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Location update and external interferenc

Viewing 15 posts - 1 through 15 (of 19 total)
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  • #63796

    I have a question does external interference make the MS make a lot of location update? if yes and want to reduced it is recommended to add more time to T3212 .


    hi RF,

    very strong interference on the BCCH could force the MS to reselect another cell. And once in the new cell, it might eventually come back to the interfered cell. If cells belong to different LAC, then … LU is performed.

    But the amount of interference must be very bad to lead to such a situation.

    IMO, the effect of interference on LU is negligible.

    T3212 = 4 hours is a standard value, you can increase it a little bit and see the effect. Most probably the effects can only be seen at NSS level : more paging without response.



    Thank you for quick response.
    Just i have two comment
    How paging can be effect by increasing this timer and
    I see in my statistic that most of Channel request is going to location update is this not come from external interference .



    according to our vendors this timer T3212

    0 ~ 255
    (0: infinite and no need of location update; 1: 6 minutes; 2; 12 minutes ……255: 530 minutes)

    timer is one of the system control parameters.
    This parameter affects the overall service performance of the network and the utilization of the radio resource. For the area with higher traffic, the period could be bigger (for example 16 or 20 hours, even 25 hours); for the area with ordinary traffic, the value of T3212 could be smaller (for example 3 or 6 hours); for the area with extreme overload traffic, it is recommended to set T3212 as 0.



    t3212 forces the MS to do a LU periodically (every t3212).
    the point is that the VLR will clean its database from all MS which are “dead” (that did not perform a periodic LU).
    If MS doesn’t do the LU, then the VLR will assume the MS is “off” and not pageable. The VLR actually waits longer than t3212 (it is t_detach, i believe, a VLR parameter usually = 2*t3212)

    So by increasing t3212, more MS will be “dead” but not yet detected as such by the VLR. So paging will go on for those, and will not be answered. So paging response rate decreases. Not very important IMO, but some operators are monitoring this indicator.

    Interference do not cause fake LU specifically… In your case I would assume that the area is
    1/ rather empty, the number of calls is very low, the MS are mostly doing their LU once in a while. It looks like a lot of traffic, but it’s not that much
    2/ faulty MS is firing channel requests “LU” to your BTS
    3/ the area is in between two LACs and MS are jumping from one LAC to the other. Fix this by increasing your Cell Reselect Hysteresis parameter.

    To ensure it is not an external interferer, just assign a new BCCH frequency to this BTS. Choose an ARFCN far away from the one you were using. If LU are still going on, then it is not because of interferer.



    Can u explain ” So by increasing t3212, more MS will be “dead” but not yet detected as such by the VLR”
    The dead MS are switched off mobile or out of coverge ?
    why would you expect lot of dead mobile by increasing the timer?


    Thank you for the help


    hi sunny,

    when you increase t3212, you must also increase the t_detach timer in the VLR. Therefore the VLR takes more time to detect the “dead” ms (MS out of coverage or out of battery or turned off, etc)
    In average the ratio of “dead” ms in the VLR will increase because of this. I don’t know how to explain this… it seems logical to me.



    Got it


    pix and sunny

    you mean when the MS did not update his location for the network after T3212 time eg =6 hours (for example) the network will push the MS to upadte his llocation , in case it did not recive response from MS it will directly consider the MS in deattch case.

    is that right ??
    what about if the MS has incoming call and he did not update his loction to the network , the network will paging it by the last location update , it no paging reponse ??


    every t3212, the MS autonomously sends a LU.
    the network does not ask for anything.

    after a certain timer “t detach”, the VLR will detach the MS from the network, if no LU were received.

    if t3212 = 6hours, then t detach = 13hours for example.

    when there is a call, the Ms is paged normally by the network. At the end of the call, if t3212 expired during the call (how unlucky !), then a LU is performed immediately after the call.


    In my case I found the periodically location update timer is 174 min. (2.9 H) this in BSS conifguration side for all our BSCs , but as you know the BScs are covered diffeent area , is that normal , boz as i know this timer deponds on the area type ,,,

    from the other side from the core network side we have the vlr after 24H will delate the subs (purge sub.) , the absent subscriber error is very high in Sending route information

    and MT error

    could you help me



    Pix you tells that if the mobile turned off VLR takes more time to detach dead mobile. But as I know there is parameter named
    “IMSI Attach-Detach Allowed (ATT, Attach-Detach allowed)”. If you set ATT=1, when you switch off the mobile, it sends acknowladge message to VLR and HLR.

    So, I agree with your 2 examples (MS out of coverage or out of battery ) but not this one (turned off).



    in my case

    if 1— t3212 = 2.9 hours, then2— t detach = t(periodical timer in VLR) = 240min (large than T3213, so it is available if the T3213 is not successful)

    3—–purge timer = 24Hours

    any comment


    I have problem that my location update was bad 80% and suddenly raised to 93% and then back to almost the 80% what could be the reason and what parameter in NSS part may change and cause this problem .

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