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PX Eliezer704
Premium Member
join:2008-08-09
Hutt River

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PX Eliezer704

Premium Member

Remembering Danish phone traffic expert AK Erlang.


Agner Krarup Erlang of Denmark
.

The [Erlang] is a basic unit of telephone traffic.

We are coming up on the anniversary of Agner Krarup Erlang's death, 3rd February 1929, so this seemed a good time to honor him.

The Erlang unit is a statistical measure of the voice traffic density in a telecommunications system and it is widely used because, for any element in a telecommunications system, whether it is a landline, or uses cellular technology, it is necessary to be able to understand the traffic volume.

As a result it is helps to have a definition of the telecommunications traffic so that the volume can be quantified in a standard way and calculations can be made. Telecommunications network designers make great use of the Erlang to understand traffic patterns within a voice network and they use the figures to determine the capacity that is required in any area of the network....

....The Erlang is named after a Danish telephone engineer named A.K Erlang (Agner Krarup Erlang). He was born on 1st January 1878 and although he trained as a mathematician, he was the first person to investigate traffic and queuing theory in telephone circuits.

After receiving his MA, Erlang worked in a number of schools. However, Erlang was a member of the Danish Mathematician's Association (TBMI) and it was through this organization that Erlang met the Chief Engineer of the Copenhagen Telephone Company (CTC) and as a result, he went to work for them from 1908 for almost 20 years.

While he was at CTC, Erlang studied the loading on telephone circuits, looking at how many lines were required to provide an acceptable service without installing too much over-capacity that would cost the company money. There was a trade-off between cost and service level.

Erlang developed his theories over a number of years, and published several papers. He expressed his findings in mathematical forms so that they could be used to calculate the required level of capacity, and today the same basic equations are in widespread use..

In view of his ground-breaking work, the International Consultative Committee on Telephones and Telegraphs (CCITT) honoured him in 1946 by adopting the name "Erlang" for the basic unit of telephone traffic....

....Erlang basics

The Erlang unit is the basic measure of telecommunications traffic intensity representing continuous use of one circuit and it is given the symbol "E". It is effectively call intensity in call minutes per sixty minutes. In general the period of an hour is used, but it actually a dimensionless unit because the dimensions cancel out (i.e. minutes per minute).

The number of Erlangs is easy to deduce in a simple case. If a resource carries one Erlang, then this is equivalent to one continuous call over the period of an hour. Alternatively if two calls were in progress for fifty percent of the time, then this would also equal one Erlang (1E). Alternatively if a radio channel is used for fifty percent of the time carries a traffic level of half an Erlang (0.5E)

From this it can be seen that an Erlang, E, may be thought of as a use multiplier where 100% use is 1E, 200% is 2E, 50% use is 0.5E and so forth.

Interestingly for many years, AT&T and Bell Canada measured traffic in another unit called CCS, 100 call seconds. If figures in CCS are encountered then it is a simple conversion to change CCS to Erlangs. Simply divide the figure in CCS by 36 to obtain the figure in Erlangs.

»www.radio-electronics.co ··· rial.php
tbrummell2
join:2002-02-09
Ottawa, ON

tbrummell2

Member

Thanks for the reminder of telephony theory. I haven't used E's and CCS in 10 years, and was taught it 20 years ago. Eeeek! I'm getting old! LoL
engineerdan
join:2006-12-07
Washington, DC

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engineerdan to PX Eliezer704

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to PX Eliezer704
said by PX Eliezer704:

.

The [Erlang] is a basic unit of telephone traffic.

We are coming up on the anniversary of Agner Krarup Erlang's death, 3rd February 1929, so this seemed a good time to honor him.

It's good to have posted this a few days before Mr. Erlang's birthday. It'll give Google's logo artists a few days to come up with something truly memorable.