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Change Parameter Max retrans

  • This topic has 43 replies, 1 voice, and was last updated 12 years ago by krish.
Viewing 15 posts - 16 through 30 (of 44 total)
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  • #58669 Reply
    Bijoy
    Guest

    Krish
    Reducing Max no. of Retransmission will reduce SDCCH Holding time for sure.If your site is having a very high SDCCH Blocking ,reducing it will definitely improve your SDCCH Blocking.
    Rach Success ratio=immediate asssignment commands/RACH requests.

    Poor RACH suceess may be due to poor radio environment,like CO-BCCH-BSIC in nearby sites,Phantom RACH(especially in very low traffic sites),BTS sensitivity,No SDCCH.you can also increase the RACH min. access level(def. -105) to improve RSR.

    #58670 Reply
    Rex
    Guest

    Hi,
    which value(%) is acceptable for Rach success ratio?
    Thanks.

    #58671 Reply
    RG
    Guest

    Hi Bijoy,

    As per my understanding:

    MaxRetrans relates to RACH retry for different Access Cause.

    As our OMCR server only pegs/trigger (increment)the counters on the basis of Abis messages or Ater messages. So, in real we cant calculate our RACH Success Ratio. That is one of the reason “RACH Success Rate” is calculated using the response from the BTS with message “Channel Act Ack” for “Channel Act” send by the BSC. “Immediate Assignment Reject” directly relates to the Hadware fault as this transparent message is send after recieving the “Channel Required” from BTS and when in the BSC allocation table required resource is not present.

    #58672 Reply
    krish
    Guest

    hi,

    K bijoy right.but can u help me to find out parameter rach access threshold para in eric?

    #58673 Reply
    Rex
    Guest

    Hi,
    what is importance of enabling Immediate assignment reject in BSC, what’s its role?
    Thanks,

    #58674 Reply
    RG
    Guest

    Immediate Assignment Reject is the default signalling RR message from BSC in respond to channel request when requierd resource is not available in the BSC allocation table.

    #58675 Reply
    KRISH
    Guest

    Hi bijoy,

    once again abt rach max retran .

    if i have its value 4 andi have high sd blocking due to high traffic then in this case by decreasing it 2 ,as per said by u it will decrease sd blocking

    but can u tell me if on my first rach bts will not allocate sdcch then ms will try second time so here actually sd is not assign form bts side so how it will reduce sd blocking?

    and whatever i said above is it beneficial to inprove rach success?

    #58676 Reply
    pix
    Guest

    hi krish,

    SD blocking is when the BSC is not able to allocate a SDCCH channel to the MS. In other words, it is when the BSC doesn’t send an “immediate assignment” message back to the MS.

    Since the MS sends the RACH twice only, instead of three times, then there are only 2 blocking counted, instead of 3.

    The best feature to reduce congestion is to use the Immediate Assignment Reject, and set the WI_OC to > 2s.

    Cheers,
    Pix

    #58677 Reply
    krish
    Guest

    Hi pix,

    thanks for reply. but i want to know if ms sends 2 time rach request and no response from bts side then in picture where sd comes because bts is not giving sd and because of that ms sends 3 ,4 time rach request.so it how to increase sd blocking……

    and second if i have poor rach success ratio and my bcch-bsic and hardware is ok then by increasing rach max retrans from 2 to 7 and tx integer from 10 to 50 will help to improve rach success ratio.. plz explain..

    #58678 Reply
    Pix
    Guest

    When 1 RACH is not answered by BTS, it is internally counted by the BSC as “1 SD blocking”.

    So … 3 RACH from one MS, not answered = 3 SD blocking.

    Cheers,
    pix

    #58679 Reply
    krish
    Guest

    Hi Thanks pix,

    and second if i have poor rach success ratio and my bcch-bsic and hardware is ok then by increasing rach max retrans from 2 to 7 and tx integer from 10 to 50 will help to improve rach success ratio.. plz explain..

    #58680 Reply
    krish
    Guest

    hi bijoy & krish,

    Can u help me for improving rach suceess?

    #58681 Reply
    Pix
    Guest

    RACH success will be improved by proper TX INTEGER tuning (50) and activation of the IMMEDIATE ASSIGNMENT REJECT message.

    The number of retrans is, IMO, useless, but you can give it a shot anyway !

    Cheers,
    Pix

    #58682 Reply
    krish
    Guest

    hi pix,

    Thanks buddy.

    Hey as per said by u if i will change the value of tx from 10 to 50 will help me in imroving rach sucess and whats the importance of parameter S with this tx ?

    And if i activate the imme assign reject
    then it will help me in imroving rach sucess ratio? And also sd blocking?

    #58683 Reply
    Pix
    Guest

    For S and TX INT yes, they work in couple.
    Look at 3GPP to find the exact formula… but otherwise you can simply use the default value of TX INT = 50 with S = …? (isn’t it written somewhere in your docs ? i can check tomorrow for the S value, i forgot 🙂 )

    For IMM Asg Reject : yes, it will reduce sd congestio and racch failure etc… Why didn’t you enable it already ? we gave you all details about this feature in past posts…

    Cheers,
    pix

Viewing 15 posts - 16 through 30 (of 44 total)
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