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Assignment request timer

  • This topic has 11 replies, 1 voice, and was last updated 10 years ago by Basit.
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  • #63015
    No TCH

    Hi, everybody!
    I have a noobish question: After expiry of what timer/set of timers BSS declare Assignemt failure with No TCH available?
    No queing allowed.



    When the BSC doesn’t have any TCH available and queuing is not activated, there is NO TIMER. The rejection is immediate.
    But the BSC might or might not send the rejection message to the MS. (this is a parameter called “immediate assignment reject”)
    if reject is not sent, the MS will just wait for a very short while, and send again another channel request. The delay between 2 consecutive channel requests is very short.

    if reject is sent, then the MS will wait for a longer while (timer is specified in the reject message)., then resend another channel request.

    Assignment failure due to congestion are usually immediate, without a timer.
    Timers are used to detect a radio failure.
    TCH assignment can also be failed due to poor radio link, and in this case, it is the expiry of a timer that triggers this event.

    No TCH

    Thanks, Pix.
    That kind of timer would be very useful in my opinion ๐Ÿ™‚
    and from your answer comes another question: Second channel request message? I have never nothised that MS ever sends another channel request message after BSC is declared that there is No radio resources available situation for TCH assignment request for MOC/MTC.
    And continuing friday crusifiction ๐Ÿ™‚ – Is it possible to delay assignment request message sending? Yea I know its a strange question but I am obsest with improving CSSR in VERY congestioned cells because I think that mechanisms that are used today can and must be improved (I am not crazy, my mom made me checked :D)
    OK, now the full story: We have very congestioned cell, no queing, no prioratisation, no traffic ho, nothing but forced directed retry HO. Sector is DCS and around it is large number of GSM and DCS sectors. GSM all are fine but DCS all are congestioned. I am setting up call in DCS, for most of phones Directed retry kicks in but are many phones whose due to internal delays etc are possible to send only one Measurement report and it is obviously not containing SI5ter list:) and call is dropped. So question is how can I delay MOC/MTC process in those cells till the moment 5ter arrives and DR HO is possible to GSM?


    you seem obsessed with it, which is probably why you are here… but do not worry, we’re all gsm maniacs here. You are among … weirdos. Welcome home.

    Your problem is that you want a timer to keep the BSC waiting for a while before rejecting the MS.
    In other words, you want the MS to queue. And while the MS is queueing, it will send measurement reports, and the BSC might detect a possible directed retry.

    So… set your T11 = 6 seconds or more, BTS Q LENTGH = 6 calls or less, and let the FDR rock’n roll your cell.

    Your other questipon : delay the sending of the 2nd channel request : i answered that in my previous post : immediate assignment reject… activate this feature, you’ll see you can change timers (WI_OC, Wait_Indication, etc)

    No TCH

    Thanks again Pix.
    A Immediate assignment reject – this option probably Siemens doesn’t provide, at least I havent seen it anywhere.
    And in the end I understand that there is no possibility to delay Asiignment failure without activisation of some addition features because for us queing is also an extra that is not activisated.
    Too bad, 3GPP takes all the fun out of basic problems ๐Ÿ™‚


    one night sleep and i notice that i just misguide you…

    the immediate assignment reject is a feature that intervenes during the SDCCH Assignment !

    So your problem is : the MS has the sDCCH but can’t get a TCH, because it is rejected too early.

    So my final solution was actually related to your problem anyway :
    The TCH Queuing is a VERY basic feature that MUST be activated ALL the time EVERYwhere. No question about it.

    On the other hands, I just forget what happens when the BSC can’t allocate a radio channel to the MS. It certainly indicates the rejection in a downlink SDCCH message, but I forgot the name. It is immediate rejection anyway, there is no timer (the only available timer is T11, which is the queueing timer… so that’s the timer you are looking for…)

    I really hope I didn’t confuse you too much with my stories about “immediate assignment”…


    our vendor has

    Assignment period

    This parameter is T10 timer. It supervises assignment process as follows:
    Timer Start: T10 timer starts when MS receives ASSIGNMENT COMMAND message.

    Timer Stop: T10 timer suspends when MS receives ASSIGNMENT COMPLETE and ASSIGNMENT FAILURE messages.
    Action Overtime: If this timer is overtime, BSC will send BSSAP ASSIGNMENT FAILURE message to MSC.


    Hi everybody.
    what is best value for T10 & T3101 timers in Nokia BSC?

    Thanks a lot.


    does anybody knows how we can modify T11 in NSN???


    A3129B:Failed Assignments (First Assignment, Terrestrial Resource Request Failed)
    A3129C:Failed Assignments (First Assignment, Assignment Timed Out)
    A3129D:Failed Assignments (Reconnection to Old Channels, Reconnection to Old Channel in Assignment)



    A3129D:Failed Assignments (Reconnection to Old Channels, Reconnection to Old Channel in Assignment)

    What Things Need to Check.
    Most of The Assignment Fails At This Part


    CSSR is degraded due MAAR.can anybody tell how we can improve the MAAR in Huawei.

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