Automorphism ensemble (AE) decoding for polar codes was proposed by decoding permuted codewords with successive cancellation (SC) decoders in parallel and hence has lower latency compared to that of successive cancellation list (SCL) decoding. However, some automorphisms are SC-invariant, thus are redundant in AE decoding. In this paper, we find a necessary and sufficient condition related to the block lowertriangular structure of transformation matrices to identify SCinvariant automorphisms. Furthermore, we provide an algorithm to determine the complete SC-invariant affine automorphisms under a specific polar code construction. 

　　Publication: 

　　2022 IEEE International Symposium on Information Theory (ISIT), Espoo, Finland, 2022, pp. 2368-2373, doi: 10.1109/ISIT50566.2022.9834828. 

　　Authors: 

　　Zicheng Ye 

　　University of Chinese Academy of Sciences; Academy of Mathematics and Systems Science 

　　Yuan Li 

　　University of Chinese Academy of Sciences; Academy of Mathematics and Systems Science; Huawei Technologies Co. Ltd. 

　　Huazi Zhang 

　　Huawei Technologies Co. Ltd. 

　　Rong Li 

　　Huawei Technologies Co. Ltd. 

　　Jun Wang 

　　Huawei Technologies Co. Ltd. 

　　Guiying Yan 

　　University of Chinese Academy of Sciences; Academy of Mathematics and Systems Science 

　　Email: yangy@amss.ac.cn 

　　Zhiming Ma 

　　University of Chinese Academy of Sciences; Academy of Mathematics and Systems Science 

　　Email: mazm@amt.ac.cn