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Activation TFO

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  • #65790 Reply
    Ian
    Guest

    Hello Experts,

    We activated TFO features from ALU and fout out we had 50% of the total HO are INTRACELL TFO

    (counter MC461)

    Intracell “Number of handover attempts on cause 29 : ‘TFO mismatch resolution, TFO optimisation’.

    Anybody experienced this ?

    like 1000 HO (cause PBGT+LEVEL…) + 1000 (intracell cause TFO, this is HUGE !!)

    Thanks
    Ian

    #65791 Reply
    Pix
    Guest

    Hi Ian,

    I suspect your TFO parameters are wrongly defined. There is roughly only one set of values that will function properly when HR is activated in your network.

    These are the correct ones:
    EN_TFO = Enable
    EN_TFO_AMR_WB = Enable (are you using that yet ??)
    EN_TFO_MATCH = Enable
    EN_TFO_OPT = Disable
    FORCE_TFO_HR_WHEN_LOADED = 1 (TFO HR only)
    FORCE_TFO_VS_AMR = 0 (disabled)
    KEEP_CODEC_HO = 0 (free choice of the codec)

    Keep Codec HO = free choice means that when MS is in FR and goes into a loaded cell, then it’ll probably get a HR channel (= it will get the codec allocated by the BSC). Then, thanks to the TFO_Match, the other MS will downgrade to HR (if it was previously in FR also), so that both sides are in HR. TFO will then resume.

    Enjoy 🙂
    pix

    #65792 Reply
    Ian
    Guest

    Hi Pix,

    Thanks so much for clarification.

    But we would like to avoid as much as possible HR, i find it provides bad Audio quality. The fact that the other MS downgrade to HR might generate more bad voice quality ?

    i’m not so confident with AMR_HR (we did not activate AMR_WB, by the way what do you think of WB ?)

    Are you working in ALU, you know so well the system !!!

    Thanks again and big congrats for your Web site ! it is a BLESSING !

    #65793 Reply
    Pix
    Guest

    Hi Ian,

    It’s not my website :)) But thanks anyway!

    I know only ALU radio, but I know it well, yes 🙂

    HR = bad voice quality
    –> NOOOOO ! If HR is used by *both* mobiles and if TFO is activated, the voice quality is actually excellent !
    The HR should actually be used only during MS-MS calls, that would be the best idea. And keep FR for MS-PSTN calls. My settings from yesterday are trying to work in this direction : HR is favorized for MS-MS calls. Therefore other type of calls (MS-PSTN) are more likely to remain in FR.

    AMR HR
    I guess you are using B10 ? In this case, you must know that AMR and TFO do not work together. I mean that if a MS is using an AMR codec (be it HR or FR), then the TFO cannot be activated for that call. Unless… unless you set FORCE_TFO_VS_AMR = Enable; in which case the MS with AMR will stop using AMR, and will use a legacy codec (such as FR or HR).
    For B10 network, I would personally push for TFO rather than AMR : TFO is free and gives good VQ. AMR is expensive and the results are not impressive at all.
    That’s just my opinion though…

    AMR WB is a new B10 feature, and that particular type of AMR works only with TFO.
    If you decide to use AMR WB, ensure that EN_TFO_AMR_WB = Enable.
    It provides a brilliant VQ, fabulous, but unless your marketing team advertizes it well, I don’t how this will generate more revenue for your operator compared to other operators. On top of that, not that many MS supports this feature yet.
    AMR WB requires to buy special MT120 boards (MT120 WB) for your TC. You could put for example 2 MT120WB boards per TC, and the rest = MT120. All MS which are AMR WB capable will be handled by these two specific WB boards. (1 board = 120 simult. calls)

    If you have more questions, let me know. And please use these TFO settings and let me know how it goes.

    Cheers
    pix

    #65794 Reply
    Ian
    Guest

    Hi Pix,

    Thank you for this clarification.

    Normally HR is using less data to perform a better coding ? i believe this has an impact on the audio quality, we had made some test here and MOS is far better on AMR_FR than AMR_HR (eventhough i’m wondering if codec 10.2 is not better than 12.2).

    We are going to ask AMR_WB.

    Can you clarify some parameters,

    Why EN_TFO_OPT = Disable –> why dont you activate that parameter ?

    Why FORCE_TFO_VS_AMR = 0 –> does it mean you dont want to force TFO over AMR ?

    Thank you again for your precious help.

    #65795 Reply
    ian
    Guest

    hi,

    HR is good when TFO is enabled.
    otherwise it is bad.
    try it.

    there is no operator in the world that is using AMR WB, so you’ll be the first ! rock n roll !

    EN_TFO_OPT = Disable –> this avoids going back to FR when the call was started in HR, after a HO to a cell which is in lowload.

    FORCE_TFO_VS_AMR = 0 –> DISABLE. It means that if a call is in AMR, TFO is disabled.
    If FORCE_TFO_VS_AMR = Enable, then a call in AMR will stop AMR in order to enjoy TFO.

    cheers
    pix

    #65796 Reply
    pix
    Guest

    ooops… previous msg was from me, not ian ^^

    #65797 Reply
    Rex
    Guest

    Hi,
    What happens in case when only EN_TFO=Enable and all other are DISABLED?
    Regards,
    Rex

    #65798 Reply
    Ian
    Guest

    Hello Pix,

    We have tried the parameters below and it looks like it works well, for now.

    I’ll monitor for some time and let you know.

    One important point :

    Before we were doing many intracell Hand Overs and with these parameters, no more Intracell HO . (the total of HO have reduced of 50%)

    By chance, do you know why when EN_TFO_OPT = Enable, it triggers so many Intracell !!

    Thanks again for ur input
    Ian

    #65799 Reply
    Ian
    Guest

    Hello Pix,

    Some news about the results, with these parameters we noticed a complete drop of TFO_success, meaning counter GQSTRCCTR (%TFO success) drop from 20% to 2%, meaning there is almost no more TFO success.

    Did you notice this ?

    BR
    Ian

    #65800 Reply
    Ian
    Guest

    Hello Expert,

    Anybody experienced this with the parameters below ?

    “drop of TFO_success, meaning counter GQSTRCCTR (%TFO success) drop from 20% to 2%, meaning there is almost no more TFO success.

    EN_TFO = Enable
    EN_TFO_AMR_WB = Enable (are you using that yet ??)
    EN_TFO_MATCH = Enable
    EN_TFO_OPT = Disable
    FORCE_TFO_HR_WHEN_LOADED = 1 (TFO HR only)
    FORCE_TFO_VS_AMR = 0 (disabled)
    KEEP_CODEC_HO = 0 (free choice of the codec)

    #65801 Reply
    pix
    Guest

    ian,

    could you please post the formula of this indicator ?

    i don’t think it is a critical issue. Are you allowing HR on all your cells ? Is it used a lot ?
    Please share the formula, we’ll investigate from here…

    Regarding the TFO_OPT and the drop of intracell_ho.
    when you disable the optimization of TFO, a call that is started with HR (on both MS) will stay in HR even though the MS did a HO into a cell where HR is not needed. In such situation, the call could move to FR.
    It is a very bad idea because the other MS might need to stay in HR (the cell is loaded). By allowing optimization, MS in loaded cell might be able to use FR.

    #65802 Reply
    Ian
    Guest

    Hi Pix,

    We have HR activated.

    This is the description below , when TFO_OPT is activated , i have as much HO intracell as Total_HO(Ppwrbgt+Level+Quality)

    When TFO_OPT is NOn activated, there are no more Intracell .

    NAME
    RTCH_TFO_success_rate 
    REFERENCE GQSTRCCTR 
    DESCRIPTION
    Rate of TCHs assigned in the serving cell for which TFO has been successfully established.
    FORMULA
    RTCH_TFO_success / RTCH_allocated 

    #65803 Reply
    pix
    Guest

    hi,

    ok, so if you have a lot of HR, the OPT will mess things up. You’re better without it.

    I believe the RTCH allocated is taking into account HO INTRACELL success. Since you have much less intra HO, the whole KPI decreases.

    only 2% of TFO is not that much… have you activated TFO in your whole network ?
    TFO wuold only work for calls from MS to MS within your own PLMN. If other operators in your country activate it as well, then the KPI will increase.
    This KPI tells you that you have only 2% of calls from MS to MS, within TFO-enabled zones.

    There is a second restriction : if one MS is in HR and the other is in FR in a cell that cannot support HR, then TFO can’t be activated.
    Do you have cells where HR is not allowed ?

    regards
    pix
    Regards

    #65804 Reply
    Ian
    Guest

    Hi Pix,

    Stangely no, we are allowing HR but most of the calls are FR (about 90%)

    Yes we have TFO everywhere.

    Stangely with TFO_OPT activated, it process Intra_Cell i believe to find the right match and therefore 20% of TFO success (cause 29 Rate of TCHs assigned in the serving cell for which TFO has been successfully established)

    When TFO_OPT disable, there is ZERO Intracell and only 2% of TFO_success.

    Does it mean that MS needs to process Intracell to find the right codec, unless without TFO_OPT, it won’t be able to match Codecs ?

    This is strange and i dont really have the details of the Algorithm, i’m curious.

    BR
    Ian

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