In the first phase of the Study, a detailed review of technologies and specifications for bandwidth-efficient communications was performed. Three major technologies were identified: Coordinated and Non-Coordinated Dynamic Spectrum Access (DSA), centralised and federated Multi-User Multiple-Input Multiple-Output (MU-MIMO) via satellite, and Multi-Connectivity (MC). Evaluations highlighted their benefits for 5G services, including extended coverage, efficient spectrum sharing, capacity gain, and improved user throughput. These technologies were assessed in the DYNASAT NGSO constellation, designed by Thales Alenia Space for global 5G connectivity.
MC and Coordinated/Non-Coordinated DSA in NGSO systems have been demonstrated at EuCNC 2022 (with preliminary evaluations) and at the Mobile World Congress (MWC) 2023. MC and C-DSA were implemented using a remote simulation environment developed by Magister solutions, while NC-DSA was demonstrated via a web-based spectrum sharing tool developed by Fairspectrum. The demonstrations gathered a great interest in both events, further substantiating the excellent results obtained in the DYNASAT Project.
A detailed description on the validation activities and plans in preparation of a potential In-Orbit Validation (IoV) of the DYNASAT system, as well as the demonstration of various use cases, has been developed based on the thorough performance assessment of the considered bandwidth-efficient techniques. Such report provides a selection among different IoV configuration options with respect to the resources in orbit, the definition of the test payload to be embarked, the test platform elements, and the identification of the necessary actions to access the spectrum during the experiment.
In the framework of 3GPP standardisation, since 3GPP RAN#94-e, several Rel. 18 Work Items (WIs) have been initiated related to NTN. Thales Alenia Space France is a leading force in the definition of the NTN specifications, including new Study or Work Items and technical contributions, also based on the analyses performed in the DYNASAT project. In particular, such contributions are mainly focusing on MC and spectrum sharing solutions; with respect to MIMO, which in 3GPP nomenclature is referred to as Coherent Joint Transmission, no specific WI/SI was identified in Rel. 18, while it might be addressed in Rel. 19 or 20. This is also motivated by the priority given to Non-Coherent solutions, which allow to relax the tight time and frequency synchronisation among the cooperating nodes.
Finally, from a regulatory perspective, the work performed in the DYNASAT Project allowed to bring forward the idea of satellite-terrestrial IMT systems by taking advantage of the development of a Satellite Radio Interface at ITU level. The DYNASAT analyses support the current development of the Vision and Requirements for the satellite component of IMT-2020 within ITU and allow to promote the international recognition of the 5G NR interface.
