Memory-Aware Quasi-Cyclic Spatially Coupled LDPC Code Design for DVB-S2X Satellite Communication Systems over AWGN Channels

Abstract

Satellite communication systems are essential for global connectivity but are constrained by long propagation delays, channel impairments, and severe noise, particularly in low-SNR environments. Reliable data transmission therefore demands highly robust forward error correction techniques. Although DVB-S2X LDPC codes are widely used, they still exhibit limitations in short-cycle suppression, structural optimisation, and hardware efficiency in practical deployments. This study proposes a memory-aware QC-SC-LDPC code design for satellite communication over AWGN channels. The proposed scheme involves the combination of deterministic spatial coupling, adaptive irregular protograph generation, pairwise cycle-aware PEG algorithm for optimisation, and QC-lifting process. The use of memory-based banded coupling scheme is employed in order to increase local connectedness, minimise harmful short cycles, and enable faster decoding convergence along with high implementation efficiency. Numerical simulation analysis carried out using the DVB-S2X short frame parameters reveals that the proposed scheme outperforms classical LDPC codes. For the QPSK 32/45 case, a coding gain of 0.36 dB is achieved at the desired FER, whereas for the QPSK 11/45 case, coding gains of 4.25 dB and 2.86 dB are realised, showing high resiliency even under very low SNR conditions. The result clearly shows that there is significant improvement in waterfall characteristics and error-floor performance. The proposed QC-SC-LDPC framework provides a scalable and hardware-efficient solution for reliable satellite communication systems, with potential extensions toward fading channels, non-terrestrial networks, and real-time hardware deployment.