This will be discussed later in this section.
3.6.3 Modified Hata Path Loss Model
There has been much work performed to extend the model for carrier frequencies up to 2 GHz. The
modified Hata model is given as follows [17].
(3.69)
where CM 0 dB for medium cities and suburban areas, 3 dB for metropolitan areas.
The valid range of these modified parameters is now
(3.70)
3.6.4 Bertoni-Walfrisch Path Loss Model
In this section we will approach the path loss discussion from a different angle. Previous models were
based on measured data where mathematical representations were formulated that would best
describe the behavior observed in the measured data. This present model will actually start with a
mathematical description of the environment and then provide the prediction of the path loss. As we
will soon see, there is reasonable agreement between these two approaches [91].
A block diagram showing the underlying mechanisms of the mathematical model is presented in
Fig. 3.45.
In Fig. 3.45 various variables have been shown and next we attempt to define them. R distance
between the transmitter and receiver, b separation of building rows,
wavelength of carrier frequency,
angle to last roof tip, r distance to the MS from the building rooftop, diffracting
angle to the MS, and x distance from building to mobile location.
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