NTN

Non-Terrestrial Network. A communication network that includes satellites, high-altitude platforms, UAVs, or other non-ground nodes.

TN

Terrestrial Network. A traditional ground-based mobile or fixed communication network.

LEO

Low Earth Orbit. A satellite orbit relatively close to Earth, often used for lower-latency satellite communication.

D2D

Direct-to-Device. A communication model where a satellite or NTN platform connects directly to user devices.