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border country_high sd drop

  • This topic has 9 replies, 1 voice, and was last updated 12 years ago by pix.
Viewing 10 posts - 1 through 10 (of 10 total)
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  • #63678

    hi all
    can any one help me to find the reason about high sd drop in border of country?(eicsson)


    Poor coverage ? Fast moving mobiles ? Location update failures (taking too much time to complete).
    If radio conditions are good, then the easiest way is to perform an A interface trace or a drive test (the problem surely comes from location update).



    What can we do to improve? I have a big SOR problem which reflects LU failures and sdcch drops?


    Hi Pix
    u are right.but pls consider it is border between 2 country .is it some thing important which need to check as well or there is no differences?


    it is possible the registration (with the loc upd in the new country) takes too much time and the SDCCH is dropped.
    Or perhaps the network doesn’t reply at all, keeping the SDCCH alive until it drops.

    It is a difficult topic where I would really start a study by doing a drive test or a trace (because I have no experience about this specific problem).



    Hi All

    I’ve started facing same problem. Suddenly SD drop increased in our border sites. It has gone from 5500 to 19000 in BSC level.

    Not finding any reason. If i go through the breakdown of drop, I’m getting t200 failure & increased suddenly.

    What actually can happen in border area.
    So far i know a flood took place on the other side. SD attempt increased abnormally.

    Any idea ???


    Hi All,

    I have also experienced this problem on my network (also ericsson) and up to now we haven’t found a solution.

    My suspicion is that, subs in the neighbouring country are trying to register on my network. As to what will cause this, I do not know.

    In my case, it occurred on the borders to three different countries… ALL AT THE SAME TIME. Really spooky.

    Any help/contribution would be appreciated.



    if “alien” sites are down, then the subs will tend to reselect neighbour cells. But if none is available, then they will (wildly) look for a cell from a different PLMN (= yours).

    You can’t avoid this. The best for you would be to do a roaming agreement and accept those incoming visitors. As soon as their site is up, they will camp back on the home PLMN.

    (note : this scenario is just an assumption ! i’m not saying it is what’s happening.)


    This is an amazing story.

    I also suspect the problem might be coming from subs in the neighbouring country attempting to register on your network…but then I have a problem with this theory.

    During Cell Selection/Reselection, isn’t the MS supposed to select an “allowed” PLMN? If there is no “allowed” PLMN and the MS selects another PLMN(your PLMN in this case), it is supposed to go into “Limited Service” state, isn’t it? In this state is the MS allowed to request for a channel on a PLMN which is not “allowed”?

    I would suggest you visit the border of your country and buy a SIM card of the neighbouring operators and doing a test registration on your PLMN. If the MS is allocated an SDCCH, then you can conclude the problem is coming from the foreign MSs.



    yep, the MS can attempt a Location Update on any PLMN. And doing the LU requires a SDCCH.

    whether the PLMN is allowed or not, i’m not sure what’s the impact. But this has to be hard coded in the SIM, which is probably not the case.

    Don’t moan. ROAM. 😀

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