CUED Publications database

Polar Code Constructions Based on LLR Evolution

Qin, M and Guo, J and Bhatia, A and GuillenFabregas, A and Siegel, PH (2017) Polar Code Constructions Based on LLR Evolution. IEEE Communications Letters, 21. pp. 1221-1224. ISSN 1089-7798

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Polar code constructions based on mutual information or Bhattacharyya parameters of bit-channels are intended for hard-output successive cancellation (SC) decoders, and thus might not be well designed for use with other decoders, such as soft-output belief propagation (BP) decoders or successive cancellation list (SCL) decoders. In this letter, we use the evolution of messages, i.e., log-likelihood ratios, of unfrozen bits during iterative BP decoding of polar codes to identify weak bit-channels, and then modify the conventional polar code construction by swapping these bit-channels with strong frozen bit-channels. The modified codes show improved performance not only under BP decoding, but also under SCL decoding. The code modification is shown to reduce the number of low-weight codewords, with and without CRC concatenation.

Item Type: Article
Uncontrolled Keywords: Polar codes belief propagation decoding successive cancellation list decoding
Divisions: Div F > Signal Processing and Communications
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:32
Last Modified: 15 Apr 2021 06:57
DOI: 10.1109/LCOMM.2017.2656126