Page 302 - Integrated Wireless Propagation Models

280 C h a p t e r F i v e

5.2.8 Analyzing the Lee In-Building Prediction Model
It is necessary to evaluate the prediction model by estimating the link budget for a typi­
cal indoor wireless system. Both the Lee and the Keenan-Motley in-building propaga­
tion models are analyzed in two situations-LOS and NLOS-and from the estimation
of the link budget for the coverage boundary in the in-building applications. Some issues
regarding the Lee and modified Keenan-Motley models are identified and discussed.
Finally, an enhancement of the Lee model is presented that provides better flexibility and
accuracy.
5.2.8. 1 Description of the Keenan-Motley Model and the Lee In-Building Model
Depending on the particular values used for different parameters, we set up the link
budget to be 110 dB. Then, from the measurement data, we found that the coverage
distance under the LOS situation varies from 200 to 300 m. Under the NLOS situation
and with one room at the end of building, the coverage distance varies from 160 to 200 m.
This demonstrates largely that the coverage is limited by the NLOS situation. For example,
in the LOS situation, 3 dB can extend coverage distance from 15 to 30 m. In the NLOS
situation, 3 dB does not provide much extension on coverage. Nevertheless, it does
provide some enhancement of the RF signal quality, especially in the C/1 calculation.

5.2.8. 1 . 1 The Keenan-Motley ModeP 2
P, = P, - L (dB) = P, - 32.5 + 20 log(j) + 20 log(d) + K · F(K)
+ P · W(K) + ( d - Db) (5.2.8.1.1)
D
where
/
Free space formula = -32.5 + 20 log( ) + 20 log(d)
=
L p ath loss (dB),
f = frequency in MHz,
d = transmitter to receiver separation in km,
K n umber of floors traversed by the direct wave,
=
F(K) = floor attenuation factor (dB) based on K number of floors,
P = number of walls traversed by the direct wave,
=
W(K) w all attenuation factor (dB) based on K number of floors,
D = linear attenuation factor (dB/m), and
Db = indoor breakpoint (m).

For distances above the breakpoint, typically add 0.2 dB/m (typical breakpoint= 65 m).
Since this section focuses only on the same floor prediction, those parameters that
deal with different floors are not discussed.
5.2.8. 1.2 The Lee Model The Lee model formula can be expressed as

P, = JJ. +G, - Lw s - L - L(c) +G, (5.2.8.1.2)
(BJ
The symbols P,, G,, L ws' and G,, are shown in Sec. 5.2.2.1.
• When in the LOS condition
L ( B) = 0
L = 0
rq