Joint blind frame synchronization and encoder identification of LDPC codes

Blind identification of channel coding has attracted a lot of research interest recently. It can be applied to adaptive modulation and coding (AMC) to save spectrum resources. The Low Density Parity Check (LDPC) code is suitable for almost all channel environments, and its performance is close to the Shannon limit, so it has become a research hotspot in the coding field in recent years. This paper studies the joint blind frame synchronization and encoder identification method of LDPC codes in a noisy environment. We have proposed three new methods based on the calculation of likelihood functions of the syndrome. The simulation proves that these three methods can simultaneously estimate the time delay and identify the check matrix over a candidate set, and the two-stage maximum a posteriori probability (TMAP) method has a higher identification accuracy for the check matrix with high row weights in the candidate set.