Microcellular radio-channel propagation prediction

Designers of wireless-communications networks require detailed understanding of radio-propagation in complicated, multi-path channels. Unlike conventional cellular systems, emerging wireless personal-communication networks will most likely operate in confined, urban environments (microcells). The application of broad-band-digital modulation to these networks requires careful consideration of the dispersive nature of the urban radio channel. This paper presents a ray-tracing simulation technique which incorporates site-specific environmental data, such as the location, the orientation, and the electrical properties of buildings, to predict path loss and delay spread in urban microcells. Using simplified geometric-optics assumptions, rays are traced in three dimensions. This determines the paths by which direct, specularly reflected and transmitted, diffusely scattered, and diffracted rays arrive at a receiver. The received rays are combined noncoherently as a function of delay, to estimate the channel power-delay profile. The power-delay profile is used for verification of model accuracy, via qualitative and statistical comparisons of measured and predicted data, for receiver locations on the Virginia Tech campus. The comparisons conclusively show the simulation's ability to accurately model urban microcellular propagation.<
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