QoS-Aware Uplink NOMA with Multi-Type Service Coexistence for LEO Satellite Constellation

With the advancement of low earth orbit (LEO) satellite constellation, the LEO satellite-based Internet of Things (S-IoT) has attracted extensive attentions due to its wide coverage and broadband access capability. Considering the mission critical communications (MCC) and massive machine-type communications (mMTC) requirements of terrestrial user equipments (UEs), we first propose a quality of service (QoS)-aware uplink non-orthogonal multiple access (NOMA) transmission scheme for LEO high-throughput satellite (HTS) constellation, where MCC and mMTC services can coexist. Then, we derive the closed-form expressions of ergodic capacity (EC) and outage probability (OP), and obtain the expression of system throughput (ST) for NOMA and OMA schemes. Further, we propose a reduced system outage probability (RSOP) algorithm to minimize the OP of MCC services, and an improved system throughput (IST) algorithm to enhance the ST of mMTC services, while guaranteeing the OP requirements for each UE. Finally, simulation results validate the accuracy of our theoretical derivations and show that both RSOP-NOMA scheme and IST-NOMA scheme can outperform the state-of-art ones.