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No response to immediate assignment

Viewing 15 posts - 1 through 15 (of 44 total)
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  • #58778 Reply
    Kryshka
    Guest

    Hi,
    We are using Ericsson equipment and encountered with the problem that MS do not response to Immediate assignment and also not send SABM message to MSC. This problem directly reflects on SDCCH establishment rate (sdcch fails due T3101 expire) and we have many customers complains due accessibility. CCCH, SDCCH resources do not perceive any congestion, interference, BSIC conflicts, signal levels in MS -75dBm.
    Any ideas?

    #58779 Reply
    Bijoy
    Guest

    Make RACH Access Level Min. to -109 and check

    #58780 Reply
    Kryshka
    Guest

    Now is -110. Does it make a difference?

    #58781 Reply
    RG
    Guest

    1.) Whats the timer value for T3101. If it is greater then 3secs then it is fine.

    2.) Any uplink interference (check IB report).

    3.) Replace the hardware if there is no issue on the Um and Abis interface.

    #58782 Reply
    Krishka
    Guest

    T3101 – 4 sec.
    ICM measurements – no uplink interference;
    With hardware – maybe, but observed in whole network.
    The interesting thing, that in Air-interface trace(did recording with NEMO) shows, that phone replies to paging with RACH, and from the network receives Immediate assignment, and later nothing. Network repages, – the procedure repeats, but stops in the same place – no answer to immediate assignment. Isn’t clear why phone do not try to choose SDCCH

    #58783 Reply
    ATTO
    Guest

    Hi Krishka,

    How to check for the value of T3101 In Ericsson? also how to change the actual value? I do not find any command to check for.

    Thanks in advance.

    #58784 Reply
    Kryshka
    Guest

    We did it by the requesting to ericsson, because the timer value cannot be changed by some command. But actually we didn’t see any significant improvement – huge number of sdcch fault due timer expire. The mobile do not answer to immediate assignment.

    #58785 Reply
    Bijoy
    Guest

    Changing T3101 will not help
    Change Rach Busy threshold to 5
    Change RACH Error Threshold to 200

    #58786 Reply
    Kryshka
    Guest

    Hi Bijou, where should be defined such thresholds and what impact they can do for immediate assignment? From my point of view – there are no problems with RACH establishment – BSC responds to RACH and sends immediate assignment but MS do not configure and send SABM message on SDCCH. Did you have problems similar like that?
    Thanks

    #58787 Reply
    Kryshka
    Guest

    I do not find such parameters in Ericsson Cell describtion…

    #58788 Reply
    Bijoy
    Guest

    Hi kryshka
    What is the value of Tx-integer in your system.Increase it & check

    #58789 Reply
    Kryshka
    Guest

    Tx integer is 32. Previously it was 20, but the changes didn’t have results. If looking to rach establishment statistics – it’s really normally – more that 99%.

    #58790 Reply
    Bijoy
    Guest

    Actually,this is a normal Rf phenomenon.That is the reason we have this Max. no. of retransmission parameter to safegaurd immediate assignment.Since RACH is slotted aloha,there will be huge losses inevidently

    #58791 Reply
    Kryshka
    Guest

    We have MAXRET=4 in one BSC, and MAXRET=7 in second. No big difference. So, my though is something strong in the MS side, – he get all that he want from network side – channel assignment in immediate assignment message. If MS do not understand that message, – he replies with immd.ass. reject, or waits for second time. In our case, he waits 4 times and later – nothing. Why he do not react to imme.assignmt…

    #58792 Reply
    Bijoy
    Guest

    Hi Kryshka.
    MS doesn’t give imm assignment reject.It is send by BSC under 3 conditions:
    1.no available channel
    2.channel activation failure
    3.channel activation timeout

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