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TMSI reallocation for LU Req intra MSC

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  • #68652 Reply
    SANE
    Guest

    Dear,
    About interworking NSS HUAWEI and BSS ALCATEL, one MS was in LAC(1) CellID (A) with TMSI(1), and few seconds later move to LAC(2) CellID (B) with TMSI(2).
    Unfortunately, the paging was sent to LAC(1) CellID (A) with TMSI(1) for a MT Call attempted after changing location.
    Then, A-party received an announcement “MS is not reachable”.
    Could you tell me the possible causes ?
    If TMSI reallocation when MS moves from one LAC to another is a normal behavior ?
    Best regards

    #68653 Reply
    pix
    Guest

    hi sane,

    yes it is a usual operation during LAU.

    to reduce those radio ping pongs between LAC, you could increase the Cell Reselect Hysteresis (CRH) up to 16dB on both cells.

    Your scenario is quite extreme. The duration of a LAU is so short that it’s really bad luck if the MS is changing LAC while NSS is trying to page it. It’s really a matter of few seconds.
    The only thing is to avoid ping pong LAU, for sure.
    CRH is a good thing. Try also increase TO and PT (temp offset, penalty time), to values 4 (40dB) and 3 (40s) for example, that’s enough to avoid stupid reselections.

    Regards

    pix

    #68654 Reply
    Agha
    Guest

    Hi Pix,
    Thanks for ur reply:
    “The duration of a LAU is so short that it’s really bad luck if the MS is changing LAC while NSS is trying to page it”
    If TMSI is reallocated so why paging on previous LAC?

    #68655 Reply
    pix
    Guest

    hi agha,

    But when does this happen compared to the LAU : 1s after ? 5s after ? 10s after ? 30s after ? All the time ?

    What’s for sure is that this behaviour comes from the MSC/VLR/HLR which is not properly up to date. Unfortunately, I know nothing about NSS ๐Ÿ™‚

    The TMSI realocation clearly indicates that the VLR has mapped this IMSI to the new LAC. But is the HLR aware of that yet ?

    Just brainstorming ๐Ÿ™‚

    regards
    pix

    #68656 Reply
    Agha
    Guest

    Hi PIX,
    Agreed,thats why i call u pix ::
    P— Person of
    I— Info
    X— Xchanger…:)

    #68657 Reply
    pix
    Guest

    kewl ๐Ÿ™‚

    plz share info if/when you have them !

Viewing 6 posts - 1 through 6 (of 6 total)
Reply To: TMSI reallocation for LU Req intra MSC
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