User's Manual Part 1

Designing a Fusion Wideband Solution
Page 82 InterReach Fusion Wideband Installation, Operation, and Reference Manual
© 2013 TE Connectivity Ltd D-620616-0-20 Rev H • TECP-77-044 Issue 7 • May 2013
ESTIMATINGRFCOVERAGE
Themaximumoutputpowerpercarrier(basedonthenumberandtypeofRFcarriersbeing
transmitted)andtheminimumacceptablereceivedpoweratthewirelessdevice(thatis,theRSSI
designgoal)essentiallyestablishtheRFdownlinkbudgetand,consequently,themaximum
allowablepathloss(APL)betweentheRAU’santennaandthewirelessdevice.Sincein‐building
systems,suchastheFusionWideband,aregenerallydownlink‐limited,thisapproachis
applicableinthemajorityofdeployments.
Figure19.
Determining APL between the Antenna and the Wireless Device
Equation1
Equation1isasfollows:
APL=(P–L
coax
+G)–RSSI
where:
• APL
=themaximumallowablepathlossindB
• P=thepower
percarriertransmittedbytheRAUindBm
• L
coax
=thecoaxialcablelossbetweentheRAUandpassiveantennaindB
• G=thegainofthepassiveanten
naindBi
CoaxialcableisusedtoconnecttheRAUtoanantenna.Table65listscoaxialcablelossforvarious
cablelengths.
Table65
. CoaxialCableLosses(L
coax
)
Length of Cable
(.195 in. diameter)
Loss at 850 MHz (dB) Loss at 1900 MHz (dB)
0.9 m (3 ft) 0.6 0.8
1.8 m (6 ft) 1.0 1.5
3.0 m (10 ft) 1.5 2.3
RAU
RSSI =
power at the
wireless device
Distance = d
G = Antenna Gain
P =
power per carrier
from the RAU
L
coax
= Coaxial cable loss