User's Manual

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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(4πd
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