Page 103 - Integrated Wireless Propagation Models

M a c r o c e l l P r e d i c t i o n M o d e l s - P a r t 1 : A r e a - t o - A r e a M o d e l s 81

where
<
b -{ 1, 0 dkm 2 0 km
-
1+ ( 0.14+0.000187 JMHz + 0 .00107h;)(log10(dkm/20)) 8 dkm � 20 km
and h; in the equation of b is

2.12.2.2 Hata-Davidson Model
The Hata-Davidson modeP is derived from the Hata model, which was in turn based
on the Okumura' curves, as described previously.
The main factors included in Hata-Davidson model are the area type (urban, suburban,
quasi-open, and open) as well as corrections for the receiver antenna height. The model
also includes frequency and distance corrections to extend the distance range to 300 km.
The Hata-Davidson model computes the basic median field strength based on the trans­
mit antenna height measured on the HAAT rather than the topography of the entire path.
HAAT is calculated on the undulation of terrain from a 3 to 16 km segment over the radio path.
The Telecommunications Industry Association recommends in its publication
TSB-88A that the Hata-Davidson model is the modification of Hata model, which con­
sists of the addition of correction terms:

(2.12.2.3)
where A(h1, dkm) and 51 (dkm) are the distance correction factors extending the range to
300 km. They are listed below:

k
d m < 20 0 0
20 � d m < 64.38 0.62137(d,m 2 0)[0.5 +0.151og 0 ( h /121.92)] 0
-
1
1
k
64.38 � d m < 300 0.62137(d m -20)[0.5 + 0.151og 1 0 ( h /121.92)] 0.17 4(d m - 64.38) 1
k
1
k
k
52 is a base station antenna height correction factor extending the range of h1 values to
2500:
53 and 5 are frequency correction factors extending the frequency to 1500 MHz:
4
53(/ M ) = / M HJ250log10(1500/f M )
Hz
Hz
54(/MHzAnJ = [0.112log10(1500/JMHJ](dkm - 6 4.38) for dkm > 64.38 km

2.13 Walfisch-Bert n i Model
o
The Walfisch-Bertoni model is a physical model that addresses propagation in urban envi­
42
ronments. Figure 2.13.1 illustrates the geometry used in the W a lfisch-Bertoni modeF • 5
As shown in Fig. 2.13.1, there are four paths. The most important path is the primary path
2
to the mobile that is diffracted over the tops of the buildings in the vicinity of the mobile/6• 7