10.4a Roaming and Access Restrictions

36.3003GPPEvolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN)Overall descriptionRelease 17Stage 2TS

The roaming and access restriction information for a UE includes information on restrictions to be applied for subsequent mobility action during ECM-CONNECTED state. It includes the Serving PLMN and may include a list of equivalent PLMNs and other information. It may be provided by the MME at context setup over the S1 interface, and may be updated by the MME during S1 Handover, and when sending NAS Downlink messages.

NOTE: In case of GWCN network sharing scenario, the roaming and access restriction information should always be provided by the MME to the eNBs.

Upon receiving the roaming and access restriction information for a UE, the eNB shall store it and thereafter it should use it to determine whether to apply restriction handling for subsequent mobility action for which the eNB provides information about the target of the mobility action towards the UE, e.g., handover and CCO, if applicable as specified in TS 23.401 [17] and TS 23.272 [23]. If the roaming and access restriction information is not available at the eNB, the eNB shall consider that there is no restriction for subsequent mobility actions.

Only if received via S1 signalling or X2 signalling, the roaming and access restriction information for a UE shall be propagated by the source eNB over X2 at intra E-UTRAN handover. For the case when the X2 handover results in a change of serving PLMN (to an equivalent PLMN), the source eNB shall replace the Serving PLMN with the identity of the target PLMN and move the Serving PLMN to the equivalent PLMN list, before propagating the roaming and access restriction information.

SCG selection for DC at the MeNB is based upon roaming and access restriction information. If the roaming and access restriction information is not available at the MeNB, the MeNB shall consider that there is no restriction for the SCG selection. In case of RAN sharing scenarios, the MeNB selects the serving PLMN ID of the SCG and provides it to the SeNB.

SCG (re)selection for EN-DC at the SgNB is based on roaming and access restriction information in SgNB. If roaming and access restriction information is not available at the SgNB, the SgNB shall consider that there is no restriction for SCG (re)selection. Therefore, MeNB needs to convey the up-to-date roaming and access restriction information from MME to SgNB via X2AP messages.

If eNBs with different versions of the X2AP or S1AP protocol are deployed, information provided by the EPC within the S1AP Handover Restriction List may be lost in the course of X2 mobility. In order to avoid such loss of information at X2 handover or UE context retrieval due to a source eNB or an old eNB not able to recognise the entire content, the source eNB or the old eNB may provide an EPC Handover Restriction List Container to the target eNB or the new eNB, containing the Handover Restriction List as received from the EPC. The target eNB or the new eNB shall use the information contained in the EPC Handover Restriction List Container as the Handover Restriction List, except for the Serving PLMN and the Equivalent PLMNs, which the eNB shall use from the X2AP Handover Restriction List. The EPC Handover Restriction List Container may be propagated at future X2 handover and UE context retrieval.

NOTE: Alternatively, the EPC may provide the S1AP Handover Restriction List to the target eNB or new eNB at path switch, either based on knowledge about the eNB’s implementation status or always.