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6-13
D-620003-0-20 Rev J
CONFIDENTIAL
Estimating RF Coverage
6.2.1
Path Loss Equation
Indoor path loss obeys the distance power law
1
in equation (2):
PL = 20log(4
π
d
0
f/c) + PLSlog(d/d
0
) +
Χ
s
(2)
where:
• PL is the path loss at a distance, d, from the antenna (the distance between the
antenna connected to the RAU and the point where the RF signal decreases to
the minimum acceptable level at the wireless device).
• d is the distance expressed in meters.
• d
0
is usually taken as 1 meter of free-space.
• f is the operating frequency in Hertz.
• c is the speed of light in a vacuum (3.0 × 10
8
m/sec).
• PLS is the path loss slope and depends on the building “clutter” or environ-
ment.
•
Χ
s
is a normal random variable that depends on partition losses inside the build-
ing, and therefore, depends on the frequency of operation.
As a reference, the following table gives estimates of signal loss for some RF barriers.
1
1. Rappaport, Theodore S.
Wireless Communications, Principles, and Practice
. Prentice Hall PTR, 1996.
Table 6-11
Average Signal Loss of Common Building Materials
Partition Type
Loss (dB)
Frequency (MHz)
Metal wall
26
815
Aluminum siding
20
815
Foil insulation
4
815
Cubicle walls
1.4
900
Concrete block wall
13
1300
Concrete floor
10
1300
Sheetrock
1 to 2
1300
Light machinery
3
1300
General machinery
7
1300
Heavy machinery
11
1300
Equipment racks
7
1300
Assembly line
6
1300
Ceiling duct
5
1300
Metal stairs
5
1300
