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Syn. Frequency Hopping

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  • #43869 Reply
    Abdel
    Guest

    Hi everybody,
    I am telecom technician and my boss told me that i have to implement Syn. Frequency hopping on our GSM network. Can anybody provide some files about FH?
    Also I have a question, how must the TSC( Training Sequence Code) planned? any Idea?
    Regards

    #43870 Reply
    colein
    Guest

    you dont have to plane TSC (defaut value)

    #43871 Reply
    Abdel
    Guest

    Hi Colein,
    Thanks for your quick response,
    I am little confused with the term frequency load? In my network the max. BTSs is S888 and i have 11 frequencies for Synthesized frequency hopping therefore will it enough to use that number of frequencies or does it need more?
    Regards

    #43872 Reply
    colein
    Guest

    for configuration 8/8/8 you need 3frequenceis BCCH, AND for hopping TCH you must use hopping frequency set more than your carriers on sector.
    So to abtain acceptable result (9 frequency per sector plus one for BCCH => (9×3 + 3)= 30 freq.
    BUT the more you use big hopping freq set,the better you get good signal quality.

    #43873 Reply
    yrrah
    Guest

    It depends on the reuse pattern you want to use.
    If you go by 1*1 (1MAList for all your sectors), you need at lesat 44 frequencies for your hopping list.
    If you go by 1*3 (1 MAList per sectors, 3 MAlist that are repeated on a site basis), you need 42 frequencies for your hopping list (14*3).

    Regards

    #43874 Reply
    areeba
    Guest

    hi yrrah
    for 1*3 (1 MAList per sectors) it is good to use 14*3FHS, BUT 8*3 is also posible but the efficiency is low than 14*3 but accepted.

    #43875 Reply
    Santo
    Guest

    Hi All,

    Have you ever implement SFH for 4 sectors site and it has neighbor 3 sectors sites ? And how it performance.. ?

    Thanks

    santo

    #43876 Reply
    yrrah
    Guest

    Hi areeba,
    it depends on the number of hopping TRX you have.
    If you want to avoid collison (co channel or adjacent channel), you need at least twice the number of hopping TRX. If you have less frequencies, you will face collision.
    Your MAIO planning will be more difficult too.
    If you have any info how to allocate 3*8MAlist if you have S888 sites, i would like to know.
    I heard about a new planning strategy called “Ad Hoc” for SFH.
    you allocate your frequencies list on a cell basis. The length of the MAList depends on the number of TRX you get.
    I’m searching some informations about it, but it seems too hard to get anyone.

    Regards

    #43877 Reply
    areeba
    Guest

    yrrah
    Yes in SFH its mandated to establish MAL twice or more than your TRX in sector.
    BUT see that: the main idea of the hopping is to averaging the interference in all channel. SO as more as you add freq to MAL above the twice no of TRX per sector as you have better performance based on quality enhancement.
    Cuz you deal here with (frequency selective fading). & any environment has a certain coherence fading (the BW between two frq which it high correlated for fading).
    SO:
    Rural: delay spread(low)===>coherence fading is high===>need large BW of MAL to deal with such fading seemed to be flat fading.
    Urban: delay spread(medium)===>coherence is medium==>need medium MAL BW.
    Dence urban: delay spread(high)-=>coherence is small==> need low BW MAL.
    AND INDOOR: delay spread is tooo small==>coherence fading is tooo large (flat fading) ====> need tooooo large BW MAL to deal with such fading (not practical),

    #43878 Reply
    areeba
    Guest

    For 8*3freq if you have S888 sites it will be:
    MAlist= A(8), B(8), C(8).
    SO you can use the following dimensioning:
    SectorA ==> MAList(A+B)
    SectorB ==>MAList(B+C)
    SectorC ==>MAList(C+A)
    But the orthognality performance with MAIO will be throug different algorithm.
    BR…..

    #43879 Reply
    Salvador
    Guest

    Dear areeba,

    can you explain why in indoor the delay spread is too small. On the other hand, what it is the diferent algorithm the for orthognality performance with MAIO?

    #43880 Reply
    seth
    Guest

    the power delay profile of RX signal at in-door environment is too small compared with other environments

    #43881 Reply
    turd!
    Guest

    Colein,

    How did you get 9 freq per sector plus 3 for BCCH? can you tell me those parameters? What I mean is what is the 9 freq and 3 frequencies.

    thanks!!!

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