UE(User Equipment)

Abstract

Provided is user equipment (UE) comprising a transceiver and a control unit. The transceiver receives a registration acceptance message including Allowed NSSAI from an AMF, and receives a UE policy management command message including URSP from a PCF, the Allowed NSSAI including first S-NSSAI for IMS services, the URSP including first S-NSSAI and first information, and the first information indicating a registration area in which the first S-NSSAI can be used. The control unit selects the first S-NSSAI for IMS services when, during a request for establishment of a PDU session for IMS services, it is determined on the basis of the URSP that the first S-NSSAI included in the Allowed NSSAI can be used in the current registration area.

Description

[Technical Field]

[0001] One aspect of the present invention relates to a UE (User Equipment). This application claims priority to Japanese Patent Application No. 2020-157079, filed on September 18, 2020, the contents of which are incorporated herein by reference. [Background technology]

[0002] The 3GPP (3rd Generation Partnership Project) is studying the system architecture of the 5G System (5GS), a fifth-generation (5G) mobile communication system, and is discussing how to support new procedures and new functions (see Non-Patent Documents 1 to 3). The initial release of the 5G standard, Release 15, introduced the concept of network slicing, and Release 17 is considering functional extensions of network slicing related to the IP Multimedia Subsystem (IMS) (see Non-Patent Document 4). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 3GPP TS 23.501 V16.5.1 (2020-08); 3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; System Architecture for the 5G System; Stage 2 (Release 16) [Non-patent document 2] 3GPP TS 23.502 V16.5.1 (2020-08); 3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Procedures for the 5G System; Stage 2 (Release 16) [Non-patent document 3] 3GPP TS 24.501 V16.5.1 (2020-08); 3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; Non-Access-Stratum (NAS) protocol for 5G System (5GS); Stage 3 (Release 16) [Non-patent document 4] 3GPP TR 23.794 V17.0.0 (2019-12); 3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Study on enhanced IP Multimedia Subsystem (IMS) to 5GC integration (Release 17); Pages 10-12, 37-42 Summary of the Invention [Problem to be solved by the invention]

[0004] However, Non-Patent Document 4 does not make clear how to select the S-NSSAI to be used for communication for IMS (hereinafter also referred to as IMS service) using SIP (Session Initiation Protocol), taking into account the registration area (hereinafter also referred to as RA).

[0005] The object of one aspect of the present invention has been made in consideration of the above circumstances, and is to provide a method for appropriately selecting an S-NSSAI to be used for communication for IMS services in 5GS, taking into account the registration area. [Means for solving the problem]

[0006] In addition, one embodiment of the UE of the present invention comprises a transceiver unit and a control unit, wherein the transceiver unit receives a registration accept message including an Allowed NSSAI (Network Slice Selection Assistance Information) from an AMF (Access and Mobility Management Function) and receives a UE policy management command message including an URSP (UE Route Selection Policy) from a PCF (Policy Control Function), wherein the Allowed NSSAI includes a first S-NSSAI (Single Network Slice Selection Assistance Information) for an IMS service, the URSP includes the first S-NSSAI and first information, and the first information is information indicating a registration area in which the first S-NSSAI can be used, and when the control unit requests establishment of a PDU session for an IMS service, if it determines based on the URSP that the first S-NSSAI included in the Allowed NSSAI is usable in the current registration area, it selects the first S-NSSAI for the IMS service. [Effects of the Invention]

[0007] According to one aspect of the present invention, in 5GS, the S-NSSAI to be used for communication for IMS services can be appropriately selected taking into account the registration area. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an outline of a mobile communication system (EPS / 5GS). [Figure 2] FIG. 1 is a diagram illustrating the detailed configuration of a mobile communication system (EPS / 5GS). [Figure 3] FIG. 1 is a diagram illustrating the device configuration of a UE. [Figure 4] A diagram explaining the configuration of an access network device (gNB) in 5GS. [Figure 5] A diagram explaining the configuration of core network devices (AMF / SMF / UPF / PCF, etc.) in 5GS. [Figure 6] FIG. 10 is a diagram illustrating a registration procedure. [Figure 7] FIG. 10 is a diagram illustrating a generic UE configuration update procedure. [Figure 8] FIG. 10 is a diagram illustrating a UE policy management procedure. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a best mode for carrying out one aspect of the present invention will be described with reference to the drawings. In this embodiment, an embodiment of a mobile communication system to which one aspect of the present invention is applied will be described as an example.

[0010] [1. System Overview] First, FIG. 1 is a diagram for explaining an outline of a mobile communication system 1 used in each embodiment, and FIG. 2 is a diagram for explaining a detailed configuration of the mobile communication system 1. As shown in FIG.

[0011] FIG. 1 shows that the mobile communication system 1 is composed of UE_A10, access network _A80, core network _A90, PDN (Packet Data Network) _A5, access network _B120, core network _B190, and DN (Data Network) _A6.

[0012] In the following, these devices and functions may be referred to by abbreviating the symbols, such as UE, access network_A, core network_A, PDN, access network_B, core network_B, DN, etc.

[0013] Figure 2 also shows devices and functions such as UE_A10, E-UTRAN80, MME40, SGW35, PGW-U30, PGW-C32, PCRF60, HSS50, 5G AN120, AMF140, UPF130, SMF132, PCF160, UDM150, and N3IWF170, as well as interfaces that connect these devices and functions to each other.

[0014] In the following, these devices and functions may be referred to by abbreviated symbols such as UE, E-UTRAN, MME, SGW, PGW-U, PGW-C, PCRF, HSS, 5G AN, AMF, UPF, SMF, PCF, UDM, N3IWF, etc.

[0015] The 4G system EPS (Evolved Packet System) includes an access network _A and a core network _A, but may further include a UE and / or a PDN. The 5G system 5GS (5G System) includes a UE, an access network _B, and a core network _B, but may further include a DN.

[0016] A UE is a device that can connect to a network service via 3GPP access (also referred to as a 3GPP access network, or 3GPP AN) and / or non-3GPP access (also referred to as a non-3GPP access network, or non-3GPP AN). A UE may be a terminal device capable of wireless communication, such as a mobile phone or a smartphone, and may be a terminal device that can connect to both EPS and 5GS. A UE may include a UICC (Universal Integrated Circuit Card) or an eUICC (Embedded UICC). Note that a UE may be referred to as a user device or a terminal device.

[0017] Furthermore, access network_A corresponds to an E-UTRAN (Evolved Universal Terrestrial Radio Access Network) and / or a wireless LAN access network. One or more eNBs (evolved Node Bs) 45 are deployed in the E-UTRAN. Note that, hereinafter, the eNB 45 may be referred to by abbreviating the symbol eNB. If there are multiple eNBs, the eNBs are connected to each other, for example, via an X2 interface. Furthermore, one or more access points are deployed in the wireless LAN access network.

[0018] Furthermore, access network_B corresponds to a 5G access network (5G AN). The 5G AN is composed of an NG-RAN (NG Radio Access Network) and / or a non-3GPP access network. One or more gNBs (NR NodeBs) 122 are deployed in the NG-RAN. Note that, hereinafter, the gNB 122 may be referred to by its symbol abbreviated as eNB. The gNB is a node that provides the NR (New Radio) user plane and control plane to UEs and connects to the 5GCN via an NG interface (including an N2 interface or an N3 interface). In other words, the gNB is a base station device newly designed for 5GS, and has different functions from the base station device (eNB) used in the 4G EPS system. Furthermore, when there are multiple gNBs, the gNBs are connected to each other, for example, via an Xn interface.

[0019] Furthermore, the non-3GPP access network may be an untrusted non-3GPP access network or a trusted non-3GPP access network. Here, the untrusted non-3GPP access network may be a non-3GPP access network that does not perform security management within the access network, such as a public wireless LAN. On the other hand, the trusted non-3GPP access network may be an access network specified by 3GPP, and may include a trusted non-3GPP access point (TNAP) and a trusted non-3GPP gateway function (TNGF).

[0020] In the following, E-UTRAN and NG-RAN may be referred to as 3GPP access. Also, wireless LAN access networks and non-3GPP AN may be referred to as non-3GPP access. Also, nodes located in access network_B may be collectively referred to as NG-RAN nodes.

[0021] Furthermore, in the following, access network _A, and / or access network _B, and / or devices included in access network _A, and / or devices included in access network _B may be referred to as access networks or access network devices.

[0022] The core network_A corresponds to an EPC (Evolved Packet Core), which includes, for example, an MME (Mobility Management Entity), an SGW (Serving Gateway), a PGW (Packet Data Network Gateway)-U, a PGW-C, a PCRF (Policy and Charging Rules Function), and an HSS (Home Subscriber Server).

[0023] Furthermore, the core network_B corresponds to a 5G Core Network (5GCN). In the 5GCN, for example, an Access and Mobility Management Function (AMF), a User Plane Function (UPF), a Session Management Function (SMF), a Policy Control Function (PCF), a Unified Data Management (UDM), etc. are arranged. Here, the 5GCN may be expressed as a 5GC.

[0024] In addition, in the following, core network _A and / or core network _B, devices included in core network _A, and / or devices included in core network _B may be referred to as core networks, core network devices, or devices within the core network.

[0025] The core network (core network _A and / or core network _B) may be an IP mobile communication network operated by a mobile network operator (MNO) that connects the access network (access network _A and / or access network _B) to the PDN and / or DN, or it may be a core network for a mobile network operator that operates and manages the mobile communication system 1, or it may be a core network for a virtual mobile communication operator or virtual mobile communication service provider such as an MVNO (Mobile Virtual Network Operator) or MVNE (Mobile Virtual Network Enabler).

[0026] Also, while FIG. 1 illustrates a case where the PDN and the DN are the same, they may be different. The PDN may be a DN (Data Network) that provides communication services to the UE. The DN may be configured as a packet data service network, or may be configured for each service. Furthermore, the PDN may include a connected communication terminal. Therefore, connecting to the PDN may mean connecting to a communication terminal or a server device located in the PDN. Furthermore, transmitting and receiving user data to and from the PDN may mean transmitting and receiving user data to and from a communication terminal or a server device located in the PDN. The PDN may be referred to as the DN, and the DN may be referred to as the PDN.

[0027] In addition, hereinafter, at least a portion of the access network _A, the core network _A, the PDN, the access network _B, the core network _B, and the DN, and / or one or more devices included therein may be referred to as a network or a network device. In other words, when a network and / or a network device sends or receives a message and / or performs a procedure, it means that at least a portion of the access network _A, the core network _A, the PDN, the access network _B, the core network _B, and the DN, and / or one or more devices included therein send or receive a message and / or perform a procedure.

[0028] The UE can also connect to an access network. The UE can also connect to a core network via the access network. The UE can also connect to a PDN or DN via the access network and the core network. That is, the UE can transmit and receive (communicate) user data with the PDN or DN. When transmitting and receiving user data, not only IP (Internet Protocol) communication but also non-IP communication can be used.

[0029] Here, IP communication refers to data communication using IP, and data is transmitted and received using IP packets. An IP packet consists of an IP header and a payload. The payload may include data transmitted and received by devices and functions included in EPS or devices and functions included in 5GS. Non-IP communication refers to data communication that does not use IP, and data is transmitted and received in a format different from the IP packet structure. For example, non-IP communication may be data communication achieved by transmitting and receiving application data without an IP header, or it may be user data transmitted and received by a UE with a different header, such as a MAC header or an Ethernet (registered trademark) frame header, added.

[0030] In addition, access network _A, core network _A, access network _B, core network _B, PDN_A, and DN_A may be configured with devices not shown in Fig. 2. For example, core network _A and / or core network _B may include an AUSF (Authentication Server Function) and an AAA (Authentication, authorization, and accounting) server (AAA-S).

[0031] Here, the AUSF is a core network device having an authentication function for 3GPP access and non-3GPP access, specifically, a network function unit that receives an authentication request for 3GPP access and / or non-3GPP access from a UE and executes the authentication procedure.

[0032] The AAA server is a device that has authentication, authorization, and accounting functions and is connected to the AUSF directly or indirectly via another network device. The AAA server may be a network device within the core network. The AAA server may not be included in the core network _A and / or core network _B, but may be included in the PLMN. In other words, the AAA server may be a core network device or a device outside the core network. For example, the AAA server may be a server device within the PLMN managed by a third party.

[0033] 2, for the sake of simplicity, each device and function is shown one by one, but multiple similar devices and functions may be configured in the mobile communication system 1. Specifically, the mobile communication system 1 may be configured with multiple devices and functions such as UE_A10, E-UTRAN80, MME40, SGW35, PGW-U30, PGW-C32, PCRF60, HSS50, 5G AN120, AMF140, UPF130, SMF132, PCF160, and / or UDM150.

[0034] [2. Configuration of each device] Next, the configuration of each device (UE, and / or access network device, and / or core network device) used in each embodiment will be described with reference to the drawings. Each device may be configured as physical hardware, as logical (virtual) hardware configured on general-purpose hardware, or as software. Furthermore, at least a part (including all) of the functions of each device may be configured as physical hardware, logical hardware, or software.

[0035] Note that each memory unit (memory unit_A340, memory unit_A440, memory unit_B540, memory unit_A640, memory unit_B740) in each device / function mentioned below is configured with, for example, a semiconductor memory, a solid state drive (SSD), a hard disk drive (HDD), etc. Furthermore, each memory unit can store not only information that was originally set at the time of shipment, but also various information transmitted and received between devices / functions other than the device / function itself (e.g., UE, and / or access network device, and / or core network device, and / or PDN, and / or DN). Furthermore, each memory unit can store identification information, control information, flags, parameters, etc. included in control messages transmitted and received in various communication procedures described below. Furthermore, each memory unit may store this information for each UE. Furthermore, when interworking between 5GS and EPS is performed, each memory unit can store control messages and user data transmitted and received between 5GS and / or devices / functions included in EPS. At this time, not only those transmitted and received via the N26 interface but also those transmitted and received without going through the N26 interface can be stored.

[0036] [2.1. UE Device Configuration] First, an example of the device configuration of UE (User Equipment) will be explained using Figure 3. The UE is composed of a control unit _A300, an antenna 310, a transceiver unit _A320, and a memory unit _A340. The control unit _A300, the transceiver unit _A320, and the memory unit _A340 are connected via a bus. The transceiver unit _A320 is connected to the antenna 310.

[0037] The control unit _A300 is a functional unit that controls the operation and functions of the entire UE.The control unit _A300 realizes various processing in the UE by reading and executing various programs stored in the memory unit _A340 as necessary.

[0038] The transceiver unit _A320 is a functional unit for wireless communication with a base station device (eNB or gNB) in the access network via an antenna. That is, the UE can use the transceiver unit _A320 to transmit and receive user data and / or control information between an access network device, and / or a core network device, and / or a PDN, and / or a DN.

[0039] Explaining in detail with reference to Figure 2, the UE can communicate with a base station device (eNB) in the E-UTRAN via the LTE-Uu interface by using the transceiver unit _A320. The UE can also communicate with a base station device (gNB) in the 5G AN by using the transceiver unit _A320. The UE can also transmit and receive AMF and NAS (Non-Access-Stratum) messages via the N1 interface by using the transceiver unit _A320. However, since the N1 interface is logical, in reality, communication between the UE and the AMF is performed via the 5G AN.

[0040] The memory unit _A340 is a functional unit for storing programs, user data, control information, etc. necessary for each operation of the UE.

[0041] [2.2. gNB device configuration] Next, an example of the gNB device configuration will be described using Figure 4. The gNB is composed of a control unit _B500, an antenna 510, a network connection unit _B520, a transceiver unit _B530, and a memory unit _B540. The control unit _B500, the network connection unit _B520, the transceiver unit _B530, and the memory unit _B540 are connected via a bus. The transceiver unit _B530 is connected to the antenna 510.

[0042] The control unit _B500 is a functional unit that controls the operation and functions of the entire gNB. The control unit _B500 realizes various processes in the gNB by reading and executing various programs stored in the memory unit _B540 as necessary.

[0043] The network connection unit _B520 is a functional unit for the gNB to communicate with the AMF and / or UPF. That is, the gNB can send and receive user data and / or control information between the AMF and / or UPF using the network connection unit _B520.

[0044] The transceiver unit _B530 is a functional unit for wireless communication with the UE via the antenna 510. That is, the gNB can transmit and receive user data and / or control information to and from the UE using the transceiver unit _B530.

[0045] 2, a gNB in ​​a 5G AN can communicate with an AMF via an N2 interface by using a network connection unit _B 520, and can communicate with a UPF via an N3 interface, and can communicate with a UE by using a transceiver unit _B 530.

[0046] The memory unit _B540 is a functional unit for storing programs, user data, control information, etc. necessary for each operation of the gNB.

[0047] [2.3. AMF device configuration] Next, an example of the AMF device configuration will be explained using Figure 5. The AMF is composed of a control unit _B700, a network connection unit _B720, and a memory unit _B740. The control unit _B700, the network connection unit _B720, and the memory unit _B740 are connected via a bus. The AMF may be a node that handles the control plane.

[0048] The control unit _B700 is a functional unit that controls the operation and functions of the entire AMF.The control unit _B700 realizes various processing in the AMF by reading and executing various programs stored in the memory unit _B740 as necessary.

[0049] The network connection unit _B720 is a functional unit for the AMF to connect to a base station device (gNB), and / or SMF, and / or PCF, and / or UDM, and / or SCEF in a 5G AN. In other words, the AMF can use the network connection unit _B720 to send and receive user data and / or control information between a base station device (gNB), and / or SMF, and / or PCF, and / or UDM, and / or SCEF in a 5G AN.

[0050] Explaining in detail with reference to FIG. 2, the AMF in the 5GCN can communicate with a gNB via the N2 interface by using the network connection unit _A620, can communicate with a UDM via the N8 interface, can communicate with an SMF via the N11 interface, and can communicate with a PCF via the N15 interface. The AMF can also send and receive NAS messages with a UE via the N1 interface by using the network connection unit _A620. However, since the N1 interface is logical, communication between the UE and the AMF is actually performed via a 5G AN. Furthermore, if the AMF supports the N26 interface, it can communicate with an MME via the N26 interface by using the network connection unit _A620.

[0051] The memory unit _B740 is a functional unit for storing programs, user data, control information, etc. necessary for each operation of the AMF.

[0052] The AMF has functions such as exchanging control messages with the RAN using the N2 interface, exchanging NAS messages with the UE using the N1 interface, encrypting and protecting the integrity of NAS messages, registration management (RM) functions, connection management (CM) functions, reachability management functions, mobility management functions for UEs, etc., transferring SM (Session Management) messages between the UE and the SMF, access authentication (Access Authorization) functions, security anchor functionality (SEA), security context management (SCM), a function to support the N2 interface for the N3IWF (Non-3GPP Interworking Function), a function to support sending and receiving NAS signals with the UE via the N3IWF, and a function to authenticate UEs connected via the N3IWF.

[0053] In addition, registration management manages the RM state for each UE. The RM state may be synchronized between the UE and the AMF. The RM state includes an unregistered state (RM-DEREGISTERED state) and a registered state (RM-REGISTERED state). In the RM-DEREGISTERED state, the UE is not registered with the network, and therefore the UE context in the AMF does not have valid location information or routing information for the UE, and therefore the AMF cannot reach the UE. In the RM-REGISTERED state, the UE is registered with the network, and therefore the UE can receive services that require registration with the network. Note that the RM state may also be expressed as a 5GMM state. In this case, the RM-DEREGISTERED state may be expressed as a 5GMM-DEREGISTERED state, and the RM-REGISTERED state may be expressed as a 5GMM-REGISTERED state.

[0054] In other words, 5GMM-REGISTERED may be a state in which each device has established a 5GMM context or a PDU session context. When each device is 5GMM-REGISTERED, UE_A10 may start transmitting and receiving user data and control messages, or may respond to paging. Furthermore, when each device is 5GMM-REGISTERED, UE_A10 may perform registration procedures other than the registration procedure for initial registration, and / or service request procedures.

[0055] Furthermore, 5GMM-DEREGISTERED may be a state in which each device has not established a 5GMM context, a state in which UE_A10's location information is not known to the network, or a state in which UE_A10 is unreachable from the network. Note that when each device is 5GMM-DEREGISTERED, UE_A10 may initiate a registration procedure or may establish a 5GMM context by performing the registration procedure.

[0056] In addition, connection management manages the CM state for each UE. The CM state may be synchronized between the UE and the AMF. The CM state includes a non-connected state (CM-IDLE state) and a connected state (CM-CONNECTED state). In the CM-IDLE state, the UE is in the RM-REGISTERED state but does not have a NAS signaling connection established with the AMF via the N1 interface. In the CM-IDLE state, the UE does not have an N2 interface connection or an N3 interface connection. On the other hand, in the CM-CONNECTED state, the UE has a NAS signaling connection established with the AMF via the N1 interface. In the CM-CONNECTED state, the UE may have an N2 interface connection and / or an N3 interface connection.

[0057] Furthermore, in connection management, the CM state in 3GPP access and the CM state in non-3GPP access may be managed separately. In this case, the CM state in 3GPP access may include a non-connected state in 3GPP access (CM-IDLE state over 3GPP access) and a connected state in 3GPP access (CM-CONNECTED state over 3GPP access). Furthermore, the CM state in non-3GPP access may include a non-connected state in non-3GPP access (CM-IDLE state over non-3GPP access) and a connected state in non-3GPP access (CM-CONNECTED state over non-3GPP access). Note that the non-connected state may be expressed as an idle mode, and the connected state mode may be expressed as a connected mode.

[0058] The CM state may be expressed as a 5GMM mode. In this case, the unconnected state may be expressed as a 5GMM-IDLE mode, and the connected state may be expressed as a 5GMM-CONNECTED mode. Furthermore, the unconnected state in 3GPP access may be expressed as a 5GMM-IDLE mode over 3GPP access, and the connected state in 3GPP access may be expressed as a 5GMM-CONNECTED mode over 3GPP access. Furthermore, the unconnected state in non-3GPP access may be expressed as 5GMM unconnected mode in non-3GPP access (5GMM-IDLE mode over non-3GPP access), and the connected state in non-3GPP access may be expressed as 5GMM connected mode in non-3GPP access (5GMM-CONNECTED mode over non-3GPP access). Note that the 5GMM unconnected mode may be expressed as idle mode, and the 5GMM connected mode may be expressed as connected mode.

[0059] In addition, one or more AMFs may be placed in the core network B. In addition, the AMF may be an NF that manages one or more NSIs (Network Slice Instances). In addition, the AMF may be a shared CP function (CCNF; Common CPNF (Control Plane Network Function)) shared among multiple NSIs.

[0060] In addition, the N3IWF is a device and / or function located between the non-3GPP access and the 5GCN when the UE connects to the 5GS via the non-3GPP access.

[0061] [2.4. SMF device configuration] Next, an example of the SMF device configuration will be explained using Figure 5. The SMF is composed of a control unit _B700, a network connection unit _B720, and a memory unit _B740. The control unit _B700, the network connection unit _B720, and the memory unit _B740 are connected via a bus. The SMF may be a node that handles the control plane.

[0062] The control unit _B700 is a functional unit that controls the operation and functions of the entire SMF.The control unit _B700 realizes various processing in the SMF by reading and executing various programs stored in the memory unit _B740 as necessary.

[0063] The network connection unit _B720 is a functional unit for the SMF to connect with the AMF, and / or UPF, and / or PCF, and / or UDM. In other words, the SMF can send and receive user data and / or control information between the AMF, and / or UPF, and / or PCF, and / or UDM using the network connection unit _B720.

[0064] Explaining in more detail with reference to Figure 2, the SMF in the 5GCN can communicate with the AMF via the N11 interface, with the UPF via the N4 interface, with the PCF via the N7 interface, and with the UDM via the N10 interface by using the network connection unit _A620.

[0065] The memory unit _B740 is a functional unit for storing programs, user data, control information, etc. required for each operation of the SMF.

[0066] The SMF has session management functions such as establishing, modifying, and releasing PDU sessions, IP address allocation for UEs and its management, UPF selection and control, UPF configuration for routing traffic to the appropriate destination, sending and receiving the SM portion of NAS messages, Downlink Data Notification, providing AN-specific (for each AN) SM information to be sent to the AN via the N2 interface via the AMF, determining the SSC mode (Session and Service Continuity mode) for the session, and roaming functions.

[0067] [2.5. UPF device configuration] Next, an example of the device configuration of the UPF will be explained using Figure 5. The UPF is composed of a control unit _B700, a network connection unit _B720, and a memory unit _B740. The control unit _B700, the network connection unit _B720, and the memory unit _B740 are connected via a bus. The UPF may be a node that handles the control plane.

[0068] The control unit _B700 is a functional unit that controls the operation and functions of the entire UPF.The control unit _B700 realizes various processing in the UPF by reading and executing various programs stored in the memory unit _B740 as necessary.

[0069] The network connection unit _B720 is a functional unit for the UPF to connect to a base station device (gNB), and / or SMF, and / or DN within the 5G AN. In other words, the UPF can use the network connection unit _B720 to transmit and receive user data and / or control information between the base station device (gNB), and / or SMF, and / or DN within the 5G AN.

[0070] Explaining in more detail with reference to Figure 2, a UPF in a 5GCN can communicate with a gNB via the N3 interface, with an SMF via the N4 interface, with a DN via the N6 interface, and with other UPFs via the N9 interface by using the network connection unit _A620.

[0071] The memory unit _B740 is a functional unit for storing programs, user data, control information, etc. required for each operation of the UPF.

[0072] The UPF has functions such as an anchor point for intra-RAT mobility or inter-RAT mobility, an external PDU session point for interconnecting to DNs (i.e., a gateway between DNs and core network_B that forwards user data), packet routing and forwarding functions, an UL CL (Uplink Classifier) ​​function that supports routing of multiple traffic flows to one DN, a branching point function that supports multi-homed PDU sessions, a QoS (Quality of Service) processing function for the user plane, an uplink traffic verification function, downlink packet buffering, and a function to trigger downlink data notifications.

[0073] The UPF may also be a gateway for IP communication and / or non-IP communication. The UPF may also have a function for forwarding IP communication and a function for converting non-IP communication and IP communication. Furthermore, multiple gateways may be gateways that connect the core network_B to a single DN. The UPF may also have connectivity with other NFs and may be connected to each device via other NFs.

[0074] The user plane refers to user data transmitted and received between a UE and a network. The user plane may be transmitted and received using a PDN connection or a PDU session. Furthermore, in the case of EPS, the user plane may be transmitted and received using the LTE-Uu interface, and / or the S1-U interface, and / or the S5 interface, and / or the S8 interface, and / or the SGi interface. Furthermore, in the case of 5GS, the user plane may be transmitted and received via the interface between the UE and the NG RAN, and / or the N3 interface, and / or the N9 interface, and / or the N6 interface. Hereinafter, the user plane may be referred to as the U-Plane.

[0075] Furthermore, the control plane refers to control messages transmitted and received to control UE communications, etc. The control plane may be transmitted and received using a NAS (Non-Access-Stratum) signaling connection between the UE and MME. Furthermore, in the case of EPS, the control plane may be transmitted and received using the LTE-Uu interface and the S1-MME interface. Furthermore, in the case of 5GS, the control plane may be transmitted and received using the interface between the UE and NG RAN and the N2 interface. Hereinafter, the control plane may be referred to as the control plane or the C-Plane.

[0076] Furthermore, the U-Plane (User Plane; UP) may be a communication path for transmitting and receiving user data and may be composed of multiple bearers. Furthermore, the C-Plane (Control Plane; CP) may be a communication path for transmitting and receiving control messages and may be composed of multiple bearers.

[0077] [2.6. PCF device configuration] Next, an example of the device configuration of the PCF used in each embodiment will be described using Figure 5. The PCF is composed of a control unit 700, a network connection unit 720, and a memory unit 740. The control unit 700, the network connection unit 720, and the memory unit 740 are connected via a bus.

[0078] The control unit _700 is a functional unit that controls the operation and functions of the entire PCF. Note that the control unit _700 may process all functions that other functional units in the PCF (network connection unit _720, memory unit _740) do not have. The control unit _700 realizes various processes in the PCF by reading and executing various programs stored in the memory unit _740 as needed.

[0079] The network connection unit _720 is a functional unit for connecting the PCF to the AMF, and / or SMF, and / or AF (Application Function). That is, the PCF can use the network connection unit _720 to send and receive control information between the AMF, and / or SMF, and / or AF.

[0080] By using the network connection section _720, the PCF can communicate with the AMF via the N15 interface, with the SMF via the N7 interface, and with the AF via the N5 interface (the interface between the PCF and the AF).

[0081] The memory unit _740 is a functional unit for storing programs, user data, control information, etc. required for each operation of the UPF.

[0082] The PCF has functions to support a unified policy framework, provide policy rules to control plane functions to enforce them, and access subscription information. The PCF also has functions to generate URSP (UE Route Selection Policy) rules, etc. All of these functions may be controlled by the control unit 700.

[0083] [2.7. Explanation of technical terms and identification information in this embodiment] Next, technical terms used in this embodiment will be explained.

[0084] A network refers to at least a portion of an access network _B, a core network _B, and a DN. Furthermore, one or more devices included in at least a portion of an access network _B, a core network _B, and a DN may be referred to as a network or a network device. In other words, when a network transmits, receives, and / or processes messages, it may mean that devices within the network (network devices and / or control devices) transmit, receive, receive, and / or process messages. Conversely, when a device within the network transmits, receives, receives, and / or processes messages, it may mean that the network transmits, receives, receives, and / or processes messages.

[0085] In addition, the SM (Session Management) message (also referred to as an NAS (Non-Access-Stratum) SM message) may be an NAS message used in a procedure for SM (hereinafter also referred to as an SM procedure), or may be a control message transmitted and received between UE_A10 and SMF_A230 via AMF_A240. Furthermore, the SM message may include a PDU session establishment request message, a PDU session establishment accept message, a PDU session establishment reject message, a PDU session modification request message, a PDU session modification command message, a PDU session modification complete message, a PDU session modification command reject message, a PDU session modification reject message, a PDU session release request message, a PDU session release reject message, a PDU session release command message, a PDU session release complete message, etc.

[0086] The procedures for SM may include a PDU session establishment procedure, a PDU session modification procedure, and a UE-requested PDU session release procedure. Each procedure may be initiated by the UE or the NW.

[0087] Furthermore, an MM (Mobility management) message (also referred to as an NAS MM message) may be an NAS message used in procedures for MM, and may be a control message transmitted and received between UE_A10 and AMF_A240. Furthermore, the MM message may include a registration request message, a registration accept message, a registration reject message, a de-registration request message, a de-registration accept message, a configuration update command message, a configuration update complete message, a service request message, a service accept message, a service reject message, a notification message, a notification response message, etc.

[0088] In addition, the procedures for MM or MM procedures may include a registration procedure, a de-registration procedure, a generic UE configuration update procedure, an authentication and authorization procedure, a service request procedure, a paging procedure, and a notification procedure.

[0089] In addition, the 5GS (5G System) service may be a connection service provided using the core network_B190. Furthermore, the 5GS service may be a service different from the EPS service or may be a service similar to the EPS service.

[0090] In addition, non-5GS services may be services other than 5GS services, and may include EPS services and / or non-EPS services.

[0091] Also, the PDN (Packet Data Network) type indicates the type of PDN connection, and can be IPv4, IPv6, IPv4v6, or non-IP. If IPv4 is specified, it indicates that data will be sent and received using IPv4. If IPv6 is specified, it indicates that data will be sent and received using IPv6. If IPv4v6 is specified, it indicates that data will be sent and received using either IPv4 or IPv6. If non-IP is specified, it indicates that communication will not be via IP, but via a communication method other than IP.

[0092] Furthermore, a PDU (Protocol Data Unit / Packet Data Unit) session can be defined as an association between a DN that provides a PDU connectivity service and a UE, but it may also be connectivity established between a UE and an external gateway. In 5GS, a UE can transmit and receive user data to and from a DN by establishing a PDU session via an access network _B and a core network _B. Here, this external gateway may be a UPF, SCEF, or the like. The UE can transmit and receive user data to and from a device such as an application server located in the DN using the PDU session.

[0093] Each device (UE, and / or access network device, and / or core network device) may associate one or more pieces of identification information with a PDU session and manage them. These pieces of identification information may include one or more of the following: DNN, QoS rule, PDU session type, application identification information, NSI identification information, access network identification information, and SSC mode, or may further include other information. Furthermore, when multiple PDU sessions are established, the identification information associated with the PDU sessions may be the same or different.

[0094] Furthermore, the DNN (Data Network Name) may be identification information for identifying a core network and / or an external network such as a DN. Furthermore, the DNN can also be used as information for selecting a gateway such as PGW_A30 / UPF_A235 that connects the core network B190. Furthermore, the DNN may be equivalent to an APN (Access Point Name).

[0095] Furthermore, the PDU (Protocol Data Unit / Packet Data Unit) session type indicates the type of PDU session, and can be IPv4, IPv6, Ethernet, or Unstructured. If IPv4 is specified, it indicates that data will be sent and received using IPv4. If IPv6 is specified, it indicates that data will be sent and received using IPv6. If Ethernet is specified, it indicates that Ethernet frames will be sent and received. Furthermore, Ethernet may indicate that communication using IP is not performed. If Unstructured is specified, it indicates that data will be sent and received to an application server or the like in the DN using Point-to-Point (P2P) tunneling technology. As the P2P tunneling technology, for example, UDP / IP encapsulation technology may be used. In addition to the above, the PDU session type may also include IP. IP can be specified if the UE is capable of using both IPv4 and IPv6.

[0096] A PLMN (Public Land Mobile Network) is a communication network that provides mobile radio communication services. A PLMN is a network managed by an operator, which is a communications carrier, and the operator can be identified by a PLMN ID. A PLMN that matches the MCC (Mobile Country Code) and MNC (Mobile Network Code) of a UE's IMSI (International Mobile Subscriber Identity) may be a Home PLMN (HPLMN). Furthermore, the UE may store an Equivalent HPLMN list in its USIM to identify one or more Equivalent HPLMNs (EPLMNs). A PLMN that is different from the HPLMN and / or EPLMN may be a Visited PLMN (VPLMN). A PLMN to which a UE has successfully registered may be a Registered PLMN (RPLMN).

[0097] A network slice (NS) is a logical network that provides specific network capabilities and network characteristics. UEs and / or networks can support network slices (NW slices; NS) in 5GS. A network slice may also be simply referred to as a slice.

[0098] A network slice instance (NSI) is composed of an instance (entity) of a network function (NF) and a set of required resources, forming a deployed network slice. Here, an NF is a processing function in a network, adopted or defined by 3GPP. An NSI is an entity of one or more NSs configured within a core network _B. An NSI may also be composed of virtual network functions (NFs) generated using a network slice template (NST). Here, an NST is associated with resource requirements for providing required communication services and capabilities, and is a logical representation of one or more NFs. In other words, an NSI may be a collection of multiple NFs within the core network _B 190. An NSI may also be a logical network configured to separate user data delivered by services, etc. One or more NFs may be configured within an NS. The NFs configured in an NS may or may not be devices shared with other NSs. A UE and / or a device in the network can be assigned to one or more NSs based on registration information such as an NSSAI, an S-NSSAI, an UE usage type, an NSI ID, or one or more APNs. The UE usage type is a parameter value included in the UE registration information and used to identify the NSI. The UE usage type may be stored in the HSS. The AMF may select an SMF and a UPF based on the UE usage type.

[0099] Furthermore, S-NSSAI (Single Network Slice Selection Assistance Information) is information for identifying an NS. The S-NSSAI may consist of only an SST (Slice / Service type) or may consist of both an SST and an SD (Slice Differentiator). Here, the SST is information indicating the expected behavior of the NS in terms of functions and services. The SD may be information that interpolates the SST when selecting one NSI from multiple NSIs indicated by the SST. The S-NSSAI may be information specific to each PLMN, or may be standard information common among PLMNs. The network may store one or more S-NSSAIs as default S-NSSAIs in the registration information of the UE. Note that when the S-NSSAI is the default S-NSSAI, if the UE does not send a valid S-NSSAI to the network in a registration request message, the network may provide an NS related to the UE.

[0100] Also, NSSAI (Network Slice Selection Assistance Information) is a collection of S-NSSAIs. Each S-NSSAI included in the NSSAI is information that assists the access network or core network in selecting an NSI. The UE may store the NSSAI authorized by the network for each PLMN. Also, the NSSAI may be information used to select an AMF.

[0101] Furthermore, the requested NSSAI (hereinafter also referred to as the requested NSSAI) is an NSSAI provided from the UE to the network during the registration procedure. The requested NSSAI may be an allowed NSSAI or a configured NSSAI stored by the UE. Specifically, the requested NSSAI may be information indicating a network slice that the UE wishes to access. The S-NSSAI included in the requested NSSAI may be expressed as a requested S-NSSAI. For example, the requested NSSAI is transmitted in a NAS message, such as a registration request message or a PDU session establishment request message, transmitted from the UE to the network, or in a Radio Resource Control (RRC) message including a NAS (Non-Access-Stratum) message.

[0102] Furthermore, the allowed NSSAI (hereinafter also referred to as the permitted NSSAI or the Allowed NSSAI) is information indicating one or more network slices to which the UE is allowed to connect. In other words, the allowed NSSAI is information identifying the network slices to which the network has permitted the UE to connect. The UE and the network each store and manage the allowed NSSAI for each access (3GPP access or non-3GPP access) as UE information. The S-NSSAI included in the allowed NSSAI may be expressed as the allowed S-NSSAI. The allowed S-NSSAI may be configured to include the S-NSSAI and the mapped S-NSSAI. Furthermore, the SST or SD constituting the S-NSSAI included in the allowed NSSAI may indicate an IMS service. In other words, the value of the SST or SD constituting the S-NSSAI included in the allowed NSSAI may correspond to the IMS service. That is, the value of the SST corresponding to the IMS service may be predetermined, and the value of the SD corresponding to the IMS service may be predetermined.

[0103] Furthermore, the first S-NSSAI is information that identifies a network slice corresponding to IMS (hereinafter also referred to as IMS service). In other words, the first S-NSSAI may be information that identifies a network slice that supports communication using IMS. Furthermore, the first S-NSSAI may be included in an Allowed NSSAI or a default NSSAI (hereinafter also referred to as default NSSAI). Furthermore, the first S-NSSAI may be an S-NSSAI stored by the UE and / or NW, or may be an S-NSSAI transmitted from the NW to the UE. Furthermore, the first S-NSSAI for an IMS service may be pre-defined by a specification or an operator.

[0104] The first S-NSSAI may be valid (usable) in the first registration area for IMS services but not valid in the second registration area. The first S-NSSAI may be valid (usable) in the first registration area for IMS services but valid in the second registration area for services other than IMS services.

[0105] Furthermore, the second S-NSSAI is information that identifies a network slice corresponding to IMS. In other words, the second S-NSSAI may be information that identifies a network slice that supports communication using IMS. Furthermore, the second S-NSSAI may be included in the Allowed NSSAI or the default NSSAI. Furthermore, the second S-NSSAI may be an S-NSSAI stored by the UE and / or the NW, or may be an S-NSSAI transmitted from the NW to the UE. Furthermore, the second S-NSSAI for an IMS service may be predefined by a specification or an operator.

[0106] Furthermore, the second S-NSSAI may be an S-NSSAI that is valid (usable) in the second registration area for IMS services, but is valid or not valid in the first registration area.

[0107] Furthermore, the default NSSAI (hereinafter also referred to as default NSSAI) is information including one or more default S-NSSAIs (hereinafter also referred to as default S-NSSAI) corresponding to the IMS (hereinafter also referred to as supporting the IMS service). In other words, the default NSSAI may be information including a default S-NSSAI that supports communication using the IMS. Here, the default S-NSSAI may be the same as or different from the first S-NSSAI. Furthermore, the default NSSAI and / or the default S-NSSAI may be an S-NSSAI stored by the UE and / or NW. Furthermore, the default S-NSSAI may be valid in all PLMNs (hereinafter also referred to as usable or applicable) or may be valid within the current PLMN. Furthermore, the default S-NSSAI for the IMS service may be predefined by a specification or an operator.

[0108] A tracking area (hereinafter also referred to as TA) is a single or multiple ranges managed by the core network that can be represented by the location information of UE_A10. A tracking area may be composed of multiple cells. Furthermore, a tracking area may be an area in which control messages such as paging are broadcast, or an area in which UE_A10 can move without performing a handover procedure. Furthermore, a tracking area may be a routing area, a location area, or anything similar. A tracking area may be identified by a TAI (Tracking Area Identity) consisting of a TAC (Tracking area code) and a PLMN.

[0109] A registration area is a collection of one or more TAs assigned to a UE by the AMF. Note that while UE_A10 is moving within one or more TAs included in the registration area, it may be able to move without sending or receiving signals for tracking area updates. In other words, a registration area may be a group of information indicating an area in which UE_A10 can move without performing a registration procedure. A registration area may be identified by a TAI list consisting of one or more TAIs.

[0110] A URSP (UE Route Selection Policy) may be configured as a list of one or more URSP rules (UE Route Selection Policy Rules), and each URSP rule may be configured as a rule precedence, a traffic descriptor, and / or a list of route selection descriptors.

[0111] Here, the rule priority indicates the order in which the URSP rules are enforced in the UE. When the UE receives a URSP, that is, when it receives one or more URSP rules, it may refer to the priority of each rule and apply the URSP rules in order from the highest priority rule.

[0112] The traffic descriptor indicates when to apply the URSP rule and may consist of application descriptors, IP descriptors, domain descriptors, non-IP descriptors, data network names (DNNs), and connection capabilities.

[0113] Here, the application descriptor may include an OS ID and an OS application ID. The IP descriptor indicates information identifying the destination of IP traffic, and may include, for example, an IP address, an IPv6 network prefix, a port number, a protocol number, etc. The domain descriptors may indicate a fully qualified domain name (FQDN) of the destination. The non-IP descriptor may indicate information identifying the destination of non-IP traffic (e.g., ethernet traffic or unstructured traffic). The DNN may be information related to the DNN provided by the application. The connection capability may indicate information provided by the UE application when the UE requests connection to a network using a certain capability. Here, the connection capability may indicate IMS.

[0114] Additionally, a Route Selection Descriptor List may consist of one or more Route Selection Descriptors, each of which may consist of a Route Selection Descriptor Precedence and / or Route selection components.

[0115] Here, the rule selection descriptor priority indicates the order in which the route selection descriptors are applied. When the UE receives a route selection descriptor list, that is, when it receives one or more route selection descriptors, it may refer to the rule selection descriptor priority in each route selection descriptor and apply the route selection descriptors in order from the highest priority to the lowest priority.

[0116] The route selection configuration may also include SSC Mode Selection, and / or Network Slice Selection, and / or DNN Selection, and / or PDU Session Type Selection, and / or Non-Seamless Offload indication, and / or Access Type preference.

[0117] Here, the SSC mode selection may indicate routing of application traffic through a PDU session of the specified SSC mode. The network slice selection may indicate routing of application traffic using a PDU session supporting one or more indicated S-NSSAIs. Here, the network slice selection may indicate a first S-NSSAI supporting IMS. The DNN selection may indicate routing of application traffic using a PDU session supporting one or more indicated DNNs. The PDU session type selection may indicate routing of application traffic using a PDU session supporting the indicated PDU session type. The non-seamless offload indication may indicate offloading of application traffic to a non-3GPP access. The access type preference may indicate an access type for establishing a PDU session if the UE needs to establish a PDU session. Here, the access type may indicate 3GPP, non-3GPP, or multi-access.

[0118] Next, the identification information transmitted, received, stored, and managed by each device in this embodiment will be described.

[0119] First, the first identification information is a default S-NSSAI (hereinafter also referred to as the default S-NSSAI). The first identification information may be the same as the 11th identification information and / or the 21st identification information and / or the 31st identification information. The first identification information may be selected from the 11th identification information and / or the 21st identification information and / or the 31st identification information.

[0120] Furthermore, the second identification information is information indicating a request for information on a registration area that can use the S-NSSAI. Specifically, the second identification information may be information indicating a request for information on a registration area that can use the S-NSSAI that supports IMS.

[0121] Furthermore, the third identification information is the first S-NSSAI that supports IMS. Furthermore, the third identification information may be the same as or different from the S-NSSAI included in the fifteenth identification information. Furthermore, the third identification information may be the same as the sixteenth identification information. Furthermore, the third identification information may be the same as or different from the S-NSSAI included in the twenty-fifth identification information. Furthermore, the third identification information may be the same as the twenty-sixth identification information. Furthermore, the third identification information may be the same as the thirty-sixth identification information.

[0122] The fourth identification information is information that includes at least a part of the first to third identification information.

[0123] The 11th identification information is a default S-NSSAI. The 11th identification information may be the same as or different from the 1st identification information and / or the 21st identification information and / or the 31st identification information.

[0124] In addition, the 12th identification information may be information indicating the registration area in which the S-NSSAI included in the Allowed NSSAI is valid, and / or information indicating whether the S-NSSAI included in the Allowed NSSAI is valid in the current registration area, and / or information indicating whether the S-NSSAI included in the Allowed NSSAI is valid within the current PLMN, and / or information indicating whether the S-NSSAI included in the Allowed NSSAI is valid in all PLMNs.

[0125] In addition, the 12th identification information may be information indicating the registration area in which the first S-NSSAI is valid, and / or information indicating whether the first S-NSSAI is valid in the current registration area, and / or information indicating whether the first S-NSSAI is valid within the current PLMN, and / or information indicating whether the first S-NSSAI is valid in all PLMNs.

[0126] Furthermore, the twelfth identification information may be configured as information for each access type for a registration area. That is, the twelfth identification information may be information indicating whether the first S-NSSAI is valid in the current registration area for 3GPP access, and / or information indicating whether the first S-NSSAI is valid in the current registration area for non-3GPP access, and / or information indicating whether the first S-NSSAI is valid in the current PLMN (Public Land Mobile Network), and / or information indicating whether the first S-NSSAI is valid in all PLMNs.

[0127] Furthermore, the twelfth identification information may include information about an access type and may be configured as information associated with the access type for a registration area. That is, the twelfth identification information may be, for each access type, information indicating whether the first S-NSSAI is valid in the current registration area, and / or information indicating whether the first S-NSSAI is valid in the current PLMN (Public Land Mobile Network), and / or information indicating whether the first S-NSSAI is valid in all PLMNs. Here, the information about the access type may be information indicating 3GPP access or non-3GPP access, as described above.

[0128] Furthermore, the twelfth identification information may be configured as a plurality of individual pieces of information for each access unit associated with an access type. For example, the twelfth identification information #A may be information indicating whether the first S-NSSAI is valid in the current registration area in 3GPP access, and the twelfth identification information #B may be information indicating whether the first S-NSSAI is valid in the current registration area in non-3GPP access.

[0129] Furthermore, the 13th identification information is information indicating that the Allowed NSSAI includes an S-NSSAI for an IMS service, and / or that the first S-NSSAI included in the Allowed NSSAI is an S-NSSAI for an IMS service, and / or that the last S-NSSAI included in the Allowed NSSAI is an S-NSSAI for an IMS service. Furthermore, the 13th identification information may be information indicating the ordinal position of the S-NSSAI for an IMS service included in the Allowed NSSAI.

[0130] The fourteenth identification information is information for identifying an IMS service. The fourteenth identification information may be associated with an S-NSSAI that supports the IMS.

[0131] The fifteenth identification information is an Allowed NSSAI. The fifteenth identification information may include a first S-NSSAI that supports an IMS service. All S-NSSAIs included in the fifteenth identification information may not support an IMS service. The fifteenth identification information may include the eleventh identification information and / or the fourteenth identification information and / or the sixteenth identification information. The positions and order of one or more S-NSSAIs included in the fifteenth identification information and the IMS service may be predefined by a specification or an operator. For example, it may be predefined that the first S-NSSAI of the one or more S-NSSAIs included in the fifteenth identification information corresponds to an IMS service. It may be predefined that the last S-NSSAI of the one or more S-NSSAIs included in the fifteenth identification information corresponds to an IMS service. Furthermore, it may be specified in advance that the nth (n is a value greater than 1) S-NSSAI from the top of one or more S-NSSAIs included in the 15th identification information is an S-NSSAI corresponding to an IMS service. Furthermore, it may be specified in advance that the nth (n is a value greater than 1) S-NSSAI from the bottom of one or more S-NSSAIs included in the 15th identification information is an S-NSSAI corresponding to an IMS service. Furthermore, the S-NSSAI included in the 15th identification information may be an S-NSSAI composed of an SST (Slice / Service type) and / or an SD (Slice Differentiator).

[0132] Furthermore, the 16th identification information is a first S-NSSAI and / or a second S-NSSAI that supports IMS. Furthermore, the 16th identification information may be the same as or different from the S-NSSAI included in the 15th identification information. Furthermore, the 16th identification information may be the same as or different from the S-NSSAI included in the 25th identification information. Furthermore, the 16th identification information may be the same as or different from the 26th identification information. Furthermore, the 16th identification information may be the same as or different from the 36th identification information. Furthermore, the 16th identification information may be an S-NSSAI configured by an SST (Slice / Service type) and / or an SD (Slice Differentiator).

[0133] Furthermore, the seventeenth identification information may be information that includes at least a part of the eleventh to sixteenth identification information.

[0134] The 21st identification information is a default S-NSSAI. The 21st identification information may be the same as or different from the 1st identification information and / or the 11th identification information and / or the 31st identification information.

[0135] In addition, the 22nd identification information is information indicating the registration area in which the first S-NSSAI is valid, and / or information indicating whether the first S-NSSAI is valid in the current registration area, and / or information indicating whether the first S-NSSAI is valid within the current PLMN, and / or information indicating whether the first S-NSSAI is valid in all PLMNs.

[0136] Furthermore, the 22nd identification information may be configured as information for each access type for a registration area. That is, the 22nd identification information may be information indicating whether the first S-NSSAI is valid in the current registration area for 3GPP access, and / or information indicating whether the first S-NSSAI is valid in the current registration area for non-3GPP access, and / or information indicating whether the first S-NSSAI is valid in the current PLMN (Public Land Mobile Network), and / or information indicating whether the first S-NSSAI is valid in all PLMNs.

[0137] Furthermore, the 22nd identification information may include information about the access type and may be configured as information associated with the access type for the registration area. That is, the 22nd identification information may be information indicating, for each access type, whether the first S-NSSAI is valid in the current registration area, and / or information indicating whether the first S-NSSAI is valid in the current PLMN (Public Land Mobile Network), and / or information indicating whether the first S-NSSAI is valid in all PLMNs. Here, the information about the access type may be information indicating 3GPP access or non-3GPP access, as described above.

[0138] Furthermore, the 22nd identification information may be configured as a plurality of individual pieces of information for each access unit associated with an access type. For example, the 22nd identification information #A may be information indicating whether the first S-NSSAI is valid in the current registration area in 3GPP access, and the 22nd identification information #B may be information indicating whether the first S-NSSAI is valid in the current registration area in non-3GPP access.

[0139] Furthermore, the 23rd identification information is information indicating that the Allowed NSSAI includes an S-NSSAI for an IMS service, and / or that the first S-NSSAI included in the Allowed NSSAI is an S-NSSAI for an IMS service, and / or that the last S-NSSAI included in the Allowed NSSAI is an S-NSSAI for an IMS service. Furthermore, the 23rd identification information may be information indicating the ordinal position of the S-NSSAI for an IMS service included in the Allowed NSSAI.

[0140] The 24th identification information is information for identifying an IMS service. The 24th identification information may be associated with an S-NSSAI that supports the IMS.

[0141] Furthermore, the 25th identification information is an Allowed NSSAI. Furthermore, the 25th identification information may include a first S-NSSAI that supports an IMS service. Furthermore, all S-NSSAIs included in the 25th identification information may not support an IMS service. Furthermore, the 25th identification information may include the 21st identification information and / or the 24th identification information and / or the 26th identification information. Furthermore, the S-NSSAI included in the 25th identification information may be an S-NSSAI configured by an SST (Slice / Service type) and / or an SD (Slice Differentiator).

[0142] Furthermore, the 26th identification information is a first S-NSSAI and / or a second S-NSSAI that supports IMS. Furthermore, the 26th identification information may be the same as or different from the S-NSSAI included in the 15th identification information. Furthermore, the 26th identification information may be the same as or different from the 16th identification information. Furthermore, the 26th identification information may be the same as or different from the S-NSSAI included in the 25th identification information. Furthermore, the 26th identification information may be the same as or different from the 36th identification information. Furthermore, the 26th identification information may be an S-NSSAI configured by an SST (Slice / Service type) and / or an SD (Slice Differentiator).

[0143] Furthermore, the 27th identification information may be information that includes at least a part of the 21st to 26th identification information.

[0144] The 31st identification information is a default S-NSSAI. The 31st identification information may be the same as or different from the first identification information, the 11th identification information, and / or the 21st identification information. The 31st identification information may be included in an Allowed NSSAI.

[0145] In addition, the 32nd identification information is information indicating the registration area in which the first S-NSSAI is valid, and / or information indicating whether the first S-NSSAI is valid in the current registration area, and / or information indicating whether the first S-NSSAI is valid within the current PLMN, and / or information indicating whether the first S-NSSAI is valid in all PLMNs.

[0146] Furthermore, the 32nd identification information may be configured as information for each access type for a registration area. That is, the 32nd identification information may be information indicating whether the first S-NSSAI is valid in the current registration area for 3GPP access, and / or information indicating whether the first S-NSSAI is valid in the current registration area for non-3GPP access, and / or information indicating whether the first S-NSSAI is valid in the current PLMN (Public Land Mobile Network), and / or information indicating whether the first S-NSSAI is valid in all PLMNs.

[0147] Furthermore, the 32nd identification information may include information about the access type and may be configured as information associated with the access type for the registration area. That is, the 32nd identification information may be information indicating, for each access type, whether the first S-NSSAI is valid in the current registration area, and / or information indicating whether the first S-NSSAI is valid in the current PLMN (Public Land Mobile Network), and / or information indicating whether the first S-NSSAI is valid in all PLMNs. Here, the information about the access type may be information indicating 3GPP access or non-3GPP access, as described above.

[0148] Furthermore, the 32nd identification information may be configured as a plurality of individual pieces of information for each access unit associated with an access type. For example, the 32nd identification information #A may be information indicating whether the first S-NSSAI is valid in the current registration area in 3GPP access, and the 32nd identification information #B may be information indicating whether the first S-NSSAI is valid in the current registration area in non-3GPP access.

[0149] The 33rd identification information is the URSP. The 33rd identification information may include at least one of the 32nd, 34th to 36th identification information.

[0150] Furthermore, the 34th identification information may be mapping information with the 32nd identification information, and / or the 35th identification information, and / or the 36th identification information. The 34th identification information may be information that explicitly indicates that the 32nd identification information, and / or the 35th identification information, and / or the 36th identification information correspond to the 34th identification information.

[0151] Furthermore, the 35th identification information is information indicating a service type. Furthermore, the 35th identification information may indicate IMS or an IMS service. Furthermore, the 35th identification information may be information indicating whether the S-NSSAI can be used for an IMS service. Furthermore, the 35th identification information may be connection capabilities indicating IMS or an IMS service. Furthermore, the 35th identification information may be connection capabilities indicating whether the S-NSSAI can be used for an IMS service. Furthermore, the 35th identification information may be associated with an S-NSSAI that supports IMS.

[0152] Furthermore, the 36th identity information is a first S-NSSAI and / or a second S-NSSAI that supports IMS. Furthermore, the 36th identity information may be the same as or different from the S-NSSAI included in the 15th identity information. Furthermore, the 36th identity information may be the same as or different from the 16th identity information. Furthermore, the 36th identity information may be the same as or different from the S-NSSAI included in the 25th identity information. Furthermore, the 36th identity information may be the same as or different from the 26th identity information. Furthermore, when the PCF receives information regarding an Allowed NSSAI from the AMF, the 36th identity information may be a first S-NSSAI selected from one or more S-NSSAIs included in the Allowed NSSAI. Furthermore, the 36th identity information may be a first S-NSSAI that supports an IMS service and is valid (usable) in a new registration area. Furthermore, the 36th identity information may be included in the Allowed NSSAI. The 36th identification information may also be an S-NSSAI composed of an SST (Slice / Service type) and / or an SD (Slice Differentiator).

[0153] Furthermore, the 37th identification information may be information that includes at least a part of the 31st to 36th identification information.

[0154] Furthermore, the 41st identification information is a cause value indicating the reason for the rejection. Furthermore, the 41st identification information may be a cause value indicating "unavailable at current registration area." Furthermore, the 41st identification information may be a cause value indicating "S-NSSAI unavailable at current registration area" for the provided S-NSSAI (including the first S-NSSAI). Furthermore, the 41st identification information may be associated with 3GPP access and / or non-3GPP access. That is, the 41st identification information may be a cause value indicating "unavailable at current registration area for 3GPP access and / or non-3GPP access." The 41st identification information may also be a reason value indicating that the provided S-NSSAI is unavailable at current registration area for 3GPP access and / or non-3GPP access.

[0155] 3. First Embodiment [3.1. Procedures used in the first embodiment] First, the procedures used in the first embodiment will be described, including the registration procedure in Chapter 3.2, and / or the generic UE configuration update procedure in Chapter 3.3, and / or the UE policy management procedure in Chapter 3.4.

[0156] In the first embodiment, as shown in FIG. 2, an example will be described in which the HSS and UDM, the PCF and PCRF, the SMF and PGW-C, and the UPF and PGW-U are configured as the same device (that is, the same physical hardware, the same logical hardware, or the same software). However, the contents described in this embodiment are also applicable to cases in which these are configured as different devices (that is, different physical hardware, different logical hardware, or different software). For example, data may be transmitted and received directly between these devices, or may be transmitted and received via the N26 interface between the AMF and MME, or may be transmitted and received via the UE.

[0157] 3.2. Registration Procedures First, the registration procedure will be described with reference to FIG. 6. Hereinafter, this procedure refers to the registration procedure. The registration procedure is a procedure initiated by the UE to register with the access network _B and / or the core network _B and / or the DN. If the UE is not registered with a network, it can execute this procedure at any time, for example, when it is powered on. In other words, if the UE is in a deregistered state (5GMM-DEREGISTERED state), it can start this procedure at any time. Furthermore, each device (especially the UE and the AMF) can transition to a registered state (5GMM-REGISTED state) based on the completion of the registration procedure. Note that each registration state may be managed by each device for each access. Specifically, each device may independently manage the registration state (registered state or unregistered state) for 3GPP access and the registration state for non-3GPP access.

[0158] Furthermore, the registration procedure may be a procedure for updating the location registration information of the UE in the network, and / or for the UE to periodically notify the network of the status of the UE, and / or for updating certain parameters related to the UE in the network.

[0159] A UE may initiate a registration procedure when performing mobility across TAs. In other words, a UE may initiate a registration procedure when it moves to a TA different from the TA indicated in the TA list it maintains. Furthermore, a UE may initiate this procedure when a running backoff timer or other timer expires. Furthermore, a UE may initiate a registration procedure when a context update for each device is required due to a PDU session disconnection or invalidation. Furthermore, a UE may initiate a registration procedure when a change occurs in the UE's capability information and / or preferences regarding PDU session establishment. Furthermore, a UE may initiate a registration procedure periodically. Furthermore, a UE may initiate a registration procedure based on the completion of the registration procedure in Chapter 3.2, the completion of the generic UE configuration update procedure in Chapter 3.3, the completion of the UE policy management procedure in Chapter 3.4, or the completion of a procedure for SM. Note that the UE may perform the registration procedure at any timing, not limited to these.

[0160] The procedure for the UE to transition from a state where it is not registered in the network (unregistered state) to a state where it is registered (registered state) may be called an initial registration procedure or a registration procedure for initial registration. Also, the registration procedure performed when the UE is registered in the network (registered state) may be called a registration procedure for mobility and periodic registration update or a mobility and periodic registration procedure.

[0161] The new AMF (hereinafter simply referred to as AMF) in Figure 6 indicates the AMF to which the UE is registered through this procedure, and the old AMF refers to the AMF to which the UE was registered through a registration procedure prior to this procedure. If no AMF change occurs during this procedure, the interface between the old AMF and the new AMF and the procedure between the old AMF and the new AMF do not occur, and the new AMF may be the same device as the old AMF. In this embodiment, when AMF is written, it may refer to the new AMF, the old AMF, or both.

[0162] First, the UE starts the registration procedure by transmitting a registration request message to the new AMF (S600) (S602) (S604). Specifically, the UE transmits an RRC message including a registration request message to the 5G AN (or gNB) (S600). The registration request message is a NAS message transmitted and received on the N1 interface. The RRC message may be a control message transmitted and received between the UE and the 5G AN (or gNB). The NAS message is processed in the NAS layer, and the RRC message is processed in the RRC layer. The NAS layer is a layer higher than the RRC layer.

[0163] Here, the UE may transmit one or more of the first to fourth identification information in the registration request message and / or the RRC message. Here, the first to fourth identification information may be as described in Chapter 2.7. Furthermore, the UE may transmit the registration request message and / or the RRC message including identification information indicating the type of this procedure. Here, the identification information indicating the type of this procedure may be a 5GS registration type IE, and may be information indicating that this procedure is a registration procedure for initial registration, mobility registration updating, periodic registration updating, or emergency registration. In particular, if this procedure is performed when the registration area changes due to UE movement, the UE may set this 5GS registration type IE to mobility registration updating.

[0164] The UE may include UE capability information in the registration request message to inform the network of the capabilities that the UE supports, where the UE capability information may be 5GMM capability of 5GS.

[0165] The UE may transmit these pieces of identification information by including them in a control message different from the above, for example, a control message of a layer lower than the RRC (Radio Resource Control) layer (for example, a MAC (Medium Access Control) layer, an RLC (Radio Link Control) layer, or a PDCP (Packet Data Convergence Protocol) layer). By transmitting these pieces of identification information, the UE may indicate that the UE supports each function, may indicate a request from the UE, or may indicate both. Furthermore, when multiple pieces of identification information are transmitted and received, two or more pieces of identification information may be configured as one or more pieces of identification information. Note that the information indicating support for each function and the information indicating a request to use each function may be transmitted and received as the same identification information, or may be transmitted and received as different identification information.

[0166] Furthermore, the UE may select and decide whether to transmit the first to fourth identification information to the network based on the UE's capability information, and / or UE policy, and / or UE status, and / or user registration information, and / or context held by the UE, etc.

[0167] Furthermore, the UE may perform the following process when determining whether to transmit at least one piece of information among the first to fourth identification information.

[0168] For example, if the UE has already received the 15th identification information and the 33rd identification information from the core network, the UE may select an S-NSSAI that is valid (usable) in the current registration area as the third identification information for the IMS service from one or more S-NSSAIs included in the 15th identification information and an S-NSSAI indicated by the 36th identification information included in the 33rd identification information based on the 15th identification information and the 33rd identification information, and transmit the third identification information.

[0169] Furthermore, if the UE has already received the 15th identification information and the 33rd identification information from the core network and the 33rd identification information does not include the 32nd identification information, the UE may determine that the S-NSSAI indicated by the 36th identification information included in the 33rd identification information is valid in the current registration area, or valid within the current PLMN, or valid in all PLMNs, and may select an S-NSSAI that is valid (usable) in the current registration area as the third identification information for the IMS service from one or more S-NSSAIs included in the 15th identification information and the S-NSSAI indicated by the 36th identification information included in the 33rd identification information, and transmit the third identification information.

[0170] In addition, if the UE has already received the 15th identification information and the 33rd identification information from the core network, and the 36th identification information included in the 33rd identification information is the first S-NSSAI selected by the PCF from the Allowed NSSAIs, the UE may select the first S-NSSAI indicated by the 36th identification information as the third identification information for the IMS service based on the 33rd identification information and transmit the third identification information.

[0171] Furthermore, if the UE has already received the 15th identity and the 33rd identity from the core network, the UE may check whether the 36th identity included in the 33rd identity is included in the 15th identity, and if the 36th identity is included in the 15th identity, select the 36th identity as the third identity for the IMS service and transmit the third identity. Furthermore, the UE may check whether the 36th identity is included in the 15th identity, and if the 36th identity is not included in the 15th identity, not select the 36th identity as the third identity for the IMS service. In this case, the UE may not transmit the third identity.

[0172] Furthermore, the UE may check for each access whether the 36th identity included in the 33rd identity is included in the 15th identity. That is, the UE may check for each of 3GPP access and non-3GPP access whether the 36th identity included in the 33rd identity is included in the 15th identity. For example, if the 36th identity included in the 33rd identity is included in the 15th identity for 3GPP access but the 36th identity included in the 33rd identity is not included in the 15th identity for non-3GPP access, the UE may select the 36th identity as the third identity for the IMS service and transmit the third identity via the 3GPP access. Furthermore, when the 36th identification information included in the 33rd identification information is not included in the 15th identification information for 3GPP access, and the 36th identification information included in the 33rd identification information is included in the 15th identification information for non-3GPP access, the UE may select the 36th identification information as the third identification information for the IMS service and transmit the third identification information via the non-3GPP access. Furthermore, when the 36th identification information included in the 33rd identification information is included in the 15th identification information for 3GPP access, and the 36th identification information included in the 33rd identification information is included in the 15th identification information for non-3GPP access, the UE may select the 36th identification information as the third identification information for the IMS service, select whether the third identification information is to be transmitted from the 3GPP access or the non-3GPP access, and transmit the third identification information via the selected access. Furthermore, if the 36th identity included in the 33rd identity is not included in the 15th identity for 3GPP access, and the 36th identity included in the 33rd identity is not included in the 15th identity for non-3GPP access, the UE does not need to select the 36th identity as the third identity for the IMS service. In this case, the UE does not need to transmit the third identity.

[0173] Furthermore, if the UE has already received an eleventh identity from the core network, the UE may store the eleventh identity in association with the IMS service. In this case, if the eleventh identity is valid in all PLMNs and the UE moves to a new registration area different from the current registration area, and the UE has not received a first S-NSSAI (the sixteenth identity, the twenty-sixth identity, and / or the thirty-sixth identity) that is valid in the new registration area (supporting the IMS service), the UE may select a default S-NSSAI indicated by the eleventh identity as the first identity for the IMS service and transmit the first identity, regardless of whether the new registration area belongs to the current PLMN. Also, if the 11th identity is valid in the current PLMN and the UE moves to a new registration area different from the current registration area, and the UE has not received a first S-NSSAI (the 16th identity, and / or the 26th identity, and / or the 36th identity) that is valid in the new registration area (supporting IMS services), and the new registration area belongs to the current PLMN, the UE may select the default S-NSSAI indicated by the 11th identity as the first identity for the IMS service and send the first identity. Furthermore, if the 11th identity is valid in the current PLMN and the UE moves to a new registration area different from the current registration area, and the UE has not received a first S-NSSAI (the 16th identity, the 26th identity, and / or the 36th identity) that is valid in the new registration area (supporting the IMS service), and the new registration area does not belong to the current PLMN, the UE may not select the default S-NSSAI indicated by the 11th identity as the first identity for the IMS service. In this case, the UE may not transmit the first identity.Also, if the 11th identity is valid in the current PLMN and the UE moves to a new registration area different from the current registration area, and the UE has received a first S-NSSAI (the 16th identity, and / or the 26th identity, and / or the 36th identity) that is valid in the new registration area (supporting IMS services), the UE may select the first S-NSSAI (the 16th identity, and / or the 26th identity, and / or the 36th identity) as the third identity for the IMS service and transmit the third identity.

[0174] Furthermore, if the UE has already received the 21st identity from the core network, the UE may store the 21st identity in association with the IMS service. In this case, if the 21st identity is valid in all PLMNs and the UE moves to a new registration area different from the current registration area, and the UE has not received a first S-NSSAI (the 16th identity, the 26th identity, and / or the 36th identity) that is valid in the new registration area (supporting the IMS service), the UE may select a default S-NSSAI indicated by the 21st identity as the first identity for the IMS service and transmit the first identity, regardless of whether the new registration area belongs to the current PLMN. Also, if the 21st identity is valid in the current PLMN and the UE moves to a new registration area different from the current registration area, and the UE has not received a first S-NSSAI (the 16th identity, and / or the 26th identity, and / or the 36th identity) that is valid in the new registration area (supporting IMS services), and the new registration area belongs to the current PLMN, the UE may select the default S-NSSAI indicated by the 21st identity as the first identity for the IMS service and send the first identity. Furthermore, if the 21st identity is valid in the current PLMN and the UE moves to a new registration area different from the current registration area, and the UE has not received a first S-NSSAI (the 16th identity, the 26th identity, and / or the 36th identity) that is valid in the new registration area (supporting the IMS service), and the new registration area does not belong to the current PLMN, the UE may not select the default S-NSSAI indicated by the 21st identity as the first identity for the IMS service. In this case, the UE may not transmit the first identity.Also, if the 21st identity is valid in the current PLMN and the UE moves to a new registration area different from the current registration area and the UE has received a first S-NSSAI (the 16th identity, and / or the 26th identity, and / or the 36th identity) that is valid in the new registration area (supporting IMS services), the UE may select the first S-NSSAI (the 16th identity, and / or the 26th identity, and / or the 36th identity) as the third identity for the IMS service and transmit the third identity.

[0175] Furthermore, if the UE has already received the 31st identity from the core network, the UE may store the 31st identity in association with the IMS service. In this case, if the 31st identity is valid in all PLMNs and the UE moves to a new registration area different from the current registration area, and the UE has not received a first S-NSSAI (the 16th identity, the 26th identity, and / or the 36th identity) that is valid in the new registration area (supporting the IMS service), the UE may select a default S-NSSAI indicated by the 31st identity as the first identity for the IMS service and transmit the first identity, regardless of whether the new registration area belongs to the current PLMN. Also, if the 31st identity is valid in the current PLMN and the UE moves to a new registration area different from the current registration area, and the UE has not received a first S-NSSAI (the 16th identity, and / or the 26th identity, and / or the 36th identity) that is valid in the new registration area (supporting IMS services), and the new registration area belongs to the current PLMN, the UE may select the default S-NSSAI indicated by the 31st identity as the first identity for IMS services and send the first identity. Furthermore, if the 31st identity is valid in the current PLMN and the UE moves to a new registration area different from the current registration area, and the UE has not received a first S-NSSAI (the 16th identity, the 26th identity, and / or the 36th identity) that is valid in the new registration area (supporting the IMS service), and the new registration area does not belong to the current PLMN, the UE may not select the default S-NSSAI indicated by the 31st identity as the first identity for the IMS service. In this case, the UE may not transmit the first identity.Also, if the 31st identity is valid in the current PLMN and the UE moves to a new registration area different from the current registration area and the UE has received a first S-NSSAI (the 16th identity, and / or the 26th identity, and / or the 36th identity) that is valid in the new registration area (supporting IMS services), the UE may select the first S-NSSAI (the 16th identity, and / or the 26th identity, and / or the 36th identity) as the third identity for the IMS service and transmit the third identity.

[0176] In addition, when communicating using an IMS service, the UE may transmit the second identification information when it wants to know the validity range of the registration area of ​​the first S-NSSAI supporting the IMS service, in other words, when it wants to obtain information about the registration area in which the first S-NSSAI supporting the IMS service can be used.

[0177] Furthermore, if the UE has already received the 12th identity, the 15th identity, and the 33rd identity from the core network, the UE may store the 33rd identity and further associate and store the 12th identity with the 15th identity or the S-NSSAI included in the 15th identity. Then, for the IMS service, the UE may select an S-NSSAI that is valid (usable) in the current registration area as a third identity from the S-NSSAI included in the 15th identity and the first S-NSSAI indicated by the 36th identity based on the 12th identity, the 15th identity, and the 33rd identity, and transmit the third identity.

[0178] In addition, when the UE is communicating using an IMS service and has already received the 14th identification information, the 15th identification information, and / or the 16th identification information from the core network, the UE may store the S-NSSAI indicated by the 15th identification information and / or the 16th identification information in association with the IMS service, and may select the requested S-NSSAI (hereinafter also referred to as Requested S-NSSAI) based on the current registration area and the stored S-NSSAI and transmit that S-NSSAI.

[0179] In addition, when the UE is communicating using an IMS service and has already received the 12th identification information, the 14th identification information, the 15th identification information and / or the 16th identification information from the core network, the UE may store the S-NSSAI indicated by the 15th identification information and / or the 16th identification information in association with the IMS service and the 12th identification information, and may select the requested S-NSSAI based on the current registration area and the stored S-NSSAI and transmit the S-NSSAI.

[0180] In addition, when the UE is communicating using an IMS service and has already received the 24th identification information, the 25th identification information, and / or the 26th identification information from the core network, the UE may store the S-NSSAI indicated by the 25th identification information and / or the 26th identification information in association with the IMS service, and may select the requested S-NSSAI based on the current registration area and the stored S-NSSAI and transmit the S-NSSAI.

[0181] In addition, when the UE is communicating using an IMS service and has already received the 22nd identification information, the 24th identification information, the 25th identification information and / or the 26th identification information from the core network, the UE may store the S-NSSAI indicated by the 25th identification information and / or the 26th identification information, the IMS service, and the 22nd identification information in association with each other, and may select the requested S-NSSAI based on the current registration area and the stored S-NSSAI and transmit the S-NSSAI.

[0182] In addition, when the UE is communicating using an IMS service and has already received 15th identification information from the core network, if the value of the SST or SD constituting the S-NSSAI included in the 15th identification information is an S-NSSAI that indicates an IMS service, the UE may select that S-NSSAI as the third identification information and transmit the third identification information.

[0183] In addition, when the UE is communicating using an IMS service and has already received 25th identification information from the core network, if the value of the SST or SD constituting the S-NSSAI included in the 25th identification information is an S-NSSAI that indicates an IMS service, the UE may select that S-NSSAI as the third identification information and transmit the third identification information.

[0184] Furthermore, when the UE performs communication using an IMS service, if the UE has already received the fifteenth identity from the core network and knows that the position and order of the first S-NSSAI (supporting IMS) included in the fifteenth identity and the association between the IMS service and the first S-NSSAI are predefined by a specification or an operator, the UE may select the first S-NSSAI supporting the IMS service from one or more S-NSSAIs included in the fifteenth identity based on the information and transmit the first S-NSSAI as the third identity. In this way, when the UE knows the position of the first S-NSSAI in the Allowed NSSAIs in advance, the UE may be able to identify the first S-NSSAI even if it has not received, from the core network, information that explicitly indicates the association between the IMS service and the first S-NSSAI, such as the fourteenth identity, the twenty-fourth identity, and the thirty-fourth identity.

[0185] Furthermore, when the UE performs communication using an IMS service, if the UE has already received the 25th identity from the core network and knows that the position and order of the first S-NSSAI (supporting IMS) included in the 25th identity and the association between the IMS service and the position and order are predefined by a specification or an operator, the UE may select the first S-NSSAI supporting the IMS service from one or more S-NSSAIs included in the 25th identity based on the information and transmit the first S-NSSAI as the third identity. In this way, when the UE knows the position of the first S-NSSAI in the Allowed NSSAIs in advance, the UE may be able to identify the first S-NSSAI even if it has not received, from the core network, information that explicitly indicates the association between the IMS service and the first S-NSSAI, such as the 14th identity, the 24th identity, and the 34th identity.

[0186] In addition, when communicating using an IMS service, if the UE has already received the 13th identification information and the 15th identification information from the core network, the UE may select a first S-NSSAI (that supports IMS) from one or more S-NSSAIs included in the 15th identification information based on the information indicated in the 13th identification information, and transmit the first S-NSSAI as the third identification information.

[0187] In addition, when communicating using an IMS service, if the UE has already received the 23rd identification information and the 25th identification information from the core network, the UE may select a first S-NSSAI (that supports IMS) from one or more S-NSSAIs included in the 25th identification information based on the information indicated by the 23rd identification information, and transmit the first S-NSSAI as the third identification information.

[0188] In addition, if the UE has previously stored an IMS service in association with a default S-NSSAI and / or a first S-NSSAI, the UE may transmit the first identification information and / or the third identification information when communicating using the IMS service.

[0189] In addition, when communicating using an IMS service, if the UE has already received a 15th identification information including the 16th identification information and the 14th identification information from the core network, the UE may send the first S-NSSAI indicated by the 16th identification information as the third identification information.

[0190] In addition, when the UE transmits a selected S-NSSAI and / or a first identification information and / or a selected third identification information, the UE may transmit a requested NSSAI including the S-NSSAI and / or the first identification information and / or the third identification information.

[0191] Furthermore, one or more pieces of third identification information may be transmitted. In this case, a requested NSSAI including one or more pieces of third identification information may be transmitted. Furthermore, transmitting at least one of the first to third identification information may mean transmitting a fourth identification information.

[0192] The UE may include identification information other than the first to fourth identification information in the registration request message and / or the RRC message including the registration request message, for example, the UE ID and / or the PLMN ID and / or the AMF identification information, and may transmit the same. Here, the AMF identification information may be information that identifies an AMF or a set of AMFs, for example, 5G-S-TMSI (5G S-Temporary Mobile Subscription Identifier) ​​or GUAMI (Globally Unique AMF Identifier).

[0193] Next, when the 5G AN (or gNB) receives an RRC message including a registration request message, it selects an AMF to which to transfer the registration request message (S602). Note that the 5G AN (or gNB) can select an AMF based on one or more identification information included in the registration request message and / or the RRC message. Specifically, the 5G AN (or gNB) may select a new AMF to which to send the registration request message based on at least one of the first to fourth identification information.

[0194] Then, the 5G AN (or gNB) forwards the identification information included in the registration request message and / or the RRC message, and / or the registration request message, to the selected new AMF (S604).

[0195] Next, when the new AMF receives the registration request message, it can perform a first condition determination. The first condition determination is for determining whether the network (or the new AMF) accepts the UE's request. If the first condition determination is true, the new AMF performs the procedures from S606 to S612. On the other hand, if the first condition determination is false, the new AMF may perform the procedure of S610 without performing the procedures from S606 to S608.

[0196] Furthermore, the new AMF may perform a first condition determination after requesting the UE context from the old AMF and receiving the UE context from the old AMF (S606, S608). In this case, the new AMF executes S610 and S612 if the first condition determination is true. On the other hand, the new AMF may execute S610 if the first condition determination is false.

[0197] Furthermore, if the first condition determination is true, the control message sent and received in S610 may be a Registration accept message, and if the first condition determination is false, the control message sent and received in S610 may be a Registration reject message.

[0198] In addition, the first condition determination may be performed based on the receipt of a registration request message, and / or each identification information contained in the registration request message, and / or subscriber information, and / or network capability information, and / or operator policy, and / or network status, and / or user registration information, and / or context held by the AMF, etc.

[0199] For example, if the network permits the UE's request, the first condition determination may be true, and if the network does not permit the UE's request, the first condition determination may be false. Furthermore, if the network to which the UE is registered and / or a device within the network supports the function requested by the UE, the first condition determination may be true, and if the function requested by the UE is not supported, the first condition determination may be false. Furthermore, if the identification information to be transmitted and received is permitted, the first condition determination may be true, and if the identification information to be transmitted and received is not permitted, the first condition determination may be false.

[0200] Furthermore, the new AMF may determine the first condition as true if the UE has an allowed NSSAI (Allowed NSSAI). Furthermore, the new AMF may determine the first condition as true if the UE has an allowed NSSAI (Allowed NSSAI), regardless of whether the NSSAI includes a first S-NSSAI that supports IMS. Furthermore, the new AMF may determine the first condition as true if the UE has an allowed NSSAI (Allowed NSSAI) and the UE includes a first S-NSSAI that supports IMS. Furthermore, the new AMF may determine the first condition as false if the UE has an allowed NSSAI (Allowed NSSAI) and the UE does not include a first S-NSSAI that supports IMS.

[0201] Next, if the new AMF is different from the AMF indicated in the AMF identification information included in the message received from the UE, the new AMF executes the procedures of S606 and S608, and if the new AMF is the same as the AMF indicated in the AMF identification information included in the message received from the UE, the procedures of S606 and S608 are not executed. In other words, if an AMF change occurs due to this procedure, the procedures of S606 and S608 are executed, and if an AMF change does not occur, the procedures of S606 and S608 are skipped.

[0202] The UE context transfer procedure (S606, S608) will be described. The new AMF sets the AMF indicated in the AMF identification information as the old AMF and sends a UE context request message to the old AMF (S606). The old AMF sends the UE context to the new AMF based on the received UE context request message. The new AMF generates a UE context based on the received UE context.

[0203] Here, the UE context transmitted from the new AMF to the old AMF may include a UE ID and an allowed NSSAI. Furthermore, the UE context may include a configured NSSAI and / or a rejected NSSAI, an NSSAI and / or a pending NSSAI, and / or a first NSSAI. Furthermore, the allowed NSSAI, and / or the configured NSSAI, and / or the rejected NSSAI, and / or the pending NSSAI, and / or the first NSSAI included in the UE context, and the S-NSSAI included in each NSSAI may be linked to information on whether notification to the UE has been completed.

[0204] Next, the new AMF sends a control message to the UE based on the determination of the first condition determination and / or based on receiving the UE context from the old AMF (S610). The control message may be a registration acceptance message or a registration rejection message.

[0205] Here, the new AMF may transmit a control message including one or more pieces of identification information among at least the 11th to 17th pieces of identification information. Here, the 11th to 17th pieces of identification information may be as described in Chapter 2.7. By transmitting these pieces of identification information and / or the control message, the AMF may indicate that the network supports each function, may indicate that the UE's request has been accepted, may indicate that the UE's request has not been permitted, or may indicate a combination of these pieces of information. Furthermore, when multiple pieces of identification information are transmitted and received, two or more pieces of identification information may be configured as one or more pieces of identification information. Note that the information indicating support for each function and the information indicating permission to use each function may be transmitted and received as the same identification information or as different identification information.

[0206] The AMF may also select and determine which of the 11th to 17th identification information to include in the control message based on each received identification information, and / or subscriber information, and / or network capability information, and / or operator policy, and / or network status, and / or user registration information, and / or context held by the AMF, etc.

[0207] For example, when the new AMF receives at least one of identification information 1 to 4 from the UE, it may transmit at least one of identification information 11 to 17 in a control message.

[0208] In addition, when at least one of identification information 1 to 4 is received from the UE and the UE's configuration information has been updated since the previous registration procedure, the new AMF may be sent with the updated information included in identification information 11 to 17.

[0209] In addition, the AMF may indicate that the UE's request has been accepted by sending a registration acceptance message, or may indicate that the UE's request has been rejected by sending a registration rejection message, based on the received identification information, and / or subscriber information, and / or network capability information, and / or operator policy, and / or network status, and / or user registration information, and / or context held by the AMF, etc.

[0210] Next, when the UE receives a control message via the 5G AN (gNB) (S610), it may recognize the content of the control message and / or the received information.

[0211] For example, if the control message is a registration accept message, the UE can recognize that the UE's request in the registration request message has been accepted and the contents of various identification information included in the registration accept message by receiving the registration accept message. Also, if the control message is a registration reject message, the UE can recognize that the UE's request in the registration request message has been rejected and the contents of various identification information included in the registration reject message by receiving a registration reject message. Furthermore, if the UE does not receive a control message within a predetermined period after sending the registration request message, the UE may recognize that the UE's request has been rejected.

[0212] Furthermore, the UE may perform the following processes based on receiving at least one of the 11th to 17th identification information and / or receiving a control message. Note that the UE may perform these processes during this procedure or after completing this procedure.

[0213] For example, if the UE has already received the 33rd identification information from the core network, when the UE receives the 15th identification information in this procedure and requests the establishment of a PDU session for an IMS service, the UE may select an S-NSSAI that is valid (usable) in the current registration area from one or more S-NSSAIs included in the 15th identification information and the S-NSSAI indicated by the 36th identification information included in the 33rd identification information based on the 15th identification information and the 33rd identification information, and may send a registration request message including that S-NSSAI, or send a PDU session establishment request message together with that S-NSSAI.

[0214] Furthermore, if the UE has already received the 15th identification information and the 33rd identification information from the core network and the 33rd identification information does not include the 32nd identification information, the UE may determine that the S-NSSAI indicated by the 36th identification information included in the 33rd identification information is valid in the current registration area, or valid within the current PLMN, or valid in all PLMNs, and may select an S-NSSAI that is valid (usable) in the current registration area for the IMS service from one or more S-NSSAIs included in the 15th identification information and the S-NSSAI indicated by the 36th identification information included in the 33rd identification information, and may send a registration request message including that S-NSSAI or send a PDU session establishment request message together with that S-NSSAI.

[0215] Furthermore, when the UE receives the 15th identification information from the core network, the UE may store the 15th identification information or the S-NSSAI included in the 15th identification information. Then, when the UE requests establishment of a PDU session for an IMS service after receiving the 33rd identification information, the UE may select an S-NSSAI that is valid (usable) in the current registration area from one or more S-NSSAIs included in the 15th identification information and an S-NSSAI indicated by the 36th identification information included in the 33rd identification information based on the 15th identification information and the 33rd identification information, and transmit a registration request message including the S-NSSAI or transmit a PDU session establishment request message together with the S-NSSAI. Note that whether the selected S-NSSAI is valid (usable) in the current registration area may be determined based on the 32nd identification information.

[0216] In addition, if the UE has already received the 33rd identification information from the core network, when the UE receives the 15th identification information in this procedure, and the 36th identification information included in the 33rd identification information is the first S-NSSAI selected by the PCF from the Allowed NSSAIs, and when requesting establishment of a PDU session for an IMS service, the UE may select the first S-NSSAI (the 36th identification information included in the 33rd identification information) based on the 33rd identification information, and send a registration request message including the first S-NSSAI, or send a PDU session establishment request message together with the first S-NSSAI.

[0217] Furthermore, when the UE has already received the 33rd identity from the core network and receives the 15th identity in this procedure and requests establishment of a PDU session for an IMS service, the UE may check whether the 36th identity included in the 33rd identity is included in the 15th identity, and if the 36th identity is included in the 15th identity, select a first S-NSSAI indicated by the 36th identity and transmit a registration request message including the first S-NSSAI or transmit a PDU session establishment request message together with the first S-NSSAI. Furthermore, the UE may check whether the 36th identity is included in the 15th identity, and if the 36th identity is not included in the 15th identity, not select the first S-NSSAI indicated by the 36th identity for the IMS service, and not transmit a registration request message including the first S-NSSAI or transmit a PDU session establishment request message together with the first S-NSSAI.

[0218] Furthermore, the UE may check for each access whether the 36th identity included in the 33rd identity is included in the 15th identity. That is, the UE may check for each of 3GPP access and non-3GPP access whether the 36th identity included in the 33rd identity is included in the 15th identity. For example, if the 36th identity included in the 33rd identity is included in the 15th identity for 3GPP access but the 36th identity included in the 33rd identity is not included in the 15th identity for non-3GPP access, the UE may send, for an IMS service, a registration request message including a first S-NSSAI indicated by the 36th identity via the 3GPP access, or may send a PDU session establishment request message with the first S-NSSAI indicated by the 36th identity via the 3GPP access. Furthermore, if the 36th identification information included in the 33rd identification information is not included in the 15th identification information for 3GPP access, and the 36th identification information included in the 33rd identification information is included in the 15th identification information for non-3GPP access, the UE may send a registration request message including the first S-NSSAI indicated by the 36th identification information via non-3GPP access for an IMS service, or may send a PDU session establishment request message together with the first S-NSSAI indicated by the 36th identification information via non-3GPP access. Furthermore, if the 36th identification information included in the 33rd identification information is included in the 15th identification information for 3GPP access, and the 36th identification information included in the 33rd identification information is included in the 15th identification information for non-3GPP access, the UE may select whether to transmit from 3GPP access or non-3GPP access for the IMS service, and may transmit a registration request message including the first S-NSSAI indicated by the 36th identification information, or transmit a PDU session establishment request message together with the first S-NSSAI indicated by the 36th identification information via the selected access.Furthermore, if the 36th identification information included in the 33rd identification information is not included in the 15th identification information for 3GPP access, and the 36th identification information included in the 33rd identification information is not included in the 15th identification information for non-3GPP access, the UE may not select the first S-NSSAI indicated by the 36th identification information for the IMS service, may not send a registration request message including the first S-NSSAI, or may not send a PDU session establishment request message together with the first S-NSSAI.

[0219] Furthermore, when the UE receives an eleventh identity from the core network, the UE may store the eleventh identity in association with the IMS service. In this case, if the eleventh identity is valid in all PLMNs and the UE moves to a new registration area different from the current registration area, and the UE has not received a first S-NSSAI (the sixteenth identity, the twenty-sixth identity, and / or the thirty-sixth identity) that is valid in the new registration area (supporting the IMS service), the UE may select a default S-NSSAI indicated by the eleventh identity for the IMS service, regardless of whether the new registration area belongs to the current PLMN. Also, if the 11th identity is valid in the current PLMN and the UE moves to a new registration area different from the current registration area, and the UE has not received a first S-NSSAI (the 16th identity, and / or the 26th identity, and / or the 36th identity) that is valid in the new registration area (supporting IMS services), and the new registration area belongs to the current PLMN, the UE may select a default S-NSSAI indicated by the 11th identity for IMS services. Also, if the 11th identity is valid in the current PLMN and the UE moves to a new registration area different from the current registration area, and the UE has not received a first S-NSSAI (the 16th identity, and / or the 26th identity, and / or the 36th identity) that is valid in the new registration area (supporting IMS services), and the new registration area does not belong to the current PLMN, the UE may not select the default S-NSSAI indicated by the 11th identity for IMS services.Also, if the 11th identity is valid in the current PLMN and the UE moves to a new registration area different from the current registration area, and the UE has received a first S-NSSAI (the 16th identity, the 26th identity, and / or the 36th identity) that is valid in the new registration area (supporting the IMS service), the UE may select the first S-NSSAI (the 16th identity, the 26th identity, and / or the 36th identity) for the IMS service. Then, the UE may send a registration request message including the selected default S-NSSAI or the first S-NSSAI, or may send a PDU session establishment request message together with the selected default S-NSSAI or the first S-NSSAI. In other words, if the UE selects an S-NSSAI, it may send a registration request message including the selected default S-NSSAI or the first S-NSSAI, or may send a PDU session establishment request message together with the selected default S-NSSAI or the first S-NSSAI. If the UE does not select an S-NSSAI, it may send a registration request message without including an S-NSSAI. If the UE does not select an S-NSSAI, it may not send a registration request message.

[0220] Furthermore, if the UE has already received the 33rd identification information from the core network, the UE may store the 33rd identification information. In this case, when the UE receives the 12th identification information and the 15th identification information from the core network, the UE may store the 12th identification information in association with the 15th identification information or the S-NSSAI included in the 15th identification information. Then, when the UE requests establishment of a PDU session for an IMS service, the UE may select an S-NSSAI that is valid (usable) in the current registration area from the S-NSSAI included in the 15th identification information and the first S-NSSAI indicated by the 36th identification information based on the 12th identification information, the 15th identification information, and the 33rd identification information, and transmit a registration request message including the S-NSSAI or transmit a PDU session establishment request message together with the S-NSSAI.

[0221] Furthermore, when the UE receives the 12th identification information and the 15th identification information from the core network, the UE may store the 12th identification information in association with the 15th identification information or the S-NSSAI included in the 15th identification information. Then, when the UE requests establishment of a PDU session for an IMS service after receiving the 33rd identification information, the UE may select an S-NSSAI that is valid (usable) in the current registration area from the S-NSSAI included in the 15th identification information and the first S-NSSAI indicated by the 36th identification information based on the 12th identification information, the 15th identification information, and the 33rd identification information, and transmit a registration request message including the S-NSSAI or transmit a PDU session establishment request message together with the S-NSSAI. Note that whether the selected S-NSSAI is valid (usable) in the current registration area may be determined based on the 32nd identification information.

[0222] Also, if the UE has established a PDU session using a first S-NSSAI for an IMS service in a first registration area, and the first S-NSSAI is valid (usable) in the first registration area for the IMS service but not valid in a second registration area, the UE receives, from the core network in the second registration area, fifteenth identification information including the first S-NSSAI, sixteenth identification information indicating the second S-NSSAI, and fourteenth identification information indicating the IMS service corresponding to the second S-NSSAI, and the second S-NSSAI is valid (usable) in the first registration area for the IMS service. If the S-NSSAI is valid in the second registration area, the UE may initiate a PDU session establishment procedure for the IMS service using the second S-NSSAI (supporting the IMS service in the second registration area) based on receiving the fourteenth identity and the sixteenth identity, and then initiate a PDU session release procedure to release the PDU session using the first S-NSSAI (not supporting the IMS service in the second registration area), or may initiate a PDU session release procedure to release the PDU session using the first S-NSSAI, and then initiate a PDU session establishment procedure for the IMS service using the second S-NSSAI. Note that in this case, the UE may use the first S-NSSAI indicated by the fifteenth identity in the second registration area for communications other than the IMS service.

[0223] Furthermore, when a UE communicates using an IMS service and receives the 14th identification information, the 15th identification information, and / or the 16th identification information from the core network, the UE may store the S-NSSAI indicated by the 15th identification information and / or the 16th identification information in association with the IMS service, and may select the requested S-NSSAI based on the current registration area and the stored S-NSSAI, and may send a registration request message including the S-NSSAI, or send a PDU session establishment request message together with the S-NSSAI.

[0224] Furthermore, when a UE communicates using an IMS service and receives the 12th identification information, the 14th identification information, the 15th identification information, and / or the 16th identification information from the core network, the UE may store the S-NSSAI indicated by the 15th identification information and / or the 16th identification information, the IMS service, and the 12th identification information in association with each other, and may select the requested S-NSSAI based on the current registration area and the stored S-NSSAI, and may send a registration request message including the S-NSSAI, or send a PDU session establishment request message together with the S-NSSAI.

[0225] In addition, when a UE communicates using an IMS service, when it receives 15th identification information from the core network, if the value of the SST or SD constituting the S-NSSAI included in the 15th identification information is an S-NSSAI that indicates an IMS service, it may select that S-NSSAI and send a registration request message including that S-NSSAI, or send a PDU session establishment request message together with that S-NSSAI.

[0226] In addition, when the UE communicates using an IMS service, it receives 15th identification information from the core network, and if the position and order of the first S-NSSAI (supporting IMS) included in the 15th identification information and the correspondence between the IMS service and the position and order of the first S-NSSAI included in the 15th identification information are pre-defined by a specification or pre-defined by an operator, the UE may select the first S-NSSAI supporting the IMS service from one or more S-NSSAIs included in the 15th identification information based on its position and order, and send a registration request message including the first S-NSSAI, or send a PDU session establishment request message together with the first S-NSSAI. In this way, if the UE knows in advance the location of the first S-NSSAI in the Allowed NSSAI, it may be able to identify the first S-NSSAI even if it has not received information from the core network that explicitly indicates the correspondence between the IMS service and the first S-NSSAI, such as the 13th identification information, and / or the 14th identification information, and / or the 23rd identification information, and / or the 24th identification information, and / or the 34th identification information.

[0227] In addition, when the UE communicates using an IMS service and receives 13th identification information and 15th identification information from the core network, the UE may select a first S-NSSAI (that supports IMS) from one or more S-NSSAIs included in the 15th identification information based on the information indicated by the 13th identification information, and send a registration request message including the first S-NSSAI, or send a PDU session establishment request message together with the first S-NSSAI.

[0228] In addition, if the UE has previously stored an association between an IMS service and a default S-NSSAI and / or a first S-NSSAI, when communicating using the IMS service, the UE may select the default S-NSSAI or the first S-NSSAI and send a registration request message including the default S-NSSAI or the first S-NSSAI, or send a PDU session establishment request message together with the default S-NSSAI or the first S-NSSAI.

[0229] In addition, when the UE communicates using an IMS service, if the UE receives a 15th identification information including the 16th identification information and the 14th identification information from the core network, the UE may select a first S-NSSAI indicated by the 16th identification information and send a registration request message including the first S-NSSAI, or send a PDU session establishment request message together with the first S-NSSAI.

[0230] Next, if the control message is a registration accept message, the UE may further send a registration complete message to the AMF via the 5G AN (gNB) as a response message to the registration accept message (S612). Here, the registration complete message is an NAS message transmitted and received on the N1 interface, but is transmitted and received between the UE and the 5G AN (gNB) in an RRC message.

[0231] The AMF receives a registration completion message via the 5G AN (gNB) (S612). In addition, each device completes this procedure based on the transmission and reception of the registration acceptance message and / or the registration completion message.

[0232] Alternatively, each device may complete this procedure based on sending and receiving a registration rejection message.

[0233] Each device may transition to or maintain a state in which the UE is registered in the network (RM_REGISTERED state or 5GMM-REGISTERED state) based on the transmission and reception of a registration accept message and / or a registration complete message, or may transition to or maintain a state in which the UE is not registered in the network on the access from which the registration reject message was received for the current PLMN (RM_DEREGISTERED state or 5GMM-DEREGISTERED state) based on the transmission and reception of a registration reject message. Also, the transition to each state of each device may be based on the transmission and reception of a registration accept message and / or a registration complete message and / or a registration reject message, or the completion of this procedure.

[0234] In addition, each device may store the information sent and received in the registration request message and / or registration acceptance message and / or registration completion message and / or registration rejection message, or may recognize the network's decision based on the sending and receiving of the registration request message and / or registration acceptance message and / or registration completion message and / or registration rejection message, or the completion of this procedure.

[0235] Furthermore, each device may determine its next behavior based on the completion of this procedure and based on updated and / or stored memory information.

[0236] Specifically, after completing this procedure, if the device transitions to a registered state on the current access of the current PLMN, each device may initiate a PDU session establishment procedure to establish a PDU session on the current access of the current PLMN.

[0237] Here, the UE may transmit third identification information in the PDU session establishment procedure. The method for selecting the S-NSSAI to be transmitted as the third identification information may use the selection method used when transmitting the S-NSSAI included in the registration request message and / or the RRC message of this procedure. Note that the selected S-NSSAI may be used as the requested NSSAI in the PDU session establishment procedure.

[0238] Specifically, for example, when a UE requests establishment of a PDU session for an IMS service, the UE may select an S-NSSAI to request in the following manner.

[0239] Based on the 15th identity and the 33rd identity, the UE may select and request an S-NSSAI that is valid (usable) in the current registration area for the IMS service from one or more S-NSSAIs included in the 15th identity and an S-NSSAI indicated by the 36th identity included in the 33rd identity.

[0240] The UE may also check from the core network whether the 36th identification information included in the 33rd identification information is included in the 15th identification information, and if the 36th identification information is included in the 15th identification information, select and request the 36th identification information as the third identification information for the IMS service.

[0241] In addition, the UE checks whether the 36th identity is included in the 15th identity, and if the 36th identity is not included in the 15th identity, the UE does not need to select the 36th identity as the third identity for the IMS service. In this case, the UE does not need to initiate a PDU session establishment procedure for the IMS service.

[0242] The UE may also associate and store the default S-NSSAI for the IMS service received as the 11th identity and / or the 21st identity and / or previously set in the UE with the IMS service, and if it is valid in the current registration area, select and request the S-NSSAI indicated in the 11th identity when it has not received or stored a first S-NSSAI (the 16th identity and / or the 26th identity and / or the 36th identity) that is valid in the current registration area (and supports the IMS service).

[0243] Based on the 12th identification information, the 15th identification information, and the 33rd identification information, the UE may select and request an S-NSSAI that is valid (usable) in the current registration area as the third identification information from among the S-NSSAI included in the 15th identification information and the first S-NSSAI indicated by the 36th identification information.

[0244] Alternatively, if the UE stores an Allowed NSSAI associated with the current PLMN, it may select and request an S-NSSAI that is valid (usable) in the current registration area as the third identity based on the stored Allowed NSSAI.

[0245] Specifically, for example, if the value of the SST or SD constituting the S-NSSAI included in the Allowed NSSAI is an S-NSSAI that indicates an IMS service, the UE may select and request that S-NSSAI.

[0246] Alternatively, the UE may select and request an S-NSSAI for the IMS service based on the position and order of the S-NSSAI included in the Allowed NSSAI.

[0247] The registration procedure described in this chapter may be a registration procedure for initial registration, or a registration procedure for movement and periodic registration.

[0248] Furthermore, the UE may initiate the registration procedure of Chapter 3.2, or the generic UE configuration update procedure of Chapter 3.3, or the UE policy management procedure of Chapter 3.4, or the procedure for SM based on the reception of the control message and / or the identification information contained in the control message.

[0249] 3.3. Generic UE Configuration Update Procedure Next, the generic UE configuration update procedure will be described with reference to FIG.

[0250] This procedure may be initiated when the AMF updates the UE configuration for access and mobility management-related parameters. This procedure may also be initiated when the AMF requests the UE to perform a registration procedure for mobility and periodic registration update to update the access and mobility management-related parameters. Furthermore, the UE may initiate the generic UE configuration update procedure based on the completion of the registration procedure in Chapter 3.2, the completion of the generic UE configuration update procedure in Chapter 3.3, the completion of the UE policy management procedure in Chapter 3.4, or the completion of the procedure for SM, etc.

[0251] This procedure begins when the AMF sends a configuration update command to the UE via the access network (S800).

[0252] Here, the setting update command may include at least part of the identification information 21 to 27. Here, the identification information 21 to 27 may be as described in Chapter 2.7. Furthermore, it is preferable that at least one of the pieces of information indicated by the identification information 21 to 27 included in the setting update command is updated from the information indicated by the identification information 11 to 17 transmitted and received in the control message (registration accept message or registration reject message) in the registration procedure described in Chapter 3.2, but it may be the same as the information indicated by the identification information 11 to 17.

[0253] Furthermore, by receiving the setting update command (S800), the UE may be able to understand the meaning of each piece of identification information included in the setting update command and / or the meaning indicated by a combination of each piece of identification information.

[0254] Furthermore, upon receiving the configuration update command, the UE may update the identification information that it has already stored, or may store the received identification information if it has not yet stored the identification information.

[0255] Furthermore, the UE may perform the following processes based on receiving at least one of the identification information items 21 to 27 and / or receiving a configuration update command. Note that the UE may perform these processes during this procedure or after completing this procedure.

[0256] For example, when the UE receives the 21st identity from the core network, the UE may store the 21st identity in association with the IMS service. In this case, if the 21st identity is valid in all PLMNs and the UE moves to a new registration area different from the current registration area, and the UE has not received a first S-NSSAI (the 16th identity, the 26th identity, and / or the 36th identity) that is valid in the new registration area and supports the IMS service, the UE may select the default S-NSSAI indicated by the 21st identity for the IMS service, regardless of whether the new registration area belongs to the current PLMN. Also, if the 21st identity is valid in the current PLMN and the UE moves to a new registration area different from the current registration area, and the UE has not received a first S-NSSAI (the 16th identity, and / or the 26th identity, and / or the 36th identity) that is valid in the new registration area (supporting IMS services), and the new registration area belongs to the current PLMN, the UE may select the default S-NSSAI indicated by the 21st identity for IMS services. Also, if the 21st identity is valid in the current PLMN and the UE moves to a new registration area different from the current registration area, and the UE has not received a first S-NSSAI (the 16th identity, and / or the 26th identity, and / or the 36th identity) that is valid in the new registration area (supporting IMS services), and the new registration area does not belong to the current PLMN, the UE may not select the default S-NSSAI indicated by the 21st identity for IMS services.Also, if the 21st identity is valid in the current PLMN and the UE moves to a new registration area different from the current registration area, and the UE has received a first S-NSSAI (the 16th identity, the 26th identity, and / or the 36th identity) valid in the new registration area (supporting the IMS service), the UE may select the first S-NSSAI (the 16th identity, the 26th identity, and / or the 36th identity) for the IMS service. Then, the UE may send a registration request message including the selected default S-NSSAI or the first S-NSSAI, or may send a PDU session establishment request message together with the selected default S-NSSAI or the first S-NSSAI. In other words, if the UE selects an S-NSSAI, it may send a registration request message including the selected default S-NSSAI or the first S-NSSAI, or may send a PDU session establishment request message together with the selected default S-NSSAI or the first S-NSSAI. If the UE does not select an S-NSSAI, it may send a registration request message without including an S-NSSAI. If the UE does not select an S-NSSAI, it may not send a registration request message.

[0257] Furthermore, if the UE has established a PDU session using a first S-NSSAI for an IMS service in a first registration area, and the first S-NSSAI is valid (usable) for the IMS service in the first registration area but not in the second registration area, and the UE has already received a 15th identification or a 25th identification including the first S-NSSAI from the core network in the second registration area, or has received a 25th identification including the first S-NSSAI in this procedure, and further has received a 26th identification indicating a second S-NSSAI and a 24th identification indicating an IMS service corresponding to the second S-NSSAI in this procedure, If the second S-NSSAI is valid for the IMS service in the second registration area, the UE may, based on receiving the 24th identity and the 26th identity, initiate a PDU session establishment procedure for the IMS service using the second S-NSSAI (supporting the IMS service in the second registration area) and then initiate a PDU session release procedure to release the PDU session using the first S-NSSAI (not supporting the IMS service in the second registration area), or may initiate a PDU session release procedure to release the PDU session using the first S-NSSAI and then initiate a PDU session establishment procedure for the IMS service using the second S-NSSAI. Note that in this case, the UE may use the first S-NSSAI indicated by the 15th identity in the second registration area for communications other than the IMS service.

[0258] Furthermore, when the UE communicates using an IMS service and receives the 24th identification information, the 25th identification information, and / or the 26th identification information from the core network, the UE may store the S-NSSAI indicated by the 25th identification information and / or the 26th identification information in association with the IMS service, and may select the requested S-NSSAI based on the current registration area and the stored S-NSSAI, and may send a registration request message including the S-NSSAI, or send a PDU session establishment request message together with the S-NSSAI.

[0259] Furthermore, when a UE communicates using an IMS service and receives the 22nd identification information, the 24th identification information, the 25th identification information and / or the 26th identification information from the core network, the UE may store the S-NSSAI indicated by the 25th identification information and / or the 26th identification information, the IMS service, and the 22nd identification information in association with each other, and may select the requested S-NSSAI based on the current registration area and the stored S-NSSAI, and may send a registration request message including the S-NSSAI, or send a PDU session establishment request message together with the S-NSSAI.

[0260] In addition, when a UE communicates using an IMS service, when it receives 25th identification information from the core network, if the value of the SST or SD constituting the S-NSSAI included in the 25th identification information is an S-NSSAI that indicates an IMS service, it may select that S-NSSAI and send a registration request message including that S-NSSAI, or send a PDU session establishment request message together with that S-NSSAI.

[0261] In addition, when the UE communicates using an IMS service, it receives 25th identification information from the core network, and if the position and order of the first S-NSSAI (supporting IMS) included in the 25th identification information and the correspondence between the IMS service and the position and order of the first S-NSSAI included in the 25th identification information are pre-defined by a specification or pre-defined by an operator, the UE may select the first S-NSSAI supporting the IMS service from one or more S-NSSAIs included in the 25th identification information based on its position and order, and send a registration request message including the first S-NSSAI, or send a PDU session establishment request message together with the first S-NSSAI. In this way, if the UE knows in advance the location of the first S-NSSAI in the Allowed NSSAI, it may be able to identify the first S-NSSAI even if it has not received information from the core network that explicitly indicates the correspondence between the IMS service and the first S-NSSAI, such as the 13th identification information, and / or the 14th identification information, and / or the 23rd identification information, and / or the 24th identification information, and / or the 34th identification information.

[0262] In addition, when the UE communicates using an IMS service and receives the 23rd identification information and the 25th identification information from the core network, the UE may select a first S-NSSAI (supporting IMS) from one or more S-NSSAIs included in the 25th identification information based on the information indicated by the 23rd identification information, and may send a registration request message including the first S-NSSAI, or send a PDU session establishment request message together with the first S-NSSAI.

[0263] In addition, if the UE has previously stored an association between an IMS service and a default S-NSSAI and / or a first S-NSSAI, when communicating using the IMS service, the UE may select the default S-NSSAI or the first S-NSSAI and send a registration request message including the default S-NSSAI or the first S-NSSAI, or send a PDU session establishment request message together with the default S-NSSAI or the first S-NSSAI.

[0264] Furthermore, each device completes this procedure based on the sending and receiving of the setting update command.

[0265] Furthermore, based on receiving the configuration update command and / or the identification information included in the configuration update command, the UE may initiate the registration procedure of Chapter 3.2, or the generic UE configuration update procedure of Chapter 3.3, or the UE policy management procedure of Chapter 3.4, or the procedure for SM.

[0266] 3.4. UE Policy Management Procedures Next, the UE policy management procedure will be explained with reference to FIG.

[0267] This procedure is used by the PCF to provide one or more UE policies to the UE. For example, the network can perform this procedure to add one or more new UE policies to the UE. The network can also perform this procedure to modify or delete one or more UE policies stored in the UE. Furthermore, the UE may initiate the UE policy management procedure based on the completion of the registration procedure in Chapter 3.2, the generic UE configuration update procedure in Chapter 3.3, the UE policy management procedure in Chapter 3.4, or the procedure for SM.

[0268] This procedure begins when the PCF sends a UE policy management command (MANAGE UE POLICY COMMAND) to the UE via the AMF (S900).

[0269] Here, the UE policy management command may include at least some of the identification information 31 to 37. Here, the identification information 31 to 37 may be as described in Chapter 2.7. The PCF may select and determine which of the identification information 31 to 37 to include in the control message based on the received identification information, and / or subscriber information, and / or network capability information, and / or operator policy, and / or network status, and / or user registration information, and / or context held by the PCF, etc.

[0270] In addition, by receiving a UE policy management command from the PCF (S900), the UE may be able to understand the meaning of each piece of identification information included in the UE policy management command and / or the meaning indicated by the combination of each piece of identification information.

[0271] Furthermore, upon receiving a UE policy management command, the UE may update the identification information that it has already stored, or may store the received identification information if it has not yet stored the identification information.

[0272] Furthermore, the UE may perform the following processes based on receiving at least one of the identification information items 31 to 37 and / or receiving a configuration update command. Note that the UE may perform these processes during this procedure or after completing this procedure.

[0273] For example, if the UE has already received the 15th identification information from the core network, when the UE receives the 33rd identification information in this procedure and requests the establishment of a PDU session for an IMS service, the UE may select an S-NSSAI that is valid (usable) in the current registration area from one or more S-NSSAIs included in the 15th identification information and the S-NSSAI indicated by the 36th identification information included in the 33rd identification information based on the 15th identification information and the 33rd identification information, and may send a registration request message including that S-NSSAI, or send a PDU session establishment request message together with that S-NSSAI.

[0274] Furthermore, if the UE has already received the 15th identification information and the 33rd identification information from the core network and the 33rd identification information does not include the 32nd identification information, the UE may determine that the S-NSSAI indicated by the 36th identification information included in the 33rd identification information is valid in the current registration area, or valid within the current PLMN, or valid in all PLMNs, and may select an S-NSSAI that is valid (usable) in the current registration area for the IMS service from one or more S-NSSAIs included in the 15th identification information and the S-NSSAI indicated by the 36th identification information included in the 33rd identification information, and may send a registration request message including that S-NSSAI or send a PDU session establishment request message together with that S-NSSAI.

[0275] Furthermore, if the UE has already received the 15th identification information from the core network, and receives the 33rd identification information in this procedure, and the 36th identification information included in the 33rd identification information is the first S-NSSAI selected by the PCF from the Allowed NSSAIs, and when requesting establishment of a PDU session for an IMS service, the UE may select the first S-NSSAI (the 36th identification information included in the 33rd identification information) based on the 33rd identification information, and send a registration request message including the first S-NSSAI, or send a PDU session establishment request message together with the first S-NSSAI.

[0276] Furthermore, when the UE has already received the 15th identity from the core network and receives the 33rd identity in this procedure and requests establishment of a PDU session for an IMS service, the UE may check whether the 36th identity included in the 33rd identity is included in the 15th identity, and if the 36th identity is included in the 15th identity, select a first S-NSSAI indicated by the 36th identity and transmit a registration request message including the first S-NSSAI or transmit a PDU session establishment request message together with the first S-NSSAI. Furthermore, the UE may check whether the 36th identity is included in the 15th identity, and if the 36th identity is not included in the 15th identity, not select the first S-NSSAI indicated by the 36th identity for the IMS service, and not transmit a registration request message including the first S-NSSAI or transmit a PDU session establishment request message together with the first S-NSSAI. Furthermore, in this case, the UE may send a UE policy management command rejection message including the 41st identification information (S902).

[0277] Furthermore, the UE may check for each access whether the 36th identification information included in the 33rd identification information is included in the 15th identification information. That is, the UE may check for each of 3GPP access and non-3GPP access whether the 36th identification information included in the 33rd identification information is included in the 15th identification information.

[0278] For example, if the 36th identity included in the 33rd identity is included in the 15th identity for 3GPP access, but the 36th identity included in the 33rd identity is not included in the 15th identity for non-3GPP access, the UE may send, for an IMS service, a registration request message including a first S-NSSAI indicated by the 36th identity via the 3GPP access, or may send a PDU session establishment request message together with the first S-NSSAI indicated by the 36th identity via the 3GPP access. In this case, the UE may send, for non-3GPP access, a UE policy management command rejection message including the 41st identity indicating that the S-NSSAI is unavailable in the current registration area or that the provided S-NSSAI is unavailable in the current registration area (S902).

[0279] Furthermore, if the 36th identity included in the 33rd identity is not included in the 15th identity for 3GPP access, and the 36th identity included in the 33rd identity is included in the 15th identity for non-3GPP access, the UE may send, for an IMS service, a registration request message including a first S-NSSAI indicated by the 36th identity via the non-3GPP access, or may send a PDU session establishment request message together with the first S-NSSAI indicated by the 36th identity via the non-3GPP access. In this case, the UE may send, for 3GPP access, a UE policy management command rejection message including the 41st identity indicating that the S-NSSAI is unavailable in the current registration area or that the provided S-NSSAI is unavailable in the current registration area (S902).

[0280] Furthermore, when the 36th identity included in the 33rd identity is included in the 15th identity for 3GPP access and the 36th identity included in the 33rd identity is included in the 15th identity for non-3GPP access, the UE may select whether to transmit from the 3GPP access or the non-3GPP access for the IMS service, and may transmit a registration request message including the first S-NSSAI indicated by the 36th identity or a PDU session establishment request message together with the first S-NSSAI indicated by the 36th identity via the selected access. In this case, the UE does not need to transmit a UE policy management command reject message including the 41st identity.

[0281] Furthermore, if the 36th identity included in the 33rd identity is not included in the 15th identity for 3GPP access, and the 36th identity included in the 33rd identity is not included in the 15th identity for non-3GPP access, the UE may not select the first S-NSSAI indicated by the 36th identity for the IMS service, and may not send a registration request message including the first S-NSSAI or may not send a PDU session establishment request message together with the first S-NSSAI. In this case, the UE may send a UE policy management command rejection message including the 41st identity for 3GPP access and non-3GPP access, indicating that the S-NSSAI is unavailable in the current registration area or that the provided S-NSSAI is unavailable in the current registration area (S902).

[0282] Furthermore, when the UE receives the 31st identity from the core network, the UE may store the 31st identity in association with the IMS service. In this case, if the 31st identity is valid in all PLMNs, and the UE moves to a new registration area different from the current registration area, and the UE has not received a first S-NSSAI (the 16th identity, the 26th identity, and / or the 36th identity) that is valid in the new registration area (supporting the IMS service), the UE may select a default S-NSSAI indicated by the 31st identity for the IMS service, regardless of whether the new registration area belongs to the current PLMN. Also, if the 31st identity is valid in the current PLMN and the UE moves to a new registration area different from the current registration area, and the UE has not received a first S-NSSAI (the 16th identity, and / or the 26th identity, and / or the 36th identity) that is valid in the new registration area (supporting IMS services), and the new registration area belongs to the current PLMN, the UE may select a default S-NSSAI indicated by the 31st identity for IMS services. Also, if the 31st identity is valid in the current PLMN and the UE moves to a new registration area different from the current registration area, and the UE has not received a first S-NSSAI (the 16th identity, and / or the 26th identity, and / or the 36th identity) that is valid in the new registration area (supporting IMS services), and the new registration area does not belong to the current PLMN, the UE may not select the default S-NSSAI indicated by the 31st identity for IMS services.Also, if the 31st identity is valid in the current PLMN and the UE moves to a new registration area different from the current registration area, and the UE has received a first S-NSSAI (the 16th identity, the 26th identity, and / or the 36th identity) valid in the new registration area (supporting the IMS service), the UE may select the first S-NSSAI (the 16th identity, the 26th identity, and / or the 36th identity) for the IMS service. Then, the UE may send a registration request message including the selected default S-NSSAI or the first S-NSSAI, or a PDU session establishment request message together with the selected default S-NSSAI or the first S-NSSAI.

[0283] Furthermore, if the UE has already received the 12th identification information and the 15th identification information from the core network, the UE may associate the 12th identification information with the 15th identification information or the S-NSSAI included in the 15th identification information and store them. In this case, when the 33rd identification information is received from the core network in this procedure, the UE may store the 33rd identification information. Then, when requesting establishment of a PDU session for an IMS service, the UE may select an S-NSSAI that is valid (usable) in the current registration area from the S-NSSAI included in the 15th identification information and the first S-NSSAI indicated by the 36th identification information based on the 12th identification information, the 15th identification information, and the 33rd identification information, and transmit a registration request message including the S-NSSAI or transmit a PDU session establishment request message together with the S-NSSAI.

[0284] Furthermore, if the UE has established a PDU session using a first S-NSSAI for an IMS service in a first registration area, and the first S-NSSAI is valid (usable) for the IMS service in the first registration area but not valid in the second registration area, and the UE has already received the 15th identification information, the 25th identification information, or the 36th identification information including the first S-NSSAI from the core network in the second registration area, or has received the 36th identification information including the first S-NSSAI in this procedure, and further has received the 36th identification information indicating the second S-NSSAI and the 35th identification information indicating the IMS service corresponding to the second S-NSSAI in this procedure, If the second S-NSSAI is valid for the IMS service in the second registration area, the UE may, based on the reception of the 35th identity and the 36th identity, initiate a PDU session establishment procedure for the IMS service using the second S-NSSAI (supporting the IMS service in the second registration area) and then initiate a PDU session release procedure to release the PDU session using the first S-NSSAI (not supporting the IMS service in the second registration area), or may initiate a PDU session release procedure to release the PDU session using the first S-NSSAI and then initiate a PDU session establishment procedure for the IMS service using the second S-NSSAI. Note that in this case, the UE may use the first S-NSSAI indicated by the 15th identity in the second registration area for communications other than the IMS service.

[0285] In addition, if the UE has previously stored an association between an IMS service and a default S-NSSAI and / or a first S-NSSAI, when communicating using the IMS service, the UE may select the default S-NSSAI or the first S-NSSAI and send a registration request message including the default S-NSSAI or the first S-NSSAI, or send a PDU session establishment request message together with the default S-NSSAI or the first S-NSSAI.

[0286] In addition, each device completes this procedure based on sending and receiving a UE policy management command and / or a UE policy management command rejection message.

[0287] Furthermore, the UE may initiate the registration procedure of Chapter 3.2, or the generic UE configuration update procedure of Chapter 3.3, or the UE policy management procedure of Chapter 3.4, or the procedure for SM based on receiving the UE policy management command message and / or the identification information included in the UE policy management command message.

[0288] 4. Variations A program running on an apparatus according to one aspect of the present invention may be a program that controls a central processing unit (CPU) or the like to cause a computer to function so as to realize the functions of an embodiment according to one aspect of the present invention. The program or information handled by the program is temporarily stored in a volatile memory such as a random access memory (RAM), a non-volatile memory such as a flash memory, a hard disk drive (HDD), or another storage device system.

[0289] A program for implementing the functions of an embodiment according to one aspect of the present invention may be recorded on a computer-readable recording medium. The program may be loaded into a computer system and executed. The term "computer system" as used herein refers to a computer system built into a device, including hardware such as an operating system and peripheral devices. The term "computer-readable recording medium" may refer to a semiconductor recording medium, an optical recording medium, a magnetic recording medium, a medium that dynamically stores a program for a short period of time, or any other computer-readable recording medium.

[0290] Additionally, each functional block or feature of the device used in the above-described embodiments may be implemented or performed by an electrical circuit, such as an integrated circuit or multiple integrated circuits. The electrical circuit designed to perform the functions described herein may include a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or a combination thereof. The general-purpose processor may be a microprocessor, or a conventional processor, controller, microcontroller, or state machine. The electrical circuit may be composed of digital circuits or analog circuits. Furthermore, as advances in semiconductor technology emerge, one or more aspects of the present invention may utilize new integrated circuit technologies that replace current integrated circuits.

[0291] It should be noted that one aspect of the present invention is not limited to the above-described embodiment. Although one example of a device has been described in the embodiment, one aspect of the present invention is not limited to this, and can be applied to terminal devices or communication devices for stationary or non-movable electronic devices installed indoors or outdoors, such as AV equipment, kitchen equipment, cleaning / washing equipment, air conditioning equipment, office equipment, vending machines, and other household appliances.

[0292] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment and includes design modifications within the scope of the invention. Furthermore, the present invention is susceptible to various modifications within the scope of the claims, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. Furthermore, configurations in which elements described in the above embodiments are substituted with elements that achieve the same effect are also included.

Claims

1. A UE (User Equipment) including a transceiver unit and a control unit, The transmitting / receiving unit Receive a registration acceptance message including an Allowed Network Slice Selection Assistance Information (NSSA) from the Access and Mobility Management Function (AMF), Receive a UE policy management command message including a UE Route Selection Policy (URSP) from a PCF (Policy Control Function); the Allowed NSSAI includes a first Single Network Slice Selection Assistance Information (S-NSSAI) for an IMS service; The URSP includes the first S-NSSAI and first information; the first information is information indicating a registration area in which the first S-NSSAI can be used, When the control unit requests establishment of a PDU session for an IMS service, if the control unit determines, based on the URSP, that the first S-NSSAI included in the Allowed NSSAI is usable in a current registration area, the control unit selects the first S-NSSAI for the IMS service. A UE characterized by:

2. A communication control method executed by a UE (User Equipment), Receive a registration acceptance message including an Allowed Network Slice Selection Assistance Information (NSSA) from the Access and Mobility Management Function (AMF), Receive a UE policy management command message including a UE Route Selection Policy (URSP) from a PCF (Policy Control Function); the Allowed NSSAI includes a first Single Network Slice Selection Assistance Information (S-NSSAI) for an IMS service; the URSP includes the first S-NSSAI and first information; the first information is information indicating a registration area in which the first S-NSSAI can be used, When requesting establishment of a PDU session for an IMS service, if it is determined based on the URSP that the first S-NSSAI included in the Allowed NSSAI is usable in a current registration area, select the first S-NSSAI for the IMS service. A communication control method executed by a UE.

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