Major Takeaways from Non-Terrestrial Networks (NTNs)
Introduction Non-Terrestrial Networks (NTNs)
Non-Terrestrial Networks (NTNs) are expected to play an important role as a key component of 5G, 5G-Advanced, and future 6G networks.
The primary objective of NTN is to extend the reach of wireless communications beyond the geographical limitations of traditional Terrestrial Networks (TNs).
Even after five generations of cellular technology, a significant portion of the Earth's surface and a large number of people still remain without reliable wireless connectivity.
NTN provides an important approach for addressing this connectivity gap.
The following are the major takeaways from the chapter.Non-Terrestrial Networks (NTNs)
1. Why NTN Is Needed
Despite the deployment of five generations of cellular technologies, wireless connectivity is still not universally available.
Large areas of the planet remain:
Unserved
Underserved
Difficult to reach
Economically challenging for terrestrial network deployment
These areas can include:
Remote rural regions
Mountains
Deserts
Oceans
Remote islands
Offshore locations
NTN can help extend wireless communication services to such areas without requiring the same level of terrestrial infrastructure.
2. What Is a Non-Terrestrial Network?
An NTN is a wireless communication network that utilizes radio network equipment placed on an airborne or spaceborne vehicle.
From the broader perspective, non-terrestrial communication can involve different types of airborne or spaceborne platforms.
However, the formal 3GPP NTN specifications focus on specific types of platforms and technologies.
The 3GPP formally defines NTN as:
“an NG-RAN consisting of gNBs, which provide non-terrestrial NR access to UEs by means of an NTN payload embarked on an airborne or spaceborne NTN vehicle and an NTN Gateway.”
In simple terms, NTN allows a UE to access a cellular network through radio equipment associated with a non-terrestrial platform.
3. NTN Platforms
The 3GPP considers several types of platforms as part of its NTN activities.
These include:
High-Altitude Platform Stations (HAPS)
A HAPS is an airborne vehicle operating at an altitude between approximately:
8 km and 50 km
above the Earth's surface.
Satellites
Important satellite categories include:
LEO — Low Earth Orbit
MEO — Medium Earth Orbit
GEO — Geosynchronous/Geostationary Earth Orbit
These platforms can provide different coverage, propagation, mobility, and latency characteristics.
4. Drones and UAS Are Not Formally Part of 3GPP NTN
A broader definition of NTN may include drones or Uncrewed Aerial Systems (UASs).
However, there is an important distinction.
Under the formal 3GPP NTN activities described in this context, HAPS and satellite platforms are considered, while drones or UASs operating below approximately 8 km altitude are not formally part of the 3GPP NTN scope.
Therefore, it is important to distinguish between:
General NTN concept
and
3GPP-defined NTN activities and specifications.
5. Key Components of an NTN Architecture
A simplified NTN architecture includes several important elements.
NTN-Capable UE
The User Equipment (UE) communicates with the NTN system through an appropriate radio interface.
Examples can include:
Smartphones
IoT devices
VSAT devices
Other NTN-capable terminals
NTN Payload
The NTN payload is located on an NTN platform such as a satellite or HAPS.
It provides the radio connectivity between the UE and the terrestrial network infrastructure.
NTN Gateway
The NTN Gateway (NTN-GW) provides connectivity between the NTN payload and the terrestrial network.
gNB/eNB
The network-side processing associated with the gNB/eNB connects the NTN system to the appropriate core network.
5GC/EPC
Depending on the technology, the core network can be:
5G Core (5GC) for NR-based NTN
Evolved Packet Core (EPC) for IoT-NTN based on technologies such as NB-IoT and eMTC/LTE-M
The overall architecture can therefore be represented conceptually as:
UE → NTN Payload → NTN-GW → gNB/eNB → 5GC/EPC → Data Network
6. Three Major Motivations for NTN
The fundamental motivation for NTN can be understood through three major use-case categories:
Service Ubiquity
Service Continuity
Service Scalability
These three concepts explain why NTN is important for modern and future wireless networks.
7. Service Ubiquity
Service ubiquity refers to providing wireless coverage in geographical areas that are unserved or underserved by traditional terrestrial networks.
NTN can provide coverage across large areas without requiring terrestrial radio equipment to be deployed throughout the geographic region being served.
This is particularly useful for:
Remote communities
Rural areas
Mountains
Deserts
Oceans
Remote islands
Offshore facilities
The key idea is:
Where terrestrial infrastructure cannot economically reach, NTN can provide an alternative coverage layer.
8. Service Continuity
Service continuity refers to maintaining wireless connectivity as a user or device moves between terrestrial and non-terrestrial coverage.
For example, a user may move from:
TN Coverage → NTN Coverage
or a device may travel through an area where terrestrial coverage disappears.
Examples include:
Vehicles
Trains
Aircraft
Ships
Remote mobile platforms
NTN can help maintain communication services in areas where terrestrial connectivity is unavailable.
Therefore, service continuity is particularly important for mobile users and devices.
9. Service Scalability
Service scalability refers to efficiently serving a large number of users across a large geographical area.
An NTN cell can cover a much larger area than a typical terrestrial cell.
This makes NTN particularly attractive for services where the same information needs to be delivered to many users.
Examples include:
Broadcast services
Multicast services
Software updates
Entertainment content
Live events
Other large-area content distribution
Instead of requiring many terrestrial base stations to transmit the same content separately, an NTN system can potentially distribute content efficiently across a large geographical region.
10. Important NTN Use Cases
The 3GPP has studied numerous NTN use cases.
Important examples include:
TN–NTN Mobility
Supporting users and devices moving between terrestrial and satellite coverage.
Satellite-Based Backhaul
Using satellite connectivity to provide backhaul for terrestrial base stations deployed in remote areas where suitable transport infrastructure is unavailable.
IoT Connectivity
Providing connectivity to IoT devices deployed in remote regions.
Remote Factories
Connecting factories and industrial facilities located in areas without adequate terrestrial coverage.
Offshore Wind Farms
Connecting offshore wind farms to remote or inland service centers.
These examples demonstrate the broad applicability of NTN across consumer, enterprise, industrial, IoT, and infrastructure applications.
11. NTN Standardization Journey
The development of NTN within 3GPP has taken place over multiple releases.
The work began before NTN became a formal 3GPP feature.
Release 15
3GPP began NTN-related work in Release 15.
The focus included:
NTN deployment scenarios
NTN-specific channel models
These studies helped address the unique propagation characteristics of non-terrestrial communication.
Release 16
Release 16 focused on:
NTN use cases
Satellite access in 5G
Service ubiquity
Service continuity
Service scalability
Potential solutions for NR support of NTN
These studies created the foundation for the normative NTN work in Release 17.
12. Release 17 — NTN Becomes a Formal Feature
Release 17 represents a major milestone in NTN development.
Both:
NR-NTN
IoT-NTN
were specified as formal 3GPP features.
NR-NTN introduced mechanisms to support 5G NR over non-terrestrial networks.
IoT-NTN extended technologies such as NB-IoT and eMTC/LTE-M to NTN environments.
13. Release 18 — 5G-Advanced NTN Enhancements
The NTN evolution continued in Release 18, as part of the development of 5G-Advanced.
Important NR-NTN enhancement areas include:
Coverage enhancement
TN–NTN mobility
Service continuity
Support for frequencies above 10 GHz
IoT-NTN enhancements include areas such as:
Discontinuous coverage
Mobility improvements
Neighbor-cell measurements
Performance improvements
GNSS enhancements
H-ARQ-related improvements
These enhancements expand the practical applicability of NTN.
14. Release 19 and Beyond
The NTN roadmap continues with Release 19 and future releases.
Additional NTN enhancements include support for:
Improved downlink coverage
Increased uplink capacity
Multimedia Broadcast Service (MBS)
Selected 5G Network Functions on the NTN platform
Regenerative payloads
RedCap UEs
For IoT-NTN, further development includes:
Store-and-forward capabilities
Uplink capacity enhancements
This represents the continued evolution of NTN from the foundational capabilities introduced in Release 17.
15. NTN and 6G
Although the current 3GPP NTN specifications are part of 5G and 5G-Advanced, NTN is expected to play a vital role in 6G.
Future 6G networks are expected to provide:
Global coverage
Greater resilience
Cost-effective connectivity
Intelligent networking
Integration of terrestrial and non-terrestrial systems
NTN can provide an alternative coverage and communication mode when terrestrial networks are unavailable.
This can be especially valuable during:
Natural disasters
Infrastructure failures
Remote-area deployments
Emergency situations
Maritime operations
Aviation
Other challenging environments
Therefore, NTN can become an important component of the broader 6G connectivity ecosystem.
16. The Bigger Picture
The evolution of NTN can be summarized as:
R15 → Study and Channel Models
↓
R16 → Use Cases and NR Support Studies
↓
R17 → Formal NR-NTN and IoT-NTN Specifications
↓
R18 → 5G-Advanced NTN Enhancements
↓
R19 → Further Coverage, Capacity, Regenerative Payload and IoT Enhancements
↓
Future → Increasing Integration with 6G
This progression demonstrates that NTN is not a temporary feature.
It is becoming an increasingly important part of the evolution of cellular communication.
Final Takeaway
The most important message from this chapter is simple:
NTN extends the reach of wireless communication beyond the limitations of terrestrial networks.
It can provide:
Ubiquity — connectivity where terrestrial networks are unavailable.
Continuity — connectivity as users and devices move between TN and NTN coverage.
Scalability — efficient communication across very large geographical areas.
At the same time, the 3GPP roadmap shows a clear evolution from early NTN studies in Release 15 to formal standardization in Release 17, followed by continued enhancements in Release 18, Release 19, and beyond.
While NTN is already an important part of 5G and 5G-Advanced, its importance is expected to increase further as the industry moves toward 6G and globally integrated communication networks.
Understanding NTN therefore requires more than understanding satellites. It requires understanding how UEs, NTN payloads, gateways, gNBs/eNBs, core networks, radio protocols, mobility, timing, synchronization, IoT, and terrestrial networks work together as one communication ecosystem.
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