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SDCCH Blocking & Location update

Viewing 15 posts - 1 through 15 (of 45 total)
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  • #35656 Reply
    Star
    Guest

    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.

    #35657 Reply
    Nguyen
    Guest

    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//

    #35658 Reply
    Matias
    Guest

    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)?

    #35659 Reply
    Nguyen
    Guest

    Hi Matias,

    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.

    Brgds

    #35660 Reply
    Matias
    Guest

    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.

    #35661 Reply
    Matias
    Guest

    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.

    #35662 Reply
    Matias
    Guest

    My mail is mtoril@ic.uma.es

    #35663 Reply
    Nguyen
    Guest

    HI,
    plz check yr mail for an attachment.

    #35664 Reply
    Umreet
    Guest

    Hi Nguyen

    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
    Rgds
    Umreet

    #35665 Reply
    Umreet
    Guest

    My Mail id is:

    umreet2003@yahoo.com

    thanx n rgds

    #35666 Reply
    Matias
    Guest

    Hi Nguyen,

    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,

    #35667 Reply
    alex
    Guest

    To Nguyen:
    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 shelupinin@nwgsm.ru
    thnx in advance

    #35668 Reply
    hermawan
    Guest

    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?

    #35669 Reply
    Zaman
    Guest

    Hi
    All there,
    Please send me the SDCCH dimensioning tool…………

    My email ID is:

    sh_kamu@hotmail.com

    Thanks

    #35670 Reply
    amberish trivedi
    Guest

    hi Nguyen
    can u send me that sdcch dimensoning tool if u don’t mid
    my email id is
    amber81@rediffmail.com

    bye

Viewing 15 posts - 1 through 15 (of 45 total)
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