Title
Modeling and Characterization of Ground-to-Air Communication Channel
Radio channel characterization is an important field of research which explores the limiting features of the propagation environment and helps designing efficient communication systems. This dissertation presents an in-depth analysis of the A2G/G2A channel models and formulates the problem of G2A channel characterization in the presence of multipaths in a multiple aircraft environment. It is observed that most of the research literature supposedly model G2A channels interchangeably in the same manner as that of land mobile communication links. G2A communications systems are generally equipped with directional antennas for dedicated coverage to flying aircrafts that benefit in increasing range and radio signal strength while restraining interfering signals coming through scattering objects around ground station (GS). This research analyzes G2A multipath channel and thus proposes a geometrically-based physical G2A multipath channel model. The proposed channel model clearly justifies the existence of multipath environment in G2A communication due to the existence of aircrafts in the vicinity of the intended aircraft. This model is based on a three-dimensional confocal prolate spheroids and uses the principle of single-bounce multipath geometry. In order to observe the reflection properties of aircraft, a new term named as Spatial Reflection Coefficient (SRC) is defined and then a novel relationship of the interdependence between RADAR Cross-Section (RCS) and SRC is established. This relationship relates two different terms which are being used differently in two different fields of research. Both terms are inter-dependent and utilize the same input parameters like incident angle, material properties, signaling frequency, polarization and observation angle. The proposed relationship interrelates RCS and SRC which interchangeably help to extract the reflectivity information of a target’s surface on the basis of observed RCS. Moreover, this interchangeability between the RCS and SRC will help the researchers of different fields to utilize simulation tools and algorithms of both domains interchangeably. The scattering properties of the body of an Aircraft are analyzed by designing geometrical models of two scenarios, satellite-to-aircraft and ground-to-aircraft. The proposed geometrical models help to estimate the correct incident angles of incoming electromagnetic (EM) waves impinging on aircraft’s surface. Utilizing information of the reflected signal from aircraft’s body and the proposed multipath geometry, an expression for the total received power at the intended aircraft is developed. For numerical computations, a quasi-realistic G2A propagation environment is constructed in Matlabr. Simulations for bistatic radar cross section (BRCS) are performed by taking A380r facet-based model on physical optics based simulation software platform POFACETr and power delay profiles (PDPs) are developed. Statistics of the PDPs are then evaluated and the expected data rates of the designed scenario are envisioned. This study highlights the time-dispersive nature of the G2A propagation environment and may become a foundation to observe the communication link performance of G2A applications in recent future. Furthermore, a visualization of the interference caused in wide-beam and narrow-beam G2A communication link scenarios is presented. The proposed model is equally applicable to the networks of passenger aircrafts, flocks of jet fighters and mesh of Unmanned Aerial Vehicle (UAV) drones. This model can also be used to analyze the performance of high data-rate communication links with high mobile speeds over sparsely distributed multipath channels.
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