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Temporary Offset

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  • #61450 Reply

    Dear All,
    I am confused regarding the role of temporary offset in cell reselection.
    I have gone through manuals and also threads on this forum.
    My conclusion regarding C2 parameters are
    CRO: is used to give priority to cell and cell is reported to have better rxlevel then it actually has.
    e.g if CRO is 1(2db)means actual rxlev -60 but reported as -58.
    Penaly timer: it is the time which is used to keep the MS stay on the cell it is already camped.
    if we increase PT it will delay the MS reselection time to other cells.
    TO: value 1:10dbm
    I am confused with this in formula it is CRO – TO
    so if we give Temporary offset will it reduce chances of cell to reselected like if actual rxlev is -60dbm then during PT time cell rxlev will be reported as -70dbm due to Temporary offset.
    if i am correct it means temporary offset is used to penalize a cell chances to be reselected.
    Please guide me in this matter.
    Thanks in advance.

    #61451 Reply


    the C2 of a cell is decreased by “TEMPORARY OFFSET” during the time “PENALTY TIME”.

    CELL RESELECT OFFSET allows to increase the C2 of a cell indefinitely.

    If C2 of cell n is lower than C2 of serving cell, the MS stays in serving cell.

    if C2(n) > C2(s) then the MS goes in cell n.


    #61452 Reply

    Dear Pix,
    Thanks for your reply.
    So why we prefer to go for PT=31 and CRO to penalize a cell.
    I mean to give it less priority to divert traffic to other cells rather then going to use TO to penalize a cell.
    Your response is highly appreciated.

    #61453 Reply


    I have noted at PT=31, C2=C1-CRO where as if PT not= 31, C2=C1+CRO-TO*H(PT-T).

    Y we opt for PT=31? also, wat is TO, H, PT and T? theorotical Description is there with me, but i need the practical.

    #61454 Reply

    hi Prabeen,
    we Opt for PT=31 if we want to penalize a cell during cell re selection.
    It will give negative CRO during cell re selection.

    #61455 Reply

    I think,when t is less than the penalty time,then the value of H=1,WHICH GiVeS U A FORMULA,C2=C1+CRO-TO*(PT-t)…

    Bt once t exceeds the penalty time ,then H will bcom zero,by which,
    C2=C1+CRO….THUS anywz C2>C1,which will lead to camping on to the new cell….

    #61456 Reply

    PT=31 is a special case that i didn’t bother explaining. sorry about that.

    This special case is :
    If PT = 31, then TO is useless and the formula is C2 = C1 – CRO, all the time. This will apply indefinitely.

    The usual case is :

    if PT < 31, then C2 = C1 + CRO - TO during PT. After PT, C2 = C1 + CRO only. All previous posts by prateen, bht, and agz are correct, so i don't know where is the problem... you just needed a confirmation ? Now let's go a little further : if you want to penalyze a cell, 1/ either you put PT = 31 and increase the CRO. Therefore C2 will decrease. 2/ or, you increase the CRO of the neighbour cells (assuming you never set PT=31 in any cell, i.e. you are in the "usual" case) Best Regards, pix

    #61457 Reply

    Hello Pix,
    I think i was unable to explain the purpose of this thread.
    Actually i was trying to make say that why we use PT=31 in cases when we want to divert traffic from one cell.
    Why TO is not used more often in these cases?
    Is using TO is not an efficient way?
    Thanks in advance.

    #61458 Reply

    Hi BHT,

    The PT is used to penalise micro or picocells, so that (fast) moving MSs do not reselect those cells.
    Consider an MS on a highway being covered by a macro cell. If this MS enters the coverage area of a micro cell, it will try to reselect this cell. After it moves out of the micro cell’s coverage area, it will then have to reselect the macro cell. To prevent this, the PT of the micro cell can be set to eg 15s, to ensure that the MS reselects this cell only if it has stayed in its coverage area for more than 15s. That’s how the PT is used.



    #61459 Reply

    Hi Sheldon,
    Thanks for the explanation.
    Best Regards,

    #61460 Reply

    BHT : I confirm, the initial post was unclear 🙂

    As Shelon said, the use of PT+TO is a temporary penalty. To be used to distinguish fast moving traffic and slow moving traffic. Or just to avoid ping pong when the MS is in between 2 cells for a while.

    The PT=31 + negative CRO is a static penalty, to be used to divert traffic.
    (I’d rather give a static bonus to neighbour cells though.)

    (sorry to repeat what sheldon has said…)


    #61461 Reply

    My apologies for ambiguous post.
    Thanks once again for your help.
    Best Regards,

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