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LU failures

Viewing 11 posts - 1 through 11 (of 11 total)
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  • #53918 Reply
    Ram
    Guest

    Hi All,
    What are the factors that could lead to Location update failures. Previously we allowed national roaming for another operator and now we have withdrawn the facility. Now the LU rate is less within 90%. In what ways it can be improved.

    thanks,
    ram

    #53919 Reply
    pix
    Guest

    what do you mean by “LU rate” ? Do you mean the ratio of SDCCH allocated for location update / SDCCH allocated (LU + SMS + Call + SS + IMSI DETACH + …) ?

    Or do you mean the LU success rate ?
    How do you compute the success rate ? Nb of LU requests / LU accept ?

    If a LU is rejected, it is done by the HLR itself, either the MS is not allowed to be in this network, or the MS has been disconnected (NSS timer expiry “implicit detach”).

    Since you said that you disabled national roaming, when a MS tries to “IMSI ATTACH” on your network, it actually sends a LOCATION UPDATING REQUEST with the cause “IMSI ATTACH”.
    This IMSI ATTACH failure is therefore counted as a LOCATION UPDATE failure.

    In order to analyze this issue, you can simply perform a drivetest with a MS from another operator, in a zone that is not covered by this operator. See if this MS is attaching to your network or not.

    Regards,
    Pix

    #53920 Reply
    Ram
    Guest

    Thanx pix,
    We will arrange for a drive test in that region. Is there any procedure to reduce the number of IMSI attach requests from other operator. I mean, is there any way to inhibit them from performing the IMSI attach request.

    thanks,
    ram

    #53921 Reply
    Pix
    Guest

    Ram,

    I’m afraid there is not. Your network is certainly considered as a possible PLMN, as hard-coded in their SIM cards, so everytime their home PLMN is not reachable, they’ll try to attach to your network.

    But frankly, I don’t see why that’s a problem… The LU success rate is not a KPI, it should be analyzed accordingly to your situation.

    Unless it totally overloads your HLR, it doesn’t look like a problem…

    #53922 Reply
    yasu
    Guest

    Hello guys,

    in NSN, LU success rate formula;
    LU started / LU completed.

    From this formula, some BSCs having low LU success rate, % 70/80.

    And we have high SDCCH drops, 1.2 %.

    so my question;
    SDCCH drop is one of cause of LU failure?
    or high number of LU cause high SD drop as well??

    thanks

    #53923 Reply
    yasu
    Guest

    any comment?

    #53924 Reply
    Scott
    Guest

    Hi Pix,

    Is there anyway where we can stop the MS from performing IMSI Attach request.. As here we have aproblem where in Roam Free Borders the HPLMN Location MS can latch to the VPLMN Cell Site which needs to be controlled.

    cheers

    Scott

    #53925 Reply
    pix
    Guest

    yes, you can turn off the IMSI ATTACH (ATT = disable), such parameter is 3GPP-compliant, so all vendors should provide it.

    It means that no MS can perform IMSI attach, even the ones that belong to your PLMN ! It’s not critical if you just need to run some tests but on the long term it’s going to bother your subscribers.

    regards
    pix

    #53926 Reply
    Scott
    Guest

    Hi Pix,

    Yes..That would cause problem to the my home PLMN.. But my requirement is as part of long term can we turn off or control particular PLMN IMSI’s to not to latch to particular LAC ID’s of neibuoring PLMN. Is this possible ?

    cheers

    Scott

    #53927 Reply
    pix
    Guest

    scott,

    no, it is not possible. You have to ensure that your cells rxlev’s are stronger than the VPLMN’s cells. That’s a big game between operators at country border.. What you should do is inform the subscribers how to set their PLMN manually so their phone won’t camp on the other VPLMN.

    That requires some ad campaigns or some mails, I guess.

    Cheers
    pix

    #53928 Reply
    Sanjay
    Guest

    How IMSI attach succ rate can be increased

Viewing 11 posts - 1 through 11 (of 11 total)
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