464
CELLULAR AND PCS RADIO SYSTEMS
where
r is between 150 MHz and 1500 MHz,
h
t
is between 30 m and 300 m, and
d is the path distance and is between 1 km and 20 km.
A(h
r
) is the correction factor for mobile antenna height and is computed as follows:
For a small- or medium-size city,
A(h
r
) = (1.1 log f - 0.7)h
r
- (1.56 log f - 0.8)(dB),
(18.2a)
where
h
r
is between 1 and 10 m.
For a large city,
A(h
r
) = 3.2[log(11.75h
r
)]
2
- 4.97(dB),
(18.2b)
where
f 400 MHz.
Example. Let
f = 900 MHz, h
t
= 40 m, h
r
= 5 m, and d = 10 km. Calculate A(h
r
) for
a medium-size city.
A(h
r
) = 12.75 - 3.8 = 8.95 dB
L
dB
= 69.55 + 72.28 - 22.14 - 8.95 + 34.4
= 145.15 dB.
18.3.2.3
Building Penetration
. For a modern multistory office building at 864 and
1728 MHz, transmission loss
(L
dB
) includes a value for clutter loss L(v) and is expressed
as follows:
L
dB
= L(v) + 20 log d + n
f
a
f
+ n
w
a
w
,
(18.3)
where the attenuation in decibels of the floors and walls was
a
f
and
a
w
, and the number
of floors and walls along the line
d were n
f
and
n
w
, respectively. The values of
L(v) at
864 MHz and 1728 MHz were 32 dB and 38 dB, with standard deviations of 3 dB and
4 dB, respectively (Ref. 2).
Another source (Ref. 5) provided the following information: At 1650 MHz the floor
loss factor was 14 dB, while the wall losses were 34 dB for double plasterboard and
79 dB for breeze block or brick. The parameter
L(v) was 29 dB. When the propagation
frequency was 900 MHz, the first floor factor was 12 dB and
L(v) was 23 dB. The
higher value for
L(v) at 1650 MHz was attributed to a reduced antenna aperture at this
frequency compared to 900 MHz. For a 100-dB path loss, the base station and mobile
terminal distance exceeded 70 m on the same floor, was 30 m for the floor above, and
was 20 m for the floor above that, when the propagation frequency was 1650 MHz. The
corresponding distances at 900 MHz were 70 m, 55 m, and 30 m. Results will vary from
building to building, depending on the type of construction of the building, the furniture
and equipment it houses, and the number and deployment of the people who populate it.
18.4
IMPAIRMENTS: FADING IN THE MOBILE ENVIRONMENT
18.4.1
Introduction
Fading in the mobile situation is quite different from the static line-of-sight (LOS)
microwave situation discussed in Section 9.2.4. In this case radio paths are not opti-
mized as in the LOS environment. The mobile terminal may be fixed throughout a