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DL RxQuality Degraded after HR Reduction

Viewing 8 posts - 1 through 8 (of 8 total)
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  • #66392 Reply
    Mickey
    Guest

    Hi Friends,

    I have a unusual problem, Please help me to optimize this :

    In one of my Cluster(450 cells) AMR HR is 80% of Total Traffic, & Rx Qual at BBH was 75% cells >96
    Now we carried an activity to Reduce HR Percentage, We changed the Threshold FR to HR to 60% & above based on Utilization, i.e HR triggering will start after 60%.

    After these changes, I have observed that TCH Congestion is 0 on these cells as earlier also HR reduced from 80% to 67%(improved), But RxQuality DL has reduced from 75% to 64%. Ideally while Reducing HR, Quality should improve.. But here it has shown a reverse effect.

    Please help, what need to checked & what can be the issues… Can it happen practically ….

    #66393 Reply
    pix
    Guest

    hi mickey,

    when you talk about FR and HR, is this related only to AMR-HR and AMR-FR ?

    Did you notice any change in the utilisation of AMR vs. non-AMR codecs ?

    The RXQUAL does not represent the voice quality, and is not related to the codec used. You can change codec but that won’t impact the BER… indeed, the rxqual only represents the BER.
    In other words, changing codec do not modify the RxQual measured.
    (but it does modify the FER!)

    Regarding your problem, i suspect:
    1/ higher timeslot usage –> higher frequency usage –> higher interference (indeed, before HR was more used, so less ts were busy overall)
    2/ depending on your system capabilities : the HO Quality and HO interference are not triggered at the same RXQUAL threshold than before. (in some systems, it might be possible to tune different thresholds for AMR FR, AMR HR and non AMR calls). By increasing the threshold of HO Qual, you actually force users to stay in the “bad quality” cell. So the average rxqual in your network is increased.
    3/ last possibility : DTX and PC are not activated for AMR-FR or non-AMR-FR, but they are activated for HR.

    I can’t think of anything else… After that, you might have to suspect AMR “implementation” in the system itself, or in the MS.

    Cheers
    pix

    #66394 Reply
    Mickey
    Guest

    Thanks Pix for quick respond….

    FR & HR is actually AMR HF & AMR HR

    1. For High TS Usage i will comeback after some analysis.

    2.Downlink receive quality Ths is 39(i.e -71), Downlink interference quality offset is 1(Check the relation between level and quality to
    judge whether there is any interference in service
    judgment channel when handover occurs in the cell).

    3.We are using ZTE system & DTX Enabling is available only for UL/DL and it is enabled. It dosen’t give like DTX FF/HR or AMR

    I am also looking for codec usages & will share the results.

    Tell me if there can be any issue with DTX(any delay in measurements), Also what are the best codec’s to be used for HR & Full Rate( How to judge codec selection)

    #66395 Reply
    Ayat
    Guest

    hello

    also we arrange to control HR in our network , and ZTE check RX Qual as a reference to check the changing of HR
    we notice that the HR is reduce and RX Qual also improve but when i reed pix’s answer i doubt in ZTE reporting

    Pix Could you confirm that HR related to MOS not related to BER , RXQUAL

    #66396 Reply
    pix
    Guest

    Hi ayat,

    I do have a doubt when re-reading myself.
    HR is using weaker encoding, so it’s more difficult for the decoder to properly retrieve the speech frames. However the BER is the number of bits that were not properly received on the radio layer. It does not depend on the encoding.
    So what i say before sounds true, still.
    But there is perhaps a second effect of the HR that will degrade the RXUAL & BER measurements. I’ll investigate this and will do some tests myself. If you’re seeing it , then it must be true ! 🙂

    cheers
    pix

    #66397 Reply
    pix
    Guest

    Hi,
    I did a short test, i didn’t see any change in terms of rxqual and even dcr, with a HR load = 100%.

    I need to find a more interfered area, to be sure….

    Regards,
    Pix

    #66398 Reply
    LEMAURE
    Guest

    Hello!

    check on the settings HOQUALAMRFR and HOQUALFR threshold. As more calls are using these codecs make sure HO settings are aligned (or lesser than those of AMRHR/HR) accordingly

    #66399 Reply
    Ayat
    Guest

    Hello pix
    I will try to share some sample with you

Viewing 8 posts - 1 through 8 (of 8 total)
Reply To: DL RxQuality Degraded after HR Reduction
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