Page 254 - Integrated Wireless Propagation Models

232 C h a p t e r F o u r

-20.00
.
-30.00
-40.00 n. ..
�"TO �
'E -50.00
Ill . �..., "' �
� -60.00 l'o: o Meas (dBm)
en -70.00 - o Pred (dBm)
� \. 1,)
en -80.00 •a. . ..
a:
-90.00
-100.00
-1 10.00 .
0.00 0.20 0.40 0.60 0.80 1 . 00
Distance (mile)
(a)
1 0 0
--
80 /
v
.J
� 60
LL I
8 40
J
20
1/
00
0.00 5.00 1 0 .00 1 5 .00 20.00
Deviation (dB)
(b)
FIGURE 4.3.3.3 Route s_1900_02. (a) Measured and predicted versus distance. (b) CDF of
difference between measured and predicted.

4.4 Tun i n g the Model for a Particular Area

4.4.1 Before Tuning the Lee Microcell Model
The purpose of feeding the field-measured data back to tune the model improves the
accuracy of the model.

4.4. 1 . 1 The Multiple-Breakpoint Model
Within Lee's microcell model, the prediction of path loss uses the multiple-breakpoint
microcell prediction model with the terrain and building database. It is composed of
Pd , and P0, as shown in Fig. 4.3. . 1 .
three breakpoints, Pd f' 1 1
a
a
The areas within the first and second breakpoints s well s the intersection point d1
1
can be obtained from the measured data and are described in Sees. 4.3.1 and 4.3.2. . The
.
calculation of near-in distance is shown in Sec. 4.2 1 . 1 .
o
4.4. 1.2 The Algorithms f Integrating the Two Models before Tuning
The algorithms of integrating the two models are described in Sec. 4.3.1. These algo­
rithms are applied without using the measured data. The enhancement is introduced by