Advanced
Propagation Modeling and RF Channel Characterization
ZHENGQING
YUN & MAGDY ISKANDER
Propagation modeling and channel characterization provide critically important data for the design and performance evaluation of advanced wireless communications networks. Since current and next generation wireless communications systems have wider bandwidths, higher data rates, and smaller cell sizes, site-specific propagation parameters are required over a broad frequency band and for complex communication environments. As new technologies such as smart antennas and multiple-input multiple-output (MIMO) systems are introduced, new propagation parameters, e.g., delay spread and angle of arrival, are needed for optimal system design.
Ray-tracing method, as one of the most widely used methods for accurate and site-specific propagation prediction, has received intensified attention from the research community. Based on geometrical optics and the uniform theory of diffraction, the ray-tracing method can accurately predict the electric field distribution and area coverage in such diversified propagation environment as a city block or an office building.
Traditional ray-tracing methods are not appropriate
for complex structures such as diffraction from
indoor objects, metal-framed windows, and reinforced
concrete walls. Other numerical methods, e.g.,
the finite-difference time-domain (FDTD), on the
other hand can be employed to develop ray-models
(building blocks) that can be integrated in the
traditional ray-tracing code.
Besides the ability to model challenging wireless communication environments, it is important that ray-tracing results be expressed in terms of parameters that can be used to model realistic and practical propagation systems. Development of ray-tracing for challenging propagation environments, and integrating the results to help simulate the performance of wireless system are the focus of HCAC research in the propagation and channel modeling.
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