User's Manual

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D-620616-0-20 Rev C CONFIDENTIAL
Estimating RF Coverage
6.5.1 Path Loss Equation
In-building path loss obeys the distance power law
1
in equation (2):
PL = 20log
10
(4πd
0
f/c) + 10nlog
10
(d/d
0
) + Χ
s
(2)
where:
• PL is the path loss at a distance, d, from the antenna
• d = the distance expressed in meters
•d
0
= free-space path loss distance in meters
• f = the operating frequency in Hertz.
• c = the speed of light in a vacuum (3.0 × 10
8
m/sec).
• n = the path loss exponent and depends on the building “clutter” and frequency
of operation
•
Χ
s
= a normal random variable that depends on partition material and geome-
tries inside the building and is accounted for by the log-normal fade margin
used in the downlink RSSI design goal calculation
As a reference, Table 6-11 provides 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