Page 272 - Integrated Wireless Propagation Models

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

where A. is the wavelength (m). Equation (4.5.5.2.2) is adapted from the near-in distance
2
d shown in Eq. (4. . 1 . 1 . 4). An approximate upper bound is given by
1
25 log10[�J

(4.5.5.2.3)
40 log10[�J for d > R bp

L is a value for the basic transmission loss at the breakpoint, defined as:
bp
L bp = 1 20 log lo[ sn�:h ( 4.5.5.2.4)

4.5.5.3 N L OS Models
Usually under the NLOS condition, NLOS signals can arrive at the BS or MS by diffrac­
tion mechanisms or by multi path, which may be a combination of diffraction and reflec­
tion mechanisms. There are two cases to be treated in this model: the base station
antenna above the rooftop and the base station antenna under the rooftop.
The models are valid under the following conditions:
h = 4 to 50 m
b
h = 1 to m 3
m
f= 800 to 2 000 MHz
d = 20 to 5 000 m

3
4.5.5. . 1 Propagation over Rooftops-NLOS44 The typical NLOS case (link BS 1 to MS 1 ,
l
l
shown in Fig. 4.5.5.3. . l ( a) is a view in a vertical plane) is described by Fig. 4.5.5.3. . l ( b)
in a top view. This case is called NLOSl.
The relevant parameters for Fig. 4.5.5.3.1.1(a) are the following:
h, = average height of buildings (m),
w = street width (m),
b = average building separation (m),
<p = street orientation with respect to the direct path (degrees),
h = BS antenna height (m),
b
h"' = MS antenna height (m),
l = length of the path covered by buildings (m), and
d = distance from BS to MS.
1
In the NLOS1 case (see Fig. 4.5.5.3. . 1 ) for rooftops of similar height, the loss
between two isotropic antennas is expressed as the sum of (1) freespace loss, L ; (2) the
b 1
diffraction loss from rooftop to street, L,1, ; and (3) the reduction due to multiple screen
diffraction past rows of buildings, L d·
ms
In this model, Llf and L,1, are independent of the BS antenna height, while L msd is
dependent on whether the base station antenna is at, below, or above the building
height.