HAPS are airborne platforms which can include aeroplanes, balloons, and airships. The base station element in a typical terrestrial network is relocated to the sky, creating International Mobile Telecommunications base stations (HIBS) which can cover large areas of land and therefore users with a single flying platform. A HIBS system provides mobile service in the same frequency bands as terrestrial mobile networks and can be used to provide both fixed-mobile connectivity for end users and transmission links between the mobile and core networks for backhaul. It can enable wireless broadband deployment in remote or dense urban areas, and the ability to provide telecom services with minimal ground network infrastructure makes it suitable for rapidly deployable disaster recovery communications and temporary coverage of entertainment events. The use of these networks has been enabled by advancements in array antennas, solar panel efficiency levels and battery densities. As part of clusters, they can become a permanent feature in the communications infrastructure.
Air-to-ground networks provide in-flight connectivity to aeroplanes via ground stations which play a similar role as base stations in terrestrial mobile networks. The antennas of the ground stations are up-tilted towards the sky, and the distances between the ground stations are much larger than that of terrestrial mobile networks.
Satellite connectivity has played a relatively minor role to date in the telecoms sector, but the ubiquitous coverage that it supports will be increasingly business-critical for operators, especially in IoT applications. However, there are some challenges including understanding how they sit alongside and integrate with terrestrial network technologies and consolidating commercial opportunities and providing the market viability of use cases. There are also more practical considerations such as space traffic management and access to spectrum frequencies.
NTNs also require policies on both the physical media (space and airspace) and telecoms services (mainly spectrum licensing). The International Telecommunications Union (ITU) currently works with administrations to help regulate and coordinate satellite orbits and spectrum use, but this is very much in its infancy and governments will likely then want to define their regulatory frameworks.
Standards development will also be important to ensure widespread adoption and sustainability. This work has already started: 3GPP Release 17 supports NTN elements and 6G is adopting NTN as a core element. This convergence of standards—alongside improvements in satellite costs and latency—will broaden the role of satellite communications within fixed and mobile network technologies.