The existing methods for channel coding recognition usually use hard-decision of the demodulator output sequence

and their robustness against error bits is to be improved.Focusing on situations of low signal-to-noise ratio

this paper presents a novel recognition algorithm which uses soft-decision.The algorithm is based on the error-containing equation model

and it solves the equation

thus accomplishes the recognition

through regarding the probability that the equation holds right as the measurement of the performance of a solution vector.The use of log-likelihood ratio(LLR) algebra makes the algorithm greatly simplified.Results of simulation experiments show that the new algorithm improves recognition performance

especially in lower signal-to-noise ratio cases

compared to the existing algorithm based on Walsh-Hadamard transform.