Energy Efficient mmWave NOMA Downlink Multi-Relay System for ITSN

In this paper, we investigate an energy efficiency (EE) millimeter-wave (mmWave) band non-orthogonal multiple access (NOMA) downlink multi-relay system for integrated terrestrial-satellite networks (ITSN), where multiple terrestrial relay nodes decode and forward (DF) the NOMA signal from a high throughput satellite (HTS) to multiple destination nodes. We first define a common framework in which the HTS system and different terrestrial networks coexist in millimeter-wave (mmWave) band NOMA system. Then, the EE expressions of the system is obtained and the optimization problem of maximizing EE is proposed. To solve this non-convex problem, we address the user scheduling and power allocation problem and a new iterative algorithm to jointly optimize the user scheduling and power allocation. Eventually, simulation results are carried out to show the benefits of the proposed scheme and discuss the influence of the key system parameters on the EE mmWave NOMA downlink multi-relay system.