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TFI in which channel PCH? AGCH ?

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  • 7th October 2012 at 07:56 #68621
    Dany
    Guest

    Hi,

    Is someone could tell me, in which logical channel is first allocated the TFI
    I am a little confuse about the first steps.

    Example:
    tell me if am right
    Mobile receive his PTMISI in PCH of the CCCH
    The mobile use RACH to answer and ask for a logical channel to communicate
    in AGCH the information of the PDCH
    (TS number and frequency) is given
    and perhaps its TFI ?
    unless the info of PDCH is already given in SI in BCCH
    but I doubt that TFI is given in PACCH because in order to collect the info in PDCH we need the TFI

    So for me TFI should be allocated in AGCH or PCH
    but I need a confirmation
    thank you very much
    Regards

    7th October 2012 at 14:41 #68622
    pix
    Guest

    yes, you guessed correctly : the TFI is provided in the AGCH, (Immediate Assignment message) if there is no ongoing “concurent” TBF which could be used to establish a new TBF in the other direction.

    7th October 2012 at 15:49 #68623
    DANY
    Guest

    Thank you pix,

    this what I like in GSM logical channel management: if we think logically, most of case we have the answer (perhaps that is why they call logical channel 🙂 )

    7th October 2012 at 16:14 #68624
    Dany
    Guest

    Just a little question

    Is the Packet Paging is in the Routing Area, or Location Area (we are using CCCH) ?

    thank you

    8th October 2012 at 18:19 #68625
    pix
    Guest

    Logical channels are easy to understand once you try to put yourself in their shoes 🙂

    Paging for GPRS is always the routing area (RA), defined by the couple Location Area Code (LAC) + Routing Area Code (RAC).
    Most operators define RAC=0, so that there is only one RA per LA. This is sufficient in networks with low PS paging. Nowadays though, there might be a need to split 1 LA in 3 or 4 RA because there is heavy PS Paging generated by smartphones apps.
    For example :
    RA1=LAC+RAC01
    RA2=LAC+RAC02
    RA3=LAC+RAC03

    cheers
    pix

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