Editing My Intra-NR Notes (section)

=== 9.2.1.3 RRC_IDLE State Transitions ===

The following figure describes the UE triggered transition from RRC_IDLE to RRC_CONNECTED (<span style="color:red">for the NAS part, see TS 23.502</span>):

<center>[[File:UE triggered transition from RRC IDLE to RRC CONNECTED.png|UE triggered transition from RRC IDLE to RRC CONNECTED sequence diagram]]</center>

: 1. The UE requests to setup a new connection from RRC_IDLE.
: 2/2a. The gNB completes the RRC setup procedure.
: NOTE: The scenario where the gNB rejects the request is described below.
: 3. The first NAS message from the UE, piggybacked in ''RRCSetupComplete'', is sent to AMF.
: 4/4a/5/5a. Additional NAS messages may be exchanged between UE and AMF, see TS 23.502.
: 6. The AMF prepares the UE context data (including PDU session context, the Security Key, UE Radio Capability and UE Security Capabilities, etc.) and sends it to the gNB.
: 7/7a. The gNB activates the AS security with the UE.
: 8/8a. The gNB performs the reconfiguration to setup SRB2 and DRBs for UE, or SRB2 and optionally DRBs for IAB-MT.
: 9. The gNB informs the AMF that the setup procedure is completed.
: NOTE 1:	RRC messages in step 1 and 2 use SRB0, all the subsequent messages use SRB1. Messages in steps 7/7a are integrity protected. From step 8 on, all the messages are integrity protected and ciphered.
: NOTE 2:	For signalling only connection, step 8 is skipped since SRB2 and DRBs are not setup.

The following figure describes the rejection from the network when the UE attempts to setup a connection from RRC_IDLE:

<center>[[File:Rejection of UE triggered transition from RRC IDLE.png|File:Rejection of UE triggered transition from RRC IDLE.png sequence diagram]]</center>

:1. UE attempts to setup a new connection from RRC_IDLE.
:2. The gNB is not able to handle the procedure, for instance due to congestion.
:3. The gNB sends ''RRCReject'' (with a wait time) to keep the UE in RRC_IDLE.