SMF node and method

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

Technical Field

[0001] The present disclosure relates to a wireless communication network, and particularly to PDU Session management.

Background Art

[0002] A 5G system (5GS) connects a wireless terminal (user equipment (UE)) to a data network (Data Network (DN)). In a 5G architecture, the connectivity service between the UE and the DN is 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 the UE and the DN. A PDU Session is used to provide a PDU connectivity service (i.e., the exchange of PDUs between the UE and the DN). A PDU Session is established between the UE and a User Plane Function (UPF) (i.e., the PDU Session anchor) to which the UE and the DN are connected. From the perspective of data transfer, a PDU Session is composed of a tunnel (N9 tunnel) in the 5G core network (5G core network (5GC)), a tunnel (N3 tunnel) between the 5GC and the access network (Access Network (AN)), and one or more radio bearers.

[0003] Non-Patent Document 2 specifies the procedures for establishing and releasing a PDU session. 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 the 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 Non-Patent Document 1. Access to DNs via a PDU Session for an LADN is only available within 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 a UE moves outside an LADN service area, the Session Management Function (SMF) must release the PDU Session for that LADN or deactivate the UP connection for that PDU Session. The UP connection (or resources) includes the data radio barer of the Radio Access Network (RAN) and the N3 tunnel between the RAN and the UPF. That is, deactivating the UP connection means releasing the data radio barer 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 involves establishing (configuring) 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 a specification for an enabling layer to facilitate communication between application clients (ACs) running on the UE and applications deployed at the edge. According to the EDGEAPP architecture, edge applications provided by Edge Application Servers (EASs) are provided to the ACs on the UE via the Edge Enabler Client (EEC) of that UE, through the Edge Configuration Server (ECS) and Edge Enabler Server (EES).

[0006] As described in Chapter A.2 of Non-Patent Document 3, there are various deployment models for DN implementations. For 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). Using this option, the Public Land Mobile Network (PLMN) supports edge computing services in the Edge Data Network (EDN) service area, which is the same as the LADN service area. The LADN service area is the service area where edge computing is supported. Individual EAS within an LADN can support service areas the same size as or smaller than the LADN.

[0007] The EDGEAPP architecture supports various Application Context Relocation (ACR) procedures for service continuity. An application context is a set of data about the AC residing in the EAS. Application context relocation involves transferring the 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 UE mobility events or non-UE mobility events. 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, EAS or EDN overload conditions, and EAS maintenance (e.g., graceful shutdown of the EAS). [Prior art documents] [Non-patent literature]

[0008] [Non-Patent Document 1] 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 2021 [Non-Patent Document 2] 3GPP 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 2021 [Non-Patent Document 3] 3GPP 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 2021 [Non-Patent Document 4] 3GPP 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 [Overview of the project] [Problems that the invention aims to solve]

[0009] The inventors considered a deployment model in which edge computing services are delivered via an edge-dedicated data network and identified several challenges. One of these challenges relates to application context relocation (ACR).

[0010] Specifically, when a UE moves from one EDN (or LADN) to another, in other words, when a UE switches from a connection to one EDN (LADN) to another, it may be preferable to be able to perform an Application Context Relocation (ACR) between these two EDNs (LADNs). That is, it may be preferable for the application context to be transferred or taken over 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 outside the current EDN service area or 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. If 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 that case, the ACR procedure involving signaling between the UE (EEC) and S-EES may not be able to be completed successfully. For example, in 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 that the embodiments disclosed herein seek to achieve is to provide apparatus, methods, and programs that contribute to preventing ACR procedure failures when a UE travels between EDNs (or LADNs). It should be noted that this objective is only one of several objectives that the embodiments disclosed herein seek to achieve. Other objectives or problems and novel features will be evident from the description herein or from the accompanying drawings. [Means for solving the problem]

[0012] In a first embodiment, the SMF node includes memory and at least one processor coupled to the memory. The at least one processor is configured to detect events relating to an Application Context Relocation (ACR) procedure after receiving a first event notification from the AMF node indicating that the UE is outside the EDN service area or the LADN service area. Furthermore, the at least one processor is configured 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 an UP connection for the PDU session in response to detecting an event relating to the ACR procedure.

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

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

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

[0016] In a fifth aspect, the UE includes 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 LADN. Furthermore, the at least one processor is configured to send a Non-Access Stratum (NAS) message containing a PDU Session Establishment Request indicating the selected mode to an AMF node to request the 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 the application context will be transferred from the first DNN before releasing the first PDU Session if the UE moves outside the LADN service area corresponding to the first DNN.

[0017] In a sixth aspect, the method performed by the UE includes (a) selecting a mode for continuity of session and service if the first DNN corresponds to a predetermined type of LADN, and (b) sending a NAS message to an AMF node containing a PDU Session Establishment Request indicating the selected mode to request the 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 the application context will be transferred from the first DNN before releasing the first PDU Session if the UE moves outside the LADN service area corresponding to the first DNN.

[0018] In a seventh aspect, the UE includes a memory and at least one processor coupled to the memory. The at least one processor is configured to provide an EEC function. The EEC function includes determining to execute any one of a plurality of ACR procedures in consideration of the UE moving outside the LADN service area related to the first EDN.

[0019] In an eighth aspect, a method performed by a UE includes providing an EEC function. The EEC function includes determining to execute any one of a plurality of ACR procedures in consideration of the UE moving outside the LADN service area related to the first EDN.

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

Advantages of the Invention

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

Brief Description of the Drawings

[0022] [Figure 1] It is a diagram showing a configuration example of a wireless communication network according to an embodiment. [Figure 2] It is a diagram showing an example of a deployment model of EDNs according to an embodiment. [Figure 3] It is a diagram showing an example of a 3GPP EDGEAPP architecture according to an embodiment. [Figure 4] It is a flowchart showing an example of the operation of the SMF according to an embodiment. [Figure 5] It is a flowchart showing an example of the operation of the SMF according to an embodiment. [Figure 6] It is a flowchart showing an example of the operation of the AF according to an embodiment. [Figure 7] This is a sequence diagram showing an example of the operation of the AMF, SMF, NEF, and AF according to the embodiment. [Figure 8] This is a sequence diagram showing an example of the operation of the SMF, NEF, and AF according to the embodiment. [Figure 9] This is a flowchart illustrating an example of the operation of the SMF according to the embodiment. [Figure 10] This is a sequence diagram showing an example of the operation of the AMF, SMF, NEF, and AF according to the embodiment. [Figure 11] This is a flowchart illustrating an example of the operation of the SMF according to the embodiment. [Figure 12] This is a sequence diagram showing an example of the operation of the AMF and SM according to the embodiment. [Figure 13] A flowchart illustrating an example of the operation of the UE according to the embodiment. [Figure 14] This is a flowchart illustrating an example of the operation of the EEC of the UE according to the present invention. [Figure 15] This is a block diagram showing an example configuration of a UE according to the embodiment. [Figure 16] This is a block diagram showing examples of the configurations of AMF, SMF, NEF, and AF according to the embodiment. [Modes for carrying out the invention]

[0023] The following describes specific embodiments in detail with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numerals, and redundant explanations are omitted where necessary for clarity.

[0024] The multiple embodiments described below can be implemented independently or in combination as appropriate. These multiple embodiments have novel features that differ from each other. Therefore, these multiple embodiments contribute to solving different objectives or problems and contribute to producing different effects.

[0025] The following embodiments are described primarily with reference to 3GPP systems (e.g., 5G systems (5GS)). However, these embodiments may be applied to other wireless communication systems.

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

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

[0028] A wireless terminal (ie.e., UE) 1 communicates with a data network (DN) using 3GPP (e.g., 5G) connectivity services. More specifically, UE 1 is connected to a (wireless) access network (e.g., 5G Access Network (5GAN)) 2 and communicates with the DN via one or more User Plane Functions (UPFs) 33 within a 3GPP core network 3 (e.g., 5G core network (5GC)). Figure 1 shows an example where two UPFs 33 are arranged in series, but this is just an example; there may be one UPF 33, or two or more UPFs 33 may be arranged in parallel. The 3GPP core network 3 is not limited to, but may be, for example, 5GC. The 3GPP core network 3 may also include networks other than 5G (e.g., future 6G, or non-3GPP).

[0029] UE1 can communicate with multiple DNs simultaneously. As an example, Figure 1 shows three DNs: LADN41, LADN42, and DN43. UE1 may communicate with one or more of LADN41, LADN42, and DN43 simultaneously. However, UE1 is only permitted to access LADN41 via a PDU session for LADN41 if UE1 is within LADN41's LADN service area. Similarly, UE1 is only permitted to access LADN42 via a PDU session for LADN42 if UE1 is within LADN42's 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.

[0030] In the architecture of 5G and later 3GPP systems, connectivity services between a 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 DN. PDU Sessions are used to provide PDU connectivity services (i.e., the exchange of PDUs between UE1 and DN). UE1 establishes one or more PDU Sessions with the UPF33 (i.e., PDU Session Anchor (PSA)) to which UE1 and DN are connected. From a data transfer perspective, a single PDU Session consists of a tunnel within the 3GPP core network 3 (i.e., an N9 tunnel), a tunnel between the 3GPP core network 3 and AN2 (i.e., an N3 tunnel), and one or more radio bearers between UE1 and AN2. Although not shown in Figure 1, UE1 may establish multiple PDU sessions with each of the multiple (PSA) UPFs33 in order to concurrently access multiple DNs or multiple Data Network Access Identifiers (DNAIs) that represent (sub)networks (or entities) (e.g., LADN41 and DN43).

[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. AMF 31 provides the termination of the RAN Control Plane (CP) interface (i.e., N2 interface). AMF 31 terminates a single signaling connection (i.e., N1 NAS signalling connection) with UE1 and provides registration management, connection management, and mobility management. AMF 31 provides NF services (i.e., Namf interface) to NF consumers (e.g., other AMFs and SMF 32) over a service-based interface (i.e., Namf interface). The NF services provided by AMF 31 include communication services (Namf_Communication). These communication services enable NF consumers (e.g., SMF 32) to communicate with UE1 or AN2 via 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. SMF32 manages PDU Sessions. SMF32 sends and receives SM signaling messages (NAS-SM messages, N1 SM messages) to and from the Non-Access-Stratum (NAS) Session Management (SM) layer of UE1 via communication services provided by AMF31. SMF32 provides Network Function (NF) services on a service-based interface (i.e., Nsmf interface) to NF consumers (e.g., AMF31, other SMFs, and NEF36). The NF services provided by SMF32 include the PDU Session Management Service (Nsmf_PDUSession). This NF service enables NF consumers (e.g., AMF31) to handle PDU Sessions. The NF services provided by SMF32 also include an event notification service (Nsmf_EventExposure). The service operations exposed by this NF service enable NF consumers (e.g., NEF36, AF5) 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 UPF 33s shown in Figure 1) interconnected via the N9 interface. The UP path for one PDU Session of 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 for routing user plane data (e.g., Internet Protocol (IP) packets) of the PDU Session from UE1 to DN (e.g., LADN41, LADN42, or DN43) and vice versa. The UP path includes at least one UPF33 and an N6 interface with the DN. The UP path may include one or more N9 tunnels, which are tunnels between two UPF33s.

[0034] The Policy Control Function (PCF)34 is one of the network function nodes within the control player of the 3GPP core network 3. PCF34 supports interactions with access and mobility policy enforcement within AMF31 via a service-based interface (i.e., NPCF interface). PCF34 provides access and mobility management-related policies to AMF31. Furthermore, PCF34 provides session-related policies to SMF32. Session-related policies include PDU session-related policy information and Policy and Charging Control (PCC) rule information. PCC rule information includes control information related to AF influence on traffic routing (i.e., AF-influenced Traffic Steering Enforcement Control information).

[0035] Unified Data Management (UDM)35 is one of the network function nodes in the control player of the 3GPP core network3. UDM35 provides access to a database (i.e., User Data Repository (UDR)) where subscriber data (subscription information) is stored. UDM35 provides NF services to NF consumers (e.g., AMF31, SMF32) on a service-based interface (i.e., Nudm interface). The NF services provided by UDM35 include subscriber data management services. These NF services enable NF consumers (e.g., AMF31, PCF34) to retrieve subscriber data and provide updated subscriber data to the NF consumers. UDM35 may also be referred to as UDR from the perspective of subscriber data management. Similarly, UDR may also be referred to as UDM35.

[0036] The Network Exposure Function (NEF)36 is one of the network function nodes within the control player of the 3GPP core network 3. NEF36 has a role similar to the Service Capability Exposure Function (SCEF) of the Evolved Packet System (EPS). Specifically, NEF36 supports the exposure of services and capabilities from the 3GPP system to applications and network functions both inside and outside the operator network. NEF36 provides NF services to NF consumers (e.g., AF5) over a service-based interface (i.e., the Nnef interface). The NF services provided by NEF36 include the event notification service (Nnef_EventExposure). The 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 NEF36 include a service for Application Function influence on traffic routing (Nnef_TrafficInfluence). The service operations exposed by this NF service enable NF consumers (e.g., AF5) to make requests that influence the traffic routing of PDU Session(s) of a particular UE.

[0037] Application Function (AF) 5 interacts with the 3GPP core network 3. For example, AF 5 interacts with the 3GPP core network 3 to support Application Function influence on traffic routing. Depending on the deployment of AF 5 and the MNO's policies, AF 5 may interact directly with network functions within the 3GPP core network 3. Otherwise, AF 5 interacts with network functions within the 3GPP core network 3 via NEF 36. AF 5 may include one or more computers. For example, AF 5 may include one or more servers (e.g., content delivery server, online game server) that communicate with UE 1 at the application layer, and a controller (i.e., AF in the 3GPP definition) that works with these one or more servers and interacts with the 3GPP core network 3 (e.g., NEF 36, and SMF 32). AF 5 may include multiple servers in a distributed configuration. For example, AF5 may include multiple edge computing servers located in (or connected to) LADN41 and LADN42, in addition to the central server located in (or connected to) DN43. In the example in Figure 1, AF5 may communicate with the running application on the UE1 processor via at least one of LADN41, LADN42, and DN43.

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

[0039] Figure 2 shows an example of an Edge Data Networks (EDNs) deployment model. The Public Land Mobile Network (PLMN) 8 includes AN2 and the 3GPP core network 3. In the example in Figure 2, EDN A(201) and EDN B(202) are Edge-dedicated Data Networks deployed as LADNs. Specifically, LADN41 includes EDN A(201), and LADN42 includes EDN B(202). The service area of ​​EDN A(201) is the same as the LADN service area of ​​LADN41. The service area of ​​EDN B(202) is the same as the LADN service area of ​​LADN42. The service area of ​​the EES within EDN A(201) is equal to or a subset of the EDN service area (i.e., the LADN service area of ​​LADN41). The service area of ​​each EAS within EDN A(201) is equal to or a subset of the service area of ​​the corresponding EES. Similarly, the service area of ​​an EES within EDN B(202) is equal to or a subset of the EDN service area (i.e., the LADN service area of ​​LADN42). The service area of ​​each EAS within EDN B(202) is equal to or a subset of the service area of ​​the corresponding EES.

[0040] As shown in Figure 2, user-plane access to LADN41, LADN42, and DN43 may be distinguished by DN Access Identifiers (DNAIs). A DNAI is an identifier for user-plane access to one or more DNs to which the application is deployed.

[0041] Figure 3 shows an example of the 3GPP EDGEAPP architecture according to this embodiment. Each element 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 running software instance on dedicated hardware, or as an instantiated virtualization function on an application platform.

[0042] In the example in Figure 3, UE1 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 on and operate on UE1. Although not explicitly shown in Figure 3, UE1 communicates with the 3GPP core network 3 (e.g., (5GC)) via AN2. This allows UE1 to provide connectivity to the data network via AN2 and the 3GPP core network 3 for the EEC 11 and AC(s) 12.

[0043] EEC11 provides the supporting functions required by AC(s)12. Specifically, EEC11 provides provisioning of configuration information to enable the exchange of application data traffic with Edge Application Servers (EAS). Furthermore, EEC11 provides functionality for discovering one or more EASs available within EDN7. EEC11 uses the EAS endpoint information obtained through EAS discovery to route outgoing application data traffic to the EAS. In addition, EEC11 provides functionality for the registration, update, and de-registration of EES71 and EAS(s)72.

[0044] Each AC12 is an application running on UE1. Each AC12 connects to one or more EASs to utilize edge computing services and exchanges application data traffic with these EASs.

[0045] A single EDN7 includes one or more EESs71 and one or more EASs72. As already described, EDN7 may also be an LADN. For example, the EDN7 in Figure 3 may be an edge-only data network deployed as an LADN41 or 42 shown in Figures 1 and 2. The EESs71 and EASs72 may be included in the AF5 shown in Figure 1.

[0046] Each EES71 provides supporting functions required by EAS(s)72 and EEC11. Specifically, each EES71 provides EEC11 with provisioning of configuration information, thereby enabling the exchange of application data traffic with EAS(s)72. Each EES71 provides registration, update, and de-registration functions for EEC11 and EAS(s)72. Each EES71 provides application context transfer functions between EASs. This function is required for application context relocation (or edge application mobility) for service continuity. An application context is a set of data about the AC that resides in the EAS. Application context relocation involves transferring the application context about the user (i.e., AC) from the Source EAS (or old EDN or old LADN) to the Target EAS (or new EDN or new LADN). Application context relocation is triggered by either UE mobility events or non-UE mobility events. 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, EAS or EDN overload conditions, and EAS maintenance (e.g., graceful shutdown of EAS).

[0047] Furthermore, each EES71 supports the functionality of Application Programming Interface (API) invoker and API exposing function. Each EES71 provides ACR management event notifications to EAS(s)72. The ACR management event notifications function notifies EASs of UE mobility events or non-UE mobility events that trigger Application Context Relocation (ACR) procedures 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 a UE has moved into or out of a specific location or area (i.e., "Presence-In-Area of ​​Interest (AOI)-Report"). EAS(s)72 subscribe to these events provided by EES71 in advance in order to receive the notifications they desire. Here, “a 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 EES71 may interact with the 3GPP core network 3 directly (e.g., via PCF34) or indirectly (e.g., via NEF36 or Service Capability Exposure Function (SCEF)) to access the services and capabilities of network functions within the 3GPP core network 3.Each EES71 may support the external exposure of 3GPP network functions services and capabilities to EAS(s)72. Each EES71 may support Application Function influence on traffic routing and interact with the 3GPP core network 3.

[0048] Each EAS72 is located in EDN7 and performs 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. Here, the cloud means a central cloud (e.g., DN43 in Figures 1 and 2) located further from UE1 than EDN7 (e.g., LADN41 or 42 in Figures 1 and 2). Therefore, an application server in the cloud means a server located in a centralized location (e.g., a centralized data center). Each EAS72 may consume or utilize 3GPP core network capabilities. Each EAS72 may directly invoke the 3GPP core network capabilities API. Alternatively, each EAS72 may consume or utilize 3GPP core network capabilities via EES71, or via NEF36 or SCEF. Each EAS72 may support Application Function influence on traffic routing and interact with the 3GPP core network 3.

[0049] The Edge Configuration Server (ECS) 6 provides the supporting functions required by EEC 11 to connect to EES(s) 71. Specifically, ECS 6 provides provisioning of edge configuration information to EEC 11. This edge configuration information includes information for EEC 11 to connect to EES(s) 71 (e.g., service area information applicable to LADN) and information for establishing a connection with EES(s) 71 (e.g., Uniform Resource Identifier (URI)). ECS 6 provides registration, update, and de-registration functions for EES(s) 71. Furthermore, ECS 6 supports API invoker and API exposing function functions. ECS 6 may interact directly (e.g., via PCF 34) or indirectly (e.g., via 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. ECS6 may be located within the MNO domain providing the 3GPP core network 3, or in a third-party domain of a service provider (e.g., Edge Computing Service Provider (ECSP)). ECS6 may be located in a central cloud (e.g., DN43 in Figures 1 and 2). ECS6 may be included in AF5 as shown in Figure 1.

[0050] The configuration example in Figure 3 shows only representative elements for the sake of explanation. For example, ECS6 may be connected to multiple EDNs.

[0051] The operation of SMF32 according to this embodiment will be described below. If UE1 moves outside the EDN service area or the LADN service area, SMF32 will not immediately release the PDU Session for the EDN or LADN, or deactivate the UP connection for the PDU Session, but will do so after a period of time. Specifically, SMF32 will release the PDU Session for the EDN or LADN, or deactivate the UP connection for the PDU Session, in response to detecting an event related to the ACR procedure. SMF32 may detect an event related to the ACR procedure after receiving a first event notification from AMF31 indicating that UE1 is outside the EDN service area or the LADN service area.

[0052] An event related to the ACR procedure may be an event indicating that AF5 has successfully completed the ACR procedure. An event related to the ACR procedure may be an event that enables AF5 to successfully complete the ACR procedure. An event related to the ACR procedure may be the receipt or detection of a response from AF5 indicating that the ACR procedure has been successfully completed. In this case, SMF32 may send an event notification (also called a second event notification) to AF5 and wait for a response from AF5. Here, the second event notification may be a notification indicating that UE1 is outside the EDN service area or the LADN service area, or a prior notification of the release of the PDU session for EDN, a prior notification of the release of the PDU session for LADN, or a prior notification of the deactivation of the UP connection. Furthermore, the response from AF5 indicating that the ACR procedure has been successfully completed may be a response to the notification of the second event. Successful completion of the ACR procedure may include the transfer of the application context from the Source Edge Application Server (S-EAS) to the Target EAS (T-EAS).

[0053] Alternatively, an event relating to the ACR procedure may be the SMF32 receiving a message from the PCF34 instructing it to initiate a procedure to release the PDU Session for the EDN or LADN, or a procedure to deactivate the UP connection for the PDU Session. In this case, the PCF34 may decide to send the message based on information provided to the PCF34 from the AF5 (e.g., S-EES) via the NEF36 and UDM35.

[0054] Alternatively, an event related to the ACR procedure may be the elapsed (or expiration) of a predetermined grace period for waiting for AF5 to complete the ACR procedure. In this case, if UE1 moves outside the EDN service area or the LADN service area, SMF32 will wait for the grace period to expire before initiating the release of the PDU session for the EDN or LADN or the deactivation of the UP connection. Deactivating the UP connection means releasing the data radio bar of (Radio) Access Network ((R)AN)2 that constitutes the UP connection, and the N3 tunnel between (R)AN2 and UPF33. Similarly, activating the UP connection means establishing (setting up) the data radio bar of (Radio) Access Network ((R)AN)2 that constitutes the UP connection, and the N3 tunnel between (R)AN2 and UPF33.

[0055] SMF32 may perform this action only with respect to a specific EDN, a specific LADN (LADN DNN), a specific PDU Session, or specific UEs. If UE1 moves outside the LADN service area and the LADN belongs to a specific LADN, SMF32 may wait for a grace period to expire before beginning to release the PDU Session or deactivate the UP connection for that LADN. Similarly, if UE1 moves outside the EDN service area and the EDN belongs to a specific LADN, SMF32 may wait for a grace period to expire before beginning to release the PDU Session or deactivate the UP connection for that EDN.

[0056] Specific LADNs may be defined by their type. Specific LADNs may be distinguished from other LADNs by their LADN DNN. Specific EDNs may be defined by their type. 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. 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] The fact that UE1 is outside the EDN service area may also mean that UE1 is outside the EES service area or the EAS service area. In other words, in the terminology of this specification, the EDN service area may be the same as the EES service area or the EAS service area. The EES service area is the service area provided by the EES within the EDN. The EAS service area is the service area provided by the EAS within the EDN. The EES service area may be a topological service area or a geographical service area. Similarly, the EAS service area may be a topological service area or a geographical service area. A topological service area is defined in relation to the UE's connection points 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 defined as an area using geographical coordinates, a circle whose center is denoted by geographical coordinates, or a polygon whose corners are denoted by geographical coordinates. Geographical service areas can also be represented in other ways, such as by well-known buildings, parks, arenas, civic addresses, or ZIP codes.

[0058] SMF32 may be pre-configured by the MNO with specific LADNs or EDNs. SMF32 may obtain settings indicating specific LADNs or EDNs from AMF31 or UDM35. For example, specific LADNs may be LADNs for EDNs. Specific LADNs or EDNs may be managed in UDM35 as subscriber information for UE1. In this case, information regarding specific LADNs or EDNs may be transferred from UDM35 to AMF31 via the Nudm_SDM_Get service when UE1 performs the registration procedure. Then, when UE1 establishes a PDU Session for the LADN, SMF32 may be notified of information regarding specific LADNs or EDNs from AMF31 via the Nsmf_PDUSession_CreateSMContext Request message or the Nsmf_PDUSession_UpdateSMContext Request message. Alternatively, for example, when UE1 establishes a PDU Session for the LADN or EDN, SMF32 may use the Nudm_SDM_Get service to receive information about specific LADNs or EDNs from UDM35. Furthermore, the information about specific LADNs or EDNs may be UE local configuration information as defined in Non-Patent Document 4. In this case, the information about specific LADNs or EDNs may be transmitted from UE1 to SMF32 via AMF31 using a NAS message (or NAS SM message).

[0059] SMF32 may distinguish a particular PDU Session based on a request from AF5 via NEF36. Specifically, if SMF32 has previously received information from AF5 indicating that it should wait for a response from AF5 before releasing a PDU Session or deactivating the UP connection, SMF32 may send an event notification to AF5 and wait for a response from AF5 before releasing the PDU Session or deactivating the UP connection.

[0060] Figure 4 is a flowchart illustrating an example of the operation of SMF32 according to this embodiment. In step 401, SMF32 receives a first event notification from AMF31 indicating that UE1 is outside the EDN service area or the LADN service area. In step 402, after receiving the first event notification, SMF32 detects an event related to the Application Context Relocation (ACR) procedure. In step 403, in response to detecting the event related to the ACR procedure, SMF32 initiates a procedure to release the PDU Session for the LADN associated with the LADN service area associated with the EDN service area, a procedure to release the PDU Session for (or associated with) the EDN, or a procedure to deactivate the UP connection for the PDU Session. In other words, after receiving the first event notification indicating that UE1 is outside the EDN service area or the LADN service area, SMF32 waits for an event related to the ACR procedure to occur before releasing the PDU Session for the EDN or the LADN or deactivating the UP connection. As already explained, SMF32 may perform the operation shown in Figure 4 only with respect to specific EDNs, specific LADNs, specific PDU Sessions, or specific UEs.

[0061] Events related to the ACR procedure may include sending a second event notification from SMF32 to AF5 directly or via NEF36, followed by receiving a response from AF5 directly or via NEF36. If SMF32 has previously received information from AF5 indicating that it will wait for a response from AF5 before initiating the release of the PDU session or the deactivation of the UP connection, SMF32 may send a second event notification to AF5 and wait for a response from AF5 before releasing the PDU session or deactivating the UP connection. For example, the information indicating that it will wait for a response from AF5 before initiating the release of the PDU session or the deactivation of the UP connection may be an indication such as "AF acknowledgement to be expected".

[0062] For example, if SMF32 has previously received an AF request from AF5, either directly or via NEF36, which is a request to subscribe to a service that provides second event notifications for a PDU Session, and the request includes an indication that "AF acknowledgement to be expected," then SMF32 may send a second event notification to AF5 and wait for a response from AF5 before releasing the PDU Session or deactivating the UP connection. In other words, SMF32 manages the timing of PDU Session release based on runtime coordination between 5GC and EDGEAPP using "AF acknowledgment to be expected." The second event notification may indicate that UE1 is outside the EDN service area or the LADN service area. The second event notification may indicate advance notice of PDU Session release for EDN or LADN, or advance notice of deactivation of the UP connection. The response from AF5 may indicate the completion of the ACR procedure, which includes the transfer of the application context from S-EAS to T-EAS.

[0063] Alternatively, an event relating to the ACR procedure may include the expiration (or elapsed) of a predetermined amount of time to wait for the completion of the ACR procedure. SMF32 may start a timer to count the predetermined amount of time after receiving a first event notification from AMF31 indicating that UE1 is outside the EDN service area or the LADN service area. SMF32 may determine whether it is necessary to start the timer based on the DNN, LADN, or EDN. SMF32 may determine whether it is necessary to start the timer based on the type of DNN, LADN, or EDN. SMF32 may determine whether it is necessary to start the timer based on whether the DNN, LADN, or EDN is associated with the timer. SMF32 may decide to perform a PDU session release procedure or an UP connection deactivation procedure based on the detection of an event relating to the ACR procedure.

[0064] Alternatively, events relating to the ACR procedure may include SMF32 receiving a notification or message relating to the procedure specified in Chapter 4.3.6.2 of Non-Patent Document 4. Specifically, SMF32 may initiate a procedure to release the PDU Session for the EDN or LADN or to deactivate the UP connection for the PDU Session by receiving the Npcf_SMPolicyControl_UpdateNotify service from PCF34. In other words, the Npcf_SMPolicyControl_UpdateNotify service called by PCF34 instructs SMF32 to release the PDU Session for the EDN or LADN or to deactivate the UP connection for the PDU Session. PCF34 may decide to send such instructions based on information provided to PCF34 from AF5 (e.g., S-EES) via NEF36 and UDM35. AF5 (e.g., S-EES) may detect that UE1 is outside the EDN service area or LADN service area using the Location Reporting function specified in Chapter 4.15.3.1 of Non-Patent Document 4. In response to this detection, AF5 (e.g., S-EES) may instruct the 3GPP core network 3 to release the PDU session for the EDN or LADN, or to deactivate the UP connection for the PDU session.

[0065] According to the operation described above, if UE1 moves outside the EDN service area or LADN service area, SMF32 can wait for a grace period to elapse before initiating the release of the PDU Session for that EDN or LADN or the deactivation of the UP connection. This can help prevent ACR procedure failures when UE1 moves between different LADNs or different EDNs. Specifically, after UE1 moves outside the EDN service area or LADN service area, the PDU Session for the old EDN or old LADN is maintained for a while (for example, until an event related to the ACR procedure is detected). For example, SMF32 maintains the PDU Session for the old EDN or old LADN until it can guarantee that the ACR procedure will complete successfully, until it is estimated that the ACR procedure will complete successfully, or until it is confirmed that the ACR procedure has completed successfully. Therefore, UE1 can communicate with the EES (i.e., S-EES) of the old EDN or old LADN via the PDU Session. Therefore, this can increase the likelihood of successfully completing the ACR procedure involving signaling between S-EES and UE1's EEC11.

[0066] In this embodiment, EDN service area management may be performed using network slices. Specifically, an EDN or an EES or EAS within an EDN may be associated with a particular network slice. In other words, UE1 may only be able to access the EDN (or EES or EAS) associated with a particular network slice when UE1 is authorized to use that particular network slice. A particular network slice may be available across the entire PLMN, or it may be available only in a subset of topological areas within the PLMN. A topological area may be one or more TAs (or TAIs). If a particular network slice is available in only one or more TAs, then the registration area of ​​UE1 establishing a PDU Session to access the EAS within that EDN is the same as or a subset of the one or more TAs (or TAIs) assigned to that particular network slice. In this case, the EDN service area is the same as or a subset of the one or more TAs (or TAIs) assigned to that particular network slice. Furthermore, step 401 in Figure 4 is an instruction to release a PDU session or deactivate an UP connection because UE1 has moved outside the topological area (e.g., one or more TAs) to which it was assigned to that particular network slice (or particular S-NSSAI). Specifically, consider the case where UE1 has been notified by the 3GPP core network 3 (i.e., AMF31) of an Allowed NSSAI containing a certain S-NSSAI, and UE1 has one or more PDU sessions associated with that S-NSSAI. In this case, if UE1 moves outside the topological area (or UE1's current registration area) to which it was assigned to that S-NSSAI, in step 401 of Figure 4, AMF31 notifies UE1 of the S-NSSAI as a Rejected S-NSSAI and instructs SMF32 to release the PDU session(s) associated with that S-NSSAI.

[0067] In cases where EDN service area management is performed using network slices, the operation of SMF32 in step 402 of Figure 4 is the same as described above. In step 403 of Figure 4, in response to the detection of events related to the ACR procedure in step 402, SMF32 releases the PDU Session(s) of UE1 associated with the S-NSSAI that became Rejected S-NSSAI.

[0068] These actions allow SMF32 to wait for a grace period to elapse before releasing the PDU Session for the EDN associated with that EDN service area or deactivating the UP connection if UE1 moves outside the EDN service area. This can help prevent ACR procedure failures when UE1 moves between different EDNs. Specifically, after UE1 moves outside the EDN service area, the PDU Session for the old EDN is maintained for a while (for example, until an event related to the ACR procedure is detected). For example, SMF32 maintains the PDU Session for the old EDN until it can guarantee that the ACR procedure will complete successfully, until it is estimated that the ACR procedure will complete successfully, or until it is confirmed that the ACR procedure has completed successfully. This allows UE1 to communicate with the old EDN's EES (i.e., S-EES) via the PDU Session. This thus increases the likelihood that the ACR procedure, involving signaling between the S-EES and UE1's EEC11, can be successfully completed.

[0069] <Second Embodiment> This embodiment provides a detailed example of the operation of SMF32 as described in the first embodiment, and a detailed example of the operation of AMF31, NEF36, and AF5 which are effective for this purpose. The example of the network architecture according to this embodiment is the same as the example described with reference to Figures 1 to 3.

[0070] Figure 5 is a flowchart illustrating an example of the operation of SMF32. Step 501 is similar to step 401 in Figure 4. Specifically, in step 501, SMF32 receives a first event notification from AMF31 indicating that UE1 is outside the EDN service area or the LADN service area. Steps 502 and 503 provide an example of step 402 in Figure 4. In step 502, SMF32 sends a second event notification to AF5 (e.g., S-EES) directly or via NEF36. In step 503, SMF32 detects that it has received a response to the second event notification from AF5 directly or via NEF36. In step 504, after detecting that it has received a response to the second event notification, SMF32 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.

[0071] Figure 6 is a flowchart illustrating an example of the operation of AF5 (e.g., S-EES). In step 601, AF5 receives a second event notification directly from SMF32 or via NEF36. In step 602, after the ACR procedure from S-EAS to T-EAS is completed, AF5 sends a response to the second event notification directly to SMF32 or via NEF36. This response may trigger SMF32 to release the PDU Session for EDN or LADN or to deactivate the UP connection.

[0072] Figure 7 is a sequence diagram showing an example of the operation of AMF31, SMF32, NEF36, and AF5. AF5 may include S-EES. In step 701, AMF31 sends an event notification to SMF32 indicating that UE1 is outside the EDN service area or the LADN service area. To receive this event notification, SMF32 may pre-subscribe to AMF31's UE mobility event notifications using the event ID "UE moving in or out of Area of ​​Interest". This allows SMF32 to receive notifications about the event ID.

[0073] In steps 702 and 703, SMF32 sends an event notification to AF5 via NEF36 that explicitly or implicitly indicates that UE1 is outside the EDN service area or the LADN service area. Specifically, in step 702, SMF32, in response to detecting an event (e.g., “Presence-In-AOI-Report”) subscribed to by an NF consumer (i.e., AF5 or NEF36), invokes the Nsmf_EventExposure_Notify service operation to report the event to NEF36 or AF5. In step 703, NEF36 invokes a service operation to report the event to AF5. The service operation invoked by NEF36 may be an improved version 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, AF5 sends a response to SMF32 via NEF36. Specifically, in step 704, AF5 sends a response to the event notification in step 703 (Acknowledgement of AOIEventNotification or Acknowledgement of EventExposure) to NEF36. This response may indicate the completion of the ACR procedure, which includes the transfer of the application context from S-EAS to T-EAS (e.g., “ACR complete”). In step 705, NEF36 sends a response to the event notification in step 702 (Acknowledgement of Event Notification) to SMF32.

[0075] In step 706, after receiving the response from step 705, SMF32 releases the PDU session for the EDN or LADN or deactivates the UP connection. Although not shown, the procedure for releasing the PDU session or deactivating the UP connection includes signaling between SMF32 and UPF33, and signaling between SMF32 and UE1 via AMF31. 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, AF5 may pre-subscribe to the event notification service for that event. Figure 8 shows an example of the procedure for subscribing to the event notification service by SMF32. In step 801, AF5 sends an AF request to NEF36 to subscribe to the event notification service for a specific PDU Session. The AF request includes the indication "AF acknowledgement to be expected". AF5 may also call the Nnef_EventExposure_Subscribe operation using the event ID "Presence In AOI Report". NEF36 provides a UE mobility out of an Area of ​​Interest function as Monitoring Events, allowing AF5 to detect UE movement. This allows AF5 to detect UE1 movement events via NEF36 (Nnef_EventExposure_Subscribe).

[0077] In step 802, NEF36 requests to subscribe to SMF32's event notification service based on the AF request in step 801. The request includes the indication "AF acknowledgement to be expected". In step 802, NEF36 may also call the Nsmf_EventExposure_Subscribe operation using Event ID "Presence In AOI Report". Based on the fact that the received request includes the indication "AF acknowledgement to be expected", SMF32 recognizes that it needs to send an event notification to AF5 and wait for a response from AF5 before releasing the PDU Session or deactivating the UP connection. SMF32 also provides a UE mobility out of an Area of ​​Interest function so that NEF36, or AF5 via NEF36, can detect the movement of UEs. This allows NEF36, or AF5 via NEF36, to receive notifications of UE1 movement events (Nsmf_EventExposure_Notify) from SMF32.

[0078] According to the example described in this embodiment, if UE1 moves outside the EDN service area or the LADN service area, SMF32 sends an event notification to AF5 and waits for a response from AF5 before initiating the release of the PDU session or deactivation of the UP connection for the EDN or LADN. This can help prevent ACR procedure failures when UE1 moves between different EDNs corresponding to different LADNs.

[0079] <Third Embodiment> This embodiment provides a detailed example of the operation of SMF32 as described in the first embodiment, and a detailed example of the operation of AMF31, NEF36, and AF5 which are effective for this purpose. The example of the network architecture according to this embodiment is the same as the example described with reference to Figures 1 to 3.

[0080] Figure 9 is a flowchart illustrating an example of the operation of SMF32. Step 901 is similar to step 401 in Figure 4. Specifically, in step 901, SMF32 receives a first event notification from AMF31 indicating that UE1 is outside the EDN service area or the LADN service area. In step 902, SMF32 detects the expiration of a predetermined time to wait for the ACR procedure to complete. SMF32 may start a timer to count the predetermined time after receiving the first event notification. In step 903, after the expiration of the predetermined time, SMF32 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. As described in the first embodiment, SMF32 may determine whether or not to start the timer based on whether the EDN or LADN associated with the first event notification is a specific EDN or LADN.

[0081] Similar to the first embodiment, this embodiment may also perform EDN service area management using network slices. Specifically, an EDN or an EES or EAS within an EDN may be associated with a particular network slice. In other words, UE1 may only be able to access the EDN (or EES or EAS) associated with a particular network slice when UE1 is authorized to use that particular network slice. If a particular network slice is available to only one or more TAs, then the registration area of ​​UE1 establishing a PDU Session to access the EAS within that EDN is the same as or a subset of the one or more TAs (or TAIs) assigned to that particular network slice. In this case, the EDN service area is the same as or a subset of the one or more TAs (or TAIs) assigned to that particular network slice. Step 901 in Figure 9 is an instruction to release the PDU Session or deactivate the UP connection because UE1 has moved outside the topological area (e.g., one or more TAs) assigned to that particular network slice (or particular S-NSSAI). Specifically, consider the case where UE1 is notified by the 3GPP core network 3 (i.e., AMF31) of an Allowed NSSAI containing a certain S-NSSAI, and UE1 has one or more PDU Sessions associated with that S-NSSAI. In this case, if UE1 moves outside the topological area (or UE1's current registration area) to which the S-NSSAI is assigned, in step 901 of Figure 9, AMF31 notifies UE1 of the S-NSSAI as a Rejected S-NSSAI and instructs SMF32 to release the PDU Session(s) associated with the S-NSSAI.

[0082] In cases where EDN service area management is performed using network slices, the operation of SMF32 in step 902 of Figure 9 is the same as described above. In step 903 of Figure 9, in response to the detection of events related to the ACR procedure in step 902, SMF32 releases the PDU Session(s) of UE1 associated with the S-NSSAI that became Rejected S-NSSAI.

[0083] Figure 10 is a sequence diagram showing an example of the operation of AMF31, SMF32, NEF36, and AF5. AF5 may include S-EES. In step 1001, AMF31 sends an event notification to SMF32 indicating that UE1 is outside the EDN service area or the LADN service area. To receive this event notification, SMF32 may pre-subscribe to AMF31's UE mobility event notifications using the event ID "UE moving in or out of Area of ​​Interest". This allows SMF32 to receive notifications regarding that event ID.

[0084] In cases where EDN service area management is performed using network slices, AMF31 may send the event notification in step 1001, i.e., an instruction to release the PDU Session(s) associated with the S-NSSAI, when UE1 moves outside the topological area (or the current registration area of ​​UE1) assigned to the S-NSSAI associated with the EDN (or EES or EAS). Specifically, AMF31 may notify SMF32 of the release of the PDU Session(s) associated with the S-NSSAI by calling the Nsmf_PDUSession_ReleaseSMContext service operation.

[0085] In step 1002, SMF32 starts a timer. The value set for the timer may be determined based on the local policy. The timer value may also be determined based on the subscriber information of UE1. In the PDU Session establishment procedure, UE1 may indicate the timer value. Alternatively, AF5 may indicate the timer value. In the procedure for subscribing to the event notification service by SMF32, AF5 may indicate the timer value to SMF32 via NEF36. This procedure may be the same as in Figure 8.

[0086] As an example, and not an limitation, in steps 1003 and 1004, SMF32 may send an event notification to AF5 via NEF36 that explicitly or implicitly indicates that UE1 is outside the EDN service area or the LADN service area. Steps 1003 and 1004 may be the same as steps 702 and 703 in Figure 7.

[0087] In step 1005, the SMF32 detects the expiration of the timer. In step 1006, after the timer has expired, the SMF32 releases the PDU session for the EDN or 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 SMF32 and the UPF33, and signaling between the SMF32 and the UE1 via the AMF31. 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.

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

[0089] <Fourth Embodiment> This embodiment provides a detailed example of the operation of the SMF32 described in the first embodiment, and a detailed example of the operation of the AMF31 that is effective for this purpose. The example of the network architecture according to this embodiment is the same as the example described with reference to Figures 1 to 3.

[0090] Figure 11 is a flowchart illustrating an example of SMF32 operation. Step 1101 is similar to step 401 in Figure 4. Specifically, in step 1101, SMF32 receives a first event notification from AMF31 indicating that UE1 is outside the EDN service area or LADN service area. In step 1102, SMF32 determines whether the EDN or LADN is of a particular type. A particular type of EDN or LADN may be an EDN or LADN that corresponds to (or supports) a mode for continuity of session and service. The type of LADN may be identified based on the LADN DNN. The type of 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. Furthermore, or alternatively, SMF32 determines whether the LADN or 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 LADN is of a specific type or is associated with a timer, SMF32 recognizes that the timer must be started before releasing the PDU Session or deactivating the UP connection for the EDN or LADN. SMF32 then starts the timer. The value set for the timer may be determined based on the local policy. The timer value may be determined based on the subscriber information of UE1. In the PDU Session establishment procedure, UE1 may indicate the timer value.

[0091] In step 1103, the SMF32 detects the expiration of the timer. In step 1104, after the timer has expired, the SMF32 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 determination by SMF32 in step 1102, a new DNN information element may be defined, such as “continuity of session and service capable LADN DNN” or “continuity of session and service capable EDN DNN”. In step 1102, SMF32 may determine whether the EDN or LADN is associated with this new DNN information element.

[0093] In the embodiments described in this specification, the definitions of the terms “continuity of session and service” and “mode for continuity of session and service” differ from those of “SSC” and “SSC mode” in the current 3GPP specification described in Non-Patent Documents 1 and 2, etc. Specifically, in the current 3GPP specification, “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 of this specification, “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 when UE1 moves outside the LADN service area corresponding to the first DNN, before releasing the old PDU session with the first DNN. The system includes establishing a service. For example, “continuity of session and service” and “mode for continuity of session and service” include establishing a new PDU session service for the second DNN to which the application context will be transferred from the first DNN, before releasing the old PDU session with the first DNN, when UE1 moves outside the LADN service area corresponding to the first DNN.

[0094] Figure 12 is a sequence diagram showing an example of the operation of AMF31 and SMF32. In step 1201, AMF31 sends an event notification to SMF32 indicating that UE1 is outside the EDN service area or the LADN service area. To receive this event notification, SMF32 may pre-subscribe to AMF31's UE mobility event notifications using the event ID "UE moving in or out of Area of ​​Interest". This allows SMF32 to receive notifications related to that event ID.

[0095] In cases where EDN service area management is performed using network slices, AMF31 may send the event notification in step 1201, i.e., an instruction to release the PDU Session(s) associated with the S-NSSAI, when UE1 moves outside the topological area (or the current registration area of ​​UE1) assigned to the S-NSSAI associated with the EDN (or EES or EAS). Specifically, AMF31 may notify SMF32 of the release of the PDU Session(s) associated with the S-NSSAI by calling the Nsmf_PDUSession_ReleaseSMContext service operation.

[0096] In step 1202, SMF32 determines whether the EDN or LADN is of a specific type. As described above, a specific type of EDN or LADN is, but is not limited to, an EDN or LADN that corresponds to (or supports) a mode for continuity of session and service. SMF32 may also determine whether the LADN is associated with a specific DNN information element, for example, the "continuity of session and service capable" information element. Alternatively, SMF32 may determine whether the EDN is associated with a specific DNN information element, for example, the "continuity of session and service capable EDN DNN" information element. If the EDN or LADN is of a specific type, SMF32 recognizes that it needs to start a timer before releasing the PDU Session or deactivating the UP connection for the EDN or LADN. SMF32 then starts the timer.

[0097] In step 1203, the SMF32 detects the expiration of the timer. In step 1204, after the timer has expired, the SMF32 releases the PDU Session for the EDN or 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 SMF32 and the UPF33, and signaling between the SMF32 and the UE1 via the AMF31. 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.

[0098] According to the example described in this embodiment, if UE1 moves outside the EDN service area or the LADN service area, SMF32 waits for a predetermined time to expire for the ACR procedure to complete before initiating the release of the PDU session for the EDN or LADN or the deactivation of the UP connection. This 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 actions shown in Figure 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 previously described, in the terminology of this specification, a mode for continuity of session and service comprises 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 outside the LADN service area corresponding to the first DNN. In one example, the second DNN is the DNN to which the application context is transferred from the first DNN. The mode for continuity of session and service selection policy may be configured in UE1 as part of the UE Route Selection Policy (URSP). The policy may be pre-configured in UE1. The policy may be supplied from PCF34 to UE1 via AMF31 during the registration procedure.

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

[0101] According to this behavior of UE1, if UE1 moves outside the LADN service area corresponding to the first DNN, it can establish a new PDU session service for a second DNN that is different from the first DNN before releasing the old PDU session with the first DNN. This can help prevent ACR procedure failures when UE1 moves between different EDNs that correspond to different LADNs.

[0102] <Fifth Embodiment> An example of the network architecture according to this embodiment is the same as the example described with reference to Figures 1 to 3.

[0103] In this embodiment, UE1 provides EEC functionality. The EEC11 of UE1 decides to execute one of several ACR procedures, taking into account that UE1 has moved outside the LADN service area associated with the first EDN. Figure 14 shows an example of the operation of UE1. In step 1401, EEC11 detects that the UE has moved outside the LADN service area associated with the EDN. In step 1402, EEC11 decides to execute one of several ACR procedures, taking into account that UE1 has moved outside the LADN service area of ​​the first EDN.

[0104] In one example, when UE1 moves outside the LADN service area associated with the first EDN, EEC11 selects and executes one of the ACR procedures that does not involve message exchange between EEC11 and the S-EES within the first EDN. This ACR procedure may be the ACR procedure via T-EES (EEC executed ACR via T-EES) described in Chapter 8.8.2.6 of Non-Patent Literature 3. In other words, when UE1 moves outside the LADN 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. These actions may, in one example, occur when UE1 moves outside the LADN service area associated with the first EDN, and the PDU Session for the first EDN is not subject to a mode for session and service continuity.

[0105] The NAS layer of UE1 may send a notification to the EEC11 of UE1 in response to detecting that UE1 is outside the LADN service area associated with the first EDN. This notification may indicate the mode for session and service continuity applicable to the PDU session for the first EDN. Furthermore, the notification may indicate the Tracking Area Identity (TAI) corresponding to the location of UE1 outside the LADN 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 EEC11 may select a T-EES based on the TAI included in the notification. The selection of a T-EES based on the TAI may be based on information already provisioned to UE1. This information may be pre-configured in UE1. Alternatively, this information may be supplied to the EEC1 from the ECS6 during the 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 the maintenance of the PDU Session for the first EDN (LADN) is not guaranteed, the EEC11 of UE1 selects and executes one of the ACR procedures that does not involve message exchange between the EEC11 and the S-EES within the first EDN. This can help prevent ACR procedure failures when UE1 moves between different EDNs corresponding to different LADNs.

[0107] Next, configuration examples of UE1, AF5, AMF31, SMF32, and NEF36 according to the above-described multiple embodiments will be explained. Figure 15 is a block diagram showing a configuration example of UE1. The Radio Frequency (RF) transceiver 1501 performs analog RF signal processing to communicate with the 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 with the antenna array 1502 and the 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 supplies the transmit RF signal to the antenna array 1502. The RF transceiver 1501 also generates a baseband receive signal based on the received RF signal received by the antenna array 1502 and supplies this to the baseband processor 1503. The RF transceiver 1501 may include an analog beamformer circuit for beamforming. The analog beamformer circuit 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 communication. Digital baseband signal processing includes (a) data compression / decompression, (b) data segmentation / concatenation, (c) generation / decomposition of transmission format (transmission frame), (d) transmission path coding / decoding, (e) modulation (symbol mapping) / demodulation, and (f) generation of OFDM symbol data (baseband OFDM signal) by Inverse Fast Fourier Transform (IFFT). Control plane processing, on the other hand, includes communication management at 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 attach, mobility, and call management).

[0109] For example, the digital baseband signal processing by the baseband processor 1503 may include signal processing for the Service Data Adaptation Protocol (SDAP) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, Medium Access Control (MAC) layer, and Physical (PHY) layer. Furthermore, the control plane processing by the baseband processor 1503 may include processing for the Non-Access Stratum (NAS) protocol, 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., Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., Central Processing Unit (CPU) or 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 described later.

[0112] The application processor 1504 is also called a CPU, MPU, microprocessor, or processor core. The application processor 1504 may include multiple processors (multiple processor cores). The application processor 1504 implements various functions of the UE1 by executing system software programs (Operating System (OS)) and various application programs (e.g., calling applications, web browsers, mail clients, camera operation applications, music playback applications) read from memory 1506 or memory not shown.

[0113] In some implementations, the baseband processor 1503 and the application processor 1504 may be integrated on a single chip, as shown 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] Memory 1506 is volatile memory, non-volatile memory, or a combination thereof. Memory 1506 may include multiple physically independent memory devices. Volatile memory is, for example, Static Random Access Memory (SRAM) or Dynamic RAM (DRAM), or a combination thereof. Non-volatile memory is Mask Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or hard disk drive, or any combination thereof. For example, memory 1506 may include an external memory device accessible from the baseband processor 1503, the application processor 1504, and the SoC 1505. Memory 1506 may also include an internal memory device integrated within the baseband processor 1503, the application processor 1504, or the SoC 1505. Furthermore, 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 containing instruction sets and data for performing the processing by the UE1 as described in the above embodiments. In some implementations, the baseband processor 1503 or application processor 1504 may be configured to read and execute the software modules 1507 from the memory 1506 to perform the processing of the UE1 as described with reference to the drawings in the above embodiments.

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

[0117] Figure 16 shows an example configuration of a device providing the functionality of AF5. Other devices providing network functions, such as AMF31, SMF32, and NEF36, may have a similar configuration to that shown in Figure 16. Referring to Figure 16, AF5 (or AMF31, or SMF32, or NEF36) includes a network interface 1601, a processor 1602, and 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) compliant with the IEEE 802.3 series.

[0118] The processor 1602 may be, for example, a microprocessor, a Micro Processing Unit (MPU), or a Central Processing Unit (CPU). The processor 1602 may include multiple processors.

[0119] Memory 1603 is composed of volatile memory and non-volatile memory. Memory 1603 may include multiple physically independent memory devices. Volatile memory is, for example, Static Random Access Memory (SRAM) or Dynamic RAM (DRAM), or a combination thereof. Non-volatile memory is Mask Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or hard disk drive, or any combination thereof. Memory 1603 may include storage located away from the processor 1602. In this case, the processor 1602 may access memory 1603 via a network interface 1601 or an I / O interface not shown.

[0120] Memory 1603 may store one or more software modules (computer programs) 1604 containing instruction sets and data for processing by AF5 (or AMF31, or SMF32, or NEF36) as described in the above embodiments. In some implementations, the processor 1602 may be configured to read the software module 1604 from memory 1603 and execute it to perform the processing of AF5 (or AMF31, or SMF32, or NEF36) as described in the above embodiments.

[0121] As explained with reference to Figures 15 and 16, each of the processors in the above-described embodiment of UE1, AF5, AMF31, SMF32, and NEF36 executes one or more programs that include a set of instructions for causing the computer to perform the algorithm described with reference to the drawings.

[0122] The program, when loaded into a computer, includes a set of instructions (or software code) for causing the computer to perform one or more of the functions described in the embodiments. The program may be stored on a non-temporary computer-readable medium or a physical storage medium. Examples, but not limited to, 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 disc storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices. The program may be transmitted over a temporary computer-readable medium or a communication medium. Examples, but not limited to, include temporary computer-readable medium or a communication medium that includes electrical, optical, acoustic or other forms of propagating signals.

[0123] The embodiments described above are merely examples of how the technical concept obtained by the present inventor can be applied. In other words, the technical concept is not limited to the embodiments described above, and various modifications are certainly possible.

[0124] For example, some or all of the above embodiments may also be described as follows, but are not limited to the following.

[0125] (Note 1) A Session Management Function (SMF) node, Memory and At least one processor coupled to the memory, Equipped with, The aforementioned at least one processor is After receiving a first event notification from the Access and Mobility Management Function (AMF) node indicating that User Equipment (UE) is outside the Edge Data Network (EDN) service area or the Local Area Data Network (LADN) service area, an event related to the Application Context Relocation (ACR) procedure is detected. In response to detecting an event related to the ACR procedure, initiate a procedure to release a Protocol Data Unit (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 User Plane (UP) connection for the PDU Session. Structured in such a way SMF node. (Note 2) The events relating to the ACR procedure include 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. The SMF node described in Appendix 1. (Note 3) The aforementioned response indicates the completion of the ACR procedure, which includes the transfer of the application context from the Source Edge Application Server (S-EAS) to the Target EAS (T-EAS). The SMF node described in Appendix 2. (Note 4) The events relating to the ACR procedure include, after sending a second event notification from the SMF node to the Application Function (AF) node directly or via the Network Exposure Function (NEF) node, receiving a message from the Policy Control Function (PCF) node instructing the initiation of 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, The aforementioned message is transmitted based on information provided from the AF node to the PCF node via the NEF node and the Unified Data Management (UDM) node. The SMF node described in Appendix 1. (Note 5) The second event notification includes a notification of information indicating that the UE is outside the EDN service area or the LADN service area. An SMF node as described in any one of the items in Appendix 2 to 4. (Note 6) The second event notification includes advance notification of the release of the PDU Session for the EDN, advance notification of the release of the PDU Session for the LADN, or advance notification of the deactivation of the UP connection. An SMF node as described in any one of the items in Appendix 2 to 4. (Note 7) The aforementioned at least one processor is A request is received from the AF node or the NEF node to subscribe to the second event notification service for the PDU Session, The ACR procedure is detected after receiving the first event notification, provided that the request includes an indication that it is waiting for a response from the AF node before initiating the procedure for releasing a PDU Session for an LADN associated with the LADN service area, the procedure for releasing a PDU Session for an EDN associated with the EDN service area, or the procedure for deactivating an UP connection for the PDU Session, Structured in such a way An SMF node as described in any one of the items 2 to 6 of the appendix. (Note 8) The events relating to the ACR procedure include the expiration of the time to wait for the completion of the ACR procedure. An SMF node as described in any one of the appendices 1 to 7. (Note 9) The at least one processor is configured to start a timer to count down the time to wait for the ACR procedure to complete after receiving the first event notification. The SMF node described in Appendix 8. (Note 10) The at least one processor is configured to determine, based on the Data Network Name (DNN) of the LADN or EDN, whether the timer needs to be started before the PDU Session release procedure or the UP connection deactivation procedure. The SMF node described in Appendix 9. (Note 11) The at least one processor is configured to determine, based on the type of the LADN or EDN, whether the timer needs to be started before the PDU Session release procedure or the UP connection deactivation procedure. The SMF node described in Appendix 9. (Note 12) The at least one processor is configured to determine, based on the LADN or whether the LADN is associated with the timer, whether the timer needs to be started before the PDU Session release procedure or the UP connection deactivation procedure. The SMF node described in Appendix 9. (Note 13) The aforementioned LADN service area or EDN service area is a set of one or more Tracking Areas (TAs). An SMF node as described in any one of the appendices 1 to 12. (Note 14) A method performed by a Session Management Function (SMF) node, After receiving a first event notification from an Access and Mobility management Function (AMF) node indicating that User Equipment (UE) is outside the Edge Data Network (EDN) service area or the Local Area Data Network (LADN) service area, the system detects events related to the Application Context Relocation (ACR) procedure. In response to detecting an event related to the ACR procedure, initiate a procedure to release a Protocol Data Unit (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 User Plane (UP) connection for the PDU session. A method for providing this. (Note 15) A program that causes a computer to perform a method for a Session Management Function (SMF) node, wherein the method is: After receiving a first event notification from an Access and Mobility management Function (AMF) node indicating that User Equipment (UE) is outside the Edge Data Network (EDN) service area or the Local Area Data Network (LADN) service area, the system detects events related to the Application Context Relocation (ACR) procedure. In response to detecting an event related to the ACR procedure, initiate a procedure to release a Protocol Data Unit (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 User Plane (UP) connection for the PDU session. A program that includes the following features. (Note 16) An Application Function (AF) node, Memory and At least one processor coupled to the memory, Equipped with, The aforementioned at least one processor is Event notifications are received directly from Session Management Function (SMF) nodes or via Network Exposure Function (NEF) nodes. After the Application Context Relocation (ACR) procedure, which includes the transfer of the application context from the Source Edge Application Server (S-EAS) to the Target EAS (T-EAS), is completed, a response to the event notification is sent directly to the SMF node or via the NEF node. It is structured in such a way, The response is a message that instructs the SMF node to initiate a procedure to release a PDU session for the Local Area Data Network (LADN), a PDU session for the Edge Data Network (EDN), or a procedure to deactivate the User Plane (UP) connection for the said PDU session. AF node. (Note 17) The event notification indicates that User Equipment (UE) is outside the service area of ​​the EDN or the LADN, indicates advance notice of the release of the PDU Session for the LADN, indicates advance notice of the release of the PDU Session for the EDN, or indicates advance notice of the deactivation of the UP connection for the PDU Session. The AF node described in Appendix 16. (Note 18) A method performed by an Application Function (AF) node, Receiving event notifications directly from Session Management Function (SMF) nodes or via Network Exposure Function (NEF) nodes. After the Application Context Relocation (ACR) procedure, which includes the transfer of the application context from the Source Edge Application Server (S-EAS) to the Target EAS (T-EAS), is completed, a response to the event notification is sent directly to the SMF node or via the NEF node. Equipped with, The response is a message that instructs the SMF node to initiate a procedure to release a PDU session for the Local Area Data Network (LADN), a PDU session for the Edge Data Network (EDN), or a procedure to deactivate the User Plane (UP) connection for the said PDU session. method. (Note 19) A program for causing a computer to perform a method for an Application Function (AF) node, wherein the method is: Receiving event notifications directly from Session Management Function (SMF) nodes or via Network Exposure Function (NEF) nodes. After the Application Context Relocation (ACR) procedure, which includes the transfer of the application context from the Source Edge Application Server (S-EAS) to the Target EAS (T-EAS), is completed, a response to the event notification is sent directly to the SMF node or via the NEF node. Equipped with, The response is a message that instructs the SMF node to initiate a procedure to release a PDU session for the Local Area Data Network (LADN), a PDU session for the Edge Data Network (EDN), or a procedure to deactivate the User Plane (UP) connection for the said PDU session. program. (Note 20) User Equipment (UE), Memory and At least one processor coupled to the memory, Equipped with, The aforementioned at least one processor is If the first Data Network Name (DNN) corresponds to a specified type of Local Area Data Network (LADN), select a mode for continuity of session and service. To request the establishment of a first Protocol Data Unit (PDU) Session for the first DNN, a Non-Access Stratum (NAS) message containing a PDU Session Establishment Request indicating the selected mode is sent to the Access and Mobility Management Function (AMF) node. It is structured in such a way, The aforementioned mode for continuity of a single session and service comprises establishing a second PDU session for a second DNN to which the application context is transferred from the first DNN before releasing the first PDU session when the UE moves outside the LADN service area corresponding to the first DNN. UE. (Note 21) A method performed by User Equipment (UE), If the first Data Network Name (DNN) corresponds to a specified type of Local Area Data Network (LADN), select a mode for continuity of session and service. To request the establishment of a first Protocol Data Unit (PDU) Session for the first DNN, send a Non-Access Stratum (NAS) message containing a PDU Session Establishment Request indicating the selected mode to an Access and Mobility Management Function (AMF) node. Equipped with, The aforementioned mode for continuity of a single session and service comprises establishing a second PDU session for a second DNN to which the application context is transferred from the first DNN before releasing the first PDU session when the UE moves outside the LADN service area corresponding to the first DNN. method. (Note 22) A program for causing a computer to perform a method for User Equipment (UE), wherein the method is If the first Data Network Name (DNN) corresponds to a specified type of Local Area Data Network (LADN), select a mode for continuity of session and service. To request the establishment of a first Protocol Data Unit (PDU) Session for the first DNN, send a Non-Access Stratum (NAS) message containing a PDU Session Establishment Request indicating the selected mode to an Access and Mobility Management Function (AMF) node. Equipped with, The aforementioned mode for continuity of a single session and service comprises establishing a second PDU session for a second DNN to which the application context is transferred from the first DNN before releasing the first PDU session when the UE moves outside the LADN service area corresponding to the first DNN. program. (Note 23) User Equipment (UE), Memory and At least one processor coupled to the memory, Equipped with, The aforementioned at least one processor is configured to provide Edge Enabler Client (EEC) functionality, The EEC function includes determining to perform one of several Application Context Relocation (ACR) procedures, taking into account that the UE has moved outside the Local Area Data Network (LADN) service area associated with the first Edge Data Network (EDN). UE. (Note 24) The EEC function includes, when the UE moves outside the LADN service area of ​​the first EDN, selecting and executing one of the ACR procedures that does not involve message exchange between the EEC and the Source Edge Enabler Server (S-EES) within the first EDN. UE as described in Appendix 23. (Note 25) The EEC function includes selecting and executing an ACR procedure via a Target EES (T-EES) belonging to a second EDN different from the first EDN when the UE moves outside the LADN service area associated with the first EDN. UE as described in Appendix 23. (Note 26) The EEC function includes determining to perform one of several ACR procedures if the Protocol Data Unit (PDU) Session for the first EDN is not subject to a mode for continuity of session and service. The UE described in any one of the appendices 23-25. (Note 27) The aforementioned at least one processor is configured to provide Non-Access Stratum (NAS) layer functionality, The NAS layer function includes sending a notification to the EEC function in response to detecting that the UE is outside the LADN service area associated with the first EDN. The aforementioned notification indicates a mode for continuity of session and service applicable to a Protocol Data Unit (PDU) Session for the first EDN. The UE described in any one of the appendices 23-26. (Note 28) The aforementioned notification indicates the Tracking Area Identity (TAI) corresponding to the location of the UE outside the LADN service area. UE as described in Appendix 27. (Note 29) The aforementioned EEC function includes selecting a Target EES (T-EES) based on the TAI included in the notification. UE as described in Appendix 28. (Note 30) A method performed by User Equipment (UE), It is equipped to provide Edge Enabler Client (EEC) functionality, The EEC function includes determining to perform one of several Application Context Relocation (ACR) procedures, taking into account that the UE has moved outside the Local Area Data Network (LADN) service area associated with the first Edge Data Network (EDN). method. (Note 31) A program for causing a computer to perform methods for User Equipment (UE), The method described above includes providing Edge Enabler Client (EEC) functionality. The EEC function includes determining to perform one of several Application Context Relocation (ACR) procedures, taking into account that the UE has moved outside the Local Area Data Network (LADN) service area associated with the first Edge Data Network (EDN). program.

[0126] This application claims priority based on Japanese Patent Application No. 2021-084223, filed on 18 May 2021, and incorporates all of its disclosures herein. [Explanation of symbols]

[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, Memory and At least one processor coupled to the memory, Equipped with, The aforementioned at least one processor is A PDU session is established between User Equipment (UE) and Protocol Data Unit (PDU) Session Anchor (PSA). A first message including a first timer is received from an Application Function (AF) via a Network Exposure Function (NEF) node, and the first timer indicates the period for which a first PSA corresponding to the PDU session is maintained. If the movement of the UE results in a change to the first PSA, the first PSA corresponding to the PDU session is maintained based on the first timer. SMF node.

2. A method performed by a Session Management Function (SMF) node, A PDU session is established between User Equipment (UE) and Protocol Data Unit (PDU) Session Anchor (PSA). A first message including a first timer is received from an Application Function (AF) via a Network Exposure Function (NEF) node, and the first timer indicates the period for which a first PSA corresponding to the PDU session is maintained. If the movement of the UE results in a change to the first PSA, the first PSA corresponding to the PDU session is maintained based on the first timer. method.

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