RRC connection till ALCAP message

1. The UE initiates the establishment of an RRC connection by sending RRC CONNECTION

REQUEST message on logical channel CCCH. The UE transmits to the RNC its initial UE

identity, which can be P_TMSI (Packet Temporary Mobile Subscriber Identity) + RAI

(Routing Area Identity), TMSI (Temporary Mobile Subscriber Identity) + LAI (Location Area

Identity), IMSI or IMEI (International Mobile Equipment Identity).

2. Upon reception of the RRC Connection Request the RNC performs Admission Control and

allocates the U-RNTI (UTRAN Radio Network Temporary Identifier) for the UE. Also, layer 1

and layer 2 related resources (RLC, MAC, Radio Link and DCH parameters) are determined

for the RRC connection.

3. RNC sends a C-NBAP (common - NodeB Application Protocol) message RADIO LINK SETUP

REQUEST in order to configure the needed BTS side resources for the Radio Link. Several

Radio Link and DCH related parameters allocated by the RNC are included in the message.

The parameters include the scrambling and channellisation codes, supported transport

formats, and power control information. Also the identifiers for the DCH, Radio Link and

Cell are included.

4. After allocating the physical resources the BTS starts physical reception and responds to

the RNC with RADIO LINK SETUP RESPONSE. The message parameters include the

Binding Identity, Traffic termination point identifier and AAL2 Endpoint Address of the

BTS.

5. Serving RNC initiates the establishment of Iub Data Transport bearer by sending the

ALCAP ESTABLISH REQUEST message to the BTS. The request contains the AAL2 Binding

identity received from the BTS in the previous message. The Binding identifier is used to

bind the ongoing BTS Radio Link Setup and ALCAP of Iub Data Transport Bearer

Establishment transactions together.

6. The request for the establishment of Iub Data Transport bearer is acknowledged by BTS

with the ESTABLISH CONFIRM message.