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one side audibility in GSM

Viewing 8 posts - 1 through 8 (of 8 total)
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  • #49177

    Hi everybody!

    Can anybody tell me about some reasons of this subject?

    I know that one of the reasons is an UL/DL power disbalance.
    Are there any other most common reasons? Um, A-bis, A-interfaces and equipments, etc.?
    How can I identify those problems?

    We use Nokia Ultrasite BTS.



    may be yo interference in the uplink that made by other mobile if you are in urban area and you have many sites inside these problem is rare but on the high ways this is most possible case that make UL interfered .
    solution is that to use UL power control or UL DTX .


    well it really depends what type of problem you have : the voice you hear tends to fade away, disappear, get noisy, sound metallic ? In this case, it is probably interference :
    – either in the UL of the cell where the called party is located
    – or the DL of the cell you are located

    on the QOS statistics, you should see HO due to UL quality, or DL quality, and also (possibly) interference HO (intracell).

    If you just don’t hear anything (no voice at all starting at the pickup), then it is a CIC definition problem, or (more generally) a routing issue at NSS side.



    Thanks, dears. I can’t find words to say about my respect of your professionalism and your good will to help.

    Here is an additional info about the problem.

    A subscriber is located in high density urban deep indoor area.
    When he(she) calls he(she) sometimes hears silence, sometimes the voice disapears, after few seconds he(she) hears everything, but the calls sometimes drop.
    Each call is with bad quality.

    I saw the statistics of cell where calls were dropped.
    It seems like neither interference no any bad TRX. I’m sure the problem is probably because of the lack of signal strenght DL and UL.

    Or I have CIC definition problem or routing issue at NSS side.

    Dear pix, can you please describe slightly more fully what does it mean “CIC definition problem or routing issue at NSS side”?
    What is the easiest way to identify these problems?


    There is a paramater in the BTS where you can enable Mobile and BTS dynamic transmit. ” I forgot the exact parameter name” You may check if BTS is dynamic … normally this should be disabled (mobile is enabled) else you will have variable BTS TX which may cause what you describe in your problem.


    To identify the problematic CICs, you have to check the average conversation time on each CIC. it should be very less for the problematic CICs. (whenever the call is routed through a problematic CIC, the user tend to disconnect it after few seconds thus making the conversation time shorter). you can also request your NSS team to carry out a no-audio or audio loop back testing for all the CICs of the respective BSC.
    To identify the problem at the radio side, i think you should conduct a walk test of drive test (whatever suits you), see the quality situation, also focus on RLINK TIMEOUT COUNTER when the call drops. may be you can make out something out of it

    Md.Abu Abdullah Al-Mehedi

    Pls,provide me the possible solution to reduce metallic sound and the call drop.
    I’m handleing HUAWEI BTS and BSC.


    Metallic sound and call drop : you have too much interference, try to enhance your frequency planning.

Viewing 8 posts - 1 through 8 (of 8 total)
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