Communication emergency high altitude base station

In the last few years, a new set of options have been added in the form of high al-titude platform stations (HAPS) and unmanned aerial vehi-cles (UAVs) that operate as mobile telecom providers, mos-tly operating at stratospheric altitudes of ~20 km, or other low altitudes, above earth; in our days, it has been deeply studied that near-space platforms could be safely deployed at altitudes in the 17-25 km range. [pdf]