Information-Optimum LDPC Decoders with Message Alignment for Irregular Codes

Article Number
8648053
Citation
IEEE Global Communications Conference (GLOBECOM 2018)
Contribution to Conference
IEEE Global Communications Conference, GLOBECOM 2018  
Publisher DOI
10.1109/GLOCOM.2018.8648053
Scopus ID
2-s2.0-85054759120
In practical implementations, message passing decoding of LDPC codes has to be implemented with finite precision, i.e., the messages are quantized with a small number of bits. This results in a significant performance degradation with respect to decoding with high-precision messages. Recently, we have proposed so-called information bottleneck decoders to design finite-precision decoders with error-correction performance close to high-precision belief-propagation decoding. Earlier works solely focus on the design of information bottleneck decoders for regular LDPC codes or specifically optimized irregular LDPC codes. In this paper, we extend the concept of information bottleneck decoders to irregular LDPC with arbitrary degree distribution. We show that this extension is not straightforward and requires an additional information-optimum step. Therefore, we devise a novel intermediate construction step which we call message alignment. Exemplary numerical simulations using an irregular LDPC code taken from the IEEE 802.11 standard show that incorporating message alignment in the construction yields a 4-bit information bottleneck decoder which performs only 0.15 dB worse than a double-precision belief propagation decoder and outperforms a min-sum decoder.