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sdcch drop decreases, TCH drop Increases

  • This topic has 9 replies, 1 voice, and was last updated 9 years ago by Hema.
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  • #53637 Reply

    hello guys..

    can you help me what must i do to decrease TCH drop..
    i have some problem with my GSM CELL, there are any trx with bad quality e.g. i have configuration 2+2+2…but last week i have upgrade on 3rd sector to be 2+2+4 because capacity needed…
    btw after trx upgraded, i have sddrop incereases very high, but i try to moving SDCCH TS from bad TRX quality to another else Trx with good quality, this case solved, SDDrop decreseas & have normal value…but TCH drop still moving to high value….

    can you give me some solution about this case? at now no alarm detected for TCH congest..

    thak you guys

    #53638 Reply


    your did a good job. it looks like the new TRX is faulty have you tried to reset it ? or perhaps re-create the cell with the 4 TRX ?

    #53639 Reply

    i have done to do..
    i thinks it’s more about hardware pix i was have checked, i think thats about other case on radio & parameter..
    i have try to retune the parameter of HO:
    HO pwrbgt,HO margin, HO rx Lev, HO Qual, and on Trx i was activated the TRP at good TRX…
    2 week ago i have done to optimization it, and last week i have monitoring this…
    the result are HOSR & CSSR increases,SDDROP decreases,TCH block decreases, but Calldrop still hapent…
    so once againt i try to check the physicaly instalation cable system BTS and antennas by VSWR…
    surprise, i get the point of problem…
    VSWR high causes the antennas connector not properly connected, this matter is caused by age of feeder and antennas overage and less maintenance…

    i have proposed to change it and maybe as soon i’ll share the result…

    #53640 Reply

    hi joe,

    good to hear from you again, and thx for sharing.

    as a rule of thumb: everytime there is a really bad QoS, it is because of hardware problems…

    #53641 Reply

    The scenario is: Only in one sector
    High SDCCH Drop=30%
    Assignment success rate = 100%, so no SDCCH Blocking/congestion.
    MHT for SDCCH = 11 sec

    My qustion is why the SDCCH drop rate is too high and how to solve this problem?

    Also why the MHT for SDCCH is to high(11 sec)? generally it is 4/5 sec.

    #53642 Reply


    SDCCH Drop due to radio problems is only detected after several seconds. So the more drops you have, the longer will be your MHT.

    So, solve your drops, it’ll solve your long MHT.

    What you could do is:
    1) lock the TRX that currently carries the SDCCH timeslot with the most SDCCH traffic. For instance if you have 2 SDCCH timeslots, focus on the one that carries the most traffic (you can check SDCCH requests per TRX for instance)

    2) if SDCCH drop reduces :
    a) either the frequency of the TRX is interfered (low probability)
    b) the TRX is faulty (high probability)

    3) if SDCCH does not reduce, unlock this TRX and lock the TRX that carries the other SDCCH timeslot. You can always locate a new SDCCH timeslot onto another TRX, in order not to reduce your SDCCH capacity.
    repeat step (2)

    4) if nothing works, then let me know 🙂


    #53643 Reply

    Where are your SD’s? It’s on BCCH or on TCH or on both?
    1st identify the SD location,and check for the interference,HW problem for that TRX.You can check the BER for that.
    If can’t find nothing,go for hard reset of that cell.

    #53644 Reply

    hei zoy….

    Do you remember my 1st case which i have discuss with PIX…??

    try my steps to solved your SD problem..
    1. identify the TRX UPlink & Down link Quality. if their has bad quality, you may check all of the TRX connection cable till to antennas system and make sure their properly connected.
    2. if the SDCCH channel available on the bad TRX, try to move it into better TRX. it will help you to reduce SDDrop.

    #53645 Reply

    Hi Guys

    M working with ALU KPI. MY 2+4+2+4. in 1st sect-there DLQ is bad and in 4th sect.their DLQ as well as SDCCH both is bad.what can i do for this???

    M using Baseband hopping in my network .but in 1st sect it is lock.This effect my DLQ.their is not a limit of Freq in my Network…

    Aside my serving Sites tch Frequency is (Eg:- 1008 and neighbor frequency is 1007 and 1009) this is also effecting my DLQ.

    #53646 Reply

    poor DL quality after TRX addition, please provide a solution

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