- This topic has 124 replies, 1 voice, and was last updated 1 year, 5 months ago by Althaf.
27th September 2005 at 07:14 #33405H.S chayaGuest
What is traffic take up?> Where can I got full details on this?.2nd October 2005 at 05:15 #33406VARUN TIWARIGuest
Dear Friend/ Fellows
Can you tell me Details about GOS?
Please send me Erlang B Formula In detail? How can be calculated the erlanb if we have N nos. of channels?
what is formula for SWITCH capacity?
Thanks.20th October 2005 at 05:49 #33407sridharanGuest
i know the definition of erlang.and i see the erlang table.I dont know exact meening of erlang table. what is erlang table? If anybody know please help me.7th November 2005 at 06:33 #33408akGuest
any idea ’bout ASR.
i know that it is signal ratio but what is it exactly.i mean how can we express it.22nd November 2005 at 08:08 #33409nanaGuest
I am nana. I have a problem about switching design
course. The problem is to design telephone central Which is
serve 1000 subscribers with calling rate 0.02 erlang,
interoffice connection 10%,and using PCM30. Please give me the hint to solve it,
especially about the interoffice connection. What does
it mean? I am sorry if there are many mistakes in my
words. Thank you very much.1st December 2005 at 14:22 #33410CerebrumGuest
Dear, akhtar nawaz!
If you find the previosly mentioned formula for too complicated, there is another way to compute the Erlang B formula. If you can use MS Excel the solution is Poisson function:
=(Poisson(,,False))/(Poisson(,,True)). There is and another method but it is more complicated.1st December 2005 at 14:25 #33411CerebrumGuest
Sorry but that system have changed the original message. The full syntax is:
=(Poisson(lines,traffic intensity,False))/(Poisson(lines,traffic intensity,True)). There is and another method but it is more complicated.1st December 2005 at 14:33 #33412CerebrumGuest
I think that interoffice means your subscribers will make only 10% of their calls out of the exchange(switch) you are designing. That is equal to:
1000(subscribers)x0.02(Erl)x10%=2 Erl. Only 2Erl will be yor outgoing traffic, internall traffic will be 18Erl. The other case is just the oposite.12th December 2005 at 11:46 #33413MoawiaGuest
Any info about the dimensioning of MGW13th December 2005 at 16:44 #33414MoawiaGuest
Anyone has info about voice quality testing14th December 2005 at 10:49 #33415BokoGuest
There are a couple of vendors which have equipment for speech quality testing. I will mention QVoice by ASCOM and SwissQual (which are former employees of ASCOM as I know). In the ITU there are several standards for testing but in the end everithing is mapped to MOS (mean oppinion score) scale (bad, poor, fair, good, excellent). We are using QVoice and they have 3 different algorithms – PACE, PACE-TA and PESQ. They all map to MOS scale with certain probability.
If you need something more specific let me know.
Regards14th December 2005 at 16:17 #33416MoawiaGuest
Thanks Boko, Can you measure MOS with these equipment and is the emulation accurate and what to do to be able to make sure it is accurate.
Can the eqt also emulate golden ear.15th December 2005 at 08:39 #33417BokoGuest
As I know the MOS scale is subjective and is prepared by ITU based on thousands of people listenning to samples. These vendors develop their own algorithms which map these samples to the MOS scale. They are quite aquarate. These speech samples are specially designed for different languages and contain male and female voices and etc. Then the reference sample is send from the one end (ex. MS) to the other (ex. ISDN) and then again compared with the reference. According to the algorithm they are maped from 1 (bad) to 5 (excellent). For example if I remember the highest possible value with ISDN to ISDN is is 4.2 and GSM EFR to ISDN around 3.9.
What do you mean with golden ear?7th February 2006 at 10:03 #33418ASHISHGuest
WHAT IS MEANING OF TRAFFIC IN ERLONG .8th February 2006 at 07:24 #33419CerebrumGuest
Definition of Traffic Intensity: The instantaneous traffic intensity in a pool of resources
is the number of busy resources at a given instant of time.
a = λ·T
λ = number of carried connections per time unit (arrival rate, call rate)
T = mean duration of a connection or holding time
• In a local switch the number of calls in an hour is 1800
• The mean holding time of a call is 3 min
a = 1800 x 3 / 60 = 90 erlang
Typical traffic intensities per a single source are (fraction of time they are being used)
− private subscriber 0.01 – 0.04 erlang
− business subscriber 0.03 – 0.06 erlang
− mobile phone 0.03 erlang
− PBX 0.1 – 0.6 erlang
− coin operated phone 0.07 erlang
A load of 90 erlang is created by a population of some 2250 – 9000 private subscribers.