摘要
Abstract
QPSK(quadrature phase shift keying)data streams often suffer from phase ambiguity.In the traditional methods,for example,decoding algorithms,convolutional codes are often used to traverse and identify the starting position of code words,which will lead to various problems,such as high calculational complexity and resource occupation.Therefore,a decoding method based on soft decision for identifying the starting position of convolutional codes and eliminating QPSK phase ambiguity is proposed to effectively improve the performance of the decoding algorithms.The mathematical expressions between the convolutional code encoding sequence and the check matrix are derived,and the logical relationships between the starting position of the convolutional code word and phase ambiguity are clarified.The check matrix of the CCSDS(consultative committee for space data system)standard convolutional code is solved,and the probability of the equation being established is used as the measure of the decision.This method is suitable for deleting convolutional codes at various bit rates and has engineering practicality.The effectiveness of the proposed method has been verified with simulation analysis.The research has shown that the method does not require traversing the starting position of convolutional codes and the phase ambiguity,has strong robustness,and requires a small amount of data.As the data volume increases and the convolutional code rate decreases,the accuracy improves gradually.关键词
卷积码/码字起始位置/相位模糊/校验矩阵/软判决/QPSKKey words
convolutional code/starting position of code word/phase ambiguity/check matrix/soft decision/QPSK分类
电子信息工程
