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Low CSSR in Huawei Cell (unknow reason)

This topic contains 28 replies, has 0 voices, and was last updated by  ziad 2 months, 1 week ago.

Viewing 15 posts - 1 through 15 (of 29 total)
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  • #63495 Reply

    Huawei – Man

    Hi all

    In one cell of Huawei site CSSR is very low (15%-60%)by statistics.

    1. DT measurement has been done, but no any problem, CSSR is 100 % in DT.

    2. No hardware issue

    3. No transmission alarm

    4. All rest KPIs are normal

    This is formula for CSSR:

    [Success Rate of TCH Assignment]*[Success Rate of Call Setup(immediate assignment)]/100

    This formula is the same for all Huawei cells and I have never seen any unknown problem like this.

    If someone of you has idea please share your experience with me.

    Thanks in advance

    #63496 Reply

    Bijoy

    Please search & read this post.
    “Worst CSSR in Huawei”.

    Br\\
    Bijoy

    #63497 Reply

    Huawei – Man

    Dear Bijoy

    The mentioned post is not existing.

    #63498 Reply

    Bijoy

    Please read thread 5637.Type “CSSR” in “search for an article”

    #63499 Reply

    Huawei – Man

    Yes yes, I found. Thanks.

    Can location update failure affect to CSSR even no SD congestion?

    #63500 Reply

    Bijoy

    Hi
    Ideally,LU shouldn’t be considered for calculating CSSR,but the formula you are using considers SDCCH drop during LU.So,yes,your CSSR will get impacted.

    P.S:There is a way out & you will find that in that very post.

    Br\\
    Bijoy

    #63501 Reply

    Huawei – Man

    Hi Bijoy

    I have defined “Channel Request (Packet Call)” is 500-800-1800 times on this cell.

    Actually what does it mean, what is Packet Call?

    #63502 Reply

    Bijoy

    Channel Request for Packet Call means the MS is sending a RACH to access the PS services.

    Br\\
    Bijoy

    #63503 Reply

    Huawei – Man

    Bijoy, please have a look stat for one hour of the mention cell. Its CSSR is very low. I can’t find the cause.

    Maybe you can give some ideas to find the reason, PLEASE. Thanks a lot.

    Start Time 13/07/2010 06:00:00
    Object Name CellA
    CA300J:Channel Requests (Circuit Service) 208
    CA303J:Call Setup Indications (Circuit Service) 45
    Call Setup Success Rate 21.635
    CA3030J:Call Setup Indications (SDCCH) (Circuit Service) 45
    CA3039J:Call Setup Indications (TCH) (Circuit Service) 0
    CA303A:Call Setup Indications (Call Type) 3
    CA303B:Call Setup Indications (Non-Call Type) 42
    A300A:Channel Requests (MOC) 4
    A300C:Channel Requests (MTC) 4
    A300D:Channel Requests (Emergency Call) 0
    A300E:Channel Requests (Call Re-establishment) 0
    A300F:Channel Requests (Location Updating) 200
    A300H:Channel Requests (Packet Call) 100
    A300I:Channel Requests (LMU+Reserved) 0
    A300K:Channel Requests (Protocol Incompatible) 0
    CA300A:Channel Requests (Call Type) 8
    CA300B:Channel Requests (Non-Call Type) 300
    CA303H:Call Setup Indications (Packet Service) 0
    K3000:SDCCH Seizure Requests 208
    K3003:Successful SDCCH Seizures 208
    K3003A:Successful SDCCH Seizures (Call Type) 7
    RCA313:Success Rate of TCH Assignment 100
    RA303I:Success Rate of Call Setup (Immediate Assignment) 21.635

    #63504 Reply

    Huawei – Man

    Bijoy, please have a look stat for one hour of the mention cell. Its CSSR is very low. I can’t find the cause.

    Maybe you can give some ideas to find the reason, PLEASE. Thanks a lot.

    Start Time 13/07/2010 06:00:00
    Object Name CellA
    CA300J:Channel Requests (Circuit Service) : 208
    CA303J:Call Setup Indications (Circuit Service) : 45
    Call Setup Success Rate : 21.635
    CA3030J:Call Setup Indications (SDCCH) (Circuit Service) : 45
    CA3039J:Call Setup Indications (TCH) (Circuit Service) : 0
    CA303A:Call Setup Indications (Call Type) : 3
    CA303B:Call Setup Indications (Non-Call Type) : 42
    A300A:Channel Requests (MOC) : 4
    A300C:Channel Requests (MTC) : 4
    A300D:Channel Requests (Emergency Call) : 0
    A300E:Channel Requests (Call Re-establishment) : 0
    A300F:Channel Requests (Location Updating) : 200
    A300H:Channel Requests (Packet Call) : 100
    A300I:Channel Requests (LMU+Reserved) : 0
    A300K:Channel Requests (Protocol Incompatible) : 0
    CA300A:Channel Requests (Call Type) : 8
    CA300B:Channel Requests (Non-Call Type) : 300
    CA303H:Call Setup Indications (Packet Service) : 0
    K3000:SDCCH Seizure Requests : 208
    K3003:Successful SDCCH Seizures : 208
    K3003A:Successful SDCCH Seizures (Call Type) : 7
    RCA313:Success Rate of TCH Assignment : 100
    RA303I:Success Rate of Call Setup (Immediate Assignment) : 21.635

    #63505 Reply

    Bijoy

    From this data,what I can conclude is:
    1.This cell is either at LA boundary or overshooting at LA boundary beacuse LU request is high.
    2.Call setup Indication is Low,which means there is either Imm. assignment reject(SDCCH Blk) or call setup indication timed out(T3101 expiry).
    3.Your immediate aasignment success is poor for Non-call type.

    Suggestions
    1.Give tilt to the cell if overshooting
    2.Check Co-BSIC-BCCH cells,if nearby
    3.Increase Cell reselection hysteresis if on LA boundary.
    4.Check for SDCCH Blocking(remote possibility)

    This formula is actually too gross,you should use CSSR for CS services only.

    P.S:
    You can increase the “RACH Min. Access level”,”RACH Busy threshold”,& “RACH error threshold” to reduce this,but you cant eliminate the effect totally.

    It is better if you use “Immediate assignment commands/Immediate Assignment requests” in place of RA303I.
    Br\\
    Bijoy

    #63506 Reply

    Huawei – Man

    You mean I should use following formula for CSSR?

    Immediate assignment commands/Immediate Assignment requests*100

    Or what is useful formula for CSSR in Huawei system?

    #63507 Reply

    Huawei – Man

    As well

    Call Setup Indications Timed Out: 162

    for this hour.

    No SD blocking

    #63508 Reply

    Bijoy

    Call Setup Success Rate=BSS Call Establishment Success Rate = [([Success Rate of Call Setup (Immediate Assignment)/{100}) x ([Success Rate of TCH Assignment]/{100}) x (1 – ([Call Drop Rate on SDCCH]/{100})) x {100}.

    In this formula,it is recommended to replace [Success Rate of Call Setup (Immediate Assignment)] by “Immediate assignment commands/Immediate Assignment requests”.

    Br\\
    Bijoy

    #63509 Reply

    Lucas

    Hi all,

    Instead of “Immediate assignment commands/Immediate Assignment requests” I would recommend using “Channel Requests (Call Type)/Call Setup Indications(Call Type)”.

    This excludes Location Update, but considers SDCCH access failures for MOC or MTC (meaning: BSC sends Immediate Assignment but MS does not respond on a given time, which is given by T3101)

    BR

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Reply To: Low CSSR in Huawei Cell (unknow reason)
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