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Reply To: D/L TBF establishment


You are Right.
Hope this explanation clears your doubt
The purpose of this function is to be able to set up a Downlink TBF using PACCH shortly after the release of a DL TBF. When a downlink TBF is released, the MS starts timer T3192 and stays on the PACCH until T3192 expires. In the BSS there is a corresponding timer T3193 that is started when the TBF has been released. The PDCHs that were assigned to the TBF are still reserved for the MS for the duration of timer T3193.If more data arrives from SGSN before T3193 has expired, a new DL TBF is set up and PACKET DOWNLINK ASSIGNMENT message is sent to the MS on the PACCH. The poll bit is set in the message indicating that the MS shall answer with a PACKET CONTROL ACKNOWLEDGEMENT message.

If this message is not received by the BSC new attempts (maximum 3) to set up a downlink TBF are done. New attempts to set up a downlink TBF can be done using PCCCH, CCCH, PACCH (normal) or PACCH (after release) depending on the traffic situation and the configuration of the BSS.

If this message is received, the downlink scheduling is started and the downlink TBF is established.

PDCHs and TBF is finally released if/when BSS timer T3193 expires after which normal set up of downlink using PCCCH, CCCH or PACCH will have to be used to set up a new downlink TBF