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Thread: Mute call on 3G

  1. #21
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    Default Re: Mute call on 3G

    hello ,
    after impleme ntation of the parameters RTW is decreased visibly from net act .
    We have noted decreased amount of complaints.
    BUT problem is not solved. On the other hand that clearly indicated that problem is UL interference.
    Honestly my fear is that NSN algo inside hsupa scheduler does not work perfectly.

    here is an answer form one of the NSN Rnd guys :

    The issues with configuring PrxMaxTargetBTS with high values are:

    - The Node B HSUPA scheduler will target PrxMaxTargetBTS so once there are a few HSUPA users in the cell, then the cell will experience high uplink interference increases and uplink coverage will shrink.

    - The Node B HSUPA scheduler will become less accurate in terms of being able to target PrxMaxTargetBTS. High values of PrxMaxTargetBTS correspond to operating on the steep part of the exponential load curve. This makes it more difficult for the Node B to be accurate with its estimate of interference floor increases. The variance of the uplink interference floor will increase. The Node B may over-schedule during one instant, then under-schedule during the next instant. This may not be visible from the RNC due to the averaging of the PrxTotal measurements. UE may experience increases in their resource allocations, then decreases in their resource allocations as the Node B attempts to target PrxMaxTargetBTS.

    SoThe issues with configuring PrxMaxTargetBTS with high values are:

    - The Node B HSUPA scheduler will target PrxMaxTargetBTS so once there are a few HSUPA users in the cell, then the cell will experience high uplink interference increases and uplink coverage will shrink.

    - The Node B HSUPA scheduler will become less accurate in terms of being able to target PrxMaxTargetBTS. High values of PrxMaxTargetBTS correspond to operating on the steep part of the exponential load curve. This makes it more difficult for the Node B to be accurate with its estimate of interference floor increases. The variance of the uplink interference floor will increase. The Node B may over-schedule during one instant, then under-schedule during the next instant. This may not be visible from the RNC due to the averaging of the PrxTotal measurements. UE may experience increases in their resource allocations, then decreases in their resource allocations as the Node B attempts to target PrxMaxTargetBTS.


    So as a next step we will reduce parameter PrxMaxTargetBTS from 15 to 10 db . By that we will reduce hsupa throughput for 15% but expand congested cells in order to prevent UL interfernce.

    Also 2 ms TTI range shell be shrinked by NSN.
    This will also affect hsupa throughput but can prevent situations that 2 ms TTI can starve UL .

    RNCHSPA- CPICHRSCPThreEDCH2MS WCEL 130 125
    RNHSPA- CPICHEcNoThreEDCH2MS WCEL -10 -6


    Anyway it is optimization capacity vs quallity.
    Good thing is that in RU30 PIC&FDE could compensate throughput loss..hopefully!

    keep you updated.

  2. #22
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    2010-12-01
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    Default Re: Mute call on 3G

    Hi, anybody finally solved this problem? Maybe you could share final solution?

  3. #23
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    3 out of 3 members found this post helpful.

    Default Re: Mute call on 3G

    Mute call.rar

    Hello,

    it was problem with UL excessive RTWP and after we have decreased it from 15 down to 10 db it was dramatically solved.
    NSN also recommends 8 db .
    usually networks have 8-12db in practice but I think that 10 is optimal.

    I will request for further deep technical explanation of the slide 7 because NSN has pretty bad implementation of HSUPA scheduler ( not accurate at all). I compared with ZTE in my network and for ZTE I have similar parameter to PrxMaxTargertBTS of 20 db and there is no any mute call issue. Checking ZTE WBTS RTWP online logging i see that scheduler cut off interference to ROT .

    Kind Regards,

  4. #24
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    2010-02-16
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    Default Re: Mute call on 3G

    nice sharing,
    should to try in our network.


    Quote Originally Posted by djordjebeg View Post
    Mute call.rar

    Hello,

    it was problem with UL excessive RTWP and after we have decreased it from 15 down to 10 db it was dramatically solved.
    NSN also recommends 8 db .
    usually networks have 8-12db in practice but I think that 10 is optimal.

    I will request for further deep technical explanation of the slide 7 because NSN has pretty bad implementation of HSUPA scheduler ( not accurate at all). I compared with ZTE in my network and for ZTE I have similar parameter to PrxMaxTargertBTS of 20 db and there is no any mute call issue. Checking ZTE WBTS RTWP online logging i see that scheduler cut off interference to ROT .

    Kind Regards,

  5. #25
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    2009-03-31
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    Default Re: Mute call on 3G

    Hi,

    We are having the same problem here and we are implementing some of the suggestions that are in djordjebeg's presentation. The problem is that when the mute periods occur, the BLER goes to the roof even though the EcIo and RSCP levels are optimal. Normally the mute periods are 5 seconds long.

    Do you have an update on this issue or an additional recommendation?

    Thanks!

  6. #26
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    Default Re: Mute call on 3G

    Hi Experts

    Facing a similar problem this side. Does anyone have a final solution to this problem?

  7. #27
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    Default Re: Mute call on 3G

    Quote Originally Posted by brianm View Post
    Hi Experts

    Facing a similar problem this side. Does anyone have a final solution to this problem?
    Hi brianm,

    After a lot of troubleshooting the problem was an incompatibility between RNC software version and Node B software version (we have RU30 RNC and RU20 node B). At least this was the problem in our network. You should check NSN Technical Note TS-RNC-SW-182 - H-RNTI allocation algorithm change in RU30 and implement it.

    Hope this helps.

  8. #28
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    Default Re: Mute call on 3G

    You are right that is one of the problems for sure.
    BUT even when you align software the problem will remain somehow.
    the reason is CM delayed. UE enters CM and cancels it--> RNC sends exit CM to the node B but delays Measurement control commend to UE--> UE is still in CM for a while while Node B it is not--> radio link failure happends
    Correction in RN6.0.2.3 mid of may ( 16.5.2013 expected GA)

    beside of that the is one more issue in RU30. ISHO attempts fdue to DL DPCH are increased 4-5 times ( bug in Node Bs power calculation ). That causes mute calls as well. Suggestion is to disable DL DPCH cause for MRAB and Voice.

    Another issue I am investigatoing now is that UE simply after RNC sents HO command cannot synch to 2G and gets stucked between 2G and 3G --> mute call. It could be that some Ue cannot read properly HO command but I am in mid of investigation and I'll info m you about results.



    regards,
    djordjebeg

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