LDPC Codes

Source Repository

The LDPC codes used in our examples are publicly available in the repository by Erdem Ray Çil and Laurent Schmalen.

Before using these codes, please review the license of the original repository. To reproduce our simulations, download the codes and build with create_bsparse_from_cil a .bsparse file with the desired code rate and quasi-cyclic expansion factor. See install_cil.sh for an example script.

See the create_bsparse_from_cil reference for full usage.

Choose of the Code Rate

For a binary input with additive white Gaussian noise channel (BIAWGNC), the code rate can be any value. For a CVQKD virtual channel, the length of a frame (\(n\)) must be divisible by the dimension (\(d\)). Since the matrices used here have a fixed initial information size of \(k = 20000\), the rate \(R = \frac{k}{n}\) must be chosen carefully so that \(n \equiv 0 \pmod{d}\).