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High SDCCH congestion even if Cap is OK

Viewing 15 posts - 1 through 15 (of 17 total)
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  • #44613 Reply
    Planet
    Guest

    Hi friends,
    I am experiencing high SDCCH congestion in most of cells even if the SD Traffic is low than the capacity, this is causing a decrease of Immediate Assignement Success Rate which affect the CSSR… This is a Siemens network. Any help will be appreciated…

    #44614 Reply
    Ahmed
    Guest

    Hi Planet,
    Check Timer setting and RACHBT setting. I am affraid this is overshooting site so this site is over hearing for any RACH. Checkn if any HW failures. Try to swith the BCCH TRX to any TRX
    Thanks

    #44615 Reply
    Planet
    Guest

    Hi Planet,
    Thank you for your fast replay, I check the RACHBT
    setting and is Ok, most of sites have tilt of antennas
    as -6, so that’s whay I exclude the overshooting cause
    because most of sites are sufering from the same
    problem ( congestion high even if the capacity is more
    ok), it remains the Timers setting which I daubt too
    as you said,do you have any idea about the famous
    Timers that may affect the QoS when are not good set.
    Thanks

    #44616 Reply
    Fabio
    Guest

    Have you checked if the transmission line (MW, leased line) is ok?
    Maybe it´s oscillating in some moments and this can make your sub-TS´s on the ABIS unavaiable…

    #44617 Reply
    Planet
    Guest

    Hi Fabio,
    Thanks a lot for your clarrification, you are right concerning the unavailable TS on the Abis interface because I asked for Alarm report on cells in the OMC and most of them having LAPD Signalling overload ( may be caused by link instable), I reduce Timer T3101 from HLFSEC-6 to HLFSEC-3 to minimise the effect of Fantom RACH and the blocking is minimised but still high in some cells even if the capacity is OK, so what should I do to solve problem of overload on the LAPD (ABIS)?
    thanks in advance

    #44618 Reply
    Fabio
    Guest

    Planet,

    Have you tried to create another LAPDm link? Sometimes, if you have a large number of TRX in this pool, it´s necessary to create another signalling link.

    #44619 Reply
    Vanderlay
    Guest

    Hi,

    By congestion do you mean blocked attempts or “percentage of time when no free SDCCH channels were available”

    #44620 Reply
    Planet
    Guest

    Thanks to All,
    to Vanderlay: Yes I mean blocked attempts, the other one is not used in SDCCH dimensionning because it gives you the utilization of the ressources.
    to Fabio: I didn’t tried to add more LAPDm link on the Abis because the number of TRX’s in the BTSM not exceed 14, when this happend people in NOC add second Abis with another LAPDm link..do you have any idea about maximum number of TRX’s supported by one LAPDm TS for signaling in the Abis interface?
    thanks in advance

    #44621 Reply
    Sad
    Guest

    Hi Planet,

    There’s no a number of TRX can be handling by one TS LAPD.

    For your case try to add other LAPD TS and assigne some TRXs to the first LPDLM and the others to the secand by the parameter LPDLMN in Create TRX object.

    and let’s us know the effects.

    Thanks

    #44622 Reply
    Fabio
    Guest

    Planet,

    You´re correct about the theoretical limit of 14 TRX…
    Although you may experience some problems (like the one you´re having)and in this case, I really think it´s a good idea to try to create another LPLDM link and associate some TRX with this new link.
    I think this could solve your problem.

    Try it out and make us know the results.

    #44623 Reply
    Planet
    Guest

    Dears,
    Thanks a lot for the idea.. OK I will try it and update u by the result
    Thanks

    #44624 Reply
    Thomas
    Guest

    Hi, How can I calculate succes rate for NB_LAPD_INFO_FRAME on both RECEIVE AND SENT

    #44625 Reply
    not mentioned
    Guest

    Please do describe clearly.

    #44626 Reply
    dung
    Guest

    sdcch congestion

    #44627 Reply
    cunal
    Guest

    Hi
    Can you plz explain HLFSEC-6.
    I mean what does this 6 mean as well as hlfsec ???

    Waiting for reply.

Viewing 15 posts - 1 through 15 (of 17 total)
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