The large-scale deployment of 5G networks requires complementary technologies and services to offer ubiquitous and reliable coverage across all geographies. Terrestrial networks (TNs) are being used to deliver 5G services to regions already covered by past generations of cellular technology. However, non-terrestrial networks (NTNs) have gained renewed interest as a complement to TNs for expanding the reach of 5G connectivity.
In this context, satellite communications (satcom) can play a critical role in leveraging communication infrastructure to deliver 5G services in the future and bridge the digital divide. Generally, satellite-based architecture leverages geostationary earth orbit (GEO), medium-earth orbit, and low-earth orbit (LEO) systems which can provide coverage across altitudes ranging from 36,000 km to 400 km. According to the Department of Telecommunications, the newer generations of LEO satellite networks overcome the limitation of latency faced in GEO satellite networks. These satellites can also provide the higher bandwidth required for backhauling 5G mobile services. Hence, LEO satellites are expected to play a key role in extending 5G services to isolated, underserved and remote geographies where terrestrial coverage is unavailable.
Satcom in the 3GPP standards
Notably, the latest 5G specification from the 3rd Generation Partnership Project (3GPP) includes, for the first time, support for satellite-based networks. The work on NTNs started under 3GPP in 2017, after which the 3GPP system aspects workgroup started discussing the use cases for satellite-based NTNs. The study identified three main categories of use cases for satellite-based networks:
- Continuity: Use cases where 5G services cannot be offered by terrestrial networks alone, with a combination of TNs and NTNs providing service continuity for such cases. Some examples are airborne platforms such as commercial or private jets, and maritime platforms such as maritime vessels.
- Ubiquity: Use cases that address unserved or underserved geographical areas, where terrestrial networks may be absent. Examples of these are internet of things (IoT) in agriculture, asset tracking, metering, public safety and emergency networks, and home access.
- Scalability: Use cases that leverage the large coverage area of satellites to multicast or broadcast similar content over a large area. An example of this is the distribution of rich TV content, that is, ultra-high-definition TV.
Use cases in the 5G ecosystem
The key areas where satcom plays an important role in the 5G ecosystem are:
Satellite backhauling of 5G cell sites
Terrestrial backhaul solutions for connecting cell sites across wide geographic regions come with high costs and low returns on investment, along with time delays. In contrast, cellular backhaul over satellite enables mobile network operators to provide consistent services to customers. It expands their coverage to larger areas which were previously considered economically unviable.
IoT over satellites
Billions of monitoring systems using IoT will be connected to 5G. In many instances, these devices will be connected via satellites through bandwidth- and power-efficient terminals, with an optimised air interface.
Content multicast
Satcom plays a major role in content caching near the edge, bringing content closer to the user. The natural capability of satellites to multicast data over a wide area can be integrated into the content delivery network. With efficient satellite multicast delivery, this will help enhance the users’ quality of experience, reduce backhaul traffic load, and provide immediate and on-demand content access.
Resilience
Satcom supports resilient 5G networks to mitigate the problems of overload or congestion. During instances of terrestrial congestion and network stress, or if the user is out of range of the terrestrial radio link, the traffic would seamlessly flow over the satellite link until the terrestrial connections are restored. Thus, satellite capacity can be shared over a number of sites at a low cost per site, providing high availability for the end user.
Recent developments
Satellite and Terrestrial Network for 5G (SaT5G), a project funded by the European Union (EU), is a key example of an ecosystem supporting the development of a standardised and integrated 5G and satcom network architecture. SaT5G supports the development of 5G technologies by leveraging satellite capabilities such as virtualised network functions delivery. Luxembourg-based SES S.A., a participant in SaT5G, announced in September 2022 that it was committed to building a European LEO satellite constellation, funded by the European Space Agency (ESA), as well as establishing an ecosystem to create Europe’s first space-based quantum key distribution satellite system, EAGLE-1. This project is due for launch in 2024 and aims to create a highly secure, satellite-based connectivity system for the EU.
In addition, the ESA has established a framework to support future industrial activities and is collaborating with the European Commission to coordinate and strengthen institutional support in Europe for satcom and 5G convergence. Further, in June 2022, the ESA signed an agreement with the European Broadcast Union and 20 companies from various countries, to make Europe a leader in media content delivery. Under the agreement, called 5G Emerge, the partners will define, develop and validate an integrated satellite and terrestrial system, which will leverage the structural advantages of satellite-based infrastructure combined with the flexibility of 5G technologies (and beyond) to reach anyone, anywhere.
Meanwhile, in June 2022, engineers at the ESA and the National Institute of Information and Communication Technologies (NICT) connected Japan and Europe through space-enabled 5G links. It was the first time that such an intercontinental connection was established between Europe and Japan. The trials aimed to assess the ability of 5G to provide high speed, high-volume data connectivity in order to fuel digital transformation across sectors. The tests, which took place between January 2022 and February 2022, were part of an agreement between the ESA and NICT to collaborate on 5G satcom.
In India, the government unveiled new policy reforms for satcom services in October 2022. They are aimed at easing procedures and streamlining clearance processes to expedite the roll-out of satcom services across the country, especially in remote areas. The procedural reforms include giving permission to mount very small aperture terminals on any mobile vehicle, allowing self-certification of satellite antennas instead of the mandatory performance verification testing, streamlining the network operation and control centre process with a simplified procedure that would reduce timelines from the current eight months to six weeks, and enhancing the scope of various licences to enable satellite-based machine-to-machine and IoT devices.
As for the private sector, Lockheed Martin’s space division announced a strategic partnership with Omnispace in 2021 to jointly build a space-based 5G network. The hybrid network aims to combine satellite and mobile wireless carrier networks to create a global 5G network that allows users to seamlessly transition between satellite and terrestrial networks. This would be the first integrated 5G platform for commercial and government use, incorporating space-based and terrestrial network architectures. Meanwhile, in January 2022, Intelsat S.A. and Thales Alenia Space signed an agreement to build two software-defined satellites to advance the former’s global fabric of software-defined GEO connectivity as part of its 5G software-defined network. The satellites are scheduled to begin service in 2025. Further, in August 2022, Omnispace and Smart (PLDT) partnered to explore interoperability between Smart’s 5G network and Omnispace’s LEO satellites, using 3GPP-compliant 5G NTN standards. The collaboration creates opportunities to deliver 5G connectivity in rural areas and use IoT devices to expand network coverage for disaster relief in the Philippines. Also, Telefónica Spain partnered with Sateliot in July 2022 to integrate 5G LEO satellite connectivity with Telefónica Tech’s 3GPP standardised narrowband-IoT network, called Kite. This will offer extended IoT connectivity for Telefónica’s customers in remote areas, and benefit enterprise use cases.
In sum
Satcom can complement 5G and boost its value by addressing coverage challenges and complex use cases that cannot be delivered using terrestrial infrastructure alone. 5G will offer new enterprise use cases and business models, while NTNs will provide additional coverage capabilities to implement and extend these use cases to new areas. The integration of 5G and satcom will help realise the high transmission speeds, lower latency and wider connectivity promised by 5G networks. It will also enable the implementation of virtual networks (network slicing) and provide more adjusted connectivity as per user requirements. Importantly, this integration is both technically possible and economically feasible due to the evolution of the underpinning technology of satellites, as well as the business models of satellite companies, such as satellites-as-a-service.
With the rapid and widespread deployment of 5G networks globally, satcom integration advancements continue to keep pace. Several new NTNs are being proposed and launched, which can be integrated with 5G. Each of these initiatives recognises the potential of private satellite constellations to not only provide internet connectivity to remote areas, but also fulfil future networking service needs.
