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The
Deterministic Two Ray Model (DTR) model computes the
direct ray and the ground reflected ray with ray optical
algorithms. If the rays are shadowed by obstacles, they
are not considered. This is the difference to the
Empirical Two Ray Model (ETR)
which considers both rays independent of their existence
(i.e. if they are shadowed or not).
The figure
shows a prediction with the DTR Model in a very hilly
scenario. As explained above, received power is only
predicted for pixels which can be reached by the direct
ray and/or the ground reflected ray. All pixels in areas
without LOS to the transmitter are not predicted. To get
a prediction also for these pixels, the DTR must be
combined with the Knife Edge Diffraction Model to
include the diffractions at the topographical obstacles.
For the
specular reflection the incident angle of the ray and
the reflected angle must be identical. The material
properties of the ground can be defined and the
reflection loss is computed depending on the angle of
incidence and the material properties.
The model can be used for all applications with a
frequency range between 300 MHz and 300 GHz. |
