LLR-Based Successive-Cancellation List Decoder for Polar Codes with Multibit Decision

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29 Scopus citations


Due to their capacity-achieving property, polar codes have become one of the most attractive channel codes. To date, the successive-cancellation list (SCL) decoding algorithm is the primary approach that can guarantee outstanding error-correcting performance of polar codes. However, the hardware designs of the original SCL decoder have a large silicon area and a long decoding latency. Although some recent efforts can reduce either the area or latency of SCL decoders, these two metrics still cannot be optimized at the same time. This brief, for the first time, proposes a general log-likelihood-ratio (LLR) based SCL decoding algorithm with multibit decision. This new algorithm, referred to as LLR-2K b-SCL, can determine 2K bits simultaneously for arbitrary K with the use of LLR messages. In addition, a reduced-data-width scheme is presented to reduce the critical path of the sorting block. Then, based on the proposed algorithm, a VLSI architecture of the new SCL decoder is developed. Synthesis results show that, for an example (1024, 512) polar code with list size 4, the proposed LLR-2K b-SCL decoders achieve a significant reduction in both area and latency as compared to prior works. As a result, the hardware efficiencies of the proposed designs with K= 2 and 3 are 2.33 times and 3.32 times of that of the state-of-the-art works, respectively.

Original languageEnglish (US)
Article number7440823
Pages (from-to)21-25
Number of pages5
JournalIEEE Transactions on Circuits and Systems II: Express Briefs
Issue number1
StatePublished - Jan 2017

Bibliographical note

Publisher Copyright:
© 2016 IEEE.


  • Log-likelihood-ratio (LLR)
  • VLSI
  • multibit decision
  • polar codes
  • successive-cancellation (SC)


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