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High SDCCH Assignment Failure

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  • 29th August 2011 at 12:23 #53453
    Rf Engineer
    Guest

    You can find good info SDCCH failure from below link.

    hXXp://www.telecomfunda.com/forum/viewtopic.php?f=6&t=3882

    where xx replaced by tt

    28th May 2012 at 04:29 #53454
    ng
    Guest

    hi in few cells sdcch assignment is very poor 80-90%, sdcch drops are high too, kindly suggest me to improve both

    12th October 2013 at 10:52 #53455
    yalda
    Guest

    Dears
    Can anybody help why T3101 tIMER in Ericsson system Expires although we increase the value of timer???

    12th October 2013 at 14:15 #53456
    pix
    Guest

    hi yalda,

    Probably because the incoming random access request is not valid. Therefore the BSC will wait for an Immediate Assignment FOREVER, until the timer t3101 expires.

    Whichever the value of t3101 you choose, the timer will always expire, for such “ghost rach”. There is a high amount of ghost rach in E/ BTS, because it is extremely sensitive and does not filter the ul noise it receives. It tends to decode a lot of ghost rach. The positive aspect of this sensitivity is a bigger cell range.

    In order to filter the ghost rach, we experimented quite succesfully with the MAXTA and TALIM values.
    Try setting MAXTA=20 and TALIM=19 (or even lower MAXTA if you can afford it). This will successfully reduce the impact of ghost rach on your t3101 expiry counter (CESSTIMASS)

    Regards

    7th March 2018 at 08:07 #53457
    Kanchan Gupta
    Guest

    I have come across with similar case in Nokia.
    voice CSSR (Phase 3 CSSR) is degrading in sec 2.
    Multiple alarms like, BTS with no transactions, Object Administrative state changed BCCH missing, BTS O&M Link Failure, Configuration of BCF failed are pegging on site. SDCCH Phase 3 drops have been increased from same date on sec 2. No change in traffic pattern observed. No TCH/SDCCH Blocking observed. No IM/CM found corelated from the date of degradation. HOSR is degraded on sec-1 from same date. BCCH frequency swap has been done between the TRX5 & TRX 6 on same date. On checking TA pattern, sec B is serving till 6.05km, no change in TA pattern observed. Intersite distance is 5.4km and site is at BSC boundary. No frequency Clash, No LAC mismatch observed.

    can anybody calrify me about Phase 3 CSSR degradation

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