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DLQ Ho In IBS site(ALU)

Viewing 14 posts - 1 through 14 (of 14 total)
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  • #68184

    Hi Pix,

    There is lots of handover due to quality in one of IBS cell,equipment use ALU.
    I checked frequencies its ok there are 4 trx in that cell, no hardware problem.pls suggest some parameter which i will change.


    hi mannu,

    how much is “a lot” ?

    could you check some QoS Stats :
    – idle band interference measurements per TRX
    – RMS path balance per TRX

    then check your frequency parameters (hopping list, maio)

    it could be due to a sudden loss of coverage (elevator, stairs, deep-indoor meeting room). To isolate this case, you can activate a microcell cause “bad SACCH”, or you can increase A QUAL HO and reduce A LEV HO.

    The best would be to “walktest” ths building…


    Sir Pix,

    There is 30% Ho due to DLQ and sample is around 35.

    And i will check – idle band interference measurements per TRX
    – RMS path balance per TRX report and get back to you.

    BBH is used.

    There is no coverage problem in the building,but some handover trigger near window.
    And current A_Lev value is 2, A_LevMcho Value is 2,A_PBGT Value is 2,A_Qual Value is 4.

    Will u suggest any other parameter need to be change.

    Thank You.


    hi manu (no sir, please !!)

    Thanks for your answer, it’s detailed and precise, that’s rare enough on this forum to be highlighted !

    Some averaging windows are very short (“2”), but not for the quality HO (“4”). Therefore I would not modify them in regards to your current issue.
    However, later, you could try to increase the A PBGT HO, and perhaps the A LEV HO.

    What are the values for L_RXQUAL_DL_H ? (there is one for AMR, one for legacy codec, etc..) and the FH OFFSET ?

    Waiting for your feedback on the Path balance and Idle band Intf.



    Hello Pix sir(i used to call you sir because you deserve this respect)

    Earlier A_lev Ho is 4(now i decreased 2),A_PBGTHO is 4(i decreased 2)and A_LevMCHO is 4(i decreased 2) but i didn’t increase A_ Qual HO because DLQ sample is quit high so it may increase CD.

    L_RXQUAL_DL_H is 4.5 for all(sorry but we cant change that parameter) and offset Hopping is 2.

    I dont know in which report TRX wise idle band interference indicate but i checked mono health report for cell in which it shows all sample in band 1.sir will u tell me in NPO in which category i search that report Indicator or Report and by which name.

    And there is 4 trx and there Pref mark are as 0,1,2,1.using BBH.And also i checked Qos Trx report in which its shows drop because of radio on trx 3 and 4 but on 1st Trx no traffic(BCCH frequency on 1st Trx).

    And also i checked DL_RxQual_RxLev Trx report in which there is some bad quality sample on good i think there is interference on Tch Freq.what you suggest sir.? or u tell me i check any other report for interference.



    Sir Mannu 🙂

    It’s great to see that you know your way around NPO !
    The Mono Health report is where you’d find the “idle band interference” indicators. I prefer to check them out through “indicators” directly rather than “reports).
    Click on TRX & Indicators
    Then search for “idle” in the list.
    You should see five bands there.

    Checking RMS reports is great. Keep in mind you can do that per TRX as well.
    Click on TRX & Reports
    “Distribution Reports”

    Do you notice a difference between the UL RXLEV/RXQUAL and the DL RXLEV/RXQUAL ?
    It seems that you only have DL interferences, which is rather consistent with a “near window” interference.
    Our strategy will be to decrease the power of the interferer(s). First step : find the interferer cell(s). Then try :
    – activating the DL PC on the interferer cell
    – activating the DL DTX on the interferer cell
    – activating the HR in interferer (or increase HR usage if it is already activating)

    In the interfered cell (indoor cell), you can try:

    – putting TCH PREF MARK = 2 in TRX 1 and TCH PREF MARK = 0 in TRX 2. If your BCCH frequency is cleaner than the TCH ones, you should see some improvements.
    – reduce the indoor coverage : reduce the Cell Reselect Offset (only useful if you are using the C2 criteria), add some “near window” neighbours

    Of course, you can try changing frequencies of the indoor cell. You could even implement a broadband SFH -> instead of using BBH on 4 frequencies, activate SFH using all your GSM 900 frequencies in the MA list.

    That’s just to test…



    Thanks Pix Sir.


    Pix Sir,

    According to your suggestion if I change the TRX-1 pref mark is 2 and TRX-2 pref mark is 0, then our TRXs pref mark is as follows
    TRX-1 (2)
    TRX-2 (0)
    TRX-3 (2)
    TRX-4 (1)

    Its mean first traffic goes on TRX-4 then on TRX-3 and last on TRX-1.

    But Sir, according to RMS report there is few bad quality samples between level -70 to -104 on TRX 3 and TRX 4.

    And TRX 2 is OK and no traffic is on TRX 1 because currently its pref mark is 0.

    Sir you suggest pref mark for all the TRX according to your point of view.



    sorry i did a typo, but you understood what i wanted to do :

    — trx pref mark = 2 on TRX1 (to push TCH traffic there)
    — trx pref mark < 2 on the other TRXs (and don't forget to put 0 on one or more TRX to allow GPRS) Then check RMS DL rxLev/rxQual on the TRX1, compared to other TRXs that carry traffic. If TRX2, 3 & 4 show equally bad DL RxQual, it is a Freq problem. If TRX1, 2, 3, 4 show bad DL RxQual, then it means your BCCH is also interferred. If only TRX3 shows problem, then I would strongly suspect a TRX problem. regards pix


    Sir Pix,

    I am going to put pref mark like this:
    TRX 1- Pref mark 2
    TRX 2- Pref mark 1
    TRX 3- Pref mark 1
    TRX 4- Pref mark 0

    Sir please tell me the difference between pref mark 2 and 1,its mean if i put pref mark 2 on TRX 1 then its a second priority for traffic.
    Actually sir i am little bit confused in value 1 and 2.
    What happen if i put pref mark 1 on TRX 1,2 and 3 and 0 for TRX 4 which use for GPRS.




    the higher the “trx pref mark”, the higher the priority of the TRX when it comes to TCH ALLOCATION.

    for ex.
    TRX 1 – trx pref mark = 4
    TRX 2 – trx pref mark = 2

    TRX 1 will have higher priority than TRX 2 for getting TCH allocated on its timeslots.
    Once all timeslots of TRX 1 are busy, then only the BSC will allocate calls on the TRX 2.
    Therefore TRX 1 will be very busy, while TRX 2 may take only little traffic during the day.

    Trx Pref Mark = 0 means the TRX can carry PDCH ((e)GPRS traffic) and voice (TCH).
    If Trx Pref Mark > 0 then the TRX can only carry voice (TCH).



    Sir Pix,

    One question suppose there are 4 trx in a cell and BBH is use.

    Lets say freq are as follows:
    TRX-1(Freq 12)
    TRX-2(Freq 34)
    TRX-3(Freq 19)
    TRX-4(Freq 21)

    If i put highest pref mark on trx-1
    then its mean our traffic is going on Trx 1.

    In that case we will able to know only the Quality of TRX 1 not the frequency interference allocated on TRX 1(because during BBH its used all 4 frequency).

    Lets say in RMS report of TRX 1 show bad quality on good level
    then how we will come to know which frequencies causing bad quality(interference)because its used all 4 freq.



    you can’t ! I should have clarify this point, you are right : you must stop the BBH and use No-Hopping.

    However I must admit that pushing more traffic to TRX1 does not serve much purpose apart from checking that this is not a HW failure on TRX 3 and TRX 4 (as those are the ones on which there was enough traffic to be able to analysie RMS reports)

    There is no real point in finding which one of the 4 frequencies is interfered : they are probably all equally interfered, assuming you are using the same BBH MA-list in the neighbours too.
    If your BCCH planning is different than your TCH planning, then you might see a little difference by going from BBH to NH and pushing traffic to BCCH.

    Notice that I proposed other things you could try in interferer and interfered cells.

    In the RMS C/I report, you may find which cell is interfering.



    Pix sir,

    New 2 dis forum. Actually facing problems in DLQ parameters of my city cells,however all the other parameters of those cells are ok. continuously the cells are getting repeated.
    Can u suggest something.

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