# Spectrum Sharing Opportunities for 6G Terrestrial and Non-Terrestrial Networks +
## 1 Introduction  
In order to meet the requirements in terms of the coverage, capacity and user experience of various emerging 6G applications and new use cases and usage scenarios, interworking between terrestrial and non-terrestrial networks is increasingly fundamental. The joint evolution and interoperability of both IMT and non-IMT (including RLAN and broadcast) terrestrial networks and non-terrestrial networks, including satellite communication systems, HIBSs (high-altitude platform stations as IMT base stations) and UASs (Unmanned Aircraft Systems), are considered key elements in providing the expected 6G services. The definition and evaluation process for the new IMT-2030 technology is underway within the ITU (International Telecommunication Union). In November 2023, the ITU approved Recommendation ITU-R M.2160 on the \"IMT-2030 Framework\" [1], which defines the overall framework and objectives of IMT towards 2030 and beyond, to guide future developments of IMT, including the evolution of the radio access network. In this context, the framework and overall objectives of future IMT development described in Recommendation ITU-R M.2083 [2] and of future technology trends included in Report ITU-R M.2516-0 [3] were taken into account. In the period 2024-2027, the ITU will define the relevant requirements and evaluation criteria for potential new radio IMT interface technologies. In May 2024, the ITU also finalized Report ITU-R M.2541 [4] on the technical feasibility of IMT in bands above 100 GHz. The report includes information on propagation mechanisms and channel models, as well as newly developed technology enablers such as active and passive components, antenna techniques, deployment architectures, andthe results of simulations and performance tests. This report complements Report ITU-R M.2376 [5], containing studies on IMT usage in the frequency range of 6-100 GHz. Agenda item 1.7 of the World Radio Conference 2027 (WRC-27) invites us to perform sharing and compatibility studies to ensure the protection of services to which the frequency band is already allocated on a primary basis and possibly develop technical conditions for the use of IMT in the frequency range of 4-15 GHz [6]. The possible IMT identification could make these new frequency bands suitable candidates for 6G deployment. The evolution of terrestrial systems also includes the use of RLANs/WASs (radio local area networks/wireless access systems) license-exempt networks; the WiFi 6E and WiFi 7 standards, designed to work in the 6 GHz band, can implement higher bandwidths to achieve the required high throughput and low latency to serve specific 6G use cases (i.e., automotive, virtual reality, augmented reality). The use of WiFi technology to provide the evolved services envisaged for 6G is facilitated by the European initiative 'European Digital Decade Policy Programme 2030--\"Gigabit for everyone\", [7] which provides gigabit FTTH (fiber to the home) distribution up to the network termination point. WiFi 6E and WiFi 7 technologies are therefore a good solution to complement gigabit fiber connections. The frequency band 6425-7125 MHz has been identified for IMT at the last World Radio Conference WRC-23. The IMT identification footnote includes recognition that these frequency bands can be also used for WASs/RLANs. The European Commission is finalizing the mandate for the CEPT (European Conference of Postal and Telecommunications Administrations) to study the feasibility of and to develop harmonized technical conditions for the efficient use, on a shared basis, of the 6425-7125 MHz ('upper 6 GHz') frequency band for the most recent and future technologies for terrestrial systems capable of providing wireless broadband (WBB) electronic communications services (ECSs) and for wireless access systems including radio local area networks (WASs/RLANs).