Reduced Complexity Belief Propagation Decoding Algorithm for Polar Codes Based on the Principle of Equal Spacing

Yinfang HONG  Hui LI  Wenping MA  Xinmei WANG  

IEICE TRANSACTIONS on Communications   Vol.E98-B   No.9   pp.1824-1831
Publication Date: 2015/09/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E98.B.1824
Type of Manuscript: PAPER
Category: Fundamental Theories for Communications
polar codes,  BP decoding algorithm,  equal spacing,  linear approximation,  

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In the log-likelihood ratio (LLR) domain, the belief propagation (BP) decoding algorithm for polar codes incurs high computation complexity due to the computation of the hyperbolic functions in the node update rules. In this paper, we propose a linear approximation method based on the principle of equal spacing to simplify the hyperbolic functions in the BP decoding algorithm. Our method replaces the computation of hyperbolic functions with addition and multiplication operations in the node update rules. Simulation results show that the performance of the modified BP decoding algorithm is almost the same as the original BP decoding algorithm in the low Signal to Noise Ratio (SNR) region, and in the high SNR region the performance of our method is slightly worse. The modified BP decoding algorithm is only implemented with addition and multiplication operations, which greatly reduces computation complexity, and simplifies hardware implementation.