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HO failure RR message

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  • #56193 Reply
    IST
    Guest

    in tems while analyzing drivetest log files, we found that for some HO failures the RR message sequence was as below:
    HO Command (sent from BS)->HO failure (sent by MS)
    and the time difference between the HO command received my MS and the HO failure sent by MS was less then 1 ms.(i.e. just after getting the HO command, MS sent HO failure instantly).
    What is the reason for that? Can any 1 help please?

    #56194 Reply
    Pix
    Guest

    very interesting ! i would suspect the MS is not happy with the content of the HO Command –> basically, the HO CMD is describing the target cell, and the MS, while reading it, feels like this neighbor cell is not suitable for himself. Wrong frequency range ? Wrong codec ? Wrong ciphering mode ?

    Regards,
    Pix

    #56195 Reply
    IST
    Guest

    hi Pix,
    in the case of wong frequency range or wrong codec, the cause for HO failure should be like “frequency not implemented” or “channel mode unacceptable” as I saw it from ETSI.

    But in our case its always the same cause “Protocol error unspecified”..(cause value: 111).
    And the interesting thing is ,MS was reacting instantly..no time delay between HO command and HO failure.

    #56196 Reply
    Rex
    Guest

    Hi IST,
    is that happening randomly or just in one HO relation, randomly in all HO relations in one BSC or HO relations between two BSCs? It’s probably MSC problem. Check NSS!

    #56197 Reply
    Pix
    Guest

    IST,

    Well, i couldn’t know that, since you didn’t say anything in your 1st post 🙂

    The mobile reads the HO CMD message and replies with a HO failure. I understand your issue with the MS timing : 1ms is rather fast. However, we must assume the MS is reading and processing this particular msg with more priority than the others, so it’s not surprising.

    In my opinion, there’s something in the HO CMD which is wrong, from the point of view of this TEMS mobile. Don’t you agree with this ? When you check QoS indicators in the cell, are there a lot of HO execution failure rate ? (lots of request, lots of attempts, but little success?)

    Could you copy & paste the full content of this ho cmd msg here please ?

    #56198 Reply
    IST
    Guest

    hi Pix,
    below HO command copy and past:
    MS1
    Handover Command

    Time: 12:27:47.54
    Frame number: 4833242

    MsgCtrlOperation :
    Skip indicator : 0
    Protocol discriminator : (6) Radio resources management messages
    Message type : 43
    Cell Description
    BSIC : 3-0
    BCCH ARFCN : 26
    Description of the first channel, after time
    Channel type : (1) TCH/F + ACCHs
    Timeslot number (TN) : 1
    Training sequence code (TSC) : 0
    Hopping RF channel : (1) RF Hopping Channel
    Mobile allocation index offset (MAIO) : 1
    Hopping sequence number (HSN) : 17
    Handover reference
    Handover reference value : 105
    Power command and access type
    Access type control (ATC) : (0) Sending of Handover Access is mandatory
    Enhanced power control (EPC) : (0) Channel(s) not in EPC mode
    Fast measurement reporting and power control (FPC) : (0) FPC not in use
    Power level : 5
    Synchronization indication
    Normal cell indication : (1) Out of range timing advance shall trigger a handover failure procedure
    Report observed time difference : (0) ‘Mobile Time Difference’ IE shall not be included in the Handover Complete message
    Synchronization indication : (0) Non-synchronized
    Frequency channel sequence, after time
    Channels : 50 56 60 71 76
    [0 ] : 50
    [1 ] : 56
    [2 ] : 60
    [3 ] : 71
    [4 ] : 76
    Multi-Rate Configuration
    Multirate speech version : (1) Adaptive Multirate speech version 1 – FR AMR, HR AMR or OHR AMR
    Noice Suppression Control Bit (NSCB) : (0) Noise Suppression can be used (default)
    Initial Codec Mode Indicator (ICMI) : (1) The initial codec mode is defined by the Start Mode field
    Start Mode : (2) CODEC_MODE_3 (Represents the third lowest mode, if the ACS includes more than two modes)
    Set of AMR codec modes
    Set of AMR Codec Modes :
    12.2 kbit/s codec rate is part of the subset :
    10.2 kbit/s codec rate is part of the subset :
    7.40 kbit/s codec rate is part of the subset :
    5.15 kbit/s codec rate is part of the subset :
    Threshold 1 : (14) 7.0 dB
    Hysteresis 1 : (1) 0.5 dB
    Threshold 2 : (21) 10.5 dB
    Hysteresis 2 : (1) 0.5 dB
    Threshold 3 : (26) 13.0 dB
    Hysteresis 3 : (1) 0.5 dB

    Header dump (Hex):
    2A 00 21 00 00 00 04 21 00 03
    01 00 01 1C

    Message dump (Hex):
    06 2B 18 1A 09 10 51 69 05 D8
    69 32 64 B5 00 00 00 00 00 00
    03 06 2A D2 0E 15 45 A1

    hi,,,no HOSR KPI doesn’t affect too much.I mean handover success rate is ok. Actually this problem is not for a particular cell.And not related to any particular BSC.

    And pix,
    is there any minimum time duration between the ho command and ho failure message?
    in my cases there was no time duration between the ho command and ho failure.MS sent HO failure instantly at the same time it got the ho command.

    #56199 Reply
    aman
    Guest

    handover faiure

    #56200 Reply
    Pix
    Guest

    Could you try deativating the AMR or the TFO ?

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