement in software design with regard to SMU and OUT units , and then it will decrease the number of times of reading and writing RAM .The method increases decoder speed and decreases pow-er dissipation , the analysis on simulation result of ModelSim proves that the method has great superiority in decoding performance .