8.7.10 SgNB initiated SgNB Release

36.4233GPPEvolved Universal Terrestrial Radio Access Network (E-UTRAN)Release 17TSX2 Application Protocol (X2AP)

8.7.10.1 General

This procedure is triggered by the en-gNB to initiate the release of the resources for a specific UE.

The procedure uses UE-associated signalling.

8.7.10.2 Successful Operation

Figure 8.7.10.2-1: SgNB initiated SgNB Release, successful operation.

The en-gNB initiates the procedure by sending the SGNB RELEASE REQUIRED message to the MeNB.

Upon reception of the SGNB RELEASE REQUIRED message, the MeNB replies with the SGNB RELEASE CONFIRM message. For each E-RAB configured with the PDCP entity in the en-gNB, the MeNB may include the DL Forwarding GTP Tunnel Endpoint IE and the UL Forwarding GTP Tunnel Endpoint IE within the E-RABs To Be Released Item IE to indicate that it requests data forwarding of uplink and downlink packets to be performed for that bearer.

If the RLC Mode IE is included for an E-RAB within the E-RABs To Be Released List IE (for E-RABs hosted at the en-gNB) in the SGNB RELEASE REQUIRED message, it indicates the mode that the en-gNB used for the E-RAB when it was hosted at the en-gNB.

If the SgNB to MeNB Container IE is included in the SGNB RELEASE REQUIRED message, the MeNB may use the contained information to apply delta configuration.

The en-gNB may start data forwarding and stop providing user data to the UE upon reception of the SGNB RELEASE CONFIRM message.

Upon successful completion of the procedure, the MeNB shall start counting time, so that information regarding time since Secondary Node Release may be transferred towards the MME as specified in TS 36.413 [4].

If the SGNB RELEASE REQUIRED message includes the SCG UE History Information IE, the MeNB shall, if supported, use the information to update UE History Information with PSCell history.

8.7.10.3 Unsuccessful Operation

Not applicable.

8.7.10.4 Abnormal Conditions

Void.