On LLR Calculations for Soft-decision Decoding in Next-generation IM-DD Systems with Laser RIN

Felipe Villenas; Yunus Can Gültekin; Alex Alvarado

On LLR Calculations for Soft-decision Decoding in Next-generation IM-DD Systems with Laser RIN

Signal Processing 2026-07-10 v1

Authors: Felipe Villenas , Yunus Can Gültekin , Alex Alvarado

Abstract

We propose a low-complexity LLR approximation for SD decoding in IM-DD systems with relative intensity noise. Our approximation results in no BER performance penalty for a concatenated KP4+Hamming FEC scheme, and outperforms mismatched AWGN-based LLRs.

Cite

@article{arxiv.2607.09433,
  title  = {On LLR Calculations for Soft-decision Decoding in Next-generation IM-DD Systems with Laser RIN},
  author = {Felipe Villenas and Yunus Can Gültekin and Alex Alvarado},
  journal= {arXiv preprint arXiv:2607.09433},
  year   = {2026}
}

Comments

To be presented at ECOC 2026