An Overview of Pre-5G Satellite Systems
Introduction Pre-5G Satellite Systems
5G-based Non-Terrestrial Networks (NTNs) are expected to become increasingly common in the coming years. At the same time, both 5G-based NTNs and non-5G-based NTNs are expected to coexist.
Several satellite communication systems that were developed before the introduction of 5G-based NTN specifications are already operational. Some of these existing systems may eventually transition from their currently used, generally non-5G technologies toward 5G-based systems because of the flexibility, efficiency, and diversity of the 5G ecosystem.
This section provides an overview of some important pre-5G satellite constellations. These can broadly be classified into two categories:
Established satellite constellations
Emerging satellite constellations
Established constellations have been operating for several decades, whereas emerging constellations have primarily been developed and deployed during the 2020s.
The examples discussed here are intended to represent selected satellite constellations alphabetically. They do not represent every existing or planned satellite constellation.
An important trend can be observed in the evolution of satellite systems:
Many established constellations initially focused heavily on GEO satellites.
Many emerging constellations are increasingly focusing on LEO satellites.
1. Established Satellite Constellations
Several established satellite communication systems have been operating for decades. Important examples include:
EchoStar
Globalstar
Intelsat
ViaSat/Inmarsat
These systems have supported applications ranging from broadband Internet and enterprise connectivity to voice communication, maritime connectivity, aviation, emergency communications, and government services.
2. EchoStar
EchoStar provides satellite communication services through its Hughes Network Systems and EchoStar Satellite Services business segments.
The merger between EchoStar and DISH Network was completed in January 2024.
One of the major satellite Internet services provided through Hughes is HughesNet.
Examples of Hughes satellites include GEO satellites such as:
Jupiter 1
Jupiter 2
Jupiter 3
These satellite systems support a variety of applications, including:
Consumer broadband
Enterprise networking
Cellular backhaul
Emergency communications
Aeronautical mobility
Maritime mobility
EchoStar Satellite Services also provides satellite communication infrastructure and solutions to:
Media organizations
Broadcast organizations
Enterprise customers
U.S. government organizations
Military service providers
As of early 2024, the EchoStar fleet included approximately 10 GEO satellites covering satellite service categories such as:
Ku-band Fixed Satellite Service (FSS)
Ka-band FSS
S-band Mobile Satellite Service (MSS)
EchoStar therefore represents an example of an established satellite operator with significant experience in GEO-based connectivity and multiple application areas.
3. Globalstar
Globalstar provides three major categories of satellite communication services:
IoT services
Messaging services
Voice and data services
IoT Services
Globalstar's IoT services can be used for applications such as:
Asset tracking
Asset monitoring
These applications allow connected devices to communicate over satellite networks in locations where terrestrial connectivity may not be available.
Messaging Services
Globalstar also provides satellite messaging services that can support emergency applications.
One example is the use of SOS alerts for emergency communication.
Voice and Data Services
Portable satellite phones can connect to Globalstar satellites to provide voice and data services.
Globalstar satellites provide coverage over more than 80% of the Earth's surface.
The Globalstar system uses Code Division Multiple Access (CDMA) technology.
The network also uses 24 ground stations connecting the LEO satellite system with terrestrial communications infrastructure across six continents.
The IP Multimedia Subsystem (IMS) is used as the services network to enable low-cost local access for voice calls.
Globalstar therefore demonstrates how an established LEO satellite system can support voice, data, messaging, and IoT applications.
4. Intelsat
Intelsat provides satellite communication services using GEO and LEO satellites and has also considered the deployment of MEO satellites.
Its satellite systems utilize multiple frequency bands, including:
C-band
Ku-band
Ka-band
Intelsat uses both:
Wide beams
Spot beams
This allows satellite capacity to be configured for different coverage and service requirements.
Intelsat is also a major provider of satellite communications services to the U.S. government.
In addition to government applications, Intelsat provides broadband connectivity for maritime passengers and crew.
The company also provides in-flight connectivity (IFC) to more than 20 commercial airline partners and nearly 3,000 aircraft, according to the source material.
These applications demonstrate the broad range of services supported by established satellite communication systems.
5. ViaSat
ViaSat provides satellite connectivity services to a wide range of customers.
Its applications include:
Consumer Services
ViaSat provides services such as home Internet access.
Business Services
Business applications include in-flight connectivity for aircraft.
Government Services
ViaSat also supports government and military applications.
The company provides coverage to approximately 99% of the U.S. population, including Internet access in hard-to-reach areas.
ViaSat also provides connectivity to unserved and underserved communities around the world.
Its satellite network utilizes high-capacity GEO satellites together with an associated ground network to provide broadband services.
6. Emerging Satellite Constellations
The satellite industry has experienced significant development during the 2020s, particularly in the area of LEO satellite constellations.
Examples of emerging satellite constellations include:
Project Kuiper
Telesat Lightspeed
Eutelsat OneWeb
Starlink
These systems represent a major evolution in satellite networking, with a strong focus on large LEO constellations, higher capacity, lower latency, and global connectivity.
7. Project Kuiper
Project Kuiper, developed by Amazon, aims to provide satellite broadband Internet access to unserved and underserved communities in the United States and around the world.
The service is designed to support applications such as:
Internet access
Video calls
Gaming
High-definition streaming
Amazon received a license from the Federal Communications Commission (FCC) in July 2020 to deploy and operate the Project Kuiper satellite system.
The first two prototype satellites were launched on October 6, 2023.
The Project Kuiper system has been designed around a large LEO satellite constellation.
Its initial constellation design consists of approximately 3,236 LEO satellites.
Project Kuiper also follows an integrated development approach, with in-house design and development of:
Satellites
Ground infrastructure
Customer terminals
This integrated approach is intended to provide an end-to-end satellite broadband ecosystem.
8. Telesat Lightspeed
Telesat Lightspeed is a LEO satellite network designed to provide global connectivity.
Telesat has developed a global network consisting of approximately 198 LEO satellites, according to the source material.
One of the important technologies used in the system is optical inter-satellite links (ISLs).
These links allow satellites to communicate with one another and create a global mesh network.
The system utilizes multiple orbital configurations to provide coverage across different regions, including polar regions.
Another important characteristic is that digital functions such as:
Modulation
Demodulation
Routing
can be carried out in space.
This approach enables higher capacity and greater flexibility in the satellite network.
9. Hopping Beams and Dynamic Capacity
Telesat Lightspeed uses phased antenna arrays to create hopping beams.
These beams can dynamically focus capacity where it is needed.
This provides flexibility in allocating satellite capacity according to changing traffic requirements.
Telesat also collaborates with terminal manufacturers whose equipment can connect to the Telesat Lightspeed satellite network.
For integration with ground infrastructure, the system supports Metro Ethernet Forum (MEF)-compliant interfaces.
Telesat's first LEO satellite was launched in January 2018.
The company also supports live demonstrations for different markets and applications.
10. Eutelsat OneWeb
In September 2023, Eutelsat combined its GEO satellite business with OneWeb's LEO satellite business, creating Eutelsat OneWeb.
The Eutelsat OneWeb LEO constellation is designed to contain more than 630 LEO satellites arranged across 12 orbital planes.
The satellites operate at an altitude of approximately 1,200 km.
Each LEO satellite connects with:
User terminals
Ground infrastructure
The ground-based OneWeb antenna system can view multiple moving satellites at a given time.
This capability is particularly useful in remote areas where continuous connectivity is required.
The constellation architecture allows the system to provide connectivity while the satellites continuously move through their orbital paths.
11. Starlink
Starlink, operated by SpaceX, represents one of the most significant examples of a large-scale LEO satellite constellation.
According to the source material, more than 5,000 Starlink satellites were operating as of August 2024, with plans discussed for approximately 12,000 satellites and potentially as many as 42,000 satellites.
One well-known example of Starlink's use was providing satellite connectivity in Ukraine during the Russia-Ukraine war in the early 2020s.
Starlink applications include:
Residential broadband
Connectivity on the go
Connectivity in unserved and underserved areas
Maritime communications
Communications on boats
12. Starlink Satellite Technologies
Starlink satellites incorporate several technologies intended to simplify satellite design, increase capacity, and support autonomous operation.
Single Solar Array
A single solar array is used on the satellite.
This approach simplifies system design and facilitates manufacturing.
Compact Flat-Panel Design
Starlink satellites use a compact and flat-panel design.
This makes it easier to accommodate large numbers of satellites during launch missions.
Autonomous Collision Avoidance
Starlink satellites implement autonomous collision avoidance.
This capability helps satellites avoid collisions with:
Other satellites
Space debris
Autonomous operation is particularly important for large LEO constellations where thousands of satellites may operate simultaneously.
13. Navigation and Beam Management
Starlink satellites use custom-built navigation sensors to determine parameters such as:
Satellite location
Altitude
Orientation
This information enables the system to focus beams toward areas where additional throughput is required.
This dynamic beam-management capability allows satellite resources to be directed according to network demand.
14. Optical Inter-Satellite Links
Starlink satellites also use optical inter-satellite links (ISLs).
These links allow satellites to communicate directly with one another in space and help establish a network capable of supporting global coverage.
Optical ISLs are an important component of modern LEO satellite architectures because they can reduce dependence on continuously routing every communication through terrestrial gateway infrastructure.
15. Starlink Antenna Configuration
Each Starlink satellite includes:
Four phased-array antennas
Two parabolic antennas
The phased-array antennas support flexible beam management, while the satellite's overall antenna architecture supports communication with users and network infrastructure.
The combination of phased-array technology and satellite networking capabilities enables Starlink to dynamically manage coverage and capacity.
16. Propulsion and End-of-Life Deorbiting
Starlink satellites use krypton-powered thrusters.
These thrusters are used for:
Orbital maneuvering
End-of-life deorbiting
Orbital maneuvering is important for maintaining the desired satellite orbit and avoiding potential collisions.
At the end of the satellite's operational life, propulsion capability can also be used to support controlled deorbiting.
17. Established vs Emerging Satellite Systems
The evolution from established satellite systems to emerging LEO constellations illustrates how satellite communications have changed over time.
Characteristic | Established Systems | Emerging Systems |
Major Orbital Focus | Historically strong GEO focus | Strong focus on LEO |
Examples | EchoStar, Globalstar, Intelsat, ViaSat | Kuiper, Lightspeed, OneWeb, Starlink |
Typical Applications | Broadband, voice, enterprise, government, aviation, maritime | Broadband, low-latency connectivity, global coverage, enterprise and mobility |
Network Architecture | Satellite + ground infrastructure | Large satellite constellations + advanced ground infrastructure |
Beam Technologies | Wide beams and spot beams | Phased arrays, spot/hopping beams |
Inter-Satellite Connectivity | More limited in traditional systems | Optical ISLs increasingly important |
Capacity Management | Relatively traditional | Dynamic and software-driven approaches |
Satellite Deployment | Traditionally fewer satellites | Large LEO constellations |
18. Evolution Toward 5G-Based NTN
The coexistence of pre-5G satellite systems and 5G-based NTNs is an important part of the evolution of satellite communications.
Existing satellite systems already provide services to consumers, enterprises, governments, aircraft, maritime users, and remote communities.
As 5G NTN technologies continue to develop, some existing satellite systems may transition toward 5G-based architectures and technologies.
The flexibility of the 5G ecosystem can provide opportunities for:
Better integration with terrestrial networks
More flexible network architectures
Improved interoperability
Diverse network applications
Integration with modern mobile-network technologies
This evolution does not necessarily mean that existing satellite technologies will immediately disappear. Instead, 5G-based and non-5G-based satellite systems are expected to coexist, particularly during the transition toward more integrated terrestrial and non-terrestrial networks.
Conclusion
Pre-5G satellite systems have already established a significant role in global communications. Established operators such as EchoStar, Globalstar, Intelsat, and ViaSat have demonstrated the ability of satellite networks to support broadband, enterprise connectivity, voice and data services, IoT, emergency communication, aviation, maritime connectivity, and government applications.
At the same time, emerging LEO constellations such as Project Kuiper, Telesat Lightspeed, Eutelsat OneWeb, and Starlink are introducing large-scale satellite architectures with advanced technologies such as phased-array antennas, optical inter-satellite links, dynamic beam management, autonomous collision avoidance, and space-based routing.
A major trend is the shift from the historical emphasis on GEO satellite systems toward large-scale LEO constellations. LEO systems can provide lower latency and support high-capacity connectivity, although they require substantially more satellites and sophisticated network-management mechanisms.
The future satellite ecosystem is therefore expected to include a combination of established pre-5G systems, emerging satellite constellations, and 5G-based NTN systems.
Understanding these existing satellite architectures is important for telecom professionals because it provides the foundation for understanding how 5G NTN and future 6G integrated terrestrial–non-terrestrial networks are evolving.
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