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Interference on Idle TCH

Viewing 15 posts - 16 through 30 (of 31 total)
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  • #49286 Reply
    agz
    Guest

    Guyz,

    is it like,the BTS measures the noise in complete band or just the BCCH freq and freqs we have defined in the Mal list as u ppl have said..m am a bit confused..suppose if there is nil traffic in the cell and all the timeslots are idle,then how does it measure the noise in the freqs which r defined in turn…does it measure all the freqs defined in MA list randomly or will it follow the MAIO…

    #49287 Reply
    agz
    Guest

    Besides to make myself clear..for instance,if in BTS A, all the timeslots are idle and a BTS B which is adjacent is having calls and happened to use some of the freqs of BTS A..now what does BTS A dO??? BTS A hears the noise on the freqs which have been assigned to it..but now since some of the same freqs are used by BTS B also,BTS A hears the same and measures the received level and report as noise in that freq..and thus the measurements are aggregated and reported????
    do they hear both UL and DL freqs..or only UL freqs..??

    #49288 Reply
    SHELDON
    Guest

    Hi agz,

    In the scenario you described, BTS A will measure the signal received from BTS B on each of its timeslots and report it as noise to the BSC.

    The basic idea behind the idle channel measurements is this: The BTS measures the received signal level on ALL idle TIMESLOTs and reports these values to the BSC as the noise levels on the timesots. These measurements are done only on the UL. The measurements enable the BSC to judge the level of interference on each timeslot, so that during channel allocation, it can assign the channel with the least interference (if your channel allocation algorithm uses quality as the criterion). I’m an ericsson person, and what I’ve said relates to ericsson.

    Regards,
    SHELDON

    #49289 Reply
    agz
    Guest

    Hi Sheldon,
    Thnx 4 d reply..so does that means BTS A when measures on idle slots ,it measures only its frequency allocated(both BCCH and TCH),and if the same freqs are there on BTS B,BTS A will report that as interference…and besides that too on uplink..so is it like that it will measure only the signals from mobiles(UL)which are in BTS B that happened to come to BTS A???

    #49290 Reply
    pix
    Guest

    agz,

    yes, i think you got it 🙂 Just to clarify even more :

    BTS A measures the UL RxLev on all its idle TCH.
    For each TCH, the measured frequency is the actual one from the MA List. Every TDMA frame the measured freq is changed if BBH or SFH are activated.
    (that’s for alcatel)

    Cheers
    Pix

    #49291 Reply
    agz
    Guest

    hey pix,nice 2 c u joinin…
    consider if all the timeslots of the cell are idle..then what will be the case…from which freq will it start to measure from the MA list…does it measure in a round robin basis..or something else???
    and as discussed,if the measurement is UL only,then does measurement of a distant MS obviously from other BTS(in our case BTS B) has a good signal strength to fall into INT BAND 5 criteria of BTS A..

    #49292 Reply
    pix
    Guest

    agz,

    yes, the ul rxlev from a “neighbour” MS will be reported into a high intf band.

    in case of hopping TRX, the average rxlev measured over one hour is done over all hopping freq.
    I don’t understand your issue with the hopping…
    each TDMA frame, the measurement is done on the freq of the MA list. There is no MS in the cell, ok, but the MA list is still hopping normally 🙂

    Cheers
    pix

    #49293 Reply
    Vanderley
    Guest

    Hi,

    As far as I know (Nokia also) you have thresholds defined by you for the 5 IF bands. The interference on idle is measured only in UL, which means that only mobiles or external sources could be the reason (99% falty equipment or other bad guys – military etc.)
    If you have any kind of hopping and you want to know which freq is interferenced you have to stop the hopping – no other way. But you could go to 15min measurements and stop it just for that time – it usually becomes obvious at once.
    Hope I help.

    #49294 Reply
    RUAA
    Guest

    HI
    I NEED YOUR HELP TO KNOW HOW THE INTERERFERANCE MEASURE & any more affected up or domn links intereference & what intereference levels for Motorla equipments.

    #49295 Reply
    fai
    Guest

    Hi guys,
    as our MS is in IDLE mode, it carries BCCH freq,as the call intiated to dedicated and MS in hoping case it may be HR/FR,will the interference effect with co-bcch,as our ms under hoping state with MA List.practically observed great interference.but how to explain for the clear clarification.and it is also clear that MS will be carrying the BCCH signal.Pls clear

    #49296 Reply
    pix
    Guest

    hi fai,

    could you explain more? I can’t understand your question.

    regards
    pix

    #49297 Reply
    Mickey
    Guest

    Hi Pix,

    Interference discussion is really gr8, Helped a lot, But i am still not clear with below point.

    1.Will both BCCH & TCH Freqencies are measured.

    2. How i will judge interference.
    Suppost I have counters based on idle interfband 0 to 5 & i have a value of “15” in band 1 & a value 18 in band “4”. So what “15” & “4” exactly mean & how to see if there is interference from these 0-5 bands.

    #49298 Reply
    Aloysius
    Guest

    What is the cause of interference on dedicate mode?

    I experienced an issue during refarming on BCCH. We were on for example 68-92. Then we had to use 48-66. After the change few cells could not pick up its neighboring cells on the range from 48-66 has planned but picked up the ARFCN frequency range from 68-92.

    What could be the possible cause of these?
    I use both nortel and huawei systems and the issue is with the Huawei BTS not able to handover to nortel bts in the ARFCN range from 48-66 but instead picking up the 68-92 frequency range. All parameters have been checked but issue still exists.

    #49299 Reply
    pix
    Guest

    hi aloysius,

    What do you mean by a bts “picking up” the signal from a neighbouring cell ?

    Each cell is defined with a list of neighbour BCCH’s. For example, in your case, let’s assume a cell with 5 neighbours. In the OMCR you will declare 5 neighbours for this cell. And the system, internally, will interpret this list of cells as a list of BCCH :
    BCCH ARFCN of the neighbours = 47, 51, 52, 56, 61

    Then the MS in this cell will only measure those ARFCNs and consider only those as potential target cells for reselection or handovers.

    Reading your post, it seems to me that you didn’t declare the right neighborus in the cells. Since you are talking about inter-OMCR handovers, the problem probably lies in the declaration of the external cells :
    -> in the Huawei OMCR, you must declare a list of external cells (= nortel cells), with their proper CI, LAC, BCCH and BSIC.
    Then, include the relevant external cells in the “list of neighbours” of the huawei cells.
    -> in the nortel OMCR, declare the external huawei cells, and use them as neighbours.

    regards,
    pix

    #49300 Reply
    Aloysius
    Guest

    Hi Pix,

    Thanks for the info, much appreciated.

    However this is what I am experiencing during Drive Test.

    1. We have re-tuned our BCCH ARFCN frequency range from 66-92 to 48-66, that is 18 BCCH ARFCN channels to use.

    2. Both Huawei and Nortel handover and reselction parameters have both been defined on Nortel(OMCR and Huawei(BSC600), neighbors, LAC,CELL ID, etc..

    3. Issue:
    During drive Test on particular sites for Huawei and Nortel, we have some cells still locked onto the BCCH ARFCN range from 66-92 and NOT the 48-66 has planned. Those particular cells have been not adapt to the changes carried out. This particular Nortel and Huawei cells are not seeing the 48-66 BCCH ARFCN has planned.

    For example new BCCH ARFCN range 48-66(new BCCH), 68-92(old BCCH), We did a DT and this particula BTS had sector-1(48), sector-2(54) and sector-3(78). Why is sector-3 behaving this way? Sector-3 is also is identifying nehgbor BCCH from the range 66-92 which is confusing. Is it because of interference due to the limited bandwidth.

    Appreciate your thoughts.

Viewing 15 posts - 16 through 30 (of 31 total)
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