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Diff Sub/Full TEMS Measurements with DTX

Viewing 10 posts - 1 through 10 (of 10 total)
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  • #63305 Reply
    ALU
    Guest

    Hi,in my network,DTX(UL/DL) is totally disabled for AMR but enabled for non-AMR.now during DT,when the call is on AMR,y do i see different values for Rxqual/Rxlev Sub and Full as theoretically when we are not using DTX, then Full values should be equal to the Sub Values? Secondly, which value SUB/FULL gives me the actual measurements(with DTX Disabled in the Network)?
    Thanks.

    #63306 Reply
    poncho
    Guest

    1st Question: I don’t know which system you are working on but on the systems I have worked with it is not possible to enable DTX on AMR only because you enable DTX on cell-level meaning the whole independent of the codec uses DTX, maybe that is why you are see the behaviour you have observed.

    2nd Question: When DTX is disabled, you use FULL measurements but when it is enabled you use SUB measurements.

    #63307 Reply
    Pix
    Guest

    Hi ALU / Poncho,

    When DTX is disabled, FULL = SUB. So you can use any of them, the values should be rather close. FULL might be more precise though.

    Poncho : I don’t understand your 1st answer. If you enable DTX on cell level, for AMR and non AMR calls, why would that create a problem ?
    DL DTX would be “on” when the TC detects “no voice activity”
    UL DTX would be “on” when the MS detects “no voice activity”.

    cheers
    pix

    #63308 Reply
    ALU
    Guest

    Hi Guyz,
    Thanks for your quick response.
    @Poncho: My network is Alcatel and in Alcatel you have different set of parameters for enabling DTX for AMR/non-AMR, UL/DL, HR/FR. So,currently we have got DTX disabled for all AMR(UL/DL, HR,FR).

    @ Pix: Thats the point.They should be the same(theoretically) but they are not.Infact in DT, you see alot of variation.Even to the extent that at a particular instance, RxqualSUB is 2 and FULL is 6 and vice versa(even though 60% of times both are equal).But this still creates a confusion as to which value should we rely on?

    #63309 Reply
    poncho
    Guest

    @Pix:
    My first answer was to say that DTX is enabled on cell-level and it does not differentiate between AMR and non-AMR calls/phones. At least in E///, when DTX is enabled it works for both AMR and non-AMR at the same time.

    #63310 Reply
    Pix
    Guest

    ALU,

    Well, small variations could occur during a short duration, in case of frequency hopping for example. But I wouldn’t mind about it too much. When you make an average over 5 seconds, are the values very close ? identical ?
    anyway, keep in mind that it is the MS that performs the DL measurements, and these are what you see in TEMS. It doesn’t matter wheter the BSS is ALU, or E/// or …

    Poncho :
    Ok, now i understand. In ALU, one DTX parameter for each codec ๐Ÿ™‚

    #63311 Reply
    ALU
    Guest

    Hi Pix,
    I have checked and the variation is there.normally the Rxlevel values are close by but RxQual varies from sample to sample.I exported the values for 15 min long logfile of a cluster DT and the average value for RxQual_Sub was 1.21 and that of RxQual_Full turned out to be 1.84.Now thats a big variation if u ask me.So, what do u suggest which value should i rely on?

    #63312 Reply
    Pix
    Guest

    alu,

    it’s great you could get a numerical value : the difference clearly appears in the measures.

    It is troubling because there should be no difference : the BER is measured on the received bits. Whether the bits are AMR or SACCH is of no importance.

    So what’s happening…?
    1) the RxQual is computed differently during AMR calls : no.
    2) or TEMS is not properly computing it properly : possible but weird
    3) There is also another possibility : when using specific cyclic frequency hopping, the SACCH would always fall on the same frequency, leading to differences between the SACCH rxqual and the TCH rxqual… but i highly doubt your FH is set this way.
    4) I’m sorry to consider this but perhaps DTX is enabled and you just misread your parameter settings (yes, i do have some trust issues…)

    In the end, it looks like he problem comes from TEMS ?

    Anyway, you just want to know which one to use… Well, you can try to do it the proper (& long) way :
    drive the same road twice consecutively (to get same radio load conditions). 1st time with EFR, 2nd time with AMR. See if the problem also appears in EFR (it should not), then use the value from the AMR-call that is the closest to the one from the EFR-call. Indeed, the RXQUAL should not change whatever the codec in use.
    My guts are telling me the RXQUAL SUB is better…

    Thanks a lot for investigating this issue. That might become a good TAC ticket ๐Ÿ™‚

    Pix

    #63313 Reply
    ALU
    Guest

    Hi Pix,
    firstly lol @ point 4. it makes me wonder that y didn’t u come up with the b/m 5th point:
    5)maybe the measurements that the TEMS is given is the same and i am reading them incorrectly by mistake ๐Ÿ˜› (just kidding ๐Ÿ™‚
    I will perform the test that you have mentioned(i hope the radio conditions remain the same because as u know quite well that in a multi-server environment, in each traversal the scenario changes completely)
    Secondly, as i mentioned before, DTX is enabled for non-AMR in the Network so ofcourse EFR would show different values for Sub/Full.So, i will try to disable it for a few cells and then perform DT to check the issue.
    Once again thank you for your support.

    #63314 Reply
    Pix
    Guest

    ALU,

    ok, let me know how it goes ๐Ÿ™‚
    btw, i work in alu too. you can send me email there, so we can get in touch using our corporate emails.

    pix_erlang@yahoo.fr

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