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Abstract High Altitude Platform (HAP) is one of the most promising infrastructures for realizing high data rate wireless communication systems in the near future. This thesis investigates a survey on communication aspects of High Altitude Platforms, namely airships or aircrafts flying at an altitude ranging between 17 and 22 km above the ground in the stratosphere. The survey begins with an introduction to HAP, historical information and advantages of HAPs compared to terrestrial and satellite networks, information about suitable airships and aircrafts, frequency bands allocated to HAPs, possible architectures, channel modeling and interference, antennas, transmission and coding techniques, access and resource allocation techniques and the type of applications that HAPs are suitable for, in addition to some related projects. An essential problem need solving for the design of HAP communication systems is to establish an effective channel model for predicting the characteristics of the communication link. There have many papers on this problem and several channel models have been proposed. We will summarize and analyze the channel models available. The existing models are divided into three categories according to their respective specialties and each channel model is briefly introduced with emphases on analysis of their strengths and weaknesses. A three-dimensional (3-D) analytical model for mobile-to-mobile, single input single output (SISO), for terrestrial network is presented as a guided model for us. From this model, the envelope Level Crossing Rate (LCR) and Average Fade Duration (AFD) are derived for a 3-D non isotropic scattering environment. We investigates the application of Multiple Input Multiple Output (MIMO) techniques to HAP- based systems and proposes a Single Input Single Output (SISO) 3 –D geometry-based single receive reference model for Ricean channels. Since the model does not give us any information about the hand off velocities of the transmitter and receiver and fading rate, accurate characterization of the second order statistics, envelope level crossing rate (LCR) and average fade duration (AFD) is necessary. from the analytical model, we derive the complex faded envelope and from it we derive the envelope level crossing rate and average fade duration for a 3-D non-isotropic scattering environment HAP channel. The obtained numerical results are carried out to verify that the assumptions made are applicable to the case of HAP model. |