A Technical Comparison of Six Satellite Systems: Suitability for Direct-to-Device Satellite Access

This paper analyses the suitability of several satellite systems for direct-to-device connectivity using the 5G New Radio air interface. The selected geostationary satellites and low Earth orbit satellite constellations cover a wide range of systems, namely Inmarsat, EchoStar, GLOBALSTAR-2, Iridium NEXT, Lynk, and AST SpaceMobile. The conducted link power budget assessment shows that depending on the targeted application, several systems are able to achieve adequate performance, especially in the downlink direction, from satellite to terminal. The analysed use cases cover both narrowband use cases such as voice and Internet-of-Things as well as broadband connections. However, direct 5G satellite services are not yet a commercial reality and therefore required technological and regulatory advancements for future developments are discussed.