User's Manual Part 1

Link Budget Analysis
InterReach Fusion Wideband Installation, Operation, and Reference Manual Page 89
D-620616-0-20 Rev H • TECP-77-044 Issue 7 • May 2013 © 2013 TE Connectivity Ltd.
LINKBUDGETANALYSIS
AlinkbudgetisamethodicalwaytoaccountforthegainsandlossesinanRFsystemsothatthe
qualityofcoveragecanbepredicted.Theendresultcanoftenbestatedasa“designgoal”inwhich
thecoverageisdeterminedbythemaximumdistancefromeachRAUbeforethesignalstrength
fallsbeneaththatgoal.
OnekeyfeatureofthelinkbudgetisthemaximumpowerpercarrierexplainedinSecti
on6.3.
Whilethemaximumpowerpercarrierisimportantasfarasemissionsandsignalquality
requirementsareconcerned,itiscriticalthatthemaximumsignalintotheMainHubneverexceed
1W(+30dBm).CompositepowerlevelsabovethislimitwillcausedamagetotheMainHub.
CAUTION! Exceedingthemaximuminputpowerof1W(+30dBm)couldcausepermanentdamagetothe
MainHub.
NOTE: VisittheTEcust
omerportalfortheon‐lineLinkBudgetTool;see“TECustomerPortal”onpage3.
ElementsofaLinkBudgetforNarrowbandStandards
Thelinkbudgetrepresentsatypicalcalculationthatmightbeusedtodeterminehowmuchpath
losscanbeaffordedinaFusionWidebanddesign.Thislinkbudgetanalyzesboththedownlink
anduplinkpaths.Formostconfigurations,thedownlinkrequireslowerpathlossandistherefore
thelimitingfactorinthesystemdesign.Itisforthisreasonthatapredetermined“designgoal”for
thedownlinkissufficienttopredictcoveragedistance.
Thelinkbudgetisorganizedina
simplemanner:thetransmittedpoweriscalculated,theairlink
lossesduetofadingandbodylossaresummed,andthereceiversensitivity(minimumlevela
signalcanbereceivedforacceptablecallquality)iscalculated.Themaximumallowablepathloss
(indB)isthedifferencebetweenthetransmittedpower,lesstheairlinklosses,andthereceiver
sensitivity.Fromthepathloss,themaximumcoveragedistancecanbeestimatedusingthepath
lossformulapresentedinSection6.5.1.
Table76onpage90
provideslinkbudgetconsiderationsfornarrowbandsystems.