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SDCCH dimensioning for HR environment

Viewing 15 posts - 46 through 60 (of 155 total)
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  • #35508 Reply

    raghdu, the paging success rate is a bit tricky… in my experience, the only paging failure might be caused by congestion in the paging channels of the cells or congestion in the BSC itself.
    In Alcatel system, we do not count those failures, so we don’t have a paging failure rate (or a paging success rate), but rather a PAGING LOAD (amount of paging performed during one hour / capacity of the PCH channels).

    I personally don’t think it is possible to compute a paging success rate, unless you know about the PCH congestion in each cell. Does your system provide this information ?

    You can work with the PAGING LOAD though : you just have to set a paging load threshold (let’s say 10%) and if the paging load is greater than 10% it means you’re in overload 😉

    #35509 Reply

    Hi All,

    We r running GSM 900 NW on NOKIA BSC 3i. Some days back, we changed some sites having more than 60% TCH blocking into Half rate. The traffic increased considerably, and TCH Blocking reduced, but we came across a new problem. You cannot make calls from those cells where half rate has been implemented using Nokia 6630, N series and other high end mobiles. I think it has something to do with the 3G capability of these sets. Can anyone help or have any more info.

    #35510 Reply

    All the phones you mention does not support Half Rate codec. They have AMR-HR codecs.

    #35511 Reply

    Hi Everyone,

    Pls clarify me what are the probable solutions to find the reasons for HIGH TCH BLOCKING AND HIGH SDCCH BLOCKING along with there solutions,if any in particular to nokia networks.


    #35512 Reply

    Hi, We’ve implemented FLP in one of the Network in our country. Everything is working properly except the SDCCH drop due to other reasons has increased.

    Do you have any solution to trace out the SDCCH drop due to other reason?

    Pls reply.
    Thanks in advance.

    #35513 Reply
    Tech Man


    Some of the nokia N series handsets as well as models such as 6630,6680,6681 do not support normal HR but work well in AMR-HR

    #35514 Reply

    I have the below problem at one of site. Below is some of the information extracted from BTS Error Log:

    The probelm is high Handover ping pogs. We replaced one TRU in Sector 3 because sector 3 couldnt handover to other sectors.


    FAULT: ATSR:0, cease ec1 TERR LINK 6

    TRACEH:Incorrect SAPI : 1
    TRACEH:Incorrect SAPI : 5 OR 6

    #35515 Reply

    remote transcoder fault may come due to transmission problem between BTS and BSC/TRC. You can check LAPD statistic of that PCM.

    #35516 Reply

    Hi Everyone,

    Pls clarify me what are the probable solutions to find the reasons for HIGH SDCCH fail along with there solutions,if any in particular to alcatel networks.


    #35517 Reply

    in ower network the maximum half rate pentration is 10%~15%.HR work on drop call increase

    #35518 Reply


    sdcch failures, 3 possibilities =
    1 – radio problems (low coverage, interference, ghost rach, timer issue …)

    2- congestion

    3- BSS (hardware failure, VERY rare in this case)

    find which is your current issue, then analyse the problem with drive test or advanced QoS analysis. Keep in mind that average SDCCH failure = 20% in alcatel system, and up to 50% if going through satellite Abis.

    #35519 Reply

    Hi Pix!
    Thank for you answer, but in our network(Alcatel BSS), about half of cells have indicator SDCCH_asign_fail are greater than 2%.Most of them due to radio.I don’t know how to threshold can accept? I think 20% to be very high

    #35520 Reply


    In Alcatel BSS, the SDCCH failure rate threshold is 20%.

    Below 20% : it is good.

    Subscribers will not “feel” anything wrong with your network, it is a perfectly normal network.

    Trust me.

    Now, you have to check the SDCCH Preparation Failure due to Congestion. If that is higher than 2% or 3% (at busy hour), then you have SDCCH congestion problems.

    #35521 Reply

    Hi Pix!
    SDCCH set-up is involved in the two main services:

    *Service requests (MOC, MTC, SMS,…)

    *Location update
    *IMSI attach/ detach
    If SDCCH_asign_fail rate is high, customer fell to be bad. for example: can’t makecall, SMS, LU…can you give me SDCCH-asign_fail_rate indicator of some good network use Alcatel’s BSS?. Thank alot

    #35522 Reply


    Those failures rates do not represent the reality, and the subscriber will not “feel” the failure at any point ! It is fully transparent for the subscriber.

    For dense urban sites, the failure rate is about 5% to 10%, and for rural sites, it is about 20% / 30%.

    It is the same in all Alcatel networks, B5, B6, B7 and B8. And I’ve worked on many Alcatel networks… It’s up to you to trust me or not, but you can always contact RTAC.

    Which country are you in ? Hungtran sounds Vietnamese ? I’ve been in Vietnam too, for all three operators (Vietel, Mobifone and Vinafone) 😀

Viewing 15 posts - 46 through 60 (of 155 total)
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