Page 393 - Integrated Wireless Propagation Models

T h e l e e C o m p r e h e n s i v e M o d e l - I n t e g r a t i o n o f t h e T h r e e l e e M o d e l s 3TI

calculated with the Lee model. The antenna height at the transmitter is 33 m (100 ft), and
1
the mobile antenna height is . 5 m. The RSSI can be found from Eq. (4.2.1.2.1):
(6.4.3.1)

where P, = received signal strength, P, = transmitted power, Lws =loss under line of sight,
L8 = loss due to building, Ga = antenna height gain and G A = additional gain.
If L8 is obtained from Eq. (4.2.1.2.3), then we have to use Eq. (4.2.1.2.4) for Ga when
the actual antenna height is different from 20 ft and G A = 0 in these case below.
Finding RSSI at Points 10 and 15-For finding RSSis of these two points in the
microcell virtual environment, Eq. (4.2.1.2.1) is used.

3
6.4. . 1 RSSI at Point 10
Point 10 is in a LOS condition. At this point, the transmitter antenna height h" is 33 m
(100 ft), the mobile antenna height h is 1 . 5 m, and the distance from the transmitter to
2
2
2
the oint is 2 80 + (75- 45) = 85.44 on the ground distance. The radial distance is
- 1
2 85.442 + (33 .5)2 = 91 m. Using the near-in distance formula from Eq. (4.2.1.1.4),
4h h
df = � 2 (6.4.3.2)
The near-in distance at a frequency of 2.4 GHz A = 0.125 m) is
(
d = 1584 m > 82 m
1
Sample point 13 is within the near-in distance. Using the free-space path-loss formula;
4rcd
Lws = 20log T = 20log 4rc * 91 = 79.22 dB (6.4.3.3)
0.125
So, the RSSI at point 13 is P, = 20 dBm 79.22 dB = -59.22 dBm.

6.4.3.2 RSSI at Point 15
Point 15 is 10 m inside of another building. The ground distance from the trans-
2
2
mitter to point 15 is �(10+ 6 0 + 20) + ( 45-30) = 91.24 m. The radial distance is
2
d = �91 . 242 +(33- 1 .5) = 96.53 m. Although point 15 is within the near-in distance, it is
in the NLOS condition due to the wall of the building. There is one wall between trans­
mitter and point 15. The additional loss due to one wall is about 10 dB (can be obtained
from the measurement data). Then the total loss is calculated from Eq. (6.4.3.1):

�
P , = - Lws - La +Ga
4rc x 9653
- 20 dbm- 20log A - 1 0+ 0
-
=
= 20 - 79.73 1 0 - 69.73 dBm
-
The received signal at point 15 is -69.73 dBm.
Figure 6.4.3.1 compares FDTD and 30 ray tracing models with Lee micro model as
the baseline for the selected 15 points. The signal strengths of Lee microcell model from
all the 15 points are stronger than those of other two models.