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TA

Viewing 15 posts - 1 through 15 (of 16 total)
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  • #55734 Reply
    uji
    Guest

    kan nyone plz explain TA (timing advance)

    #55735 Reply
    Pix
    Guest

    Uji,

    Mister MKT can help, perhaps ? It’s about time he shares his knowledge a little 🙂

    #55736 Reply
    MKT
    Guest

    Hi, Pix..

    I like your sense of humor.But let me clarify that i am not a man of “knowledge”.

    For me knowledge(destination) is always second….the approach(path to destination) is first.

    I see my self as an man of approach, not a man of knowledge.

    In USA, they always stress for that whatever written in book should be questioned for why and how.
    Unfortunately in the part of world where i took birth doesn’t have time and money for the thinkers on the above lines.

    Regards,
    MKT,India

    Regards,

    #55737 Reply
    Pix
    Guest

    … no, this is a defense strategy. Who think of himself as an “upper” thinker is just more concerned about his pride getting few dents 😉

    You know about Timing Advance.

    Share with us, in one paragraph only. See it as an exercise for a soon-to-be trainer… (that’s what we do during trainers’ interviews)

    Please 😉

    #55738 Reply
    uji
    Guest

    hay guys kan sumbody tell me abt TA or i shd sit a side n watch u guys ving gud dialouges
    kumon PIX

    #55739 Reply
    Pix
    Guest

    Uji,

    Please, sit aside and read.
    click on “search” on the side of this website,

    search for timing advance.. you might find many posts about this…

    regards,
    pix

    #55740 Reply
    positive telco
    Guest

    Timing Advance is counter which measurement traffic distribution. such as,
    TA level 1 is that subscriber location less than 0.5 km. Usually this parameter to measure traffic distribution of GSM and DCS. Actually on area which near BTS level 1 and 2 , DCS should be attractive than GSM. Like that lah..

    #55741 Reply
    MKT
    Guest

    Hi Uji,

    Here is my explanation of TA(Timing Advance) concept in GSM.

    The MS and BTS communicates with each other using the radio(electromagnetic)waves.

    Timing Advance is a concept employed in GSM when the MS enters into DEDICATED MODE.

    In IDLE MODE the Timing Advance has no significance.

    What ever information MS transmits over a given TS reaches the BTS with a speed equal to the velocity of light(c). But even with this speed there occurs a delay. To address this delay the concept of Timing Advance has been evolved in GSM.

    The definition of Timing Advance:

    In the GSM cellular mobile phone standard, timing advance value corresponds to the length of time a signal from the mobile phone takes to reach the base station. GSM uses TDMA technology in the radio interface to share a single frequency between several users, assigning sequential time slots to the individual users sharing a frequency. Each user transmits periodically for less than one-eighth of the time within one of the eight time slots. Since the users are various distances from the base station and radio waves travel at the finite speed of light, the precise time at which the phone is allowed to transmit a burst of traffic within a time slot must be adjusted accordingly. Timing Advance (TA) is the variable controlling this adjustment.

    Technical Specifications 3GPP TS 05.10 and TS 45.010 describe the TA value adjustment procedures. The TA value is normally between 0 and 63, with each step representing an advance of one symbol period (approximately 3.69 microseconds). With radio waves traveling at about 300,000,000 meters per second (that is 300 meters per microsecond), one TA step then represents a change in round-trip distance (twice the propagation range) of about 1,100 meters. This means that the TA value changes for each 550-meter change in the range between a mobile and the base station.

    …..contd

    #55742 Reply
    MKT
    Guest

    Imagine the picture:

    Often the term TA is described with word like MS advances its transmission by time corresponding to the value of TA.

    The confusion starts from here. In dedicated mode, whatever I am speaking is to be transmitted exactly at the same time. How can be it is possible that MS advances its transmission without my lips has uttered the words??

    …..CONTD

    #55743 Reply
    MKT
    Guest

    We the human beings …belongs to a world which uses a watch(wrist watch) for synchronizing our life our activities.
    Lets us say if it is 6 PM in my watch then it will be 6 PM in your watch too if we are in the same part of world.

    But,

    The MS belongs to a different world…… which is termed as GSM.

    All the MS synchronizes there watch(s)from BTS. Just see the term watch replaced with clock in this case.

    With the above background …

    just read this…

    It is all there in the name itself. Its “Timing Advance”.

    Let us say it like this:

    A MS will use SCH initially to know the time(TDMA) of network/BTS first.

    But before entering into the dedicated mode the MS will be told by the BTS to correct its watch(the one which is to be used for Tx)using the given TA.

    Also for Rx the MS need not to do anything as BTS is taking care of adjusting its watch attached to the particular TS of MS under question.

    To make the circuitry inside MS somewhat simpler (As MS need not have to send and receive simultaneously), The concept of difference of 3 TS between UL/DL or Tx and Rx is there in GSM.

    MS adjusts its clock as per the clock(1) of BTS. Under hypothetical condition(assuming no delay)….MS will use clock(1) for listening(Rx) and speaking(Tx)…….MS will apply a difference of 3TS between Tx and RX. Everything is fine here and happy ending.

    contd……

    #55744 Reply
    MKT
    Guest

    But in reality..
    A delay is there….BTS senses this….and he(BTS) tells the MS to advance its timing for speaking a little bit(TA)….MS will now start speaking early(TA)….and BTS starts listening the MS well at the schedule time…But same should be applicable to BTS also….he knows that if is getting the speech of MS delivered late to him so do the MS also….hence BTS also applies a TA on the TS allocated to the particular MS…..

    But MS has to apply the concept of speaking(Tx) 3 TS later after Rx…..Now he is listening to BTS as the clock(1)……..MS cant do any changes wrt to clock(1)…hence MS has to use a separate clock(2) for Tx. However the clock(2) will no doubt be derived from clock(1).

    contd..

    #55745 Reply
    MKT
    Guest

    Sequence is like..

    a) get clock(1) from BTS through SCH

    b) use this clock(1) for Rx

    c) apply a difference of 3 TS to this clock(1) for Tx . let us say the new time is clock(2).

    d) But as per the wish of BTS apply a correction of TA to clock(2) and finally use this resulting clock time for transmitting.

    REGARDS

    #55746 Reply
    MKT
    Guest

    So,TA is for any individual MS is:

    1. calculated by BTS
    2. used by MS in UL
    3. used by BTS in downlink

    sorry for posting in parts…
    not sure which part is restricting the post to be seen.

    #55747 Reply
    Kamal
    Guest

    Hey MKT,
    Great man…u have told whole ‘geetha’ of TA..hope uji will find it very clear…
    What do u say pix?
    From my side, 9.5 out of 10…..
    BR,
    kamal kotecha

    #55748 Reply
    uji
    Guest

    hay mkt thanku so very much 4 dis explanation seriously i can neva find dis kinda explanation 4rm ny side
    thanx again

Viewing 15 posts - 1 through 15 (of 16 total)
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