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Um and A-bis

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  • #53609 Reply
    MKT
    Guest

    Hi all,

    Um is said to be an open interface while A-bis is a closed one.

    At Um we have terms like layer2 layer 3. If these layers are analogous to the layers of ISO OSI layers then…

    Where does the remaining layers ie 4 to 7 are goen?

    Also

    at A-bis we do have the same term like layer2 (not sure whether layer3 is there or not) but

    A-bis is a closed interface.

    What restricts the A-bis to be an open interface?

    Is it due to the choice of implementing Modulo8 or Modulo128 versions of LAPD?

    Regards
    MKT

    #53610 Reply
    pix
    Guest

    mkt,

    the Um (or Air) interface is open in order to allow mobile equipments from different brands to be used with BTS from other brands.

    layer 4…7 are applications layer. They are not managed by the mobile network (not the BSS at least). Those are protocols used by distant servers, etc. For instance, HTTP / TCP-IP, those are higher layers.

    Layer 1, 2 and 3 are “transport” layer. That’s what the BSS does : it transports data from point A to point B. No need for other layers.

    #53611 Reply
    Pix
    Guest

    the Abis interface is closed so that a BTS from brand “A” can work only with a BSC of the same brand. It gives opportunity to vendors to develop proprietary features, which are not (yet) defined in 3GPP.

    #53612 Reply
    MKT
    Guest

    THANKS FOR REPLY PIX.

    Does that means we have to purchase the protocol analyzers(A-bis) from the same vendors as that of BTS/BSC?

    MKT

    #53613 Reply
    Narchai
    Guest

    MKT
    doesn’t
    as i know the protocol analyzers can provide protocal stk to match with BSS equipment. such as tektonix K12,K15

    #53614 Reply
    pix
    Guest

    yes, that’s correct. actually, you buy the protocol analyser from any brand, and you just install certain “patches” or libraries, to decode the abis messages.

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