Fast list decoders for polarization‐adjusted convolutional (PAC) codes

• Published in: IET communications Vol. 17; no. 7; pp. 842 - 851
• Main Authors: Zhu, Hongfei, Cao, Zhiwei, Zhao, Yuping, Li, Dou, Yang, Yanjun
• Format: Journal Article
• Language: English
• Published: Stevenage John Wiley & Sons, Inc 01-04-2023; Wiley
• Subjects: Algorithms; channel coding; Codes; Complexity; Constituents; Convolutional codes; Decoders; Decoding; Error correction; Error correction & detection; information theory; Nodes; Performance degradation; polar codes; Polarization; signal processing
• ISSN: 1751-8628; 1751-8636
• DOI: 10.1049/cmu2.12587

A latest coding scheme named polarization‐adjusted convolutional (PAC) codes is shown to approach the dispersion bound for the code (128,64) under list decoding. However, to achieve the near‐bound performance, the list size of list decoding needs to be excessively large, which leads to insufferable time complexity. In this paper, to improve the speed of list decoding, fast list decoders for PAC codes are proposed. Four types of constituent nodes are defined and fast list decoding algorithms are provided for each of them. Simulation results present that fast list decoding with three types of constituent nodes can yield exactly the same error‐correction performance as list decoding, and reduce more than 50% time steps for the code (128,64). Moreover, fast list decoding with four types of constituent nodes can further reduce decoding complexity with negligible performance degradation.
In this paper, to improve the speed of list decoding, fast list decoders for PAC codes are proposed. Four types of constituent nodes are defined and fast list decoding algorithms are provided for each of them. Simulation results present that fast list decoding can yield exactly the same error‐correction performance as list decoding with no or negligible performance degradation.