Novel Blind Identification of LDPC Code Check Vector Using Soft-decision

In non-cooperative conditions, the identification of LDPC codes is a complicated issue in channel coding. Aiming at the problems of poor fault tolerance and low recognition rate of existing recognition algorithms of LDPC code verification vector, an iterative recognition algorithm of LDPC code verification vector is proposed in this paper. In the algorithm, the logarithmic likelihood ratio of the parity relation is constructed, and a pre-judgment method of the parity vector is proposed, which greatly reduces the search space of constructing the parity vector. Then, under the condition of soft-decision, using the generalized logarithmic likelihood ratio, the vector in the search space is judged and the check vector is obtained. Finally, multiple sets of data are used to iteratively identify the check vectors in the search space, and the new data is decoded with the result of iteration recognition, so as to improve the reliability of the new data. The experimental results show that the vector search space of the proposed algorithm is greatly reduced, and the recognition rate is also significantly improved in low SNR environment, and the gain of the algorithm can be increased by about 2.3 dB.