Erlangs vs Kb/s

Eric, I think Erlang is a telecom traffic unit which works on circuit switching. One circuit used for 1 hour makes 1 erlang traffic. Circuit switching needs a dedicated channel (although it may use mutiplexing). Packet switching shares a circuit or channel. So here, a circuit is not dedicated to anyone. Moreover, packets can travel through alternate routes. Kb/s is a measure of data flow for packet switching. So erlang does not apply here in that sense.

Nil,
From what I’ve read,Erlang is measure of ‘occupancy’ so

Erlang = usage / capacity

So if you measured X kbps on a sig link, which was on a timeslot of capacity 64kbps then

Erlang = X/64

you may also want to additionally factor in a QoS measurement, so would never run them at above 0.8 erlang = 80% of 64 =~51k

Nil,

I’m looking at it from a GSM traffic point of view.The Qos or Gos (Grade of service) will ensure that if I have peaks in traffic there will be sufficient capacity available.Most suppliers recommend that you don’t dimension above 80% of the total capacity. In reality, if you have two signalling links you might might to consider redundancy, in that you dimension them upto 40% of their capacity.
So if one fails the other can handle the full load.
Hope this answers your question!

Radhakat Das,
I think you may be allocating too many channels for your systems if you assign 2 erlangs for 64kbps data rates. My primary reasoning is that the Rx direction is not nearly as loaded as the Tx direction. And also that you are not using the 64 kbps on the Rx or Tx side continuously. The traffic loading will most likely be less than 100%. As an example, data packets will be assigned an order in a particular channel based on service session duration, queueing, average packet length, service priority, etc… so the system tries to keep the channel occupied without having services wait too long before being serviced. But there is a good chance that the sytem will not have enough requests to keep this channel busy all the time. So when allocating erlangs for data at a specific data rate the channel usage has to be taken into consideration.
Nil

how to relate between GoS with Erlang.

Hi, great forum, Erlang is oriented to Voice therefore first step is to calculate how many channels you need to support 2.88 Erlang, my calculation gives 7 circuits (2.2 Erl @0.01).

One call using VOIP is 24 Kbps (depending in your codecs for compression), then Kbps could be:
24 Kbps* 7 = 168 Kps. Then based on this you can convert to Ethernet packets.

Comments or corrections are welcome