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CRH parameter issue

Viewing 9 posts - 1 through 9 (of 9 total)
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  • #70068 Reply
    Samer
    Guest

    hello, i have problem with CRH parameter assignment. is there any other parameters will affect its behavior maybe not only in RBS but on BSC or MSC. although CRH value have been changed no effect is happened please give me any hint. we use Ericsson hardware.

    #70069 Reply
    pix
    Guest

    Hello Samer,

    What kind of effect are you looking for ?

    You should see a decrease of the number of 2G LAU on cells located at lac borders.
    However, it might be difficult to see it… because there is still many 2G LAU due to 3G to 2G mobility (at the end of a call with IRAT HO , or Idle mode 3G-2G). So you shouldn’t expect such a huge impact of CRH on the number of 2G LAU. On top of that, CRH will reduce the pingpong 2G LAU, but many MS are really moving from LAC to LAC (physical mobility along highways, roads, rails…), in which case the CRH will only delay the inevitable LAU.

    To reduce the 3G2G mobility,
    – activate the “fast reselection”,
    – inhibit the IRAT HO,
    – decrease the qRxlevmin (from -112dBm to -114dBm for example)

    Cheers,

    pix

    #70070 Reply
    Samer
    Guest

    thank you. however i am looking if there is any other parameters will control CRH parameter behavior. for example in BTS or BSC or MSC parameters. you need to know that we have 2G network only and 3G not yet implemented.

    #70071 Reply
    pix
    Guest

    hi samer,

    ok, so in this case I believe, if I remember correctly, that you need to activate the computation of the C2 criterion.
    This is controlled by a radio parameter in ALU. But I need to check it out in E///. I’ll answer more precisely tomorrow.

    br /pix

    #70072 Reply
    Samer
    Guest

    i am waiting and thanks in advance 🙂

    #70073 Reply
    pix
    Guest

    hi,

    No, nothing special in E///. CRH and CRO are always active.

    BTZ – Ensure that CRH is set to a high value in the neighbours of the cell you are observing.
    If CRH(neighbours) is high, that will reduce the number of incoming cell reselections in the serving cell.

    I can have a look at your settings if you want ? Please list the parameters values :
    CRO
    TO
    CRH
    PT
    T3212
    ACCMIN
    CBQ

    br / pix

    #70074 Reply
    Samer
    Guest

    thank you for your efforts, however we put the default values for the parameters you mentioned as follow:
    CRO 0
    TO 0
    CRH 14
    PT 0
    T3212 30
    ACCMIN 110
    CBQ high

    we actually tried all possible values to CRH and nothing happened so a conclusion came out that an other parameter might control its behavior or something stuck in Ericsson device !!

    #70075 Reply
    pix
    Guest

    ok… but exactly, what are you looking at ? can you share some values ?

    with a CRH = 14, you should see a huge issue in GPRS mobility (a lot of TBF drops)

    you should also see less SDCCH LAU, and a decrease in CSSR, because MS are stuck in their serving cells, without being able to move to (reselect) a better neighbour cell.

    With a ACCMIN = 110, the effect should be even more pronounced.

    The Ericsson implementation of the CRH is fine, I can see it in the many DT I’ve done, no worry about that aspect.

    Let’s do some testings ? select two cells, one from each side of a LAC border.
    Put CRH = 0dB on both cells
    Put CRO = 10dB on cell A, observe that trafic increases in Cell A
    Put CRH = 20dB on cell B, observe that trafic increases (a little) on cell B, and decreases (a little) on cell A. Also, you should not there is less SDCCH LAU in cell A.

    Now there is another possibility that the border between cell A and B is very “poor”, meaning that RXLEV dips below -110dBm, in which case the MS will not be using the CRH anymore.
    CRH works well if RXLEV at borders are “CRH” dB higher than ACCMIN.

    Let me know how it goes…

    #70076 Reply
    Samer
    Guest

    thanks, we actually appreciate your help, i will check with my group and return back to you for any new progress. my greetings 🙂

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