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handover

  • This topic has 9 replies, 1 voice, and was last updated 10 years, 8 months ago by Pedro Miguel Saraiva Santos.
Viewing 10 posts - 1 through 10 (of 10 total)
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  • #48949 Reply
    emre
    Guest

    what it mean hard handower, soft handover and softer handover

    #48950 Reply
    aso
    Guest

    dear emre
    the meaning of Hard handover is mean that when the mobile send handover coammand and get handover complete it will move from the source cell to target cell but ( no more relation to sourse cell) which this kind of handovr is exist in 2g and for the soft handover is the same prcedure as before but it will be in cantact with source cell which it exist is 3g it look like chain with out break but is 2g the chain is breaking

    #48951 Reply
    Irfan
    Guest

    Hi aso kindly confrim me that is in 2g handover type is Hard handover and 3g is soft handover and why we need contact with source cell in 3g?

    #48952 Reply
    deaf and dumb
    Guest

    in CDMA, the frequency on which the mobile communicates doesnot change but the orthogonal codes change….the mobile changes the code but not frequency so it is called a soft handover (unlike gsm in which frequency also changes,). in CDMA, the mobile keeps on measuring on the same frequency but different code.

    #48953 Reply
    pix
    Guest

    soft handover : during the call, the mobile is connected to two cells at the same time, or sometimes more than 2 ! The soft HO happens when the mobile actually stops communicating with one of the cells in the “active set” (low level maybe, or bad quality, etc..)

    hard handover : it is the type of handovers used in 2G GSM, no doubt about that 🙂

    oh, i just found this :
    There are following categories of handover (also referred to as handoff):

    # Hard Handover

    Hard handover means that all the old radio links in the UE are removed before the new radio links are established. Hard handover can be seamless or non-seamless. Seamless hard handover means that the handover is not perceptible to the user. In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover.

    # Soft Handover

    Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN. Soft handover is performed by means of macro diversity, which refers to the condition that several radio links are active at the same time. Normally soft handover can be used when cells operated on the same frequency are changed.

    # Softer handover

    Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (i.e. the site of co-located base stations from which several sector-cells are served. In softer handover, macro diversity with maximum ratio combining can be performed in the Node B, whereas generally in soft handover on the downlink, macro diversity with selection combining is applied.

    (cf [url]www.umtsworld.com/technology/handover.htm[/url])

    #48954 Reply
    aso
    Guest

    Dear irfan
    as you know in 3G tackling with CDMA multiple access which depend on code not frequency or time as in 2G therefore this kind for technique is more sensitive and therefore it connect to two or more sites in the same time because may be send the same code which make it more reliable for Mobile to have precise signal strength

    #48955 Reply
    Irfan
    Guest

    Thanks a lot for guiding me

    #48956 Reply
    sasa
    Guest

    thanks a lot

    #48957 Reply
    paraHO
    Guest

    deaf and dumb, you said
    “…the mobile changes the code but not frequency…”

    Are you saying the code is the same for all Masts that the mobile is connected?

    or

    Are you saying a different code exists for each of the Masts the mobile is connected so that the mobile knowns to which Mast to handover?

    #48958 Reply
    Pedro Miguel Saraiva Santos
    Guest

    UMTS issue : We´ve seen lots of Dropped calls like this one : lot´s of “Measurement Reports” to delete one of the Radio links (1b), but with no “Active Set Update Update” message.The Best Scrambling Code CEll is with Good EcNo.Finally the Call Dropped.Why the system doesn´t delete the Bad Radio link cell, and that way save the call? Just Before the Call Dropped, sudden Increase of SIR.Any Explanation for this ?Thanks a lot, Pedro Saraiva

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