SER VICE ENHANCEMENTS ON MCX

BACKGROUND

[0001] Generally, all terms used herein are to be interpreted according to their ordinary meaning in the relevant technical field, unless a different meaning is clearly given and/or is implied from the context in which it is used. All references to a/an/the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any methods disclosed herein do not have to be performed in the exact order disclosed, unless a step is explicitly described as following or preceding another step and/or where it is implicit that a step must follow or precede another step. Any feature of any of the embodiments disclosed herein may be applied to any other embodiment, wherever appropriate. Likewise, any advantage of any of the embodiments may apply to any other embodiments, and vice versa. Other objectives, features, and advantages of the enclosed embodiments will be apparent from the following description. [0002] Several operators are using Mission Critical Service (MCX) on Evolved Packet System (EPS) and are planning to support MCX on devices that are capable to use Fifth Generation System (5GS), and hence, may camp on 5GS.

[0003] Mission Critical Push to talk (MCPTT) and other Mission Critical (MC) services have been specified for both EPS and 5GS. MCPTT has been specified for both EPS and for 5GS in Third Generation Partnership Project (3GPP) Technical Specification (TS) 23.379. MCPTT uses a special Data Network Name (DNN) for Protocol Data Unit (PDU) Sessions I Packet Data Network (PDN) connections. Access and Mobility Management Function (AMF) indicates MCX priority to the User Equipment (UE), based on subscription information. MCPTT uses specific 5G Quality -of-Service Identifiers (5Qls) I CoS Class Identifier (QCI) (69 and 65) for default and for dedicated CoS flow I EPS bearer in MC PDU session I PDN connection.

[0004] 5QI/QCI 69 is requested when the application is launched. This may or may not be the default CoS flow/bearer. 69 could be a dedicated bearer/flow. For a Mission Critical DDN, a default bearer/flow with a lower priority than 5QI 69,65,5,1 and 5QI 69 as dedicated signaling bearer and 5QI 65 as dedicated bearer for MCPTT voice could be established. Hence, 5QI 69 is "semi-permanent” for signaling (compare 5QI 5 for Voice over New Radio (VoNR)) and 5QI 65 "during calls” for media (compare 5Q1 1 for VoNR). In such case, 5QI/QCI 69 will be established when the MC client is activated by the user while the PDU/PDN for MC is established at power on and with a lower priority default CoS flow. [0005] The MCPTT client in the UE initiates a Session Initiation Protocol (SIP) registration to the MCPTT service. The MCPTT layer cannot control the UE behavior if rejected on network layer. The MCPTT client in the UE will retry SIP registration if that has failed. [0006] The MCPPT may trigger for establishing PDU/PDN. This is implementation specific, e.g., the MCPTT client aims to send something. 5QI for default and dedicated QoS flows/bearers is decided by dynamic policy control.

[0007] 3GPP TS 23.501, clause 5.16.6 "Mission Critical Services,” is reproduced below:

***** g| _ar t _c | _ause 5 16.6 "Mission Critical Services” *****

According to TS 22.280 [37], a Mission Critical Service (MCX Service) is a communication service reflecting enabling capabilities Mission Critical Applications and provided to end users from Mission Critical Organizations and mission critical applications for other businesses and organizations (e.g. utilities, railways). An MCX Service is either Mission Critical Push To Talk (MCPTT) as defined in TS 23.379 [38], Mission Critical Video (MCVideo) as defined in

TS 23.281 [39], or Mission Critical Data (MCData) as defined in TS 23.282 [40] and represents a shared underlying set of requirements between two or more MCX Service types. MCX Services are not restricted only to the ones defined in this clause and such services can also have priority treatment, if defined via operator's policy and/or local regulation.

MCX Services are based on the ability to invoke, modify, maintain and release sessions with priority, and deliver the priority media packets under network congestion conditions. As specified in clause 6.8 of TS 22.261 [2], MCX Users require 5GS functionality that allows for real-time, dynamic, secure and limited interaction with the QoS and policy framework for modification of the QoS and policy framework by authorized users. The limited interaction is based on operator policy, and provides specific limitations on what aspects of the QoS and policy framework an authorized MCX User can modify. MCX Services are supported in a roaming environment when roaming agreements are in place and where regulatory requirements apply.

An MCX-subscribed UE obtains priority access to the Radio Access Network by using the Unified Access Control mechanism according to TS 22.261 [2], This mechanism provides preferential access to UEs based on its assigned Access Identity. If an MCX-subscribed UE belongs to the special Access Identity as defined in TS 22.261 [2], the UE has preferential access to the network compared to ordinary UEs in periods of congestion. MCX subscription allows users to receive priority services, if the network supports MCX. MCX subscription entitles a USIM with special Access Identity. MCX Services leverage the foundation of the 5G QoS Model as defined in clause 5.7, and 5G Policy Control as defined in clause 5.14. It requires that the necessary subscriptions are in place for both the 5G QoS Profile and the necessary Policies. In addition, MCX Services leverage priority mechanism as defined in clause 5.22.

The terminating network identifies the priority of the MCX Service session and applies priority treatment, including paging with priority, to ensure that the MCX Service session can be established with priority to the terminating user (either an MCX User or normal user).

Priority treatment for MCX Service includes priority message handling, including priority treatment during authentication, security, and Mobility Management procedures.

Priority treatment for MCX Service sessions require appropriate ARP and 5QI (plus 5G QoS characteristics) setting for QoS Flows according to the operator's policy.

NOTE: Use of QoS Flows for MCX Service sessions with non-standardized 5QI values enables the flexible assignment of 5G QoS characteristics (e.g. Priority Level). When a MCX Service session is requested by an MCX User, the following principles apply in the network:

- QoS Flows employed in a MCX Service session shall be assigned ARP value settings appropriate for the priority of the MCX User.

- Setting ARP pre-emption capability and vulnerability of QoS Flows related to a MCX Service session, subject to operator policies and depending on national/regional regulatory requirements.

- Pre-emption of non-MCX Users over MCX Users during network congestion situations, subject to operator policy and national/regional regulations.

Priority treatment is applicable to IMS based multimedia services and priority PDU connectivity services.

***** End of clause 5.16.6 "Mission Critical Services" *****

Figure 1

[0008] Figure 1 illustrates the registration in 5GS of a MCX capable device. The RRC ‘establishment cause' (in Figure 1) is described in, for example, 3GPP TS 38.331, version 17.0.0 (2022-04-19). 3GPP TS 38.331 discloses that the ‘Establishmentcause' " [provides the establishment cause for the RRCSetupRequest in accordance with the information received from upper layers. gNB is not expected to reject an RRCSetupRequest due to unknown cause value being used by the UE.” 3GPP TS 28.331 also discloses that the ‘Establishmentcause' includes "emergency, highPriorityAccess, mt- Access, mo-Signalling, mo-Data, mo-VoiceCall, mo-VideoCall, mo-SMS, mps-PriorityAccess, mcs-PriorityAccess, spare6, spare5, spare4, spare3, spare2, sparel

SUMMARY

[0009] There currently exist certain chai lenge(s) . An MCX capable device may camp on 5GS, but the operator of the device may not want to use MCPTT on 5GS but rather that the device is moved to EPS when using MCPTT. This procedure is not covered in 3GPP today and thus there is no identification of the handover is triggered by a Radio Access Network (RAN) and identified by other Network Functions (NFs)Zproducts for appropriate handling.

[0010] Certain aspects of the present disclosure and their embodiments may provide solutions to the aforementioned or other challenges.

[0011] It is possible for 5G RAN to identify an MCPTT service by identifying the unique QoS flows established for an MCPTT service. 3GPP specifies two unique 5QI values used for MCPTT, these are, 5QI=65 and 5QI=69 and for MC Video it is 5QI =67 and 5QI=69. If 5G RAN identifies an attempt to set up an MCPTT service or an MC Video service, 5G RAN may perform a UE fallback by initiating handover to 4G RAN.

[0012] During a PCF initiated modification, PCF includes MCX support or not support on 5GC to SMF. SMF then creates a merge value of 5GC MCX support based on PCF and SMF capability. The 5GC MCX support indicator is sent to RAN. [0013] During SMF initiated QoS modification, SMF indicates the UE NAS result per each QoS flow to RAN (together with some additional information) for RAN to decide on when to initiate MCX fallback.

[0014] SMF creates MCX 5GC Support Indicator based on SMF and PCF capabilities and sends the information to RAN in NG-AP PDU SESSION RESOURCE MODIFY REQUEST message.

[0015] SMF indicates information from the NAS response of PDU Session Modification Command to RAN including the modification result per each 5QI (using UE NAS 5QI Status Indicator) in NG-AP PDU SESSION RESOURCE MODIFY REQUEST message.

[0016] Certain embodiments may provide one or more of the following technical advantage(s). The present disclosure enables RAN to make a proper decision if MCX service can be kept in 5GC or should be handed over to 4G by moving the UE from 5GS to EPS and also if to be handed over to 4G when to start to trigger the handover. The present disclosure enables to reduce the total MCX service setup time for group call or MC Video call when moving the UE from 5GS to EPS just before a group call with 5QI =65 (or 5QI =67) flow takes place; hence MCPTT group affiliation is completed and other pre-conditions to group call or MC Video call i.e. 5G preparation are completed on 5GS. RAN can use the UE NAS indication provided by SMF e.g.to immediately trigger the handover or proceed the MCX service in 5GS.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 illustrates the registration in 5GS of a MCX capable device.

Fig. 2 is an example of a communications system 200 in which the present disclosure may be implemented.

Fig. 3 is a 5G network architecture using point-to-point interfaces.

Fig. 4 is a 5G network architecture using service-based interfaces.

Fig.s 5A-5B illustrate message sequence chart according to one or more embodiments of the present disclosure.

Fig.s 6A-6B illustrate adapted message sequence chart from TS 23.502 V17.5.0 (2022-06) section 4.2.3.2.

Fig.s 7A-7B correspond to TS 23.502 Figure 4.2.2.2.2-1 of section 4.2.2.2.2 General Registration.

Fig. 8 corresponds to TS 23.502 Figure 4.9.1.3.2-1 of section 4.9.1.3.2 Preparation Phase.

Fig. 9 corresponds to TS 23.502 Figure 4.9.1.3.3-1 of section 4.9.1.3.3 Execution Phase.

Fig. 10 is a block diagram of a network node 1000 according to some embodiments of the present disclosure.

Fig. 11 is a block diagram of a virtualized embodiment of the network node 1000 according to some embodiments of the present disclosure.

Fig. 12 is a block diagram of the network node 1000 according to some embodiments of the present disclosure.

Fig. 13 is a block diagram of a wireless communication device 1300 according to some embodiments of the present disclosure.

Fig. 14 is a block diagram of the wireless communication device 1300 according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0017] Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Other embodiments, however, are contained within the scope of the subject matter disclosed herein, the disclosed subject matter should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art. [0018] Radio Node: As used herein, a "radio node” is either a radio access node or a wireless communication device.

[0019] Radio Access Node: As used herein, a "radio access node” or "radio network node” or "radio access network node” is any node in a Radio Access Network (RAN) of a cellular communications network that operates to wirelessly transmit and/or receive signals. Some examples of a radio access node include, but are not limited to, a base station (e.g., a New Radio (NR) base station (gNB) in a Third Generation Partnership Project (3GPP) Fifth Generation (5G) NR network or an enhanced or evolved Node B (eNB) in a 3GPP Long Term Evolution (LTE) network), a high-power or macro base station, a low-power base station (e.g., a micro base station, a pico base station, a home eNB, or the like), a relay node, a network node that implements part of the functionality of a base station (e.g., a network node that implements a gNB Central Unit (gNB-CU) or a network node that implements a gNB Distributed Unit (gNB-DU)), or a network node that implements part of the functionality of some other type of radio access node.

[0020] Core Network Node: As used herein, a "core network node” is any type of node in a core network or any node that implements a core network function. Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a Packet Data Network Gateway (P-GW), a Service Capability Exposure Function (SCEF), a Home Subscriber Server (HSS), or the like. Some other examples of a core network node include a node implementing an Access and Mobility Management Function (AMF), a User Plane Function (UPF), a Session Management Function (SMF), an Authentication Server Function (AUSF), a Network Slice Selection Function (NSSF), a Network Exposure Function (NEF), a Network Function (NF) Repository Function (NRF), a Policy Control Function (PCF), a Unified Data Management (UDM), or the like.

[0021] Communication Device: As used herein, a "communication device” is any type of device that has access to an access network. Some examples of a communication device include, but are not limited to: mobile phone, smart phone, sensor device, meter, vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, a television, radio, lighting arrangement, tablet computer, laptop, or Personal Computer (PC). The communication device may be a portable, hand-held, computer-comprised, or vehiclemounted mobile device, enabled to communicate voice and/or data via a wireless or wireline connection.

[0022] Wireless Communication Device: One type of communication device is a wireless communication device, which may be any type of wireless device that has access to (i.e., is served by) a wireless network (e.g., a cellular network). Some examples of a wireless communication device include, but are not limited to: a User Equipment device (UE) in a 3GPP network, a Machine Type Communication (MTC) device, and an Internet of Things (loT) device. Such wireless communication devices may be, or may be integrated into, a mobile phone, smart phone, sensor device, meter, vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, a television, radio, lighting arrangement, tablet computer, laptop, or PC. The wireless communication device may be a portable, hand-held, computer-comprised, or vehicle-mounted mobile device, enabled to communicate voice and/or data via a wireless connection.

[0023] Network Node: As used herein, a "network node” is any node that is either part of the RAN or the core network of a cellular communications network/system.

[0024] Transmission/Reception Point (TRP): In some embodiments, a TRP may be either a network node, a radio head, a spatial relation, or a Transmission Configuration Indicator (TCI) state. A TRP may be represented by a spatial relation or a TCI state in some embodiments. In some embodiments, a TRP may be using multiple TCI states. In some embodiments, a TRP may a part of the gNB transmitting and receiving radio signals to/from UE according to physical layer properties and parameters inherent to that element. In some embodiments, in Multiple TRP (multi-TRP) operation, a serving cell can schedule UE from two TRPs, providing better Physical Downlink Shared Channel (PDSCH) coverage, reliability and/or data rates. There are two different operation modes for multi-TRP: single Downlink Control Information (DCI) and multi-DCI. For both modes, control of uplink and downlink operation is done by both physical layer and Medium Access Control (MAC). In single-DCI mode, UE is scheduled by the same DCI for both TRPs and in multi- DCI mode, UE is scheduled by independent DCIs from each TRP.

[0025] In some embodiments, a set Transmission Points (TPs) is a set of geographically co-located transmit antennas (e.g., an antenna array (with one or more antenna elements)) for one cell, part of one cell or one Positioning Reference Signal (PRS) -only TP. TPs can include base station (eNB) antennas, Remote Radio Heads (RRHs), a remote antenna of a base station, an antenna of a PRS-only TP, etc. One cell can be formed by one or multiple TPs. For a homogeneous deployment, each TP may correspond to one cell.

[0026] In some embodiments, a set of TRPs is a set of geographically co-located antennas (e.g., an antenna array (with one or more antenna elements)) supporting TP and/or Reception Point (RP) functionality.

[0027] Note that the description given herein focuses on a 3GPP cellular communications system and, as such, 3GPP terminology or terminology similar to 3GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3GPP system.

[0028] Note that, in the description herein, reference may be made to the term "cell;” however, particularly with respect to 5G NR concepts, beams may be used instead of cells and, as such, it is important to note that the concepts described herein are equally applicable to both cells and beams.

Figure 2

[0029] Figure 2 illustrates one example of a cellular communications system 200 in which embodiments of the present disclosure may be implemented. In the embodiments described herein, the cellular communications system 200 is either a 5G system (5GS) including a Next Generation RAN (NG-RAN) and a 5G Core (5GC) or an Evolved Packet System (EPS) including an Evolved Universal Terrestrial RAN (E-UTRAN) and a Evolved Packet Core (EPC). In this example, the RAN includes base stations 202-1 and 202-2, which in the 5GS include NR base stations (gNBs) and optionally next generation eNBs (ng-eNBs) (e.g., LTE RAN nodes connected to the 5GC) and in the EPS include eNBs, controlling corresponding (macro) cells 204-1 and 204-2. The base stations 202-1 and 202-2 are generally referred to herein collectively as base stations 202 and individually as base station 202. Likewise, the (macro) cells 204-1 and 204-2 are generally referred to herein collectively as (macro) cells 204 and individually as (macro) cell 204. The RAN may also include a number of low power nodes 206-1 through 206-4 controlling corresponding small cells 208-1 through 208-4. The low power nodes 206-1 through 206-4 can be small base stations (such as pico or femto base stations) or RRHs, or the like. Notably, while not illustrated, one or more of the small cells 208-1 through 208-4 may alternatively be provided by the base stations 202. The low power nodes 206-1 through 206-4 are generally referred to herein collectively as low power nodes 206 and individually as low power node 206. Likewise, the small cells 208-1 through 208-4 are generally referred to herein collectively as small cells 208 and individually as small cell 208. The cellular communications system 200 also includes a core network 210, which in the 5G System (5GS) is referred to as the 5GC. The base stations 202 (and optionally the low power nodes 206) are connected to the core network 210.

[0030] The base stations 202 and the low power nodes 206 provide service to wireless communication devices 212-1 through 212-5 in the corresponding cells 204 and 208. The wireless communication devices 212-1 through 212-5 are generally referred to herein collectively as wireless communication devices 212 and individually as wireless communication device 212. In the following description, the wireless communication devices 212 are oftentimes UEs, but the present disclosure is not limited thereto.

Figure 3

[0031] Figure 3 illustrates a wireless communication system represented as a 5G network architecture composed of core Network Functions (NFs), where interaction between any two NFs is represented by a point-to-point reference poi nt/i nterface. Figure 3 can be viewed as one particular implementation of the system 200 of Figure 2.

[0032] Seen from the access side the 5G network architecture shown in Figure 3 comprises a plurality of UEs 212 connected to either a RAN 202 or an Access Network (AN) as well as an AMF 300. Typically, the R(AN) 202 comprises base stations, e.g. such as eNBs or gNBs or similar. Seen from the core network side, the 5GC NFs shown in Figure 3 include a NSSF 302, an AUSF 304, a UDM 306, the AMF 300, a SMF 308, a PCF 310, and an Application Function (AF) 312.

[0033] Reference point representations of the 5G network architecture are used to develop detailed call flows in the normative standardization. The N1 reference point is defined to carry signaling between the UE 212 and AMF 300. The reference points for connecting between the AN 202 and AMF 300 and between the AN 202 and UPF 314 are defined as N2 and N3, respectively. There is a reference point, N11, between the AMF 300 and SMF 308, which implies that the SMF 308 is at least partly controlled by the AMF 300. N4 is used by the SMF 308 and UPF 314 so that the UPF 314 can be set using the control signal generated by the SMF 308, and the UPF 314 can report its state to the SMF 308. N9 is the reference point for the connection between different UPFs 314, and N14 is the reference point connecting between different AMFs 300, respectively. N15 and N7 are defined since the PCF 310 applies policy to the AMF 300 and SMF 308, respectively. N12 is required for the AMF 300 to perform authentication of the UE 212. N8 and N10 are defined because the subscription data of the UE 212 is required for the AMF 300 and SMF 308.

[0034] The 5GC network aims at separating UP and CP. The UP carries user traffic while the CP carries signaling in the network. In Figure 3, the UPF 314 is in the UP and all other NFs, i.e., the AMF 300, SMF 308, PCF 310, AF 312, NSSF 302, AUSF 304, and UDM 306, are in the CP. Separating the UP and CP guarantees each plane resource to be scaled independently. It also allows UPFs to be deployed separately from CP functions in a distributed fashion. In this architecture, UPFs may be deployed very close to UEs to shorten the Round Trip Time (RTT) between UEs and data network for some applications requiring low latency.

[0035] The core 5G network architecture is composed of modularized functions. For example, the AMF 300 and SMF 308 are independent functions in the CP. Separated AMF 300 and SMF 308 allow independent evolution and scaling. Other CP functions like the PCF 310 and AUSF 304 can be separated as shown in Figure 3. Modularized function design enables the 5GC network to support various services flexibly.

[0036] Each NF interacts with another NF directly. It is possible to use intermediate functions to route messages from one NF to another NF. In the CP, a set of interactions between two NFs is defined as service so that its reuse is possible. This service enables support for modularity. The UP supports interactions such as forwarding operations between different UPFs.

Figure 4

[0037] Figure 4 illustrates a 5G network architecture using service-based interfaces between the NFs in the CP, instead of the point-to-point reference points/i nterfaces used in the 5G network architecture of Figure 3. However, the NFs described above with reference to Figure 3 correspond to the NFs shown in Figure 4. The service(s) etc. that a NF provides to other authorized NFs can be exposed to the authorized NFs through the service-based interface. In Figure 4 the service based interfaces are indicated by the letter “N” followed by the name of the NF, e.g. Namf for the service based interface of the AMF 300 and Nsmf for the service based interface of the SMF 308, etc. The NEF 400 and the NRF 402 in Figure 4 are not shown in Figure 3 discussed above. However, it should be clarified that all NFs depicted in Figure 3 can interact with the NEF 400 and the NRF 402 of Figure 4 as necessary, though not explicitly indicated in Figure 3.

[0038] Some properties of the NFs shown in Figures 3 and 4 may be described in the following manner. The AMF 300 provides UE-based authentication, authorization, mobility management, etc. A UE 212 even using multiple access technologies is basically connected to a single AMF 300 because the AMF 300 is independent of the access technologies. The SMF 308 is responsible for session management and allocates Internet Protocol (IP) addresses to UEs. It also selects and controls the UPF 314 for data transfer. If a UE 212 has multiple sessions, different SMFs 308 may be allocated to each session to manage them individually and possibly provide different functionalities per session. The AF 312 provides information on the packet flow to the PCF 310 responsible for policy control in order to support QoS. Based on the information, the PCF 310 determines policies about mobility and session management to make the AMF 300 and SMF 308 operate properly. The AUSF 304 supports authentication function for UEs or similar and thus stores data for authentication of UEs or similar while the UDM 306 stores subscription data of the UE 212. The Data Network (DN), not part of the 5GC network, provides Internet access or operator services and similar.

[0039] An NF may be implemented either as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, or as a virtualized function instantiated on an appropriate platform, e.g., a cloud infrastructure.

Figures 5A-5B

[0040] Figures 5A and 5B illustrate a message sequence chart between the UE 212, RAN 202, AMF 300, SMF 308, UPF 314, UDM 306, and PCF 310 according to one or more embodiments of the present disclosure. The message sequence chart generally discloses a possible method of operation of a wireless network for deploying service enhancements for Mission Critical Services (MCX). In an embodiment, FIGs 5A and 5B correspond to Figure 4.3.3.2-1 From Section 4.3.3.2 UE or network requested PDU Session Modification (non-roaming and roaming with local breakout) of 3GPP TS 23.502 v17.5.0 (2022-06). The following description provides new steps added to the message sequence chart in the present disclosure related to service enhancements for MCX.

[0041] PLEASE NOTE: The 23.502 procedures below are examples of procedures where the proposed mechanisms are visualized. These are examples for steps impacted but could be for other steps and new parameters can be included into other carrying messages e.g. "Namf messages”. Also, it is examples of procedures impacted. For each of the 23.502 procedures it is also stated if the same mechanism also is applicable for other 3GPP procedures.

[0042] NOTE: The UE or network requested PDU Session Modification procedure is an example for PDU session procedure that the proposed mechanism can used but is not limited to that. For instance, also PDU Session Establishment procedure is also applicable.

[0043] The message sequence can start at 502 where the UE 212 initiates the PDU Session Modification procedure by the transmission of an NAS message (N1 SM container (PDU Session Modification Request (PDU session ID, Packet Filters, Operation, Requested QoS, Segregation, 5GSM Core Network Capability, Number Of Packet Filters, [Always-on PDU Session Requested])), PDU Session ID, UE Integrity Protection Maximum Data Rate, [Port Management Information Container]) message. Depending on the Access Type, if the UE was in CM-IDLE state, this SM-NAS message is preceded by the Service Request procedure. The NAS message is forwarded by the (R)AN to the AMF with an indication of User location Information. The AMF 300 invokes Nsmf_PDUSession_UpdateSMContext (SM Context ID, N1 SM container (PDU Session Modification Request)).

[0044] When the UE 212 requests specific QoS handling for selected SDF(s), the PDU Session Modification Request includes Packet Filters describing the SDF(s), the requested Packet Filter Operation (add, modify, delete) on the indicated Packet Filters, the Requested QoS and optionally a Segregation indication. The Segregation indication is included when the UE recommends to the network to bind the applicable SDF(s) on a distinct and dedicated QoS Flow e.g. even if an existing QoS Flow can support the requested QoS. The network should abide by the UE request, but is allowed to proceed instead with binding the selected SDF(s) on an existing QoS Flow

[0045] In an embodiment, only one QoS Flow is used for traffic segregation. If UE 212 makes subsequent requests for segregation of additional SDF(s), the additional SDF(s) are multiplexed on the existing QoS Flow that is used for segregation.

[0046] The UE 212 shall not trigger a PDU Session Modification procedure for a PDU Session corresponding to a LADN when the UE 212 is outside the area of availability of the LADN.

[0047] The PS Data Off status, if changed, shall be included in the PCO in the PDU Session Modification Request message.

[0048] For a PDU Session which was established in the EPS, when the UE 212 moves from EPS to 5GS for the first time, the UE 212 includes an Always-on PDU Session Requested indication in the PDU Session Modification Request message if it wants to change the PDU Session to an always-on PDU Session.

[0049] When PCF 310 is deployed, the SMF 308 shall further report the PS Data Off status to PCF 310 if the PS Data Off event trigger is provisioned, the additional behavior of SMF 308 and PCF 310 for 3GPP PS Data Off is defined in TS 23.503 [20],

[0050] The 5GSM Core Network Capability is provided by the UE 212 and handled by SMF 308 as defined in clause 5.4.4b of TS 23.501 [2],

[0051] The UE Integrity Protection Maximum Data Rate indicates the maximum data rate up to which the UE can support UP integrity protection. It is set as defined in TS 23.501 [2],

[0052] The Number Of Packet Filters indicates the number of supported packet filters for signalled QoS rules as described in clause 5.17.2.2.2 of TS 23.501 [2],

[0053] When it moves from EPS to 5GS for the first time, a UE 212 that supports EAS re-discovery as described in clause 6.2.3.3 of TS 23.548 [74], may indicate so in the PCO.

[0054] When it moves from EPS to 5GS for the first time, a UE 212 that hosts the EDC functionality shall indicate in the PCO its capability to support the EDC functionality (see clause 5.2.1 of TS 23.548 [74]).

[0055] Port Management Information Container is received from DS-TT and includes DS-TT port related management information as defined in clause 5.28.3 of TS 23.501 [2], [0056] At step 504, (PCF initiated SM Policy Association Modification) The PCF 310 performs a PCF initiated SM Policy Association Modification procedure as defined in clause 4.16.5.2 to notify SMF 308 about the modification of policies. This may e.g. have been triggered by a policy decision or upon AF requests, e.g. Application Function influence on traffic routing as described in step 5 in clause 4.3.6.2 or AF to provide Port management information Container.

[0057] If the QoS Monitoring for Ultra Reliable Low Latency Communications (URLLC) is requested by the AF, the PCF 310 generates the QoS Monitoring policy for the corresponding service data flow and provides the policy in the PCC rules to the SMF 308 in this step.

[0058] For a DNN related to MCX, PCF includes MCX Support Indication to SMF 308. The MCX Support Indication includes PCF support for MCX on 5GS or not. MCX Support Indication indicates separate support for each different MCX service i.e. MCPTT, MC Video and MC Data.

[0059] At 506, (SMF requested modification) The UDM 306 updates the subscription data of SMF 308 by Nudm_SDM_Notification (SUPI, Session Management Subscription Data). The SMF 308 updates the Session Management Subscription Data and acknowledges the UDM 306 by returning an Ack with (SUPI).

[0060] At 508, (SMF requested modification) he SMF 308 may decide to modify PDU Session. This procedure also may be triggered based on locally configured policy or triggered from the (R)AN (see clause 4.2.6 and clause 4.9.1). It may also be triggered if the UP connection is activated (as described in Service Request procedure) and the SMF has marked that the status of one or more QoS Flows are deleted in the 5GC but not synchronized with the UE yet.

[0061] The SMF 308 may decide to modify PDU Session to send updated ECS Address Configuration Information to the UE as defined in clause 6.5.2 of TS 23.548 [74],

[0062] The SMF 308 may decide to modify PDU Session to send updated DNS server address to the UE as defined in clause 6.2.3.2.3 of TS 23.548 [74],

[0063] If the SMF 308 receives one of the triggers in step 1b ~ 1d, the SMF 308 starts SMF requested PDU Session Modification procedure.

[0064] At step 510, (AN initiated modification) (R)AN 202 shall indicate to the SMF 308 when the AN resources onto which a QoS Flow is mapped are released irrespective of whether notification control is configured. (R)AN 202 sends the N2 message (PDU Session ID, N2 SM information) to the AMF 300. The N2 SM information includes the QFI, User location Information and an indication that the QoS Flow is released. The AMF 300 invokes Nsmf_PDUSession_UpdateSMContext (SM Context ID, N2 SM information).

[0065] (AN initiated notification control) If notification control is configured for a GBR QoS Flow, (R)AN sends a N2 message (PDU Session ID, N2 SM information) to SMF when the (R)AN decides the QoS targets of the QoS Flow cannot be fulfilled or can be fulfilled again, respectively. The N2 SM information includes the QFI and an indication that the QoS targets for that QoS Flow cannot be fulfilled or can be fulfilled again, respectively. When QoS targets cannot be fulfilled, the N2 SM information indicates a reference to the Alternative QoS Profile matching the values of the QoS parameters that the NG-RAN is currently fulfilling as specified in clause 5.7.2.4 of TS 23.501. The AMF 300 invokes Nsmf_PDUSession_UpdateSMContext (SM Context ID, N2 SM information) at step 512. If the PCF 310 has subscribed to the event, SMF 308 reports this event to the PCF 310 for each PCC Rule for which notification control is set in step 518.

[0066] In step 514, (AMF initiated modification) if the UE 212 supports CE mode B and use of CE mode changes from restricted to unrestricted or vice versa in the Enhanced Coverage Restriction information in the UE context in the AMF 300 and the UE 212 has already established PDU sessions, then the AMF 300 shall trigger a PDU session modification to the SMFs 308 serving the UE's PDU sessions when the AMF 300 determines that NAS-SM timer shall be updated due to the change of Enhanced Coverage Restriction and include the extended NAS-SM indication only if use of CE mode B is now unrestricted in the Enhanced Coverage Restriction information in the UE context in the AMF 300.

[0067] At step 516, (AMF initiated modification) the AMF 300 informs the SMF 308 of updates of the NWDAF ID(s) used for UE related Analytics and corresponding Analytics ID(s). Also, if the PCF request notification of SM Policy Association and there is any PDU Session established to that DNN, S-NSSAI [PCF binding information, notification of SM Policy Association establishment Indication], Based on the extended NAS-SM timer indication, the SMF shall use the extended NAS-SM timer setting for the UE as specified in TS 24.501

[0068] At step 518, the SMF 308 may need to report some subscribed event to the PCF 310 by performing an SMF initiated SM Policy Association Modification procedure as defined in clause 4.16.5.1. This step may be skipped if PDU Session Modification procedure is triggered by step 504 or 508. If dynamic PCC is not deployed, the SMF 308 may apply local policy to decide whether to change the QoS profile

[0069] The SMF may update the UPF with N4 Rules related to new or modified QoS Flow(s).

[0070] At step 520, the SMF 308 may update the UPF 314 with N4 Rules related to new or modified QoS Flow(s).

If redundant transmission has not been activated to the PDU session and the SMF 308 decides to perform redundant transmission for the QoS Flow, the SMF 308 indicates to the UPF to perform packet duplication and elimination for the QoS Flow.

[0071] If redundant transmission has been activated on the PDU Session and the SMF 308 decides to stop redundant transmission, the SMF 308 indicates the UPF 314 to release the CN Tunnel Info which is used as the redundancy tunnel of the PDU Session and also indicates the UPF to stop packet duplication and elimination for the corresponding QoS Flow(s)

[0072] The method to perform elimination and reordering on RAN/UPF based on the packets received from the two GTP-U tunnels is up to RAN/UPF implementation. The two GTP-U tunnels are terminated at the same RAN node and UPF.

[0073] If redundant transmission has not been activated to the PDU Session and the SMF decides to perform redundant transmission for the QoS Flow with two l-UPFs between the PSA UPF and the NG-RAN, the SMF 308 sends a N4 Session Establishment Request message to the l-UPFs including UL CN Tunnel Info of the PSA UPF and a request to allocate CN Tunnel Info. [0074] SMF 308 may make use of Redundant Transmission Experience analytics provided by NWDAF, when SMF 308 takes a decision whether to perform redundant transmission, or stop redundant transmission if it had been activated, as described in clause 6.13 of TS 23.288

[0075] At step 522, The UPF(s) 314 respond to the SMF 308. If redundant transmission has not been activated to the PDU session and the SMF 308 indicated the UPF 314 to perform packet duplication and elimination for the QoS Flow in step 520, the UPF allocates an additional CN Tunnel Info. The additional CN Tunnel Info is provided to the SMF 308. [0076] If redundant transmission has not been activated to the PDU Session and the SMF decides to perform redundant transmission for the QoS Flow with two l-UPFs in step 520, the UPFs 314 allocate CN Tunnel Info. The CN Tunnel Info of each l-UPF is provided to the SMF 308.

[0077] At step 524, For UE or AN initiated modification, the SMF responds to the AMF through Nsmf_PDUSession_UpdateSMContext Response ([N2 SM information (PDU Session ID, QFI(s), QoS Profile(s), [Alternative QoS Profile(s)], Session-AMBR], [CN Tunnel lnfo(s)]), N1 SM container (PDU Session Modification Command (PDU Session ID, QoS rule(s), QoS rule operation, QoS Flow level QoS parameters if needed for the QoS Flow(s) associated with the QoS rule(s), Session-AMBR, [Always-on PDU Session Granted], [Port Management Information Container]))). See clause 5.7 of TS 23.501 [2] for the QoS Profile, Alternative QoS Profile and QoS rule and QoS Flow level QoS parameters. Alternative QoS Profile is only valid for AN initiated modification.

[0078] If the PDU Session Modification was requested by the UE to modify a PDU Session to an always-on PDU Session, the SMF shall include an Always-on PDU Session Granted indication in the PDU Session Modification Command to indicate whether the PDU Session is to be changed to an always-on PDU Session or not via the Always-on PDU Session Granted indication in the PDU Session Modification Command.

[0079] The N2 SM information carries information that the AMF shall provide to the (R)AN. It may include the QoS profiles and the corresponding QFIs to notify the (R)AN that one or more QoS flows were added, or modified. It may include only QFI(s) to notify the (R)AN that one or more QoS flows were removed. The SMF may indicate for each QoS Flow whether redundant transmission shall be performed by a corresponding redundant transmission indicator. If the SMF decides to activate redundant transmission in step 520, the SMF includes the allocated additional CN Tunnel Info in the N2 SM information. If the SMF decides to perform redundant transmission for new QoS Flow with two l-UPFs in step 520, the SMF includes the allocated CN Tunnel Info of the two l-UPFs in the N2 SM information. If the PDU Session Modification was triggered by the (R)AN Release in step 512 the N2 SM information carries an acknowledgement of the (R)AN Release. If the PDU Session Modification was requested by the UE for a PDU Session that has no established User Plane resources, the N2 SM information provided to the (R)AN includes information for establishment of User Plane resources.

[0080] If redundant transmission has been activated on the PDU Session and the SMF decides to stop redundant transmission in step 520, the SMF indicates the (R)AN to release the AN Tunnel and stop packet duplication and elimination associated with the redundancy tunnel of the PDU Session. [0081] The N1 SM container carries the PDU Session Modification Command that the AMF shall provide to the UE. It may include the QoS rules, QoS Flow level QoS parameters if needed for the QoS Flow(s) associated with the QoS rule(s) and corresponding QoS rule operation and QoS Flow level QoS parameters operation to notify the UE that one or more QoS rules were added, removed or modified.

[0082] If port number and a Port Management Information Container have been received from PCF in Step 518 and the port number matches the port number assigned for the DS-TT port for this PDU session, then SMF includes the Port Management Information Container in the N1 SM container.

[0083] The SMF may need to send transparently through NG-RAN the PDU Session Modification Command to inform the UE about changes in the QoS parameters (i.e. 5QI, GFBR, MFBR) that the NG-RAN is currently fulfilling after the SMF receives QoS Notification Control as defined in clause 57.2.4 of TS 23.501 [2], When the SMF sends on the PDU Session Modification Command transparently through NG-RAN, the N2 SM information is not included as part of the Namf_Communication_N1 N2MessageTransfer.

[0084] If the UE indicated in the PCO that it supports the EDC functionality, the SMF may indicate to the UE either that the use of the EDC functionality is allowed for the PDU Session or that the use of the EDC functionality is required for the PDU Session (see clause 5.2.1 of TS 23.548 [74])

[0085] At step 526, for SMF requested modification, the SMF invokes Namf_Communication_N1 N2MessageTransfer (New: MCX 5GC Support Indication, [N2 SM information] (PDU Session ID, QFI(s), QoS Profile(s), [Alternative QoS Profile(s)], Session-AMBR, [CN Tunnel lnfo(s)], QoS Monitoring indication, QoS Monitoring reporting frequency, [TSCAI(s)], New: MCX 5GC Support Indication), N1 SM container (PDU Session Modification Command (PDU Session ID, QoS rule(s), QoS Flow level QoS parameters if needed for the QoS Flow(s) associated with the QoS rule(s), QoS rule operation and QoS Flow level QoS parameters operation, Session-AMBR))). [0086] The SMF may indicate for each QoS Flow whether redundant transmission shall be performed by a corresponding redundant transmission indicator. If the SMF decides to activate redundant transmission in step 520, the SMF includes the allocated additional CN Tunnel Info in the N2 SM information. If the SMF decides to perform redundant transmission for new QoS Flow with two l-UPFs in step 520, the SMF includes the allocated CN Tunnel Info of the two I- UPFs in the N2 SM information.

[0087] If redundant transmission has been activated on the PDU Session and the SMF decides to stop redundant transmission in step 520, the SMF indicates the (R)AN to release the AN Tunnel and stop packet duplication and elimination associated with the redundancy tunnel of the PDU Session.

[0088] The SMF indicates the request for QoS Monitoring for the QoS Flow according to the information received from the PCF in step 504, or based on SMF local policy, e.g. when the RAN rejected the creation of a specific QoS Flow for URLLC. In the case of receiving the QoS Monitoring indication, the RAN enables the RAN part of UL/DL packet delay measurement for the QoS Flow and the QoS Monitoring reporting frequency is used by RAN to determine the packet delay measurement frequency of the RAN part. The TSCAI is defined in clause 5.27.2 of TS 23.501 [2], [0089] If the UE is in CM-IDLE state and an ATC is activated, the AMF updates and stores the UE context based on the Namf_Communication_N1 N2MessageTransfer and steps 532, 534, 536 and 538 are skipped. When the UE is reachable e.g. when the UE enters CM-CONNECTED state, the AMF forwards the N1 message to synchronize the UE context with the UE.

[0090] For a DNN related to MCX, the SMF includes both to RAN and AMF, MCX 5GC Support Indication which combines indicators for PCF and SMF support or not for MCX on 5GS into one indicator with the lowest supported value. MCX Support Indication includes separate support for each different MCX service i.e. MCPTT, MC Video and MC Data. AMF shall store the indication in the UE context and shall forward it to RAN in N2 message when the UE is reachable e.g. when the UE enters CM-CONNECTED state.

[0091] At step 528, for SMF requested modification due to updated SMF-Associated parameters from the UDM, the SMF may provide the SMF derived CN assisted RAN parameters tuning to the AMF. The SMF invokes

Nsmf_PDUSession_SMContextStatusNotify (SMF derived CN assisted RAN parameters tuning) towards the AMF. The AMF stores the SMF derived CN assisted RAN parameters tuning in the associated PDU Session context for this UE.

[0092] At step 530, for SMF requested modification due to updated NWDAF ID, the SMF informs the AMF of updates of the NWDAF ID(s) used for UE related Analytics and corresponding Analytics ID(s).

[0093] At step 532, the AMF may send N2 ([N2 SM information received from SMF], NAS message (PDU Session ID, N1 SM container (PDU Session Modification Command))) Message to the (R)AN.

[0094] If N2 SM information includes MCX 5GC Support Indication, including an indicator for 5GC support for MCX or not, RAN shall store it and use it for mobility reasons e.g. trigger MCX fallback. MCX Support Indication indicates separate support for each different MCX service i.e. MCPTT, MC Video and MC Data

[0095] At step 534, the (R)AN may issue AN specific signaling exchange with the UE that is related with the information received from SMF. For example, in the case of a NG-RAN, an RRC Connection Reconfiguration may take place with the UE modifying the necessary (R)AN resources related to the PDU Session or if only N1 SM container is received in step 4 from AMF, RAN transports only the N1 SM container to the UE.

[0096] The (R)AN may consider the updated CN assisted RAN parameters tuning to reconfigure the AS parameters.

[0097] As part of this, the N1 SM container is provided to the UE. If the N1 SM container includes a Port Management Information Container then the UE provides the container to DS-TT.

[0098] If new DNS server address is provided to the UE in the PCO, the UE can refresh all EAS(s) information (e.g. DNS cache) bound to the PDU Session, based on UE implementation as described in clause 6.2.3.2.3 of TS 23.548 [74], [0099] At step 536, the (R)AN may acknowledge N2 PDU Session Request by sending a N2 PDU Session Ack (N2 SM information (List of accepted/rejected QFI(s), AN Tunnel Info, PDU Session ID, Secondary RAT usage data), User location Information) Message to the AMF. In the case of Dual Connectivity, if one or more QFIs were added to the PDU Session, the Master RAN node may assign one or more of these QFIs to a NG-RAN node which was not involved in the PDU Session earlier. In this case the AN Tunnel Info includes a new N3 tunnel endpoint for QFIs assigned to the new NG-RAN node. Correspondingly, if one or more QFIs were removed from the PDU Session, a (R)AN node may no longer be involved in the PDU Session anymore and the corresponding tunnel endpoint is removed from the AN Tunnel Info. The NG-RAN may reject QFI(s) if it cannot fulfil the User Plane Security Enforcement information for a corresponding QoS Profile, e.g. due to the UE Integrity Protection Maximum Data Rate being exceeded. When receiving the request for QoS Monitoring, the (R)AN may indicate its rejection to perform QoS Monitoring, e.g. due to the (R)AN load condition. The (R)AN may reject the addition or modification of a QoS Flow, e.g. due to handling of the UE-Slice-MBR as described in clause 5.7.1.10 of TS 23.501 [2], If the (R)AN rejects the addition or modification of a QoS Flow, the SMF is responsible of updating the QoS rules and QoS Flow level QoS parameters associated to that QoS Flow in the UE accordingly. [0100] If the PLMN has configured secondary RAT usage reporting, the NG-RAN node may provide RAN Usage Data Report. The User Location Information shall include the serving cell's ID and, if Dual Connectivity is activated for the UE, the PSCell ID.

[0101] If the redundant transmission has not been activated to the PDU session and the SMF indicates to the RAN that one of the QoS Flow shall perform redundant transmission, the RAN includes an additional AN tunnel info in N2 SM information.

[0102] At step 538, The AMF forwards the N2 SM information and the User location Information received from the AN to the SMF via Nsmf_PDUSession_UpdateSMContext service operation. The SMF replies at step 540 with a Nsmf_PDUSession_UpdateSMContext Response.

[0103] If the (R)AN rejects QFI(s) the SMF is responsible of updating the QoS rules and QoS Flow level QoS parameters if needed for the QoS Flow(s) associated with the QoS rule(s) in the UE accordingly.

[0104] If the PDU Session modification is UE triggered and the N2 SM information indicates modification failure, the SMF shall reject the PDU session modification by including a N1 SM container with a PDU Session Modification Reject message (see clause 8.3.3 of TS 24.501 [25]) in the Nsmf_PDUSession_UpdateSMContext Response in step 540. Step 542 and 544 are skipped in this case.

[0105] At step 542 and 544, The SMF may update N4 session of the UPF(s) that are involved by the PDU Session Modification by sending N4 Session Modification Request message to the UPF (see NOTE 3).

[0106] The SMF may update the UPF with N4 Rules related to new, modified or removed QoS Flow(s), unless it was done already in step 520.

[0107] NOTE 4:This allows the DL packets of the new or modified QoS Flow to be transferred.

[0108] If an additional AN Tunnel Info is returned by RAN in step 536, the SMF informs the UPF about this AN

Tunnel Info for redundant transmission. In the case of redundant transmission with two l-UPFs, the SMF provides AN Tunnel Info to two l-UPFs. If CN Tunnel Info of two l-UPFs is allocated by the UPFs in step 522, the SMF also provides the DL CN Tunnel Info of two l-UPFs to the UPF (PSA). [0109] If the QoS Monitoring for URLLC is enabled for the QoS Flow, the SMF provides the N4 rules containing the QoS Monitoring policy generated according to the information received in step 1b to the UPF via the N4 Session Modification Request message.

[0110] If port number and a Port Management Information Container have been received from PCF in Step 518 and the port number matches the port number of the NW-TT port for this PDU session, then SMF includes the Port Management Information Container in the N4 Session Modification Request. If the N4 Session Modification Request includes a Port Management Information Container, then UPF also includes a Port Management Information Container in the N4 Session Modification Response.

[0111] At step 546, the UE acknowledges the PDU Session Modification Command by sending a NAS message (PDU Session ID, N1 SM container (PDU Session Modification Command Ack, [Port Management Information Container])) message.

[0112] At step 548, the RAN forwards the NAS message to the AMF.

[0113] At step 550, the AMF forwards the N1 SM container (PDU Session Modification Command Ack) and User

Location Information received from the AN to the SMF via Nsmf_PDUSession_UpdateSMContext service operation. The SMF replies at step 552 with a Nsmf_PDUSession_UpdateSMContext Response. The SMF includes in Nsmf_PDUSession_UpdateSMContext Response UE NAS 5QI Status Indicator which informs RAN of the received NAS modification result from the UE per each 5QI together with a cause e.g. MCX fallback.

[0114] At step 552b, which can be an alternative solution to 552, another message from SMF 308 to AMF 300 may be sent including "User Equipment device, UE, (212) Non-Access Stratum, NAS, 5G Quality of Service Indicator, 5QI.

[0115] At step 553, the AMF 300 can provide the RAN 202 with an N2 message

[0116] If the SMF initiated modification is to delete QoS Flows (e.g. triggered by PCF) which do not include QoS Flow associated with the default QoS rule and the SMF does not receive response from the UE, the SMF marks that the status of those QoS Flows is to be synchronized with the UE.

[0117] At step 554, The SMF may update N4 session of the UPF(s) that are involved by the PDU Session Modification by sending N4 Session Modification Request (N4 Session ID) message to the UPF. For a PDU Session of Ethernet PDU Session Type, the SMF may notify the UPF to add or remove Ethernet Packet Filter Set(s) and forwarding rule(s). The UPFs that are impacted in the PDU Session Modification procedure depends on the modified QoS parameters and on the deployment. For example in the case of the session AMBR of a PDU Session with an UL CL changes, only the UL CL is involved. This note also applies to the steps 542 and 544.

[0118] At step 558, if the SMF interacted with the PCF in step 504 or 518, the SMF notifies the PCF whether the PCC decision could be enforced or not by performing an SMF initiated SM Policy Association Modification procedure as defined in clause 4.16.5.1. If the trigger for 5GS Bridge information available is armed and the SMF received a Port Management Information Container from either UE or UPF, then SMF provides the Port Management Information Container and the port number of the related port to the PCF in this step, as described in clause 5.28.3.2 of TS 23.501 . If the trigger for 5GS Bridge information available is armed and the SMF received the User Plane node Management Information Container from UPF, then the SMF provides the User Plane node Management Information Container to the PCF as described in clause 5.28.3.2 of TS 23.501. SMF notifies any entity that has subscribed to User Location Information related with PDU Session change.

[0119] If step 1b is triggered to perform Application Function influence on traffic routing by step 5 in clause 4.3.6.2, the SMF may reconfigure the User Plane of the PDU Session as described in step 6 in clause 4.3.6.2.

[0120] It is to be appreciated that the description above related to FIGS. 5A and 5B refer to a PDU Session Modification procedure for MCX, but in other embodiments, a similar process can be applied to PDU Session Establishment, with many of the steps being shared or similar. For instance, for a PDU Session Establishment, the message of step 1a (502) would be a PDU Session Establishment Request, and the message of step 9 (546) would be a PDU Session Establishment Accept. Further, it should be appreciated by those of skill in the art that the MCX Support Indication included in the various messages of Figures 5A and 5B may be included in similar messages of other types of procedures. For example, in Step 532, the AMF provides the MCX Support Indication to the RAN as part of the PDU Session Modification procedure; however, the AMF may provide the MCX Support Indication to the RAN in other procedures, e.g., when the UE transitions from IDLE to CONNECTED state.

Figures 6A-6B

[0121] The following section is adapted from TS 23.502 V17.5.0 (2022-06) section 4.2.3.2. The figures 6A and 6B are adapted from Figure 4.2.3.2-1 from section 4.2.3.2.

[0122] 4.2.3.2 UE Triggered Service Request

[0123] The UE in CM IDLE state initiates the Service Request procedure in order to send uplink signalling messages, user data, to request emergency services fallback, or as a response to a network paging request. The UE shall not initiate UE Triggered Service Request from CM-IDLE if there is a Service Gap timer running. After receiving the Service Request message, the AMF may perform authentication. After the establishment of the signalling connection to an AMF, the UE or network may send signalling messages, e.g. PDU Session establishment from UE to the SMF, via the AMF.

[0124] The Service Request procedure is used by a UE in CM-CONNECTED to request activation of a User Plane connection for PDU Sessions and to respond to a NAS Notification message from the AMF. When a User Plane connection for a PDU Session is activated, the AS layer in the UE indicates it to the NAS layer.

[0125] The Service Request procedure is used by the Multi-USIM UE over 3GPP access, in:

[0126] a)CM-CONNECTED state to request release of the UE connection, stop data transmission, discard of any pending data and, optionally, store Paging Restriction Information; or

[0127] b)CM-IDLE state to request removal of Paging Restriction Information. [0128] The Multi-USIM UE shall not execute UE triggered Service Request procedure with Release Request indication if regulatory prioritized services (e.g. emergency service, emergency callback waiting) are ongoing. After an emergency call, the UE shall not execute a UE triggered Service Request procedure with Release Request indication for a duration which is sufficient for emergency call back.

[0129] c)CM-IDLE state to respond to paging with a Reject Paging Indication that indicates that N1 connection shall be released and no user plane connection shall be established. The UE optionally provides the Paging Restriction Information. The UE may be unable to respond to paging with a Reject Paging Indication, e.g. due to UE implementation constraints.

[0130] NOTE 1 : A Multi-USIM UE in RRC Inactive/CM-CONNECTED state that decides to reject the RAN paging, requests the release of the UE connection as in bullet a) above. The UE can discard, by implementation, any data or NAS PDUs that it receives before it is released.

[0131] For any Service Request, the AMF responds with a Service Accept message to synchronize PDU Session status between UE and network, if necessary. The AMF responds with a Service Reject message to UE, if the Service Request cannot be accepted by network. The AMF may steer the UE from 5GC by rejecting the Service Request. The AMF should take into account the Preferred and Supported Network Behaviour (see clause 5.31.2 of TS 23.501 [2]) and availability of EPC to the UE before steering the UE from 5GC. The Service Reject message may include an indication or cause code requesting the UE to perform Registration procedure.

[0132] For this procedure, the impacted SMF and UPF, if any, are all under control of the PLMN serving the UE, e.g. in Home Routed roaming case the SMF and UPF in HPLMN are not involved if V-SMF relocation is not triggered. [0133] For Service Request due to user data, network may take further actions if User Plane connection activation is not successful.

[0134] The procedure in this clause 4.2.3.2 is applicable to the scenarios with or without intermediate UPF and with or without intermediate UPF reselection.

[0135] If the UE initiates Service Request procedures via non-3GPP Access, functions defined in clause 4.12.4.1 are applied.

[0136] The User Plane of all PDU Sessions with redundant l-UPFs or with redundant N3/N9 tunnels for URLLC shall be activated during the Service Request procedure if the UE in CM-IDLE state initiates the Service Request procedure from 3GPP access. If the redundant l-UPFs are to be added/replaced/removed, the N4 Session procedure to manage the l-UPF is done for each l-UPF in steps 6c, 6d,7a, 7b, 8a, 8b, 9, 10, 17a, 17b, 20a, 20b, 21 a, 21b, 22a and 22b of the figure 4.2.3.2-1 . If the redundant N3/N9 tunnels are used for URLLC and the l-UPF is to be added/replaced/removed, the N4 Session procedure to update the tunnel is done for each N3/N9 tunnel in steps 6c, 6d, 7a, 7b, 8a, 8b, 9, 10, 17a, 17b. 20a, 20b, 21 a and 21b of the figure 4.2.3.2-1. [0137] 1 . (step 602) UE to (R)AN: AN message (AN parameters, Service Request (List Of PDU Sessions To Be

Activated, List Of Allowed PDU Sessions, security parameters, PDU Session status, 5G-S-TMSI, [NAS message container], Exempt Indication, [Release Request indication], [Paging Restriction Information], [Reject Paging Indication])). [0138] The NAS message container shall be included if the UE is sending a Service Request message as an Initial NAS message and the UE needs to send non-cleartext lEs, see clause 4.4.6 in TS 24.501 [25],

[0139] The Multi-USIM UE in CM-CONNECTED state may include the Release Request indication and optionally Paging Restriction Information in the Service Request message over 3GPP access, if the UE intends to leave CM- CONNECTED state.

[0140] The Multi-USIM UE in CM-IDLE state may include the Release Request indication and not include Paging Restriction Information in the Service Request message over 3GPP access, if the UE intends to delete the Paging Restriction Information.

[0141] If the Multi-USIM UE in CM-IDLE state decides not to accept the paging, it may send a Service Request message including a Reject Paging Indication and optionally Paging Restriction Information, unless it is not able to send this message e.g. due to UE implementation constraints.

[0142] The List Of PDU Sessions To Be Activated is provided by UE when the UE wants to re-activate the PDU Session(s). The List Of Allowed PDU Sessions is provided by the UE when the Service Request is a response of a Paging or a NAS Notification for a PDU Session associated with non-3GPP access and identifies the PDU Sessions that can be transferred to 3GPP access.

[0143] In the case of NG-RAN:

[0144] -The AN parameters include 5G-S-TMSI, Selected PLMN ID (or PLMN ID and NID, see clause 5.30 of TS 23.501 [2]), Establishment cause and may also include NSSAI information. The Establishment cause provides the reason for requesting the establishment of an RRC connection. Whether and how the UE includes the NSSAI information as part of the AN parameters is dependent on the value of the Access Stratum Connection Establishment NSSAI Inclusion Mode parameter, as specified in clause 5.15.9 of TS 23.501 [2],

[0145] -The UE sends Service Request message towards the AMF encapsulated in an RRC message to the NG- RAN. The RRC message(s) that can be used to carry the 5G-S-TMSI and this NAS message are described in TS 38.331 [12] and TS 36.331 [16],

[0146] If the Service Request is triggered by the UE for user data, the UE identifies, using the List Of PDU Sessions To Be Activated, the PDU Session(s) for which the UP connections are to be activated in Service Request message. When the UE includes the List Of PDU Sessions To Be Activated, the UE shall indicate PDU Sessions only associated with the access the Service Request is related to. If the Service Request is triggered by the UE for signalling only, the UE doesn't identify any List Of PDU Sessions To Be Activated. If this procedure is triggered for paging response and the UE has at the same time some user data to be transferred, the UE identifies the PDU Session(s) whose UP connections are to be activated in Service Request message, by the List Of PDU Sessions To Be Activated. Otherwise the UE does not identify any PDU Session(s) in the Service Request message for paging response. As defined in TS 24.501 [25] the UE shall include always-on PDU Sessions which are accepted by the network in the List Of PDU Sessions To Be Activated even if there are no pending uplink data for those PDU Sessions or when the Service Request is triggered for signaling only or when the Service Request is triggered for paging response.

[0147] If the Service Request over 3GPP access is triggered in response to the paging or NAS Notification indicating non-3GPP access, the Service Request message shall identify the list of PDU Sessions associated with the non-3GPP access that can be re-activated over 3GPP access in the List Of Allowed PDU Sessions, as described in clause 4.2.3.3 (step 6) of this specification and in clause 5.6.8 of TS 23.501 [2], When the UE over 3GPP access is in NB- N1 mode and the resulting number of PDU Sessions with user plane resources activated for the UE does not exceed the maximum number of supported user plane resources (0, 1 or 2), based on whether the UE supports UP data transfer and the UE's 5GMM Core Network Capability as described in clause 5.31.19 of TS 23.501 [2], the AMF shall notify the SMF that reactivation of the user-plane resources for the corresponding PDU session(s) associated with non-3GPP access can be performed as defined in TS 24.501 [25],

[0148] If the Service Request is triggered to report PS Data Off status change and the UE is in Non-Allowed Area, the UE shall send Service Request message with an indication that the message is exempted from restriction (e.g. Non- Allowed Area). In this case, if the UE is in Non-Allowed Area, the UE shall not include the List Of PDU Sessions To Be Activated and as a result the always-on PDU Session is not re-activated during the Service Request procedure.

[0149] The PDU Session status indicates the PDU Sessions available in the UE.

[0150] The UE shall not trigger a Service Request procedure for a PDU Session corresponding to a LADN when the UE is outside the area of availability of the LADN.

[0151] NOTE 2:A PDU Session corresponding to a LADN is not included in the List Of PDU Sessions To Be Activated when the UE is outside the area of availability of the LADN.

[0152] For UE in CM-CONNECTED state, only the List Of PDU Sessions To Be Activated and List Of Allowed PDU Sessions need to be included in the Service Request.

[0153] 2. (step 604) (R)AN to AMF: N2 Message (N2 parameters, Service Request).

[0154] Details of this step are described in TS 38.413 [10], If the AMF can't handle the Service Request it will reject it.

[0155] When NG-RAN is used, the N2 parameters include the 5G-S-TMSI, Selected PLMN ID (or PLMN ID and NID, see clause 5.30 of TS 23.501 [2]), Location information and Establishment cause, UE Context Request.

[0156] If the UE is in CM-IDLE state, the NG-RAN obtains the 5G-S-TMSI in RRC procedure. NG-RAN selects the AMF according to 5G-S-TMSI. The Location Information relates to the cell in which the UE is camping.

[0157] Based on the PDU Session status, the AMF may initiate PDU Session Release procedure in the network for the PDU Sessions whose PDU Session ID(s) were indicated by the UE as not available. [0158] When the Establishment cause is associated with priority services (e.g. MPS, MCX), or when the AMF determines that the UE has priority subscription (e.g. MPS, MCX) in the UDM, the AMF includes a Message Priority header to indicate priority information. Other NFs relay the priority information by including the Message Priority header in service-based interfaces, as specified in TS 29.500 [17],

[0159] The AMF enforces the Mobility Restrictions as specified in clause 5.3.4.1.1 of TS 23.501 [2],

[0160] If there is a Service Gap timer running in AMF for the UE and the AMF is not waiting for a MT paging response from the UE and the Service Request is not for regulatory prioritized services like Emergency services or not for exception reporting, the AMF rejects the Service Request with an appropriate cause. In addition, AMF may also provide a UE with a Mobility Management Back-off timer set to the remaining value of the Service Gap timer.

[0161] If the AMF supports RAGS and the AMF detects that the selected PLMN is different from the currently registered PLMN for the UE, the AMF determines the UE Radio Capability ID of the newly selected PLMN to the gNB as described in clause 5.4.4.1a of TS 23.501 [2],

[0162] For NR satellite access, the AMF may decide to verify the UE location and determine whether the PLMN is allowed to operate at the UE location, as described in clause 5.4.11.4 of TS 23.501 [2], If the UE receives a Service Reject message with cause value indicating that the PLMN is not allowed to operate in the present UE location, the UE shall attempt to select a PLMN, as specified in TS 23.122 [22],

[0163] 3a)AMF to (R)AN: N2 Request (security context, Mobility Restriction List, list of recommended cells I TAs I NG-RAN node identifiers).

[0164] If the 5G-AN had requested for UE Context or there is a requirement for AMF to provide this e.g. the AMF needs to initiate fallback procedure as in clause 4.13.4.2 for Emergency services, AMF initiates NGAP procedure as specified in TS 38.413 [10], For UE in CM-IDLE state, 5G-AN stores the Security Context in the UE AN context. Mobility Restriction List is described in clause 5.3.4.1 of TS 23.501 [2],

[0165] The 5G-AN uses the Security Context to protect the messages exchanged with the UE as described in TS 33.501 [15],

[0166] If the NG-RAN node had provided the list of recommended cells I TAs I NG-RAN node identifiers during the AN Release procedure (see clause 4.2.6), the AMF shall include it in the N2 Request. The RAN may use this information to allocate the RAN Notification Area when the RAN decides to enable RRC Inactive state for the UE.

[0167] 3. (step 606) If the Service Request was not sent integrity protected or integrity protection verification failed, the AMF shall reject the Service Request as stated in TS 24.501 [25],

[0168] If the UE in CM-IDLE state triggered the Service Request to establish a signalling connection only, after successful establishment of the signalling connection the UE and the network can exchange NAS signalling and steps 4 to 11 and 15 to 22 are skipped. [0169] If the UE in Non-Allowed Area triggered the Service Request with an indication that the message is exempted from restriction (e.g. Non-Allowed Area), the AMF should accept the Service Request. In this case, if the UE is in Non-Allowed Area, the AMF rejects user plane setup request from the SMF except for emergency services.

[0170] If the procedure was triggered in response to paging or NAS notification indicating non-3GPP access and the AMF received N1 SM Container only from the SMF in step 3a of clause 4.2.3.3, the AMF sends the NAS signalling including the N1 SM Container to the UE in step 7 of clause 4.2.3.3 without updating the access associated to the PDU Session.

[0171] If the Service Request message is received over 3GPP access without a Release Request indication or a Reject Paging Indication, the AMF shall delete any stored Paging Restriction Information for this UE and stop restricting paging accordingly.

[0172] If the Service Request message over 3GPP access includes a Release Request indication or a Reject Paging Indication, then:

[0173] -the AMF may accept or reject the received Paging Restriction Information requested by the UE based on operator policy. If the AMF rejects the Paging Restriction Information, the AMF removes any stored Paging Restriction Information from the UE context and discards the UE requested Paging Restriction Information. If the AMF accepts the Paging Restriction Information from the UE, the AMF stores the Paging Restriction Information from the UE in the UE context.

[0174] -If no Paging Restriction Information is provided, no paging restrictions apply and the AMF removes any stored Paging Restriction Information from the UE context.

[0175] -no User Plane resources are established and instead the AMF triggers the AN Release procedure as described in clause 4.2.6.

[0176] NOTE 3:lf AMF does not perform steps 5-7 before step 2 then some DL data might not be delivered to the UE.

[0177] If the procedure was triggered in response to paging and the Service Request message includes a Reject Paging Indication, the AMF initiates the UCU procedure as described in step 7 of clause 4.2.3.3 before the triggering of the AN Release procedure.

[0178] 4. (step 608) [Conditional] AMF to SMF: Nsmf_PDUSession_UpdateSMContext Request (PDU Session

ID(s), Operation Type, UE location information, Access Type, RAT Type, UE presence in LADN service area, Indication of Access Type can be changed, [MO Exception Data Counter]).

[0179] The Nsmf_PDUSession_UpdateSMContext Request is invoked:

[0180] -If the UE identifies List Of PDU Sessions To Be Activated in the Service Request message;

[0181] -This procedure is triggered by the SMF but the PDU Session(s) identified by the UE correlates to other PDU Session ID(s) than the one triggering the procedure; or [0182] -If this procedure is triggered by the SMF in response to paging or NAS notification indicating 3GPP access or if this step onwards is invoked following step 4a of clause 4.2.3.3 and the current UE location is outside the "Area of validity for the N2 SM information" provided by the SMF in step 3a of clause 4.2.3.3 or the "Area of validity for the N2 SM information" was not provided by the SMF in step 3a of clause 4.2.3.3, the AMF shall not send the N2 information provided by the SMF in step 3a of clause 4.2.3.3. Otherwise, if the current UE location is in the "Area of validity for the N2 SM information", steps 4 to 11 are skipped; or

[0183] -If this procedure is triggered by the SMF in response to paging or NAS notification indicating non-3GPP access and the AMF received N2 SM Information only, or both N1 SM Container and N2 SM Information in step 3a of clause 4.2.3.3.

[0184] If the DNN corresponds to an LADN then the "UE presence in LADN service area" indicates if the UE is IN or OUT of the LADN service area. If the AMF does not provide the "UE presence in LADN service area" indication and the SMF determines that the DNN corresponds to a LADN, then the SMF considers that the UE is OUT of the LADN service area.

[0185] The AMF determines the PDU Session(s) for which the UP connection(s) shall be activated and sends an Nsmf_PDUSession_UpdateSMContext Request to SMF(s) associated with the PDU Session(s) with Operation Type set to "UP activate" to indicate establishment of User Plane resources for the PDU Session(s). The AMF determines Access Type and RAT Type, see clause 4.2.2.2.1. If the RAT type is NB-loT, the AMF shall ensure that the number of PDU session(s) for which UP connection(s) are active does not exceed this UE's maximum number of supported user plane resources (0, 1 or 2) based on whether the UE supports UP data transfer and the UE 5GMM Core Network Capability as described in clause 5.31.19 of TS 23.501 [2],

[0186] If the procedure was triggered in response to paging or NAS Notification indicating non-3GPP access, the AMF received N2 SM Information in step 3a of clause 4.2.3.3 and the PDU Session for which the UE was paged or notified is not in the List Of Allowed PDU Sessions provided by the UE, the AMF notifies the SMF that the UE is not reachable. For other PDU Sessions in the List Of Allowed PDU Sessions the Service Request Procedure succeeds without re-activating the User Plane of any PDU Sessions, unless they have also been included by the UE in the List Of PDU Sessions To Be Activated.

[0187] If the procedure was triggered in response to paging or NAS notification indicating non-3GPP access and the PDU Session for which the UE was paged or notified is in the List Of Allowed PDU Sessions provided by the UE and the AMF received N2 SM Information only or N1 SM Container and N2 SM Information from the SMF in step 3a of clause 4.2.3.3, the AMF notifies the SMF that the access type of the PDU session can be changed. The AMF discards any already received N1 SM Container and N2 SM Information. In Home Routed roaming case, the V-SMF triggers Nsmf_PDUSession_Update service operation towards the H-SMF to notify the access type of the PDU Session can be changed and the procedure continues as specified in clause 4.3.3.3 from step 1a to step 10. [0188] If the UE is accessing via the NB-loT RAT, the AMF may inform all (H-)SMFs whether the RRC establishment cause is set to "MO exception data", as described in clause 5.31.14.3 of TS 23.501 [2], The AMF may immediately send the MO Exception Data Counter to the (H-)SMF.

[0189] The AMF may receive a Service Request to establish another NAS signalling connection via a new NG-RAN while it has maintained an old NAS signalling connection for UE still via an old NG-RAN. The new NG-RAN and the old NG-RAN can be the same NG-RAN node. In this case, AMF shall trigger the AN release procedure toward the old NG- RAN to release the old NAS signalling connection as defined in clause 4.2.6 and:

[0190] -For the PDU Sessions indicated by the UE in the List Of PDU Sessions To Be Activated, the AMF requests the SMF to activate the PDU Session(s) immediately by performing this step 4; and

[0191] NOTE 4:This activates the UP of PDU Session(s) using resources of the new NG-RAN.

[0192] -For the PDU Sessions indicated by the old NG-RAN in the "List of PDU Session ID(s) with active N3 user plane" but not in the List Of PDU Sessions To Be Activated sent by the UE, the AMF requests the SMF to deactivate the PDU Session (s).

[0193] NOTE 5: This deactivates the UP of PDU Session(s) that are no more needed by the UE.

[0194] 5a.Void.

[0195] 5b. (step 610) If the PDU Session ID corresponds to a LADN and the SMF determines that the UE is outside the area of availability of the LADN based on the "UE presence in LADN service area" from the AMF, the SMF decides to (based on local policies) either:

[0196] -keep the PDU Session, but reject the activation of User Plane connection for the PDU Session and inform the AMF about it. If the procedure has been triggered by a Network Triggered Service Request as described in clause 4.3.2.3, the SMF may notify the UPF that originated the Data Notification to discard downlink data for the PDU Sessions and/or to not provide further Data Notification messages; or

[0197] -to release the PDU Session: the SMF releases the PDU Session and informs the AMF that the PDU Session is released.

[0198] In any case of the two cases above the SMF answers to the AMF (stepIO) with an appropriate reject cause and the User Plane Activation of PDU Session is stopped.

[0199] Otherwise, based on the location info received from the AMF, the SMF checks the UPF Selection Criteria according to clause 6.3.3 of TS 23.501 [2] and determines to perform one of the following:

[0200] -accepts the activation of UP connection and continue using the current UPF(s);

[0201] -accepts the activation of UP connection and selects a new intermediate UPF (or add/remove an intermediate UPF), if the UE has moved out of the service area of the UPF that was previously connecting to the AN, while maintaining the UPF(s) acting as PDU Session Anchor. The steps to perform l-UPF addition/change/removal are described as conditional steps in the following of the current procedure; or [0202] NOTE 6: If the old and/or new l-UPF implements an UL CL or BP functionality and a PDU Session Anchor for connectivity to the local access to the Data Network as described in clause 5.6.4.2 of TS 23.501 [2], the signalling described in the current clause is intended as the signalling to add, remove or change the PDU Session Anchor and must be complemented by the signalling to add, release or change the UL CL or BP as described respectively in clauses 4.3.5.4, 4.3.5.5 and 4.3.57.

[0203] -rejects the activation of UP connection of a PDU Session of SSC mode 2 and trigger re-establishment of the PDU Session after Service Request procedure to perform the allocation of a new UPF to act as PDU Session Anchor, e.g. the UE has moved out of the service area of the anchor UPF which is connecting to NG-RAN.

[0204] In the case that the SMF fails to find suitable l-UPF, the SMF decides to (based on local policies) either:

[0205] -trigger re-establishment of PDU Session. After Service Request procedure, SMF sends N1 SM message to the UE via the AMF by invoking Namf_Communication_N1 N2MessageTransfer containing the cause indicating PDU Session re-establishment is required for the UE; or

[0206] -keep the PDU Session, but reject the activation request of User Plane connection for the PDU Session and inform the AMF about it; or

[0207] -release the PDU Session after Service Request procedure.

[0208] If the SMF has determined that the UE is performing Inter-RAT mobility to or from the NB-loT RAT then the SMF uses the "PDU Session continuity at inter RAT mobility" to determine how to handle the PDU Session.

[0209] 6a. (step 612) [Conditional] SMF to UPF (PSA): N4 Session Modification Request.

[0210] Depending on the network deployment, the CN Tunnel Info of UPF (PSA) allocated for N3 or N9 interface may be changed during the Service Request procedure, e.g. UPF connected to different IP domains. If different CN Tunnel Info need be used, the SMF sends N4 Session Modification Request message to UPF (PSA) and requests CN Tunnel Info providing the target Network Instance.

[0211] 6b. (step 614) [Conditional] UPF (PSA) to SMF: N4 Session Modification Response.

[0212] The UPF (PSA) sends an N4 Session Establishment Response message to the SMF. The UPF provides CN Tunnel Info to the SMF. The UPF (PSA) associate the CN Tunnel Info with UL Packet detection rules provided by the SMF.

[0213] If the redundant l-UPFs are used for URLLC, each l-UPF provides UL CN Tunnel Info for N3 interface to the SMF in the N4 Session Establishment Response message.

[0214] If the redundant N3 tunnels are used for URLLC, the UPF (PSA) provides redundant UL CN Tunnel Info for N3 interface to the SMF in N4 Session Establishment Response message.

[0215] 6c. (step 616) [Conditional] SMF to new UPF (intermediate): N4 Session Establishment Request.

[0216] If the SMF selects a new UPF to act as intermediate UPF for the PDU Session, or if the SMF selects to insert an intermediate UPF for a PDU Session which did not have an intermediate UPF, an N4 Session Establishment Request message is sent to the new UPF, providing Packet detection, Data forwarding, enforcement and reporting rules to be installed on the intermediate UPF. The CN Tunnel Info (on N9) of PSA, i.e. which is used to establish the N9 tunnel, for this PDU Session is also provided to the intermediate UPF.

[0217] If a new UPF is selected by the SMF to replace the old (intermediate) UPF, the SMF may also include a request for the new UPF to allocate a second tunnel endpoint for buffered DL data from the old l-UPF and to indicate via usage reporting end marker reception on this second tunnel. In this case, the UPF is instructed by the SMF to buffer the DL data it may receive at the same time from the UPF (PSA).

[0218] 6d. (step 618) New UPF (intermediate) to SMF: N4 Session Establishment Response.

[0219] The new intermediate UPF sends an N4 Session Establishment Response message to the SMF. The UPF provides DL CN Tunnel Info as requested by SMF in step 6c. The SMF starts a timer, to be used in step 22a to release the resource in old intermediate UPF if there is one.

[0220] 7a. (step 620) [Conditional] SMF to UPF (PSA): N4 Session Modification Request.

[0221] If the SMF selects a new UPF to act as intermediate UPF for the PDU Session, the SMF sends N4 Session Modification Request message to PDU Session Anchor UPF, providing DL Tunnel Info from new intermediate UPF. If the new intermediate UPF was added for the PDU Session, the UPF (PSA) begins to send the DL data to the new l-UPF as indicated in the DL CN Tunnel Info. The UPF (PSA) sends one or more "end marker" packets for each N9 tunnel to the old l-UPF immediately after switching the path to new l-UPF.

[0222] If the Service Request is triggered by the network and the SMF removes the old l-UPF but does not replace it with a new l-UPF, the SMF may also include a request for the UPF to allocate a second tunnel endpoint for buffered DL data from the old l-UPF and to indicate end marker reception on this second tunnel via usage reporting. In this case, the UPF (PSA) begins to buffer the DL data it may receive at the same time from the N6 interface. The UPF (PSA) sends one or more "end marker" packets for each N9 tunnel to the old l-UPF immediately after switching the path to (R)AN.

[0223] 7b. (step 622) The UPF (PSA) sends N4 Session Modification Response message to SMF.

[0224] If requested by SMF, the UPF (PSA) sends DL CN tunnel info for the old (intermediate) UPF to the SMF.

The SMF starts a timer, to be used in step 22a to release the resource in old intermediate UPF if there is one.

[0225] If the UPF that connects to RAN is the UPF (PSA) and if the SMF finds that the PDU Session is activated when receiving the Nsmf_PDUSession_UpdateSMContext Request in step 4 with Operation Type set to "UP activate" to indicate establishment of User Plane resources for the PDU Session(s), it deletes the AN Tunnel Info and initiates an N4 Session Modification procedure to remove Tunnel Info of AN in the UPF.

[0226] 8a. (step 624) [Conditional] SMF to old UPF (intermediate): N4 Session Modification Request (New UPF address, New UPF DL Tunnel ID)

[0227] If the service request is triggered by the network and the SMF removes the old (intermediate) UPF, the SMF sends the N4 Session Modification Request message to the old (intermediate) UPF, providing the DL Tunnel Info for the buffered DL data. If the SMF allocated new l-UPF, the DL Tunnel Info is from the new (intermediate) UPF acting as N3 terminating point. If the SMF did not allocate a new l-UPF, the DL Tunnel Info is from the new UPF (PSA) acting as N3 terminating point. The SMF starts a timer to monitor the forwarding tunnel as step 6d or 7b.

[0228] If the old l-UPF receives end marker packets and there is no associated tunnel to forward these packets, the old l-UPF discards the received end marker packets and does not send any Data Notification to SMF.

[0229] If the SMF find the PDU Session is activated when receiving the Nsmf_PDUSession_UpdateSMContext Request in step 4 with Operation Type set to "UP activate" to indicate establishment of User Plane resources for the PDU Session(s), it deletes the AN Tunnel Info and initiates an N4 Session Modification procedure to remove Tunnel Info of AN in the UPF.

[0230] 8b. (step 626) old UPF (intermediate) to SMF: N4 Session Modification Response

[0231] The old (intermediate) UPF sends N4 Session Modification Response message to SMF.

[0232] 9. (step 628) [Conditional] old UPF (intermediate) to new UPF (intermediate): buffered downlink data forwarding

[0233] If the l-UPF is changed and forwarding tunnel was established to the new l-UPF, the old (intermediate) UPF forwards its buffered data to the new (intermediate) UPF acting as N3 terminating point. If indicated by SMF in step 6c, the new l-UPF reports to SMF when end marker packet is received. Then the SMF initiates N4 Session Modification procedure to indicate the new l-UPF to send the buffered downlink packet(s) received from the UPF (PSA).

[0234] 10. (step 630) [Conditional] old UPF (intermediate) to UPF (PSA): buffered downlink data forwarding

[0235] If the old l-UPF is removed and no new l-UPF is assigned for the PDU Session and forwarding tunnel was established to the UPF (PSA), the old (intermediate) UPF forwards its buffered data to the UPF (PSA) acting as N3 Terminating Point. If indicated by SMF in step 7a, the UPF (PSA) reports to SMF when the end marker packet has been received. Then the SMF initiates N4 Session Modification procedure to request the UPF (PSA) to send the buffered DL data received from the N6 interface.

[0236] 11 . (step 632) [Conditional] SMF to AMF: Nsmf_PDUSession_UpdateSMContext Response (N2 SM information (PDU Session ID, QFI(s), QoS profile(s), CN N3 Tunnel Info, S-NSSAI, User Plane Security Enforcement, UE Integrity Protection Maximum Data Rate, RSN, PDU Session Pair ID), N1 SM Container, Cause) to the AMF. If the UPF that connects to RAN is the UPF (PSA), the N3 CN Tunnel Info is the UL CN Tunnel Info of the UPF (PSA). If the UPF that connects to RAN is the new intermediate UPF, the CN N3 Tunnel Info is the UL Tunnel Info of the intermediate UPF. [0237] For the PDU Session with redundant l-UPFs or with redundant N3 tunnels for URLLC, the two UL N3 CN Tunnel Info are included, the SMF also indicates the NG-RAN that one of the CN Tunnel Info is used as the redundancy tunnel of the PDU session as described in clause 5.33.2.2 of TS 23.501 [2],

[0238] The SMF shall send N1 SM Container and/or N2 SM Information to the AMF when applicable, (e.g. when the SMF was notified from the AMF that the access type of the PDU Session can be changed in step 4).

[0239] For a PDU Session that the SMF has determined to accept the activation of UP connection in step 5a or 5b, the SMF generates only N2 SM information and sends Nsmf_PDUSession_UpdateSMContext Response to the AMF to establish the User Plane(s). The N2 SM information contains information that the AMF shall provide to the NG-RAN. The SMF may indicate for each QoS Flow whether redundant transmission shall be performed by a corresponding redundant transmission indicator. If the SMF decided to change the PSA UPF for the SSC mode 3 PDU Session, the SMF triggers the change of SSC mode 3 PDU Session anchor as an independent procedure described in clause 4.3.5.2 or clause 4.3.5.3 after accepting the activation of UP of the PDU Session.

[0240] The SMF can reject the activation of UP of the PDU Session by including a cause in the Nsmf_PDUSession_UpdateSMContext Response. Following are some of the cases:

[0241] -If the PDU Session corresponds to a LADN and the UE is outside the area of availability of the LADN as described in step 5b;

[0242] -If the AMF notified the SMF that the UE is reachable only for regulatory prioritized service and the PDU Session to be activated is not for a regulatory prioritized service; or

[0243] -If the SMF decided to change the PSA UPF for the requested PDU Session as described in step 5b. In this case, after sending Nsmf_PDUSession_UpdateSMContext Response, the SMF triggers another procedure to instruct UE to re-establish the PDU Session as described in clause 4.3.5.1 for SSC mode 2.

[0244] -If the SMF received negative response in Step 6b due to UPF resource unavailability.

[0245] If the PDU Session has been assigned any EPS bearer ID, the SMF also includes the mapping between

EPS bearer ID(s) and QFI(s) into the N2 SM information to be sent to the NG-RAN.

[0246] The User Plane Security Enforcement information is determined by the SMF upon PDU session establishment as described in clause 5.10.3 of TS 23.501 [2], If the User Plane Security Enforcement information indicates that Integrity Protection is "Preferred" or "Required", the SMF also includes the UE Integrity Protection Maximum Data Rate.

[0247] The RSN and PDU Session Pair ID are included when applicable, as determined by the SMF during PDU Session establishment as described in clause 5.33.2.1 of TS 23.501 [2],

[0248] 12. (step 634) AMF to (R)AN: N2 Request (N2 SM information received from SMF, security context, Mobility

Restriction List, UE-AMBR, List of UE-Slice-MBR(s) (optional and for 3GPP access type only), MM NAS Service Accept, list of recommended cells I TAs I NG-RAN node identifiers, UE Radio Capability, Core Network Assistance Information, Tracing Requirements, UE Radio Capability ID, NEW: MCX 5GC Support Indication). The Allowed NSSAI for the Access Type for the UE is included in the N2 message. If the subscription information includes Tracing Requirements, the AMF includes Tracing Requirements in the N2 Request.

[0249] If the UE triggered the Service Request while in CM-CONNECTED state, only N2 SM information received from SMF and MM NAS Service Accept are included in the N2 Request.

[0250] If the Service Request procedure is triggered by the Network (as described in clause 4.2.3.3) while the UE is in CM-CONNECTED state, only N2 SM information received from SMF is included in the N2 Request. [0251] If the Service Request procedure is triggered by the Network (as described in clause 4.2.3.3) while the UE is in CM-IDLE state, only N2 SM information received from SMF and MM NAS Service Accept is included in the N2 Request.

[0252] For a UE that was in CM-IDLE state when the Service Request was triggered, the NG-RAN stores the Security Context. If the Service Request is not triggered by UE for a signalling connection only, RAN also stores QoS Information for the QoS Flows of the PDU Sessions that are activated and N3 Tunnel IDs in the UE RAN context and Mobility Restriction List (as described in clause 5.3.4.1 of TS 23.501 [2]) NEW: and MCX 5GC Support Indication. If N2 Request includes MCX 5GC Support Indication, including an indicator for 5GC support for MCX or not, RAN shall store it and use it for mobility reasons e.g. trigger MCX fallback. MCX Support Indication indicates separate support for each different MCX service i.e. MCPTT, MC Video and MC Data.

[0253] MM NAS Service Accept includes PDU Session status in AMF. Any local PDU Session Release during the Session Request procedure is indicated to the UE via the Session Status. PDU Session Reactivation Result is provided in Service Accept for the PDU sessions in the List Of PDU Sessions To Be Activated and the PDU Session in the List of Allowed PDU Sessions which has caused paging or NAS notification. If the PDU Session Reactivation Result of a PDU Session is failure, the cause of the failure is also provided.

[0254] If the AMF accepts the Paging Restriction Information sent from the UE, the AMF informs the UE about the acceptance/rejection of the requested Paging Restriction Information in the MM NAS Service Accept message.

[0255] If there are multiple PDU Sessions that involves multiple SMFs, AMF does not need to wait for responses from all SMFs in step 11 before it sends N2 SM information to the RAN. However, the AMF shall wait for all responses from the SMFs before it sends MM NAS Service Accept message to the UE.

[0256] AMF shall include at least one N2 SM information from SMF if this step is triggered for PDU Session User Plane activation. AMF may send additional N2 SM information from SMFs in separate N2 message(s) (e.g. N2 tunnel setup request), if there is any. Alternatively, if multiple SMFs are involved, the AMF may send one N2 Request message to (R)AN after all the Nsmf_PDUSession_UpdateSMContext Response service operations from all the SMFs associated with the UE are received.

[0257] If the NG-RAN node had provided the list of recommended cells I TAs I NG-RAN node identifiers during the AN Release procedure (see clause 4.2.6), the AMF shall include it in the N2 Request. The NG-RAN may use this information to allocate the RAN Notification Area when the NG-RAN decides to enable RRC Inactive state for the UE.

[0258] The AMF includes the UE's "RRC Inactive Assistance Information" as defined in clause 5.3.3.2.5 of TS 23.501 [2],

[0259] If the NG-RAN node does not support RAGS and the AMF have UE Radio Capability ID but not the UE Radio Capability information, then AMF will use Nucmf_UECapabilityManagement_Resolve to try to retrieve the corresponding UE Radio Capability information. [0260] If the NG-RAN node does not support RAGS, or the AMF does not have UE Radio Capability ID in UE context, the AMF shall include the UE Radio Capability information, if available, to the NG-RAN node as described in TS 23.501 [2], If the RAT Type is NB-loT then NB-loT specific UE Radio Access Capability Information is included instead, if available.

[0261] If AMF has UE Radio Capability ID in UE context valid for the PLMN the UE is currently in and the NG-RAN supports RAGS, the AMF signals the UE Radio Capability ID. If the NG-RAN node does not have mapping between the UE Radio Capability ID and the corresponding UE radio capabilities, it shall use the non-UE associated procedure described in TS 38.413 [10] to retrieve the mapping from the AMF.

[0262] The AMF may include the Core Network Assistance Information which includes Core Network assisted RAN parameters tuning and Core Network assisted RAN paging information as defined in TS 23.501 [2],

[0263] If the UE included support for restriction of use of Enhanced Coverage, the AMF sends Enhanced Coverage Restricted information to the (R)AN in the N2 message.

[0264] If the UE and the AMF have negotiated to enable MICO mode and the AMF uses the Extended connected timer, then the AMF provides the Extended Connected time value to NG-RAN (see clause 5.31 .7.3 of TS 23.501 [2]) in this step. The Extended Connected Time value indicates the minimum time the RAN should keep the UE in RRC- CONNECTED state regardless of inactivity.

[0265] If the AMF accepted MICO mode in the last registration procedure and knows there may be mobile terminated data or signalling pending, the AMF maintains the N2 connection for at least the Extended Connected Time as described in clause 5.31.7.3 of TS 23.501 [2] and provides the Extended Connected Time value to the RAN in N2 message with Service Accept message. The RAN should keep the UE in RRC-CONNECTED state for an Extended Connected Time period in order to ensure the downlink data and/or signalling is delivered to the UE.

[0266] If the RAN receives two CN Tunnel Info for a PDU session in step 11 for redundant transmission, RAN also allocates two AN Tunnel Info correspondingly and indicate to SMF one of the AN Tunnel Info is used as the redundancy tunnel of the PDU session as described in clause 5.33.2.2 of TS 23.501 [2], [0267] 13. (step 636) (R)AN to UE: The NG-RAN performs RRC Connection Reconfiguration with the UE depending on the QoS Information for all the QoS Flows of the PDU Sessions whose UP connections are activated and Data Radio Bearers. For a UE that was in CM-IDLE state, if the Service Request is not triggered by UE for a signalling connection only, the User Plane security is established at this step, which is described in detail in TS 38.331 [12] and TS 36.331 [16], For a UE that was in CM-IDLE state, if the Service Request is triggered by UE for a signalling connection only, AS security context may be established in this step, which is described in detail in TS 38.331 [12] and TS 36.331 [16].

[0268] If the N2 Request includes a NAS message, the NG-RAN forwards the NAS message to the UE. The UE locally deletes context of PDU Sessions that are not available in 5GC. [0269] NOTE 7:The reception of the Service Accept message does not imply the successful activation of the User Plane radio resources.

[0270] NOTE 8:lf not all the requested User Plane AN resources are successfully activated, see TS 38.413 [10],

[0271] After the User Plane radio resources are setup, the uplink data from the UE can now be forwarded to NG-

RAN. The NG-RAN sends the uplink data to the UPF address and Tunnel ID provided in the step 11.

[0272] If the NG-RAN cannot establish redundant user plane for the PDU Session as indicated by the RSN parameter and PDU Session Pair ID, the NG-RAN takes the decision on how to proceed with the PDU Session as described in TS 23.501 [2],

[0273] 14. (step 638) [Conditional] (R)AN to AMF: N2 Request Ack (List of PDU Sessions To Be Established with

N2 SM information (AN Tunnel Info, List of accepted QoS Flows for the PDU Sessions whose UP connections are activated, List of rejected QoS Flows for the PDU Sessions whose UP connections are activated), List of PDU Sessions that failed to be established with the failure cause given in the N2 SM information element).

[0274] The message may include N2 SM information(s), e.g. AN Tunnel Info. NG-RAN may respond N2 SM information with separate N2 message (e.g. N2 tunnel setup response) if AMF sends separate N2 message in step 11 . [0275] If multiple N2 SM information are included in the N2 Request message in step 12, the N2 Request Ack includes multiple N2 SM information and information to enable the AMF to associate the responses to relevant SMF. [0276] 15. (step 640) [Conditional] AMF to SMF: Nsmf_PDUSession_UpdateSMContext Request (N2 SM information, RAT Type, Access Type) per PDU Session to the SMF. The AMF determines Access Type and RAT Type, see clause 4.2.2.2.1.

[0277] If the AMF received N2 SM information (one or multiple) in step 14, then the AMF shall forward the N2 SM information to the relevant SMF per PDU Session ID. If the UE Time Zone has changed compared to the last reported UE Time Zone then the AMF shall include the UE Time Zone IE in this message.

[0278] If the PDU Session is moved from the non-3GPP access to 3GPP access (i.e. N3 tunnel for the PDU Session is established successfully), the SMF and AMF update associated access of the PDU Session. The UE updates associated access of the PDU Session when the user plane resource for the PDU Session is successfully established. [0279] Procedure for unpausing a charging pause initiated earlier is specified in clause 4.4.4.

[0280] If a PDU Session is rejected by the serving NG-RAN with an indication that the PDU Session was rejected because User Plane Security Enforcement is not supported in the serving NG-RAN and the User Plane Enforcement Policy indicates "Required" as described in clause 5.10.3 of TS 23.501 [2], the SMF shall trigger the release of this PDU Session. In all other cases of PDU Session rejection, the SMF can decide whether to release the PDU Session or to deactivate the UP connection of this PDU Session.

[0281] If some of the QoS Flows of a PDU Session are not accepted by the serving NG-RAN, the SMF shall initiate the PDU Session Modification procedure to remove the non-accepted QoS Flows from the PDU Session after this procedure is completed. [0282] 16. (step 642) [Optional] SMF to PCF: If dynamic PCC is deployed and if Policy Control Request Trigger condition(s) have been met (e.g. change of Access Type, change of UE location), performs SMF initiated SM Policy Modification procedure as defined in clause 4.16.5.1. The PCF may provide updated policies.

[0283] 17a. (step 644) [Conditional] SMF to new intermediate UPF: N4 Session Modification Request (AN Tunnel

Info and List of accepted QFI(s)).

[0284] If the SMF selected a new UPF to act as intermediate UPF for the PDU Session in step 5b, the SMF initiates a N4 Session Modification procedure to the new l-UPF and provides AN Tunnel Info. The Downlink Data from the new l-UPF can now be forwarded to NG-RAN and UE.

[0285] 17b. (step 646) [Conditional] UPF to SMF: N4 Session Modification Response.

[0286] 18a. (step 648) [Conditional] SMF to UPF (PSA): N4 Session Modification Request (AN Tunnel Info, List of rejected CoS Flows).

[0287] If a User Plane is to be setup or modified and after the modification there is no l-UPF, the SMF initiates a N4 Session Modification procedure to UPF (PSA) and provides AN Tunnel Info. The Downlink Data from the UPF (PSA) can now be forwarded to NG-RAN and UE.

[0288] For CoS Flows in the List of rejected CoS Flows, the SMF shall instruct the UPF to remove the rules (e.g. Packet Detection Rules etc.) which are associated with the CoS Flows.

[0289] If SMF decides to perform redundant transmission for one or more CoS Flows of the PDU, the SMF also indicates the UPF (PSA) to perform packet duplication for the CoS Flow(s) in downlink direction by forwarding rules.

[0290] If the PCC rule(s) are updated in step 16, the SMF may initiate a N4 Session Modification procedure to UPF (PSA) based on the updated PCC rule(s).

[0291] 18b. (step 650) [Conditional] UPF to SMF: N4 Session Modification Response.

[0292] 19. (step 652) [Conditional] SMF to AMF: Nsmf_PDUSession_UpdateSMContext Response.

[0293] 20a. (step 654) [Conditional] SMF to new UPF (intermediate): N4 Session Modification Request.

[0294] If forwarding tunnel has been established to the new l-UPF and if the timer SMF set for forwarding tunnel at step 8a has expired, SMF sends N4 Session modification request to new (intermediate) UPF acting as N3 terminating point to release the forwarding tunnel.

[0295] 20b. (step 656) [Conditional] new UPF (intermediate) to SMF: N4 Session modification response.

[0296] New (intermediate) UPF acting as N3 terminating point sends N4 Session Modification response to SMF.

[0297] 21a. (step 658) [Conditional] SMF to UPF (PSA): N4 Session Modification Request.

[0298] If forwarding tunnel has been established to the UPF (PSA) and if the timer SMF set for forwarding tunnel at step 7b has expired, SMF sends N4 Session modification request to UPF (PSA) acting as N3 Terminating Point to release the forwarding tunnel.

[0299] 21b. (step 660) [Conditional] UPF (PSA) to SMF: N4 Session Modification Response.

[0300] UPF (PSA) acting as N3 Terminating Point sends N4 Session Modification Response to SMF. [0301] 22a. (step 662) [Conditional] SMF to old UPF: N4 Session Modification Request or N4 Session Release

Request.

[0302] If the SMF decided to continue using the old UPF in step 5b, the SMF sends an N4 Session Modification Request, providing AN Tunnel Info.

[0303] If the SMF decided to select a new UPF to act as intermediate UPF in step 5b and the old UPF is not PSA UPF, the SMF initiates resource release, after timer in step 6b or 7b expires, by sending an N4 Session Release Request (Release Cause) to the old intermediate UPF.

[0304] 22b. (step 664) [Conditional] Old intermediate UPF to SMF: N4 Session Modification Response or N4

Session Release Response.

[0305] The old UPF acknowledges with an N4 Session Modification Response or N4 Session Release Response message to confirm the modification or release of resources.

[0306] For the mobility related events described in clause 4.15.4, the AMF invokes the Namf_EventExposure_Notify service operation after step 4.

[0307] Upon reception of the Namf_EventExposure_Notify with an indication that the UE is reachable, if the SMF has pending DL data the SMF invokes the Namf_Communication_N1 N2MessageTransfer service operation to the AMF to establish the User Plane(s) for the PDU Sessions, otherwise the SMF resumes sending DL data notifications to the AMF in the case of DL data.

[0308] Upon reception of the Namf_EventExposure_Notify with an indication that UE is reachable only for regulatory prioritized service, the SMF deactivates the PDU Session if the service of the PDU Session is not regulatory prioritized. For home routed roaming case, the V-SMF triggers the deactivation of the PDU Session, in addition, the H- SMF refrains from sending downlink signalling if the signalling is not related to regulatory prioritized service upon receiving the notification.

[0309] 3GPP TS 23.502 v17.5.0 (2022-06):

[0310] NOTE: The Registration procedures below are examples for idle mode mobility procedures that the proposed mechanism can be used for but is not limited to that. For instance, also intersystem change with idle mode mobility from 5G to 4G is also applicable.

[0311] 4.2.2.2 Registration procedures

[0312] 4.2.2.2.1 General

[0313] A UE needs to register with the network to get authorized to receive services, to enable mobility tracking and to enable reachability. The UE initiates the Registration procedure using one of the following Registration types:

- Initial Registration to the 5GS;

- Mobility Registration Update upon changing to a new Tracking Area (TA) outside the UE's Registration Area in both CM-CONNECTED and CM-IDLE state, or when the UE needs to update its capabilities or protocol parameters that are negotiated in Registration procedure with or without changing to a new TA, a change in the UE's Preferred Network Behaviour that would create an incompatibility with the Supported Network Behaviour provided by the serving AMF, or when the UE intends to retrieve LADN Information, or with NR satellite access upon changing to a suitable cell indicating multiple TAs for the RPLMN all of which are outside the UE's Registration Area in both CM-CONNECTED and CM-IDLE state, or when the Multi-USI M UE needs a new 5G- GUTI assignment; or

- Periodic Registration Update (due to a predefined time period of inactivity); or

- Emergency Registration; or

- Disaster Roaming Initial Registration, as specified in clause 5.40 of TS 23.501 [2]; or

- Disaster Roaming Mobility Registration Update, as specified in clause 5.40 of TS 23.501 [2]; or

- SNPN Onboarding Registration allows the UE to access an ON-SNPN for the purpose of provisioning the UE with SO-SNPN credentials to enable SO-SNPN access. SNPN Onboarding Registration is only applicable for registration with ON-SNPN i.e., when the UE uses PLMN credentials for accessing an ONN the UE initiates an Initial Registration. The SNPN Onboarding Registration is specified in clause 4.2.2.2.4.

NOTE 1 : With NR satellite access, more than one TAO can be indicated to a UE for each PLMN in any cell.

[0314] The General Registration call flow in clause 4.2.2.2.2 applies on all these Registration procedures, but the periodic registration need not include all parameters that are used in other registration cases.

[0315] The following are the cleartext lEs, as defined in TS 24.501 [25] that can be sent by the UE in the

Registration Request message if the UE has no NAS security context:

- Registration type;

- SUCI or 5G-GUTI or PEI;

- Security parameters;

- additional GUTI;

- 4G Tracking Area Update;

- the indication that the UE is moving from EPS;

- PLMN with Disaster Condition;

- if the UE is registering with an SNPN, the NID of the SNPN that assigned the 5G-GUTI.

NOTE 2: The NID is provided when the 5G-GUTI is assigned by another SNPN than the selected SNPN.

[0316] Aspects related to dual registration in 3GPP and non-3GPP access are described in clause 4.12. The general Registration call flow in clause 4.2.2.2.2 is also used for the case of registration in 3GPP access when the UE is already registered in a non-3GPP access and vice versa. Registration in 3GPP access when the UE is already registered in a non-3GPP access scenario may require an AMF change, as further detailed in clause 4.12.8.

[0317] The general Registration call flow in clause 4.2.2.2.2 is also used by UEs in limited service state (see TS

23.122 [22]) registering for emergency services only (referred to as Emergency Registration), see clause 5.16.4 of TS

23.501 [2], [0318] During the initial registration the PEI is obtained from the UE. If the PEI is needed (e.g. for EIR check), the AMF shall retrieve the PEI when it establishes the NAS security context with a Security Mode Command during initial registration. The AMF operator may check the PEI with an EIR. If the PEI was retrieved by the AMF (either from the UE or another AMF), AMF shall provide it to the UDM using Nudm_UECM_Registration in order to ensure that the UDM always has the latest PEI available e.g. for reporting event Change of SUPI-PEI association. The AMF passes the PEI to the UDM, to the SMF and the PCF. The UDM may store this data in UDR by Nudr_SDM_Update.

[0319] NOTE 3: The use of NSI ID in the 5GC is optional and depends on the deployment choices of the operator.

[0320] During the registration the Home Network (or Credentials Holder in case of access to an SNPN) can provide Steering of Roaming information to the UE via the AMF (i.e. a list of preferred PLMN/access technology combinations and/or Credentials Holder controlled prioritized lists of preferred SNPNs and GINs or HPLMN/Credentials Holder indication that 'no change of the above list(s) stored in the UE is needed'). The Home Network can include an indication for the UE to send an acknowledgement of the reception of this information. Details regarding the handling of Steering of Roaming information including how this information is managed between the AMF and the UE are defined in TS 23.122 [22].

[0321] The AMF determines Access Type and RAT Type as defined in clause 5.3.2.3 of TS 23.501 [2],

Figures 7A-7B

[0322] Figures 7A and 7B correspond to TS 23.502 Figure 4.2.2.2.2-1 of section 4.2.2.2.2 General Registration, and the following steps relate to Figures 7A and 7B.

[0323] 1 (702) UE to (R)AN: AN message (AN parameters, Registration Request (Registration type, SUCI or 5G-

GUTI or PEI, [last visited TAI (if available)], Security parameters, [Requested NSSAI], [Mapping Of Requested NSSAI], [Default Configured NSSAI Indication], [UE Radio Capability Update], [UE MM Core Network Capability], [PDU Session status], [List Of PDU Sessions To Be Activated], [Follow-on request], [MICO mode preference], [Requested Active Time], [Requested DRX parameters for E-UTRA and NR], [Requested DRX parameters for NB-loT], [extended idle mode DRX parameters], [LADN DNN(s) or Indicator Of Requesting LADN Information], [NAS message container], [Support for restriction of use of Enhanced Coverage], [Preferred Network Behaviour], [UE paging probability information], [Paging Subgrouping Support Indication], [UE Policy Container (the list of PSIs, indication of UE support for ANDSP and the operating system identifier)] and [UE Radio Capability ID], [Release Request indication], [Paging Restriction Information], PEI, [PLMN with Disaster Condition])).

[0324] NOTE 1 : The UE Policy Container and its usage is defined in TS 23.503 [20],

[0325] In the case of NG-RAN, the AN parameters include e.g. 5G-S-TMSI or GUAMI, the Selected PLMN ID (or PLMN ID and NID, see clause 5.30 of TS 23.501 [2]) and NSSAI information, the AN parameters also include Establishment cause. The Establishment cause provides the reason for requesting the establishment of an RRC connection. Whether and how the UE includes the NSSAI information as part of the AN parameters is dependent on the value of the Access Stratum Connection Establishment NSSAI Inclusion Mode parameter, as specified in clause 5.15.9 of TS 23.501 [2],

[0326] The AN parameters shall also include an I AB-I ndication if the UE is an lAB-node accessing 5GS.

[0327] The Registration type indicates if the UE wants to perform an Initial Registration (i.e. the UE is in RM-

DEREGISTERED state), a Mobility Registration Update (i.e. the UE is in RM-REGISTERED state and initiates a Registration procedure due to mobility or due to the UE needs to update its capabilities or protocol parameters, or to request a change of the set of network slices it is allowed to use), a Periodic Registration Update (i.e. the UE is in RM- REGISTERED state and initiates a Registration procedure due to the Periodic Registration Update timer expiry, see clause 4.2.2.2.1), an Emergency Registration (i.e. the UE is in limited service state), a Disaster Roaming Initial Registration, or a Disaster Roaming Mobility Registration Update.

[0328] When the UE is using E-UTRA, the UE indicates its support of CloT 5GS Optimisations, which is relevant for the AMF selection, in the RRC connection establishment signalling associated with the Registration Request.

[0329] When the UE is performing an Initial Registration or a Disaster Roaming Registration the UE shall indicate its UE identity in the Registration Request message as follows, listed in decreasing order of preference in the case of registration with a PLMN:

[0330] i)a 5G-GUTI mapped from an EPS GUTI, if the UE has a valid EPS GUTI.

[0331] ii)a native 5G-GUTI assigned by the PLMN to which the UE is attempting to register, if available;

[0332] iii)a native 5G-GUTI assigned by an equivalent PLMN to the PLMN to which the UE is attempting to register, if available;

[0333] iv)a native 5G-GUTI assigned by any other PLMN, if available.

[0334] NOTE 2:This can also be a 5G-GUTIs assigned via another access type.

[0335] v)Otherwise, the UE shall include its SUCI in the Registration Request as defined in TS 33.501 [15], [0336] If the UE is registering with an SNPN, when the UE is performing an Initial Registration the UE shall indicate its UE identity in the Registration Request message as follows, listed in decreasing order of preference:

[0337] i)a native 5G-GUTI assigned by the same SNPN to which the UE is attempting to register, if available;

[0338] ii)a native 5G-GUTI assigned by any other SNPN along with the NID of the SNPN that assigned the 5G-

GUTI, if available;

[0339] iii)Otherwise, the UE shall include its SUCI in the Registration Request as defined in TS 33.501 [15],

[0340] When the UE performing an Initial Registration has both a valid EPS GUTI and a native 5G-GUTI, the UE shall also indicate the native 5G-GUTI as Additional GUTI. If more than one native 5G-GUTIs are available, the UE shall select the 5G-GUTI in decreasing order of preference among items (ii)-(iv) in the list above.

[0341] The NAS message container shall be included if the UE is sending a Registration Request message as an Initial NAS message and the UE has a valid 5G NAS security context and the UE needs to send non-cleartext lEs, see clause 4.4.6 in TS 24.501 [25], If the UE does not need to send non-cleartext lEs, the UE shall send a Registration Request message without including the NAS message container.

[0342] If the UE does not have a valid 5G NAS security context, the UE shall send the Registration Request message without including the NAS message container. The UE shall include the entire Registration Request message (i.e. containing cleartext lEs and non-cleartext lEs) in the NAS message container that is sent as part of the Security Mode Complete message in step 9b.

[0343] When the UE is performing an Initial Registration (i.e. the UE is in RM-DEREGISTERED state) with a native 5G-GUTI then the UE shall indicate the related GUAMI information in the AN parameters. When the UE is performing an Initial Registration with its SUCI, the UE shall not indicate any GUAMI information in the AN parameters.

[0344] When the UE is performing an Initial Registration or a Mobility Registration and if CloT 5GS Optimisations are supported the UE shall indicate its Preferred Network Behaviour (see clause 5.31.2 of TS 23.501 [2]). If S1 mode is supported the UE's EPC Preferred Network Behaviour is included in the S1 UE network capabilities in the Registration Request message, see clause 8.2.6.1 of TS 24.501 [25],

[0345] For an Emergency Registration, the SUCI shall be included if the UE does not have a valid 5G-GUTI available; the PEI shall be included when the UE has no SUPI and no valid 5G-GUTI. In other cases, the 5G-GUTI is included and it indicates the last serving AMF.

[0346] The UE may provide the UE's usage setting based on its configuration as defined in clause 5.16.3.7 of TS 23.501 [2], The UE provides Requested NSSAI (as described in clause 5.15.5.2.1 of TS 23.501 [2] and, if the UE supports the subscription-based restrictions to simultaneous registration of network slices, also taking into account the NSSRG Information constraints as described in clause 5.15.12 of TS 23.501 [2] and, in the case of Initial Registration or Mobility Registration Update, the UE includes the Mapping Of Requested NSSAI (if available), which is the mapping of each S-NSSAI of the Requested NSSAI to the HPLMN S-NSSAIs, to ensure that the network is able to verify whether the S-NSSAI(s) in the Requested NSSAI are permitted based on the Subscribed S-NSSAIs. In the case of inter PLMN mobility, if the serving PLMN S-NSSAI(s) corresponding to the established PDU Session(s) are not present in the UE, the associated HPLMN S-NSSAI(s) associated with the established PDU Session(s) shall be provided in the Mapping Of Requested NSSAI as described in clause 5.15.5.2.1 TS 23.501 [2],

[0347] The UE includes the Default Configured NSSAI Indication if the UE is using a Default Configured NSSAI, as defined in TS 23.501 [2],

[0348] The UE may include UE paging probability information if it supports the assignment of WUS Assistance Information or AMF PEIPS Assistance Information from the AMF (see TS 23.501 [2]).

[0349] The UE may include Paging Subgrouping Support Indication as defined in TS 23.501 [2],

[0350] In the case of Mobility Registration Update, the UE includes in the List Of PDU Sessions To Be Activated the PDU Sessions for which there are pending uplink data. When the UE includes the List Of PDU Sessions To Be Activated, the UE shall indicate PDU Sessions only associated with the access the Registration Request is related to. As defined in TS 24.501 [25] the UE shall include always-on PDU Sessions which are accepted by the network in the List Of PDU Sessions To Be Activated even if there are no pending uplink data for those PDU Sessions.

[0351] NOTE 3:A PDU Session corresponding to a LADN is not included in the List Of PDU Sessions To Be Activated when the UE is outside the area of availability of the LADN

[0352] The UE MM Core Network Capability is provided by the UE and handled by AMF as defined in clause 5.4.4a of TS 23.501 [2], The UE includes in the UE MM Core Network Capability an indication if it supports Request Type flag "handover" for PDN connectivity request during the attach procedure as defined in clause 5.17.2.3.1 of TS 23.501 [2], If the UE supports 'Strictly Periodic Registration Timer Indication', the UE indicates its capability of 'Strictly Periodic Registration Timer Indication' in the UE MM Core Network Capability. If the UE supports CAG, the UE indicates its capability of "CAG supported" in the UE MM Core Network Capability. If the UE operating two or more USIMs, supports and intends to use one or more Multi-USIM feature(s), the UE indicates one or more Multi-USIM specific features described in clause 5.38 of TS 23.501 [2] in the UE MM Core Network Capability.

[0353] The UE may provide either the LADN DNN(s) or an Indication Of Requesting LADN Information as described in clause 5.6.5 of TS 23.501 [2],

[0354] If available, the last visited TAI shall be included in order to help the AMF produce Registration Area for the UE.

[0355] NOTE 4: With NR satellite access, the last visited TAI is determined as specified in clause 5.4.11.6 of

TS 23.501 [2]

[0356] The Security parameters are used for Authentication and integrity protection, see TS 33.501 [15], Requested NSSAI indicates the Network Slice Selection Assistance Information (as defined in clause 5.15 of TS 23.501 [2]). The PDU Session status indicates the previously established PDU Sessions in the UE. When the UE is connected to the two AMFs belonging to different PLMN via 3GPP access and non-3GPP access then the PDU Session status indicates the established PDU Session of the current PLMN in the UE.

[0357] The Follow-on request is included when the UE has pending uplink signalling and the UE doesn't include List Of PDU Sessions To Be Activated, or the Registration type indicates the UE wants to perform an Emergency Registration. In Initial Registration and Mobility Registration Update, UE provides the UE Requested DRX parameters, as defined in clause 5.4.5 of TS 23.501 [2], The UE may provide the extended idle mode DRX parameters as defined in clause 5.31.7.2 of TS 23.501 [2] to request extended idle mode DRX.

[0358] The UE provides UE Radio Capability Update indication as described in TS 23.501 [2],

[0359] The UE includes the MICO mode preference and optionally a Requested Active Time value if the UE wants to use MICO Mode with Active Time.

[0360] The UE may indicate its Service Gap Control Capability in the UE MM Core Network Capability, see clause 5.31.16 of TS 23.501 [2], [0361] For a UE with a running Service Gap timer in the UE, the UE shall not set Follow-on Request indication or Uplink data status in the Registration Request message (see clause 5.31.16 of TS 23.501 [2]), except for network access for regulatory prioritized services like Emergency services or exception reporting.

[0362] If UE supports RAGS and has been assigned UE Radio Capability ID(s), the UE shall indicate a UE Radio Capability ID as defined in clause 5.4.4.1a of TS 23.501 [2] as non-cleartext IE.

[0363] The PEI may be retrieved in initial registration from the UE as described in clause 4.2.2.2.1.

[0364] If a UE supports the subscription-based restrictions to simultaneous registration of network slices feature, it includes the NSSRG handling support indication in the UE 5GMM Core Network Capability according to clause 5.15.12 of TS 23.501 [2], The AMF stores whether the UE supports this feature in the UE context.

[0365] When a Multi-USIM UE wants to enter CM-IDLE state immediately e.g. after having performed mobility or periodic registration, it includes the Release Request indication and optionally provides Paging Restriction Information. [0366] When the UE is performing a Disaster Roaming Registration, the UE may indicate the PLMN with Disaster Condition for the cases as defined in TS 24.501 [25],

[0367] 2(704). If a 5G-S-TMSI or GUAMI is not included or the 5G-S-TMSI or GUAMI does not indicate a valid AMF the (R)AN, based on (R)AT and Requested NSSAI, if available, selects an AMF

[0368] The (R)AN selects an AMF as described in clause 6.3.5 of TS 23.501 [2], If UE is in CM-CONNECTED state, the (R)AN can forward the Registration Request message to the AMF based on the N2 connection of the UE. [0369] If the (R)AN cannot select an appropriate AMF, it forwards the Registration Request to an AMF which has been configured, in (R)AN, to perform AMF selection.

[0370] 3 (706).(R)AN to new AMF: N2 message (N2 parameters, Registration Request (as described in step 1) and

[LTE-M Indication],

[0371] When NG-RAN is used, the N2 parameters include the Selected PLMN ID (or PLMN ID and NID, see clause 5.30 of TS 23.501 [2]), Location Information and Cell Identity related to the cell in which the UE is camping, UE Context Request which indicates that a UE context including security information needs to be setup at the NG-RAN.

[0372] When NG-RAN is used, the N2 parameters shall also include the Establishment cause and I AB-I ndication if the indication is received in AN parameters in step 1.

[0373] Mapping Of Requested NSSAI is provided only if available.

[0374] If the Registration type indicated by the UE is Periodic Registration Update, then steps 4 to 19 may be omitted.

[0375] When the Establishment cause is associated with priority services (e.g. MPS, MCS), the AMF includes a Message Priority header to indicate priority information. Other NFs relay the priority information by including the Message Priority header in service-based interfaces, as specified in TS 29.500 [17], [0376] The RAT Type the UE is using is determined (see clause 4.2.2.2.1) and based on it the AMF determines whether the UE is performing Inter-RAT mobility to or from NB-loT. If the AMF receives the LTE M indication, then it considers that the RAT Type is LTE-M and stores the LTE-M Indication in UE Context.

[0377] If a UE includes a Preferred Network Behaviour, this defines the Network Behaviour the UE supports and is expecting to be available in the network as defined in clause 5.31.2 of TS 23.501 [2],

[0378] If the UE has included the Preferred Network Behaviour and what the UE indicated it supports in Preferred Network Behaviour is incompatible with the network support, the AMF shall reject the Registration Request with an appropriate cause value (e.g. one that avoids retries on this PLMN).

[0379] If there is a Service Gap timer running in the UE Context in AMF for the UE and Follow-on Request indication or Uplink data status is included in the Registration Request message, the AMF shall ignore the Follow-on Request indication and Uplink data status and not perform any of the actions related to the status.

[0380] If the UE has included a UE Radio Capability ID in step 1 and the AMF supports RAGS, the AMF stores the Radio Capability ID in UE context.

[0381] For NR satellite access, the AMF may verify the UE location and determine whether the PLMN is allowed to operate at the UE location, as described in clause 5.4.11.4 of TS 23.501 [2], If the UE receives a Registration Reject message with cause value indicating that the PLMN is not allowed to operate at the present UE location, the UE shall attempt to select a PLMN as specified in TS 23.122 [22],

[0382] For a Disaster Roaming Registration, based on the ULI (including Cell ID) received from the NG-RAN, the PLMN with Disaster Condition derived from the UE's 5G-GUTI, derived from the UE's SUCI or indicated by the UE and the local configuration, the AMF determines if Disaster Roaming service can be provided. If the current location is not subject to Disaster Roaming service or the Disaster Roaming service is not provided to the PLMN with Disaster Condition derived from the UE's 5G-GUTI, derived from the UE's SUCI or indicated by UE, then the AMF should reject the Registration Request indicating a suitable Cause value.

[0383] 4. (708) [Conditional] new AMF to old AMF: Namf_Communication_UEContextTransfer (complete

Registration Request) or new AMF to UDSF: Nudsf_Unstructured Data Management_Query().

[0384] The new AMF determines the old AMF using the UE's 5G-GUTI. If the new AMF received an NID in the Registration request, it determines that the 5G-GUTI was assigned by an SNPN and determines the old AMF using the 5G-GUTI and NID of the SNPN.

[0385] (With UDSF Deployment): If the UE's 5G-GUTI was included in the Registration Request and the serving AMF has changed since last Registration procedure, new AMF and old AMF are in the same AMF Set and UDSF is deployed, the new AMF retrieves the stored UE's SUPI and UE context directly from the UDSF using Nudsf_UnstructuredDataManagement_Query service operation or they can share stored UE context via implementation specific means if UDSF is not deployed. This includes also event subscription information by each NF consumer for the given UE. In this case, the new AMF uses integrity protected complete Registration request NAS message to perform and verify integrity protection.

[0386] (Without UDSF Deployment): If the UE's 5G-GUTI was included in the Registration Request and the serving AMF has changed since last Registration procedure, the new AMF may invoke the Namf_Communication_UEContextTransfer service operation on the old AMF including the complete Registration Request NAS message, which may be integrity protected, as well as the Access Type, to request the UE's SUPI and UE Context. See clause 5.2.2.2.2 for details of this service operation. In this case, the old AMF uses either 5G-GUTI and the integrity protected complete Registration request NAS message, or the SUPI and an indication that the UE is validated from the new AMF, to verify integrity protection if the context transfer service operation invocation corresponds to the UE requested. The old AMF also transfers the event subscriptions information by each NF consumer, for the UE, to the new AMF. If the old AMF has not yet reported a non-zero MO Exception Data Counter to the (H-)SMF, the Context Response also includes the MO Exception Data Counter.

[0387] If the old AMF has PDU Sessions for another access type (different from the Access Type indicated in this step) and if the old AMF determines that there is no possibility for relocating the N2 interface to the new AMF, the old AMF returns UE's SUPI and indicates that the Registration Request has been validated for integrity protection, but does not include the rest of the UE context.

[0388] For inter PLMN mobility, UE Context information includes HPLMN S-NSSAIs corresponding to the Allowed NSSAI for each Access Type, without Allowed NSSAI of old PLMN.

[0389] NOTE 5:The new AMF Sets the indication that the UE is validated according to step 9a, if the new AMF has performed successful UE authentication after previous integrity check failure in the old AMF.

[0390] NOTE 6:The NF consumers do not need to subscribe for the events once again with the new AMF after the UE is successfully registered with the new AMF.

[0391] If the new AMF has already received UE contexts from the old AMF during handover procedure, then step 4,5 and 10 shall be skipped.

[0392] For an Emergency Registration, if the UE identifies itself with a 5G-GUTI that is not known to the AMF, steps 4 and 5 are skipped and the AMF immediately requests the SUPI from the UE. If the UE identifies itself with PEI, the SUPI request shall be skipped. Allowing Emergency Registration without a user identity is dependent on local regulations.

[0393] 5. (710) [Conditional] old AMF to new AMF: Response to Namf_Communication_UEContextTransfer (SUPI,

UE Context in AMF (as per Table 5.2.2.2.2-1) NEW: including MCX 5GC Support Indication) or UDSF to new AMF: Nudsf_Unstructured Data Management_Query(). The old AMF may start an implementation specific (guard) timer for the UE context.

[0394] If the UDSF was queried in step 4, the UDSF responds to the new AMF for the Nudsf_Unstructured Data Management_Query invocation with the related contexts including established PDU Sessions, the old AMF includes SMF information DNN, S-NSSAI(s) and PDU Session ID, active NGAP UE-TNLA bindings to N3IWF/TNGF/W-AGF, the old AMF includes information about the NGAP UE-TNLA bindings. If the Old AMF was queried in step 4, Old AMF responds to the new AMF for the Namf_Communication_UEContextTransfer invocation by including the UE's SUPI and UE Context.

[0395] NEW: Old AMF includes MCX 5GC Support Indication from the UE context, if available. If Namf_Communication_UEContextTransfer includes MCX 5GC Support Indication, including an indicator for 5GC support for MCX or not, new AMF stores it in the UE context and forwards it further to RAN. MCX Support Indication indicates separate support for each different MCX service i.e. MCPTT, MC Video and MC Data.

[0396] If old AMF holds information about established PDU Session(s) and it is not an Initial Registration, the old AMF includes SMF information, DNN(s), S-NSSAI(s) and PDU Session ID(s).

[0397] If old AMF holds UE context established via N3IWF, W-AGF or TNGF, the old AMF includes the CM state via N3IWF, W-AGF or TNGF. If the UE is in CM-CONNECTED state via N3I WF, W-AGF or TNGF, the old AMF includes information about the NGAP UE-TNLA bindings.

[0398] If old AMF fails the integrity check of the Registration Request NAS message, the old AMF shall indicate the integrity check failure. If the new AMF is configured to allow emergency services for unauthenticated UE, the new AMF behaves as follows:

[0399] -If the UE has only an emergency PDU Session, the AMF either skips the authentication and security procedure or accepts that the authentication may fail and continues the Mobility Registration Update procedure; or [0400] -If the UE has both emergency and non-emergency PDU Sessions and authentication fails, the AMF continues the Mobility Registration Update procedure and deactivates all the non-emergency PDU Sessions as specified in clause 4.3.4.2.

[0401] NOTE 7:The new AMF can determine if a PDU Session is used for emergency service by checking whether the DNN matches the emergency DNN.

[0402] If old AMF holds information about AM Policy Association and the information about UE Policy Association (i.e. the Policy Control Request Trigger for updating UE Policy as defined in TS 23.503 [20]), the old AMF includes the information about the AM Policy Association, the UE Policy Association and PCF ID. In the roaming case, V-PCF ID and H-PCF ID are included.

[0403] If old AMF was a consumer of UE related NWDAF services, the old AMF includes information about active analytics subscriptions, i.e. the Subscription Correlation ID, NWDAF identifier (i.e. Instance ID or Set ID), Analytics ID(s) and associated Analytics specific data in the Namf_Communication_UEContextTransfer response. Usage of the analytics information by the new AMF is specified in TS 23.288 [50],

[0404] During inter PLMN mobility, the handling of the UE Radio Capability ID in the new AMF is as defined in TS 23.501 [2], [0405] NOTE 8:When new AMF uses UDSF for context retrieval, interactions between old AMF, new AMF and UDSF due to UE signalling on old AMF at the same time is implementation issue.

[0406] 6 (712) [Conditional] new AMF to UE: Identity Request ().

[0407] If the SUCI is not provided by the UE nor retrieved from the old AMF the Identity Request procedure is initiated by AMF sending an Identity Request message to the UE requesting the SUCI.

[0408] 7 (714) [Conditional] UE to new AMF: Identity Response ().

[0409] The UE responds with an Identity Response message including the SUCI. The UE derives the SUCI by using the provisioned public key of the HPLMN, as specified in TS 33.501 [15],

[0410] 8. (716) The AMF may decide to initiate UE authentication by invoking an AUSF. In that case, the AMF selects an AUSF based on SUPI or SUCI, as described in clause 6.3.4 of TS 23.501 [2],

[0411] If the AMF is configured to support Emergency Registration for unauthenticated SUPIs and the UE indicated Registration type Emergency Registration, the AMF skips the authentication or the AMF accepts that the authentication may fail and continues the Registration procedure.

[0412] 9a. (718) If authentication is required, the AMF requests it from the AUSF; if Tracing Requirements about the UE are available at the AMF, the AMF provides Tracing Requirements in its request to AUSF. For a Disaster Roaming Registration, the AMF may provide the indication of Disaster Roaming service in its request to AUSF. Upon request from the AMF, the AUSF shall execute authentication of the UE. The authentication is performed as described in TS 33.501 [15], The AUSF selects a UDM as described in clause 6.3.8 of TS 23.501 [2] and gets the authentication data from UDM. [0413] The AUSF may provide the indication of Disaster Roaming service to UDM if the indication is received from AMF. For a Disaster Roaming Registration, the AUSF executes authentication of the UE based on the local policy and/or local configuration as specified in clause 5.40.4 of TS 23.501 [2] and in TS 33.501 [29],

[0414] Once the UE has been authenticated the AUSF provides relevant security related information to the AMF. If the AMF provided a SUCI to AUSF, the AUSF shall return the SUPI to AMF only after the authentication is successful.

[0415] After successful authentication in new AMF, which is triggered by the integrity check failure in old AMF at step 5, the new AMF invokes step 4 above again and indicates that the UE is validated (i.e. through the reason parameter as specified in clause 5.2.2.2.2).

[0416] 9b (718) If NAS security context does not exist, the NAS security initiation is performed as described in TS 33.501 [15], If the UE had no NAS security context in step 1, the UE includes the full Registration Request message as defined in TS 24.501 [25],

[0417] The AMF decides if the Registration Request needs to be rerouted as described in clause 4.2.2.2.3, where the initial AMF refers to the AMF.

[0418] 9c.The AMF initiates NGAP procedure to provide the 5G-AN with security context as specified in TS 38.413 [10] if the 5G-AN had requested for UE Context. Also, if the AMF decides that EPS fallback is supported (e.g. based on UE capability to support Request Type flag "handover" for PDN connectivity request during the attach procedure as defined in clause 5.17.2.3.1 of TS 23.501 [2], subscription data and local policy), the AMF shall send an indication "Redirection for EPS fallback for voice is possible" towards 5G-AN as specified in TS 38.413 [10], Otherwise, the AMF indicates "Redirection for EPS fallback for voice is not possible". In addition, if Tracing Requirements about the UE are available at the AMF, the AMF provides the 5G-AN with Tracing Requirements in the NGAP procedure.

[0419] 9d.The 5G-AN stores the security context and acknowledges to the AMF. The 5G-AN uses the security context to protect the messages exchanged with the UE as described in TS 33.501 [15],

[0420] 10. (720) [Conditional] new AMF to old AMF: Namf_Communication_RegistrationStatusUpdate (PDU

Session ID(s) to be released e.g. due to slice not supported).

[0421] If the AMF has changed the new AMF informs the old AMF that the registration of the UE in the new AMF is completed by invoking the Namf_Communication_RegistrationStatusUpdate service operation.

[0422] If the authentication/security procedure fails, then the Registration shall be rejected and the new AMF invokes the Namf_Communication_RegistrationStatusUpdate service operation with a reject indication towards the old AMF. The old AMF continues as if the UE context transfer service operation was never received.

[0423] The new AMF determines the PDU Session(s) that cannot be supported in the new Registration Area in the cases below:

[0424] -If one or more of the S-NSSAIs used in the old Registration Area cannot be served in the target Registration Area.

[0425] -When continuity of the PDU Session(s) cannot be supported between networks (e.g. SNPN-SNPN mobility, inter-PLMN mobility where no HR agreement exists).

[0426] If any of the cases is met, the new AMF invokes the Namf_Communication_RegistrationStatusUpdate service operation including the rejected PDU Session ID towards the old AMF. Then the new AMF modifies the PDU Session Status correspondingly. The old AMF informs the corresponding SMF(s) to locally release the UE's SM context by invoking the Nsmf_PDUSession_ReleaseSMContext service operation.

[0427] If new AMF received in the UE context transfer in step 5 the information about the AM Policy Association and the UE Policy Association and decides, based on local policies, not to use the PCF(s) identified by the PCF ID(s) for the AM Policy Association and the UE Policy Association, then it will inform the old AMF that the AM Policy Association and the UE Policy Association in the UE context is not used any longer and then the PCF selection is performed in step 15.

[0428] If the new AMF received in the UE context transfer in step 5 the information about UE related analytics subscription(s), the new AMF may take over the analytics subscription(s) from the old AMF. Otherwise, if the new AMF instead determines to create new analytics subscription(s), it informs the old AMF about the analytics subscriptions (identified by their Subscription Correlation ID) that are not needed any longer and the old AMF may now unsubscribe those NWDAF analytics subscriptions for the UE according to TS 23.288 [50], [0429] 11 . (722) [Conditional] new AMF to UE: Identity Request/Response (PEI). [0430] If the PEI was not provided by the UE nor retrieved from the old AMF the Identity Request procedure is initiated by AMF sending an Identity Request message to the UE to retrieve the PEI. The PEI shall be transferred encrypted unless the UE performs Emergency Registration and cannot be authenticated.

[0431] For an Emergency Registration, the UE may have included the PEI in the Registration Request. If so, the PEI retrieval is skipped.

[0432] If the UE supports RAGS as indicated in UE MM Core Network Capability, the AMF shall use the PEI of the UE to obtain the I MEI/TAC for the purpose of RAGS operation.

[0433] 12. (724) Optionally the new AMF initiates ME identity check by invoking the N5g- eir_EquipmentldentityCheck_Get service operation (see clause 5.2.4.2.2).

[0434] The PEI check is performed as described in clause 4.7.

[0435] For an Emergency Registration, if the PEI is blocked, operator policies determine whether the Emergency Registration procedure continues or is stopped.

[0436] 13. (726) If step 14 is to be performed, the new AMF, based on the SUPI, selects a UDM, then UDM may select a UDR instance. See clause 6.3.9 of TS 23.501 [2],

[0437] The AMF selects a UDM as described in clause 6.3.8 of TS 23.501 [2],

[0438] 14a-c. (728-732)lf the AMF has changed since the last Registration procedure, if UE Registration type is

Initial Registration or Emergency Registration, or if the UE provides a SUPI which does not refer to a valid context in the AMF, or if the UE registers to the same AMF it has already registered to a non-3GPP access (i.e. the UE is registered over a non-3GPP access and initiates this Registration procedure to add a 3GPP access), the new AMF registers with the UDM using Nudm_UECM_Registration for the access to be registered (and subscribes to be notified when the UDM deregisters this AMF). The UDM based on the "Registration Type" in the Nudm_UECM_Registration request, can act on SoR information according to TS 23.122 [22], In this case, if the AMF does not have event exposure subscription information for this UE, the AMF indicates it to UDM. Then, if the UDM has existing applicable event exposure subscriptions for events detected in AMF for this UE or for any of the groups this UE belongs to (possibly retrieved from UDR), UDM invokes the Namf_EventExposure_Subscribe service for recreating the event exposure subscriptions.

[0439] The AMF provides the "Homogenous Support of IMS Voice over PS Sessions" indication (see clause 5.16.3.3 of TS 23.501 [2]) to the UDM. The "Homogenous Support of IMS Voice over PS Sessions" indication shall not be included unless the AMF has completed its evaluation of the support of "IMS Voice over PS Session" as specified in clause 5.16.3.2 of TS 23.501 [2],

[0440] During initial Registration, if the AMF and UE supports SRVCC from NG-RAN to UTRAN the AMF provides UDM with the UE SRVCC capability.

[0441] If the AMF determines that only the UE SRVCC capability has changed, the AMF sends UE SRVCC capability to the UDM. [0442] NOTE 9:At this step, it is possible that the AMF does not have all the information needed to determine the setting of the IMS Voice over PS Session Supported indication for this UE (see clause 5.16.3.2 of TS 23.501 [2]). Hence the AMF can send the "Homogenous Support of IMS Voice over PS Sessions" later on in this procedure.

[0443] After AMF has successfully completed the Nudm_UECM_Registration operation and if the AMF does not have subscription data for the UE, the AMF retrieves the Access and Mobility Subscription data, SMF Selection Subscription data, UE context in SMF data and LCS mobile origination using Nudm_SDM_Get. If the AMF already has subscription data for the UE but the SoR Update Indicator in the UE context requires the AMF to retrieve SoR information depending on the NAS Registration Type ("Initial Registration" or "Emergency Registration") (see Annex C of TS 23.122 [22]), the AMF retrieves the Steering of Roaming information using Nudm_SDM_Get. This requires that UDM may retrieve this information from UDR by Nudr_DM_Query. After a successful response is received, the AMF subscribes to be notified using Nudm_SDM_Subscribe when the data requested is modified, UDM may subscribe to UDR by Nudr_DM_Subscribe. The GPSI is provided to the AMF in the Access and Mobility Subscription data from the UDM if the GPSI is available in the UE subscription data. The UDM may provide indication that the subscription data for network slicing is updated for the UE. If the UE is subscribed to MPS in the serving PLMN, "MPS priority" is included in the Access and Mobility Subscription data provided to the AMF. If the UE is subscribed to MCX in the serving PLMN, "MCX priority" is included in the Access and Mobility Subscription data provided to the AMF. The UDM also provides the lAB-Operation allowed indication to AMF as part of the Access and Mobility Subscription data. The AMF shall trigger the setup of the UE context in NG-RAN, or modification of the UE context in NG-RAN if the initial setup is at step 9c, including an indication that the lAB-node is authorized.

[0444] For a Disaster Roaming Registration, the AMF may provide the indication of Disaster Roaming service to the UDM. The UDM provides the subscription data for a Disaster Roaming service to the AMF based on the local policy and/or the local configuration as specified in clause 5.40.4 of TS 23.501 [2], [0445] The AMF provides MINT support indication via Nudm_UECM_Registration towards UDM, if UE includes the MINT support indication in the 5GMM capability as specified in clause 5.40.2 of TS 23.501 [2] or if the MINT support indication in the 5GMM capability is changed.

[0446] If the AMF receives a priority indication (e.g. MPS, MCX) as part of the Access and Mobility Subscription data, but the UE did not provide an Establishment cause associated with priority services, the AMF shall include a Message Priority header to indicate priority information for all subsequent messages. Other NFs relay the priority information by including the Message Priority header in service-based interfaces, as specified in TS 29.500 [17], [0447] The new AMF provides the Access Type it serves for the UE to the UDM and the Access Type is set to "3GPP access". The UDM stores the associated Access Type together with the serving AMF and does not remove the AMF identity associated to the other Access Type if any. The UDM may store in UDR information provided at the AMF registration by Nudr_DM_Update. [0448] If the UE was registered in the old AMF for an access and the old and the new AMFs are in the same PLMN, the new AMF sends a separate/independent Nudm_UECM_Registration to update UDM with Access Type set to access used in the old AMF, after the old AMF relocation is successfully completed.

[0449] The new AMF creates an UE context for the UE after getting the Access and Mobility Subscription data from the UDM. The Access and Mobility Subscription data includes whether the UE is allowed to include NSSAI in the 3GPP access RRC Connection Establishment in clear text. The Access and Mobility Subscription data may include Enhanced Coverage Restricted information. If received from the UDM and the UE included support for restriction of use of Enhanced Coverage in step 1, the AMF determines whether Enhanced Coverage is restricted or not for the UE as specified in clause 5.31.12 of TS 23.501 [2] and stores the updated Enhanced Coverage Restricted information in the UE context.

[0450] The Access and Mobility Subscription data may include the NB-loT UE Priority.

[0451] The subscription data may contain Service Gap Time parameter. If received from the UDM, the AMF stores this Service Gap Time in the UE Context in AMF for the UE.

[0452] For an Emergency Registration in which the UE was not successfully authenticated, the AMF shall not register with the UDM.

[0453] The AMF enforces the Mobility Restrictions as specified in clause 5.3.4.1.1 of TS 23.501 [2], For an Emergency Registration, the AMF shall not check for Mobility Restrictions, access restrictions, regional restrictions or subscription restrictions. For an Emergency Registration, the AMF shall ignore any unsuccessful registration response from UDM and continue with the Registration procedure.

[0454] NOTE 10:The AMF can, instead of the Nudm_SDM_Get service operation, use the Nudm_SDM_Subscribe service operation with an Immediate Report Indication that triggers the UDM to immediately return the subscribed data if the corresponding feature is supported by both the AMF and the UDM.

[0455] 14d. (734) When the UDM stores the associated Access Type (e.g. 3GPP) together with the serving AMF as indicated in step 14a, it will cause the UDM to initiate a Nudm_UECM_DeregistrationNotification (see clause 5.2.3.2.2) to the old AMF corresponding to the same (e.g. 3GPP) access, if one exists. If the timer started in step 5 is not running, the old AMF may remove the UE context for the same Access Type. Otherwise, the AMF may remove UE context for the same Access Type when the timer expires. If the serving NF removal reason indicated by the UDM is Initial Registration, then, as described in clause 4.2.2.3.2, the old AMF invokes the Nsmf_PDUSession_ReleaseSMContext (SM Context ID) service operation towards all the associated SMF(s) of the UE to notify that the UE is deregistered from old AMF for the same Access Type. The SMF(s) shall release the PDU Session on getting this notification.

[0456] If the old AMF has established an AM Policy Association and a UE Policy Association with the PCF(s) and the old AMF did not transfer the PCF I D(s) to the new AMF (e.g. new AMF is in different PLMN), the old AMF performs an AMF-initiated Policy Association Termination procedure, as defined in clause 4.16.3.2 and performs an AMF-initiated UE Policy Association Termination procedure, as defined in clause 4.16.13.1. In addition, if the old AMF transferred the PCF ID(s) in the UE context but the new AMF informed in step 10 that the AM Policy Association information and UE Policy Association information in the UE context will not be used then the old AMF performs an AMF-initiated Policy Association Termination procedure, as defined in clause 4.16.3.2 and performs an AMF-initiated UE Policy Association Termination procedure, as defined in clause 4.16.13.1.

[0457] If the old AMF has an N2 connection for that UE (e.g. because the UE was in RRC Inactive state but has now moved to E-UTRAN or moved to an area not served by the old AMF), the old AMF shall perform AN Release (see clause 4.2.6) with a cause value that indicates that the UE has already locally released the NG-RAN's RRC Connection. [0458] If the UE context in the old AMF contains an Allowed NSSAI including one or more S-NSSAI(s) subject to NSAC, the old AMF upon receipt of the Nudm_UECM_DeregistrationNotification from the UDM, sends an update request message for each S-NSSAI subject to NSAC to the corresponding NSACF(s) with update flag parameter set to decrease (see clause 4.2.11.2).

[0459] At the end of registration procedure, the AMF may initiate synchronization of event exposure subscriptions with the UDM if the AMF does not indicate unavailability of event exposure subscription in step 14a.

[0460] NOTE 11 : The AMF can initiate synchronization with UDM even if events are available in the UE context (e.g. as received from old AMF) at any given time and based on local policy. This can be done during subscription change related event.

[0461] 14e. [Conditional] If old AMF does not have UE context for another access type (i.e. non-3GPP access), the

Old AMF unsubscribes with the UDM for subscription data using Nudm_SDM_unsubscribe.

[0462] 15. (738) If the AMF decides to initiate PCF communication, the AMF acts as follows.

[0463] If the new AMF decides to use the (V-)PCF identified by the (V-)PCF ID included in UE context from the old

AMF in step 5, the AMF contacts the (V-)PCF identified by the (V-)PCF ID to obtain policy. If the AMF decides to perform PCF discovery and selection and the AMF selects a (V)-PCF and may select an H-PCF (for roaming scenario) as described in clause 6.3.7.1 of TS 23.501 [2] and according to the V-NRF to H-NRF interaction described in clause 4.3.2.2.3.3.

[0464] 16. (740) [Optional] new AMF performs an AM Policy Association Establishment/Modification. For an

Emergency Registration, this step is skipped.

[0465] If the new AMF selects a new (V-)PCF in step 15, the new AMF performs AM Policy Association Establishment with the selected (V-)PCF as defined in clause 4.16.1.2.

[0466] If the (V-)PCF identified by the (V-)PCF ID included in UE context from the old AMF is used, the new AMF performs AM Policy Association Modification with the (V-)PCF as defined in clause 4.16.2.1.2.

[0467] If the AMF notifies the Mobility Restrictions (e.g. UE location) to the PCF for adjustment, or if the PCF updates the Mobility Restrictions itself due to some conditions (e.g. application in use, time and date), the PCF shall provide the updated Mobility Restrictions to the AMF. If the subscription information includes Tracing Requirements, the AMF provides the PCF with Tracing Requirements. [0468] If the AMF supports DNN replacement, the AMF provides the PCF with the Allowed NSSAI and, if available, the Mapping Of Allowed NSSAI.

[0469] If the PCF supports DNN replacement, the PCF provides the AMF with triggers for DNN replacement.

[0470] 17. (742) [Conditional] AMF to SMF: Nsmf_PDUSession_UpdateSMContext ()■

[0471] For an Emergency Registered UE (see TS 23.501 [2]), this step is applied when the Registration Type is Mobility Registration Update.

[0472] The AMF invokes the Nsmf_PDUSession_UpdateSMContext (see clause 5.2.8.2.6) in the following scenario(s):

[0473] -If the List Of PDU Sessions To Be Activated is included in the Registration Request in step 1, the AMF sends Nsmf_PDUSession_UpdateSMContext Request to SMF(s) associated with the PDU Session(s) in order to activate User Plane connections of these PDU Session(s). Steps from step 5 onwards described in clause 4.2.3.2 are executed to complete the User Plane connection activation without sending the RRC Inactive Assistance Information and without sending MM NAS Service Accept from the AMF to (R)AN described in step 12 of clause 4.2.3.2. When a User Plane connection for a PDU Session is activated, the AS layer in the UE indicates it to the NAS layer.

[0474] -If the AMF has determined in step 3 that the UE is performing Inter-RAT mobility to or from NB-loT, the AMF sends Nsmf_PDUSession_UpdateSMContext Request to SMF(s) associated with the UEs PDU Session(s), so the SMF(s) can update them according to the "PDU Session continuity at inter RAT mobility" subscription data. Steps from step 5 onwards described in clause 4.2.3.2 are executed without sending MM NAS Service Accept from the AMF to (R)AN described in step 12 of clause 4.2.3.2.

[0475] When the serving AMF has changed, the new serving AMF notifies the SMF for each PDU Session that it has taken over the responsibility of the signalling path towards the UE: the new serving AMF invokes the Nsmf_PDUSession_UpdateSMContext service operation using SMF information received from the old AMF at step 5. It also indicates whether the PDU Session is to be re-activated.

[0476] NOTE 12: If the UE moves into a different PLMN, the AMF in the serving PLMN can insert or change the V- SMF(s) in the serving PLMN for Home Routed PDU session(s). In addition, a V-SMF is removed in case the UE moves from a VPLMN into the HPLMN. In these cases, the same procedures described in clause 4.23.3 are applied for the V- SMF change as for the l-SMF change (i.e. by replacing the l-SMF with V-SMF). During inter-PLMN change, if the same SMF is used, session continuity can be supported depending on operator policies.

[0477] Steps from step 5 onwards described in clause 4.2.3.2 are executed. In the case that the intermediate UPF insertion, removal, or change is performed for the PDU Session(s) not included in "PDU Session(s) to be re-activated", the procedure is performed without N11 and N2 interactions to update the N3 user plane between (R)AN and 5GC.

[0478] The AMF invokes the Nsmf_PDUSession_ReleaseSMContext service operation towards the SMF in the following scenario: [0479] -If any PDU Session status indicates that it is released at the UE, the AMF invokes the Nsmf_PDUSession_ReleaseSMContext service operation towards the SMF in order to release any network resources related to the PDU Session.

[0480] If the serving AMF is changed, the new AMF shall wait until step 18 is finished with all the SMFs associated with the UE. Otherwise, steps 19 to 22 can continue in parallel to this step.

[0481] 18. (744) [Conditional] If the new AMF and the old AMF are in the same PLMN, the new AMF sends a UE

Context Modification Request to N3IWF/TNGF/W-AGF as specified in TS 29.413 [64],

[0482] If the AMF has changed and the old AMF has indicated that the UE is in CM-CONNECTED state via N3I WF, W-AGF or TNGF and if the new AMF and the old AMF are in the same PLMN, the new AMF creates an NGAP UE association towards the N3IWF/TNGF/W-AGF to which the UE is connected. This automatically releases the existing NGAP UE association between the old AMF and the N3IWF/TNGF/W-AGF.

[0483] 19. (746) N3IWF/TNGF/W-AGF sends a UE Context Modification Response to the new AMF.

[0484] 19a. (748) [Conditional] After the new AMF receives the response message from the N3IWF, W-AGF or

TNGF in step 19, the new AMF registers with the UDM using Nudm_UECM_Registration as step 14a, but with the Access Type set to "non-3GPP access". The UDM stores the associated Access Type together with the serving AMF and does not remove the AMF identity associated to the other Access Type if any. The UDM may store in UDR information provided at the AMF registration by Nudr_DM_Update.

[0485] 19b. (750) [Conditional] When the UDM stores the associated Access Type (i.e. non-3GPP) together with the serving AMF as indicated in step 19a, it will cause the UDM to initiate a Nudm_UECM_DeregistrationNotification (see clause 5.2.3.2.2) to the old AMF corresponding to the same (i.e. non-3GPP) access. The old AMF removes the UE context for non-3GPP access.

[0486] 19c. (752) The Old AMF unsubscribes with the UDM for subscription data using Nudm_SDM_unsubscribe.

[0487] 20a.Void.

[0488] 21. (754) New AMF to UE: Registration Accept (5G-GUTI, Registration Area, [Mobility restrictions], [PDU

Session status], [Allowed NSSAI], [Mapping Of Allowed NSSAI], [Configured NSSAI for the Serving PLMN], [Mapping Of Configured NSSAI], [NSSRG Information], [NSAG Information], [rejected S-NSSAIs], [Pending NSSAI], [Mapping Of Pending NSSAI], [Periodic Registration Update timer], [Active Time], [Strictly Periodic Registration Timer Indication], [LADN Information], [accepted MICO mode], [IMS Voice over PS session supported Indication], [Emergency Service Support indicator], [Accepted DRX parameters for E-UTRA and NR], [Accepted DRX parameters for NB-loT], [extended idle mode DRX parameters], [Paging Time Window], [Network support of Interworking without N26], [Access Stratum Connection Establishment NSSAI Inclusion Mode], [Network Slicing Subscription Change Indication], [Operator-defined access category definitions], [List of equivalent PLMNs], [Enhanced Coverage Restricted information], [Supported Network Behaviour], [Service Gap Time], [PLMN-assigned UE Radio Capability ID], [PLMN-assigned UE Radio Capability ID deletion], [WUS Assistance Information], [AMF PEIPS Assistance Information], [Truncated 5G-S-TMSI Configuration], [Connection Release Supported], [Paging Cause Indication for Voice Service Supported], [Paging Restriction Supported], [Reject Paging Request Supported], [Paging Restriction Information acceptance I rejection], ["List of PLMN(s) to be used in Disaster Condition"], [Disaster Roaming wait range information], [Disaster Return wait range information]).

[0489] NEW: If N2 Request includes MCX 5GC Support Indication, including an indicator for 5GC support for MCX or not, RAN shall store it and use it for mobility reasons e.g. trigger MCX fallback. MCX Support Indication indicates separate support for each different MCX service i.e. MCPTT, MC Video and MC Data.

[0490] If the Requested NSSAI does not include S-NSSAIs which map to S-NSSAIs of the HPLMN subject to Network Slice-Specific Authentication and Authorization and the AMF determines that no S-NSSAI can be provided in the Allowed NSSAI for the UE in the current UE's Tracking Area and if no default S-NSSAI (s) not yet involved in the current UE Registration procedure could be further considered, the AMF shall reject the UE Registration and shall include in the rejection message the list of Rejected S-NSSAIs, each of them with the appropriate rejection cause value.

[0491] The Allowed NSSAI for the Access Type for the UE is included in the N2 message carrying the Registration Accept message. The Allowed NSSAI contains only S-NSSAIs that do not require, based on subscription information, Network Slice-Specific Authentication and Authorization and, based on the UE Context in the AMF, those S-NSSAIs for which Network Slice-Specific Authentication and Authorization previously succeeded, regardless of the Access Type. The Mapping Of Pending NSSAI is the mapping of each S-NSSAI of the Pending NSSAI for the Serving PLMN to the HPLMN S-NSSAIs.

[0492] If the UE has indicated its support of the Network Slice-Specific Authentication and Authorization procedure in the UE MM Core Network Capability in the Registration Request, AMF includes in the Pending NSSAI the S-NSSAIs that map to an S-NSSAI of the HPLMN which in the subscription information has indication that it is subject to Network Slice-Specific Authentication and Authorization, as described in clause 4.6.2.4 of TS 24.501 [25], In such case, the AMF then shall trigger at step 25 the Network Slice-Specific Authentication and Authorization procedure, specified in clause 4.2.9.2, except, based on Network policies, for those S-NSSAIs for which Network Slice-Specific Authentication and Authorization have already been initiated on another Access Type for the same S-NSSAI (s). The UE shall not attempt reregistration with the S-NSSAIs included in the list of Pending NSSAIs until the Network Slice-Specific Authentication and Authorization procedure has been completed, regardless of the Access Type.

[0493] If the UE has not indicated its support of the Network Slice-Specific Authentication and Authorization procedure in the UE 5GMM Core Network Capability in the Registration Request and the Requested NSSAI includes S- NSSAIs which map to HPLMN S-NSSAIs subject to Network Slice-Specific Authentication and Authorization, the AMF includes those S-NSSAIs in the Requested NSSAI in the Rejected S-NSSAIs.

[0494] If no S-NSSAI can be provided in the Allowed NSSAI because:

[0495] -all the S-NSSAI(s) in the Requested NSSAI are to be subject to Network Slice-Specific Authentication and Authorization; or [0496] -no Requested NSSAI was provided or none of the S-NSSAIs in the Requested NSSAI matches any of the Subscribed S-NSSAIs and all the S-NSSAI(s) marked as default in the Subscribed S-NSSAIs are to be subject to Network Slice-Specific Authentication and Authorization.

[0497] The AMF shall provide an empty Allowed NSSAI. Upon receiving an empty Allowed NSSAI and a Pending NSSAI, the UE is registered in the PLMN but shall wait for the completion of the Network Slice-Specific Authentication and Authorization procedure without attempting to use any service provided by the PLMN on any access, except e.g. emergency services (see TS 24.501 [25]), until the UE receives an Allowed NSSAI.

[0498] The AMF stores the NB-loT Priority retrieved in Step 14 and associates it to the 5G-S-TMSI allocated to the UE.

[0499] If the Registration Request message received over 3GPP access does not include any Paging Restriction Information, the AMF shall delete any stored Paging Restriction Information for this UE and stop restricting paging accordingly.

[0500] If the Registration Request message received over 3GPP access includes the Paging Restriction Information, AMF may accept or reject the Paging Restriction Information requested by the UE based on operator policy. If the AMF rejects the Paging Restriction Information, the AMF removes any stored Paging Restriction Information from the UE context and discards the UE requested Paging Restriction Information. If the AMF accepts the Paging Restriction Information from the UE, the AMF stores the Paging Restriction Information from the UE in the UE context and informs the UE about the acceptance/rejection of the requested Paging Restriction Information in the Registration Accept message.

[0501] If the Registration Request message received over 3GPP access includes a Release Request indication, then:

[0502] -the AMF updates the UE context with any received Paging Restriction Information, then enforces it in the network triggered Service Request procedure as described in clause 4.2.3.3;

[0503] -the AMF does not establish User Plane resources and triggers the AN release procedure as described in clause 4.2.6 after the completion of Registration procedure.

[0504] The AMF sends a Registration Accept message to the UE indicating that the Registration Request has been accepted. 5G-GUTI is included if the AMF allocates a new 5G-GUTI. Upon receiving a Registration Request message of type "Initial Registration", "mobility registration update", "Disaster Roaming Initial Registration" or "Disaster Roaming Mobility Registration Update" from the UE, the AMF shall include a new 5G-GUTI in the Registration Accept message. Upon receiving a Registration Request message of type "periodic registration update" from the UE, the AMF should include a new 5G-GUTI in the Registration Accept message. If the UE is already in RM-REGISTERED state via another access in the same PLMN, the UE shall use the 5G-GUTI received in the Registration Accept for both registrations. If no 5G-GUTI is included in the Registration Accept, then the UE uses the 5G-GUTI assigned for the existing registration also for the new registration. If the AMF allocates a new Registration area, it shall send the Registration area to the UE via Registration Accept message. For a Disaster Roaming Registration, the AMF allocates the Registration Area limited to the area with Disaster Condition as specified in clause 5.40 of TS 23.501 [2], If there is no Registration area included in the Registration Accept message, the UE shall consider the old Registration Area as valid. Mobility Restrictions is included if mobility restrictions applies for the UE and Registration Type is not Emergency Registration. The AMF indicates the established PDU Sessions to the UE in the PDU Session status. The UE removes locally any internal resources related to PDU Sessions that are not marked as established in the received PDU Session status. If the AMF invokes the Nsmf_PDUSession_UpdateSMContext procedure for UP activation of PDU Session(s) in step 18 and receives rejection from the SMF, then the AMF indicates to the UE the PDU Session ID and the cause why the User Plane resources were not activated. When the UE is connected to the two AMFs belonging to different PLMN via 3GPP access and non-3GPP access then the UE removes locally any internal resources related to the PDU Session of the current PLMN that are not marked as established in received PDU Session status. If the PDU Session status information was in the Registration Request, the AMF shall indicate the PDU Session status to the UE.

[0505] If the RAT Type is NB-loT and the network is configured to use the Control Plane Relocation Indication procedure then the AMF shall include in the Registration Accept message the Truncated 5G-S-TMSI Configuration that the UE using Control Plane CloT 5GS Optimisation uses to create the Truncated 5G-S-TMSI, see clause 5.31 .4.3 of TS 23.501 [2],

[0506] The Allowed NSSAI provided in the Registration Accept is valid in the Registration Area and it applies for all the PLMNs which have their Tracking Areas included in the Registration Area. The Mapping Of Allowed NSSAI is the mapping of each S-NSSAI of the Allowed NSSAI to the HPLMN S-NSSAIs. The Mapping Of Configured NSSAI is the mapping of each S-NSSAI of the Configured NSSAI for the Serving PLMN to the HPLMN S-NSSAIs.

[0507] If the UE has indicated its support of the subscription-based restrictions to simultaneous registration of network slices feature in the UE 5GMM Core Network Capability, the AMF includes, if available, the NSSRG Information, defined in clause 5.15.12 of TS 23.501 [2],

[0508] If the UE has not indicated its support of the subscription-based restrictions to simultaneous registration of network slices feature and the subscription information for the UE includes SRG information and the AMF is providing the Configured NSSAI to the UE, the Configured NSSAI shall include the S-NSSAIs according to clause 5.15.12 of TS 23.501 [2].

[0509] If the UE has indicated its support of the NSAG feature in the 5GMM Core Network Capability, the AMF includes, if available, the NSAG Information, defined in clause 5.15.14 of TS 23.501 [2],

[0510] The AMF shall include in the Registration Accept message the LADN Information for the list of LADNs, described in clause 5.6.5 of TS 23.501 [2], that are available within the Registration area determined by the AMF for the UE. The AMF may include Operator-defined access category definitions to let the UE determine the applicable Operatorspecific access category definitions as described in TS 24.501 [25], [0511] If the UE included MICO mode in the Registration Request, then AMF responds in the Registration Accept message whether MICO mode should be used. When MICO mode is allowed for the UE, the AMF may include an Active Time value and/or Strictly Periodic Registration Timer Indication in the Registration Accept message. The AMF determines the Periodic Registration Update timer value, Active Time value and the Strictly Periodic Registration Timer Indication based on local configuration, Expected UE Behaviour if available, UE indicated preferences, UE capability, UE subscription information and network policies, or any combination of them so as to enable UE power saving, as described in clause 5.31.7 of TS 23.501 [2], The AMF determines to apply the Strictly Periodic Registration Timer Indication to the UE if the UE indicates its capability of the Strictly Periodic Registration Timer Indication in the registration request message, as described in step 1 . If the AMF provides the Periodic Registration Update timer value with the Strictly Periodic Registration Timer Indication to the UE, the UE and the AMF start the Periodic Registration Update timer after this step, as described in clause 5.31 .7.5 of TS 23.501 [2],

[0512] In the case of registration over 3GPP access, the AMF Sets the IMS Voice over PS session supported Indication as described in clause 5.16.3.2 of TS 23.501 [2], In order to set the IMS Voice over PS session supported Indication the AMF may need to perform the UE Capability Match Request procedure in clause 4.2.8a to check the compatibility of the UE and NG-RAN radio capabilities related to IMS Voice over PS. If the AMF hasn't received Voice Support Match Indicator from the NG-RAN on time then, based on implementation, AMF may set IMS Voice over PS session supported Indication and update it at a later stage.

[0513] In the case of registration over 3GPP access and the AMF has retrieved or determined according to local configuration a Target NSSAI and a corresponding RFSP Index for the purpose of allowing the NG-RAN to redirect the UE to a cell supporting network slices not available in the current TA as described in clause 5.3.4.3.3 of TS 23.501 [2], the AMF provides the Target NSSAI and the corresponding RFSP Index to the NG-RAN.

[0514] In the case of registration over non-3GPP access, the AMF Sets the IMS Voice over PS session supported Indication as described in clause 5.16.3.2a of TS 23.501 [2],

[0515] The Emergency Service Support indicator informs the UE that emergency services are supported, i.e. the UE is allowed to request PDU Session for emergency services. If the AMF received "MPS priority" from the UDM as part of Access and Mobility Subscription data, based on operator policy, "MPS priority" is included in the Registration Accept message to the UE to inform the UE whether configuration of Access Identity 1 is valid within the selected PLMN, as specified in TS 24.501 [25], If the AMF received "MCX priority" from the UDM as part of Access and Mobility Subscription data, based on operator policy and UE subscription to MCX Services, "MCX priority" is included in the Registration Accept message to the UE to inform the UE whether configuration of Access Identity 2 is valid within the selected PLMN, as specified in TS 24.501 [25], The Accepted DRX parameters are defined in clause 5.4.5 of TS 23.501 [2], The AMF includes Accepted DRX parameters for NB-loT, if the UE included Requested DRX parameters for NB-loT in the Registration Request message. The AMF Sets the Network support of Interworking without N26 parameter as described in clause 5.17.2.3.1 of TS 23.501 [2], If the AMF accepts the use of extended idle mode DRX, the AMF includes the extended idle mode DRX parameters and Paging Time Window as described in 5.31 .7.2 of TS 23.501 [2], [0516] If the UDM intends to indicate the UE that subscription has changed, the Network Slicing Subscription Change Indication is included. If the AMF includes Network Slicing Subscription Change Indication, then the UE shall locally erase all the network slicing configuration for all PLMNs and, if applicable, update the configuration for the current PLMN based on any received information.

[0517] The Access Stratum Connection Establishment NSSAI Inclusion Mode, as specified in clause 5.15.9 of TS 23.501 [2], is included to instruct the UE on what NSSAI, if any, to include in the Access Stratum connection establishment. The AMF can set the value to modes of operation a,b,c defined in clause 5.15.9 of TS 23.501 [2] in the 3GPP Access only if the Inclusion of NSSAI in RRC Connection Establishment Allowed indicates that it is allowed to do so.

[0518] For a UE registered in a PLMN, the AMF may provide a List of equivalent PLMNs which is handled as specified in TS 24.501 [25], For a UE registered in an SNPN, the AMF shall not provide a list of equivalent PLMNs to the UE.

[0519] If the UE included support for restriction of use of Enhanced Coverage in step 1, the AMF sends the Enhanced Coverage Restricted information to the NG-RAN in N2 message. The AMF also sends Enhanced Coverage Restricted information to the UE in the Registration Accept message.

[0520] If the UE receives Enhanced Coverage Restricted information in the Registration Accept message, the UE shall store this information and shall use the value of Enhanced Coverage Restricted information to determine if Enhanced Coverage feature should be used or not.

[0521] If the UE and the AMF have negotiated to enable MICO mode and the AMF uses the Extended connected timer, then the AMF provides the Extended Connected time value to NG-RAN (see clause 5.31 .7.3 of TS 23.501 [2]) in this step. The Extended Connected Time value indicates the minimum time the RAN should keep the UE in RRC- CONNECTED state regardless of inactivity.

[0522] The AMF indicates the CloT 5GS Optimisations it supports and accepts in the Supported Network Behaviour information (see clause 5.31.2 of TS 23.501 [2]) if the UE included Preferred Network Behaviour in its Registration Request.

[0523] The AMF may steer the UE from 5GC by rejecting the Registration Request. The AMF should take into account the Preferred and Supported Network Behaviour (see clause 5.31 .2 of TS 23.501 [2]) and availability of EPC to the UE before steering the UE from 5GC.

[0524] If the AMF accepts MICO mode and knows there may be mobile terminated data or signalling pending, the AMF maintains the N2 connection for at least the Extended Connected Time as described in clause 5.31 .7.3 of TS 23.501 [2] and provides the Extended Connected Time value to the RAN. [0525] The AMF includes Service Gap Time if Service Gap Time is present in the subscription information (steps 14a-c) or the Service Gap Time has been updated by the Subscriber Data Update Notification to AMF procedure (see clause 4.5.1) and the UE has indicated UE Service Gap Control Capability.

[0526] If the UE receives a Service Gap Time in the Registration Accept message, the UE shall store this parameter and apply Service Gap Control (see clause 5.31 .16 of TS 23.501 [2]).

[0527] If the network supports WUS grouping (see TS 23.501 [2]), the AMF shall send the WUS Assistance Information to the UE. If the UE provided the UE paging probability information in Step 1, the AMF takes it into account to determine the WUS Assistance Information.

[0528] If the UE provided Paging Subgrouping Support Indication in step 1, a supporting AMF may provide the AMF PEIPS Assistance Information, including the Paging Subgroup ID as defined in TS 23.501 [2], [0529] When the UE and the AMF supports RAGS as defined in clause 5.4.4.1a of TS 23.501 [2] and the AMF needs to configure the UE with a UE Radio Capability ID and the AMF already has the UE radio capabilities other than NB-loT radio capabilities for the UE, the AMF may provide the UE with the UE Radio Capability ID for the UE radio capabilities the UCMF returns to the AMF in a Nucmf_assign service operation for this UE. Alternatively, when the UE and the AMF support RAGS, the AMF may provide the UE with an indication to delete any PLMN-assigned UE Radio Capability ID in this PLMN (see clause 5.4.4.1a of TS 23.501 [2]).

[0530] If the UE is "GAG supported" and the AMF needs to update the GAG information of the UE, the AMF may include the GAG information as part of the Mobility Restrictions in the Registration Accept message.

[0531] If the Multi-USIM UE has indicated support for one or more Multi-USIM Specific Capabilities in the UE 5GMM Core Network Capability in step 1, the AMF shall indicate to the Multi-USIM UE whether the corresponding one or more Multi-USIM specific features described in clause 5.38 of TS 23.501 [2] are supported, based on network capability and preference by the network (i.e. based on local network policy), by providing one or more of the Connection Release Supported, Paging Cause Indication for Voice Service Supported, Paging Restriction Supported and Reject Paging Request Supported indications. The AMF shall only indicate Paging Restriction Supported together with either Connection Release Supported or Reject Paging Request Supported. The UE shall only use Multi-USIM specific features that the AMF indicated as being supported.

[0532] If the UE and AMF supports Disaster Roaming service, the AMF may include the "list of PLMN(s) to be used in Disaster Condition", Disaster Roaming wait range information and Disaster Return wait range information as specified in TS 23.501 [2],

[0533] In the case of Emergency Registration, the AMF shall not indicate support for any Multi-USIM specific features to the UE.

[0534] 21b. (758) [Optional] The new AMF performs a UE Policy Association Establishment as defined in clause

4.16.11. For an Emergency Registration, this step is skipped. [0535] The new AMF sends a NpcfJJ EPol icyControl Create Request to PCF. PCF sends a Npcf_U EPol icyControl Create Response to the new AMF.

[0536] PCF triggers UE Configuration Update Procedure as defined in clause 4.2.4.3.

[0537] 22. (760) [Conditional] UE to new AMF: Registration Complete ().

[0538] The UE sends a Registration Complete message to the AMF when it has successfully updated itself after receiving any of the [Configured NSSAI for the Serving PLMN], [Mapping Of Configured NSSAI], [NSSRG Information], [NSAG Information] and a Network Slicing Subscription Change Indication, or CAG information in step 21.

[0539] The UE sends a Registration Complete message to the AMF to acknowledge if a new 5G-GUTI was assigned.

[0540] If new 5G-GUTI was assigned, then the UE passes the new 5G-GUTI to its 3GPP access' lower layer when a lower layer (either 3GPP access or non-3GPP access) indicates to the UE's RM layer that the Registration Complete message has been successfully transferred across the radio interface.

[0541] NOTE 13:The above is needed because the NG-RAN may use the RRC Inactive state and a part of the 5G- GUTI is used to calculate the Paging Frame (see TS 38.304 [44] and TS 36.304 [43]). It is assumed that the Registration Complete is reliably delivered to the AMF after the 5G-AN has acknowledged its receipt to the UE.

[0542] When the List Of PDU Sessions To Be Activated is not included in the Registration Request and the Registration procedure was not initiated in CM-CONNECTED state, the AMF releases the signalling connection with UE, according to clause 4.2.6.

[0543] When the Follow-on request is included in the Registration Request, the AMF should not release the signalling connection after the completion of the Registration procedure.

[0544] If the AMF is aware that some signalling is pending in the AMF or between the UE and the 5GC, the AMF should not release the signalling connection immediately after the completion of the Registration procedure.

[0545] If PLMN-assigned UE Radio Capability ID is included in step 21, the AMF stores the PLMN-assigned UE Radio Capability ID in UE context if receiving Registration Complete message.

[0546] If the UE receives PLMN-assigned UE Radio Capability ID deletion indication in step 21, the UE shall delete the PLMN-assigned UE Radio Capability ID(s) for this PLMN.

[0547] 23 (762). [Conditional] AMF to UDM: If the Access and Mobility Subscription data provided by UDM to AMF in 14b includes Steering of Roaming information with an indication that the UDM requests an acknowledgement of the reception of this information from the UE, the AMF provides the UE acknowledgement to UDM using Nudm_SDM_lnfo. For more details regarding the handling of Steering of Roaming information refer to TS 23.122 [22],

[0548] 23a.For Registration over 3GPP Access, if the AMF does not release the signalling connection, the AMF sends the RRC Inactive Assistance Information to the NG-RAN.

[0549] For Registration over non-3GPP Access, if the UE is also in CM-CONNECTED state on 3GPP access, the AMF sends the RRC Inactive Assistance Information to the NG-RAN. If the Multi-USIM UE has indicated support for the Paging Cause Indication for Voice Service feature and the network supports the Paging Cause Indication for Voice Service, the AMF shall include an indication in the RRC Inactive Assistance Information that the UE supports the Paging Cause Indication for Voice Service to NG-RAN to enable NG-RAN to apply the Paging Cause Indication for Voice Service feature for RAN based paging.

[0550] The AMF also uses the Nudm_SDM_lnfo service operation to provide an acknowledgment to UDM that the UE received CAG information, or the Network Slicing Subscription Change Indication (see step 21 and step 22) and acted upon it.

[0551] 24. (764) [Conditional] AMF to UDM: After step 14a and in parallel to any of the preceding steps, the AMF shall send a "Homogeneous Support of IMS Voice over PS Sessions" indication to the UDM using NudmJJECMJJpdate: [0552] -If the AMF has evaluated the support of IMS Voice over PS Sessions, see clause 5.16.3.2 of TS 23.501 [2], and

[0553] -If the AMF determines that it needs to update the Homogeneous Support of IMS Voice over PS Sessions, see clause 5.16.3.3 of TS 23.501 [2],

[0554] 25. (766) [Conditional] If the UE indicates its support for Network Slice-Specific Authentication and

Authorization procedure in the UE MM Core Network Capability in Registration Request and any S-NSSAI of the HPLMN is subject to Network Slice-Specific Authentication and Authorization, the related procedure is executed at this step (see clause 4.2.9.1). Once the Network Slice-Specific Authentication and Authorization procedure is completed for all S- NSSAIs, the AMF shall trigger a UE Configuration Update procedure to deliver an Allowed NSSAI containing also the S- NSSAIs for which the Network Slice-Specific Authentication and Authorization was successful and include any rejected NSSAIs with an appropriate rejection cause value.

[0555] The AMF shall remove the mobility restriction if the T racking Areas of the Registration Area were previously assigned as a Non-Allowed Area due to pending Network Slice-Specific Authentication and Authorization.

[0556] The AMF stores an indication in the UE context for any S-NSSAI of the HPLMN subject to Network Slice- Specific Authentication and Authorization for which the Network Slice-Specific Authentication and Authorization succeeds. [0557] Once completed the Network Slice-Specific Authentication and Authorization procedure, if the AMF determines that no S-NSSAI can be provided in the Allowed NSSAI for the UE, which is already authenticated and authorized successfully by a PLMN and if no default S-NSSAI(s) could be further considered, the AMF shall execute the Network-initiated Deregistration procedure described in clause 4.2.2.3.3 and shall include in the explicit De-Registration Request message the list of Rejected S-NSSAIs, each of them with the appropriate rejection cause value.

[0558] The mobility related event notifications towards the NF consumers are triggered at the end of this procedure for cases as described in clause 4.15.4.

3GPP TS 23.502 v17.5.0 (2022-06):

NOTE: The Inter NG-RAN node N2 based handover is an example for handover procedure that the proposed mechanism can used but is not limited to that. For instance, also intersystem change with handover from 5G to 4G is also applicable. [0559] 4.9.1.3 Inter NG-RAN node N2 based handover

[0560] 4.9.1.3.1 General

[0561] Clause 4.9.1 .3 includes details regarding the inter NG-RAN node N2 based handover without Xn interface.

[0562] The source NG-RAN decides to initiate an N2-based handover to the target NG-RAN. This can be triggered, for example, due to new radio conditions or load balancing, if there is no Xn connectivity to the target NG-RAN, an error indication from the target NG-RAN after an unsuccessful Xn-based handover (i.e. no IP connectivity between T-RAN and S-UPF), or based on dynamic information learnt by the S-RAN.

[0563] The availability of a direct forwarding path is determined in the source NG-RAN and indicated to the SMFs. If IP connectivity is available between the source and target NG-RAN and security association(s) is in place between them, a direct forwarding path is available.

[0564] If a direct forwarding path is not available, indirect forwarding may be used. The SMFs use the indication from the source NG-RAN to determine whether to apply indirect forwarding.

[0565] If both source NG-RAN and source AMF support DAPS the source NG-RAN may decide that some of the DRBs are subject for DAPS handover as defined in TS 38.300 [9]; in this case, the source NG-RAN provides the DAPS information indicating the request concerns a DAPS handover for the DRB as part of the Source to Target (NG-RAN) Transparent Container. If the target NG-RAN accepts that the request concerns DAPS handover and both Target NG- RAN and Target AMF support DAPS, the DAPS handover will be performed and target NG-RAN provides DAPS response information as part of the Target to Source (NG-RAN) Transparent Container.

[0566] In the case of handover to a shared network, the source NG-RAN determines a PLMN to be used in the target network as specified by TS 23.501 [2], The source NG-RAN shall indicate the selected PLMN ID (or PLMN ID and NID, see clause 5.30 of TS 23.501 [2]) to be used in the target network to the AMF as part of the Tracking Area sent in the HO Required message.

[0567] If the AMF generates the N2 downlink signalling during the ongoing handover and receives a rejection to a N2 interface procedure (e.g. DL NAS message transfer; Location reporting control; etc.) from the NG-RAN with an indication that an Inter NG-RAN node handover procedure is in progress, the AMF may reattempt the same N2 interface procedure either when the handover is complete or the handover is deemed to have failed if the AMF is still the serving AMF, when possible. If the Inter NG-RAN node handover changes the serving AMF, the source AMF shall terminate any other ongoing N2 interface procedures except the handover procedure.

[0568] In order to minimize the number of procedures rejected by NG-RAN, the AMF should pause non-handover related N2 interface procedures (e.g. DL NAS message transfer, Location Report Control, etc.) while a handover is ongoing (i.e. from the time that a Handover Required has been received until either the Handover procedure has succeeded (Handover Notify) or failed (Handover Failure)) and continue them once the Handover procedure has completed if the AMF is still the serving AMF. [0569] If during the handover procedure the AMF detects that the AMF needs be changed, the AMF shall reject any SMF initiated N2 request received since handover procedure started and shall include an indication that the request has been temporarily rejected due to handover procedure in progress.

[0570] Upon reception for an SMF initiated N1 and/or N2 request(s) with an indication either from the NG-RAN (via N2 SM Info) or AMF that the request has been temporarily rejected due to handover procedure in progress, the SMF starts a locally configured guard timer. The SMF should hold any signalling messages targeted towards AMF for a given UE during the handover preparation phase unless it detects that the handover execution is completed or handover has failed/cancelled. The SMF may re-attempt, up to a pre-configured number of times, when either it detects that the handover is completed or has failed using message reception or at expiry of the guard timer.

[0571] In the case of home routed roaming scenario, the SMF in the Inter NG-RAN node N2 based handover procedure (Figure 4.9.1.3.2-1 and Figure 4.9.1.3.3-1) interacting with the S-UPF, T-UPF, S-AMF and T-AMF is the V-SMF and the SMF (Figure 4.9.1.3.3-1) interacting with the UPF (PSA) is the H-SMF.

Figure 8

[0572] Figure 8 corresponds to TS 23.502 Figure 4.9.1.3.2-1 of section 4.9.1.3.2 Preparation Phase, and the following steps relate to Figure 8.

[0573] 1. (802) S-RAN to S-AMF: Handover Required (Target ID, Source to Target transparent container (NEW: including MCX 5GC Support Indication), SM N2 info list, PDU Session IDs, intra system handover indication).

[0574] Source to Target transparent container includes NG-RAN information created by S-RAN to be used by T- RAN and is transparent to 5GC. It also contains for each PDU session the corresponding QoS flows/DRBs information subject to data forwarding. It may also contain DAPS Information if DAPS handover is supported by S-RAN and S-AMF and DAPS handover is requested for one or more DRBs as described in TS 38.300 [9], NEW: If Handover Required includes MCX 5GC Support Indication, including an indicator for 5GC support for MCX or not, source RAN shall store it and use it for mobility reasons e.g. trigger MCX fallback. MCX Support Indication indicates separate support for each different MCX service i.e. MCPTT, MC Video and MC Data.

[0575] All PDU Sessions handled by S-RAN (i.e. all existing PDU Sessions with active UP connections) shall be included in the Handover Required message, indicating which of those PDU Session(s) are requested by S-RAN to handover. The SM N2 info includes Direct Forwarding Path Availability if direct data forwarding is available.

[0576] Direct Forwarding Path Availability indicates whether direct forwarding is available from the S-RAN to the T- RAN. This indication from S-RAN can be based on e.g. the presence of IP connectivity and security association(s) between the S-RAN and the T-RAN.

[0577] If the source NG RAN and target NG RAN support RAGS as defined in TS 23.501 [2], the Source to Target transparent container need not carry the UE radio access capabilities (instead the UE Radio Capability ID is supplied from the CN to the T-RAN). However, if the source NG-RAN has knowledge that the target NG-RAN might not have a local copy of the Radio Capability corresponding to the UE Radio Capability ID (i.e. because the source NG-RAN had itself to retrieve the UE's Radio Capability from the AMF) then the source NG-RAN may also send some (or all) of the UE's Radio Capability to the target NG-RAN (the size limit based on local configuration). In the case of inter-PLMN handover, when the source and target NG-RAN support RAGS as defined in TS 23.501 [2] and the source NG-RAN determines based on local configuration that the target PLMN does not support the UE Radio Capability ID assigned by the source PLMN, then the source NG-RAN includes the UE radio access capabilities in the Source to Target transparent container.

[0578] 2. (804) T-AMF Selection: When the S-AMF can't serve the UE anymore, the S-AMF selects the T-AMF as described in clause 6.3.5 on "AMF Selection Function" in TS 23.501 [2],

[0579] 3. (806) [Conditional] S-AMF to T-AMF: Namf_Communication_CreateUEContext Request (N2 Information

(Target ID, Source to Target transparent container (NEW: including MCX 5GC Support Indication), SM N2 information list, PDU Session IDs, NEW: MCX 5GC Support Indication ), UE context information (SUPI, Service area restriction, Allowed NSSAI for each Access Type if available, Tracing Requirements, LTE M Indication, the list of PDU Session IDs along with the corresponding SMF information and the corresponding S-NSSAI(s), PCF ID(s), DNN, UE Radio Capability ID and UE Radio Capability Information, N2 Notify URI). If the subscription information includes Tracing Requirements, the old AMF provides the target AMF with Tracing Requirements. The indication - if sent as a separate parameter - could either be sent from source RAN to target RAN (via source AMF and target AMF) or be sent from source AMF.

[0580] If the old AMF was a consumer of UE related NWDAF services, the old AMF includes information about active analytics subscriptions, i.e. the Subscription Correlation ID(s), NWDAF identifier(s) (i.e. Instance ID or Set ID), Analytics ID(s) and associated Analytics specific data in the Namf_Communication_UEContextTransfer request. Usage of the analytics information by the new AMF is specified in TS 23.288 [50],

[0581] In inter PLMN handover case, UE context information includes HPLMN S-NSSAIs corresponding to the Allowed NSSAI for each Access Type, without Allowed NSSAI of source PLMN. The target AMF may determine the Allowed NSSAI based on the HPLMN S-NSSAIs received in step 3, or else the target AMF queries the NSSF by invoking Nnssf_NSSelection_Get service operation with the HPLMN S-NSSAIs and PLMN ID of SUPI. Based on the query result returned from the NSSF, the target AMF determines whether the AMF re-allocation need be triggered and if needed reselects another target AMF. In this case the target AMF selected by the S-AMF is the Initial AMF. And another reselected target AMF is the final target AMF (i.e. T-AMF).

[0582] The S-AMF initiates Handover resource allocation procedure by invoking the Namf_Communication_CreateUEContext service operation towards the target AMF.

[0583] When the S-AMF can still serve the UE, this step and step 12 are not needed.

[0584] NEW: S-AMF includes MCX 5GC Support Indication from the UE context in S-AMF, if available. If

Namf_Communication_CreateUEContext Request includes MCX 5GC Support Indication, including an indicator for 5GC support for MCX or not, T-AMF stores it in the UE context and forwards it further to target RAN. MCX Support Indication indicates separate support for each different MCX service i.e. MCPTT, MC Video and MC Data. [0585] If target AMF re-allocation is needed, e.g. due to the inter PLMN handover, the initial AMF invokes Namf_Communication_RelocateUEContext request (SUPI, Target 5GAN Node ID, Source to Target Transparent Container (NEW: including MCX 5GC Support Indication), 5GS MM Context, PDU Session ID and its associated S-NSSAI of the VPLMN value for each PDU Session, the corresponding S-NSSAI of HPLMN value for home routed PDU Session(s), Allowed NSSAI, N2 Notify URI, NEW: MCX 5GC Support Indication ) to the selected final target AMF. The indication - if sent as a separate parameter - could either be sent from source RAN to target RAN (via source AMF and target AMF) or be sent from source AMF. The N2 Notify URI is the N2 Notify URI of the source AMF, which is used by the T-AMF to send N2 handover notify to the S-AMF. If the information about active analytics subscriptions are received from S-AMF, it is also included them in the Namf_Communication_RelocateUEContext request.

[0586] If Service area restrictions are available in the S-AMF, they may be forwarded to the T-AMF as described in clause 5.3.4.1.2 in TS 23.501 [2],

[0587] If both Home and Visited PCF ID(s) are provided by the S-AMF, the T-AMF contacts the (V-) PCF identified by the (V-)PCF ID. If the (V-)PCF identified by the (V-)PCF ID is not used or there are no PCF ID(s) received from the S- AMF, the T-AMF may select the PCF(s) as described in clause 6.3.7.1 of TS 23.501 [2] and according to the V-NRF to H- NRF interaction described in clause 4.3.2.2.3.3. The T-AMF informs the S-AMF that the PCF ID is not used, as defined in step 12 and then the S-AMF terminates the AM Policy Association with the PCF identified by the PCF ID.

[0588] NEW: S-AMF includes MCX 5GC Support Indication from the UE context in S-AMF, if available. If Namf_Communication_RelocateUEContext request includes MCX 5GC Support Indication, including an indicator for 5GC support for MCX or not, T-AMF stores it in the UE context and forwards it further to target RAN. MCX Support Indication indicates separate support for each different MCX service i.e. MCPTT, MC Video and MC Data.

[0589] 4. (808) [Conditional] T-AMF to SMF: Nsmf_PDUSession_UpdateSMContext (PDU Session ID, Target ID,

T-AMF ID, N2 SM Information).

[0590] For each PDU Session indicated by S-RAN, the AMF invokes the Nsmf_PDUSession_UpdateSMContext Request to the associated SMF. However, if the S-NSSAI associated with PDU Session is not available in the T-AMF, the T-AMF does not invoke Nsmf_PDUSession_UpdateSMContext for this PDU Session.

[0591] PDU Session ID indicates a PDU Session candidate for N2 Handover. Target ID corresponds to Target ID provided by S-RAN in step 1. SM N2 Info includes the Direct Forwarding Path Availability if the direct data forwarding is available between the S-RAN and the T-RAN and has been inserted by the S-RAN.

[0592] If the (T-)AMF detects that the UE moves into a non-allowed area based on Service area restrictions, the (T )AMF notifies each NF consumer which has subscribed for UE reachability event (e.g. SMFs corresponding to the list of PDU Sessions received in UE Context from (S-)AMF via Namf_EventExposure_Notify that the UE is only reachable for regulatory prioritized services.

[0593] 5. (809) [Conditional] Based on the Target ID, SMF checks if N2 Handover for the indicated PDU Session can be accepted. The SMF checks also the UPF Selection Criteria according to clause 6.3.3 of TS 23.501 [2], If UE has moved out of the service area of the UPF connecting to NG-RAN, SMF selects a new intermediate UPF. If redundant transmission is performed for one or more QoS Flows of the PDU Session, the SMF selects two new Intermediate UPFs to support the redundant transmission based on two N3 and N9 tunnels between the T-RAN and the UPF (PSA) as described in clause 5.33.2.2 of TS 23.501 [2], In this case, step 6c and 6d are performed between SMF and each T-UPF. [0594] In the case that the SMF fails to find a suitable l-UPF, the SMF decides to (based on local policies) either:

[0595] -trigger re-establishment of PDU Session. After handover procedure, SMF sends N1 message to the UE via the AMF by invoking Namf_Communication_N1 N2MessageTransfer containing the cause indicating PDU Session reestablishment is required for the UE; or

[0596] -keep the PDU Session, but reject the activation request of User Plane connection for the PDU Session and inform the AMF about it; or

[0597] -release the PDU Session after handover procedure.

[0598] 6a. (810) [Conditional] SMF to UPF (PSA): N4 Session Modification Request.

[0599] If the SMF selects a new UPF to act as intermediate UPF for the PDU Session and the different CN Tunnel Info need be used, the SMF sends N4 Session Modification Request message to UPF (PSA). The SMF provides the CN Tunnel Info (on N9) if the CN Tunnel Info is allocated by the SMF and UL Packet detection rules associate the CN Tunnel Info (on N9) to be installed on the UPF (PSA).

[0600] If redundant transmission is performed for one or more QoS Flows of the PDU Session and the different CN Tunnel Info need be used, the SMF provides two CN Tunnel Info (on N9) to the UPF (PSA) if the CN Tunnel Info is allocated by the SMF and indicates to the UPF (PSA) one of the CN Tunnel Info is used as redundancy tunnel of the PDU Session.

[0601] 6b. (812) [Conditional] UPF (PSA) to SMF: N4 Session Modification Response.

[0602] The UPF (PSA) sends an N4 Session Modification Response message to the SMF. If the UPF (PSA) allocates CN Tunnel Info (on N9) of UPF (PSA), it provides CN Tunnel Info (on N9) to the SMF. If redundant transmission is performed for one or more QoS Flows of the PDU Session, the UPF (PSA) provides two CN Tunnel Info (on N9) of UPF (PSA) to the SMF and indicates the SMF that one CN Tunnel Info is used as redundancy tunnel of the PDU Session as described in in clause 5.33.2.2 of TS 23.501 [2], The UPF (PSA) associate the CN Tunnel Info (on N9) with UL Packet detection rules provided by the SMF.

[0603] 6c. (814) [Conditional] SMF to T-UPF (intermediate): N4 Session Establishment Request.

[0604] If the SMF selects a new intermediate UPF, i.e. the target UPF (T-UPF), for the PDU Session and if CN

Tunnel Info is allocated by the T-UPF, an N4 Session Establishment Request message is sent to the T-UPF, providing Packet detection, enforcement and reporting rules to be installed on the T-UPF. The CN Tunnel Info (on N9) of UPF (PSA) for this PDU Session, which is used to setup N9 tunnel, is also provided to the T-UPF.

[0605] 6d. (816) T-UPF (intermediate) to SMF: N4 Session Establishment Response. [0606] The T-UPF sends an N4 Session Establishment Response message to the SMF with DL CN Tunnel Info and UL CN Tunnel Info (i.e. N3 tunnel info). The SMF starts a timer to release the resource of S-UPF, which is to be used in step 13a of the Execution Phase.

[0607] 7. (818) SMF to T-AMF: Nsmf_PDUSession_UpdateSMContext Response (PDU Session ID, N2 SM

Information, Reason for non-acceptance).

[0608] If N2 handover for the PDU Session is accepted, the SMF includes in the Nsmf_PDUSession_UpdateSMContext response the N2 SM Information containing the N3 UP address and the UL CN Tunnel ID of the UPF, the QoS parameters, TSCAI and the User Plane Security Enforcement information for the Target NG-RAN. If redundant transmission is performed for one or more QoS Flows of the PDU Session, two UL CN Tunnel Info are included in the N2 SM Information. If the N2 SM information received at step 4 does not include the Direct Forwarding Path Availability and the SMF knows that there is no indirect data forwarding connectivity between source and target, the N2 SM Information includes a Data forwarding not possible indication. If the SMF indicated that Direct Forwarding is available in step 4, the SMF should further include a "Direct Forwarding Path Availability" indication in the N2 SM information container. The SMF sends the Alternative QoS Profiles (see TS 23.501 [2]) to the Target NG-RAN on a per QoS Flow basis, if available.

[0609] If N2 handover for the PDU Session is not accepted as described in step 5, the SMF does not include an N2 SM Information regarding the PDU Session to avoid establishment of radio resources at the target NG-RAN. Instead of that, the SMF provides a reason for non-acceptance. If the SMF has received notification from (T-)AMF that the UE is only reachable for regulatory prioritized services, the SMF does not include any N2 SM info regarding the PDU Session for non-regulatory prioritized services to avoid establishment of radio resources at the target NG-RAN. If the SMF receives notification from (T-)AMF that UE is only reachable for regulatory prioritized service after this step via Namf_EventExposure_Notify, the SMF deactivates the PDU Session after handover procedure finish if the PDU Session is not for regulatory prioritized services.

[0610] 8. (820) AMF supervises the Nsmf_PDUSession_UpdateSMContext Response messages from the involved

SMFs. The lowest value of the Max delay indications for the PDU Sessions that are candidates for handover gives the maximum time AMF may wait for Nsmf_PDUSession_UpdateSMContext Response messages before continuing with the N2 Handover procedure. At expiry of the maximum wait time or when all Nsmf_PDUSession_UpdateSMContext Response messages are received, AMF continues with the N2 Handover procedure (Handover Request message in step 9).

[0611] NOTE: The delay value for each PDU Session is locally configured in the AMF and implementation specific. [0612] 9. (822) T -AMF to T-RAN: Handover Request (Source to Target transparent container (NEW: including MCX

5GC Support Indication), N2 MM Information, N2 SM Information list, Tracing Requirements, UE Radio Capability ID, NEW: MCX 5GC Support Indication). If the subscription information includes Tracing Requirements, the target AMF provides the target RAN with Tracing Requirements in the Handover Request. [0613] T-AMF determines T-RAN based on Target ID. T-AMF may allocate a 5G-GUTI valid for the UE in the AMF and target TAI.

[0614] Source to Target transparent container is forwarded as received from S-RAN. N2 MM Information includes e.g. security information and Mobility Restriction List if available in the T-AMF NEW: and MCX 5GC Support Indication. If Handover Request includes MCX 5GC Support Indication, including an indicator for 5GC support for MCX or not, RAN shall store it and use it for mobility reasons e.g. trigger MCX fallback. MCX Support Indication indicates separate support for each different MCX service i.e. MCPTT, MC Video and MC Data..

[0615] N2 SM Information list includes N2 SM Information received from SMFs for the T-RAN in the Nsmf_PDUSession_UpdateSMContext Response messages received within allowed max delay supervised by the T-AMF mentioned in step 8.

[0616] T-AMF provides the UE Radio Capability ID to T-RAN if RAGS is supported. If the UE Radio Capability ID is included in the Handover Request message and no UE radio access capabilities are provided in the Source to Target transparent container, when there is no corresponding UE radio capabilities set for UE Radio Capability ID at T-RAN, T- RAN shall request the T-AMF to provide the UE radio capabilities set corresponding to UE Radio Capability ID to the T- RAN. If the Source to Target transparent container contains the UE radio access capabilities and the T-RAN did not receive the UE Radio Capability ID from the T-AMF, NG-RAN shall proceed with handover using the received UE radio access capabilities. If the T-RAN received both the UE radio access capabilities and the UE Radio Capability ID, then the T-RAN shall use any locally stored UE radio access capability information corresponding to the UE Radio Capability ID. If none are stored locally, the T-RAN may request the full UE radio access capability information from the core network. If the full UE radio access capability information is not promptly received from the core network, or the T-RAN chooses not to request them, then the T-RAN shall proceed with the UE radio access capabilities sent by the source RAN node. The T-RAN shall not use the UE radio access capability information received from the source RAN node for any other UE with the same the UE Radio Capability ID.

[0617] NEW: If Handover Request includes MCX 5GC Support Indication, including an indicator for 5GC support for MCX or not, RAN shall store it and use it for mobility reasons e.g. trigger MCX fallback. MCX Support Indication indicates separate support for each different MCX service i.e. MCPTT, MC Video and MC Data. MCX 5GC Support Indication is either included as a separate indication or as part of Source to Target transparent container.

[0618] 10. (824) T-RAN to T-AMF: Handover Request Acknowledge (Target to Source transparent container, List of PDU Sessions to Hand-over with N2 SM information, List of PDU Sessions that failed to be established with the failure cause given in the N2 SM information element).

[0619] Target to Source transparent container includes a UE container with an access stratum part and a NAS part. The UE container is sent transparently via T-AMF, S-AMF and S-RAN to the UE. If DAPS handover is supported by the T- RAN and T-AMF and the DAPS Information for one or more DRBs had been received in the Source to Target Transparent Container, the T-RAN includes the DAPS Response information in the Target to Source Transparent Container as described in TS 38.300 [9],

[0620] T-RAN creates List Of PDU Sessions failed to be setup and reason for failure (e.g. T-RAN decision, S- NSSAI is not available, unable to fulfil User Plane Security Enforcement) based on T-RAN determination. The information is provided to the S-RAN.

[0621] The N2 SM information in the List Of PDU Sessions to Hand-over, contains per each PDU Session ID T- RAN N3 addressing information i.e. N3 UP address and Tunnel ID of T-RAN for the PDU Session.

[0622] If redundant transmission is performed for one or more QoS Flows of the PDU Session, the T-RAN provides two AN Tunnel Info for the PDU Session in the N2 SM information. The T-RAN indicates to the SMF one of the AN Tunnel Info is used as the redundancy tunnel of the PDU session as described in clause 5.33.2.2 of TS 23.501 [2], If only one AN Tunnel Info is provided by the Target NG-RAN for the PDU session, the SMF may release these QoS Flows by triggering PDU Session Modification procedure as specified in clause 4.3.3 after the handover procedure.

[0623] The N2 SM information may also include:

[0624] -an Indication whether UP integrity protection is performed or not on the PDU Session based on User Plane Security Enforcement information received in N2 SM information in step 9.

[0625] -if the PDU Session has at least one QoS Flow subject for data forwarding, N3 UP address and Tunnel ID of T-RAN for receiving forwarded data. The T-RAN provides data forwarding addresses for each data forwarding tunnel which it decided to setup.

[0626] -For each QoS Flow accepted with an Alternative QoS Profile (see TS 23.501 [2]), the Target NG-RAN shall include a reference to the fulfilled Alternative QoS Profile.

[0627] 11a. (826) AMF to SMF: Nsmf_PDUSession_UpdateSMContext Request (PDU Session ID, N2 SM response received from T-RAN in step 10).

[0628] For each N2 SM response received from the T-RAN (N2 SM information included in Handover Request Acknowledge), AMF sends the received N2 SM response to the SMF indicated by the respective PDU Session ID. [0629] If no new T-UPF is selected, SMF stores the N3 tunnel info of T-RAN from the N2 SM response if N2 handover is accepted by T-RAN.

[0630] The SMF/UPF allocates the N3 UP address and Tunnel IDs for indirect data forwarding corresponding to the data forwarding tunnel endpoints established by T-RAN.

[0631] If a PDU Session is indicated as a rejected PDU Session by the Target NG-RAN with an indication that the PDU session was rejected because User Plane Security Enforcement is not supported in the Target NG-RAN and the User Plane Enforcement Policy indicates "Required" as described in clause 5.10.3 of TS 23.501 [2], the SMF triggers the release of this PDU Session. In all other cases of PDU Session rejection, the SMF can decide whether to release the PDU Session (possibly triggering the re-establishment of the PDU Session as described in step 5) or to deactivate the UP connection of this PDU Session. [0632] If some of the QoS Flows of a PDU Session are not accepted by the Target NG-RAN, the SMF shall initiate the PDU Session Modification procedure to remove the non-accepted QoS Flows from the PDU Session(s) after the handover procedure is completed.

[0633] 11b. (828) [Conditional] SMF to T-UPF: N4 Session Modification Request (T-RAN SM N3 forwarding

Information list, indication to allocate DL forwarding tunnel(s) for indirect forwarding)

[0634] If the SMF selected a T-UPF in step 6a, the SMF updates the T-UPF by providing the T-RAN SM N3 forwarding information list by sending a N4 Session Modification Request to the T-UPF.

[0635] If indirect forwarding applies based on indication from the S-RAN and the UPF is re-allocated and if the SMF decides to setup the indirect forwarding tunnel on the same T-UPF, the SMF also requests in the N4 Session Modification Request message to the T-UPF, to allocate DL forwarding tunnel(s) for indirect forwarding.

[0636] Indirect forwarding may be performed via a UPF which is different from the T-UPF, in which case the SMF selects a T-UPF for indirect forwarding.

[0637] 11c. (830) [Conditional] T-UPF to SMF: N4 Session Modification Response (T-UPF SM N3 forwarding

Information list).

[0638] The T-UPF allocates Tunnel Info and returns an N4 Session Modification Response message to the SMF.

[0639] The T-UPF SM N3 forwarding info list includes T-UPF N3 address, T-UPF N3 Tunnel identifiers for forwarding data

[0640] 11 d. (832) [Conditional] SMF to S-UPF: N4 Session Modification Request (T-RAN SM N3 forwarding

Information list or T-UPF SM N3 forwarding Information list, indication to allocate DL forwarding tunnel(s) for indirect forwarding).

[0641] If the UPF is re-allocated, this message includes the T-UPF SM N3 forwarding info list. If the UPF is not reallocated, this message includes the T-RAN SM N3 forwarding info list.

[0642] If indirect forwarding applies based on indication from NG-RAN and UPF allocates tunnel identities, the SMF indicates in the N4 Session Modification Request message to the S-UPF to allocate DL forwarding tunnel(s) for indirect forwarding.

[0643] Indirect forwarding may be performed via a UPF which is different from the S-UPF.

[0644] 11e. (834) [Conditional] S-UPF to SMF: N4 Session Modification Response (S-UPF SM N3 forwarding

Information list).

[0645] The S-UPF allocates Tunnel Info and returns an N4 Session establishment Response message to the SMF.

[0646] The S-UPF SM N3 forwarding Information list includes S-UPF N3 address, S-UPF N3 Tunnel identifiers for

DL data forwarding.

[0647] 11 f. (836) SMF to T-AMF: Nsmf_PDUSession_UpdateSMContext Response (N2 SM Information).

[0648] The SMF sends an Nsmf_PDUSession_UpdateSMContext Response message per PDU Session to T-AMF. [0649] The SMF creates an N2 SM information containing the DL forwarding Tunnel Info to be sent to the S-RAN by the AMF. The SMF includes this information in the Nsmf_PDUSession_UpdateSMContext response. The DL forwarding Tunnel Info can be one of the following information:

[0650] -If direct forwarding applies, then the SMF includes the T-RAN N3 forwarding information the SMF received in step 11a.

[0651] -If the indirect forwarding tunnel is setup in step 11b or 11d, then the SMF includes the T-UPF or S-UPF DL forwarding information containing the N3 UP address and the DL Tunnel ID of the UPF.

[0652] 12. (838) [Conditional] T-AMF to S-AMF: Namf_Communication_CreateUEContext Response (N2 information necessary for S-AMF to send Handover Command to S-RAN including Target to Source transparent container, PDU Sessions failed to be setup list, N2 SM information (N3 DL forwarding Information, PCF ID), [Target AMF ID]).

[0653] T-AMF supervises the Nsmf_PDUSession_UpdateSMContext Response message from the involved SMFs. At expiry of the maximum wait time or when all Nsmf_PDUSession_UpdateSMContext Response messages are received, T-AMF sends the Namf_Communication_CreateUEContext Response to the S-AMF.

[0654] The PDU Sessions failed to be setup list includes the List Of PDU Sessions failed to be setup received from target RAN in step 10 and the Non-accepted PDU session List generated by the T-AMF.

[0655] Non-accepted PDU Session List includes following PDU Session(s) with proper cause value:

[0656] -Non-accepted PDU Session(s) by the SMF(s);

[0657] -Non-accepted PDU Session(s) by the AMF due to no response from the SMF within maximum wait time; and

[0658] -Non-accepted PDU Session(s) by the AMF due to non-available S-NSSAI in the T-AMF, which is decided at step 4.

[0659] The Target to Source transport container is received from the T-RAN. The N2 SM Information is received from the SMF in step 11f.

[0660] If target AMF re-allocation is executed in step 3, the selected final target AMF, i.e. T-AMF, invoke Namf_Communication_RelocateUEContext Response (Cause, N2 information necessary for S-AMF to send Handover Command to S-RAN including Target to Source transparent container, N2 SM information (PDU Sessions failed to setup list, N3 DL forwarding Information), PCF ID, PCF reselected indication, target AMF ID) to the initial AMF. The cause indicates whether the Relocate UE Context (hand-Over) succeeded or failed. If the target NG RAN has rejected the Handover Request in step 10, the cause indicates a failure due to RAN rejection. The target AMF ID is used for S-AMF to transfer RAN Status to T-AMF directly. Based on the receiving Namf_Communication_RelocateUEContext Response, the initial AMF invokes Namf_Communication_CreateUEContext Response. Figure 9

[0661] Figure 9 corresponds to TS 23.502 Figure 4.9.1.3.3-1 of section 4.9.1.3.3 Execution Phase, and the following steps relate to Figure 9.

[0662] 1 . (902) S-AMF to S-RAN: Handover Command (Target to Source transparent container, List Of PDU

Sessions to be handed-over with N2 SM information containing information received from T-RAN during the handover preparation phase, List Of PDU Sessions failed to be setup).

[0663] Target to Source transparent container is forwarded as received from S-AMF. If DAPS Response information for one or more DRBs is received by S-RAN and indicates that DAPS handover is accepted, the execution phase for DAPS handover procedure as described in clause 4.9.1.3.3a is performed.

[0664] The SM forwarding info list includes T-RAN SM N3 forwarding info list for direct forwarding or S-UPF SM N3 forwarding info list for indirect data forwarding

[0665] S-RAN uses the PDU Sessions failed to be setup list and the indicated reason for failure to decide whether to proceed with the N2 Handover procedure.

[0666] If the S-RAN supports and receives a reference to an Alternative QoS Profile for an accepted QoS Flow, it shall take it into account for deciding whether or not to proceed with the N2 Handover procedure (see TS 23.501 [2]). [0667] 2. (904) S-RAN to UE: Handover Command (UE container).

[0668] UE container is a UE part of the Target to Source transparent container which is sent transparently from T- RAN via AMF to S-RAN and is provided to the UE by the S-RAN.

[0669] 2a (906). If the PLMN has configured secondary RAT usage reporting and the source NG-RAN has

Secondary RAT usage data to report, the source NG-RAN node may provide RAN usage data report message (N2 SM Information (Secondary RAT usage data), Handover Flag) as in clause 4.21 to the AMF. The Handover Flag indicates to the AMF that it should buffer the N2 SM Information containing the usage data report before forwarding it.

[0670] NOTE 2:This step is not shown in this figure but the secondary RAT usage data reporting procedure is shown in figure 4.21-1 in clause 4.21.

[0671] 2a. - 2c. (906-910)The S-RAN sends the Uplink RAN Status Transfer message to the S-AMF, as specified in

TS 36.300 [46] and TS 38.300 [9], The S-RAN may omit sending this message if none of the radio bearers of the UE shall be treated with PDCP status preservation.

[0672] If there is an AMF relocation, the S-AMF sends this information to the T-AMF via the Namf_Communication_N1 N2MessageTransfer service operation and the T-AMF acknowledges. The S-AMF or, if the AMF is relocated, the T-AMF, sends the information to the T-RAN via the Downlink RAN Status Transfer message, as specified in TS 36.300 [46] and TS 38.300 [9],

[0673] For Inter PLMN handover, if the target AMF has been relocated in Preparation phase, e.g. due to the inter PLMN handover, the S-AMF send this information to the indicated T-AMF, which is derived from the target AMF ID received in step 12 of clause 4.9.1.3.2. [0674] 3. (912-914) Uplink packets are sent from T-RAN to T-UPF and UPF (PSA). Downlink packets are sent from

UPF (PSA) to S-RAN via S-UPF. The S-RAN should start forwarding of downlink data from the S-RAN towards the T- RAN for QoS Flows or DRBs subject to data forwarding. This may be either direct (step 3a) or indirect forwarding (step 3b).

[0675] 4. (916) UE to T-RAN: Handover Confirm.

[0676] After the UE has successfully synchronized to the target cell, it sends a Handover Confirm message to the T-RAN. Handover is by this message considered as successful by the UE.

[0677] 5. (918) T-RAN to T-AMF: Handover Notify.

[0678] Handover is by this message considered as successful in T-RAN.

[0679] 6a. (920) [Conditional] T-AMF to S-AMF: Namf_Communication_N2lnfoNotify.

[0680] The T-AMF notifies to the S-AMF about the N2 handover notify received from the T-RAN by invoking the Namf_Communication_N2lnfoNotify.

[0681] A timer in S-AMF is started to supervise when resources in S-RAN shall be release.

[0682] 6b. (922) [Conditional] S-AMF to T-AMF: Namf_Communication_N2lnfoNotify ACK (N2 SM Information

(Secondary RAT usage data)).

[0683] The S-AMF acknowledges by sending the Namf_Communication_N2lnfoNotify ACK to the T-AMF. The N2 SM Information here is the one buffered at step 2a0 when applicable.

[0684] 6c. (924) [Conditional] S-AMF to SMF: Nsmf_PDUSession_ReleaseSMContext Request (SM Context ID,

N2 SM Information (Secondary RAT Usage Data)).

[0685] If the PDU Session(s) is not accepted by the T-AMF (e.g. S-NSSAI associated with the PDU Session is not available in the T-AMF), S-AMF triggers PDU Session Release procedure as specified in clause 4.3.4.2 after the S-AMF is notified for the reception of N2 Handover Notify in step 6a.

[0686] 7. (926) T-AMF to SMF: Nsmf_PDUSession_UpdateSMContext Request (Handover Complete indication for

PDU Session ID, UE presence in LADN service area, N2 SM Information (Secondary RAT usage data)). The N2 SM Information here is the one received at step 6b when applicable.

[0687] Handover Complete indication is sent per each PDU Session to the corresponding SMF to indicate the success of the N2 Handover.

[0688] When an Nsmf_PDUSession_UpdateSMContext Response message arrived too late during the handover preparation phase (see step 8 of clause 4.9.1.3.2), or the PDU Session with SMF involvement is not accepted by T-RAN, Nsmf_PDUSession_UpdateSMContext Request (SM Context ID, Operation Type) is sent to the corresponding SMF allowing the SMF to deallocate a possibly allocated N3 UP address and Tunnel ID of the selected UPF. A PDU Session handled by that SMF is considered deactivated and handover attempt is terminated for that PDU Session.

[0689] In the case that the AMF determines that the PDU Session is related to a LADN then the AMF provides the "UE presence in LADN service area". If the AMF does not provide the "UE presence in LADN service area" indication and the SMF determines that the DNN corresponds to a LADN, then the SMF considers that the UE is OUT of the LADN service area.

[0690] The SMF takes actions for the LADN PDU Session as defined in clause 5.6.5 of TS 23.501 [2] based on the "UE presence in LADN service area" indication.

[0691] For each QoS Flow for which the SMF has received a reference to the fulfilled Alternative QoS Profile in step 10 of clause 4.9.1.3.2, the SMF notifies the PCF and the UE as described in TS 23.501 [2], [0692] 8a. (928) [Conditional] SMF to T-UPF (intermediate): N4 Session Modification Request.

[0693] If new T-UPF is inserted or an existing intermediate S-UPF is re-allocated, the SMF shall send N4 Session

Modification Request indicating DL AN Tunnel Info of T-RAN to the T-UPF.

[0694] 8b. (930) [Conditional] T-UPF to SMF: N4 Session Modification Response.

[0695] The T-UPF acknowledges by sending N4 Session Modification Response message to SMF.

[0696] 9a. (932) [Conditional] SMF to S-UPF (intermediate): N4 Session Modification Request.

[0697] If UPF is not re-allocated, the SMF shall send N4 Session Modification Request indicating DL AN Tunnel Info of T-RAN to the S-UPF.

[0698] 9b. (934) [Conditional] S-UPF to SMF: N4 Session Modification Response.

[0699] The S-UPF acknowledges by sending N4 Session Modification Response message to SMF.

[0700] 10a. (936) [Conditional] SMF to UPF (PSA): N4 Session Modification Request.

[0701] For non-roaming or local breakout roaming scenario, the SMF sends N4 Session Modification Request message to PDU Session Anchor UPF, UPF (PSA), providing N3 AN Tunnel Info of T-RAN or the DL CN Tunnel Info of T-UPF if a new T-UPF is inserted or an existing intermediate S-UPF is re-allocated. If redundant transmission is performed for one or more QoS Flows of the PDU Session, two N3 AN Tunnel Info of T-RAN or two DL CN Tunnel Info of two T-UPFs are provided and the SMF indicates to the UPF (PSA) one of the AN/CN Tunnel Info is used as redundancy tunnel of the PDU Session. If the existing intermediate S-UPF terminating N9 toward the H-UPF (PDU Session Anchor) is re-allocated for the home routed roaming scenario, the V-SMF invokes an Nsmf_PDUSession_Update Request (DL CN Tunnel Info) service operation toward the H-SMF.

[0702] In the case of the S-UPF acts as a UL CL or BP, the SMF indicates only one of the PDU Session Anchors to send the "end marker" packets. To ensure the "end marker" is the last user plane packet on the old path, the SMF should modify the path on other PDU Session Anchors before it indicates the PDU Session Anchor to send the "end marker" packets.

[0703] If T-UPF is not inserted or an existing intermediate S-UPF is not re-allocated, step 10a and step 10b are skipped.

[0704] 10b. (938) [Conditional] UPF (PSA) to SMF: N4 Session Modification Response.

[0705] The UPF (PSA) sends N4 Session Modification Response message to SMF. In order to assist the reordering function in the T-RAN, the UPF (PSA) sends one or more "end marker" packets for each N3 tunnel on the old path immediately after switching the path, the source NG-RAN shall forward the "end marker" packets to the target NG- RAN. At this point, UPF (PSA) starts sending downlink packets to the T-RAN, via T-UPF if a new T-UPF is inserted or an existing intermediate S-UPF is re-allocated. In the case of home routed roaming scenario, the H-SMF responds with the Nsmf_PDUSession_Update Response service operation to V-SMF once the H-UPF (PDU Session Anchor) is updated with the UL Tunnel Info of the T-UPF.

[0706] When there are multiple UPFs(PSA), step 10a and step 10b are performed for each UPFs(PSA).

[0707] 11 . (940) SMF to T-AMF: Nsmf_PDUSession_UpdateSMContext Response (PDU Session ID).

[0708] SMF confirms reception of Handover Complete.

[0709] If indirect data forwarding applies, the SMF starts an indirect data forwarding timer, to be used to release the resource of indirect data forwarding tunnel.

[0710] 12. (942) The UE initiates Mobility Registration Update procedure as described in clause 4.2.2.2.2.

[0711] The target AMF knows that it is a Handover procedure and therefore the target AMF performs only a subset of the Registration procedure, specifically the steps 4, 5 and 10 in the Registration procedure for the context transfer between source AMF and target AMF are skipped.

[0712] The target AMF, based on the S-NSSAIs subject to Network Slice-Specific Authentication and Authorization status information from source AMF in step 3 of clause 4.9.1 .3.2, may decide to skip step 25 in the Registration procedure (i.e. NSSAA procedure) or whether to perform it if the status is pending.

[0713] 13a. (944) [Conditional] SMF to S-UPF (intermediate): N4 Session Release Request.

[0714] If there is a source intermediate UPF, the SMF initiates resource release, after timer in step 6 or indirect data forwarding timer expires, by sending an N4 Session Release Request (Release Cause) to source UPF. This message is also used to release the indirect data forwarding resource in S-UPF.

[0715] 13b. (946) S-UPF to SMF: N4 Session Release Response.

[0716] The S-UPF acknowledges with an N4 Session Release Response message to confirm the release of resources.

[0717] In the case of indirect data forwarding, the resource of indirect data forwarding is also released.

[0718] 14a. (948) AMF to S-RAN: UE Context Release Command ().

[0719] After the timer in step 6a expires, the AMF sends UE Context Release Command.

[0720] 14b. (950) S-RAN to AMF: UE Context Release Complete ().

[0721] The source NG-RAN releases its resources related to the UE and responds with a UE Context Release

Complete () message.

[0722] 15a. (952) [Conditional] SMF to T-UPF: N4 Session Modification Request.

[0723] If indirect forwarding applies and UPF is re-allocated, after timer of indirect data forwarding expires, the SMF sends N4 Session Modification Request to T-UPF to release the indirect data forwarding resource.

[0724] 15b. (954) [Conditional] T-UPF to SMF: N4 Session Modification Response. [0725] The T-UPF acknowledges with an N4 Session Modification Response message to confirm the release of indirect data forwarding resources.

[0726] If the AMF is subscribed to Mobility Event by other NFs, the AMF notifies the event to the corresponding NFs by invoking the Namf_EventExposure_Notify service operation as described in clause 4.15.4.2.

[0727] Upon reception of the Namf_EventExposure_Notify with an indication that UE is reachable only for regulatory prioritized service, the SMF deactivates the PDU Session if the service of the PDU Session is not regulatory prioritized. For home routed roaming case, the V-SMF triggers the deactivation of the PDU Session, in addition, the H- SMF refrains from sending downlink signalling if the signalling is not related to regulatory prioritized service upon receiving the notification.

Implementation examples

[0728] In the tables below, which are adopted from 38.413 v17.1.1, the additional portions that are disclosed herein, and not included in TS 38.413 v17.1.1 are underlined. The clauses relate to 23.502 4.3.3 PDU Session Modification above.

[0729] NG-AP message PDU SESSION RESOURCE MODIFY REQUEST (clause 9.2.1.5) includes PDU Session Resource Modify Request Transfer IE (clause 9.3.4.3).

[0730] PLEASE NOTE: Below are some examples of NG-AP messages impacted. In some cases, also other NG- AP messages are impacted where the similar changes are proposed. Also, impact on S1-AP (i.e. messages applicable in 4G between MME and RAN) are impacted in the same way that are proposed for NG-AP.

[0731] PLEASE NOTE that also PDU SESSION RESOURCE SETUP REQUEST may as an alternative also be impacted in the similar way as for PDU SESSION MODIFY REQUEST message.

9.2.1.5 PDU SESSION RESOURCE MODIFY REQUEST

This message is sent by the AMF and is used to request the NG-RAN node to enable modifications of already established PDU session resources for a given UE.

Direction: AMF ® NG-RAN node

9, 3,1. XX MCX 5GC Support Indicator

The IE indicates 5GC support for MCX.

9.3.4.3 PDU Session Resource Modify Request Transfer

This IE is transparent to the AMF.

9.3.1.X UE NAS 5QI Status Indicator

The IE indicates UE NAS Status Indicator. [0732] The clause relates to 23.502 4.2.3.2 UE Triggered Service Request above. The procedure can be triggered either as a standalone procedure or by triggered Network triggered Service Request (clause 4.2.3.3 in 23.502).

[0733] PLEASE NOTE that the proposed change in INITIAL CONTEXT SETUP REQUEST also can be sent in other NG-AP messages e.g. DOWNLINK NAS TRANSPORT, UE CONTEXT MODIFICATION REQUEST. 9.2.2.1 INITIAL CONTEXT SETUP REQUEST

This message is sent by the AMF to request the setup of a UE context.

Direction: AMF ® NG-RAN node

[0734] The clauses (HANDOVER REQUEST and HANDOVER REQUIRED) relate to 23.502 4.9.1.3 Inter NG-RAN node N2 based handover above.

[0735] Please Note: ‘MCX 5GC Support Indicator' can be included in HANDOVER REQUEST either as a separate parameter or as part of the transparent container. The separate parameter can be found in the end of the message and the transparent container as part of Source to Target Transparent Container. Both marked in underline text below.

9.2.3.4 HANDOVER REQUEST This message is sent by the AMF to the target NG-RAN node to request the preparation of resources.

Direction: AMF ® NG-RAN node.

9.2.3.1 HANDOVER REQUIRED

This message is sent by the source NG-RAN node to the AMF to request the preparation of resources at the target. Direction: NG-RAN node ® AMF.

Figure 10

[0736] Figure 10 is a schematic block diagram of a network node 1000 according to some embodiments of the present disclosure. Optional features are represented by dashed boxes. The network node 1000 may be, for example, a base station 202 or 206 or a network node that implements all or part of the functionality of the base station 202 or gNB described herein. The network node 1000 may alternatively be a network node that implements an NF of the core network such as, e.g., an AMF, SMF, PCF, or the like. As illustrated, the network node 1000 includes a control system 1002 that includes one or more processors 1004 (e.g., Central Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), and/or the like), memory 1006, and a network interface 1008. The one or more processors 1004 are also referred to herein as processing circuitry. In addition, if the network node 1000 is a base station or other radio access node, the network node 1000 may include one or more radio units 1010 that each includes one or more transmitters 1012 and one or more receivers 1014 coupled to one or more antennas 1016. The radio units 1010 may be referred to or be part of radio interface circuitry. In some embodiments, the radio unit(s) 1010 is external to the control system 1002 and connected to the control system 1002 via, e.g., a wired connection (e.g., an optical cable). However, in some other embodiments, the radio unit(s) 1010 and potentially the antenna(s) 1016 are integrated together with the control system 1002. The one or more processors 1004 operate to provide one or more functions of the network node 1000 as described herein (e.g., one or more functions of a RAN node or core network NF described herein). In some embodiments, the function(s) are implemented in software that is stored, e.g., in the memory 1006 and executed by the one or more processors 1004.

Figure 11

[0737] Figure 11 is a schematic block diagram that illustrates a virtualized embodiment of the network node 1000 according to some embodiments of the present disclosure. This discussion is equally applicable to other types of network nodes. Further, other types of network nodes may have similar virtualized architectures. Again, optional features are represented by dashed boxes.

[0738] As used herein, a "virtualized” network node is an implementation of the network node 1000 in which at least a portion of the functionality of the network node 1000 is implemented as a virtual component(s) (e.g., via a virtual machine(s) executing on a physical processing node(s) in a network(s)). As illustrated, the network node 1000 includes one or more processing nodes 1100 coupled to or included as part of a network(s) 1102. Each processing node 1100 includes one or more processors 1104 (e.g., CPUs, ASICs, FPGAs, and/or the like), memory 1106, and a network interface 1108. If the network node 1000 is a base station or other radio access node, the network node 1000 may also include the control system 1002 and/or the one or more radio units 1010, as described above. The control system 1002 may be connected to the radio unit(s) 1010 via, for example, an optical cable or the like. If present, the control system 1002 or the radio unit(s) are connected to the processing node(s) 1100 via the network 1102.

[0739] In this example, functions 1110 of the network node 1000 described herein are implemented at the one or more processing nodes 1100 or distributed across the one or more processing nodes 1100 and the control system 1002 and/or the radio unit(s) 1010 in any desired manner. In some particular embodiments, some or all of the functions 1110 of the network node 1000 described herein are implemented as virtual components executed by one or more virtual machines implemented in a virtual environment(s) hosted by the processing node(s) 1100. As will be appreciated by one of ordinary skill in the art, additional signaling or communication between the processing node(s) 1100 and the control system 1002 may be used in order to carry out at least some of the desired functions 1110. Notably, in some embodiments, the control system 1002 may not be included, in which case the radio unit(s) 1010, if present, may communicate directly with the processing node(s) 1100 via an appropriate network interface(s).

[0740] In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of the network node 1000 or a node (e.g., a processing node 1100) implementing one or more of the functions 1110 of the network node 1000 in a virtual environment according to any of the embodiments described herein is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).

Figure 12

[0741] Figure 12 is a schematic block diagram of the network node 1000 according to some other embodiments of the present disclosure. The network node 1000 includes one or more modules 1200, each of which is implemented in software. The module(s) 1200 provide the functionality of the network node 1000 described herein. This discussion is equally applicable to the processing node 1100 of Figure 11 where the modules 1200 may be implemented at one of the processing nodes 1100 or distributed across multiple processing nodes 1100 and/or distributed across the processing node(s) 1100 and the control system 1002.

Figure 13

[0742] Figure 13 is a schematic block diagram of a wireless communication device 1300 according to some embodiments of the present disclosure. As illustrated, the wireless communication device 1300 includes one or more processors 1302 (e.g., CPUs, ASICs, FPGAs, and/or the like), memory 1304, and one or more transceivers 1306 each including one or more transmitters 1308 and one or more receivers 1310 coupled to one or more antennas 1312. The transceiver(s) 1306 includes radio-front end circuitry connected to the antenna(s) 1312 that is configured to condition signals communicated between the antenna(s) 1312 and the processor(s) 1302, as will be appreciated by on of ordinary skill in the art. The processors 1302 are also referred to herein as processing circuitry. The transceivers 1306 are also referred to herein as radio circuitry. In some embodiments, the functionality of the wireless communication device 1300 described above may be fully or partially implemented in software that is, e.g., stored in the memory 1304 and executed by the processor(s) 1302. Note that the wireless communication device 1300 may include additional components not illustrated in Figure 13 such as, e.g., one or more user interface components (e.g., an input/output interface including a display, buttons, a touch screen, a microphone, a speaker(s), and/or the like and/or any other components for allowing input of information into the wireless communication device 1300 and/or allowing output of information from the wireless communication device 1300), a power supply (e.g., a battery and associated power circuitry), etc.

[0743] In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of the wireless communication device 1300 according to any of the embodiments described herein is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).

Figure 14

[0744] Figure 14 is a schematic block diagram of the wireless communication device 1300 according to some other embodiments of the present disclosure. The wireless communication device 1300 includes one or more modules 1400, each of which is implemented in software. The module(s) 1400 provide the functionality of the wireless communication device 1300 described herein.

[0745] Any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses. Each virtual apparatus may comprise a number of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include Digital Signal Processor (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as Read Only Memory (ROM), Random Access Memory (RAM), cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and/or data communications protocols as well as instructions for carrying out one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according one or more embodiments of the present disclosure. [0746] While processes in the figures may show a particular order of operations performed by certain embodiments of the present disclosure, it should be understood that such order is exemplary (e.g., alternative embodiments may perform the operations in a different order, combine certain operations, overlap certain operations, etc.).

Summary of Various Embodiments

Some embodiments described above may be summarized in the following manner:

1 . A method of operation of a Policy Control Function, PCF, (310) of a wireless network for initiating a Session Management, SM, Policy Association Modification or Establishment for Mission Critical Services, MCX, the method comprising: providing (504) to a Session Management Function, SMF, (308) an MCX Support Indication that indicates whether the PCF (310) supports MCX on 5G system, 5GS.

2. The method of embodiment 1 , wherein the MCX Support Indication indicates respective support for each MCX service of the MCX services.

3. The method of embodiment 2, wherein the MCX services comprise Mission Critical Push to Talk, MCPTT, Mission Critical, MC, Video, and MC Data.

4. A method of operation of a Session Management Function, SMF, (308) of a wireless network for initiating a Session Management, SM, Policy Association Modification for Mission Critical Services, MCX, the method comprising: providing (526) to both a network node of a Radio Access Network, RAN, (202) and an Access and Mobility Management Function, AMF, (300) an MCX Support Indication that indicates whether a Policy Control Function, PCF, (310) and the SMF (308) support MCX on 5G System, 5GS.

5. The method of embodiment 4, wherein the MCX Support Indication indicates respective support for each MCX service of the MCX services.

6. The method of embodiment 5, wherein the MCX services comprise Mission Critical Push to Talk, MCPTT, Mission Critical, MC, Video, and MC Data.

7. The method of any of embodiments 4-6, wherein the MCX Support Indication comprises a single indicator that indicates whether the PCF (310) and the SMF (308) support MCX on the 5GS. 8. The method of any of embodiments 4-7, further comprising: receiving (550) a PDU Session Modification Command Acknowledgement or a PDU Session Establishment Accept NAS response message, from the UE (212) via the AMF (300); and providing (552, 553, 552b, 553) to the RAN via AMF (300) a User Equipment device, UE, (212) Non-Access Stratum, NAS, 5G Quality of Service Indicator, 5QI, indicating a NAS result from the UE (212) per each 5QI and a cause of a NAS modification.

9. A method of operation of an Access and Mobility Management Function, AMF, (300) of a wireless network for initiating a Session Management, SM, Policy Association Modification for Mission Critical Services, MCX, the method comprising: receiving (526), from a Session Management Function, SMF, (308) an MCX Support Indication that indicates whether a Policy Control Function, PCF, (310) and the SMF (308) support MCX on 5G System, 5GS; storing (526) the MCX Support Indication in a User Equipment device, UE, (212) context; and forwarding (532) the MCX Support Indication to a network node of a Radio Access Network, RAN, (202).

10. The method of embodiment 9, wherein the MCX Support Indication indicates respective support for each MCX service of the MCX services.

11. The method of embodiment 10, wherein the MCX services comprise Mission Critical Push to Talk, MCPTT, Mission Critical, MC, Video, and MC Data.

12. The method of any of embodiments 9-11, wherein the MCX Support Indication comprises a single indicator that indicates whether the PCF (310) and the SMF (308) support MCX on the 5GS.

13. The method of any of embodiments 9-12, wherein the forwarding (532) is in response to a handover preparation phase.

14. The method of any of embodiments 9-12, wherein the forwarding (532) is in response to the UE (212) performing mobility in handover preparation phase or in idle mode mobility.

15. The method of embodiment 9, wherein the forwarding (532) is in response to the UE (212) entering a Connection Management Connected, CM-Connected, state. 16. A method of operation of a network node of a Radio Access Network, RAN, (202) of a wireless network for initiating a Session Management, SM, Policy Association Modification or Establishment for Mission Critical Services, MCX, the method comprising: receiving (532) from an Access and Mobility Management Function, AMF, (300) an MCX Support Indication that indicates whether a Policy Control Function, PCF, (310) and a Session Management Function, SMF, (308) support MCX on 5G System 5GS; and storing (532) the MCX Support Indication in a User Equipment device, UE, (212) context.

17. The method of embodiment 16, wherein the MCX Support Indication indicates respective support for each MCX service of the MCX services.

18. The method of embodiment 17, wherein the MCX services comprise Mission Critical Push to Talk, MCPTT, Mission Critical, MC, Video, and MC Data.

19. The method of any of embodiments 16-18, further comprising: receiving (553) a User Equipment device, UE, (212) Non-Access Stratum, NAS, 5G Quality of Service Indicator, 5QI, indicating a NAS result from the UE (212) per each 5QI and a cause of a NAS modification.

20. A method of operation of an Access and Mobility Management Function, AMF, (300) of a wireless network for initiating a Session Management, SM, Policy Association Modification for Mission Critical Services, MCX, the method comprising: providing (634) to a network node of a Radio Access Network, RAN, (202) an MCX Support Indication that indicates whether a 5G Core Network, 5GC, supports MCX.

21 . A network node adapted to perform the method of any of embodiments 1 to 20.

Abbreviations

At least some of the following abbreviations may be used in this disclosure.

3GPP Third Generation Partnership Project

5G Fifth Generation

5GC Fifth Generation Core

5GS Fifth Generation System

AF Application Function

AMF Access and Mobility Management Function

AN Access Network

DN Data Network eNB Enhanced or Evolved Node B

EPC Evolved Packet Core

E-UTRA Evolved Universal Terrestrial Radio Access gNB New Radio Base Station

HSS Home Subscriber Server

LTE Long Term Evolution

MME Mobility Management Entity

MTC Machine Type Communication

NEF Network Exposure Function

NF Network Function

NR New Radio

NRF Network Function Repository Function

NSSF Network Slice Selection Function

OTT Over-the-Top

PCF Policy Control Function

P-GW Packet Data Network Gateway

RAN Radio Access Network

SCEF Service Capability Exposure Function

SMF Session Management Function

UDM Unified Data Management

UE User Equipment

UPF User Plane Function