How non-terrestrial networks can play a role in 6G?

• ETSI recently held a conference focused on non-terrestrial networks (NTNs)
• There's a long way to go to get everyone on the planet connected, but some of the efforts aligned with the implementation of 6G will help fulfil that dream
• Much depends on harmonised technical standardisation for 6G
• Collaboration and cooperation are vital

The topic of non-terrestrial networks (NTNs) is hot right now and not just to meet current connectivity needs: Add to them a soupçon of the "global vision for 6G" and a focus on the challenges inherent in devising the all-encompassing, immensely technical, globally harmonised standardisation that will be necessary to deliver the promise of a completely connected planet and you have the subject matter of the timely and instructive ETSI (European Telecommunications Standards Institute) conference, Non-Terrestrial Networks, A Native Component of 6G, held recently in Sophia Antipolis in the South of France.

It is a matter of unassailable fact that the global 6G networks of the (not so distant future) will incorporate NTNs and harmonised technical standardisation, and that reality was mirrored by the fact that the European Space Agency (ESA), the 6G Smart Networks and Services Industry Association (6G-IA) and the Smart Networks and Services Joint Undertaking (SNS JU) co-organised and participated in the conference.

The main objective of the 6G Smart Networks and Services Industry Association (6G-IAR) is to research and contribute to the development of Europe's next-generation networks and services with particular emphasis on 5G evolution and the development of 6G. The European SNS JU was established in 2021 and is an EU partnership led by both the European Commission and the 6G Smart Networks and Services Industry Association (6G-IA). It forms alliances with EU member states on 6G research and innovation programmes and pursues international cooperation towards setting a 6G global standard.

NTNs are wireless communication platforms that operate above the surface of the Earth and are typically realised by the deployment of satellites in low, medium or geostationary orbit as well as drones, high altitude platforms (HAPS) and other aerial systems. Only NTNs can offer truly seamless global coverage to support a wide range of comms applications that require high availability and resilience and thus will be crucial to the 6G ecosystem.

It's not just about 6G though: NTNs have been a crucial component of 5G standards since the 3GPP Release 17 and pre-standardisation discussions relating to 6G technology, which will feature native integration of NTNs from the very outset, are already underway. NTNs offer truly seamless global coverage to support a wide range of comms applications that demand high availability and resilience, and native integration will facilitate the optimisation of both terrestrial and non-terrestrial networks in 6G.

Luis Jorge Romero, the director general of ETSI, commented: "NTN is already well recognised as a pivotal part of the 6G story, with its development supported by significant long-term investments by Europe's R&D communities." He added, "The successful realisation of NTN depends on effective collaboration between terrestrial and non-terrestrial communities, supported by dialogue between industry, standardisation groups, researchers and academia. The key enablers for NTN's success in 6G include a flexible regulatory and licensing environment that provides timely access to sufficient globally harmonised spectrum – all underpinned by robust technology standards that support smooth integration of cost-effective, reliable and interoperable NTN and TN solutions within the timeframe for 6G as envisaged by 3GPP."

Indeed, over the time of the development of the 3G, 4G and 5G wireless standards, 3GPP has, as a global organisation, long shown itself to be an efficient forum that can foster efficient collaboration between the different parts of the global ecosystem, including the chipset vendors, equipment vendors and network operators, and it is expected to play a major role in the development of 6G standards too.

The timeline for 6G standards and roll-out was sketched out in December 2023 when 3GPP committed to develop 6G specifications. Technology studies on system architecture and radio protocol/access are expected to be approved in September this year with initial technology studies to follow in June 2025, followed by other technology studies in June 2026. They will map a common technology framework (architecture and protocols) supporting, natively, both terrestrial and non-terrestrial networks with the intent of avoiding later calls for specific add-ons for the support of NTNs: It's an effort to cover all the bases before anyone comes up with something to add once the i's have been dotted and the t's all crossed.

Meanwhile, the International Telecommunications Union (ITU) will actively promote corresponding specifications as a candidate radio technology for IMT-2030 in the corresponding ITU working groups, and to support its approval at the WRC-27 gathering, where delegates will be tasked with identifying possible new frequency allocations for mobile satellite services.