Improved LDPC-like BPL Decoding Algorithm for Polar Code

• Rui Guo,
• Chenfei Zhang,
• Chen Lou,

Vol. 19, No. 1, January 31, 2025
10.3837/tiis.2025.01.013, Download Paper (Free):

• Polar codes
• BP
• List decoding
• Factor Graph
• sparse graph

Abstract

To improve the performance of BP decoding for polar codes, researchers have developed a Belief Propagation List (BPL) decoding algorithm by executing multiple BP decoders in parallel. This algorithm outperforms traditional BP decoding based on single graph decoding, although it sacrifices some complexity and delay. Unlike this basic Polar-BPL decoding mentioned above, a low-density parity check like (LDPC-like) BPL decoding algorithm has been introduced into polar codes. This algorithm performs more efficient BP decoding iterations on sparse graphs. To further reduce the complexity and delay of LDPC-like BPL, and avoid analyzing all sparse graphs, this article proposes an improved LDPC-like BPL (ILDPC-like BPL) decoding algorithm based on selecting factor graphs. This algorithm analyzes differences in permuted factor graphs and selects these graphs with non-convergent decoding results to form a decoding list, allowing decoding to be completed with fewer graphs traversed and iterations, thereby reducing complexity and delay. On this basis, to improve the reliability of this algorithm, this article further adds a path metric (PM) mechanism, which can dynamically evaluate different sparse graphs’ results in parallel decoding. The simulation results show that compared with LDPC-like BPL (random scheme), ILDPC-like BPL improves decoding performance while reducing decoding delay and complexity; Compared with basic Polar-BPL (cycle-shift scheme), this algorithm greatly reduces decoding delay and complexity while achieving similar performance.

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