- This topic has 22 replies, 1 voice, and was last updated 1 year, 3 months ago by Harbi.
21st November 2007 at 08:56 #49784LatheefGuest
If a route which have 20 circuits carried 3.3 Erlangs in one hour.
How do i convert 3.3 Erlangs to minutes.?21st November 2007 at 09:23 #49785pixGuest
3.3 erlangs = 3.3 hours of cumulated time of traffic onto the system
3 hours = 180 minutes
0.3 hour = 20 minutes
3.3 hours = 200 minutes22nd November 2007 at 05:11 #49786latheefGuest
any specific formula to do this Erlnag to minute calculation.
If the hourly traffic has been read are you saying the traffice carrried on that particular is an accumulated figue?
Thanks22nd November 2007 at 09:06 #49787pixGuest
the erlang is the cumulated time of traffic carried in the channels of the observed system.
1 erlang = 60 minutes
2 erlang = 120 minutes
3 erlangs = 180 minutes
4 erlangs = 240 minutes
40 erlangs = 2,400 minutes
400 erlangs= 24,000 minutes
and so on… there is no formula.
you measure 3 erlangs between 9am and 10am, it meands that there were 180 minutes of usage of your system at that hour.22nd November 2007 at 12:03 #49788ArunGuest
Does that one hour include the unsuccessful calls also or is the erlang calculated only for successful calls.
Arun22nd November 2007 at 21:53 #49789pixGuest
erlang is the amount of traffic really carried ! does an unsuccessful call put traffic on a carrier ?
– yes, on a SDCCH –> therefore unsuccesfull call increases the amount of SDCCH erlangs.
– no, not on TCH –> therefore the TCH erlangs are not impacted by unsuccesful calls.23rd November 2007 at 05:32 #49790ArunGuest
Thx for clarifying the doubt.
Arun23rd November 2007 at 07:11 #49791scorGuest
IM into OMC Side.
What is the ratio between the TCH Erlangs & SDCCH Erlangs . Ideally the SDCCH Erlangs should be on the higher side. right
And the TCH Erlangs does capture the missed calls
Thanks23rd November 2007 at 08:38 #49792pixGuest
sdcch traffic is about 10 times smaller than tch traffic (approx.)
unsuccessful calls (mean there was a failure during the call setup) do not use a TCH carrier. The failure occurs while they are on the sdcch channel. therefore they simply cannot be counted in the tch traffic.
if the failure occurs after the callsetup, then it is called a call drop. A call which is dropped occupies a tch carrier for a while, therefore it is counted in the tch erlang.28th November 2007 at 12:13 #49793scorGuest
Is the same calculation holds good when we apply half rate erlang also.
Thanks28th November 2007 at 19:55 #49794pixGuest
of course 🙂 if you activate HR at 60% traffic load on a cell with 30 TS, the actual number of carriers in your cell is :
(60% of 30) + (40% of 30)*2
= 20 + 10*2 = 40 carriers
you can compute your capacity based on this input.
Pix8th January 2009 at 15:21 #49795CplusGuest
I would like to ask you a question.. I hope there is someone is able to help me thanks. .the question is :
Why do we use Erlang B tables and explain the reason of the 10 times more bandwidth than the average traffic..
thanks in advance…8th January 2009 at 19:57 #49796PixGuest
I assume you mean the number of channels compared to the number of erlangs?
6 channels can carry only 2.3 erlangs (which means that only 2.3 channels are busy during one hour, in average, but that’s enough to get 2% congestion), and so on?
Well, the reason is because the traffic has a random rate of arrivals, and you want to keep the probability of “1 call incoming while 6 are already engaged” as low as possible (below 2%).
Pix9th January 2009 at 06:09 #49797cplusGuest
Dear Pix, is that last answer for my question ? Because i have doubt whether is for my question or not. Thank u very much…12th January 2009 at 09:37 #49798pixGuest
… yes, that was for you, Cplus.
I’m afraid my answer does not answer your question???