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 Trafc in a communication networkreers to the aggregate o all user

request being serviced by the network

 Telephone trafc means, number o

subscribers .trying to contact othersubscribers.

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Figure 1. Trafc Variationurve

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elated Terms and Topics on Telephone Traf

" Trafc #ngineering

 Telecommunications trafcengineering, teletrafc engineering, ortrafc engineering is the application o

trafc engineering theory totelecommunications.

"$usy %our

 The busy hour is de&ned as a period osi'ty consecutive minutes during which thetelephone trafc is the highest.

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"$usy %our alling !ate(t is de&ned as the average number o

calls per subscriber during the busy hour.

"%olding Time This is called holding time because duringthis time, the switches in the e'change areheld busy. The holding time per call consists

o two parts)1. *perating time+. onversation time

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" Trafc nit - The #rlang, # The unit o telephone trafc is called

ater #rlang, a anish mathematician, whopublished in 1/10 and 1/1 the &rst basicresults on the number o subscribers thatcan be served with a given number o

channels at a required 2uality o 3ervice4blocking probability5.

(t is de&ned as the product o thenumber o calls per busy hour and theaverage holding time per call measured inhours.

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"(n 63T7 architectures7etworks are handled as)

1. 8oss systems where calls that

cannot be handled are givenequipment busy tone or

+. 2ueuing systems where calls that

cannot be handled immediately arequeued."(n call centers

9 good e'ample o the use o

teletrafc theory in practice is in thedesign and management o a call center.

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equal to the product o themathematical e'pectation o thenumber o calls coming in per unit time

and the average time required or acall. (ntensity is measured in terms othe erlang, which is equal to the trafc

whose calls, i placed end to end, wouldkeep one channel continuouslyoccupied.

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Trafc Density

the trafc per time unit.

the unit usually employed are the 3and the busy hour

usually stated in terms o 3 per hour

4$% 3.5

e'press trafc in terms o busy hour#rlang 4$% #!85

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Trafc Rate

the busy hour trafc density per trafcsource 4subscriber line, selector, etc.5

7ote) there is a di:erence between

calling rate, which is calls per trafcsource, and trafc rate, which is density4$% 3, $% #!8, etc.5 per trafc source.

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Grade o Service 

measure o the probability, thatduring a speci&ed period o peaktrafc a call o:ered to a group o

trunks or circuits will ail on idlecircuit at the &rst attempt.

sually applied to the busy hour o

trafc.

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Full Availability Switches 

devices with lines and trunks

Limited Availability

not all the ree outlets in a switching systemcan be reached by inlets

the absence o ull availabilityCarried Trafc 

the volume o trafc actually carried by aswitch.

Oered Trafc 

the volume o trafc o:ered to a switch.

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9. Trafc ;easurements

 Trafc 2uantity Trafc (ntensity

all (ntensity

• Telephone Trafc alculations nits o Trafc (ntensity

 Trafc Flow or Trafc (ntensity

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 Trafc ;easurements Trafc 2uantity (t represent the total number o channel uses in

units o time.

 Trafc (ntensity 9lso called trafc load

9verage number o calls present during a periodo time

all (ntensitysed in estimating trafc loads on control

equipment where the duration o calls on thetrafc<carrying path is irrelevant

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 Telephone Trafc alculations

1. nits o Trafc (ntensity!rlan"

7amed ater anish ;athematician9gner =rarup #rlang

(nternational dimensionless unit o trafcintensity

*ne #rlang o trafc intensity on onetrafc circuit means continues occupancyo that cicuit

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Call#Second$CS%& Call#'inute& Call#(our$Ch% 9re units o trafc quantity representing the

occupation o a circuit or a second, minute, orhour

Century Call Second$CCS%nit o trafc intensity equal to 1>?@ o an

#rlang

=nown as %undred all<3econd4%35

!)uated *usy (our Call$!*(C% #uropean unit or trafc intensity equal to 1>?@

o an #rlang

+ !rlan" , -.Cmin

  , /-CCs

, /-

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+. Trafc Flow or Trafc(ntensity

Callin" Rate 9verage number o calls placed during the

busy hour

(oldin" Time uration o occupancy o a trafc path o

a call

Grade o Service*loc0in" 1robability

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3ample 6roblemalculate the trafc intensity in #rlang,

given the ollowing calling rate o holding

tme. 9. c A 1BBBcalls>hrC tA /B secs C 9A +D #!8

$. c A 1+BB calls>hrC t A +mins C 9A 0B #!8

 a. #$% A 9'?B#$% A DB #$%  b.

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!eerences)

http://www.daenotes.com/electronics/communication-system/telephone-trafc-trunking-principle#axzz1jQEo!t"

http://wireless.per.nl/reerence/chaptr$%/erlang/erlang.html

http://www.wikipedia.com