high altidude platform (satellite comm.) (HAP)

Stratospheric communications platforms are intended to link satellite-based and terrestrial communications. Since terrestrial communications are affected by ground infrastructure and radio cell density depends on traffic density and ground acquisition, geostationary communications platforms positioned in the stratosphere, called High Altitude Platforms (HAPs), are under discussion as an alternative for satellite communications and terrestrial mobile communications.

Stationed at altitudes of 15 km to 25 km, the HAPs, which could be installed in an unmanned airship, could serve a radio range of about 500 km. HAPs have no transit time problems compared to geostationary satellites and the advantage over Low Earth Orbiters( LEO) in that they are stationary and do not change location.

Thanks to the large radiation area, all of Europe could be irradiated with about 30 stratospheric communications platforms, as opposed to several thousand base stations.

Frequencies in the 47.2 GHz and 48.2 GHz range have already been reserved internationally for communications between the HAPs and ground terminals, especially since high-speed data transmission is possible over such platforms. The HAPs are also interconnected via link connections, the Inter Platform Links( IPL). Since there is line-of-sight between the HAPs and no cloud interference is possible, this connection can be laser, which would enable data rates in the gigabit range.