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Abis structure question

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  • #49630 Reply
    TNS
    Guest

    Hi, all.

    The Gb interface links the PCU carrier equipment with the SGSN.
    The Gb interface by pass the Transcoder, so I think we don’t ” use transcoder for Packet Control unit to link with SGSN”…
    Is this correct?

    BR,
    TNS

    #49631 Reply
    GD
    Guest

    Ciphering is always done between BTS and Mobile on Air Interface. BTS Ciphers in downlink and Mobile does in Uplink.
    BTS receives encryption key and Algo( A5/1, A5/3 etc)from BSC.

    #49632 Reply
    pix
    Guest

    hello,

    the keys are provided by the HLR, aren’t they ? (Kc, SRES)
    the algorithms are implemented in the software of the TRX, but i suppose that is vendor-dependent.

    #49633 Reply
    Tamiflu
    Guest

    thanks !! very helpful post!

    #49634 Reply
    maryannflesscon
    Guest

    Hi all,
    I am new to this forum…
    Pls extend ur support to me.
    Regards.

    #49635 Reply
    Zyoti
    Guest

    hi ,

    i want to know now a days as latest technology on Abis link , Every BTS has IP so i guess abis link is alo IP based but i wonder it is used on same E1 ( as it is the main base for transmission used and i guess this cannnot be changed), so i want to know how may TRX will it support, cause before for S666 it need 2 E1 but now i see BTS using Single E1 for S666.. so pleas some one can make it clear with calculation

    #49636 Reply
    Pix
    Guest

    Zyoti,

    it only depends on the equipment use for transmission. It it supports E1 and IP, then you just have to switch the mode of transmission :
    BTS -> Abis Equipment : Ethernet link
    Abis Equipment 1 –> Abis Equipment 2 : Radio, Optical, Satellite, etc.

    In terms of link capacity : the voice is now “packetized”. when an user is not talking, zero packet are sent from BTS to TC.

    On top of that, the whole capacity of the IP link is shared among all the TRXs. With E1, each TRX has its own TS, all the time, even when there are no calls on the TRX.

    So altogether, the gain is about 50% : 2Mb/s in E1 can handle only S444. 2Mb/s in IP could handle S888 (to be calculated).

    Cheers,
    Pix

    #49637 Reply
    vishwas agrawal
    Guest

    Hi,
    I want to know that
    1- How many TSLs in one EDAP
    2- one PCM can support how many EDAP & How many TRX .
    3- what is the data rate reduction in the abis dimensioning how we can calculate it.

    #49638 Reply
    Zyoti
    Guest

    thanku pix,

    but i am stillnot clear about the query.. i need some reason how one E1 can support such huge TRX when E1 is over ip.. so please can probide me solutino for it… i need some calculation and reason…

    #49639 Reply
    zyoti
    Guest

    hi, inder

    in my view.. transcoder is used to save transmission resource ie transcoder is used to multiplex, so not only in sgsn in other links also transcoder r used as in A link so transcoder isused to save resource…

    #49640 Reply
    Bijoy
    Guest

    Hi Pix.
    This is only the theoretical calculation.
    In fact when u start using fixed & flexible PDTCH’s the capacity for Abis over IP E1 reduces to 14 TRX approx(for 3 fixed & 3 switchable PDTCH),and can be even less if u accomodate more PDTCH’s.

    #49641 Reply
    Pix
    Guest

    Bijoy,

    I am not talking about PDCH in the Abis, I am talking about IP compression of the Abis (Abis over IP) 🙂 Sorry if I wasn’t clear.

    Best Regards;
    Pix

    #49642 Reply
    Bijoy
    Guest

    Hi Pix
    That I know,I was just putting up the practical scenario,that’s it
    No offense meant

    #49643 Reply
    david,
    Guest

    Hey,

    one more finger of doubt this side. i think Frequency hopping is not possible in IP based solutions??? And as hopping is not allowed how is it possible to provide 14 TRX etc (as read in posts) in a single site? So many seperate frequencies for a cell? Practical???

    #49644 Reply
    Bijoy
    Guest

    That is not the case David
    Freq hopping is possible in Abis over IP

Viewing 15 posts - 16 through 30 (of 32 total)
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