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# Interpretation Of Erlang-B

Viewing 7 posts - 1 through 7 (of 7 total)
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• #38693
Sapat
Guest

Hi ,

If according to Erlang-B table 87 Erlangs is for say the load for 99 carriers With a 2% gos.
Does this mean

1. I am supposed to give 99 carriers which can handle a maximum of 87erlangs with 2% GOS.My system will through without blocking 87 Erlangs of trafiic in the busiest hour and if offered more it will dropwith a probability of 0.02.
(or)
2.Even if i give 99 carriers,My system will accept 87erlangs of traffic but it actually allows a traffic of(1-0.02)*87=85.26 Erlangs only.

Any one Kindly explain me the right interpretation..

Regards,
SapatHi ,

If according to Erlang-B table 87 Erlangs is for say the load for 99 carriers With a 2% gos.
Does this mean

1. I am supposed to give 99 carriers which can handle a maximum of 87erlangs with 2% GOS.My system will through without blocking 87 Erlangs of trafiic in the busiest hour and if offered more it will dropwith a probability of 0.02.
(or)
2.Even if i give 99 carriers,My system will accept 87erlangs of traffic but it actually allows a traffic of(1-0.02)*87=85.26 Erlangs only.

Any one Kindly explain me the right interpretation..

Regards,
Sapat

#38694
DMCK
Guest

Your system will actually carry up to 99 erlangs maximum (1 call per channel), but it will carry 87E with 2%gos. GOS above 87E (up to 99E) will have a higher failure rate (lessor GOS)

#38695
Sapat
Guest

Thanks….

#38696
Akshay
Guest

The situation which you have described is that suppose the offered traffic is 87 erlangs. now from the erlangB table, to handle that traffic(87 erl) at 2% GOS we need 99 channels.
now if the OFFERED traffic is 87 erl that DOES NOT means that system will not block in busiest hour.even if offerd traffic is LESS than 87erl say 60ERL still the system can block because may be at a particular point of time there may be no free channel.GOS is a probability of finding ‘n’ channels busy.
consider a situation, where offered traffic is 103 ERLANGS with GOS=10% that too require 99 channels as required for 87erl with gos2% from erlangb table.
but i dont think system can carry more than 99 erlangs.

#38697
Sapat
Guest

Hi Arun,

Thanks for that. Let me try to put it again what i understood from ur explaination.

GOS is just a statistical figure. Erlang-B just says that GOS will be as low as 2% with offering 99 carriers and when my traffic load on an average is 87erl.

If my traffic load is higher than 87erl ,setup failure is MORE LIKELY to happen than when my traffic load was 87erl or less.

It does not necessarily mean there has to be more setup faillures but it just means that the probability or chance of setup failure rises.

I guess i got it right this time…

Regds,
Sapat

#38698
Akshay
Guest

hi sapat,

my name is Akshay not Arun
anyway,i think you got it perfectly right.
but i want to stress when offered traffic is more than 99Erl say 103 ERLANGS with GOS=10%. now from erlangB table that require 99 channels.
but think how 99 channels can support 103 erlangs.
explore an appropriate reason.

I=Q*T/3600
I=traffic intensity
Suppose holding time is 1hr
so Q=max 99
I=99*3600/3600 =99erl,and from erlangB table 103erl.how? try to find out.

#38699
Vijay Sharma
Guest

Akshay, Here Blocked erlang is also included that’s why it is going more than 99.

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