Power Multiplexing NOMA and Bandwidth Compression for Satellite-Terrestrial Networks

Due to the spectrum scarcity in the space information networks, non-orthogonal multiple access (NOMA) is envisioned as a promising technique in satellite-terrestrial communications networks as its improved system capacity and spectral efficiency. In this paper, to further improve the spectrum utilization efficiency in satellite-terrestrial networks, bandwidth compression (BC) design is embedded in the NOMA scheme, which contributes to the non-orthogonality both in power and frequency domains, named BC-NOMA. However, with such advantages provided by BC-NOMA, the inter-carrier interference (ICI) and the intra-group interference (IGI) are severe, which degrade the reliability and the capacity. Therefore, the impacts of BC and power domain multiplexing on the system capacity are first investigated. To cancel the mixed internal interference, an iterative and successive interference cancellation (ISIC) approach is proposed. Secondly, the symmetrical coding (SC) is designed with BC-NOMA to avoid the error propagation when using ISIC, which benefits much for the low power user (LUE). Furthermore, the closed-form expression of error probability for SCNOMA is derived and the system and individual capacities are also analyzed. Results show that the BC-NOMA system can achieve a quasi-optimal performance compared with the orthogonal subcarrier NOMA (ONOMA) system and balance the fairness.