Satellite Networks: Past, Present, and Future Challenges—Part 1: Mobile Systems

The Non Terrestrial Networks (NTNs) field, mainly encompassing satellite telecommunications, is experiencing a resurgence driven by Low Earth Orbit (LEO) megaconstellations complementing Terrestrial Networks (TN) and the emergence of direct-to-device (D2D) satellite connectivity for mobile phones and IoT devices. This contrasts with early 21st-century LEO bankruptcies and the declining market for GEO-based broadcasting due to over-the-top streaming growing success. Reduced launch costs, mass production of satellites and user equipment, and private investment have revitalized the sector. This proliferation of NTN presents new technical and regulatory challenges regarding service quality and cost. This paper, dedicated to mobile systems, is the first of two contributions. These contributions review key features of recent satcom systems and associated technologies, outline future challenges for various network classes, including Non Geo-Synchronous Orbit (NGSO) and Geosynchronous Earth Orbit (GSO) mobile and high-throughput constellations, and discuss the key technical challenges faced by different NTN types.