SMF node and method thereof

Abstract

In the present invention, a session management function (SMF) (32) detects an event relating to an application context relocation (ACR) procedure after receiving, from an access and mobility management function (AMF) (31), a first event notification indicating that a piece of user equipment (UE) is outside the service area of an edge data network (EDN) or a local area data network (LADN). In response to the detection of the event relating to an ACR procedure, the SMF (32) starts a procedure to release a PDU session for the EDN or LADN, or starts a procedure to inactivate an UP connection for the PDU session. This can contribute to, for example, prevention of an ACR procedure failure when a UE moves between EDNs or LADNs.

Description

SMF node, AF node, UE, and methods thereof

[0001] The present disclosure relates to wireless communication networks, and more particularly to PDU session management.

[0002] The 5G system (5GS) connects a wireless terminal (user equipment (UE)) to a data network (DN). In the 5G architecture, connectivity services between a UE and a DN are supported by one or more Protocol Data Unit (PDU) Sessions (see, for example, Non-Patent Documents 1 and 2). A PDU Session is an association, session, or connection between a UE and a DN. A PDU Session is used to provide PDU connectivity services (i.e., exchange of PDUs between a UE and a DN). A PDU Session is established between the UE and a User Plane Function (UPF) (i.e., PDU Session anchor) to which the UE and the DN are connected. From the perspective of data transfer, a PDU Session consists of a tunnel (N9 tunnel) within the 5G core network (5GC), a tunnel (N3 tunnel) between the 5GC and an access network (AN), and one or more radio bearers.

[0003] Non-Patent Document 2 specifies a PDU session establishment procedure and a PDU session release procedure. More specifically, the PDU session establishment procedure is described, for example, in Chapter 4.3.2.2 of Non-Patent Document 2. The PDU session release procedure is described, for example, in Chapter 4.3.4.2 of Non-Patent Document 2. Furthermore, Non-Patent Document 2 specifies a procedure for deactivating a user-plane (UP) connection (or resources) for a PDU session. This procedure is described, for example, in Chapter 4.3.7 of Non-Patent Document 2.

[0004] 5GS supports Local Area Data Networks (LADNs). An overview of LADNs is described, for example, in Chapter 5.6.5 of 3GPP TS 2.0 / 2013. Access to a DN via a PDU session for LADN is only available in a specific LADN service area. An LADN service area is a set of one or more Tracking Areas (TAs) belonging to the UE's current registration area. If the UE moves out of the LADN service area, the Session Management Function (SMF) must release the PDU session for the LADN or deactivate the UP connection for the PDU session. The UP connection (or resources) includes the data radio bar of the Radio Access Network (RAN) and the N3 tunnel between the RAN and the UPF. In other words, deactivating a UP connection means releasing the data radio bar of the (Radio) Access Network ((R)AN) that constitutes the UP connection and the N3 tunnel between the (R)AN and the UPF. Similarly, activating a UP connection means establishing (setting up) the data radio bar of the (R)AN that constitutes the UP connection and the N3 tunnel between the (R)AN and the UPF.

[0005] The Third Generation Partnership Project (3GPP) SA6 working group has begun standardization work on an architecture for enabling edge applications (see, for example, Non-Patent Document 3). This 3GPP architecture is called the EDGEAPP architecture. The EDGEAPP architecture provides specifications for an enabling layer to facilitate communication between application clients (ACs) running on a UE and edge-deployed applications. According to the EDGEAPP architecture, edge applications provided by Edge Application Servers (EASs) are provided to the UE's ACs by an Edge Configuration Server (ECS) and an Edge Enabler Server (EES) via the UE's Edge Enabler Client (EEC).

[0006] As described in Chapter A.2 of Non-Patent Document 3, there are deployment models for various DN implementations. In one example, edge computing services can be provided via Edge-dedicated Data Networks deployed as LADNs (see Chapter A.2.4 of Non-Patent Document 3). With this option, a Public Land Mobile Network (PLMN) supports edge computing services in an Edge Data Network (EDN) service area that is the same as the LADN service area. The LADN service area is the service area in which edge computing is supported. An individual EAS within an LADN can support a service area that is the same as or smaller than the LADN.

[0007] The EDGEAPP architecture supports various Application Context Relocation (ACR) procedures for service continuity. Application context is a set of data related to an AC that exists in an EAS. Application context relocation involves transferring application context from a Source EAS (or old EDN or old LADN) to a Target EAS (or new EDN or new LADN). Application context relocation is triggered by a UE mobility event or a non-UE mobility event. UE mobility events include, for example, intra-EDN mobility, inter-EDN mobility, and Local Area Data Network (LADN)-related mobility. Non-UE mobility events include, for example, an EAS or EDN overload situation and EAS maintenance (e.g., graceful shutdown of the EAS).

[0008] 3GPP TS 23.501 V17.0.0 (2021-03) “3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; System Architecture for the 5G System (5GS); Stage 2 (Release 17)”, March 20213GPP TS 23.502 V17.0.0 (2021-03) “3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Procedures for the 5G System (5GS); Stage 2 (Release 17)”, March 20213GPP TS 23.558 V2.0.0 (2021-03) “3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Architecture for enabling Edge Applications; (Release 17)”, March 20213GPP TS 23.503 V17.0.0 (2021-03) “3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Policy and charging control framework for the 5G System (5GS); Stage 2 (Release 17)”, March 2021

[0009] The inventors have considered a deployment model in which edge computing services are provided via an edge-dedicated data network and have found various challenges, one of which is related to application context relocation (ACR).

[0010] Specifically, when a UE moves from one EDN (or LADN) to another EDN (or LADN), i.e., when a UE switches from a connection to one EDN (LADN) to a connection to another EDN (LADN), it may be desirable to be able to perform application context relocation (ACR) between these two EDNs (LADNs). That is, it may be desirable to transfer or carry over application context from the Source EAS (S-EAS) in the old EDN (LADN) to the Target EAS (T-EAS) in the new EDN (LADN). However, if the UE moves out of the current EDN service area or out of the current LADN service area, the SMF must release the PDU session corresponding to that EDN (LADN) or deactivate the UP connection (or resources) for that PDU session. When the PDU session for the old EDN (LADN) is released or the UP connection is deactivated, the UE (EEC) may no longer be able to communicate with the Source EES (S-EES) in the old LADN. In this case, the ACR procedure involving signaling between the UE (EEC) and the S-EES may not be completed successfully. For example, in the case of ACR initiated by the EEC and ACs (see Non-Patent Document 3, Chapter 8.8.2.2, Figure 8.8.2.3-1), the UE (EEC) may not be able to send the ACR Request message (Step 5) to the S-EES.

[0011] One of the objectives to be achieved by the embodiments disclosed in this specification is to provide an apparatus, a method, and a program that contribute to preventing a failure of the ACR procedure when a UE moves between EDNs (or LADNs). It should be noted that this objective is only one of the objectives to be achieved by the embodiments disclosed in this specification. Other objectives or problems and novel features will become apparent from the description of this specification or the accompanying drawings.

[0012] In a first aspect, an SMF node includes a memory and at least one processor coupled to the memory, wherein the at least one processor is configured to detect an event related to an Application Context Relocation (ACR) procedure after receiving a first event notification from an AMF node indicating that a UE is out of an EDN service area or out of an LAD service area, and wherein the at least one processor is further configured to initiate, in response to detecting the event related to the ACR procedure, a procedure for releasing a PDU session for a LAD associated with the LAD service area, a procedure for releasing a PDU session for an EDN associated with the EDN service area, or a procedure for deactivating a UP connection for the PDU session.

[0013] In a second aspect, a method performed by an SMF node includes: (a) detecting an event related to an ACR procedure after receiving a first event notification from an AMF node indicating that the UE is outside an EDN service area or outside an LADN service area; and (b) in response to detecting the event related to the ACR procedure, initiating a procedure for releasing a PDU session for an LADN associated with the LADN service area, a procedure for releasing a PDU session for an EDN associated with the EDN service area, or a procedure for deactivating a UP connection for the PDU session.

[0014] In a third aspect, an Application Function (AF) node includes a memory and at least one processor coupled to the memory. The at least one processor is configured to receive an event notification from an SMF node directly or via a Network Exposure Function (NEF) node. The at least one processor is further configured to send a response to the event notification to the SMF node directly or via the NEF node after an ACR procedure including a transfer of application context from an S-EAS to a T-EAS is completed. The response is a message that causes the SMF node to initiate a procedure to release a PDU session for an LADn, a procedure to release a PDU session for an EDN, or a procedure to deactivate a UP connection for the PDU session.

[0015] In a fourth aspect, a method performed by an AF node includes (a) receiving an event notification from an SMF node directly or via an NEF node, and (b) after an ACR procedure including a transfer of application context from an S-EAS to a T-EAS is completed, sending a response to the event notification to the SMF node directly or via the NEF node, wherein the response is a message that causes the SMF node to initiate a procedure to release a PDU session for an LADn, a procedure to release a PDU session for an EDN, or a procedure to deactivate a UP connection for the PDU session.

[0016] In a fifth aspect, a UE includes a memory and at least one processor coupled to the memory. The at least one processor is configured to select a mode for continuity of session and service if a first Data Network Name (DNN) corresponds to a predetermined type of Data Network Name (DNN). The at least one processor is further configured to transmit a Non-Access Stratum (NAS) message indicating the selected mode to an AMF node to request establishment of a first PDU session for the first DNN. The mode for continuity of session and service includes establishing a second PDU session for a second DNN to which application context is transferred from the first DNN before releasing the first PDU session when the UE moves out of a Data Network Name (DNN) service area corresponding to the first DNN.

[0017] In a sixth aspect, a method performed by a UE includes: (a) selecting a mode for continuity of session and service if a first DNN corresponds to a predetermined type of LADN; and (b) transmitting a NAS message containing a PDU Session Establishment Request indicating the selected mode to an AMF node to request establishment of a first PDU session for the first DNN. The mode for continuity of session and service includes establishing a second PDU session for a second DNN to which application context is transferred from the first DNN before releasing the first PDU session when the UE moves out of the LADN service area corresponding to the first DNN.

[0018] In a seventh aspect, a UE includes a memory and at least one processor coupled to the memory, the at least one processor configured to provide an EEC function, the EEC function including determining to perform one of a plurality of ACR procedures in consideration of the UE moving out of a LAN service area associated with a first EDN.

[0019] In an eighth aspect, a method performed by a UE includes providing an EEC function, the EEC function including determining to perform one of a plurality of ACR procedures in consideration of the UE moving out of a LAN service area associated with a first EDN.

[0020] In a ninth aspect, the program includes a group of instructions (software code) that, when loaded into a computer, causes the computer to perform the method according to the second, fourth, sixth, or eighth aspect described above.

[0021] According to the above-described aspects, it is possible to provide an apparatus, a method, and a program that contribute to preventing failure of the ACR procedure when a UE moves between EDNs (or LADNs).

[0022] 1 is a diagram illustrating an example of a configuration of a wireless communication network according to an embodiment. FIG. 2 is a diagram illustrating an example of a deployment model of EDNs according to an embodiment. FIG. 3 is a diagram illustrating an example of 3GPP EDGEAPP architecture according to an embodiment. FIG. 4 is a flowchart illustrating an example of an operation of an SMF according to an embodiment. FIG. 5 is a flowchart illustrating an example of an operation of an AF according to an embodiment. FIG. 6 is a sequence diagram illustrating an example of an operation of an AMF, SMF, NEF, and AF according to an embodiment. FIG. 7 is a sequence diagram illustrating an example of an operation of an SMF according to an embodiment. FIG. 8 is a sequence diagram illustrating an example of an operation of an AMF, SMF, NEF, and AF according to an embodiment. FIG. 9 is a flowchart illustrating an example of an operation of an SMF according to an embodiment. FIG. 10 is a sequence diagram illustrating an example of an operation of an AMF and an SM according to an embodiment. FIG. 11 is a flowchart illustrating an example of an operation of a UE according to an embodiment. FIG. 12 is a flowchart illustrating an example of an operation of an EEC of a UE according to an embodiment. FIG. 13 is a block diagram illustrating an example of a configuration of a UE according to an embodiment. FIG. 14 is a block diagram illustrating an example of a configuration of an AMF, SMF, NEF, and AF according to an embodiment.

[0023] Hereinafter, specific embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are designated by the same reference numerals, and for clarity of explanation, duplicate explanations will be omitted as necessary.

[0024] The multiple embodiments described below can be implemented independently or in appropriate combination. These multiple embodiments have different novel features. Therefore, these multiple embodiments contribute to solving different purposes or problems and to achieving different effects.

[0025] Although the following embodiments are primarily described for a 3GPP system (e.g., a 5G system (5GS)), these embodiments may also be applied to other wireless communication systems.

[0026] <First Embodiment> Fig. 1 shows an example of the configuration of a wireless communication network (i.e., 5GS) according to this embodiment. Each of the elements shown in Fig. 1 is a network function and provides an interface defined by 3GPP. Each element (network function) shown in Fig. 1 can be implemented, for example, as a network element on dedicated hardware, as a software instance running on dedicated hardware, or as a virtualized function instantiated on an application platform.

[0027] The wireless communication network shown in Fig. 1 may be provided by a Mobile Network Operator (MNO) or may be a Non-Public Network (NPN) provided by a party other than an MNO. If the wireless communication network shown in Fig. 1 is an NPN, it may be an independent network referred to as a Stand-alone Non-Public Network (SNPN), or an NPN linked to an MNO network referred to as a Public network integrated NPN.

[0028] A wireless terminal (i.e., UE) 1 uses a 3GPP (e.g., 5G) connectivity service to communicate with a data network (DN). More specifically, the UE 1 is connected to a (radio) access network (e.g., 5G Access Network (5GAN)) 2 and communicates with the DN via one or more User Plane Functions (UPFs) 33 in a 3GPP core network 3 (e.g., 5G core network (5GC)). While FIG. 1 illustrates an example in which two UPFs 33 are arranged in series, this is merely an example. There may be only one UPF 33, or two or more UPFs 33 may be arranged in parallel. The 3GPP core network 3 may be, for example, but is not limited to, a 5GC. The 3GPP core network 3 may also include a network other than 5G (e.g., a future 6G or non-3GPP) network.

[0029] UE1 can communicate with multiple DNs simultaneously. As an example, FIG. 1 shows three DNs: LADN 41, LADN 42, and DN 43. UE1 may communicate with one or more of LADN 41, LADN 42, and DN 43 simultaneously. However, UE1 is permitted to access LADN 41 via a PDU session for LADN 41 only when UE1 is within the LADN service area of ​​LADN 41. Similarly, UE1 is permitted to access LADN 42 via a PDU session for LADN 42 only when UE1 is within the LADN service area of ​​LADN 42. An LADN service area is a set of one or more Tracking Areas (TAs) that belong to the UE's current registration area.

[0030] In the architecture of 5G and later 3GPP systems, connectivity services between UE1 and a DN are supported by one or more Protocol Data Unit (PDU) Sessions. A PDU Session is an association, session, or connection between UE1 and a DN. A PDU Session is used to provide PDU connectivity services (i.e., exchange of PDUs between UE1 and a DN). UE1 establishes one or more PDU Sessions between UE1 and a UPF 33 (i.e., PDU Session Anchor (PSA)) to which the DN is connected. From the perspective of data transfer, one PDU Session consists of a tunnel within the 3GPP core network 3 (i.e., N9 tunnel), a tunnel between the 3GPP core network 3 and AN2 (i.e., N3 tunnel), and one or more radio bearers between UE1 and AN2. Although not shown in FIG. 1, UE 1 may establish multiple PDU Sessions with each of multiple (PSA) UPFs 33 to concurrently access (sub)networks (or entities) represented by multiple DNs or multiple Data Network Access Identifiers (DNAIs) (e.g., DN 41 and DN 43).

[0031] The Access and Mobility management Function (AMF) 31 is one of the network function nodes in the control plane of the 3GPP core network 3. The AMF 31 provides the termination of the RAN Control Plane (CP) interface (i.e., N2 interface). The AMF 31 terminates a single signaling connection (i.e., N1 NAS signaling connection) with the UE 1 and provides registration management, connection management, and mobility management. The AMF 31 provides NF services to NF consumers (e.g., other AMFs and the SMF 32) over a service-based interface (i.e., Namf interface). The NF services provided by the AMF 31 include a communication service (Namf_Communication). This communication service enables the NF consumer (e.g., the SMF 32) to communicate with the UE 1 or the AN 2 via the AMF 31.

[0032] The Session Management Function (SMF) 32 is one of the network function nodes in the control plane of the 3GPP core network 3. The SMF 32 manages PDU Sessions. The SMF 32 transmits and receives SM signaling messages (NAS-SM messages, N1 SM messages) to and from the Non-Access-Stratum (NAS) Session Management (SM) layer of the UE 1 via the communication service provided by the AMF 31. The SMF 32 provides Network Function (NF) services to NF consumers (e.g., the AMF 31, other SMFs, and the NEF 36) over a service-based interface (i.e., the Nsmf interface). NF services provided by the SMF 32 include a PDU Session management service (Nsmf_PDUSession), which enables NF consumers (e.g., the AMF 31) to handle PDU Sessions. The NF services provided by the SMF 32 further include an event notification service (Nsmf_EventExposure), whose service operations are exposed to enable NF consumers (e.g., NEF 36, AF 5) to get notified of events occurring in PDU Sessions.

[0033] The User Plane Function (UPF) 33 is one of the network function nodes in the user plane of the 3GPP core network 3. The UPF 33 processes and forwards user data. The functionality of the UPF 33 is controlled by the SMF 32. The UPF 33 may include multiple UPFs (e.g., two UPFs 33 shown in FIG. 1) interconnected via an N9 interface. The UP path for one PDU Session of the UE 1 may include one or more PDU Session Anchor (PSA) UPFs, one or more Intermediate UPFs (I-UPFs), and one or more Uplink Classifier (UL CL) UPFs (or Branching Point (BP) UPFs). The UP path for a PDU Session is a path established within the 3GPP core network 3 to route user plane data (e.g., Internet Protocol (IP) packets) of the PDU Session from the UE 1 to the DN (e.g., the LADN 41, the LADN 42, or the DN 43) and vice versa. The UP path includes at least one UPF 33 and includes an N6 interface with the DN. The UP path may include one or more N9 tunnels. An N9 tunnel is a tunnel between two UPFs 33.

[0034] The Policy Control Function (PCF) 34 is one of the network function nodes in the control plane of the 3GPP core network 3. The PCF 34 supports interactions with access and mobility policy enforcement in the AMF 31 via a service-based interface (i.e., Npcf interface). The PCF 34 provides access and mobility management-related policies to the AMF 31. Furthermore, the PCF 34 provides session-related policies to the SMF 32. The session-related policies include PDU session-related policy information and Policy and Charging Control (PCC) rule information. The PCC rule information includes control information related to AF influence on traffic routing (i.e., AF-influenced Traffic Steering Enforcement Control information).

[0035] The Unified Data Management (UDM) 35 is one of the network function nodes in the control plane of the 3GPP core network 3. The UDM 35 provides access to a database (i.e., User Data Repository (UDR)) in which subscriber data (subscription information) is stored. The UDM 35 provides NF services to NF consumers (e.g., AMF 31, SMF 32) over a service-based interface (i.e., Nudm interface). The NF services provided by the UDM 35 include a subscriber data management service. The NF service enables NF consumers (e.g., AMF 31, PCF 34) to retrieve subscriber data and provides updated subscriber data to the NF consumers. The UDM 35 may also be referred to as a UDR from the perspective of subscriber data management. Similarly, a UDR may also be referred to as a UDM 35.

[0036] The Network Exposure Function (NEF) 36 is one of the network function nodes in the control plane of the 3GPP core network 3. The NEF 36 has a role similar to the Service Capability Exposure Function (SCEF) of the Evolved Packet System (EPS). Specifically, the NEF 36 supports the exposure of services and capabilities from the 3GPP system to applications and network functions inside and outside the operator network. The NEF 36 provides NF services to NF consumers (e.g., AF5) over a service-based interface (i.e., Nnef interface). NF services provided by the NEF 36 include an event notification service (Nnef_EventExposure). Service operations exposed by this NF service enable NF consumers (e.g., AF5) to get notified of events occurring within the 3GPP system. Furthermore, the NF services provided by the NEF 36 include a service (Nnef_TrafficInfluence) for Application Function influence on traffic routing. The service operations exposed by this NF service enable NF consumers (e.g., AF 5) to make requests to influence traffic routing of PDU Session(s) of a specific UE.

[0037] The Application Function (AF) 5 interacts with the 3GPP core network 3. For example, the AF 5 interacts with the 3GPP core network 3 to support application function influence on traffic routing. Depending on the deployment of the AF 5 and the MNO's policies, the AF 5 may interact directly with network functions within the 3GPP core network 3. Otherwise, the AF 5 interacts with network functions within the 3GPP core network 3 via the NEF 36. The AF 5 may include one or more computers. For example, the AF 5 may include one or more servers (e.g., content distribution server, online game server) that communicate with the UE 1 at the application layer, and a controller (i.e., an AF in the 3GPP definition) that cooperates with these one or more servers and interacts with the 3GPP core network 3 (e.g., the NEF 36 and the SMF 32). The AF 5 may include multiple distributed servers. For example, the AF 5 may include a central server located in (or connected to) the DN 43, as well as multiple edge computing servers located in (or connected to) the LADN 41 and the LADN 42. In the example of Figure 1, the AF 5 may communicate with an application running on a processor of the UE 1 via at least one of the LADN 41, the LADN 42, and the DN 43.

[0038] For convenience of explanation, the configuration example in Fig. 1 shows only representative NFs. The wireless communication network according to this embodiment may include other NFs not shown in Fig. 1, such as a Network Slice Selection Function (NSSF) and a Network Data Analytics Function (NWDAF).

[0039] FIG. 2 shows an example of a deployment model for Edge Data Networks (EDNs). A Public Land Mobile Network (PLMN) 8 includes an AN 2 and a 3GPP core network 3. In the example of FIG. 2, EDN A (201) and EDN B (202) are edge-dedicated data networks deployed as LADNs. Specifically, LADN 41 includes EDN A (201), and LADN 42 includes EDN B (202). The service area of ​​EDN A (201) is the same as the LADN service area of ​​LADN 41. The service area of ​​EDN B (202) is the same as the LADN service area of ​​LADN 42. The service area of ​​the EES in EDN A (201) is equal to or a subset of the EDN service area (i.e., the LADN service area of ​​LADN 41). The service area of ​​each EAS in EDN A (201) is equal to or a subset of the service area of ​​the corresponding EES. Similarly, the service area of ​​the EES in EDN B (202) is equal to or a subset of the EDN service area (i.e., the LADN service area of ​​LADN 42). The service area of ​​each EAS in EDN B (202) is equal to or a subset of the service area of ​​the corresponding EES.

[0040] 2, user plane access to LADN 41, LADN 42, and DN 43 may be distinguished by DN Access Identifiers (DNAIs), which are identifiers of user plane access to one or more DNs where an application is deployed.

[0041] Figure 3 shows an example of a 3GPP EDGEAPP architecture according to this embodiment. Each of the elements shown in Figure 3 is a functional entity that provides functions and interfaces defined by 3GPP. Each element (functional entity) shown in Figure 3 can be implemented, for example, as a network element on dedicated hardware, as a software instance running on dedicated hardware, or as a virtualized function instantiated on an application platform.

[0042] In the example of Fig. 3, UE 1 includes an Edge Enabler Client (EEC) 11 and one or more Application Clients (ACs) 12. In other words, the EEC 11 and one or more ACs 12 are located in and operate on UE 1. Although not explicitly shown in Fig. 3, UE 1 communicates with a 3GPP core network 3 (e.g., (5GC)) via AN 2. In this way, UE 1 provides connectivity to a data network via AN 2 and 3GPP core network 3 to EEC 11 and AC(s) 12.

[0043] The EEC 11 provides supporting functions required by the AC(s) 12. Specifically, the EEC 11 provides provisioning of configuration information to enable the exchange of application data traffic with an Edge Application Server (EAS). Furthermore, the EEC 11 provides functionality for discovery of one or more EASs available within the EDN 7. The EEC 11 uses the EAS endpoint information obtained through EAS discovery for routing outgoing application data traffic to the EAS. Furthermore, the EEC 11 provides functionality for registration (i.e., registration, update, and de-registration) of the EES 71 and EAS(s) 72.

[0044] Each AC 12 is an application running on the UE 1. To utilize edge computing services, each AC 12 connects to one or more EASs and exchanges application data traffic with these EASs.

[0045] An EDN 7 includes one or more EESs 71 and one or more EASs 72. As previously described, the EDN 7 may be an edge-only data network (LADN). For example, the EDN 7 of FIG. 3 may be an edge-only data network deployed as the LADN 41 or 42 shown in FIGS. 1 and 2. The EESs 71 and EASs 72 may be included in the AF 5 shown in FIG. 1.

[0046] Each EES 71 provides supporting functions required by the EAS(s) 72 and the EEC 11. Specifically, each EES 71 provides configuration information provisioning to the EEC 11, thereby enabling the exchange of application data traffic with the EAS(s) 72. Each EES 71 provides functions for registration, update, and deregistration of the EEC 11 and the EAS(s) 72. Each EES 71 also provides functions for application context transfer between EASs. This function is required for application context relocation (or edge application mobility) for service continuity. Application context is a set of data related to an AC that resides in an EAS. Application context relocation involves transferring application context related to a user (i.e., an AC) from a Source EAS (or old EDN or old LADN) to a Target EAS (or new EDN or new LADN). The application context relocation is triggered by a UE mobility event or a non-UE mobility event. UE mobility events include, for example, intra-EDN mobility, inter-EDN mobility, and Local Area Data Network (LADN)-related mobility. Non-UE mobility events include, for example, an EAS or EDN overload situation and EAS maintenance (e.g., graceful shutdown of the EAS).

[0047] Furthermore, each EES 71 supports an Application Programming Interface (API) invoker and an API exposing function. Each EES 71 provides an ACR management event notification function to the EAS(s) 72. The ACR management event notification function notifies the EAS(s) of UE mobility events or non-UE mobility events that trigger an Application Context Relocation (ACR) procedure for one or more UEs. Event types (event IDs) include user plane path change detection (i.e., "User plane path change"), user plane path change detection and T-EAS identification (i.e., "ACR monitoring"), user plane path change and T-EAS identification and traffic change appropriate for the T-EAS (i.e., "ACR facilitation"), and whether the UE has moved into or out of a specific location or area (i.e., "Presence-In-Area of ​​Interest (AOI)-Report"). The EAS(s) 72 subscribe to these events provided by the EES 71 in advance to receive the desired notifications. Here, the "specific location or area" may be a Tracking Area Identity (TAI) list or Cell IDs, or a TAI list associated with a specific LADN. Each EES 71 may interact with the 3GPP core network 3 directly (e.g., via the PCF 34) or indirectly (e.g., via the NEF 36 or the Service Capability Exposure Function (SCEF)) to access the services and capabilities of network functions within the 3GPP core network 3.Each EES 71 may support external exposure of 3GPP network function services and capabilities to EAS(s) 72. Each EES 71 may support application function influence on traffic routing and interact with the 3GPP core network 3.

[0048] Each EAS 72 is located in the EDN 7 and executes application server functions. The application server functions may be available only at the edge. In other words, the application server functions may be available only as an EAS. However, the application server functions may be available both at the edge and in the cloud. In other words, the application server functions may be available as an EAS and also as an application server in the cloud. The cloud here refers to a central cloud (e.g., the DN 43 in FIGS. 1 and 2) located farther from the UE 1 than the EDN 7 (e.g., the LADNS 41 or 42 in FIGS. 1 and 2). Therefore, an application server in the cloud refers to a server located in a centralized location (e.g., a centralized data center). Each EAS 72 may consume or utilize 3GPP core network capabilities. Each EAS 72 may directly invoke 3GPP core network function APIs. Alternatively, each EAS 72 may consume or utilize 3GPP core network capabilities via the EES 71, or via the NEF 36 or SCEF. Each EAS 72 may support Application Function influence on traffic routing and interact with the 3GPP core network 3.

[0049] The Edge Configuration Server (ECS) 6 provides supporting functions required by the EEC 11 to connect to the EES(s) 71. Specifically, the ECS 6 provides provisioning of edge configuration information to the EEC 11. The edge configuration information includes information for the EEC 11 to connect to the EES(s) 71 (e.g., service area information applicable to the LADN) and information for establishing a connection with the EES(s) 71 (e.g., Uniform Resource Identifier (URI)). The ECS 6 provides functions for registration, update, and deregistration of the EES(s) 71. Furthermore, the ECS 6 supports API invoker and API exposing function functions. The ECS 6 may interact directly (e.g., via the PCF 34) or indirectly (e.g., via the NEF 36 or SCEF) with the 3GPP core network 3 to access the services and capabilities of network functions within the 3GPP core network 3. The ECS 6 may be located within the domain of the MNO providing the 3GPP core network 3, or may be located in a third-party domain of a service provider (e.g., an Edge Computing Service Provider (ECSP)). The ECS 6 may be located in a central cloud (e.g., the DN 43 in FIGS. 1 and 2). The ECS 6 may be included in the AF 5 shown in FIG. 1.

[0050] For convenience of explanation, only representative elements are shown in the configuration example of Fig. 3. For example, the ECS 6 may be connected to multiple EDNs.

[0051] The operation of the SMF 32 according to this embodiment will be described below. If the UE 1 moves outside the EDN service area or the LADN service area, the SMF 32 does not immediately release the PDU session for the EDN or the LADN, or deactivate the UP connection for the PDU session, but rather waits a while. Specifically, the SMF 32 releases the PDU session for the EDN or the LADN, or deactivates the UP connection for the PDU session, in response to detecting an event related to the ACR procedure. The SMF 32 may detect the event related to the ACR procedure after receiving a first event notification from the AMF 31, indicating that the UE 1 is outside the EDN service area or the LADN service area.

[0052] The event related to the ACR procedure may be an event indicating that the AF 5 has successfully completed the ACR procedure. The event related to the ACR procedure may be an event that enables the AF 5 to successfully complete the ACR procedure. The event related to the ACR procedure may be reception or detection of reception of a response indicating successful completion of the ACR procedure from the AF 5. In this case, the SMF 32 may send an event notification (also referred to as a second event notification) to the AF 5 and wait for a response from the AF 5. Here, the second event notification may be a notification indicating that the UE 1 is out of the EDN service area or out of the LADN service area, or a pre-notification of release of a PDU session for the EDN, a pre-notification of release of a PDU session for the LADN, or a pre-notification of deactivation of a UP connection. Furthermore, the response from the AF 5 indicating successful completion of the ACR procedure may be a response to the second event notification. The successful completion of the ACR procedure may include transfer of application context from the Source Edge Application Server (S-EAS) to the Target EAS (T-EAS).

[0053] Alternatively, the event related to the ACR procedure may be the SMF 32 receiving a message from the PCF 34 to instruct the SMF 32 to start a procedure to release the PDU session for the EDN or the LADN or a procedure to deactivate the UP connection for the PDU session. In this case, the PCF 34 may determine to send the message based on information provided to the PCF 34 from the AF 5 (e.g., S-EES) via the NEF 36 and the UDM 35.

[0054] Alternatively, the event related to the ACR procedure may be the passage (or expiration) of a predetermined grace period for waiting for the completion of the ACR procedure by the AF 5. In this case, if the UE 1 moves out of the EDN service area or out of the LADN service area, the SMF 32 waits for the grace period to elapse before initiating the release of the PDU session for that EDN or LADN or the deactivation of the UP connection. Deactivating the UP connection means releasing the data radio barr of the (Radio) Access Network ((R)AN) 2 that constitutes the UP connection and the N3 tunnel between the (R)AN 2 and the UPF 33. Similarly, activating the UP connection means establishing (setting up) the data radio barr of the (Radio) Access Network ((R)AN) 2 that constitutes the UP connection and the N3 tunnel between the (R)AN 2 and the UPF 33.

[0055] The SMF 32 may perform this operation only for a specific EDN, a specific LADN (LADN DNN), a specific PDU Session, or specific UEs. If UE1 moves out of the LADN service area and the LADN belongs to a specific LADN, the SMF 32 may wait for a grace period to elapse before initiating the release of the PDU Session or the deactivation of the UP connection for the LADN. Similarly, if UE1 moves out of the EDN service area and the EDN belongs to a specific EDN, the SMF 32 may wait for a grace period to elapse before initiating the release of the PDU Session or the deactivation of the UP connection for the EDN.

[0056] Specific LADNs may be defined by the type of LADN. Specific LADNs may be distinguished from other LADNs by their LADN DNN. Specific EDNs may be defined by the type of EDN. Specific EDNs may be distinguished from other EDNs by their (EDN) DNN, or by their (EDN) DNN and DNAI, or by their network slice information, or by their (EDN) DNN and network slice information. The network slice information may be Single Network Slice Selection Assistance Information (S-NSSAI). Specifically, a PDU session for a specific EDN may be associated with a specific network slice (or a specific S-NSSAI). In this case, a specific EDN can be identified by its DNN and network slice information (e.g., S-NSSAI).

[0057] UE1 being outside the EDN service area may mean that UE1 is outside the EES service area or outside the EAS service area. In other words, in the terminology used herein, an EDN service area may be the same as an EES service area or an EAS service area. An EES service area is a service area provided by an EES in an EDN. An EAS service area is a service area provided by an EAS in an EDN. An EES service area may be a topological service area or a geographical service area. Similarly, an EAS service area may be a topological service area or a geographical service area. A topological service area is defined relative to the UE's point of attachment to the network. A topological service area may be defined by a set of Cell IDs, a set of TAIs, or a PLMN ID. A geographical service area may be an area defined by geographical coordinates, a circle whose center is denoted by geographical coordinates, or a polygon whose corners are denoted by geographical coordinates. Geographical service areas may also be represented in other ways, such as by well-known buildings, parks, arenas, civic addresses, ZIP codes, etc.

[0058] The SMF 32 may be configured with specific LADNS or specific EDNs in advance by the MNO. The SMF 32 may acquire configuration indicating the specific LADNS or specific EDNs from the AMF 31 or the UDM 35. For example, the specific LADNS may be LADNS for EDNs. The specific LADNS or specific EDNs may be managed by the UDM 35 as subscriber information for the UE 1. In this case, information regarding the specific LADNS or specific EDNs may be transferred from the UDM 35 to the AMF 31 using the Nudm_SDM_Get service when the UE 1 performs a location registration procedure. Then, when the UE 1 establishes a PDU session for the LADNS (PDU Session Establishment procedure), the SMF 32 may be notified of information regarding the specific LADNS or specific EDNs from the AMF 31 via an Nsmf_PDUSession_CreateSMContext Request message or an Nsmf_PDUSession_UpdateSMContext Request message. Alternatively, for example, when the UE 1 establishes a PDU session related to the LADNS or the EDN, the SMF 32 may receive information related to specific LADNS or specific EDNs from the UDM 35 by using the Nudm_SDM_Get service. The information related to the specific LADNS or specific EDNs may be UE local configuration information specified in Non-Patent Document 4. In this case, the information related to the specific LADNS or specific EDNs may be transmitted from the UE 1 to the SMF 32 via the AMF 31 by using a NAS message (or a NAS SM message).

[0059] The SMF 32 may distinguish a specific PDU Session based on a request from the AF 5 via the NEF 36. Specifically, if the SMF 32 has previously received information from the AF 5 indicating that it will wait for a response from the AF 5 before initiating the release of the PDU Session or the deactivation of the UP connection, the SMF 32 may send an event notification to the AF 5 and wait for a response from the AF 5 before releasing the PDU Session or deactivating the UP connection.

[0060] 4 is a flowchart showing an example of the operation of the SMF 32 according to this embodiment. In step 401, the SMF 32 receives a first event notification from the AMF 31, indicating that the UE 1 is outside the EDN service area or the LADN service area. In step 402, after receiving the first event notification, the SMF 32 detects an event related to an Application Context Relocation (ACR) procedure. In step 403, in response to detecting the event related to the ACR procedure, the SMF 32 initiates a procedure to release a PDU session for the LADN associated with the LADN service area associated with the EDN service area, a procedure to release a PDU session for (or associated with) the EDN, or a procedure to deactivate a UP connection for the PDU session. In other words, after receiving the first event notification indicating that the UE 1 is outside the EDN service area or the LADN service area, the SMF 32 waits for the occurrence of an event related to the ACR procedure before releasing the PDU session for the EDN or the LADN or deactivating the UP connection. As already explained, the SMF 32 may perform the operations of FIG. 4 only for specific EDNs, specific LADNs, specific PDU Sessions, or specific UEs.

[0061] An event related to the ACR procedure may include sending a second event notification from the SMF 32 to the AF 5 directly or via the NEF 36, and then receiving a response from the AF 5 directly or via the NEF 36. If the SMF 32 has previously received information from the AF 5 indicating that the SMF 32 will wait for a response from the AF 5 before initiating the release of the PDU session or the deactivation of the UP connection, the SMF 32 may send a second event notification to the AF 5 and wait for a response from the AF 5 before releasing the PDU session or deactivating the UP connection. For example, the information indicating that a response from the AF 5 will be waited for before initiating the release of the PDU session or the deactivation of the UP connection may be an indication that "AF acknowledgement is expected."

[0062] In one example, if the SMF 32 has previously received an AF request from the AF 5 directly or via the NEF 36, which is a request to subscribe to a second event notification provision service for a PDU session, and the request includes an indication that an "AF acknowledgment is expected," the SMF 32 may send a second event notification to the AF 5 and wait for a response from the AF 5 before releasing the PDU session or deactivating the UP connection. That is, the SMF 32 manages the timing of the PDU session release based on runtime coordination between the 5GC and the EDGEAPP using the "AF acknowledgment to be expected." The second event notification may indicate that the UE 1 is out of the EDN service area or out of the LADN service area. The second event notification may indicate an advance notification of the release of the PDU session for the EDN or LADN, or an advance notification of the deactivation of the UP connection. The response from the AF5 may indicate the completion of the ACR procedure, including the transfer of the application context from the S-EAS to the T-EAS.

[0063] Alternatively, the event related to the ACR procedure may include the expiration (or passage) of a predetermined amount of time for waiting for completion of the ACR procedure. After receiving a first event notification from the AMF 31 indicating that the UE 1 is outside the EDN service area or the LADN service area, the SMF 32 may start a timer to count the predetermined amount of time. The SMF 32 may determine whether starting the timer is required based on the DNN, LADN, or EDN. The SMF 32 may determine whether starting the timer is required based on the type of the DNN, LADN, or EDN. The SMF 32 may determine whether starting the timer is required based on whether the DNN, LADN, or EDN is associated with the timer. The SMF 32 may determine to perform a PDU session release procedure or a UP connection deactivation procedure based on the detection of an event related to the ACR procedure.

[0064] Alternatively, the event related to the ACR procedure may include the SMF 32 receiving a notification or a message related to the procedure specified in Chapter 4.3.6.2 of 3GPP TS 33-34094-1. Specifically, the SMF 32 may initiate a procedure to release the PDU session for the EDN or the LADN or a procedure to deactivate the UP connection for the PDU session, by using the Npcf_SMPolicyControl_UpdateNotify service received from the PCF 34. In other words, the Npcf_SMPolicyControl_UpdateNotify service invoked by the PCF 34 instructs the SMF 32 to release the PDU session for the EDN or the LADN or to deactivate the UP connection for the PDU session. The PCF 34 may determine to send the instruction based on information provided to the PCF 34 from the AF 5 (e.g., S-EES) via the NEF 36 and the UDM 35. The AF 5 (e.g., S-EES) may detect that the UE 1 is outside the EDN service area or the LADN service area by using the Location Reporting function defined in Chapter 4.15.3.1 of Non-Patent Document 4. Then, in response to this detection, the AF 5 (e.g., S-EES) may instruct the 3GPP core network 3 to perform a procedure for releasing the PDU session of the EDN or the LADN, or to deactivate the UP connection for the PDU session.

[0065] According to the above-described operation, if UE1 moves outside the EDN service area or the LAD service area, SMF 32 can wait for a grace period to elapse before initiating the release of the PDU session for that EDN or LAD or the deactivation of the UP connection. This can help prevent the ACR procedure from failing when UE1 moves between different LADs or EDNs. Specifically, after UE1 moves outside the EDN service area or the LAD, the PDU session for the old EDN or LAD is maintained for a while (e.g., until an event related to the ACR procedure is detected). For example, SMF 32 maintains the PDU session for the old EDN or LAD until it can guarantee that the ACR procedure will be completed successfully, until it is estimated that the ACR procedure will be completed successfully, or until it is confirmed that the ACR procedure has been completed successfully. Therefore, UE1 can communicate with the EES (i.e., S-EES) of the old EDN or LAD via the PDU session. This can therefore increase the likelihood of successfully completing the ACR procedure involving signaling between the S-EES and the EEC 11 of UE 1.

[0066] In this embodiment, EDN service area management may be performed using a network slice. Specifically, an EDN or an EES or EAS within the EDN may be associated with a specific network slice. In other words, UE1 may be able to access the EDN (or EES or EAS) associated with the network slice only when UE1 is authorized to use the specific network slice. A specific network slice may be available throughout the PLMN or only in a certain topological area within the PLMN. The topological area may be one or more TAs (or TAIs). If a specific network slice is only available in one or more TAs, the registration area of ​​UE1 establishing a PDU session to access an EAS in the EDN is the same as or a subset of one or more TAs (or TAIs) assigned to the specific network slice. In this case, the EDN service area is the same as or a subset of one or more TAs (or TAIs) assigned to the specific network slice. Also, step 401 in Figure 4 is an instruction to release a PDU session or deactivate an UP connection due to UE1 moving out of the topological area (e.g., one or more TAs) assigned to the specific network slice (or a specific S-NSSAI). Specifically, consider a case where UE1 has been notified of an Allowed NSSAI including a certain S-NSSAI from the 3GPP core network 3 (i.e., AMF 31), and there are one or more PDU sessions of UE1 related to that S-NSSAI. In this case, if UE1 moves out of the topological area assigned to the S-NSSAI (or UE1's current registration area), in step 401 in Figure 4, AMF 31 notifies UE1 of the S-NSSAI as a Rejected S-NSSAI and instructs SMF 32 to release the PDU session(s) related to the S-NSSAI.

[0067] In the case where EDN service area management using network slicing is performed, the operation of SMF 32 in step 402 of Figure 4 is similar to that described above. In step 403 of Figure 4, in response to detecting an event related to the ACR procedure in step 402, SMF 32 releases UE1's PDU Session(s) associated with the S-NSSAI that has become the Rejected S-NSSAI.

[0068] According to these operations, if UE1 moves out of the EDN service area, SMF 32 can wait for a grace period to elapse before initiating the release of the PDU session or deactivation of the UP connection for the EDN associated with that EDN service area. This can help prevent the ACR procedure from failing when UE1 moves between different EDNs. Specifically, after UE1 moves out of the EDN service area, the PDU session for the old EDN is maintained for a while (e.g., until an event related to the ACR procedure is detected). For example, SMF 32 maintains the PDU session for the old EDN until it can guarantee that the ACR procedure will be completed successfully, until it is estimated that the ACR procedure will be completed successfully, or until it is confirmed that the ACR procedure has been completed successfully. This allows UE1 to communicate with the EES (i.e., S-EES) of the old EDN via the PDU session. This can therefore increase the likelihood of successfully completing the ACR procedure, which involves signaling between the S-EES and UE1's EEC 11.

[0069] Second Embodiment This embodiment provides a detailed example of the operation of the SMF 32 described in the first embodiment, and detailed examples of the operations of the AMF 31, the NEF 36, and the AF 5 that are effective therefor. An example of a network architecture according to this embodiment is similar to the example described with reference to FIGS. 1 to 3.

[0070] FIG. 5 is a flowchart showing an example of the operation of the SMF 32. Step 501 is similar to step 401 in FIG. 4. Specifically, in step 501, the SMF 32 receives a first event notification from the AMF 31, indicating that the UE 1 is outside the EDN service area or the LADN service area. Steps 502 and 503 provide an example of step 402 in FIG. 4. In step 502, the SMF 32 sends a second event notification to the AF 5 (e.g., S-EES) directly or via the NEF 36. In step 503, the SMF 32 detects that a response to the second event notification has been received from the AF 5 directly or via the NEF 36. In step 504, after detecting that a response to the second event notification has been received, the SMF 32 initiates a procedure to release a PDU session for the LADN associated with the LADN service area, a procedure to release a PDU session for the EDN associated with the EDN service area, or a procedure to deactivate the UP connection for the PDU session.

[0071] 6 is a flowchart showing an example of the operation of the AF 5 (e.g., S-EES). In step 601, the AF 5 receives a second event notification from the SMF 32 directly or via the NEF 36. In step 602, the AF 5 sends a response to the second event notification to the SMF 32 directly or via the NEF 36 after the ACR procedure from the S-EAS to the T-EAS is completed. The response may trigger the SMF 32 to release the PDU Session for the EDN or LADN or to deactivate the UP connection.

[0072] 7 is a sequence diagram showing an example of the operations of the AMF 31, the SMF 32, the NEF 36, and the AF 5. The AF 5 may include an S-EES. In step 701, the AMF 31 sends an event notification to the SMF 32 indicating that the UE 1 is outside the EDN service area or the LADN service area. To receive this event notification, the SMF 32 may subscribe in advance to the UE mobility event notifications of the AMF 31 using the event ID "UE moving in or out of Area of ​​Interest." This allows the SMF 32 to receive notifications about the event ID.

[0073] In steps 702 and 703, the SMF 32 sends an event notification to the AF 5 via the NEF 36, which explicitly or implicitly indicates that the UE 1 is outside the EDN service area or the LADN service area. Specifically, in step 702, in response to detecting an event (e.g., "Presence-In-AOI-Report") subscribed to by the NF consumer (i.e., the AF 5 or the NEF 36), the SMF 32 invokes the Nsmf_EventExposure_Notify service operation to report the event to the NEF 36 or the AF 5. In step 703, the NEF 36 invokes a service operation to report the event to the AF 5. The service operation invoked by the NEF 36 may be an improvement of an existing service operation (e.g., Nnef_EventExposure) or a newly defined service operation (e.g., Nnef_AOIEventNotification).

[0074] In steps 704 and 705, the AF 5 sends a response to the SMF 32 via the NEF 36. Specifically, in step 704, the AF 5 sends a response to the event notification of step 703 (Acknowledgement of AOIEventNotification or Acknowledgement of EventExposure) to the NEF 36. The response may indicate the completion of the ACR procedure, including the transfer of application context from the S-EAS to the T-EAS (e.g., "ACR complete"). In step 705, the NEF 36 sends a response to the event notification of step 702 (Acknowledgement of Event Notification) to the SMF 32.

[0075] In step 706, after receiving the response in step 705, the SMF 32 releases the PDU session or deactivates the UP connection for the EDN or the LADN. Although not shown, the procedure for releasing the PDU session or deactivating the UP connection includes signaling between the SMF 32 and the UPF 33, and signaling between the SMF 32 and the UE 1 via the AMF 31. The procedure for releasing the PDU session or deactivating the UP connection may be similar to the procedure specified in Chapter 4.3.4.2 or Chapter 4.3.7 of Non-Patent Document 2.

[0076] To receive the event notification in step 705, the AF 5 may subscribe to the notification service of the event in advance. FIG. 8 shows an example of a procedure for subscribing to an event notification service by the SMF 32. In step 801, the AF 5 sends an AF request to the NEF 36 to subscribe to the event notification service for a specific PDU Session. The AF request includes an indication that "AF acknowledgement to be expected." The AF 5 may invoke the Nnef_EventExposure_Subscribe operation using the event ID "Presence In AOI Report." The NEF 36 provides a UE mobility out of an Area of ​​Interest function as a Monitoring Event, allowing the AF 5 to detect UE mobility. This allows the AF 5 to detect UE mobility events via the NEF 36 (Nnef_EventExposure_Subscribe).

[0077] In step 802, the NEF 36 requests subscription to the event notification service of the SMF 32 based on the AF request of step 801. The request includes an indication that "AF acknowledgment is expected." In step 802, the NEF 36 may invoke the Nsmf_EventExposure_Subscribe operation using the Event ID "Presence In AOI Report." Based on the fact that the received request includes an indication that "AF acknowledgment is expected," the SMF 32 recognizes that it needs to send an event notification to the AF 5 and wait for a response from the AF 5 before releasing the PDU Session or deactivating the UP connection. In addition, the SMF 32 provides a UE mobility out of an Area of ​​Interest function so that the NEF 36, or the AF 5 via the NEF 36, can detect the movement of UEs. This allows the NEF 36, or the AF 5 via the NEF 36, to receive a notification (Nsmf_EventExposure_Notify) of a movement event of the UE 1 from the SMF 32.

[0078] According to the example described in this embodiment, if UE1 moves out of the EDN service area or out of the LADN service area, SMF 32 sends an event notification to AF 5 and waits for a response from AF 5 before initiating the release of the PDU session for that EDN or that LADN or the deactivation of the UP connection, which can help prevent the ACR procedure from failing when UE1 moves between different EDNs corresponding to different LADNs.

[0079] <Third Embodiment> This embodiment provides a detailed example of the operation of the SMF 32 described in the first embodiment, and detailed examples of the operations of the AMF 31, the NEF 36, and the AF 5 that are effective therefor. An example of a network architecture according to this embodiment is similar to the example described with reference to Figures 1 to 3.

[0080] 9 is a flowchart showing an example of the operation of the SMF 32. Step 901 is similar to step 401 in FIG. 4. Specifically, in step 901, the SMF 32 receives a first event notification from the AMF 31, indicating that the UE 1 is outside the EDN service area or the LADN service area. In step 902, the SMF 32 detects the expiration of a predetermined time for waiting for the completion of the ACR procedure. After receiving the first event notification, the SMF 32 may start a timer to count the predetermined time. In step 903, after the expiration of the predetermined time, the SMF 32 initiates a procedure to release a PDU session for the LADN associated with the LADN service area, a procedure to release a PDU session for the EDN associated with the EDN service area, or a procedure to deactivate the UP connection for the PDU session. As described in the first embodiment, the SMF 32 may determine whether to start the timer based on whether the EDN or LADN related to the first event notification is a specific EDN or LADN.

[0081] As in the first embodiment, in this embodiment, EDN service area management using a network slice may be performed. Specifically, an EDN or an EES or EAS within the EDN may be associated with a specific network slice. In other words, UE1 may be able to access the EDN (or EES or EAS) associated with the network slice only when UE1 is authorized to use the specific network slice. If a specific network slice is available only in one or more TAs, the registration area of ​​UE1 establishing a PDU session to access an EAS in the EDN is the same as or a subset of one or more TAs (or TAIs) assigned to the specific network slice. In this case, the EDN service area is the same as or a subset of one or more TAs (or TAIs) assigned to the specific network slice. Also, step 901 in FIG. 9 is an instruction to release a PDU session or deactivate a UP connection due to UE1 moving out of a topological area (e.g., one or more TAs) assigned to the specific network slice (or a specific S-NSSAI). Specifically, consider a case where UE1 has been notified of an Allowed NSSAI including a certain S-NSSAI from the 3GPP core network 3 (i.e., AMF 31), and there are one or more PDU Sessions of UE1 related to that S-NSSAI. In this case, if UE1 moves out of the topological area assigned to that S-NSSAI (or out of UE1's current registration area), in step 901 of Figure 9, AMF 31 notifies UE1 of the S-NSSAI as a Rejected S-NSSAI and instructs SMF 32 to release the PDU Session(s) related to that S-NSSAI.

[0082] In the case where EDN service area management using network slicing is performed, the operation of SMF 32 in step 902 of Figure 9 is similar to that described above. In step 903 of Figure 9, in response to detecting an event related to the ACR procedure in step 902, SMF 32 releases UE1's PDU Session(s) associated with the S-NSSAI that has become the Rejected S-NSSAI.

[0083] 10 is a sequence diagram showing an example of the operations of the AMF 31, the SMF 32, the NEF 36, and the AF 5. The AF 5 may include an S-EES. In step 1001, the AMF 31 sends an event notification to the SMF 32 indicating that the UE 1 is outside the EDN service area or the LADN service area. To receive this event notification, the SMF 32 may subscribe in advance to the UE mobility event notifications of the AMF 31 using the event ID "UE moving in or out of Area of ​​Interest." This allows the SMF 32 to receive notifications related to the event ID.

[0084] In a case where EDN service area management using network slicing is performed, AMF 31 may send the event notification of step 1001, i.e., an instruction to release the PDU Session(s) related to the S-NSSAI, in response to UE 1 moving out of the topological area (or UE 1's current registration area) assigned to the S-NSSAI associated with the EDN (or EES or EAS). Specifically, AMF 31 may notify SMF 32 of the release of the PDU Session(s) related to the S-NSSAI by calling the Nsmf_PDUSession_ReleaseSMContext service operation.

[0085] In step 1002, the SMF 32 starts a timer. The value set for the timer may be determined based on a local policy. The timer value may also be determined based on the subscription information of the UE 1. The UE 1 may indicate the timer value in the PDU session establishment procedure. Alternatively, the AF 5 may indicate the timer value. The AF 5 may indicate the timer value to the SMF 32 via the NEF 36 in the procedure for subscribing to the event notification service by the SMF 32. This procedure may be similar to that shown in FIG. 8.

[0086] By way of example and not limitation, in steps 1003 and 1004, the SMF 32 may send an event notification to the AF 5 via the NEF 36, explicitly or implicitly indicating that the UE 1 is out of the EDN service area or out of the LADN service area. Steps 1003 and 1004 may be similar to steps 702 and 703 of Figure 7.

[0087] In step 1005, the SMF 32 detects expiration of the timer. In step 1006, after expiration of the timer, the SMF 32 releases the PDU session or deactivates the UP connection for the EDN or the LADN. Although not shown, the procedure for releasing the PDU session or deactivating the UP connection includes signaling between the SMF 32 and the UPF 33, and signaling between the SMF 32 and the UE 1 via the AMF 31. The procedure for releasing the PDU session or deactivating the UP connection may be similar to the procedure specified in Chapter 4.3.4.2 or Chapter 4.3.7 of 3GPP TS 36.210.

[0088] According to the example described in this embodiment, if UE1 moves out of the EDN service area or out of the LADN service area, SMF32 waits for a predetermined time to expire before initiating the release of the PDU session or deactivation of the UP connection for that EDN or that LADN, which can help prevent the ACR procedure from failing when UE1 moves between different EDNs corresponding to different LADNs.

[0089] <Fourth Embodiment> This embodiment provides a detailed example of the operation of the SMF 32 described in the first embodiment, and a detailed example of the operation of the AMF 31 that is effective for that operation. An example of a network architecture according to this embodiment is similar to the example described with reference to Figures 1 to 3.

[0090] FIG. 11 is a flowchart showing an example of the operation of the SMF 32. Step 1101 is similar to step 401 in FIG. 4. Specifically, in step 1101, the SMF 32 receives a first event notification from the AMF 31, indicating that the UE 1 is outside the EDN service area or outside the LADN service area. In step 1102, the SMF 32 determines whether the EDN or the LADN is of a specific type. The specific type of EDN or the LADN may be an EDN or the LADN that is compatible with (or supports) a mode for continuity of session and service. The type of the LADN may be identified based on the LADN DNN. The type of the EDN may be identified based on the (EDN) DNN of the EDN, based on the (EDN) DNN and DNAI, or based on the (EDN) DNN and S-NSSAI. Additionally or alternatively, the SMF 32 determines whether the LADN or the EDN is associated with a timer. These determinations may be made based on the LADN DNN of the LADN. These determinations may be made based on the (EDN) DNN of the EDN, based on the (EDN) DNN and DNAI, or based on the (EDN) DNN and S-NSSAI. If the EDN or the LADN is of a specific type or is associated with a timer, the SMF 32 recognizes that a timer needs to be started before releasing the PDU session for the EDN or the LADN or deactivating the UP connection. The SMF 32 then starts the timer. The value set for the timer may be determined based on local policy. The timer value may also be determined based on UE1's subscriber information. UE1 may indicate the timer value during the PDU session establishment procedure.

[0091] In step 1103, SMF 32 detects expiration of the timer. In step 1104, after expiration of the timer, SMF 32 initiates a procedure to release the PDU session for the LADN associated with the LADN service area, a procedure to release the PDU session for the EDN associated with the EDN service area, or a procedure to deactivate the UP connection for the PDU session.

[0092] To assist the SMF 32 in making the determination in step 1102, a new DNN information element may be defined, called a "continuity of session and service capable LADN DNN" or a "continuity of session and service capable EDN DNN." In step 1102, the SMF 32 may determine whether the EDN or the LADN is associated with this new DNN information element.

[0093] Note that in the embodiments described herein, the definitions of the terms "continuity of session and service" and "mode for continuity of session and service" are different from those of "SSC" and "SSC mode" in the current 3GPP specifications described in Non-Patent Documents 1 and 2, etc. Specifically, in the current 3GPP specifications, "SSC" and "SSC mode" are used to maintain PDU session connectivity to the same DN (or the same DNN). In particular, SSC mode 2 and mode 3 involve the establishment of a new PDU session to the same DN (or DNN) as the old PDU session. In contrast, in the terminology used herein, "continuity of session and service" and "mode for continuity of session and service" refer to the establishment of a new PDU session for a second DNN different from the first DNN before releasing the old PDU session with the first DNN when UE1 moves out of the DN (or DNN) service area corresponding to the first DNN. In one example, the "continuity of session and service" and "mode for continuity of session and service" comprise, when UE1 moves out of a LDPN service area corresponding to the first DNN, establishing a new PDU Session service for the second DNN to which the application context is transferred from the first DNN before releasing the old PDU Session with the first DNN.

[0094] 12 is a sequence diagram showing an example of the operation of the AMF 31 and the SMF 32. In step 1201, the AMF 31 sends an event notification indicating that the UE 1 is outside the EDN service area or the LADN service area to the SMF 32. To receive this event notification, the SMF 32 may subscribe in advance to the UE mobility event notifications of the AMF 31 using the event ID "UE moving in or out of Area of ​​Interest". This allows the SMF 32 to receive notifications related to this event ID.

[0095] In a case where EDN service area management using network slicing is performed, AMF 31 may send the event notification of step 1201, i.e., an instruction to release the PDU Session(s) related to the S-NSSAI, in response to UE 1 moving out of the topological area (or UE 1's current registration area) assigned to the S-NSSAI associated with the EDN (or EES or EAS). Specifically, AMF 31 may notify SMF 32 of the release of the PDU Session(s) related to the S-NSSAI by calling the Nsmf_PDUSession_ReleaseSMContext service operation.

[0096] In step 1202, the SMF 32 determines whether the EDN or the LADN is of a specific type. As described above, an EDN or an LADN of a specific type is, for example, but not limited to, an EDN or an LADN that is capable of (or supports) a mode for continuity of session and service. The SMF 32 may determine whether the LADN is associated with a specific DNN information element, such as a "continuity of session and service capable" information element. Alternatively, the SMF 32 may determine whether the EDN is associated with a specific DNN information element, such as a "continuity of session and service capable EDN DNN" information element. If the EDN or the LADN is of a specific type, the SMF 32 recognizes that a timer needs to be started before releasing the PDU session for the EDN or the LADN or deactivating the UP connection. The SMF 32 then starts the timer.

[0097] In step 1203, the SMF 32 detects expiration of the timer. In step 1204, after expiration of the timer, the SMF 32 releases the PDU session for the EDN or the LADN or deactivates the UP connection. Although not shown, the procedure for releasing the PDU session or deactivating the UP connection includes signaling between the SMF 32 and the UPF 33, and signaling between the SMF 32 and the UE 1 via the AMF 31. The procedure for releasing the PDU session or deactivating the UP connection may be similar to the procedure specified in Chapter 4.3.4.2 or Chapter 4.3.7 of 3GPP TS 36.210.

[0098] According to the example described in this embodiment, if UE1 moves out of the EDN service area or out of the LADN service area, SMF32 waits for a predetermined time for the ACR procedure to complete before initiating the release of the PDU session or deactivation of the UP connection for that EDN or that LADN, which can help prevent the ACR procedure from failing when UE1 moves between different EDNs corresponding to different LADNs.

[0099] In this embodiment, UE1 may perform the operations shown in FIG. 13 when establishing a PDU session. In step 1301, the NAS layer of UE1 selects a mode for continuity of session and service if the DNN (UE requested DNN) corresponds to a predetermined type of EDN or LADN. As already explained, in the terminology used herein, the mode for continuity of session and service includes establishing a new PDU session service for a second DNN different from the first DNN before releasing the old PDU session with the first DNN when UE1 moves out of the LADN service area corresponding to the first DNN. In one example, the second DNN is a DNN to which application context is transferred from the first DNN. The session and service continuity mode selection policy may be configured for UE1 as part of a UE Route Selection Policy (URSP). The policy may also be preconfigured for UE1. The policy may be provided from PCF 34 to UE 1 via AMF 31 during the registration procedure.

[0100] In step 1302, UE1 sends a NAS message containing a PDU Session Establishment Request to AMF31 to request establishment of a PDU Session for the DNN, indicating the selected session and the mode for service continuity.

[0101] According to this operation of UE1, when UE1 moves out of the LAD service area corresponding to the first DNN, a new PDU session service for a second DNN different from the first DNN can be established before releasing the old PDU session with the first DNN, which can help prevent the ACR procedure from failing when UE1 moves between different EDNs corresponding to different LADs.

[0102] Fifth Embodiment An example of a network architecture according to this embodiment is similar to the example described with reference to FIGS.

[0103] In this embodiment, the UE 1 provides an EEC function. The EEC 11 of the UE 1 determines to perform one of a plurality of ACR procedures in consideration of the UE 1 having moved out of the LADN service area associated with the first EDN. Figure 14 shows an example of the operation of the UE 1. In step 1401, the EEC 11 detects that the UE has moved out of the LADN service area associated with the EDN. In step 1402, the EEC 11 determines to perform one of a plurality of ACR procedures in consideration of the UE 1 having moved out of the LADN service area of ​​the first EDN.

[0104] In one example, when UE1 moves out of a LAN service area associated with a first EDN, EEC11 selects and executes an ACR procedure that does not involve message exchange between EEC11 and a S-EES in the first EDN. This ACR procedure may be the ACR procedure via T-EES described in Chapter 8.8.2.6 of Non-Patent Document 3. In other words, when UE1 moves out of a LAN service area associated with the first EDN, EEC11 selects and executes an ACR procedure via a Target EES (T-EES) belonging to a second EDN different from the first EDN. In one example, these operations may be performed when UE1 moves out of a LAN service area associated with the first EDN and the PDU session for the first EDN does not apply a session and service continuity mode.

[0105] The NAS layer of UE1 may send a notification to the EEC 11 of UE1 in response to detecting that UE1 is outside the LAN service area associated with the first EDN. The notification may indicate a session and service continuity mode to be applied to the PDU session for the first EDN. Furthermore, the notification may indicate a Tracking Area Identity (TAI) corresponding to the location of UE1 outside the LAN service area. The NAS layer of UE1 may obtain the TAI based on system information (System Information Block (SIB)) broadcast in the AN to which UE1 is moving. In this case, the EEC 11 may select a T-EES based on the TAI included in the notification. The TAI-based T-EES selection may be based on information already provisioned to UE1. The information may be preconfigured in UE1. Alternatively, the information may be provided to EEC 1 from the ECS 6 during a service provisioning procedure.

[0106] According to the operation of UE1 described in this embodiment, when UE1 moves from a first EDN (LADN) to a second EDN (LADN), if maintenance of the PDU session for the first EDN (LADN) is not guaranteed, the EEC 11 of UE1 selects and executes any ACR procedure that does not include message exchange between the EEC 11 and the S-EES in the first EDN. This can help prevent the ACR procedure from failing when UE1 moves between different EDNs corresponding to different LADNs.

[0107] Next, exemplary configurations of the UE 1, AF 5, AMF 31, SMF 32, and NEF 36 according to the above-described embodiments will be described below. FIG. 15 is a block diagram showing an exemplary configuration of the UE 1. A radio frequency (RF) transceiver 1501 performs analog RF signal processing for communication with a RAN node. The RF transceiver 1501 may include multiple transceivers. The analog RF signal processing performed by the RF transceiver 1501 includes frequency up-conversion, frequency down-conversion, and amplification. The RF transceiver 1501 is coupled to an antenna array 1502 and a baseband processor 1503. The RF transceiver 1501 receives modulation symbol data (or OFDM symbol data) from the baseband processor 1503, generates a transmit RF signal, and provides the transmit RF signal to the antenna array 1502. The RF transceiver 1501 also generates a baseband receive signal based on the receive RF signal received by the antenna array 1502 and provides the baseband receive signal to the baseband processor 1503. The RF transceiver 1501 may include an analog beamformer circuit for beamforming, which may include, for example, multiple phase shifters and multiple power amplifiers.

[0108] The baseband processor 1503 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communications. Digital baseband signal processing includes (a) data compression / decompression, (b) data segmentation / concatenation, (c) transmission format (transmission frame) generation / decomposition, (d) transmission path coding / decoding, (e) modulation (symbol mapping) / demodulation, and (f) generation of OFDM symbol data (baseband OFDM signal) using Inverse Fast Fourier Transform (IFFT). Meanwhile, control plane processing includes communication management for Layer 1 (e.g., transmit power control), Layer 2 (e.g., radio resource management and hybrid automatic repeat request (HARQ) processing), and Layer 3 (e.g., signaling related to attachment, mobility, and call management).

[0109] For example, the digital baseband signal processing by the baseband processor 1503 may include signal processing of a Service Data Adaptation Protocol (SDAP) layer, a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, a Medium Access Control (MAC) layer, and a Physical (PHY) layer. Also, the control plane processing by the baseband processor 1503 may include processing of a Non-Access Stratum (NAS) protocol, a Radio Resource Control (RRC) protocol, MAC Control Elements (CEs), and Downlink Control Information (DCIs).

[0110] The baseband processor 1503 may perform Multiple Input Multiple Output (MIMO) encoding and precoding for beamforming.

[0111] The baseband processor 1503 may include a modem processor (e.g., a Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., a Central Processing Unit (CPU) or a Micro Processing Unit (MPU)) that performs control plane processing. In this case, the protocol stack processor that performs control plane processing may be shared with the application processor 1504, which will be described later.

[0112] The application processor 1504 is also referred to as a CPU, MPU, microprocessor, or processor core. The application processor 1504 may include multiple processors (multiple processor cores). The application processor 1504 executes a system software program (operating system (OS)) and various application programs (e.g., a call application, a web browser, a mailer, a camera operation application, and a music playback application) read from the memory 1506 or a memory not shown, thereby realizing various functions of the UE 1.

[0113] In some implementations, the baseband processor 1503 and the application processor 1504 may be integrated on a single chip, as indicated by the dashed line (1505) in Figure 15. In other words, the baseband processor 1503 and the application processor 1504 may be implemented as a single System on Chip (SoC) device 1505. An SoC device is sometimes called a system Large Scale Integration (LSI) or chipset.

[0114] The memory 1506 is volatile memory, nonvolatile memory, or a combination thereof. The memory 1506 may include multiple physically independent memory devices. The volatile memory may be, for example, static random access memory (SRAM), dynamic RAM (DRAM), or a combination thereof. The nonvolatile memory may be mask read only memory (MROM), electrically erasable programmable ROM (EEPROM), flash memory, a hard disk drive, or any combination thereof. For example, the memory 1506 may include an external memory device accessible from the baseband processor 1503, the application processor 1504, and the SoC 1505. The memory 1506 may also include an internal memory device integrated within the baseband processor 1503, the application processor 1504, or the SoC 1505. Furthermore, the memory 1506 may include memory within a Universal Integrated Circuit Card (UICC).

[0115] The memory 1506 may store one or more software modules (computer programs) 1507 including instructions and data for performing the processes described in the above embodiments by the UE 1. In some implementations, the baseband processor 1503 or the application processor 1504 may be configured to read and execute the software modules 1507 from the memory 1506 to perform the processes by the UE 1 described in the above embodiments using the drawings.

[0116] In addition, the control plane processing and operations performed by UE1 described in the above embodiment can be realized by elements other than the RF transceiver 1501 and the antenna array 1502, i.e., at least one of the baseband processor 1503 and the application processor 1504, and the memory 1506 storing the software module 1507.

[0117] FIG. 16 shows an example of the configuration of a device that provides the function of the AF5. Devices that provide other network functions, such as the AMF 31, the SMF 32, and the NEF 36, may also have a configuration similar to that shown in FIG. 16. Referring to FIG. 16, the AF5 (or the AMF 31, the SMF 32, or the NEF 36) includes a network interface 1601, a processor 1602, and a memory 1603. The network interface 1601 is used, for example, to communicate with other network functions (NFs) or nodes. The network interface 1601 may include, for example, a network interface card (NIC) that complies with the IEEE 802.3 series.

[0118] The processor 1602 may be, for example, a microprocessor, a microprocessing unit (MPU), or a central processing unit (CPU). The processor 1602 may include multiple processors.

[0119] The memory 1603 is composed of volatile memory and nonvolatile memory. The memory 1603 may include multiple physically independent memory devices. The volatile memory is, for example, static random access memory (SRAM), dynamic RAM (DRAM), or a combination thereof. The nonvolatile memory is, for example, mask read only memory (MROM), electrically erasable programmable ROM (EEPROM), flash memory, or a hard disk drive, or any combination thereof. The memory 1603 may include storage located remotely from the processor 1602. In this case, the processor 1602 may access the memory 1603 via the network interface 1601 or an I / O interface (not shown).

[0120] The memory 1603 may store one or more software modules (computer programs) 1604 including instructions and data for performing processing by the AF5 (or the AMF 31, the SMF 32, or the NEF 36) described in the above-described embodiments. In some implementations, the processor 1602 may be configured to read and execute the software modules 1604 from the memory 1603 to perform processing by the AF5 (or the AMF 31, the SMF 32, or the NEF 36) described in the above-described embodiments.

[0121] As explained using Figures 15 and 16, each of the processors possessed by UE1, AF5, AMF31, SMF32, and NEF36 in the above-mentioned embodiments executes one or more programs including a group of instructions for causing a computer to perform the algorithms explained using the drawings.

[0122] The program includes instructions (or software code) that, when loaded into a computer, cause the computer to perform one or more functions described in the embodiments. The program may be stored on a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, computer-readable media or tangible storage media include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technologies, CD-ROM, digital versatile disk (DVD), Blu-ray disc or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage device. The program may also be transmitted on a transitory computer-readable medium or communication medium. By way of example and not limitation, transitory computer-readable media or communication media include electrical, optical, acoustic, or other forms of propagated signals.

[0123] The above-described embodiments are merely examples of application of the technical ideas obtained by the inventors of the present invention. In other words, the technical ideas are not limited to the above-described embodiments, and various modifications are possible.

[0124] For example, some or all of the above embodiments can be described as, but are not limited to, the following supplementary notes.

[0125] (Supplementary Note 1) A Session Management Function (SMF) node comprising: a memory; and at least one processor coupled to the memory, wherein the at least one processor is configured to: detect an event related to an Application Context Relocation (ACR) procedure after receiving a first event notification from an Access and Mobility management Function (AMF) node indicating that User Equipment (UE) is outside an Edge Data Network (EDN) service area or outside a Local Area Data Network (LADN) service area; and, in response to detecting the event related to the ACR procedure, initiate a procedure to release a Protocol Data Unit (PDU) Session for a Local Area Data Network (LADN) associated with the LADN service area, a procedure to release a PDU Session for an EDN associated with the EDN service area, or a procedure to deactivate a User Plane (UP) connection for the PDU Session. (Supplementary Note 2) The SMF node according to Supplementary Note 1, wherein the event related to the ACR procedure includes sending a second event notification from the SMF node to an Application Function (AF) node directly or via a Network Exposure Function (NEF) node, and then receiving a response corresponding to the second event notification from the AF node directly or via the NEF node. (Supplementary Note 3) The SMF node according to Supplementary Note 2, wherein the response indicates completion of the ACR procedure, including transfer of application context from a Source Edge Application Server (S-EAS) to a Target EAS (T-EAS).(Supplementary Note 4) The SMF node according to Supplementary Note 1, wherein the event related to the ACR procedure includes receiving, after sending a second event notification from the SMF node to an Application Function (AF) node directly or via a Network Exposure Function (NEF) node, a message from a Policy Control Function (PCF) node instructing to initiate a procedure to release a PDU session for an LADN associated with the LADN service area, a procedure to release a PDU session for an EDN associated with the EDN service area, or a procedure to deactivate a UP connection for the PDU session, and the message is sent based on information provided from the AF node to the PCF node via the NEF node and a Unified Data Management (UDM) node. (Supplementary Note 5) The SMF node according to any one of Supplements 2 to 4, wherein the second event notification includes notification of information indicating that the UE is outside the EDN service area or outside the LADN service area. (Supplementary Note 6) The SMF node according to any one of Supplements 2 to 4, wherein the second event notification includes a prior notification of the release of the PDU session for the EDN, a prior notification of the release of the PDU session for the LADN, or a prior notification of the deactivation of the UP connection. (Supplementary Note 7) The SMF node according to any one of Supplements 2 to 6, wherein the at least one processor is configured to: receive a request from the AF node or the NEF node to subscribe to a service providing the second event notification for the PDU session, and detect an event related to the ACR procedure after receiving the first event notification, on condition that the request includes an indication instructing the AF node to wait for a response from the AF node before initiating a procedure to release a PDU session for an LADN associated with the LADN service area, a procedure to release a PDU session for an EDN associated with the EDN service area, or a procedure to deactivate a UP connection for the PDU session.(Supplementary Note 8) The SMF node according to any one of Supplements 1 to 7, wherein the event related to the ACR procedure includes expiration of a time for waiting for completion of the ACR procedure. (Supplementary Note 9) The SMF node according to Supplementary Note 8, wherein the at least one processor is configured to start a timer to count a time for waiting for completion of the ACR procedure after receiving the first event notification. (Supplementary Note 10) The SMF node according to Supplementary Note 9, wherein the at least one processor is configured to determine whether starting the timer is required before a PDU session release procedure or a UP connection deactivation procedure based on a Data Network Name (DNN) of the LADN or the EDN. (Supplementary Note 11) The SMF node according to Supplementary Note 9, wherein the at least one processor is configured to determine whether starting the timer is required before a PDU session release procedure or a UP connection deactivation procedure based on a type of the LADN or the EDN. (Supplementary Note 12) The SMF node according to Supplementary Note 9, wherein the at least one processor is configured to determine whether starting the timer is required before a release procedure for the PDU Session or a deactivation procedure for the UP connection based on whether the LADN or the LADN is associated with the timer. (Supplementary Note 13) The SMF node according to any one of Supplements 1 to 12, wherein the LADN service area or the EDN service area is a set of one or more Tracking Areas (TAs).(Supplementary Note 14) A method performed by a Session Management Function (SMF) node, comprising: detecting an event related to an Application Context Relocation (ACR) procedure after receiving a first event notification from an Access and Mobility management Function (AMF) node, the first event notification indicating that User Equipment (UE) is outside an Edge Data Network (EDN) service area or a Local Area Data Network (LADN) service area; and in response to detecting the event related to the ACR procedure, initiating a procedure to release a Protocol Data Unit (PDU) Session for a Local Area Data Network (LADN) associated with the LADN service area, a procedure to release a PDU Session for an EDN associated with the EDN service area, or a procedure to deactivate a User Plane (UP) connection for the PDU Session. (Supplementary Note 15) A program causing a computer to perform a method for a Session Management Function (SMF) node, the method comprising: detecting an event related to an Application Context Relocation (ACR) procedure after receiving a first event notification from an Access and Mobility management Function (AMF) node, the first event notification indicating that User Equipment (UE) is outside an Edge Data Network (EDN) service area or a Local Area Data Network (LADN) service area; and initiating, in response to detecting the event related to the ACR procedure, a procedure for releasing a Protocol Data Unit (PDU) Session for a Local Area Data Network (LADN) associated with the LADN service area, a procedure for releasing a PDU Session for an EDN associated with the EDN service area, or a procedure for deactivating a User Plane (UP) connection for the PDU Session.(Supplementary Note 16) An Application Function (AF) node comprising: a memory; and at least one processor coupled to the memory, wherein the at least one processor is configured to: receive an event notification from a Session Management Function (SMF) node directly or via a Network Exposure Function (NEF) node; and send a response to the event notification to the SMF node directly or via the NEF node after an Application Context Relocation (ACR) procedure, including a transfer of an application context from a Source Edge Application Server (S-EAS) to a Target EAS (T-EAS), wherein the response is a message that causes the SMF node to initiate a procedure to release a PDU Session for a Local Area Data Network (LADN), a procedure to release a PDU Session for an Edge Data Network (EDN), or a procedure to deactivate a User Plane (UP) connection for the PDU Session. (Supplementary Note 17) The AF node according to Supplementary Note 16, wherein the event notification indicates that User Equipment (UE) is out of the service area of ​​the EDN or out of the service area of ​​the LADN, indicates a preliminary notification of the release of the PDU Session for the LADN, indicates a preliminary notification of the release of the PDU Session for the EDN, or indicates a preliminary notification of the deactivation of the UP connection for the PDU Session.(Supplementary Note 18) A method performed by an Application Function (AF) node, comprising: receiving an event notification from a Session Management Function (SMF) node directly or via a Network Exposure Function (NEF) node; and sending a response to the event notification to the SMF node directly or via the NEF node after an Application Context Relocation (ACR) procedure including a transfer of application context from a Source Edge Application Server (S-EAS) to a Target EAS (T-EAS) is completed, wherein the response is a message that causes the SMF node to initiate a procedure to release a PDU Session for a Local Area Data Network (LADN), a procedure to release a PDU Session for an Edge Data Network (EDN), or a procedure to deactivate a User Plane (UP) connection for the PDU Session.(Supplementary Note 19) A program for causing a computer to perform a method for an Application Function (AF) node, the method comprising: receiving an event notification from a Session Management Function (SMF) node directly or via a Network Exposure Function (NEF) node; and sending a response to the event notification to the SMF node directly or via the NEF node after an Application Context Relocation (ACR) procedure including transfer of application context from a Source Edge Application Server (S-EAS) to a Target EAS (T-EAS) is completed, the response being a message that causes the SMF node to initiate a procedure to release a PDU Session for a Local Area Data Network (LADN), a procedure to release a PDU Session for an Edge Data Network (EDN), or a procedure to deactivate a User Plane (UP) connection for the PDU Session.(Supplementary Note 20) A User Equipment (UE), comprising: a memory; and at least one processor coupled to the memory, wherein the at least one processor is configured to: select a mode for continuity of session and service if a first Data Network Name (DNN) corresponds to a predetermined type of Local Area Data Network (LADN); and send a Non-Access Stratum (NAS) message including a PDU Session Establishment Request indicating the selected mode to an Access and Mobility management Function (AMF) node to request establishment of a first Protocol Data Unit (PDU) Session for the first DNN, wherein the mode for continuity of session and service comprises establishing a second PDU Session for a second DNN to which an application context is transferred from the first DNN before releasing the first PDU Session when the UE moves out of a Local Area Data Network service area corresponding to the first DNN.(Supplementary Note 21) A method performed by a User Equipment (UE), comprising: selecting a mode for continuity of session and service if a first Data Network Name (DNN) corresponds to a predetermined type of Local Area Data Network (LADN); and sending a Non-Access Stratum (NAS) message including a PDU Session Establishment Request indicating the selected mode to an Access and Mobility management Function (AMF) node to request establishment of a first Protocol Data Unit (PDU) Session for the first DNN; wherein the mode for continuity of session and service comprises establishing a second PDU Session for a second DNN to which an application context is transferred from the first DNN before releasing the first PDU Session when the UE moves out of a Local Area Data Network service area corresponding to the first DNN.(Supplementary Note 22) A program for causing a computer to perform a method for User Equipment (UE), the method comprising: selecting a mode for continuity of session and service if a first Data Network Name (DNN) corresponds to a predetermined type of Local Area Data Network (LADN); and sending a Non-Access Stratum (NAS) message including a PDU Session Establishment Request indicating the selected mode to an Access and Mobility management Function (AMF) node to request establishment of a first Protocol Data Unit (PDU) Session for the first DNN; the mode for continuity of session and service comprises establishing a second PDU Session for a second DNN to which an application context is transferred from the first DNN before releasing the first PDU Session when the UE moves out of a Local Area Data Network service area corresponding to the first DNN. (Supplementary Note 23) A User Equipment (UE) comprising: a memory; and at least one processor coupled to the memory, wherein the at least one processor is configured to provide an Edge Enabler Client (EEC) function, the EEC function comprising: determining to perform one of a plurality of Application Context Relocation (ACR) procedures, taking into account that the UE has moved out of a Local Area Data Network (LADN) service area associated with a first Edge Data Network (EDN).(Supplementary Note 24) The UE of Supplementary Note 23, wherein the EEC function is configured to select and perform any ACR procedure that does not include message exchange between the EEC and a Source Edge Enabler Server (S-EES) in the first EDN when the UE moves out of the Local Area Network (LADN) service area associated with the first EDN. (Supplementary Note 25) The UE of Supplementary Note 23, wherein the EEC function is configured to select and perform an ACR procedure via a Target EES (T-EES) belonging to a second EDN different from the first EDN when the UE moves out of the Local Area Network (LADN) service area associated with the first EDN. (Supplementary Note 26) The UE of any one of Supplements 23 to 25, wherein the EEC function is configured to determine to perform any of a plurality of ACR procedures if a Protocol Data Unit (PDU) Session for the first EDN does not apply a mode for continuity of session and service. (Supplementary Note 27) The UE of any one of Supplements 23 to 26, wherein the at least one processor is configured to provide a Non-Access Stratum (NAS) layer function, the NAS layer function comprising: in response to detecting that the UE is out of the Local Access Network (LADN) service area associated with the first EDN, sending a notification to the EEC function, the notification indicating a mode for continuity of session and service to be applied to a Protocol Data Unit (PDU) Session for the first EDN. (Supplementary Note 28) The UE of Supplementary Note 27, wherein the notification indicates a Tracking Area Identity (TAI) corresponding to the location of the UE outside the Local Access Network (LADN) service area. (Supplementary Note 29) The UE of Supplementary Note 28, wherein the EEC function comprises selecting a Target EES (T-EES) based on the TAI included in the notification.(Supplementary Note 30) A method performed by a User Equipment (UE), comprising: providing an Edge Enabler Client (EEC) function, wherein the EEC function determines to perform one of a plurality of Application Context Relocation (ACR) procedures in consideration that the UE has moved out of a Local Area Data Network (LADN) service area associated with a first Edge Data Network (EDN). (Supplementary Note 31) A program for causing a computer to perform a method for User Equipment (UE), comprising: providing an Edge Enabler Client (EEC) function, wherein the EEC function determines to perform one of a plurality of Application Context Relocation (ACR) procedures in consideration that the UE has moved out of a Local Area Data Network (LADN) service area associated with a first Edge Data Network (EDN).

[0126] This application claims priority based on Japanese Patent Application No. 2021-084223, filed on May 18, 2021, the disclosure of which is incorporated herein in its entirety.

[0127] 1 User Equipment (UE) 2 Access Network (AN) 3 3GPP core network 5 Application Function (AF) 6 Edge Configuration Server (ECS) 7 Edge Data Network (EDN) 8 Public Land Mobile Network (PLMN) 11 Edge Enabler Client (EEC) 12 Application client (AC) 31 Access and Mobility management Function (AMF) 32 Session Management Function (SMF) 33 User Plane Function (UPF) 34 Policy Control Function (PCF) 35 Unified Data Management (UDM) 36 Network Exposure Function (NEF) 41, 42 Local Area Data Network (LADN) 43 Data Network (DN) 71 Edge Enabler Server (EES) 72 Edge Application Server (EAS) 1503 Baseband processor 1504 Application processor 1506 Memory 1507 Module 1602 Processor 1603 Memory 1604 Module

Claims

1. A Session Management Function (SMF) node, comprising: Memory, at least one processor coupled to the memory; Equipped with The at least one processor Establish a PDU session between the User Equipment (UE) and the Protocol Data Unit (PDU) Session Anchor (PSA), receiving a first message from an Application Function (AF) via a Network Exposure Function (NEF) node upon edge relocation, the first message including a first timer, the first timer indicating a period for maintaining a first PSA corresponding to the PDU session; maintain the PSA corresponding to the PDU session based on the first timer; SMF node.

2. A method performed by a Session Management Function (SMF) node, comprising: Establish a PDU session between the User Equipment (UE) and the Protocol Data Unit (PDU) Session Anchor (PSA), receiving a first message from an Application Function (AF) via a Network Exposure Function (NEF) node upon edge relocation, the first message including a first timer, the first timer indicating a period for maintaining a first PSA corresponding to the PDU session; maintain the PSA corresponding to the PDU session based on the first timer; method.