Telephony 4

Introduction Of Teletraffic Engineering Telecommunications traffic engineering ,  teletraffic engineering , or  traffic engineering  is the application of traffic engineering theory to  telecommunications . Teletraffic engineers use their knowledge of  statistics  including  queuing theory , the nature of traffic, their practical models, their measurements and  simulations  to make predictions and to plan telecommunication networks such as a  telephone network  or the  Internet . Traffic is defined as a total number of call passing through over a trunk.Channel is defined as a transmission medium.The field was created by the work of  A. K. Erlang  for  circuit-switched  networks .A good example of the use of teletraffic theory in practice is in the design and management of a  call center . Call centers use teletraffic theory to increase the efficiency of their services and overall profitability through calculating how many operators are really needed at each time of the day.Que

Call Intensity ·        Call Intensity,Y , defined as number of calls offered per unit time @ ratio of traffic intensity to call average duration. ·        Formula Y is:                                                                                         A- Traffic intensity s-     Average holding time for a call (unit in second)           Average Call Duration,S ·        For data, quantity that sent calculated in bit or byte. While transmission speed in second. ·        S is defined as a voice data transmission in second at one channel that have been used OR the average period of service calls. Call Intensity Example Question Given traffic intensity of 90E and holding time for a call is a 3    minutes. Find call intensity. Y = 90E/180s     = 90E x 3600s / 180s     = 324K / 180s     = 1800calls

DIFFERENCE BETWEEN ERLANG AND GRADE OF SERVICE Erlang Erlang is the unit of telephone call traffic. It is defined as average number of calls in progress at some time. Erlang equation is mentioned below. Erlang traffic measurements are carried out by wireless network designers to understand the voice traffic patterns in the network. This will help them derive how many lines will be needed between telephone system and PSTN central office(CO) or between the two cellular/wireless networks. Erlang A = C*h/T Where, C is average no. of call arrived during time interval T h is the average call holding time. In North America CCS(Call Seconds per hour) is used in place of Erlang. 1 Erlang = 36 CCS. Erlang Traffic models Following section mentions difference between Erlang B, Extended Erlang B and Erlang C. • Erlang B: It is used to derive number of lines needed when traffic in erlangs during busy hour is known. This traffic model is mostly used. It assumes that blocked calls are c

This is Agner Krarup Erlang Erlang     An Erlang is a unit of telecommucications traffic measurement.    An Erlang is defined as the average number of simultaneous calls on a system during one-        hour period.    Erlang defined as the traffic carried by a  group of trunks      In honor of Agner Krarup Erlang What is Erlang?      Erlang = 1 call hour / hour     1 Erlang = 1 hour ( 60 minutes) of traffic   Erlang = (calls/busy hour) x holding time                          Tips: units must be the same ! Erlang Example Question A subscriber makes 3 phone calls of 3 minutes, 4 minutes , and 2 minutes duration in 1 hours period. Calculate Minutes of traffic in the hour = number of calls x duration Minutes of traffic in the hour = (4min+3min+2min) Hours of traffic in the hour    = 9 minutes / 60 minutes Hours of traffic in the hour   = 0.15 Traffic of traffic in the hour  = 0.15 Erl

~ (CCS) A unit used (in North America) to quantify the total traffic running in a network. 1 CCS is 100 call-seconds. That means 1 CCS could be 2 calls of 50 seconds duration or 20 calls of 5 seconds duration. ~ Also known the hundred call second ~ 1 CCS = 100sec call    = 100sec x 1 min / 60 sec x 1 hour / 60 min    = 1 / 36 Erlang

Grade of Service (GoS) Video GoS is a measure of the probability that a percentage of the offered traffic will  be blocked or delayed. Grade of service is used to observe and measure how many calls are  offered, carried and lost in the system.     GoS is also defined as proportion of calls which are allowed to fail in busy hour due limitation or economic reasons of the amount of switching equipment.  The term GOS, B is defined as the ratio of lost traffic to offered traffic: B= Number of Call Lost /  Number of Call Offered or B=  Traffic  Lost / Traffic  Offered For more information:  https://en.wikipedia.org/wiki/Grade_of_service