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SDCCH Congestion

Viewing 13 posts - 1 through 13 (of 13 total)
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  • 12th February 2010 at 13:57 #61043
    dannn
    Guest

    Hi guys. Im experiencing some extraordinary SDCCH congestion on one site located at a LAC border. The vendor in that area is Ericsson. For most cells at LAC borders, we are using CRH=6 but this value ain’t working for this two cells.
    Would someone kindly assist on this?

    13th February 2010 at 15:23 #61044
    safar
    Guest

    Hi,

    u can also put c2 value and will control sd congestion

    18th February 2010 at 23:12 #61045
    Louisa
    Guest

    Hi,

    how do I calculate the SDCCH congestion, also the TCH congestion?

    19th February 2010 at 09:23 #61046
    pix
    Guest

    hello,

    for tch congestion, count the number of 48.008 ASSIGMENT FAILURE (cause: “no radio resource available”)

    for sdcch congestion, it’s triky :
    count the number of times a 48.058 CHANNEL REQUIRED is received by BSC but **not** followed by a 48.058 CHANNEL ACTIVATION (sent from BSC to BTS).

    and

    count the number of IMMEDIATE ASSIGN REJECT (available only if the feature is activated)

    cheers
    pix

    19th February 2010 at 11:37 #61047
    Bijoy
    Guest

    Hi Pix
    What feature are you talking about??
    We dont need any feature to count IMMEDIATE ASSIGN REJECT in OSS.Do we??

    Br\\
    Bijoy

    20th February 2010 at 05:06 #61048
    Pix
    Guest

    No, but there will be Immediate Assign Reject to be counted only if you allow the system to send them.

    So you need to activate the feature, otherwise you’ll just count “zero” all the time 🙂

    (which is not a problem actually… is that what you mean ?)

    pix

    21st February 2010 at 07:55 #61049
    Bijoy
    Guest

    Hi Pix
    As far as I know,BSC sends IMMD Assgn Reject to the MS each time for
    1.no available channel
    2.channel activation failure
    3.channel activation timeout

    for each type of access reason.I dont know any such feature in any vendor which prohibits this(except ALU).

    Also,you are right,we dont need to count this,as we need to count only SDCCH seizure requests & successful SDCCH seizures to account for SDCCH Blocking.

    Br\\
    Bijoy

    22nd February 2010 at 06:19 #61050
    Lvin
    Guest

    Dear Friends

    hi to all
    who can help us about the Erlang?
    please we have cells with 20% Tch congestion ,half rate (50% with AMR and 20 without AMR) the Erlangs are 6.
    so must the Erlang over 21 because of each cells 4 TRX and TCH availabilities are 100%.
    please help us for this problem.

    thanks
    Regards;

    22nd February 2010 at 18:06 #61051
    Pix
    Guest

    Bijoy ,

    The difference between Request and Success will give you oth congestion rejections and radio failures (or possible hardware failures).
    The only way is to count the difference between Channel Request and Channel activation.
    This way, the result only shows the rejections dur to congestion.

    I didn’t know about the Imm asg Reject feature being so specific to ALU. And the worse thing is that it is disabled by default !

    ———————————-
    Lvin,

    could you check the erlang per TRX, to detect unused TRX, perhaps ?

    Cheers,
    pix

    23rd February 2010 at 06:05 #61052
    Bijoy
    Guest

    Pix
    Channel Activation failure can also happen due to faulty RTSL.Also.Imm assgn reject comes due to Ch,nnel act. timeout.

    In all vendors, I think there is an exact counter to account for SDCCCH channel requests rejected due to busy sdcch.

    Br\\
    Bijoy

    23rd February 2010 at 20:23 #61053
    Pix
    Guest

    Bijoy,

    Yes, there is probably such a counter, that’s true.

    channel activation failures are quite rare, but ok, that’s a risk i didn’t mention 🙂

    pix

    21st April 2010 at 03:52 #61054
    PSR
    Guest

    PSR

    22nd April 2010 at 06:34 #61055
    Mania
    Guest

    Hi Dann,
    I think the best solution would be to drive the area and confirm if the LAC updates are due to pingpong Location updates / genuine updates.
    If Pingpong: increase CRH on both cells between by 2dB initially and fine tune.
    Other wise you can increase CRH of neighbouring cell towards this cell take it to 8 and then tune.

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