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Handover Access

Viewing 10 posts - 1 through 10 (of 10 total)
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  • #49677 Reply
    mehrdad
    Guest

    Hi everey body,
    You know MS for implementation inter-cell handover will send handover access to new cell.I want to know HO access format. for example rach is 1 octet. could you please tell me?

    #49678 Reply
    pix
    Guest

    you can have a look to 3gpp.org.

    i can have a look later, but i’m afraid i’m going to forget 🙂

    #49679 Reply
    mehrdad
    Guest

    Hi pix,
    i am searching 3gpp site but i couldn’t find HO burst format until now. if you find it please tell me.
    thanks alot

    #49680 Reply
    mehrdad
    Guest

    I found the “Handover Access” format finally. it contains 1 octet usefull data like “Rach” message. both of them will be sent on “Access Burst” so sometimes BTS detects “Handover Access” Burst as “Rach” wrongly and BSC assigns SDCCH to this request (SDCCH GHOST) that waste the SDCCH resource.

    #49681 Reply
    pix
    Guest

    hi mehrdad,

    good job 🙂

    #49682 Reply
    splashingbee
    Guest

    I shall share what I found on HANDOVER ACCESS. HO Access Burst is basically a burst of bits – the 41 sync bits. There is a long guard period followed by 8 tail bits. This is followed by 26 encrypted data bits followed by 4 tail bits. Bits 88 – 156 are long guard bit period – to avoid any collision with other such access bursts.
    The access burst is sent in 4 consecutive time slots if the systems are TDMA synchronized. Else the MS keeps on sending this burst unless the BSS replies with a PHYSICAL INFORMATION message containing the TIMING ADV information or Timer T3124 expires (HANDOVER FAILED).

    Reference – Gsm – Architecture, Protocols and Services – Jörg Eberspächer, Hans-Joerg Vögel, Christian Bettstetter, Christian Hartmann | Page 152

    Sorry to dig out this thread after so long. However the info may be useful to somebody else.

    #49683 Reply
    pix
    Guest

    thanks dude 🙂

    #49684 Reply
    Dell
    Guest

    Hi,
    what’s the cause of Handover failure-unspecified? Radio? MSC?
    BR,
    Dell

    #49685 Reply
    kalpesh
    Guest

    How many Handover Access burst MS may send over SACCH?

    #49686 Reply
    pix
    Guest

    hi,

    HO ACCESS is rarely sent on SACCH. If cell is synchronized (intra-BTS HO), then HO ACCESS is sent on FACCH exclusively, 4 times.

    In case on non-sycn cells :

    3GPP 44.018

    3.4.4.2.2 Non synchronized cell case

    After having switched to the assigned channels, the mobile station starts repeating the HANDOVER ACCESS message in successive layer 1 frames on the main DCCH ( = FACCH) and optionally on the SACCH. This message is sent in an access burst. Its content is reduced to the handover reference information element. The mobile station starts timer T3124 at the start point of the timeslot in which the HANDOVER ACCESS message is sent the first time on the main DCCH.

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