Protograph-Based LDPC Code Design for Ternary Message Passing Decoding

09/28/2018

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by   Emna Ben Yacoub, et al.

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In this paper, we develop a ternary message passing (TMP) decoding algorithm for low-density parity-check codes. All messages exchanged between variable and check nodes come from a ternary alphabet, while variable nodes still exploit soft information from the channel. A density evolution analysis is developed for unstructured and protograph-based ensembles. For unstructured ensembles the stability condition is also derived. As a result of our analysis, we present optimized ensembles for TMP decoding and show asymptotic gains of up to 0.6 dB w.r.t. ensembles optimized for binary message passing decoding. Finite length simulations of codes from TMP-optimized ensembles show gains of up to 0.5 dB under TMP compared to protograph-based codes designed for unquantized belief propagation decoding.