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timing advance measurement

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  • #52207 Reply
    TA
    Guest

    dear
    can any body help about TA measurement for statistic does measurement come from direct line of sight or non line of sight when BCCH or SACCH measuring for specific cell ??????

    #52208 Reply
    pix
    Guest

    timing advance is based on measurements performed on the TCH bursts, and it’s a mixture of LOS and N-LOS. There is actually no way to distinguish los and nlos.

    The TA you see in your statistics is the same TA that is measured by the BTS.

    #52209 Reply
    TA
    Guest

    dear pix
    thank you very much ? but i read in one document says that the (TA) is calculated on the first arrived propagation path which has a significant reception power level. what I understood is that LOS measurement????????????

    #52210 Reply
    pix
    Guest

    well, it can be LOS or it can be NON LOS… if there is LOS, then the first signal to arrive is LOS (the direct path is always the fastest). If there is some NLOS arriving almost at the same time (within the same wavelength), then the signal will be a mixture.

    if there is NLOS, then the LOS cannot reach the BTS. So the first NLOS to arrive will be used to compute the TA. And the first LOS to arrive might be a mixture between different NLOS.

    But why do you ask this question ? Maybe there is another question behind, isn’t it ?

    #52211 Reply
    TA
    Guest

    pix
    my point is that in my network there is measuremnt for TA ( from 0 to 63) and when i check this stat for specific cell for TA some cell it is TA reach MAimum which is 63 which means around 35 Km and this makes me surprise it is from LOS or NOn LOS

    #52212 Reply
    pix
    Guest

    the maximum ta measurement is not always reliable, because it can always happen that a MS has a wrong implementation and will tend to send its burst too late. Or maybe it’s a little problem in the BTS.

    The real question is : how many samples with TA=63 are reported during one day ? If it’s only 1 or 2…it’s not important at all.

    The important thing is to check the distribution of samples per timing advance, so you can see where are located 99% of the subscribers.

    The difference between los and nlos is not something that we can use in radio optimization, as far as i can see.

    #52213 Reply
    Johan
    Guest

    HI ALL

    In my experiance when you set TA value to maximum 63 doesn’t that you can make call 35 km i don’t think so becouse you will get very weak signal i think the best call you get is 30 km . by the way if you do tracing for one MSISDN ,Can you get his TA value .i mean how much the MS far from BTS ,is that possible ?

    #52214 Reply
    pix
    Guest

    johan,

    coverage up to 35km is possible, if the site has a great coverage in DL and in UL. With high power trx, TMA, Tx and Rx diversity, high antenna height, and very open area, etc.. with all this, there is absolutely no reason not to achieve 35km (easily)

    Most vendors has developped a solution in order to cover up to 70km with a GSM cell (extended cell solution).

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