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SDCCH dimensioning for HR environment

Viewing 15 posts - 31 through 45 (of 155 total)
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  • #35493
    Garry !!

    Hi Dina,

    Could you just elaborate, what was the earlier system which was swapped to Nokia ?

    For SDCCH drop rate, Nokia takes sum of all failures occuring on RF/Abis/Aif/LAPD/BTS/Usr/BCSU and some of them during handovers. So it is quite high. I hope you have this in mind.

    There is other reason too, but this is due to MSC settings and the drop rate would be high on the PLMN boundary sites.

    Which one relates to your SDCCH drop ?

    Best regards,

    Garry !!


    dina, I’m on Nokia BSC which is connected to Ericsson MSC, there are several special settings on Nokia BSC for Ericsson MSC, but it’s for A interface, not for Abis/Air… SDCCH have no connection with NSS part of the network…

    Avinash Sharma

    hi all,
    i am new to the field of GSM, i am working on NOKIA BSS, recently there was a major outage due to faliur of the optical backbone, when the system was restored i found that the LAPD of most the trx’s and transcoders where not restored and where still blocked i had to bring them up manually,
    i am wondering what could have possibly went wrong is it a problem with the BSC. i am working on NOKIA BSC 3i s11.


    Hi Folks,

    I am new to GPRS/GSM stuff,

    I have one question, if we use combined CCH for both GSM and GPRS
    how excatly these CCH messages are trasmitted from BSC to TRX.

    In GSM we use LAPD to transfer cch
    messages to TRX and from there TRX will schedule those sgs to transmit on air, what happens in
    GPRS??, do we have to send RLC/MAC
    blocks on LAPD(wild guess)?

    And another one is, I believe that
    in GSM, TRX will take care of interleaving and framming ..etc.

    who does scheduling of the messaages on air In case GPRS



    Avinash Sharma, such things sometimes happen, it’s not only your problem, we also sometimes have such problems, it may happen if transmission dropes down and only way to solve problem is to unlock LAPD manually. I had such problems on BSC2 with S9, currently I’m working on BSC3i with S10.5 and sometimes(very seldom) have same problems

    Avinash Sharma

    hi Alexander,
    well then i think it is a electra case and needs to be taken care of i think this never happens with other systems like ericssion or nortel so there is something seriously wrong with the system, any one working on ericssion or nortel plz reply if u ever face such a problem.


    I don’t under stand the SDCCH drop is high due to Others i.e including the hardware Issues and increase the SDR_1a also.
    the Functional failure rate is high means sdr_1a should increase and what are the resions for functional failure rate.




    Does somebody have a summary about call stablisment: BCCH, SDCCH…etc…normally I configure it in BSC but I would like to have a better understanding…



    Iam a new GSM engineer in mobile company
    i ask about the main KPI in MSC System , IN and SMS, thanks


    Yes jaddu
    you have to send RLC/MAC header on each packet.
    & Interleaving & coding is according to class & coding scheme for MS.
    & CCH is transfering through LAPD under the datalink layer.


    Hi everybody!
    I have a problem with some cells had high SDCCH drop dute to low SS. some cell in LAC border but enough neighbour and no fault in hard ware.
    We use Ericsson equipment.
    Thank alot!


    hi ayat,

    There’s a lot of KPI should be considered to monitor the network, for NSS it’s divided into 3 part which are : 1. Performance KPI which included ASR (Answer to Seize Ratio), NER (Network Efficiency Ratio), LUSR (Location Update Success Rate), PSR (Paging Success Rate), Inter MSC HO Success Rate, Security Operation Success Rate, PDD. 2. Utilization KPI which included Signaling Load, Trunk Occupancy, Processor Load, VLR Subscriber. 3. Availability which inculuded MSC/VLR Availability, Trunk Availability and Signaling SS7 Availability. For IN and SMS i just know a little bit such as : IN Success Call Rate, SMS Success Delivery Rate. Hope it will help you..

    ali mohammad

    hi all,,,
    what about the SDCCH Congestion and TCH Congestion?


    what does the paging success rate on a bsc mean?


    ali moh’… it means that all the radio channels TCH / SDCCH are fully utilized and that a certain amount of calls is rejected because they have no resource available in the cell.

    for instance : TCH congestion rate of CELL A = 3.5% means that 3.5% of the subscribers that tried to perform a call in the cell A were rejected (= blocked call OR the call is handover to a neighbor cell).

Viewing 15 posts - 31 through 45 (of 155 total)
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