User Manual

FiberDistributedAntennaSystem(FiberDAS)
43
Whatweseehereisthatifwesetthesystemupinthisfashionwewilldesensitizethebasestationwithabout5,5
dB.ThiscanbeokayifthebasestationcoverageisonlythroughtheFiber‐DASsystembutifthebasestationisalso
beingusedforout
doorcoverageitisnotgood.Weneedtochangethenetgaintoreflectthis.Ingeneralweshould
loweroursothatwedesensitizetheBTSonlyabout3dB.Thisvalueisagoodcompromiseandsimilartoaddinga
secondantennatothesamereceiverport(whichiskindofwha
twearedoingwiththeFiber‐DAS).
Herear
ethenewvalues:
Table 47
Chain NF Gain Noise Load
RU1
RU2
RU3
RU4
SumofNoiseLoad
BaseStation
Fiber‐DA
SNoiseLoad
TotalNo
iseintoBTS
Desensitization
Adjusted Noise Load
Asyoucanseeweshouldsetthesystemupwithanetgainofabout‐5dB.Goingbacktothesettingswehadbefore
whichwas:
Table 48 Example Link Budget
Unit/Component Gain/Loss (dB) Accumulated Gain/Loss (dB)
RemoteUn
it(RU)
Fiber‐Op
ticCable
FOI
POI
BIU
Coupler
Weonlynee
dtochangetheBIUsettingusingtheattenuatorsintheBIUtolowerthegainwith5dB.Thiswill
accomplishwhatweneedtodoandtheuplinkshouldthenbecommissioned.
2.8 -5.5 -2.2
3.2 -5.5 -1.8
3.8 -5.5 -1.2
2.6 -5.5 -2.4
4.1
4.0
4.1
7.1
-3.1
40 40
-10 30
20 50
-35 15
015
-15 0