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BCCH configuring in high signalling Cell

Viewing 6 posts - 1 through 6 (of 6 total)
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  • #51363

    Hi all
    What´s the rule to configure common control channels in a cell with high Location Update signalling, for example an Airport. Mi question is focused in number of PCH,AGCH and RACH channels, any recommendation ??
    (Consider a cell with enough SDCCH channels configured)


    Hi victor,

    do you have a feature to use several timeslots for CCCH, or are you limited to just one BCCH ?

    If you have just one BCCH, then you must configure it as “non combined”. Therefore, your full 51-multiframe is used for the BCCH physical channel.
    In DL, you can configure 9 blocks : 5 for AGCH and 4 for PCH.
    In UL, all your blocks will be used for RACH.
    As you can see, the main optimization will not be here..
    You can also, if available, activate the Dynamic AGCH : the split between PCH and AGCH blocks is automatic, depending on the load.

    You can play around with the number of Paging groups as well, but I’m not too sure how it’s going to spread the load. If you increase the number of groups, that *should* decrease the PCH load, but slow down the call establishment.


    Is it possible to measure RACH congestion from stats? I don’t think so because if an MS is unable to get a RACH itself, BSC would be completely unaware of this event.


    That’s true, but you can count the number of RACH attempts. Since you also know the RACH capacity of your cell, there is a “rule” that says that if, at busy hour :
    RACH attempts/RACH capacity > 5 %
    then your RACH channel might be congested.

    … i think it is 5%.



    At just 5% utilization how can we say that RACH is congested? I’m confused.


    Not congested… but 5% utilization will lead to a “higher” probability of collision. Not high, really, but not acceptable…

Viewing 6 posts - 1 through 6 (of 6 total)
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