Apparatus and method for managing session in wireless communication system

Abstract

The present disclosure relates to a 5G communication system or a 6G communication system for supporting higher data rates beyond 4G communication systems such as Long Term Evolution (LTE). According to an embodiment, a method performed by a UE is provided. The method includes transmitting information to an access and mobility management function (AMF) indicating that the UE supports a network slice replacement feature, and if there is a protocol data unit (PDU) session associated with a single network slice selection assistance information (S-NSSAI) requiring replacement, receiving a mapping from the AMF of the S-NSSAI to an alternative S-NSSAI.

Description

TECHNICAL FIELD

[0001] The disclosure relates to an apparatus and method for managing a session in a wireless communication system. BACKGROUND

[0002] The 5th-Generation (5G) mobile communication technologies define broad frequency bands so as to achieve a high data rate beyond that of the Long-Term Evolution (LTE) standard. In addition, the 5G mobile communication technologies are implemented to be compatible with the existing infrastructure of the LTE, and to be introduced in the form of a hybrid of frequency bands, including a low frequency band similar to that of the LTE, a mid frequency band similar to that of the Institute of Electrical and Electronics Engineers (IEEE) 802.11ad, and a high frequency band (mmWave), such as 28 GHz and 60 GHz.

[0003] In the early stage of development of the 5G mobile communication technologies, in order to support services and meet performance requirements associated with Enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), there has been ongoing standardization regarding beamforming and massive Multiple-Input Multiple-Output (MIMO) for mitigating radio-wave path loss and increasing radio-wave transmission distances in mmWave, support of a numerology (for example, operating multiple subcarrier spacings) and a dynamic operation of a slot format for efficient utilization of mmWave resources, initial access techniques for supporting multi-beam transmission and wide bands, definition and operation of a Bandwidth Part (BWP), new channel coding methods such as a Low Density Parity Check (LDPC) code for large data transmission and a polar code for highly reliable transmission of control information, Layer 2 (L2) pre-processing, and network slicing for providing a dedicated network dedicated to a specific service.

[0004] At present, in view of services to be supported by the 5G mobile communication technologies, there are ongoing discussions regarding improvement and performance enhancement of initial 5G mobile communication technologies, and there has been ongoing standardization regarding physical layer technologies such as Vehicle-to-Everything (V2X) for assisting in driving determination of an autonomous vehicle based on information about a position and a state of a vehicle transmitted by the vehicle and for enhancing user convenience, New Radio Unlicensed (NR-U) for system operation conforming to various regulatory requirements within an unlicensed band, New Radio (NR) User Equipment (UE) power saving, Non-Terrestrial Network (NTN) for providing coverage in an area where communication with a terrestrial network is not possible as UE-satellite direct communication, and positioning.

[0005] Further, in the field of air interface architecture / protocol, standardization is ongoing regarding technologies such as Industrial Internet of Things (IIoT) for support of new services through interworking and convergence with other industries, Integrated Access and Backhaul (IAB) for providing a node for network service area expansion by supporting a wireless backhaul link and an access link in an integrated manner, mobility enhancement including conditional handover and Dual Active Protocol Stack (DAPS) handover, and two-step random access (two-step Random Access Channel (RACH) for NR) for simplifying a random access procedure. In the field of system architecture / service, standardization is also ongoing regarding 5G baseline architecture (e.g., service based architecture or service based interface) for combining Network Function Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and mobile edge computing (MEC) for receiving services based on UE location.

[0006] When such a 5G mobile communication system is commercialized, connected devices, which have exponentially increased, will be connected to a communication network, and thus it is expected that enhanced functionality and performance of the 5G mobile communication system and integrated operation of connected devices will be necessary. To this end, new research is scheduled, involving extended reality (XR) for efficiently supporting augmented reality (AR), virtual reality (VR), mixed reality (MR), etc., 5G performance improvement and complexity reduction by utilizing artificial intelligence (AI) and machine learning (ML), AI service support, metaverse service support, drone communication, etc.

[0007] Further, such development of 5G mobile communication systems will serve as a basis for not only developing new waveforms for providing coverage of terahertz bands for 6G mobile communication technologies, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), array antennas, and large-scale antennas, lenses and antennas based on metamaterials for improving coverage of terahertz band signals, high-dimensional space multiplexing technology using Orbital Angular Momentum (OAM), and reconfigurable intelligent surfaces (RIS), but also developing full-duplex technology for improving frequency efficiency of 6G mobile communication technologies and ameliorating system networks, AI-based communication technology for system optimization from the design stage by utilizing satellites and AI and internalizing end-to-end AI support functions, and next-generation distributed computing technology for implementing services at a level of complexity exceeding the limit of UE operation capability by utilizing super-high-performance communication and computing resources.

[0008] The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure. SUMMARY

[0009] SOLUTION TO PROBLEM

[0010] Aspects of the disclosure will address at least the above-mentioned problems and / or disadvantages and provide at least the advantages described below. Accordingly, an aspect of the disclosure is to provide a method and apparatus in a wireless communication system.

[0011] According to an embodiment of the disclosure, a method performed by a user equipment (UE) in a wireless communication system is provided. The method can include transmitting, to an access and mobility management function (AMF), information indicating that the UE supports a network slice replacement feature. The method can include receiving, from the AMF, a mapping of a single network slice selection assistance information (S-NSSAI) to a replacement S-NSSAI in case there is a protocol data unit (PDU) session associated with the S-NSSAI that needs to be replaced. In case the S-NSSAI is replaced by the replacement S-NSSAI, the PDU session is associated with both the S-NSSAI and the replacement S-NSSAI.

[0012] According to an embodiment of the disclosure, a user equipment (UE) in a wireless communication system is provided. The UE can include a transceiver; and at least one processor. The at least one processor can be configured to transmit, to an access and mobility management function (AMF), information indicating that the UE supports a network slice replacement feature. The at least one processor can be configured to receive, from the AMF, a mapping of a single network slice selection assistance information (S-NSSAI) to a replacement S-NSSAI in case there is a protocol data unit (PDU) session associated with the S-NSSAI that needs to be replaced. In case the S-NSSAI is replaced by the replacement S-NSSAI, the PDU session is associated with both the S-NSSAI and the replacement S-NSSAI.

[0013] According to an embodiment of the disclosure, a method performed by an access and mobility management function (AMF) in a wireless communication system is provided. The method can include receiving, from a user equipment (UE), information indicating that the UE supports a network slice replacement feature. The method can include determining that a single network slice selection assistance information (S-NSSAI) is to be replaced by a replacement S-NSSAI in case the S-NSSAI becomes unavailable or congested. The method can include transmitting, to the UE, a mapping of the S-NSSAI to the replacement S-NSSAI in case there is a protocol data unit (PDU) session associated with the S-NSSAI that needs to be replaced, the mapping of the S-NSSAI to the replacement S-NSSAI being stored in a UE context in the AMF.

[0014] According to an embodiment of the disclosure, an access and mobility management function (AMF) in a wireless communication system is provided. The AMF can include a transceiver; and at least one processor. The at least one processor can be configured to receive, from a user equipment (UE), information indicating that the UE supports a network slice replacement feature. The at least one processor can be configured to determine that a single network slice selection assistance information (S-NSSAI) is to be replaced by a replacement S-NSSAI in case that the S-NSSAI becomes unavailable or congested. The at least one processor can be configured to transmit, to the UE, a mapping of the S-NSSAI to the replacement S-NSSAI in case that there is a protocol data unit (PDU) session associated with the S-NSSAI that needs to be replaced, wherein the mapping of the S-NSSAI to the replacement S-NSSAI is stored in a UE context in the AMF.

[0015] Additional aspects will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following description and drawings.

[0016] The various embodiments of the present disclosure are disclosed in detail below with reference to the attached drawings. BRIEF DESCRIPTION OF DRAWINGS

[0017] The above and other aspects, features, and advantages of certain embodiments of the present disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0018] Figure 1 is a diagram illustrating a configuration of a single network slice selection assistance information information element (S-NSSAI IE) according to an embodiment of the disclosure;

[0019] Figure 2 illustrates an architecture of a mobile communication system according to an embodiment of the disclosure;

[0020] Figure 3 illustrates a procedure in which an access and mobility management function (AMF) transmits user equipment (UE) policy information to a UE in a wireless communication system according to an embodiment of the disclosure;

[0021] Figure 4 illustrates a procedure of determining and managing replacement slice information in a registration procedure in a wireless communication system according to an embodiment of the disclosure;

[0022] Figure 5 illustrates a new protocol data unit (PDU) session establishment procedure in a wireless communication system according to an embodiment of the disclosure;

[0023] Figure 6A procedure for using an existing PDU session in a wireless communication system according to an embodiment of the disclosure is illustrated;

[0024] Figure 7 FIG. is a diagram illustrating a configuration of a network entity according to an embodiment of the disclosure; and

[0025] Figure 8 FIG. is a diagram illustrating a configuration of a UE (also referred to as a terminal) according to an embodiment of the disclosure.

[0026] Throughout the drawings, the same reference numerals are used for the same elements. DETAILED DESCRIPTION

[0027] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the disclosure. In addition, descriptions of well-known functions and constructions can be omitted for clarity and conciseness.

[0028] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but are merely used to enable a clear and consistent understanding of the disclosure. Accordingly, those of ordinary skill in the art will appreciate that the description of various embodiments of the present disclosure herein includes various specific details that, however, should not be construed as limiting the scope of the disclosure. Rather, the described embodiments of the present disclosure should be understood to include any numerous alternatives, modifications, permutations, additions, subtractions, subdivisions, combinations, and the like as would be appreciated by one of ordinary skill in the art, in light of the disclosure.

[0029] It should be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces.

[0030] Throughout this disclosure the expression “at least one of a, b or c” means only a, only b, only c, both a and b, both a and c, both b and c, all of a, b, and c, or variations thereof.

[0031] Throughout the specification, a layer can also be referred to as an entity.

[0032] Hereinafter, the disclosure relates to an apparatus and method for providing a network slice in a wireless communication system. More specifically, the disclosure describes a technology by which a mobile communication network providing a network slice function can control and manage user equipment (UE) configuration information in a wireless communication system.

[0033] In the 3rd Generation Partnership Project (3GPP) standards, a 5th generation (5G) network system architecture and procedures are standardized. A mobile communication operator can provide various services in a 5G network. In order to provide each service, the mobile communication operator needs to satisfy different service requirements (e.g., latency time, communication range, data rate, bandwidth, reliability, etc.) for each service. To this end, the mobile communication operator can configure a network slice, and can allocate network resources suitable for a specific service for each network slice or each group of network slices. The network resources can indicate a network function (NF) or a logical resource provided by the NF or a radio resource allocation of a base station (BS), etc.

[0034] For example, the mobile communication operator can configure a network slice A for providing a mobile broadband service, can configure a network slice B for providing a vehicle communication service, and can configure a network slice C for providing an Internet of Things (IoT) service. For example, in a 5G network, services can be provided on network slices dedicated to the characteristics of each service. As a differentiator for distinguishing network slices, Single Network Slice Selection Assistance Information (S-NSSAI) defined in 3GPP can be used.

[0035] It should be understood that the blocks in each flowchart and combinations of the flowcharts can be executed by one or more computer programs including computer-executable instructions. The entirety of the one or more computer programs can be stored in a single memory device, or the one or more computer programs can be divided into different parts stored in different multiple memory devices.

[0036] Any function or operation described herein can be processed by one processor or a combination of processors. The one processor or the combination of processors is a circuit that performs processing, and includes a circuit such as an application processor (AP, e.g., a central processing unit (CPU)), a communication processor (CP, e.g., a modem), a graphics processing unit (GPU), a neural processing unit (NPU) (e.g., an artificial intelligence (AI) chip), a wireless fidelity (Wi-Fi) chip, a Bluetooth chip, a global positioning system (GPS) chip, a near field communication (NFC) chip, a connectivity chip, a sensor controller, a touch controller, a fingerprint sensor controller, a display driver integrated circuit (IC), an audio codec chip, a universal serial bus (USB) controller, a camera controller, an image processing IC, a micro processing unit (MPU), a system on chip (SoC), an IC, etc. TM Any function or operation described herein can be processed by one processor or a combination of processors. The one processor or the combination of processors is a circuit that performs processing, and includes a circuit such as an application processor (AP, e.g., a central processing unit (CPU)), a communication processor (CP, e.g., a modem), a graphics processing unit (GPU), a neural processing unit (NPU) (e.g., an artificial intelligence (AI) chip), a wireless fidelity (Wi-Fi) chip, a Bluetooth chip, a global positioning system (GPS) chip, a near field communication (NFC) chip, a connectivity chip, a sensor controller, a touch controller, a fingerprint sensor controller, a display driver integrated circuit (IC), an audio codec chip, a universal serial bus (USB) controller, a camera controller, an image processing IC, a micro processing unit (MPU), a system on chip (SoC), an IC, etc.

[0037] Figure 1 FIG. 1 is a diagram illustrating a configuration of an S-NSSAI information element (IE) according to an embodiment of the disclosure.

[0038] ReferenceFigure 1 One S-NSSAI can include at least one of a home public land mobile network (home PLMN: HPLMN) slice / service type (SST) 116 used by the HPLMN, an HPLMN slice differentiator (SD) 118 used by the HPLMN, an SST 112 used by the serving PLMN, an SD 114 used by the serving PLMN, or a length of the S-NSSAI content 110.

[0039] In a non-roaming case, the SST 112 used by the serving PLMN can be the HPLMN SST 116 used by the HPLMN, and in addition, the SD 114 used by the serving PLMN can be the HPLMN SD 118 used by the HPLMN.

[0040] In a roaming case, the SST 112 used by the serving PLMN can be an SST used by a visited PLMN (VPLMN), and in addition, the SD 114 used by the serving PLMN can be an SD used by the VPLMN.

[0041] Each SST and each SD configuring one S-NSSAI can or can not have a value according to a case.

[0042] A network slice selection assistance information (NSSAI) can consist of one or more NSSAI. Examples of the NSSAI can include a configured NSSAI stored in a UE, a requested NSSAI requested by the UE, an allowed NSSAI determined by an NF (e.g., an AMF, an NSSF, etc.) of a 5G core network, which the UE can use, a subscribed NSSAI to which the UE is subscribed, etc., but this is merely an example, and examples of the NSSAI are not limited to those described above.

[0043] Figure 2 An architecture of a mobile communication system according to an embodiment of the disclosure is illustrated.

[0044] Referring to Figure 2 , a 5G system (5GS) (N13, N35, N22, N12, N8, N10, N36, N14, N11, N7, N5, N14, N15, N1, N2, N4, N3, N9, and N6) can consist of a UE, a new radio (NR) base station (NG-RAN), and a 5G core network. Referring to Figure 2, the 5G core network can be composed of an access and mobility management function (AMF), a session management function (SMF), a user plane function (UPF), a policy control function (PCF), a unified data management (UDM), a network slice selection function (NSSF), an authentication server function (AUSF), a unified data repository (UDR), etc. A user terminal can access the 5G core network via a BS ((R)AN). Hereinafter, the user terminal can be referred to as a UE, and the (R)AN can be referred to as a BS. In addition, the 5G core network can further include an application function (AF) and a data network (DN).

[0045] According to an embodiment of the disclosure, the AMF is an NF that manages wireless network access and mobility with respect to the UE.

[0046] The SMF is an NF that manages a session with respect to the UE, and session information can include quality of service (QoS) information, charging information, packet processing information, etc.

[0047] The UPF is an NF that processes user plane traffic, and is controlled by the SMF.

[0048] The PCF is an NF that manages operator policies for providing services in a wireless communication system. In addition, the PCF can be divided into a PCF that manages access and mobility (AM) policies and UE policies, and a PCF that manages session management (SM) policies. The PCF that manages AM / UE policies and the PCF that manages SM policies can be logically or physically separate NFs, or can be one NF logically or physically.

[0049] The UDM is an NF that stores and manages a UE subscription of the UE.

[0050] The UDR is an NF or a database (DB) that stores and manages data. The UDR can store UE subscription information, and can provide the UE subscription information to the UDM. In addition, the UDR can store operator policy information, and can provide the operator policy information to the PCF.

[0051] The NSSF can be an NF that selects a network slice instance that serves the UE or performs a function of determining an NSSAI.

[0052] The AUSF can be an NF that performs a function of authentication for supporting 3GPP access and non-3GPP access.

[0053] The AF can be an NF that provides a function for a service according to the disclosure.

[0054] The DN can be a data network capable of providing operator services, Internet access, third party services, etc.

[0055] Figure 3 A procedure in which an AMF transmits UE policy information to a UE in a wireless communication system according to an embodiment of the disclosure is illustrated.

[0056] Reference Figure 3 In operation 310, the UE 300 can request the UE policy information from the AMF 302. The procedure can be performed during a UE registration procedure. Figure 3 Alternatively, Figure 3 The procedure can be performed as a standalone procedure.

[0057] In operation 312, the AMF 302 can obtain the UE policy information from the PCF 304. The PCF 304 can retrieve the UE policy information stored in the UDR.

[0058] In operation 314, the AMF 302 can transmit the UE policy information to the UE 300. When the UE policy information transmission illustrated in Figure 3 is performed during a UE registration procedure, the message in operation 314 can be a registration accept message.

[0059] Table 1 below is an example of the UE policy information received by the UE 300.

[0060] [Table 1]

[0061]

[0062] The UE 300 can establish protocol data unit (PDU) sessions based on the received UE policy information. For example, the UE 300 can establish a PDU session corresponding to S-NSSAI-a for transmission and reception of data for App1. The UE 300 can reuse a pre-established PDU session corresponding to S-NSSAI-a to transmit and receive data for App2. The UE 300 can establish a PDU session corresponding to S-NSSAI-b for transmission and reception of data for App3. The UE 300 can establish a PDU session corresponding to S-NSSAI-c for transmission and reception of data for App4. For example, when two or more applications (e.g., App1 and App2) are associated with the same network slice (S-NSSAI-a), the UE 300 can transmit and receive data for the two or more applications on one PDU session mapped to the network slice.

[0063] Figure 4 A procedure in which alternative slice information is determined and managed in a registration procedure in a wireless communication system according to an embodiment of the disclosure is illustrated.

[0064] Reference Figure 4In operation 410, the UE 400 can perform a registration procedure.

[0065] In operation 410, the UE 400 can transmit a registration request message to the AMF 402. The registration request message can include a requested NSSAI that the UE 400 attempts to use. Based on the UE 400 supporting the network slice replacement function, the registration request message can include information indicating that the UE 400 supports the network slice replacement function.

[0066] In operation 412, the AMF 402 processes the registration request for the UE 400 and transmits a request message to the UDM 404 for receiving subscription information from the UDM 404. The request message can be a Nudm_SDM_Get request message and can include an identifier (ID) of the UE (subscriber) 400.

[0067] In operation 414, the UDM 404 generates a response including subscription information of the UE (subscriber) 400 according to the request from the AMF 402. The response message including the UE subscription information can include S-NSSAI information of the subscription of the UE 400.

[0068] In operation 416, the UDM 404 transmits the subscription information of the UE (subscriber) 400 to the AMF 402, and the message used here can be a Nudm_SDM_Get response message.

[0069] In operation 418, other operations for registration can be performed.

[0070] In operation 420, the AMF 402 can determine allowed slices and replacement slices. The AMF 402 can determine the allowed NSSAI based on the requested NSSAI received in operation 410 and the subscribed S-NSSAI received in operation 416.

[0071] In operation 420, the AMF 402 can determine whether at least one S-NSSAI (first S-NSSAI) included in the allowed NSSAI is unavailable or congested. The AMF 402 can determine whether the first S-NSSAI included in the allowed NSSAI is unavailable or congested based on at least one of information received from other NFs (e.g., PCF, NSSF, NWDAF, etc.), information received from OAM, or local configuration information stored in the AMF 402.

[0072] In operation 420, the AMF 402 can determine a replacement S-NSSAI (second S-NSSAI) to replace the unavailable first NSSAI based on information indicating whether the UE 400 supports network slice replacement, information received from the UE 400 in operation 410, and an operator policy (local policy). For example, the AMF 402 can determine a replacement S-NSSAI only for S-NSSAIs for which the PDU session of the UE 400 is established. Alternatively, the AMF 402 can determine a replacement S-NSSAI regardless of the PDU session establishment of the UE 400, i.e., even for S-NSSAIs for which the PDU session of the UE 400 is not established. When the AMF 402 determines to determine a replacement S-NSSAI (second S-NSSAI) to replace the unavailable first S-NSSAI, the AMF 402 can determine information on the replacement S-NSSAI (i.e., second S-NSSAI) to replace the unavailable first S-NSSAI based on at least one of information received from other NFs (e.g., PCF, NSSF, NWDAF, etc.), information received from OAM, and local configuration information stored in the AMF 402. Here, the first S-NSSAI can be a subscribed S-NSSAI of the UE 400. The subscribed S-NSSAI can be stored in the UDM 404 and can be one of the S-NSSAIs included in the message received by the AMF 402 in operation 416. In addition, the second S-NSSAI can or can not be a subscribed S-NSSAI of the UE 400. The AMF 402 can configure replacement slice mapping information (mapping information between the first S-NSSAI and the second S-NSSAI), i.e., replacement NSSAI. Table 2 below shows an example of the replacement NSSAI. The replacement NSSAI can include one or more entries.

[0073] [Table 2]

[0074]

[0075] Table 3 below shows an example of the entry. The entry can include information of one S-NSSAI (first S-NSSAI) and a replacement S-NSSAI (second S-NSSAI) that replaces the S-NSSAI.

[0076] [Table 3]

[0077]

[0078] The AMF 402 can include the alternative S-NSSAI (second S-NSSAI) in the allowed NSSAI in order to use the alternative S-NSSAI (second S-NSSAI). For example, the allowed NSSAI can include both the first S-NSSAI and the second S-NSSAI.

[0079] The AMF 402 can determine whether the second S-NSSAI is included in the configured NSSAI of the UE 400. Based on the second S-NSSAI not being included in the current configured NSSAI (first configured NSSAI) of the UE 400, the AMF 402 can include at least one of the second S-NSSAI and the alternative NSSAI (mapping information between the first S-NSSAI and the second S-NSSAI) in the configured NSSAI (second configured NSSAI).

[0080] The AMF 402 can configure a registration response message including the allowed NSSAI determined in operation 420. Also, the registration response message can include the second configured NSSAI. The registration response message can include the alternative NSSAI (mapping information between the first S-NSSAI and the second S-NSSAI).

[0081] The AMF 402 can store the alternative network slice information. The alternative network slice information is as follows:

[0082] - at least one of an indicator indicating whether to use an alternative S-NSSAI, an allowed NSSAI, a first S-NSSAI (an S-NSSAI to be replaced), a second S-NSSAI (an alternative S-NSSAI for the S-NSSAI), and mapping information between the first S-NSSAI and the second S-NSSAI (an alternative NSSAI)

[0083] - information on a PDU session established for the first S-NSSAI or the second S-NSSAI (e.g., a PDU session ID, etc.) when there is a PDU session established for the first S-NSSAI or the second S-NSSAI

[0084] The AMF 402 can store the alternative network slice information in a UE context associated with the UE 400.

[0085] In operation 422, the AMF 402 can transmit the registration response message to the UE 400, and the message can include at least one of the allowed NSSAI, the configured NSSAI, and the alternative NSSAI (alternative slice mapping information) determined by the AMF 402 in operation 420.

[0086] In operation 424, the UE 400 can store the slice information received from the AMF 402, and can perform an additional operation.

[0087] To describe the following embodiments of the disclosure, in Figure 4 The allowed NSSAI and the replacement NSSAI determined by the AMF 402 in the process of the above-described embodiment are shown in Table 4 below, and the following embodiments will now be described. The first S-NSSAI, the second S-NSSAI, and the third S-NSSAI can be configured in the form of the IE shown in Table 1. Figure 1

[0088] [Table 4]

[0089]

[0090] The AMF 402 can determine to include the first S-NSSAI and the second S-NSSAI in the allowed NSSAI based on the requested NSSAI and the subscribed S-NSSAI. In addition, the AMF 402 can determine that the first S-NSSAI is currently unavailable / congested, and can determine the third S-NSSAI as a replacement S-NSSAI to replace the first S-NSSAI. In addition, the AMF 402 can determine that the second S-NSSAI is currently unavailable / congested, and can determine the third S-NSSAI as a replacement S-NSSAI to replace the second S-NSSAI. Accordingly, the AMF 402 can include the third S-NSSAI in the allowed NSSAI. The AMF 402 can configure the allowed NSSAI.

[0091] The allowed NSSAI can include information of a mapping between the first S-NSSAI to be replaced due to unavailability / congestion and the third S-NSSAI as a replacement S-NSSAI. In addition, the allowed NSSAI can include information of a mapping between the second S-NSSAI to be replaced due to unavailability / congestion and the third S-NSSAI as a replacement S-NSSAI.

[0092] The AMF 402 can store the allowed NSSAI and the replacement NSSAI as a UE context. The AMF 402 can transmit a registration response message including the allowed NSSAI and the replacement NSSAI to the UE 400. The UE 400 can store the received allowed NSSAI and the received replacement NSSAI, and can perform a next operation by using the stored information.

[0093] To describe the following embodiments of the disclosure, in Figure 3 ​A UE routing selection policy (URSP) received by the UE in the process is shown in Table 5 below, and the following embodiments will now be described. According to the UE policy information (URSP), an application 1 (App1) of the UE can use a first S-NSSAI, and an application 2 (App2) can use a second S-NSSAI.

[0094] [Table 5]

[0095]

[0096] Figure 5 A new PDU session establishment procedure in a wireless communication system according to an embodiment of the disclosure is illustrated.

[0097] Referring to Figure 5 In operation 510, the UE 500 can determine to establish a PDU session using App1 based on at least one of the allowed NSSAI, the alternative NSSAI, and the URSP. The UE 500 can determine that the network slice to use App1 is the first S-NSSAI based on the URSP. The UE 500 can determine that the first S-NSSAI is an available network slice based on the allowed NSSAI. The UE 500 can determine that the third S-NSSAI is used as an alternative S-NSSAI as a replacement for the first S-NSSAI based on the alternative NSSAI. The UE 500 can configure a PDU session establishment request message for using App1. The PDU session establishment request message can include at least one of a PDU session ID, the first S-NSSAI, and the third S-NSSAI. The UE 500 can transmit the PDU session establishment request message to the AMF 502.

[0098] In operation 512, the AMF 502 can process the PDU session establishment request of the UE 500. The AMF 502 can perform a PDU session establishment procedure with the SMF 504 supporting the first S-NSSAI and / or the third S-NSSAI requested by the UE 500.

[0099] In operation 514, the AMF 502 can transmit a PDU session establishment accept message to the UE 500. The PDU session establishment accept message can include a PDU session ID and at least one of the first S-NSSAI and the third S-NSSAI.

[0100] The UE 500 can store established PDU session information. For example, the UE 500 can store at least one of the first S-NSSAI and the third S-NSSAI and the first PDU session ID as the PDU session information. The first S-NSSAI can be information transmitted from the UE 500 in operation 510. Alternatively, the first S-NSSAI can be information received by the UE 500 in operation 514. When the S-NSSAI information is not provided in operation 510, the UE 500 can determine the first S-NSSAI based on the alternative NSSAI and the third S-NSSAI information received in operation 514. The third S-NSSAI can be information received by the UE 500 in operation 514. Alternatively, the third S-NSSAI can be information received by the UE 500 in operation 510. The UE 500 can transmit and receive user data of App1 by using the first PDU session.

[0101] In operation 516, the UE 500 can determine whether to establish a new PDU session or reuse an existing PDU session in order to use App2, based on at least one of the allowed NSSAI, the alternative NSSAI, the URSP, and the PDU session information. The UE 500 can determine that the network slice for using App2 is the second S-NSSAI based on the URSP. The UE 500 can determine that the second S-NSSAI is an available network slice based on the allowed NSSAI. The UE 500 can determine that the third S-NSSAI is used as an alternative S-NSSAI as a replacement of the second S-NSSAI based on the alternative NSSAI. The UE 500 can identify, from among the existing sessions currently established by the UE 500, that the PDU session indicated by the first PDU session ID corresponds to the first S-NSSAI (the S-NSSAI to be replaced) and / or the third S-NSSAI (the alternative S-NSSAI) based on the PDU session information. Since the PDU session corresponding to the first S-NSSAI indicated by the first PDU session ID is different from the second S-NSSAI of the network slice for using App2, the UE 500 can determine not to reuse the existing PDU session but to establish a new PDU session. For example, although the alternative S-NSSAI of the PDU session indicated by the first PDU session ID corresponds to the alternative S-NSSAI for App2, the UE 500 can determine not to use the existing PDU session but to establish a new PDU session.

[0102] In operation 518, the UE 500 can configure a PDU session establishment request message for using App2. The PDU session establishment request message can include a PDU session ID and at least one of the second S-NSSAI and the third S-NSSAI. The UE 500 can transmit the PDU session establishment request message to the AMF 502.

[0103] In operation 520, the AMF 502 can process the PDU session establishment request of the UE 500. The AMF 502 can perform a PDU session establishment procedure with the SMF 506 supporting the second S-NSSAI and / or the third S-NSSAI requested by the UE 500.

[0104] In operation 522, the AMF 502 can transmit a PDU session establishment accept message to the UE 500. The PDU session establishment accept message can include the PDU session ID and at least one of the second S-NSSAI and the third S-NSSAI.

[0105] The UE 500 can store the established PDU session information. For example, the UE 500 can store at least one of the second S-NSSAI and the third S-NSSAI and the second PDU session ID as the PDU session information. The second S-NSSAI can be information transmitted from the UE 500 in operation 518. Alternatively, the second S-NSSAI can be information received by the UE 500 in operation 522. When the S-NSSAI information is not provided in operation 518, the UE 500 can determine the second S-NSSAI based on the alternative NSSAI and the third S-NSSAI information received in operation 522. The third S-NSSAI can be information received by the UE 500 in operation 522. Alternatively, the third S-NSSAI can be information transmitted from the UE 500 in operation 518. The UE 500 can transmit and receive user data of App2 by using the second PDU session.

[0106] According to an embodiment of the disclosure, when one alternative S-NSSAI replaces different S-NSSAIs, a plurality of PDU sessions corresponding to the same alternative S-NSSAI can be established.

[0107] In operation 524, the AMF 502 can detect that the first S-NSSAI that is unavailable / congested is available again / less congested. Accordingly, the AMF 502 can determine to use the first S-NSSAI again, and can determine not to use the third S-NSSAI used as a replacement for the first S-NSSAI as a substitute S-NSSAI for the first S-NSSAI. The AMF 502 can determine whether there is a PDU session established for the first S-NSSAI and the third S-NSSAI as a substitute S-NSSAI mapped thereto. For example, the AMF 502 can determine the presence or absence of a PDU session corresponding to the condition based on PDU session information (SM context) stored in the AMF 502. The AMF 502 can determine to transfer / change the first PDU session established for the first S-NSSAI and / or the third S-NSSAI to the first S-NSSAI.

[0108] In operation 526, the AMF 502 can transmit a PDU session update message to the SMF 504 managing the first PDU session. The PDU session update message can include an SM context ID and at least one of the first S-NSSAI and the third S-NSSAI. The SMF 504 can determine to change the first PDU session associated with the third S-NSSAI to the first S-NSSAI.

[0109] In operation 528, the SMF 504 can transmit a PDU session modification request message or a PDU session release request message to the UE 500. The PDU session modification request message or the PDU session release request message can change the first S-NSSAI.

[0110] The UE 500 can change the network slice information included in the SM context related to the first PDU session to the first S-NSSAI. For example, information of the substitute S-NSSAI (the third S-NSSAI) among the network slice information (at least one of the first S-NSSAI and the third S-NSSAI) included in the information related to the first PDU session established in operations 510 to 514 can be deleted.

[0111] The UE 500 can transmit and receive user data of App1 by still using the first PDU session. In addition, the UE 500 can transmit and receive user data of App2 by still using the second PDU session, regardless of the modification of the first PDU session.

[0112] Figure 6 A procedure for using an existing PDU session in a wireless communication system according to an embodiment of the disclosure is illustrated.

[0113] Reference Figure 6In operation 610, the UE 600 can determine to establish a PDU session for using App1 based on at least one of the allowed NSSAI, the alternative NSSAI, and the URSP. The UE 600 can determine that the network slice for using App1 is the first S-NSSAI based on the URSP. The UE 600 can determine that the first S-NSSAI is an available network slice based on the allowed NSSAI. The UE 600 can determine that the third S-NSSAI is used as an alternative S-NSSAI as a replacement for the first S-NSSAI based on the alternative NSSAI. The UE 600 can configure a PDU session establishment request message for using App1. The PDU session establishment request message can include a PDU session ID and at least one of the first S-NSSAI and the third S-NSSAI. The UE 600 can transmit the PDU session establishment request message to the AMF 602.

[0114] In operation 612, the AMF 602 can process the PDU session establishment request of the UE 600. The AMF 602 can perform a PDU session establishment procedure with the SMF 604 supporting the first S-NSSAI and / or the third S-NSSAI requested by the UE 600.

[0115] In operation 614, the AMF 602 can transmit a PDU session establishment accept message to the UE 600. The PDU session establishment accept message can include a PDU session ID and at least one of the first S-NSSAI and the third S-NSSAI.

[0116] The UE 600 can store the established PDU session information. For example, the UE 600 can store at least one of the first S-NSSAI and the third S-NSSAI and the first PDU session ID as the PDU session information. The first S-NSSAI can be information transmitted from the UE 600 in operation 610. Alternatively, the first S-NSSAI can be information received by the UE 600 in operation 614. When the S-NSSAI information is not provided in operation 610, the UE 600 can determine the first S-NSSAI based on the alternative NSSAI and the third S-NSSAI information received in operation 614. The third S-NSSAI can be information received by the UE 600 in operation 614. Alternatively, the third S-NSSAI can be information transmitted from the UE 600 in operation 610. The UE 600 can transmit and receive user data of App1 by using the first PDU session.

[0117] In operation 616, the UE 600 can determine whether to establish a new PDU session or reuse an existing PDU session in order to use App2, based on at least one of the allowed NSSAI, the alternative NSSAI, the URSP, and the PDU session information. The UE 600 can determine that the network slice for using App2 is the second S-NSSAI based on the URSP. The UE 600 can determine that the second S-NSSAI is an available network slice based on the allowed NSSAI. The UE 600 can determine that the third S-NSSAI is used as an alternative S-NSSAI as a replacement of the second S-NSSAI based on the alternative NSSAI. The UE 600 can identify, from among the existing sessions currently established by the UE 600, a PDU session corresponding to the first S-NSSAI (the S-NSSAI to be replaced) and / or the third S-NSSAI (the alternative S-NSSAI) based on the PDU session information indicated by the first PDU session ID. Since the alternative S-NSSAI of the PDU session indicated by the first PDU session ID corresponds to the alternative S-NSSAI for App2, the UE 600 can determine to use the existing PDU session to transmit and receive user data for App2 by using the existing PDU session. For example, although the PDU session indicated by the first PDU session ID is different from the second S-NSSAI for the network slice using App2, the UE 600 can determine not to establish a new PDU session but to reuse the established existing PDU session by using the same alternative S-NSSAI (the third S-NSSAI). The UE 600 can transmit and receive user data for App2 by using the first PDU session.

[0118] According to an embodiment of the disclosure, when one alternative S-NSSAI replaces different S-NSSAIs, one PDU session corresponding to the same alternative S-NSSAI can be associated with different S-NSSAIs, and thus, can be used for transmission and reception of data.

[0119] In operation 618, the AMF 602 can detect that the first S-NSSAI that was unavailable / congested is now available / less congested. Accordingly, the AMF 602 can determine to use the first S-NSSAI again, and can determine not to use the third S-NSSAI used as a replacement for the first S-NSSAI as a substitute S-NSSAI for the first S-NSSAI. The AMF 602 can determine whether there is a PDU session established for the first S-NSSAI and the third S-NSSAI as a substitute S-NSSAI mapped thereto. For example, the AMF 602 can determine the presence or absence of a PDU session corresponding to the condition based on the PDU session information (SM context) stored in the AMF 602. The AMF 602 can determine to transfer / change the first PDU session established for the first S-NSSAI and / or the third S-NSSAI to the first S-NSSAI.

[0120] In operation 620, the AMF 602 can transmit a PDU session update message to the SMF 604 managing the first PDU session. The PDU session update message can include an SM context ID and at least one of the first S-NSSAI and the third S-NSSAI. The SMF 604 can determine to change the first PDU session associated with the third S-NSSAI to the first S-NSSAI.

[0121] In operation 622, the SMF 604 can transmit a PDU session modification request message or a PDU session release request message to the UE 600. The PDU session modification request message or the PDU session release request message can change the first S-NSSAI.

[0122] The UE 600 can change the network slice information included in the SM context related to the first PDU session to the first S-NSSAI. For example, information of the substitute S-NSSAI (the third S-NSSAI) among the network slice information (at least one of the first S-NSSAI and the third S-NSSAI) included in the information related to the first PDU session established in operations 610 to 614 can be deleted.

[0123] The UE 600 can transmit and receive user data of App1 by still using the first PDU session.

[0124] In operation 624, the UE 600 can not be able to transmit and receive user data of App2 by using the first PDU session due to the modification of the first PDU session. Accordingly, the UE 600 can determine to establish a new PDU session for using App2.

[0125] In operation 626, the UE 600 can configure a PDU session establishment request message for using App2. The PDU session establishment request message can include a PDU session ID and at least one of a second S-NSSAI and a third S-NSSAI. The UE 600 can transmit the PDU session establishment request message to the AMF 602.

[0126] In operation 628, the AMF 602 can process the PDU session establishment request of the UE 600. The AMF 602 can perform a PDU session establishment procedure with the SMF 606 supporting the second S-NSSAI and / or the third S-NSSAI requested by the UE 600.

[0127] In operation 630, the AMF 602 can transmit a PDU session establishment accept message to the UE 600. The PDU session establishment accept message can include a PDU session ID and at least one of a second S-NSSAI and a third S-NSSAI.

[0128] The UE 600 can store the established PDU session information. For example, the UE 600 can store at least one of the second S-NSSAI and the third S-NSSAI and the second PDU session ID as the PDU session information. The second S-NSSAI can be information transmitted from the UE 600 in operation 626. Alternatively, the second S-NSSAI can be information received by the UE 600 in operation 630. In operation 626, when the S-NSSAI information is not provided, the UE 600 can determine the first S-NSSAI based on the alternative NSSAI and the third S-NSSAI information received in operation 630. The third S-NSSAI can be information received by the UE 600 in operation 630. Alternatively, the third S-NSSAI can be information transmitted from the UE 600 in operation 626. The UE 600 can transmit and receive user data of App2 by using the second PDU session.

[0129] According to an embodiment of the disclosure, the allowed NSSAI and the alternative NSSAI determined by the AMF according to the mobile communication operator policy can be as shown in Table 6 below. For example, different network slices (the first S-NSSAI and the second S-NSSAI) can be replaced with different alternative S-NSSAI (the third S-NSSAI and the fourth S-NSSAI). Accordingly, the UE 600 can establish different PDU sessions for the respective slices (the first S-NSSAI and the second S-NSSAI) in a similar manner to the procedure shown in Table 6. Figure 5

[0130] [Table 6]

[0131] ​

[0132] The UE according to an embodiment of the disclosure can not include the S-NSSAI information in the PDU session establishment request message of operation 510 or 610.

[0133] The AMF can perform other operations for the PDU session establishment in operation 512 or 612.

[0134] To perform the PDU session establishment procedure, the AMF can select an available or non-congested S-NSSAI from among the S-NSSAIs included in the allowed NSSAI. The AMF can transmit the selected S-NSSAI to the SMF in order to establish the PDU session.

[0135] Based on all the S-NSSAIs included in the allowed NSSAI being unavailable or congested, the AMF can not select an S-NSSAI. Accordingly, the AMF can reject the PDU session establishment request. In this case, the message of operation 514 or 614 can be a PDU session establishment reject message. Further, the AMF can determine to reconfigure the UE. The AMF can transmit an alternative NSSAI to the UE. The alternative NSSAI can include mapping information related to the first S-NSSAI and the third S-NSSAI. The alternative NSSAI can be transmitted to the UE during a registration procedure or a UE configuration update procedure. The UE can perform the PDU session establishment request again based on the received alternative NSSAI. More specifically, the UE can include the first S-NSSAI and the third S-NSSAI in the PDU session establishment request message, and can transmit the PDU session establishment request message to the AMF. The AMF can process the PDU session establishment request according to the procedures described with reference to Figure 5 or Figure 6

[0136] ​Alternatively, when all S-NSSAIs included in the allowed NSSAI are not available or congested, the AMF can select one S-NSSAI (first S-NSSAI) from among the S-NSSAIs included in the allowed NSSAI and can determine a replacement S-NSSAI (third S-NSSAI) to replace the selected S-NSSAI (first S-NSSAI). The AMF can transmit the first S-NSSAI and the third S-NSSAI to the SMF in order to establish the PDU session. The message of operation 514 or 614 can include the third S-NSSAI. Further, the AMF can determine to reconfigure the UE. The AMF can transmit a replacement NSSAI to the UE. The replacement NSSAI can include mapping information related to the first S-NSSAI and the third S-NSSAI. The replacement NSSAI can be transmitted to the UE during a registration procedure or a UE configuration update procedure. Based on the replacement NSSAI and the third S-NSSAI included in the PDU session establishment accept message, the UE can determine that the AMF selected the first S-NSSAI for the PDU session establishment and selected the third S-NSSAI as a replacement S-NSSAI because the first S-NSSAI is not available or congested.

[0137] Figure 7 FIG. 1 is a diagram illustrating a configuration of a network entity according to an embodiment of the disclosure.

[0138] Referring to Figure 7 , the network entity 700 can be any one of an AMF, an SMF, a UPF, a PCF, a UDM, an NSSF, an AUSF, a UDR, an AF, and a DN. The network entity 700 of the disclosure can correspond to the network entity of the above-described Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 .

[0139] Referring to Figure 7 , the network entity 700 of the disclosure can include a transceiver 710, a memory 720, and a processor 730. The processor 730, the transceiver 710, and the memory 720 of the network entity 700 can operate according to the method of operating the network entity 700. However, the elements of the network entity 700 are not limited to the above-described examples. The network entity 700 can include more elements than the foregoing elements, or can include fewer elements than the foregoing elements. Further, at least one of the processor 730, the transceiver 710, and the memory 720 can be implemented as one chip. The network entity 700 can include an NF such as an AMF, an SMF, a UPF, a PCF, a UDM, an NSSF, an AUSF, a UDR, an AF, a DN, and the like. Further, the network entity 700 can include a BS.

[0140] The receiver of the network entity 700 and the transmitter of the network entity 700 can be collectively referred to as a transceiver 710, and the transceiver 710 can transmit or receive a signal to or from a UE or other network entity. Here, the transmitted or received signal can include control information and data. To this end, the transceiver 710 can include a radio frequency (RF) transmitter for up-converting and amplifying a frequency of a signal to be transmitted, and an RF receiver for low-noise amplification and down-converting a frequency of a received signal. However, this is merely an example of the transceiver 710, and thus the elements of the transceiver 710 are not limited to the RF transmitter and the RF receiver. The transceiver 710 can include a wired / wireless transceiver, and can include various configurations for transmitting and receiving a signal.

[0141] In addition, the transceiver 710 can receive and output a signal to the processor 730 via a communication channel (e.g., a wireless channel), and can transmit a signal output from the processor 730 via the communication channel.

[0142] In addition, the transceiver 710 can receive and output a signal to the processor 730 via a communication channel (e.g., a wireless channel), and can transmit a signal output from the processor 730 via the communication channel.

[0143] The memory 720 can store programs and data required for the operation of the network entity 700. In addition, the memory 720 can store control information or data included in a signal obtained by the network entity 700. The memory 720 can be implemented as a storage medium including a read-only memory (ROM), a random access memory (RAM), a hard disk, a compact disk (CD)-ROM, a digital versatile disk (DVD), etc., or any combination thereof.

[0144] The processor 730 can control a series of processes to allow the network entity 700 such as a SN to operate according to the aforementioned embodiments of the disclosure. The processor 730 can include at least one processor. The method according to the embodiments of the disclosure described herein or in the appended claims can be implemented as hardware, software, or a combination of hardware and software.

[0145] Figure 8 FIG. 1 is a diagram illustrating a configuration of a UE according to an embodiment of the disclosure. The UE of the disclosure can correspond to the UE of the above-described Figure 3 , Figure 4 , Figure 5 and Figure 6 .

[0146] Referring to Figure 8The UE 800 of the disclosure can include a transceiver 810, a memory 820, and a processor 830. The processor 830, the transceiver 810, and the memory 820 of the UE 800 can operate according to the communication method of the UE 800. However, the elements of the UE 800 are not limited to the aforementioned examples. The UE 800 can include more elements than the aforementioned elements, or can include less elements than the aforementioned elements. Furthermore, the processor 830, the transceiver 810, and the memory 820 can be implemented as one chip.

[0147] The receiver of the UE 800 and the transmitter of the UE 800 can be collectively referred to as the transceiver 810, and the transceiver 810 can transmit or receive a signal to or from a BS or other network entity. The signal transmitted or received by the UE 800 to or from the BS or network entity can include control information and data. To this end, the transceiver 810 can include an RF transmitter for up-converting and amplifying a frequency of a signal to be transmitted, and an RF receiver for low-noise amplification and down-converting a frequency of a received signal. However, this is merely an example of the transceiver 810, and thus the elements of the transceiver 810 are not limited to the RF transmitter and the RF receiver.

[0148] Furthermore, the transceiver 810 can include a wired / wireless transceiver, and can include various configurations for transmitting and receiving a signal.

[0149] Furthermore, the transceiver 810 can receive a signal via a wireless channel and output the signal to the processor 830, and can transmit a signal output from the processor 830 via a wireless channel.

[0150] Furthermore, the transceiver 810 can receive a communication signal and output it to the processor 830, and can transmit a signal output from the processor 830 to a network entity via a wired / wireless network.

[0151] The memory 820 can store programs and data required for the operation of the UE 800. Furthermore, the memory 820 can store control information or data included in a signal obtained by the UE 800. The memory 820 can be implemented as a storage medium including a ROM, a RAM, a hard disk, a CD-ROM, a DVD, and the like, or any combination thereof.

[0152] The processor 830 can control a series of processes to allow the UE 800 to operate according to the aforementioned embodiments of the disclosure. The processor 830 can include at least one processor. For example, the processor 830 can include a communication processor (CP) for performing control for communication, and an application processor (AP) for controlling a higher layer such as an application program, etc.

[0153] The method according to the embodiments of the disclosure described in the claims or specification can be implemented as hardware, software, or a combination of hardware and software.

[0154] When implemented as software, a computer-readable storage medium storing one or more programs (e.g., software modules) can be provided. The one or more programs stored in the computer-readable storage medium are configured to be executed by one or more processors in an electronic device. The one or more programs include instructions that instruct the electronic device to perform the method according to the embodiments of the disclosure described in the claims or specification.

[0155] The program (e.g., software module or software) can be stored in a non-volatile memory including RAM or flash memory, ROM, electrically erasable programmable read-only memory (EEPROM), a magnetic disc storage device, a CD-ROM, a DVD, another optical storage device, or a magnetic cassette. Alternatively, the program can be stored in a memory including a combination of some or all of the above-mentioned storage media. Furthermore, a plurality of such memories can be included.

[0156] In addition, the program can be stored in an attachable storage device accessible via any one or a combination of communication networks such as the Internet, an intranet, a local area network (LAN), a wide LAN (WLAN), a storage area network (SAN), etc. Such a storage device can access a device performing embodiments of the disclosure via an external port. Furthermore, a separate storage device on the communication network can access a device performing embodiments of the disclosure.

[0157] In the foregoing embodiments of the disclosure, elements included in the disclosure are expressed in singular or plural form according to embodiments of the disclosure. However, the singular or plural form is appropriately selected for the convenience of description, and the disclosure is not limited thereto. As such, an element expressed in plural form can also be configured as a single element, and an element expressed in singular form can also be configured as a plurality of elements.

[0158] Furthermore, the above-described embodiments can be combined as needed. For example, the BS, the UE, and the network entity can operate according to some combination of embodiments.

[0159] It should be understood that various embodiments of the disclosure according to the claims and description in the specification can be implemented in the form of hardware, software, or a combination of hardware and software.

[0160] Any such software can be stored in a non-transitory computer-readable storage medium. The non-transitory computer-readable storage medium stores one or more computer programs (software modules) including computer-executable instructions that, when executed by one or more processors of an electronic device, cause the electronic device to perform the method of the disclosure.

[0161] Any such software can be stored in the form of volatile or non-volatile storage such as a storage device like a Read Only Memory (ROM), whether erasable or rewritable or not, or in the form of memory such as Random Access Memory (RAM), memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a compact disc (CD), digital versatile disc (DVD), a magnetic disk or magnetic tape or the like. It will be appreciated that the storage devices and storage media are various embodiments of non-transitory machine- readable storage that are suitable for storing a computer program comprising instructions that, when executed, implement various embodiments of the present disclosure. Accordingly, various embodiments provide a program and non-transitory machine-readable storage storing such a program, the program comprising instructions to implement apparatus or methods as claimed in any one of the claims of this specification.

[0162] While the present disclosure has been illustrated and described with reference to various embodiments thereof, it will be understood that various changes in form and details can be made therein without departing from the spirit and scope of the present disclosure as defined by the following claims and the full range of equivalents to which such claims are entitled.

Claims

1. A method performed by a user equipment (UE) in a wireless communication system, the method comprising: Send information to the Access and Mobility Management Function (AMF) instructing the UE to support network slice replacement features; as well as In the presence of a Protocol Data Unit (PDU) session associated with the single Network Slice Selection Auxiliary Information (S-NSSAI) that needs to be replaced, the mapping from receiving S-NSSAI from the AMF to the replacement S-NSSAI is performed. In the case where S-NSSAI is replaced by the alternative S-NSSAI, the PDU session is associated with both S-NSSAI and the alternative S-NSSAI.

2. The method according to claim 1, further comprising: For applications, identify whether to establish a PDU session for the application or to use an existing PDU session associated with an S-NSSAI, based on S-NSSAI rather than on an alternative S-NSSAI.

3. The method according to claim 2, wherein, The logo includes: Identify whether the S-NSSAI matches the first S-NSSAI associated with the application; and If the first S-NSSAI does not match the S-NSSAI, it is identified as an application establishing a PDU session.

4. The method according to claim 1, wherein, The registration response message or UE configuration update message includes the mapping sent to the UE.

5. A user equipment (UE) in a wireless communication system, the UE comprising: transceiver; and At least one processor is configured as follows: Send information to the Access and Mobility Management Function (AMF) instructing the UE to support network slice replacement features; as well as In the presence of a Protocol Data Unit (PDU) session associated with the single Network Slice Selection Auxiliary Information (S-NSSAI) that needs to be replaced, the mapping from receiving S-NSSAI from the AMF to the replacement S-NSSAI is performed. In the case where S-NSSAI is replaced by the alternative S-NSSAI, the PDU session is associated with both S-NSSAI and the alternative S-NSSAI.

6. The UE according to claim 5, wherein, The at least one processor is further configured to: For applications, identify whether to establish a PDU session for the application or to use an existing PDU session associated with an S-NSSAI, based on S-NSSAI rather than on an alternative S-NSSAI.

7. The UE according to claim 6, wherein, The at least one processor is configured to: Identify whether the S-NSSAI matches the first S-NSSAI associated with the application; and If the first S-NSSAI does not match the S-NSSAI, it is identified as an application establishing a PDU session.

8. The UE according to claim 5, wherein, The registration response message or UE configuration update message includes the mapping sent to the UE.

9. A method performed by an Access and Mobility Management Function (AMF) in a wireless communication system, the method comprising: Receive information from the user equipment (UE) indicating that the UE supports network slice replacement features; In cases where a single network slice selection auxiliary information (S-NSSAI) becomes unavailable or congested, determine which S-NSSAI will be replaced by an alternative S-NSSAI; and If a Protocol Data Unit (PDU) session exists that is associated with the S-NSSAI that needs to be replaced, a mapping from S-NSSAI to the replacement S-NSSAI is sent to the UE, wherein the mapping from S-NSSAI to the replacement S-NSSAI is stored in the UE context in the AMF.

10. The method of claim 9, further comprising: Indicate whether there are any established PDU sessions associated with the alternative S-NSSAI that are now available or no longer congested; If an established PDU session associated with an alternative S-NSSAI becomes available again or is no longer congested, it is flagged so that the established PDU session is transferred to S-NSSAI. as well as Send a PDU session update message to the Session Management Function (SMF) to transfer the PDU session to S-NSSAI.

11. The method according to claim 9, wherein, The alternative S-NSSAI is determined based on at least one of the following: information from the Network Slice Selection Function (NSSF), information from the Policy Control Function (PCF), information from Operation, Administration and Maintenance (OAM), and local configuration.

12. The method according to claim 9, wherein, The registration response message or UE configuration update message includes the mapping sent to the UE.

13. An Access and Mobility Management Function (AMF) in a wireless communication system, the AMF comprising: transceiver; and At least one processor is configured as follows: Receive information from the user equipment (UE) indicating that the UE supports network slice replacement features; In cases where a single network slice selection auxiliary information (S-NSSAI) becomes unavailable or congested, determine which S-NSSAI will be replaced by an alternative S-NSSAI; and If a Protocol Data Unit (PDU) session exists that is associated with the S-NSSAI that needs to be replaced, a mapping from S-NSSAI to the replacement S-NSSAI is sent to the UE, wherein the mapping from S-NSSAI to the replacement S-NSSAI is stored in the UE context in the AMF.

14. The AMF according to claim 13, wherein, The at least one processor is further configured to: Indicate whether there are any established PDU sessions associated with the alternative S-NSSAI that are now available or no longer congested; If an established PDU session associated with an alternative S-NSSAI becomes available again or is no longer congested, it is flagged so that the established PDU session is transferred to S-NSSAI. as well as Send a PDU session update message to the Session Management Function (SMF) to transfer the PDU session to S-NSSAI.

15. The AMF according to claim 13, wherein, The alternative S-NSSAI is determined based on at least one of the following: information from the Network Slice Selection Function (NSSF), information from the Policy Control Function (PCF), information from Operation, Administration and Maintenance (OAM), and local configuration.

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