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call drop due to expiry of T200 timer

Viewing 15 posts - 46 through 60 (of 69 total)
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  • #54408 Reply
    Vanderley
    Guest

    Guys,
    correct me if I am wrong but after expiry of T200 the only thing that happens is sending again the message (for example ASS CMD on SDCCH). The channel is released with the error indication after N200+1 repetitions.
    So yes the chance for SD blocking is higher if you increase the T200, because you keep the channel busy (for total of (N200+1)xT200…and there is no MS to respond.
    Here is the Siemens opinion:
    To achieve an optimum
    radio interface performance (from the subscriber’s point of view), the
    timer values for T200 should be set in such a way that
    – a Um layer 2 frame retransmission should take place at the earliest
    after a time period the MS needs for the transmission of an
    acknowledgement of a received layer 2 frame
    – a Um layer 2 frame retransmission should take place as early as
    possible when the aforementioned time period has passed and no
    acknowledgement was received from the MS
    – unnecessary retransmissions are avoided.

    so they recommend 145ms T200, and default is 220ms (N200 is 23 for SD)

    #54409 Reply
    suhaibi
    Guest

    Hello,

    which could be the causes of the expiry of T200?

    #54410 Reply
    Bijoy
    Guest

    Hi Krish/Pan/Pix
    If you increase the T200 timer for SDCCH.it will improve the SDCCH Drop at the cost of SDCCH Blocking,that’s it.But only upto a certain extent.

    Certain Vendors like,Nokia,Ericsson,Huawei has actually got some new features like repeated SACCH & FACCH to improve the Signalling Drops & HOSR

    Br\\
    Bijoy

    #54411 Reply
    Binit
    Guest

    Hi bijoy

    Idle SDCCH Threshold N1=2
    TCH Minimum Recovery Time(s)=60 sec is the current status of one site and there is sdcch blocking and tch blocking .what value of these two parameter will solve my both problem.

    #54412 Reply
    Bijoy
    Guest

    Binit
    These are recommended values in Huawei.Have you defined adequate SDCCH/TCH checking the SDCCH/TCH Traffic?
    If dimensioning is OK,& you want immediate improvement in SDCCH/TCH Blocking enable “Immediate Assignment on TCH” to reduce SDCCH Blocking.For TCH Blocking,lower the triggering threshold for HR,i.e,use more HR’s

    Br\\
    Bijoy

    #54413 Reply
    david
    Guest

    anyone knows suggested values for T200 timers for GSM over satellite?

    #54414 Reply
    danekaba
    Guest

    in ERICSSON switch . we have one subscriber which can not make call in roaming but he can receive: i have checked all subcription status: HGDSP:msisdn=…, all; there is not trouble just this parameter i dont understand it.

    SERVICES RESTRICTED IN VLR
    RSP
    7
    plz i need your suggestion.

    #54415 Reply
    Bijoy
    Guest

    Hi David
    Keep T200 as 1400 ms with SIGDEL=LONG for Abis over satellite.

    Br\\
    Bijoy

    #54416 Reply
    pravesh
    Guest

    Hello Bijoy i am trying to run Abis over satellite and tried T200 from 1.5 to 3 seconds.

    Can you please let me know how much is the optimum retry we should set.

    #54417 Reply
    Bijoy
    Guest

    Hi Pravesh
    MAXRET can be set to 4 in case of Abis over satellite.Also,set TTALONG to 15 desisecs.

    Br\\
    Bijoy

    #54418 Reply
    HARS
    Guest

    Radio link time out value ?

    #54419 Reply
    Bijoy
    Guest

    RLT can be kept the same as when normal.

    Br\\
    Bijoy

    #54420 Reply
    Pravesh
    Guest

    Thanx!! Bijoy can you please specify what is this parameter TTALONG i hope it is vendor specific and how i should map it with my system.I also see in one of the message you are mentioneing SIGDEL=LONG is it coorelated

    #54421 Reply
    Bijoy
    Guest

    Hi
    TTALONG in the BSC controls the value of the time-alignment timer.Time Alignment is a mechanism used between the BTSs and the transcoders to minimize the time speech and data frames are stored in the BTS before being sent out on the radio interface.The time-alignment timer TTA is located in the BTS and it starts when the BTS sends time-alignment change information to the transcoder and it stops after receiving a response from the transcoder.

    TTALONG will be used for TGs where SIGDEL is set to LONG.SIGDEL is set to LONG for Satellite A-bis.There are Ericsson specific parameters.

    Br\\
    Bijoy

    #54422 Reply
    Makarand
    Guest

    Hi bijoy,
    exactly when t200 starts?
    Is ho failure is one of the cause for data link failure?
    In ho failure which data link gets broken ,i think it must be at source side , then how it gets restored as its nt necessary that call may drop after data link failure.

Viewing 15 posts - 46 through 60 (of 69 total)
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