In this letter, a novel class of sparse codebooks is proposed for sparse code multiple access (SCMA) aided non-terrestrial networks (NTN) with randomly distributed users characterized by Rician fading channels. Specifically, we first exploit the upper bound of bit error probability (BEP) of an SCMA-aided NTN with large-scale fading of different users under Rician fading channels. Then, the codebook is designed by employing pulse-amplitude modulation constellation, user-specific rotation and power factors. To further reduce the optimization complexity while maintaining the power diversity of different users, an orthogonal layer-assisted joint layer and power assignment strategy is proposed. Finally, unlike existing SCMA codebook designs that treat all users as one super-user, we propose to minimize the BEP of the worst user to ensure user fairness. The simulation results show that the proposed scheme is capable of providing a substantial performance gain over conventional codebooks.
Cite
@article{arxiv.2504.04928,
title = {Advanced Codebook Design for SCMA-aided NTNs With Randomly Distributed Users},
author = {Tianyang Hu and Qu Luo and Lixia Xiao and Jiaxi Zhou and Pei Xiao and Tao Jiang},
journal= {arXiv preprint arXiv:2504.04928},
year = {2025}
}