Non-terrestrial networks (NTN), explained
A non-terrestrial network delivers connectivity from above — satellites in low, medium or geostationary orbit, or high-altitude platforms — and, since 3GPP Release 17, can plug into the same 5G and LTE standards that ground networks use.
How satellites connect to the mobile network
There is more than one way to build an NTN. The architecture decides where the radio network lives — on the ground or on the satellite — and whether an ordinary device can talk to the satellite directly.
NTN Relay / Enablement Model
A device reaches a satellite service layer that bridges into existing terrestrial service platforms.
- In engineering terms
- NTN enablement abstracts satellite specifics and exposes onboarding/session control toward terrestrial network functions.
- Where the RAN sits
- Mostly terrestrial or partner-managed; satellite is access relay/service layer.
True Direct-to-Device NTN RAN in Space
The phone talks straight to the satellite, which behaves like a cell site in space.
- In engineering terms
- Satellite payload hosts or emulates RAN functions; UE signaling anchors through NTN-compatible 5G architecture.
- Where the RAN sits
- RAN intelligence in satellite payload and tightly integrated ground segment.
Community LTE + Satellite Backhaul
Phone connects to a local tower first. Satellite only carries tower traffic upstream.
- In engineering terms
- eNB/gNB remains terrestrial; SATCOM link replaces fiber/microwave on transport/backhaul segment.
- Where the RAN sits
- At terrestrial eNB/gNB tower site.
Aviation Air-to-Ground Access Model
Aircraft terminal connects to terrestrial ATG towers; access does not traverse satellite.
- In engineering terms
- Mobility session is anchored through ATG radio coverage and terrestrial transport/core interconnect, with no orbital access leg.
- Where the RAN sits
- ATG terrestrial base station network and ground core domain.
Broadcast / DTH One-to-Many Distribution
One uplink sends content to large regions where many receivers consume the same stream.
- In engineering terms
- Hub uplink feeds high-power transponders/spot beams and downlink receivers with conditional access and regional rights controls.
- Where the RAN sits
- Not cellular RAN-centric; distribution payload is broadcast optimized.
Hybrid Multi-Orbit + Terrestrial Model
Traffic is steered across GEO/LEO and terrestrial links based on app needs and link quality.
- In engineering terms
- Policy engines and SD-WAN orchestration perform path selection, bonding, and failover across heterogeneous transport domains.
- Where the RAN sits
- Depends on service edge; transport abstraction is the key intelligence layer.
The building blocks
Free training course
7 modules, from foundations to 3GPP standards and the cutting edge:
- Module 1: Satellite Networking Foundations — Core building blocks: what a satellite network is, orbit mechanics, and spectrum planning.
- Module 2: How Satellite Services Work — Access models, packet paths, ground infrastructure, and real-world service categories.
- Module 3: Why NTN Now? — The convergence of standards, chipsets, regulation, and coverage gaps driving NTN adoption.
- Module 4: D2D / Direct-to-Cell Explained — How direct-to-device NTN works, key players, architectures, and current performance reality.
- Module 5: Regulatory and Standards Primer — ITU, WRC, 3GPP releases, national regulators, and spectrum sharing challenges.
- Module 6: The Cutting Edge — Optical links, space data centers, launch economics, AI in orbit, and the mega-constellation race.
- Module 7: Anatomy of a Satellite — A guided teardown: the bus, the payload, power and propulsion, antennas and lasers — and what happens from factory floor to fiery deorbit.