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TBF Reallocation Request

  • This topic has 5 replies, 1 voice, and was last updated 13 years ago by Pix.
Viewing 6 posts - 1 through 6 (of 6 total)
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  • #54558 Reply
    Ajil
    Guest

    Hi all, i have changed the MAX PDCH parameter in some cells and i saw that there where no change on Radio througput, what are the possible causes?? besides the TBF Reallocation request decreases in the concerned cell area, any explanations?

    #54559 Reply
    pix
    Guest

    what is your current radio throughput per TBF ?
    what was and what is your value of MAX PDCH ?

    MAX PDCH is just a guideline for your MFS. If there is some CS trafic in your cell, the MFS cannot allocate MAX PDCH, but only a computed value called “MAX SPDCH LIMIT”.

    If you really want to increase your PDCH versus your TCH, you should also increase your MAX PDCH HIGH LOAD and increase your HIGH_TRAFFIC_LOAD_GPRS.

    But as i said, now the algorithm of PDCH allocation is quite “automatic” and you can’t do much with parameters. Rather, you could try to increase your half rate occupancy, or add some TRX, or share the CS load with neighbour cells.

    regards,
    pix

    #54560 Reply
    Ajil
    Guest

    Actual max radio througput per TBF is 34 kbits/s in DL and 22 in UL.
    for the MAX PDCH we have changed the value from 4 to 8.
    but pix, i think even when we don’t change the MAX PDCH HIGH LOAD we should observe a higher throughput off the preemtable time (high CS traffic), am i right? i find it a little bit strange!!

    #54561 Reply
    pix
    Guest

    hi,

    now, increasing the max pdch will not change ANYTHING if your cell is highly loaded in TCH.

    could you check these indicators:
    nb of PDCH per TBF (this is a new report, located in MONO Object Distribution > GPRS distribution)
    ratio of usage of each MCS.

    the opint is: why do you have such low throughput: because users have low number of PDCH, or because the MCS is low ?

    if low PDCH –> you must increase the max pdch high load, and try to decrease the CS load

    if low MCS –> increase the max_mcs (i forgot the exact name), check your Abis & Ater are not congested, check there are no interference in the cell.

    to summary: check all your GPRS indicators in order to diagnose the problem 🙂 you are already trying to fix the parameters, but you didn’t finish the investigation. It’s like you’re filling up a car’s fuel tank when a tire is flat.

    #54562 Reply
    Ajil
    Guest

    Thanks pix i’ll check the items you mentioned, otherwise could u give me some docs for TBF allocation and PDCH mapping into TBF, i have a little bit info and i’ll search furthermore.

    #54563 Reply
    Pix
    Guest

    I’m afraid all documents are internal and can’t be given away publically.

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