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Call drops in GSM

Viewing 13 posts - 1 through 13 (of 13 total)
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  • #65999 Reply
    RF Engineer
    Guest

    Hi All,

    Can anybody tell why calls are droped in the below mentioned scenario?

    Call Drops on Traffic Channel in Stable State (Error Indication).

    Call Drops on Traffic Channel in Stable State (Connection Failure).

    In counter level analysis i am getting due to poor indoor coverage.so what can i do for that?

    #66000 Reply
    007
    Guest

    to improve inbuilding coverage u need
    to give some mechenical tilt to near sector( antenna) or IBS also a solution to improve inbuilding coverage

    #66001 Reply
    RF Engineer
    Guest

    Hi 007,

    Thanks!!
    For Single user IBS is not a competitive solution and Mechanical tilt will reduce the coverage foot print-because we are using RF antenna height at 24-27mtrs.
    Is there any other soft parameter can do will improve the call drops.

    Could you provide the reason for call drop in the below scenario?

    Call Drops on Traffic Channel in Stable State (Error Indication).

    Call Drops on Traffic Channel in Stable State (Connection Failure).

    Team i need in details-Pls help me!!!

    #66002 Reply
    pix
    Guest

    hi rf engineer,

    the only soft solution I know is to use a stronger codec : have you tried AMR-FR with a codec around 6 or 7 kb/s ?
    This should be more resistant in poor radio conditions. You will need to increase the radio link timeout ‘amr’ to fully benefit from it. (in most recent radio releases, there is a new feature “repeated SACCH”, that is useful for robustness of AMR against call drop)

    Physical solution : add a cheap indoor repeater for this user, this will cost few hundred $.
    1 outdoor antenna
    2 feeders 1/2″
    1 repeater (2-ways amplifier)
    1 indoor antenna

    It’s an easy upgrade as long as there are not too many frequencies to repeat. If the GSM band is very used, then you’ll have to invest in a band-selective or even channel selective repeater (more $$).

    cheers
    pix

    #66003 Reply
    RF Engineer
    Guest

    Hi Pix,

    Thanks!!

    I am using huawei system. i was searching those parameter,but i did not found that. Can you please help me to get this in which parameter group?.

    I have a doubt,If we increase the repeated SACCH frames,is there any congestion in the network?

    Kindly guide me..

    #66004 Reply
    pix
    Guest

    rf egineer,

    i can’t tell you were are AMR and RSACCH parameters in Huawei : i don’t know this system.

    RSACCH does not increase the load of the system, nowhere ! Instead of sending one new SACCH message every 480ms, there is one new SACCH msg every 2*480ms ! In the meanwhile, the same message is sent two times (at t=0 and at t=480ms).

    So there is the same amount of SACCH load, with twice less information, each ifo being sent twice.

    Enable Repeated FACCH as well, RSACCH and RFACCH are two features that works well together.

    RSACCH is only useful when AMR is enabled and you are using “low” codecs. With regular EFR codec, there will be no improvement.
    Regards
    pix

    #66005 Reply
    RF Engineer
    Guest

    Thanks Mr.Pix.

    #66006 Reply
    RF Engineer
    Guest

    Can anybody tell,is there any relation between AMR and Call drops. During drive in some of the scenario i am getting HO Fail/Call drops due to AMR.

    I want to know how does AMR works?
    What is the value of AMR in good and bad conditions.

    Kindly help me!!

    #66007 Reply
    Ganesh
    Guest

    Mr Pix can you tell me how many card used in Huwei BTS

    #66008 Reply
    pix
    Guest

    no sorry, i don’t know the huawei bts…

    regards
    pix

    #66009 Reply
    mohamed
    Guest

    Can anybody tell,is there any relation between AMR and Call drops. During drive in some of the scenario i am getting HO Fail/Call drops due to AMR.

    #66010 Reply
    Wallis Dudhnath
    Guest

    For your case a RCA is required.

    Factors that influence call drops include but is not limited to
    the following; Transmission issues (high Bit Error Rates), Handover between
    sites that have not been optimised and Co-Channel interference.

    Check if your BTS has any obvious harware faults that require a correction (e.g.
    latest fix / correction Package).

    #66011 Reply
    LEMAURE
    Guest

    Hello Mohamed!

    make sure the Radio Link Timer related to AMR is greater than these of non AMR calls. adjust the following parameters
    AFR SACCH Multi-Frames ==>48
    AHR SACCH Multi-Frames ==>32

Viewing 13 posts - 1 through 13 (of 13 total)
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