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The Empirical
Two Ray Model (ETR) model computes the path loss to each
pixel based on the assumption that the direct ray and
the ground-reflected ray would exist. There is no check
if the rays are really existing or if they are shadowed.
The visibility check is only made in the
Deterministic Two Ray Model
(DTR) which considers rays only if they are not
shadowed.
The figure
shows a prediction with the ETR Model in a very hilly
scenario. As explained above, received power is always
predicted for all pixels independent of the visibility
status between transmitter and receiver. The predicted
values for the path loss do not depend on the LOS or
NLOS status. To include an additional loss for all
pixels which have no LOS to the transmitter, the ETR
must be combined with the Knife Edge Diffraction Model
to include the diffractions at the topographical
obstacles.
The model can
be used for all applications with a frequency range
between 100 MHz and 300 GHz. |
