Complexity-efficient Fano decoding of polarization-adjusted convolutional (PAC) codes

Mohammad Rowshan, Andreas Burg, Emanuele Viterbo

Research output: Chapter in Book/Report/Conference proceedingConference PaperResearchpeer-review

5 Citations (Scopus)


Polarization-adjusted convolutional (PAC) codes are modified polar codes in which a one-to-oneconvolutional transformation is employed before the classical polar transform. Fano decoding of PACcodes in the Shannon lecture at ISIT2019 showed an outstanding performance at the cost of a high time-complexity, particularly at low SNR regimes. In order to reduce this complexity, an adaptive heuristic metric is proposed that improves the comparability of the variable-length paths and adjusts itself in response to the channel noise level. This metric can significantly reduce the number of nodes visited on average in tree-traversal. Additionally, a partial rewinding of the successive cancellation process is proposed to efficiently compute the intermediate LLRs and partial sums when backtracking occurs in the Fano algorithm. This method avoids storing the intermediate results of the decoding process or restarting (full rewinding) the decoding process.

Original languageEnglish
Title of host publicationProceedings of 2020 International Symposium on Information Theory and its Applications (ISITA 2020)
EditorsHiroshi Kamabe, Navin Kashyap
Place of PublicationPiscataway NJ USA
PublisherIEEE, Institute of Electrical and Electronics Engineers
Number of pages5
ISBN (Electronic)9784885523304, 9781728128559
Publication statusPublished - 2020
EventInternational Symposium on Information Theory and Its Applications 2020 - Virtual, Kapolei, United States of America
Duration: 24 Oct 202027 Oct 2020
Conference number: 16th (Proceedings)

Publication series

NameProceedings of 2020 International Symposium on Information Theory and its Applications, ISITA 2020
PublisherThe Institute of Electronics, Information and Communication Engineers (IEICE)
ISSN (Print)2689-5838
ISSN (Electronic)2689-5854


ConferenceInternational Symposium on Information Theory and Its Applications 2020
Abbreviated titleISITA 2020
Country/TerritoryUnited States of America
CityVirtual, Kapolei
Internet address

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