Operation method due to slice deregistration inactivity timer expiry

Abstract

According to one example of the present specification, a method is provided. The method may include the steps of: driving a slice deregistration inactivity timer; locally removing a Single Network Slice Selection Assistance Information (S-NSSAI) from Network Slice Selection Assistance Information (NSSAI) when the slice deregistration inactivity timer expires; and performing de-mapping between the replaced S-NSSAI and the alternative S-NSSAI in the access type when the replaced S-NSSAI or the alternative S-NSSAI is removed from the allowed NSSAI upon the expiration of the slice deregistration inactivity timer in the corresponding access type.

Description

Technology Field

[0001] This specification relates to 3GPP wireless communication systems. Background Technology

[0002] Thanks to the success of LTE (long term evolution) / LTE-Advanced (LTE-A) for 4th generation mobile communication, interest in the next generation, namely 5th generation (so-called 5G) mobile communication, is also rising, and research is being conducted one after another.

[0003] Fifth-generation mobile communication, as defined by the International Telecommunication Union (ITU), refers to providing a maximum data transmission speed of 20 Gbps and a perceived transmission speed of at least 100 Mbps anywhere, and is officially called 'IMT-2020'.

[0004] Fifth-generation mobile communication supports multiple numerologies or subcarrier spacings (SCS) to support various services. For example, when the SCS is 15 kHz, it supports a wide area in traditional cellular bands; when the SCS is 30 kHz / 60 kHz, it supports dense-urban environments, lower latency, and wider carrier bandwidth; and when the SCS is 60 kHz or higher, it supports a bandwidth greater than 24.25 GHz to overcome phase noise.

[0005] The NR frequency band is defined by two types of frequency ranges (FR1, FR2). FR1 is 410 MHz - 7125 MHz, and FR2 is 24250 MHz - 52600 MHz, which can refer to millimeter wave (mmW).

[0006] For the convenience of explanation, among the frequency ranges used in the NR system, FR1 may mean "sub 6GHz range" and FR2 may mean "above 6GHz range" and may be called millimeter wave (mmW).

[0007] Frequency Range designation Corresponding frequency range Subcarrier Spacing FR1 410MHz - 7125MHz 15, 30, 60kHz FR2 24250MHz - 52600MHz 60, 120, 240kHz

[0008] The numerical values ​​of the frequency range of the NR system may change. For example, FR1 may include a band of 410 MHz to 7125 MHz as shown in Table 1 below. That is, FR1 may include a frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or higher. For example, the frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or higher included within FR1 may include an unlicensed band. The unlicensed band may be used for various purposes, for example, for communication for vehicles (e.g., autonomous driving).

[0009] Figure 1 is a diagram illustrating a wireless communication system.

[0010] The 5GC (5G Core) network may include various components, and in FIG. 1, it includes the Access and Mobility Management Function (41), Session Management Function (42), Policy Control Function (43), User Plane Function (44), Application Function (45), Unified Data Management (46), and Non-3GPP InterWorking Function (49).

[0011] The UE (User Equipment) (10) is connected to the data network via the NG-RAN (Next Generation Radio Access Network) and the UPF (44).

[0012] The UE (10) can also receive data services through untrusted non-3GPP (non-3rd Generation Partnership Project) access, such as a WLAN (Wireless Local Area Network). To connect the non-3GPP access to the core network, an N3IWF (49) may be deployed.

[0013] Figure 2 is an example diagram showing the structure of a wireless communication system from the perspective of nodes.

[0014] As can be seen by referring to Figure 2, the UE is connected to the Data Network (DN) through the Radio Access Network (RAN).

[0015] The illustrated Control Plane Function (CPF) node performs all or part of the functions of the Mobility Management Entity (MME) of 4th generation mobile communication, and all or part of the control plane functions of the Serving Gateway (S-GW) and PDN Gateway (P-GW). The CPF node includes the Access and Mobility Management Function (AMF) and the Session Management Function (SMF).

[0016] The illustrated User Plane Function (UPF) node is a type of gateway through which user data is transmitted and received. The UPF node can perform all or part of the user plane functions of the S-GW and P-GW of 4th generation mobile communication.

[0017] The illustrated PCF (Policy Control Function) is a node that controls the operator's policy.

[0018] The illustrated Application Function (AF) is a server designed to provide various services to the UE.

[0019] The Unified Data Management (UDM) described above is a type of server that manages subscriber information, such as the Home Subscriber Server (HSS) of 4th generation mobile communication. The UDM stores and manages the subscriber information in the Unified Data Repository (UDR).

[0020] The illustrated Authentication Server Function (AUSF) authenticates and manages UEs.

[0021] The illustrated Network Slice Selection Function (NSSF) is a node for network slicing as described below.

[0022] A UE can simultaneously connect to two data networks using multiple PDU (protocol data unit or packet data unit) sessions.

[0023] Figure 3 is another example diagram showing the structure of a wireless communication system from the perspective of nodes.

[0024] Figure 3 shows an architecture for a UE to simultaneously access two data networks using a single PDU session.

[0025] The details regarding the reference points shown in Figures 2 and 3 are as follows.

[0026] N1 represents a reference point between the UE and the AMF.

[0027] N2 represents a reference point between (R)AN and AMF.

[0028] N3 represents a reference point between (R)AN and UPF.

[0029] N4 represents the reference point between SMF and UPF.

[0030] N5 represents the reference point between PCF and AF.

[0031] N6 represents a reference point between UPF and DN.

[0032] N7 represents a reference point between SMF and PCF.

[0033] N8 represents a reference point between UDM and AMF.

[0034] N9 represents a reference point between UPFs.

[0035] N10 represents a reference point between UDM and SMF.

[0036] N11 represents a reference point between AMF and SMF.

[0037] N12 represents a reference point between AMF and AUSF.

[0038] N13 represents a reference point between UDM and AUSF.

[0039] N14 represents a reference point between AMFs.

[0040] N15 represents a reference point between PCF and AMF.

[0041] N16 represents a reference point between SMFs.

[0042] N22 represents a reference point between AMF and NSSF.

[0043] N33 represents a reference point between the Network Exposure Function (NEF) and the AF.

[0044] Figure 4 is an example diagram showing the structure of a radio interface protocol between a terminal and a network.

[0045] The above wireless interface protocol is based on the 3GPP wireless access network standard. The above wireless interface protocol is horizontally composed of a physical layer, a data link layer, and a network layer, and vertically divided into a user plane for transmitting data information and a control plane for transmitting signaling.

[0046] The above protocol layers can be classified into L1 (Layer 1), L2 (Layer 2), and L3 (Layer 3) based on the lower three layers of the Open System Interconnection (OSI) standard model, which is widely known in communication systems.

[0047] Below, each layer of the above wireless interface protocol is described.

[0048] The first layer, the physical layer, provides information transfer services using a physical channel. The physical layer is connected to the upper Medium Access Control (MAC) layer via a transport channel, and data between the MAC layer and the physical layer is transmitted through this transport channel. Additionally, data is transmitted between different physical layers, specifically between the physical layers of the transmitting and receiving sides, via a physical channel.

[0049] Layer 2 includes the Medium Access Control (MAC) layer, the Radio Link Control (RLC) layer, and the Packet Data Convergence Protocol (PDCP) layer.

[0050] Layer 3 includes the Radio Resource Control (RRC) layer. The RRC layer is defined only in the control plane and is responsible for controlling logical channels, transmission channels, and physical channels in relation to the configuration, reconfiguration, and release of Radio Bearers (RBs). Here, an RB refers to a service provided by Layer 2 for data transfer between a terminal and a RAN.

[0051] The above NAS (Non-Access Stratum) layer performs functions such as session management and mobility management.

[0052] The NAS layer is divided into NAS entities for Mobility Management (MM) and NAS entities for Session Management (SM).

[0053] 1) NAS entities for MM provide the following common functions.

[0054] As a NAS procedure related to AMF, it includes the following.

[0055] - Registration management and connection management procedures. AMF supports the following functions.

[0056] - Secure NAS signal connection between UE and AMF (integrity protection, encryption)

[0057] 2) The NAS entity for SM performs session management between the UE and the SMF.

[0058] SM signaling messages are processed, i.e., generated and processed, at the NAS-SM layer of the UE and SMF. The content of SM signaling messages is not interpreted by the AMF.

[0059] - In the case of SM signaling transmission,

[0060] - The NAS entity for the MM generates a NAS-MM message that derives the method and location for delivering the SM signaling message through a security header indicating the NAS transmission of the SM signaling and additional information about the receiving NAS-MM.

[0061] - Upon receiving SM signaling, the NAS entity for SM performs an integrity check on the NAS-MM message and interprets additional information to derive the method and location for the SM signaling message.

[0062] Meanwhile, the RRC layer, RLC layer, MAC layer, and PHY layer located below the NAS layer in Figure 4 are sometimes grouped together and called the Access Stratum (AS).

[0063] Network systems for 5G (i.e., 5GC) also support non-3GPP access. Representative examples of such non-3GPP access include WLAN access. Such WLAN access may include both trusted WLANs and untrusted WLANs.

[0064] In a system for 5G, the AMF performs Registration Management (RM) and Connection Management (CM) for 3GPP access as well as non-3GPP access. The problem to be solved

[0065] The disclosure of this specification aims to provide a method of operation upon the expiration of a slice deregistration inactive timer. means of solving the problem

[0066] According to one example of the present specification, a method is provided. The method may include the steps of: driving a slice deregistration inactivity timer; locally removing a Single Network Slice Selection Assistance Information (S-NSSAI) from Network Slice Selection Assistance Information (NSSAI) when the slice deregistration inactivity timer expires; and performing de-mapping between the replaced S-NSSAI and the alternative S-NSSAI in the access type when the replaced S-NSSAI or the alternative S-NSSAI is removed from the allowed NSSAI upon the expiration of the slice deregistration inactivity timer in the corresponding access type.

[0067] According to one example of the present specification, a user device (UE) is provided. The UE may include a transceiver; and a processor that controls the transceiver to perform operations. The operations performed by the processor may include: driving a slice deregistration inactivity timer; locally removing a Single Network Slice Selection Assistance Information (S-NSSAI) from Network Slice Selection Assistance Information (NSSAI) when the slice deregistration inactivity timer expires; and performing de-mapping between the replaced S-NSSAI and the alternative S-NSSAI in the access type when the replaced S-NSSAI or the alternative S-NSSAI is removed from the Network Slice Selection Assistance Information in the access type upon the expiration of the slice deregistration inactivity timer.

[0068] According to one example of the present specification, a chipset mounted on a user device (UE) is provided. The chipset may include at least one processor; and at least one memory that stores instructions and is operablely electrically connected to the at least one processor. An operation performed based on the instruction being executed by the at least one processor is: driving a slice deregistration inactivity timer; and, when the slice deregistration inactivity timer expires, locally removing a Single Network Slice Selection Assistance Information (S-NSSAI) from Network Slice Selection Assistance Information (NSSAI); And, if a replaced S-NSSAI or an alternative S-NSSAI is removed from an allowed NSSAI upon the expiration of the slice deregistration disable timer on the corresponding access type, the method may include the step of performing de-mapping between the replaced S-NSSAI and the alternative S-NSSAI on the access type.

[0069] According to one example of the present specification, a non-volatile computer-readable storage medium is provided for recording instructions. The storage medium contains instructions, and when executed by one or more processors mounted on a device, the instructions may cause the one or more processors to perform an operation. The operation may include: driving a slice deregistration inactivity timer; locally removing a Single Network Slice Selection Assistance Information (S-NSSAI) from Network Slice Selection Assistance Information (NSSAI) when the slice deregistration inactivity timer expires; and performing de-mapping between the replaced S-NSSAI and the alternative S-NSSAI in the access type when the replaced S-NSSAI or the alternative S-NSSAI is removed from the Network Slice Selection Assistance Information upon the expiration of the slice deregistration inactivity timer on the corresponding access type. Effects of the invention

[0070] According to the disclosure of this specification, a method of operation upon the expiration of a slice deregistration inactive timer is provided. Brief explanation of the drawing

[0071] Figure 1 is a diagram illustrating a wireless communication system. Figure 2 is an example diagram showing the structure of a wireless communication system from the perspective of nodes. Figure 3 is another example diagram showing the structure of a wireless communication system from the perspective of nodes. Figure 4 is an example diagram showing the structure of a radio interface protocol between a terminal and a network. Figures 5a and 5b are signal flow diagrams illustrating an exemplary registration procedure. Figures 6a and 6b are signal flow diagrams illustrating an exemplary PDU session establishment procedure. Figures 7a and 7b are signal flow diagrams illustrating the modification procedure of an exemplary PDU session. Figure 8 is an example diagram to explain the concept of network slicing. FIG. 9 is a flowchart according to one disclosure of the present specification. FIG. 10 is a block diagram showing the configuration of a terminal according to one embodiment of the present specification. FIG. 11 shows a block diagram of a processor in which the disclosure of the present specification is implemented. Specific details for implementing the invention

[0072] It should be noted that technical terms used in this specification are used merely to describe specific embodiments and are not intended to limit the content of this specification. Furthermore, unless specifically defined otherwise in this specification, technical terms used in this specification should be interpreted in the sense generally understood by those skilled in the art to which this disclosure pertains, and should not be interpreted in an overly broad or overly narrow sense. Additionally, if a technical term used in this specification is an incorrect technical term that fails to accurately express the content and concept of this specification, it should be understood as being replaced by a technical term that can be correctly understood by those skilled in the art. Moreover, general terms used in this specification should be interpreted according to their prior definitions or the context, and should not be interpreted in an overly narrow sense.

[0073] Additionally, singular expressions used in this specification include plural expressions unless the context clearly indicates otherwise. In this application, terms such as "composed of" or "have" should not be interpreted as necessarily including all of the various components or steps described in the specification, and should be interpreted as meaning that some of the components or steps may be omitted or additional components or steps may be included.

[0074] Additionally, terms including ordinal numbers, such as first, second, etc., used herein may be used to describe various components, but said components shall not be limited by said terms. Such terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the rights, the first component may be named the second component, and similarly, the second component may be named the first component.

[0075] When it is stated that a component is connected to or coupled with another component, it may be directly connected to or coupled with that other component, or there may be other components in between. On the other hand, when it is stated that a component is directly connected to or directly coupled with another component, it should be understood that there are no other components in between.

[0076] Hereinafter, embodiments will be described in detail with reference to the attached drawings. Identical or similar components regardless of drawing symbols are assigned the same reference number, and redundant descriptions thereof will be omitted. Furthermore, in describing the contents of this specification, if it is determined that a detailed description of related prior art may obscure the gist of this specification, such detailed description will be omitted. Additionally, it should be noted that the attached drawings are intended only to facilitate understanding of the contents and concepts of this specification, and should not be interpreted as limiting the contents and concepts of this specification. The contents and concepts of this specification should be interpreted as extending to all modifications, equivalents, and substitutions in addition to the attached drawings.

[0077] In this specification, “A or B” may mean “only A,” “only B,” or “both A and B.” Alternatively, in this specification, “A or B” may be interpreted as “A and / or B.” For example, in this specification, “A, B or C” may mean “only A,” “only B,” “only C,” or “any combination of A, B and C.”

[0078] As used herein, a slash ( / ) or a comma may mean “and / or.” For example, “A / B” may mean “A and / or B.” Accordingly, “A / B” may mean “only A,” “only B,” or “both A and B.” For example, “A, B, C” may mean “A, B, or C.”

[0079] In this specification, “at least one of A and B” may mean “only A,” “only B,” or “both A and B.” Additionally, in this specification, the expressions “at least one of A or B” or “at least one of A and / or B” may be interpreted as synonymous with “at least one of A and B.”

[0080] Additionally, in this specification, “at least one of A, B and C” may mean “only A,” “only B,” “only C,” or “any combination of A, B and C.” Furthermore, “at least one of A, B or C” or “at least one of A, B and / or C” may mean “at least one of A, B and C.”

[0081] Additionally, parentheses used in this specification may mean “for example.” Specifically, when indicated as “Control Information (PDCCH),” “PDCCH” may be proposed as an example of “Control Information.” In other words, “Control Information” in this specification is not limited to “PDCCH,” and “PDDCH” may be proposed as an example of “Control Information.” Furthermore, even when indicated as “Control Information (i.e., PDCCH),” “PDCCH” may be proposed as an example of “Control Information.”

[0082] Technical features described individually within a single drawing in this specification may be implemented individually or simultaneously.

[0083] In the attached drawings, User Equipment (UE) is illustrated as an example, but the illustrated UE may also be referred to by terms such as UE (100) (Terminal), ME (Mobile Equipment), etc. Additionally, the UE may be a portable device such as a laptop, mobile phone, PDA, smartphone, multimedia device, etc., or a non-portable device such as a PC, vehicle-mounted device, etc.

[0084] <Registration Procedure>

[0085] The UE needs to obtain authorization to enable mobility tracking, enable data reception, and receive services. To do this, the UE must register with the network. The registration procedure is performed when the UE needs to perform initial registration with the 5G system. Additionally, the registration procedure is performed when the UE performs a periodic registration update, when moving to a new tracking area (TA) from idle mode, and when the UE needs to perform a periodic registration update.

[0086] During the initial registration process, the UE's ID can be obtained from the UE. The AMF can transmit the PEI (IMEISV) to the UDM, SMF, and PCF.

[0087] Figures 5a and 5b are signal flow diagrams illustrating an exemplary registration procedure.

[0088] 1) A UE may transmit an AN message to a RAN. The AN message may include AN parameters and a registration request message. The registration request message may include information such as a registration type, a subscriber permanent ID or temporary user ID, security parameters, NSSAI, the UE's 5G capability, and PDU session status.

[0089] In the case of a 5G RAN, the above AN parameters may include SUPI or temporary user ID, selected network and NSSAI.

[0090] The registration type may indicate whether the UE is in "Initial Registration" (i.e., the UE is in a non-registered state), "Mobility Registration Update" (i.e., the UE is in a registered state and initiates the registration process due to mobility), or "Periodic Registration Update" (i.e., the UE is in a registered state and initiates the registration process due to the expiration of the periodic update timer). If a temporary user ID is included, said temporary user ID represents the last serving AMF. If the UE is already registered via non-3GPP access in a PLMN different from the PLMN of 3GPP access, the UE may not provide the UE temporary ID assigned by the AMF during the registration process via non-3GPP access.

[0091] Security parameters can be used for authentication and integrity protection.

[0092] The PDU session status indicates the PDU sessions available (previously established) to the UE.

[0093] 2) If SUPI is included or temporary user ID does not represent a valid AMF, RAN may select an AMF based on (R)AT and NSSAI.

[0094] If the (R)AN cannot select a suitable AMF, it selects a random AMF according to local policy and forwards the registration request to the selected AMF. If the selected AMF cannot service the UE, the selected AMF selects another AMF that is more suitable for the UE.

[0095] 3) The above RAN transmits an N2 message to a new AMF. The N2 message includes N2 parameters and a registration request. The registration request may include a registration type, a subscriber permanent identifier or temporary user ID, security parameters, NSSAI and MICO mode default settings, etc.

[0096] When 5G-RAN is used, the N2 parameter includes location information, a cell identifier, and a RAT type associated with the cell where the UE is camping.

[0097] If the registration type specified by the UE is a periodic registration update, the following steps 4 to 17 may not be performed.

[0098] 4) The newly selected AMF can send an information request message, such as Namf_Communication_UEContextTransfer, to the previous AMF.

[0099] If the UE's temporary user ID is included in the registration request message and the serving AMF has changed since the last registration, the new AMF may send an information request message containing the complete registration request information to the previous AMF to request the UE's SUPI and MM context.

[0100] 5) The previous AMF sends an information response message, such as Namf_Communication_UEContextTransfer response, to the newly selected AMF. The information response message may include SUPI, MM context, and SMF information.

[0101] Specifically, the previous AMF transmits an information response message containing the UE's SUPI and MM context.

[0102] - If the previous AMF contains information about an active PDU session, the previous AMF may include SMF information, including the SMF ID and PDU session ID, within the information response message.

[0103] 6) If the new AMF above does not have a SUPI provided by the UE or retrieved from the previous AMF, it sends an Identity Request message to the UE.

[0104] 7) The UE sends an Identity Response message containing the SUPI to the new AMF.

[0105] 8) AMF may decide to trigger AUSF. In this case, AMF may select AUSF based on SUPI.

[0106] 9) AUSF can initiate authentication of UE and NAS security functions.

[0107] 10) The new AMF above can send the Namf_Communication_RegistrationCompleteNotify message to the previous AMF.

[0108] 11) The new AMF above can send an Identity Request message to the UE.

[0109] If the PEI is not provided by the UE or has not been retrieved from a previous AMF, an Identity Request message may be sent to the AMF to retrieve the PEI.

[0110] 12) The new AMF above checks the identifier.

[0111] 13) If process 14 described below is performed, the new AMF selects a UDM based on SUPI.

[0112] 14) The above new AMF performs the registration procedure with UDM.

[0113] 15) The above new AMF can select PCF based on SUPI.

[0114] 16) The new AMF above performs Policy Association Establishment as a PCF.

[0115] 17) The new AMF sends a PDU Session Update SM Context message or a PDU Session Release SM Context message to the SMF.

[0116] 18-19) The new SMF sends an AMF Mobility Request message to N3IWF and receives a Mobility Response message from AMF.

[0117] 20) The aforementioned AMF sends a UE Context Termination Request message to the PCF.

[0118] If the aforementioned previous AMF previously requested that the UE context be set in the PCF, the aforementioned previous AMF can delete the UE context from the PCF.

[0119] 21) The new AMF sends a registration acceptance message to the UE. The registration acceptance message may include a temporary user ID, registration zone, mobility restriction, PDU session state, NSSAI, periodic registration update timer, and allowed MICO mode.

[0120] If the AMF assigns a new temporary user ID, the temporary user ID may be further included within the registration acceptance message. If mobility restrictions apply to the UE, information indicating the mobility restrictions may be additionally included within the registration acceptance message. The AMF may include information indicating the PDU session status for the UE within the registration acceptance message. The UE may remove any internal resources associated with a PDU session that is not marked as active in the received PDU session status. If PDU session status information is present in the Registration Request, the AMF may include information indicating the PDU session status to the UE within the registration acceptance message.

[0121] 22) The above UE sends a registration completion message to the above new AMF.

[0123] <PDU 세션 수립 절차>

[0124] There can be two types of PDU (Protocol Data Unit) session establishment procedures as follows.

[0125] - Procedure for establishing a PDU session initiated by the UE

[0126] - A procedure for establishing a PDU session initiated by the network. To this end, the network may send a device trigger message to the UE's application(s).

[0127] Figures 6a and 6b are signal flow diagrams illustrating an exemplary PDU session establishment procedure.

[0128] The procedure illustrated in FIGS. 6a and 6b assumes that the UE has already registered on the AMF according to the registration procedure. Therefore, it is assumed that the AMF has already obtained user subscription data from the UDM.

[0129] 1) The UE sends a NAS message to the AMF. The message may include S-NSSAI (Single Network Slice Selection Assistance Information), DNN (Data Network Name), PDU session ID, request type, N1 SM (Session Management) information, etc.

[0130] Specifically, the UE includes an S-NSSAI from the allowed NSSAI of the current access type. If information regarding the mapped NSSAI is provided to the UE, the UE may provide both an S-NSSAI based on the allowed NSSAI and a corresponding S-NSSAI based on the information of the mapped NSSAI. Here, the information of the mapped NSSAI is information mapping each S-NSSAI of the allowed NSSAI to the S-NSSAI of the NSSAI configured for the HPLMN (Home Public Land Mobile Network).

[0131] More specifically, the UE may extract and store information regarding the allowed S-NSSAI and the mapped S-NSSAI included in the registration acceptance message received from the network (i.e., AMF) during the registration procedure. Accordingly, the UE may include both the S-NSSAI based on the allowed NSSAI and the corresponding S-NSSAI based on the information of the mapped NSSAI in the PDU session establishment request message and transmit them.

[0132] To establish a new PDU session, the UE can generate a new PDU session ID.

[0133] The UE can initiate a PDU session establishment procedure initiated by the UE by transmitting a NAS message that includes a PDU session establishment request message within N1 SM information. The PDU session establishment request message may include a request type, a Session and Service Continuity (SSC) mode, and protocol configuration options.

[0134] If the PDU session establishment is for setting up a new PDU session, the request type indicates "initial request". However, if an existing PDU session exists between 3GPP access and non-3GPP access, the request type may indicate "existing PDU session".

[0135] The NAS message transmitted by the above UE is encapsulated within an N2 message by the AN. The N2 message is transmitted to the AMF and may include user location information and access technology type information.

[0136] - N1 SM information may include an SM PDU DN request container containing information about PDU session authentication by an external DN.

[0137] 2) AMF may determine that the message corresponds to a request for a new PDU session if the request type indicates an "initial request" and the PDU session ID has not been used for the UE's existing PDU session.

[0138] If the NAS message does not include an S-NSSAI, the AMF can determine the default configured S-NSSAI for the requested PDU session based on the UE subscription. The AMF can store the PDU session ID in association with the SMF ID.

[0139] The above AMF can select SMF.

[0140] 3) The AMF may send the Nsmf_PDUSession_CreateSMContext request message or the Nsmf_PDUSession_UpdateSMContext request message to the selected SMF.

[0141] The above Nsmf_PDUSession_CreateSMContext request message may include SUPI (Subscription Permanent Identifier), DNN, S-NSSAI(s), PDU Session ID, AMF ID, Request Type, PCF ID, Priority Access, N1 SM container, User location information, Access Type, PEI (Permanent Equipment Identifier), GPSI (Generic Public Subscription Identifier), UE presence in LADN service area, Subscription For PDU Session Status Notification, DNN Selection Mode, and Trace Requirements. The above SM container may include a PDU Session Establishment Request message.

[0142] The above Nsmf_PDUSession_UpdateSMContext request message may include SUPI, DNN, S-NSSAI(s), SM Context ID, AMF ID, Request Type, N1 SM container, User location information, Access Type, RAT type, and PEI. The above N1 SM container may include a PDU Session Establishment Request message.

[0143] The AMF ID is used to identify the AMF servicing the UE. N1 SM information may include a PDU session establishment request message received from the UE.

[0144] 4) The SMF sends a subscriber data request message to the UDM. The subscriber data request message may include a subscriber permanent ID and a DNN. The UDM may send a subscriber data response message to the SMF.

[0145] In process 3 above, if the request type indicates "existing PDU session," the SMF determines that the request is due to a handover between 3GPP access and non-3GPP access. The SMF can identify an existing PDU session based on the PDU session ID.

[0146] If the SMF has not yet retrieved SM-related subscription data for UEs associated with the DNN, the SMF can request the subscription data.

[0147] Subscription data may include information on authenticated request types, authenticated SSC modes, and default QoS profiles.

[0148] SMF can verify whether the UE request complies with user subscription and local policies. Alternatively, SMF rejects the UE request via NAS SM signaling (including the relevant SM denial cause) delivered by AMF, and SMF informs AMF that the PDU session ID should be considered released.

[0149] 5) SMF sends the Nsmf_PDUSession_CreateSMContext Response message or the Nsmf_PDUSession_UpdateSMContext Response message to AMF.

[0150] The above Nsmf_PDUSession_CreateSMContext Response message may include a cause, an SM context ID, or an N1 SM container. The above N1 SM container may include a PDU Session Reject.

[0151] In process 3 above, if the SMF received the Nsmf_PDUSession_CreateSMContext request message and the SMF can process the PDU Session Establishment Request message, the SMF creates the SM context and transmits the SM context ID to the AMF.

[0152] 6) Secondary authentication / authorization is performed optionally.

[0153] 7a) When dynamic PCC (Policy and Charging Control) is used for a PDU session, the SMF selects the PCF.

[0154] 7b) The above SMF performs the SM policy association establishment procedure to establish an SM policy association with PCF.

[0155] 8) If the request type in process 3 indicates "initial request", the SMF selects the SSC mode for the PDU session. If process 5 is not performed, the SMF may also select UPF. For request type IPv4 or IPv6, the SMF may assign an IP address / prefix for the PDU session.

[0156] 9) SMF performs the SM policy association modification procedure and provides information on policy control request trees and conditions.

[0157] 10) If the request type indicates "initial request", the SMF can start the N4 session establishment procedure using the selected UPF, otherwise it can start the N4 session modification procedure using the selected UPF.

[0158] 10a) The SMF sends an N4 session establishment / modification request message to the UPF. The SMF may also provide packet detection, enforcement, and reporting rules to be installed in the UPF for the PDU session. If the SMF is assigned CN tunnel information, the CN tunnel information may be provided to the UPF.

[0159] 10b) UPF may respond by sending an N4 session establishment / modification response message. If CN tunnel information is assigned by UPF, CN tunnel information may be provided to SMF.

[0160] 11) The above SMF transmits the Namf_Communication_N1N2MessageTransfer message to the AMF. The above Namf_Communication_N1N2MessageTransfer message may include a PDU Session ID, N2 SM information, and N1 SM container.

[0161] The above N2 SM information may include PDU Session ID, QFI (QoS Flow ID), QoS Profile(s), CN Tunnel Info, S-NSSAI from the Allowed NSSAI, Session-AMBR (Aggregate Maximum Bit Rate), PDU Session Type, User Plane Security Enforcement information, and UE Integrity Protection Maximum Data Rate.

[0162] The above N1 SM container may include a PDU session establishment acceptance message.

[0163] The above PDU session establishment acceptance message may include an authorized QoS rule, SSC mode, S-NSSAI, and an assigned IPv4 address.

[0164] 12) The AMF sends an N2 PDU session request message to the RAN. The message may include N2 SM information and a NAS message. The NAS message may include a PDU session ID and a message accepting the establishment of a PDU session.

[0165] The AMF can transmit a NAS message containing a PDU session ID and a message accepting the establishment of a PDU session. Additionally, the AMF transmits the N2 SM information received from the SMF to the RAN by including it in an N2 PDU session request message.

[0166] 13) The RAN can perform specific signaling exchanges with the UE related to information received from the SMF.

[0167] The RAN also assigns RAN N3 tunnel information to PDU sessions.

[0168] The RAN delivers the NAS message provided in process 10 to the UE. The NAS message may include a PDU session ID and N1 SM information. The N1 SM information may include a PDU session establishment acceptance message.

[0169] The RAN sends a NAS message to the UE only when the necessary RAN resources are configured and the allocation of RAN tunnel information is successful.

[0170] 14) The RAN sends an N2 PDU session response message to the AMF. The message may include a PDU session ID, a cause, and N2 SM information. The N2 SM information may include a PDU session ID, (AN) tunnel information, and a list of allowed / denied QoS profiles.

[0171] - RAN tunnel information may correspond to the access network address of the N3 tunnel corresponding to the PDU session.

[0172] 15) The AMF may send an Nsmf_PDUSession_UpdateSMContext request message to the SMF. The Nsmf_PDUSession_UpdateSMContext request message may include N2 SM information. Here, the AMF may transmit the N2 SM information received from the RAN to the SMF.

[0173] 16a) If an N4 session for the above PDU session has not already been established, the SMF may initiate the N4 session establishment procedure with the UPF. Otherwise, the SMF may initiate the N4 session modification procedure using the UPF. The SMF may provide AN tunnel information and CN tunnel information. CN tunnel information may be provided only if the SMF selected CN tunnel information in process 8.

[0174] 16b) The above UPF can send an N4 session modification response message to the SMF.

[0175] 17) The above SMF sends the Nsmf_PDUSession_UpdateSMContext Response message to the AMF.

[0176] Once this process is complete, the AMF can transmit the relevant events to the SMF.

[0177] 18) The above SMF sends the Nsmf_PDUSession_SMContextStatusNotify message.

[0178] 19) SMF transmits information to the UE via UPF. Specifically, for PDU Type IPv6, SMF can generate an IPv6 Router Advertisement and transmit it to the UE via N4 and UPF.

[0179] 20) If the establishment of a PDU session is unsuccessful during the procedure, the SMF notifies the AMF.

[0180] <PDU 세션 수정 절차>

[0181] There can be two types of PDU (Protocol Data Unit) session establishment procedures as follows.

[0182] - Procedure for establishing a PDU session initiated by the UE

[0183] - A procedure for establishing a PDU session initiated by the network. To this end, the network may send a device trigger message to the UE's application(s).

[0184] Figures 7a and 7b are signal flow diagrams illustrating the modification procedure of an exemplary PDU session.

[0185] PDU sessions can be established / managed based on the PDU session modification procedure.

[0186] The PDU session modification procedure may be initiated by the UE or the network.

[0187] 1a) When initiated by a UE, the UE may initiate a PDU session modification procedure by transmitting a NAS message. The NAS message may include an N1 SM container. The N1 SM container may include a PDU session modification request message, a PDU session ID, and information regarding the UE's integrity protection maximum data rate. The PDU session modification request message may include a PDU session ID, packet filters, information regarding the requested QoS, 5GSM (5G Session Management) core network capability, and the number of packet filters. The UE's integrity protection maximum data rate indicates the maximum data rate at which the UE can support UP integrity protection. The number of packet filters indicates the number of packet filters supported for QoS rules.

[0188] The above NAS message is transmitted via the RAN to the appropriate AMF based on the location information of the UE. Then, the AMF sends the Nsmf_PDUSession_UpdateSMContext message to the SMF. The message may include a Session Management (SM) context ID and an N1 SM container. The N1 SM container may include a PDU session modification request message.

[0189] 1b) If initiated by a PCF among network nodes, the PCF can notify the SMF of the policy change by initiating the SM policy association modification procedure.

[0190] 1c) When initiated by a UDM among network nodes, the UDM can update the subscription data of the SMF by sending a Nudm_SDM_Notification message. The SMF can update the session management subscriber data and send an ACK message to the UDM.

[0191] 1d) When initiated by an SMF among network nodes, the SMF can trigger a QoS update.

[0192] If triggered according to 1a to 1d above, the SMF may perform a PDU session modification procedure.

[0193] 1e) When initiated by an AN among network nodes, the AN may notify the SMF when the AN resource mapped to the QoS flow is released. The AN may send an N2 message to the AMF. The N2 message may include a PDU session ID and N2 SM information. The N2 SM information may include a QFI (QoS flow ID), user location information, and an indication that the QoS flow has been released. The AMF may send an Nsmf_PDUSession_UpdateSMContext message. The message may include an SM context ID and N2 SM information.

[0194] 2) The above SMF may transmit a report on a subscription event by performing the SM policy alliance modification procedure. If the PDU session modification procedure is triggered by 1b or 1d, this step may be skipped. If a dynamic PCC is not deployed on the network, the SMF may apply an internal policy to determine the change of the QoS profile.

[0195] Processes 3 through 7 described below may not be performed if PDU session modification requires only UPF operation.

[0196] 3a) When initiated by a UE or AN, the SMF may respond to the AMF by sending an Nsmf_PDUSession_UpdateSMContext message. The message may include N2 SM information and an N2 SM container. The N2 SM information may include a PDU session ID, QFI, QoS profile, and session-AMBR. The N1 SM container may include a PDU session update command. The PDU session update command may include a PDU session ID, QoS rule, QoS rule action, QoS flow unit QoS parameter, and session-AMBR.

[0197] The above N2 SM information may include information that the AMF must transmit to the AN. The above N2 SM information may include QFI and QoS profiles to notify the AN that one or more QoS flows are added or modified. If a PDU session modification is requested by a UE for which no user plane resource is configured, the above N2 SM information to be transmitted to the AN may include information regarding the establishment of the user plane resource.

[0198] The above N1 SM container may include a PDU session modification command to be transmitted by the AMF to the UE. The PDU session modification command may include QoS rules and QoS flow-level QoS parameters.

[0199] 3b) When initiated by an SMF, the SMF may transmit a Namf_Communication_N1N2MessageTransfer message. The message may include N2 SM information and an N1 SM container. The N2 SM information may include a PDU session ID, QFI, QoS profile, and session-AMBR. The N1 SM container may include a PDU session modification command. The PDU session modification command may include a PDU session ID, QoS rules, and QoS flow level QoS parameters.

[0200] If the above UE is in the CM (Connection Management)-IDLE state and ATC (Asynchronous Type Communication) is enabled, the above AMF may update and save the UE context based on the Namf_Communication_N1N2MessageTransfer message, and then skip steps 3 through 7 described below. When the above UE enters a reachable state, that is, the UE enters the CM-CONNECTED state, the above AMF may transmit an N1 message to synchronize the UE and the UE context.

[0201] 4) The above AMF may transmit an N2 PDU session request message to the AN. The N2 PDU session request message may include N2 SM information received from the SMF and a NAS message. The NAS message may include a PDU session ID and an N1 SM container. The N1 SM container may include a PDU session modification command.

[0202] 5) The AN performs AN signaling exchanges with the UE associated with the information received from the SMF. For example, in the case of NG-RAN, a Connection Reconfiguration procedure may be performed with the UE to modify the necessary AN resources associated with the PDU session.

[0203] 6) The AN sends an N2 PDU session ACK message in response to the received N2 PDU session request. The N2 PDU session ACK message may include N2 SM information and user location information. The N2 SM information may include a list of accepted / rejected QFIs, AN tunnel information, and PDU session ID, etc.

[0204] 7) The above AMF transmits the N2 SM information and user location information received from AN to the SMF via the Nsmf_PDUSession_UpdateSMContext message. Then, the above SMF transmits the Nsmf_PDUSession_UpdateSMContext message to the above AMF.

[0205] 8) The above SMF sends an N4 session modification request message to UPF to update the N4 session of UPF included in the PDU session modification.

[0206] When a new QoS flow occurs, the SMF updates the UL packet detection rule of the new QoS flow together with the UPF.

[0207] 9) The UE transmits a NAS message in response to receiving a PDU session modification command. The NAS message may include a PDU session ID and an N1 SM container. The N1 SM container may include a PDU session modification command ACK.

[0208] 10) The above AN transmits the above NAS message to the above AMF.

[0209] 11) The above AMF may transmit the N1 SM container and user location information received from the above AN to the SMF via the Nsmf_PDUSession_UpdateSMContext message. The above N1 SM container may include a PDU session modification command ACK. The above SMF may transmit the Nsmf_PDUSession_UpdateSMContext response message to the above AMF.

[0210] 12) The above SMF sends an N4 session modification request message to the UPF to update the UPF's N4 session included in the PDU session modification. The message may include an N4 session ID.

[0211] 13) When the SMF interacts with the PCF in process 1b or process 2 above, the SMF may inform the PCF whether or not a PCC decision can be performed through the SM Policy Association Modification procedure.

[0212] The above SMF can notify the entity that requested user location information related to the above PDU session change.

[0213] Network Slicing

[0214] Figure 8 is an example diagram to explain the concept of network slicing.

[0215] Network slicing refers to the division of a single physical network into multiple virtual networks. Each divided network can be operated in a customized and optimized manner for specific application services or subscriber types. Based on cloud computing and virtualization technologies, shared physical network resources can be dynamically and effectively scheduled to logical network slices in response to changes in user requirements.

[0216] A 5G network slice consists of a set of network functions and configurations for a specific use case or business model. Referring to FIG. 5, Network Slice 1 represents an example of 5G network slicing with eMBB (enhanced Mobile Broadband), Network Slice 2 represents V2X (Vehicle to Everything), and Network Slice 3 represents MioT (Massive IoT).

[0217] A single network slice can span several domains, including distributed cloud infrastructure, wireless access networks where transport networks operate, and core networks. The fundamental principle of 5G network slice design is to provide only the customized capabilities necessary to handle traffic for specific use cases. Network slices possess the ability to adapt to changing requirements along with the necessary customized capabilities.

[0218] Meanwhile, according to the Next Generation Mobile Networks (NGMN) definition, network slicing consists of three layers: the Service Instance Layer, the Network Slice Instance Layer, and the Resource Layer. The Service Instance Layer represents end-user services, with each service represented by a Service Instance. The Network Slice Service Instance Layer contains the provided Network Slice Instances, which provide the network characteristics required by the Service Instances. The Resource Layer provides all virtual or physical resources and network functions necessary to create Network Slice Instances.

[0219] Network slicing in 3GPP 5G mobile networks, currently being conducted by the IETF (Internet Engineering Task Force) DetNet (Deterministic Networking) WG (Working Group), operates based on a Core Network (CN), and fundamentally operates based on Network Slice Instance information. A Network Slice Instance refers to information regarding the resources required to form a network slice and the set of Network Function Instances. A single network slice can be utilized across the entire PLMN (Public Land Mobile Network) or across one or more TAs (Tracking Areas). A single Network Slice Instance may be associated with one or more S-NSSAIs (Single-Network Slice Selection Assistance Information), and conversely, a single S-NSSAI may be associated with one or more Network Slice Instances.

[0220] In 3GPP 5G mobile networks, a single network slice is identified by a single S-NSSAI. An S-NSSAI consists of an SST (Slice / Service type) and an SD (Slice Differentiator); while the SST must be included in the S-NSSAI, the SD may be included optionally or omitted. Currently, as shown in Table 2, a total of six SST types and values ​​are defined as standards in the 3GPP technical specifications.

[0221] Slice / Service Type SST value enhanced Mobile Broadband (eMBB) 1 Ultra-Reliable Low Latency Communications (URLLC) 2 MIoT (massive IoT) 3 V2X (Vehicle to Everything) 4 HMTC*(High-performance Machine-Type Communications)(*since Rel-17 onwards) 5 HDLLC**(High Data rate and Low Latency Communications)(**since Rel-18 onwards) 6

[0222] Meanwhile, one or more sets of S-NSSAIs are called NSSAI (Network Slice Selection Assistance Information). During the registration process of a 5G mobile communication network, the terminal requests a network slice connection of the core network using NSSAI, and the core network is responsible for authentication and authorization regarding this network slice connection request from the terminal.

[0223] The terminal may receive and configure or store various forms of NSSAI information from the 5G core network. The Configured NSSAI is the NSSAI configured by receiving it from the serving PLMN, the Default Configured NSSAI is the NSSAI configured by receiving it from the Home PLMN, and the Requested NSSAI is the NSSAI used when the terminal requests a connection to a specific network slice from the core network. The Allowed NSSAI is an NSSAI signifying that the core network permits the terminal to connect to a specific network slice. Additionally, the Subscribed S-NSSAI refers to the S-NSSAI included in the subscriber information.

[0224] The terminal may be configured with a default NSSAI that is pre-configured and stored, provided by the core network, or updated. Each S-NSSAI within the default NSSAI corresponds to an S-NSSAI in the subscriber NSSAI. The S-NSSAI within the terminal's requested NSSAI refers to an S-NSSAI within a previously configured or allowed NSSAI from the network. Consequently, the NSSAI or S-NSSAI generally used by the terminal refers to an NSSAI or S-NSSAI that was previously configured or allowed by the network.

[0225] Meanwhile, the terminal and the 5G mobile communication network receive or utilize NSSAI information during the registration process to support and manage network slice connections. First, the terminal generally possesses a configured NSSAI that is pre-configured and stored, as well as an allowed NSSAI that has been previously permitted by the network for use. If there is no NSSAI previously permitted by the network, there may be no allowed NSSAI. During the registration process to request a connection to a specific network slice, the terminal transmits a Registration Request message to the network containing requested NSSAI information. In this case, the requested NSSAI information refers to the use of the default configured NSSAI information if the terminal does not have a configured NSSAI stored or if no allowed NSSAI is stored—that is, if there is no information on a configured NSSAI that is available for use. If no allowed NSSAI is stored but an available configured NSSAI is stored, the configured NSSAI is used as the requested NSSAI information. Finally, if an available allowed NSSAI is stored, the allowed NSSAI is used as the request NSSAI information. The core network verifies the request NSSAI included in the registration request message transmitted by the terminal, and then responds to the terminal by including all information regarding the configured NSSAI, allowed NSSAI, and rejected NSSAI in the Registration Accept message. The terminal stores the configured NSSAI, allowed NSSAI, and rejected NSSAI information received via the Registration Accept message transmitted from the network and uses them when requesting a network slice connection thereafter. However, in the case of a rejected NSSAI, since it is information that the network has refused to use, the terminal does not, in principle, use the rejected NSSAI.Through this registration request process, the terminal and the network mutually provide NSSAI information for supporting and managing network slice connections, thereby enabling configuration management.

[0226] In addition, when a terminal sends a PDU session setup request message to a network for data transmission, it sends to the network S-NSSAI information regarding the network slice that the application related to data transmission intends to connect to, from the stored allowed NSSAI, and the network checks the S-NSSAI information included in the PDU session setup request message sent by the terminal and, if there is no problem, responds with acceptance.

[0227] In addition, if network slicing-related information, including NSSAI, changes due to changes in subscriber information or mobile network policies, the network may notify the terminal of the changed NSSAI information. In this case, the network may provide the changed NSSAI information to the terminal through a Generic UE Configuration Update procedure. To this end, the AMF transmits a Configuration Update Command message to the terminal containing the configured NSSAI, allowed NSSAI, and rejected NSSAI information, and the terminal updates and stores the received configured NSSAI, allowed NSSAI, and rejected NSSAI information. Subsequently, the terminal performs a network slice connection request using the changed NSSAI information.

[0228] Meanwhile, the recent 3GPP Release 18 standard defines an Alternative S-NSSAI, which refers to a compatible / replaceable S-NSSAI (e.g., S-NSSAI#2) among the existing Allowed NSSAIs when an S-NSSAI (e.g., S-NSSAI#1) becomes unavailable or congested. When an S-NSSAI (e.g., S-NSSAI#1) becomes unavailable or congested in the network, the compatible / replaceable S-NSSAI, i.e., the Alternative S-NSSAI, is provided to the terminal to update it. At this time, the Alternative S-NSSAI can be provided to the terminal to update it using the Generic UE Configuration Update procedure.

[0229] On the other hand, the 3GPP Release 18 standard defines partially allowed NSSAIs. An existing allowed NSSAI refers to an NSSAI that indicates to the network (AMF and / or SMF) that network slicing services associated with the NSSAI information are permitted for the NSSAI requested by the terminal in the registration area where the terminal is registered. In this case, the allowed NSSAI applies to PLMNs or all TA lists in the registration area where the terminal is registered. Conversely, a partially allowed NSSAI applies to PLMNs or some TA lists in the registration area where the terminal is registered. Therefore, in some TAs within the registered zone, network slicing services associated with the partially allowed NSSAI (e.g., Partially Allowed NSSAI#1 - actually a specific S-NSSAI#1) are allowed, but in other TAs, network slicing services associated with the partially allowed NSSAI (e.g., Partially Allowed NSSAI#1 - actually a specific S-NSSAI#1) are not allowed. Updates to this partially allowed NSSAI information are provided through the Registration Procedure or the Generic UE Configuration Update Procedure.

[0230] <Disclosure of the present specification>

[0231] FIG. 9 is a flowchart according to one disclosure of the present specification.

[0232] As can be seen by referring to Fig. 9, the UE sends a registration request message.

[0233] The UE sends a registration request message.

[0234] At this time, the UE may include and transmit the UE MM Core Network Capability within the registration request message. The UE MM Core Network Capability may include information indicating that it supports the UE configuration of network-controlled Slice Usage Policy. Alternatively, the UE MM Core Network Capability may include information indicating that it supports temporarily available network slices.

[0235] The above UE receives a registration acceptance message. Alternatively, the above UE may receive a UE Configuration Update Command.

[0236] The above Registration Accept message or the above UE Configuration Update Command message may include a slice deregistration inactivity timer.

[0237] The slice deregistration inactivity timer mentioned above is set according to the access type.

[0238] When the slice deregistration inactivity timer expires, the UE can locally remove the S-NSSAI (Single Network Slice Selection Assistance Information) from the allowed NSSAI (Network Slice Selection Assistance Information).

[0239] When a replaced S-NSSAI or an alternative S-NSSAI is removed from an allowed NSSAI upon the expiration of the slice deregistration disable timer on a corresponding access type, the UE can perform de-mapping between the replaced S-NSSAI and the alternative S-NSSAI on the access type.

[0240] To this end, the UE can locally remove the mapping between the replaced S-NSSAI and the alternative S-NSSAI.

[0241] a) when a network slice is added to the allowed NSSAI and there are no Protocol Data Unit (PDU) sessions associated with the network slice on the corresponding access type, or b) when the last PDU session associated with the network slice on the same access type is released, the slice deregistration inactivity timer may be started.

[0242] The UE may stop or reset the slice deregistration inactivity timer when at least one PDU session associated with the network slice is successfully established or when the network slice is removed from the allowed NSSAI.

[0243] <Summary of Examples of the Present Specification>

[0244] I. UE Settings for Network Control Slice Usage Policy

[0245] The UE can indicate in the UE MM Core Network Capability that it supports the UE setting of the network control slice usage policy during the registration process. In this case, the AMF determines a slice usage policy for one or more network slices for the UE and controls the use of these network slices by setting this information to the UE along with the configured NSSAI. The AMF may set the network slice usage policy locally, receive a policy from the AM-PCF, or receive information related to AF management timer values ​​from the UDM.

[0246] Network control slice usage policies are provided to the UE via registration acceptance messages or UE settings update command messages and may include the following:

[0247] - For one or more S-NSSAIs in the HPLMN of the configured NSSAI, information indicating whether the UE registers with the network slice only when an application in the network slice requires data transmission (i.e., the UE registers the network slice as needed and can consider the network slice as an on-demand S-NSSAI).

[0248] Optionally, for on-demand S-NSSAIs in the HPLMN of the configured NSSAI, a slice unregister inactive timer that causes UEs to unregister network slices by access type.

[0249] The following may apply regarding the slice unregistration inactive timer:

[0250] a. The UE and AMF start a timer when one of the following conditions occurs: 1) a network slice is added to the Allowed NSSAI and there are no PDU sessions associated with the network slice in that access type, 2) the last PDU session associated with the network slice in the same access type is released.

[0251] b. The UE and AMF stop and reset the timer when at least one PDU session associated with the network slice is successfully established or when the network slice is removed from the Allowed NSSAI.

[0252] c. When the slice unregistration inactivity timer for a network slice of an access type expires, the UE and AMF locally remove the corresponding S-NSSAI from the Allowed NSSAI.

[0253] If there is a mismatch between the UE and the network state, for example, the UE may request a connection from a network slice that is no longer allowed. In this case, the AMF rejects the PDU session setup and provides an updated Allowed NSSAI via the UE setup update command. The UE can then re-register with the network slice if necessary.

[0254] The UE stores the received slice usage policy along with the configured NSSAI of the serving PLMN and maintains it as long as the configured NSSAI for the PLMN is stored. When the configured NSSAI is updated, the AMF can provide the new slice usage policy to the UE.

[0255] II. Support for Network Slice Replacement

[0256] The Network Slice Replacement function is used to temporarily replace the S-NSSAI with an Alternative S-NSSAI when the S-NSSAI (Single Network Slice Selection Assistance Information) is unavailable or congested within the 5th generation mobile communication core network (5GC).

[0257] Network slice replacement can be triggered by the following cases.

[0258] - If the Network Slice Selection Function (NSSF) detects that a specific S-NSSAI is unavailable or congested (e.g., based on analysis results from the Operation and Maintenance (OAM) or Network Data Analytics Function (NWDAF)), the NSSF sends a network slice availability notification for that S-NSSAI to the Access and Mobility Management Function (AMF). This notification may include alternative S-NSSAIs that the AMF can use to replace the S-NSSAI, as well as congestion mitigation information in case the S-NSSAI is congested. Additionally, when the S-NSSAI becomes available again, the NSSF notifies the AMF of this.

[0259] - If the Policy Control Function (PCF) detects that an S-NSSAI is unavailable or congested for a specific User Equipment (UE) (e.g., based on OAM or NWDAF analysis results), the PCF sends an access and mobility-related policy notification to the AMF. This notification may include alternative S-NSSAIs that the AMF can use to replace the relevant S-NSSAI. When the S-NSSAI becomes available again for the relevant UE, the PCF notifies the AMF.

[0260] If the OAM detects that a specific S-NSSAI is unavailable or congested, the OAM notifies the AMF of this fact and provides an alternative S-NSSAI. In this case, if the S-NSSAI is congested, information regarding congestion relief may also be provided. Additionally, when the S-NSSAI becomes available again, the OAM notifies the AMF of this.

[0261] A network slice associated with an alternative S-NSSAI is considered to cover at least the Network Slice Area of ​​Service (NS-AoS) of the network slice to be replaced. If a user terminal (UE) moves to a cell where the replaced S-NSSAI is not supported but is still within the NS-AoS of the alternative S-NSSAI, the AMF removes the S-NSSAI from the Allowed NSSAI if it is included in the Routing Area (RA) and removes it from the Partially Allowed NSSAI if it is outside the Routing Area.

[0262] Additionally, if an area restriction is set on the replaced S-NSSAI, the AMF transmits information to the SMF (Session Management Function) that the corresponding PDU session is subject to the area restriction; subsequently, the AMF and SMF apply the area restriction to the replaced S-NSSAI, and the SMF further deactivates the PDU session if the UE moves out of the AoI (Area of ​​Interest).

[0263] As described above, based on notifications from the Network Slice Selection Function (NSSF), Policy Control Function (PCF), or Operation and Maintenance (OAM), the AMF may determine that it is necessary to replace a specific S-NSSAI with a replacement S-NSSAI. In the case of a roaming situation, the AMF subscribes to network slice availability notifications for the S-NSSAI of the Home PLMN (HPLMN) from the NSSF within the Visited Public Land Mobile Network (VPLMN), and the NSSF of the VPLMN subscribes to the corresponding notifications from the NSSF of the HPLMN.

[0264] Meanwhile, if the above notification is transmitted from the NSSF or OAM and the reason for replacement is due to congestion, the notification additionally includes congestion mitigation information. The details of the congestion mitigation information provided by the NSSF and how such information is utilized by the AMF will be described later.

[0265] The Access and Mobility Management Function (AMF) uses the Alternative S-NSSAI included in the notifications received from the Network Slice Selection Function (NSSF), Operation and Maintenance (OAM), or Policy Control Function (PCF). If the notifications received from the NSSF, OAM, or PCF do not include the Alternative S-NSSAI, the AMF determines the Alternative S-NSSAI based on the local configuration.

[0266] The alternate S-NSSAI must be supported within the Registration Area of ​​the User Terminal (UE). If the AMF cannot determine an alternate S-NSSAI for a specific S-NSSAI, for example, if the OAM or NSSF does not provide an alternate S-NSSAI and such information does not exist within the AMF's local configuration, the AMF may additionally interact with the PCF to determine the alternate S-NSSAI.

[0267] Additionally, if the replacement S-NSSAI is subject to Network Slice-Specific Authentication and Authorization (NSSAA), it may only be used for user terminals included in the Subscribed S-NSSAIs list. In such cases, the AMF must perform the NSSAA procedure on the replacement S-NSSAI before triggering Network Slice Replacement.

[0268] UE (User Equipment) indicates whether the Network Slice Replacement function is supported during the UE Registration procedure.

[0269] To support UEs in the CM-CONNECTED state, and if there are PDU sessions associated with Single Network Slice Selection Assistance Information (S-NSSAI) that require replacement via a specific access type within the UE context, the Access and Mobility Management Function (AMF) provides an Alternative S-NSSAI for the said S-NSSAI as follows:

[0270] Within the Allowed NSSAI on the same Access Type, and

[0271] If not already included, include it within the configured NSSAI,

[0272] Through the UE Configuration Update message, mapping information between the S-NSSAI and the replacement S-NSSAI is provided to the UE.

[0273] In this case, the AMF provides mapping information as follows depending on whether the UE is roaming:

[0274] For non-roaming UEs, the AMF provides the UE with mapping information between the S-NSSAI and the alternate S-NSSAI.

[0275] In the case of a roaming UE, if the S-NSSAI of the VPLMN (Visited Public Land Mobile Network) needs to be replaced, the AMF provides the UE with mapping information between the VPLMN S-NSSAI and the replacement VPLMN S-NSSAI.

[0276] In the case of a roaming UE, if the HPLMN (Home PLMN) S-NSSAI needs to be replaced, the AMF provides the UE with mapping information between the HPLMN S-NSSAI and the replacement HPLMN S-NSSAI.

[0277] Additionally, the AMF provides mapping information between the corresponding S-NSSAI and the replacement S-NSSAI based on the Access Type intended to trigger network slice replacement. The UE stores the received mapping information along with the received Access Type information and uses it only for that Access Type.

[0278] Since Network Slice Replacement is applied regardless of the Access Type, when a replacement occurs, the same Alternative S-NSSAI mapping corresponding to the replaced Single Network Slice Selection Assistance Information is provided for all Access Types included in the Allowed NSSAI where the replaced S-NSSAI is.

[0279] If a replaced S-NSSAI cannot be retained in an Allowed NSSAI or Partially Allowed NSSAI, and the replacement S-NSSAI was used solely for network slice replacement, the AMF further removes the replacement S-NSSAI from the Allowed NSSAI or Partially Allowed NSSAI.

[0280] During mobility between AMFs, the source AMF transmits the replacement S-NSSAI within the User Terminal (UE) context and the mapping information between the replaced S-NSSAI and the replacement S-NSSAI to the new AMF. If the S-NSSAI is subject to network slice replacement, the new AMF compares the requested NSSAI with the received UE context and updates the mapping information for the replaced S-NSSAI for any User Terminals where such information is missing.

[0281] When a user terminal that supports network slice replacement has a NAS signaling connection, that is, is in a CM-CONNECTED state or becomes in a CM-CONNECTED state through a Service Request procedure or a UE registration procedure, the AMF determines that a specific S-NSSAI needs to be replaced, and if there is a PDU session associated with the S-NSSAI, it transmits mapping information between the S-NSSAI and the replacement S-NSSAI to the user terminal through a UE Configuration Update message or a Registration Accept message.

[0282] When an S-NSSAI is replaced with a replacement S-NSSAI, the user terminal associates both the replaced S-NSSAI and the replacement S-NSSAI with the corresponding PDU session. However, the association procedure between the application and the PDU session and the PDU session setup procedure based on the User Route Selection Policy (URSP) are performed based on the replaced S-NSSAI rather than the replacement S-NSSAI.

[0283] When a new PDU session establishment procedure is performed for a specific S-NSSAI (Single Network Slice Selection Assistance Information), the following actions are performed.

[0284] When a User Terminal (UE) receives mapping information between an S-NSSAI and an Alternative S-NSSAI along with an Allowed NSSAI, the UE includes the Alternative S-NSSAI along with the S-NSSAI in a PDU Session Establishment message and transmits it. Upon receiving the message, the Access and Mobility Management Function (AMF) utilizes the SMF Selection Subscription data for the S-NSSAI to be replaced to select an appropriate Session Management Function (SMF) that supports Network Slice Replacement and the Alternative S-NSSAI. Subsequently, the AMF verifies the S-NSSAI and the Alternative S-NSSAI based on the UE context, and then includes both pieces of information in the SMF and transmits them via the Nsmf_PDUSession_CreateSMContext service operation.

[0285] If the UE has not yet received mapping information between the S-NSSAI and the alternate S-NSSAI along with the accepted NSSAI, the UE transmits only the S-NSSAI in the PDU session setup message. At this point, if the AMF determines that the requested S-NSSAI must be replaced with the alternate S-NSSAI and the UE supports network slice replacement, the AMF executes the UE Configuration Update procedure to reconfigure the UE as the alternate S-NSSAI. Subsequently, the AMF continues the PDU session setup procedure using the alternate S-NSSAI and selects an appropriate SMF that supports network slice replacement and the alternate S-NSSAI based on the SMF-selected subscriber information for the replaced S-NSSAI. The AMF provides both the S-NSSAI and the alternate S-NSSAI to the SMF through the Nsmf_PDUSession_CreateSMContext service operation.

[0286] The SMF performs the PDU session establishment procedure using the replacement S-NSSAI and the received DNN (Data Network Name). The SMF queries subscriber data based on the replacement S-NSSAI and DNN, and uses the replacement S-NSSAI value when registering the PDU session with the UDM (Unified Data Management). Subsequently, the SMF includes the replacement S-NSSAI in the N2 SM Information and transmits it to the NG-RAN, and also delivers the replacement S-NSSAI to the UE through the PDU Session Establishment Accept message.

[0287] If an existing PDU session is associated with a Single Network Slice Selection Assistance Information (S-NSSAI) that has been replaced by an Alternative S-NSSAI, the Access and Mobility Management Function (AMF) transmits mapping information between the S-NSSAI and the Alternative S-NSSAI to the UE via a UE Configuration Update message, and then performs an update on the Session Management Function (SMF) of the corresponding PDU session. At this time, the AMF triggers the Nsmf_PDUSession_UpdateSMContext service operation to notify that the PDU session has switched to the Alternative S-NSSAI and transmits the Alternative S-NSSAI to the SMF.

[0288] If the SMF decides to maintain the PDU session (e.g., when the anchor UPF is reusable in the alternate S-NSSAI and SSC mode 1 applies), the SMF transmits the alternate S-NSSAI to the UPF via the N4 message, to the NG-RAN via the N2 message, and to the UE via the PDU Session Modification Command message. The S-NSSAI provided to the (R)AN and UPF is the alternate S-NSSAI.

[0289] If the SMF decides to re-establish the PDU session,

[0290] In the case of SSC mode 3, include the alternative S-NSSAI within the PDU session modification command message and send it to the UE, and

[0291] In the case of SSC mode 2 or SSC mode 1, an alternative S-NSSAI is delivered to the UE via a PDU Session Release message to trigger a PDU session reset.

[0292] At this time, the UE includes both the S-NSSAI and the alternative S-NSSAI in the PDU Session Establishment message and transmits it.

[0293] During the registration procedure, the requested NSSAI may include an alternative S-NSSAI that is not a subscribed NSSAI. Accordingly, the AMF verifies whether the S-NSSAI within the requested NSSAI is either a subscribed S-NSSAI or an alternative S-NSSAI within the UE context, and determines whether to update the UE configuration based on the result.

[0294] If the AMF is notified that the availability of the S-NSSAI has been restored (e.g., congestion has been resolved), and the AMF is configured with an alternate S-NSSAI for the UE, and the UE is in a CM-CONNECTED state and the AMF decides to use the alternate S-NSSAI again, the AMF reconfigures the UE through the UE configuration update procedure (or subsequent registration procedure) as follows:

[0295] Remove mapping information between S-NSSAI and alternative S-NSSAI, and

[0296] If the corresponding replacement S-NSSAI was used solely for network slice replacement purposes, remove it from the allowed NSSAIs.

[0297] Additionally, if an alternate S-NSSAI is not included in the list of subscribed NSSAIs and is not used by any access type, it is removed from the configured NSSAIs as well.

[0298] When the UE is in the CM-IDLE state, the AMF may wait until the UE returns to the CM-CONNECTED state, and when the UE establishes a NAS signaling connection (e.g., a service request procedure or a registration procedure), the AMF reconfigures the UE in the manner described above.

[0299] If the availability of the S-NSSAI is restored or congestion is resolved, and there are existing PDU sessions associated with the replacement S-NSSAI, the AMF sends an update to the SMF of the corresponding PDU session via the Nsmf_PDUSession_UpdateSMContext service operation, causing the PDU session to switch back to the replacement S-NSSAI.

[0300] If the SMF decides to maintain the PDU session (e.g., when the anchor UPF can be reused in the replaced S-NSSAI and SSC mode 1 is applied), the SMF transmits the replaced S-NSSAI to the UPF via the N4 message, to the NG-RAN via the N2 message, and to the UE via the PDU session modification command message, without including the replacement S-NSSAI.

[0301] If the SMF decides to reset the PDU session,

[0302] In the case of SSC mode 3, through the PDU session modification command message,

[0303] In the case of SSC mode 2 or SSC mode 1, through the PDU session release message,

[0304] Deliver the replaced S-NSSAI to the UE, and the UE sends back a PDU session setup message containing only the replaced S-NSSAI.

[0305] Even if a specific S-NSSAI (Single Network Slice Selection Assistance Information) needs to be replaced with an alternative S-NSSAI (Alternative S-NSSAI) during a handover procedure, the handover procedure (including all PDU sessions associated with the S-NSSAI to be replaced) must continue without being affected by network slice replacement. In other words, network slice replacement for an S-NSSAI does not occur during the handover procedure but is performed after the handover procedure is completed.

[0306] In addition, even if a specific S-NSSAI needs to be replaced with a replacement S-NSSAI while the Network Slice Specific Authentication and Authorization (NSSAA) re-authentication process is being performed, the Access and Mobility Management Function (AMF) proceeds with the NSSAA process as is without affecting the network slice replacement, and executes the network slice replacement after the NSSAA process is completed.

[0307] Meanwhile, if Network Slice Admission Control (NSAC) for the Maximum Number of PDU Sessions is configured for the replaced S-NSSAI and / or the replacement S-NSSAI, the Session Management Function (SMF) performs NSAC as follows according to **operator-determined policies:

[0308] The SMF interacts with the NSACF (Network Slice Admission Control Function) for the replaced S-NSSAI, and

[0309] At the same time, it also interacts with the NSACF for the alternative S-NSSAI,

[0310] For example, it processes dynamically to respond to situations requiring an increase in capacity for the replacement S-NSSAI and a decrease in capacity for the replaced S-NSSAI.

[0311] For a specific access type, if the Single Network Slice Selection Assistance Information (S-NSSAI) or Alternative S-NSSAI for that access type is removed from the Allowed NSSAI due to the expiration of the Slice Deregistration Inactivity Timer, the UE (User Terminal) and the AMF (Access and Mobility Management Function) locally remove the mapping information between the replaced S-NSSAI and the Alternative S-NSSAI.

[0312] FIG. 10 is a block diagram showing the configuration of a terminal according to one embodiment of the present specification.

[0313] The UE (100) includes a memory (1010), a processor (1020), a transceiver (1031), a power management module (1091), a battery (1092), a display (1041), an input unit (1053), a speaker (1042) and a microphone (1052), a SIM (subscriber identification module) card, and one or more antennas.

[0314] The processor (1020) may be configured to implement the proposed functions, procedures, and / or methods described herein. Layers of wireless interface protocols may be implemented in the processor (1020). The processor (1020) may include an application-specific integrated circuit (ASIC), other chipsets, logic circuits, and / or data processing devices. The processor (1020) may be an application processor (AP). The processor (1020) may include at least one of a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), and a modem (modulator and demodulator). Examples of the processor (1020) may be a SNAPDRAGON™ series processor manufactured by Qualcomm®, an EXYNOSTM series processor manufactured by Samsung®, an A series processor manufactured by Apple®, a HELIO™ series processor manufactured by MediaTek®, an ATOM™ series processor manufactured by INTEL®, or a corresponding next-generation processor.

[0315] The power management module (1091) manages power for the processor (1020) and / or the transceiver (1031). The battery (1092) supplies power to the power management module (1091). The display (1041) outputs the results processed by the processor (1020). The input unit (1053) receives input to be used by the processor (1020). The input unit (1053) may be displayed on the display (1041). A SIM card is an integrated circuit used to securely store the International Mobile Subscriber Identity (IMSI) and associated keys used to identify and authenticate a subscriber in mobile devices such as mobile phones and computers. Contact information may also be stored on many SIM cards.

[0316] Memory (1010) is operably coupled with the processor (1020) and stores various information for operating the processor (610). Memory (1010) may include ROM (read-only memory), RAM (random access memory), flash memory, memory card, storage medium and / or other storage device. Where the embodiment is implemented in software, the techniques described herein may be implemented as modules (e.g., procedures, functions, etc.) that perform the functions described herein. Modules may be stored in memory (1010) and executed by the processor (1020). Memory (1010) may be implemented inside the processor (1020). Alternatively, memory (1010) may be implemented outside the processor (1020) and may be communically connected to the processor (1020) through various means known in the art.

[0317] The transceiver (1031) is operably coupled with the processor (1020) and transmits and / or receives a wireless signal. The transceiver (1031) includes a transmitter and a receiver. The transceiver (1031) may include a baseband circuit for processing a wireless frequency signal. The transceiver controls one or more antennas to transmit and / or receive a wireless signal. The processor (1020) transmits command information to the transceiver (1031) to transmit a wireless signal, for example, constituting voice communication data, in order to initiate communication. The antennas function to transmit and receive wireless signals. When receiving a wireless signal, the transceiver (1031) may transmit the signal to the processor (1020) for processing and convert the signal to baseband. The processed signal may be converted into audible or readable information output through a speaker (1042).

[0318] The speaker (1042) outputs sound-related results processed by the processor (1020). The microphone (1052) receives sound-related input to be used by the processor (1020).

[0319] The user inputs command information, such as a phone number, by, for example, pressing (or touching) a button on the input unit (1053) or by voice activation using the microphone (1052). The processor (1020) receives this command information and processes it to perform appropriate functions, such as making a call to the phone number. Operational data can be extracted from a SIM card or memory (1010). Additionally, the processor (1020) can display the command information or operation information on the display (1041) for the user's awareness and convenience.

[0320] FIG. 11 shows a block diagram of a processor in which the disclosure of the present specification is implemented.

[0321] As can be seen with reference to FIG. 11, a processor (1020) in which the disclosure of this specification is implemented may include a plurality of circuits to implement the proposed functions, procedures and / or methods described in this specification. For example, the processor (1020) may include a first circuit (1020-1), a second circuit (1020-2), and a third circuit (1020-3). Additionally, although not illustrated, the processor (1020) may include more circuits. Each circuit may include a plurality of transistors.

[0322] The first circuit (1020-1) above can drive a slice deregistration inactivity timer.

[0323] The second circuit (1020-2) can locally remove the S-NSSAI (Single Network Slice Selection Assistance Information) from the allowed NSSAI (Network Slice Selection Assistance Information) when the slice deregistration disable timer expires.

[0324] The third circuit (1020-3) can perform de-mapping between the replaced S-NSSAI and the alternative S-NSSAI in the access type when the replaced S-NSSAI or the alternative S-NSSAI is removed from the allowed NSSAI upon the expiration of the slice deregistration disable timer in the corresponding access type.

[0325] The above processor (1020) may be called an ASIC (application-specific integrated circuit) or an AP (application processor), and may include at least one of a DSP (digital signal processor), a CPU (central processing unit), and a GPU (graphics processing unit).

[0326] The above processor can be mounted on the UE.

[0327] Although preferred embodiments have been described by way of example above, the disclosure of this specification is not limited to such specific embodiments, and may be modified, changed, or improved in various forms within the scope of the spirit and claims of this specification.

[0328] In the exemplary system described above, methods are described based on a flowchart as a series of steps or blocks, but are not limited to the order of the described steps, and some steps may occur in a different order or simultaneously with other steps as described above. Furthermore, a person skilled in the art will understand that the steps shown in the flowchart are not exclusive, and that other steps may be included, or that one or more steps of the flowchart may be omitted without affecting the scope of rights.

[0329] The claims described in this specification may be combined in various ways. For example, the technical features of the method claims in this specification may be combined to be implemented as a device, and the technical features of the device claims in this specification may be combined to be implemented as a method. Furthermore, the technical features of the method claims and the technical features of the device claims in this specification may be combined to be implemented as a device, and the technical features of the method claims and the technical features of the device claims in this specification may be combined to be implemented as a method.

Claims

Claim 1 A method of operation of a user device (UE), comprising the steps of: driving a slice deregistration inactivity timer; locally removing a Single Network Slice Selection Assistance Information (S-NSSAI) from a Network Slice Selection Assistance Information (NSSAI) when the slice deregistration inactivity timer expires; and performing de-mapping between the replaced S-NSSAI and the alternative S-NSSAI in the corresponding access type when the replaced S-NSSAI or the alternative S-NSSAI is removed from the Network Slice Selection Assistance Information (NSSAI) upon the expiration of the slice deregistration inactivity timer. Claim 2 A method according to claim 1, further comprising the step of locally removing the mapping between the replaced S-NSSAI and the alternative S-NSSAI. Claim 3 A method according to claim 1, wherein the slice deregistration disable timer is set according to the access type. Claim 4 A method according to claim 1, wherein a) when a network slice is added to the allowed NSSAI and no Protocol Data Unit (PDU) sessions associated with the network slice exist on the corresponding access type, or b) when the last PDU session associated with the network slice is released on the same access type, the slice unregistering disable timer starts. Claim 5 A method according to claim 1, further comprising the step of stopping or resetting the slice unregistering disable timer when at least one PDU session associated with the network slice is successfully established or when the network slice is removed from the allowed NSSAI. Claim 6 A UE (User Equipment) comprising: a transmitting and receiving unit; and a processor that controls the transmitting and receiving unit to perform an operation, wherein the operation performed by the processor comprises: a step of driving a slice deregistration inactivity timer; a step of locally removing an S-NSSAI (Single Network Slice Selection Assistance Information) from an Allowed NSSAI (Network Slice Selection Assistance Information) when the slice deregistration inactivity timer expires; and a step of performing de-mapping between the replaced S-NSSAI and the alternative S-NSSAI in the access type when the replaced S-NSSAI or the alternative S-NSSAI is removed from the Allowed NSSAI upon the expiration of the slice deregistration inactivity timer in the corresponding access type. Claim 7 A chipset mounted in a UE comprising: at least one processor; and at least one memory that stores instructions and is operabably electrically connected to the at least one processor, wherein the operation performed based on the instruction being executed by the at least one processor comprises: driving a slice deregistration inactivity timer; locally removing a Single Network Slice Selection Assistance Information (S-NSSAI) from a Network Slice Selection Assistance Information (NSSAI) when the slice deregistration inactivity timer expires; and, when a replaced S-NSSAI or an alternative S-NSSAI is removed from the Network Slice Selection Assistance Information (NSSAI) on a corresponding access type upon the expiration of the slice deregistration inactivity timer, performing a de-mapping between the replaced S-NSSAI and the alternative S-NSSAI on the access type. Claim 8 A non-volatile computer-readable storage medium for recording instructions, comprising instructions, wherein the instructions, when executed by one or more processors mounted on the device, cause the one or more processors to perform an operation: the operation comprises: driving a slice deregistration inactivity timer; locally removing a Single Network Slice Selection Assistance Information (S-NSSAI) from a Network Slice Selection Assistance Information (NSSAI) when the slice deregistration inactivity timer expires; and, when a replaced S-NSSAI or an alternative S-NSSAI is removed from the Network Slice Selection Assistance Information (NSSAI) upon the expiration of the slice deregistration inactivity timer on a corresponding access type, performing a de-mapping between the replaced S-NSSAI and the alternative S-NSSAI on the access type.

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