System, method, and information processing apparatus

Abstract

To suppress deterioration in radio communication quality due to movement of a user terminal.SOLUTION: The system includes a plurality of network functions (NFs). Acquiring, by each NF, based on first information including information about one or more cells in which a UE (UserEquipment) is predicted to be located according to movement of the UE, second information used for providing radio communication to the UE when the UE moves from or to a first cell that is a serving cell among the one or more cells included in the first information, before the UE moves from or to the first cell; And when the UE moves from or to the first cell, performing a first process related to provision of radio communication to the UE by using the second information without performing a process related to acquisition of the second information.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to communication network systems. [Background technology]

[0002] It is disclosed that the predicted communication quality for the predicted movement route of a mobile terminal is obtained based on a predicted communication quality distribution in a communication area, and the timing for starting communication for the mobile terminal is determined based on the predicted communication quality (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-197622 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to provide a system, a method, and an information processing device that can suppress deterioration of wireless communication quality due to movement of a user terminal. [Means for solving the problem]

[0005] One aspect of the present disclosure is Based on first information including information about one or more cells in which a UE (User Equipment) is predicted to be present as the UE moves, second information to be used in providing wireless communication to the UE when the UE moves from or to a first cell that is a serving cell among the one or more cells is acquired before the UE moves from or to the first cell; When the UE moves from or to the first cell, performing a first process related to providing wireless communication to the UE using the second information without performing a process related to acquiring the second information; Multiple NFs (Network Functions) that execute the above, The system is provided with:

[0006] Another aspect of the present disclosure is NF, acquiring, based on first information including information about one or more cells in which the UE is predicted to be present as the UE moves, second information to be used in providing wireless communication to the UE when the UE moves from or to a first cell that is a serving cell among the one or more cells, before the UE moves from or to the first cell; When the UE moves from or to the first cell, performing a first process related to providing wireless communication to the UE using the second information without performing a process related to acquiring the second information; The method includes:

[0007] One aspect of the present disclosure is Based on first information including information about one or more cells where the UE is predicted to be present as the UE moves, second information used to provide wireless communication to the UE when the UE moves from or to a first cell that is a serving cell among the one or more cells is generated before the UE moves from or to the first cell. , and obtaining When the UE moves from or to the first cell, performing a first process related to providing wireless communication to the UE using the second information without performing a process related to acquiring the second information; A control unit that executes It is an information processing device. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to suppress deterioration of wireless communication quality due to movement of a user terminal. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an example of the architecture of a fifth-generation mobile communication system. [Figure 2] FIG. 2 is a diagram illustrating processing in the communication system according to the first embodiment. [Figure 3] FIG. 3 shows handover scenario #1. [Figure 4] FIG. 4 illustrates handover scenario #2. [Figure 5] FIG. 5 illustrates handover scenario #3. [Figure 6] FIG. 6 illustrates handover scenario #4. [Figure 7] FIG. 7 is a diagram illustrating an example of the hardware configuration of an information processing device capable of operating as each NF and AF in the 5GC. [Figure 8] FIG. 8 is a diagram illustrating an example of the functional configuration of the AF. [Figure 9] FIG. 9 is a diagram illustrating an example of the functional configuration of the NEF. [Figure 10] FIG. 10 is a diagram illustrating an example of the functional configuration of the AMF. [Figure 11] FIG. 11 is a diagram illustrating an example of the functional configuration of an SMF. [Figure 12] FIG. 12 is an example of a flowchart of a process related to an AF pre-setting request. [Figure 13] FIG. 13 is an example of a flowchart of a process related to presetting of the NEF. [Figure 14] Figure 14 is an example of a flowchart of processing when an AMF handover pre-configuration request is received. [Figure 15] Figure 15 is an example of a flowchart of an AMF intra-region handover pre-configuration process. [Figure 16] Figure 16 is an example of a flowchart of AMF out-of-region handover pre-configuration processing. [Figure 17]Figure 17 is an example of a flowchart of a PDU session pre-configuration process when an AMF PDU session pre-configuration request is received. [Figure 18] FIG. 18 is an example of a flowchart of processing when a pre-configuration request is received in SMF. [Figure 19] Figure 19 is an example of a flowchart of a handover process or PDU session establishment process by an NF. [Figure 20] FIG. 20 shows an example of a processing sequence from when route information is transmitted from the UE to when a pre-configuration request is transmitted to the current AMF. [Figure 21] FIG. 21 is a diagram showing an example of a handover pre-setting sequence in scenario #1. [Figure 22] Figure 22 shows the PDU session pre-establishment sequence in scenario #1. [Figure 23] FIG. 23 is a diagram showing an example of a handover sequence in scenario #1. [Figure 24] FIG. 24 shows an example of a sequence for establishing a PDU session for an application that is the target of pre-configuration in scenario #1. [Figure 25] FIG. 25 is a diagram showing an example of a handover pre-setting sequence in scenario #2. [Figure 26] FIG. 26 is a diagram showing an example of a handover sequence in scenario #2. [Figure 27] FIG. 27 is a diagram showing an example of a handover pre-setting sequence in scenario #3. [Figure 28] FIG. 28 is a diagram showing an example of a handover sequence in scenario #3. [Figure 29] FIG. 29 is a diagram showing an example of a handover pre-setting sequence in scenario #4. [Figure 30] FIG. 30 is a diagram showing an example of a handover sequence in scenario #4. [Figure 31]FIG. 31 is a diagram illustrating processing in the communication system according to the second embodiment. [Figure 32] FIG. 32 is an example of a flowchart of the AF process in the second embodiment. [Figure 33] FIG. 33 is an example of a flowchart of processing related to presetting of the NEF according to the second embodiment. [Figure 34] FIG. 34 shows an example of a processing sequence from when a pre-setting request is transmitted from the AF to when a pre-setting request is transmitted to the current AMF in the second embodiment. [Figure 35] FIG. 35 is an example of a flowchart of processing related to presetting of an NEF according to a modification of the second embodiment. [Figure 36] FIG. 36 shows an example of a processing sequence from when a pre-setting request is transmitted from the AF to when a pre-setting request is transmitted to the current AMF in a modified example of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] For example, when a mobile terminal such as an onboard device mounted on a vehicle moves to another cell, it takes time to configure the wireless communication settings of the network-side device for the destination cell, and communication quality may deteriorate when the destination cell is changed.

[0011] In one aspect of the present disclosure, a system is configured to preconfigure wireless communication for a user equipment (UE) in advance of the UE's movement, based on information about one or more cells that the UE is expected to be in as the UE moves. When the UE moves to another cell, the system is configured to provide wireless communication services to the UE in the destination cell. This reduces the time required for processing related to system configuration associated with the UE's movement between cells, and allows wireless communication to continue without degradation in wireless communication quality due to the UE's movement between cells.

[0012] More specifically, one aspect of the present disclosure is a system including a plurality of NFs. The NFs acquire, based on first information including information about one or more cells where the UE is predicted to be located as the UE moves, second information to be used in providing wireless communication to the UE when the UE moves from or to a first cell that is a serving cell among the one or more cells, before the UE moves from or to the first cell. When the UE moves from or to the first cell, the NF performs a first process related to providing wireless communication to the UE using the second information without performing a process related to acquiring the second information.

[0013] The system is, for example, a core network system of a mobile communication system of a generation after 5G (5th Generation). An NF is, for example, an instance that performs a predetermined function in a core network of a mobile communication system. An instance of an NF is realized, for example, by executing virtualized computing such as a container on an information processing device. An information processing device that implements an instance of an NF is, for example, a computer equipped with a control unit. The control unit is, for example, a central processing unit (CPU) and a graphics processing unit (GPU), etc. When the system is a 5G core network system, the NF is, for example, an Access and Mobility Management Function (AMF) and a Session Management Function (SMF). However, the NF is not limited to these.

[0014] The UE is, for example, a mobile terminal equipped with a wireless communication function, such as an in-vehicle device installed in a vehicle, a smartphone, or a tablet terminal. The UE may also include a vehicle equipped with a wireless communication function. In addition to vehicles, the UE may also include moving objects such as ships, aircraft, and trains, and devices installed in these moving objects.

[0015] The predetermined processing executed by the second NF to provide wireless communication services to the UE when the UE is located in each of the one or more cells in the future includes, for example, selecting an NF to be changed or added due to a handover of the UE, storing configuration information related to wireless communication for the UE and transmitting it to another NF, etc. The configuration information related to wireless communication for the UE includes, for example, QoS configuration, radio resource allocation, network slice configuration, etc.

[0016] According to one aspect of the present disclosure, a predetermined process is performed on one or more second NFs currently providing wireless communication services to a UE, in anticipation of the UE's movement, so that the second NFs can provide wireless communication services to the UE when the UE is located in one or more cells included in the first information. For example, when the UE moves into the coverage area of ​​another cell, wireless communication settings for the UE have already been configured in one or more second NFs providing wireless communication services in the destination cell. This makes it possible to suppress degradation of wireless communication quality due to movement between cells.

[0017] In one aspect of the present disclosure, multiple NFs may store second information in a storage unit so as to indicate that the second information is pre-configured. Storing the second information in a storage unit so as to indicate that the second information is pre-configured may, for example, be storing the second information together with information indicating that the second information is pre-configured, or storing the configuration information in a storage area reserved for pre-configuration. The information indicating that the second information is pre-configured may, for example, be identification information, a flag, a keyword, or a code of the pre-configuration. This may prevent the second information from conflicting with other configuration information, such as a context, held by the NF.

[0018] Furthermore, when multiple NFs transmit a request to another NF using the second information while executing the first process, the NFs may transmit the second information together with information indicating that the request has been pre-configured, thereby notifying the other NFs that receive the request that the other NFs may hold information obtained regarding the request as the second information.

[0019] Furthermore, when a plurality of NFs receives a request accompanied by information indicating that the information is pre-configured from another NF while executing the first process, the NFs may search a storage unit for the second information. In this way, when a request accompanied by information indicating that the information is pre-configured is received from another NF, the NFs can search the storage unit to detect the second information before executing a process related to the request, which is a process related to obtaining the second information, thereby preventing the process from being executed.

[0020] Furthermore, the NFs may acquire the second information by executing a second process that is a part of the first process. This eliminates the need to execute the second process again when executing the first process, thereby reducing the time required to execute the first process.

[0021] In one aspect of the present disclosure, the system may further include a first NF. The first NF may acquire first information and transmit, to a second NF of the plurality of NFs, a first request for wireless communication pre-configuration of the UE and the first information. The first NF may acquire the first information from route information held by the UE, or may acquire the first information from a Network Data Analytics Function (NWDAF). The plurality of NFs may acquire the second information when a second NF receives the first request. For example, if a first NF transmits the first request upon detecting that a UE has started moving, the system can perform pre-configuration of wireless communication for the UE in real time in response to the UE's movement.

[0022] In one aspect of the present disclosure, the second NF may be an Access and Mobility Management Function (AMF) in charge of managing the mobility of the UE. Upon receiving the first request, the F may transmit a second request to a third NF having at least one of the one or more cells included in the first information as a serving cell, requesting pre-configuration of wireless communication for the UE. Upon receiving the second request, the third NF may perform pre-configuration of wireless communication for the UE. This allows the third NF to perform pre-configuration of wireless communication for the UE, starting from the second NF.

[0023] Furthermore, when the first information includes a cell other than the cell served by the second NF, the second NF may transmit a second request as a third NF to an AMF serving a cell other than the cell served by the second NF included in the first information. As a result, even if the UE may move between AMF regions, pre-configuration of radio communication for the UE is also performed in an AMF including the destination cell in its region. Therefore, when the UE moves from a cell served by the AMF as the second NF to a cell served by the AMF as the third NF in the future, the time required for radio communication configuration for the UE within the system can be reduced.

[0024] Furthermore, when the first information includes a cell other than the cell served by the second NF, the second NF may acquire information about the third NF as part of the second information by selecting an AMF as the third NF from multiple NFs in the system based on the first information. When the UE moves from the cell served by the second NF as the first cell to the cell served by the third NF in the first information, the second NF may perform the handover process as the first process using the acquired information about the third NF without selecting an AMF. This can shorten the time required for handover from the cell served by the second NF as the first cell to the cell served by the third NF.

[0025] In addition, when one or more AMFs included in multiple NFs in the system receive the first request or the second request, and when the serving cells of one or more of its own AMFs included in the first information include a second cell other than the serving cell of the first SMF (Session Management Function) that is managing the first session established by the UE, The UE may transmit a third request to the first SMF and a second SMF that may manage the first session in the second cell, requesting pre-configuration of wireless communication for the UE. In this case, a pre-configuration for handover of the first session may be performed. As a result, when the UE moves to a cell serving the first SMF and a cell serving the second SMF in the future, the UE can continue communication using the first session with little degradation in communication quality. The first session is, for example, a PDU (Packet Data Unit) session.

[0026] Furthermore, the one or more AMFs may select a second SMF from multiple NFs in the system based on the first information, and acquire information about the selected second SMF as one piece of second information. When a UE moves to a second cell, the one or more AMFs may perform a handover process as the first process using information about the second SMF without selecting an SMF. This can shorten the time required for handover from a cell serving the first SMF to a cell serving the second SMF when the UE moves.

[0027] Furthermore, when the first SMF receives the third request and the serving cells of one or more first SMFs included in the first information include a third cell other than the serving cell of the first UPF in which the first session is being established, the first SMF may select a second UPF that may establish the first session in the third cell based on the first information, and acquire information on the selected second UPF as part of the second information. When the UE moves to the third cell, the first SMF may perform a process related to handover as the first process using information on the second UPF without selecting a UPF. This can shorten the time required for handover from a cell serving the first UPF to a cell serving the second UPF due to the movement of the UE.

[0028] Furthermore, when the second SMF receives the third request, it may select a third UPF that may establish the first session in the second cell based on the first information, and acquire information about the selected third UPF as part of the second information. When the UE moves to the second cell, the second SMF may perform the handover process as the first process using information about the third UPF without selecting a UPF. This makes it possible to reduce the time required for handover from a cell served by the first SMF to a cell served by the second SMF when the UE moves.

[0029] In one aspect of the present disclosure, when the second NF receives the first request, the second NF may, as a third NF, designate at least one fourth cell among the one or more cells included in the first information as a serving cell, and transmit a fourth request to a third SMF that may manage a second session when the UE requests establishment of the second session in the fourth cell, requesting pre-configuration of wireless communication for the UE. The second session is a PDU session that may be established in the future. When the third SMF receives the fourth request, the third SMF performs pre-configuration for the establishment of the second session for the UE. Therefore, when the UE requests establishment of the second session in the future while moving through one or more cells included in the first information, it is possible to reduce the time required for configuration for the establishment of the second session for the UE in the system.

[0030] Furthermore, the second NF may acquire information about the third SMF as one of the second information by selecting a third SMF from among multiple NFs in the system based on the first information. When a UE requests establishment of a second session in a fourth cell, the second NF may execute the process for establishing the second session as the first process using the information about the third SMF without selecting an SMF. In this way, when a UE requests establishment of a second session in the fourth cell, the second NF may acquire information about the third SMF as one of the second information. The time required to establish a session can be reduced.

[0031] Furthermore, when the third SMF receives the fourth request, it may select a UPF that may establish the second session in the fourth cell based on the first information, and acquire information about the selected UPF as part of the second information. When the UE requests the establishment of the second session in the fourth cell, the third SMF may perform the first process for establishing the second session using the acquired information about the UPF without selecting a UPF. This makes it possible to reduce the time required to establish the second session when the UE requests the establishment of the second session in the fourth cell.

[0032] As another aspect, the present disclosure can be specified as a method in which multiple NFs execute the above process in the system. The method includes: an NF acquiring, before the UE moves from or to the first cell, second information used to provide wireless communication to the UE when the UE moves from or to a first cell that is a serving cell among the one or more cells, based on first information including information about one or more cells where the UE is predicted to be located as the UE moves; storing the second information in a storage unit; and, when the UE moves from or to the first cell, executing a first process related to providing wireless communication to the UE using the second information stored in the storage unit without executing a process related to acquiring the second information. Furthermore, as another aspect, the present disclosure can be specified as an information processing device corresponding to the NF, a program for causing a computer to execute the process of the information processing device, and a non-transitory computer-readable recording medium having the program recorded thereon.

[0033] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. The configurations of the following embodiments are examples, and the present disclosure is not limited to the configurations of the embodiments.

[0034] First Embodiment FIG. 1 is a diagram showing an example of the architecture of a fifth-generation mobile communication system. The fifth-generation mobile communication network will hereinafter be referred to as the 5G network. The 5G network has a 5G core network (5GC) and an access network ((R)AN). A UE (User Equipment) 50, a DN (Data Network), and an AF (Application Function) 1 are connected to the 5G network. The UE 50 is a terminal of a user (subscriber). A RAN (Radio Access Network) is an access network to the 5GC. The RAN includes a base station (gNB) as one of its nodes. Hereinafter, when simply referred to as RAN, it refers to a node within the RAN.

[0035] FIG. 1 shows some of the components included in 5GC. Also, in FIG. 1, the components according to the first embodiment are denoted by reference numerals. In 5G, the software that realizes network functions and the hardware on which the software runs are separated using hardware abstraction technology. This allows various network function software to run on common hardware resources, regardless of the configuration of each hardware product. FIG. 1 shows the network functions (NFs) included in 5GC. Each of the multiple NFs included in 5GC is realized by one or more computers (information processing devices) executing a program. However, a single computer may realize any two or more NFs.

[0036] UPF (User Plane Function) is responsible for routing, forwarding, and The user packets are user plane packets that the UE 50 transmits and receives.

[0037] AMF (Access and Mobility Management Function) 7 houses the RAN and manages the 5GC. AMF 7 performs registration management, connection management, and mobility management for UEs in SMF. It also relays messages between the UE 50 and the UE 6.

[0038] SMF (Session Management Function) 6 is a PDU (Protocol Data Unit) session It manages PDU sessions, assigns and manages IP addresses to UEs, and selects and controls UPF. PDU session management includes the establishment and modification of PDU sessions. For example, when a policy is changed, the PD A change in the U-session occurs, and a change in QoS or policy is applied to the UPF through the SMF 6. A PDU session is a virtual communication path for exchanging data between the UE 50 and the DN. The DN is a data network (cloud, internet, etc.) external to the 5GC.

[0039] The PCF (Policy Control Function) 5 is responsible for, for example, the policy of access and mobility management. The UDR 4 manages policies for session management and charging, and provides policy-related information to the AMF and SMF. Policies related to access and movement include, for example, routing. Policies related to session management include QoS and filtering. For example, when information related to a policy is registered, changed, or deleted in the UDR 4, it is notified to the PCF 5, and the PCF 5 notifies the AMF 7 or SMF 6.

[0040] UDM (Unified Data Management)2 is a service that manages and manages subscribers' information. The subscriber information includes, for example, access and mobility subscription data used for registering the UE 50 and managing mobility, and slice selection subscriber information used for network slice selection. Slice Selection Subscription data, SMF Selection used to select SMF 6 Subscriber information (SMF Selection subscription data), used to establish a PDU session The network slice includes session management subscription data used for communication with the UE 50, and energy related subscription data used for processing related to communication with the UE 50. A network slice is a virtual network with specifications according to its intended use.

[0041] The UDR 4 stores and provides retrieval of data used by the UDM 2, PCF 5, and NEF 3. More specifically, the data held by the UDR 4 includes, for example, subscriber information, authentication information, and policy data.

[0042] The NEF 3 provides a function for securely disclosing capabilities and event information disclosed by network functions in the 5G system to external applications such as the AF 1. The NEF 3 also provides a function for receiving information from authorized external applications into the network. The AF 1 is an application server (external server) that provides auxiliary services other than those specified in the 5GC specification. In the first embodiment, the NEF 3 manages preconfiguration (PreConfiguration) related to wireless communication for the UE 50 in 5GC, in advance of the movement of the UE 50. Details of the preconfiguration related to wireless communication for the UE 50 will be described later.

[0043] The NWDAF 8 provides, for example, analytical and statistical information within the network, and analytical and predictive information regarding the movement of the UE 50. The predictive information regarding the movement provided by the NWDAF 8 includes, for example, information regarding cells to which the UE may move.

[0044] The Edge Application Server Discovery Function (EASDF) mediates communication between the UE 50 and the DNS server. The EASDF discovers the EAS using the DNS server.

[0045] The NRF stores and manages information about NFs (e.g., AMF, SMF, UPF, etc.) within 5GC. In response to an inquiry about an NF to be used, the NRF can return multiple NF candidates to the inquiry source. The AUSF provides the UE authentication function. The UDM holds subscriber contract information and authentication information for AKA authentication.

[0046] In 5GC, multiple NFs of the same type may be prepared. For example, one NF may be prepared for each data center (station). Also, one NF may be shared between data centers. Also, one data center may configure multiple NFs of the same type. The correspondence between NFs and data centers can be set as appropriate.

[0047] FIG. 2 is a diagram illustrating processing in the communication system 100 according to the first embodiment. The communication system 100 is, for example, a system in which a vehicle manufacturer provides communications and communication services to vehicles equipped with communication functions. The communication system 100 includes a 5GC 10, multiple RANs 20, and a UE 50. FIG. 2 shows some of the NFs included in the 5GC 10. The communication system 100 includes multiple UEs 50, but FIG. 2 shows one UE 50 as a representative.

[0048] In the communication system 100 according to the first embodiment, the UE 50 is a vehicle or an in-vehicle device mounted on a vehicle. The in-vehicle device is, for example, a device having a wireless communication function, such as a data communication module and a car navigation system. In the description, it is assumed that the UE 50 is a data communication device mounted on a vehicle. In the first embodiment, it is assumed that the UE 50 has been registered with the 5GC 10 and has established at least one PDU session.

[0049] In the first embodiment, the communication system 100 provides a pre-configuration service. The pre-configuration service is a service in which, in advance of the movement of the UE 50, the 5CG 10 performs pre-configuration related to wireless communication for the UE 50 in one or more cells through which the planned movement route of the UE 50 passes. In the first embodiment, the pre-configuration service performs pre-configuration related to handover in the 5CG 10, assuming movement of the UE 50 along the planned movement route, and pre-configuration for the establishment of a PDU session that may occur in the future. This allows handover to be performed more smoothly when the UE 50 moves along the planned movement route. Furthermore, while the UE 50 is moving along the planned movement route, for example, if establishment of a PDU session is initiated for communication of a predetermined application, the PDU session can be established more smoothly, and QoS-related settings can be applied, thereby providing a communication service with a quality suitable for the application.

[0050] In the first embodiment, the AF 1 is an AF that provides a service of performing pre-configuration related to wireless communication for the UE 50. The AF 1 transmits a pre-configuration request to the 5CG 10. The pre-configuration request transmitted by the AF 1 is a request for requesting pre-configuration related to wireless communication for the UE 50. In the first embodiment, identification information and route information of the UE 50 are also transmitted together with the pre-configuration request. The route information of the UE 50 is, for example, a route set in a car navigation system of the UE 50. When the pre-configuration request is input from the AF 1 to the 5CG 10, pre-configuration related to wireless communication for the UE 50 in the 5CG 10 is started.

[0051] In the 5GC 10, the pre-configuration request sent from the AF 1 is received by the NEF 3. The NEF 3 converts the route information into cell transition information. The cell transition information is a list of information indicating cells arranged in route order. The cell transition information can also be said to be a list of handover destination cells of the UE 50 arranged in the order in which the UE 50 will be handed over. The NEF 3 also identifies the AMF 7 currently in charge of managing access and mobility of the UE 50. The NEF 3 transmits to the AMF 7 a pre-configuration request requesting pre-configuration of radio communication for the UE 50 and the cell transition information.

[0052] In the first embodiment, the starting point of pre-configuration related to radio communication for UE 50 in 5GC 10 is AMF 7 in charge of managing access and mobility of UE 50. NFs related to (I) pre-configuration related to handover and (II) pre-configuration related to establishment of PDU sessions are mainly AMF(s) and SMF(s). Therefore, in the first embodiment, pre-configuration is sequentially performed from the AMF 7 serving as the starting point to the AMF 7 and SMF 6 related to pre-configuration related to radio communication for UE 50. The reason why the AMF 7 in charge of managing access and mobility of UE 50 is used as the starting point is that the AMF 7 holds all the information about UE 50 used for (I) pre-configuration related to handover and (II) pre-configuration related to PDU sessions. One of the pieces of information about the UE 50 held by the AMF 7 is information indicating cooperation between NFs, such as an SM context ID, a UE policy association ID, an AM policy association ID, and an SM policy association ID.

[0053] Hereinafter, preconfiguration related to radio communication for UE 50 will also be simply referred to as preconfiguration. (I) Preconfiguration related to handover will simply be referred to as handover preconfiguration. (II) Preconfiguration related to establishment of a PDU session will simply be referred to as PDU session preconfiguration. Furthermore, one or more NFs related to the preconfiguration will be referred to as related NFs.

[0054] In the first embodiment, in the procedures of (I) handover pre-configuration and (II) PDU session pre-configuration in 5GC 10, each related NF is made to perform the following processing as a pre-configuration process. (A) NF selection process performed in the handover procedure and PDU session establishment procedure. (B) Association establishment process between related NFs established in the handover procedure. (C) Storage process of the information obtained by processes (A) and (B) as pre-configured information.

[0055] The AMF 7 and the related NFs that have received the pre-configuration request each perform the above steps (A) to (C). As a result, when a handover or / and a PDU session is established while the UE 50 is moving on a route, the related NFs have performed the pre-configuration process, so that the handover or / and the PDU session can be established more quickly.

[0056] 3, 4, 5, and 6 are examples of handover scenarios in the first embodiment. FIG. 3 is a diagram showing handover scenario #1. Handover scenario #1 is a scenario in which the entire path from the origin to the destination of UE 50 is contained within a single AMF 7 region. In scenario #1, a handover occurs between RANs. Hereinafter, the NF and RAN responsible for processing related to UE 50 at the origin or time of departure will be referred to as the current NF and current RAN, respectively. The NF and RAN scheduled to be responsible for processing related to UE 50 at the destination of UE 50 will be referred to as the future NF and future RAN, respectively. An AMF region is set on a cell-by-cell or TA-by-TA basis. Therefore, a cell within an AMF region can also be referred to as an AMF-served cell.

[0057] In scenario #1, there is no replacement, addition, or release of the AMF and SMF responsible for processing the UE 50. In scenario #1, a pre-configuration request is sent from the current AMF 7A to the current SMF 6A. The pre-configuration request is sent to the current SMF 6A because the handover also causes changes to be made to established PDU sessions.

[0058] FIG. 4 illustrates handover scenario #2. Handover scenario #2 is a scenario in which the route from the origin of UE 50 to the destination spans two regions, AMF 7A and AMF 7B. In scenario #2, the route is assumed to be within the service area of ​​SMF 6A. In scenario #2, a handover between RANs occurs, and a replacement from AMF 7A to AMF 7B occurs when moving from the region of current AMF 7A to the region of future AMF 7B. In scenario #2, a handover from current AMF 7A to current AMF 7B occurs. In addition to the ent SMF 6A, a pre-configuration request is also sent from the current AMF 7A to the future AMF 7B. Hereinafter, the region of the current AMF will be referred to as the current region, and the region of the future AMF will be referred to as the future region. The service area of ​​an SMF is set on a cell-by-cell or TA-by-TA basis. Therefore, a cell within the service area of ​​an SMF can also be said to be the cell responsible for the SMF.

[0059] 5 is a diagram illustrating handover scenario #3. Handover scenario #3 is a scenario in which the path from the origin to the destination of UE 50 is included in one AMF 7A region but spans the service areas of two SMFs 6A and 6C. Scenario #3 includes handover between RANs and insertion of SMF 6C as an I-SMF (Intermediate-SMF) when moving from the service area of ​​the current SMF 6A to the service area of ​​the future SMF 6C. In scenario #2, the current AMF 7A is replaced by the current In addition to SMF 6A, pre-configuration requests are sent from the current AMF 7A to future SMF 6C.

[0060] 6 illustrates handover scenario #4. Handover scenario #4 is a scenario in which the route from the origin to the destination of UE 50 spans two regions (AMF 7A and AMF 7C) and also spans the service areas of two SMFs 6A and SMF 6D. In scenario #4, an inter-RAN handover occurs, an AMF change occurs when UE 50 moves from the region of current AMF 7A to the region of future AMF 7C, and SMF 6D as the I-SMF changes when UE 50 moves from the service area of ​​current SMF 6A to the service area of ​​future SMF 6D. In scenario #4, pre-configuration requests are sent from current AMF 7A to current SMF 6A, as well as from current AMF 7A to future AMF 7C and from future AMF 7C to future SMF 6D.

[0061] In Fig. 6, for convenience of explanation, the AMF region and the SMF service area are shown as if they are the same range. However, this is not limited to this, and the AMF region and the SMF service area may be set to different ranges independently. Furthermore, the handover scenarios are not limited to scenarios #1 to #4. <Device configuration>

[0062] FIG. 7 is a diagram showing an example of the hardware configuration of an information processing device that can operate as each NF and AF 1 in the 5GC 10. The information processing device 110 is a personal computer. The information processing device 110 can be configured using an information processing device (computer) such as a personal computer (PC), a workstation (WS), or a server machine. The information processing device 110 may be a collection (cloud) of one or more computers. Note that the NF and AF 1 in the 5G core network may be configured using a dedicated FPGA (Field-Programmable Gate Array) or ASIC that executes the relevant processing. It may also be a device equipped with an electrical circuit such as an Application Specific Integrated Circuit (ASIC). stomach.

[0063] The information processing device 110 has, as its hardware configuration, a processor 101, a memory 102, an auxiliary storage device 103, and a communication unit 104. The memory 102 and the auxiliary storage device 103 are computer-readable recording media. The processor 101, the auxiliary storage device 103, and the communication unit 104 are electrically connected by a bus.

[0064] The auxiliary storage device 103 stores programs used to operate as either each NF or AF 1 in the 5G core network, and data used by the processor 101 when executing each program. The auxiliary storage device 103 is, for example, an erasable programmable ROM (EPROM), a hard disk drive, or a solid state drive (SSD). The programs stored in the auxiliary storage device 103 include, for example, an operating system The operating system (OS) and the corresponding NF or AF control program are included.

[0065] The memory 102 is a storage device that provides the processor 101 with a storage area and a working area for loading programs stored in the auxiliary storage device 103, and is used as a buffer. The memory 102 includes, for example, semiconductor memory such as a ROM (Read Only Memory) and a RAM (Random Access Memory).

[0066] The processor 101 loads into the memory 102 an OS stored in the auxiliary storage device 103 and a program related to either one of the NFs or AFs 1 in the 5G core network and executes the programs, thereby executing processing corresponding to each NF or AF 1 in the 5G core network. The processor 101 is, for example, a CPU or a DSP (Digital Signal Processor). The number of processors 101 is not limited to one, and multiple processors 101 may be provided.

[0067] The communication unit 104 is, for example, a network interface card (NIC), an optical line interface, etc. The communication unit 104 may be, for example, a wireless communication circuit that connects to a wireless network such as a wireless LAN. The hardware configuration of the information processing device 110 that realizes the functions of each NF and AF 1 in the 5G core network is not limited to that shown in FIG. 7.

[0068] FIG. 8 is a diagram showing an example of the functional configuration of the AF 1. In FIG. 8, functional components according to the first embodiment are extracted from the functional configuration of the AF 1 and shown. The same applies to the functional configuration of each subsequent NF. The AF 1 includes a control unit 11 as a functional component. The AF 1 receives route information from the UE 50. For example, when one of multiple routes searched by a car navigation system is selected and an operation to start route guidance is input, the UE 50 transmits the set route information to the AF 1. The route information includes, for example, position information of a departure point, one or more points on the route, and a destination point in the order in which they are passed. The position information is, for example, latitude and longitude.

[0069] When the control unit 11 receives the route information from the UE 50, it first transmits a QoS registration request to the NEF 3, requesting registration of the QoS setting contents for the UE 50 for the application to be pre-configured, which is used when pre-configuring a PDU session. The QoS registration request also transmits identification information of the UE 50, identification information of the flow of the target application, and QoS setting information. The identification information of the UE 50 is, for example, , SUPI (Subscription Permanent Identifier) ​​of the target application. The flow identification information is, for example, a combination of a destination IP address, a source IP address, a destination port number, a source port number, and a protocol number, or an application ID. The QoS setting information includes, for example, priority, required delay, maximum burst size, maximum bit rate, guaranteed bit rate, packet error rate, etc. However, the QoS setting information is not limited to these.

[0070] It should be noted that the identification information of the target application does not need to be transmitted if it is desired to set the same QoS for all PDU sessions of the UE 50. When the control unit 11 receives a response to the QoS registration request from the NEF 3, it transmits a pre-configuration request, the identification information of the UE 50, the route information, and the identification information of the target application to the NEF 3.

[0071] 9 is a diagram showing an example of the functional configuration of the NEF 3. The NEF 3 has, as its functional configuration, a control unit 31 and a geographic information conversion unit 32. When the control unit 31 receives a QoS registration request from the AF 1, it transmits the QoS registration request, identification information of the UE 50, identification information of the target application, and QoS setting information to the UDM 2, and requests registration from the UDM 2. When it receives a response to the request from the UDM 2, the control unit 31 transmits the response to the QoS registration request to the AF 1.

[0072] When the control unit 31 receives a pre-configuration request from the AF 1, the control unit 31 requests the geographic information conversion unit 32 to convert the route information received together with the pre-configuration request into cell transition information, thereby acquiring the cell transition information. The NEF 3 identifies the AMF 7 (current AMF) responsible for managing the mobility of the UE 50. The NEF 3 identifies the current AMF by, for example, querying the UDM 2. The NEF 3 transmits a handover pre-configuration request, UE identification information, and cell transition information to the current AMF 7. Furthermore, if a PDU session for the target application has not been established, the NEF 3 transmits a PDU session pre-configuration request, UE identification information, cell transition information, and flow identification information for the target application to the current AMF 7. Whether the UE 50 has established a PDU session for the target application may be acquired by, for example, querying the UDM 2, or the AF 1 may acquire information on the application currently communicating from the UE 50 and notify the NEF 3 of the information together with the pre-configuration request.

[0073] The geographic information conversion unit 32 converts the geographic area into a list of TA (Tracking Area), RAN no. In the first embodiment, when route information is input from the control unit 31, the geographic information conversion unit 32 converts, for example, location information of the starting point, intermediate points, destination point, and multiple points on the route from the starting point to the destination, included in the route information into cell identification information, arranges the information in order from the starting point to the destination, and converts the route information into cell transition information. However, the information included in the cell transition information is not limited to cell identification information, and may be a list of TAs or identification information of RAN nodes. The geographic information conversion unit 32 outputs the cell transition information to the control unit 31.

[0074] FIG. 10 is a diagram showing an example of the functional configuration of the AMF 7. The AMF 7 includes a control unit 71 and a setting information storage unit 72 as functional components. The control unit 71 executes handover pre-configuration processing when it receives a handover pre-configuration request from the NEF 3. The control unit 71 executes PDU session pre-configuration processing when it receives a PDU session pre-configuration request from the NEF 3. In the first embodiment, the handover pre-configuration processing and PDU session pre-configuration processing of the AMF 7 are respectively executed as handover pre-configuration processing. This is similar to some of the processing performed by the AMF in the PDU session establishment procedure, except that information indicating pre-configuration is also sent along with messages exchanged with other NFs.

[0075] The handover pre-configuration process is divided into processes for within the region of AMF 7 and processes for outside the region of AMF 7. In the handover pre-configuration process, a handover pre-configuration request, which is a pre-configuration request for handover, is used.

[0076] In the intra-region handover pre-configuration process, the control unit 71 sends a pre-configuration request to the SMF (current SMF) responsible for managing the currently established PDU session, prompting the control unit 71 to determine whether a UPF should be selected for the handover. The control unit 71 also determines whether an I-SMF (Intermediate-SMF) should be inserted, replaced, or removed for the currently established PDU session, based on the cell transition information. If the control unit 71 determines the insertion, replacement, or removal of an I-SMF, it performs the corresponding process with the corresponding I-SMF, as disclosed in the 3GPP standard. For example, if the control unit 71 determines the insertion or replacement of an I-SMF, it selects a new I-SMF (future SMF) and sends a handover pre-configuration request to the selected future SMF to prompt the establishment of an association and the selection of a UPF. When it is determined that the I-SMF is to be released, the control unit 71 identifies the SMF that manages the I-SMF, transmits a handover pre-setting request, and establishes an association.

[0077] The out-of-region handover pre-configuration process is executed when the route of the UE 50 spans the region of another AMF 7. In the out-of-region handover pre-configuration process, the control unit 71 selects another AMF (future AMF) that is likely to be in charge of mobility management in the destination cell of the UE 50 based on the cell transition information, and transmits a pre-configuration request to the future AMF.

[0078] In the PDU session pre-configuration process, the control unit 71 selects an SMF 6 (future AMF) that will manage the new PDU session when a new PDU session is established in the future for the UE 50. The control unit 71 transmits a PDU session pre-configuration request, which is a pre-configuration request for the PDU session, to the selected future AMF.

[0079] When the control unit 71 receives a pre-configuration request from another AMF 7, it executes handover pre-configuration processing within the region as a future AMF. Furthermore, the control unit 71 stores information acquired in the handover pre-configuration processing and PDU session pre-configuration processing in the configuration information storage unit 72. Hereinafter, with respect to the AMF 7, the handover pre-configuration processing and PDU session pre-configuration processing may be collectively referred to as the pre-configuration processing. Hereinafter, the information acquired through the execution of the handover pre-configuration processing and PDU session pre-configuration processing is also referred to as pre-configuration information.

[0080] When the control unit 71 receives a handover request or a PDU session establishment request, it refers to the preset information stored in the setting information storage unit 72. If there is corresponding preset information, the control unit 71 uses the preset information to perform the subsequent handover process or PDU session establishment process.

[0081] The setting information storage unit 72 is, for example, a part of the storage area of ​​the auxiliary storage device 103 of the information processing device 110 in which the AMF 7 is implemented. The preset information acquired through the execution of the process is stored with an indication that it is preset information. For example, the preset information may be stored in a storage area or file prepared for preset information, thereby indicating that it is preset information. Alternatively, the preset information may be stored in the setting information storage unit 72 together with information indicating that it is "preset." The information indicating that it is "preset" may be, for example, a preset ID, a flag, a code, or a keyword.

[0082] FIG. 10 illustrates an example in which preconfiguration information is stored in a storage area prepared for preconfiguration information in the configuration information storage unit 72. In the example illustrated in FIG. 10, preconfiguration information is stored for each identification information (UE ID) of the UE 50. Furthermore, preconfiguration information is stored for each preconfiguration ID. The preconfiguration ID is uniquely assigned to each preconfiguration request by, for example, the NEF 3. The preconfiguration information identified by the preconfiguration ID includes preconfiguration information obtained through a handover preconfiguration process and preconfiguration information obtained through a PDU session preconfiguration process. The preconfiguration information obtained through the handover preconfiguration process is hereinafter referred to as handover preconfiguration information. The preconfiguration information obtained through the PDU session preconfiguration process is hereinafter referred to as PDU session preconfiguration information.

[0083] The handover preconfiguration information includes, for example, a target RAN ID and PDU session-specific information for each PDU session. The RAN ID may be a cell ID or a RAN node ID. The PDU session-specific information includes a PDU session ID, an SMF ID that has established an SM association with the AMF 7, an SM context ID, and the like. The SM context ID is identification information assigned by the SMF to identify the SM association between the AMF and the SMF for the PDU session. In addition, if the target RAN is a cell outside the AMF 7 region, the PDU session-specific information includes a target AMF ID, which is the ID of the AMF selected as the future AMF. Furthermore, if the target RAN is a cell outside the service area of ​​the SMF responsible for managing the PDU session, the ID of the selected SMF is included. PDU session-specific information in the handover preconfiguration information is maintained for each established PDU session.

[0084] The PDU session pre-configuration information includes QoS flow-specific information. The QoS flow-specific information includes, for example, QoS flow identification information, the SMF ID of the SMF selected to manage the PDU session corresponding to the QoS flow, and the SM context ID in the SMF. The QoS flow identification information is the flow identification information of the target application sent from the AF 1 together with the QS registration request. The QoS flow identification information includes, for example, the destination IP address, the source IP address, the destination port number, the source port number, and the protocol number.

[0085] Note that the SMF ID included in the pre-configuration information obtained through the handover pre-configuration process is the SMF responsible for managing the established PDU session, while the SMF ID included in the PDU session pre-configuration information is the SMF responsible for managing the PDU session that may be established in the future (i.e., not yet established). Note that the information included in the pre-configuration information held by the AMF shown in Figure 10 is an example. The information included in the pre-configuration information held by the AMF is not limited to the example shown in Figure 10.

[0086] For example, when a handover request is received, the control unit 71 searches the setting information storage unit 72 using the UE ID, target RAN ID, and PDU session ID of the handover request as keys. If handover preset information exists, the control unit 71 performs the subsequent handover process using the handover preset information.

[0087] For example, when a PDU session establishment request is received, the control unit 71 searches the setting information storage unit 72 using the UE ID included in the PDU session establishment request as a key. If PDU session pre-configuration information that matches the search key is present, the control unit 71 performs the subsequent PDU session establishment process using the PDU session pre-configuration information.

[0088] FIG. 11 is a diagram illustrating an example of the functional configuration of the SMF 6. The SMF 6 includes a control unit 61 as a functional component. When the control unit 61 receives a handover pre-configuration request from the SMF 6, it selects a UPF to which an established PDU session in a target cell of the handover is assigned as a handover pre-configuration process. When the control unit 61 receives a PDU session pre-configuration request from the SMF 6, it performs, as a PDU session pre-configuration process, NF selection and policy information acquisition processes, which are processes executed by the SMF in the PDU session establishment procedure. The control unit 61 also stores information acquired through the pre-configuration process in the configuration information storage unit 62. When the control unit 61 receives a handover request or a PDU session establishment request, it refers to the pre-configuration information stored in the configuration information storage unit 62. If there is corresponding pre-configuration information, the control unit 61 uses the pre-configuration information to perform the subsequent handover process or PDU session establishment process.

[0089] The setting information storage unit 62 is, for example, a part of the storage area of ​​the auxiliary storage device 103 of the information processing device 110 in which the SMF 6 is implemented. The setting information DB 62 stores the pre-setting information acquired by the control unit 61 through the execution of the pre-setting process, with the information clearly indicated as being pre-setting.

[0090] 11, the preset information is held for each identification information of the UE 50. Furthermore, the preset information is held for each preset ID. The preset information identified by the preset ID includes handover preset information and PDU session preset information.

[0091] The handover pre-configuration information includes, for example, the target RAN ID and PDU session-specific information for each PDU session. The PDU session-specific information includes, for example, the PDU session ID, the AMF ID that has established an SM association for the PDU session, the SM context ID, the old SMF ID, and the selected UPF ID. The PDU session-specific information in the handover pre-configuration information is maintained for each established PDU session whose management is assigned to the SMF at the time the pre-configuration request is issued. The AMF that has established an SM association is the AMF that sent the handover pre-configuration request.

[0092] The PDU session pre-configuration information includes QoS flow-oriented information. The QoS flow-oriented information includes, for example, QoS flow identification information, the AMF ID that establishes the SM association, the SM context ID, the ID of the selected PCF that is assigned policy management for the PDU session of the target application, the SM policy association ID, the selected UPF ID, and QoS information. The QoS information includes the QoS configuration information sent from the AF 1 together with the QoS registration request. Note that the information included in the pre-configuration information held by the SMF 6 shown in FIG. 11 is an example. The information included in the pre-configuration information held by the SMF 6 is not limited to the example shown in FIG. 11.

[0093] For example, when a handover request is received from the AMF, the control unit 61 searches the setting information storage unit 62 using the UE ID, preconfigured ID, target RAN ID, and PDU session ID received together with the handover request as keys in the setting information storage unit 62. If handover preconfiguration information matching the search key exists, the control unit 61 performs the subsequent handover processing using the handover preconfiguration information.

[0094] For example, when a PDU session establishment request is received, the control unit 61 searches the configuration information storage unit 62 using the UE ID, pre-configured ID, and SM context ID received together with the PDU session establishment request as keys. If PDU session pre-configuration information matching the search key is present, the control unit 61 performs the subsequent PDU session establishment process using the PDU session pre-configuration information. Note that the pre-configuration information held by the SMF 6 is not limited to the information shown in FIG. 11, and information received from other NFs through the pre-configuration process may also be held. Note that the functional configurations of each NF shown in FIGS. 8 to 11 are merely examples, and the functional configurations of each NF are not limited to the functional configurations shown in FIGS. 8 to 11.

[0095] <Processing flow> FIG. 12 is an example of a flowchart of processing related to a pre-configuration request of AF 1. The processing shown in FIG. 12 is repeatedly executed at a predetermined cycle. The processing shown in FIG. 12 is executed by the CPU 101 of the information processing device 110 in which an instance of AF 1 is implemented. However, for convenience of explanation, the processing will be explained with AF 1 or a functional component of AF 1 as the main entity. Furthermore, when AF 1 is explained as the main entity in the explanation of the flowchart, it is assumed that the processing is handled by the control unit of AF 1. The same applies to the flowcharts from FIG. 12 onwards.

[0096] In OP11, the AF 1 determines whether or not route information has been received from the UE 50. If route information has been received from the UE 50 (OP11: YES), the process proceeds to OP12. If route information has not been received from the UE 50 (OP11: NO), the process shown in Fig. 12 ends. Along with the route information, information on the application currently in communication is also received from the UE 50.

[0097] In OP12, the AF 1 transmits a QoS registration request for the target application to the NEF 3. Along with the QoS registration request, for example, identification information of the UE 50, flow identification information of the target application, and QoS setting information are also transmitted.

[0098] In OP13, the AF 1 determines whether or not a response to the QoS registration request has been received. If a response to the QoS registration request has been received (OP13: YES), the process proceeds to OP14. The AF 1 remains in a standby state until a response to the QoS registration request is received (OP13: NO).

[0099] In OP14, the AF 1 sends a pre-configuration request to the NEF 3. Along with the pre-configuration request, identification information of the UE 50, route information, flow identification information of the target application, and information indicating whether the UE 50 has already established a PUD session for the target application are also sent.

[0100] In OP15, the AF 1 determines whether a response to the pre-configuration request has been received. If a response to the pre-configuration request has been received (OP15: YES), the processing shown in Fig. 12 ends. The AF 1 remains in a standby state until a response to the pre-configuration request has been received (OP15: NO).

[0101] FIG. 13 is an example of a flowchart of a process related to the presetting of the NEF 3. The process shown in FIG. 13 is repeatedly executed at a predetermined cycle. In OP21, the NEF 3 13. In OP21, it is determined whether a pre-configuration request has been received from AF 1. If a pre-configuration request has been received from AF 1 (OP21: YES), the process proceeds to OP22. If a pre-configuration request has not been received from AF 1 (OP21: NO), the process shown in FIG. 13 ends.

[0102] In OP22, the NEF 3 (geographic information conversion unit 32) converts the route information into cell transition information. In OP23, the NEF 3 queries the UDM 2 to identify the AMF that manages the mobility of the UE 50 as the target of pre-configuration. In OP24, the NEF 3 sends a handover pre-configuration request to the identified AMF. The pre-configuration ID, identification information of the UE 50, and cell transition information are also sent together with the handover pre-configuration request. If multiple AMFs are identified in OP23, a handover pre-configuration request is sent to each AMF.

[0103] In OP25, the NEF 3 determines whether a PDU session for the target application has been established. For example, the determination in OP25 is made based on information indicating whether the UE 50 has established a PDU session for the target application, which is received from the AF 1 together with the pre-configuration request. If a PDU session for the target application has been established (OP25: YES), the process proceeds to OP27. If a PDU session for the target application has not been established (OP25: NO), the process proceeds to OP26.

[0104] In OP26, the NEF 3 sends a PDU session pre-configuration request to the AMF identified in OP23. Along with the PDU session pre-configuration request, the pre-configuration ID, the identification information of the UE 50, the cell transition information, and the flow identification information of the application to be pre-configured are also sent.

[0105] In OP27, the NEF 3 determines whether or not a response to the handover and PDU session pre-configuration request has been received. If a response to the pre-configuration request has been received (OP27: YES), the process proceeds to OP28. If a response to the pre-configuration request has been received (OP27: NO), the NEF 3 enters a standby state. In OP28, the NEF 3 transmits the response to the pre-configuration request to the AF 1. Then, the process shown in FIG. 13 ends.

[0106] FIG. 14 is an example of a flowchart of the processing of the AMF 7 when a handover preset request is received. The processing shown in FIG. 14 is repeatedly executed at a predetermined cycle. In OP31, the AMF 7 determines whether or not a handover preset request has been received from the NEF 3. If a handover preset request has been received (OP31: YES), the processing of OP32 and OP33 is initiated. The processing of OP32 and OP33 is performed in parallel. If a handover preset request has not been received (OP31: NO), the processing proceeds to OP38A.

[0107] The processes of OP32 to OP37 are processes that are executed when the AMF 7 is the current AMF and receives a pre-configuration request from the NEF 3. In OP32, the AMF 7 executes an intra-region handover process. In OP33, the AMF 7 executes an out-of-region handover process. Details of the intra-region handover process and the out-of-region handover process will be described later.

[0108] In OP35, the AMF 7 determines whether or not all of the processing from OP32 to OP33 has been completed. If all of the processing from OP32 to OP33 has been completed (OP35: YES), the processing proceeds to OP36. The AMF 7 remains in a standby state until all of the processing from OP32 to OP34 has been completed (OP35: NO).

[0109] In OP36, the AMF 7 stores the handover pre-configuration information in the configuration information storage unit 72. In OP37, the AMF 7 transmits a response to the handover pre-configuration request to the NEF 3. Thereafter, the processing shown in Fig. 14 ends.

[0110] The processes from OP38A to OP38D are processes when AMF 7 is selected as the future AMF. In OP38A, AMF 7 determines whether or not a pre-configuration request has been received from the AMF. If a pre-configuration request has been received from the AMF (OP38A: YES), the process proceeds to OP38B. If a pre-configuration request has not been received from the AMF (OP38B: NO), the process shown in Fig. 14 ends.

[0111] In OP38B, the AMF 7 executes intra-region handover processing. In OP38C, the AMF 7 stores the pre-configuration information in the configuration information storage unit 72. In OP38D, the AMF 7 transmits a response to the pre-configuration request to the AMF that transmitted the pre-configuration request received in OP38. Thereafter, the processing shown in FIG. 14 ends.

[0112] FIG. 15 is an example of a flowchart of an intra-region handover pre-configuration process. The process shown in FIG. 15 is a process executed in OP32 of FIG. 14. In the process shown in FIG. 15, AMF 7 corresponds to the current AMF. The process in FIG. 15 is executed by the UE 50 for each PDU session currently being established. The PDU session that is the target of the process is referred to as the target PDU session. Therefore, in FIG. 15, The SMF is the SMF in charge of processing the PDU session in question.

[0113] In OP321, the AMF 7 determines whether or not a future RAN is present in the region based on the cell transition information. The future RAN is a RAN corresponding to a cell included in the cell transition information and is a RAN to which the UE 50 is not currently serving. If a future RAN is present in the region (OP321: YES), the process proceeds to OP322 and OP324. If a future RAN is not present in the region (OP321: NO), the process shown in Fig. 15 ends, and the process proceeds to OP35 in Fig. 14.

[0114] The processes from OP322 to OP323 and the processes from OP324 to OP327 are executed in parallel. The processes from OP322 to OP323 are processes for the current SMF. In OP322, the AMF 7 sends a handover pre-configuration request to the current SMF. Together with the handover pre-configuration request, the ID of the UE 50, the pre-configuration ID, cell transition information, and the ID of the PDU session to be handed over are also sent.

[0115] In OP323, the AMF 7 determines whether or not a response to the handover pre-configuration request has been received from the current SMF. If a response to the handover pre-configuration request has been received from the current SMF (OP323: YES), processing for the current SMF for the target PDU session is terminated. The AMF 7 remains in a waiting state until a response to the handover pre-configuration request is received from the current SMF (OP323: NO).

[0116] The processing from OP324 to OP327 is processing related to future SMF. In OP324, AMF 7 includes the cell transition information indicating that the cell transition is outside the service area of ​​the current SMF. If the cell transition information includes a cell outside the service area of ​​the current SMF (OP324: YES), the process proceeds to OP325. If the cell transition information does not include a cell outside the service area of ​​the current SMF (OP324: NO), the process for the future SMF for the target PDU session ends.

[0117] In OP325, the AMF 7 selects a future SMF whose service area includes a cell outside the service area of ​​the current SMF included in the cell transition information. The AMF 7 queries the NRF for candidate AMFs, for example, according to the 3GPP standard, and selects a future SMF from the list of candidate SMFs, taking into consideration the future RAN, the service area of ​​the SMF, the processing load of the SMF, etc. In OP326, the AMF 7 transmits a handover pre-configuration request to the SMF selected as the future SMF. The handover pre-configuration request also transmits the ID of the UE 50, the pre-configuration ID, the cell transition information, the PDU session ID to be handovered, and the target RAN ID in the case of handover to a cell within the service area of ​​the future SMF.

[0118] In OP327, the AMF 7 determines whether or not a response to the handover pre-configuration request has been received. If a response to the handover pre-configuration request has been received (OP327: YES), the processing related to the future SMF for the target PDU session is terminated. The AMF 7 remains in a standby state until a response to the handover pre-configuration request is received (OP327: NO). When the processing related to the current SMF and the processing related to the future SMF for all established PDU sessions is terminated, the processing shown in FIG. 15 is terminated, and the processing proceeds to OP35 in FIG. 14.

[0119] Fig. 16 is an example of a flowchart of an out-of-region handover pre-configuration process of AMF 7. The process shown in Fig. 16 is a process executed in OP33 of Fig. 14. In the process shown in Fig. 16, AMF 7 is the current AMF.

[0120] In operation OP331, the AMF 7 determines whether or not the cell transition information includes a cell outside the region. If the cell transition information includes a cell outside the region (OP331: YES), the process proceeds to operation OP332. If the cell transition information does not include a cell outside the region (OP331: NO), the process shown in Fig. 16 ends.

[0121] In OP332, AMF 7 selects a future AMF. For example, according to the 3GPP standard, AMF 7 queries the NRF for candidate AMFs and selects, from the list of candidate SMFs, an AMF whose region includes a cell outside the region included in the cell transition information as the future AMF. For multiple AMFs other than the current AMF, if the cell transition information includes a cell within the region, these multiple AMFs are selected as the future AMF. In OP333, AMF 7 transmits a handover pre-configuration request to the future AMF selected in OP332. The ID of UE 50, the pre-configuration ID, the cell transition information, and the PDU session ID of the handover target are also transmitted together with the handover pre-configuration request.

[0122] In OP334, the AMF 7 determines whether or not a handover pre-configuration request has been received from all future AMFs. If a handover pre-configuration request has been received from all future AMFs (OP334: YES), the process shown in FIG. 16 ends, and the process proceeds to OP35 in FIG. 14. The AMF 7 remains in a standby state until a handover pre-configuration request has been received from all future AMFs. (OP334:NO).

[0123] 17 is an example of a flowchart of a PDU session pre-configuration process when an AMF receives a PDU session pre-configuration request. In the process shown in FIG. 17, AMF 7 is the current AMF.

[0124] In operation OP341, the AMF 7 determines whether or not a PDU session pre-establishment request has been received from the NEF 3. If a PDU session pre-establishment request has been received (OP341: YES), the process proceeds to operation OP342. If a PDU session for the target application has not yet been established (OP341: NO), the process shown in Fig. 17 ends.

[0125] In OP342, AMF 7 selects a future SMF that will be responsible for the PDU session of the target application. AMF 7 may, for example, query the NRF for candidate SMFs according to the 3GPP standard, and select a future SMF from the list of candidate SMFs. In OP343, the AMF 7 sends a PDU session establishment request to the future SMF. The PDU session pre-configuration request also includes the ID of the UE 50, the pre-configuration ID, cell transition information, and flow identification information of the target application.

[0126] In OP344, AMF 7 determines whether or not a response to the PDU session pre-configuration request has been received from the future SMF. If a response to the PDU session pre-configuration request has been received from the future SMF (OP334: YES), processing proceeds to OP345. AMF 7 remains in a waiting state until a response to the PDU session pre-configuration request is received from the future SMF (OP334: NO).

[0127] In OP345, the AMF 7 stores the PDU session pre-configuration information in the configuration information storage unit 72. In OP346, the AMF 7 transmits a response to the PDU session pre-configuration request to the NEF 3. Thereafter, the processing shown in Fig. 17 ends.

[0128] Figure 18 is an example of a flowchart of the processing of the SMF 6 when a pre-configuration request is received. The processing shown in Figure 18 is repeatedly executed at a predetermined cycle. In OP41, the SMF 6 determines whether or not a pre-configuration request has been received from the AMF. If a pre-configuration request has been received from the AMF (OP41: YES), the processing proceeds to OP42. If a pre-configuration request has not been received from the AMF (OP41: NO), the processing proceeds to OP46.

[0129] The processing from OP42 to OP45 is processing when a handover pre-configuration request is received. In OP42, the SMF 6 determines whether or not to select a UPF. If it is determined that a UPF selection is to be performed (OP42: YES), the processing proceeds to OP43. If it is determined that a UPF selection is not to be performed (OP42: NO), the processing proceeds to OP44. In OP43, the SMF 6 selects a UPF. The SMF 6 queries the NRF for UPF candidates, for example, and selects a UPF from a list of candidate UPFs that includes in its service area the future cell included in the cell transition information.

[0130] For example, when the SMF 6 does not hold information about the PDU session to be handed over that is received together with the pre-configuration request, that is, when a session with the UPF that has established the PDU session to be handed over is not established, the SMF 6 determines to select a UPF (OP42: YES) and selects a UPF to establish the PDU session to be handed over. For example, if SMF 6 is selected as I-SMF (future SMF) by AMF 7 and receives a handover pre-configuration request from AMF 7, SMF 6 will not hold information about the PDU session to be handed over.

[0131] Furthermore, even when the SMF 6 holds information about the PDU session to be handed over that was received together with the pre-configuration request, it determines to select a UPF in the following cases: In a local breakout or redundant configuration, if the cell transition information includes a transition from a cell within the service area of ​​the I-UPF currently connected to the RAN to a cell outside the service area, the SMF 6 determines to select a UPF during handover from a cell within the service area of ​​the I-UPF (Intermediate UPF) currently connected to the RAN to a cell outside the service area (OP42: YES), and selects a new I-UPF (OP43).

[0132] For example, if the SMF 6 holds information about the PDU session to be handed over received together with the pre-configuration request, and the cell transition information does not include a transition from a cell within the service area of ​​the UPF currently connected to the RAN to a cell outside the service area, it determines not to perform UPF selection (OP42: NO).

[0133] In OP44, the SMF 6 stores handover pre-configuration information in the configuration information storage unit 62, such as information about the UPF selected in OP43 and the target RAN ID when the UPE is selected. In OP45, the SMF 6 transmits a response to the handover pre-configuration request to the AMF. After that, the process shown in FIG. 18 ends.

[0134] In OP46, the SMF 6 determines whether or not a PDU session pre-configuration request has been received from the AMF. If a PDU session pre-configuration request has been received (OP46: YES), the process proceeds to OP47. If a PDU session pre-configuration request has not been received (OP46: NO), the process shown in Figure 18 ends.

[0135] The OP47 to OP49 processes are performed when a PDU session pre-establishment request is received. In OP47, the SMF 6 selects a UPF to allocate a PDU session that will be newly requested to be established in the future, and acquires policy rules including QoS information. In accordance with the 3GPP standard, the SMF 6 selects a UPF whose service area includes the cell included in the cell transition information. If the target application is to be transferred to an edge server, the SMF 6 connects, for example, to the UL CL (Uplink Classifier) ​​and local DN. In OP48, the SMF 6 stores information about the selected UPF as PDU session pre-configuration information in the configuration information storage unit 62. In OP49, the SMF 6 transmits a response to the PDU session pre-configuration request to the AMF. Then, the process shown in FIG. 18 ends.

[0136] 19 is an example of a flowchart of a handover process or a PDU session establishment process of an NF. In the first embodiment, the NFs that are the subjects of the process of FIG. 19 are, for example, the AMF and the SMF.

[0137] In OP51, the NF determines whether or not a handover request or a PDU session request has been received. If a handover request or a PDU session request has been received (OP51: YES), the process proceeds to OP52. If a handover request or a PDU session request has not been received (OP51: NO), the process proceeds to OP53. 19 is completed. If a handover request is received, the process from OP52 onwards is for handover. If a PDU session request is received, the process from OP52 onwards is for PDU session.

[0138] In OP52, the NF determines whether or not there is corresponding information in the pre-configured information. When a handover request is received, the NF determines whether or not there is corresponding information in the handover pre-configuration information. When a PDU session establishment request is received, the NF determines whether or not there is corresponding information in the PDU session pre-configuration information. If there is corresponding information in the pre-configured information (OP52: YES), the process proceeds to OP53. If there is no corresponding information in the pre-configured information (OP52: NO), the process proceeds to OP6. In OP56, the NF performs the process for when a handover request or PDU session request is received as specified in the 3GPP standard. Then, the process shown in FIG. 19 ends.

[0139] In OP53, the NF reflects pre-configured information corresponding to the handover request or PDU session request in the context information. In OP54, an appropriate request corresponding to the handover request or PDU session request is sent to the selected NF included in the pre-configured information. In OP55, the NF performs subsequent processing in the handover procedure or PDU session establishment procedure specified in the 3GPP standard. Thereafter, the processing shown in Figure 19 ends. Note that the processing shown in Figures 12 to 19 is an example and can be modified as appropriate depending on the embodiment.

[0140] Fig. 20 shows an example of a processing sequence from when path information is transmitted from the UE 50 to when a pre-configuration request is transmitted to the current AMF. In the example shown in Fig. 20, it is assumed that the UE 50 has already registered in the region of the current AMF 7A and that at least one PDU session has already been established under the management of the current SMF 6A.

[0141] In S11, when a route is set in a car navigation system by a vehicle occupant, for example, the UE 50 transmits route information and information about the application currently communicating to the AF 1. In S12, when the AF 1 receives the route information and the like from the UE 50 (OP11: YES in FIG. 12), the AF 1 transmits a QoS registration request to the NEF 3 to request the NEF 10 to set QoS for the application to be pre-configured (OP12 in FIG. 12). The QoS registration request is transmitted, for example, by using an Nnef_AF_Request_QoS_Create request message. Identification information of the UE 50, identification information of the flow of the application to be pre-configured, and QoS setting information are also transmitted together with the Nnef_AF_Request_QoS_Create request message. However, the Nnef_AF_Request_QoS_Create request message uses a Generic Public Subscription Identifier (GPSI) as identification information of the UE 50.

[0142] In S13, when the NEF 3 receives the Nnef_AF_Request_QoS_Create request message, it acquires the SUPI corresponding to the GPSI of the UE 50 from the UDM 2. Thereafter, the AF 1 uses the SUPI as identification information of the UE 50.

[0143] In S14, the NEF 3 sends a Nudr_DM_Create request to the UDR 4 requesting registration of QoS information for the UE 50. As a result, the QoS information of the target application for the UE 50 is registered in the UDR 4. The QoS information is registered as "Policy Data." A response is sent from the UDR 4 to the NEF 3. In S15, upon receiving the response from the UDR 4, the NEF 3 sends a Nudr_AF_Request_QoS_Create response message to the AF 1. AF 1 The Nnef_AF_Request_QoS_Create response message is received (OP13 in FIG. 12: YES).

[0144] In S16, since the policy data for the UE 50 has been updated in S14, the UDR 4 transmits a Nudr_DM_Notify message notifying the PCF 5 of the update of the policy data and the update contents (flow identification information and QoS information of the target application). The PCF 5 receives the QoS information of the target application for the UE 50 via the Nudr_DM_Notify message.

[0145] In S17, the PCF 5 identifies the current SMF 6A that manages the PDU session of the target application and initiates a procedure for changing the SM policy association with the current SMF 6A. Through the procedure for changing the SM policy association, the PCF 5 notifies the current SMF 6A of the QoS information of the target application for the UE 50.

[0146] At S18, the current SMF 6A initiates an N4 session modification procedure with the UPF to which the PDU session of the target application is assigned, and notifies the UE 50 of the QoS information of the target application through this procedure.

[0147] In S19, the current SMF 6A sends the QoS information of the target application for the UE 50 to the current RAN together with a Namf_Communication_N1N2MessageTransfer message to the current AMF 7A. Upon receiving the Namf_Communication_N1N2MessageTransfer message, the current SMF 6A transfers the QoS information of the target application for the UE 50 to the current RAN using an N2 message. As a result, the QoS information of the target application for the UE 50 is reflected in the PCF 5 currently in charge of the PDU session of the target application, the current SMF 6A, and the current RAN.

[0148] In S21, the AF 1 sends a pre-configuration request to the NEF 3. Along with the pre-configuration request, a pre-configuration ID, identification information of the UE 50, route information, flow identification information of the target application, and information indicating whether the UE 50 has already established a PDU session for the target application are also sent (OP14 in FIG. 12). The pre-configuration ID is used to identify the pre-configuration request. The NEF 3 receives the pre-configuration request (OP21: YES in FIG. 13).

[0149] In S22, the NEF 3 converts the route information received together with the pre-configuration request into cell transition information (OP22 in FIG. 13). In S23, the NEF 3 identifies the current AMF 7A to be configured (OP23 in FIG. 13). In S24, the NEF 3 transmits a handover pre-configuration request to the current AMF 7A (OP24 in FIG. 13). The pre-configuration ID, identification information of the UE 50, and cell transition information are transmitted together with the handover pre-configuration request.

[0150] If a PDU session for the target application has not been established, the process of S25 is executed. In S25, the NEF 3 determines that the UE 50 has not established a PDU session for the target application (OP25: NO in FIG. 13), and therefore the current AMF 13, the UE 50 transmits a PDU session pre-configuration request to the UE 50 (OP26 in FIG. 13). The UE 50 transmits the pre-configuration ID, the identification information of the UE 50, the cell transition information, and the flow identification information of the target application together with the PDU session pre-configuration request.

[0151] FIG. 21 is a diagram showing an example of a handover pre-configuration sequence in scenario #1. Scenario #1 is in the current AMF 7A region and in the current This is a scenario in which the route of UE 50 falls within the service area of ​​SMF 6 A. Therefore, one or more cells included in the cell transition information are cells that are included in the region of current AMF 7 A and also included in the service area of ​​current SMF 6 A. Also, in Fig. 21, it is assumed that the cell transition information, i.e., the planned movement route of UE 50, does not include movement from a cell within the service area of ​​the UPF currently connected to the RAN to a cell outside the service area.

[0152] The sequence shown in Fig. 21 is a continuation of the sequence shown in Fig. 20. S100 is the same process as S24 in Fig. 20. In S100, the current AMF 7A receives a preconfiguration request, a preconfiguration ID, identification information of the UE 50, and cell transition information from the NEF 3 (OP31: YES in Fig. 14).

[0153] In scenario #1, no handover outside the region of the current AMF 7A occurs, so the current AMF 7A performs intra-region handover pre-configuration processing (OP32 in FIG. 14) and PDU session pre-configuration processing (FIG. 17). The sequence from S111 to S115 is the handover pre-configuration sequence within the current region in scenario #1.

[0154] In S111, the current AMF 7A identifies the current SMF 6A. The current AMF 7A holds information about each established PDU session in the UE context for the UE 50. The information about the PDU session held by the AMF 7A includes the ID of the SMF that manages the PDU session. The current AMF 7A identifies the SMF included in the information about the PDU session as the current SMF 6A. In the example shown in FIG. 21, it is assumed that one SMF is identified as the current SMF 6A. However, this is not limited to this, and there may be multiple SMFs identified as the current SMF 6A.

[0155] In S112, the current AMF 7A transmits a handover pre-configuration request to the current SMF 6A (OP321: YES, OP322 in FIG. 15). Along with the handover pre-configuration request, for example, the ID of the UE 50, the pre-configuration ID, cell transition information, and the ID of the PDU session to be handed over are also transmitted.

[0156] A handover pre-configuration request is, for example, a Nsmf_PDUSession_UpdateSMContext request. For example, information indicating that it is a handover pre-configuration request is included in the Nsmf_PDUSession_UpdateSMContext request message. The information indicating that the request is a handover pre-configuration request may be, for example, a keyword, a code, or a flag. The Nsmf_PDUSession_UpdateSMContext request message may include, as a format, a target RAN ID and a PDU session ID to be handed over. Cell transition information may be included in the Nsmf_PDUSession_UpdateSMContext request message as the target RAN. The Nsmf_PDUSession_UpdateSMContext request message also includes an SM context ID that identifies the SM association with the current SMF 6A. The SM context ID is included in information about the PDU session in the UE context for the UE 50 in the current AMF 7A. The message used to send the handover pre-configuration request is the Nsmf_PDUSession_UpdateSMContext The current SMF 6A receives a handover pre-configuration request (OP41 in FIG. 18: YES), and is not limited to a request message.

[0157] In S113, the current SMF 6A holds information regarding the PDU session to be handed over, and in scenario #1, the cell transition information does not include a transition from a cell within the service area of ​​the UPF currently connected to the RAN to a cell outside the service area, so the current SMF 6A does not select a UPF for the PDU session to be handed over (OP42: NO in Figure 18).

[0158] In S114, the current SMF 6A stores the information received in S112 and the execution result of the process in S113 as handover pre-configuration information together with the pre-configuration ID (OP44 in FIG. 18). For example, for each active PDU session, the current SMF 6A stores the PDU session ID, the SM context ID included in the Nsmf_PDUSession_UpdateSMContext request message received in S112, and the SM context ID included in the Nsmf_PDUSession_UpdateSMContext request message received in S112. The ID of the current AMF 7A corresponding to the context ID is stored as the target RAN ID in the configuration information storage unit 62 as handover pre-configuration information for the UE 50, together with one or more cell IDs and pre-configured IDs included in the cell transition information (see Figure 11).

[0159] In S115, the current SMF 6A transmits a response to the handover pre-configuration request (OP45 in FIG. 18). Along with the response to the handover pre-configuration request, the pre-configuration ID, the target RAN ID(s) (future cell included in the cell transition information) in which the handover pre-configuration information is stored, and the PDU session ID are also transmitted. The response to the handover pre-configuration request is transmitted, for example, using an Nsmf_PDUSession_UpdateSMContext response message, including information indicating that it is a response to the handover pre-configuration request. The Nsmf_PDUSession_UpdateSMContext response message also includes the SM context ID. The current AMF 7A receives the response to the handover pre-configuration request (OP323: YES in FIG. 15).

[0160] In S116, the current AMF 7A stores the information received in S100 and S115 together with the preset ID as handover preset information (OP36 in FIG. 14). For example, the current AMF 7A stores the PDU session ID for each PDU session included in the Nsmf_PDUSession_UpdateSMContext response message received in S115. The U session ID and the Nsmf_PDUSession_UpdateSMContext record received in S115 The SM context ID included in the response message and the ID of the current SMF 6A corresponding to the SM context ID are stored in the configuration information storage unit 72 as handover pre-configuration information for the UE 50, together with the cell ID and pre-configuration ID included in the cell transition information as the target RAN ID (see Figure 10).

[0161] In S117, the current AMF 7A sends a response to the handover pre-configuration request to the NEF 3 (OP37 in FIG. 14). The ID of the UE 50 and the pre-configuration ID are also sent together with the response to the handover pre-configuration request. The NEF 3 receives the response to the pre-configuration request (OP27: YES in FIG. 13). The handover pre-configuration sequence in FIG. 21 completes the handover pre-configuration in the 5CG 10 in scenario #1.

[0162] Figure 22 shows the PDU session pre-establishment sequence in scenario #1. The PDU session pre-establishment sequence is executed when the current AMF 7A receives a PDU session pre-establishment request from the NEF 3 (Figure 17, OP341: YES).

[0163] In S121, the current AMF 7A will be in the current region in the future. When a PDU session establishment request for a target application is received in the AMF 7A, the AMF 7A selects an SMF 6B to which management of the PDU session is assigned (OP342 in FIG. 17). For example, the AMF 7A queries the NRF to obtain a list of candidate SMFs, and selects a future SMF 6B from the list based on cell transition information.

[0164] In S122, the current AMF 7A sends a PDU session pre-configuration request to the selected SMF 6B (OP343 in FIG. 17). The PDU session pre-configuration request may also include identification information of the UE 50, a pre-configuration ID, and cell transition information. The PDU session pre-configuration request may be, for example, a Nsmf_PDUSession_CreateSMContext request message containing the PDU session pre-configuration request. The information indicating that it is a PDU session pre-configuration request is, for example, a keyword, a code, or a flag. In addition to the above information, the Nsmf_PDUSession_CreateSMContext request message also includes U The SMF 6B receives the PDU session pre-establishment request (OP46: YES in Fig. 18) and creates an SM context for the received Nsmf_PDUSession_CreateSMContext request message. Issue an ID.

[0165] In S123, the SMF 6B sends a Nudm_SDM_Get message to the UDM 2 to request the subscribe data of the UE 50. The processing of S123 is processing for acquiring information used for UPF selection and policy data acquisition (OP47 in FIG. 18). In S124, the UDM 2 sends the subscribe data of the UE 50 to the SMF 6B together with a Nudm_SDM_Get response message. The SMF 6B receives the subscribe data of the UE 50. The subscribe data of the UE 50 acquired in S124 is session management subscribe data. The session management subscribe data includes, for example, authentication information and the like.

[0166] In S125, the SMF 6B selects a PCF 5 that will manage the policy for the PDU session to be established in response to a new PDU session establishment request that will occur in the future. The SMF 6B, for example, queries the NRF for candidate PCFs and selects the PCF 5 from among the candidate PCFs. The PCF 5 may be the same PCF as that of the existing PDU session.

[0167] In S126, SMF 6B sends an Npcf_SMPolicyControl_Create request to PCF 5. Npcf_SMPolicyControl_Create request message to request the creation of a new SM policy association with the PCF 5 for the UE 50. The message includes, as part of the information, the identification information of the UE 50, a PDU session ID, etc. However, in FIG. 22, a request to establish a PDU session accompanying the start of communication of the target application has not yet occurred, so the PDU session ID remains undetermined or uses a value indicating that it has been pre-set. When the PCF 5 receives the Npcf_SMPolicyControl_Create request message, it An SM policy association is created and an SM policy association ID is issued.

[0168] In S127, the PCF 5 sends a Nudr_DM_Query request message to the UDR 4 requesting policy information for the UE 50. In S128, the UDR 4 , the PCF 5 receives the policy information of the UE 50 together with the Nudr_DM_Query response message. The policy information of the UE 50 also includes the QoS information of the target application registered in the UDR 4 in S14 of FIG. 20. The PCF 5 sends the Nudr_DM_Query The policy information of the UE 50 is received together with the response message, and is stored in association with the SM policy association ID with the SMF 6B.

[0169] In S129, PCF 5 sends the Npcf_SMPolicyControl_Create response to SMF 6B. The Npcf_SMPolicyControl_Create response contains, for example, PCF 5 and The response includes the SM policy association ID of the UE 50, policy information about the UE 50, etc. The policy information about the UE 50 includes, as one piece of information, a default PCC rule used for subsequent UPF selection, QoS information of the target application, etc. The SMF 6B receives the Npcf_SMPolicyControl_Create response.

[0170] In S130, the SMF 6B selects a UPF to which a PDU session for the target application will be assigned when a PDU session establishment request for the target application is received in the future based on the default PCC rule. At this time, if the target application is a target of edge computing, for example, a UPF operating as a UL CL and a UPF operating as a PSA may be selected as the UPF. Information indicating that the target application is a target of edge computing is included in the policy information for the UE 50 received in S129.

[0171] In S131, the SMF 6B sends an Npcf_SMPolicyControl_Update request message to the PCF 5, requesting the creation of a PCC rule for the target application. The Npcf_SMPolicyControl_Update request message includes, for example, an SM association ID as one piece of information. In S132, the PCF 5 receives the Npcf_SMPolicyControl_Update request message and updates the SM association ID for the UE 50 based on the policy information. At this time, a PCC rule for the target application is also created. In S133, the PCF 5 sends the Npcf_SMPolicyControl_Update record to the SMF 6B. Sends a Npcf_SMPolicyControl_Update response message. The Npcf_SMPolicyControl_Update contains, for example, the SM association ID and the PCC rules for the target application. A response message is received, which completes the PDU session pre-establishment process in SMF 6B (OP47 in Figure 18).

[0172] In S134, the SMF 6B stores information about the PCF 5 selected in S125, information about the UPF selected in S130, and information received in S122, S124, S129, and S133 together with a preset ID as PDU session preset information (OP48 in FIG. 18). For example, the SMF 6B stores, for each target application, QoS flow identification information (flow identification information of the target application) and the Nsmf_PDUSession_CreateSMContext request message received in S122. The issued SM context ID, the ID of the current AMF 7A corresponding to the SM context, and the Npcf_SMPolicyControl_Update response received in S131 The SM policy association ID, the ID of the selected PCF 5, the ID of the selected UPF, and the QoS information included in the response message are stored in the configuration information storage unit 62 as PDU session pre-configuration information for the UE 50, together with the pre-configuration ID (see Figure 11).

[0173] In S135, the SMF 6B sends a response to the PDU session pre-configuration request to the current AMF 7A (OP49 in Figure 18). Along with the response to the PDU session pre-configuration request, the UE identification information and the pre-configuration ID are also sent. The response to the PDU session pre-configuration request may be, for example, a Nsmf_PDUSession_CreateSMContext response message containing the PDU session pre-configuration request. The Nsmf_PDUSession_CreateSMContext response message includes information indicating that it is a response to a request. For example, the SMF Contains the SM context ID issued by 6B. 7A receives a response to the PDU session pre-setting request (OP344: YES in Figure 17).

[0174] In S136, the current AMF 7A stores information about the SMF 6B selected in S121 and the information received in S100 and S135 of Fig. 21 together with the preset ID as PDU session preset information (OP345 in Fig. 17). For example, the current AMF 7A stores, for each target application, QoS flow identification information (flow identification information of the target application), the ID of the selected SMF 6B, and the QoS flow identification information included in the Nsmf_PDUSession_CreateSMContext response message received in S135. The SM context ID and the preset ID are stored in the setting information storage unit 72 as PDU session preset information for the UE 50 (see FIG. 10).

[0175] In S137, the current AMF 7A sends a response to the pre-configuration request to the NEF 3 (OP346 in FIG. 17). The NEF 3 receives the response to the pre-configuration request (OP27: YES in FIG. 13). The PDU session pre-configuration sequence in FIG. 22 completes the PDU session pre-configuration within the 5CG 10 in Scenario #1.

[0176] Fig. 23 is a diagram showing an example of a handover sequence in scenario #1. Fig. 23 is based on the premise that the pre-setting sequence from Fig. 20 to Fig. 22 has been completed in 5CG 10. It is also assumed that UE 50 is moving on a route based on the route information notified in S11 of Fig. 20.

[0177] When UE 50 moves near the boundary between the source RAN and the target RAN, it detects a handover and transmits a handover request, which is received by the source RAN and a handover preparation process is performed between the source RAN and the target RAN (see, for example, steps 1-8 in TS38.300 Fig. 9.2.3.2.1-1).

[0178] In S151, the target RAN transmits an N2 Path Switch request message including a handover request to the current AMF 7A. The N2 Path Switch request message includes, as one piece of information, identification information of the UE 50, the target RAN The current AMF 7A sends an N2 Path Switch Request message containing the handover request, including the ID and the list of PDU sessions to be handed over. Receive.

[0179] In S152, the current AMF 7A receives the identification information of the UE 50, the target RAN I, and the N2 Path Switch request message received in S151. D. Search for handover pre-configuration information using the ID of the PDU session to be handed over as a key, and detect the handover pre-configuration information stored in S116 of Figure 21 as the search result.

[0180] In S153, the current AMF 7A sends a Nsmf_PDUSession_UpdateSMContext request message to the SMF 6A included in the handover pre-configuration information detected in S152. The Nsmf_PDUSession_UpdateSMContext request message includes identification information of the UE 50, a handover request, a target RAN ID, and the SM context ID and PDU session ID included in the handover pre-configuration information detected in S152. The pre-configuration ID corresponding to the handover pre-configuration information detected in S152 is also sent together with the request message. Receives a request message.

[0181] In S154, the SMF 6A searches for handover pre-configuration information using the identification information of the UE 50, the pre-configuration ID, the target RAN ID, and the PDU session ID included in the Nsmf_PDUSession_UpdateSMContext request message received in S153 as keys, and detects the handover pre-configuration information stored in S114 of Fig. 21 as the search result. In the example shown in Fig. 23, UPF selection was not performed in S113 of Fig. 21, and the detected handover pre-configuration information does not include information on the selected UPF, so in Fig. 23, the SMF 6A does not determine whether to perform UPF selection and does not select a UPF.

[0182] In S155, the SMF 6A performs the N4 session change process, for example, in step 3-5 of Fig. 4.9.1.2.2-1 of 3GPP TS23.502, for the selected UPF based on the handover pre-configuration information detected in S154, thereby switching the PDU session established between the source RAN and the UPF to a PDU session between the target RAN and the UPF.

[0183] In S156, the SMF 6A sends an Nsmf_PDUSession_UpdateSMContext response message to the current AMF 7A, which includes information indicating the success of the handover. The current AMF 7A uses the Nsmf_PDUSession_UpdateSMContext response message. At S157, the current AMF 7A receives an Ack message for the N2 Path Switch request containing information indicating the successful handover to the target RAN. The target RAN then notifies the source RAN and the UE 50 that the handover has been successful.

[0184] In the handover sequence in Scenario #1 shown in Figure 23, since the SMF 6A has already determined in the pre-configuration process that it will not select a UPF to allocate the PDU session to be handed over, it does not determine whether to select a UPF in S154. This reduces the time required for handover and further shortens the time of communication interruption due to handover.

[0185] In addition, in scenario #1, if a local breakout is configured for one of the established PDU sessions, for example, by edge computing, and a cell outside the service area of ​​the I-UPF operating as UL CL is included in the cell transition information (OP42 in FIG. 18: YES), the current SMF 6A selects a new I-UPF and PSA (PDU Session Anchor) in pre-configuration S113 in FIG. 21 (OP43 in FIG. 18). In this case, when the UE 50 performs a handover from a cell within the service area of ​​the I-UPF to a cell outside the service area of ​​the I-UPF, the current Since the SMF 6A holds handover pre-configuration information including information about the selected I-UPF, the SMF 6A performs a session establishment process for handover between the selected I-UPF included in the handover pre-configuration information and the PSA without selecting a new I-UPF. This reduces the time required for handover, even when local breakout is configured, and further reduces the time for communication interruption due to handover.

[0186] Fig. 24 is a diagram showing an example of a sequence for establishing a PDU session for an application that is a target of pre-configuration in Scenario #1. The premise of the example in Fig. 24 is the same as the example in Fig. 23. In S171, UE 50 transmits a PDU session establishment request for an application that is a target of pre-configuration. The PDU session establishment request includes, as one piece of information, identification information of UE 50 and a PDU session ID. The current AMF 7A receives the PDU session establishment request from UE 50.

[0187] In S172, the current AMF 7A searches for PDU session pre-configuration information using the identification information of the UE 50 included in the PDU session establishment request received in S171 as a key, and detects the handover pre-configuration information stored in S136 of Fig. 22 as the search result. Since the handover pre-configuration information includes information about the SMF 6B already selected in S121 of Fig. 22, the AMF 7A does not perform SMF selection in Fig. 24.

[0188] In S173, the current AMF 7A sends the Nsmf_PDUSession_CreateSMContext link to the SMF 6B included in the PDU session pre-configuration information detected in S172. Send a request message. Nsmf_PDUSession_CreateSMContext request message The message includes a PDU session establishment request, the identification information of the UE 50 and the PDU session ID included in the PDU session establishment request received in S171, and the SM context ID included in the PDU session pre-configuration information detected in S172. The preset ID corresponding to the PDU session preset information detected in S172 is also sent. Believe.

[0189] In S174, the SMF 6B receives the identification information of the UE 50, the preconfigured ID, and the 22, the SMF 6B searches for PDU session pre-configuration information using the SM context ID as a key, and detects the PDU session pre-configuration information stored in S134 of Fig. 22 as a search result. The PDU session pre-configuration information includes, for example, subscription data for UE 50 acquired in S123 and S124 of Fig. 22, information on the PCF selected in S125 of Fig. 22, information on the UPF selected in S130 of Fig. 22, the SM policy association ID received in S129, and flow identification information and QoS information of the target application received in S133. Therefore, in Fig. 24, the SMF 6B does not acquire subscription data for UE 50. The SMF 6B reflects the PDU session pre-configuration information in the context information of UE 50.

[0190] In S175, the SMF 6B sends a Nsmf_PDUSession_CreateSMContext response message to the current AMF 7A. The Nsmf_PDUSession_CreateSMContext response message includes an SM context ID as one piece of information. The pre-configured ID is also sent together with the Nsmf_PDUSession_CreateSMContext response message. The current AMF 7A uses the Nsmf_PDUSession_CreateSMContext response. The current AMF 7A may also reflect the PDU session advance information corresponding to the received SM context ID in the context information of the UE 50.

[0191] In S176, secondary authentication is performed for the UE 50 (see 4.3.2.2.1 step 6 of TS23.502). In S177, since the PDU session pre-configuration information includes information on the PCF already selected in S125 of Fig. 22, the SM policy association ID received in S129, the flow identification information and QoS information of the target application received in S133, etc., the SMF 6B does not select a PCF, does not establish an SM association with the PCF 5, does not acquire QoS information from the PCF 5, etc.

[0192] In S178, since the PDU session pre-configuration information includes information about the UPF already selected in S130 of FIG. 22, the SMF 6B does not select a UPF.

[0193] In S179, the SMF 6B performs a procedure to change the SM policy association with the selected PCF 5 included in the PDU session pre-configuration information and notifies the PDU session ID. As a result, the PCF 5 obtains the PDU session ID corresponding to the SM policy association ID issued in S131 of Fig. 22 and updates the SM policy association information. In S180, the SMF 6B performs a procedure to establish an N4 session with the selected UPF included in the PDU session pre-configuration information.

[0194] In S181, the SMF 6B transmits a Namf_Communication_N1N2MessageTransfer message to the current AMF 7A. The Namf_Communication_N1N2MessageTransfer message includes, as part of its information, an acceptance of the establishment of the PDU session, flow identification information and QoS information of the target application included in the PDU session pre-configuration information, etc. The current AMF 7A receives the Namf_Communication_N1N2MessageTransfer message and notifies, for example, the RAN and UE 50 of the acceptance of the establishment of the PDU session, and the flow identification information and QoS information of the target application.

[0195] In the sequence of establishing a PDU session in Scenario #1 shown in Fig. 24, in the pre-configuration process, the current AMF 7A has already selected the SMF 6B that will manage a new PDU session that will be generated in the future, and the SMF 6B has already acquired subscription data for the UE 50, selected a PCF and a UPF, and acquired flow identification information and QoS information for the target application from the PCF. As a result, in the sequence shown in Fig. 24, the SMF selection process in S172, the acquisition of information from the UDM in S174, the selection of a PCF and acquisition of a policy in S177, and the UPF selection in S178 are not performed. This can shorten the time required for the procedure of establishing a PDU session, and the UE 50 can more quickly perform communication for the target application with appropriate QoS applied.

[0196] FIG. 25 is a diagram showing an example of a handover pre-configuration sequence in scenario #2. Scenario #2 is a scenario in which the route of UE 50 does not fit within the region of the current AMF 7A, but extends to the region of another AMF, resulting in AMF replacement. On the other hand, in scenario #2, the route of UE 50 is Therefore, the cell transition information includes the cells included in the region of the current AMF 7A and the cells included in the region of the current AMF 6A. 25, the cell transition information includes a cell that is not included in the region of SMF 7A. Furthermore, one or more cells included in the cell transition information are cells that are included in the service area of ​​current SMF 6A. Furthermore, in FIG. 25, it is assumed that the cell transition information, i.e., the planned movement route of UE 50, does not include movement from a cell in the service area of ​​the UPF currently connected to the RAN to a cell outside the service area.

[0197] The sequence shown in Fig. 25 is a continuation of the sequence shown in Fig. 20. S200 is the same process as S24 in Fig. 20, and the current AMF 7A receives a handover pre-configuration request, identification information of the UE 50, a pre-configured ID, and cell transition information from the NEF 3 (OP31: YES in Fig. 14).

[0198] In Scenario #2, the cell transition information includes a cell outside the region of the current AMF 7A, so the current AMF 7A uses the intra-region handover pre-configuration. 14) and out-of-region handover pre-setting processing (OP33 in FIG. 14).

[0199] In S211, for handover between cells within the region of the current AMF 7A included in the cell transition information, a handover pre-configuration sequence within the region of the current AMF 7A is executed, similar to S111-S116 in Scenario #1.

[0200] The sequence from S212 to S219 is the current This is a handover pre-configuration sequence for handover from a cell within the region of the AMF 7A to a cell outside the region of the current AMF 7A and handover between cells outside the region of the current AMF 7A, i.e., for handover outside the region of the current AMF 7A. In S212, the current AMF 7A selects a future AMF 7B (OP332 in FIG. 16). The AMF 7A, for example, queries the NRF to acquire future AMF candidates, and selects a future AMF 7B from the candidates based on the cell transition information. An AMF whose region includes a cell outside the region of the current AMF 7A included in the cell transition information is selected as the future AMF 7B.

[0201] In S213, the current AMF 7A transmits a handover pre-configuration request to the future AMF 7B (OP333 in FIG. 16). A pre-configuration ID and cell transition information are also transmitted together with the handover pre-configuration request. The handover pre-configuration request is transmitted, for example, in a Namf_Communication_CreateUEContext request message including information indicating that it is a handover pre-configuration request. The Namf_Communication_CreateUEContext request message includes, as part of its information, a UE context for the UE 50 held by the current AMF 7A, a target cell ID, and the like. The target cell ID in the Namf_Communication_CreateUEContext request message may include, as the target cell, an ID of a cell outside the region of the current AMF 7A in the cell transition information. The UE context for the UE 50 also includes, for example, IDs of active PDU sessions, an SM context ID for each PDU session, and the ID of the SMF responsible for managing the PDU session. The future AMF 7B receives the handover pre-configuration request (OP38A in FIG. 14: YES).

[0202] In S214, the future AMF 7B transmits a handover pre-configuration request to the SMF 6A included in the Namf_Communication_CreateUEContext request message received in S213 (OP38B in FIG. 14, OP322 in FIG. 15). The pre-configuration ID and cell transition information may be transmitted together with the handover pre-configuration request. The handover pre-configuration request may include, for example, a Namf_PDUSession_UpdateSMContext request message containing information indicating that the handover pre-configuration request is a handover pre-configuration request. The Nsmf_PDUSession_UpdateSMContext request message contains the information As one of the pieces of information, the ID of the UE 50, the target cell ID, the SM context ID included in the Namf_Communication_CreateUEContext request message, and the ID of future AMF 7B as the target AMF are included. If the Namf_Communication_CreateUEContext request message received in S213 contains IDs of multiple active PDU sessions, the Nsmf_PDUSession_UpdateSMContext request message is sent to the corresponding SMF for each PDU session. The SMF 6A receives the handover pre-configuration request (see Figure 18). OP41:YES).

[0203] In S215, SMF 6A holds information about the PDU session to be handed over, and in scenario #2, the cell transition information does not include a transition from a cell within the service area of ​​the UPF currently connected to the RAN to a cell outside that service area, so no UPF is selected for the PDU session to be handed over (OP42: NO in Figure 18).

[0204] In S216, the SMF 6A stores the information received in S214 as handover pre-configuration information together with the pre-configuration ID received in S214 (OP44 in FIG. 18). For example, the SMF 6A stores the PDU session ID and the Nsmf_PDUSession_UpdateSMContext request received in S214 for each active PDU session. The SM context ID included in the target message and the ID of the future AMF 7B corresponding to the SM context are stored as the target RAN ID in the configuration information storage unit 62 as handover pre-configuration information for the UE 50, together with the cell ID and pre-configuration ID in the region of the future AMF 7B included in the cell transition information (see Figure 11).

[0205] In S217, the SMF 6A sends a response to the handover pre-configuration request to the future AMF 7B (OP45 in FIG. 18). The response to the handover pre-configuration request also sends a pre-configuration ID. The response to the handover pre-configuration request is, for example, an Nsmf_PDUSession_UpdateSMContext record. The response message is sent with information indicating that it is a response to a handover pre-configuration request. The message includes, as part of the information, the SM context ID, the ID of the PDU session for which handover pre-configuration has been performed, etc. The future AMF 7B receives a response to the handover pre-configuration request (OP323: YES in FIG. 15).

[0206] In S218, the future AMF 7B stores the information received in S213 and S217 together with the preset ID as handover preset information (OP38C in FIG. 14). For example, the future AMF 7B stores the P DU session ID and Nsmf_PDUSession_UpdateSMContext received in S217 The SM context ID included in the response message and the ID of the SMF 6A corresponding to the SM context ID are stored in the configuration information storage unit 72 as handover pre-configuration information for the UE 50, together with the ID of the cell in the region of the future AMF 7B included in the cell transition information as the target RAN ID and the pre-configuration ID (see FIG. 10).

[0207] In S219, the future AMF 7B transmits a response to the handover pre-configuration request to the current AMF 7A (OP38D in FIG. 14). The pre-configuration ID is also transmitted together with the response to the handover pre-configuration request. The response to the handover pre-configuration request is transmitted, for example, in a Namf_Communication_CreateUEContext response message, including information indicating that it is a response to the handover pre-configuration request. The Namf_Communication_CreateUEContext response message includes, as one piece of information, the ID of the future AMF 7B as the target AMF, for example. The current AMF 7A receives the response to the handover pre-configuration request (OP334: YES in FIG. 16).

[0208] In S220, the current AMF 7A stores the information received in S219 together with the preset ID as handover preset information, and information about the future AMF 7B selected in S212 (OP36 in FIG. 14). For example, the current AMF 7A stores the PDU session ID for each PDU session included in the Nsmf_PDUSession_UpdateSMContext response message received in S219. ID and the Nsmf_PDUSession_UpdateSMContext response message received in S115 The SM context ID included in the message, the ID of the current SMF 6A corresponding to the SM context ID, and the ID of the future AMF 7B as the target AMF ID selected in S212 are stored in the configuration information storage unit 72 as handover pre-configuration information for the UE 50, together with the ID and pre-configuration ID of the cell within the region of the future AMF 7B included in the cell transition information as the target RAN ID (see Figure 10).

[0209] In S221, the current AMF 7A transmits a response to the handover pre-configuration request to the NEF 3 (OP37 in FIG. 14). The NEF 3 receives the response to the handover pre-configuration request (OP27 in FIG. 13: YES).

[0210] If a PDU session for the application to be pre-configured has not already been established, the PDU session pre-configuration sequence is also executed in scenario #2. The PDU session pre-configuration sequence in scenario #2 is the same as the PDU session pre-configuration sequence in scenario #1 shown in Figure 22.

[0211] FIG. 26 is a diagram showing an example of a handover sequence in scenario #2. The premise of FIG. 26 is the same as that of FIG. 23. In FIG. 26, UE 50 is connected to the current The following describes a handover sequence when moving from a cell in the region of AMF 7A to a cell in the region of future AMF 7B. Therefore, in Figure 26, the target RAN is a cell in the region of future AMF 7B to which UE 50 transitions from a cell in the region of current AMF 7A. In Figure 26, the current AMF 7A in Figure 25 is referred to as the source AMF 7A, and the future AMF 7B is referred to as the target AMF 7B.

[0212] In S251, the source RAN determines whether to perform a handover based on the field strength of the received signal from the source RAN and the field strength from the target RAN, which are included in a measurement report from the UE 50, and transmits a Handover Required message to the source AMF 7A. The Handover Required message includes, as part of its information, identification information of the UE 50 and the target RAN ID. The source AMF 7A receives the Handover Required message from the source RAN.

[0213] In S252, the source AMF 7A searches for handover preset information in the configuration information storage unit 72 using the identification information of the UE 50 and the target RAN ID included in the Handover Required message as keys, and detects, for example, the handover preset information stored in S220 of Fig. 25 as the corresponding handover preset information. The detected handover preset information includes the PDU session ID and the ID of the selected target AMF 7B (see Fig. 10). Therefore, in S252, the source AMF 7A does not select a target AMF.

[0214] In S253, the source AMF 7A sends a Namf_Communication_CreateUEContext request message including information indicating a handover request to the target AMF 7B. The Namf_Communication_CreateUEContext request message includes, as part of the information, a UE context for the UE 50 held by the source AMF 7A, a target RAN ID, etc. In the example shown in FIG. 26, the target RAN ID is the ID of a cell in the region of the future AMF 7B to which the UE 50 will transition from a cell in the region of the current AMF 7A. The UE context for the UE 50 also includes, for example, IDs of active PDU sessions, an SM context ID for each PDU session, and the ID of the SMF responsible for managing the PDU sessions. A pre-configured ID is also sent together with the Namf_Communication_CreateUEContext request message. The target AMF 7B receives the Namf_Communication_CreateUEContext request message.

[0215] In S254, the target AMF 7B searches for handover preset information in the configuration information storage unit 72 using the ID of the UE 50, the target cell ID, the preset ID, and the PDU session ID received together with the Namf_Communication_CreateUEContext request message as keys, and detects the handover preset information stored in S218 of Fig. 25 as the corresponding handover preset information. The detected handover preset information includes, for example, an SMF ID, an SM context ID, etc. (see Fig. 10). The target AMF 7B confirms that the information included in the handover preset information matches the information received together with the Namf_Communication_CreateUEContext request message.

[0216] The target AMF 7B transmits a Nsmf_PDUSession_UpdateSMContext request message including information indicating a handover request to the SMF 6A. The Nsmf_PDUSession_UpdateSMContext request message includes, as one piece of information, the ID of the UE 50, the target RAN, and the like, which are included in the Nsmf_Communication_CreateUEContext request message. The Nsmf_PDUSession_UpdateSMContext request message contains the ID, SM context ID, and target AMF 7B ID. The pre-configured ID received with the Nsmf_Communication_CreateUEContext request message is also sent with the Nsmf_PDUSession_UpdateSMContext request message. SMF 6A receives an Nsmf_PDUSession_UpdateSMContext request message.

[0217] In S255, SMF 6A uses the Nsmf_PDUSession_UpdateSMContext request message. The SMF 6A searches for handover preset information in the configuration information storage unit 72 using the ID of the UE 50, the preset ID, the PDU session ID, and the target RAN ID received together with the message as keys, and detects the handover preset information stored in S216 of Fig. 25 as the corresponding handover preset information. The detected handover preset information does not include information on the selected UPF because UPF selection was not performed in S215 of Fig. 25. Therefore, in S255, the SMF 6A does not determine whether to perform UPF selection or not, and does not select a UPF.

[0218] In S256, the SMF 6A performs the N4 session change procedure, for example, steps 6a-6b in Fig. 4.9.1.3.2-1 of 3GPP TS23.502, with the UPF to which the target PDU session is currently assigned, to prepare for the establishment of a PDU session between the target RAN and the UPF.

[0219] In S257, the SMF 6A sends an Nsmf_PDUSession_UpdateSMContext response message to the target AMF 7B. The Nsmf_PDUSession_UpdateSMContext response message includes information about the PDU session with the target RAN in the UPF. The target AMF 7B sends the Nsmf_PDUSession_UpdateSMContext Receive a response message.

[0220] In S258, the target AMF 7B transmits a Handover Request message to the target RAN. The Handover Request message is a message requesting the target RAN to prepare for handover. Thereafter, the handover sequence proceeds in accordance with the 3GPP standard. In S259, a Handover Request Acknowledge message is transmitted from the target RAN to the target AMF 7B, and information regarding the PDU session with the UPF in the target RAN is transmitted.

[0221] In S260, the target AMF 7B transfers the information about the PDU session with the UPF in the target RAN received in S259 to the SMF 6A using an Nsmf_PDUSession_UpdateSMContext request message. The SMF 6A performs an N4 session modification procedure with the UPF, which notifies the UPF of information about the PDU session with the UPF in the target RAN. In S262, the SMF 6A completes the UPF configuration and sends an Nsmf_PDUSession_UpdateSMContext response message to the target AMF 7B.

[0222] In S263, the target AMF 7B transmits a Namf_Communication_CreateUEContext response message to the source AMF 7A in response to the Namf_Communication_CreateUEContext request message in S253. This completes preparation for handover within 5GC 10. In S264, the source AMF 7A transmits a Handover Command message to the source RAN to notify that preparation for handover within 5GC 10 has been completed. Thereafter, the handover sequence is executed in accordance with the handover execution procedure disclosed in 4.9.1.3.3 of 3GPP TS23.502, for example.

[0223] In the sequence of handover between AMF regions in scenario #2 shown in Figure 26, the source AMF 7A has already selected the target AMF 7B in the pre-configuration process, so AMF selection is not performed in S252. Also, the SMF 6A has already selected a UPF to which the PDU session to be handed over is to be assigned, so UPF selection is not performed in S255. As a result, even when the UE 50 moves as in scenario #2, the pre-configuration process can shorten the time required for handover between AMF regions, and the time of communication interruption due to handover can be further shortened.

[0224] Furthermore, similar to scenario #1, scenario #2 can also support a configuration including an I-UPF such as a local breakout. For example, when UE 50 moves out of the service area of ​​the I-UPF due to movement from a cell in the region of source AMF 7A to a cell in target AMF 7B (OP42: YES in FIG. 18), SMF 6 selects a new I-UPF and PSA in pre-configuration S215 in FIG. 25 (OP43 in FIG. 18). When handover occurs due to movement from a cell in the region of source AMF 7A to a cell in target AMF 7B, SMF 6A holds handover pre-configuration information including information on the selected I-UPF, and therefore performs a session establishment process related to handover between the selected I-UPF included in the handover pre-configuration information and the PSA without performing a process of selecting a new I-UPF.

[0225] 27 is a diagram showing an example of a handover pre-configuration sequence in scenario #3. In scenario #3, the route of UE 50 falls within the region of the current AMF 7A, so AMF replacement does not occur, but the current AMF 7B is replaced. Since it does not fit within the service area of ​​SMF 6A, an I-SMF is added (insertion ), replacement, and removal occur. The cell transition information in scenario #3 includes cells included in the service area of ​​the current SMF 6A and cells not included in the service area of ​​the current SMF 6A. Note that all of the cells included in the cell transition information in scenario #3 are cells included in the service area of ​​the current AMF 7A.

[0226] The sequence shown in Fig. 27 is a continuation of the sequence shown in Fig. 20. S300 is the same process as S24 in Fig. 20, and the current AMF 7A receives a handover pre-configuration request, identification information of the UE 50, a pre-configured ID, and cell transition information from the NEF 3 (OP31: YES in Fig. 14).

[0227] In scenario #3, the cell transition information does not include cells outside the region of the current AMF 7A, so the current AMF 7A performs intra-region handover pre-configuration processing (OP32 in FIG. 14). In S311, for handover between cells within the region of the current AMF 7A included in the cell transition information, a handover pre-configuration sequence within the region of the current AMF 7A is executed, similar to S111-S116 in scenario #1.

[0228] The sequence from S312 to S319 is the current This is a handover pre-configuration sequence for handover from a cell within the service area of ​​SMF 6A to a cell outside the service area of ​​current SMF 6A. In S312, the current AMF 7A selects a future SMF and selects SMF 6C as the future SMF (OP325 in FIG. 15) because the cell transition information includes a transition to a cell outside the service area of ​​current SMF 6A (OP324 in FIG. 15: YES). The current AMF 7A, for example, queries the NRF to obtain SMF candidates and selects, from the candidates, an SMF whose service area includes a cell outside the service area of ​​SMF 6A included in the cell transition information.

[0229] In step S313, the current AMF 7A sends a handover pre-configuration request to the selected future SMF 6C (step OP326 in FIG. 15). Along with the handover pre-configuration request, for example, a pre-configuration ID, cell transition information, and an ID of the PDU session to be handed over are also sent.

[0230] The handover pre-configuration request is sent, for example, using the Nsmf_PDUSession_CreateSMContext request message, including information indicating that it is a handover pre-configuration request. The Nsmf_PDUSession_CreateSMContext request message also includes the following: The cell transition information includes the target RAN ID, the PDU session ID to be handed over, the SM context ID, and the ID of the current SMF 6A. The cell transition information is included in the Nsmf_PDUSession_CreateSMContext request message as the target RAN. The SM context included in the Nsmf_PDUSession_CreateSMContext request message can be used. The SM context ID is the SM context ID associated with the PDU session to be handed over in the context information of the UE 50 held by the current AMF 7A. The ID of the rent SMF 6A is an SMF ID associated with the PDU session to be handed over in the context information of the UE 50 held by the current AMF 7A. The future SMF 6C receives the handover pre-configuration request (OP41: YES in FIG. 18).

[0231] In S314, the future SMF 6C does not hold information about the PDU session to be handed over, so it determines whether to perform UPF selection (OP42 in FIG. 18). YES). In S315, future SMF 6C will use the Nsmf_PDUSession_Context resource. The request message is sent to the Nsmf_PDUSession_CreateSMContext link received in S313. The Nsmf_PDUSession_Context request message contains the SM context ID contained in the Nsmf_PDUSession_CreateSMContext request message received in S313, and is a message requesting the SM context corresponding to the SM context ID. In S316, the current SMF 6A sends the Nsmf_PDUSession_Context request message to the current SMF 6A. Receives the message and sends a Nsmf_PDUSession_Context response message to future SMF 6C, including the SM context corresponding to the specified SM context ID. do.

[0232] In S317, the future SMF 6C selects a UPF for the PDU session to be handed over (OP43 in FIG. 18).

[0233] In S318, the future SMF 6C stores the information received in S313 and S316 and the execution result of the process in S317 as handover pre-configuration information together with the pre-configuration ID (OP44 in FIG. 18). For example, for each PDU session, the future SMF 6C stores the PDU session ID, the SM context ID and the old SM context ID included in the Nsmf_PDUSession_CreateSMContext request message received in S313. The ID of the current SMF 6A as the SMF ID, the ID of the current AMF 7A corresponding to the SM context ID, and the ID of the UPF selected in S317 as the selected SMF ID are stored in the configuration information storage unit 62 as handover pre-configuration information for the UE 50, together with the ID and pre-configured ID of the cell in the service area of ​​the future SMF 6C to which the cell transition from the cell in the service area of ​​the current SMF 6A in the cell transition information is to be transitioned as the target RAN ID (see Figure 11).

[0234] In S319, the future SMF 6C transmits a response to the handover pre-configuration request to the current AMF 7A (OP45 in FIG. 18). Along with the response to the handover pre-configuration request, the pre-configuration ID, the target RAN ID(s) (cells in the service area of ​​the future SMF 6C included in the cell transition information) in which the handover pre-configuration information is stored, and the PDU session ID are also transmitted. The response to the handover pre-configuration request is transmitted, for example, using an Nsmf_PDUSession_CreateSMContext response message, including information indicating that it is a response to the handover pre-configuration request. The Nsmf_PDUSession_CreateSMContext response message also includes the SM context ID. The current AMF 7A receives the response to the handover pre-configuration request (OP327: YES in FIG. 15).

[0235] In S320, the current AMF 7A stores the information received in S300 and S319 together with the preset ID as handover preset information (OP36 in FIG. 14). For example, the current AMF 7A stores the following for each PDU session included in the Nsmf_PDUSession_CreateSMContext response message received in S319: The PDU session ID, SM context ID, and future SMF 6C ID are stored in the configuration information storage unit 72 as handover pre-configuration information for the UE 50, together with the ID of the cell in the service area of ​​the future SMF 6C included in the cell transition information as the target RAN ID and the pre-configuration ID (see Figure 10).

[0236] In S321, the current AMF 7A sends a response to the handover pre-configuration request to the NEF 3 (OP37 in FIG. 14). The ID of the UE 50 and the pre-configuration ID are also transmitted together with the response to the configuration request. The NEF 3 receives the response to the pre-configuration request (OP27: YES in FIG. 13). The handover pre-configuration sequence in FIG. 27 completes the handover pre-configuration within the 5CG 10 in Scenario #3.

[0237] FIG. 28 is a diagram showing an example of a handover sequence in scenario #3. FIG. 28 assumes that the pre-configuration sequences of FIG. 20 and FIG. 27 have been completed in the 5CG 10. It is also assumed that the UE 50 is moving on a route based on the route information notified in S11 of FIG. 20. FIG. 28 illustrates a handover sequence when the UE 50 moves from a cell within the service area of ​​the current SMF 6A to a cell outside the service area of ​​the current SMF 6A. However, both cells are cells within the region of the current AMF 7A. It is also assumed that the current SMF 6A is the main SMF that manages the target PDU session, and is not an I-SMF.

[0238] In the example of Figure 28, since the current SMF 6A is not an I-SMF, an I-SMF is added by handover when UE 50 moves from a cell within the service area of ​​current SMF 6A to a cell outside the service area of ​​current SMF 6A. In the example of Figure 28, the target RAN is a cell outside the region of current SMF 6A to which UE 50 transitions from a cell within the region of current SMF 6A in the cell transition information. In Figure 28, the current SMF 6A in Figure 27 is referred to as the source SMF 6A, and the future SMF 6C is referred to as the target SMF 6C.

[0239] In S351, the target RAN transmits an N2 Path Switch request message corresponding to a handover request to the current AMF 7A. The N2 Path Switch request message includes, among other information, identification information of the UE 50, the target RAN ID, and a list of PDU sessions to be handed over. The current AMF 7A receives the N2 Path Switch request message.

[0240] In S352, the current AMF 7A searches for handover pre-configuration information using the identification information of the UE 50, the target RAN ID, and the ID of the PDU session to be handed over, which are included in the N2 Path Switch request message received in S351, as keys, and detects the handover pre-configuration information stored in S320 of Fig. 27 as the search result. The detected handover pre-configuration information includes the pre-configuration ID, the SM context ID, and the ID of the target SMF 6C as the selected SMF ID (see Fig. 10). Therefore, in S352, the current AMF 7A does not perform SMF selection.

[0241] In S353, the current AMF 7A transmits an Nsmf_PDUSession_CreateSMContext request message to the target SMF 6C included in the handover pre-configuration information detected in S352. The Nsmf_PDUSession_CreateSMContext request message includes identification information of the UE 50, information indicating the handover request, the target RAN ID, the SM context ID and PDU session ID included in the handover pre-configuration information detected in S152, and the ID of the source SMF 6A as the old SMF ID. The ID of the source SMF 6A as the old SMF ID is the SMF ID associated with the PDU session to be handed over in the context information of the UE 50 held by the current AMF 7A. In addition, in S352, the Nsmf_PDUSession_CreateSMContext request message is transmitted together with the Nsmf_PDUSession_CreateSMContext request message. The pre-configuration ID corresponding to the detected handover pre-configuration information is also sent. The target SMF 6C receives the Nsmf_PDUSession_CreateSMContext request message.

[0242] In S354, the target SMF 6C receives the identification information of the UE 50, the pre-configured The handover pre-configuration information in the configuration information storage unit 62 is searched for using the ID, target RAN ID, and PDU session ID as keys, and the handover pre-configuration information stored in S318 in Fig. 27 is detected as the search result. In the example shown in Fig. 28, the detected handover pre-configuration information includes the ID of the source SMF 6A as the old SMF ID and the selected UPF ID. Therefore, in Fig. 28, the target SMF 6C does not determine whether to perform UPF selection or not, and does not select a UPF.

[0243] In S355, the target SMF 6C performs an N4 session establishment procedure for the selected UPF (I-UPF) included in the handover pre-configuration information detected in S354, thereby preparing the I-UPF for establishing a PDU session with the target RAN.

[0244] In S356, the target SMF 6C sends an Nsmf_PDUSession_Create request message to the source SMF 6A, requesting the creation of a PDU session. The Nsmf_PDUSession_Create request message includes, among other information, the ID of the UE 50, the SM context ID, and the PDU session ID. The source SMF 6A receives the Nsmf_PDUSession_Create request message.

[0245] In S357, the source SMF 6A performs the N4 session modification procedure on the PSA UPF of the PDU session corresponding to the PDU session ID included in the Nsmf_PDUSession_Create request message. This prepares the PSA UPF to establish a PDU session with the I-UPF. In S358, the source SMF 6A sends an Nsmf_PDUSession_Create response message to the target SMF 6C. The Nsmf_PDUSession_Create response message includes information about the PDU session with the I-UPF in the PSA.

[0246] In step S359, the target SMF 6C notifies the I-UPF of information about the PDU session with the I-UPF in the PSA UPF, which is included in the Nsmf_PDUSession_Create response message, and performs the N4 session modification procedure, thereby preparing the I-UPF to establish a PDU session with the PSA UPF.

[0247] In S360, the target SMF 6C sends a Nsmf_PDUSession_CreateSMContext response to the current AMF 7A indicating that it is ready to establish a PDU session. The current AMF 7A receives the Nsmf_PDUSession_CreateSMContext response message. 7A sends an Ack message to the transmission target RAN in response to the N2 Path Switch request, notifying the completion of preparation for handover in 5GC. After that, the completion of preparation for handover is notified from the target RAN to the source RAN and UE 50, and the handover is performed.

[0248] In the handover sequence in Scenario #3 shown in FIG. 28, the selection of the I-SMF by the current AMF 7A in S352, the selection of the UPF by the target SMF 6C in S354, and the acquisition of the SM context from the source SMF 6A have already been performed by the handover pre-configuration sequence in FIG. 27; This is skipped in the handover sequence in Fig. 28. This allows the time required for handover to be shortened even in a handover in which the SMF service area is changed, as in scenario #3, and also allows the time for communication interruption due to handover to be shortened.

[0249] In Figure 28, the sequence in which an I-SMF is added in conjunction with a handover in which the SMF service area changes is explained using an example in which there is no I-SMF other than the current SMF (source SMF) 6A, and the current SMF 6A is the SMF that was initially responsible for managing the target PDU session. This is not limited to this, and even if the current SMF is an I-SMF, the handover pre-configuration sequence in Figure 27 can be executed to subsequently shorten the time required for a handover sequence in which the SMF service area changes. Hereinafter, the SMF that was initially responsible for managing the target PDU session will be referred to as the original SMF.

[0250] For example, when the current SMF is an I-SMF, a handover that changes the service area of ​​the SMF may result in either the I-SMF being released or the I-SMF being replaced. The case in which the I-SMF is released occurs when the current SMF is an I-SMF and the target cell is a cell within the service area of ​​the original SMF. The case in which the I-SMF is replaced occurs when the current SMF is an I-SMF and the target cell is a cell within the service area of ​​an SMF other than the original SMF.

[0251] In the case where the I-SMF is released, the original SMF is selected as the future SMF in the pre-configuration at S312 in FIG. 27, and the PSA UPF managed by the SMF is selected at S317 in FIG. 27. Thereafter, when a handover occurs that changes the service area of ​​the SMF, management of the target PDU session is transferred to the original SMF as the future SMF, and at the same time, the path of the PDU session is changed to a path that reaches the pre-selected PSA UPF without passing through the I-UPF managed by the I-SMF. Then, the I-UPF and the I-SMF that manages the I-UPF are released. In this series of sequences, for example, processes such as selecting the original SMF as the future SMF and selecting the PSA UPF as the UPF to which the target PDU session is assigned within the service area of ​​the original SMF are not performed.

[0252] In the case where the I-SMF is replaced, in the pre-configuration, an SMF whose service area includes a target cell other than the original SMF is selected as the future SMF at S312 in Figure 27, and a UPF managed by the SMF is selected at S317 in Figure 27. Thereafter, when a handover occurs that changes the service area of ​​the SMF, the I-SMF on which the target PDU session is established is switched to the SMF selected as the future SMF, and at the same time, the I-UPF of the path of the PDU session is switched to the I-UPF selected in the pre-configuration sequence. In this series of sequences, for example, processes such as selecting a future SMF and selecting a UPF to which the target PDU session is assigned within the service area of ​​the future SMF are not performed.

[0253] Also, in scenario #3, for example, the handover pre-configuration sequence shown in FIG. 27 can be applied to local breakout such as edge computing. For example, in the case where the above-mentioned I-SMF is added or replaced, the UL CL UPF and PSA UPF in the service area of ​​the future I-SMF are selected in S317 of FIG. 27. In this case, if the UE 50 is in the service area of ​​the current SMF, When a handover is performed from a cell in the service area of ​​the future I-SMF to a cell in the service area of ​​the future I-SMF, the future I-SMF holds handover pre-configuration information including information on the selected I-UPF (UL CL and PSA), and therefore performs a session establishment process for the handover between the selected UL CL and PSA included in the handover pre-configuration information without performing a process for selecting a new I-UPF. This allows the time required for handover to be shortened even in scenario #3, for example, even when local breakout is configured, and the time of communication interruption due to handover can be further shortened. Note that in scenario #3, the PDU session pre-configuration sequence and PDU session establishment sequence are the same as those in scenario #1.

[0254] 29 is a diagram showing an example of a handover pre-configuration sequence in scenario #4. Scenario #4 is a scenario in which the route of UE 50 is not within the region of the current AMF 7A nor within the service area of ​​the current SMF 6A. Therefore, in scenario #4, AMF replacement and I-SM Scenarios in which insertion, replacement, or removal of F occurs Therefore, the cell transition information in scenario #4 includes cells within the region of the current AMF 7A and cells outside the region of the current AMF 7A, and also includes cells within the service area of ​​the current SMF 6A and cells outside the service area of ​​the current SMF 6A. Furthermore, in the cell transition information in scenario #4, it is assumed that a transition from a cell within the service area of ​​the current SMF 6A to a cell outside the service area of ​​the current SMF 6A occurs outside the region of the current AMF 7A.

[0255] The sequence shown in Fig. 29 is a continuation of the sequence shown in Fig. 20. S400 is the same process as S24 in Fig. 20, and the current AMF 7A receives a handover pre-configuration request, identification information of the UE 50, a pre-configured ID, and cell transition information from the NEF 3 (OP31: YES in Fig. 14).

[0256] In S411, for handover between cells within the region of the current AMF 7A included in the cell transition information, a sequence similar to S111-S116 in scenario #1 is executed. Also, for handover from a cell within the region of the current AMF 7A included in the cell transition information to a cell outside the region of the current AMF 7A included in the cell transition information, a sequence similar to S212-S218 in scenario #2 is executed. In S411, it is assumed that AMF 7C is selected as the future AMF.

[0257] The sequence from S412 to S422 is a handover pre-configuration sequence for handover from a cell in the service area of ​​the current SMF 6A to a cell outside the service area of ​​the current SMF 6A in the region of the future AMF 7C included in the cell transition information. Since the cell transition information includes a transition to a cell outside the service area of ​​the current SMF 6A (OP324: YES in FIG. 15), 7C selects a future SMF and selects SMF 6D as the future SMF (OP325 in FIG. 15).

[0258] The processing from S413 to S420 is the same as the processing from S313 to S320 in Scenario #3, except that the current AMF 7A is replaced by the future AMF 7C and the future SMF 6B is replaced by the future SMF 6D. In S413, the future AMF 7C sends a handover pre-configuration request to the selected future SMF 6D using the Nsmf_PDUSession_CreateSMContext request message. Send the quest (OP326 in Figure 15).

[0259] In S414, the future SMF 6D does not hold information about the PDU session to be handed over, and therefore determines whether to perform UPF selection (OP42 in FIG. 18: YES). In S415, the future SMF 6D In step S416, the current SMF 6A receives the Nsmf_PDUSession_Context request message. , and sends an Nsmf_PDUSession_Context response message to future SMF 6D, including the SM context corresponding to the specified SM context ID.

[0260] In S417, the future SMF 6D selects a UPF for the PDU session to be handed over (OP43 in FIG. 18). In S418, the future SMF 6D stores the information received in S413 and S416 and the execution result of the process of S417 together with a preset ID as handover preset information (OP44 in FIG. 18). For example, for each PDU session, the future SMF 6D stores the PDU session ID, the SM context ID, the ID of the current SMF 6A as the old SMF ID, the ID of the future AMF 7C corresponding to the SM context ID, and the ID of the UPF selected in S417 as the selected SMF ID, together with the ID and preset ID of the cell in the service area of ​​the future SMF 6D to which transition is made from the cell in the service area of ​​the current SMF 6A in the cell transition information as the target RAN ID in the configuration information storage unit 62 as handover preset information for the UE 50 (see FIG. 11).

[0261] In S419, future SMF 6D sends a handover pre-configuration request to future AMF 7C using the Nsmf_PDUSession_CreateSMContext response message. The future AMF 7C transmits a response to the request (OP45 in FIG. 18). In S420, the future AMF 7C stores the information received in S319 together with the preset ID as handover preset information (OP38C in FIG. 14). For example, the future AMF 7C stores, for each PDU session, the PDU session ID, the SM context ID, and the ID of the future SMF 6D, together with the ID of the cell in the service area of ​​the future SMF 6D included in the cell transition information as the target RAN ID and the preset ID, as handover preset information for the UE 50 in the configuration information storage unit 72 (see FIG. 10).

[0262] In S421, the future AMF 7C sends a response to the handover pre-configuration request to the current AMF 7A by using a Namf_Communication_CreateUEContext response message (OP38D in FIG. 14). In S422, the current AMF 7A stores the information received in S421 together with a pre-configuration ID as handover pre-configuration information (OP36 in FIG. 14). For example, the current AMF 7A stores, for each PDU session, the PDU session ID, the SM context ID, the ID of the current SMF 6A corresponding to the SM context ID, and the ID of the future AMF 7C as the target AMF ID, together with the ID of the cell in the region of the future AMF 7C included in the cell transition information as the target RAN ID and the pre-configuration ID, as handover pre-configuration information for the UE 50 in the configuration information storage unit 72 (see FIG. 10).

[0263] In S423, the current AMF 7A transmits a response to the handover pre-configuration request to the NEF 3 (OP37 in FIG. 14). The NEF 3 receives the response to the handover pre-configuration request (OP25: YES in FIG. 13). The handover pre-configuration sequence in FIG. 29 allows the 5CG in Scenario #4 to The handover pre-configuration within 10 is completed.

[0264] FIG. 30 is a diagram showing an example of a handover sequence in scenario #4. FIG. 30 is based on the premise that the pre-setting sequences of FIG. 20 and FIG. 29 have been completed in the 5CG 10. It is also assumed that the UE 50 is moving on a route based on the route information notified in S11 of FIG. 20. In FIG. 30, the cell located at the boundary of the region of the current AMF 7A and the cell located at the boundary of the service area of ​​the current SMF 6A are the same cell, and the UE 50 is notified of the current AMF Assume that when moving from a cell within the region of current SMF 7A to a cell in the region of current SMF 7A, a transition also occurs from a cell within the service area of ​​current SMF 6A to a cell outside the service area of ​​current SMF 6A.

[0265] 30, it is assumed that the current SMF 6A is an I-SMF. It is also assumed that the cell outside the service area of ​​the current SMF 6A, which is the destination of movement from a cell within the service area of ​​the current SMF 6A, is not a cell within the service area of ​​the original SMF 6E. Therefore, in the example of FIG. 30, the I-SMF is replaced by a handover when moving from a cell within the service area of ​​the current SMF 6A to a cell outside the service area of ​​the current SMF 6A.

[0266] In the example of Figure 30, the target RAN is a cell outside the region of the current AMF 7A to which the UE 50 transitions from a cell within the region of the current AMF 7A in the cell transition information, and is a cell outside the region of the current SMF 6A to which the UE 50 transitions from a cell within the region of the current SMF 6A. In Figure 30, the current AMF 7A in Figure 29 is referred to as the source AMF 7A, the future AMF 7C is referred to as the target AMF 7C, and the current SMF 6A is referred to as the source SMF 6A, and future SMF 6D is referred to as the target SMF 6D.

[0267] In S451, the target RAN transmits a Handover Required message corresponding to a handover request to the source AMF 7A. The Handover Required message includes, as part of the information, identification information of the UE 50 and the target RAN ID. The source AMF 7A receives the Handover Required message.

[0268] In S452, the source AMF 7A searches for handover pre-configuration information in the configuration information storage unit 72 using the identification information of the UE 50 and the target RAN ID included in the Handover Required message as keys, and detects, for example, the handover pre-configuration information stored in S422 of Fig. 29 as the corresponding handover pre-configuration information. The detected handover pre-configuration information includes the PDU session ID and the ID of the selected target AMF 7C (see Fig. 10). Therefore, in S452, the source AMF 7A does not select a target AMF.

[0269] In S453, the source AMF 7A transmits a Namf_Communication_CreateUEContext request message including information indicating a handover request to the target AMF 7C. The Namf_Communication_CreateUEContext request message includes, as one piece of information, a UE context for the UE 50 held by the source AMF 7A, a target RAN ID, etc. In the example shown in FIG. 30, the target RAN ID is the ID of a cell in the region of the future AMF 7C to which the UE 50 will transition from a cell in the region of the current AMF 7A. The context also contains, for example, the PDU session ID, the SM context ID for each PDU session and the ID of the SMF responsible for managing the PDU session. A pre-configured ID is also sent with the Namf_Communication_CreateUEContext request message. The target AMF 7C receives the Namf_Communication_CreateUEContext request message.

[0270] In S454, the target AMF 7C searches for handover preset information in the configuration information storage unit 72 using the ID of the UE 50, the target cell ID, the preset ID, and the PDU session ID received together with the Namf_Communication_CreateUEContext request message as keys, and detects the handover preset information stored in S420 of Fig. 29 as the corresponding handover preset information. The detected handover preset information includes the preset ID, the SM context ID, and the ID of the target SMF 6D as the selected SMF ID (see Fig. 10). Therefore, in S454, the target MF 7C does not perform SMF selection.

[0271] In S455, the target AMF 7C sends the Nsmf_PDUSession_CreateSMContext link to the target SMF 6D included in the handover pre-configuration information detected in S454. Send a request message. Nsmf_PDUSession_CreateSMContext request message The message includes identification information of the UE 50, information indicating the handover request, the target RAN ID, the SM context ID and PDU session ID included in the handover pre-configuration information detected in S454, and the source SMF as the old SMF ID. The ID of the source SMF 6A as the old SMF ID is the SMF ID associated with the PDU session to be handed over in the context information of the UE 50 that the target AMF 7C received from the source AMF 7A in S453. The target SMF 6D also sends the Nsmf_PDUSession_CreateSMContext request along with the handover pre-configuration ID corresponding to the handover pre-configuration information detected in S454. Receive a test message.

[0272] In S456, the target SMF 6D receives the identification information of the UE 50, the pre-configured The handover pre-configuration information in the configuration information storage unit 62 is searched for using the ID, target RAN ID, and PDU session ID as keys, and the handover pre-configuration information stored in S418 of Fig. 29 is detected as the search result. In the example shown in Fig. 30, the detected handover pre-configuration information includes the ID of the source SMF 6A as the old SMF ID and the selected UPF ID. Therefore, in Fig. 30, the target SMF 6D does not determine whether to perform UPF selection, and does not select a UPF. The detected handover pre-configuration information also includes the SM context in the source SMF 6A acquired in S416 of Fig. 29.

[0273] In S457, the target SMF 6D performs an N4 session establishment procedure with the selected UPF (target I-UPF) included in the handover pre-configuration information detected in S456. The target SMF 6D notifies the target I-UPF of information about the PDU session with the PSA, and the target I-UPF prepares to establish a PDU session with the PSA. The information about the PDU session with the PSA is included in the SM context detected in S456. In addition, the target I-UPF prepares to establish a PDU session with the target RAN.

[0274] In S458, the target SMF 6D sends a Nsmf_PDUSession_CreateSMContext response message to the target AMF 7A. The xt response message contains information about the PDU session with the target RAN in the target I-UPF.

[0275] At S459, the target AMF 7C transmits a Handover Request message to the target RAN. The Handover Request message is a message requesting the target RAN to prepare for handover. At S460, the target RAN transmits a Handover Request Acknowledge message to the target AMF 7C, indicating that the target RAN has accepted the handover.

[0276] In S461, the target AMF 7C transmits an Nsmf_PDUSession_UpdateSMContext request message including information indicating acceptance of the handover in the target RAN to the target SMF 6D. The Nsmf_PDUSession_UpdateSMContext request message includes configuration information of the PDU session in the target RAN.

[0277] At S462, the target SMF 6D performs an N4 session modification procedure with the target I-UPF. At S462, the target I-UPF is notified of PDU session configuration information in the target RAN. The target I-UPF also prepares indirect forwarding between the source I-UPF and the target I-UPF to transfer data from the UE 50 generated during handover from the source RAN to the target RAN.

[0278] In S463, the target SMF 6D sends an Nsmf_PDUSession_UpdateSMContext request message to the source SMF 6A. The Nsmf_PDUSession_UpdateSMContext request message sent in S463 includes information about indirect forwarding between the source I-UPF and the target I-UPF. In S464, the source SMF 6A performs an N4 session modification procedure with the source I-UPF. In S464, the source I-UPF is notified of information about indirect forwarding, and the source I-UPF prepares for indirect forwarding with the target I-UPF.

[0279] In S465, the source SMF 6A sends a Nsmf_PDUSession_UpdateSMContext response message to the target SMF 6D to update the indirect forwarding In S466, the target SMF 6D notifies the target AMF 7C of the Nsmf_PDUSession_UpdateSMContext request received in S461. Send a Nsmf_PDUSession_UpdateSMContext response message to the Nsmf_PDUSession_UpdateSMContext request message. The Nsmf_PDUSession_UpdateSMContext response message contains the It contains information about indirect forwarding to

[0280] In S467, the target AMF 7C transmits a Namf_Communication_CreateUEContext response message in response to the Namf_Communication_CreateUEContext request message received in S453 to the source AMF 7A. The Namf_Communication_CreateUEContext response message includes information about indirect forwarding to be notified to the source RAN.

[0281] In S468, the source AMF 7A transmits a Handover Command message to the source RAN to notify it that preparation for handover within the 5GC 10 has been completed. At the same time, information regarding indirect forwarding is also notified to the source RAN. After this, the handover sequence is executed in accordance with the handover execution procedure disclosed in 4.23.7.3.3 of 3GPP TS23.502, for example.

[0282] In the handover sequence in scenario #4 shown in Figure 30, the selection of the target AMF by the source AMF 7A in S452, the selection of the target SMF by the target AMF 7C in S454, the selection of the UPF by the target SMF 6D in S456, and the acquisition of the SM context from the source SMF 6A have already been performed in the handover pre-configuration sequence in Figure 29, and are skipped in the handover sequence in Figure 30. This makes it possible to shorten the time required for handover, even in a handover in which the SMF service area changes along with a change in the AMF region, as in scenario #4, and further shorten the time required for communication interruption due to handover.

[0283] 30, the case where the current SMF (source SMF) 6A is an I-SMF and the handover destination cell is a cell within the service area of ​​another SMF other than the original SMF, and therefore the I-SMF is replaced with a new I-SMF, has been described as an example. However, the present invention is not limited to this. In the case where the current SMF is an I-SMF and the handover destination cell is a cell within the service area of ​​the original SMF, and therefore the I-SMF is released, and in the case where the current SMF is the original SMF and the handover destination cell is a cell within the service area of ​​another SMF, and therefore an I-SMF is added, the time required for the handover sequence can be reduced in the same way as in the example shown in FIG.

[0284] Also, in scenario #4, for example, when a local breakout such as edge computing is configured, the handover pre-configuration sequence shown in Figure 29 can be applied, as in scenario #3. Note that in scenario #4, the PDU session pre-configuration sequence and PDU session establishment sequence are the same as in scenario #1.

[0285] <Effects of the First Embodiment> In the first embodiment, the 5GC 10 performs pre-configuration of handover and PDU session establishment in advance of the movement path of the UE 50, thereby shortening the time required for handover and PDU session establishment. This shortens the time for communication interruption due to handover and reduces degradation in communication quality. Furthermore, the time required for PDU session establishment can be shortened, allowing the UE 50 to start communication through the PDU session more quickly. Furthermore, since QoS is configured in advance for a specific application, communication related to the application can be started more quickly with communication quality appropriate for the UE 50.

[0286] Second Embodiment In the second embodiment, cell transition information of the UE 50 is acquired using the UE mobility prediction function of the NWDAF 8. In the second embodiment, descriptions common to the first embodiment will be omitted. In the second embodiment, the hardware configuration and functional configuration of each NF are the same as those in the first embodiment.

[0287] 31 is a diagram illustrating processing in a communication system 100B according to the second embodiment. In the second embodiment, the AF 1 transmits a pre-configuration request for the UE 50 to the 5CG 10. However, unlike the first embodiment, the AF 1 does not transmit route information for the UE 50. Also, in the second embodiment, the AF 1 does not need to transmit a pre-configuration request for the UE 50 every time a route is configured in the UE 50.

[0288] Upon receiving the pre-configuration request, the NEF 3 starts monitoring the movement of the UE 50, and when it detects that the UE 50 has started to move, it acquires movement prediction information of the UE 50 from the NWDAF 8. The movement prediction information of the UE 50 acquired from the NWDAF 8 includes, for example, identification information of cells in which the UE 50 may be located during a predetermined period, in order of time slots. The NEF 3 transmits the movement prediction information acquired from the NEF 8 as cell transition information to the AMF 1 together with the handover pre-configuration request.

[0289] FIG. 32 is an example of a flowchart of the process of AF 1 in the second embodiment. The process shown in FIG. 32 is repeatedly executed at a predetermined cycle. 1 is assumed to receive location information from UE 50 at a predetermined period.

[0290] In OP61, the AF 1 determines whether the UE 50 has started moving. The start of movement of the UE 50 is detected, for example, by a change in the position of the UE 50. If the UE 50 has started moving (OP61: YES), the process proceeds to OP62. If the UE 50 has not started moving (OP61: NO), the process shown in FIG. 32 ends.

[0291] In OP62, the AF 1 sends a pre-configuration request to the NEF 3. The identification information of the UE 50 is also sent together with the pre-configuration request. In OP63, the AF 1 determines whether or not a response to the pre-configuration request has been received. If a response to the pre-configuration request has been received (OP63: YES), the process proceeds to OP64. If a response to the pre-configuration request has not been received (OP63: NO), the AF 1 enters a standby state.

[0292] In OP64, the AF 1 determines whether the movement of the UE 50 has ended. The end of the movement of the UE 50 is detected, for example, when the location information of the UE 50 does not change for a predetermined period of time. If the movement of the UE 50 has ended (OP64: YES), the process proceeds to OP65. If the movement of the UE 50 has not ended (OP64: NO), the AF 1 enters a standby state.

[0293] In OP65, the AF 1 notifies the NEF 3 of the end of the movement of the UE 50. After that, the process shown in Figure 32 ends.

[0294] 33 is an example of a flowchart of processing related to pre-configuration of the NEF 3 according to the second embodiment. The processing shown in FIG. 33 is repeatedly executed at a predetermined cycle. In OP71, the NEF 3 determines whether or not a pre-configuration request has been received from the AF 1. If a pre-configuration request has been received from the AF 1 (OP71: YES), the processing proceeds to OP72. If a pre-configuration request has not been received from the AF 1 (OP71: NO), the processing shown in FIG. 33 ends.

[0295] In OP72, the NEF 3 starts monitoring the location of the UE 50. Specifically, the NEF 3 registers with the AMF 7 for notification of the serving cell of the UE 50, and periodically acquires the serving cell of the UE 50.

[0296] In OP73, the NEF 3 inquires of the NWDAF 8 and acquires movement prediction information of the UE 50. In OP74, the NEF 3 executes the processes of OP23 to OP27 in Fig. 13 using the movement prediction information acquired from the NWDAF 8 as cell transition information. As a result, pre-configuration related to wireless communication for the UE 50 in the 5CG 10 is performed.

[0297] In OP75, the NEF 3 determines the location of the UE 50 based on the notification of the serving cell from the AMF 7. Then, it is determined whether the UE 50 has moved out of the cell included in the cell transition information. If the UE 50 has moved out of the cell included in the cell transition information (YES in OP75), the process proceeds to OP73, and the process is executed again from obtaining movement prediction information for the UE 50. If the UE 50 has not moved out of the cell included in the cell transition information (NO in OP75), the process proceeds to OP76.

[0298] In OP76, the NEF 3 determines whether the movement of the UE 50 has ended. The NEF 3 detects the end of the movement of the UE 50 by receiving a notification from the AF 1 that the movement of the UE 50 has ended. If the movement of the UE 50 has ended (OP76: YES), the process proceeds to OP77. If the movement of the UE 50 has not ended (OP76: NO), the process proceeds to OP75. In OP77, the NEF 3 ends the location monitoring of the UE 50. Specifically, the NEF 3 transmits a message to the AMF 7 to cancel the registration of the notification of the serving cell of the UE 50. Then, the process shown in FIG. 33 ends.

[0299] Fig. 34 shows an example of a processing sequence from when a pre-configuration request is transmitted from the AF 1 to when the pre-configuration request is transmitted to the current AMF in the second embodiment. In the example shown in Fig. 34, it is assumed that the UE 50 has already registered in the region of the current AMF 7A, and one PDU session has already been established under the management of the current SMF 6A. It is also assumed that the QoS configuration sequence (S12 to S18 in Fig. 20) for the target application has already been executed.

[0300] In S501, the AF 1 detects that the UE 50 has started to move from the location information of the UE 50 that is periodically received. In S502, the AF 1 transmits a pre-configuration request to the NEF 3. The pre-configuration request transmitted in S501 includes identification information of the UE 50. The NEF 3 receives the pre-configuration request (FIG. 33, OP71: YES).

[0301] In S511, the NEF 3 sends a Namf_EventExposure_Subscribe request message to the AMF 7 to which the UE 50 is registered, to register for notification of the serving cell of the UE 50. The AMF 7 to which the UE 50 is registered is identified, for example, by querying the UDM 2. The Namf_EventExposure_Subscribe request message includes: The target event ID is "Location Reporting" and the target UE ID is the ID of the UE 50. In S512, the AMF 7 transmits a Namf_EventExposure_Subscribe response message to the NEF 3. This allows the AMF 7 to The NEF 3 periodically notifies the NEF 3 of the cell in which the UE 50 is located at a predetermined cycle, and the NEF 3 starts monitoring the location of the UE 50 (OP72 in FIG. 33).

[0302] In S513, the NEF 3 transmits an Nnwdaf_AnalyticsInfo_Request message to the NWDAF 8, requesting mobility prediction information for the UE 50. The Nnwdaf_AnalyticsInfo_Request message includes "UE Mobility" as the Analytics ID, The ID includes the ID of the UE 50. In S514, the NWDAF 8 transmits an Nnwdaf_AnalyticsInfo_Request response message including the movement prediction information of the UE 50 to the NEF 3. The NEF 3 acquires the movement prediction information of the UE 50 (OP73 in FIG. 33).

[0303] In S515, the NEF 3 identifies the current AMF 7A to be configured (OP74 in FIG. 33). In S516, the NEF 3 transmits a handover pre-configuration request to the current AMF 7A (OP74 in FIG. 33). The NEF 3 transmits the pre-configuration ID, identification information of the UE 50, and cell transition information together with the handover pre-configuration request.

[0304] In S521, the AMF 7 notifies the UE 50 of the serving cell at a predetermined period. When it is detected that the mobile station 50 has moved out of the cell included in the cell transition information, the sequence starts again from S513.

[0305] According to the second embodiment, by utilizing the UE movement prediction function of the NWDAF 8, even if the route information of the UE 50 cannot be obtained, the 5GC 10, pre-configuration regarding wireless communication for the UE 50 can be performed.

[0306] <Modification of the second embodiment> In the second embodiment, the AF 1 acquires the location information of the UE 50 from the UE 50 and In the second embodiment, the NEF 3 periodically acquires location information of the UE 50 from the NWDAF 8 and detects when the UE 50 starts moving. In a modified example of the second embodiment, the AF 1 does not detect the start and end of movement of the UE 50, but transmits a pre-configuration request to the NEF 3.

[0307] Fig. 35 is an example of a flowchart of a process related to pre-configuration of the NEF 3 according to a modification of the second embodiment. The process shown in Fig. 35 is started when the NEF 3 receives a pre-configuration request from the AF 1. The process shown in Fig. 35 is stopped, for example, when an instruction to stop the pre-configuration process is received from the AF 1.

[0308] If the NEF 3 receives a pre-configuration request from the AF 1 (OP81: YES), the process proceeds to OP82. In OP82, the NEF 3 registers with the NWDAF 8 for periodic notification of the location information of the UE 50. Thereafter, the NEF 3 periodically acquires the location information of the UE 50 from the NWDAF 8. The location information of the UE 50 acquired from the NWDAF 8 is indicated by, for example, latitude and longitude. The location information of the UE 50 acquired from the NWDAF 8 may also include the serving cell of the UE 50.

[0309] In OP83, the NEF 3 determines whether the UE 50 has started moving based on the location information of the UE 50. For example, if there is a change in the location information of the UE 50, the start of movement of the UE 50 is detected. If the UE 50 has started moving (OP83: YES), the process proceeds to OP84. The NEF 3 remains in a standby state until the UE 50 has started moving (OP83: NO).

[0310] In OP84, the NEF 3 acquires movement prediction information of the UE 50 from the NWDAF 8, and in OP85, executes the processes of OP23 to OP27 in FIG. 13 using the movement prediction information as cell transition information.

[0311] In OP86, the NEF 3 determines whether the UE 50 has moved out of the cell included in the cell transition information, based on the location information of the UE 50 periodically notified by the NWDAF 8. If the UE 50 has moved out of the cell included in the cell transition information (OP86: YES), the process proceeds to OP84, and is executed again from obtaining movement prediction information for the UE 50. If the UE 50 has not moved out of the cell included in the cell transition information (OP86: NO), the process proceeds to OP87.

[0312] In OP87, the NEF 3 determines whether the movement of the UE 50 has ended based on the location information of the UE 50 periodically notified from the NWDAF 8. If the movement of the UE 50 has ended (OP87: YES), the process proceeds to OP83. If the movement of the UE 50 has not ended (OP87: NO), the process proceeds to OP86.

[0313] Fig. 36 shows an example of a processing sequence from when a preset request is sent from AF 1 to when a preset request is sent to the current AMF in a modified example of the second embodiment. The premise of the example shown in Fig. 36 is the same as the example shown in Fig. 34.

[0314] In S601, the AF 1 transmits a pre-configuration request to the NEF 3 together with the identification information of the UE 50. The NEF 3 receives the pre-configuration request (FIG. 34, OP81: YES).

[0315] In S602, the NEF 3 transmits to the NWDAF 8 an Nnwdaf_AnalyticsSubscription_Subscribe request message requesting periodic notification of the location information of the UE 50 (OP82 in FIG. 35). The Nnwdaf_AnalyticsSubscription_Subscribe request message includes "UE Mobility" as the target Analytics ID, The ID includes the identification information of the UE 50. In S603, the NWDAF 8 transmits an Nnwdaf_AnalyticsSubscription_Subscribe response message to the NEF 3. As a result, the NWDAF 8 notifies the NEF 3 of the location information of the UE 50 periodically at a predetermined cycle, and the NEF 3 starts monitoring the location of the UE 50.

[0316] In S604, the NWDAF 8 transmits an Nnwdaf_AnalyticsSubscription_Notify message to the NEF 3 to notify the NEF 3 of the location information of the UE 50. The Nnwdaf_AnalyticsSubscription_Notify message includes the location information of the UE 50. Thereafter, the NWDAF 8 notifies the NEF 3 of the location information of the UE 50 at predetermined intervals.

[0317] In S611, the UE 50 starts moving, and the NEF 3 detects that the UE 50 has started moving based on the location information of the UE 50 notified from the NWDAF 8 (OP83 in FIG. 35: YES). In S612, the NEF 3 transmits an Nnwdaf_AnalyticsInfo_Request message to the NWDAF 8, requesting movement prediction information for the UE 50. The Nnwdaf_AnalyticsInfo_Request message includes "UE Mobility" as the Analytics ID. ", and the ID of the UE 50 is included as the target UE ID. In S613, the NWDAF 8 transmits an Nnwdaf_AnalyticsInfo_Request response message including the movement prediction information of the UE 50 to the NEF 3. The NEF 3 acquires the movement prediction information of the UE 50 (OP84 in FIG. 35).

[0318] In S614, the NEF 3 identifies the current AMF 7A to be configured (OP85 in FIG. 35). In S615, the NEF 3 transmits a handover pre-configuration request to the current AMF 7A (OP85 in FIG. 35). The NEF 3 transmits the pre-configuration ID, identification information of the UE 50, and cell transition information together with the handover pre-configuration request.

[0319] Thereafter, if the NEF 3 detects, based on the location information of the UE 50 notified from the NWDAF 8, that the UE 50 has moved out of the cell included in the cell transition information (OP86: YES in FIG. 35), the processing from S612 is performed.

[0320] According to the modified example of the second embodiment, by utilizing the UE movement statistics function of the NWDAF 8, it is possible to preconfigure the UE 50 without the UE 50 periodically notifying the location information of the UE 50, and it is possible to reduce wireless communication with the AF 1.

[0321] In the modification of the second embodiment, the location information and movement prediction information of the UE 50 are acquired from the NWDAF 8 by different messages (see S604 and S613). (See reference) However, the present invention is not limited to this, and the location information of the UE 50 and the movement prediction information can be acquired from the NWDAF 8 in the same message. In this case, the movement prediction information, together with the location information of the UE 50, is periodically transmitted by the Nnwdaf_AnalyticsSubscription_Notify message. The NWDAF 8 notifies the NEF 3. In this case, the NEF 3 may detect that the UE 50 has deviated from the cell transition information by detecting a change in the content of the mobility prediction information that is periodically notified (OP86 in FIG. 35 ).

[0322] <Other embodiments> The above-described embodiment is merely an example, and the present disclosure can be modified and implemented as appropriate within the scope that does not deviate from the gist of the disclosure.

[0323] In the first and second embodiments, the NEF 3 has a function to control pre-configuration related to radio communication for the UE 50 in the 5GC 10. This is not limiting, and a new NF may have a function to control pre-configuration. The new NF receives the pre-configuration request and cell transition information through the NEF 3, identifies the AMF that manages the UE 50, and transmits the pre-configuration request to the AMF.

[0324] In the first and second embodiments, existing messages (Nsmf_PDUSession_Create / UpdateSMContext, Namf_Commnication_CreateUEContext) in the 3GPP standard are used to transmit pre-configuration requests and responses between AMF and SMF, and between AMFs. New messages for pre-configuration may be used to send pre-configuration requests and responses between AMF and SMF, and between AMFs.

[0325] In the first and second embodiments, the QoS configuration for a specific application may be performed before the UE 50 starts moving, regardless of the timing at which the pre-configuration request is transmitted.

[0326] In the first and second embodiments, the handover pre-configuration is performed by the UE. The handover pre-configuration request may be limited to a case where the UE 50 is currently establishing a PDU session for a predetermined application. The predetermined application is, for example, an application that transmits and receives a large amount of data and requires low latency, such as a metaverse application. Whether the UE 50 is currently establishing a PDU session for the target application can be obtained, for example, by the NEF 3 inquiring of the UDM 2. When the UE 50 is currently establishing a PDU session for the predetermined application, the NEF 3 sends a handover pre-configuration request to the current AMF, and the UE 50 may decide not to perform handover pre-configuration if a PDU session is not being established for a given application.

[0327] In the first and second embodiments, the QoS of a specific application is configured in accordance with the handover pre-configuration and the PDU session pre-configuration, but in addition to this, a network slice selection policy may also be configured.

[0328] In the first and second embodiments, the pre-configuration information held by each NF may be deleted from each NF when triggered by the expiration of a timer, reflection in a context, or receipt of a response to a pre-configuration request.

[0329] In the first and second embodiments, the NEF 3 sends a pre-configuration request to the current AMF, but is not limited to this. The NEF 4 performs the AMF selection, SMF selection, and The UPF may select a UPF and notify each AMF and each SMF of the selection result along with a pre-configuration request. Information used for these NF selections may be collected, for example, from the UDM 2, the NWDAF 8, and each NF.

[0330] Although the first and second embodiments have been described assuming a 5G system, the present invention is not limited to this. The techniques described in the first and second embodiments may be applied to, for example, systems of mobile communication methods of 5G and later generations.

[0331] The processes and means described in this disclosure can be freely combined and implemented as long as no technical contradiction occurs.

[0332] Furthermore, a process described as being performed by one device may be shared and executed by multiple devices. Alternatively, a process described as being performed by different devices may be executed by a single device. In a computer system, the hardware configuration (server configuration) by which each function is realized can be flexibly changed.

[0333] The present disclosure can also be realized by providing a computer program implementing the functions described in the above embodiments to a computer, and having one or more processors in the computer read and execute the program. Such a computer program may be provided to the computer via a non-transitory computer-readable storage medium connectable to the computer's system bus or via a network. Non-transitory computer-readable storage media include, for example, any type of disk, such as a magnetic disk (e.g., a floppy disk, a hard disk drive (HDD), etc.), an optical disk (e.g., a CD-ROM, a DVD disk, a Blu-ray disk), a read-only memory (ROM), a random-access memory (RAM), an EPROM, an EEPROM, a magnetic card, a flash memory, an optical card, or any type of medium suitable for storing electronic instructions. [Explanation of symbols]

[0334] 1··AF 2. UDM 3··NEF 4. UDR 5··PCF 6··SMF 7. AMF 8··NWDAF 10··5G Core 11, 31, 61, 71 Control section 32 Geographical Information Conversion Unit 50··UE 62, 72: Setting information storage section 100 Communication Systems 101 Processor 102 Memory 103...Auxiliary storage device 104··Communications Department 110 Information processing device

Claims

1. Based on first information including information about one or more cells in which a UE (User Equipment) is predicted to be present as the UE moves, second information to be used in providing wireless communication to the UE when the UE moves from or to a first cell that is a serving cell among the one or more cells is acquired before the UE moves from or to the first cell; When the UE moves from or to the first cell, performing a first process related to providing wireless communication to the UE using the second information without performing a process related to acquiring the second information; A plurality of NFs (Network Functions) that execute the above, A system comprising:

2. The plurality of NFs are and further storing the second information in a storage unit so that the second information is clearly indicated as being preset. The system of claim 1 .

3. The plurality of NFs are When a request is sent to another NF using the second information during the execution of the first process, the request is sent together with information indicating that the second information has been preset. The system of claim 2 .

4. The plurality of NFs are When a request accompanied by information indicating that the information is pre-configured is received from another NF during execution of the first process, the storage unit is searched for the second information. The system of claim 3.

5. The plurality of NFs are acquiring the second information by executing a second process that is a part of the first process; The system of claim 1 .

6. obtaining the first information; transmitting, to a second NF among the plurality of NFs, a first request requesting pre-configuration of wireless communication for the UE and the first information; a first NF that executes The plurality of NFs acquire the second information when the second NF receives the first request. The system of claim 1 .

7. The first NF is acquiring the first information from route information held by the UE; The system of claim 6.

8. The first NF is acquiring the first information from a Network Data Analytics Function (NWDAF); The system of claim 6.

9. The second NF is The AMF (Access and Mobility Management Function) in charge of managing the mobility of the UE ) and receiving the first request; transmitting a second request to a third NF having at least one of the one or more cells included in the first information as a serving cell, the second request requesting pre-configuration of wireless communication for the UE; Run The third NF performs pre-configuration related to wireless communication for the UE when receiving the second request. The system of claim 6.

10. The second NF is When the first information includes a cell other than a cell served by the second NF, transmitting the second request as the third NF to an AMF that is in charge of a cell other than a cell served by the second NF included in the first information; The system of claim 9, wherein the system executes:

11. The second NF is When the first information includes a cell other than the cell served by the second NF, an AMF is selected as the third NF from the plurality of NFs based on the first information, and information about the third NF is acquired as one of the second information; When the UE moves from a cell served by the second NF as the first cell to a cell served by an AMF as the third NF, the handover process as the first process is performed using the acquired information about the third NF without selecting an AMF. The system of claim 10.

12. One or more AMFs included in the plurality of NFs When the first request or the second request is received, and the serving cell of one or more own AMFs included in the first information includes a second serving cell other than a serving cell of a first SMF (Session Management Function) that is managing a first session established by the UE. If the second cell includes the first SMF, send a third request to the first SMF and a second SMF that may manage the first session in the second cell, requesting pre-configuration of wireless communication for the UE; When the first SMF and the second SMF receive the third request, they perform pre-configuration for handover of the first session. The system of claim 9.

13. The one or more AMFs Selecting the second SMF from the plurality of NFs based on the first information, and acquiring information about the selected second SMF as one piece of the second information; When the UE moves to the second cell as the first cell, the handover process as the first process is performed using the acquired information on the second SMF without selecting an SMF. The system of claim 12.

14. The first SMF comprises: When the third request is received, and when a third cell other than a serving cell of a first UPF establishing the first session is included in the serving cells of one or more of the first SMFs included in the first information, the third cell is and selecting a second UPF with which the first session may be established, thereby acquiring information about the selected second UPF as one piece of second information; When the UE moves to the third cell as the first cell, a process related to handover as the first process is executed using the acquired information on the second UPF without selecting a UPF. The system of claim 12.

15. The second SMF comprises: When the third request is received, selecting a third UPF that may establish the first session in the second cell based on the first information, and acquiring information about the selected third UPF as one piece of the second information; When the UE moves to the second cell as the first cell, the process related to handover as the first process is executed using the acquired information on the third UPF without selecting a UPF. The system of claim 12.

16. The second NF is When receiving the first request, the third NF sets at least one fourth cell among the one or more cells included in the first information as a serving cell, and when the UE requests establishment of a second session in the fourth cell, transmits a fourth request to a third SMF that may manage the second session, requesting pre-configuration of wireless communication for the UE; Run The third SMF, when receiving the fourth request, pre-configures the UE regarding the establishment of the second session. The system of claim 9.

17. The second NF is By selecting the third SMF from among the plurality of NFs based on the first information, information on the third SMF is acquired as one of the second information; When the UE requests the establishment of the second session in the fourth cell, the process for establishing the second session as the first process is performed using information about the third SMF without selecting the SMF.

17. The system of claim 16.

18. The third SMF comprises: When the fourth request is received, by selecting a UPF that may establish the second session in the fourth cell based on the first information, information about the selected UPF is acquired as one piece of the second information; When the UE requests establishment of the second session in the fourth cell, the process for establishing the second session as the first process is performed using information about the UPF without selecting a UPF.

17. The system of claim 16.

19. NF (Network Function) Based on first information including information about one or more cells in which the UE is predicted to be present as the UE moves, second information is acquired, before the UE moves from or to a first cell that is a serving cell among the one or more cells, to be used for providing wireless communication to the UE when the UE moves from or to the first cell; When the UE moves from or to the first cell, performing a first process related to providing wireless communication to the UE using the second information without performing a process related to acquiring the second information; A method comprising:

20. Based on first information including information about one or more cells in which the UE is predicted to be present as the UE moves, second information is acquired, before the UE moves from or to a first cell that is a serving cell among the one or more cells, to be used for providing wireless communication to the UE when the UE moves from or to the first cell; When the UE moves from or to the first cell, performing a first process related to providing wireless communication to the UE using the second information without performing a process related to acquiring the second information; A control unit that executes Information processing device.

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