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2G to 3G HO

  • This topic has 56 replies, 1 voice, and was last updated 2 years, 1 month ago by push traffic to 3G.
Viewing 15 posts - 1 through 15 (of 57 total)
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  • #61889 Reply
    RK
    Guest

    Dears
    can you please let me know what are the reasons due to that HO from 2G to 3G fails? I had one event like Intersystem Handover of CS12.2k Voice Service (GSM to UMTS ) was unsuccessful.

    Please help me!!

    #61890 Reply
    coldfire222
    Guest

    hi rk,

    a lot of factors affects isho. have the isho parameters checked first.

    cf222

    #61891 Reply
    varun sharma
    Guest

    Hi RK,

    Reason of 2G to 3G HO Failure is:

    1)If 3G coverage is also poor.
    2)Neighborlist of 3G is not defined properly.

    #61892 Reply
    Ayat
    Guest

    Hi our vendor is ZTE

    and we are only using handover from 3G to 2G .

    i do not knwon why we do not use handover from 2G to 3G ??

    do you knwon

    #61893 Reply
    machine
    Guest

    pls, what could make 3G to 2G handover failure increase by 50% in a day. No parameter change was implemented on radio part. Cud it be possibly due to transmission problems?

    #61894 Reply
    pix
    Guest

    perhaps the 2G cell was congested that day ?

    #61895 Reply
    machine
    Guest

    Tx Pix for the response. but there was no congestion on the 2G, this is actually happening across an entire RNC.

    #61896 Reply
    pix
    Guest

    so the problem is from 3G to 2G ? (your title suggests the opposite)

    then it probably has to do with core network parameters, or a core network routing failure.
    Is it still happening today ?
    Check that the interworking & LAC/CI definitions of 2G and 3G is well defined in the call server / MSC.

    #61897 Reply
    AliAsgher
    Guest

    I wanted to ask just the same question. Why do most of networks donot implement 2G to 3G handovers? I have seen in Ericsson networks that 2G to 3G handover feature is not implemented. But why?

    #61898 Reply
    Sunny
    Guest

    3G is usually overlaid on the 2G so most likely you will run out of 3G service before 2G during a call.
    So it make more sense to allow 3G to go 2G than the other way round.
    This is true only for dedicated mode, in idle mode both 3g and 2g reselection is allowed . So mobile can reselect to UMTS again when the target EC/IO is met

    #61899 Reply
    paul
    Guest

    Dear All,

    I’m working in 3G Huawei.So,
    related to HO 3G to 2G, and its selection/reselection :

    First of all, we should make a proper adjacency with 2G Cells. Ensure that the LAC of the adjacent 2G (neighbor) must be enlisted in RNC and vise versa (RAC 3G is also listed in OMC 2G). If both requirements are not reached, then there will be no HO happen between 3G-2G.

    In 3G Huawei, each node B has its parameter that arrange the HO, at what level of RSCP the HO happens. So does reselection.
    Remember, 3G capacity is based on CE (channel elements).

    We know that 3G is focused on Packet data services which mean, most its capacity is for Data, not voice. We can also see the RNC license, the maximum voice Erlang could be handled by its RNC.

    So how to control it? For reselection, check LST UCELLINTERRATHOCOV, check parameter Inter-RAT R99 PS measure start RSCP THD[dBm], Inter-RAT R99 PS measure stop RSCP THD[dBm], for HSDPA , and also for CS selection.
    This parameter indicates whether you want the reselection from 3G to 2G happens faster (at strong 3g signal level, HO/reselection happens), or slower (keep the UE always attach to 3G even at the weak level RSCP).

    Why most of vendor don’t implement 2G ==> 3G Handover? From my point of view :

    The principal understanding of Capacity between 2G and 3G is different. As I know, If one UE attach on 3G and make a call in 3G, that it will spend 1 CE. How about alot of UE use 3G for call? Instead, we should remember about the throughput in 3G (SF8,SF16,SF32). The smallest SF is defined (e.x SF8), the higher throughput will be get and the fewer UEs can attach to 3G. The higher throughput, the higher CE (CHannel elements) are needed. Please correct me if I’m wrong.

    Well, that’s what I know, please feel free to discus about 3G 🙂 It’s interesting topic to discus 🙂

    Best regards,

    Paul

    #61900 Reply
    Sunny
    Guest

    I guess the startegy is to keep the two network as independent as possible , unless it is necessay to save a call due to lack of coverage(IRAT)/Capacity(ISDR) .
    Both 2G and 3G are using 5.9 amr so voice quality is the same.
    Howeve the edge data user have to go have to idle mode reselection to 3G.
    So it is important to put the 3G access parameter to floor , so it wont select 2G untill 3G is dead

    #61901 Reply
    ayat
    Guest

    in my case the 2G covergae is larger than 3G coverge , but is there any reason prevent to active these 2 feature , handover from 2G to 3G and from 3G to 2G

    ???

    #61902 Reply
    sunny
    Guest

    2G coverage > 3G
    1.You need 3G to 2G HO(IRAT) and IRAT should not be prevented otherwise you will drop the call.

    2. I believe 2G to 3G HO should be prevented to avoid unnecessary loading of 3G system . As I mentioned the voice quality is same for both 2G and 3G , both are using same codec amr 12.2 or 5.9.

    #61903 Reply
    machine
    Guest

    Hi Paul,
    I am interested in your analysis, please do you have such information on Alcatel 3G system, the common parameters to tune. Here, it seems the only thing they’re doing is just azimuth and tilt modifications.

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