New Space Co-Creation Manager and Associate Professor
VTT Technical Research Centre of Finland Ltd, Finland
Satellite communications and terrestrial mobile communications systems have been traditionally designed and operated as distinctively separate systems. During third generation of cellular technology (3G) first steps toward convergence of satellite and terrestrial systems were done and the satellite air interface was made compatible with the terrestrial universal mobile telecommunication system (UMTS) infrastructure. In 4G, satellite systems have been used to enable global roaming in places where terrestrial 4G network is impossible to be installed or too expensive. During the 5G the progress is continuing and there are real promises of having wide-scale use of integrated systems in the future.
What will integration of networks mean for the end users and operators? First of all, a joint radio interface for terrestrial and satellite link would mean that we could use the same handheld to connect via satellite in any location, also outside terrestrial coverage. There are still plenty of locations where building the terrestrial infrastructure is not economically feasible – or not possible at all such as in marine environment. The ability to use same equipment without the need to buy specific satellite terminals would reduce barriers in adopting the technology and provide resiliency and higher feeling of safety also to consumers e.g. during hiking trips in remote locations. Secondly, it is possible to create private networks for public safety use, harbor areas etc. and use satellites as backhaul connections to connect those private networks to outside world.
Now the research community is already looking actively towards 6G networks. The aim is to enable new applications, increase capacity, reduce latency and provide even higher mobility compared to previous generations. One of the planned aspects is that the vertical dimension and the integration of terrestrial, aerial, and satellite networks is taken into account in the network design and operations from the beginning, leading to the three-dimensional (3D) architecture (Dang 2020, Höyhtyä et al., 2022). Therefore, 6G systems can be tailored to support both connectivity and positioning needs of future users and applications accurately and efficiently.
In addition to technical advantages, the 6G systems are designed with sustainable development goals in mind. The multi-layer systems are developed from economic, social and environmental viewpoints. There are currently large satellite constellations under development aiming to provide services to developing countries, enabling remote healthcare, and supporting e-learning e.g. in Congo. From the environmental viewpoint satellites can help to preserve Arctic areas since no terrestrial infrastructure need to be built in the fragile environment. In addition, increasing number of satellites in the orbit should not increase the space debris in a way that endangers satellite services to future generations.
From the frequency point of view, there are many challenges ahead regarding the spectrum management for 6G systems in order to be able to support needs and ensure interference-free operation to existing systems. Dynamic spectrum management needs to be updated to the 6G era. There are many topics to be addressed to make this successfully. First, defining the most suitable frequency bands for systems and links. Second, developing spectrum sharing mechanisms to manage the complexity of a dynamic and mobile 3D network. Most probably, artificial intelligence-based solutions are required. 6G SatCom related spectrum sharing may include spectrum coexistence a) between different satellite systems, b) between satellite and terrestrial systems and c) between systems in different layers of the multi-layer network. There have been studies on database-assisted spectrum sharing operations and predictive approaches where e.g. licensed shared access has been studied (Höyhtyä et al., 2021). However, plenty of technical studies and regulatory decisions will be required to enable visions shown by the research community.
M. Höyhtyä et al., “Licensed shared access field trial and a testbed for integrated satellite-terrestrial communications including research directions for 5G and beyond” Wiley International Journal of Satellite Communications and Networking, vol. 39, pp. 455–472, July/August 2021 https://doi.org/10.1002/sat.1380.
M. Höyhtyä, S. Boumard, A. Yastrebova, P. Järvensivu, M. Kiviranta, and A. Anttonen, “Sustainable Satellite Communications in the 6G Era: A European View for Multi-Layer Systems and Space Safety,” submitted for consideration in IEEE journal, preprint available at https://arxiv.org/pdf/2201.02408
Marko Höyhtyä received the D.Sc. (Tech.) degree on telecommunication engineering from the University of Oulu, where he currently holds associate professor position. He is an associate professor at the National Defence University as well. He is currently working as a New Space Co-Creation Manager, coordinating space technology research at VTT. He was a Visiting Researcher at the Berkeley Wireless Research Center, CA, from 2007 to 2008, and a Visiting Research Fellow with the European Space Research and Technology Centre, the Netherlands, in 2019. His research interests include critical communications, autonomous systems, and resource management in terrestrial and satellite communication systems.