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Dramatic LU increase

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  • #60546

    Hi, everybody!
    I would like to ask for your help or advice.
    In my network there is small problem with Location updates and SDCCH MHT. Stuacion is like this:
    Somewere in middle of LAC there sometimes at nigth appears large amount of LU (from 100 LU/hour to 1500 lu/h) and SDCCH MHT increases from 5-6 sec to 60-120 sec. Situacion like this hold for 5-6 hours and then everything normalise again. Other KPIs are OK, no call drop, SDCCH drop, CSSR decrease, no interference. The problem is not on one location and appears not frequently: at one nigth there are problem with one place, other night with other in another BSC, MSC and in the other end of country. No airports, country borders or other places that could generate LU are near. Till this moment we can’t find what generates this SDCCH traffic because of this random appearence and at nigth.
    PS. Vendor is Siemens BR10
    PPS. Sorry for my English I am not using it as often as I should 🙂
    Thanks in advance!


    Hi m121,

    If you have the resources to do so, try to perform an A interface trace to understand who is performing the LU (which IMSI’s ?).

    I experienced a situation where the subscribers froma different operators (but same country) were trying to attach during the night, because their own PLMN was down for a while.

    Your competitor is perhaps performing some network upgrade, which cuts the BTS’s in some areas during the night.

    SDCCH MHT of 60 to 120 seconds is a little strange though. Here again, an A interface trace could help you understand the matter. Is there anyone in your MSC that could provide you with some info ?



    Thanks pix for your replay.
    Yes A interface tracing would give us the good amount of necesery information but problem is that we dont know when and where problem will occur. Sometimes its weeks without problems but sometimes its appears for few nigth in a row and till this moment we could catch only one case where clone sim was involved but in that case MHT stayed normal.
    but your idea involving concurent network is interesting. I will try to check it out.

Viewing 3 posts - 1 through 3 (of 3 total)
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