8.3 Context Management procedures

36.4133GPPEvolved Universal Terrestrial Radio Access Network (E-UTRAN)Release 17S1 Application Protocol (S1AP)TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

8.3.1 Initial Context Setup

8.3.1.1 General

The purpose of the Initial Context Setup procedure is to establish the necessary overall initial UE Context including E-RAB context, the Security Key, Handover Restriction List, UE Radio capability and UE Security Capabilities etc. The procedure uses UE-associated signalling.

8.3.1.2 Successful Operation

Figure 8.3.1.2-1: Initial Context Setup procedure. Successful operation.

In case of the establishment of an E-RAB the EPC must be prepared to receive user data before the INITIAL CONTEXT SETUP RESPONSE message has been received by the MME. If no UE-associated logical S1-connection exists, the UE-associated logical S1-connection shall be established at reception of the INITIAL CONTEXT SETUP REQUEST message.

The INITIAL CONTEXT SETUP REQUEST message shall contain within the E-RAB to be Setup List IE the information required by the eNB to build the new E-RAB configuration consisting of at least one additional E-RAB.

The E-RAB to be Setup Item IE may contain:

– the NAS-PDU IE,

– the Correlation ID IE in case of LIPA operation,

– the SIPTO Correlation ID IE in case of SIPTO@LN operation,

– the Bearer Type IE.

– the Security Indication IE

The INITIAL CONTEXT SETUP REQUEST message may contain

– the Trace Activation IE.

– the Handover Restriction List IE, which may contain roaming or access restrictions.

– the UE Radio Capability IE.

– the Subscriber Profile ID for RAT/Frequency priority IE.

– the Additional RRM Policy Index IE.

– the CS Fallback Indicator IE.

– the SRVCC Operation Possible IE.

– the CSG Membership Status IE.

– the Registered LAI IE.

– the GUMMEI IE, which indicates the MME serving the UE, and shall only be present according to subclauses 4.6.2 and 4.7.6.6 of TS 36.300 [14].

– the MME UE S1AP ID 2 IE, which indicates the MME UE S1AP ID assigned by the MME, and shall only be present according to subclause 4.6.2 of TS 36.300 [14].

– the Management Based MDT Allowed IE.

– the Management Based MDT PLMN List IE.

– the Additional CS Fallback Indicator IE.

– the Masked IMEISV IE.

– the Expected UE Behaviour IE.

– the ProSe Authorized IE.

– the UE User Plane CIoT Support Indicator IE.

– the V2X Services Authorized IE.

– the UE Sidelink Aggregate Maximum Bit Rate IE.

– the NR UE Security Capabilities IE.

– the Aerial UE subscription information IE.

– the Pending Data Indication IE.

– the IAB Authorized IE.

– the NR V2X Services Authorized IE.

– the NR UE Sidelink Aggregate Maximum Bit Rate IE.

– the PC5 QoS Parameters IE.

The INITIAL CONTEXT SETUP REQUEST message shall contain the Subscriber Profile ID for RAT/Frequency priority IE, if available in the MME.

If the Correlation ID IE is included in the INITIAL CONTEXT SETUP REQUEST message towards the eNB with L-GW function for LIPA operation, then the eNB shall use this information for LIPA operation for the concerned E-RAB.

If the SIPTO Correlation ID IE is included in the INITIAL CONTEXT SETUP REQUEST message towards the eNB with L-GW function for SIPTO@LN operation, then the eNB shall use this information for SIPTO@LN operation for the concerned E-RAB.

If the Bearer Type IE is included in the INITIAL CONTEXT SETUP REQUEST message and is set to "non IP", then the eNB shall not perform IP header compression for the concerned E-RAB.

If the Ethernet Type IE is included in the INITIAL CONTEXT SETUP REQUEST message and is set to "True", then the eNB shall, if supported, take this into account to perform header compression appropriately for the concerned E-RAB.

If the Security Indication IE is included in the INITIAL CONTEXT SETUP REQUEST message, the eNB shall, if supported, act as defined in the E-RAB Setup procedure for the concerned E-RAB.

If the Masked IMEISV IE is contained in the INITIAL CONTEXT SETUP REQUEST the target eNB shall, if supported, use it to determine the characteristics of the UE for subsequent handling.

If the Expected UE Behaviour IE is included in the INITIAL CONTEXT SETUP REQUEST message, the eNB shall, if supported, store this information and may use it to determine the RRC connection time.

Upon receipt of the INITIAL CONTEXT SETUP REQUEST message, the eNB shall

– attempt to execute the requested E-RAB configuration.

– store the UE Aggregate Maximum Bit Rate in the UE context, and use the received UE Aggregate Maximum Bit Rate for non-GBR Bearers for the concerned UE.

– pass the value contained in the E-RAB ID IE and the NAS-PDU IE received for the E-RAB for each established Data radio bearer to the radio interface protocol. The eNB shall not send the NAS PDUs associated to the failed Data radio bearers to the UE.

– store the received Handover Restriction List in the UE context.

– store the received UE Radio Capability in the UE context.

– store the received Subscriber Profile ID for RAT/Frequency priority in the UE context and use it as defined in TS 36.300 [14].

– if supported, store the received Additional RRM Policy Index IE in the UE context and use it as defined in TS 36.300 [14].

– store the received SRVCC Operation Possible in the UE context and use it as defined in TS 23.216 [9].

– store the received UE Security Capabilities in the UE context.

– store the received Security Key in the UE context, take it into use and associate it with the initial value of NCC as defined in TS 33.401 [15].

– store the received CSG Membership Status, if supported, in the UE context.

– store the received Management Based MDT Allowed information, if supported, in the UE context.

– store the received Management Based MDT PLMN List information, if supported, in the UE context.

– store the received ProSe Authorization information, if supported, in the UE context.

– store the received V2X Services Authorization information, if supported, in the UE context.

– store the received UE Sidelink Aggregate Maximum Bit Rate, if supported, in the UE context, and use it for the concerned UE’s sidelink communication in network scheduled mode for V2X services.

– store the received IAB Authorization Information, if supported, in the UE context.

– store the received NR V2X Services Authorization information, if supported, in the UE context.

– store the received NR UE Sidelink Aggregate Maximum Bit Rate, if supported, in the UE context, and use it for the concerned UE’s sidelink communication in network scheduled mode for NR V2X services.

– store the received PC5 QoS Parameters, if supported, in the UE context, and use it for the concerned UE’s NR sidelink communication as specified in TS 23.285 [49].

For the Initial Context Setup an initial value for the Next Hop Chaining Count is stored in the UE context.

The allocation of resources according to the values of the Allocation and Retention Priority IE shall follow the principles described for the E-RAB Setup procedure.

The eNB shall use the information in the Handover Restriction List IE if present in the INITIAL CONTEXT SETUP REQUEST message to

– determine a target for subsequent mobility action for which the eNB provides information about the target of the mobility action towards the UE, except if the CS Fallback Indicator IE is set to “CS Fallback High Priority” and the Additional CS Fallback Indicator IE is not present in which case the eNB may use the information in the Handover Restriction List IE;

– select a proper SCG during dual connectivity operation.

If the Handover Restriction List IE is not contained in the INITIAL CONTEXT SETUP REQUEST message, the eNB shall consider that no roaming and no access restriction apply to the UE. The eNB shall also consider that no roaming and no access restriction apply to the UE when:

– one of the setup E-RABs has a particular ARP value (TS 23.401 [11]);

– the CS Fallback Indicator IE is set to “CS Fallback High Priority” and the Additional CS Fallback Indicator IE is not present and, in case the Handover Restriction List IE is applied, no suitable target is found, in which case it shall process according to TS 23.272 [17];

– the CS Fallback Indicator IE is set to “CS Fallback High Priority” and the Additional CS Fallback Indicator IE is set to “no restriction”, in which case it shall process according to TS 23.272 [17].

If the Trace Activation IE is included in the INITIAL CONTEXT SETUP REQUEST message then eNB shall, if supported, initiate the requested trace function as described in TS 32.422 [10]. In particular, the eNB shall, if supported:

– if the Trace Activation IE does not include the MDT Configuration IE, initiate the requested trace session as described in TS 32.422 [10];

– if the Trace Activation IE includes the MDT Activation IE, within the MDT Configuration IE, set to “Immediate MDT and Trace”, initiate the requested trace session and MDT session as described in TS 32.422 [10];

– if the Trace Activation IE includes the MDT Activation IE ,within the MDT Configuration IE, set to “Immediate MDT Only”, “Logged MDT only” or “Logged MBSFN MDT”, initiate the requested MDT session as described in TS 32.422 [10] and the eNB shall ignore Interfaces To Trace IE, and Trace Depth IE.

– if the Trace Activation IE includes the MDT Location Information IE, within the MDT Configuration IE, store this information and take it into account in the requested MDT session.

– if the Trace Activation IE includes the Signalling based MDT PLMN List IE, within the MDT Configuration IE, the eNB may use it to propagate the MDT Configuration as described in TS 37.320 [31].

– if the Trace Activation IE includes the MBSFN-ResultToLog IE, within the MDT Configuration IE, take it into account for MDT Configuration as described in TS 37.320 [31].

– if the Trace Activation IE includes the MBSFN-AreaId IE in the MBSFN-ResultToLog IE, within the MDT Configuration IE, take it into account for MDT Configuration as described in TS 37.320 [31].

– if the Trace Activation IE includes the UE Application layer measurement configuration IE, initiate the requested trace session and QoE Measurement Collection function as described in TS 36.300 [14].

– if the Trace Activation IE includes the Bluetooth Measurement Configuration IE, within the MDT Configuration IE, take it into account for MDT Configuration as described in TS 37.320 [31].

– if the Trace Activation IE includes the WLAN Measurement Configuration IE, within the MDT Configuration IE, take it into account for MDT Configuration as described in TS 37.320 [31].

– if the Trace Activation IE includes the MDT Configuration NR IE, store and forward the MDT Configuration NR IE to the SgNB, if the eNB has configured EN-DC for the UE.

– if the Trace Activation IE includes the Sensor Measurement Configuration IE within the MDT Configuration IE, take it into account for MDT Configuration as described in TS 37.320 [31].

If the CS Fallback Indicator IE is included in the INITIAL CONTEXT SETUP REQUEST message, it indicates that the UE Context to be set-up is subject to CS Fallback. The eNB shall reply with the INITIAL CONTEXT SETUP RESPONSE message and then act as defined in TS 23.272 [17].

If the Registered LAI IE is included in the INITIAL CONTEXT SETUP REQUEST message, it indicates that the eNB may take the Registered LAI IE into account when selecting the target cell or frequency and then act as defined in TS 23.272 [17].

If the UE Security Capabilities IE included in the INITIAL CONTEXT SETUP REQUEST message only contains the EIA0 algorithm as defined in TS 33.401 [15] and if this EIA0 algorithm is defined in the configured list of allowed integrity protection algorithms in the eNB (TS 33.401 [15]), the eNB shall take it into use and ignore the keys received in the Security Key IE.

If the GUMMEI IE is contained in the INITIAL CONTEXT SETUP REQUEST message, the eNB shall, if supported, store this information in the UE context and use it for subsequent X2 handovers.

If the MME UE S1AP ID 2 IE is contained in the INITIAL CONTEXT SETUP REQUEST message, the eNB shall, if supported, store this information in the UE context and use it for subsequent X2 handovers.

If the Management Based MDT Allowed IE is contained in the INITIAL CONTEXT SETUP REQUEST message, the eNB shall use it, if supported, together with information in the Management Based MDT PLMN List IE, if available in the UE context, to allow subsequent selection of the UE for management based MDT defined in TS 32.422 [10].

If the UE User Plane CIoT Support Indicator IE is included in the INITIAL CONTEXT SETUP REQUEST message and is set to "supported", the eNB shall, if supported, consider that User Plane CIoT EPS Optimisation as specified in TS 23.401 [11] is supported for the UE.

If the Enhanced Coverage Restricted IE is included in the INITIAL CONTEXT SETUP REQUEST message, the eNB shall store this information in the UE context and use it as defined in TS 23.401 [11].

If the CE-Mode-B Restricted IE is included in the INITIAL CONTEXT SETUP REQUEST message and the Enhanced Coverage Restricted IE is not set to restricted and the Enhanced Coverage Restricted information stored in the UE context is not set to restricted, the eNB shall store this information in the UE context and use it as defined in TS 23.401 [11].

If the NR UE Security Capabilities IE is included in the INITIAL CONTEXT SETUP REQUEST message, the eNB shall, if supported, store this information in the UE context and use it as defined in TS 33.401 [15].

If the Aerial UE subscription information IE is included in the INITIAL CONTEXT SETUP REQUEST message, the eNB shall, if supported, store this information in the UE context and use it as defined in TS 36.300 [14].

If the Pending Data Indication IE is included in the INITIAL CONTEXT SETUP REQUEST message, the eNB shall use it as defined in TS 23.401 [11].

If the Subscription Based UE Differentiation Information IE is included in the INITIAL CONTEXT SETUP REQUEST message, the eNB shall, if supported, store this information in the UE context for further use according to TS 23.401 [11].

If the UE Radio Capability ID IE is included in the INITIAL CONTEXT SETUP REQUEST message, the eNB shall, if supported, use it as defined in TS 23.401 [11].

The eNB shall report to the MME, in the INITIAL CONTEXT SETUP RESPONSE message, the successful establishment of the security procedures with the UE, and, the result for all the requested E-RABs in the following way:

– A list of E-RABs which are successfully established shall be included in the E-RAB Setup List IE

– A list of E-RABs which failed to be established shall be included in the E-RAB Failed to Setup List IE.

When the eNB reports the unsuccessful establishment of an E-RAB, the cause value should be precise enough to enable the MME to know the reason for the unsuccessful establishment, e.g., “Radio resources not available”, “Failure in the Radio Interface Procedure”.

After sending the INITIAL CONTEXT SETUP RESPONSE message, the procedure is terminated in the eNB.

8.3.1.3 Unsuccessful Operation

Figure 8.3.1.3-1: Initial Context Setup procedure. Unsuccessful operation.

If the eNB is not able to establish an S1 UE context, or cannot even establish one non GBR bearer it shall consider the procedure as failed and reply with the INITIAL CONTEXT SETUP FAILURE message.

8.3.1.4 Abnormal Conditions

If the eNB receives an INITIAL CONTEXT SETUP REQUEST message containing a E-RAB Level QoS Parameters IE which contains a QCI IE indicating a GBR bearer (as defined in TS 23.203 [13]), and which does not contain the GBR QoS Information IE, the eNB shall consider the establishment of the corresponding E-RAB as failed.

If the eNB receives an INITIAL CONTEXT SETUP REQUEST message containing several E-RAB ID IEs (in the E-RAB to Be Setup List IE) set to the same value, the eNB shall consider the establishment of the corresponding E-RABs as failed.

If the supported algorithms for encryption defined in the Encryption Algorithms IE in the UE Security Capabilities IE, plus the mandated support of EEA0 in all UEs (TS 33.401 [15]), do not match any allowed algorithms defined in the configured list of allowed encryption algorithms in the eNB (TS 33.401 [15]), the eNB shall reject the procedure using the INITIAL CONTEXT SETUP FAILURE message.

If the supported algorithms for integrity defined in the Integrity Protection Algorithms IE in the UE Security Capabilities IE, plus the mandated support of the EIA0 algorithm in all UEs (TS 33.401 [15]), do not match any allowed algorithms defined in the configured list of allowed integrity protection algorithms in the eNB (TS 33.401 [15]), the eNB shall reject the procedure using the INITIAL CONTEXT SETUP FAILURE message.

If the CSG Membership Status IE is not included in the INITIAL CONTEXT SETUP REQUEST message and the cell accessed by the UE is a hybrid cell, the eNB shall reject the procedure using the INITIAL CONTEXT SETUP FAILURE message.

If the eNB receives an INITIAL CONTEXT SETUP REQUEST message containing both the Correlation ID and the SIPTO Correlation ID IEs for the same E-RAB, the eNB shall consider the establishment of the corresponding E-RAB as failed.

8.3.2 UE Context Release Request (eNB initiated)

8.3.2.1 General

The purpose of the UE Context Release Request procedure is to enable the eNB to request the MME to release the UE-associated logical S1-connection due to E-UTRAN generated reasons, e.g., “TX2_RELOCOverallExpiry”. The procedure uses UE-associated signalling.

8.3.2.2 Successful Operation

Figure 8.3.2.2-1: UE Context Release Request procedure. Successful operation.

The eNB controlling a UE-associated logical S1-connection initiates the procedure by generating a UE CONTEXT RELEASE REQUEST message towards the affected MME node.

The UE CONTEXT RELEASE REQUEST message shall indicate the appropriate cause value, e.g., “User Inactivity”, “Radio Connection With UE Lost”, “CSG Subscription Expiry”, “CS Fallback triggered”, “Redirection towards 1xRTT”, “Inter-RAT Redirection”, “UE Not Available for PS Service”, “Release due to pre-emption”, for the requested UE-associated logical S1-connection release.

If the Secondary RAT Usage Report List IE is included in the UE CONTEXT RELEASE REQUEST message, the MME shall handle this information as specified in TS 23.401 [11].

Interactions with UE Context Release procedure:

The UE Context Release procedure should be initiated upon reception of a UE CONTEXT RELEASE REQUEST message. If the UE was configured with EN-DC radio resources at the time UE Context Release Request procedure was triggered, and the PSCell information was available, the eNB shall store the PSCell information in the UE context.

8.3.3 UE Context Release (MME initiated)

8.3.3.1 General

The purpose of the UE Context Release procedure is to enable the MME to order the release of the UE-associated logical connection due to various reasons, e.g., completion of a transaction between the UE and the EPC, or completion of successful handover, or completion of handover cancellation, or release of the old UE-associated logical S1-connection when two UE-associated logical S1-connections toward the same UE is detected after the UE has initiated the establishment of a new UE-associated logical S1-connection, or the UE is no longer allowed to access the CSG cell (i.e., the UE becomes a non-member of the currently used CSG cell). The procedure uses UE-associated S1 connection.

8.3.3.2 Successful Operation

Figure 8.3.3.2-1: UE Context Release procedure. Successful operation.

The MME initiates the procedure by sending the UE CONTEXT RELEASE COMMAND message to the eNB.

The UE CONTEXT RELEASE COMMAND message shall contain the UE S1AP ID pair IE if available, otherwise the message shall contain the MME UE S1AP ID IE.

The MME provides the cause IE set to “Load Balancing TAU Required” in the UE CONTEXT RELEASE COMMAND message sent to the eNB for all load balancing and offload cases in the MME.

Upon reception of the UE CONTEXT RELEASE COMMAND message, the eNB shall release all related signalling and user data transport resources and reply with the UE CONTEXT RELEASE COMPLETE message. In case of eNB supporting L-GW function for LIPA and/or SIPTO@LN operation, the eNB shall also release any related tunnel resources. In case of successful handover, the eNB using L-GW function for SIPTO@LN operation shall also request using intra-node signalling the collocated L-GW to release the SIPTO@LN PDN connection as defined in TS 23.401 [11].

The eNB shall, if supported, report in the UE CONTEXT RELEASE COMPLETE message location information of the UE in the User Location Information IE. If the PSCell Information IE is included in the User Location Information IE, it indicates the UE was configured with EN-DC radio resources at the eNB . Also, if the Time Since Secondary Node Release IE is included in the UE CONTEXT RELEASE COMPLETE message, it indicates the time elapsed since EN-DC operation in the eNB was stopped for the UE.

If the User Location Information IE is included in the UE CONTEXT RELEASE COMPLETE message, the MME shall handle this information as specified in TS 23.401 [11].

If the Information on Recommended Cells and eNBs for Paging IE is included in the UE CONTEXT RELEASE COMPLETE message, the MME shall, if supported, store it and may use it for subsequent paging.

If the Cell Identifier and Coverage Enhancement Level IE is included in the UE CONTEXT RELEASE COMPLETE message, the MME shall, if supported, store it and use it for subsequent paging.

If the Secondary RAT Usage Report List IE is included in the UE CONTEXT RELEASE COMPLETE message, the MME shall handle this information as specified in TS 23.401 [11].

8.3.3.3 Abnormal Conditions

If the UE Context Release procedure is not initiated towards the eNB before the expiry of the timer TS1_RELOCOverall, the eNB shall request the MME to release the UE context.

If the UE returns to the eNB before the reception of the UE CONTEXT RELEASE COMMAND message or the expiry of the timer TS1_RELOCOverall, the eNB shall stop the TS1_RELOCOverall and continue to serve the UE.

8.3.4 UE Context Modification

8.3.4.1 General

The purpose of the UE Context Modification procedure is to partly modify the established UE Context, e.g., with the Security Key or the Subscriber Profile ID for RAT/Frequency priority. The procedure uses UE-associated signalling.

8.3.4.2 Successful Operation

Figure 8.3.4.2-1: UE Context Modification procedure. Successful operation.

The UE CONTEXT MODIFICATION REQUEST message may contain.

– the Security Key IE.

– the Subscriber Profile ID for RAT/Frequency priority IE.

– the Additional RRM Policy Index IE.

– the UE Aggregate Maximum Bit Rate IE.

– the CS Fallback Indicator IE.

– the UE Security Capabilities IE.

– the CSG Membership Status IE.

– the Registered LAI IE.

– the Additional CS Fallback Indicator IE.

– the ProSe Authorized IE.

– the SRVCC Operation Possible IE.

– the SRVCC Operation Not Possible IE.

– the V2X Services Authorized IE.

– the UE Sidelink Aggregate Maximum Bit Rate IE.

– the NR UE Security Capabilities IE.

– the Aerial UE subscription information IE.

– the IAB Authorized IE.

– the NR V2X Services Authorized IE.

– the NR UE Sidelink Aggregate Maximum Bit Rate IE.

– the PC5 QoS Parameters IE.

– the UE Radio Capability ID IE.

Upon receipt of the UE CONTEXT MODIFICATION REQUEST message, the eNB shall

– store the received Security Key IE, take it into use and associate it with the initial value of NCC as defined in TS 33.401 [15]

– store the UE Security Capabilities IE and take them into use together with the received keys according to TS 33.401 [15].

– if supported, store the NR UE Security Capabilities IE and use it as defined in TS 33.401 [15]

– store the Subscriber Profile ID for RAT/Frequency priority IE and use it as defined in TS 36.300 [14].

– if supported, store the Additional RRM Policy Index IE and use it as defined in TS 36.300 [14].

– store the received IAB Authorized IE, if supported, in the UE context.

If the UE Aggregate Maximum Bit Rate IE is included in the UE CONTEXT MODIFICATION REQUEST message, the eNB shall:

– replace the previously provided UE Aggregate Maximum Bit Rate by the received UE Aggregate Maximum Bit Rate in the UE context;

– use the received UE Aggregate Maximum Bit Rate for non-GBR Bearers for the concerned UE.

If the CSG Membership Status IE is received in the UE CONTEXT MODIFICATION REQUEST message, the eNB shall take the following action:

– If the cell that serves the UE is a hybrid cell, the eNB shall store the value contained in the CSG Membership Status IE and replace any previously stored membership status value by this new one. It shall then use it as defined in TS 36.300 [14].

– If the cell that serves the UE is a CSG cell, and the CSG Membership Status IE is set to “not-member”, the eNB should initiate actions to ensure that the UE is no longer served by the CSG cell as defined in TS 36.300 [14].

– If the UE is in dual connectivity operation and the cell configured as SCG is a hybrid cell, the eNB shall inform the eNB serving the SCG of the updated CSG membership status.

If the UE Aggregate Maximum Bit Rate IE is not contained in the UE CONTEXT MODIFICATION REQUEST message, the eNB shall use the previously provided UE Aggregate Maximum Bit Rate which is stored in the UE context.

If the CS Fallback Indicator IE is included in the UE CONTEXT MODIFICATION REQUEST message, it indicates that the concerned UE Context is subject to CS Fallback. The eNB shall reply with the UE CONTEXT MODIFICATION RESPONSE message and then act as defined in TS 23.272 [17]. If the CS Fallback Indicator IE is set to “CS Fallback High Priority” and the Additional CS Fallback Indicator IE is not present and, in case the Handover Restriction List information that may exist in the UE context is applied, no suitable target is found, or if the CS Fallback Indicator IE is set to “CS Fallback High Priority” and the Additional CS Fallback Indicator IE is set to “no restriction”, the eNB shall consider that no roaming and no access restriction apply to the UE and process according to TS 23.272 [17].

If the Registered LAI IE is included in the UE CONTEXT MODIFICATION REQUEST message, it indicates that the eNB may take the Registered LAI IE into account when selecting the target cell or frequency and then act as defined in TS 23.272 [17].

If the ProSe Authorized IE is contained in the UE CONTEXT MODIFICATION REQUEST message, the eNB shall, if supported, update its ProSe authorization information for the UE accordingly. If the ProSe Authorized IE includes one or more IEs set to “not authorized”, the eNB shall, if supported, initiate actions to ensure that the UE is no longer accessing the relevant ProSe service(s).

If the SRVCC Operation Possible IE is included in UE CONTEXT MODIFICATION REQUEST message, the eNB shall store content of the received SRVCC Operation Possible IE in the UE context and, if supported, use it as defined in TS 23.216 [9].

If the SRVCC Operation Not Possible IE is included in UE CONTEXT MODIFICATION REQUEST message, the eNB shall, if supported, remove the SRVCC Operation Possible information from the UE context.

If the V2X Services Authorized IE is contained in the UE CONTEXT MODIFICATION REQUEST message, the eNB shall, if supported, update its V2X services authorization information for the UE accordingly. If the V2X Services Authorized IE includes one or more IEs set to “not authorized”, the eNB shall, if supported, initiate actions to ensure that the UE is no longer accessing the relevant service(s).

If the UE Sidelink Aggregate Maximum Bit Rate IE is included in the UE CONTEXT MODIFICATION REQUEST message, the eNB shall, if supported:

– replace the previously provided UE Sidelink Aggregate Maximum Bit Rate, if available in the UE context, with the received value;

– use the received value for the concerned UE’s sidelink communication in network scheduled mode for V2X services.

If the Aerial UE subscription information IE is included in the UE CONTEXT MODIFICATION REQUEST message, the eNB shall, if supported, store this information in the UE context and use it as defined in TS 36.300 [14].

If the UE Radio Capability ID IE is included in the UE CONTEXT MODIFICATION REQUEST message, the eNB shall, if supported, use it as defined in TS 23.401 [11].

The eNB shall report, in the UE CONTEXT MODIFICATION RESPONSE message to the MME the successful update of the UE context.

After sending the UE CONTEXT MODIFICATION RESPONSE message, the procedure is terminated in the eNB.

If the NR V2X Services Authorized IE is contained in the UE CONTEXT MODIFICATION REQUEST message, the eNB shall, if supported, update its V2X services authorization information for the UE accordingly. If the NR V2X Services Authorized IE includes one or more IEs set to “not authorized”, the eNB shall, if supported, initiate actions to ensure that the UE is no longer accessing the relevant service(s).

If the NR UE Sidelink Aggregate Maximum Bit Rate IE is included in the UE CONTEXT MODIFICATION REQUEST message, the eNB shall, if supported:

– replace the previously provided NR UE Sidelink Aggregate Maximum Bit Rate, if available in the UE context, with the received value;

– use the received value for the concerned UE’s sidelink communication in network scheduled mode for NR V2X services.

If the PC5 QoS Parameters IE is included in the UE CONTEXT MODIFICATION REQUEST message, the eNB shall, if supported, use it for the concerned UE’s NR sidelink communication as specified in TS 23.285 [49].

8.3.4.3 Unsuccessful Operation

Figure 8.3.4.3-1: UE Context Modification procedure. Unsuccessful operation.

In case the UE context update cannot be performed successfully the eNB shall respond with the UE CONTEXT MODIFICATION FAILURE message to the MME with an appropriate cause value in the Cause IE.

8.3.4.4 Abnormal Conditions

If the eNB receives both the CS Fallback Indicator IE and one of the security IEs (either the Security Key IE or the UE Security Capabilities IE) in the UE Context Modification Request message, the eNB shall ignore both IEs and send back the UE CONTEXT MODIFICATION FAILURE message with an appropriate cause value.

8.3.5 UE Radio Capability Match

8.3.5.1 General

The purpose of the UE Radio Capability Match procedure is for the MME to request the eNB to derive and provide an indication to the MME whether the UE radio capabilities are compatible with the network configuration for voice continuity.

The procedure uses UE-associated signalling.

8.3.5.2 Successful Operation

Figure 8.3.5.2-1: UE Radio Capability Match. Successful operation

The MME initiates the procedure by sending a UE RADIO CAPABILITY MATCH REQUEST message. If the UE-associated logical S1-connection is not established, the MME shall allocate a unique MME UE S1AP ID to be used for the UE and include the MME UE S1AP ID IE in the UE RADIO CAPABILITY MATCH REQUEST message; by receiving the MME UE S1AP ID IE in the UE RADIO CAPABILITY MATCH REQUEST message, the eNB establishes the UE-associated logical S1-connection.

Upon receipt of the UE RADIO CAPABILITY MATCH REQUEST message, the eNB shall act as defined in the TS 23.401 [11] and respond with a UE RADIO CAPABILITY MATCH RESPONSE message.

If the UE Radio Capability IE is contained in the UE RADIO CAPABILITY MATCH REQUEST message, the eNB shall use it to determine the value of the Voice Support Match Indicator IE to be included in the UE RADIO CAPABILITY MATCH RESPONSE message.

If the UE Radio Capability ID IE is included in the UE RADIO CAPABILITY MATCH REQUEST message, the eNB shall, if supported, use it as defined in TS 23.401 [11].

8.3.5.3 Unsuccessful Operation

Not applicable.

8.3.5.4 Abnormal Conditions

Not applicable.

8.3.6 UE Context Modification Indication

8.3.6.1 General

The purpose of the UE Context Modification Indication procedure is for the eNB to request the modifications on the established UE Context.

The procedure uses UE-associated signalling.

In the current version of the specification, this procedure is only used for membership verification, as described in TS 36.300 [14].

8.3.6.2 Successful Operation

Figure 8.3.6.2-1: UE Context Modification Indication. Successful operation

If the CSG Membership Info IE is included in the UE CONTEXT MODIFICATION INDICATION message, the MME shall use the information for CSG membership verification as specified in TS 36.300 [14] and provide the result of the membership verification in the CSG Membership Status IE contained in the UE CONTEXT MODIFICATION CONFIRM message.

If no CSG Membership Info IE is received in the UE CONTEXT MODIFICATION INDICATION message and the UE was previously configured with resources from a hybrid cell, the MME shall consider that the UE has moved into an open access cell.

If PLMN Identity IE is received in the CSG Membership Info IE in the UE CONTEXT MODIFICATION INDICATION message, the MME shall use it for CSG membership verification as specified in TS 36.300 [14].

8.3.6.3 Unsuccessful Operation

Not applicable.

8.3.6.4 Abnormal Conditions

If the CSG Membership Info IE in the UE CONTEXT MODIFICATION message does not contain the Cell Access Mode IE set to "hybrid"the MME shall trigger the UE Context Release procedure.

8.3.7 UE Context Suspend

8.3.7.1 General

The purpose of the UE Context Suspend procedure is to suspend the UE context, the UE-associated logical S1-connection and the related bearer contexts in the E-UTRAN and the EPC.

8.3.7.2 Successful Operation

Figure 8.3.7.2-1: UE Context Suspend procedure. Successful operation.

The eNB initiates the procedure by sending the UE CONTEXT SUSPEND REQUEST message to the MME.

Upon receipt of the UE CONTEXT SUSPEND REQUEST the MME shall act as defined in TS 23.401 [11].

Upon receipt of the UE CONTEXT SUSPEND RESPONSE message, the eNB shall suspend the UE context, the UE-associated logical S1-connection and the related bearer contexts and send the UE to RRC_IDLE.

If the Information on Recommended Cells and eNBs for Paging IE is included in the UE CONTEXT SUSPEND REQUEST message, the MME shall, if supported, store it and may use it for subsequent paging.

If the Cell Identifier and Coverage Enhancement Level IE is included in the UE CONTEXT SUSPEND REQUEST message, the MME shall, if supported, store it and use it for subsequent paging.

If the Secondary RAT Usage Report List IE is included in the UE CONTEXT SUSPEND REQUEST message, the MME shall handle this information as specified in TS 23.401 [11].

If the Security Context IE is included in the UE CONTEXT SUSPEND RESPONSE message, the eNB shall store the received Security Context IE in the UE context and remove any existing unused stored {NH, NCC} as specified in TS 33.401 [15].

The eNB shall, if supported, report in the UE CONTEXT SUSPEND REQUEST message location information of the UE in the User Location Information IE. If the PSCell Information IE is included in the User Location Information IE, it indicates the UE was configured with EN-DC radio resources at the eNB. Also, if the Time Since Secondary Node Release IE is included in the UE CONTEXT SUSPEND REQUEST message, it indicates the time elapsed since EN-DC operation in the eNB was stopped for the UE.

8.3.8 UE Context Resume

8.3.8.1 General

The purpose of the UE Context Resume procedure is to indicate to the MME that the UE has resumed the suspended RRC connection or accesses for early data transmission and to request the MME to resume the UE context, UE-associated logical S1-connection and the related bearer contexts in the EPC.

8.3.8.2 Successful Operation

Figure 8.3.8.2-1: UE Context Resume procedure. Successful operation.

The eNB initiates the procedure by sending the UE CONTEXT RESUME REQUEST message to the MME. If the eNB is not able to admit all suspended E-RABs the eNB shall indicate this in the E-RABs Failed To Resume List IE.

Upon receipt of the UE CONTEXT RESUME REQUEST message the MME shall act as defined in TS 23.401 [11] and respond with the UE CONTEXT RESUME RESPONSE. If the MME is not able to admit all suspended E-RABs the MME shall indicate this in the E-RABs Failed To Resume List IE.

The eNB shall release resources for each E-RAB failed to resume and shall assume that the EPC has released respective resources as well.

If the Security Context IE is included in the UE CONTEXT RESUME RESPONSE message, the eNB shall store the received Security Context IE in the UE context and the eNB shall use it for the next suspend/resume or X2 handover or Intra eNB handovers as specified in TS 33.401 [15].

If the Pending Data Indication IE is included in the UE CONTEXT RESUME RESPONSE message, the eNB shall use it as defined in TS 23.401 [11].

If the UE Context Resume procedure was initiated as a result of an EDT session as described in TS 36.300 [14] and the Pending Data Indication IE is received in the UE CONTEXT RESUME RESPONSE message, the eNB shall, if supported, use it to decide whether to proceed to set up an RRC connection for the UE.

8.3.8.3 Unsuccessful Operation

Figure 8.3.8.3-1: UE Context Resume procedure. Unsuccessful operation.

If the MME is not able to resume a single E-RAB it releases the UE-associated logical S1-connection by sending the UE CONTEXT RESUME FAILURE message to the eNB. Upon reception of the UE CONTEXT RESUME FAILURE message, the eNB shall release the RRC connection as specified in TS 36.331 [16] and release all related signalling and user data transport resources.

8.3.9 Connection Establishment Indication

8.3.9.1 General

The purpose of the Connection Establishment Indication procedure is to enable the MME to complete the establishment of the UE-associated logical S1-connection, and/or trigger the eNB to obtain and report UE Radio Capability. The procedure uses UE-associated signalling.

8.3.9.2 Successful Operation

Figure 8.3.9.2-1: Connection Establishment Indication procedure. Successful operation.

The MME initiates the procedure by sending a CONNECTION ESTABLISHMENT INDICATION message to the eNB.

If the UE-associated logical S1-connection is not established, the MME shall allocate a unique MME UE S1AP ID to be used for the UE and include that in the CONNECTION ESTABLISHMENT INDICATION message.

If the UE Radio Capability IE is included in the CONNECTION ESTABLISHMENT INDICATION message, the eNB shall store this information in the UE context, use it as defined in TS 36.300 [14].

If the Enhanced Coverage Restricted IE is included in the CONNECTION ESTABLISHMENT INDICATION message, the eNB shall store this information in the UE context and use it as defined in TS 23.401 [11].

If the DL CP Security Information IE is included in the CONNECTION ESTABLISHMENT INDICATION message, the eNB shall forward this information to the UE as described in TS 36.300 [14].

If the CE-Mode-B Restricted IE is included in the CONNECTION ESTABLISHMENT INDICATION message and the Enhanced Coverage Restricted IE is not set to restricted and the Enhanced Coverage Restricted information stored in the UE context is not set to restricted, the eNB shall store this information in the UE context and use it as defined in TS 23.401 [11].

If the End Indication IE is included in the CONNECTION ESTABLISHMENT INDICATION message and set to "no further data", the eNB shall consider that there are no further NAS PDUs to be transmitted for this UE.

If the Subscription Based UE Differentiation Information IE is included in the CONNECTION ESTABLISHMENT INDICATION message, the eNB shall, if supported, store this information in the UE context for further use according to TS 23.401 [11].

If the UE Level QoS Parameters IE is contained in the CONNECTION ESTABLISHMENT INDICATION message, the eNB shall, if supported, store this information in the UE context, and use it as specified in TS 23.401 [11].

If the UE Radio Capability ID IE is contained in the CONNECTION ESTABLISHMENT INDICATION message, the eNB shall, if supported, use it as defined in TS 23.401 [11].

If the Masked IMEISV IE is contained in the CONNECTION ESTABLISHMENT INDICATION message, the eNB shall, if supported, use it to determine the characteristics of the UE for subsequent handling.

8.3.9.3 Unsuccessful Operation

Not applicable.

8.3.9.4 Abnormal Conditions

Not applicable.

8.3.10 Retrieve UE Information

8.3.10.1 General

The purpose of the Retrieve UE information procedure is for the eNB to request the UE information including QoS Parameters and UE Radio capability from MME, for a NB-IoT UE using Control Plane CIoT EPS Optimisation.

8.3.10.2 Successful Operation

Figure 8.3.10.1: Retrieve UE Information Procedure. Successful operation.

The eNB initiates the procedure by sending the RETRIEVE UE INFORMATION message to the MME.

8.3.10.3 Unsuccessful Operation

Not applicable.

8.3.10.4 Abnormal Conditions

Not applicable.

8.3.11 UE Information Transfer

8.3.11.1 General

The purpose of the UE information transfer procedure is for the MME to send the UE information including QoS Parameters and UE Radio capability to the eNB, for a NB-IoT UE using Control Plane CIoT EPS Optimisation.

8.3.11.2 Successful Operation

Figure 8.3.11.1: UE Information Transfer Procedure. Successful operation.

The MME initiates the procedure by sending the UE INFORMATION TRANSFER message to the eNB.

If the UE Level QoS Parameters IE is contained in the UE INFORMATION TRANSFER message, the eNB shall store this information in the UE context, and use it as specified in TS 23.401 [11].

If the UE Radio Capability IE is contained in the UE INFORMATION TRANSFER message, the eNB shall store this information in the UE context, and use it as specified in TS 23.401 [11].

If the Subscription Based UE Differentiation Information IE is included in the UE INFORMATION TRANSFER message, the eNB shall, if supported, store this information in the UE context for further use according to TS 23.401 [11].

If the Pending Data Indication IE is contained in the UE INFORMATION TRANSFER message, the eNB shall store this information in the UE context, and use it as specified in TS 23.401 [11].

If the Masked IMEISV IE is contained in the UE INFORMATION TRANSFER message, the eNB shall, if supported, use it to determine the characteristics of the UE for subsequent handling.

8.3.11.3 Unsuccessful Operation

Not applicable.

8.3.11.4 Abnormal Conditions

Not applicable.

8.3.12 eNB CP Relocation Indication

8.3.12.1 General

The purpose of the eNB CP Relocation Indication procedure is to request the MME to authenticate the UE’s re-establishment request as described in TS 36.300 [14], and trigger the establishment of the respective UE-associated logical S1-connection, for a NB-IoT UE using Control Plane CIoT EPS Optimisation.

The procedure uses UE-associated signalling.

8.3.12.2 Successful Operation

Figure 8.3.12.2-1: eNB CP Relocation Indication. Successful operation.

The eNB initiates the procedure by sending a eNB CP RELOCATION INDICATION message to the MME.

The eNB shall allocate a unique eNB UE S1AP ID to be used for the UE and the eNB shall include this identity in the eNB CP RELOCATION INDICATION message.

8.3.12.3 Unsuccessful Operation

Not applicable.

8.3.12.4 Abnormal Conditions

Not applicable.

8.3.13 MME CP Relocation Indication

8.3.13.1 General

The purpose of the MME CP Relocation Indication procedure is to inform the eNB that the UE’s connection is to be relocated to another eNB as described in TS 36.300 [14], for a UE using Control Plane CIoT EPS Optimisation.

The procedure uses UE-associated signalling.

8.3.13.2 Successful Operation

Figure 8.3.13.2-1: MME CP Relocation Indication. Successful operation.

The MME initiates the procedure by sending a MME CP RELOCATION INDICATION message to the eNB.

Upon reception of the MME CP RELOCATION INDICATION message, the eNB shall terminate the delivery of NAS messages that have been received from the MME, and proceed as described in TS 36.300 [14].

8.3.13.3 Unsuccessful Operation

Not applicable.

8.3.13.4 Abnormal Conditions

Not applicable.