- This topic has 180 replies, 1 voice, and was last updated 13 years, 8 months ago by kishor.
23rd March 2004 at 17:05 #32952ErikGuest
First of all, i am most probably younger in this field than a few other posters on this board, so excuse me -and please explain me- if i am wrong.
You are talking about holding time and call time.
holding time is about signalling (call setup) and should be around 1 or 2 seconds in a GSM network.
Call time is about the call in itself, the conversation between people and can last for a while (70 seconds in average for the same GSM network).
Are you doing (on purpose or not) some comparison between SDCCH and TCH traffic?25th March 2004 at 19:11 #32953ScotGuest
I am taliking from Switch point of View.
I think this will be giving clear Picture.For a call….
Actual Holding Time :- Time between ISUP-IAM message and ISUP-RLC Message.
Act. Call Time:- Time duration between ISUP-ANM and REL Messages.
What do you think guys ?
What abt in AIR Iterface ?
Rgds29th April 2004 at 04:41 #32954davidtGuest
Bear in mind that Erlang B is theory.
For example a long term average 2% blocking in a cell can mean 0% for 4 days then 10% on Friday!
You will also find that blocking in low capacity cells doesn’t follow Erlang B (or Erlang C) – why? because it’s not random. An extreme example, say, in a conference hall, everone will try make a call at the end of the presentation. So you get blocking even though the average traffic is much lower than what Erlang B predicts.
So, be-aware of using Erlang B for capacity planning on small numbers of circuits.29th April 2004 at 15:21 #32955VijayGuest
Hi Davidt, If i’m not wrong then the capacity planning always consider Busy hour traffic. If yes then your example does not fit here.
Regards1st May 2004 at 20:25 #32956davidtGuest
It depends what you mean by busy hour… Typically, you would average BH traffic over a few days to decide what ‘weekly’ BH traffic (for dimensioning & projecting purposes) is… Some enlightened operators even use ‘bouncing busy hour’ to dimension resources.
If you don’t average, then you end up building capacity for the peak-of-peaks and dimensioning for non-typical spikes in demand. Which means your congestion is unecessarily low, but more importantly, you’ve got excessive network capacity (transcievers, transmission links, line cards, switching capcity, trunks etc) that only get used for about 72 seconds a week (if you have 2% blocking for the BH).
In India, as I understand it, with the huge increases in subscribers/traffic, you’d be well advised to ignore Erlang tables and put a load of capacity in anyway – it’ll save you having to go back 2 weeks later and add new radios!
Erlang is still theory and nobody told the callers they have to call with a Poisson distribution and not retry if they don’t get through…20th May 2004 at 15:50 #32957LouLouGuest
Mobile users in a certain GSM cell generate 700 calls per hour. Furthermore users
in this cell’s coverage area receive 1000 calls per hour while calls are handed over
from neighbouring cells in to this cell at a rate, 300 calls per hour. Assuming that all
calls (handover and new) have an average call length of 3 minutes, what is the
bandwidth required in this cell to support all calls at a GoS blocking probability of
1%. (Assume that the handover traffic from this cell to any of the neighbouring cells
is negligible.)20th May 2004 at 20:35 #32958Vijay SharmaGuest
Hi Loulou, to cater 100 erlang with 1% GOS u need 118 TCH.21st May 2004 at 12:14 #32959LouLouGuest
Thank you Vijay Sharma
but could you inform me how can i find the realtion between the channel whicj i have and the bandwidth which i have to find ?24th May 2004 at 03:53 #32960DEMEGuest
i m looking for a programm which look the number organ(n) in the erlang B24th May 2004 at 10:09 #32961RosyGuest
When dimensioning trunks using erlang-B formula, should the “maximum busy hour” during the observation period be used or a “busy hour averaged for the individual busy hours of each day” ?23rd July 2004 at 08:13 #32962Abhishek RanjanGuest
Hi! can u let me know abt design parameters. for example.-
mobile subscribers- 12650
fixed wireless – 8433
erlangs – 865 (How ?)
cell sites with 2C – 18
Erlangs built -2052 (how ?)
%ge buffer – 138 (wat does this mean?)
erlang/carrier – 48
tell me abt this design ???23rd July 2004 at 09:54 #32963SapatGuest
“Wireless: Principles and Practices” by Rappaport is a good one.29th July 2004 at 08:38 #32964ErikGuest
[Quote]’bouncing busy hour'[/Quote]
Hi all. Davidt, what do you mean by “bouncing BH”? Is it some kind of averaging? for example, taking the 3 busiest hours in the week? or taking into account the weekly BH over a few weeks (in order to discard “special events” congestion?
Thanks in advance and good day7th August 2004 at 06:39 #32965PavenGuest
Why don’t have Erlang A?
can you explain me?3rd September 2004 at 15:38 #32966DeepakGuest
Can you tell me the difference between LSR/QSR/TRD in traffic ?