Analysis and Design of Binary Message-Passing Decoders
Abstract
Binary message-passing decoders for low-density parity-check (LDPC) codes are studied by using extrinsic information transfer (EXIT) charts. The channel delivers hard or soft decisions and the variable node decoder performs all computations in the L-value domain. A hard decision channel results in the well-know Gallager B algorithm, and increasing the output alphabet from hard decisions to two bits yields a gain of more than 1.0 dB in the required signal to noise ratio when using optimized codes. The code optimization requires adapting the mixing property of EXIT functions to the case of binary message-passing decoders. Finally, it is shown that errors on cycles consisting only of degree two and three variable nodes cannot be corrected and a necessary and sufficient condition for the existence of a cycle-free subgraph is derived.
Cite
@article{arxiv.1004.4020,
title = {Analysis and Design of Binary Message-Passing Decoders},
author = {Gottfried Lechner and Troels Pedersen and Gerhard Kramer},
journal= {arXiv preprint arXiv:1004.4020},
year = {2016}
}
Comments
8 pages, 6 figures, submitted to the IEEE Transactions on Communications