- This topic has 44 replies, 1 voice, and was last updated 12 years, 9 months ago by zvino.
30th May 2003 at 12:05 #35656StarGuest
I want to know when a subscriber make location update(periodic or boundary) meeting SDCCH blocking what will happen, whether the subscriber will continue make the location update or just try 1 time. Thanks.13th July 2003 at 10:19 #35657NguyenGuest
In normal case, the location update process is as follow:
MS -> BSS: CHANNEL REQUEST
BSS -> MS: IMMEDIATE ASSIGNMENT
MS -> BSS: LOCATION UPDATE REQUEST
BSS -> MS: LOCATION UPDATE ACCEPT
In the abnormal case, due to SDCCH congestion, the process will be:
MS -> BSS: CHANNEL REQUEST
BSS -> MS: IMMEDIATE ASSIGNMENT REJECT
In this case the location updating is not started. The IMMEDIATE ASSIGNMENT REJECT will indicate the value for the timer T3122. At the MS side, the timer T3122 will start and when this timer expires, the MS will makes another attempt for location updating.
However the total number of attempts will be limited by the “Attempt Counter”.
Brgds//10th September 2003 at 13:25 #35658MatiasGuest
I would like to know typical values of timer T3122 and maximum value of attempt counter. Is it true that high SDCCH blocking from counters in Location Area borders could be due to repeated blocked attempts? Is it reasonable to extend SDCCH resources acordingly in this particular case (i.e. LA border)?11th September 2003 at 01:55 #35659NguyenGuest
The timer T3122 is sometimes called wait indication parameter. There is no default value specified by the GSM recommendation for this timer, and I think it is depended on the hardware vendor. In the Motorola BSS system, the default value for this parameter is 5 seconds. I have no information about the attempt counter parameter.
You are true that in the LA border, it is reasonable to increase the SDCCH, bacause of the number of location updating attempt will be increase in this area.
Brgds11th September 2003 at 10:48 #35660MatiasGuest
What counter do operators use to detect blocking problems in SDCCH: blocking rate or congestion rate (%time in congestion?
Do they really want to overdimension SDCCH resources to carry peaks of LU traffic (p.ej. train/bus station, airport) that could be done no matter the delay or even performed in other cells? (note that a high blocking rate, possibly due to repeated LU attempts concentrated in time, does not necessarily mean bad call initiation blocking performance)
Wouldn´t congestion ratio be a better KPI to reflect call initiation problems(ideally uniformly distributed in time)?
Thanks.11th September 2003 at 19:32 #35661MatiasGuest
Hi Nguyen, I saw in another topic in the forum that you have built a tool to dimension SDCCH based on number of TRXs,Ratio of Location update to calls, Ratio of SMS to calls, Blocking probability for SDCCH, Blocking probability for TCH,…
Would it be possible to have it?
Thanks, br.11th September 2003 at 19:35 #35662MatiasGuest
My mail is firstname.lastname@example.org September 2003 at 02:34 #35663NguyenGuest
plz check yr mail for an attachment.12th September 2003 at 09:27 #35664UmreetGuest
This is Umreet..I had requested u to send me the tool to dimension SDCCH which u have mentioned in one of the forum.
I request u to kindly send me the same..
Thanks in anticipation
Umreet12th September 2003 at 09:29 #35665UmreetGuest
My Mail id is:
thanx n rgds12th September 2003 at 10:51 #35666MatiasGuest
I’ve read that Erlang-B model is commonly assumed as the model to dimension SDCCH during planning stage. Have you ever checked this a posteriori with the collected traffic and blocking counters? It seems that repeated SDCCH attempts during congestion periods give higher blocking rates than expected.
BR,13th September 2003 at 23:43 #35667alexGuest
Hi, Nguyen !
Could you send me you SDCCH dimensioning tool because several days ago I removed almost 300 extra SDCCHs in my network and now want to know if it was correct 🙂
I did’nt see “SDCCH channel congestion” on cells where I remove SDCCH but any way I want to check …
my email email@example.com
thnx in advance30th September 2003 at 02:12 #35668hermawanGuest
I want to know the formula to calculate the blocking of the SDCCH, and what cannal logic in GSM that influence by GPRS alocation Timeslot?9th October 2003 at 07:28 #35669ZamanGuest
Please send me the SDCCH dimensioning tool…………
My email ID is:
Thanks9th October 2003 at 16:53 #35670amberish trivediGuest
can u send me that sdcch dimensoning tool if u don’t mid
my email id is