AR4JA codes

The AR4JA family of LDPC codes as specified in the CCSDS experimental standard

Please see our paper, “On Distance Properties of Quasi-Cyclic Protograph-Based LDPC Codes" for our detailed analysis results.

The code family is proposed for deep space operation. For a precise definition of the code, visit ccsds.org for the standard (see section 7.4 of CCSDS 131.0-B-3 Blue Book for "TM SYNCHRONIZATION AND CHANNEL CODING") for AR4JA.

The code is specified for several rates and block lengths.

k = information bits per block

n = block length in bits per block (after puncturing)

M = overall expansion factor, which also corresponds to the number of variable nodes punctured per block

The number of parity check equations per block is n+M-k.

The base AR4JA protograph is expanded in two steps in the standard: first by a factor of 4, and then by a factor M/4.

To help validate our results I've made the parity check matrices that I've generated from the standard available to all. Two WinZip archives contain Alist or MATLAB format files of the AR4JA parity check matrices.

A third WinZip archive contains the AR4JA generator matrices created per the standard in MATLAB format. (WinZip archives are in the .zip file format, archive at bottom of page)