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Drop due to BBS Interm/RTC – in ALU

Viewing 11 posts - 1 through 11 (of 11 total)
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  • #65955

    Dear All,

    Hello guys, is there any idea how to reduce drop due to BSS Interm/RTC fail? I know it mostly related to BSC connection, RTC, etc.

    I’m working in B10 ALU. I was wondering if there is a parameter which could be set to reduce it, instead of doing an investigation in BSC side.

    I’d be grateful to see your answer. 🙂





    BSS Drop RTC are due to HW failures…
    1/ either a faulty board in the BTS, in the BSC or in the TC
    2/ or a faulty interface : Abis or AterMux failures

    –> you cannot fix this with a parameter.
    If you can find which board or interface is faulty, you could lock it and transfer the load to another board.

    BSS Drop due to internal failures are usually due to O&M commands (lock/unlock/reset/restart).

    Priority : fix your HW failures, and once it is done (–> rtc drop = 0), check if the “internal failures” are still there. Cuz they might be a side-effect of the “RTC drop” problem.



    Dear Pix,

    Thanks alo t fo-rin the answer. Yup u’re right,ít’s due to hardware failures. The problem is that i just do the optimization by remote, we just follow úp the issue to field operation team anđ that’s nọt easy for theM to check.

    I figured out that those drops always occured when the traffic was increasing. This happened in all trxs. In which connection do u think the cause of the drops? Or perhaps the ANC hardware issue? Could u share your experience, i mean your action in the field that can reduce the drops?





    investigating the RTC drop is easy :

    does it happen on several BSC ?
    does it happen on a whole BSC ?
    does it happen on only few BTS ?
    only one BTS ?
    only one cell ?
    only one TRX ?

    If 1 or many BSC : are they all connected to the same TC ?
    thanks to “AIC” (a-interface) counters in NPO (AIC is the name of an object, such as Cell, Adjacency, TRX, etc), you can detect in which Ater-mux timeslot there is a failure.

    Since you say that it occurs only when the traffic is high, then I would suspect a board to be faulty, either in 1 BSC or in 1 TC. Again, refer to the investigation method above… Normally, the traffic is allocated randomly on the BSC or TC boards, so the traffic should not influence the % of RTC drops.

    Please share your QoS stats here 🙂



    Hi Pix,

    Can you tell —>The Counter Name :AIC” (a-interface) counters in NPO (AIC is the name of an object, such as Cell, Adjacency, TRX, etc), you can detect in which Ater-mux timeslot there is a failure.

    Is there any counter in NPO from which we findout which Ater-mux timeslot is problematic.

    Also I have A-interface failure counter in NPO- C181j(A-interface failures due to BSSUnequipped.
    Can you explain the causes of these failures.



    AIC counters are counted per Atermux nibble, or A-interface timeslot
    –> not per Atermux “timeslot”

    There are some counters, such as C181 or C18x… that are counting messages sent or received by the BSC on the A interface. Thanks to them, you are able to investigate a problem on A interface. But they are not counted per Atermux nibble. They are counted per cell.

    Regarding C181 precisely, could you check its properties ? Check the “trigger”. that will tell you which message is actually counted. Then go to the 3GPP and find in which situation this message is sent/received on A interface.
    This is the way to do it… Can’t do it for you because I’m not in the office right now…


    June Nguyen


    I got some sector-cells randomly have high bss drop every hour, not because of transmission reason, bsc, TC, i checked trx, agc, trans is ok, pls help to find out reason

    Adigun Joseph

    Hi, can anybody advise me on what to do? I’m having two Ater Mux on my BSC as up but the corrensponding N7 are down.
    What could be the cause and do I go about resolving it. Thanks


    Hi Adigun

    If the C7 is down and ater is up it can mean
    1) There is BER on the Ater and as the C7 is more sensitive then the ater so the C7 can remain down.
    2) Get the Loop Break checked at both BSC and XCDR end to confirm any mismatch at TXN end.
    3) There is Mismatch between the CIC on which the C7 is defined between BSC and MSC.

    Try : move the C7 on another Ater and check if it comes or not, move the C7 on another CIC if you are sure about the Ater, i have faced similar problems many times in our NW.

    Which Vendor equipment are you using




    I’m working at ALU systems B12.
    Can someone please tell me what are the reasons for Call Drops BSS Internal Failures.
    I’m unable to know why this happens. When we ask BSS team , they say that site is having congestion so there is BSS Internal call drops.
    I’m not satisfied by this answer as if congestion is there cell will not receive new TCH but how will it affect drops?
    Please answer to my queries.



    Which counter is triggered exactly ? (MC…?)
    Looking at the counter definition should already give you a pretty clear picture of the trigger causes.

    What is the distribution of internal drops in your BSC : only few RBS, all the RBS ? at any random hour, or only during peak our ? during the night ?

    Is the BSC an “BSC MX” ?


Viewing 11 posts - 1 through 11 (of 11 total)
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