Direct-to-Device: How LEO Satellites Are Transforming Mobile Communications

Historically, mobile satellite services (MSS) depended on satellite phones or specialised user terminals. The emergence of low‑earth‑orbit (LEO) constellations has allowed new services that target end‑user devices more directly. Known as direct-to-device (D2D), direct-to-cell (D2C), or direct-to-handset (D2H) services, these services allow smartphones and similar devices to connect directly to satellites without specialised terminals.

LEO satellites function as long-term evolution (LTE/4G) or 5G mobile base stations or cellular towers, which would usually be on the ground but are now in orbit, transmitting signals and providing coverage directly to mobile devices on the ground.

Newer high-end handsets currently incorporate specialised antennas and chipsets that enable connectivity to existing satellite services using the spectrum bands allocated to Mobile Satellite Services, thanks to collaboration between handset manufacturers and MSS operators.

The upcoming World Radiocommunication Conference in November 2027 will address, among other key topics, the allocation of radio frequency spectrum bands for current International Mobile Telecommunications (IMT) systems, especially 4G and 5G, to MSS services.

Depending on its outcomes, the distinction between terrestrial and satellite spectrum use, and thus services, could diminish by 2030, enabling seamless switching between terrestrial and non-terrestrial (such as satellite) networks.

However, for the potential of mobile satellite services to be fully harnessed, technical challenges must be addressed. These include the distance and path-loss effects from LEO satellites in the sky and end-user devices on Earth’s surface, reducing bandwidth and reliability. Any additional obstacle could make communication impossible.