If we try to send uplink data in CELL_PCH what will happen?

Question

we know that in CELL_PCH only downlink data is possible.... in case if we try to send uplink data means what type of message we will get or will come?

Comments

Random Access procedure resulting in transition to Cell_FACH state followed by uplink packet transfer.

Answer 1

1. When UE has uplink data to send while in CELL_PCH, UE will send Cell Update message with cell update cause "Uplink Data transmission on Common Control Channel(CCCH).

2. On reception of Cell Update, RNC will upsize the call to CELL_FACH(if there is only one PS call existing) and if more than one PS call exists or has establishment cause, then it will upsize to CELL_DCH.

3. When upsized to CELL_FACH, RRC Cell Update Confirm will be sent to UE to which UE has to respond with RRC Radio Bearer Reconf Complete.

4. When upsized to CELL_DCH RL will be setup(NBAP RL Setup Req <-> NBAP RL Setup Response) and then Cell Update Confirm will be sent to UE, to which UE responds with Radio Bearer Reconfiguration Complete. Once synchronisation achieved between UE and NodeB, NodeB sends NBAP RL Restore Indication to RNC.