Performance Evaluation of HAP-based Communications Using a Realistic Channel Model

The term HAPs (High Altitude Platforms) defines both airships or airplanes, flying at an altitude ranging between 17 and 30 km in the stratosphere. Recently, they have been proposed as a valid alternative to traditional terrestrial or satellite based communication systems. The International Telecommunication Union (ITU) has endorsed various frequency ranges for HAPs applications. In particular, the bands 47.2 -47.5 GHz and 47.9 -48.2 GHz are allocated for fixed services (1); the frequency range 18 - 22 GHz is allocated to a number of countries in Region 3 for broadband wireless applications (2); and the bands 1885 -1980 MHz, 2010 - 2025 MHz, 2110-2170 MHz in Region 1 and 3 and 1885 -1980 MHz and 2110 -2160 MHz in Region 2 are allocated to the 3 -rd generation wireless communication systems (3). The LHAP channel, for carrier frequencies in the low GHz bandwidth endorsed by ITU for HAP -based communications, is time and frequency selective and its features are different from the usual terrestrial channels. In this paper, a LHAP channel model for the communication link between the platform and terrestrial users or grou nd stations is briefly reviewed (4). Then, considering different modulation schemes, the performances of the channel are investigated.