Protograph-Based LDPC Code Design for Probabilistic Shaping with On-Off Keying

This work investigates protograph-based low-density parity-check (LDPC) codes for the additive white Gaussian noise (AWGN) channel with on-off keying (OOK) modulation. A non-uniform distribution of the OOK modulation symbols is considered to improve the power efficiency especially for low signal-to-noise ratios (SNRs). To this end, a specific transmitter architecture based on time sharing is proposed that allows probabilistic shaping of (some) OOK modulation symbols. Tailored protograph-based LDPC code designs outperform standard schemes with uniform signaling and off-the-shelf codes by l.ldB for a transmission rate of 0.25bits/channel use and by 0. 9dB for 0.67bits/channel use.