摘要
Background Although widely established and providing numerous valuable services,terrestrial networks,such as mobile networks,have geographic and deployment cost limitations due to the high reliance on fixed-ground infrastructure.Hence,spaceair-ground integrated networks(SAGINs)have been proposed to increase network intelligence,enhance network reliability,and offer ubiquitous wireless coverage via satellite networks including Geosynchronous Orbit(GSO),Geostationary Equatorial Orbit(GEO),Medium Earth Orbit(MEO)and Low Earth Orbit(LEO)satellites,aerial networks(e.g.,drone networks),and ground networks(e.g.,mobile networks).SAGINs are envisioned to support various promising IoT applications and multimedia services and satisfy the high demands of seamless communications and network Quality of Services(QoS).
