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BB Hopping

Viewing 15 posts - 1 through 15 (of 18 total)
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  • #58202 Reply
    Alf
    Guest

    Hi all,

    Is there any disadvantage or advantage of activating BB Hopping to 2 TRX only?

    #58203 Reply
    Pix
    Guest

    Disadvantage : only 2 frequencies are hopping (high frequency diversity is achieved wen 4 or more freq are hopping)

    Advantage : still better than non-hopping

    #58204 Reply
    cool
    Guest

    Hi Pix

    I’ve facing problem with BB hopping for few of my cells. When disabled no of drop is around 350 but when enabled drop increases sharply to 1400. It’s amazing. What can be the logic of it ??

    #58205 Reply
    KP
    Guest

    Please check the Mobile allocation list in IMM ASS msg and SI change mark field in SI13.

    #58206 Reply
    pix
    Guest

    hi cool,

    sorry i missed your post.
    have you found the issue ?

    I would say that there is probably a configuration issue, or a faulty TRX.
    Last possibility, less probable though : perhaps one of the Hopping frequency is very interfered.

    One would need full information in order to troubleshoot more specifically.

    cheers
    pix

    #58207 Reply
    Cool
    Guest

    Thanks pix !! I’m nt being able to visualize abt d configuration problem. What type of config problem can it be, if u can name few. It’s a 2 trx cell with around 15 erl traffic. Means both trxs have almost similar attempt. So if trx is faulty or one frequency is interferred, no. of drop should b high irrespective of BB hopping. Rather no. of drop should b hogher whn disabled. I didn’t send any drive test team so can’t check SI13.Please b informed tht it’s a huawei system. Anyway thanks again fr ur reply. Kindly don’t delete this issue from ur brain.

    #58208 Reply
    pix
    Guest

    oh, i don’t delete anything from my brain… but beer does 😀

    ok, radio is good, then so it is definitely a configuration issue or a hw issue..

    I’m not familiar with Huawei. The best would be to read slowly their “operational guide” to activate the BBH… maybe you missed a step ?

    I’m not sure how I can help, i’m sorry.

    did you activate it successfully in another site ?
    Cheers,
    pix

    #58209 Reply
    Dell
    Guest

    Hi,
    I have a question, wich is better in terms of voice quality, BBH or SFH? In an urban area with the conf 4x4x4 we want to switch to BBH from SFH . According to AFP there is better quality than SFH. Number of freq is 50. Vendor is ALU. Any idea?
    BR,
    Dell

    #58210 Reply
    Dell
    Guest

    Anybody?

    #58211 Reply
    Lemaure
    Guest

    Hi Dell,

    my post is a bit long so i’ll do it on many posts.
    both BBH and SFH have advantages/disavantages. Indeed, SFH has a poor AFP than BBH but this is usually compensated with some parameters (OFFSET_Hopping_HO&PC, OFFSET_RXQUAL_FH,…)that should be tuned once the frequency plan is implemented. the efficiency of SFH depends on the load factor of your cells. It means the number of frequency you reserve for hopping should be sufficient in order to ensure a RLF (Real Load Factor) less than 11% on your urban area. you should also reduce overlapping between cells with priority on high loaded zone. the quality of network dealing with SFH depends on the good design of cells. also, with SFH it would be easier to integrate new cells or add a new TRX on a site (no more TCH frequency seeking, MAIO are now used).

    #58212 Reply
    Lemaure
    Guest

    frequency plans with BBH are to tight where traffic is high. For your case, your reuse partern is 50/4 about 12 not to good in GSM because the reference value is around 15. If you separate BCCH and TCH bands (mandoratory to avoid HO Fail)your TCH reuse partern would be less than 12 still not to good, because you will need at least 15 frequencies for your BCCH.for me it is better to implement SFH; you should just be careful with your design.

    #58213 Reply
    Dell
    Guest

    Hi Lemaure,
    thank you very much for your explanations.
    I’ve changed to BBH in one of urban areas 11 BTS in DCS 1800. The rest are GSM900 which are still in SFH. I noticed that there are improvements in quality, especially UL for 1800 MHz. I’m not sure if it will succeed with the rest of 15 BTS in GSM900. Another question, is BBH better in terms of penetration indoor in DCS1800?
    BR,
    Dell

    #58214 Reply
    Lemaure
    Guest

    Hi Dell,

    Indeed, it i easier for u to use BBH for BTS in DCS 1800 because I guess you have enough frequencies in this band than in GSM900. For the 15 BTS remaining, to switch from SFH to BBH, you should not have too much traffic to manage in this GSM 900 band or if its the case you may push it towards the DCS 1800 (if BTS 900&1800 are colocated for instance).
    to come back to your question,I think the penetration does depend only on the power of the signal and the frequency band used irrespectively to the type of hopping adopted.

    #58215 Reply
    Dell
    Guest

    Hi Lemaure,
    we cannot use collocated cells, don’t have the multiband feature yet. In DCS1800 there are 50 channels, in GSM900 50 channels.
    Thanks again for your help
    BR,
    Dell

    #58216 Reply
    pix
    Guest

    Hi Dell,

    Just one more info : the RXQual measured in SFH is artificially lower than in BBH. It doesn’t mean the voice quality is worst in SFH than in BBH.

    You must perform Voice Quality measurements in order to know that for sure.

    It’s interesting to test BBH vs SFH, however:
    1/ SFH is so easy to use, considering the high amount of freq you have… Just properly downtilt your antennas
    2/ it requires VQ measurements, to get the full picture.

    Regarding radio coverage (indoor penetration, for example),

    Radio coverage at the cell edge is enhanced when Hopping over 4 or more frequencies. This is known as “frequency diversity”. That increases radio quality (a lot) & radio coverage (a little), compared to No Hopping.

    If you have 4 or more TRX, then it means the TCH will hop over 4 or more frequencies, which is optimal for Frequency Diversity, regardless it’s BBH or SFH.

    Regards
    pix

Viewing 15 posts - 1 through 15 (of 18 total)
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