Recognition Algorithm for DB-CTC in DVB_RCS Protocol Using Average Conformity of Parity-check Equation

Channel coding parameter analysis meant reversely analyzing and estimating the coding parameters, and played an important role in applications like cooperative communication, intelligent communication and information interception. This paper presented an identification algorithm for the code lengths and puncturing patterns of the double binary convolutional turbo codes (DB-CTC) in DVB_RCS protocol, based on the average conformity of parity-check equation. Firstly, the concept and calculation method of the average conformity of parity-check equation were given, and the parity-check equations between the information sequences and the check sequences of each puncturing pattern were also derived. Then, the DB-CTC parameters were identified, using the two truths that the separation of received sequences was performed according to these parameters and the correctly separated sequences could maximize the average conformity of parity-check equation. Simulation results show that the proposed algorithm can effectively identify the true code length and puncturing pattern under low signal-to-noise ratios for different code rates.