Communication terminal, core network node, and method

Abstract

To provide a communication terminal and a core network that handle service access to isolated network slices, enabling separation between network slices and improving 5G security and data exchange integrity.SOLUTION: In a communication system 1, users of mobile devices 3 communicate with each other and other users via respective base stations 5 and a core network 7 using E-UTRA and / or 5G RAT. Each of the base stations 5 controls one or more associated cells. The core network 7 includes a control plane function (CPF) and a user plane function (UPF).SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] This disclosure relates to a communication system. Although this disclosure is not limited to wireless communication systems and their devices operating according to 3rd Generation Partnership Project (3GPP) standards or their equivalents or derivatives, it has a specific relevance. This disclosure is particularly relevant, although not exclusive, to on-demand registration in response to requirements for disjoint network slices in so-called "5G" (or "next-generation") systems.

Background Art

[0002] The network slicing functions defined in 3GPP Release 15 and Release 16 enable a variety of communication services for communication carriers and industries. To enhance the commercialization potential of network slicing, GSMA 5GJA introduced the concept of a Generic Slice Template (GST) in document NG.116 (Non-Patent Document 6) from which descriptions of various network slice types can be derived. Some parameters of the GST explicitly show the boundary definition with the parameters of the services provided to end-customers. However, some of these parameter and boundary enforcements are not yet supported in 5GS.

[0003] In the 3GPP SA1 study on extended access and support for network slices in Rel-18 (Non-Patent Document 4), various use cases and scenarios using network slices, such as the following, are being considered to identify potential service requirements for 5G systems. - When there are restrictions on network slices for specific frequency bands / sub-bands, radio access technologies (RATs), geographical areas, networks, and applications. -When a UE has subscriptions to multiple network slices, and these network slices are deployed for different frequency bands / subbands, RATs, geographical areas, and applications. - For example, when there are conflicting constraints regarding the availability of network slices, and one network slice takes precedence over another. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 3GPP TR 21.905: "Vocabulary for 3GPP Specifications" V16.0.0 (2019-06) - https: / / www.3gpp.org / ftp / / Specs / archive / 21_series / 21.905 / 21905-g00.zip [Non-Patent Document 2] 3GPP TS 23.501: "System Architecture for the 5G System (5GS)" V16.7.0 (2020-12) - http: / / www.3gpp.org / ftp / Specs / archive / 23_series / 23.501 / 23501-g70.zip [Non-Patent Document 3] 3GPP TS 23.502: "Procedures for the 5G System (5GS)" V16.7.0 (2020-12) - http: / / www.3gpp.org / ftp / Specs / archive / 23_series / 23.502 / 23502-g70.zip [Non-Patent Document 4] 3GPP TR 22.835: "Study on Enhanced Access to and Support of Network Slices" V0.2.0 (2020-11) - http: / / www.3gpp.org / ftp / Specs / archive / 22_series / 22.835 / 22835-020.zip [Non-Patent Document 5] 3GPP TR 23.700-40: “Study on Enhancement of Network Slicing Phase 2” V1.2.0 (2020-11) - http: / / www.3gpp.org / ftp / tsg_sa / WG2_Arch / Latest_SA2_Specs / Latest_draft_S2_Specs / 23700-40-120.zip [Non-Patent Document 6] GSM Association Official Document NG.116: “Generic Network Slice Template” V2.0 (2019-10) - https: / / www.gsma.com / newsroom / wp-content / uploads / NG.116-v2.0.pdf [Non-Patent Document 7] 3GPP TS 38.413: "NG-RAN; NG Application Protocol (NGAP)" V16.3.0 (2020-09) - https: / / www.3gpp.org / ftp / / Specs / archive / 38_series / 38.413 / 38413-g30.zip [Overview of the project] [Problems that the invention aims to solve]

[0005] As more network slices are deployed, each UE may subscribe to multiple network slices. Some network slice services may be available to UEs simultaneously, while others may not be available to UEs at the same time. This is because network slices have multiple associated factors, such as enterprise vs. personal use, isolation requirements, public vs. public safety use, frequency restrictions, and location restrictions.

[0006] Figure 1 schematically illustrates an example of a disjointed network slice. Specifically, Figure 1 shows a use case scenario in which a (R)AN node connects to slice M, provided via a core network node for access and mobility management (e.g., AMF Y), and to slice N, provided by another core network node for access and mobility management of the same PLMN (e.g., AMF X). For example, slice M is used for public security and slice N is used for internet access. In the core network (e.g., 5GC), dedicated network resources and network functions are individually customized for public security emergency services and video services to meet isolation requirements. This ensures the independence of core network resources between different network slices. Thus, the two network slices are disjointed and cannot be provided to the UE simultaneously. Such network slices are called disjointed network slices.

[0007] Registration (subscription) and configuration: -UE A1 and A3 have registration in slice M. -UE A2 and A3 have registrations to slice N. -UE A3 configures which application uses which network slice.

[0008] Deployment: - Slice N and slice M are separated. -(R)AN can be connected to both slice M and slice N. -Slices M and N are supplied by the same PLMN. Problem to be solved: Telecommunication systems (e.g., 5GS) lack a mechanism to prevent a UE subscribed to multiple network slices that are not provided to the UE simultaneously (e.g., separate network slices) from accessing those multiple network slices at the same time.

[0009] To meet this requirement, telecommunications systems (e.g., 5G systems) must be able to do the following: - Provides network slices optimized for the UE (e.g., based on ongoing applications and user preferences). - Supports changes to the provided network slice with minimal disruption (for example, when triggered by changes in the active application or priority). [Means for solving the problem]

[0010] In one respect, the communication terminal (3) Means for sending a first Non-Access Stratum (NAS) message to a core network node (10A) including first information indicating that the communication terminal (3) supports an on-demand registration function, and second information indicating a list of network slices for which the communication terminal (3) requests registration, Means for receiving a second NAS message from the core network node (10A) including third information indicating a first network slice used by the communication terminal (3) in the Public Land Mobile Network (PLMN), and fourth information indicating a second network slice to which the communication terminal (3) is subscribed and which is supported by the PLMN, but which is not supported by the core network node (10A) to which the communication terminal (3) is registered, The system includes means for triggering on-demand registration to the second network slice, The first network slice and the second network slice are included in the list.

[0011] In one respect, the core network node (10A) A means for receiving a first Non-Access Stratum (NAS) message from the communication terminal (3), which includes first information indicating that the communication terminal (3) supports an on-demand registration function, and second information indicating a list of network slices for which the communication terminal (3) requests registration. When the first NAS message is received, means for generating fourth information indicating a second network slice to which the communication terminal (3) is subscribed and which is supported by the Public Land Mobile Network (PLMN), but which is not supported by the core network node (10A) to which the communication terminal (3) is registered; The PLMN includes means for sending a second NAS message to the communication terminal (3) that includes a third piece of information indicating a first network slice used by the communication terminal (3), and the fourth piece of information, The first network slice and the second network slice are included in the list.

[0012] In one respect, the method of the communication terminal (3) is, A process of sending a first Non-Access Stratum (NAS) message to a core network node (10A) including first information indicating that the communication terminal (3) supports an on-demand registration function, and second information indicating a list of network slices for which the communication terminal (3) requests registration; A process of receiving, from the core network node (10A), a second NAS message including third information indicating a first network slice used by the communication terminal (3) in a Public land mobile network (PLMN), and fourth information indicating a second network slice that the communication terminal (3) subscribes to and is supported by the PLMN but not supported by the core network node (10A) where the communication terminal (3) is registered. A process of triggering an on-demand registration to the second network slice is executed. The first network slice and the second network slice are included in the list.

[0013] In one aspect, a method of a core network node (10A) includes: A process of receiving, from the communication terminal (3), a first Non-Access Stratum (NAS) message including first information indicating that the communication terminal (3) supports an on-demand registration function, and second information indicating a list of network slices for which the communication terminal (3) requests registration; When the first NAS message is received, a process of generating fourth information indicating a second network slice that the communication terminal (3) subscribes to and is supported by the Public land mobile network (PLMN) but not supported by the core network node (10A) where the communication terminal (3) is registered; A process of transmitting, to the communication terminal (3), a second NAS message including third information indicating a first network slice used by the communication terminal (3) in the PLMN and the fourth information; The first network slice and the second network slice are included in the list.

Advantages of the Invention

[0014] This disclosure proposes on-demand registration for network slices that are not registered by the UE. This allows the UE to access services on isolated network slices via on-demand registration if the UE or an application on the UE requires access to those isolated network slices. This improves 5G security and data exchange integrity by maintaining isolation between isolated network slices. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 schematically shows an example of a separated network slice. [Figure 2] Figure 2 is a schematic timing (signaling) diagram illustrating an exemplary method for initial registration of a UE. [Figure 3] Figure 3 shows that Solution 1 proposes "on-demand registration" for isolated network slices (e.g., isolated network slice S-NSSAI_N). [Figure 4] Figure 4 shows that Solution 2 proposes "on-demand registration" for isolated network slices by rerouting to an AMF10 that supports in-demand S-NSSAI (e.g., isolated network slices). [Figure 5] Figure 5 schematically shows a mobile (cellular or wireless) telecommunications system 1 to which the above embodiment can be applied. [Figure 6] Figure 6 is a block diagram showing the main components of the UE (Mobile Device 3) shown in Figure 5. [Figure 7] Figure 7 is a block diagram showing the main components of the exemplary (R)AN node 5 (base station) shown in Figure 5. [Figure 8] Figure 8 is a block diagram showing the main components of a typical core network node (or function) as shown in Figure 5, such as AMF10, PCF13, UDM / UDR15, and NSSF17. [Modes for carrying out the invention]

[0016] Abbreviation 3GPP 3rd Generation Partnership Project 5G 5th Generation 5GC 5G Core Network 5GS 5G System 5G-AN 5G Access Network AF Application Function AMF Access and Mobility Management Function ASApplication Server AUSF Authentication Server Function CAG Closed Access Group CST Generic Network Slice Template GSMA Global System for Mobile Communications GUAMI Globally Unique AMF Identifier gNB Next generation Node B GST Generic Slice Template MM Mobility Management MNO Mobile Network Operator NAS Non-Access Stratum NF Network Function NG-RAN Next Generation Radio Access Network NID Network identifier NPN Non-Public Network NR New Radio NSSAI Network Slice Selection Assistance Information NSSF Network Slice Selection Function PCC Policy and Charging Control PCF Policy Control Function PDU Protocol Data Unit PLMN Public land mobile network PNI-NPN Public Network Integrated NPN (R)AN (Radio) Access Network RAT Radio Access Technology RRC Radio Resource Control SAE System Architecture Evolution SNPN Stand-alone Non-Public Network S-NSSAI Single Network Slice Selection Assistance Information S-TMSI SAE-Temporary Mobile Subscriber Identity UDM Unified Data Management UDR Unified Data Repository UE User Equipment URSP UE Route Selection Policy

[0017] Definition For the purposes of this document, the terms and definitions set forth in 3GPP Technical Report (TR) 21.905 (Non-Patent Literature 1) and below shall apply. Terms defined herein shall take precedence over those defined in 3GPP TR 21.905 (Non-Patent Literature 1) if the same terms are defined therein.

[0018] Common aspects - Applicability of aspects All disclosures in this embodiment are applicable not only to network slice processing within a PLMN, but also to network slice switching between one network slice in a PLMN and another network slice in a non-public network (NPN). Furthermore, all disclosures in this embodiment are applicable to network slice processing within an NPN. The NPN may be either a standalone non-public network (SNPN) or a public network integrated NPN (PNI-NPN).

[0019] - New definition The following new definition is proposed. -Available NSSAI (or other notation for network slices conforming to the definition below) - A list of one or more network slices (e.g., S-NSSAI) that UE3 has joined and is supported by PLMN, but is not supported in the current AMF10 to which UE3 is registered. Members of "Available NSSAI" are called available network slices (e.g., available S-NSSAI). The list of available network slices may be generated based on interaction with operator policies and / or settings to identify network slices that UE3 has registered but has not registered or could not register, but is supported by PLMN. The list of available network slices may be provided to UE3 as an "Available NSSAI" parameter during the registration procedure (e.g., Registration Accept message), or via a UE configuration update procedure within a UE policy parameter (e.g., as part of a UE Route Selection Policy (URSP) parameter), or as a separate parameter. For example, in addition to the registration procedure or UE Configuration Update procedure, the list of available network slices can be provided in an existing or new NAS message during a NAS procedure (e.g., a Service Request procedure), or in an existing AS (Access Stratum) message (e.g., an RRC SETUP message or RRC It can also be provided using a Reconfiguration Request message or an RRC Release message. There may be different NSSAIs available for each access type: one for 3GPP access and another for non-3GPP access.For example, available NSSAIs may be provided per PLMN or per registration area where UE3 is registered during the registration procedure. If UE3 needs to switch network slices between network slices in a PLMN and network slices in a PNI-NPN, or if it needs to switch network slices within an NPN, the term “network slice” in this disclosure may be interpreted as “Closed Access Group (CAG)” or a combination of “CAG” and “network slice” or “Network Identifier (NID)”.

[0020] The available NSSAI may take on different definitions. Several possible definitions are listed below. One or more network slices (such as S-NSSAI) that are supported by PLMN and are also listed in NSSAI for UE3. One or more network slices (such as S-NSSAI) that are supported in the PLMN registration area and are also listed in the NSSAI that have joined UE3. One or more network slices (such as S-NSSAI) that are supported by PLMN and also listed in the configured NSSAIs for UE3. One or more network slices (such as S-NSSAI) that are supported in the PLMN registration area and are also listed in the configured NSSAIs for UE3. The result of subtracting one or more network slices listed in the permitted NSSAI from one or more network slices (such as S-NSSAI) that are supported by PLMN and listed in the UE3 enrolled NSSAI. The number of network slices supported in the PLMN registration area and listed in the UE3 enrolled NSSAI (such as S-NSSAI), minus the number of network slices listed in the permitted NSSAI. The result of subtracting one or more network slices listed in the permitted NSSAI from one or more network slices (such as S-NSSAI) that are supported by PLMN and also listed in the configured NSSAI in UE3. The difference between one or more network slices listed in the permitted NSSAI and one or more network slices (such as S-NSSAI) that are supported in the PLMN registration area and also listed in the configured NSSAI in UE3.

[0021] -On-demand registration (or other notation for the procedure conforming to the definition below)- Registration by UE3 to an available network slice (such as an available S-NSSAI(s)). An example of such an available network slice is an isolated network slice that UE3 could not initially register because it is not supported at the same time. When an application on UE3 requests access to one or more available network slices (e.g., an available S-NSSAI), i.e., a network slice that UE3 is not registered with but UE3 is enrolled in and supported by PLMN, UE3 triggers on-demand registration.

[0022] -On-Demand Registration Support Indicator (or other notation for information conforming to the definition below)- UE3 that supports "On-Demand Registration" indicates the "On-Demand Registration Support" indicator at registration (for example, in a Registration Request message) so that the network returns a list of available network slices (e.g., available S-NSSAI, etc.) if such a list exists.

[0023] - Indemnity NSSAI (or other notation for network slices that conforms to the following definition): A list of one or more network slices (such as S-NSSAI) that trigger UE3 to perform on-demand registration, PDU session establishment requests, or service requests. The "In demand NSSAI" parameter member is invoked in an in-demand network slice (e.g., In-demand S-NSSAI) and provided to the network during registration (e.g., in a Registration Request message) or during a UE configuration update procedure. One example of an in-demand network slice is an isolated network slice that UE3 previously could not register because it did not support isolated network slices simultaneously.

[0024] Initial registration by providing a list of available network slices to UE3 The following example of initial UE registration outlines the preparation steps for the proposed new solution.

[0025] Figure 2 is a schematic timing (signaling) diagram illustrating an exemplary method for initial UE registration. UE3 joins network slices S-NSSAI_M and S-NSSAI_N and camps in a cell that supports both network slices S-NSSAI_M and S-NSSAI_N. UE3 requests registration on both network slices, but the two requested network slices S-NSSAI_M and S-NSSAI_N are separate network slices supported by different AMF10s at the UE's location (e.g., AMF_1 10A supports S-NSSAI_M and AMF_2 10B supports S-NSSAI_N). If UE3 indicates "Support for On-Demand Registration" in its Registration Request message, the separate network slice S-NSSAI_N is returned to UE3 as an available network slice supported by another AMF10 at the UE's location (e.g., AMF_2 10B).

[0026] 1) UE3 triggers initial registration to the network (for example, this step starts when UE3 is switched on).

[0027] 2) UE3 sends an RRC Connection Setup Complete message (Requested NSSAI = S-NSSAI_M, S-NSSAI_N, NAS message = Registration Request ("On-Demand Registration Function Support" indicator, Requested NSSAI = S-NSSAI_M, S-NSSAI_N)). UE3 first triggers the RRC connection establishment procedure with (R)AN node 5, and UE3 includes S-NSSAI_M and S-NSSAI_N in the Requested NSSAI parameters of the RRC Connection Setup Complete message, and UE3 also includes a Registration Request message in the RRC Connection Setup Complete message in accordance with TS23.502 (Non-Patent Literature 3). In the Registration Request message, UE3 includes an "On-Demand Registration Support" indicator indicating that UE3 supports the "On-Demand Registration" function (e.g., registration to an isolated network slice).

[0028] 3) If (R)AN node 5 cannot find an AMF10 that supports both S-NSSAI_M and S-NSSAI_N, (R)AN node 5 selects AMF_1 10A that supports only S-NSSAI_M.

[0029] 4) (R) AN node 5 sends the UE initial message (NAS message = Registration Request ("on demand registration feature support" indicator, Requested NSSAI = S-NSSAI_M, S-NSSAI_N)) to the selected AMF_1 10A. (R) AN node 5 forwards the Registration Request message from UE3 to the selected AMF_1 10A.

[0030] 5) Continue the registration procedure with AMF_1 10A in accordance with 3GPP Technical Specification (TS) 23.502 (Non-Patent Literature 3).

[0031] 6) If UE3 indicates "Support for On-Demand Enrollment," AMF_1 10A checks the availability of network slices in (R)AN node 5 / NSSF17 / PCF13 / UDM / UDR15 / operator policy or configuration, and AMF_1 10A generates a list of available network slices (e.g., available NSSAI).

[0032] AMF_1 10A may retrieve a list of UE-subscribed network slices from UDM / UDR15, and AMF_1 10A may check NSSF17 to see which of these UE-subscribed network slices are not supported by PLMN, and UE3 may check PCF13 for access restrictions on network slices based on various criteria by PCC rules within PCF13 (e.g., access restrictions on network slices based on location or time, or restrictions per specific UE3, or access restrictions based on other criteria). UDM / UDR15 may provide additional network slice information for each subscribed network slice, for both subscribed and isolated network slices.

[0033] (R)AN node 5 may also provide AMF_1 10A with information to generate a list of available network slices (e.g., available NSSAIs). For example, AMF_1 10A may obtain from (R)AN node 5 information about the S-NSSAIs supported by each neighboring AMF 10. Each (R)AN node 5 connected to AMF_1 10A may provide in the NG SETUP REQUEST message the combination of the S-NSSAI and the associated AMF 10, the RAN CONFIGURATION UPDATE ACKNOWLEDGE message or AMF CONFIGURATION UPDATE message as defined in 3GPP TS38.413 (Non-Patent Literature 7), or any other name for the message between (R)AN node 5 and AMF 10.

[0034] AMF_1 10A may also consider other access restrictions on the network slice based on the operator's policies or settings.

[0035] Based on these interactions with UDM / UDR15, NSSF17, PCF13, (R)AN node 5 and / or operator policies and / or settings, AMF_1 10A generates a list of network slices (e.g., available NSSAI) referred to as available network slices. Therefore, the available network slices are: -Supported in PLMN or the registration area within PLMN, - You have a valid UE subscription, -This registration procedure does not provide the network slice to UE3 as an authorized network slice. This list of available network slices (e.g., available NSSAIs) may include isolated network slices that UE3 has requested to register but are not allowed to register because they are isolated network slices, even though they are supported within the PLMN or registration area, and are not supported by the AMF10 (e.g., AMF_1 10A) that UE3 registers.

[0036] The list of available network slices (e.g., available NSSAIs) may also include network slices for which UE3 has a valid subscription, even though UE3 has not requested registration. Depending on the reason for rejection, the list of available network slices (e.g., available NSSAIs) may also include network slices that are included in the list of rejected network slices (e.g., network slices rejected because they are not supported in the current AMF10, but are supported in other AMF10s within PLMN, i.e., isolated network slices).

[0037] 7) If UE3 indicates "support for on-demand registration" in the Registration Request message and the requested S-NSSAI_N is supported by another AMF10 (e.g., AMF_2 10B), then AMF_1 10A will include S-NSSAI_N in the list of available network slices (e.g., in the "Available NSSAI" parameter of the Registration Accept message to UE3).

[0038] 8) AMF_1 10A sends a Registration Accept message (Allowed NSSAI=S-NSSAI_M, Available NSSAI=S-NSSAI_N) to UE3. AMF_1 10A confirms the registration of NSSAI_M by including NSSAI_M in the Allowed NSSAI parameter, and AMF_1 10A also returns S-NSSAI_N (the currently available S-NSSAI) in the Available NSSAI parameter. Alternatively, the available S-NSSAI_N may be provided to UE3 along with additional differentiated tags (e.g., information, indicator, or parameter) in existing parameters such as Allowed NSSAI or Rejected NSSAI, or any other existing parameters in the Registration Accept message. This allows UE3 to distinguish S-NSSAI_N from other network slices.

[0039] 9) UE3 successfully registers S-NSSAI_M and receives S-NSSAI_N as an available S-NSSAI. If a service on such an S-NSSAI is required by an application on UE or UE3, or if UE3 receives a paging message instructing UE3 to request activation of a service on such an S-NSSAI, UE3 can trigger an "on-demand registration," a PDU session establishment request, or a service request for an available S-NSSAI (e.g., isolated S-NSSAI_N).

[0040] Alternatively, UE3 can predict, determine, or generate which network slices are eligible as available S-NSSAI by subtracting authorized S-NSSAIs from the list of joined S-NSSAIs, independently of the network. However, in this case, the likelihood of "on-demand registration," PDU session establishment requests, or service requests being rejected increases because, without network assistance, the UE cannot obtain complete information about the availability of network slices.

[0041] For example, in the case of UE3 which does not support the "On-Demand Registration" feature, AMF_1 10A does not support S-NSSAI_N, but can set S-NSSAI_N to an authorized NSSAI in the Registration Accept message. This can occur if UE3 does not include the "On-Demand Registration Support" directive in the Registration Request message, and AMF_1 10A is aware that UE3 can access S-NSSAI_N using another AMF10 while UE3 is in the registration area. After this registration procedure, if AMF_1 10A receives a PDU session establishment request message or service request message from UE3 on S-NSSAI_N, AMF_1 10A will send a PDU session establishment denial message or service denial message to UE3, along with a new cause value or an existing cause value indicating to UE3 that re-registration is required. When AMF_1 10A receives a new Registration Request message from UE 3 with S-NSSAI_N set as the Requested NSSAI, AMF_1 10A treats S-NSSAI_N as an Indemnity NSSAI parameter, as described in Solution 2. Therefore, the Registration Request message can be rerouted to a neighboring AMF10 (e.g., AMF_2 10B) that supports S-NSSAI_N, as described in Solution 2.

[0042] Solution 1 - Access to isolated network slices via on-demand registration Solution 1 proposes "on-demand registration" to isolated network slices (e.g., isolated network slice S-NSSAI_N), as shown in Figure 3. When a UE3 application (app) requires a service on an isolated or available S-NSSAI (e.g., S-NSSAI_N), UE3 triggers on-demand registration by including the required "available S-NSSAI_N" in the RRC message and Registration Request message. UE3 also demonstrates support for "on-demand registration functionality."

[0043] 1) UE3 is enrolled in S-NSSAI_N and S-NSSAI_M. UE3 is in idle mode and camps in a cell that supports both S-NSSAI_N and S-NSSAI_M, and UE3 is enrolled in S-NSSAI_M via AMF_1 10A. During the UE enrollment of S-NSSAI_M to AMF_1 10A, S-NSSAI_N was separated from S-NSSAI_M, so UE3 is assigned an available S-NSSAI_N (as shown, for example, in Figure 2 and related explanations).

[0044] During the registration process, UE3 may obtain information from (R)AN node 5 regarding support for the "On-Demand Registration Function" based on information transmitted in RRC releases or any RRC messages during the registration process. Alternatively, UE3 may obtain information from (R)AN node 5 regarding support for the "On-Demand Registration Function" via system information on the broadcast channel.

[0045] 2) The UE3 app requires a service on a separate network slice (e.g., "Available S-NSSAI_N"). The network slice S-NSSAI_N is available in PLMN (e.g., supported by PLMN), but UE3 is not registered for it. UE3 triggers an "on-demand registration" for the separate network slice (e.g., Available S-NSSAI_N).

[0046] 3) UE3 sends an RRC Connection Setup Complete message (In demand NSSAI=S-NSSAI_N, Requested NSSAI=S-NSSAI_M, NAS message=Registration Request ("On-Demand Registration Function Support" indicator, Requested NSSAI=S-NSSAI_N, S-NSSAI_M)) to (R)AN node 5. UE3 first triggers the RRC connection establishment procedure with (R)AN node 5, and UE3 includes the separated available S-NSSAI_N in the "In demand NSSAI" parameter, the requested S-NSSAI_M in the Requested NSSAI parameter, and includes the Registration Request message as a NAS message in the RRC Connection Setup Complete message. UE3 does not need to include GUAMI, 5G-S-TMSI, or 5G-GUTI in the RRC Connection Setup Complete message, as it forces (R)AN node 5 to perform AMF selection even though UE3 has not changed its location (e.g., UE3 remains in the same cell). If (R)AN node 5 cannot find an AMF10 that supports both network slices S-NSSAI_N and S-NSSAI_M, then "Independence S-NSSAI_N" has preference / priority over the requested S-NSSAI_M. UE3 does not need to include the requested S-NSSAI_M in the RRC Connection Setup Complete message.

[0047] Alternatively, the Indemnity S-NSSAI_N may be provided to (R)AN node 5 using additional differentiated tags (e.g., information, instruction, or parameter) within existing parameters such as Requested NSSAI, or other existing parameters within the RRC message. This allows (R)AN node 5 to distinguish the Indemnity S-NSSAI_N from other network slices and prioritize the Indemnity S-NSSAI_N when selecting AMF10.

[0048] In the Registration Request message, UE3 includes the "On-Demand Registration Support" directive, indicating that UE3 supports the "On-Demand Registration" feature. UE3 also includes S-NSSAI_N in the Requested NSSAI, along with other requested S-NSSAIs (e.g., S-NSSAI_M).

[0049] 4) (R) AN node 5 selects AMF_2 10B, which supports "Indemnity S-NSSAI_N", which has a higher priority than S-NSSAI_M.

[0050] 5) (R)AN node 5 sends the UE initial message (NAS message = Registration Request ("On-Demand Registration Function Support" indicator, Requested NSSAI = S-NSSAI_N, S-NSSAI_M)) to AMF_2 10B. (R)AN node 5 forwards the Registration Request message from UE3 to AMF_2 10B.

[0051] 6) Continue the registration procedure with AMF_2 10B in accordance with TS23.502 (Non-Patent Document 3).

[0052] 7) If UE3 indicates "Support for On-Demand Registration" in the Registration Request message, AMF_2 10B will include S-NSSAI_M in the "Available NSSAI" parameter returned to UE3 because S-NSSAI_M is not supported by AMF_2 10B. This is because S-NSSAI_M and S-NSSAI_N are separate network slices and are supported by the same AMF_2 10B, but S-NSSAI_M is available in PLMN and UE3 is subscribed to it. When determining whether S-NSSAI_M is an available S-NSSAI, AMF_2 10B may interact with UDM / UDR15, PCF13 and / or other network nodes to verify that S-NSSAI_M is a UE-subscribed network slice and that S-NSSAI_M is not restricted by PCC rules, operator policies or settings. AMF_2 10B may also check with NSSF17 whether S-NSSAI_M is supported by another AMF10 at the UE3 location.

[0053] 8) The AMF_2 10B sends a Registration Accept message (Allowed NSSAI=S-NSSAI_N, Available NSSAI=S-NSSAI_M) to the UE3. The AMF_2 10B confirms the registration of the isolated network slice S-NSSAI_N, i.e., the "Indemnity S-NSSAI_N", by including S-NSSAI_N in the Allowed NSSAI parameter, and the AMF_2 10B also returns S-NSSAI_M (the currently available S-NSSAI) in the Available NSSAI parameter. Alternatively, the available S-NSSAI_M may be provided to the UE3 along with additional differentiating tags (e.g., information, instructions, or parameters) in existing parameters such as Allowed NSSAI or Rejected NSSAI, or any other existing parameters in the Registration Accept message. This allows the UE3 to distinguish S-NSSAI_M from other network slices.

[0054] 9) UE3 may trigger an "on-demand registration," a PDU session establishment request, or a service request to a separate available S-NSSAI (e.g., S-NSSAI_M) if the service on such S-NSSAI is required by UE3 or an application on UE3, or if UE3 receives a paging message on such S-NSSAI that indicates UE3 needs to activate the service.

[0055] Alternatively, UE3 could predict, determine, or generate which network slices are eligible as available S-NSSAI by subtracting authorized S-NSSAIs from the list of enrolled S-NSSAIs, independently of the network. However, in this case, without network assistance, UE3 would not be able to obtain complete information about the availability of network slices, making it more likely that "on-demand registration" or service requests would be rejected.

[0056] For example, UE3 may set S-NSSAI_N to Requested NSSAI and not set GUAMI, 5G-S-TMSI, or 5G-GUTI in the RRC Connection Setup Complete message. Then, (R)AN node 5 performs AMF selection based on the existing mechanism, even though UE3 has not changed its position (for example, UE3 remains in the same cell).

[0057] Solution 2 - Access to isolated network slices by rerouting on-demand registration Solution 2 proposes "on-demand registration" of isolated network slices via rerouting to an AMF10 that supports in-demand S-NSSAI (e.g., isolated network slices), as shown in Figure 4. When a UE3 application (app) requires a service on an isolated or available S-NSSAI (e.g., S-NSSAI_N), UE3 triggers on-demand registration by placing the required available S-NSSAI_N in the "In demand NSSAI" parameter in the Registration Request message to AMF_110A. Since AMF_110A does not support S-NSSAI_N in the Requested NSSAI, AMF_110A finds an AMF10 that supports S-NSSAI_N and forwards the Registration Request message to the found AMF10 (e.g., AMF_210B). UE3 also demonstrates that it supports the "on-demand registration" functionality itself.

[0058] 1) UE3 is subscribed to S-NSSAI_N and S-NSSAI_M. UE3 is in idle mode and camps in a cell that supports both S-NSSAI_N and S-NSSAI_M, and UE3 is registered with S-NSSAI_M via AMF_1 10A. During UE registration of S-NSSAI_M using AMF_1 10A, S-NSSAI_N was separated from S-NSSAI_M, so UE3 was assigned an available S-NSSAI_N (as shown, for example, in Figure 2 and related explanations).

[0059] 2) The UE3 app requires a service on a separate network slice (e.g., "Available S-NSSAI_N"). Although the network slice S-NSSAI_N is available in PLMN (i.e., supported by PLMN), UE3 is not registered for it. UE3 triggers on-demand registration of the separate network slice (e.g., Available S-NSSAI_N).

[0060] 3) UE3 sends a Registration Request message ("On-Demand Registration Feature Support" indicator, Requested NSSAI=S-NSSAI_M, Requested NSSAI=S-NSSAI_N) to AMF_1 10A. In the Registration Request message to AMF_1 10A, UE3 includes the "On-Demand Registration Feature Support" indicator, which indicates that UE3 supports the "On-Demand Registration" feature. UE3 also includes the requested available S-NSSAI_N in the "In demand NSSAI" parameter, along with the S-NSSAI_M in the Requested NSSAI parameter. The S-NSSAI_N in the "In demand NSSAI" parameter takes precedence over the requested S-NSSAI_M in the Requested NSSAI parameter.

[0061] Alternatively, the Indemnity S-NSSAI_N may be provided to AMF_1 10A along with additional differentiated tags (e.g., information, indicators, or parameters) within existing parameters such as Requested NSSAI or any other existing parameters in the Registration Request message. This allows AMF_1 10A to distinguish the Indemnity S-NSSAI_N from other network slices and give priority to the Indemnity S-NSSAI_N when selecting AMF10 for rerouting.

[0062] 4) "Indemnity S-NSSAI_N" is not supported by AMF_1 10A. With the help of NSSF17, AMF_1 10A finds AMF_2 10B which supports "Indemnity S-NSSAI_N" and reroutes UE3 to AMF_2 10B via (R)AN node 5.

[0063] 5) Reroute the initial UE message to AMF_2 10B and continue the registration procedure on AMF_2 10B in accordance with 3GPP TS 23.502 (Non-Patent Document 3).

[0064] 6) If UE3 indicates "Support for On-Demand Registration" in the Registration Request message, AMF_2 10B will include S-NSSAI_M in the "Available NSSAI" parameter returned to UE3 because S-NSSAI_M is not supported by AMF_2 10B. This is because S-NSSAI_M and S-NSSAI_N are separate network slices and are not supported by the same AMF_2 10B, while S-NSSAI_M is available in PLMN and UE3 is subscribed to it. When determining whether S-NSSAI_M is an available S-NSSAI, AMF_2 10B may interact with UDM / UDR15, PCF13 and / or other network nodes to verify that S-NSSAI_M is the network slice to which UE is subscribed and that S-NSSAI_M is not restricted by PCC rules, operator policies, or settings. AMF_2 10B may also check with NSSF17 whether S-NSSAI_M is supported by another AMF10 at the UE3 location.

[0065] 7) AMF_2 10B sends a Registration Accept (Allowed NSSAI=S-NSSAI_N,Available NSSAI=S-NSSAI_M) message to UE3. AMF_2 10B confirms the registration of the in-demand S-NSSAI_N by including S-NSSAI_N in the Allowed NSSAI parameter, and AMF_2 10B also returns S-NSSAI_M (the currently available S-NSSAI) in the Available NSSAI parameter. Alternatively, the available S-NSSAI_M may be provided to UE3 along with additional differentiating tags (e.g., information, instructions, or parameters) in existing parameters such as Allowed NSSAI or Rejected NSSAI, or any other existing parameters in the Registration Accept message. This allows UE3 to distinguish S-NSSAI_M from other network slices.

[0066] 8) If a service on such an S-NSSAI is required by UE3 or an application on UE3, or if UE3 receives a paging message on such an S-NSSAI that indicates UE3 needs to activate the service, UE3 may trigger an "on-demand registration," a PDU session establishment request, or a service request to a separate, available S-NSSAI (e.g., S-NSSAI_M).

[0067] Alternatively, UE3 can predict, determine, or generate which network slices are eligible as available S-NSSAI by subtracting authorized S-NSSAIs from the list of enrolled S-NSSAIs, independently of the network. However, in this case, the likelihood of "on-demand registration," PDU session establishment requests, or service requests being rejected increases because UE3 cannot obtain complete information about the availability of network slices without network assistance.

[0068] overview Beneficial examples include, but are not limited to, one or more of the following features: -Available NSSAI- A list of one or more S-NSSAIs that the UE is enrolled in and supported by PLMN, but which are not currently supported in AMF. The list of available S-NSSAIs is provided to the UE during the registration process (for example, as a new parameter in the Registration Accept message). -In-Demand NSSAI- A list of one or more available S-NSSAIs that trigger on-demand registration by the UE. A list of one or more available S-NSSAIs can be called an in-demand S-NSSAI list. The in-demand S-NSSAI list is provided to the network during the registration process (for example, as a new parameter in the Registration Request message). -On-Demand Registration Function Support Indicator- UEs that support "On-Demand Registration" indicate the "On-Demand Registration Function Support" indicator during the registration process (for example, in the Registration Request message) so that the network returns a list of available S-NSSAIs.

[0069] To provide these functions, the above embodiments describe an exemplary method that includes at least some of the following steps: -On-demand registration (Solution 1)- Registration to one or more available S-NSSAIs by UE. Here, if a UE requires service on a network slice it subscribes to but is not registered with, the UE can trigger registration on that network slice if it is on the list of available S-NSSAIs provided to the UE at the time of last registration. To this end, the UE mimics location registration by adding the Requested NSSAI and the list of available S-NSSAIs to the RRC message and by not including GUAMI, 5G-S-TMSI, or 5G-GUTI in the RRC Connection Setup Complete message. This causes the (R)AN node to perform AMF selection as if the UE had changed its location, but the UE remains in the same cell. In this way, the NG-RAN node can select an AMF that supports the available S-NSSAI (that the service is needed for), because available S-NSSAIs have "on-demand registration" priority. -On-demand registration via rerouting (Solution 2)- Registration by the UE to one or more available S-NSSAIs. Here, if the UE needs service on a network slice that it subscribes to but is not registered with, the UE can trigger registration on that network slice if it is on the list of available S-NSSAIs provided to the UE at the time of last registration. For this purpose, the UE includes a new parameter "In demand NSSAI" in the Registration Request message. This causes the UE to be rerouted to a target AMF that supports the network slice in the "In demand NSSAI" parameter, which has a higher priority than the network slice in the "Requested NSSAI" parameter.

[0070] System Overview Figure 5 schematically shows a mobile (cellular or wireless) telecommunications system 1 to which the above embodiment can be applied.

[0071] In this network, users of mobile devices 3 can communicate with each other and with other users via their respective base stations 5 and core network 7 using appropriate 3GPP radio access technologies (RATs), such as E-UTRA and / or 5G RATs. It should be understood that multiple base stations 5 form a (radio) access network or (R)AN. As those skilled in the art will understand, three mobile devices 3 and one base station 5 are shown in Figure 1. Referring to Figure 5 for illustrative purposes, the system, when implemented, would typically include other base stations and mobile devices. Mobile devices 3 may be referred to as UE3, and base station 5 may be referred to as (R)AN node 5.

[0072] Each base station 5 controls one or more associated cells (directly or via other nodes such as home base stations, relays, remote radio heads, and distributed units). A base station 5 that supports the E-UTRA protocol for mobile devices 3 may be called an "ng-eNB," and a base station 5 that supports next-generation protocols for mobile devices 3 may be called a "gNB." It will be understood that some base stations 5 may be configured to support both 4G and 5G, and / or any other 3GPP or non-3GPP communication protocols.

[0073] The mobile device 3 and its service base station 5 are connected via an appropriate air interface (e.g., a so-called "Uu" interface). Neighboring base stations 5 are connected to each other via appropriate inter-base station interfaces (e.g., a so-called "X2" interface, an "Xn" interface). The base stations 5 / access network are also connected to core network nodes via appropriate interfaces (e.g., a so-called "NG-U" interface (for the user plane), a so-called "NG-C" interface (for the control plane), and / or similar).

[0074] The core network 7 typically includes logical nodes (or “functions”) to support communications in the telecommunications system 1. Typically, for example, the core network 7 in a “next-generation” / 5G system includes, among other functions, control plane functions (CPF) and user plane functions (UPF). It should be understood that the core network 7 may also include, among other things, one or more access and mobility management functions (AMF) 10 (e.g., slice-specific AMF 10A / 10B), policy control functions (PCF) 13, unified data management (UDM) / unified data repository (UDR) functions 15, and network slice selection functions (NSSF) 17. Although not shown in Figure 5, the core network 7 may also be coupled to at least one application function (AF) / application server (AS), etc. The core network 7 also provides connectivity to an external IP network / data network 20 (such as the Internet).

[0075] The components of this system 1 are configured to perform one or more of the methods described with reference to Figures 1 to 4.

[0076] User Equipment (UE) Figure 6 is a block diagram showing the main components of the UE (Mobile Device 3) shown in Figure 5. As shown, the UE includes a transceiver circuit 31 capable of transmitting signals to and receiving signals from nodes connected via one or more antennas 33. Although not necessarily shown in Figure 6, the UE of course has all the usual functions of a conventional mobile device (such as a user interface 35), which may be adequately provided by any one or any combination of hardware, software, and firmware. The controller 37 controls the operation of the UE according to software stored in memory 39. The software may be pre-installed in memory 39 and / or downloaded via the communication network 1 or, for example, from a removable data storage device (RMD). The software includes, among other things, an operating system 41 and a communication control module 43. The communication control module 43 is responsible for processing (generating / transmitting / receiving) signaling messages and uplink / downlink data packets between the UE 3 and other nodes, including the (R)AN node 5, application functions, and core network nodes. Such signaling includes properly formatted requests and responses related to on-demand registration of UE3 to isolated network slices.

[0077] (R)AN node Figure 7 is a block diagram showing the main components of an exemplary (R)AN node 5 (base station) as shown in Figure 5. As shown, the (R)AN node 5 includes a transmit / receive circuit 51 that can operate to send and receive signals to and from UE3 connected via one or more antennas 53, and to send and receive signals to and from network nodes (directly or indirectly) via a network interface 55. The network interface 55 typically includes a suitable base station-base station interface (e.g., X2 / Xn) and a suitable base station-core network interface (e.g., NG-U / NG-C). A controller 57 controls the operation of the (R)AN node 5 according to software stored in memory 59. The software may be pre-installed in memory 59 and / or downloaded via the communication network 1, or from, for example, a removable data storage device (RMD). The software includes, among other things, an operating system 61 and a communication control module 63. The communication control module 63 is responsible for processing (generating / transmitting / receiving) signaling between the (R)AN node 5, other nodes such as UE3, and core network nodes. Such signaling includes properly formatted requests and responses regarding on-demand registration of UE3 to isolated network slices.

[0078] Core network node Figure 8 is a block diagram showing the main components of a general-purpose core network node (or function) as shown in Figure 5, such as AMF10, PCF13, UDM / UDR15, and NSSF17. As shown, the core network node includes a transmit / receive circuit 71 that can operate to send and receive signals to and from other nodes (including UE3 and (R)AN node 5) via a network interface 75. A controller 77 controls the operation of the core network node according to software stored in memory 79. The software may be pre-installed in memory 79 and / or downloaded via the communication network 1 or, for example, from a removable data storage device (RMD). The software includes, among other things, an operating system 81 and at least a communication control module 83. The communication control module 83 is responsible for processing (generating / transmitting / receiving) signaling between the core network node and other nodes such as UE3, (R)AN node 5, and other core network nodes. Such signaling includes appropriately formatted requests and responses regarding the on-demand registration of UE3 to isolated network slices.

[0079] Change and replacement Detailed embodiments are described above. As those skilled in the art will understand, many modifications and substitutions can be made to the above embodiments, while still benefiting from the invention as embodied therein. Some of these substitutions and modifications are described here for illustrative purposes only.

[0080] The above explanation uses specific messages and parameters for illustrative purposes. However, please understand that any other appropriate messages and parameters can be used if appropriate. The parameters mentioned above can be included in one or more appropriately formatted information elements, etc.

[0081] In the above description, the UE, (R)AN node, and core network node are described as having several separate modules (such as communication control modules) for ease of understanding. These modules may thus be provided for a specific application, for example, where an existing system has been modified to implement the above embodiments, but in other applications, for example, in a system designed from the outset with the features of the invention in mind, these modules may not be identifiable as separate entities because they are integrated into the entire operating system or code. These modules may also be implemented in software, hardware, firmware, or a combination thereof.

[0082] Each controller may comprise any suitable form of processing circuitry, including, but not limited to, the following: a microprocessor, a central processing unit (CPU), an arithmetic logic unit (ALU), input / output (IO) circuits, internal memory / cache (program and / or data), processing registers, communication buses (e.g., control, data, and / or address buses), direct memory access (DMA) functions, hardware or software-implemented counters, pointers, and / or timers, and / or similar.

[0083] In the embodiments described above, several software modules have been described. As those skilled in the art will understand, the software modules may be provided in compiled or uncompiled form and may be supplied to the UE, (R)AN nodes, and core network nodes as signals over a computer network or on a recording medium. Furthermore, some or all of the functions performed by this software can be performed using one or more dedicated hardware circuits. However, the use of software modules is preferred in order to facilitate the updating of the UE, (R)AN nodes, and core network nodes to update the functions.

[0084] The above aspects can also be applied to "non-mobile" or generally stationary user devices.

[0085] Various other modifications are obvious to those skilled in the art and will not be described in further detail here.

[0086] All or part of the embodiments disclosed above may be described as follows, but are not limited to these. (Note 1) A communication terminal (3), Means for sending a first Non-Access Stratum (NAS) message to a core network node (10A) including first information indicating that the communication terminal (3) supports an on-demand registration function, and second information indicating a list of network slices for which the communication terminal (3) requests registration, Means for receiving a second NAS message from the core network node (10A) including third information indicating a first network slice used by the communication terminal (3) in the Public Land Mobile Network (PLMN), and fourth information indicating a second network slice to which the communication terminal (3) is subscribed and which is supported by the PLMN, but which is not supported by the core network node (10A) to which the communication terminal (3) is registered, The system includes means for triggering on-demand registration to the second network slice, The first network slice and the second network slice are communication terminals (3) included in the list. (Note 2) The triggering means is executed when the communication terminal (3) or an application within the communication terminal (3) requests service on the second network slice, or when the communication terminal (3) receives a paging message indicating that it needs to enable service on the second network slice. The communication terminal (3) as described in Appendix 1. (Note 3) The triggering means sends a third NAS message containing the first information and the second information to a second core network node (10B). The communication terminal(3) as described in Appendix 1 or 2. (Note 4) The triggering means transmits a fourth NAS message to the core network node (10A) including the first information, the fifth information, and the sixth information, wherein the fifth information indicates the first network slice as a network slice for which the communication terminal (3) requests registration, and the sixth information indicates the second network slice as a network slice that the communication terminal (3) has not previously registered. The communication terminal(3) as described in Appendix 1 or 2. (Note 5) The receiving means receives a fifth NAS message from the second core network node (10B) which includes a seventh piece of information indicating the second network slice used by the communication terminal (3) in the PLMN, and an eighth piece of information indicating the first network slice to which the communication terminal (3) is subscribed and which is supported by the PLMN, but which is not supported by the second core network node (10B) to which the communication terminal (3) is registered. A communication terminal (3) as described in any one of the items 1 to 4 of the appendix. (Note 6) The fourth piece of information described above is set for each access type, PLMN, or registration area. A communication terminal (3) as described in any of the appendices 1 to 5. (Note 7) A core network node (10A), A means for receiving a first Non-Access Stratum (NAS) message from the communication terminal (3), which includes first information indicating that the communication terminal (3) supports an on-demand registration function, and second information indicating a list of network slices for which the communication terminal (3) requests registration. When the first NAS message is received, means for generating fourth information indicating a second network slice to which the communication terminal (3) is subscribed and which is supported by the Public Land Mobile Network (PLMN), but which is not supported by the core network node (10A) to which the communication terminal (3) is registered; The PLMN includes means for sending a second NAS message to the communication terminal (3) that includes a third piece of information indicating a first network slice used by the communication terminal (3), and the fourth piece of information, The first network slice and the second network slice are included in the above list. Core network node (10A). (Note 8) The fourth piece of information is generated based on at least one of the following: interaction with network nodes (5, 17, 13, 15), operator policies, and settings. The core network node (10A) described in Appendix 7. (Note 9) The receiving means receives a fourth NAS message from the communication terminal (3) containing the first information, the fifth information, and the sixth information, wherein the fifth information indicates the first network slice as a network slice that the communication terminal (3) requests to register, and the sixth information indicates the second network slice as a network slice that the communication terminal (3) has not previously registered. The core network node (10A) further includes means for finding a second core network node (10B) that supports the second network slice if the second network slice indicated by the fifth information is not supported by the core network node (10A), Means for rerouting the communication terminal (3) to the second core network node (10B), The core network node (10A) as described in Appendix 7 or 8. (Note 10) The second core network node (10B) is discovered based on interaction with the network node (17). The core network node (10A) as described in Appendix 7 or 8. (Note 11) The communication terminal (3) A process of sending a first Non-Access Stratum (NAS) message to a core network node (10A) including first information indicating that the communication terminal (3) supports an on-demand registration function, and second information indicating a list of network slices for which the communication terminal (3) requests registration; A process for receiving a second NAS message from the core network node (10A) includes: third information indicating a first network slice used by the communication terminal (3) in the Public Land Mobile Network (PLMN); and fourth information indicating a second network slice to which the communication terminal (3) is subscribed and which is supported by the PLMN, but which is not supported by the core network node (10A) to which the communication terminal (3) is registered; The process that triggers on-demand registration to the second network slice described above is performed, The first network slice and the second network slice are methods included in the list. (Note 12) The triggering process is executed when the communication terminal (3) or an application within the communication terminal (3) requests service on the second network slice, or when the communication terminal (3) receives a paging message indicating that it needs to enable service on the second network slice. The method described in Appendix 11. (Note 13) In the triggering process, a fourth NAS message containing the first information, the fifth information, and the sixth information is sent to the core network node (10A), wherein the fifth information indicates the first network slice as a network slice for which the communication terminal (3) requests registration, and the sixth information indicates the second network slice as a network slice that the communication terminal (3) has not previously registered. The method described in Appendix 11 or 12. (Note 14) The core network node (10A) A process of receiving a first Non-Access Stratum (NAS) message from the communication terminal (3), which includes first information indicating that the communication terminal (3) supports an on-demand registration function, and second information indicating a list of network slices for which the communication terminal (3) requests registration. When the first NAS message is received, the process generates fourth information indicating a second network slice to which the communication terminal (3) is subscribed and which is supported by the Public Land Mobile Network (PLMN), but which is not supported by the core network node (10A) to which the communication terminal (3) is registered. The PLMN performs the following process: sending a second NAS message to the communication terminal (3) that includes a third piece of information indicating a first network slice used by the communication terminal (3), and the fourth piece of information. The first network slice and the second network slice are included in the above list. method. (Note 15) The fourth piece of information is generated based on at least one of the following: interaction with network nodes (5, 17, 13, 15), operator policies, and settings. The method described in Appendix 14.

[0087] This application is based on Indian Patent Application No. 202011057170, filed on 30 December 2020, which claims priority, and its disclosure is incorporated herein by reference in its entirety. [Explanation of Symbols]

[0088] 1. Communication System 20 IP Networks / Data Networks 3 UE 31 Transmit / Receive Circuit 33 Antennas 35 User Interface 37 Controllers 39 memory 41 Operating Systems 43 Communication control module 5 (R) AN node (base station) 7 Core Network 51 Transceiver Circuit 53 Antenna 55 Network Interfaces 57 Controllers 59 memory 61 Operating Systems 63 Communication control module 10 AMF 13 PCF 15 UDM / UDR 17 NSSF 71 Transmit / Receive Circuit 75 Network Interfaces 77 Controllers 79 memory 81 Operating Systems 83 Communication control module

Claims

1. It is a communication terminal, A first message containing first information indicating support for controlling network slices is sent to the core network node. The core network node receives a second message containing Allow NSSAI (Network Slice Selection Assistance Information) and second information, The second piece of information indicates that S-NSSAI (Single Network Slice Selection Assistance Information) included in Configured NSSAI can be registered on the network on demand in response to a request from the communication terminal's application. When the application of the communication terminal requests the use of a service using the S-NSSAI, a third message including the S-NSSAI is sent to the core network node in the Requested NSSAI. Communication terminal.

2. The PDU session establishment procedure is initiated after the S-NSSAI registration procedure is successfully completed. The communication terminal according to claim 1.

3. The communication terminal according to claim 1, wherein the first information indicates that the communication terminal supports an on-demand registration function.

4. It is a core network node, A first message containing first information indicating support for controlling network slices is received from a communication terminal. A second message containing Allow NSSAI (Network Slice Selection Assistance Information) and second information is sent to the communication terminal. The second piece of information indicates that S-NSSAI (Single Network Slice Selection Assistance Information) included in Configured NSSAI can be registered on the network on demand in response to a request from the communication terminal's application. When the application of the communication terminal requests the use of a service using the S-NSSAI, the communication terminal receives a third message containing the S-NSSAI in the Requested NSSAI. Core network node.

5. The PDU session establishment procedure is initiated after the S-NSSAI registration procedure is successfully completed. The core network node according to claim 4.

6. The core network node according to claim 4, wherein the first information indicates that the communication terminal supports an on-demand registration function.

7. Having means for determining the second information based on subscriber data in the UDM, The core network node according to claim 4.

8. The communication terminal, A first message containing first information indicating support for controlling network slices is sent to the core network node. The core network node receives a second message containing Allow NSSAI (Network Slice Selection Assistance Information) and second information, The second piece of information indicates that S-NSSAI (Single Network Slice Selection Assistance Information) included in Configured NSSAI can be registered on the network on demand in response to a request from the communication terminal's application. When the application of the communication terminal requests the use of a service using the S-NSSAI, a third message including the S-NSSAI is sent to the core network node in the Requested NSSAI. method.

9. The PDU session establishment procedure is initiated after the S-NSSAI registration procedure is successfully completed. The method according to claim 8.

10. The method according to claim 8, wherein the first information indicates that the communication terminal supports an on-demand registration function.

11. The core network node, A first message containing first information indicating support for controlling network slices is received from a communication terminal. A second message containing Allow NSSAI (Network Slice Selection Assistance Information) and second information is sent to the communication terminal. The second piece of information indicates that S-NSSAI (Single Network Slice Selection Assistance Information) included in Configured NSSAI can be registered on the network on demand in response to a request from the communication terminal's application. When the application of the communication terminal requests the use of a service using the S-NSSAI, the communication terminal receives a third message containing the S-NSSAI in the Requested NSSAI. method.

12. The PDU session establishment procedure is initiated after the S-NSSAI registration procedure is successfully completed. The method according to claim 11.

13. The method according to claim 11, wherein the first information indicates that the communication terminal supports an on-demand registration function.

14. Furthermore, the second information is determined based on subscriber data within the UDM. The method according to claim 11.

15. The second message, in addition to the second information, The information includes a third piece of information indicating that some of the S-NSSAIs in the list of configured NSSAIs are permitted, The communication terminal according to claim 1.

16. In response to transmitting the first information to the core network node, the second information is received from the core network node. The communication terminal according to claim 1.

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