Abstract: In order to solve the problems that the error pattern set of polar codes is too large to be counted and the cyclic redundancy check code at the tail is prone to make the errors as well as the poor sorting of the revised critical set of the successive cancellation list flip (SCL-Flip) decoding algorithm, a polar code SCL-Flip decoding algorithm is proposed to optimize the error pattern set. In the algorithm, the error pattern set is reduced by reducing the number of check digits of the cyclic redundancy check code, and the cyclic redundancy check code is placed in the sequence header with the highest reliability to reduce the error as well as optimize the distance spectrum of polar codes. When the decoding fails, the revised critical set is reordered according to the row weight firstly, and then the error pattern set is searched according to the error pattern of the cyclic redundancy check to obtain the location of the first error and place it at the head of the revised critical set. This not only improves the flip accuracy but also reduces the number of the extra flip. The simulation results show that the proposed algorithm has a significant performance gain, furthermore, and the number of the flip is significantly reduced.

Key words: polar codes, cyclic redundancy check codes, error pattern set, successive cancellation list decoding, bit flip