Virtual source modeling for diffraction in reference channel models

The paper investigates diffraction-specific ray properties which should be implemented in reference channel models in order to achieve physically correct representation of diffraction. When modeling propagation by diffraction (mostly in urban settings), one needs to decide on how to arrange virtual sources of rays that arrive from the base station to the user. Usually, virtual sources are placed at the edges of buildings where diffraction occurs. The paper analyses if this usual approach is appropriate, especially in the case of mobile users, where Doppler frequency shift needs to be modeled correctly. To that goal, a model for virtual source is established, that mimics correctly angles of arrival, time delay and Doppler frequency shifts.