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Error indication: T200 expired

Viewing 15 posts - 1 through 15 (of 30 total)
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  • #51035 Reply
    Kassem
    Guest

    Dears
    Thanks in advace for your reply
    coud you please help me what the reasons for TCH Drop due to “Error indication: T200 expired”

    Thanks alot
    Kassem

    #51036 Reply
    Michele
    Guest

    T200 is an air interface timer regulating the communication between MS and BTS. It defines the rate of repetition of a message (on BTS side) on the air if it is not acknowledged by MS.
    If the message was repeated N200 times and no answer was received by MS, an error indication with cause T200 expired is provided to BSC.
    Probably there is not a correct setting of T200 or N200 or the DL quality/level is very bad. Another problem could be the use of the same BSIC between adjacent cell, causing some problem during handovers.

    #51037 Reply
    Kassem
    Guest

    Thanks alot for your reply Michele
    coud you please help me what the reasons for TCH Drop due to “Connection failure: radio link failure”

    Thanks alot kassem

    #51038 Reply
    Pix
    Guest

    Assem,

    you should ask all your questions at once 🙂
    radio link failure : the radio link counter has expired. It means that during few consecutive seconds (def. 9s), there was no SACCH UL that was succesfully decoded by the BTS.
    It is an indication of the TCH quality : if the SACCH could not be decoded, then the TCH probably can’t be decoded either.

    #51039 Reply
    Kassem
    Guest

    Thanks alot Pix for your fast reply
    Pix ,could you help me also for these
    please I have some questions:
    What the reasons for TCH drop due to these Counters:

    1-Error indication: unsolicited DM response, multiple frame established state

    2 Error indication: sequence error

    3 Connection failure: T_MSRFPCI expired

    4 Connection failure: distance limit exceeded

    5 Connection failure: handover access failure

    6 Connection failure: radio link failure

    7 Connection failure: remote transcoder failure

    #51040 Reply
    Michele
    Guest

    3 T_MSRFPCI expired: on the new channel no ms rf power capability indication were received in BTS (from BSC) within 20 sec fron Channel Activation. In this case probably MS was never presented on the new channel (no SABM was received in BTS);

    5 handover access failure: T3105 expires ny1 times and MS never accessed on the target cell;

    4 distance limit exceeded: the distance between MS and BTS exceed the maximum allowed one into the cell (attribute excessiveDistance) and so the call is released;

    7 remote transcoder failure: no DL TRAU frames were received in DL direction after channel activation (for the timer TTRAU).

    Do you work with SIEMENS BSS?

    #51041 Reply
    Kassem
    Guest

    Yes , I am working in Siemens network.and I Faced all above Problems

    your cooperation high appreciated
    Thanks alot

    #51042 Reply
    NK
    Guest

    Hi! Michele,

    I do not understand why MSRFPCI should be provided by the BS.It should be provided by MS.

    Regards,
    NK

    #51043 Reply
    Michele
    Guest

    Hi Kassem, as you know in Siemens BSS Handover and Power Control algorithm are implemented in BTS instead of in BSC. So MS capabilities sent from MS to BSC (transparent to BTS) are then forwarded from BSC to BTS by an Abis message (RF MS Power Capability Indication).
    If BTS doesn’t receive this message (from BSC) in a time of 20 sec from Channel Activation a Connection failure with cause T_MSRFPCI expired is generated.

    #51044 Reply
    Kassem
    Guest

    Thanks for your reply Michele/Pix
    In siemens Vendor we have the default Value for T200
    T200=29-31-38-90-70-29-168,
    Parameter format: sdcchSAPI0 – facchTCHF – facchTCHH –
    sacchTCHSAPI0 – sacchSDCCH – sdcchSAPI3 –
    sacchTCHSAPI3.
    if we face TCH Drop due to T200 Expired,we change in default value,lead to improvement
    please advice us about it
    Thanks in advace for your reply

    #51045 Reply
    Kassem
    Guest

    Dears Pix/Michele
    please help me about last question

    #51046 Reply
    pix
    Guest

    T200 is directly proportional to the delay expected on the ABIS link :

    with terrestrial Abis, this value shall be 300ms

    with satellite Abis, it shall be incremented to 1000ms (1 second)

    thererfore, you can try to increase this timer until the T200 stops expiring. Basically, you should look for the root problem : what is causing such high delays on the Abis interface ? Is your link stable ? Are your LapD stable ? What about the boards that take care of LapD at BTS side (SUM or TRX) and at BSC side (TSU or TCU) ?
    Is there any congestion/overload on these boards ?

    Regards,
    Pix

    #51047 Reply
    Michele
    Guest

    Hi pix/Kassem,
    the problem found by Kassem is on air interface (LAPDm).

    Which is the release SW on field? BR9.0? It seems that there are some MS types having some problem with low T200 values.

    I can suggest you some settings used on field by an Italian network operator. It doesn’t claim any problem and has a very very low tassfail.

    T200=60-31-60-90-90-90-135

    T3105= 50ms

    NY1=70

    #51048 Reply
    Zbigniew
    Guest

    Hi Michele,

    do you have some information about the TCH drop reasons

    2 Error Indication: Unsolicited DM Response, Multi Frame Established State

    3 Error Indication: Sequence Error

    in Siemens BSS ?

    Thanks,

    Zbigniew

    #51049 Reply
    pix
    Guest

    michelle,

    thanks for your inputs.. maybe you can explain a little bit :

    T200 supervises Ack on the LapD, so ok, it is impacted by internal MS delay as well.
    Basically, how can you ensure the problem is in the Air interface ? It’s based on experience I guess ?

Viewing 15 posts - 1 through 15 (of 30 total)
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