Core network node and method thereof

Abstract

To contribute to implementing session management that adapts to restrictions on use of network slices.SOLUTION: A first core network node receives, from a second core network node, a first message including user equipment moving to an area that is not an area associated with a single network slice selection assistance information (S-NSSAI) identifying a network slice. The first core network node then transmits, to the user equipment via the second core network node, a second message including deactivating a session established for the user equipment and initiating release of the session.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to wireless communication networks, and more particularly to network slicing. [Background technology]

[0002] The 5G system (5GS) supports network slicing. Network slicing allows multiple logical networks or non-virtualized logical networks to be created on a physical network. For example, network slicing may use Network Function Virtualization (NFV) technology and software-defined networking (SDN) technology to create multiple virtualized logical networks on a physical network. Each logical network is called a network slice. A network slice provides specific network capabilities and network characteristics. A network slice instance (NSI) is defined as a set of network function (NF) instances, resources (e.g., computer processing resources, storage, and networking resources), and access networks (ANs) (Next Generation Radio Access Network (NG-RAN) and / or Non-3GPP InterWorking Function (N3IWF)) to form one network slice.

[0003] A network slice is identified by an identifier known as Single Network Slice Selection Assistance Information (S-NSSAI). S-NSSAI consists of Slice / Service type (SST) and Slice Differentiator (SD). SST refers to the expected network slice behavior in terms of features and services. SD is optional information that complements SST to differentiate between multiple network slices of the same Slice / Service type.

[0004] The S-NSSAI can have standard values ​​or non-standard values. Currently, standard SST values ​​1, 2, 3, and 4 are associated with enhanced Mobile Broad Band (eMBB), Ultra Reliable and Low Latency Communication (URLLC), Massive Internet of Things (MIoT), and Vehicle to Everything (V2X) slice types. The non-standard values ​​of the S-NSSAI identify one network slice in a particular Public Land Mobile Network (PLMN). That is, the non-standard SST values ​​are PLMN-specific values ​​and are associated with the PLMN ID of the PLMN that assigned them. Each S-NSSAI ensures network isolation in terms of selecting a particular NSI. The same NSI may be selected via different S-NSSAIs. The same S-NSSAI may be associated with different NSIs. Each network slice may be uniquely identified by an S-NSSAI.

[0005] There are two types of S-NSSAI, known as S-NSSAI and Mapped S-NSSAI. S-NSSAI identifies the network slice served by the serving Public Land Mobile Network (PLMN) to which the UE is attached. Thus, when the UE is in the home network, S-NSSAI identifies the network slice of the home network (e.g., Home PLMN (HPLMN)). When roaming, S-NSSAI identifies the network slice of the roaming network (e.g., Visited PLMN (VPLMN)). Mapped S-NSSAI may be the S-NSSAI of the Home PLMN (HPLMN) that is mapped (associated or corresponds) to the S-NSSAI that identifies the network slice of the roaming network when the UE is roaming, and may further be the S-NSSAI included in the subscriber information of the UE user therein.

[0006] On the other hand, Network Slice Selection Assistance Information (NSSAI) refers to a set of S-NSSAIs. Therefore, at least one S-NSSAI can be included in one NSSAI. There are several types of NSSAI, which are known as Configured NSSAI, Requested NSSAI, Allowed NSSAI, Rejected NSSAI, and Pending NSSAI.

[0007] The Configured NSSAI includes at least one S-NSSAI, each applicable to at least one PLMN. The Configured NSSAI is configured by, for example, a Serving PLMN and applied to the Serving PLMN. Alternatively, the Configured NSSAI may be a Default Configured NSSAI. The Default Configured NSSAI is configured by a Home PLMN (HPLMN) and applied to any PLMNs for which a specific Configured NSSAI is not provided. The Default Configured NSSAI is provisioned to a radio terminal (User Equipment (UE)) from, for example, a Unified Data Management (UDM) of the HPLMN via an Access and Mobility Management Function (AMF).

[0008] The Requested NSSAI is signaled by the UE to the network, for example during a registration procedure, and enables the network to determine a Serving AMF, at least one network slice, and at least one NSI for the UE.

[0009] The Allowed NSSAI is provided to the UE by the Serving PLMN and indicates at least one S-NSSAI that the UE can use in the current Registration Area (RA) of the Serving PLMN. The Allowed NSSAI is determined by the AMF of the Serving PLMN, e.g., during the registration procedure. The Allowed NSSAI is signaled to the UE by the network (i.e., AMF) and stored in the respective memories (e.g., non-volatile memories) of the AMF and the UE.

[0010] The Rejected NSSAI includes at least one S-NSSAI rejected by the current PLMN. The Rejected NSSAI may also be referred to as rejected S-NSSAIs. The S-NSSAI is rejected by the entire current PLMN or by the current Registration Area (RA). If the AMF rejects any of the at least one S-NSSAI included in the Requested NSSAI, for example during the UE registration procedure, it includes them in the Rejected NSSAI. The Rejected NSSAI is signaled to the UE by the network (i.e., AMF) and stored in the respective memories of the AMF and the UE.

[0011] A Pending NSSAI indicates at least one S-NSSAI for which Network Slice-Specific Authentication and Authorization (NSSAA) is pending. The Serving PLMN must perform an NSSAA for the S-NSSAI(s) of the HPLMN for which an NSSAA is imposed based on the subscription information. To perform an NSSAA, the AMF invokes an Extensible Authentication Protocol (EAP)-based authorization procedure. The EAP-based authentication procedure takes a relatively long time to obtain an outcome. Therefore, the AMF determines the Allowed NSSAI as described above in the UE registration procedure, but does not include the S-NSSAI(s) for which an NSSAA is imposed in the Allowed NSSAI, but includes them in the Pending NSSAI instead. The Pending NSSAI is signaled to the UE by the network (i.e., AMF) and stored in the respective memories of the AMF and the UE.

[0012] The 3rd Generation Partnership Project (3GPP) is considering network slice enhancements for Release 17. In addition, the 3GPP Technical Specification Group Services and System Aspects (TSG-SA) Working Group 1 (WG1) has approved a new working / study item for Release 18 to investigate the feasibility of Enhanced Access to and Support of Network Slice (see Non-Patent Document 1). One of the objectives of this study item is to identify various deployment and usage scenarios of network slices, when there is a restriction of network slice to e.g., certain frequency bands / sub bands, RATs, geographical areas, networks and applications.Another objective of this study item is to identify various deployment and usage scenarios of network slices, when a UE has a subscription to multiple network slices and these network slices are deployed for e.g., different frequency bands / sub bands, RATs, geographical area, networks, and applications. [Prior art documents] [Non-patent literature]

[0013] [Non-Patent Document 1] 3GPP SA WG1, "New WID on Study on Enhanced Access to and Support of Network Slice (from S1-202284)", SP-200571, 3GPP TSG SA Meeting # 88e, Electronic Meeting, June 30th - July 3rd 2020 [Non-Patent Document 2] 3GPP TS 23.501 V16.6.0 (2020-09) “3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; System architecture for the 5G System (5GS); Stage 2 (Release 16)”, September 2020 Summary of the Invention [Problem to be solved by the invention]

[0014] At this time, it is unclear how the UE and the network will deal with various restrictions on the use of network slices (e.g., restrictions on frequency bands, geographic areas, or applications). For example, it is unclear how the core network will perform session management for the UE based on restrictions on the use of network slices.

[0015] One of the objectives of the embodiments disclosed herein is to provide an apparatus, a method, and a program that contribute to realizing session management adapted to restrictions on the use of network slices. It should be noted that this objective is only one of the objectives of the embodiments disclosed herein. Other objectives or problems and novel features will be apparent from the description of this specification or the accompanying drawings. [Means for solving the problem]

[0016] In a first aspect, a core network node for session management comprises at least one memory and at least one processor coupled to the at least one memory, the at least one processor configured to receive a report from a core network node for mobility management indicating that an update of a restriction on a use of a network slice by a UE has occurred, the at least one processor further configured to control a release or modification of an established PDU Session of the UE associated with the network slice in response to receiving the report.

[0017] In a second aspect, a core network node for mobility management comprises at least one memory and at least one processor coupled to the at least one memory, the at least one processor configured to, in response to updating a restriction on a use of a network slice by a UE, send a report to the core network node for session management indicating that the update of the restriction has occurred.

[0018] In a third aspect, a method performed by a core network node for session management comprises the steps of: (a) receiving a report from a core network node for mobility management indicating that an update to a restriction on the use of a network slice by a UE has occurred; and (b) the at least one processor further controls release or modification of an established PDU Session of the UE associated with the network slice in response to receiving the report.

[0019] In a fourth aspect, a method performed by a core network node for mobility management includes, in response to updating a restriction on use of a network slice by a UE, sending a report to a core network node for session management indicating that the update of the restriction has occurred.

[0020] In a fifth aspect, a core network node for mobility management comprises at least one memory and at least one processor coupled to the at least one memory, the at least one processor being configured to request a core network node for session management to release an established PDU Session associated with the network slice or to deactivate user plane resources of the established PDU Session in response to updating a restriction on usage of the network slice.

[0021] In a sixth aspect, a method performed by a core network node for mobility management includes, in response to updating restrictions on use of a network slice, requesting a core network node for session management to release an established PDU Session associated with the network slice or deactivate user plane resources of the established PDU Session.

[0022] In a seventh aspect, a core network node for mobility management comprises at least one memory and at least one processor coupled to the at least one memory. The at least one processor is configured to receive from a UE a first Non-Access Stratum (NAS) message including a Session Management (SM) message requesting establishment of a PDU Session. The at least one processor is configured to determine whether a usage restriction is imposed or needs to be imposed on a network slice identifier associated with the PDU Session. If the usage restriction is imposed or needs to be imposed on the network slice identifier, the at least one processor is configured to stop forwarding the SM message to a core network node for session management and reject the NAS message. The usage restriction includes at least one of a restriction on a radio frequency on which the network slice can be used, a restriction on a radio access technology on which the network slice can be used, a restriction on a geographical area on which the network slice can be used, and a restriction on an application on which the network slice can be used.

[0023] In an eighth aspect, a method performed by a core network node for mobility management comprises the following steps: (a) receiving a first NAS message from a UE, the first NAS message including an SM message requesting establishment of a PDU Session; (b) determining whether a usage restriction is imposed or needs to be imposed on a network slice identifier associated with the PDU Session; and (c) if the usage restriction is or should be imposed on the network slice identifier, stopping forwarding the SM message to a core network node for session management and rejecting the NAS message, the usage restriction including at least one of a restriction on a radio frequency on which the network slice can be used, a restriction on a radio access technology on which the network slice can be used, a restriction on a geographical area on which the network slice can be used, and a restriction on an application on which the network slice can be used.

[0024] In a ninth aspect, a core network node for mobility management comprises at least one memory and at least one processor coupled to the at least one memory. The at least one processor is configured to receive from a UE a NAS message including an SM message requesting establishment of a PDU Session. The at least one processor is configured to determine whether a usage restriction needs to be imposed on a network slice identifier associated with the PDU Session. If the usage restriction needs to be imposed on the network slice identifier, the at least one processor is configured to forward the SM message to a core network node for session management together with an indication that establishment of the PDU Session should be rejected due to the usage restriction. The usage restriction includes at least one of a restriction on a radio frequency on which a network slice can be used, a restriction on a radio access technology on which a network slice can be used, a restriction on a geographical area on which a network slice can be used, and a restriction on an application on which a network slice can be used.

[0025] In a tenth aspect, a core network node for session management comprises at least one memory and at least one processor coupled to the at least one memory. The at least one processor is configured to receive a control message from a core network node for mobility management, the control message including a first SM message requesting establishment of a PDU Session for a UE. The at least one processor is configured to reject establishment of the PDU Session if the control message includes an indication indicating that establishment of the PDU Session should be rejected due to usage restrictions. The usage restrictions include at least one of restrictions on radio frequencies on which a network slice can be used, restrictions on radio access technologies on which a network slice can be used, restrictions on geographical areas on which a network slice can be used, and restrictions on applications on which a network slice can be used.

[0026] In an eleventh aspect, a method performed by a core network node for mobility management comprises the following steps: (a) receiving a NAS message from a UE, the NAS message including an SM message requesting establishment of a PDU Session; (b) determining whether a usage restriction needs to be imposed on a network slice identifier associated with the PDU Session; and (c) if the usage restriction needs to be imposed on the network slice identifier, forwarding the SM message to a core network node for session management together with an indication indicating that establishment of the PDU Session should be rejected due to the usage restriction, the usage restriction including at least one of a restriction on a radio frequency on which the network slice can be used, a restriction on a radio access technology on which the network slice can be used, a restriction on a geographical area on which the network slice can be used, and a restriction on an application on which the network slice can be used.

[0027] In a twelfth aspect, a method performed by a core network node for session management comprises the steps of: (a) receiving a control message from a core network node for mobility management, the control message including a first SM message requesting establishment of a PDU Session for the UE; and (b) rejecting the establishment of the PDU Session if the control message includes an indication indicating that the establishment of the PDU Session should be rejected due to a usage restriction, the usage restriction including at least one of a restriction on a radio frequency on which the network slice can be used, a restriction on a radio access technology on which the network slice can be used, a restriction on a geographical area on which the network slice can be used, and a restriction on an application on which the network slice can be used.

[0028] In a thirteenth aspect, the program comprises a set of instructions (software code) which, when loaded into a computer, causes the computer to perform a method according to the third, fourth, sixth, eighth, eleventh or twelfth aspect described above. Effect of the Invention

[0029] According to the above aspects, an apparatus, method, and program can be provided that contribute to realizing session management that adapts to restrictions on the use of network slices. [Brief description of the drawings]

[0030] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a communication network according to an embodiment. [Diagram 2] 10 is a flowchart illustrating an example of an operation of AMF according to an embodiment. [Diagram 3] 11 is a flowchart showing an example of an operation of the SMF according to the embodiment. [Figure 4] A sequence diagram showing an example of the operation of the UE, AMF, and SMF relating to the embodiment. [Diagram 5]A sequence diagram showing an example of the operation of the UE, AMF, and SMF relating to the embodiment. [Figure 6] A sequence diagram showing an example of the operation of the UE, AMF, and SMF relating to the embodiment. [Figure 7] A sequence diagram showing an example of the operation of a UE and an AMF according to the embodiment. [Figure 8] 10 is a flowchart illustrating an example of an operation of AMF according to an embodiment. [Figure 9] 10 is a flowchart illustrating an example of an operation of AMF according to an embodiment. [Figure 10] 10 is a flowchart illustrating an example of an operation of AMF according to an embodiment. [Figure 11] A sequence diagram showing an example of the operation of the AMF and other NFs according to the embodiment. [Figure 12] A sequence diagram showing an example of the operation of the UE, AMF, and SMF relating to the embodiment. [Figure 13] 10 is a flowchart illustrating an example of an operation of AMF according to an embodiment. [Figure 14] FIG. 2 is a block diagram showing an example of the configuration of a UE according to the embodiment. [Figure 15] A block diagram showing an example of the configuration of AMF and SMF according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] In the following, specific embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numerals, and duplicated descriptions will be omitted as necessary for clarity of explanation.

[0032] The multiple embodiments described below can be implemented independently or in appropriate combination. These multiple embodiments have different novel features. Therefore, these multiple embodiments contribute to solving different objects or problems and provide different effects.

[0033] The following embodiments are described mainly for the 3GPP fifth generation mobile communication system (5G system (5GS)). However, these embodiments may be applied to other cellular communication systems that support network slicing similar to 5GS.

[0034] <First embodiment> FIG. 1 shows an example of the configuration of a communication network (i.e., 5GS) according to this embodiment. Each of the elements shown in FIG. 1 is a network function, and provides an interface defined by the 3rd Generation Partnership Project (3GPP). Each of the elements (network functions) shown in FIG. 1 can be implemented, for example, as a network element on dedicated hardware, as a software instance running on dedicated hardware, or as a virtualized function instantiated on an application platform.

[0035] The cellular network shown in Fig. 1 may be provided by a Mobile Network Operator (MNO) or may be a Non-Public Network (NPN) provided by a party other than an MNO. If the cellular network shown in Fig. 1 is an NPN, it may be an independent network represented as a Stand-alone Non-Public Network (SNPN) or an NPN linked to an MNO network represented as a Public network integrated NPN (PNI-NPN).

[0036] A wireless terminal (i.e., UE) 1 uses a 5G connectivity service to communicate with a data network (DN) 7. More specifically, the UE 1 is connected to an access network (i.e., 5G Access Network (5GAN)) 5 and communicates with the data network (DN) 7 via a User Plane Function (UPF) 6 in a core network (i.e., 5G core network (5GC)). The AN 5 includes a Next Generation Radio Access Network (NG-RAN) or a non-3GPP AN, or both. The non-3GPP AN may be a network that handles wireless LAN (WiFi) communication, or may be a network that handles wired communication represented as a Wireline 5G Access Network (W-5GAN). The UPF 6 may include multiple UPFs that are interconnected.

[0037] UE1 establishes one or more Protocol Data Unit (PDU) Sessions between UE1 and a UPF6 (i.e., PDU session anchor) to which UE1 and DN7 are connected. A PDU Session is an association, session, or connection between UE1 and DN7. A PDU Session is used to provide a PDU connectivity service (i.e., exchange of PDUs between UE1 and DN7). In terms of data transfer, a PDU Session consists of a tunnel in 5GC (N9 tunnel), a tunnel between 5GC and AN5 (N3 tunnel), and one or more radio bearers. Although not shown in FIG. 1, UE1 may establish multiple PDU Sessions with multiple UPFs (PDU session anchors)6, respectively, to access multiple DNs7 concurrently.

[0038] AMF2 is one of the network functions in the 5GC Control Plane. AMF2 provides the termination of the (R)AN Control Plane (CP) interface (i.e., N2 interface). AMF2 terminates a single signaling connection (i.e., NAS signalling connection) with UE1 and provides registration management, connection management, and mobility management. Registration management is used to register or deregister UE1 to the network (5G system). Connection management is used to establish and release the NAS signalling connection between UE1 and AMF2. Mobility management is used to keep track of the location of UE1. Mobility management uses a periodic registration update procedure and a mobility registration update procedure. Therefore, in the 5G system, it can be said that mobility management is included in registration management.

[0039] The AMF2 provides NF services to NF consumers (e.g., other AMFs and the Session Management Function (SMF) 3) over a service-based interface (i.e., Namf interface). The NF services provided by the AMF2 include a communication service (Namf_Communication), which enables the NF consumers (e.g., SMF 3) to communicate with the UE 1 or the AN 5 via the AMF2. Furthermore, the AMF2 consumes NF services provided by other NFs (e.g., the Network Slice Selection Function (NSSF) 4 and the Unified Data Management (UDM) 8).

[0040] The SMF3 is one of the network functions in the 5GC Control Plane. The SMF3 provides session management. The session management is used to establish, modify, and release PDU Sessions to provide PDU Connectivity Service to UE1. The session management includes signaling with UE1, AMF2, and UPF6 for establishing, modifying, and releasing PDU Sessions.

[0041] The SMF3 transmits and receives SM signaling messages (NAS-SM messages, N1 SM messages) to and from the Non-Access-Stratum (NAS) Session Management (SM) layer of UE1 via the communication service provided by AMF2. The SMF3 provides NF services to NF consumers (e.g., AMF2, other SMFs) over a service-based interface (i.e., Nsmf interface). The NF services provided by the SMF3 include a session management service (Nsmf_PDUSession), which allows NF consumers (e.g., AMF2) to handle PDU Sessions. The SMF3 may be an Intermediate SMF (I-SMF). The I-SMF is inserted between the AMF2 and the original SMF as needed when the UPF6 belongs to a different SMF service area and cannot be controlled by the original SMF.

[0042] NSSF4 is one of the network functions in the 5GC Control Plane. AMF2 or NSSF4 determines the mapping of the Configured NSSAI for the serving PLMN (i.e., VPLMN) to the HPLMN Subscribed S-NSSAI(s). Furthermore, AMF2 or NSSF4 determines the mapping of the Allowed NSSAI for the serving PLMN (i.e., VPLMN) to the HPLMN Subscribed S-NSSAI(s). The Configured NSSAI is provisioned in UE1 by the serving PLMN (i.e., VPLMN) during the Registration procedure or the UE Configuration Update procedure. The Configured NSSAI includes at least one S-NSSAI, each applicable to at least one PLMN. Meanwhile, the Allowed NSSAI indicates at least one S-NSSAI that UE1 can use in the current Registration Area of ​​the serving PLMN (i.e., VPLMN). The Allowed NSSAI is provisioned in UE1 by the serving PLMN (ie, VPLMN), for example during the registration procedure.

[0043] UDM8 is one of the network functions in the 5GC Control Plane. UDM8 provides access to a database (i.e., User Data Repository (UDR)) where subscriber data (subscription information) is stored. UDM8 provides NF services to NF consumers (e.g., AMF2 and SMF3) over a service-based interface (i.e., Nudm interface). The NF services provided by UDM8 include a subscriber data management service. The NF services allow NF consumers (e.g., AMF2) to retrieve subscriber data and provide updated subscriber data to NF consumers.

[0044] In addition, the network function that stores subscriber data (subscription information) may be UDM8 or UDR. If a split architecture that separates data management and data repository is used in the network design or operation policy of a network operator, the subscriber data may be stored by UDR. On the other hand, if a split architecture is not used, the subscriber data may be stored by UDM8. In this specification, the network function that stores subscriber data may be UDM8 or UDR.

[0045] Next, details of the session management according to this embodiment will be described below. FIG. 2 shows an example of the operation of the AMF2. In step 201, the AMF2 manages the state of the network slice restriction (NSR). Specifically, the AMF2 manages whether there is a restriction on the use of the network slice identified by each of one or more S-NSSAIs. The restriction on the use of the network slice may include at least one of a restriction on a radio frequency (e.g., a frequency band or a sub-band) in which the network slice can be used, a restriction on a radio access technology (RAT) in which the network slice can be used, a restriction on a geographical area in which the network slice can be used, a restriction on an application in which the network slice can be used, and a priority among multiple network slices.

[0046] In one example, the AMF2 may recognize that an S-NSSAI is in an NSR state where it is usable only in one or more specific frequency bands, or that it is in an NSR state where it cannot be used in one or more specific frequency bands. The AMF2 may recognize that an S-NSSAI is in an NSR state where it is usable only in one or more specific RATs, or that it is in an NSR state where it cannot be used in one or more specific RATs. In one example, the AMF2 may recognize that an S-NSSAI is in an NSR state where it is usable only in one or more specific geographical areas, or that it is in an NSR state where it cannot be used in one or more specific geographical areas. Each geographical area may be a tracking area or a cell. In one example, the AMF2 may recognize that an S-NSSAI is in an NSR state where it is usable only for one or more specific applications (or services), or that it is in an NSR state where it cannot be used for one or more specific applications (or services). In one example, AMF2 may recognize that multiple S-NSSAIs are in an NSR state where there is a priority among multiple network slices (S-NSSAIs). For example, AMF2 may recognize that when a network slice with a higher priority is being used by UE1, a network slice with a lower priority cannot be used simultaneously by the same UE1. Alternatively, AMF2 may recognize that an S-NSSAI (network slice) is in an NSR state where it cannot be used simultaneously with other S-NSSAI(s) (network slices).

[0047] In step 202, the AMF2 sends a report indicating the NSR status update to the SMF3 when an update of the restrictions on the use of a specific S-NSSAI occurs for the UE1 (i.e., an update of the NSR status of the UE1). The AMF2 may send the report to the SMF3 that manages the established PDU Session of the UE1 associated with the S-NSSAI. The report enables the SMF3 to control the release or modification of the established PDU Session associated with the S-NSSAI in response to the update of the NSR status.

[0048] The report indicating the NSR status update of step 202 may indicate an S-NSSAI and an NSR status for that S-NSSAI. The report may indicate that the NSR status is active, inactive, or unknown. An active status means that the use of the corresponding S-NSSAI is restricted. An inactive status means that the use of the corresponding S-NSSAI is not restricted. An unknown status means that it is not known whether the corresponding S-NSSAI is restricted or not.

[0049] The report indicating the NSR status update in step 202 may be provided to the SMF3 via an Application Program Interface (API) of an event notification service (i.e., Namf_EventExposure Service) provided by the AMF2. More specifically, the SMF3 as an NF Service Consumer requests the AMF2 to create a new subscription when a subscription is required to monitor at least one event related to the NSR status of at least one S-NSSAI. The SMF3 includes in the request an identifier identifying a specific UE (or UE group) and a list of subscribed events (e.g., list of S-NSSAI(s)) to indicate the Subscription Target. If the request is accepted, the AMF2 notifies the SMF3 of the creation of the event subscription. Afterwards, when an event of the subscribed NSR status notification occurs, the AMF2 sends a notification to the SMF3.

[0050] FIG. 3 shows an example of the operation of SMF3. In step 301, SMF3 receives a report from AMF2 indicating a restriction on the use of a particular S-NSSAI by UE1 (i.e., an update of the NSR state of UE1). In step 302, in response to the report, SMF3 controls the release or modification of an established PDU Session of UE1 associated with the S-NSSAI. For example, SMF3 may initiate the release of an established PDU Session or the deactivation of user plane resources of an established PDU Session if the report indicates that there is a restriction on the use of a network slice by UE1. SMF3 may also reject a modification of an established PDU Session requested by UE1 if the report indicates that there is a restriction on the use of a network slice by UE1.

[0051] FIG. 4 shows an example of a PDU Session release procedure initiated by the SMF 3. In step 401, the UE 1 establishes a PDU Session. Step 401 may be performed according to an existing PDU Session establishment procedure. In step 402, the AMF 2 detects an update of the NSR state of the UE 1 for at least one S-NSSAI. For example, the AMF 2 may detect that the UE 1 has moved from a geographical area where the network slice is available to a geographical area where the use of the network slice is restricted. Here, the geographical area may be indicated by a collection of Tracking Area Identities (TAIs), a collection of E-UTRAN Cell Global Identifications (ECGIs), or a collection of NR Cell Global Identities (NCGIs). Alternatively, the geographical area may be an Allowed Area, a Non-Allowed Area, a Forbidden Area, or a Mobility Pattern as defined in Non-Patent Document 2.

[0052] In step 403, the AMF2 sends a report indicating an NSR status update to the SMF3. The report indicates a restriction on the use of a specific S-NSSAI by UE1 (i.e., an update of the NSR status of UE1). In step 404, if the report indicating the NSR status update indicates that there is a restriction on the use of a specific S-NSSAI by UE1, the SMF3 decides to release the established PDU Session of UE1 for the S-NSSAI. More specifically, in step 404, if the S-NSSAI associated with the established PDU Session is included in the report indicating the NSR status update and indicates that the NSR status for the S-NSSAI is restricting the use, and the SMF3 decides to release the established PDU Session, the SMF3 decides to release the established PDU Session associated with the S-NSSAI.

[0053] In step 405, the SMF 3 initiates a PDU Session Release procedure. The SMF 3 sends a PDU Session Release Command message to the UE 1 via the AMF 2. The PDU Session Release Command message may include a new 5GSM cause value indicating that the use of the S-NSSAI is restricted.

[0054] The procedure of Fig. 4 may be modified as follows: In step 404, if the report indicating the NSR status update indicates that there is a restriction on the use of a particular S-NSSAI by UE1, the SMF3 may decide to deactivate the user plane resources of the established PDU Session of UE1 for that S-NSSAI. In step 405, the SMF3 may signal with the UPF6 to deactivate the user plane resources of that PDU Session.

[0055] Figure 5 shows an example of a PDU Session Modification procedure. Steps 501 to 503 are similar to steps 401 to 403 in Figure 4. In step 504, SMF3 receives a PPDU Session Modification Request message from UE1. The PDU Session Modification Request message requests modification of a PDU Session for a specific S-NSSAI. In step 505, SMF3 determines based on the report of step 503 that UE1 is restricted from using the S-NSSAI.

[0056] In step 506, the SMF3 sends a PDU Session Modification Reject message to the UE1. The PDU Session Modification Reject message may include a new 5GSM cause value indicating that the use of the S-NSSAI is restricted. More specifically, in step 506, if the S-NSSAI associated with the established PDU Session targeted by the PDU Session Modification Request message is included in the report indicating the update of the NSR status and indicates that the NSR status is restricted for the S-NSSAI, and the SMF3 determines to reject the PDU Session Modification Request, the SMF3 sends a PDU Session Modification Reject message to the UE1.

[0057] As can be understood from the above description, in this embodiment, the AMF2 notifies the SMF3 of the state of restrictions on the use of a specific network slice by the UE1. Then, in response to the notification from the AMF2, the SMF3 controls the release or modification of the established PDU Session of the UE1 for the network slice. This contributes to realizing session management adapted to restrictions on the use of the network slice.

[0058] <Second embodiment> A configuration example of the communication network according to this embodiment is similar to the example described with reference to Fig. 1. This embodiment provides a modification of the first embodiment.

[0059] 6 shows an example of a PDU session release procedure triggered by AMF 2. In step 601, UE 1 establishes a PDU session. Step 601 may be performed according to an existing PDU session establishment procedure.

[0060] In step 602, the AMF2 detects an update of the NSR state of UE1 for at least one S-NSSAI. The operation of the AMF2 in step 602 is similar to the corresponding operation described in the first embodiment (e.g., step 201 in FIG. 2, step 402 in FIG. 4). In the example of FIG. 6, the AMF2 detects that there is a restriction on the use of a particular network slice (a particular S-NSSAI) by UE1. In step 603, the AMF2 requests the SMF3 to release the established PDU Session of UE1 for the particular network slice. The request (or trigger) may include a Cause information element set to a new value (e.g., REL_DUE_TO_SLICE_NWRESTRICTION) to indicate to the SMF3 that this is based on a usage restriction of the network slice. In step 604, the SMF3 initiates a PDU Session Release procedure in response to the request (or trigger) of step 603. The SMF3 sends a PDU Session Release Command message to UE1 via the AMF2. The PDU Session Release Command message may include a new 5GSM cause value indicating that the use of the S-NSSAI is restricted.

[0061] The procedure of Fig. 6 may be modified as follows: In step 604, the SMF 3 may initiate deactivation of user plane resources of the established PDU Session of UE1 for the S-NSSAI. The SMF 3 may signal with the UPF 6 to deactivate the user plane resources of the PDU Session.

[0062] As can be understood from the above description, in this embodiment, if the use of a specific network slice by UE1 is restricted, AMF2 requests SMF3 to release the established PDU Session of UE1 for the network slice. This contributes to realizing session management adapted to restrictions on the use of the network slice.

[0063] <Third embodiment> A configuration example of a communication network according to this embodiment is similar to the example described with reference to Fig. 1. This embodiment provides an operation of the AMF2 when the AMF2 receives from the UE1 a NAS message (i.e., UL NAS Transport) including an SM message (i.e., PDU Session Establishment Request) requesting establishment of a PDU Session associated with an S-NSSAI that is not permitted for use by the UE1.

[0064] Figure 7 shows an example of signaling between UE1 and AMF2. Figure 8 shows an example of the operation of AMF2. In step 701, UE1 sends a UL NAS Transport message carrying an N1 SM container (PDU Session Establishment Request) to AMF2 via AN5. In other words, AMF2 receives a UL NAS Transport message carrying a PDU Session Establishment Request message from UE1 (step 801).

[0065] The AMF2 manages whether there are any restrictions on the use of the network slice identified by each of one or more S-NSSAIs. The restrictions on the use of the network slice may include at least one of a restriction on a radio frequency (e.g., a frequency band or sub-band) on which the network slice can be used, a restriction on a radio access technology (RAT) on which the network slice can be used, a restriction on a geographical area on which the network slice can be used, a restriction on an application on which the network slice can be used, and a priority among multiple network slices.

[0066] In one example, the AMF2 may recognize that an S-NSSAI is in an NSR state where it is usable only in one or more specific frequency bands, or that it is in an NSR state where it cannot be used in one or more specific frequency bands. The AMF2 may recognize that an S-NSSAI is in an NSR state where it is usable only in one or more specific RATs, or that it is in an NSR state where it cannot be used in one or more specific RATs. In one example, the AMF2 may recognize that an S-NSSAI is in an NSR state where it is usable only in one or more specific geographical areas, or that it is in an NSR state where it cannot be used in one or more specific geographical areas. Each geographical area may be a tracking area or a cell. In one example, the AMF2 may recognize that an S-NSSAI is in an NSR state where it is usable only for one or more specific applications (or services), or that it is in an NSR state where it cannot be used for one or more specific applications (or services). In one example, AMF2 may recognize that multiple S-NSSAIs are in an NSR state where there is a priority among multiple network slices (S-NSSAIs). For example, AMF2 may recognize that when a network slice with a higher priority is being used by UE1, a network slice with a lower priority cannot be used simultaneously by the same UE1. Alternatively, AMF2 may recognize that an S-NSSAI (network slice) is in an NSR state where it cannot be used simultaneously with other S-NSSAI(s) (network slices).

[0067] In steps 702 and 802, the AMF2 determines whether a usage restriction is imposed on the S-NSSAI associated with the PDU Session requested by the UE1. In steps 703 and 803, if a usage restriction is imposed on the S-NSSAI, the AMF2 stops forwarding the PDU Session Establishment Request message to the SMF3 and rejects the UL NAS Transport message. As shown in step 703, the AMF2 may send a DL NAS Transport message to the UE1. The DL NAS Transport message may include the rejected N1 SM container (PDU Session Establishment Request). The DL NAS Transport message may include a message identifier, message sequence number, or other identifier of the UL NAS Transport message to indicate an association with the rejected UL NAS Transport message. The DL NAS Transport message may indicate an existing 5GMM Cause value (e.g., 5GMM cause #90 "payload was not forwarded"). Alternatively, the DL NAS Transport message may include a new 5GMM cause value indicating that the SM message will not be forwarded due to slice usage restrictions.

[0068] FIG. 9 illustrates an example of the operation of AMF2, providing a variation of the operation illustrated in FIG. 8. Step 901 is similar to step 801 in FIG. 8. AMF2 receives a UL NAS Transport message carrying a PDU Session Establishment Request message from UE1. Step 902 determines whether UE1 indicates support for network slice restriction (NSR). In one example, AMF2 may determine whether the received PDU Session Establishment Request message includes an indication indicating support for NSR. In another example, AMF2 may determine whether UE1 indicated support for NSR during a previously performed registration procedure. More specifically, AMF2 may determine whether a context of UE1 stored in AMF2 indicates support for NSR. The indication of support for NSR may be capability information of UE1.

[0069] Step 903 is the same as step 802 in Fig. 8. The AMF2 judges whether or not a usage restriction is imposed on the S-NSSAI associated with the PDU Session requested by the UE1. Note that the order of steps 902 and 903 is not limited to the order shown in Fig. 9. The judgment of step 902 may be performed after the judgment of step 903, or may be performed simultaneously with the judgment of step 903.

[0070] In step 904, if UE1 does not indicate support for NSR and there is usage restriction imposed on the S-NSSAI, AMF2 stops forwarding the PDU Session Establishment Request message to SMF3 and rejects the UL NAS Transport message.

[0071] According to the operation of FIG. 9, AMF2 can reject a PDU Session establishment request for a slice with usage restrictions that is received from a UE that does not support NSR (eg, a pre-Release 18 UE).

[0072] Figure 10 shows an example of the operation of AMF2, providing a variation of the operation shown in Figure 8. Step 901 is similar to step 801 in Figure 8. AMF2 receives a UL NAS Transport message carrying a PDU Session Establishment Request message from UE1. In step 1002, AMF2 determines whether a usage restriction needs to be imposed on the S-NSSAI associated with the PDU Session requested by UE1. In step 903, if a usage restriction needs to be imposed on the S-NSSAI, AMF2 stops forwarding the PDU Session Establishment Request message to SMF3 and rejects the UL NAS Transport message.

[0073] According to the operation of Figure 10, AMF2 can quickly reject a PDU Session Establishment request for a network slice on which usage restrictions need to be imposed if network slice usage restrictions are enabled simultaneously with receiving a PDU Session Establishment Request.

[0074] FIG. 11 shows a variation of the signaling shown in FIG. 7. In some implementations, the AMF2 may receive information about the NSR from another network function (Network Function (NF)) 1100. The NF 1100 may be the NSSF4, UDM8, or UDR described above. The NF 1100 may be any other of the existing NFs of 5GC, for example, a Policy Control Function (PCF) or a Network Data Analytics Function (NWDAF). Alternatively, the NF 1100 may be a new network function of 5GC. In step 1101, the AMF2 queries the NF 1100 for information about the NSR. In step 1102, the AMF2 receives a report (e.g., NSR report) including information about the NSR from the NF 1100.

[0075] According to this embodiment, it is possible for the AMF to control the forwarding of SM messages (PDU Session Establishment Request messages) to the SMF taking into account usage restrictions of network slices.

[0076] <Fourth embodiment> A configuration example of the communication network according to this embodiment is similar to the example described with reference to Fig. 1. This embodiment provides a modification of the third embodiment.

[0077] Figure 12 shows an example of signaling between UE1, AMF2, and SMF3. Figure 13 shows an example of the operation of AMF2. Step 1201 is similar to step 701 in Figure 7. UE1 sends a UL NAS Transport message carrying an N1 SM container (PDU Session Establishment Request) to AMF2 via AN5. In other words, AMF2 receives a UL NAS Transport message carrying a PDU Session Establishment Request message from UE1 (step 1301).

[0078] The AMF2 manages whether there are any restrictions on the use of the network slice identified by each of one or more S-NSSAIs. The restrictions on the use of the network slice may include at least one of a restriction on a radio frequency (e.g., a frequency band or sub-band) on which the network slice can be used, a restriction on a radio access technology (RAT) on which the network slice can be used, a restriction on a geographical area on which the network slice can be used, a restriction on an application on which the network slice can be used, and a priority among multiple network slices.

[0079] In one example, the AMF2 may recognize that an S-NSSAI is in an NSR state where it is usable only in one or more specific frequency bands, or that it is in an NSR state where it cannot be used in one or more specific frequency bands. The AMF2 may recognize that an S-NSSAI is in an NSR state where it is usable only in one or more specific RATs, or that it is in an NSR state where it cannot be used in one or more specific RATs. In one example, the AMF2 may recognize that an S-NSSAI is in an NSR state where it is usable only in one or more specific geographical areas, or that it is in an NSR state where it cannot be used in one or more specific geographical areas. Each geographical area may be a tracking area or a cell. In one example, the AMF2 may recognize that an S-NSSAI is in an NSR state where it is usable only for one or more specific applications (or services), or that it is in an NSR state where it cannot be used for one or more specific applications (or services). In one example, AMF2 may recognize that multiple S-NSSAIs are in an NSR state where there is a priority among multiple network slices (S-NSSAIs). For example, AMF2 may recognize that when a network slice with a higher priority is being used by UE1, a network slice with a lower priority cannot be used simultaneously by the same UE1. Alternatively, AMF2 may recognize that a certain S-NSSAI (network slice) is in an NSR state where it cannot be used simultaneously with other S-NSSAI (network slices). Similar to the operation shown in FIG. 11, AMF2 may receive information about NSR from other network functions.

[0080] In steps 1202 and 1302, the AMF2 determines whether a usage restriction needs to be imposed (or is imposed) on the S-NSSAI associated with the PDU Session requested by the UE1. In steps 1203 and 1303, if a usage restriction needs to be imposed (or is imposed) on the S-NSSAI, the AMF2 forwards a PDU Session Establishment message to the SMF3 with an indication that the establishment of the PDU Session should be rejected due to the usage restriction. Specifically, the AMF2 sends a control message (eg, Nsmf_PDUSession_CreateSMContext Request) including the PDU Session Establishment message and the indication to the SMF3. The indication may be, for example, "REJECT_DUE_TO_SLICE_NWRESTRICTION".

[0081] In step 1204, if the SMF3 receives the PDU Session Establishment message with an indication that the PDU Session establishment should be rejected due to a usage restriction, it rejects the PDU Session establishment. The SMF3 sends a PDU Session Establishment Reject message to the UE1 via the AMF2 (steps 1204 and 1205). The PDU Session Establishment Reject message may include a new 5GSM cause value indicating a slice usage restriction.

[0082] According to this embodiment, the AMF 2 and the SMF 3 can reject a request to establish a PDU session for a network slice with a usage restriction imposed, which contributes to realizing session management adapted to restrictions on the use of the network slice.

[0083] Next, the following describes configuration examples of the UE1, AMF2, and SMF3 according to the above-mentioned embodiments. FIG. 14 is a block diagram showing a configuration example of the UE1. The Radio Frequency (RF) transceiver 1401 performs analog RF signal processing to communicate with RAN nodes. The RF transceiver 1401 may include multiple transceivers. The analog RF signal processing performed by the RF transceiver 1401 includes frequency up-conversion, frequency down-conversion, and amplification. The RF transceiver 1401 is coupled to the antenna array 1402 and the baseband processor 1403. The RF transceiver 1401 receives modulation symbol data (or OFDM symbol data) from the baseband processor 1403, generates a transmission RF signal, and provides the transmission RF signal to the antenna array 1402. The RF transceiver 1401 also generates a baseband reception signal based on the reception RF signal received by the antenna array 1402, and provides the baseband reception signal to the baseband processor 1403. The RF transceiver 1401 may include an analog beamformer circuit for beamforming, which may include, for example, multiple phase shifters and multiple power amplifiers.

[0084] The baseband processor 1403 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. Digital baseband signal processing includes (a) data compression / decompression, (b) data segmentation / concatenation, (c) generation / decomposition of transmission format (transmission frame), (d) transmission line coding / decoding, (e) modulation (symbol mapping) / demodulation, and (f) generation of OFDM symbol data (baseband OFDM signal) by Inverse Fast Fourier Transform (IFFT). Meanwhile, control plane processing includes communication management of layer 1 (e.g., transmission power control), layer 2 (e.g., radio resource management, and hybrid automatic repeat request (HARQ) processing), and layer 3 (e.g., signaling related to attachment, mobility, and call management).

[0085] For example, the digital baseband signal processing by the baseband processor 1403 may include signal processing of a Service Data Adaptation Protocol (SDAP) layer, a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, a Medium Access Control (MAC) layer, and a Physical (PHY) layer. Also, the control plane processing by the baseband processor 1403 may include processing of a Non-Access Stratum (NAS) protocol, a Radio Resource Control (RRC) protocol, and MAC Control Elements (CEs).

[0086] The baseband processor 1403 may perform Multiple Input Multiple Output (MIMO) encoding and precoding for beamforming.

[0087] The baseband processor 1403 may include a modem processor (e.g., Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., Central Processing Unit (CPU) or Micro Processing Unit (MPU)) that performs control plane processing. In this case, the protocol stack processor that performs control plane processing may be shared with the application processor 1404 described later.

[0088] The application processor 1404 is also called a CPU, an MPU, a microprocessor, or a processor core. The application processor 1404 may include multiple processors (multiple processor cores). The application processor 1404 executes a system software program (operating system (OS)) and various application programs (e.g., a call application, a web browser, a mailer, a camera operation application, and a music playback application) read from the memory 1406 or a memory not shown, thereby implementing various functions of the UE1.

[0089] In some implementations, the baseband processor 1403 and the application processor 1404 may be integrated on a single chip, as shown by the dashed line (1405) in Figure 14. In other words, the baseband processor 1403 and the application processor 1404 may be implemented as a single System on Chip (SoC) device 1405. An SoC device may also be called a system Large Scale Integration (LSI) or a chipset.

[0090] The memory 1406 is a volatile memory or a non-volatile memory, or a combination thereof. The memory 1406 may include a plurality of physically independent memory devices. The volatile memory is, for example, a Static Random Access Memory (SRAM) or a Dynamic RAM (DRAM), or a combination thereof. The non-volatile memory is a Mask Read Only Memory (MROM), an Electrically Erasable Programmable ROM (EEPROM), a flash memory, or a hard disk drive, or any combination thereof. For example, the memory 1406 may include an external memory device accessible from the baseband processor 1403, the application processor 1404, and the SoC 1405. The memory 1406 may include an internal memory device integrated in the baseband processor 1403, the application processor 1404, or the SoC 1405. Furthermore, the memory 1406 may include a memory in a Universal Integrated Circuit Card (UICC).

[0091] The memory 1406 may store one or more software modules (computer programs) 1407 including instructions and data for performing the processes by the UE 1 described in the above embodiments. In some implementations, the baseband processor 1403 or the application processor 1404 may be configured to read the software modules 1407 from the memory 1406 and execute them to perform the processes by the UE 1 described in the above embodiments using the drawings.

[0092] In addition, the control plane processing and operations performed by UE1 described in the above embodiment can be realized by elements other than the RF transceiver 1401 and the antenna array 1402, i.e., at least one of the baseband processor 1403 and the application processor 1404, and the memory 1406 storing the software module 1407.

[0093] FIG. 15 shows an example of the configuration of the AMF2. The SMF3 may also have the configuration shown in FIG. 15. Referring to FIG. 15, the AMF2 includes a network interface 1501, a processor 1502, and a memory 1503. The network interface 1501 is used, for example, to communicate with (R)AN nodes and to communicate with other network functions (NFs) or nodes in the 5GC. The other NFs or nodes in the 5GC include, for example, UDM, AUSF, SMF, and PCF. The network interface 1501 may include, for example, a network interface card (NIC) conforming to the IEEE 802.3 series.

[0094] The processor 1502 may be, for example, a microprocessor, a Micro Processing Unit (MPU), or a Central Processing Unit (CPU). The processor 1502 may include multiple processors.

[0095] The memory 1503 is composed of a volatile memory and a non-volatile memory. The memory 1503 may include a plurality of physically independent memory devices. The volatile memory is, for example, a static random access memory (SRAM) or a dynamic RAM (DRAM), or a combination thereof. The non-volatile memory is, for example, a mask read only memory (MROM), an electrically erasable programmable ROM (EEPROM), a flash memory, or a hard disk drive, or any combination thereof. The memory 1503 may include a storage located away from the processor 1502. In this case, the processor 1502 may access the memory 1503 via the network interface 1501 or an I / O interface.

[0096] The memory 1503 may store at least one software module (computer program) 1504 including instructions and data for performing processing by the AMF2 described in the above-mentioned aspects. In some implementations, the processor 1502 may be configured to read the software module 1504 from the memory 1503 and execute it to perform processing by the AMF2 described in the above-mentioned aspects.

[0097] As described with reference to FIG. 14 and FIG. 15, each of the processors included in the UE1, AMF2, and SMF3 according to the above-mentioned embodiment executes one or more programs including instructions for making a computer execute the algorithm described with reference to the drawings. The program can be stored and provided to a computer using various types of non-transitory computer readable media. The non-transitory computer readable media includes various types of tangible storage media. Examples of the non-transitory computer readable media include magnetic recording media (e.g., flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), Compact Disc Read Only Memory (CD-ROM), CD-R, CD-R / W, and semiconductor memory (e.g., mask ROM, programmable ROM (PROM), erasable PROM (EPROM), flash ROM, random access memory (RAM)). The program may also be provided to a computer by various types of transitory computer readable media. Examples of the temporary computer-readable medium include an electric signal, an optical signal, and an electromagnetic wave. The temporary computer-readable medium can provide the program to the computer via a wired communication path such as an electric wire or an optical fiber, or a wireless communication path.

[0098] The above-described embodiments are merely examples of application of the technical ideas obtained by the inventors of the present invention. In other words, the technical ideas are not limited to the above-described embodiments, and various modifications can be made to these.

[0099] A part or all of the above-described embodiments can be described as, but is not limited to, the following supplementary notes.

[0100] (Appendix A1) A core network node for mobility management, At least one memory; at least one processor coupled to the at least one memory; Equipped with The at least one processor is configured to, in response to updating the restriction on the use of the network slice, request a core network node for session management to release an established PDU Session associated with the network slice or to deactivate user plane resources of the established PDU Session. A core network node for mobility management. (Appendix A2) The restriction includes at least one of a restriction on a radio frequency on which the network slice can be used, a restriction on a radio access technology on which the network slice can be used, a restriction on a geographical area on which the network slice can be used, a restriction on an application on which the network slice can be used, and a restriction based on a priority among multiple network slices. A core network node for mobility management as described in Appendix A1. (Appendix A3) 1. A method performed by a core network node for mobility management, comprising: In response to updating restrictions on the use of the network slice, requesting a core network node for session management to release an established PDU Session associated with the network slice or to deactivate user plane resources of the established PDU Session. method. (Appendix B1) A core network node for mobility management, At least one memory; at least one processor coupled to the at least one memory; Equipped with The at least one processor: receiving a first Non-Access Stratum (NAS) message including a Session Management (SM) message requesting establishment of a PDU Session from a User Equipment (UE); Determining whether a usage restriction is imposed or needs to be imposed on a network slice identifier associated with the PDU Session; If the usage restriction is imposed or needs to be imposed on the network slice identifier, stop forwarding the SM message to a core network node for session management and reject the NAS message; The usage restriction includes at least one of a restriction on a radio frequency on which the network slice can be used, a restriction on a radio access technology on which the network slice can be used, a restriction on a geographical area on which the network slice can be used, a restriction on an application on which the network slice can be used, and a restriction based on a priority among multiple network slices. A core network node for mobility management. (Appendix B2) The at least one processor stops forwarding the SM message to the core network node for session management and rejects the NAS message if the UE does not indicate support for network slice restriction and the usage restriction is imposed on the network slice identifier. A core network node for mobility management as described in Appendix B1. (Appendix B3) The at least one processor is configured to send a second NAS message to the UE, the second NAS message including a cause value indicating that the SM message is not forwarded due to the usage restriction. A core network node for mobility management according to appendix B1 or B2. (Appendix B4) the at least one processor is configured to receive information indicative of the usage restriction from another network function. A core network node for mobility management according to any one of appendices B1 to B3. (Appendix B5) 1. A method performed by a core network node for mobility management, comprising: receiving a first Non-Access Stratum (NAS) message from a User Equipment (UE), the NAS message including a Session Management (SM) message requesting establishment of a PDU Session; Determining whether a usage restriction is imposed or needs to be imposed on a network slice identifier associated with the PDU Session; and If the usage restriction is imposed or needs to be imposed on the network slice identifier, stopping forwarding the SM message to a core network node for session management and rejecting the NAS message; Equipped with The usage restriction includes at least one of a restriction on a radio frequency on which the network slice can be used, a restriction on a radio access technology on which the network slice can be used, a restriction on a geographical area on which the network slice can be used, a restriction on an application on which the network slice can be used, and a restriction based on a priority among multiple network slices. method. (Appendix B6) A program for causing a computer to perform a method for a core network node for mobility management, the method comprising: receiving a first Non-Access Stratum (NAS) message from a User Equipment (UE), the NAS message including a Session Management (SM) message requesting establishment of a PDU Session; Determining whether a usage restriction is imposed or needs to be imposed on a network slice identifier associated with the PDU Session; and If the usage restriction is imposed or needs to be imposed on the network slice identifier, stopping forwarding the SM message to a core network node for session management and rejecting the NAS message; Equipped with The usage restriction includes at least one of a restriction on a radio frequency on which the network slice can be used, a restriction on a radio access technology on which the network slice can be used, a restriction on a geographical area on which the network slice can be used, a restriction on an application on which the network slice can be used, and a restriction based on a priority among multiple network slices. program. (Appendix C1) A core network node for mobility management, At least one memory; at least one processor coupled to the at least one memory; Equipped with The at least one processor: Receive a Non-Access Stratum (NAS) message including a Session Management (SM) message requesting establishment of a PDU Session from a User Equipment (UE); Determining whether a usage restriction is imposed or needs to be imposed on a network slice identifier associated with the PDU Session; If the usage restriction is imposed or needs to be imposed on the network slice identifier, forward the SM message to a core network node for session management together with an indication that establishment of the PDU Session should be rejected due to the usage restriction. It is configured as follows: The usage restriction includes at least one of a restriction on a radio frequency on which the network slice can be used, a restriction on a radio access technology on which the network slice can be used, a restriction on a geographical area on which the network slice can be used, a restriction on an application on which the network slice can be used, and a restriction based on a priority among multiple network slices. A core network node for mobility management. (Appendix C2) the at least one processor is configured to receive information indicative of the usage restriction from another network function. A core network node for mobility management as described in Appendix C1. (Appendix C3) A core network node for session management, At least one memory; at least one processor coupled to the at least one memory; Equipped with The at least one processor: receiving a control message including a first Session Management (SM) message requesting establishment of a PDU Session for User Equipment (UE) from a core network node for mobility management; If the control message includes an indication that the establishment of the PDU Session should be rejected due to usage restrictions, reject the establishment of the PDU Session. It is configured as follows: The usage restriction includes at least one of a restriction on a radio frequency on which the network slice can be used, a restriction on a radio access technology on which the network slice can be used, a restriction on a geographical area on which the network slice can be used, a restriction on an application on which the network slice can be used, and a restriction based on a priority among multiple network slices. A core network node for session management. (Appendix C4) The at least one processor is configured to send, to the UE via the core network node for mobility management, a second SM message including a cause value indicating that establishment of the PDU Session is rejected due to the usage restriction. A core network node for session management as described in Appendix C3. (Appendix C5) 1. A method performed by a core network node for mobility management, comprising: receiving a Non-Access Stratum (NAS) message including a Session Management (SM) message requesting establishment of a PDU Session from a User Equipment (UE); Determining whether a usage restriction is imposed or needs to be imposed on a network slice identifier associated with the PDU Session; and forwarding the SM message to a core network node for session management together with an indication that establishment of the PDU Session should be rejected due to the usage restriction, if the usage restriction is imposed or needs to be imposed on the network slice identifier; Equipped with The usage restriction includes at least one of a restriction on a radio frequency on which the network slice can be used, a restriction on a radio access technology on which the network slice can be used, a restriction on a geographical area on which the network slice can be used, a restriction on an application on which the network slice can be used, and a restriction based on a priority among multiple network slices. method. (Appendix C6) 1. A method performed by a core network node for session management, comprising: receiving a control message from a core network node for mobility management, the control message including a first Session Management (SM) message requesting establishment of a PDU Session for a User Equipment (UE); and rejecting the establishment of the PDU Session if the control message includes an indication that the establishment of the PDU Session should be rejected due to usage restrictions; Equipped with The usage restriction includes at least one of a restriction on a radio frequency on which the network slice can be used, a restriction on a radio access technology on which the network slice can be used, a restriction on a geographical area on which the network slice can be used, a restriction on an application on which the network slice can be used, and a restriction based on a priority among multiple network slices. method.

[0101] (Appendix 1) A core network node for session management, At least one memory; at least one processor coupled to the at least one memory; Equipped with The at least one processor: Receive a report from a core network node for mobility management indicating that an update to a restriction on the use of the network slice by the User Equipment (UE) has occurred; In response to receiving the report, control a release or modification of an established PDU Session of the UE associated with the network slice. A core network node for session management. (Appendix 2) The at least one processor is configured to initiate a release of the established PDU Session or a deactivation of user plane resources of the established PDU Session if the report indicates that there is a restriction on the use of the network slice. A core network node for session management as described in Supplementary Note 1. (Appendix 3) The at least one processor is configured to reject the modification of the established PDU session requested by the UE if the report indicates that there is a restriction on the use of the network slice. 3. A core network node for session management according to claim 1 or 2. (Appendix 4) The report includes information indicating whether restrictions on use of the network slice are activated, deactivated, or unknown; The at least one processor is configured to control a release or modification of the established PDU Session associated with the network slice when the information indicates that the restriction is activated. A core network node for session management according to any one of Supplementary Notes 1 to 3. (Appendix 5) The at least one processor: Sending a request to the core network node for mobility management to subscribe to a notification service regarding restrictions on the use of the network slice by the UE; receiving a report corresponding to the request; A core network node for session management according to any one of supplements 1 to 4. (Appendix 6) A core network node for mobility management, At least one memory; at least one processor coupled to the at least one memory; Equipped with The at least one processor is configured to, in response to updating a restriction on use of the network slice by a User Equipment (UE), send a report indicating that the restriction update has occurred to a core network node for session management. A core network node for mobility management. (Appendix 7) The restriction includes at least one of a restriction on a radio frequency on which the network slice can be used, a restriction on a radio access technology on which the network slice can be used, a restriction on a geographical area on which the network slice can be used, a restriction on an application on which the network slice can be used, and a restriction based on a priority among multiple network slices. A core network node for mobility management as described in Supplementary Note 6. (Appendix 8) The report includes information indicating whether restrictions on the use of the network slice are activated, deactivated, or unknown. 8. A core network node for mobility management according to claim 6 or 7. (Appendix 9) The at least one processor: receiving a request for subscription to a notification service regarding restrictions on the use of the network slice by the UE from the core network node for session management; and transmitting a report corresponding to the request to the core network node for session management. A core network node for mobility management according to any one of Supplementary Notes 6 to 8. (Appendix 10) 1. A method performed by a core network node for session management, comprising: Receiving a report from a core network node for mobility management indicating that an update to a restriction on the use of the network slice by a User Equipment (UE) has occurred; and In response to receiving the report, controlling a release or modification of an established PDU Session of the UE associated with the network slice; A method for providing the above. (Appendix 11) 1. A method performed by a core network node for mobility management, comprising: In response to updating a restriction on use of the network slice by a User Equipment (UE), sending a report to a core network node for session management indicating that the restriction update has occurred. method. (Appendix 12) 1. A program for causing a computer to perform a method for a core network node for session management, the method comprising: Receiving a report from a core network node for mobility management indicating that an update to a restriction on the use of the network slice by a User Equipment (UE) has occurred; and In response to receiving the report, controlling a release or modification of an established PDU Session of the UE associated with the network slice; A program that includes: (Appendix 13) A program for causing a computer to perform a method for a core network node for mobility management, comprising: The method includes, in response to updating a restriction on use of a network slice by a User Equipment (UE), sending a report to a core network node for session management indicating that the restriction update has occurred. program.

[0102] This application claims priority based on Japanese Patent Application No. 2020-174588, filed on October 16, 2020, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0103] 1 UE 2 AMF 3 SMF 4. NSSF 5 A N 6 UPF 7DN 8 UDM 1403 Baseband Processor 1404 Application Processor 1406 Memory 1407 Modules 1502 Processor 1503 Memory 1504 Modules

Claims

1. A first core network node, means for receiving a first message from a second core network node when the user equipment moves into an area that is not associated with a Single Network Slice Selection Assistance Information (S-NSSAI) that identifies a network slice; means for deactivating an established session with respect to said user equipment; and means for transmitting a second message to the user equipment via the second core network node when initiating release of the established session.

2. The first core network node of claim 1 , wherein the session is established for the user equipment associated with the S-NSSAI.

3. The first message further includes an identifier of the user equipment. A first core network node according to claim 1 or 2.

4. The area comprises a tracking area or a cell. A first core network node according to any one of claims 1 to 3.

5. the session comprises a Protocol Data Unit (PDU) session. A first core network node according to any one of claims 1 to 4.

6. The first message includes a Namf_EventExposure Service. A first core network node according to any one of claims 1 to 5.

7. the second message includes a PDU Session Release Command; A first core network node according to any preceding claim.

8. The first core network node performs session management. A first core network node according to any preceding claim.

9. The second core network node performs mobility management. A first core network node according to any preceding claim.

10. A method of a first core network node, comprising: receiving a first message from a second core network node when the user equipment moves into an area that is not associated with a Single Network Slice Selection Assistance Information (S-NSSAI) that identifies a network slice; deactivating an established session with respect to the user equipment; sending a second message to the user equipment via the second core network node when initiating release of the established session.

11. The method of claim 10 , wherein the session is established for the user equipment associated with the S-NSSAI.

12. The first message further includes an identifier of the user equipment.

12. The method according to claim 10 or 11.

13. The area comprises a tracking area or a cell.

13. A method according to any one of claims 10 to 12.

14. the session comprises a Protocol Data Unit (PDU) session. A method according to any one of claims 10 to 13.

15. The first message includes a Namf_EventExposure Service.

15. The method according to any one of claims 10 to 14.

16. the second message includes a PDU Session Release Command; 16. The method according to any one of claims 10 to 15.

17. The first core network node performs session management.

17. A method according to any one of claims 10 to 16.

18. The second core network node performs mobility management.

18. A method according to any one of claims 10 to 17.

Images