Current situation and technology trends of high altitude platforms

High-altitude platforms (HAPs) are autonomous airships or airplanes that fly beyond 20 kilometers in the ozone to build a telecommunications network or do remote sensing. Several initiatives were started in the 1990s and 2000s, but only a handful have been completed. In 2014, two major Internet corporations such as Google and Facebook announced new HAP initiatives to give Net access in areas where there is no network system (terrestrial or satellite), reviving interest in HAP development. The goal of this review is to review the history of HAPs, as well as the present state-of-the-art, technological developments, and problems. This analysis will concentrate on technology directly connected to the aircraft control system and inserted into the field of aviation, rather than on features of telecommunication services.