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SDCCH handover

Viewing 13 posts - 1 through 13 (of 13 total)
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  • #53624 Reply
    MKT
    Guest

    Hi all,

    SDCCH handover is an optional or mandatory option in GSM?

    FACCH burst are supposed to carry the TCH handover related signaling when the MS is on active TCH.

    then..

    On which channel the SDCCH handover related signaling is carried out?

    Also for a TCH handover…
    Is it true that as standby arrangement we do exchange the same signaling over SACCH as the FACCH?

    Regards

    MKT

    #53625 Reply
    pix
    Guest

    hi mkt,

    the FACCH is used during SDCCH. Actually, SDCCH contains “SDCCH+SACCH+FACCH”.

    I don’t understand your last question. “StdBy arrangement” ?

    #53626 Reply
    MKT
    Guest

    thanks pix,

    standby arrangement i am referring to is the one which said that HO_COMMAND message from BTS will be sent on FACCH as well as SACCH, so as to avoid the possibility of missing/ not decoded the message(HO_CMD)

    Is it correct?

    MKT

    #53627 Reply
    MKT
    Guest

    FACCH is generated from TCH by STEALING.

    How do we generate FACCH from SDCCH, in the same way as TCH?

    does that means SDCCH is mapped to normal burst.

    Regards

    #53628 Reply
    pix
    Guest

    sorry, i said something wrong : there is no FACCH on SDCCH : the HO CMD is sent on a normal sdcch burst. Since there is no real time transmission of data on the sdcch, there is no “stealing” per say.

    as far as i know, the ho cmd is sent only on the FACCH, not on the SACCH. Could you find the document that says otherwise ?

    #53629 Reply
    Bloody
    Guest

    May I can explain you properly MKT… Let me try….tell me if m wrong.

    As you should know there is 26 Frams of TCH in one multi frame.

    |TCH|TCH|TCH|….

    in this frame one slot is alloted to SDCCH i suppose that is 12th slot. Now this SDCCH is used to carrly all signalling information during call. Like Measurment, Power Management etc. It also includes HO_COMMAND if required.

    |TCH||TCH||TCH||TCH|….|SDCCH|TCH||TCH||TCH|….26

    Now if BSC decided to do HO and in this multiframe slot number 14 is going on and now BSC can not wait for such a long period because call may ge dropped and at that time BSC decided to steal TCH and replaced by FACCH and gives HO_COMMAND.

    So Both channels are atually used for carring out HO_COMMAND.

    #53630 Reply
    pix
    Guest

    bloody,

    your explanation needs some corrections:
    – you miswrite SDCCH instead of SACCH. The TCH multiframe contains a SACCH block at TS12, not a SDCCH.

    – the FACCH will always carry the HO COMMAND, not the SACCH. Unless someone can show me a document where it says otherwise 🙂

    #53631 Reply
    Bloody
    Guest

    Pix actually i have one motorola GSM basic PDF which was given to me while Training. Buts too big that i can not even mail it.

    #53632 Reply
    pix
    Guest

    in this motorola document, they claim to carry the HO CMD over the SACCH ?

    well, ok, you could just snapshot the page talking about that.

    #53633 Reply
    MKT
    Guest

    Pix, You are right in saying that HO_CMD is carried over FACCH.

    Carrying the HO_CMD over SACCH in addition to the FACCH is a part of proposed inventions by some individuals working in the field.

    #53634 Reply
    pix
    Guest

    ok, thank you for clarifying bloody’s comments…
    i wonder what means “proposed inventions” ? you mean “common beliefs” ?

    #53635 Reply
    MKT
    Guest

    NO,

    its not common beliefs. It is about the patents ( various in numbers) which were/are filed by individuals/groups for their modifications or new addtions to the existing standards.

    Regards

    #53636 Reply
    pix
    Guest

    patents are just so dumb… 3GPP is an open standard, why would companies or individuals try to prevent 3GPP to use their ideas, by patenting them ? It’s the best way for this idea NEVER to be implemented in 3GPP.

    it just blows my mind.

    Anyway, I doubt that this kind of idea would ever appear in the 3GPP standards, because i just can’t see the benefit of doing so…

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