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GPRS UL ESTB FAIL Due BSS

Viewing 11 posts - 1 through 11 (of 11 total)
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  • #52255 Reply
    Da Architect
    Guest

    Dear Champs,

    In Alcatel, what could be the reasons for “GPRS_UL_TBF_estab_fail_BSS” taking into consideration that BSC Ater VSAT.

    Many Thanks,

    #52256 Reply
    m12
    Guest

    hello,

    what is the settings of the parameter ROUND_TRIP_DELAY at cell level?,

    m12.

    #52257 Reply
    Da Architect
    Guest

    ROUND_TRIP_DELAY = 700 ms

    #52258 Reply
    m12
    Guest

    that’s OK,

    what about bit error rates on the satellite links? In most cases, GPRS is very sensitive to BER’s and sat links are known not to be that persistently stable.

    m12

    #52259 Reply
    pix
    Guest

    i know there is a while list of GPRS timers to change when you have VSAT link.. the “satellite” recommended values are available in the customer documentation (look for “satellite” at the main page)

    otherwise, there are many other reasons, absolutely not related to VSAT link 🙂 I don’t know if you want to dig into that ?
    on top of my mind, but with a very small chance of it being correct :
    – GPU or anything else is frozen (try MFS/GPRS reset)
    – GPRS power control is activated (try alpha = gamma_tnx = 0)
    – some other feature is activated (???)
    – try lowering the CS & MCS init
    – etc…

    #52260 Reply
    Da Architect
    Guest

    Thank you Pix and M12

    T_ul_access_max value was not settled correctly. After correcting it, the UL TBF Establishment Failure Rate stayed the same value [around 30%] but the reason for this failure is now Radio. I will change GPRS Power control parameters and audit.

    What is the acceptable UL TBF Estab Success rate?

    #52261 Reply
    pix
    Guest

    with gprs over ater vsat, i’m not sure we have typical values for that… what is the value for the sdcch assignment failure radio ?

    i would say the ul tbf estab should vary proportionnally to the sd assign fail radio (in case of vsat, both indicators are directly impacted by the same issues implied by vsat)

    #52262 Reply
    Da Architect
    Guest

    Why and Which issues? Thank you.

    #52263 Reply
    pix
    Guest

    the vsat implies longer delays…
    i’m just saying :
    if a voice call is made on a BSS w/ VSAT, IF there is a problem you’ll probably see it in the SDCCH assign failure %

    if a GPRS transfer is done on a BSS w/ VSAT, IF there is a problem, you’ll probably see it in the GPRS TBF UL estab failure %.

    By VSAT problem, i mean that the BSS & NSS timers are not set correctly in order to deal with the longer delays.

    #52264 Reply
    Richard
    Guest

    we got alot of transmission fluctuations on a particular link almost occuring at the same time in the night each day. connectors have been changed but the issue persists. What else can be done?

    #52265 Reply
    Ian
    Guest

    Hi Da Architect ,

    Have you solved your problem, after migrating from VSAT SEVIS to VSAT HD(IP), we encountered a lot of UL_TBF_Estab failures and a very low DL Throuhput, have you found anything wrong with the parameters ? We set recommended ALU parameters but nothing improved.

    BR
    IAn

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