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Intra cell HO failures!!

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  • #65225 Reply
    Puru
    Guest

    Hi everyone,
    I am facing a specific issue in our N/W. There are high Intra cell failures in numerous cells.
    Situation:
    Numerous cells have very high intra cells HO(s) happening.
    We have switched off HR to HR intra cell HO(s). The ones happening are either FR to HR or FR to FR.
    The count is as high as 3 to 4 thousand intra cells counts per hour (busy hours).
    Now the problem is that the same is bringing down our HOSR (as intra cell success rate is counted in HOSR. Formula includes intra cell success & outgoing success over total pegs.
    Many cells our N/W have high intra cell failures and no inter cell failures which is making HOSR KPI look really bad.
    Parameters: Thresholds are with window from -75dB to -85dB & HO triggering at -90dB (town) & (-92dB rural). Rest parameters are in sync to support this.
    The threshold for intra cell HO(s) to take place is till -75dB (means intra cell will only be initiated if and only if there is interference AND the level is at least -75dB.
    CAN SOMEONE PLS ENRICH ME ON SOME OTHER INTRA CELL DECISSION PARAMETERS I NEED TO CHECK ALONG WITH REASONS FOR THE SAME.
    One more catch point: Most calls are in idle mode band of 2nd best so idle mode interference can slighlty by taken lightly here in most cases.

    #65226 Reply
    Just Passing By
    Guest

    check cells for Swap Cables

    #65227 Reply
    pix
    Guest

    hi puru,

    you forgot one major information:
    which vendor are you working with?

    and also:
    – are those concentric cells (inner zone / outer zone) or multiband cells (1800 zone and 900 zone) ?
    – what is the major cause of the HO? (you should find the split of handover causes in your qos stats)

    List of Intracell HO possible causes:

    Interferences for non AMR calls
    Interferences for AMR calls
    AMR FR-HR
    AMR HR-FR
    TFO
    TCH vs PDCH resources management
    Inner-Outer Zone
    Outer-Inner Zone

    And that’s it, for alcatel. Perhaps other vendors propose additional causes.

    regards
    pix

    #65228 Reply
    Purusharth
    Guest

    Hi all,
    Thanks for the info.
    We are using Moto.
    900 MHz band and no zone division.
    Causes of HO:
    >65% PBGT
    About 23% dur to DL & UL qual.
    For UL qual.
    All these are town cells so no rxlev issues in vicinity.
    i have played with max retrans (4 to 2), ms max power (39 to 33), rach min acc lev (-105 to -100/-98) & T3122>T3126 timers for retrans reduction but of no use at all.
    Traffic shifting to other cells also did not help much.
    How can I check the failures specific to FR to HR & HR to FR intra cell HO(s)? There is no counter in my knowledge which gives seperate segregation against the same. There is no cong, traffic is less than 80% fr capacity & TCH availability is high enough (as required).
    Pls help further.

    #65229 Reply
    pix
    Guest

    hi,

    well, i can’t help you about your counters, because i work only with ALU.
    which vendor are you working with?
    PBGT and QUAL handovers are NOT intracell HO. Therefore these are not the causes of intracell HO.

    could you provide me with these numbers (per day) ?
    intercell HO requests = …
    intracell HO requests = …

    All the parameters you tried to tune do not impact the intracell HO ! They only impact the access grant phase of a connection setup…

    Cheers
    pix

    #65230 Reply
    b
    Guest

    Hi

    For intracell HO you need to post intracell parameters.

    I dont know Moto counters but check:

    Intracell HO watch & valid time
    TRX Interference
    TRX Qual
    Check cables on site
    Intracell HO threshold

    ect…

    #65231 Reply
    pix
    Guest

    vendor = motorola, sorry i repeated the question earlier…

    #65232 Reply
    Purusharth
    Guest

    Intra cell HO requests: 1200 (peak hour)
    Inter cell HO requests: 512 (peak hour)
    All other cells are in the same range.
    Astonishing: wait & watch timers are same in all cells across n/w but still this high value of intra cell fail is specifcially on some cells spread across the circles.
    Observation: DL & UL interference is not alarming high on these cells, there are many cells having higher interference levels but not the same amount of intra cell failures. Poo %age samples vary from 4 to 9 % in these cells (DL/UL).
    Pix pls help.

    #65233 Reply
    pix
    Guest

    hello,

    the figures you shared are the number of intracell HO requests and intercell HO requests, not the failure rate. Therefore I am not able to fully comprehend your problem.
    There are other reasons than interference that trigger an intracell HO : AMR, TFO, Concentric Cell, GPRS.

    Maybe your issue is not so critical after all..?

    Regards
    pix

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