JP7719626B2 - UE (User Equipment) - Google Patents

Description

The present invention relates to UE (User Equipment).

The 3GPP (3rd Generation Partnership Project) is studying the system architecture of the 5G System (5GS), a fifth-generation (5G) mobile communications system, and is discussing how to support new procedures and new functions (see Non-Patent Documents 1 and 2). The initial release of the 5G standard, Release 15, introduced the concept of network slicing, and in Release 17, functional expansion of network slicing is being discussed (see Non-Patent Document 3).

3GPP TS 23.501 V17.0.0 (2021-03); 3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; System architecture for the 5G System (5GS); Stage 2 (Release 17) 3GPP TS 23.502 V17.0.0 (2021-03); 3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Procedures for the 5G System (5GS); Stage 2 (Release 17) 3GPP TR 23.700-40 V17.0.0 (2021-03); 3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Study on Enhancement of Network Slicing Phase 2 (Release 17)

Non-patent document 3 does not disclose detailed operations related to network slice access control that take into account interworking between 5GS or 5GC (5G Core Network) and EPC (Evolved Packet Core), the core network of the 4G system.

One aspect of the present invention was made in consideration of the above circumstances, and aims to clarify the detailed operation of network slice access control that takes into account interworking between 5GS or 5GC and EPC, the core network of the 4G system.

One aspect of the present invention is a UE (User Equipment) comprising a transceiver and a controller, wherein the transceiver receives a registration accept message or a registration reject message from a base station device, the registration accept message including a cause value indicating that the maximum number of UEs per network slice has been exceeded, and the controller, if E-UTRA capability is disabled, enables E-UTRA capability, disables N1 mode capability for 3GPP access, and transitions to a 5GMM-DEREGISTERED.NO-CELL-AVAILABLE state.

This invention clarifies detailed operations related to network slice access control, taking into account interworking between 5GS or 5GC and EPC, the core network of the 4G system.

FIG. 1 is a diagram illustrating an outline of a mobile communication system (EPS/5GS). FIG. 1 is a diagram illustrating the detailed configuration of a mobile communication system (EPS/5GS). FIG. 1 is a diagram illustrating the device configuration of a UE. A diagram explaining the configuration of an access network device (gNB) in 5GS. A diagram explaining the configuration of core network devices (AMF/SMF/UPF) in 5GS. FIG. 10 is a diagram illustrating a registration procedure. A diagram explaining the PDU session establishment procedure.

The best mode for carrying out the present invention will be described below with reference to the drawings. In this embodiment, we will describe an example of a mobile communications system to which the present invention is applied.

[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.

Figure 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.

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

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.

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.

Note that the 4G system, EPS (Evolved Packet System), is composed of an access network A and a core network A, but may also include a UE and/or a PDN. Also, the 5G system, 5GS (5G System), is composed of a UE, access network B, and core network B, but may also include a DN.

A UE is a device that can connect to network services 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 smartphone, and may be a terminal device that can connect to both EPS and 5GS. A UE may be equipped with a UICC (Universal Integrated Circuit Card) or eUICC (Embedded UICC). Note that a UE may be referred to as either a user device or a terminal device.

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, eNBs 45 may be referred to by abbreviating the symbol eNB. Furthermore, 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.

Furthermore, access network_B corresponds to a 5G access network (5G AN). A 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 symbol for gNB 122 may be abbreviated, such as gNB. A 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, a gNB is a base station device newly designed for 5GS, and has different functions from the base station device (eNB) used in the 4G system, EPS. Furthermore, when there are multiple gNBs, the gNBs are connected to each other, for example, via an Xn interface.

Furthermore, the non-3GPP access network may be an untrusted non-3GPP access network or a trusted non-3GPP access network. Here, an 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, a trusted non-3GPP access network may be an access network specified by 3GPP, and may include a TNAP (trusted non-3GPP access point) and a TNGF (trusted non-3GPP gateway function).

Furthermore, in the following, E-UTRAN and NG-RAN may be referred to as 3GPP access. Furthermore, wireless LAN access networks and non-3GPP ANs may be referred to as non-3GPP access. Furthermore, nodes deployed in access network B may be collectively referred to as NG-RAN nodes.

Furthermore, hereinafter, 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.

Core network_A corresponds to the EPC (Evolved Packet Core). The EPC 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).

In addition, core network_B corresponds to 5GCN (5G Core Network). 5GCN includes, for example, AMF (Access and Mobility Management Function), UPF (User Plane Function), SMF (Session Management Function), PCF (Policy Control Function), UDM (Unified Data Management), etc. Here, 5GCN may also be expressed as 5GC.

Furthermore, 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 a core network.

The core network (Core Network A and/or Core Network B) may be an IP mobile communications network operated by a mobile network operator (MNO) that connects the access network (Access Network A and/or Access Network B) with the PDN and/or DN, or it may be a core network for a mobile network operator that operates and manages mobile communications system 1, or it may be a core network for a virtual mobile communications operator or virtual mobile communications service provider such as an MVNO (Mobile Virtual Network Operator) or MVNE (Mobile Virtual Network Enabler).

Also, while Figure 1 shows 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 connected communication terminals. Therefore, connecting to a PDN may mean connecting to a communication terminal or server device located in the PDN. Furthermore, transmitting and receiving user data to and from a PDN may mean transmitting and receiving user data to and from a communication terminal or 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.

Furthermore, in the following, at least a portion of Access Network _A, Core Network _A, PDN, Access Network _B, Core Network _B, DN, and/or one or more devices included therein may be referred to as a network or network device. In other words, when a network and/or network device sends and receives messages and/or performs a procedure, it means that at least a portion of Access Network _A, Core Network _A, PDN, Access Network _B, Core Network _B, DN, and/or one or more devices included therein send and receive messages and/or perform a procedure.

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 core network. In other words, the UE can send and receive user data (communicate) with a PDN or DN. When sending and receiving user data, not only IP (Internet Protocol) communication but also non-IP communication can be used.

Here, IP communication refers to data communication using IP, and data is sent and received using IP packets. An IP packet consists of an IP header and a payload portion. The payload portion may contain data sent 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 sent and received in a format different from the IP packet structure. For example, non-IP communication may be data communication achieved by sending and receiving application data without an IP header, or it may be user data sent and received by a UE with a different header, such as a MAC header or an Ethernet (registered trademark) frame header, added.

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 Figure 2. For example, core network_A and/or core network_B may include an AUSF (Authentication Server Function) or an AAA (Authentication, Authorization, and Accounting) server (AAA-S).

Here, AUSF is a core network device equipped with authentication functions for 3GPP access and non-3GPP access. Specifically, it is a network function unit that receives authentication requests for 3GPP access and/or non-3GPP access from the UE and executes the authentication procedure.

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 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.

Note that in Figure 2, for simplicity's sake, each device and function is shown one by one, but the mobile communication system 1 may be configured with multiple similar devices and functions. 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.

[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.

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 composed of, for example, semiconductor memory, SSD (Solid State Drive), HDD (Hard Disk Drive), etc. Furthermore, each memory unit can store not only information that was originally configured at the time of shipment, but also various information sent 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 sent and received within the 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 sent and received between devices/functions included in 5GS and/or EPS. At this time, it is possible to store not only data sent and received via the N26 interface, but also data sent and received without going through the N26 interface.

[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.

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

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 the access network device, and/or core network device, and/or PDN, and/or DN.

Explaining in more 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 send 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.

The memory unit_A340 is a functional unit for storing programs, user data, control information, etc. required for each operation of the UE.

[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.

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

The network connection unit _B520 is a functional unit that enables the gNB to communicate with the AMF and/or UPF. In other words, the gNB can send and receive user data and/or control information between the AMF and/or UPF using the network connection unit _B520.

Transmitter/receiver unit_B530 is a functional unit for wireless communication with the UE via antenna 510. In other words, the gNB can transmit and receive user data and/or control information to and from the UE using transmitter/receiver unit_B530.

Referring to Figure 2 in more detail, a gNB in a 5G AN can communicate with the AMF via the N2 interface by using the network connection unit _B520, and can communicate with the UPF via the N3 interface. The gNB can also communicate with the UE by using the transceiver unit _B530.

The memory unit_B540 is a functional unit for storing programs, user data, control information, etc. required for each operation of the gNB.

[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.

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

The network connection unit _B720 is a functional unit that allows the AMF to connect to a base station device (gNB), and/or SMF, and/or PCF, and/or UDM, and/or SCEF within 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 within a 5G AN.

Explaining in more detail with reference to Figure 2, the AMF in the 5GCN can communicate with the gNB via the N2 interface by using the network connection unit A620, can communicate with the UDM via the N8 interface, can communicate with the SMF via the N11 interface, and can communicate with the PCF via the N15 interface. The AMF can also send and receive NAS messages with the 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 actually occurs via the 5G AN. Furthermore, if the AMF supports the N26 interface, it can communicate with the MME via the N26 interface by using the network connection unit A620.

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

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), connection management (CM), reachability management, mobility management for UEs, transferring Session Management (SM) messages between the UE and SMF, access authentication (Access Authorization), security anchor functionality (SEA), security context management (SCM), supporting the N2 interface for the N3IWF (Non-3GPP Interworking Function), supporting the sending and receiving of NAS signals with the UE via the N3IWF, and authenticating UEs connected via the N3IWF.

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

In other words, 5GMM-REGISTERED may mean that each device has established a 5GMM context, or that each device has established a PDU session context. When each device is 5GMM-REGISTERED, UE_A10 may start sending 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.

Furthermore, 5GMM-DEREGISTERED may mean that each device has not established a 5GMM context, that the network does not know the location information of UE_A10, or that the network is unable to reach UE_A10. Note that when each device is 5GMM-DEREGISTERED, UE_A10 may initiate a registration procedure or establish a 5GMM context by performing the registration procedure.

Connection management also manages the CM state for each UE. The CM state may be synchronized between the UE and the AMF. CM states include a CM-IDLE state and a 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.

Furthermore, connection management may be performed separately for the CM state in 3GPP access and the CM state in non-3GPP access. 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 idle mode, and the connected state mode may be expressed as connected mode.

The CM state may also be expressed as 5GMM mode. In this case, the unconnected state may also be expressed as 5GMM-IDLE mode, and the connected state may also be expressed as 5GMM-CONNECTED mode. Furthermore, the unconnected state in 3GPP access may also be expressed as 5GMM-IDLE mode over 3GPP access, and the connected state in 3GPP access may also be expressed as 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 5GMM unconnected mode may also be expressed as idle mode, and 5GMM connected mode may also be expressed as connected mode.

In addition, one or more AMFs may be deployed within the core network_B. An AMF may also be a Network Function (NF) that manages one or more Network Slice Instances (NSIs). An AMF may also be a shared CP function (CCNF; Common CPNF (Control Plane Network Function)) shared among multiple NSIs.

Note that 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.

[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.

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

The network connection unit _B720 is a functional unit that allows the SMF to connect to 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.

Referring to Figure 2 in more detail, 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.

The memory unit_B740 is a functional unit for storing programs, user data, control information, etc. required for each SMF operation.

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 AMF, determining the SSC mode (Session and Service Continuity mode) for the session, and roaming functions.

[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.

The control unit _B700 is a functional unit that controls the operation and functions of the entire UPF. The control unit _B700 performs various processes in the UPF by reading and executing various programs stored in the memory unit _B740 as needed.

The network connection unit _B720 is a functional unit that allows the UPF to connect to base station devices (gNBs), and/or SMFs, and/or DNs within the 5G AN. In other words, the UPF can use the network connection unit _B720 to send and receive user data and/or control information between base station devices (gNBs), and/or SMFs, and/or DNs within the 5G AN.

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

The memory unit_B740 is a functional unit for storing programs, user data, control information, etc. required for each operation of the UPF.

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

The UPF may also be a gateway for IP communications and/or non-IP communications. The UPF may also have the function of forwarding IP communications and the function of converting non-IP communications to IP communications. 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.

The user plane refers to user data transmitted and received between the UE and the network. The user plane may be transmitted and received using a PDN connection in the case of 4G, or a PDU session in the case of 5G. 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.

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

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

[2.6. Description of other devices and/or functions and identification information in this embodiment]
Next, other devices and/or functions and identification information will be described.

The term "network" refers to at least a portion of the access network _B, core network _B, and DN. Furthermore, one or more devices included in at least a portion of the access network _B, core network _B, and DN may also be referred to as a network or 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, 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.

Furthermore, an NSSF (Network Slice Selection Function) may be a network function (also referred to as an NF) that has the function of selecting a network slice to serve a UE.

In addition, an NWDAF (Network Data Analytics Function) may be an NF that has the function of collecting data from NFs and application functions (also referred to as AFs).

Furthermore, a PCF (Policy Control Function) may be an NF that has the function of determining policies for controlling network behavior.

Furthermore, an NRF (Network Repository Function) may be an NF with a service discovery function. An NRF may be an NF with the function of providing information about the discovered NF when it receives a discovery request for another NF from another NF.

The NSACF (Network Slice Admission Control Function) may also have the functionality to monitor and control the number of registered UEs per NS and/or the number of PDU sessions per NS for network slices (NSs) associated with the NSAC (Network Slice Admission Control). The NSACF may also be configured with a maximum number of permitted UEs per NS and/or a maximum number of permitted PDU sessions per NS for each NS associated with the NSAC. The NSACF may also have the functionality to increase or decrease the number of UEs registered with an NS so as not to exceed the maximum number of UEs permitted to register with that NS. The NSACF may also maintain a list of UE IDs registered with an NS associated with an NSAC. When the number of UEs registered with an NS increases (e.g., when a UE sends a new registration request message to that NS), the NSACF may also have the functionality to check whether the ID of that UE is already included in the list of UE IDs registered with that NS. If the ID of that UE is not included in the list, the NSACF may further check with that NS whether the maximum number of UEs per NS has been reached. Furthermore, when the registration status of a UE for an NS associated with an NSAC changes during a registration procedure, a deregistration procedure, and/or an NSSAA procedure, the AMF may request the NSACF regarding the maximum number of UEs per NS. The NSACF may also have a function to increase or decrease the number of PDU sessions for an NS so as not to exceed the maximum number of PDU sessions permitted by that NS. When the number of PDU sessions using an NS increases (for example, when a UE sends a PDU session establishment request message to that NS), the NSACF may also have a function to check with that NS whether the maximum number of UEs per NS has been reached. The SMF may also request the NSACF regarding the maximum number of PDU sessions per NS during a PDU session establishment procedure and/or a PDU session release procedure.

Furthermore, an SM (Session Management) message (also referred to as a NAS (Non-Access-Stratum) SM message) may be a NAS message used in procedures for SM, or may be a control message sent and received between UE_A10 and SMF_A230 via AMF_A240. Furthermore, SM messages 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.

Furthermore, the procedures for SM or SM procedures 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 network.

Furthermore, an MM (Mobility management) message (also referred to as a NAS MM message) may be a NAS message used in MM procedures, and may be a control message transmitted and received between UE_A10 and AMF_A240. Furthermore, MM messages 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.

Furthermore, 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.

Furthermore, 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.

Furthermore, non-5GS services may be services other than 5GS services, and may include EPS services and/or non-EPS services.

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 rather via a communication method other than IP.

A PDU (Protocol Data Unit) session can be defined as an association between a DN that provides PDU connectivity services 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, etc. The UE can use the PDU session to transmit and receive user data to and from devices such as an application server located in the DN.

In addition, 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. This identification information may include one or more of the following: DNN, QoS rule, PDU session type, application identification information, NSI identification information, and access network identification information, 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.

The DNN (Data Network Name) may be identification information that identifies the 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 also be equivalent to an APN (Access Point Name).

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. Ethernet may also 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 a 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.

A PLMN (Public Land Mobile Network) is a communications network that provides mobile wireless communications services. A PLMN is a network managed by an operator, 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, a 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).

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. Network slices are sometimes simply referred to as slices.

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 an NS, of which one or more are configured within the core network _B. An NSI may also be composed of a virtual NF (Network Function) generated using an NST (Network Slice Template). Here, an NST is associated with resource requirements for providing the required communication services and capabilities, and is a logical representation of one or more NFs. In other words, an NSI may be a collection within the core network _B190 composed of multiple NFs. An NSI may also be a logical network configured to separate user data delivered by services, etc. One or more NFs may be configured in 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 NSI IDs, and/or an APN. 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.

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 both an SST and an SD (Slice Differentiator). Here, the SST is information indicating the expected behavior of the NS in terms of functionality 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 standard information shared among PLMNs. The network may store one or more S-NSSAIs in the UE's registration information as default S-NSSAIs. If the S-NSSAI is the default S-NSSAI, and the UE does not send a valid S-NSSAI to the network in a registration request message, the network may provide the NS associated with the UE.

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. The NSSAI may also be information used to select an AMF.

The configured NSSAI (also referred to as the configured NSSAI) is an NSSAI that is provided and stored in the UE. The UE may store the configured NSSAI for each PLMN. The configured NSSAI may be information configured by the network (or PLMN). The S-NSSAI included in the configured NSSAI may be expressed as the configured S-NSSAI. The configured S-NSSAI may be configured to include the S-NSSAI and the mapped S-NSSAI.

The requested NSSAI (also referred to as the Requested NSSAI) is an NSSAI provided by 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 the network slice that the UE wishes to access. The S-NSSAI included in the requested NSSAI may be expressed as the requested S-NSSAI. For example, the requested NSSAI is transmitted in an NAS message or an RRC (Radio Resource Control) message including a NAS (Non-Access-Stratum) message transmitted from the UE to the network, such as a registration request message or a PDU session establishment request message.

Also, the allowed NSSAI (also referred to as the permitted NSSAI or Allowed NSSAI) is information indicating one or more network slices to which the UE is allowed. In other words, the allowed NSSAI is information that identifies the network slice to which the network has allowed 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 an S-NSSAI and a mapped S-NSSAI.

Furthermore, a mapped S-NSSAI (also referred to as a mapped S-NSSAI) is an S-NSSAI of an HPLMN mapped to an S-NSSAI of a registered PLMN in a roaming scenario. The UE may store one or more mapped S-NSSAIs mapped to the configured NSSAI and the S-NSSAI included in the Allowed NSSAI for each access type. Furthermore, the UE may store one or more mapped S-NSSAIs for the S-NSSAI included in the rejected NSSAI.

Furthermore, a rejected NSSAI (also referred to as a rejected NSSAI) is information indicating one or more network slices to which the UE is not permitted to connect. In other words, a rejected NSSAI is information identifying a network slice to which the network does not permit the UE to connect. A rejected NSSAI may be information including one or more combinations of an S-NSSAI and a rejection reason value. Here, the rejection reason value is information indicating the reason why the network rejects the corresponding S-NSSAI. The UE and the network may store and manage the rejected NSSAI appropriately based on the rejection reason value associated with each S-NSSAI. Furthermore, the rejected NSSAI may be included in an NAS message sent from the network to the UE, such as a registration accept message, a configuration update command, or a registration rejection message, or in an RRC message including an NAS message. An S-NSSAI included in a rejected NSSAI may be expressed as a rejected S-NSSAI. The rejected NSSAI may be any one of the first to third rejected NSSAIs, a pending NSSAI, or a combination of these. An S-NSSAI included in a rejected NSSAI may be expressed as a rejected S-NSSAI. The rejected S-NSSAI may be composed of an S-NSSAI and a mapped S-NSSAI.

Here, the first rejected NSSAI is a set of one or more S-NSSAIs that the UE included in the requested NSSAI and that are unavailable in the current PLMN. The first rejected NSSAI may be a 5GS rejected NSSAI for the current PLMN, a rejected S-NSSAI for the current PLMN, or an S-NSSAI included in the rejected NSSAI for the current PLMN. The first rejected NSSAI may be a rejected NSSAI stored by the UE or the NW, or may be a rejected NSSAI sent from the NW to the UE. If the first rejected NSSAI is a rejected NSSAI sent from the NW to the UE, the first rejected NSSAI may be information that includes one or more combinations of an S-NSSAI and a reason value. The rejection reason value at this time may be "S-NSSAI is not available in the current PLMN" or may be information indicating that the S-NSSAI associated with the rejection reason value is not available in the current PLMN.

The first rejected NSSAI is valid for the entire registered PLMN. In other words, the UE and/or NW may treat the first rejected NSSAI and the S-NSSAI included in the first rejected NSSAI as information independent of the access type. In other words, the first rejected NSSAI may be information valid for both 3GPP access and non-3GPP access.

The UE may delete the first rejected NSSAI from its memory if it transitions to an unregistered state for the current PLMN in both 3GPP access and non-3GPP access. In other words, if the UE transitions to an unregistered state for the current PLMN via one access, or if it successfully registers to a new PLMN via one access, or if it fails to register to the new PLMN via one access and transitions to an unregistered state, and if the UE is not registered (unregistered) via the other access, the UE deletes the first rejected NSSAI.

The second rejected NSSAI is a set of one or more S-NSSAIs that the UE included in the requested NSSAI are unavailable in the current registration area. The second rejected NSSAI may be a 5GS rejected NSSAI for the current registration area. The second rejected NSSAI may be a rejected NSSAI stored by the UE or the NW, or may be a rejected NSSAI transmitted from the NW to the UE. If the second rejected NSSAI is a rejected NSSAI transmitted from the NW to the UE, the second rejected NSSAI may be information including one or more combinations of an S-NSSAI and a reason value. In this case, the reason value may be "S-NSSAI is not available in the current registration area" or may be information indicating that the S-NSSAI associated with the reason value is unavailable in the current registration area.

The second rejected NSSAI is also valid within the current registration area. That is, the UE and/or NW may treat the second rejected NSSAI and the S-NSSAI included in the second rejected NSSAI as information for each access type. That is, the second rejected NSSAI may be information valid for either 3GPP access or non-3GPP access. That is, once the UE transitions to an unregistered state for a certain access, it may delete the second rejected NSSAI from its memory.

The third rejected NSSAI is a set of one or more S-NSSAIs that require an NSSAA and for which the NSSAA for that S-NSSAI has failed or been revoked. The third rejected NSSAI may be an NSSAI stored by the UE and/or NW, or may be transmitted from the NW to the UE. When the third rejected NSSAI is transmitted from the NW to the UE, the third rejected NSSAI may be information that includes one or more combinations of an S-NSSAI and a rejection reason value. In this case, the rejection reason value may be "S-NSSAI is not available due to the failed or revoked NSSAA" or may be information indicating that the NSSAA for the S-NSSAI associated with the rejection reason value has failed or been revoked.

The third rejected NSSAI is also valid across the entire registered PLMN. In other words, the UE and/or NW may treat the third rejected NSSAI and the S-NSSAI included in the third rejected NSSAI as information independent of the access type. In other words, the third rejected NSSAI may be information valid for both 3GPP access and non-3GPP access. The third rejected NSSAI may be an NSSAI different from the rejected NSSAI. The third rejected NSSAI may also be the first rejected NSSAI.

The third rejected NSSAI is a rejected NSSAI that identifies a slice that the UE has rejected due to an NSSAA failure or cancellation from the core network. Specifically, while the UE stores the third rejected NSSAI, it does not initiate a registration request procedure for the S-NSSAI included in the third rejected NSSAI. The third rejected NSSAI may be identification information including one or more S-NSSAIs received from the core network in association with a rejection reason value indicating an NSSAA failure. The third rejected NSSAI is information independent of the access type. Specifically, when the UE stores the third rejected NSSAI, the UE may not attempt to send a registration request message including the S-NSSAI included in the third rejected NSSAI to both 3GPP access and non-3GPP access. Alternatively, the UE may send a registration request message including the S-NSSAI included in the third rejected NSSAI based on UE policy. Alternatively, the UE may delete the third rejected NSSAI based on UE policy and transition to a state in which it can transmit a registration request message including an S-NSSAI included in the third rejected NSSAI. In other words, if the UE transmits a registration request message including an S-NSSAI included in the third rejected NSSAI based on UE policy, the UE may delete the S-NSSAI from the third rejected NSSAI.

A pending NSSAI (also referred to as a Pending NSSAI) is a collection of one or more S-NSSAIs that are S-NSSAIs for which the network requires network slice specific authentication, for which network slice specific authentication has not been completed, and which cannot be used in the current PLMN. A pending NSSAI may be a 5GS Rejected NSSAI due to NSSAA or a pending NSSAI. A pending NSSAI may be an NSSAI stored by the UE or NW, or an NSSAI sent from the NW to the UE. Note that a pending NSSAI is not limited to a rejected NSSAI, and may be an NSSAI independent of the rejected NSSAI. When a pending NSSAI is an NSSAI sent from the NW to the UE, the pending NSSAI may be information that includes one or more combinations of an S-NSSAI and a rejection reason value. The rejection reason value in this case may be "NSSAA is pending for the S-NSSAI" or may be information indicating that the S-NSSAI associated with the rejection reason value is prohibited or pending use by the UE until the NSSAA for that S-NSSAI is completed.

The pending NSSAI is also valid across the entire registered PLMN. In other words, the UE and/or NW may treat the third rejected NSSAI and the S-NSSAI included in the pending NSSAI as information independent of the access type. In other words, the pending NSSAI may be information valid for both 3GPP access and non-3GPP access. The pending NSSAI may be an NSSAI different from the rejected NSSAI. The pending NSSAI may also be the first rejected NSSAI.

The pending NSSAI is an NSSAI consisting of one or more S-NSSAIs that identify slices for which the UE is pending a procedure. Specifically, while the UE stores the pending NSSAI, it does not initiate a registration request procedure for the S-NSSAI included in the pending NSSAI. In other words, the UE does not use the S-NSSAI included in the pending NSSAI during the registration procedure until the NSSAA for the S-NSSAI included in the pending NSSAI is completed. The pending NSSAI is identification information that includes one or more S-NSSAIs received from the core network in association with a rejection reason value indicating a pending NSSAA. The pending NSSAI is information that is independent of the access type. Specifically, when the UE stores the pending NSSAI, the UE does not attempt to send a registration request message including the S-NSSAI included in the pending NSSAI to both 3GPP access and non-3GPP access.

A tracking area 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. Hereinafter, a tracking area may be a TA (Tracking Area). A tracking area may be identified by a TAI (Tracking Area Identity) consisting of a TAC (Tracking area code) and a PLMN.

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 areas in which UE_A10 can move without performing a tracking area update procedure. A registration area may be identified by a TAI list consisting of one or more TAIs.

The UE ID is information for identifying a UE. Specifically, for example, the UE ID may be a SUCI (Subscription Concealed Identifier), a SUPI (Subscription Permanent Identifier), a GUTI (Globally Unique Temporary Identifier), an IMEI (International Mobile Subscriber Identity), an IMEISV (IMEI Software Version), or a TMSI (Temporary Mobile Subscriber Identity). Alternatively, the UE ID may be other information set within an application or network. Furthermore, the UE ID may be information for identifying a user.

Network Slice-Specific Authentication and Authorization (NSSAA) is a function for realizing network slice-specific authentication and authorization. Network slice-specific authentication and authorization allows UE authentication and authorization to be performed outside the core network, such as by a third party. PLMNs and network devices with NSSAA functionality can perform NSSAA procedures for a certain S-NSSAI based on the UE's registration information. Furthermore, UEs with NSSAA functionality can manage and store rejected NSSAIs pending for NSSAA and/or rejected NSSAIs due to NSSAA failure. In this document, NSSAA may be referred to as the network slice-specific authentication and authorization procedure or the authentication and authorization procedure.

An S-NSSAI requiring NSSAA is an S-NSSAI requiring NSSAA that is managed by the core network and/or core network device. The core network and/or core network device may store an S-NSSAI requiring NSSAA by associating the S-NSSAI with information indicating whether or not an NSSAA is required. The core network and/or core network device may further store an S-NSSAI requiring NSSAA in association with information indicating whether or not the NSSAA has been completed, or information indicating that the NSSAA has been completed and is permitted or successful. The core network and/or core network device may manage an S-NSSAI requiring NSSAA as information unrelated to the access network.

A UE in single registration mode can only have one active MM state. That is, a UE in single registration mode can only be active in either the RM state (5GMM state) in 5GC or the EMM state in EPC. A UE in single registration mode is in 5GC NAS mode when connecting to 5GC, and is in EPC NAS mode when connecting to EPC. A UE in single registration mode can only register to either 5GC or EPC, so when moving between EPC and 5GC, mapping between EPS-GUTI (also called 4G-GUTI) and 5G-GUTI is required.

Also, a UE in dual registration mode may be able to register independently to 5GC and EPC. A UE in dual registration mode can maintain 5G-GUTI and EPS-GUTI (also referred to as 4G-GUTI) independently.

Next, we will explain the identification information that is sent, received, stored, and managed by each device in this embodiment.

First, the first identification information is information indicating the network slice in which the UE wishes to register. The first identification information may also be a Requested NSSAI, which may be an NSSAI provided by the UE to the PLMN when registering with the network. The first identification information may also include one or more S-NSSAIs. The S-NSSAI included in the first identification information may be an S-NSSAI included in a configured NSSAI associated with the current PLMN, or an S-NSSAI included in an allowed NSSAI associated with the current PLMN. In other words, the first identification information may be an S-NSSAI included in a configured NSSAI associated with one or more current PLMNs, an S-NSSAI included in an allowed NSSAI associated with one or more current PLMNs, or a combination of the two. More specifically, the allowed NSSAI associated with the current PLMN may be an allowed NSSAI associated with the current PLMN and the current access type.

Furthermore, the S-NSSAI included in the first identification information may be a rejected NSSAI and/or an S-NSSAI that is not included in the pending NSSAI. Furthermore, the S-NSSAI included in the first identification information may be an S-NSSAI for which the associated back-off timer is not running.

Furthermore, the 11th identification information may be information indicating a network slice. Moreover, the 11th identification information may be an S-NSSAI. Moreover, the 11th identification information may be information indicating an S-NSSAI that has reached the maximum number of UEs or the maximum number of PDU sessions that can be registered in a network slice. Furthermore, the 11th identification information may be included in an Allowed NSSAI transmitted from the network, may be included in a Rejected NSSAI transmitted from the network, may be included in a Pending NSSAI transmitted from the network, or may be transmitted from the network as information different from these.

The eleventh identification information may also be an NSSAI. The eleventh identification information may also be an Allowed NSSAI, a Rejected NSSAI, a Pending NSSAI, or an NSSAI different from these. The eleventh identification information may be configured to include one or more of the twelfth and/or thirteenth identification information.

The 12th identification information may also be a cause value. The 12th identification information may also be indicated as a 5G Mobility Management (5GMM) cause.

Furthermore, the 12th identification information may indicate that the maximum number of UEs per NS has been exceeded, that the maximum number of UEs per NS has been reached, or that an NS-related quota regarding the maximum number of UEs has been exceeded.

Furthermore, the 12th identification information may indicate congestion, may indicate that redirection to EPC is required, may indicate that no network slices are available, may indicate that there are insufficient resources for a specific NS and DNN, or may indicate that there are insufficient resources for a specific slice.

Furthermore, the 12th identification information may be configured to include one or more of the 11th and/or 13th identification information.

The 13th identification information may also be a backoff timer value. Specifically, the 13th identification information may indicate a period during which the UE is prohibited from transmitting an MM message or an SM message using the S-NSSAI indicated by the 11th identification information. The 13th identification information may also indicate a period during which the UE is prohibited from returning to N1 mode when the UE has made a system change from N1 mode to S1 mode. The 13th identification information may also indicate a period during which the UE is prohibited from transmitting an MM message or an SM message using the S-NSSAI indicated by the 11th identification information, but is allowed to return to N1 mode when the UE has made a system change from N1 mode to S1 mode.

Furthermore, the 13th identification information may be configured to include one or more of the 11th and/or 12th identification information.

Furthermore, the 14th identification information may be information that includes at least one of the 11th to 13th identification information.

Furthermore, the 21st identification information is a PDU session ID that identifies the PDU session. Furthermore, the 21st identification information may be a PDU session ID that identifies the PDU session that is requested to be established.

The 22nd identification information is a PDU session type that identifies the type of PDU session. The 22nd identification information may also be the PDU session type requested by the UE for the PDU session. The 22nd identification information may also indicate any of IPv4, IPv6, IPv4v6, Unstructured, or Ethernet (registered trademark).

Furthermore, the 23rd identification information is the SSC mode. Furthermore, the 23rd identification information may be the SSC mode requested by the UE for the PDU session. Furthermore, the 23rd identification information may indicate any of SSC mode 1, SSC mode 2, or SSC mode 3.

Furthermore, the 24th identification information is one or more S-NSSAIs. Furthermore, the 24th identification information may be one or more S-NSSAIs requested by the UE for the PDU session to be established. Furthermore, the 24th identification information may be one or more S-NSSAIs selected from the Allowed NSSAIs for the current access type. Specifically, the 24th identification information may be one or more S-NSSAIs allowed by the network as Allowed S-NSSAIs included in the registration accept message in the registration procedure. Furthermore, not including the 24th identification information may be referred to as no S-NSSAI.

Furthermore, the 25th identification information is a DNN. Furthermore, the 25th identification information may be a DNN that identifies the DN to which the PDU session that the UE requests to establish is connected. Furthermore, not including the 25th identification information may be referred to as "no DNN."

Furthermore, the 26th identification information may be information that includes at least one of the 21st to 25th identification information.

Furthermore, the 31st identification information is a PDU session ID that identifies a PDU session. It may be a PDU session ID that identifies a PDU session that is permitted to be established by the network. The 31st identification information may be the same as the 21st identification information.

The 32nd identification information is a PDU session type that identifies the type of PDU session. The 32nd identification information may be a PDU session type selected by the network. The 32nd identification information may indicate any of IPv4, IPv6, IPv4v6, Unstructured, or Ethernet (registered trademark).

Furthermore, the 33rd identification information is the SSC mode. Furthermore, the 33rd identification information may be the SSC mode selected by the network for the PDU session. Furthermore, the 33rd identification information may indicate any of SSC mode 1, SSC mode 2, or SSC mode 3.

Furthermore, the 34th identification information is one or more S-NSSAIs. The 34th identification information may be the same as the 24th identification information. The 34th identification information may be configured to include one or more of the 36th and/or 37th identification information.

Furthermore, the 35th identification information is a DNN. Furthermore, the 35th identification information may be a DNN that identifies the DN to which the PDU session is connected. The 35th identification information may be the same as the 25th identification information.

Furthermore, the 36th identification information may be a cause value. Furthermore, the 36th identification information may be indicated as a 5G Mobility Management (5GMM) cause and/or a 5G Session Management (5GSM) cause.

The 36th identification information may also indicate that the maximum number of PDU sessions per NS has been exceeded, or that the maximum number of PDU sessions per NS has been reached, or that an NS-related quota regarding the maximum number of PDU sessions has been exceeded.

Furthermore, the 36th identification information may indicate insufficient resources, insufficient resources for a specific NS and DNN, insufficient resources for a specific slice, or that the maximum number of PDU sessions has been reached.

Furthermore, the 36th identification information may be configured to include one or more of the 34th and/or 37th identification information.

Furthermore, the 37th identification information may be a backoff timer value. Specifically, the 37th identification information may indicate a period during which the UE is prohibited from transmitting an MM message or an SM message using the S-NSSAI indicated by the 34th identification information. Furthermore, the 37th identification information may indicate a period during which the UE is prohibited from returning to N1 mode when the UE has made a system change from N1 mode to S1 mode. Furthermore, the 37th identification information may indicate a period during which the UE is prohibited from transmitting an MM message or an SM message using the S-NSSAI indicated by the 11th identification information, but can return to N1 mode when the UE has made a system change from N1 mode to S1 mode.

Furthermore, the 37th identification information may be configured to include one or more of the 34th and/or 36th identification information.

Furthermore, the 38th identification information may be information that includes at least one of the 31st to 37th identification information.

3. First Embodiment
First, procedures used in the first embodiment will be described. The procedures used in the first embodiment include a registration procedure, a PDU session establishment procedure, etc. Each procedure will be described below.

In the first embodiment, as shown in Figure 2, the HSS and UDM, PCF and PCRF, SMF and PGW-C, and UPF and PGW-U are each configured as the same device/function (i.e., the same physical hardware, the same logical hardware, or the same software). However, the content described in this embodiment is also applicable to cases where these are configured as different devices/functions (i.e., different physical hardware, different logical hardware, or different software). For example, data may be sent and received directly between them, or data may be sent and received via the N26 interface between the AMF and MME, or data may be sent and received via the UE.

3.1. Registration Procedure
Next, the registration procedure will be described with reference to FIG. 6. In this chapter, this registration procedure may be simply referred to as this 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 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.

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

The UE may initiate the registration procedure when it performs mobility across TAs. In other words, the UE may initiate the registration procedure when it moves to a TA different from the TA indicated in the TA list it maintains. Furthermore, the UE may initiate the registration procedure when the context of each device needs to be updated due to a PDU session being disconnected or invalidated. Furthermore, the UE may initiate the registration procedure when there is a change in the capability information and/or preferences related to the UE's PDU session establishment. Furthermore, the UE may initiate the registration procedure periodically. Furthermore, the UE may initiate the registration procedure based on the completion of the registration procedure, the completion of the PDU session establishment procedure, or information received from the network during each procedure. In other words, the UE may initiate the registration procedure after performing the procedures in Chapter 3.1 and/or Chapter 3.2. However, the UE is not limited to these and may perform the registration procedure at any time.

The procedure for the UE to transition from a state in which it is not registered with the network (unregistered state) to a registered state (registered state) may be an initial registration procedure or a registration procedure for initial registration. Furthermore, the registration procedure performed when the UE is registered with the network (registered state) may be a registration procedure for mobility and periodic registration update or a mobility and periodic registration procedure.

The registration process details below are applicable to both.

First, the UE initiates the registration procedure by sending a registration request message to the AMF (S600) (S602) (S604). Specifically, the UE sends an RRC message including a registration request message to the base station device (also referred to as a 5G AN or gNB) (S600). Note that the registration request message is a NAS message transmitted and received over the N1 interface. The RRC message may be a control message transmitted and received between the UE and the base station device. Note that the NAS message is processed in the NAS layer, and the RRC message is processed in the RRC layer. Note that the NAS layer is a layer higher than the RRC layer.

Here, the UE can transmit the first identification information by including it in the registration request message and/or the RRC message. Here, the first identification information may be as described in Chapter 2.6. Furthermore, the UE may transmit the registration request message and/or the RRC message by 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 (Information Element). The 5GS registration type IE is information for indicating the type of registration requested, and may indicate initial registration, mobility registration updating, periodic registration updating, or emergency registration.

The UE may include its capability information in the registration request message to notify the network of the features it supports. Here, the UE capability information may be the 5GMM capability IE for 5GS.

The UE may transmit this identification information in a different control message, such as a control message for a layer lower than the RRC layer (e.g., the Medium Access Control (MAC) layer, the Radio Link Control (RLC) layer, the Packet Data Convergence Protocol (PDCP) layer, the Service Data Adaptation Protocol (SDAP) layer, etc.). By transmitting this identification information, the UE may indicate that it supports each function, indicate a request from the UE, or indicate both.

The UE may select and decide whether to transmit the first 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.

The UE may store the allowed NSSAI, configured NSSAI, rejected NSSAI, and mapped S-NSSAI.

The UE may include information other than the first identification information in the registration request message and/or the RRC message, such as the UE ID and/or PLMN ID and/or AMF identification information, and may transmit the message. Here, the AMF identification information may be information that identifies an AMF or a set of AMFs, such as the 5G-S-TMSI (5G S-Temporary Mobile Subscription Identifier) or the GUAMI (Globally Unique AMF Identifier).

When the base station device receives an RRC message including a registration request message, it selects an AMF to which to forward the registration request message (S602). The base station device may select an AMF based on identification information included in the registration request message and/or the RRC message. Specifically, when the base station device receives first identification information, it may select an AMF to which to send the registration request message based on the first identification information. Specifically, the base station device may select an AMF included in the network slice identified by the first identification information, or an AMF that has connectivity to the network slice identified by the first identification information.

Note that the AMF selection method is not limited to this, and the base station device may select AMF based on other conditions.

The base station device extracts the registration request message from the received RRC message and forwards the registration request message to the selected AMF (S604). Note that if the first identification information is not included in the registration request message but is included in the RRC message, the identification information included in the RRC message may be forwarded to the selected AMF together with the registration request message (S604).

When the AMF receives a registration request message, it can perform a first condition determination. The first condition determination is for determining whether the network will accept the UE's request. If the AMF determines that the first condition determination is true, it can perform procedures S610 to S612. Also, if the AMF determines that the first condition determination is false, it can perform the procedure S610.

The first condition determination may also be performed by a network function (also referred to as NF) other than the AMF. The NF may be, for example, an NSACF. When an NF other than the AMF performs the first condition determination, the AMF may provide the NF with information necessary to perform the first condition determination, specifically at least a portion of the information received from the UE (S606). Then, when the NF determines whether the first condition determination is true or false based on the information received from the AMF, it may convey information including the result of the first condition determination (i.e., true or false) to the AMF. The AMF may determine the identification information and/or control message to be sent to the UE based on the result of the first condition determination received from the NF.

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.

The first condition determination may be performed based on the reception of a registration request message, and/or the 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.

For example, if the network permits the UE's request, the first condition determination may be determined to be true, and if the network does not permit the UE's request, the first condition determination may be determined to 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 determined to be true, and if the function requested by the UE is not supported, the first condition determination may be determined to be false. Furthermore, if the identification information to be transmitted and received is permitted, the first condition determination may be determined to be true, and if the identification information to be transmitted and received is not permitted, the first condition determination may be determined to be false. Furthermore, if the registration request is rejected due to reasons such as exceeding the maximum number of UEs per NS, reaching the maximum number of UEs per NS, exceeding an NS-related quota regarding the maximum number of UEs, congestion, redirection to EPC required, no network slices available, insufficient resources for a specific NS and DNN, or insufficient resources for a specific NS (hereinafter referred to as rejection reason 1), the first condition determination may be determined to be false. Furthermore, if the registration request is not rejected due to rejection reason 1, the first condition determination may be determined to be true.

The AMF may transmit one or more of the identification information items 11 to 14 in a control message. Here, the identification information items 11 to 14 may be as described in Chapter 2.6. By transmitting this identification information and/or control message, the AMF may indicate that the network supports each function, that the UE's request has been accepted, that the UE's request has not been permitted, or a combination of these. Furthermore, when multiple pieces of identification information are transmitted and received, two or more of these identification information items 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 as different identification information.

When the AMF receives a registration request message including the first identification information from the UE, it may transmit at least one of the 11th to 14th identification information in a control message.

Furthermore, even if the AMF receives a registration request message from the UE that does not include the first identification information, the AMF may include at least one of the 11th to 14th identification information in the control message and send it.

The AMF may further include the configured NSSAI, and/or the allowed NSSAI, and/or the rejected NSSAI, and/or the pending NSSAI in the control message and transmit it. Note that the identification information 11 to 14 may be transmitted by being included in the allowed NSSAI, and/or the rejected NSSAI, and/or the pending NSSAI, or may be transmitted as information separate from these.

When the AMF sends a control message, if there is no S-NSSAI (allowed NSSAI) permitted for the UE, but if an NSSAA procedure is planned to be performed after the completion of this procedure or in parallel with this procedure, or if an NSSAA procedure is currently being performed between the UE and the network, or if a pending NSSAI is sent in the control message, the AMF may send an empty value in the allowed NSSAI.

In addition, the AMF may determine which of the 11th to 14th identification information 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 AMF, etc.

Furthermore, 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.

Furthermore, when rejecting a registration request due to rejection reason 1, the network (e.g., AMF and/or NSACF) may set the 12th identification information to: exceeded maximum number of UEs per NS, and/or reached maximum number of UEs per NS, and/or exceeded NS-related quota on maximum number of UEs, and/or congestion, and/or redirection to EPC required, and/or no network slices available, and/or insufficient resources for specific slice and DNN, and/or insufficient resources for specific slice.

In this case, the network (e.g., AMF and/or NSACF) may take into account the UE's S1 mode capability when deciding to reject using the 12th identity. Here, S1 mode may refer to a mode of the UE that allows access to a 4G core network via a 4G access network, and S1 mode capability may refer to the UE having S1 mode capability, i.e., the UE having the capability to access a 4G core network via a 4G access network, or may refer to the UE having the capability to communicate using 4G.

Furthermore, when the AMF and/or NSACF permit the UE request because rejection reason 1 does not apply, or when the AMF and/or NSACF permits the use of the S-NSSAI included in the first identification information received from the UE, the AMF and/or NSACF may designate the S-NSSAI as an allowed S-NSSAI and include the allowed S-NSSAI in the 11th identification information.Furthermore, when the AMF and/or NSACF permit the UE request because rejection reason 1 does not apply, or when the AMF and/or NSACF permits the use of the S-NSSAI included in the first identification information received from the UE, the AMF and/or NSACF may designate the S-NSSAI as an allowed S-NSSAI and include the Allowed NSSAI including the allowed S-NSSAI in the 11th identification information.

Furthermore, if the AMF and/or NSACF does not allow (reject) a UE request because it falls under rejection reason 1, or if it does not allow (reject) the use of an S-NSSAI included in the first identification information received from the UE, it may designate that S-NSSAI as a rejected S-NSSAI and include the rejected S-NSSAI in the 11th identification information.Furthermore, if the AMF and/or NSACF does not allow (reject) a UE request because it falls under rejection reason 1, or if it does not allow (reject) the use of an S-NSSAI included in the first identification information received from the UE, it may designate that S-NSSAI as a rejected S-NSSAI and include an Allowed NSSAI or Rejected NSSAI including the rejected S-NSSAI in the 11th identification information.

Furthermore, the AMF and/or NSACF do not need to include the 12th identification information when approving the UE request because rejection reason 1 does not apply, or when approving the use of the S-NSSAI included in the first identification information received from the UE.

In addition, the AMF and/or NSACF may include a 12th identification if they do not authorize (reject) the UE's request because it corresponds to rejection reason 1, or if they do not authorize (reject) the use of the S-NSSAI included in the first identification received from the UE.

In addition, if the AMF and/or NSACF does not authorize (rejects) the UE's request because it falls under rejection reason 1, or if it does not authorize (rejects) the use of the S-NSSAI included in the first identification information received from the UE, it may include a back-off timer value in the 13th identification information.

The UE receives the control message (registration acceptance message or registration rejection message) and/or the transmitted identification information items 11 to 14 via the base station device (S610). If the control message is a registration acceptance message, the UE can recognize by receiving the registration acceptance message that the UE's request in the registration request message has been accepted and the contents of the various identification information included in the registration acceptance message. If the control message is a registration rejection message, the UE can recognize by receiving the registration rejection message that the UE's request in the registration request message has been rejected and the contents of the various identification information included in the registration rejection message.

If the UE receives the 12th identification information via non-3GPP access, this may be considered an abnormal case. If the UE receives the 12th identification information via a cell belonging to an SNPN, this may also be considered an abnormal case.

Furthermore, when the UE receives the 12th identification information, it may set the 5GS update status (also referred to as 5U status) of the UE to 5U3 ROAMING NOT ALLOWED. Here, 5U status specifies the status of the UE in the 5GMM layer, and 5U3 ROAMING NOT ALLOWED may be a status indicating that the previous registration, previous service request, or previous registration procedure for mobility and periodic registration update was performed correctly (successfully), but the response from the AMF was negative.

Furthermore, when the UE receives the 12th identification information, it may delete all 5G-GUTIs, previously registered TAIs, TAI lists, etc. Furthermore, the UE may reset a registration attempt counter. Here, the registration attempt counter is used to limit the number of registration attempts. In other words, the registration attempt counter may be used to limit the number of times the registration procedure is performed. The registration attempt counter is incremented by 1 each time the registration procedure fails unless it is set to 5, but may be reset in certain cases. The registration attempt counter is also reset when the UE is powered on, when a USIM is inserted, when the registration procedure is successfully completed, etc.

Furthermore, when the UE receives the 12th identification information, if E-UTRA capability is disabled, it may enable E-UTRA capability, or it may disable N1 mode capability for 3GPP access, or it may transition to a 5GMM-DERIGISTERED.NO-CELL-AVAILABLE state. Here, E-UTRA capability may mean that the UE has the capability to access a 4G core network via a 4G access network, or it may mean that the UE has the capability to access a 4G access network, or it may mean the capability to communicate using 4G. Furthermore, N1 mode means a UE mode in which the UE can access a 5G core network via a 5G access network, and N1 mode capability may mean that the UE has N1 mode capability, i.e., that the UE has the capability to access a 5G core network via a 5G access network. Furthermore, 5GMM-DERIGISTERED.NO-CELL-AVAILABLE may mean that a 5G cell cannot be selected.

Also, if the UE receives the 12th identity via 3GPP access, the UE is operating in single registration mode, and the EPS attach procedure is rejected using the 12th identity, the UE may operate using the EMM state, EPS update status, 4G-GUTI, attach attempt counter, etc. In other words, the UE may operate using 4G parameters instead of 5G parameters. Here, the attach attempt counter is used to limit the number of attach attempts. In other words, the attach attempt counter may be used to limit the number of times the attach procedure is performed. The attach attempt counter is incremented by one each time the registration procedure fails unless it is set to 5, but may be reset in certain cases. The attach attempt counter is also reset when the UE is powered on, when a USIM is inserted, when the attach procedure is successfully completed, etc.

Also, if the UE receives the 12th identity via 3GPP access, the UE is operating in single registration mode, and the tracking area update procedure in EPS is rejected using the 12th identity, the UE may operate using the EMM state, EPS update status, 4G-GUTI, tracking area update attempt counter, etc. In other words, the UE may operate using 4G parameters instead of 5G parameters. Here, the tracking area update attempt counter is used to limit the number of tracking area update attempts. In other words, the tracking area update attempt counter may be used to limit the number of times the tracking area update procedure is performed. The tracking area update attempt counter is incremented by one each time the registration procedure fails unless it is set to 5, but may be reset in certain cases. The tracking area update attempt counter is also reset when the UE is powered on, when a USIM is inserted, when the tracking area update procedure is successfully completed, etc.

Also, if the UE receives the 12th identification information and disables the N1 mode capability, and the UE's lower layers do not provide information that the current E-UTRA cell is connected to the EPC, it may search for a suitable E-UTRA cell to connect to the EPC.

Also, if the UE receives the 12th identification information and disables the N1 mode capability, and if the UE's lower layers provide information that the current E-UTRA cell is connected to the EPC, it may perform core network selection to select the EPC.

Also, if the UE receives the 12th identification information and disables N1 mode capability, and the UE's lower layers cannot find an E-UTRA cell connecting to the EPC, the UE may indicate to the lower layers that it will continue camping on the E-UTRA cell connecting to the 5GC, may start a timer, or may transition to the 5GMM-REGISTERED.LIMITED-SERVICE state. Here, 5GMM-REGISTERED.LIMITED-SERVICE may be a state in which the UE knows that the cell it has selected cannot provide normal service. Then, when the timer expires, the UE may enable N1 mode capability for 3GPP access.

Furthermore, if the UE receives the 11th identification information including the Allowed S-NSSAI, the UE may recognize that it is permitted to use the S-NSSAI, and/or that it is permitted to register with the network, and/or that the UE's request is permitted.

Furthermore, if the UE receives the 11th identification information including the Allowed S-NSSAI but does not receive the 12th and/or 13th identification information, the UE may recognize that it is permitted to use the S-NSSAI, and/or that it is permitted to register with the network, and/or that the UE's request is permitted.

Furthermore, even if the UE receives the 11th identification information including the Allowed S-NSSAI, if the UE also receives the 12th identification information and/or the 13th identification information, the UE may recognize that use of the S-NSSAI is not permitted (rejected), and/or that registration with the network is not permitted (rejected), and/or that the UE's request is not permitted (rejected).

Furthermore, if the UE receives the 11th identification information including the Rejected S-NSSAI, the UE may recognize that the use of the S-NSSAI is not permitted (rejected), and/or that registration with the network is not permitted (rejected), and/or that the UE's request is not permitted (rejected).

Furthermore, if the UE receives the 11th identification information including the Rejected S-NSSAI and also receives the 12th identification information and/or the 13th identification information, the UE may recognize that use of the S-NSSAI is not permitted (rejected), and/or that registration with the network is not permitted (rejected), and/or that the UE's request is not permitted (rejected).

Furthermore, when the UE receives the 13th identification information, it may set the back-off timer value indicated by the 13th identification information to a timer that the UE has and that corresponds to the S-NSSAI indicated by the 11th identification information, and start the timer. The UE may not be able to send an MM message and/or SM message for the S-NSSAI indicated by the 11th identification information while the timer corresponding to the S-NSSAI indicated by the 11th identification information is running. The UE may be able to send an MM message and/or SM message for the S-NSSAI when the timer corresponding to the S-NSSAI indicated by the 11th identification information expires. Note that the UE may send an MM message and/or SM message for an S-NSSAI other than the S-NSSAI even if the timer corresponding to the S-NSSAI indicated by the 11th identification information is running.

Furthermore, based on receiving the 11th identification information, and/or the 12th identification information, and/or the 13th identification information, and/or the 14th identification information, the UE may decide to communicate via E-UTRAN and/or the EPC and/or the EPS, or to perform a system change from N1 mode to S1 mode, or to change from communication using 5G to communication using 4G. In this case, the UE may perform an attach procedure and/or a tracking area update procedure in the EPS.

Furthermore, even if the UE performs an attach procedure and/or a tracking area update procedure in EPS, the UE may continue or stop the operation of the timer corresponding to the S-NSSAI indicated by the 11th identification information. If the UE continues the operation of the timer corresponding to the S-NSSAI indicated by the 11th identification information, the UE may not be able to send an MM message and/or an SM message for that S-NSSAI in 5GS until the timer expires. Then, when the timer expires, the UE may be able to send an MM message and/or an SM message for that S-NSSAI in 5GS. Furthermore, if the UE stops the operation of the timer corresponding to the S-NSSAI indicated by the 11th identification information, the UE may be able to send an MM message and/or an SM message for that S-NSSAI in 5GS.

The UE may also start a timer to release the NAS signaling connection if it receives a registration rejection message containing the 12th identification information.

If the control message is a registration accept message, the UE can further transmit a registration complete message to the AMF via the base station device as a response message to the registration accept message (S612). Here, the registration complete message is an NAS message transmitted and received over the N1 interface, but may be transmitted and received between the UE and the base station device as part of an RRC message.

The AMF receives a registration completion message via the base station device (S612). Each device then completes this procedure based on the sending and receiving of a registration acceptance message and/or a registration completion message.

In addition, each device may complete the registration procedure based on sending and receiving a registration rejection message.

In addition, each device may transition to or maintain a state in which the UE is registered with 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 with the network on the access from which the registration rejection message was received for the current PLMN (RM_DEREGISTERED state or 5GMM-DEREGISTERED state) based on the transmission and reception of a registration rejection message. Furthermore, the transition of each device to each state may be based on the transmission and reception of a registration complete message or the completion of the registration procedure.

Furthermore, upon completion of the registration procedure, each device may perform processing based on the information transmitted and received during the registration procedure. For example, if information indicating that some of the UE's requests were rejected is transmitted and received, the device may recognize the reason why the UE's requests were rejected. Furthermore, based on the reason why the UE's requests were rejected, each device may perform this procedure again, or may perform the registration procedure with core network_A or another cell.

Furthermore, the UE may store the identification information received with the registration accept message and/or registration reject message and may recognize the network's decision based on the completion of the registration procedure.

[3.2. PDU Session Establishment Procedure]
Next, the PDU session establishment procedure will be explained using Fig. 7. In this chapter, this PDU session establishment procedure may be simply referred to as this procedure.

The UE may also perform this procedure after performing the procedures in Chapter 3.1 and/or Chapter 3.2 one or more times. The UE may also perform this procedure while it is registered with the network.

The UE may also determine whether to perform this procedure based on messages and/or information obtained in the procedures of Chapter 3.1 and/or Chapter 3.2. For example, in the procedures of Chapter 3.1, if the UE receives a registration accept message, the UE may perform this procedure. Also, in the procedures of Chapter 3.1, if the UE receives an eleventh identification including an allowed S-NSSAI, the UE may perform this procedure. Also, in the procedures of Chapter 3.1, if the UE receives a thirteenth identification, the UE may not initiate this procedure for the S-NSSAI indicated by the eleventh identification received simultaneously with the thirteenth identification until the timer corresponding to the S-NSSAI indicated by the eleventh identification received simultaneously with the thirteenth identification expires. Also, in the procedures of Chapter 3.1, if the UE receives a thirteenth identification, the UE may initiate this procedure for an S-NSSAI other than the S-NSSAI, regardless of whether the timer corresponding to the S-NSSAI indicated by the eleventh identification received simultaneously with the thirteenth identification expires.

First, the UE initiates the PDU session establishment procedure by sending a NAS message including an N1 SM container containing a PDU session establishment request message to the AMF via the access network (S800). The NAS message is, for example, a message sent via the N1 interface and may be an uplink NAS transport (UL NAS TRANSPORT) message. By sending the PDU session establishment request message, the UE may also start a timer associated with retransmission of the PDU session establishment request message.

Here, the access network may be a 3GPP access or a non-3GPP access and may include a base station device. That is, the UE sends an NAS message to the AMF via the base station device.

The UE can also notify the network of its request by including at least one of the identification information items 21 to 26 in the PDU session establishment request message, and/or the N1 SM container, and/or the NAS message. Here, the identification information items 21 to 26 may be as described in Chapter 2.6.

The UE may determine which of the identification information items 21 to 26 to transmit 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.

For example, if the UE receives the 11th identification information including the allowed S-NSSAI in the procedure of Chapter 3.1, it may transmit the 24th identification information including the S-NSSAI indicated by the 11th identification information.

Here, no S-NSSAI may mean that the UE does not include the 24th identification information in the PDU session establishment request message, and/or the N1 SM container, and/or the NAS message.

Also, no DNN may mean that the UE does not include the 25th identification information in the PDU session establishment request message, and/or the N1 SM container, and/or the NAS message.

The UE may also transmit this identification information in a different control message, such as a control message for a layer lower than the NAS layer (e.g., RRC layer, MAC layer, RLC layer, PDCP layer, SDAP layer, etc.) or a control message for a layer higher than the NAS layer (e.g., transport layer, session layer, presentation layer, application layer, etc.).

Next, when the AMF receives the NAS message, it can recognize what the UE is requesting and/or the content of the information contained in the NAS message (message, container, information, etc.).

Here, the AMF may or may not make a third condition determination. Furthermore, the third condition determination may be for determining whether the network will accept the UE's request. If the AMF determines that the third condition determination is true, it may initiate the procedure from S802 onwards in Figure 7, and if it determines that the third condition determination is false, it may send a control message to the UE.

The third condition determination may be performed by an NF other than the AMF. The NF may be, for example, an NSACF. When an NF other than the AMF performs the third condition determination, the AMF may provide the NF with the information necessary to perform the third condition determination, specifically, at least a portion of the information received from the UE. Then, when the NF determines whether the third condition determination is true or false based on the information received from the AMF, it may convey information including the result of the third condition determination (i.e., true or false) to the AMF. The AMF may determine the identification information and/or control message to be sent to the UE based on the result of the third condition determination received from the NF.

The third condition determination may be performed based on information received from the UE (message, container, information), and/or information received from the AMF (message, container, information), and/or subscription information, and/or network capability information, and/or UE policy, and/or operator policy, and/or network status, and/or user registration information, and/or information held by the AMF, and/or information held by the NSACF, etc.

For example, if the network permits the UE's request, the third condition determination may be determined to be true, and if the network does not permit the UE's request, the third condition determination may be determined to be false. Furthermore, if the network to which the UE is connected and/or a device within the network supports the function requested by the UE, the third condition determination may be determined to be true, and if the function requested by the UE is not supported, the third condition determination may be determined to be false. Furthermore, if the transmitted and received identification information is permitted, the third condition determination may be determined to be true, and if the transmitted and received identification information is not permitted, the third condition determination may be determined to be false. Furthermore, if the request to establish a PDU session is rejected due to reasons such as exceeding the maximum number of PDU sessions per NS, reaching the maximum number of PDU sessions per NS, exceeding an NS-related quota regarding the maximum number of PDU sessions, congestion, the need for redirection to EPC (Redirection to EPC required), no network slices available, insufficient resources for a specific NS and DNN (Insufficient resources for a specific slice), or insufficient resources for a specific NS (Insufficient resources for a specific slice) (hereinafter referred to as rejection reason 2), the third condition determination may be determined to be false. Furthermore, if the request to establish a PDU session is not rejected due to rejection reason 2, the third condition determination may be determined to be true.

Note that the conditions used to determine the truth or falsity of the third condition determination do not have to be limited to the conditions mentioned above.

Furthermore, when rejecting a PDU session establishment request due to rejection reason 2, the network (e.g., AMF and/or NSACF) may set the 36th identification information to indicate that the maximum number of PDU sessions per NS has been exceeded, and/or that the maximum number of PDU sessions per NS has been reached, and/or that an NS-related quota on the maximum number of PDU sessions has been exceeded, and/or that there is congestion, and/or that redirection to EPC is required (Redirection to EPC required), and/or that no NS is available (No network slices available), and/or that there are insufficient resources for a specific NS and DNN (Insufficient resources for a specific slice).The network (e.g., AMF and/or NSACF) may then transmit a control message including the 31st, 34th to 38th identification information to the UE.

In this case, the network (e.g., AMF and/or NSACF) may take into account the UE's S1 mode capability when deciding to reject using the 36th identity.

In addition, if the network (e.g., AMF and/or NSACF) does not receive the 24th identification information, it may not include the 34th identification information in the control message, or it may include the 34th identification information indicating no S-NSSAI and send it.

Furthermore, if the network (e.g., AMF and/or NSACF) does not receive the 25th identification information, it may not include the 35th identification information in the control message, or may include the 35th identification information indicating no DNN and send it.

When the UE receives a control message from the AMF containing the 36th identification indicating a 5GMM cause, it may notify the 5GSM sublayer of the UE that it was unable to forward the 5GSM message due to the information indicated by the 36th identification. In this case, the UE may treat the maximum number of PDU sessions of the PLMN executing this procedure as the maximum number of PDU sessions per NS. The UE may also abort this procedure or stop the timer associated with retransmission of the PDU session establishment request message, which was started by transmitting the PDU session establishment request message.

Next, if the third condition determination is not performed, or if the third condition determination is performed and determined to be true, the AMF selects an SMF as the transfer destination for at least part of the information (message, container, information) contained in the NAS message received from the UE (S802). The AMF may select the transfer destination SMF based on the information (message, container, information) contained in the NAS message, and/or subscriber information, and/or network capability information, and/or UE policy, and/or operator policy, and/or network status, and/or user registration information, and/or context held by the AMF, etc.

Next, the AMF sends at least a portion of the information (message, container, information) contained in the NAS message received from the UE to the selected SMF, for example via the N11 interface (S804).

Next, when the SMF receives information (messages, containers, information) sent from the AMF, it can recognize what the UE is requesting and/or the content of the information (messages, containers, information) received from the AMF.

Here, the SMF may perform a second condition determination. The second condition determination may be for determining whether the network will accept the UE's request. If the SMF determines that the second condition determination is true, it may initiate the procedure in (A) of FIG. 7. If the SMF determines that the second condition determination is false, it may initiate the procedure in (B) of FIG. 7.

The second condition determination may be performed by an NF other than the SMF. The NF may be, for example, an NSACF. When an NF other than the SMF performs the second condition determination, the SMF may provide the NF with information necessary to perform the second condition determination, specifically, at least a portion of the information received from the UE (S806). Then, when the NF determines whether the second condition determination is true or false based on the information received from the SMF, it may convey information including the result of the second condition determination (i.e., whether it is true or false) to the SMF. The SMF may determine the identification information and/or control message to be transmitted to the UE based on the result of the second condition determination received from the NF.

The second condition determination may be performed based on information received from the UE (message, container, information), and/or information received from the AMF (message, container, information), and/or subscription information, and/or network capability information, and/or UE policy, and/or operator policy, and/or network status, and/or user registration information, and/or information held by the SMF, and/or information held by the NSACF, etc.

For example, if the network permits the UE's request, the second condition determination may be determined to be true, and if the network does not permit the UE's request, the second condition determination may be determined to be false. Furthermore, if the network to which the UE is connected and/or a device within the network supports the function requested by the UE, the second condition determination may be determined to be true, and if the function requested by the UE is not supported, the second condition determination may be determined to be false. Furthermore, if the transmitted and received identification information is permitted, the second condition determination may be determined to be true, and if the transmitted and received identification information is not permitted, the second condition determination may be determined to be false. Furthermore, if the PDU session establishment request is rejected due to rejection reason 2, the second condition determination may be determined to be false. Furthermore, if the PDU session establishment request is not rejected due to rejection reason 2, the second condition determination may be determined to be true.

Also, when rejecting a PDU session establishment request due to rejection reason 2, the network (e.g., SMF and/or NSACF) may set the following to identification information 36: the maximum number of PDU sessions per NS has been exceeded, and/or the maximum number of PDU sessions per NS has been reached, and/or the NS-related quota on the maximum number of PDU sessions has been exceeded, and/or congestion, and/or redirection to EPC required, and/or no network slices available, and/or insufficient resources for a specific NS and DNN, and/or insufficient resources for a specific slice.

In this case, the network (e.g., SMF and/or NSACF) may take into account the UE's S1 mode capability when deciding to reject using the 36th identity.

Note that the conditions used to determine the truth or falsity of the second condition determination do not have to be limited to the conditions described above.

Next, we will explain each step of the procedure in Figure 7 (A).

The SMF may then select a UPF for the PDU session to be established and send an N4 session establishment request message to the selected UPF, for example, via the N4 interface (S808). The N4 session establishment request message may include at least a portion of the PCC rules received from the PCF.

Here, the SMF may select one or more UPFs based on information received from the AMF (messages, containers, information), and/or information such as PCC rules received from the PCF, and/or subscriber information, and/or network capability information, and/or UE policies, and/or operator policies, and/or network status, and/or user registration information, and/or context held by the SMF. If multiple UPFs are selected, the SMF may send an N4 session establishment request message to each UPF. Here, it is assumed that UPF_230 is selected.

Next, when the UPF receives the N4 session establishment request message (S808), it can recognize the contents of the information received from the SMF. Furthermore, based on the reception of the N4 session establishment request message, the UPF may send an N4 session establishment response message to the SMF, for example, via the N4 interface (S810).

Next, when the SMF receives an N4 session establishment response message as a response message to the N4 session establishment request message, it can recognize the contents of the information received from the UPF.

Next, based on the receipt of the PDU session establishment request message, and/or the selection of the UPF, and/or the receipt of the N4 session establishment response message, the SMF then sends an N1 SM container, N2 SM information, and/or PDU session ID to the AMF, for example via the N11 interface (S812). Here, the N1 SM container may include a PDU session establishment accept message.

Next, the AMF that has received the N1 SM container, and/or N2 SM information, and/or PDU session ID, transmits a NAS message to the UE via a base station device included in the access network (S814) (S816). Here, the NAS message is transmitted, for example, via the N1 interface. The NAS message may also be a downlink NAS transport (DL NAS TRANSPORT) message.

Specifically, the AMF transmits an N2 PDU session request message to a base station device included in the access network (S814). The base station device that receives the N2 PDU session request message transmits an NAS message to the UE (S816). Here, the N2 PDU session request message may include an NAS message and/or N2 SM information. The NAS message may also include a PDU session ID and/or an N1 SM container.

The PDU session establishment acceptance message may also be a response message to a PDU session establishment request. The PDU session establishment acceptance message may also indicate that the establishment of the PDU session has been accepted.

Here, the SMF and/or AMF may indicate that at least part of the UE's request in the PDU session establishment request message has been accepted by sending a PDU session establishment accept message, and/or an N1 SM container, and/or a PDU session ID, and/or an NAS message, and/or N2 SM information, and/or an N2 PDU session request message.

Here, the SMF and/or AMF and/or NSACF may include at least one of the identification information items 31 to 35 and 38 in the PDU session establishment accept message, and/or the N1 SM container, and/or the NAS message, and/or the N2 SM information, and/or the N2 PDU session request message and transmit it. Here, the identification information items 31 to 35 and 38 may be as described in Chapter 2.6.

Furthermore, the SMF and/or NSACF do not need to include the 36th identification information when approving the UE request because rejection reason 2 does not apply, or when approving the establishment of a PDU session via the S-NSSAI included in the 24th identification information received from the UE.

Furthermore, when the SMF and/or NSACF approves the UE's request because rejection reason 2 does not apply, or when they approve the establishment of a PDU session via the S-NSSAI included in the 24th identification information received from the UE, they do not need to include a back-off timer value in the 37th identification information.

Note that the 34th identification information may be the same as the 24th identification information.

Note that if the network (e.g., SMF and/or NSACF) does not receive the 24th identification information, it may not include the 34th identification information in the control message, or may include the 34th identification information indicating no S-NSSAI in the control message.

Furthermore, if the network (e.g., SMF and/or NSACF) does not receive the 25th identification information, it may not include the 35th identification information in the control message, or it may include the 35th identification information indicating no DNN and send it.

Note that by transmitting this identification information and/or PDU session establishment acceptance message, the SMF and/or AMF and/or NSACF may indicate that the network supports each function, that the UE request has been accepted, that the request from the UE has not been permitted, or a combination of these. Furthermore, when multiple pieces of identification information are transmitted and received, two or more of these 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 as different identification information.

The SMF and/or AMF and/or NSACF may also include the configured NSSAI, and/or allowed NSSAI, and/or rejected NSSAI, and/or pending NSSAI in the PDU session establishment acceptance message and transmit it. Note that the identification information 31 to 35, and 38 may be transmitted in these NSSAIs, or may be transmitted as information separate from these NSSAIs.

The SMF and/or AMF and/or NSACF can notify the UE of the contents of these identification information by transmitting at least one of these identification information.

In addition, the SMF and/or AMF and/or NSACF may determine which identification information to include in the PDU session establishment accept message, and/or N1 SM container, and/or NAS message, and/or N2 SM information, and/or N2 PDU session request message based on the received identification information, and/or subscriber information, and/or network capability information, and/or UE policy, and/or operator policy, and/or network status, and/or user registration information, and/or information held by the SMF, and/or information held by the AMF, and/or information held by the NSACF, etc.

Next, when the UE receives the NAS message (S816), for example via the N1 interface, it can recognize that the UE's request via the PDU session establishment request message has been accepted and/or the contents of the information (message, container, information) contained in the NAS message.

Next, we will explain each step of the procedure in Figure 7 (B).

First, upon receiving the PDU session establishment request message, the SMF sends an N1 SM container and/or a PDU session ID to the AMF, for example via the N11 interface (S818). Here, the N1 SM container may include a PDU session establishment rejection message.

Next, the AMF that has received the N1 SM container and/or PDU session ID transmits a NAS message to the UE via a base station device included in the access network (S820) (S822). Here, the NAS message is transmitted, for example, via the N1 interface. The NAS message may be a downlink NAS transport (DL NAS TRANSPORT) message. The NAS message may include the PDU session ID and/or the N1 SM container.

The PDU session establishment rejection message may also be a response message to a PDU session establishment request. The PDU session establishment rejection message may also indicate that the establishment of a PDU session has been rejected.

Here, the SMF and/or AMF and/or NSACF may indicate that the UE's request in the PDU session establishment request message has been rejected by sending a PDU session establishment rejection message, and/or an N1 SM container, and/or a PDU session ID, and/or an NAS message.

Here, the SMF and/or AMF and/or NSACF may include at least one of the identification information items 31 to 38 in the PDU session establishment rejection message and/or the N1 SM container and/or the NAS message and send it. Here, the identification information items 31 to 38 may be as described in Chapter 2.6.

The SMF and/or AMF and/or NSACF may, by transmitting this identification information and/or PDU session establishment rejection message, indicate that the network does not support each function, that the UE request has been rejected, that the request from the UE has not been authorized, or a combination of these. Furthermore, when multiple pieces of identification information are transmitted and received, two or more of these pieces of identification information may be configured as one or more pieces of identification information. 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 as different identification information.

Furthermore, when the SMF and/or NSACF receives a PDU session establishment request message and rejects the PDU session establishment request due to rejection reason 2, the network (e.g., SMF and/or NSACF) may set the following to identification information 36: the maximum number of PDU sessions per NS has been exceeded, and/or the maximum number of PDU sessions per NS has been reached, and/or the NS-related quota for the maximum number of PDU sessions has been exceeded, and/or congestion has occurred, and/or redirection to EPC is required (Redirection to EPC required), and/or no network slices are available, and/or insufficient resources for a specific NS and DNN (Insufficient resources for a specific slice).

In this case, the network (e.g., SMF and/or NSACF) may take into account the UE's S1 mode capability when deciding to reject using the 36th identity.

In addition, the SMF and/or NSACF may include the 36th identification information if they do not authorize (reject) the UE request due to rejection reason 2, or if they do not authorize (reject) the establishment of a PDU session via the S-NSSAI included in the 24th identification information received from the UE.

In addition, if the SMF and/or NSACF does not authorize (rejects) a UE request due to rejection reason 2, or if it does not authorize (rejects) the establishment of a PDU session via the S-NSSAI included in the 24th identification information received from the UE, it may include a back-off timer value in the 37th identification information.

Note that the 34th identification information may be the same as the 24th identification information.

Note that if the network (e.g., SMF and/or NSACF) does not receive the 24th identification information, it may not include the 34th identification information in the control message, or may include the 34th identification information indicating no S-NSSAI in the control message.

Furthermore, if the network (e.g., SMF and/or NSACF) does not receive the 25th identification information, it may not include the 35th identification information in the control message, or it may include the 35th identification information indicating no DNN and send it.

The SMF and/or NSACF may also include the configured NSSAI, and/or allowed NSSAI, and/or rejected NSSAI, and/or pending NSSAI in the PDU session establishment acceptance message and transmit it. Note that the identification information 31 to 38 may be transmitted in these NSSAIs, or may be transmitted as information separate from these NSSAIs.

The SMF and/or AMF and/or NSACF can notify the UE of the contents of these identification information by transmitting at least one of these identification information.

In addition, the SMF and/or AMF and/or NSACF may determine which identification information to include in the PDU session establishment rejection message, and/or N1 SM container, and/or NAS message, and/or N2 SM information, and/or N2 PDU session request message based on the received identification information, and/or subscriber information, and/or network capability information, and/or UE policy, and/or operator policy, and/or network status, and/or user registration information, and/or information held by the SMF, and/or information held by the AMF, and/or information held by the NSACF, etc.

Next, when the UE receives the NAS message (S822), for example via the N1 interface, it can recognize that the UE's request via the PDU session establishment request message has been rejected and/or the contents of the information (message, container, information) contained in the NAS message.

In addition, if the UE receives the 36th identification information via non-3GPP access, it may consider this to be an abnormal case.In addition, if the UE receives the 36th identification information via a cell belonging to an SNPN, it may also consider this to be an abnormal case.

Furthermore, when the UE receives the 36th identification information, it may set the 5GS update status (also referred to as 5U status) of the UE to 5U3 ROAMING NOT ALLOWED.

Furthermore, when the UE receives the 36th identification information, it may delete all 5G-GUTIs, previously registered TAIs, TAI lists, etc. Furthermore, the UE may reset the registration attempt counter.

Furthermore, when the UE receives the 36th identification information, if the E-UTRA capability is disabled, it may enable the E-UTRA capability, disable the N1 mode capability for 3GPP access, or transition to the 5GMM-DERIGISTERED.NO-CELL-AVAILABLE state.

Also, if the UE receives the 36th identification via 3GPP access, the UE is operating in single registration mode, and the attach procedure in EPS is rejected using the 36th identification, the UE may operate using the EMM state, EPS update status, 4G-GUTI, attach attempt counter, etc. In other words, the UE may operate using 4G parameters instead of 5G parameters.

Also, if the UE receives the 36th identification via 3GPP access, the UE is operating in single registration mode, and the tracking area update procedure in EPS is rejected using the 36th identification, the UE may operate using the EMM state, EPS update status, 4G-GUTI, tracking area updating attempt counter, etc. In other words, the UE may operate using 4G parameters instead of 5G parameters.

Also, if the UE receives the 36th identification information and disables the N1 mode capability, and the UE's lower layers do not provide information that the current E-UTRA cell is connected to the EPC, it may search for a suitable E-UTRA cell to connect to the EPC.

Also, if the UE receives the 36th identification information and disables the N1 mode capability, and the UE's lower layers provide information that the current E-UTRA cell is connected to the EPC, the UE may perform core network selection to select the EPC.

Also, if the UE receives the 36th identification information and disables the N1 mode capability, and the UE's lower layers cannot find an E-UTRA cell connected to the EPC, it may indicate to the lower layers that it will continue to camp on the E-UTRA cell connected to the 5GC, may start a timer, or may transition to the 5GMM-REGISTERED.LIMITED-SERVICE state.

Furthermore, when the UE receives the 34th identification information, and/or the 36th identification information, and/or the 37th identification information, it may recognize that the use of the S-NSSAI indicated by the 34th identification information is not permitted (rejected), and/or that the establishment of the PDU session is not permitted (rejected), and/or that the UE's request is not permitted (rejected).

Furthermore, when the UE receives the 34th identification information, and/or the 36th identification information, and/or the 37th identification information, the UE may recognize that the reason why the use of the S-NSSAI indicated by the 34th identification information was not permitted (rejected), and/or the reason why the establishment of the PDU session was not permitted (rejected), and/or the reason why the UE's request was not permitted (rejected) is based on the information indicated by the 36th identification information.

Furthermore, when the UE receives identification information No. 34, identification information No. 36, and/or identification information No. 37, it may set the back-off timer value indicated by identification information No. 37 to a timer that the UE has and that corresponds to the S-NSSAI indicated by identification information No. 34, and start the timer. The UE may not be able to send an MM message and/or SM message for the S-NSSAI indicated by identification information No. 34 while the timer corresponding to the S-NSSAI indicated by identification information No. 34 is running. The UE may be able to send an MM message and/or SM message for the S-NSSAI when the timer corresponding to the S-NSSAI indicated by identification information No. 34 expires. Note that the UE may send an MM message and/or SM message for an S-NSSAI other than the S-NSSAI even if the timer corresponding to the S-NSSAI indicated by identification information No. 34 is running.

Furthermore, based on receiving the 34th identification information, and/or the 36th identification information, and/or the 37th identification information, and/or the 38th identification information, the UE may decide to communicate via E-UTRAN and/or the EPC and/or the EPS, or to perform a system change from N1 mode to S1 mode, or to change from communication using 5G to communication using 4G. In this case, the UE may perform an attach procedure and/or a tracking area update procedure in the EPS.

Furthermore, even if the UE performs an attach procedure and/or a tracking area update procedure in EPS, the UE may continue or stop the operation of the timer corresponding to the S-NSSAI indicated by the 34th identification information. If the UE continues the operation of the timer corresponding to the S-NSSAI indicated by the 34th identification information, the UE may not be able to send an MM message and/or an SM message for that S-NSSAI in 5GS until the timer expires. Then, when the timer expires, the UE may be able to send an MM message and/or an SM message for that S-NSSAI in 5GS. Furthermore, if the UE stops the operation of the timer corresponding to the S-NSSAI indicated by the 34th identification information, the UE may be able to send an MM message and/or an SM message for that S-NSSAI in 5GS.

The UE may also start a timer to release the NAS signaling connection if it receives a registration rejection message containing the 36th identification information.

Furthermore, if the UE does not receive the 34th identification information or receives the 34th identification information indicating no S-NSSAI, the UE may recognize that the above operation is for no S-NSSAI.

Furthermore, if the UE does not receive the 35th identification information or receives the 35th identification information indicating no DNN, the UE may recognize that the above operation is for no DNN.

Each device may complete this procedure based on sending and receiving a PDU session establishment acceptance message. At this time, each device may transition to a state in which it can communicate with the DN using the established PDU session.

Each device may complete this procedure based on sending or receiving a PDU session establishment acceptance message or a PDU session establishment rejection message. At this time, each device will not be able to establish a PDU session, and therefore will not be able to communicate with the DN if there is no already established PDU session.

Note that the processes performed by the UE based on the reception of each piece of identification information described above may be performed during this procedure, after completion of this procedure, or after completion of this procedure based on the completion of this procedure.

Each device may complete this procedure based on sending and receiving a PDU session establishment acceptance message. At this time, each device may transition to a state in which it can communicate with the DN using the newly established PDU session.

Each device may complete this procedure based on sending and receiving a PDU session establishment rejection message. At this time, each device cannot establish a new PDU session, and therefore cannot communicate with the DN if there is no already established PDU session.

Note that the processes performed by the UE based on the reception of each piece of identification information described above may be performed during this procedure, after completion of this procedure, or after completion of this procedure based on the completion of this procedure.

4. Variations
The program that runs on the device according to the present invention may be a program that controls a central processing unit (CPU) or the like to make a computer function so as to realize the functions of the embodiments according to 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 other storage device system.

In addition, a program for realizing the functions of the embodiments of the present invention may be recorded on a computer-readable recording medium. The program may be read into a computer system and executed to realize the functions. The term "computer system" as used here refers to a computer system built into a device, and includes hardware such as an operating system and peripheral devices. Furthermore, the term "computer-readable recording medium" may refer to a semiconductor recording medium, optical recording medium, magnetic recording medium, medium that dynamically stores a program for a short period of time, or any other computer-readable recording medium.

Furthermore, 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, if advances in semiconductor technology result in the emergence of integrated circuit technologies that replace current integrated circuits, one or more aspects of the present invention may also utilize new integrated circuits based on that technology.

Note that the present invention is not limited to the above-described embodiment. While the embodiment describes one example of a device, the present invention is not limited to this and can be applied to terminal devices or communication devices for stationary or non-mobile 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.

Although the embodiments of the present invention have been described above in detail 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 within the technical scope of the present invention. Furthermore, configurations in which elements described in the above embodiments are substituted for elements that achieve similar effects are also included.

1. Mobile communication systems
10 UE_A
30 PGW-U
32 PGW-C
35 SGW
40 MME
45 eNB
50 HSS
60 PCRF
80 Access Network_A (E-UTRAN)
90 Core Network_A
120 Access Network_B (5G AN)
122 gNB
130 UPF
132 SMF
140 AMF
150 UDM
160 PCF
190 Core Network_B

Claims (1)

A UE (User Equipment) including a transceiver unit and a control unit,
When the transceiver unit receives, from the base station device, a registration acceptance message including an S-NSSAI (Single Network Slice Selection Assistance Information) exceeding the maximum number of UEs per network slice and an Allowed NSSAI (Network Slice Selection Assistance Information) including a reason value indicating that the maximum number of UEs per network slice has been exceeded, the control unit:
If E-UTRA capability is disabled, enable E-UTRA capability;
Disable N1 mode capability for 3GPP access,
5Transition to GMM-DEREGISTERED.NO-CELL-AVAILABLE state,
storing the S-NSSAI;
A UE characterized by: