There is a growing interest for High Altitude Platforms (HAPs) positioned at a stratospheric altitude of about 20 kilometers and used to complement terrestrial or satellite networks.

 

HAPs platforms can be of different types: floating balloons (such as Google Loons), solar planes (such as Airbus zephyr) or stationary airships (such as Thales Alenia Space Stratobus). They can be used for observation as well as communication service with fixed or mobile terminals.

 

Figure below is an illustration of a fleet of airship HAPs carrying base station to provide cellular coverage. They use antenna with dynamic beam forming and can be adapted to various mobile density conditions: from reduced coverage high density to extended range low density.