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TBF Reallocation

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  • #62416

    Hi Pix,

    Could you help me in explaining the parameter TBF Reallocation. I have seen this in an Alcatel material. Thats why asking you.


    TBF reallocation is not a parameter, it is a procedure.
    When a TBF is allocated and suddenly one of the PDCH timeslot is preempted for a TCH allocation, then you see the TBF must be reallocated : from 4 PDCH it is now reduced to only 3 PDCH.
    This is a TBF reallocation.
    Causes for reallocation are mostly :
    1/ TCH preemption (= reduction of PDCH)
    2/ Optimization (= increase of PDCH because the cell is less loaded now than before)
    3/ change of bias : the DL TBF is less used than the UL TBF, then DL TBF is reduced and UL TBF is increased

    There are some other causes for reallocation, ut they are very rare and complex to explain 🙂



    hi prabeen,

    If tbf soft limit is crossed then also chance of tbf reallocation.

    There is also one reason if u have edge priority is higjer than gprs .in this case only cs1 cs2 tbf reallocate


    hi pix, hi safar and others, just a little query in relation to this, if one TBF was ongoing and CV=0 situation arrives and Network has Extended ul tbf mode enabled, so if the TBF is extended will that also mean tbf is reallocated? i mean if tbf gets extended should it also be accounted as reallocation?


    hi ghamiz,

    If this feature is enabled the duration of UL TBF will be extend in order to quicly restart the data transmission in UL if higher layers in the MS deliver the new data,without having to re-establish a new UL TBF,after the countdown procedure has started.E.g to maintain the UL TBF established,some time after the last block(CV=0)has been acknowledge by the network.During inactivity period the BSS should keep the USF schedueling & reception of the UL RLC data block as long as uplink TBF is in extended phase.


    thanks vicky for the response. my own stance was the same but one of my colleagues at ZTE was insisting that a new tbf may be establised in extended phase. While i argued that if there is new tbf establishment, it would be against the very significance of EUTM…

Viewing 6 posts - 1 through 6 (of 6 total)
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