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EDGE Low DL Throughput

Viewing 15 posts - 1 through 15 (of 22 total)
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  • #57669 Reply
    KB
    Guest

    How to improve data throughput?
    Current cell parameter 4 Tre

    -min pdch = 4
    -max pdch = 22
    -max high load = 4

    voice traffic = ~ 40 – 50%
    no.of Extra TS = 2
    DL Throughput < 80 kbit/s

    #57670 Reply
    Pix
    Guest

    what is your MAX MCS ?
    what is your GPRS HIGH LOAD ?
    how many cell in the BTS ?
    What is MAX TBF PER SPDCH (UL & DL) ?

    Why only 2 Extra timeslots ?

    so regarding the current info:
    max pdch highload is way too low (try to set it to 7 or 8)
    extra ts is too low

    waiting for your answers,
    cheers,
    pix

    #57671 Reply
    KB
    Guest

    Thanks Master optimizer ๐Ÿ˜‰
    the problem occur all cell( ALU B9 )but sometime data thr > 180 kbit/s (static test)

    MAX MCS = 9
    GPRS HIGH LOAD = 80%
    cell in the BTS = 3
    MAX TBF PER SPDCH (UL & DL)= 5
    MAX PDCH PER TBF = 5
    Why only 2 Extra timeslots ? = no budget for 2 abis ๐Ÿ™

    could u pls recommend parameter setting and extra ts

    Cheers,
    KB

    #57672 Reply
    krish
    Guest

    Hi,

    hey pix can u explain this terms if u can ?

    #57673 Reply
    Pix
    Guest

    KB, no problem ๐Ÿ™‚
    if you can’t work on your Abis capacity.. mmm…

    BTS config = 4/4/4 ?
    that’s (i assume) 3 BCCH + 6 SDCCH
    so you have 9 bonus nibbles + 8 extra nibbles… that’s a total of 14 extra nibbles.

    Imagine: one MS, with 4 PDCH at MCS-9. It will use 4 x 4.5 nibbles = 18 nibbles.

    it will use its 4 basic nibbles + 12 extra nibbles.

    All extra nibbles are used up by only one MS !!!
    Since they are a lot of GPRS signallings (Attach, PDP context, RA update), many MS’s will require capacity… And therefore there won’t be enough even for the one MS that needs 4PDCH at MCS 9.

    Conclusion: you must add extra TS. If you can’t, then the ONLY solution is to reduce TCH capacity. You can do it this way:

    MAX PDCH HIGH LOAD = 5 … 7 … 8
    GPRS HIGH LOAD = 85% … 90%

    Start with values at the left, then try the values at the right. Check if you have improvements, step by step. Check your TCH congestion.

    If your BTS is 4/4/4, you should have more than 2 extra abis nibbles left… I cant remember exactly, but it should be 5 or 6, no ?

    Finally, check your GPRS indicators. You can see how much Abis nibbles are busy or free, how many PDCH are allocated in the cell, at busy hour, etc. They will really help you to understand what is limiting your TBF throughput.

    #57674 Reply
    Pix
    Guest

    sorry… 18 nibbles = 4 basic nibbles + 14 extra nibbles !
    your 2 abis ts are not enough to satisfy even one full-throughput MS.

    The hi-speed throughput can only be achieved if there are only little amount of TCH allocated in the cell. (night ?)

    #57675 Reply
    Pix
    Guest

    Krish,
    ooooch… i’m sorry, it’s really hard to explain it on a forum.

    I can only tell you that the names of those parameters are quite self-explanatory. And unfortunately, if you don’t understand them, it means you need some fundamentals trainings about GPRS Alcatel. I’m not being arrogant (for once ?), because it’s really a difficult topic.

    That’s why 3G is so successful. GPRS was too complicated to understand :))

    #57676 Reply
    KB
    Guest

    could u pls recommend no.of extra ts for 2 abis

    cheers,

    KB

    #57677 Reply
    KB
    Guest

    If we got 2 abis,the current extra ts = 2 .Avg TRX/cell in urban = 5.could u pls recommend no.of extra ts for hi-speed throughput

    Thank you in advance
    cheers,

    KB

    #57678 Reply
    Pix
    Guest

    KB,

    extra timeslots are the timeslots which are not occupied by OML, RSL or TCH.
    if those TS are not “extra” then they are nothing, they are lost. You might as well define them as extra, don’t you think?

    if you have 2 Abis links, i think you can have much more than only 2 extra TS.

    recommendation: this is a dimensioning job ! nobody is doing that in your company ?
    ok, I recommend you to define 6 extra timeslots per BTS.
    … what do you do with that number…? Please let me know.

    #57679 Reply
    krish
    Guest

    Hi pix,

    thanks for ur reply.

    hey i want to understand only this term if u can

    (1) dl edge and gprs thrput per tbf like value 75,200,121= it indicates data volume or speed?

    (2) tbf success ratio per tbf= it indicates per ms ?

    #57680 Reply
    pix
    Guest

    (1) throughput is in kb/s the value you see is wrong

    (2) i dont know this indic. check the formula.

    #57681 Reply
    KB
    Guest

    Thanks Master

    at here have team plan for low Throughput ๐Ÿ˜‰

    could u pls explain 4.5 nibbles at MCS9

    #57682 Reply
    Pix
    Guest

    hello,

    not master, please…

    one radio ts in Edge can carry up to 60kb/s, thanks to 8PSK modulation.
    On Abis though, there is only 16kb/s per nibble, it can’t be enhanced.
    So one PDCH (radio ts) is going to be carried over 4.5 Abis nibbles (GCH).

    Simple ๐Ÿ™‚
    Cheers
    Pix

    #57683 Reply
    AD Boy
    Guest

    Hi guys, gone through this but I need to get more understanding. What if i have a case of 2cells i.e 4/4 Trx on cells 1 & 2. With (1BCCH + 2SDCCH) on Trx1 of Cell 1 and (1BCCH + 1SDCCH) on Trx1 of Cell2. How many Basic, Bonus and Extra Nibbles do I require? Also what are the total Number of Abis TS on [Basic, Bonus & Extra Nibbles]?

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