# ERLANG to Mbps conversion

#1

Hello dear experts.

How can we convert Voice Traffic/Video Traffic from Erlang to Kbps/Mbps and vice versa?

Is there some direct conversion model or not?

Scenario: 2G/3G Voice and Video on Um/UU interface.

Definition:

Erlang - telecommunications traffic measurement unit, it was named in honour of Danish mathematician A. K. Erlang, who developed telecommunications traffic theory. An Erlang represents the continuous use of one voice path. In practice, it is used to describe the total traffic volume of one hour.
When you have telephone call during half an hour and then idle another half an hour you produce 0.5 erlang telecom traffic. When you and your friend simultaneously call someone and talk during one hour, your total traffic load will be 2 erlangs

Kbps - stands for kilobits per second (thousands of bits per second) and is a measure of bandwidth (the amount of data that can flow in a given time) on a data transmission medium.

#2

I have this question too. I was wondering too if it is possible to convert figures from Erlangs into Megabits per Second.

If is there a specific formula which is used or do you divde by a cetain factor.

#3

Erlang is offered load (traffic intensity) = mean arrival rate * mean service time (or holding time)

It is a dimensionless (unitless) quantity.

It seems strange to try to convert a dimensionless quantity into dimension Mbps.

#4

I think in UMTS we have:

Traffic (erl)*12.2 kbit/sec.*3600/8 = Kbyte
12.2 AMR bit rate

If video:
Erlang*64 k bit/sec *3600/8 Kbytes

#5

There is no direct calculation for converting Data Traffic to voice traffic or vise versa.

All this calculation found in Internet is for Voice over IP or simple term when channels/TC are very fixed ie 1 or 2 ch/TC, may ch having capacity to deliver 64 Kbps, can calculate the erlang to Kbps.
but when throughput is depend on, dynamically used Time slot and depend on request of Terminal.

#6

For the above scenario (2G/3G Voice and Video on Um/UU interface) should we take 12.2 Kbps & 3G Video 64Kbps while calculating for GB conversion, or should it be the double: instead of 12.2 Kbps it it should 12.2*2=24.4 Kbps (UL& DL combined)?

#7

Downlink and uplink are using different “dimensions” (frequencies), so you can’t add them up.

It’s like trying to add time to space.

#8

Thank you all for the answers, but some doubts still remain:

1. Whats is the difference for Erlang value and MB value in data units.

2. If the Erlang is a unit of measurement of “intensity” of voice traffic, does it takes other data also?

#9

Traffic (volume) = Traffic (Erlang) * 3600 * Bearer BR * AF

Bearer BR = Channel Bit Rate
AF = Activity Factor

For voice services most vendors recommend to use 0.6
For data services most vendors recommend to use 1

#10

What if I need to compare the voice traffic volume on the GSM network with the voice traffic volume on a VoLTE network.

Is there any way to compare those different dimensions?

I know there are no erlangs in VoLTE but kpbs instead, but perhaps there is a formula that can convert those kbps to some kind of erlang equivalence in order to make comparisons.

#11

You can calculate an Erlang equivalent for VoLTE quite easily.

For Huawei it is L.E-RAB.SessionTime.QCI1/3600 .

Session time above is measured in seconds, hence dividing by 3600 (secs in an hour). So if you held a VoLTE call for one hour, session time would be 3600s and hence our formula would give you 1 erlang (one “circuit” held for one hour).