一族适用于空间通信的原型图LDPC码

摘要

Taking aim at the higher complexity of decoding AR4JA codes and the characters of space communication,a new protograph based rate compatible family of LDPC codes were constructed.The difference between the decoding thresholds of these codes and their capacity limits is within about 0.5 dB.These codes also have minimum distance growing linearly with code length,which is of advantage for low error floor performance.In addition,a common decoder can be used for decoding all rates with the same protograph.In the aspects of theory and computer simulation,protograph based LDPC was compared with AR4JA protograph based LDPC which was proposed for CCSDS by NASA JPL.The compared result shows that the performances of both are of little difference,but the latter'S computational complexity is higher than the former.%针对已有AR4JA码译码复杂度较高的问题,结合空间通信的特点,构造了一族新的基于原型图的码率兼容LDPC码.这族码的译码门限距信道容量都在0.5 dB内,而且最小码距随码长线性增长,从而有利于降低误码平台.此外,由于具有相同的原型图结构,可以用同一个译码器完成不同码率码的译码.本文从理论和计算机仿真两方面说明,所提出的原型图LDPC码与NASA JPL向CCSDS递交的AR4JA原型图LDPC码相比,性能相近.而译码计算复杂度更低.