الفهرس 
Stratospheric segmentOnly 14 pages are availabe for public view
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Abstract
The demand for mobile communications services is growing at an explosive
rate with the anticipation to provide anyone, anywhere, and at any time with
services at low cost, high quality, high data rates supporting multimedia, with
little mobile handset. These demands have put the system operators and
researchers in a challenge with the system resources in digging for solutions
for increasing the system capacity and quality of service at an affordable cost.
Recently, an innovated communi,cations system based on utilizing High
Altitude Platforms (HAPs) has a great interest especially for mobile and
wireless data communications. They are located at 17-22 km above the earth
surface and the International Telecommunications Union (lTU) has already
allocated several bands of frequency from 2-66 GHz for HAP based
communications. The quasi-stationary aerial platforms operating in the
stratosphere preserve many advantages of both terrestrial and satellite
systems but also provide special advantages of their own.
Despite the optimistic features of HAPs, there are some issues that must be
explored and require research and developments such as system architecture,
interference analysis, antennas, channel and propagation characteristics,
modulation and coding and station keeping. In this work, the antennas
developments and interference mitigation are the main tasks. Interference
analysis is closely linked with the examination of the effects of the antenna
specifications on Carrier to Interference Ratio (CIR). Various types of
antennas are currently explored that meet the requirements imposed by the
high frequency bands, the movement of the HAP, the minimization of the
interference and the reduced weight, size, and power consumption of the