engleski

Diffraction in urban scenarios: Where is the (virtual) source?

In urban scenarios diffraction is significant, if not dominant mode of propagation. When implementing geometry-based reference channel models, , in order to achieve physically correct representation of diffraction one needs to decide on how to arrange virtual sources of rays that arrive from base station to the user. Usually, virtual sources are placed at the edges of the buildings where diffraction occurs. This paper analyses if this usual approach is appropriate, specially in the case of mobile users, where Doppler frequency shift needs to be modeled correctly. The results show that this common approach is valid only for a static case and yields Doppler shift miscalculation in mobile user case. An alternative approach to modeling of virtual sources in case of diffraction is suggested, that can be used as a new paradigm for diffraction modeling in geometry-based reference channel models.

urban scenario diffraction, virtual source, radio channel modelling

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