What is High Altitude Stratospheric Platforms (HASPs)

High Altitude Stratospheric Platforms (HASPs) have gained much of attention from the scientific society and the communication industry in the recent years. Their use in the Next Generation Networks can offer enhanced coverage and facilitate the implementation of several heterogeneous wireless networks schemes. In this chapter, the main aspects of the HASP-related technology are presented. Emphasis is given in the ways the intrinsic characteristics of these platforms can be used effectively in order to compensate for the disadvantages of both the existing terrestrial and satellite solutions. Antennas and coverage planning, capacity and interference, call admission control, handover, mobility management, networking and TCP/IP performance are the main issues addressed. The provided mathematical tools and the state-of-the-art techniques presented here, can be useful to engineers interested in designing and evaluating performance of HASP-aided hybrid networks.