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SDCCH dimensioning for HR environment

  • This topic has 154 replies, 1 voice, and was last updated 15 years ago by pix.
Viewing 15 posts - 91 through 105 (of 155 total)
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  • #35553 Reply

    Hi Ramajayam cyr,

    I am talking about what could be the the reason not to use dualband but two separate cells on both bands with no SDCCH in 1800. In dence urban the distance between cells is small so 1800 serves almost the same area as 900 (except deep indoor)

    #35554 Reply

    We have Alcatel BTS use Sattelite Abis. please tell me:
    Do we need use GPS to synchronise or not?
    Now we set Free running, I don’t know about stabilisation.

    #35555 Reply

    Hi Hungtran (still in vietnam ? 🙂 )

    satellite BTS shall be set to free running. it is stable. Some timers in the BSC shall be set to special values, to take into account the delay due to the distance earth-satellite-earth.

    T3168 = 1.5s
    ROUND TRIP DELAY = 700ms
    T GCH CORR = 700ms
    T GCH ESTAB = 1000ms
    BS CV MAX = 15
    T3192 = 1000ms (if DRX TIMER MAX > 0 or EN DELAYED DL TBF REL = ENABLE)

    But please liase with your TPM so he can confirm you those values.

    #35556 Reply

    Hi after implementin AMR half rate in our network TCH and SD completion rates has gone very bad in our network for sites carrying more than 30% of AMR half rate traffic.

    Also if i enable the FACCH call setup parameter in BSC ,will it reduce the SD congestion .And also if we make trx signalling for such sites to 48kbps.Is going to help us

    #35557 Reply
    Baleseng R Jubane

    After implementing Synthesize Frequency Hopping, we experienced a slow call setup and Cell reselection. How do I improve this. Please help

    #35558 Reply

    hi balenseng,

    frequency hopping and a slow call setup/cell reselection are probably not related. On which indicators are you basing this study ?

    Is it statistical or only drive-tests results ?

    #35559 Reply

    Hie Pix,

    This is experienced in field, during drive test and just normal call set up, just like a subscriber.

    When you make a call it takes close to a minute for a call to set up.

    Also I have slow handovers.During drive test we found that a work cell takes too long to Handover to a better cell, even though the quality is good and RxLev good, with neighbours well defined.

    #35560 Reply


    I would recommend you also have a look to QoS statistics, to confirm that there is actually a difference between “before hopping activation” and “after hopping activation”. you might get a clearer picture of what is really going on, and whether the issue occured right at the time of the hopping activation or not.

    however, if you’re sure of yourself, you must contact your vendor (which brand is it ?), so they can check the frequency hopping is working well in your release.

    frankly, unless there is an issue in your network software, because i can’t see how frequeny hopping can relate to call setup and handover delays… but i don’t know… i simply never experienced that or heard about it, and i can’t even imagine what could be the problem.

    good luck ! and tell us which vendor is it…

    #35561 Reply
    Ravi kant

    hi ran,

    I am having call drops when my rx lev is around -40 and rx qual is also 0-3, suddenly…
    Is it someway related to the difference in the power at which the two trxs in the same sector are radiating…
    How much power difference in db is acceptable between the same trx of the same sector?

    I wud thank if any body can answer my question.

    #35562 Reply

    hello ravi,

    i think you’re referring to a possible issue when using the power control and you’re locating very close to the BTS. The power attenuation beween different TRX and even different timeslots of the same TRX can be up to 30dB…

    Normally, it should work fine, but if you’re having a doubt, why not simply deactivate the downlink power control ?

    #35563 Reply

    In Alcatel system: HO from G900 cell to G1800 cell always has bad performance, low HOSR with failure due to ROC (Return to Old Cell). But HO from G1800 cell to G900 cell is always OK (HOSR approx 98%)
    We ‘ve got no solution for that. Would you help us to solve this problem

    #35564 Reply
    Baleseng R Jubane

    I use a GSM 900 Ericsson systems, but suddenly there are slow handovers and high cell re-selection. Dynamic MS and BTS Power control are both activated.
    This causes inteference problems as a mobile take long while camping on a worst cell.

    #35565 Reply

    hi baleseng,
    Pls check for any inter msc HOs.,that come and also ur handover default time,check for any physical changes too like TILT,and height changes of sites in the meantime.Check for C1 and C2 too.


    #35566 Reply

    hello tranhung,

    what is the cause of HO failure G900 to G1800 ?

    if it is congestion, then i would say it is normal. the preferred band HO will push MS from G900 to G1800, leading to HO failure due to congestion. It is a normal behaviour, a “wanted” behaviour (preferred band HO will push the MS…)

    if it is “radio failures”, then i would check your HO tresholds, especially the l_rxlev_cpt_ho and the traffic condition (any load ?) to perform the “preferred band ho”.

    #35567 Reply
    Nguyen Duc Lam

    Hi all,
    I am using BSS of Alcatel. For 3 years, I can not improve Handover success rate (from 900MHz to 1800 MHz_ macro to macro cell). I have tried many times and many ways but not. The unsuccess cause is radio fail (no congestion). I checked performace hourly for many day and found out that sometimes they (Cells) work well and sometimes they do not.
    Can you give me any recommendation?.
    Thanks a lot.

Viewing 15 posts - 91 through 105 (of 155 total)
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