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LU Timer & SD Drops

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  • #62341 Reply
    DangerousMinds
    Guest

    Hi all,

    The timer for periodic location updates was set as 30 minutes on cell level on our network. Since we realized 30 mins is too less a time for the periodic LU to take place, we increased the value of the timer to 4 hours. However, that has led to a sharp rise in SD Drop Rate. The SD Traffic has obviously come down as well. What could be the reason for the SD Drop degradation?
    Thanks/

    #62342 Reply
    Pix
    Guest

    Dangerous Minds,

    Are you sure the timer was set to 30 minutes ? Not 30 x 0.1 hour ? (= 3 hours)
    The unit is usually deci-hours ( = 0.1 hour)

    Increasing from 3 hours to 4 hours will decrease your SD Traffic. There is less “SD requests”. However, the SD drops may be as numerous as before, because the SD drops are more often linked to Call setup or SMS, or Location Area update due to LAC change (not periodic update).

    SD drop / SD request ==> SD drop rate increases.

    Cheers
    pix

    #62343 Reply
    DangerousMinds
    Guest

    Hi Pix,

    Yes, I think you are spot on ๐Ÿ™‚ The reasoning makes sense. Yes, the LU Timer was initially set to 30 minutes (Nokia 2G default). But is there any other way to reverse this SD Drop degradation trend without the LU timer reversion ?!

    #62344 Reply
    Mania
    Guest

    Hello DAngerousMinds,
    First of all please check if the SDDrops Number has increased or not.. SDR might be increased as you have decreased the attempts. so if the denominator drops the radio would rise.
    Probably as the attempts reduced were periodic location updates and they had lesser chances of generating drops. now the attempts have decreased but drops have not decreased correspondingly…
    else we can investigate

    #62345 Reply
    DangerousMinds
    Guest

    Thanks for your reply, Mania.

    Yes, the SD drops have actually reduced! But the attempts have reduced by, like, 50%, and the drops have not reduced by the same raio, so the overall SD Drop rate has gone up from 3.1 to 4.5% network level. Is there any other parameter which we can modify to cater for this?

    Thanks/

    #62346 Reply
    Pix
    Guest

    30 minutes is insane…
    A network with a T3212 set at 30 minutes would just implode under the gigantic load.

    I’m pretty sure Nokia’s default is 3 hours ๐Ÿ™‚

    It’s very funny : you just decreased the number of SD drops, probably reduced the SD congestion and the VLR/HLR load, and yet you are not happy. Sometimes it is dangerous to focus only on the corporate KPIs ๐Ÿ™‚

    If you want to decrease the SDCCH drop rate, you’ll have to focus on interference, coverage, path balance, … you’ll probably have to work on a cell per cell basis. Extract the worst cells (highest number of drops), and see what is the main SDCCH usage, see why it drops, etc…

    #62347 Reply
    DangerousMinds
    Guest

    Hi Pix,

    yes i guess you are right ๐Ÿ™‚ … this rise is not user perceived, and it is good for the network, but it will be very difficult to convince my management! Do you know what is the relationship between the LU Timer on the BSS and its counterpart on the core end? I think the value of core LU timer is 6 hours, so what impact does that have?

    Thanks for your help.

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