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High SDCCH Traffic in LA Borders

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  • #44226 Reply

    I have trains crossing the Location Area border, why is this a problem? how can it be solved?
    The statistics are the following:
    (they are all statistics al peak hour, but they keep approximately the same all day long)
    SDCCH traffic: 22.12
    CCALLS: 193696
    CCONGS: 95834
    CTCONGS: 6369
    CMSESTAB: 9845

    Any help will be appreciated,
    Thanks in advance.

    #44227 Reply

    The parameters are:
    CCALLS: Allocation Attemps
    CCONGS: Congestion
    CTCONGS: Congestion time
    CMSESTAB: MS conection stablishment on SDCCH


    #44228 Reply

    Take in consideration this are counters for 1 hour and the Overlay and Underlay counters are added together

    #44229 Reply

    I asked about the trains, because we also have problems when a train full with subscribers crosses the LA/RA border and all of them start to update their location at the same time.

    #44230 Reply

    All you write now is a confirmation of your previous saying for high SDCCH Congestion. These numbers that you present now just proves this. You need to investigate the problem and one way of doing this is my previous post.

    #44231 Reply

    I am showing this statistics so that you can have a more detailed information of the problem at hand. Is the MHT at the right values?

    #44232 Reply

    I can’t find what each of the selection types means, can you help me?

    #44233 Reply

    I founf the selection types, most of them are because of the location updating (just as we suspected). Is there anything I can do to fix this?
    thanks in advance…

    #44234 Reply

    Kalinizma o someone that can help me:
    As I told you before the entire network is Ericsson, I need to know if there is a way to know which telephones are generating all this traffic due to Location Update. Is there a process in the OSS to do this?
    Thanks Kalinzma for the previous post, it was really helpfull (y)
    Any more help will be appreciated greately.

    #44235 Reply

    HI all

    I had a similar problem in my network.

    I agree with Boko regarding MHT thing.

    I suggest Esamoraglo to change LAC boundry and avoid trains crossing the LAC boundry.

    If possible on your part just try increasing no of SDCCH Blocks for a day or 2 and then observe whats the change. If you feel this may bring in TCH blocking, try going in for half rate.

    This is what I did and for my 2 TRX problamatic cell, normally we go in for 8 SDCCH Blocks, but I had to finnaly set SDCCH blocks to 24. I also managed to pick up extra traffic on voice front also.

    Reason for my recomendation:
    SDCCH traffic is 22.12 Erlang.
    To cater this with 1% GoS, you need about 32 channels(From Erlan B table), So you need atleast 32 SDCCH Blocks to cater the SDCCH requirement.

    I hope it helps

    #44236 Reply

    what I need to do is to reduce this SDCCH traffic because it is excesive. There has to be some kind of problem with the network. Increasing the number of SDCCH is not a solution, as you increase the SDCCH blocks the traffic also increases, generating congestion in the same way. I am trying to find the reason for so many Location Updates, but I cant seem to find a way to see it in detail (what telephones are generating all the traffic, if it is a gruop of telephones or it is just a problem of the location of the LA. Thanks. Any sugestion is more than welcome.

    #44237 Reply

    Dear Esamoraglo,
    The only way to solve this problem is to go to cell level what you need to do is:
    1- Check the LA and if the cells are properly homed to the destinated BSC-MSC
    2- Check the cells @ LA borders
    3- Check if there are any cells shooting from far away to this LA
    4- Set some plans to downtilt shooting cells
    5- Study the possibility to re-plan the LA
    6- The most important issue is to check if there is a best server because you may have cells are doing a cell selection/reselection due to no best server thus doing a high LAU.

    Hope you’ll get rid of your problem…

    #44238 Reply

    usually the cells with such problems are couples. If this is your case you could more easily locate the problem place.
    There is no way to find out the phones that generate this if the LU is not successful (blocked) I think MSC guys could easily check this.

    #44239 Reply


    Hardware problem? Ruled that out already?
    Low RF area causing lots of cells to serve there?
    Overshooting cells?
    The terminals that might keep requesting for SDCCH bt keep failing, maybe you can drive around in that area, see if there is any research centre there dealing with mobiles, SIMs, transmitting equipment….very hard to find these terminals.

    #44240 Reply
    Kamal Goyal

    What exactly is the difference between TCH Blocking and TCH Congestion?

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