Editing My Intra-NR Notes (section)

==== 9.2.2.4.1	UE triggered transition from RRC_INACTIVE to RRC_CONNECTED ====

The following figure describes the UE triggered transition from RRC_INACTIVE to RRC_CONNECTED in case of UE context retrieval success:

<center>[[File:UE triggered transition from RRC INACTIVE to RRC CONNECTED (UE context retrieval success).png|UE triggered transition from RRC INACTIVE to RRC CONNECTED (UE context retrieval success)]]</center>

:1. The UE resumes from RRC_INACTIVE, providing the I-RNTI, allocated by the last serving gNB.
:2. The gNB, if able to resolve the gNB identity contained in the I-RNTI, requests the last serving gNB to provide UE Context data.
:3. The last serving gNB provides UE context data.
:4/5. The gNB and UE completes the resumption of the RRC connection.
: NOTE:	User Data can also be sent in step 5 if the grant allows.
: 6. If loss of DL user data buffered in the last serving gNB shall be prevented, the gNB provides forwarding addresses.
: 7/8. The gNB performs path switch.
: 9. The gNB triggers the release of the UE resources at the last serving gNB.

After step 1 above, when the gNB decides to use a single RRC message to reject the Resume Request right away and keep the UE in RRC_INACTIVE without any reconfiguration (e.g. as described in the two examples below), or when the gNB decides to setup a new RRC connection, SRB0 (without security) is used. Conversely, when the gNB decides to reconfigure the UE (e.g. with a new Discontinuous Reception (DRX) cycle or RNA) or when the gNB decides to push the UE to RRC_IDLE, SRB1 (with integrity protection and ciphering as previously configured for that SRB) shall be used.

NOTE:	SRB1 can only be used once the UE Context is retrieved i.e. after step 3.

The following figure describes the UE triggered transition from RRC_INACTIVE to RRC_CONNECTED in case of UE context retrieval failure:

<center>[[File:UE triggered transition from RRC INACTIVE to RRC CONNECTED (UE context retrieval failure).png|UE triggered transition from RRC INACTIVE to RRC CONNECTED (UE context retrieval failure)]]</center>

:1. The UE resumes from RRC_INACTIVE, providing the I-RNTI, allocated by the last serving gNB.
:2. The gNB, if able to resolve the gNB identity contained in the I-RNTI, requests the last serving gNB to provide UE Context data.
:3. The last serving gNB cannot retrieve or verify the UE context data.
:4. The last serving gNB indicates the failure to the gNB.
:5. The gNB performs a fallback to establish a new RRC connection by sending RRCSetup.
:6. A new connection is setup as described in clause 9.2.1.3.

The following figure describes the rejection from the network when the UE attempts to resume a connection from RRC_INACTIVE:

<center>[[File:Reject from the network, UE attempts to resume a connection.png|Reject from the network, UE attempts to resume a connection]]</center>

:1. UE attempts to resume the connection from RRC_INACTIVE.
: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_INACTIVE.