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ThispagewassetupforthoseneedingtoperformroughcalculationsonresourcemanagementusingErlangBandErlangCcalculations.ThisworksheetusestheErlangBandErlangCequationstocalculatetheappropriategradeofservice(GOS).Entereachoftheparameters,thenpressthe"Calculate"buttonatthebottomofeachsection.

CalculatingErlangBBlockingProbabilityInthissection,youneedtoentertheofferedloadtothesystem,whichistypicallydenoted"A",andismeasuredinerlangs.Youalsoneedtoenterthenumberofavailablechannelsinthesystem.Forexample,youmighthaveacellularsysteminwhichonetowerprovides27channels.Ifthesystemishandling200calls/hour,andeachcalllasts6minutes,thiswouldcorrespondtoanofferedloadof(200calls/hour)*(1hour/60minutes)*(6minutes/call)=20erlangs.Wecouldthenpluginthevalueof"20"(fortheofferedload)intothefirstbox,andthevalueof27(forthenumberofavailablechannels)intothesecondbox,thenpress"CalculateBlockingProbability".Thiswouldgiveusananswerof0.0268.Thismeansthattheprobabilityofachannelbeingblockedforanyparticularcallerwouldbe0.0268,or2.68%.

OfferedLoad(A,inerlangs):NumberofChannels(C):

CalculateBlockingProbability

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CalculatingErlangBOfferedLoadInthissection,youneedtoenterthedesiredgradeofservice(GOS)forthesystemandthenumberofavailablechannels(C).Thegradeofservice(GOS)isnothingmorethantheprobabilityofacallbeingblockedforagivenofferedloadaswellasthenumberofavailablechannels.Thisscriptwillcalculatetheofferedloadwhichprovidesthegradeofservice,giventhenumberofavailablechannels.Forexample,youmighthaveacellularsysteminwhichonetowerprovides43channels.Ifthedesiredgradeofserviceis0.02,wecouldthenpluginthevalueof"0.02"(forthegradeofservice)intothefirstbox,andthevalueof43(forthenumberofavailablechannels)intothesecondbox,thenpress"CalculateOfferedLoad".Thiswouldgiveusananswerof33.758.Thismeansthatasystemwith43channelswishingtoprovidea0.02gradeofservice(or2%blockingprobability)wouldbeabletohandle33.758erlangsofofferedload.Iftheofferedloadincreasesbeyondthis,thenthegradeofservice,meaningtheblockingprobability,wouldrapidlyincrease.

DesiredGradeofService(GOS): NOTE:Thegradeofserviceor"GOS"isnothingmorethantheblockingprobabilityforaparticularsystem.NumberofChannels(C):

CalculateOfferedLoadforBlocking

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CalculatingErlangCDelayProbabilityThissectioncalculatestheprobabilitythatacallwillbedelayedbeforeitisserviced.ThisisPr(Delay>0).Youneedtoentertheamountofofferedloadtothesystem,inerlangs,aswellasthenumberofavailablechannels.Thisscriptwillthencalculatetheprobabilityofadelayoccurringgiventhesetwoparameters.Forexample,considerasystemwithanofferedloadof15erlangsandwith25availablechannels.Plugin"15"(theofferedload)intothefirstboxand"25"(thenumberofavailablechannels)intothesecondbox.Thenpress"CalculateDelayProbability".Thiswouldprovideaprobabilitythatthedelayisgreaterthan0of0.01243.

OfferedLoad(A,inerlangs):NumberofChannels(C):

CalculateDelayProbability

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CalculatingErlangCOfferedLoad

2/24/2015 ErlangCalculator

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Thissectioncalculatestheofferedloadthatcanhandle,givenagradeofservice(theprobabilitythatacallwillbedelayed)andanavailablenumberofchannels.Forexample,considerasystemwithagradeofservice(probabilityofdelay)of0.035and37availablechannels.Plugin"0.035"(thegradeofservice)intothefirstboxand"37"(thenumberofavailablechannels)intothesecondbox.Thenpress"CalculateOfferedLoadforDelay".Thiswouldprovideanofferedloadof26.437929erlangs.Thismeansthatthesystem,with37availablechannels,canhandleupto26.437929erlangsoftrafficbeforetheprobabilityofadelayoccuringrisesabove0.035.

GradeofService(GOS):NumberofAvailableChannels(C):

CalculateOfferedLoadforDelay

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