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improve TBF drop rate

Viewing 15 posts - 1 through 15 (of 62 total)
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  • #47347 Reply
    oharazu
    Guest

    hey,

    if anyone know any method to improve TBF drop, i welcome to share.

    Thanks

    #47348 Reply
    Pix
    Guest

    First, you must ensure the GSM QoS is good in the cell. Basically, ensure the radio part is reliable (no interference, neighbors defined, rxlev > -85dBm at the cell border, etc.)

    Once this is done, it means your cell has a good GSM quality of service, but a poor GPRS qos. So you should check that your cell is not preempting some of the PDCH to voice calls (leading to TBF drops), or that your MFS/SGSN/GGSN are all working correctly.
    And no congestion on Ater and Gb interfaces.

    Of course, you should put all your radio parameters regarding GPRS to their default values. (no UL power control for instance)

    Regards,
    Pix

    #47349 Reply
    mohamed
    Guest

    can you speak with me about the Ericsson OSS and it applications.

    #47350 Reply
    Zeus
    Guest

    Hi Pix,

    It’s really good reading ur comments, i learned a lot from it.
    btw, I have problem with the UL TBF success rate, i encountered high failure due to radio.
    There is this parameter in Alcatel to prioritize the BCCH trx (Ps_Pref_Bcch_Trx). When i did this, there was a significant improvement, But i noticed a degradation on GSM qos, Call drop increased also HOSR bit degraded.

    Is there any other way on how to improved this?

    many thanks!!!

    #47351 Reply
    TNS
    Guest

    Hi, Zeus.

    What type of TRXs are used in this cell ( TRAG, TRAGE, … )?
    Hopping enable?

    There are two reasons ( in my opinion ): faulty TRX or bad freq…

    ( if we speak for one cell only )

    BR

    #47352 Reply
    Pix
    Guest

    I didn’t read this question, sorry Zeus,

    Yes, it points to a frequency problem. In RNO, can you check which TRX are carrying most of Erlang TCH ? Also, if you’re in B10, you can check the number of PDCH allocation per TRX (can’t you?).

    So this could help you find out which TRX could be the problem. Are you using SFH, BBH or NH? If SFH, then it looks like your BCCH is clean but the MA list used on the other TRX’s is a very dirty one.

    A popular saying: “If only my wife was as dirty as your TRX…”

    #47353 Reply
    pankaj
    Guest

    what is TBF , and how to improve tbf DROP RATE

    #47354 Reply
    Bijoy
    Guest

    Hi mohamed
    pls explain what u want to know abt ericsson oss

    br//
    Bijoy

    #47355 Reply
    HasnatBD
    Guest

    Hey,
    the cause of this can be several but you can the below steps to confirm.
    1. Check frequency in BBH and the retransmission rate in those cells. if high retransmission –> for sure there is problem on Frequency
    2. Try use most BCCH TRX TS for PDCH.
    3. Make sure (E)GPRS link adaptation is enabled.
    4. If frequency change doesn;t get good result, limit the (E)GPRS coding scheme up to MCS7 instead of MCS9. MCS7 is more robust than MCS9.

    #47356 Reply
    Mangesh
    Guest

    I want to know more about how to increase GPRS Speed, I am using 2 PDCH for each sector.

    #47357 Reply
    SHELDON
    Guest

    Hi Mangesh,

    To increase throughput, here are some of the things you should consider:

    1. Improve C/I ( reduce interference)
    2. Reduce no. of users per PDCH
    3. Check PCU congestion/Utilization

    Which vendor are you using? Also, you said you have 2PDCH per sector, what does that mean? Are these 2PDCHs dedicated? Semi-dedicated?

    Regards,
    SHELDON

    #47358 Reply
    krish
    Guest

    hi,

    Can anyone plz explain what is link adaption in egprs?

    #47359 Reply
    HasnatBD
    Guest

    Link adaptation is switching among the Modulation & coding schemes from 1 to 9 based on BLER(Block error rate). BLER is affected by C/I.

    When BLER is worse the lower MCS is selected while BLER is better higher MCS is selected.

    #47360 Reply
    Mania
    Guest

    Hi,
    In response to Zeus, your problem is because Alcatel algorithm wants you to have Pref_Mark 0 i.e least prioritized for at least one TRX if GPRS / EDGE is enabled, and this is the TRX on which PDCHs would be allocated be it fixed or switchable.
    You probably shifted PD to BCCH by changing its pref mark to 0 and Ps_Pref_Bcch_Trx. so automatically your GSM Calls are now disfavoured for this TRX.
    What you can do is to define your BCCH on the max GSM TRX count available e.g TRX-4 if you have 4 TRXs keep all pref_marks at 0 then since alcatel uses back filling your BCCH would be preferred for both CS and PS.
    This is one way around which you can use in B-9.
    Hope it proves useful

    #47361 Reply
    anand
    Guest

    please tell me the formula for calculating TBF Success Rate

Viewing 15 posts - 1 through 15 (of 62 total)
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