One and Two Bit Message Passing for SC-LDPC Codes with Higher-Order Modulation
Journal article, 2019

Low complexity decoding algorithms are necessary to meet data rate requirements in excess of 1 Tbps. In this paper, we study one and two bit message passing algorithms for belief propagation decoding of low-density parity-check (LDPC) codes and analyze them by density evolution. The variable nodes exploit soft information from the channel output, and to decrease the data flow, the messages exchanged between check and variable nodes are represented by one or two bits. The newly proposed quaternary message passing (QMP) algorithm is compared asymptotically and in finite length simulations to binary message passing (BMP) and ternary message passing (TMP) for spectrally efficient communication with higher-order modulation and probabilistic amplitude shaping (PAS). To showcase the potential for high throughput forward error correction, spatially coupled LDPC codes and a target spectral efficiency of 3 bits/QAM symbol are considered. Gains of about 0.7 dB and 0.1 dB are observed compared to BMP and TMP, respectively. The gap to unquantized belief propagation decoding is reduced to about 0.75 dB. For smaller code rates, the gain of QMP compared to TMP is more pronounced and amounts to 0.24 dB in the considered example.


Fabian Roland Steiner

Technical University of Munich

Emna Ben Yacoub

Technical University of Munich

Balázs Matuz

German Aerospace Center (DLR)

Gianluigi Liva

German Aerospace Center (DLR)

Alexandre Graell I Amat

Chalmers, Electrical Engineering, Communication and Antenna Systems, Communication Systems

Journal of Lightwave Technology

0733-8724 (ISSN)

Vol. 37 23 5914-5925

Rethinking Distributed Storage for Data Storage and Wireless Content Delivery

Swedish Research Council (VR), 2016-01-01 -- 2019-12-31.

Areas of Advance

Information and Communication Technology

Subject Categories


Atom and Molecular Physics and Optics

Condensed Matter Physics



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