Communication method and device in wireless communication system supporting network slice

Abstract

The disclosure relates to a communication method and device in a wireless communication system supporting network slices, and according to an embodiment of the disclosure, a method performed by a terminal in a wireless communication system supporting network slices includes the steps of: the terminal transmitting a session establishment request message for a first network slice through a first access network; receiving a session establishment rejection message from a network entity for managing sessions for the first network slice through the first access network; and if the session establishment rejection message includes information indicating that the number of sessions exceeds the maximum number of sessions for the first network slice as a reason for rejecting the session establishment request, determining handover to a second access network as a preferred access network of the terminal.

Description

Technical Field

[0001] This disclosure relates to communication methods and devices in wireless communication systems that support network slicing. Background Technology

[0002] To meet the surge in demand for wireless data traffic since the introduction of fourth-generation (4G) communication systems, efforts are underway to develop enhanced fifth-generation (5G) or near-5G communication systems. Therefore, 5G or near-5G communication systems are referred to as super-4G network communication systems or post-LTE systems. For even higher data transmission rates, 5G communication systems are considered to be implemented in ultra-high frequency bands (millimeter waves) (such as 60 GHz). To mitigate path loss in ultra-high frequency bands and increase the reach of radio waves, technologies such as beamforming, massive MIMO, full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive MIMO are considered for 5G communication systems.

[0003] Various technologies are also being developed to enable 5G communication systems to have enhanced network capabilities, such as evolved or advanced small cells, cloud radio access networks (cloud RAN), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, cooperative communication, coordinated multipoint (CoMP), and receive interference cancellation. Other various schemes being developed for 5G systems include, for example, hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC) as advanced coding and modulation (ACM) schemes, and filter bank multicarrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) schemes.

[0004] The Internet, as a human-centric network in which people generate and consume information, is now evolving into the Internet of Things (IoT), in which distributed entities (such as things) exchange and process information without human intervention. The Internet of Everything (IoE), combining IoT technology with cloud servers and big data processing technologies, has emerged. Because the realization of the IoT requires technical elements such as sensing technology, wired / wireless communication and network infrastructure, service interface technology, and security technology, sensor networks, machine-to-machine (M2M) communication, and machine-type communication (MTC) have recently been studied.

[0005] Such an IoT environment can provide intelligent Internet of Things (IT) services, creating new value for human life by collecting and analyzing data generated between connected things. IoT can be applied to various fields through the integration and combination of existing information technology (IT) and various industrial applications, including smart homes, smart buildings, smart cities, smart cars or connected cars, smart grids, healthcare, smart appliances, and advanced medical services.

[0006] Consistent with this, various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, MTC, and M2M communication can be implemented through beamforming, MIMO, and array antennas. Cloud RAN, as an application of the aforementioned big data processing technologies, can also be considered an example of the convergence between 5G and IoT technologies. Summary of the Invention

[0007] Technical issues

[0008] This disclosure provides efficient communication methods and devices in wireless communication systems that support network slicing.

[0009] Furthermore, this disclosure provides a method and apparatus for establishing a session in a wireless communication system that supports network slicing, taking into account the number of sessions.

[0010] Furthermore, this disclosure provides an efficient session handover method and apparatus in a wireless communication system that supports network slicing.

[0011] Technical solutions

[0012] According to embodiments of this disclosure, a method performed by a user equipment (UE) in a wireless communication system supporting network slicing includes: the UE sending a session establishment request message for a first network slice via a first access network; receiving a session establishment rejection message from a network entity managing sessions for the first network slice via the first access network; and determining a handover to a second access network, which is the preferred access network of the UE, if the session establishment rejection message includes information indicating that the maximum number of sessions for the first network slice is exceeded as a reason for rejecting the session establishment request.

[0013] Furthermore, according to embodiments of this disclosure, a method performed by a network entity managing sessions in a wireless communication system supporting network slicing includes: receiving a session establishment request message for a first network slice from a user equipment (UE) via a first access network, identifying whether the current number of sessions using the first network slice exceeds the maximum allowed number of sessions, and, if the current number of sessions exceeds the maximum allowed number of sessions, sending a session establishment rejection message including information indicating that the maximum number of sessions has been exceeded as a reason for rejecting the UE's session establishment request.

[0014] Furthermore, according to embodiments of this disclosure, a UE in a wireless communication system supporting network slicing includes a transceiver and a processor configured to transmit a session establishment request message for a first network slice via a first access network, receive a session establishment rejection message from a network entity managing sessions for the first network slice via the transceiver via the first access network, and determine a handover to a second access network, which is the preferred access network of the UE, if the session establishment rejection message includes information indicating that the maximum number of sessions for the first network slice is exceeded as a reason for rejecting the session establishment request.

[0015] Furthermore, according to embodiments of this disclosure, a network entity managing sessions in a wireless communication system supporting network slicing includes a network interface and a processor. The processor is configured to receive a session establishment request message for a first network slice from a UE via a first access network through the network interface, identify whether the current number of sessions using the first network slice exceeds the maximum allowed number of sessions, and, if the current number of sessions exceeds the maximum allowed number of sessions, send a session establishment rejection message via the network interface including information indicating that the maximum number of sessions has been exceeded as a reason for rejecting the UE's session establishment request. Attached Figure Description

[0016] Figure 1 This is a diagram illustrating the structure of a fifth-generation system (5GS) according to an embodiment of the present disclosure.

[0017] Figure 2 This is a diagram illustrating the Protocol Data Unit (PDU) session establishment process according to an embodiment of the present disclosure.

[0018] Figure 3 This is a diagram illustrating the PDU session establishment process according to an embodiment of the present disclosure.

[0019] Figure 4 This is a diagram illustrating a PDU session switching process according to an embodiment of the present disclosure.

[0020] Figure 5 This is a diagram illustrating an exemplary configuration of a user equipment (UE) 100 according to an embodiment of the present disclosure.

[0021] Figure 6 This is a diagram illustrating the configuration of network entities according to embodiments of the present disclosure. Detailed Implementation

[0022] The operating principles of this disclosure will now be described in detail with reference to the accompanying drawings. Although the terms described below are defined in consideration of the functions in this disclosure, these terms may change according to the intent or habits of the user or operator. Therefore, they should not be defined simply according to the terms actually used, but according to the meaning of each term within the scope of this disclosure.

[0023] For ease of description, terms indicating network entities, terms indicating messages, etc., are provided illustratively as used in this disclosure. Therefore, embodiments of this disclosure are not limited to the terms described below, and other terms with equivalent technical meanings may be used. Furthermore, although this disclosure uses terms and names defined in fifth-generation (5G) system standards, this disclosure can be applied equivalently to systems conforming to other standards without being limited by the terms and names used.

[0024] The devices according to various embodiments of this disclosure can be any of a variety of electronic devices. For example, electronic devices may include, for instance, portable communication devices (e.g., smartphones), portable multimedia devices, portable medical devices, cameras, wearable devices, home appliances, or servers. It should be understood that the various embodiments of this disclosure and the terminology used therein are not intended to limit the technical features set forth herein to specific embodiments, but rather to include various modifications, equivalents, or substitutions for corresponding embodiments. Regarding the description of the drawings, similar reference numerals may be used to refer to similar or related elements. It should be understood that the singular form of a noun corresponding to an item may include one or more things unless the relevant context clearly indicates otherwise.

[0025] As used herein, each of the phrases such as “A or B,” “at least one of A and B,” “at least one of A or B,” “A, B or C,” “at least one of A, B and C,” and “at least one of A, B or C” can be included in any one or all possible combinations of items enumerated together in the corresponding phrase. Terms such as “first” and “second” or “first” and “second” as used herein can be used simply to distinguish corresponding components from other components without otherwise limiting the components (e.g., in terms of importance or order). It should be understood that if an element (e.g., a first element) is referred to as “coupled to another element (e.g., a second element),” “coupled to another element (e.g., a second element),” “connected to another element (e.g., a second element),” or “connected to another element (e.g., a second element),” regardless of whether the terms “operably” or “communicably” are used, this means that the element can be coupled to that other element directly (e.g., wired), wirelessly, or via a third element.

[0026] Various embodiments of this disclosure can be implemented as software including one or more instructions stored in an electronically readable storage medium (e.g., internal or external memory). For example, a processor of an electronic device can invoke and execute at least one of the one or more instructions stored in the storage medium. This allows the machine to be operated to perform at least one function according to the invoked at least one instruction. The one or more instructions may include code generated by a compiler or interpreter-executable code. The electronically readable storage medium may be provided in the form of a non-transitory storage medium. The term "non-transitory" means only that the storage medium is a tangible device and does not include signals (e.g., electromagnetic waves), but this term does not distinguish between cases where data is stored semi-permanently in the storage medium and cases where data is temporarily stored in the storage medium.

[0027] According to embodiments, methods according to various embodiments of this disclosure can be included in and provided therewith in a computer program product. The computer program product can be traded as a product between a seller and a buyer. The computer program product can be distributed in the form of a machine-readable storage medium (e.g., a compact disk read-only memory (CD-ROM)) or via an app store (e.g., the Play Store). TM Alternatively, it can be distributed online (e.g., downloaded or uploaded) directly between two user devices (e.g., smartphones). If distributed online, at least a portion of the computer program product may be temporarily generated or at least temporarily stored in a machine-readable storage medium (such as the memory of a manufacturer's server, app store server, or relay server).

[0028] According to various embodiments, each component may include a single entity or multiple entities, and some of the multiple entities may be separately located in different components. According to various embodiments, one or more of the aforementioned components may be omitted, or one or more other components may be added. Alternatively or additionally, multiple components (e.g., modules or programs) may be integrated into a single component. In this case, according to various embodiments, the integrated component may still perform one or more functions of each of the multiple components in the same or similar manner as performed by a corresponding component among the multiple components prior to integration. According to various embodiments, operations performed by modules, programs, or other components may be performed sequentially, in parallel, repeatedly, or heuristically, or one or more operations may be performed in a different order or omitted, or one or more other operations may be added.

[0029] According to embodiments of this disclosure, an electronic device can refer to various devices used by a user. For example, an electronic device can be a terminal, a user equipment (UE), a mobile station, a subscriber station, a remote terminal, a wireless terminal, or a user equipment. For convenience, embodiments of this disclosure will be described below in the context of a UE as an electronic device. Furthermore, an access network (AN) can provide channels for wireless communication with the electronic device. The AN can be a radio access network (RAN), a base station (BS), an eNB, an eNodeB, a 5G node, a transmit / receive point (TRP), or a fifth-generation NodeB (5GNB).

[0030] This disclosure relates to methods and apparatuses for supporting various services in wireless communication systems. Specifically, this disclosure describes techniques for supporting various services in wireless communication systems by using network slicing to manage sessions. In wireless communication systems supporting network slicing, traffic from different network slices is handled by different Protocol Data Unit (PDU) sessions. A PDU session refers to the association between a data network providing PDU connectivity services and a UE. A network slice can be understood as a logically configured set of network functions (NFs) to support various services with different characteristics (such as large-scale Internet of Things (IoT) and mission-critical services such as Vehicle-to-Everything (V2X)) and to separate different network slices from each other. Therefore, even if communication is interrupted in one network slice, communication in other network slices will not be affected, thereby enabling the provision of stable communication services. In this disclosure, the terms "slice" and "network slice" are used interchangeably with the same meaning.

[0031] In a network environment, when a UE receives various services, it can connect to two or more network slices. NF can be implemented as a network element as a software instance running on hardware, or as a virtualization function instantiated on a suitable platform.

[0032] For ease of description, terms for identifying access nodes, network entities or NFs, messages, interfaces between network entities, and various types of identification information are given by way of example in the description of this disclosure. Therefore, this disclosure is not limited to the terms described below, and these terms may be replaced by other technically equivalent terms.

[0033] For ease of description, this disclosure uses the terms and names defined in the 3GPP LTE and 5G standards. However, this disclosure is not limited to the terms and names mentioned above. Therefore, the terms or names defined in this disclosure may also be applied to systems conforming to other standards.

[0034] For the network technologies described in this disclosure, reference may be made to the standard specifications defined by the International Telecommunication Union (ITU) or 3GPP (e.g., TS 23.501 and TS 23.502). These will be described later. Figure 1 Each of the components included in the network environment shown can be a physical entity, or it can be software that performs a separate function, or hardware that is combined with software.

[0035] Furthermore, according to embodiments of this disclosure, the core network (CN) can manage at least one of the following regarding the UE: subscriber information, mobility, access authorization, session establishment, data packet traffic, or charging policies. The CN may include nodes (or entities), such as User Plane Function (UPF), Access and Mobility Management Function (AMF), Session Management Function (SMF), User Plane Function (UPF), Unified Data Management (UDM), Policy Control Function (PCF) nodes, etc. For a description of the nodes (or entities) included in the CN, reference may be made to the standard specifications defined by 3GPP (e.g., TS 23.501 and TS 23.502).

[0036] For ease of description, the names of NFs (e.g., AMF, SMF, Network Slice Selection Function (NSSF), etc.) are used to indicate the entities used for exchanging information on access control and state management. However, the embodiments of this disclosure also apply even when NFs are actually implemented as instances (AMF instances, SMF instances, NSSF instances, etc.).

[0037] Figure 1 This is a diagram illustrating the system architecture of a 5G system (5GS) according to an embodiment.

[0038] refer to Figure 1 5G CN can include AMF 120, SMF 135, UPF 130, PCF 140, UDM 145, NSSF 160, Network Data Analysis Function (NWDAF) 165, Non-3GPP Function (N3F) 115, etc. Figure 1 In the figure, the reference numerals (such as N2, N3, ...) shown as Nx indicate known interfaces between NFs in the 5G CN, and for related descriptions, please refer to the standard specification (TS 23.501). Therefore, detailed descriptions of these interfaces will be omitted in this document.

[0039] exist Figure 1In this configuration, UE 100 can access the 5G CN via 3GPP Radio Access Network (RAN) 110 and / or non-3GPP (N3GPP) AN 115. UE 100 can connect to AMF 120 via RAN 110 through the N2 interface and to UPF 130 via the N3 interface. RAN 110 may also be referred to as BS, "Access Point (AP)," "eNodeB or eNB," "5G Node," "gNodeB or gNB," or other terms with equivalent technical meanings.

[0040] exist Figure 1 In this context, N3GPP AN 115 serves as the NF for terminating the N2 and N3 interfaces of a UE 100 that has already accessed a non-3GPP access network (e.g., Wi-Fi) not defined by 3GPP. For example, N3GPPAN 115 can be a Non-3GPP Interoperability Function (N3IWF), a Trusted Non-3GPP Gateway Function (TGF), a Wired Access Gateway Function (W-AGF), etc. N3GPP AN 115 can process N2 control plane signaling and N3 user plane packets. A UE connected to N3GPP AN 115 can connect to AMF120 via the N2 interface and to UPF 130 via the N3 interface through N3GPP AN 115.

[0041] exist Figure 1 In this configuration, AMF 120 is the NF that manages the UE's wireless network access and mobility. SMF 135 is the NF that manages the UE's sessions, and session information includes Quality of Service (QoS) information, charging information, and packet processing information. UPF 130 is the NF that processes user traffic (user plane traffic) and is controlled by SMF 135. PCF 140 is the NF that manages operator policies used to provide services in the wireless communication system. UDM 145 is the NF that stores and manages UE subscription information. UDR 150 is the NF that stores and manages data, and the UE subscription information stored in UDR 150 can be used. UDR 150 can store UE subscription information and provide it to UDM 145. Furthermore, UDR 150 can store operator policy information and provide it to PCF 140. Figure 1 In this context, NWDAF 165 is an NF that provides analytical information to operate a 5G system. NWDAF165 can collect data from other NFs or Operations, Administration and Maintenance (OAM) systems included in 5GS, analyze the collected data, and provide the analysis results to other NFs.

[0042] In the NF service provided by the SMF 135 of the management session, the service operations related to the PDU session are defined in the 5G standard (TS 23.502V16.4.0) as shown in Table 1 below.

[0043] Table 1

[0044]

[0045]

[0046] Figure 1 The 5G system architecture supports service-based interfaces, and the service-based interfaces associated with SMF 135 are defined by "Nsmf", as shown in Table 1 above. In Table 1, "Nsmf_PDUSession" represents the service operated in a PDU session, and this service includes creation / deletion / modification operations on the PDU session. These operations can be performed by sending and receiving PDU session request / response messages between AMF 120 and SMF 135.

[0047] Furthermore, as in the example in Table 1, SMF 135 can receive an "Nsmf_PDUSession_CreateSMContext" request message as a PDU session request message from AMF 120, and in response to the received message, send an "Nsmf_PDUSession_CreateSMContext" response message to AMF 120, as an association creation operation between AMF 120 and SMF 135, thereby supporting PDU sessions. Additionally, as in the example in Table 1, SMF 135 can receive an "Nsmf_PDUSession_UpdateSMContext" request message as a PDU session request message from AMF 120, and in response to the received message, send an "Nsmf_PDUSession_UpdateSMContext" response message to AMF 120, as an association update operation between AMF 120 and SMF 135, thereby supporting PDU sessions. For other service operations in Table 1, please refer to the relevant standards; detailed descriptions are omitted here.

[0048] For ease of description, the entities used to exchange access control and state management information will be collectively referred to as NFs. In this disclosure, according to embodiments of this disclosure, an NF can be described as an NF entity, and an NF can be implemented as an instance (such as an AMF instance, an SMF instance, an NSSF instance, etc.).

[0049] In this disclosure, an instance can refer to a state in which a particular NF exists in the form of software code and can be executed through physical and / or logical resource allocation to perform the functionality of an NF from a physical computing system (e.g., a specific computing system existing on a CN). Therefore, an AMF instance, an SMF instance, and an NSSF instance can refer to physical and / or logical resources allocated and available for AMF, SMF, and NSSF operations from a specific computing system existing on a CN, respectively. Thus, physical AMF, SMF, and NSSF devices can use the physical and / or logical resources allocated by a specific computing system existing on the network for AMF, SMF, and NSSF operations to perform the same operations as AMF, SMF, and NSSF instances. Therefore, in embodiments of this disclosure, the term NF (AMF, SMF, UPF, NSSF, NRF, SCP, etc.) can be replaced by NF instance, and vice versa. Similarly, in embodiments of this disclosure, the term network slice can be replaced by network slice instance, and vice versa.

[0050] According to embodiments of this disclosure, in a 5G system defined by 3GPP, a network slice can be referred to as Single Network Slice Selection Auxiliary Information (S-NSSAI). Therefore, a network slice can be identified by the S-NSSAI. The S-NSSAI may include Slice / Service Type (SST) and Slice Distinguishing Feature (SD). The SST may indicate the characteristics of the services supported by the slice (e.g., enhanced mobile broadband (eMBB), Internet of Things (IoT), ultra-reliable low latency communication (URLLC), vehicle-to-everything (V2X), etc.). The SD may be a value used as an additional identifier (ID) for the specific service indicated by the SST.

[0051] NSSAI may include one or more S-NSSAIs. Examples of NSSAIs may include, but are not limited to, configured NSSAIs stored in the UE, requested NSSAIs requested by the UE, permitted NSSAIs that the UE is allowed to use as determined by the NF of the 5G CN (e.g., AMF, NSSF, etc.), and subscribed NSSAIs that the UE has already subscribed to.

[0052] In this disclosure, UE 100 can access at least one of a 3GPP access network or an N3GPP access network. Furthermore, UE 100 can connect to both a 3GPP access network and an N3GPP access network simultaneously for registration in a 5G system.

[0053] Access networks can be replaced by various terms (such as BS, AN, access point (AP), etc.). For example, a 3GPP access network can be a network using licensed frequency bands, while an N3GPP access network can be a network using unlicensed frequency bands; this does not restrict network classification.

[0054] Specifically, UE 100 can access 3GPP RAN 110 and perform a registration procedure with AMF 120. During the registration procedure, AMF 120 can determine the allowed slices (allowed NSSAIs) available to UE 100 that has already accessed 3GPP RAN 110, and assign the allowed slices to UE 100. This is referred to as the first allowed slice. UE 100 can also access N3GPP AN 115 and perform a registration procedure with AMF 120. During the registration procedure, AMF 120 can determine the allowed slices (allowed NSSAIs) available to UE 100 that has already accessed N3GPP AN 115, and assign the allowed slices to UE 100. This is referred to as the second allowed slice. The first allowed slice and the second allowed slice can include the same S-NSSAI or different S-NSSAIs. In this disclosure, the first permitted slice and the second permitted slice may use the same S-NSSAI or different S-NSSAI.

[0055] Mobile communication operators can define the size of available network resources based on network slicing. In this disclosure, this may be referred to as a network slicing policy (or slicing strategy). Slicing policy information may include at least one of the following:

[0056] -S-NSSAI

[0057] - Maximum number of PDU sessions

[0058] - Methods for calculating the maximum number of sessions

[0059] The maximum number of sessions included in the slice policy information according to embodiments of this disclosure can indicate the maximum number of sessions established using S-NSSAI. The NFs (e.g., AMF, SMF, etc.) of the 5G CN can count the number of sessions established during PDU session establishment that use a specific S-NSSAI. According to embodiments of this disclosure, the maximum number of sessions can indicate the maximum number of sessions using that S-NSSAI. For example, if the maximum number of sessions is 100,000 for an eMBB slice, then for a session request including an S-NSSAI indicating an eMBB slice, the 5G CN (or at least one NF in the 5G CN) can allow up to 100,000 sessions.

[0060] According to embodiments of this disclosure, a 5G CN (or at least one NF within a 5G CN) can store and manage slicing policy information within the NF. The slicing policy information stored in the NF can be determined by the mobile operator's policies. The mobile operator can store and update the slicing policy information in the NF in an operation, management, and maintenance (OAM) manner.

[0061] According to embodiments of this disclosure, an NF (or at least one NF in a 5G CN) can obtain slicing policy information from another NF in a 5G CN.

[0062] Figure 2 This is a diagram illustrating the PDU session establishment process according to an embodiment of the present disclosure. Figure 2 In this context, the basic operation of UE 100, AN200 and 201, AMF 120 and SMF 135 is similar to... Figure 1 The corresponding configurations are the same, so detailed descriptions of them will be omitted.

[0063] refer to Figure 2 According to embodiments of this disclosure, the UE 100 can access the first AN 200 and perform the PDU session establishment procedure. The first AN 200 can be 3GPP RAN 110 or N3GPP AN 115.

[0064] In step 210, UE 100 may access the first AN 200 and send a PDU session establishment request message. The PDU session establishment request message may include information about the slice the UE intends to use (i.e., requesting session establishment for its UE). The information about the slice the UE intends to use may include S-NSSAI.

[0065] UE 100 may include information about the preferred access type in the PDU session establishment request message. The preferred access type may indicate the type of AN preferred by UE 100 for the S-NSSAI of the PDU session requested by the UE (e.g., 3GPPAN, N3GPP AN, etc.).

[0066] According to embodiments of this disclosure, a preferred access type can be set based on the AN currently accessed by the UE 100. In this case, the UE 100 can set the preferred access type to the AN type supported by the first AN 200 currently accessed.

[0067] According to another embodiment, a preferred access type can be set regardless of the AN currently accessed by the UE 100. In this case, the UE 100 can set the preferred access type to an AN type supported by the currently accessed first AN 200 or an AN type not supported by the currently accessed first AN 200. For example, although the first AN 200 currently accessed by the UE 100 is a 3GPP AN, the preferred access type can be set to N3GPP AN, or although the first AN 200 currently accessed is an N3GPP AN, the preferred access type can be set to 3GPP AN.

[0068] In step 212, upon receiving a PDU session establishment request message, the first AN 200, according to an embodiment of this disclosure, can select the AMF 120 to which the PDU session establishment request message will be sent. The first AN 200 can send the PDU session establishment request message to the selected AMF 120. In step 214, the AMF 120 can send the PDU session establishment request message to the SMF 135. This PDU session establishment request message includes information included in the PDU session establishment request message in step 210, such as at least one of the following: information about the slice that UE 100 intends to use (i.e., the slice for which session establishment is requested by UE 100) or the preferred access type.

[0069] For example, the Nsmf_PDUSession_CreateSMContext request message described in Table 1 above can be used as a PDU session establishment request message sent by AMF 120 to SMF 135.

[0070] The SMF 135 can process the PDU session request. The SMF 135 can determine whether the requested S-NSSAI will be counted in the maximum number of sessions. For example, the SMF 135 can determine whether the requested S-NSSAI will be counted in the maximum number of sessions based on local configuration stored in the SMF 135. Alternatively, the SMF 135 can determine whether the requested S-NSSAI will be counted in the maximum number of sessions based on subscription information about UE 100 received from the UDM 145. Alternatively, all S-NSSAI requested from the SMF 135 can be counted in the maximum number of sessions. Furthermore, all or some of the S-NSSAI that can be counted in the maximum number of sessions, or the S-NSSAI that will be counted in the maximum number of sessions, can be determined / set in various ways, combining at least one of each operator, each region, each time zone, or each traffic type.

[0071] When the requested S-NSSAI is counted in the maximum number of sessions, in step 216, before determining whether session establishment for UE100 is permitted, SMF 135 may query NF 202 of the 5G CN (or at least one NF in the 5G CN) for slice availability. NF 202 can be any of various entities (or instances), such as PCF 140, AMF 120, SMF135, UPF 130, UDM145, NWDAF 165, NSSF 160, UDR 150, third parties, application functions (AP), and network exposure functions (NEF) for edge computing (not shown).

[0072] Therefore, SMF 135 can send a slice availability request message to NF 202. In another embodiment, when NF 202 is SMF 135, SMF 135 can directly determine the availability of the slice, thus skipping the request / response message sending and receiving in steps 216 and 220. The slice availability request message in step 216 may include at least one of the following: information about the slice (e.g., S-NSSAI, etc.), information about the AN of UE 100 (e.g., 3GPP, N3GPP, etc.), preferred access type, UE location information (e.g., tracking area (TA), etc.), or UE information (e.g., subscription permanent identifier (SUPI), 5G globally unique temporary identifier (5G-GUTI), etc.).

[0073] Meanwhile, when the preferred access type requested / set by UE 100 is included in the Nsmf_PDUSession_CreateSMContext request message sent in step 214, SMF 135 can store the preferred access type.

[0074] According to another embodiment, SMF 135 can obtain information about the preferred access type for S-NSSAI from UDM 145 or PCF 140. SMF 135 can store the preferred access type received from UDM 145 or PCF 140. According to another embodiment, SMF 135 can determine the preferred access type for S-NSSAI based on operator policies (local configuration, local policies, etc.). SMF 135 can store the preferred access type according to operator policies.

[0075] When the information regarding the preferred access type for S-NSSAI is provided by UDM 145 or PCF 140, or when the preferred access type for S-NSSAI is determined based on operator policy, the information regarding the preferred access type may not be included in the request message of step 210. In another embodiment, as described above, when the information regarding the preferred access type is included in the request message of step 210, and the information regarding the preferred access type for S-NSSAI is provided by UDM 145, PCF 140, or operator policy, the preferred access type can be determined based on a predetermined priority among multiple preferred access types.

[0076] In step 218, NF 202 can identify the slicing policy (e.g., S-NSSAI, etc.) received from SMF 135 for the slicing and the current number of sessions for that slicing.

[0077] For example, NF 202 compares the maximum number of sessions included in the slicing policy used for the slice with the current number of sessions for that slice. If the current number of sessions for that slice does not reach the maximum number of sessions (i.e., when the current number of sessions is less than the maximum number of sessions), NF 202 can determine that the slice is currently available. If the target slice is currently available, NF 202 can increment the current number of sessions for that slice by 1 based on the request message in step 216.

[0078] According to another example, NF 202 can compare the maximum number of sessions in the slice policy used for that slice with the current number of sessions for that slice. When the current number of sessions for the target slice has reached the maximum number of sessions (i.e., when the current number of sessions equals the maximum number of sessions), NF 202 can determine that the slice is currently unavailable.

[0079] In step 220, NF 202 may send a slice availability response message to SMF 135. At least one of the following may be included in the slice availability response message: information about the slice (e.g., S-NSSAI, etc.) or information indicating whether the slice is available (e.g., an indication or reason value indicating whether the slice is available or unavailable).

[0080] SMF 135 can determine whether to allow session establishment based on the availability of the slice indicated by NF 202. For example, when NF 202 indicates that the slice (S-NSSAI) is available, SMF 135 can determine to accept the request to establish a PDU session using the slice (S-NSSAI). In another embodiment, for example, when NF 202 sends a message indicating that the slice (S-NSSAI) is unavailable, SMF 135 can determine to reject the request to establish a PDU session using the slice (S-NSSAI).

[0081] In step 222, SMF 135 may send a response message to AMF 120 in response to the PDU session establishment request message received in step 214. For example, the Nsmf_PDUSession_CreateSMContext response message described in can be used as the response message.

[0082] When SMF 135 determines to accept the request to establish a PDU session using Slice-NSASI, the response message sent by SMF 135 to AMF 120 in step 222 may include a PDU session establishment acceptance message (or information indicating acceptance). When SMF 135 determines to reject the request to establish a PDU session using Slice-NSASI, the response message sent by SMF 135 to AMF 120 in step 222 may include a PDU session establishment rejection message (or information indicating rejection).

[0083] Subsequently, in steps 224 and 226, AMF 120 can send the PDU session establishment accept / reject message received from SMF 135 to UE 100 via the first AN 200.

[0084] Figure 3 This is a diagram illustrating the PDU session establishment process according to an embodiment of the present disclosure. Figure 3 In this context, the basic operation of UE 100, AN200 and 201, AMF 120 and SMF 135 is similar to... Figure 1 The corresponding configurations are the same, so detailed descriptions of them will be omitted. Assume that, based on... Figure 2 The process establishes the execution state for the S-NSSAI session requested by UE 100. Figure 3 The process.

[0085] refer to Figure 3 According to embodiments of this disclosure, UE 100 can access the second AN 201 and perform the PDU session establishment procedure. The second AN 201 can be 3GPP RAN 110 or N3GPP AN 115.

[0086] In step 310, UE 100 can access the second AN 201 and send a PDU session establishment request message. The PDU session establishment request message may include information about the slice that UE 100 intends to use (i.e., the slice for which UE 100 requests session establishment). The information about the slice that UE 100 intends to use may include S-NSSAI. Furthermore, S-NSSAI can be communicated via... Figure 2 The S-NSSAI used by UE 100 in the PDU session established via the first AN 200 may be the same or different from that shown in the process.

[0087] Furthermore, UE 100 may include information about the preferred access type in the PDU session establishment request message in step 310. The preferred access type may indicate the type of AN preferred by UE 100 for the S-NSSAI of the PDU session requested by the UE (e.g., 3GPP AN, N3GPP AN, etc.). According to embodiments of this disclosure, the preferred access type can be set based on the AN currently accessed by UE 100. In this case, UE 100 may set the preferred access type to an AN type supported by the currently accessed second AN 201. According to another embodiment, the preferred access type can be set regardless of the AN currently accessed by UE 100. In this case, UE 100 may set the preferred access type to an AN type supported by the currently accessed second AN 201 or an AN type not supported by the currently accessed second AN 201. For example, although the second AN 201 currently accessed by UE 100 is N3GPP AN, the preferred access type may be set to 3GPP AN, or although the second AN 201 currently accessed is 3GPP AN, the preferred access type may be set to N3GPP AN.

[0088] When in Figure 2 When the PDU session establishment request message sent in step 210 includes a preferred access type for S-NSSAI, the UE 100 according to embodiments of this disclosure may not be required to specify the preferred access type for S-NSSAI. Figure 3 The PDU session establishment request message sent in step 310 includes the preferred access type. In another embodiment, it is desirable to change the... Figure 2 In step 210, the UE 100 requesting the preferred access type for S-NSSAI can be in Figure 3 The PDU session establishment request message sent in step 310 includes a changed / updated preferred access type. For example, although UE 100 indicates 3GPP AN as the preferred access type for S-NSSAI in step 210, UE 100 may change the preferred access type to N3GPPAN in step 310.

[0089] Furthermore, in embodiments of this disclosure, UE 100 may set the request type of the PDU session establishment request message to "initial request".

[0090] In step 312, upon receiving a PDU session establishment request message, the second AN 201, according to an embodiment of this disclosure, can select the AMF 120 to which the PDU session establishment request message will be sent. The second AN 201 can send the PDU session establishment request message to the selected AMF 120.

[0091] In step 314, AMF 120 may send a PDU session establishment request message to SMF 135. The PDU session establishment request message includes information included in the PDU session establishment request message in step 310, such as at least one of the following: information about the slice that UE 100 intends to use (i.e., the slice for which session establishment is requested by UE 100) or the preferred access type.

[0092] When the request type of the PDU session establishment request message is "initial request", for example, the Nsmf_PDUSession_CreateSMContext request message described in Table 1 above can be used as a PDU session establishment request message sent by AMF 120 to SMF 135.

[0093] The SMF 135 can process the PDU session request. The SMF 135 can determine whether the requested S-NSSAI will be counted in the maximum number of sessions. For example, the SMF 135 can determine whether the requested S-NSSAI will be counted in the maximum number of sessions based on local configuration stored in the SMF 135. Alternatively, the SMF 135 can determine whether the requested S-NSSAI will be counted in the maximum number of sessions based on subscription information received from the UDM 145. Alternatively, all S-NSSAI requested from the SMF 135 can be counted in the maximum number of sessions. Furthermore, all or some of the S-NSSAI that can be counted in the maximum number of sessions, or the S-NSSAI that will be counted in the maximum number of sessions, can be determined / set in various ways, combining at least one of each operator, each region, each time zone, or each traffic type.

[0094] When the requested S-NSSAI is included in the maximum number of sessions, in step 316, before determining whether session establishment for UE100 is permitted, the SMF 135 may query the NF 202 of the 5G CN (or at least one NF in the 5G CN) for slice availability. To do this, the SMF 135 may send a slice availability request message to NF 202. (As in...) Figure 2As described in the embodiments, the slice availability request message may include at least one of the following: information about the slice (e.g., S-NSSAI, etc.), information about the AN of UE 100 (e.g., 3GPP, N3GPP, etc.), preferred access type, UE location information (e.g., TA, etc.), or UE information (e.g., SUPI, 5G-GUTI, etc.).

[0095] Simultaneously, when the preferred access type requested / set by UE 100 is included in the Nsmf_PDUSession_CreateSMContext request message sent in step 314, SMF 135 can store the preferred access type. For example, if there is no preferred access type for S-NSSAI, SMF 135 can store the preferred access type. Alternatively, if a preferred access type for S-NSSAI exists, SMF 135 can update the stored preferred access type with newly received preferred access type information.

[0096] According to another embodiment, SMF 135 can obtain information about the preferred access type for S-NSSAI from UDM 145 or PCF 140. SMF 135 can store the preferred access type received from UDM 145 or PCF 140. According to another embodiment, SMF 135 can determine the preferred access type for S-NSSAI based on operator policies (local configuration, local policies, etc.). SMF 135 can store the preferred access type according to operator policies.

[0097] When the information regarding the preferred access type for S-NSSAI is provided by UDM 145 or PCF 140, or when the preferred access type for S-NSSAI is determined based on operator policy, the information regarding the preferred access type may not be included in the request message of step 310. In another embodiment, as described above, when the information regarding the preferred access type is included in the request message of step 210, and the information regarding the preferred access type for S-NSSAI is provided by UDM 145, PCF 140, or operator policy, the preferred access type can be determined based on a predetermined priority among multiple preferred access types.

[0098] In step 318, NF 202 can identify the slicing policy (e.g., S-NSSAI, etc.) and the current number of sessions for that slice received from SMF 135.

[0099] For example, NF 202 compares the maximum number of sessions included in the slicing policy used for the slice with the current number of sessions for that slice. If the current number of sessions for that slice has not reached the maximum number of sessions, NF 202 can determine that the slice is currently available. If the target slice is currently available, NF 202 can increment the current number of sessions for that slice by 1 based on the request message in step 316.

[0100] According to another example, NF 202 can compare the maximum number of sessions in the slicing policy used for a slice with the current number of sessions for that slice. When the current number of sessions for the target slice has reached the maximum number of sessions, NF 202 can determine that the slice is currently unavailable.

[0101] In step 320, NF 202 may send a slice availability response message to SMF 135. At least one of the following may be included in the slice availability response message: information about the slice (e.g., S-NSSAI, etc.) or information indicating whether the slice is available (e.g., an indication or reason value indicating whether the slice is available or unavailable).

[0102] SMF 135 can determine whether to allow session establishment based on the availability of the slice indicated by NF 202. For example, when NF 202 indicates that the slice (S-NSSAI) is available, SMF 135 can determine to accept the request to establish a PDU session using the slice (S-NSSAI). In another embodiment, for example, when NF 202 sends a message indicating that the slice (S-NSSAI) is unavailable, SMF 135 can determine to reject the request to establish a PDU session using the slice (S-NSSAI).

[0103] In step 322, SMF 135 may send a response message to AMF 120 in response to the PDU session establishment request message received in step 214. For example, the Nsmf_PDUSession_CreateSMContext response message described in Table 1 may be used as the response message.

[0104] When SMF 135 determines to reject the request to establish a PDU session using Slice-NSASI, the response message sent by SMF 135 to AMF 120 in step 322 may include a PDU session establishment rejection message (or information indicating rejection). When SMF 135 determines to accept the request to establish a PDU session using Slice-NSASI, the response message sent by SMF 135 to AMF 120 in step 322 may include a PDU session establishment acceptance message (or information indicating acceptance).

[0105] Subsequently, in steps 324 and 326, AMF 120 can send the PDU session establishment accept / reject message received from SMF 135 to UE 100 via the second AN 201.

[0106] exist Figure 2 and Figure 3 In some embodiments, the PDU session establishment rejection message may include a reason value indicating the reason for rejection.

[0107] According to embodiments of this disclosure, the value indicating the reason for rejection can be a value indicating that the maximum number of sessions has been reached (e.g., quota overflow, exceeding quota, etc.). SMF 135 can set the value indicating the reason for rejection based on the information received from NF 202 in steps 220 and 320.

[0108] According to another example, the value indicating the reason for rejection could be a value indicating that the maximum number of sessions has been reached and a session handover is available. SMF 135 can set the value indicating the reason for rejection based on at least one of the information received from NF202 in steps 220 and 320, the session-related context of UE 100, or the preferred access type for S-NSSAI.

[0109] For example, when a UE 100 using a PDU session that has already been established for an S-NSSAI via the first AN 200 requests the establishment of a PDU session using the same S-NSSAI via the second AN 201, and the corresponding S-NSSAI is currently unavailable (quota overflow), the SMF 135 can set the value indicating that the maximum number of sessions has been reached but session handover is available to the value indicating the reason for rejection. When the SMF 135 sets the value indicating the reason for rejection in this way, a preferred access type can be considered. For example, the preferred AN type can be determined between the first AN 200 and the second AN 201 based on the preferred access type. If the AN supported by the second AN 201 receiving the PDU session request is preferred over the AN supported by the first AN 200 using the PDU session, the SMF 135 can set the value indicating that session handover is available to the value indicating that the session establishment request is rejected.

[0110] Furthermore, the PDU session establishment rejection message may include a backoff time associated with the rejected S-NSSAI. The backoff time may refer to the period during which UE 100 does not perform a specific operation (e.g., SM NAS signaling). For example, during the backoff time period, UE 100 may not request a new PDU session for that S-NSSAI, which is included in the PDU session establishment rejection message. When described as UE not being allowed to request a new PDU session for an S-NSSAI, this may mean that UE does not send a PDU session establishment request message that includes the S-NSSAI as a network slice and a request type set to "Initial Request". Furthermore, the backoff time does not affect specific operations performed by UE 100. For example, UE 100 may perform a PDU session handover procedure or a PDU session modification procedure during the backoff time period. The PDU session handover process can refer to sending a PDU session establishment request message that includes an S-NSSAI (Network Slice Request) and a request type set to "Existing PDU Session". The PDU session modification process can refer to sending a PDU session modification request message that includes an S-NSSAI (Network Slice Request).

[0111] When a PDU session establishment rejection message is received, the UE 100 can identify, based on the reason value included in the PDU session establishment rejection message, that the maximum number of sessions has been reached and therefore the PDU session request has been rejected.

[0112] UE 100 can determine the next action based on at least one of the information received in steps 226 and 326 and session-related information stored by UE 100.

[0113] According to embodiments of this disclosure, the UE 100 can request a PDU session again after a backoff time included in the PDU session establishment rejection message. After the backoff time has elapsed (after the backoff timer expires), the request type of the PDU session establishment request message can be set to "initial request". The backoff time can be applied to the same Public Land Mobile Network (PLMN) regardless of the AN.

[0114] According to another embodiment, UE 100 can determine a handover from a PDU session established via first AN 200 to second AN 201. UE 100 can request a session handover before the backoff time expires, and the request type of the PDU session establishment request message used to request the handover can be set to "existing PDU session". In this case, the PDU session established via first AN 200 and the PDU session moving to second AN 201 can be sessions using the same S-NSSAI. (See reference...) Figure 4 The session switching process according to embodiments of this disclosure is described in detail.

[0115] As in Figure 2 Implementation examples and / or Figure 3 As described in the embodiments, when the PDU session establishment rejection message includes a reason value indicating the reason for rejection and a value indicating that session switching is available is included as a reason value indicating the rejection of the session establishment request, as will be described later. Figure 4 The switching process can be triggered. Therefore, Figure 2 Implementation examples and / or Figure 3 Implementation examples and Figure 4 The embodiments can be combined to achieve this.

[0116] Figure 4 This is a diagram illustrating a PDU session switching process according to an embodiment of the present disclosure. Figure 4 The implementation is based on the assumption that UE100 is using a PDU session through the first AN 200.

[0117] refer to Figure 4 According to embodiments of the present disclosure, UE 100 can determine the handover from a PDU session used by the first AN 200 to the second AN 201.

[0118] In step 410, UE 100 can perform a session handover by sending a PDU session establishment request message through accessing the second AN 201. UE 100 can set the request type of the PDU session establishment request message to, for example, "existing PDU session".

[0119] The PDU session establishment request message may include the PDU session ID of the PDU session that UE 100 is currently using and subject to session handover.

[0120] The PDU session establishment request message may include information about the slice that UE 100 intends to use. This information may include the S-NSSAI. The S-NSSAI may be the same as the S-NSSAI of the PDU session used via the first AN 200, which UE 100 intends to switch to.

[0121] In step 412, according to an embodiment of this disclosure, upon receiving a PDU session establishment request message, the AMF to which the PDU session establishment request message will be sent can be selected. The second AN 201 can then send the PDU session establishment request message to the selected AMF 120.

[0122] In step 414, AMF 120 may send a PDU session establishment request message to SMF 135. When the request type of the PDU session request message is "existing PDU session", the PDU session establishment request message sent by AMF 120 to SMF 135 may be, for example, the Nsmf_PDUSession_UpdateSMContext request message described in Table 1 above. That is, it may be a request to update the session management (SM) context associated with the PDU session used through the first AN 200, rather than a request to create a new SM context. The SM context may include information related to the PDU session, such as the PDU session ID, the AN type used by the PDU session, etc.

[0123] SMF 135 can process the PDU session request. SMF 135 can determine whether the requested S-NSSAI will be counted in the maximum number of sessions. For example, SMF 135 can determine whether the requested S-NSSAI will be counted in the maximum number of sessions based on local configuration stored in SMF 135. Alternatively, SMF 135 can determine whether the requested S-NSSAI will be counted in the maximum number of sessions based on subscription information received from UDM 145. Alternatively, all S-NSSAI requested from SMF 135 can be counted in the maximum number of sessions.

[0124] When the requested S-NSSAI is to be included in the maximum number of sessions and the request type is "existing PDU session", SMF 135 can identify that the PDU session request is a request to switch an ongoing PDU session established by the first AN 200 to the second AN 201. SMF 135 can identify the session context included in the PDU session establishment request message that corresponds to the PDU session ID (i.e., the PDU session ID of the PDU session currently being used by UE100 and subject to session handover). If a PDU session corresponding to that PDU session ID exists, SMF 135 can determine the handover from the PDU session established and used in the first AN 200 to the second AN 201. Therefore, SMF 135 can determine that a slice availability check related to the maximum number of sessions is not required. In other words, considering the handover from the PDU session used by the first AN 200 to the second AN 201, SMF 135 can determine that it is not necessary to count the number of currently used sessions. Therefore, SMF 135 may omit steps 416 to 420 for checking slice availability. Alternatively, SMF 135 may perform steps 416 to 420 to notify NF 202 that the AN type for the S-NSSAI session in which UE 100 is using a PDU has been changed (e.g., from an AN supported by first AN 200 to an AN supported by second AN 201).

[0125] In step 422, SMF 135 may send a response message to AMF 120 in response to the PDU session establishment request message received in step 414. This response message may be, for example, the Nsmf_PDUSession_UpdateSMContext response message described in Table 1 above.

[0126] If SMF 135 determines to accept the PDU session handover using Slice-NSASI (S-NSASI), the response message sent by SMF 135 to AMF 120 in step 422 may include a PDU session establishment accept message indicating that the session handover is accepted. If SMF 135 decides to reject the PDU session handover using S-NSASI (S-NSASI), the response message sent by SMF 135 to AMF 120 in step 422 may include a PDU session establishment reject message indicating that the session handover is rejected, although not shown.

[0127] In steps 424 and 426, AMF 120 can send a PDU session establishment accept message received from SMF 135 to UE 100 via the second AN 201. The same operation can be performed when a PDU session establishment reject message is sent.

[0128] Subsequently, upon receiving the PDU session establishment acceptance message, UE 100 can recognize that the handover from the PDU session used through the first AN 200 to the second AN 201 was successful.

[0129] In step 428a, the SMF 135, which has already handled the session handover, can determine to release the PDU session established through the first AN 200 and execute the PDU session release procedure.

[0130] Alternatively, in step 428b, the UE 100, which has already identified a successful session handover, can determine to release the PDU session established through the first AN 200 and perform the PDU session release procedure.

[0131] Alternatively, in steps 428c and 428d, each of the SMF 135 that has processed the session handover and the UE 100 that has identified the successful session handover can delete the PDU session information associated with the first AN 200.

[0132] exist Figure 4 In one embodiment, PDU session release can be performed via steps 428a and 428b or steps 428c and 428d.

[0133] Furthermore, according to embodiments of this disclosure, when UE 100 cannot use slices (S-NSSAI) through the first AN 200 (e.g., when S-NSSAI is not included in the NSSAIs allowed by the first AN 200, when S-NSSAI is included in the S-NSSAIs rejected by the first AN 200, when the UE is deregistered through the first AN 200, etc.), Figure 4 The PDU session handover process shown can occur. In this case, Figure 4 In the event of this process, AMF 120 can perform operations to maintain the PDU session-related SM context stored in SMF 135, as follows.

[0134] It has been determined that the AMF 120, which excludes the S-NSSAI from the NSSAIs permitted for the first AN 200, can do so after a specific time has passed (e.g., after a timer expires) rather than immediately.

[0135] Alternatively, it has been determined that the AMF 120, which includes the S-NSSAI in the S-NSSAI rejected by the first AN 200, may do so after a certain time has elapsed (e.g., after a timer expires) rather than immediately.

[0136] Alternatively, it has been determined that the AMF 120 for UE deregistration via the first AN 200 can perform UE deregistration via the first AN 200 after a specific time has elapsed (e.g., after a timer expires) rather than immediately.

[0137] Alternatively, when UE 100 is unable to use the slice (S-NSSAI) via the first AN 200, AMF 120 may instruct SMF 135 to delete the PDU session-related SM context after a specific time has elapsed (e.g., after a timer expires) rather than immediately. AMF 120 may send an Nsmf_PDUSession_UpdateSMContext or Nsmf_PDUSession_ReleaseSMContext request message as shown in Table 1 above to instruct SMF 135 to delete the PDU session-related SM context. Upon receiving the Nsmf_PDUSession_UpdateSMContext or Nsmf_PDUSession_ReleaseSMContext request message, SMF 120 may delete the related SM context.

[0138] Alternatively, when UE 100 is unable to use the slice (S-NSSAI) via the first AN 200, AMF 120 may instruct SMF 135 to delete the PDU session-related SM context after a specific time has elapsed. For example, the Nsmf_PDUSession_UpdateSMContext or Nsmf_PDUSession_ReleaseSMContext request message sent by AMF 120 to instruct SMF 135 to delete the PDU session-related SM context may include time information (timer). Upon receiving the Nsmf_PDUSession_UpdateSMContext or Nsmf_PDUSession_ReleaseSMContext request message, SMF 120 may delete the related SM context after the time included in the received message has elapsed (after the timer expires).

[0139] Figure 5 This is a diagram illustrating an exemplary configuration of a UE 100 according to an embodiment of the present disclosure.

[0140] refer to Figure 5 UE 100 can be implemented to include features for determining whether a device has a certain performance. Figure 1 The processor 502 and transceiver 504 in the configured communication system execute wireless communication using a determined communication method. The processor 501 can control the operation of the transceiver 903, and according to... Figures 1 to 4 The method described in at least one of the embodiments provides overall control to the device to perform session establishment and session switching procedures.

[0141] Figure 6 This is a diagram illustrating the configuration of a network entity (or NF) according to embodiments of this disclosure. The network entity (or NF) can be, in addition to... Figure 1 One of the components in the configuration other than UE 100.

[0142] Figure 6 A network entity (or NF) can be implemented as including elements for determining whether it has Figure 1 The processor 602 and communication interface 604 are configured in a communication system to perform wired / wireless communication using a determined communication method. The processor 602 can control the operation of the communication interface 604, and according to the... Figures 1 to 4 The method described in at least one of the embodiments provides overall control over the device to perform session establishment and session switching procedures.

[0143] Although specific embodiments have been described in detail in this disclosure, it is clear that various modifications are possible without departing from the scope of this disclosure. Therefore, the scope of this disclosure should be defined by the appended claims and their equivalents, and not by the described embodiments.

Claims

1. A method performed by a network entity in a wireless communication system including a 3GPP access network and a non-3GPP access network, the method comprising: Receive a request message from the Session Management Function (SMF), the request message including information about the access type of the network slice associated with the Protocol Data Unit (PDU) session, the access type information including at least one of a 3GPP access network or a non-3GPP access network; Based on information about the access type, determine whether to increase the current number of PDU sessions for network slices; as well as A response message is sent to the SMF, the response message including an indication of the result related to the determination.

2. The method according to claim 1, wherein, The network entity is configured with a maximum number of PDU sessions for Single Network Slice Selection Auxiliary Information (S-NSSAI) that identifies the network slice.

3. The method according to claim 1, wherein, During the network slice-related availability check process, the network entity receives a request message from the SMF that includes information about the access type.

4. The method according to claim 1, wherein, The network entity receives information about the access type from the SMF during the PDU session establishment process.

5. The method according to claim 1, wherein, The non-3GPP access networks include wireless local area networks (WLANs).

6. A network entity in a wireless communication system including a 3GPP access network and a non-3GPP access network, the network entity comprising: transceiver; and The processor is configured as follows: The transceiver receives a request message from the Session Management Function (SMF), the request message including information about the access type of the network slice associated with the Protocol Data Unit (PDU) session, the access type information including at least one of a 3GPP access network or a non-3GPP access network. Based on information about the access type, determine whether to increase the current number of PDU sessions for network slices, and A response message is sent to the SMF, the response message including an indication of the result related to the determination.

7. The network entity according to claim 6, wherein, The network entity is configured with a maximum number of PDU sessions for Single Network Slice Selection Auxiliary Information (S-NSSAI) that identifies the network slice.

8. The network entity of claim 6, wherein the processor is further configured to receive, via the transceiver, a request message including information about the access type from the SMF during a network slice-related availability check.

9. The network entity of claim 6, wherein the processor is further configured to receive information about the access type from the SMF via the transceiver during PDU session establishment.

10. The network entity according to claim 6, wherein, The non-3GPP access networks include wireless local area networks (WLANs).

11. A method performed by a Session Management Function (SMF) in a wireless communication system including a first access network and a second access network, wherein the first access network is one of a non-3GPP access network and a 3GPP access network, and the second access network is the other of a non-3GPP access network and a 3GPP access network, the method comprising: Receives a first request message from the Access and Mobility Management Function (AMF) associated with the Protocol Data Unit (PDU) session establishment process from the User Equipment (UE) to the second access network; and In the case where the first request message is a request for the UE to switch PDU sessions from the first access network to the second access network, a response message is sent to the AMF in response to the receipt of the first request message, without any interaction for network slice availability checks associated with multiple PDU sessions for each network slice.

12. The method according to claim 11, wherein, The first request message includes a request type indicating an existing PDU session for the PDU session switching.

13. The method of claim 11, further comprising, when the first request message is a request for the establishment of a new PDU session for the UE, sending a second request message for the network slice availability check to the network entity responsible for the network slice availability check.

14. The method according to claim 11, wherein, The first request message includes information about the access type of the PDU session that the UE is currently using in the first access network.

15. The method according to claim 11, wherein, The non-3GPP access networks include wireless local area networks (WLANs).

16. A Session Management Function (SMF) in a wireless communication system including a first access network and a second access network, wherein the first access network is one of a non-3GPP access network and a 3GPP access network, and the second access network is the other of a non-3GPP access network and a 3GPP access network, wherein the SMF includes: Communication interface; and The processor is configured as follows: The system receives a first request message from the Access and Mobility Management Function (AMF) via the communication interface, associated with the Protocol Data Unit (PDU) session establishment process from the User Equipment (UE) to the second access network. In the case where the first request message is a request for the UE to switch PDU sessions from the first access network to the second access network, in response to the receipt of the first request message, a response message is sent to the AMF via the communication interface, without any interaction for network slice availability checks associated with the number of PDU sessions for each network slice.

17. The SMF according to claim 16, wherein, The first request message includes a request type indicating an existing PDU session for the PDU session switching.

18. The SMF according to claim 16, wherein, The processor is also configured to send a second request message for the network slice availability check to the network entity responsible for the network slice availability check via the communication interface if the first request message is a request for the establishment of a new PDU session for the UE.

19. The SMF according to claim 16, wherein, The first request message includes information about the access type of the PDU session that the UE is currently using in the first access network.

20. The SMF according to claim 16, wherein, The non-3GPP access networks include wireless local area networks (WLANs).

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