一种改进的(2,1,7)Viterbi译码器设计方法

A Modified Design Method of (2,1,7)Viterbi Decoder

(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 restrict 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 power dissipation,the analysis on simulation result of ModelSim proves that the method has great superiority in decoding performance.