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call drop due to expiry of T200 timer

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  • #54393 Reply
    krish
    Guest

    ok pix,pan thanks for this but this entire process will continue atleast on some channel after immediate assignment so which one that channel? And if i will modify the t200 on bsc level than on bts level it will automatic update?

    #54394 Reply
    Pix
    Guest

    Krish,

    T200 is not related to a GSM procedure. Every time something is sent on Abis, an ACK is awaited. It won’t improve the call setup time, unless you have a lot of LapD retransmissions, usually.
    You can check lapd retransmission with a qos indicator.

    If you update the T200 in BSC, I don’t know if the BTS is going to be updated as well. It depends on your system. Is it alcatel ? In this case, check your parameters dictionary, it should be explained there.

    #54395 Reply
    Pan
    Guest

    Dear, KRISH!
    Immediate Ass message is sent om AGCH. On this channel only unacknowledged operation is possible. There is no T200 in unacknowledge operation (see 04.05, 04.06).
    In our BSS T200 is set only one time – for all BSS – not separately for BTS and BSC.

    #54396 Reply
    krish
    Guest

    ok thanks great discussion on this topic

    #54397 Reply
    Pan
    Guest

    Your are always welcome:)

    #54398 Reply
    krish
    Guest

    hey pan last discussion on this t200 first ms will send channel request thr rach and it will get reply thr agch after imme assignment and also ms gets sdcch with agch and after this t200 start so by increasing t200 there will be chance of sd blocking…

    #54399 Reply
    Pan
    Guest

    No, krish!
    All normal events on radiointerface must be ended within T200. T200 timer expiring (when it’s setting is right – according 04.06 or as default in your system) is exclusive situation and should be viewed as error.

    #54400 Reply
    krish
    Guest

    not getting exactly i mean abt sdcch blocking after imme assign and increasing t200 value from 280 to 1000 ms

    #54401 Reply
    Pix
    Guest

    Pan,

    which messages are acknowledged based on t200 on lapdm ?

    i assume it’s done only for the sdcch and sacch?
    and the ack is sent in the layer 2 header of the message ?

    #54402 Reply
    krish
    Guest

    i think sacch will not come in pitcure

    #54403 Reply
    Pix
    Guest

    Krish, I’m done with pictures, now i’m reading books with words in them.
    Give them a try…

    #54404 Reply
    krish
    Guest

    hey i want to know if we increase the timer value upto 1000 ms then if entire process is on sdcch then there will be chance of sd blocking….

    #54405 Reply
    Pix
    Guest

    Krish,

    Are you working on a live network ? You know, the easiest way is to change the parameter for few hours, check the impact, and roll back.
    That’s the easiest way to see what happens when you change the parameter.

    Please keep us informed about your findings 🙂

    Thanks, bye
    Pix

    #54406 Reply
    Pan
    Guest

    Pix
    Acknowledged mode of operation is supported by SDCCH, SACCH and FACCH.
    I think that all MM and CM Layer3 messages are transfered by Layer2 in acknowledged mode.
    Remote data link entity acknowledges a received frame by means of I-frames or S(supervisory)-frames.
    Acknowledgement (N(R) – last properly recieved frame) is contained in control field of I- or S- frame.
    Krish
    If you will increase T200 there will happen nothing. What is your objective?

    #54407 Reply
    krish
    Guest

    ok i will share the analysis and now can we share some knowledge on edge ,gprs

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Reply To: call drop due to expiry of T200 timer
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