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PROBLEM IN IMMIDIATE ASSIGNMENT

Viewing 15 posts - 1 through 15 (of 20 total)
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  • #53095 Reply
    Ajay
    Guest

    We are using SIEMENS EQUIPMENTS with BR9. Recently we have upgrade our software from BR7 to BR9. After upgrading we are facing problem with micro BTS BS82II. The site is connected via SATELLITE. When link is down and after it comes up then the site will work for couple of minutes but after then only signalling is there but no traffic. Immediate assignment is very low. We check the statistics and found like there are lots of SDCCH drops due to T_MSRFPCI expiry. Could anybody give some solution regarding this. Thanks in advance.

    #53096 Reply
    uzn
    Guest

    Hi ajay!
    could you specify the problem. Since as i know immediate assignment is phase to allocate SDCCH channel and in this phase there is no SDCCH drop since SDCCH hasn’t been allocated. SDCCH drop is happen in case SDCCH has been occupied.

    rgd//uzn

    #53097 Reply
    pix
    Guest

    UZN,

    beware : the definition of a “sdcch drop” changes depending on the vendor. What Siemens call a SDCCH Drop might be considered as a SDCCH assignment failure in alcatel… you never know.

    #53098 Reply
    uzn
    Guest

    hi pix,
    thanks for your information. This is really a new for me, since i have worked in 2 vendors and both give the same definition of immediate assignment.

    #53099 Reply
    Pix
    Guest

    Hello UZN,

    I remember a thread in this forum where we noticed such a confusion between 2 vendors, sdcch drop vs. sdcch assignment unsuccess. But maybe i don’t remember correctly. Other times (many many times), it’s the optimizer himself that makes the confusion ๐Ÿ™‚

    With which vendor have you worked with ?

    #53100 Reply
    uzn
    Guest

    i have been working in E///, last year i joined to NSN for 2 years.

    #53101 Reply
    pix
    Guest

    thx

    #53102 Reply
    Hi uzn
    Guest

    Yes immediate assignment is phase to allocate SDCCH channel but when MS request for channel to BTS then BTS will send message CHNRD(Channel Required) to BSC and then BSC send message CHNAV(channel activation SDCCH) to BTS. Here BSC will increment counter for attempted SDCCH and IMMEDIATE ASSIGNMENT as well.When BTS receive CHNAV message from BSC then it sends CHNAK message to BSC and T_MSRFPCI counter is started. Now BSC will assign immediate assignment message to BTS. If BTS does not receive immediate assignment message time between T_MSRFPCI then the call gets dropped. This means that SDCCH and IMMEDIATE ASSIGNMENT will be dropped. This means that yes there is SDCCH drop during immediate assignment. Please correct me if I am wrong.
    We got the solution. Actually what happened was that, When we migrate to BR9 then there was bug in software. T200 timer handling capability was only 500msec but actually we were having 620 msec delay in abis.

    #53103 Reply
    pix
    Guest

    ajay,

    then yes, with all due respect, your description is not correct : there is no dedicated connection yet, Immediate assignment is still considered as part of the sdcch assignment phase. Therefore the problem you are describing is a sdcch assignment failure and not a sdcch drop ๐Ÿ™‚

    Glad you found your problem ๐Ÿ™‚

    #53104 Reply
    Ajay
    Guest

    Thanks Pix for correcting me. So in our case we are having two different cases.
    First case is Immediate Assignment Failure Rate which is because of BTS not receiving CHNAV message from BSC or BSC not receiving CHNAK message from BTS as I have said previously which is SDCCH assignment failure.
    Second case is SDCCH drop due to T_MSRFPCI which is the case after Successful Immediate Assignment.
    Thank you once again.

    #53105 Reply
    Rain
    Guest

    What is the possible cause of SDCCH Drop due to Abis Failure

    #53106 Reply
    pix
    Guest

    huh… Abis failure ๐Ÿ˜‰

    #53107 Reply
    mamun
    Guest

    what is the cause of traffic abnormal release ? can anybody explain plz. ?

    #53108 Reply
    pix
    Guest

    mamun,

    call drop!
    due to..

    poor coverage
    high interference
    faulty hardware (in BTS, Abis, BSC, Ater or TC)
    failure during handover

    #53109 Reply
    Masud
    Guest

    would you plz tell me any one why SDCCH is drop?

Viewing 15 posts - 1 through 15 (of 20 total)
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