## 1 Introduction  
Today, 5G NR technologies play one of the most important roles in the sustainable development of countries, and different types of enhanced applications such as IoT, smartphone connectivity, industrial applications, smart cities, vehicle communications, and many others require high network capacity. To fulfill the requirements of all emerging 5G applications, an extra spectrum is needed for capacity expansion. According to numerous reports, including GSMA, to meet the demands of future 5G applications in a long-term period, an extra 2 GHz of the spectrum might be required to be allocated for 5G [1]. At present, the following bands are allocated for international mobile telecommunications (IMT), and some of these bands are already in use for 5G and some of them are still being studied for compatibility issues. Current bands identified for IMT are presented in Table 1, and the bands are divided into three categories: low bands, middle bands, and high bands. The low bands are good for providing higher coverage since the propagation conditions are much better in these bands, particularly because they allow us to improve residential connections, provide smart energy services, and provide rural coverage. Middle bands are good for providing urban coverage for different types of services, including smartphone connectivity, vehicle communications, transport infrastructure, etc. High bands allow for providing services in small areas where extremely high capacities are required, such as large-scale events (e.g., sports games, concerts, exhibitions, and so on). The frequency bands 5G NR were split into frequency range one and frequency range two (FR1 and FR2). Frequency range one works at sub-6-GHz or below the 6 GHz band, whereas frequency range two covers the millimeter waves [2; 3; 4]. This study focuses particularly on the 4800-4990 MHz band for the reason that this band has potential problems with international compatibility with incumbent services which require interference analysis. During the World Radiocommunication Conference in 2015 (WRC-15), organized by the International Telecommunication Union (ITU), a significant number of countries added their name to footnote 5.441B of the Radio Regulations, which identified the frequency band 4800-4990 MHz for International Mobile Telecommunications (IMT) [5; 6; 7]. Additionally, 3 GPP has designated the 4400-50,000 MHz band for 5G NR standard under the prefix n79 frequency, which includes the 4800-4990 MHz band. The strongest interest to use this band for 5G NR applications was shown by China, Russia, Japan, Brazil, Vietnam, South Africa, Nigeria, and many other countries. Overall, 40 countries are included in current footnote 5.441B of the Radio Regulations, thus the 4800-4990 MHz developed an interest from a significant number of countries. This, however, has raised a question of protection of the aeronautical and maritime mobile services operating in this band, in particular those aeronautical and maritime receivers that are located in international airspace or waters. The frequency range of 400-4990 MHz is allocated on a primary basis in all three ITU regions to the mobile service. Under the mobile service allocation, systems and networks operating in the aeronautical and maritime mobile service comprise stations for broadband, airborne, or shipborne data links to support remote sensing and stations of aeronautical mobile telemetry. These systems may experience interference from the aggregate interference of 5G NR deployed in the cities near the coastline, especially since many of the countries that showed interest in the 4800-4990 MHz frequency band have access to the oceans, where a lot of aircraft and vessels may use that band while being in international airspace or waters at a different distance from the coastlines.