Non-3GPP AN node selection method

Abstract

One disclosure in the present specification provides a method for a NAS layer of a UE to perform communication, the method including: transmitting a first registration request message to a specific non-3GPP Access Network (AN) node via a non-3GPP access; receiving a registration rejection message from an AMF based on the first registration request message including a Requested NSSAI and the specific non-3GPP AN node not supporting the Requested NSSAI; and transmitting a second registration request message, the registration rejection message including target non-3GPP AN node information, based on the step of transmitting the second registration request message using the target non-3GPP AN node information.

Description

[Technical Field]

[0001] This specification relates to mobile communications. [Background technology]

[0002] 3GPP (3rd Generation Partnership Project) LTE (Long-Term Evolution) is a technology that enables high-speed packet communications. Many methods have been proposed to achieve the goals of LTE: reducing costs for users and operators, improving service quality, expanding coverage, and increasing system capacity. 3GPP LTE's high-level requirements include reduced cost per bit, improved service availability, flexible use of frequency bands, simple architecture, open interfaces, and reasonable terminal power consumption.

[0003] The International Telecommunication Union (ITU) and 3GPP have begun work to develop requirements and specifications for a New Radio (NR) system. 3GPP must identify and develop the technical components necessary to successfully standardize NR in a timely manner that meets all of the immediate market needs and the longer-term requirements presented by the ITU-R (ITU radio communication sector) IMT (International Mobile Telecommunications)-2020 process. Furthermore, NR must be able to use any spectrum band extending to at least 100 GHz that remains available for wireless communications well into the distant future.

[0004] NR targets a single technology framework that addresses all deployment scenarios, usage scenarios, and requirements, including enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), ultra-reliable and low latency communications (URLLC), etc. NR must be forward compatible in nature.

[0005] There was a problem in certain situations where device registration requests were repeatedly rejected. Summary of the Invention [Means for solving the problem]

[0006] Using the information contained in the registration rejection, the terminal performs a registration request via a message containing the same Requested NSSAI as the previous registration request. [Brief explanation of the drawings]

[0007] [Figure 1] 1 illustrates an example of a communication system to which implementations of the present disclosure may be applied. [Figure 2] 1 illustrates an example of a wireless device to which the implementations of the present disclosure may be applied. [Figure 3] 1 illustrates an example of a UE to which the implementation of the present specification may be applied. [Figure 4] 1 is a structural diagram of a next-generation mobile communication network. [Figure 5] 1 illustrates an example of a 5G system structure to which the present specification may be applied. [Figure 6] 1 illustrates an example of a registration procedure to which the present invention may be applied. [Figure 7] 1 illustrates an example of a registration procedure to which the present invention may be applied. [Figure 8a] 1 illustrates registration over untrusted non-3GPP access according to an embodiment of the present disclosure. [Figure 8b] 1 illustrates registration over untrusted non-3GPP access according to an embodiment of the present disclosure. [Figure 8c] 1 illustrates registration over untrusted non-3GPP access according to an embodiment of the present disclosure. [Figure 9a] 1 illustrates registration via trusted non-3GPP access according to an embodiment of the present disclosure. [Figure 9b] 1 illustrates registration via trusted non-3GPP access according to an embodiment of the present disclosure. [Figure 9c] 1 illustrates registration via trusted non-3GPP access according to an embodiment of the present disclosure. [Figure 9d] 1 illustrates registration via trusted non-3GPP access according to an embodiment of the present disclosure. [Figure 10] 1 illustrates a UE procedure for the present disclosure. [Figure 11] 1 shows the AMF procedure for the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0008] The following techniques, devices, and systems apply to various wireless multiple access systems. Examples of multiple access systems include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and multicarrier frequency division multiple access (MC-FDMA). CDMA is implemented via radio technologies such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA is implemented via radio technologies such as global system for mobile communications (GSM), general packet radio service (GPRS), or enhanced data rates for GSM evolution (EDGE). OFDMA is implemented via radio technologies such as IEEE (Institute of Electrical and Electronics Engineers) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, or evolved UTRA (E-UTRA). UTRA is part of the universal mobile telecommunications system (UMTS). 3GPP (3rd generation partnership project) long-term evolution (LTE) is part of evolved UMTS (E-UMTS) that uses E-UTRA. 3GPP LTE uses OFDMA on the downlink (DL) and SC-FDMA on the uplink (UL).Evolutions of 3GPP LTE include LTE-A (advanced), LTE-A Pro, and / or 5G NR (New Radio).

[0009] For convenience of explanation, the present specification will be described mainly in relation to a 3GPP-based wireless communication system. However, the technical characteristics of the present specification are not limited thereto. For example, the following detailed description is provided based on a mobile communication system corresponding to a 3GPP-based wireless communication system, but aspects of the present specification that are not limited to a 3GPP-based wireless communication system can be applied to other mobile communication systems.

[0010] For terms and technologies used in this specification that are not specifically described, reference may be made to wireless communication standard documents published prior to this specification.

[0011] As used herein, "A or B" can mean "only A," "only B," or "both A and B." Also, as used herein, "A or B" can be interpreted as "A and / or B." For example, as used herein, "A, B or C" can mean "only A," "only B," "only C," or "any combination of A, B, and C."

[0012] As used herein, a slash ( / ) or a comma can mean "and / or." For example, "A / B" can mean "A and / or B." Thus, "A / B" can mean "only A," "only B," or "both A and B." For example, "A, B, C" can mean "A, B, or C."

[0013] In this specification, "at least one of A and B" can mean "only A," "only B," or "both A and B." Furthermore, in this specification, the expressions "at least one of A or B" and "at least one of A and / or B" can be interpreted as "at least one of A and B."

[0014] Furthermore, in this specification, "at least one of A, B, and C" can mean "only A," "only B," "only C," or "any combination of A, B, and C." Furthermore, "at least one of A, B, or C" or "at least one of A, B, and / or C" can mean "at least one of A, B, and C."

[0015] Furthermore, parentheses used in this specification may mean "for example." Specifically, when "control information (PDCCH)" is used, "PDCCH" is proposed as an example of "control information." Furthermore, "control information" in this specification is not limited to "PDCCH," and "PDDCH" is proposed as an example of "control information." Furthermore, when "control information (i.e., PDCCH)" is used, "PDCCH" is proposed as an example of "control information."

[0016] In this specification, technical features individually described in one drawing may be embodied individually or simultaneously.

[0017] Without limitation, the various descriptions, functions, procedures, suggestions, methods and / or operational flow charts disclosed herein may be applied to various fields where device-to-device wireless communication and / or connectivity (e.g., 5G) is required.

[0018] Hereinafter, this specification will be described in more detail with reference to the drawings, in which the same reference numbers in the following drawings and / or description may refer to identical or corresponding hardware blocks, software blocks and / or functional blocks unless otherwise indicated.

[0019] FIG. 1 shows an example of a communication system in which the present invention may be implemented.

[0020] The 5G usage scenarios shown in FIG. 1 are merely examples, and the technical features of this specification apply to other 5G usage scenarios not shown in FIG. 1.

[0021] The three main requirement categories for 5G are (1) enhanced mobile broadband (eMBB) category, (2) massive machine type communication (mMTC) category, and (3) ultra-reliable and low latency communications (URLLC) category.

[0022] 1, a communication system 1 includes wireless devices 100a to 100f, a base station (BS) 200, and a network 300. While FIG. 1 illustrates a 5G network as an example of the network of the communication system 1, the present specification is not limited to the 5G system and is applicable to future communication systems beyond the 5G system.

[0023] The base station 200 and network 300 are embodied in wireless devices, and a particular wireless device is capable of operating as a base station / network node in relation to other wireless devices.

[0024] The wireless devices 100a to 100f represent devices that perform communication using a radio access technology (RAT) (e.g., 5G NR or LTE) and may also be referred to as communication / wireless / 5G devices. The wireless devices 100a to 100f may include, but are not limited to, a robot 100a, vehicles 100b-1 and 100b-2, an extended reality (XR) device 100c, a mobile device 100d, a home appliance 100e, an IoT device 100f, and an artificial intelligence (AI) device / server 400. For example, vehicles include vehicles with wireless communication capabilities, autonomous vehicles, and vehicles capable of performing inter-vehicle communication. Vehicles include unmanned aerial vehicles (UAVs) (e.g., drones). XR devices can include AR / VR / mixed reality (MR) devices and are embodied in the form of head-mounted devices (HMDs) and head-up displays (HUDs) attached to vehicles, televisions, smartphones, computers, wearable devices, home appliances, digital signs, vehicles, robots, etc. Portable devices include smartphones, smart pads, wearable devices (e.g., smart watches or smart glasses), and computers (e.g., laptops). Home appliances include TVs, refrigerators, and washing machines. IoT devices include sensors and smart meters.

[0025] In this specification, the wireless devices 100a to 100f may be referred to as user equipment (UE). The UE may include, for example, a mobile phone, a smartphone, a laptop computer, a digital broadcasting terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), a navigation system, a slate PC, a tablet PC, an ultrabook, a vehicle, a vehicle with autonomous driving capabilities, a connected automobile, a UAV, an AI module, a robot, an AR device, a VR device, a MR device, a hologram device, a public safety device, an MTC device, an IoT device, a medical device, a fintech device (or financial device), a security device, a weather / environment device, a 5G service-related device, or a fourth industrial revolution-related device.

[0026] For example, a UAV is an aircraft without a human on board that is navigated by radio control signals.

[0027] For example, a VR device may include a device for implementing an individual or background in a virtual environment. For example, an AR device may include a device that implements an individual or background in a virtual world by connecting them to an individual or background in the real world. For example, an MR device may include a device that implements an individual or background in a virtual world by merging them with an individual or background in the real world. For example, a hologram device may include a device that implements a 360-degree 3D image by recording and reproducing 3D information using the optical interference phenomenon that occurs when two laser lights, called a hologram, meet.

[0028] For example, public safety devices may include image relay devices or image devices that can be worn on the user's body.

[0029] For example, MTC and IoT devices are devices that do not require direct human intervention or operation, such as smart meters, vending machines, thermometers, smart light bulbs, door locks, or various sensors.

[0030] For example, a medical device is a device used for the purposes of diagnosing, treating, mitigating, curing, or preventing disease. For example, a medical device is a device used to diagnose, treat, mitigate, or correct injury or damage. For example, a medical device is a device used for the purposes of examining, replacing, or modifying structure or function. For example, a medical device is a device used for fertility control. For example, a medical device may include a therapeutic device, a driving device, an (in vitro) diagnostic device, a hearing aid, or a surgical device.

[0031] For example, a security device is a device installed to prevent possible dangers and maintain safety, such as a camera, a closed circuit TV (CCTV), a sound recorder, or a black box.

[0032] For example, a fintech device is a device that can provide financial services such as mobile payments. For example, a fintech device can include a payment device or a point-of-sale system.

[0033] For example, weather / environment devices may include devices that monitor or predict the weather / environment.

[0034] The wireless devices 100a to 100f are connected to a network 300 via a base station 200. AI technology can be applied to the wireless devices 100a to 100f, and the wireless devices 100a to 100f are connected to an AI server 400 via the network 300. The network 300 is configured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR) network, a network beyond 5G, or the like. The wireless devices 100a to 100f can communicate with each other via the base station 200 / network 300, but can also communicate directly (e.g., sidelink communication) without going through the base station 200 / network 300. For example, the vehicles 100b-1 and 100b-2 can communicate directly (e.g., V2V (vehicle-to-vehicle) / V2X (vehicle-to-everything) communication). Furthermore, an IoT device (for example, a sensor) can directly communicate with another IoT device (for example, a sensor) or another wireless device 100a to 100f.

[0035] Wireless communications / connections 150a, 150b, and 150c are established between the wireless devices 100a-100f and / or between the wireless devices 100a-100f and the base station 200 and / or between the base stations 200. Here, the wireless communications / connections are established via various RATs (e.g., 5G NR) such as uplink / downlink communications 150a, sidelink communications 150b (or device-to-device (D2D) communications), and inter-base station communications 150c (e.g., relaying, integrated access and backhaul (IAB)). Through the wireless communications / connections 150a, 150b, and 150c, the wireless devices 100a-100f and the base station 200 can transmit / receive wireless signals to / from each other. For example, the wireless communications / connections 150a, 150b, and 150c can transmit / receive signals via various physical channels. To this end, based on the various proposals in this specification, at least some of the processes of setting various configuration information for transmitting / receiving wireless signals, various signal processing processes (e.g., channel encoding / decoding, modulation / demodulation, resource mapping / demapping, etc.), and resource allocation processes are performed.

[0036] AI refers to the field that studies artificial intelligence or the methodologies that can create it, while machine learning refers to the field that defines various problems that are dealt with in the field of artificial intelligence and studies the methodologies that solve them. Machine learning can also be defined as an algorithm that improves its performance for a certain task through consistent experience with that task.

[0037] A robot can refer to a machine that automatically processes or operates a given task using its own capabilities. In particular, a robot that has the ability to recognize its environment, make decisions, and perform actions independently can be called an intelligent robot. Robots can be classified into industrial, medical, domestic, military, etc. depending on their intended use or field. Robots are equipped with driving parts including actuators or motors to perform various physical operations, such as moving robot joints. In addition, mobile robots have driving parts including wheels, brakes, propellers, etc., and can move on the ground or fly in the air using the driving parts.

[0038] Autonomous driving refers to technology that drives itself, and an autonomous vehicle refers to a vehicle that drives without user input or with minimal user input. For example, autonomous driving can include technology that maintains a lane while driving, technology that automatically adjusts speed like adaptive cruise control, technology that automatically drives along a predetermined route, and technology that automatically sets a route and drives when a destination is set. Vehicles include vehicles equipped with only an internal combustion engine, hybrid vehicles equipped with both an internal combustion engine and an electric motor, and electric vehicles equipped with only an electric motor, and can include not only automobiles but also trains, motorcycles, etc. An autonomous vehicle can be considered a robot with autonomous driving capabilities.

[0039] Augmented reality is a general term for VR, AR, and MR. VR technology provides real-world objects and backgrounds only in CG images, AR technology provides virtual CG images on top of images of real things, and MR technology is a CG technology that combines virtual objects with the real world. MR technology is similar to AR technology in that it shows both real and virtual objects. However, it differs in that AR technology uses virtual objects to complement real objects, while MR technology uses virtual and real objects with equal characteristics.

[0040] NR supports multiple numerologies or subcarrier spacings (SCS) to support various 5G services. For example, a 15 kHz SCS supports wide areas in traditional cellular bands, a 30 kHz / 60 kHz SCS supports dense urban areas, lower latency, and wider carrier bandwidths, and a 60 kHz or higher SCS supports bandwidths greater than 24.25 GHz to overcome phase noise.

[0041] The NR frequency band can be defined as two types of frequency ranges (FR1 and FR2). The values ​​of the frequency ranges can be changed. For example, the two types of frequency ranges (FR1 and FR2) are shown in Table 1 below. For convenience of explanation, among the frequency ranges used in the NR system, FR1 can mean the "sub 6 GHz range" and FR2 can mean the "above 6 GHz range" and can be called millimeter wave (mmW).

[0042] [Table 1]

[0043] As mentioned above, the numerical values ​​of the frequency range of the NR system can be changed. For example, FR1 can include the band from 410 MHz to 7125 MHz as shown in Table 2 below. That is, FR1 can include frequency bands above 6 GHz (or 5850, 5900, 5925 MHz, etc.). For example, the frequency bands above 6 GHz (or 5850, 5900, 5925 MHz, etc.) included in FR1 can include unlicensed bands. Unlicensed bands can be used for various purposes, such as communications for vehicles (e.g., autonomous driving).

[0044] [Table 2]

[0045] Here, the wireless communication technology implemented in the wireless device of the present specification may include not only LTE, NR, and 6G, but also narrowband IoT (NB-IoT) for low-power communication. For example, NB-IoT technology is an example of low-power wide area network (LPWAN) technology and may be implemented in standards such as LTE Cat NB1 and / or LTE Cat NB2, and is not limited to the above names. Additionally or alternatively, the wireless communication technology implemented in the wireless device of the present specification may perform communication based on LTE-M technology. For example, LTE-M technology is an example of LPWAN technology and may be referred to by various names such as enhanced MTC (eMTC). For example, LTE-M technology may be implemented in at least one of various standards such as 1) LTE CAT 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-BL (non-bandwidth limited), 5) LTE-MTC, 6) LTE MTC, and / or 7) LTE M, and is not limited to the above names. Additionally or alternatively, the wireless communication technology implemented in the wireless device of this specification may include at least one of ZigBee (registered trademark), Bluetooth (registered trademark), and / or LPWAN, which consider low-power communication, but are not limited to the above names. For example, ZigBee technology can create personal area networks (PANs) related to small / low-power digital communication based on various standards such as IEEE 802.15.4, and may be called by various names.

[0046] FIG. 2 shows an example of a wireless device to which the present invention may be applied.

[0047] 2, the first wireless device 100 and / or the second wireless device 200 may be embodied in various forms depending on the use case / service. For example, {the first wireless device 100 and the second wireless device 200} may correspond to at least one of {the wireless devices 100a-100f and the base station 200}, {the wireless devices 100a-100f and the wireless devices 100a-100f}, and / or {the base station 200 and the base station 200} in FIG. 1. The first wireless device 100 and / or the second wireless device 200 may be configured with various components, devices / parts, and / or modules.

[0048] First wireless device 100 may include at least one transceiver, such as transceiver 106 , at least one processing chip, such as processing chip 101 , and / or one or more antennas 108 .

[0049] Processing chip 101 may include at least one processor, such as processor 102, and at least one memory, such as memory 104. Additionally and / or alternatively, memory 104 may be located external to processing chip 101.

[0050] The processor 102 may control the memory 104 and / or the transceiver 106 and may be configured to implement the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein. For example, the processor 102 may process information in the memory 104 to generate first information / signals and transmit a wireless signal including the first information / signals via the transceiver 106. The processor 102 may receive a wireless signal including second information / signals via the transceiver 106 and store information obtained by processing the second information / signals in the memory 104.

[0051] The memory 104 may be operatively coupled to the processor 102. The memory 104 may store various types of information and / or instructions. The memory 104 may store firmware and / or software code 105 that, when executed by the processor 102, embodies code, instructions, and / or collections of instructions that perform the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein. For example, the firmware and / or software code 105 may embodi instructions that, when executed by the processor 102, perform the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein. For example, the firmware and / or software code 105 may control the processor 102 to implement one or more protocols. For example, the firmware and / or software code 105 may control the processor 102 to implement one or more air interface protocol layers.

[0052] Here, the processor 102 and memory 104 are part of a communication modem / circuit / chip designed to implement a RAT (e.g., LTE or NR). The transceiver 106 is coupled to the processor 102 and can transmit and / or receive wireless signals via one or more antennas 108. Each transceiver 106 may include a transmitter and / or a receiver. The transceiver 106 may be used interchangeably with an RF (radio frequency) unit. In this specification, the first wireless device 100 may refer to a communication modem / circuit / chip.

[0053] Second wireless device 200 may include at least one transceiver, such as transceiver 206 , at least one processing chip, such as processing chip 201 , and / or one or more antennas 208 .

[0054] Processing chip 201 may include at least one processor, such as processor 202, and at least one memory, such as memory 204. Additionally and / or alternatively, memory 204 may be located external to processing chip 201.

[0055] The processor 202 may control the memory 204 and / or the transceiver 206 and may be configured to implement the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein. For example, the processor 202 may process information in the memory 204 to generate third information / signals and transmit a wireless signal including the third information / signals via the transceiver 206. The processor 202 may receive a wireless signal including fourth information / signals via the transceiver 206 and store information obtained by processing the fourth information / signals in the memory 204.

[0056] Memory 204 may be operatively coupled to processor 202. Memory 204 may store various types of information and / or instructions. Memory 204 may store firmware and / or software code 205 that, when executed by processor 202, embody instruction codes, commands, and / or sets of commands that implement the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein. For example, firmware and / or software code 205 may embody instructions that, when executed by processor 202, implement the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein. For example, firmware and / or software code 205 may control processor 202 to implement one or more protocols. For example, firmware and / or software code 205 may control processor 202 to implement one or more air interface protocol layers.

[0057] Here, the processor 202 and memory 204 are part of a communication modem / circuit / chip designed to implement a RAT (e.g., LTE or NR). The transceiver 206 is coupled to the processor 202 and can transmit and / or receive wireless signals via one or more antennas 208. Each transceiver 206 may include a transmitter and / or a receiver. The transceiver 206 may be used interchangeably with an RF unit. In this specification, the second wireless device 200 may refer to a communication modem / circuit / chip.

[0058] The hardware elements of the wireless devices 100 and 200 will be described in more detail below. Without limitation, one or more protocol layers may be implemented by one or more processors 102 and 202. For example, one or more processors 102 and 202 may implement one or more layers (e.g., functional layers such as a physical (PHY) layer, a media access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, a radio resource control (RRC) layer, and a service data adaptation protocol (SDAP) layer). The one or more processors 102 and 202 may generate one or more protocol data units (PDUs), one or more service data units (SDUs), messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods, and / or operational flow charts disclosed herein. The one or more processors 102, 202 can generate and provide signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein to the one or more transceivers 106, 206. The one or more processors 102, 202 can receive signals (e.g., baseband signals) from the one or more transceivers 106, 206 and obtain the PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein.

[0059] The one or more processors 102, 202 may be referred to as a controller, microcontroller, microprocessor, and / or microcomputer. The one or more processors 102, 202 may be implemented using hardware, firmware, software, and / or a combination thereof. For example, the one or more processors 102, 202 may include one or more application-specific integrated circuits (ASICs), one or more digital signal processors (DSPs), one or more digital signal processing devices (DSPDs), one or more programmable logic devices (PLDs), and / or one or more field programmable gate arrays (FPGAs). For example, the one or more processors 102, 202 may include a collection of a communication control processor, an application processor (AP), an electronic control unit (ECU), a central processing unit (CPU), a graphic processing unit (GPU), and a memory control processor.

[0060] One or more memories 104, 204 may be coupled to one or more processors 102, 202 and may store various types of data, signals, messages, information, programs, code, instructions, and / or commands. The one or more memories 104, 204 may be comprised of Random Access Memory (RAM), Dynamic RAM (DRAM), Read-Only Memory (ROM), Erasable Programmable ROM (EPROM), flash memory, volatile memory, non-volatile memory, hard drives, registers, cache memory, computer-readable storage media, and / or combinations thereof. The one or more memories 104, 204 may be located internal and / or external to the one or more processors 102, 202. The one or more memories 104, 204 may also be coupled to the one or more processors 102, 202 via various techniques, such as wired or wireless connections.

[0061] One or more transceivers 106, 206 may transmit user data, control information, wireless signals / channels, etc., as referred to in the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein to one or more other devices. One or more transceivers 106, 206 may receive user data, control information, wireless signals / channels, etc., as referred to in the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein from one or more other devices. For example, one or more transceivers 106, 206 may be coupled to one or more processors 102, 202 and may transmit and receive wireless signals. For example, one or more processors 102, 202 may control one or more transceivers 106, 206 to transmit user data, control information, wireless signals, etc., to one or more other devices. Also, one or more processors 102, 202 may control one or more transceivers 106, 206 to receive user data, control information, wireless signals, etc., from one or more other devices.

[0062] One or more transceivers 106, 206 may be coupled with one or more antennas 108, 208. Additionally and / or alternatively, one or more transceivers 106, 206 may include one or more antennas 108, 208. The one or more transceivers 106, 206 may be configured to transmit or receive user data, control information, wireless signals / channels, etc., referred to in the descriptions, functions, procedures, suggestions, methods, and / or operational flow charts disclosed herein via the one or more antennas 108, 208. As used herein, the one or more antennas 108, 208 may be multiple physical antennas or multiple logical antennas (e.g., antenna ports).

[0063] The one or more transceivers 106, 206 may convert received user data, control information, radio signals / channels, etc., from RF-band signals to baseband signals for processing by the one or more processors 102, 202. The one or more transceivers 106, 206 may convert user data, control information, radio signals / channels, etc., processed by the one or more processors 102, 202, from baseband signals to RF-band signals. To this end, the one or more transceivers 106, 206 may include an (analog) oscillator and / or a filter. For example, the one or more transceivers 106, 206 may up-convert an OFDM baseband signal to an OFDM signal via an (analog) oscillator and / or a filter under the control of the one or more processors 102, 202, and transmit the up-converted OFDM signal at a carrier frequency. One or more transceivers 106, 206 can receive OFDM signals at a carrier frequency and down-convert the OFDM signals to OFDM baseband signals via (analog) oscillators and / or filters under the control of one or more processors 102, 202.

[0064] 2, the wireless devices 100, 200 may further include additional components. The additional components 140 may be configured in various ways depending on the type of the wireless devices 100, 200. For example, the additional components 140 may include at least one of a power unit / battery, an input / output (I / O) device (e.g., an audio I / O port, a video I / O port), a drive unit, and a computing device. The additional components 140 may be connected to one or more processors 102, 202 via various techniques, such as a wired or wireless connection.

[0065] In embodiments of the present specification, a UE may operate as a transmitter in the uplink (UL) and as a receiver in the downlink (DL). In embodiments of the present specification, a base station may operate as a receiver in the UL and as a transmitter in the DL. In the following, for convenience of explanation, it is primarily assumed that the first wireless device 100 operates as a UE and the second wireless device 200 operates as a base station. For example, a processor 102 coupled to, mounted on, or released in the first wireless device 100 is configured to perform UE operations in accordance with embodiments of the present specification or to control the transceiver 106 to perform UE operations in accordance with embodiments of the present specification. A processor 202 coupled to, mounted on, or released in the second wireless device 200 is configured to perform base station operations in accordance with embodiments of the present specification or to control the transceiver 206 to perform base station operations in accordance with embodiments of the present specification.

[0066] In this specification, a base station may be referred to as a Node B, an eNode B (eNB), or a gNB.

[0067] FIG. 3 illustrates an example of a UE to which the implementations of this specification may be applied.

[0068] FIG. 3 illustrates an example of a UE to which the implementations of this specification may be applied.

[0069] Referring to FIG. 3, a UE 100 may correspond to the first wireless device 100 of FIG.

[0070] The UE 100 includes a processor 102, a memory 104, a transceiver 106, one or more antennas 108, a power management module 141, a battery 142, a display 143, a keypad 144, a SIM (Subscriber Identification Module) card 145, a speaker 146, and a microphone 147.

[0071] The processor 102 may be configured to implement the descriptions, functions, procedures, suggestions, methods, and / or operational flow charts disclosed herein. The processor 102 may be configured to control one or more other components of the UE 100 to implement the descriptions, functions, procedures, suggestions, methods, and / or operational flow charts disclosed herein. A layer of an air interface protocol may be embodied in the processor 102. The processor 102 may include an ASIC, other chipset, logic circuit, and / or data processing device. The processor 102 is an application processor. The processor 102 may include at least one of a DSP, a central processing unit (CPU), a graphics processing unit (GPU), and a modem (modulator and demodulator). An example of the processor 102 is a SNAPDRAGON made by Qualcomm®. TM EXYNOS series processor, made by Samsung® TM Series processors, A-series processors made by Apple®, HELIO made by MediaTek® TM ATOM series processors, made by Intel® TM It can be found in the series processors or the corresponding next-generation processors.

[0072] Memory 104 is operatively coupled to processor 102 and stores various information for operating processor 102. Memory 104 may include ROM, RAM, flash memory, a memory card, a storage medium, and / or other storage devices. When implemented in software, the techniques described herein may be implemented using modules (e.g., procedures, functions, etc.) that execute the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein. The modules may be stored in memory 104 and executed by processor 102. Memory 104 may be implemented within processor 102 or external to processor 102, in which case it may be communicatively coupled to processor 102 via various methods known in the art.

[0073] The transceiver 106 is operatively coupled to the processor 102 to transmit and / or receive radio signals. The transceiver 106 includes a transmitter and a receiver. The transceiver 106 may include baseband circuitry for processing radio frequency signals. The transceiver 106 controls one or more antennas 108 to transmit and / or receive radio signals.

[0074] The power management module 141 manages the power supply of the processor 102 and / or the transceiver 106. The battery 142 supplies power to the power management module 141.

[0075] The display 143 outputs the results processed by the processor 102. The keypad 144 receives input for use by the processor 102. The keypad 144 can be displayed on the display 143.

[0076] The SIM card 145 is an integrated circuit for securely storing an International Mobile Subscriber Identity (IMSI) and associated keys used to identify and authenticate a subscriber to a mobile device such as a cell phone or computer. Many SIM cards can also store contact information.

[0077] A speaker 146 outputs sound-related results processed by the processor 102. A microphone 147 receives sound-related input for use by the processor 102.

[0078] FIG. 4 is a structural diagram of a next-generation mobile communication network.

[0079] 5GC (5G Core) may include various components, some of which are shown in Figure 5, such as AMF (Access and Mobility Management Function) 410, SMF (Session Management Function) 420, PCF (Policy Control Function) 430, UPF (User Plane Function) 440, AF (Application Function) 450, UDM (Unified Data Management) 460, and N3IWF (Non-3GPP (3rd Generation Partnership Project) Inter Working Function) 490.

[0080] The UE 100 is connected to a data network via a Next Generation Radio Access Network (NG-RAN) including a gNB 20 via a UPF 440.

[0081] The UE 100 can also receive data services via an untrusted non-3GPP access, such as a wireless local area network (WLAN). An N3IWF 490 can be deployed to connect the non-3GPP access to the core network.

[0082] The illustrated N3IWF 490 performs the function of managing interworking between non-3GPP access and a 5G system. When the UE 100 is connected to a non-3GPP access (e.g., WiFi called IEEE 801.11), the UE 100 can be connected to the 5G system via the N3IWF 490. The N3IWF 490 performs control signaling with the AMF 410 and is connected to the UPF 440 via the N3 interface for data transmission.

[0083] The illustrated AMF 410 can manage access and mobility in a 5G system. The AMF 410 can perform a function of managing Non-Access Stratum (NAS) security. The AMF 410 can perform a function of handling mobility in an idle state.

[0084] The illustrated UPF 440 is a type of gateway through which user data is transmitted and received. The UPF node 440 can perform all or part of the user plane functions of a Serving Gateway (S-GW) and a Packet Data Network Gateway (P-GW) for 4G mobile communications.

[0085] The UPF 440 serves as a demarcation point between the next generation radio access network (NG-RAN) and the core network, and maintains a data path between the gNB 20 and the SMF 420. When the UE 100 moves within the area served by the gNB 20, the UPF 440 serves as a mobility anchor point. The UPF 440 can handle PDUs. For mobility within the NG-RAN (Next Generation Radio Access Network defined in 3GPP Release-15 and later), the UPF can route packets. The UPF 440 can also function as an anchor point for mobility with other 3GPP networks (RANs defined before 3GPP Release-15, such as UTRAN, E-UTRAN (Evolved-UMTS (Universal Mobile Telecommunications System) Terrestrial Radio Access Network)), or GERAN (GSM (Global System for Mobile Communication) / EDGE (Enhanced Data rates for Global Evolution) Radio Access Network). The UPF 440 can serve as the termination point of the data interface toward the data network.

[0086] The illustrated PCF 430 is a node that controls the operator's policies.

[0087] The illustrated AF 450 is a server for providing various services to the UE 100 .

[0088] The illustrated UDM 460 is a type of server that manages subscriber information, such as a Home Subscriber Server (HSS) for fourth generation mobile communications. The UDM 460 stores and manages the subscriber information in a Unified Data Repository (UDR).

[0089] The illustrated SMF 420 may perform a function of allocating an Internet Protocol (IP) address of a UE, and may control a protocol data unit (PDU) session.

[0090] For reference, in the following, the reference numerals for AMF410, SMF420, PCF430, UPF440, AF450, UDM460, N3IWF490, gNB20, or UE100 may be omitted.

[0091] Fifth generation mobile communications support multiple numerologies or subcarrier spacings (SCS) to support various 5G services. For example, a 15 kHz SCS supports wide areas in traditional cellular bands, a 30 kHz / 60 kHz SCS supports dense urban areas, lower latency, and wider carrier bandwidths, and a 60 kHz or higher SCS supports bandwidths greater than 24.25 GHz to overcome phase noise.

[0092] FIG. 5 shows an example of a 5G system structure to which the present specification may be applied.

[0093] The 5G system (5GS) structure consists of the following network functions (NFs):

[0094] -AUSF(Authentication Server Function)

[0095] -AMF(Access and Mobility Management Function)

[0096] -DN (Data Network), such as operator services, Internet connection or other company services

[0097] -USDF(Unstructured Data Storage Function)

[0098] -NEF (Network Exposure Function)

[0099] -I-NEF (Intermediate NEF)

[0100] -NRF(Network Repository Function)

[0101] -NSSF(Network Slice Selection Function)

[0102] -PCF (Policy Control Function)

[0103] -SMF(Session Management Function)

[0104] -UDM (Unified Data Management)

[0105] -UDR (Unified Data Repository)

[0106] -UPF (User Plane Function)

[0107] -UCMF(UE radio Capability Management Function)

[0108] -AF (Application Function)

[0109] -UE (User Equipment)

[0110] -(R)AN ((Radio)Access Network)

[0111] -5G-EIR(5G-Equipment Identity Register)

[0112] -NWDAF(Network Data Analytics Function)

[0113] -CHF (Charging Function)

[0114] Additionally, the following network functions can be considered:

[0115] -N3IWF (Non-3GPP InterWorking Function)

[0116] -TNGF(Trusted Non-3GPP Gateway Function)

[0117] -W-AGF(Wireline Access Gateway Function)

[0118] Figure 5 shows the 5G system architecture for the non-roaming case using a reference point representation that shows how various network functions interact with each other.

[0119] For clarity of the point-to-point diagram, the UDSF, NEF, and NRF are not illustrated in Figure 5. However, all of the network functions shown can interact with the UDSF, UDR, NEF, and NRF as needed.

[0120] For clarity, the coupling between the UDR and other NFs (e.g., PCFs) is not shown in Figure 4. For clarity, the coupling between the NWDAF and other NFs (e.g., PCFs) is not shown in Figure 4.

[0121] The 5G system architecture includes the following reference points:

[0122] N1: Reference point between the UE and the AMF.

[0123] -N2: Reference point between (R)AN and AMF.

[0124] -N3: Reference point between (R)AN and UPF.

[0125] N4: Reference point between SMF and UPF.

[0126] N6: Reference point between the UPF and the data network.

[0127] - N9: Reference point between two UPFs.

[0128] The following reference points indicate the interactions that exist between NF services of an NF:

[0129] - N5: Reference point between PCF and AF.

[0130] N7: Reference point between SMF and PCF.

[0131] - N8: Reference point between UDM and AMF.

[0132] - N10: Reference point between UDM and SMF.

[0133] - N11: Reference point between AMF and SMF.

[0134] -N12: Reference point between AMF and AUSF.

[0135] -N13: Reference point between UDM and AUSF.

[0136] - N14: Reference point between two AMFs.

[0137] -N15: In a non-roaming scenario, the reference point between the PCF and the AMF; in a roaming scenario, the reference point between the PCF and the AMF of the visited network.

[0138] N16: Reference point between two SMFs (in the case of roaming, between the SMF of the visited network and the SMF of the home network)

[0139] -N22: Reference point between AMF and NSSF.

[0140] In some cases, two NFs may need to be interconnected to serve a UE.

[0141] <Registration Procedure>

[0142] The registration procedure is described in Section 4.2.2.2 of 3GPP TS 23.502 V16.3.0(2019-12).

[0143] 6 and 7 show an example of a registration procedure to which the present invention may be applied.

[0144] A UE must register with the network to receive services, activate mobility tracking, and activate reachability. The UE initiates the registration procedure using one of the following registration types:

[0145] -initial registration for 5GS; or

[0146] -mobility registration update; or

[0147] -periodic registration update; or

[0148] -Emergency registration

[0149] The general registration procedure of Figures 6 and 7 applies to all registration procedures described above, but the periodic registration update does not need to include all parameters used in the other registration procedures.

[0150] The general registration procedures of Figures 6 and 7 are used when a UE is registered in a non-3GPP connection and registers to a 3GPP connection, and vice versa. When a UE is already registered in a non-3GPP connection scenario, an AMF change is required if it attempts to register to a 3GPP connection.

[0151] First, the procedure in FIG. 6 will be described.

[0152] (1) Step 1: The UE sends a Registration Request message to the (R)AN. The Registration Request message corresponds to an AN message.

[0153] The registration request message may include AN parameters. In the case of NG-RAN, the AN parameters include, for example, a 5G SAE temporary mobile subscriber identity (5G-S-TMSI) or globally unique AMF ID (GUAMI), a selected PLMN (public and mobile network) ID (or PLMN ID and NID (network identifier)), and a requested network slice selection assistance information (NSSAI). The AN parameters also include an establishment cause. The establishment cause provides the reason for requesting establishment of an RRC connection. Whether and how the UE includes the requested NSSAI as part of the AN parameters depends on the value of the access stratum connection establishment NSSAI inclusion mode parameter.

[0154] The registration request message may include a registration type, which indicates whether the UE wants to perform initial registration (i.e., the UE is in the RM-DEREGISTERED state), or mobility registration update (i.e., the UE is in the RM-REGISTERED state and the registration procedure is initiated because the UE moves, or the UE wants to update capabilities or protocol parameters, or the UE requests a change in the network slice set it is authorized to use), or periodic registration update (i.e., the UE is in the RM-REGISTERED state and the registration procedure is initiated due to expiration of the periodic registration update timer), or emergency registration (i.e., the UE is in a limited service state).

[0155] When a UE performs initial registration, it indicates the UE ID in the registration request message as follows, listed in order of decreasing priority:

[0156] i) If the UE has a valid evolved packet system (EPS) globally unique temporary identifier (GUTI), the 5G-GUTI mapped with the EPS GUTI;

[0157] ii) The native 5G-GUTI (if available) assigned by the PLMN to which the UE is attempting to register;

[0158] iii) A native 5G-GUTI assigned by a PLMN equivalent to the PLMN to which the UE is attempting to register;

[0159] iv) Native 5G-GUTI allocated by other PLMNs (if available);

[0160] v) Otherwise, the UE includes a subscriber concealed identifier (SUCI) in the registration request message.

[0161] Also, if the UE performing initial registration has both a valid EPS GUTI and a native 5G-GUTI, the UE displays the native 5G-GUTI as an additional GUTI. If one or more native 5G-GUTIs are available, the UE selects a 5G-GUTI from items (ii) to (iv) in the list in order of decreasing priority.

[0162] When the UE performs initial registration in native 5G-GUTI, the UE displays related GUAMI information in the AN parameters. When the UE performs initial registration in SUCI, the UE does not display GUAMI information in the AN parameters.

[0163] In the case of emergency registration, if the UE does not have a valid 5G-GUTI, the SUCI is included, and if the UE does not have a subscriber permanent identifier (SUPI) and a valid 5G-GUTI, the PEI (permanent equipment identifier) ​​is included. Otherwise, the 5G-GUTI is included, which indicates the last serving AMF.

[0164] The registration request message may also include security parameters, PDU session status, etc. The security parameters are used for authentication and integrity protection. The PDU session status indicates a PDU session previously established in the UE. When a UE is connected to two AMFs belonging to different PLMNs via a 3GPP connection and a non-3GPP connection, the PDU session status indicates the PDU session currently established in the PLMN in the UE.

[0165] (2) Step 2: (R)AN selects AMF.

[0166] If the 5G-S-TMSI or GUAMI is not included or does not indicate a valid AMF, the (R)AN selects an AMF, if available, based on the (R)AT and the requested NSSAI.

[0167] If the UE is in the CM-CONNECTED state, the (R)AN may transmit a registration request message to the AMF based on the N2 connection of the UE.

[0168] If the (R)AN cannot select an appropriate AMF, the (R)AN transmits a registration request message to the AMF configured in the (R)AN to perform AMF selection.

[0169] (3) Step 3: (R)AN sends a registration request message to the new AMF. The registration request message corresponds to the N2 message.

[0170] The registration request message may include all and / or part of the information included in the registration request message received from the UE described in step 1.

[0171] The registration request message may include an N2 parameter. When NG-RAN is used, the N2 parameter includes the selected PLMN ID (or PLMN ID and NID), location information and cell ID associated with the cell on which the UE is camped, and a UE context request indicating that a UE context including security information should be established in NG-RAN. When NG-RAN is used, the N2 parameter also includes an establishment cause.

[0172] If the registration type indicated by the UE is periodic registration update, steps 4-19 described below can be omitted.

[0173] (4) Step 4: If the UE's 5G-GUTI is included in the registration request message and the serving AMF has changed since the last registration procedure, the new AMF includes the full registration request NAS (non-access stratum) message to request the UE's SUPI and UE context. It can invoke the Namf_Communication_UEContextTransfer service operation on the previous AMF.

[0174] (5) Step 5: The previous AMF can respond to the Namf_Communication_UEContextTransfer call to the new AMF, including the UE's SUPI and UE context.

[0175] (6) Step 6: If the SUCI is not provided by the UE or has not been previously retrieved by the AMF, the new AMF may initiate the ID request procedure by sending an Identity Request message to request the SUCI from the UE.

[0176] (7) Step 7: The UE can respond with an Identity Response message containing the SUCI. The UE derives the SUCI using the provided public key of the Home PLMN (HPLMN).

[0177] (8) Step 8: The new AMF may decide to call the AUSF to initiate UE authentication. In this case, the new AMF selects the AUSF based on the SUPI or SUCI.

[0178] (9) Step 9: Authentication / security can be established by the UE, new AMF, AUSF and / or UDM.

[0179] (10) Step 10: If the AMF is changed, the new AMF can call the Namf_Communication_RegistrationCompleteNotify service operation to inform the previous AMF that UE registration to the new AMF is complete. If the authentication / security procedure fails, registration is rejected and the new AMF can call the Namf_Communication_RegistrationCompleteNotify service operation to the previous AMF with a reject indication reason code. The previous AMF can be maintained so that the UE context transfer service operation is not received.

[0180] (11) Step 11: If the PEI is not provided by the UE or has not been previously retrieved by the AMF, the new AMF may initiate the ID request procedure by sending an Identity Request message to the UE to retrieve the PEI from the UE. The PEI is sent encrypted unless the UE performs emergency registration and cannot be authenticated.

[0181] (12) Step 12: Optionally, the new AMF can call the N5g-eir_EquipmentIdentityCheck_Get service operation to initiate the ME ID check.

[0182] The procedure in FIG. 7, which follows the procedure in FIG. 6, will now be described.

[0183] (13) Step 13: When the following step 14 is executed, the new AMF can select a UDM based on the SUPI, and the UDM can select a UDR instance.

[0184] (14) Step 14: New AMF can be registered with UDM.

[0185] (15) Step 15: The new AMF can select a PCF.

[0186] (16) Step 16: The new AMF can selectively perform AM policy association establishment / modification.

[0187] (17) Step 17: The new AMF can send update / release SM context messages (e.g., Nsmf_PDUSession_UpdateSMContext and / or Nsmf_PDUSession_ReleaseSMContext) to the SMF.

[0188] (18) Step 18: If the new AMF and the previous AMF are in the same PLMN, the new AMF can send a UE context modification request to the N3IWF / TNGF / W-AGF.

[0189] (19) Step 19: The N3IWF / TNGF / W-AGF can send a UE context modification response to the new AMF.

[0190] (20) Step 20: After the new AMF receives the response message from the N3IWF / TNGF / W-AGF in step 19, the new AMF can register with the UDM.

[0191] (21) Step 21: The new AMF sends a Registration Accept message to the UE.

[0192] The new AMF sends a registration accept message to the UE indicating that the registration request has been accepted. If the new AMF assigns a new 5G-GUTI, the 5G-GUTI is included. If the UE is already in the RM-REGISTERED state through another connection in the same PLMN, the UE uses the 5G-GUTI received in the registration accept message for both registrations. If the registration accept message does not include the 5G-GUTI, the UE uses the 5G-GUTI assigned to the existing registration for the new registration. If the new AMF assigns a new registration realm, it sends the registration realm to the UE via the registration accept message. If the registration accept message does not include a registration realm, the UE considers the previous registration realm to be valid. Mobility restrictions are included when mobility restrictions are applied to the UE and the registration type is not emergency registration. The new AMF indicates the PDU sessions established for the UE in the PDU session state. The UE locally removes internal resources associated with PDU sessions that are not indicated as established in the received PDU session state. When a UE is connected to two AMFs belonging to different PLMNs via a 3GPP connection and a non-3GPP connection, the UE locally removes internal resources associated with PDU sessions of the current PLMN that are not indicated as established in the received PDU session status. If the PDU session status information is in the registration accept message, the new AMF indicates the PDU session status to the UE.

[0193] The Allowed NSSAIs provided in the Registration Accept message are valid for the registration area and apply to all PLMNs with tracking areas included in the registration area. Mapping of Allowed NSSAIs is to map the HPLMN S-NSSAI to each S-NSSAI in the Allowed NSSAIs. Mapping of Configured NSSAIs is to map the HPLMN S-NSSAI to each S-NSSAI in the Configured NSSAIs for the serving PLMN.

[0194] Optionally, the new AMF also performs UE policy association establishment.

[0195] (22) Step 22: If the UE successfully updates itself, it can send a Registration Complete message to the new AMF.

[0196] The UE may send a registration complete message to the new AMF to confirm whether a new 5G-GUTI has been assigned.

[0197] (23) Step 23: In the case of registration via a 3GPP connection, if the new AMF does not release the signaling connection, the new AMF may send RRC inactive assistance information to the NG-RAN. In the case of registration via a non-3GPP connection, if the UE is in the CM-CONTENED state on the 3GPP connection, the new AMF may send RRC inactive assistance information to the NG-RAN.

[0198] (24) Step 24: The AMF can perform an information update to the UDM.

[0199] (25) Step 25: The UE may perform a network slice-specific authentication and authorization (NSSAA) procedure.

[0200] <Network Slicing>

[0201] For a description of network slicing, please refer to section 4.6 of 3GPP TS 24.501 V16.4.1.

[0202] 5GS supports network slicing. Within a PLMN or SNPN (stand-alone non-public network), a network slice is identified by an S-NSSAI, which consists of a slice / service type (SST) and a slice differentiator (SD). Including an SD in an S-NSSAI is optional. A collection of one or more S-NSSAIs is called an NSSAI. The following NSSAIs can be defined:

[0203] a) configured NSSAI;

[0204] b) requested NSSAI;

[0205] c) allowed NSSAI;

[0206] d) subscribed NSSAI; and

[0207] e) Pending NSSAI

[0208] Additionally, the following NSSAIs can be defined:

[0209] a) rejected NSSAI for the current PLMN or SNPN;

[0210] b) rejected NSSAI for the current registration area; and

[0211] c) rejected NSSAI for the failed or revoked NSSAA

[0212] In the case of a PLMN, the serving PLMN may configure a Configured NSSAI to the UE for each PLMN. In addition, the HPLMN may configure a single basic Configured NSSAI to the UE and consider the basic Configured NSSAI to be valid in PLMNs where the UE does not have a configured NSSAI or an allowed NSSAI. In the case of an SNPN, the SNPN may configure the UE with a configured SNPN applicable to the SNPN.

[0213] The rejected NSSAIs and allowed NSSAIs for the current registration area are managed independently for each connection type (i.e., 3GPP connection or non-3GPP connection) and are applied to the registration area. If a registration area includes tracking area IDs (TAIs) that belong to different PLMNs, the rejected NSSAIs and allowed NSSAIs for the current registration area can be applied to the PLMNs within this registration area.

[0214] The allowed NSSAI associated with a registration area including TAIs belonging to different PLMNs, which are EPLMNs (equivalent PLMNs), can be used to form a requested NSSAI for any EPLMN when the UE leaves the registration area in which the allowed NSSAI was received.

[0215] When the NSSAA procedure is initiated for one or more S-NSSAIs in the Requested NSSAI, the corresponding S-NSSAIs can be included in the Pending NSSAI. When the NSSAA procedure is completed for an S-NSSAI in the Pending NSSAI, the corresponding S-NSSAI becomes an Accepted NSSAI or a Rejected NSSAI depending on the result of the NSSAA procedure and is notified to the UE. Pending NSSAIs are managed regardless of the connection type. That is, a pending NSSAI can be applied to both 3GPP and non-3GPP connections, regardless of whether it is sent to only one side.

[0216] The rejected NSSAI for the current PLMN or SNPN is applicable to all registered PLMNs or SNPNs. The AMF sends the rejected NSSAI for the current PLMN when the registration realm consists of TAIs belonging to only the registered PLMN. If the UE receives the rejected NSSAI for the current PLMN and the registration realm includes TAIs belonging to different PLMNs, the UE considers the received rejected NSSAI for the current PLMN to be applicable to all registered PLMNs.

[0217] The rejected NSSAI for a failed or revoked NSSAA includes one or more S-NSSAIs for which the NSSAA has failed or been revoked and is applicable to all registered PLMNs or SNPNs.

[0218] For a description of NSSAI storage, see section 4.6.2.2 of 3GPP TS 24.501 V16.4.1.

[0219] Generally, the Configured NSSAI is the UE's subscribed NSSAI when the UE is connected to the HPLMN and remains the same unless the UE's subscription information changes. However, due to changes in subscription information, an existing S-NSSAI can be created as the Configured NSSAI, or a specific S-NSSAI can be deleted. The AMF can then notify the UE of the updated S-NSSAI in the currently connected network.

[0220] In addition, the UE can store and save the configured NSSAI for the network visited by the UE in non-volatile memory. Therefore, when the UE selects a new VPLMN, the configured NSSAI information of the previously visited network can be present. Therefore, when performing PLMN selection, the UE can have the configured NSSAI information of the PLMN selected by the UE.

[0221] Furthermore, if there is a service level agreement (SLA) between the HPLMN and VPLMN to which the UE can connect, the UE can know what HPLMN's S-NSSAI the VPLMN has.

[0222] If possible, the Configured NSSAI is stored in the non-volatile memory of the UE. The Allowed NSSAI is stored in the non-volatile memory of the UE.

[0223] Each Configured NSSAI stored in the UE is a set of up to 16 S-NSSAIs. Each Allowed NSSAI stored in the UE is a set of up to 8 S-NSSAIs and is associated with a PLMN ID or SNPN ID and a connection type. Each Configured NSSAI, excluding rejected NSSAIs and basic Configured NSSAIs, is associated with a PLMN ID or SNPN ID. An S-NSSAI in a rejected NSSAI for the current registration area is additionally associated with the registration area in which the rejected S-NSSAI cannot be used. An S-NSSAI in a rejected NSSAI for the current PLMN or SNPN is considered rejected for the current PLMN or SNPN regardless of the connection type. An S-NSSAI in a rejected NSSAI for an NSSAI and NSSAA failure or withdrawal is considered rejected for the current PLMN regardless of the connection type. There are no duplicate PLMN IDs or SNPN IDs in each of the lists of Configured NSSAI, Allowed NSSAI, Rejected NSSAI for the current PLMN or SNPN, and Rejected NSSAI for the current registration area.

[0224] The UE stores the NSSAI as follows:

[0225] a) The Configured NSSAI is stored until a new Configured NSSAI is received for a given PLMN or SNPN. The network can also provide the UE with an S-NSSAI mapped to the new Configured NSSAI stored in the UE. When the UE receives a new Configured NSSAI for a PLMN or SNPN, the UE must perform the following:

[0226] 1) Replace the stored Configured NSSAI for this PLMN or SNPN with a new Configured NSSAI for this PLMN or SNPN;

[0227] 2) Delete the stored mapped S-NSSAI for the Configured NSSAI and, if possible, store the mapped S-NSSAI for the new Configured NSSAI;

[0228] 3) Delete the stored allowed NSSAI for this PLMN or SNPN, and, if possible, delete the stored mapped S-NSSAI for the allowed NSSAI if the UE receives a new Configured NSSAI for this PLMN or SNPN via the same Configuration Update Command message and a configuration update indication IE with the Registration requested bit set to "Registration requested", and the message does not contain a new allowed NSSAI for this PLMN or SNPN;

[0229] 4) Delete the stored rejected NSSAI for the current PLMN or SNPN, rejected NSSAI for the current registration area, NSSAI and rejected NSSAI for NSSAA failure or withdrawal.

[0230] When the UE receives an S-NSSAI associated with a PLMN ID from the network during the PDN connection establishment procedure in EPS, the UE may store the received S-NSSAI as the Configured NSSAI for the PLMN identified as the PLMN ID associated with the S-NSSAI (if not already stored in the Configured NSSAI).

[0231] When the UE registers with another PLMN, the UE may continue to store the Configured NSSAI and associated mapped S-NSSAI received for the PLMN, if possible.

[0232] b) The allowed NSSAI is stored until a new allowed NSSAI is received for a given PLMN or SNPN. The network may also provide the UE with an S-NSSAI mapped to the new allowed NSSAI stored in the UE. When a new allowed NSSAI is received for a PLMN or SNPN, the UE performs the following:

[0233] 1) Replace the stored allowed NSSAI for this PLMN or SNPN with the new allowed NSSAI for this PLMN or SNPN;

[0234] 2) Delete the stored mapped S-NSSAI for the accepted NSSAI and, if possible, store the mapped S-NSSAI for the new accepted NSSAI;

[0235] 3) Remove the S-NSSAI (if any) currently included in the new accepted NSSAI for the PLMN or SNPN from the stored rejected NSSAI;

[0236] 4) Remove one or more S-NSSAIs (if any) currently included in the newly allowed NSSAI for the PLMN or SNPN from the stored pending NSSAIs.

[0237] When the UE receives a Configuration Update Command message with the Registration Request bit in the Configuration Update Indication IE set to "Registration Request" and no other parameters, the UE shall delete the allowed NSSAIs stored for this PLMN or SNPN and, if possible, delete the mapped S-NSSAIs stored for the allowed NSSAIs.

[0238] c) When the UE receives an S-NSSAI included in a rejected NSSAI in a registration accept message, registration reject message, deregistration request message, or configuration update command message, the UE performs the following:

[0239] 1) Store the S-NSSAI into the rejected NSSAI based on the associated rejection cause;

[0240] 2) Remove the S-NSSAI (if any) currently contained in the stored allowed NSSAIs for the PLMN or SNPN:

[0241] i) Rejected NSSAI for the current PLMN or SNPN for each and every connection type;

[0242] ii) A rejected NSSAI for a currently registered domain associated with the same connection type; and

[0243] iii) Rejected NSSAI for NSSAA failure or withdrawal for each and every connection type;

[0244] 3) Remove one or more S-NSSAIs (if any) that are currently stored pending NSSAIs for the PLMN or SNPN and include:

[0245] i) Rejected NSSAI for the current PLMN or SNPN for each and every connection type;

[0246] ii) A rejected NSSAI for a currently registered domain associated with the same connection type; and

[0247] iii) Rejected NSSAI for NSSAA failure or withdrawal for each and every connection type;

[0248] UE,

[0249] 1) deregisters with the current PLMN using explicit signaling or enters 5GMM-DEREGISTERED state with respect to the current PLMN; or

[0250] 2) Upon successful registration with a new PLMN; or

[0251] 3) Upon entering 5GMM-DEREGISTERED state after a failed new PLMN registration;

[0252] If the UE is not currently registered to the PLMN via another connection, the rejected NSSAI for the current PLMN is deleted.

[0253] UE,

[0254] 1) Unsubscribe via the connection type;

[0255] 2) successfully registering in a new registration area via a connection type; or

[0256] 3) Entering 5GMM-REGISTERED or 5GMM-DEREGISTERED state after failing to register in a new registration area via a connection type;

[0257] Rejected NSSAIs for currently registered areas that correspond to the connection type will be deleted.

[0258] d) When the UE receives one or more S-NSSAIs included in the pending NSSAI in the registration accept message, the UE stores one or more S-NSSAIs for the pending NSSAIs.

[0259] UE,

[0260] 1) Deregisters with the current PLMN using explicit signaling or enters 5GMM-DEREGISTERED state with respect to the current PLMN;

[0261] 2) Upon successful registration with the new PLMN;

[0262] 3) Upon entering 5GMM-DEREGISTERED state after a failed new PLMN registration;

[0263] 4) Successfully completing an attach or tracking region update procedure in S1 mode; or

[0264] 5) Initiating an attach or tracking area update procedure in S1 mode and receiving an attach reject message or a tracking area update reject message;

[0265] If the UE is not currently registered to the PLMN via another connection, the currently pending NSSAI for the PLMN is deleted.

[0266] e) For PLMNs, when the UE receives a network slicing indication IE in a registration accept message or a configuration update command message with the network slicing subscription change indication set to "Network slicing subscription changed," the UE deletes the network slicing information for each PLMN (excluding the current PLMN) that stores the network slicing information. The UE does not delete the basic configured NSSAI. Additionally, the UE updates the network slicing information for the current PLMN (if received) as described in a), b), c), and e).

[0267] The pending NSSAI indicates the S-NSSAI provided by the serving PLMN during the registration procedure, for which the network slice specific authentication and authorization procedure is pending.

[0268] <non-3GPPアクセス>

[0269] Non-3GPP access networks include untrusted non-3GPP access networks, trusted non-3GPP access networks, and W-5GANs.

[0270] The UE shall enter the RM-DEREGISTERED state for UEs in non-3GPP access and the AMF shall enter the RM-DEREGISTERED state as follows:

[0271] -After performing the explicit deregistration procedure, the UE and AMF

[0272] In AMF, after the network non-3GPP implicit deregistration timer expires.

[0273] At the UE, after the UE non-3GPP deregistration timer expires.

[0274] A UE registered via non-3GPP access starts the UE non-3GPP deregistration timer according to the value received from the AMF during the registration procedure each time it enters the CM-IDLE state for non-3GPP access.

[0275] Over non-3GPP access, the AMF runs a network non-3GPP implicit deregistration timer. The network non-3GPP implicit deregistration timer is started with a value longer than the UE's non-3GPP deregistration timer every time the CM state for a UE registered over non-3GPP access changes to CM-IDLE for non-3GPP access.

[0276] For a UE registered via non-3GPP access, a change of attachment point (e.g., a change of WLAN AP) shall not cause the UE to perform the registration procedure.

[0277] A UE registered via a non-3GPP access may trigger a mobility registration update procedure via the new non-3GPP AN node (i.e., N3IWF or TNGF) to divert traffic from the previous non-3GPP access to the new non-3GPP access.

[0278] During the registration procedure, the AMF can determine whether the serving N3IWF / TNGF is appropriate based on the slices supported by the N3IWF / TNGF.

[0279] 1. Select N3IWF

[0280] If the UE supports connectivity with the N3IWF but does not support connectivity with the ePDG, the UE performs a certain procedure to select the N3IWF.

[0281] When the UE supports connection with not only the ePDG but also the N3IWF, the UE must perform a certain procedure to select one of the N3IWF or the ePDG, i.e., to select a non-3GPP access node.

[0282] In both cases, the UE can be configured by the HPLMN with the same information, including:

[0283] 1) ePDG Identifier Configuration: Contains the FQDN or IP address of the ePDG in the HPLMN. This is used only if the UE supports connection with the ePDG and attempts to select an ePDG. Ignored in all other cases.

[0284] 2) N3IWF Identifier Configuration: Contains the FQDN or IP address of the N3IWF in the HPLMN.

[0285] 3) Extended Home N3IWF Identifier Configuration: Contains the FQDN / IP address of the N3IWF in the HPLMN and one or more tuples of S-NSSAIs supported by this N3IWF.

[0286] 4) Non-3GPP Access Node Selection Information: This includes a PLMN priority list and, for each PLMN, (i) a "Preference" parameter indicating whether an ePDG or N3IWF is preferred in this PLMN, and (ii) an FQDN parameter. This indicates whether the TA / Location Area ID FQDN or the Operator Identifier FQDN should be used when searching for the address of an ePDG or N3IWF in this PLMN. The PLMN list must include the HPLMN and an "All PLMNs" item that matches all PLMNs to which the UE is connected except for the HPLMN.

[0287] 5) Slice-specific N3IWF prefix configuration: Includes one or more tuples configured as follows:

[0288] -Supported S-NSSAI Inventory

[0289] - prefixed N3IWF OI or TA FQDN prefix.

[0290] Reference 1: It is assumed that the extended home N3IWF identifier configuration and slice-specific N3IWF prefix configuration are provided to the UE as part of the ANDSP.

[0291] The ePDG identifier configuration, N3IWF identifier configuration, extended home N3IWF identifier configuration, and slice-specific N3IWF prefix configuration are optional parameters, whereas the non-3GPP access node selection information is mandatory and must include at least the HPLMN and "any PLMN" items.

[0292] If the ePDG identifier configuration is configured in the UE, when the UE decides to select an ePDG in the HPLMN, the UE must use the ePDG identifier configuration to find the IP address of the HPLMN. The ePDG of the HPLMN must be specified and the FQDN parameter of the HPLMN must be ignored in the non-3GPP access node selection information.

[0293] If an N3IWF identifier configuration or an extended home N3IWF identifier configuration is configured in the UE, when the UE decides to select an N3IWF in the HPLMN, the UE shall use the extended home N3IWF identifier configuration if possible, otherwise it shall use the N3IWF identifier configuration to find the IP address of the N3IWF in the HPLMN and shall ignore the FQDN parameter of the HPLMN in the non-3GPP access node selection information.

[0294] The PCF of the HPLMN takes into account the S-NSSAI to which the UE has subscribed when providing the UE with an extended home N3IWF identifier configuration and / or a slice-specific N3IWF prefix configuration.

[0295] If the UE does not support the extended home N3IWF identifier configuration and slice-specific N3IWF prefix configuration, the HPLMN provides the UE with non-3GPP access node selection information and N3IWF identifier configuration taking into account the UE's subscribed S-NSSAIs.

[0296] Reference 2: If the HPLMN deploys various N3IWFs using different TAs that support different S-NSSAIs, the HPLMN can configure the UE with an N3IWF identifier configuration so that the UE can select an N3IWF that supports the UE's subscribed S-NSSAI.

[0297] The UE may be configured by the VPLMN with the following information applicable to V-PLMN:

[0298] Slice-specific N3IWF prefix configuration: Contains one or more tuples configured as follows:

[0299] -Supported S-NSSAI Inventory

[0300] - prefixed N3IWF OI or TA FQDN prefix.

[0301] To enable the V-PCF to provide the UE with a per-slice N3IWF prefix configuration, the AMF provides the V-PCF with the NSSAI configured for the serving PLMN during the UE policy connection setup / modification procedure.

[0302] Note 3: In the non-roaming case, the UE PCF receives the NSSAI already subscribed from the UDR. Therefore, in the non-roaming case, the AMF does not need to provide the configured NSSAI to the PCF.

[0303] Reference 4: PCF (V-PCF in case of roaming) is assumed to be locally configured and is information on slices supported by different N3IWFs of the serving PLMN.

[0304] During the registration procedure, the AMF may determine whether the N3IWF selected by the UE is suitable for the S-NSSAI(s) requested by the UE in consideration of the UE joining. If the AMF determines that another N3IWF must be selected, the AMF shall:

[0305] If the UE supports slice-based N3IWF selection, it may trigger a UE policy-related configuration or UE policy-related update procedure to provide the UE with updated N3IWF selection information. When the AMF is notified that the N3IWF selection information update is complete, the AMF may release the UE policy connection if not necessary before proceeding to registration denial.

[0306] -A registration rejection message must be sent to the UE. If the UE supports it, the AMF may include target N3IWF information (FQDN and / or IP address) in the registration rejection so that the UE can use the target N3IWF information to select an N3IWF to register with 5GC. The target N3IWF information applies only to the single N3IWF selection performed by the UE immediately after receiving the registration rejection.

[0307] The AMF can determine the N3IWF based on the obtained list of supported TAs and the corresponding list of supported slices for each TA.

[0308] 2.Trusted Non-3GPP access network selection

[0309] A method is defined for a UE that is attempting to establish a connection via trusted non-3GPP access and is not operating in an SNPN access mode to select a PLMN and a trusted non-3GPP access network (TNAN) to connect to.

[0310] For example, the UE may decide to use Trusted Non-3GPP access to connect to a 5GC in a particular PLMN based on the following:

[0311] - UE implementation specific criteria; or

[0312] UE configuration, e.g., the UE may be configured to first attempt a Trusted Non-3GPP access procedure; or

[0313] UE capabilities, e.g., the UE can only support Trusted Non-3GPP access procedures; or

[0314] -Advertised capabilities of discovered non-3GPP access networks. One or more available non-3GPP access networks advertise reliable connection support for 5GC of a particular PLMN.

[0315] In the deployment scenario, the UE discovers five non-3GPP access networks, which are WLAN access networks. These WLANs advertise information about the PLMNs they interact with using the ANQP protocol. Each WLAN can support "S2a connectivity" and / or "5G connectivity" to one or more PLMNs. Before establishing a connection via a trusted non-3GPP access, the UE must select (a) the PLMN, (b) the non-3GPP access network that provides a reliable connection to this PLMN, and (c) the connection type, i.e., "5G connectivity" or "S2a connectivity."

[0316] Each non-3GPP access network may advertise one or more of the following PLMN inventories:

[0317] 1) PLMN List-1 includes PLMNs for which "AAA connectivity" is supported. A non-3GPP access network supports "AAA connectivity" with a PLMN when it distributes AAA functionality that can interface with this PLMN's 3GPP AAA server / proxy via the STa interface (from trusted WLAN to EPC) or the SWa interface (from untrusted WLAN to EPC).

[0318] 2) PLMN List-2 including PLMNs where 'S2a connectivity' is supported. A non-3GPP access network supports 'S2a connectivity' with a PLMN when it distributes a TWAG function that can connect to the PGW of this PLMN via the S2a interface.

[0319] 3) PLMN List-3, which includes PLMNs that support '5G connectivity'. A non-3GPP access network supports '5G connectivity' with a PLMN when it distributes a TNGF function that can connect to the AMF function and UPF function of this PLMN via the N2 and N3 interfaces, respectively.

[0320] If a UE wishes to search for a list of PLMNs supported by a non-3GPP access network and the non-3GPP access network supports ANQP, the UE shall send an ANQP query to the non-3GPP access network requesting "3GPP Cellular Network" information. If the non-3GPP access network supports interworking with one or more PLMNs, the response received by the UE includes a "3GPP Cellular Network" information element containing one or more of the three PLMN lists. PLMN List-1 and PLMN List-2 indicate support for interworking with EPC in one or more PLMNs. PLMN List-3 is a list used to indicate support for interworking with 5GC in one or more PLMNs. If the non-3GPP access network does not support ANQP, the method by which the UE discovers the list of PLMNs supported by the non-3GPP access network is not defined herein.

[0321] The UE receives PLMN List-2 and PLMN List-3 advertised by this access network and determines whether the non-3GPP access network supports "trusted connectivity" to a particular PLMN. If this PLMN is not included in either of these lists, the non-3GPP access network can only support connectivity to the PLMN's ePDG or N3IWF (i.e., "untrusted connectivity").

[0322] The problem is how to select the TNGF / N3IWF that supports the S-NSSAI required by the UE.

[0323] The selection of the N3IWF that supports the S-NSSAI required for the UE can be activated based on the extended ANDSP configuration and NAS-based redirection (using Registration Reject).

[0324] TNGF selection to support the S-NSSAI required for the UE can be activated based on the following:

[0325] -It is a UE-based solution in which the UE uses the WLANSP policy to select an SSID that allows access to the TNGF that supports the slice used by the UE, and then uses this information to attempt to register with 5GC via the TNGF.

[0326] -WLANSP policy is extended to indicate slice aggregation associated with SSID.

[0327] The AMF can determine that the UE used an incorrect SSID based on information received from the TNGF via N2.

[0328] If the selected SSID (TNGF) does not support the slice requested by the UE, the AMF may trigger a UE policy-related configuration procedure to provide the UE with an updated WLANSP. The AMF requests the PCF to be notified when the PCF completes the WLANSP update. When the AMF receives this notification from the PCF, the AMF may issue a registration rejection.

[0329] The AMF may provide the UE with target TNAN information (e.g., SSID) associated with the Requested NSSAI in the registration rejection message.

[0330] The UE selects the appropriate SSID associated with the Requested NSSAI and builds the NAI area.

[0331] During the registration procedure, the AMF may determine whether the N3IWF selected by the UE is suitable for the S-NSSAI(s) Requested by the UE, taking into account the UE's subscription. If the AMF determines that another N3IWF must be selected, the AMF may:

[0332] If the UE supports slice-based N3IWF selection, it may trigger a UE Policy Association Establishment or UE Policy Association Update procedure to provide the UE with updated N3IWF selection information. When the AMF is notified that the N3IWF selection information update is complete, the AMF may release the UE policy association if not necessary before proceeding to registration rejection.

[0333] -A registration rejection message must be sent to the UE. If the UE supports it, the AMF may include target N3IWF information (FQDN and / or IP address) in the registration rejection so that the UE can use the target N3IWF information to select an N3IWF to register with 5GC. The target N3IWF information may only apply to the single N3IWF selection performed by the UE immediately after receiving the registration rejection.

[0334] If the AMF includes the N3IWF information in the Registration Reject, the terminal can select an N3IWF using the N3IWF information when sending the next Registration Request.

[0335] The N3IWF information is the N3IWF information appropriate for the terminal that the AMF notifies the terminal based on the Requested NSSAI requested by the terminal.

[0336] If the terminal configures the Requested NSSAI according to the previous operation while performing registration again (i.e., if the Requested NSSAI is configured based on the Configured NSSAI and Allowed NSSAI), the terminal can request a new S-NSSAI in the Requested NSSAI.

[0337] In this case, the N3IWF selected by the terminal based on the N3IWF information notified by the AMF may not support the Requested S-NSSAI included in the registration request.

[0338] The N3IWF information provided by the AMF is based on the NSSAI previously included in the registration request, and therefore the N3IWF selected based on this information will not be able to support the new NSSAI.

[0339] Therefore, the AMF may reject the terminal registration again. This rejection may occur repeatedly. That is, a "loop of registration request" phenomenon may occur. This problem needs to be solved.

[0340] In relation to this, the standards related to the registration process are as shown in Table 3.

[0341] [Table 3]

[0342] This specification proposes methods for solving the above-mentioned problems. The methods described below can be implemented or used in combination or complementarily. The explanations made in this specification based on N3IWF can also be applied to TNGF selection in a similar manner.

[0343] The following embodiments are not alternatives and may be implemented in combination with one another.

[0344] I. First Example

[0345] (1) General

[0346] There are the following problems:

[0347] -The PCF notifies the AMF that the UE policy update is complete, and the AMF sends a Registration Reject based on this. However, the question remains as to whether the PCF should notify the AMF about the completion of policy transmission.

[0348] The AMF may release the UE policy association before sending a Registration Reject. However, if the association is not released, the association may still be maintained even if the UE is not registered in the network.

[0349] If the AMF provides target N3IWF information in Registration Reject, and the UE supports it, the UE may select an N3IWF using the target N3IWF information. However, if the UE changes the Requested NSSAI, the target N3IWF information is no longer valid.

[0350] The following method can be proposed:

[0351] -The policy transmission completion indication from PCF to AMF can be removed.

[0352] -AMF may release UE policy connection before sending registration rejection.

[0353] If the UE receives target N3IWF information via the registration rejection message, the UE may use the same Requested NSSAI as the network slice included in the Requested NSSAI of the previous registration request message.

[0354] (2) Select N3IWF

[0355] The UE may perform a procedure to select an N3IWF.

[0356] When the UE supports connection with not only the ePDG but also the N3IWF, the UE may perform a procedure to select one of the N3IWF or the ePDG, i.e., to select a non-3GPP access node.

[0357] In both cases, the UE can be configured by the HPLMN with the same information, including:

[0358] 1) ePDG Identifier Configuration: This can include the FQDN or IP address of the ePDG in the HPLMN. This can only be used if the UE supports connection with the ePDG and attempts to select an ePDG. It can be ignored in all other cases.

[0359] 2) N3IWF Identifier Configuration: It may contain the FQDN or IP address of the N3IWF in the HPLMN.

[0360] 3) Extended Home N3IWF Identifier Configuration: It may contain one or more tuples of the FQDN / IP address of the N3IWF in the HPLMN and the S-NSSAI supported by this N3IWF.

[0361] 4) Non-3GPP Access Node Selection Information: This includes a PLMN priority list and, for each PLMN, (i) a "Preference" parameter indicating whether an ePDG or N3IWF is preferred in this PLMN, and (ii) an FQDN parameter. It can indicate whether a TA / Location Area ID FQDN or an Operator Identifier FQDN should be used when searching for an ePDG or N3IWF address in this PLMN. The PLMN list should include the HPLMN and may include an "All PLMNs" item that matches all PLMNs to which the UE is connected, except for the HPLMN.

[0362] 5) Slice-specific N3IWF prefix configuration: It can include one or more tuples configured as follows:

[0363] -Supported S-NSSAI Inventory

[0364] - prefixed N3IWF OI or TA FQDN prefix.

[0365] Reference 1: It can be assumed that the extended home N3IWF identifier configuration and slice-specific N3IWF prefix configuration are provided to the UE as part of the ANDSP.

[0366] The ePDG identifier configuration, N3IWF identifier configuration, extended home N3IWF identifier configuration, and slice-specific N3IWF prefix configuration are optional parameters, whereas the non-3GPP access node selection information is mandatory and may include at least the HPLMN and "any PLMN" entries.

[0367] If the ePDG identifier configuration is configured in the UE, when the UE decides to select an ePDG in the HPLMN, the UE can use the ePDG identifier configuration to find the IP address of the HPLMN. The ePDG of the HPLMN can be specified and the FQDN parameter of the HPLMN can be ignored in the non-3GPP access node selection information.

[0368] If an N3IWF identifier configuration or an extended home N3IWF identifier configuration is configured in the UE, when the UE decides to select an N3IWF in the HPLMN, the UE may use the extended home N3IWF identifier configuration if available, otherwise it may use the N3IWF identifier configuration to find the IP address of the N3IWF in the HPLMN and ignore the FQDN parameter of the HPLMN in the non-3GPP access node selection information.

[0369] The PCF of the HPLMN may take into account the S-NSSAI to which the UE subscribes when providing the extended home N3IWF identifier configuration and / or slice-specific N3IWF prefix configuration to the UE.

[0370] If the UE does not support the extended home N3IWF identifier configuration and slice-specific N3IWF prefix configuration, the HPLMN can provide the UE with non-3GPP access node selection information and N3IWF identifier configuration taking into account the UE's subscribed S-NSSAI.

[0371] Reference 2: If the HPLMN deploys various N3IWFs using different TAs that support different S-NSSAIs, the HPLMN can configure the UE with an N3IWF identifier configuration so that the UE can select an N3IWF that supports the UE's subscribed S-NSSAI.

[0372] The UE may be configured by the VPLMN with the following information applicable to V-PLMN:

[0373] Slice-specific N3IWF prefix configuration: Can contain one or more tuples configured as follows:

[0374] -Supported S-NSSAI Inventory

[0375] - prefixed N3IWF OI or TA FQDN prefix.

[0376] To enable the V-PCF to provide the UE with a per-slice N3IWF prefix configuration, the AMF may provide the V-PCF with the NSSAI configured for the serving PLMN during the UE policy connection setup / modification procedure.

[0377] Note 3: In the non-roaming case, the UE PCF can receive the NSSAI already subscribed from the UDR. Therefore, in the non-roaming case, the AMF does not need to provide the configured NSSAI to the PCF.

[0378] Reference 4: PCF (V-PCF in case of roaming) is information on slices supported by different N3IWFs of the serving PLMN and can be assumed to be locally configured.

[0379] During the registration procedure, the AMF can determine whether the N3IWF selected by the UE is suitable for the S-NSSAI(s) requested by the UE taking into account the UE subscriber information.

[0380] If the AMF determines that the N3IWF selected by the UE is not suitable, the AMF may determine that the UE must select another N3IWF. In this case, the AMF may perform the following:

[0381] If the UE supports slice-based N3IWF selection, the AMF may trigger a UE Policy Association Establishment or UE Policy Association Update procedure to provide the UE with updated N3IWF selection information. When the AMF detects that the N3IWF selection information update is complete, the AMF may release the UE policy association before proceeding with registration rejection.

[0382] The AMF may send a registration rejection message to the UE. If the UE supports it, the AMF may include target N3IWF information (FQDN and / or IP address) in the registration rejection message so that the UE can use the target N3IWF information to select an N3IWF to register with 5GC. If the UE wants to include the same Requested NSSAI as the previous registration request in the new registration request, the UE may use the target N3IWF information (FQDN and / or IP address) (if supported by the UE) to select an N3IWF and attempt to register with 5GC.

[0383] The target N3IWF information may only apply to the single N3IWF selection performed by the UE immediately after receiving the registration rejection message. When performing registration, if the UE uses the target N3IWF information, the UE may include the same Requested NSSAI as that included in the previous registration request. The UE may send a registration request including the same Requested NSSAI as that included in the previous registration request.

[0384] Alternatively, the terminal may select a portion of the S-NSSAI from the Requested NSSAIs previously sent and send it as the Requested NSSAI.

[0385] Alternatively, only if the terminal selects an S-NSSAI that is the same as or part of a previously sent Requested NSSAI and sends it as the Requested NSSAI, the terminal can perform N3IWF selection using the target N3IWF information provided by the AMF. That is, if the terminal adds a new S-NSSAI that is not an S-NSSAI previously included in the Requested NSSAI, the terminal can perform a new N3IWF selection using the N3IWF selection procedure. In this case, the terminal can perform N3IWF selection without using the target N3IWF information.

[0386] The AMF can determine the N3IWF based on the obtained list of supported TAs and the corresponding list of supported slices for each TA.

[0387] II. Second Example

[0388] (1) General

[0389] A method is needed to prevent registration request loops and AMF rejections when there are errors in policy updates, provided UE policies, etc. The following methods can be proposed for this purpose.

[0390] If the AMF detects that the UE is attempting registration several times without selecting an appropriate N3IWF, the AMF accepts the UE registration and only S-NSSAIs supported by the selected N3IWF may be included in the allowed NSSAI.

[0391] The question arises as to whether the PCF needs to inform the AMF of the completion of policy transmission. The following methods can be proposed to address this issue.

[0392] Basically, the UE policy update procedure is transparent to the AMF, and the AMF cannot know whether the policy update is completed. After the policy update is completed, no messages are exchanged between the UE and the PCF. If the AMF detects that messages are not exchanged, it can send a Registration Reject to the UE. The AMF can run a locally configured inactivity timer to detect the completion of the UE policy update.

[0393] (2) Registration procedures for untrusted non-3GPP access

[0394] 8a, 8b, and 8c illustrate registration over untrusted non-3GPP access according to an embodiment of the present disclosure.

[0395] The signal flows in Figures 8a, 8b and 8c do not show all the details of the registration procedure over untrusted non-3GPP access, but mainly show the steps performed between the UE and the N3IWF.

[0396] 1. A UE can connect to an untrusted non-3GPP access network through an appropriate authentication procedure and receive an IP address assignment. For example, a non-3GPP-based authentication method such as EAP, which includes no authentication (in the case of a free WLAN), a pre-shared key, or a user name / password, can be used. When a UE decides to connect to a 5GC network, a UE not operating in SNPN access mode can select an N3IWF from a 5G PLMN. When a UE decides to connect to a 5GC network, a UE operating in SNPN access mode can select an N3IWF in the SNPN.

[0397] Reference 1: UE selection of N3IWF supporting S-NSSAI required for UE can be activated based on ANDSP configuration.

[0398] 2. The UE can initiate an IKE initial exchange and proceed with IPsec Security Association (SA) setup with the selected N3IWF. All subsequent IKE messages after step 2 can be encrypted and integrity protected using the IKE SA established in this step.

[0399] 3. The UE can initiate the IKE_AUTH exchange by sending an IKE_AUTH request message. The AUTH payload is not included in the IKE_AUTH request message. This may indicate that the IKE_AUTH exchange should use EAP signaling (in this case, EAP-5G signaling). If the UE supports MOBIKE, it should include a Notify payload in the IKE_AUTH request, which may indicate that MOBIKE is supported. Also, if the UE is provisioned with an N3IWF root certificate, it must include a CERTREQ payload in the IKE_AUTH request message to request the N3IWF certificate.

[0400] 4. The N3IWF can respond with an IKE_AUTH response message including an EAP-Request / 5G-Start packet. The EAP-Request / 5G-Start packet can inform the UE to start an EAP-5G session, i.e., to start sending NAS messages encapsulated in EAP-5G packets. If the N3IWF receives a CERTREQ payload from the UE, the N3IWF must include a CERT payload in the IKE_AUTH response message containing the N3IWF's certificate.

[0401] 5. The UE shall send an IKE_AUTH request including an EAP response / 5G-NAS packet containing an access network parameter (AN parameter) and a registration request message. The AN parameter may include information used by the N3IWF to select an AMF in the 5G core network. For example, this information may include the GUAMI, the selected PLMN ID (or PLMN ID and NID, see clause 5.30 of TS 23.501 [2]), the requested NSSAI, and the establishment cause. The establishment cause may provide the reason for requesting a signaling connection with the 5GC. Whether and how the UE includes the requested NSSAI as part of the AN parameter may depend on the value of the access stratum connection establishment NSSAI inclusion mode parameter. The registration request may include an indication that the UE supports N3IWF selection based on the slice the UE desires to use over untrusted non-3GPP access (i.e., an indication that the UE supports extended home N3IWF identifier configuration and slice-specific N3IWF prefix configuration).

[0402] Note 2: Because the UE includes the corresponding ID in the first IKE_AUTH, the N3IWF does not send an EAP-Identity request.

[0403] 6. The N3IWF can select an AMF based on the received AN parameters and local policies. The N3IWF can transmit the registration request received from the UE to the selected AMF in an N2 message. This message can include N2 parameters including the selected PLMN ID, the optionally selected NID, and the configuration cause.

[0404] Note 3: The selected NID may be present when the UE connects to the SNPN via an untrusted non-3GPP access.

[0405] 7. The selected AMF may decide to request SUCI by sending a NAS Identity Request message to the UE. This NAS message and all subsequent NAS messages may be encapsulated in EAP / 5G-NAS packets and sent to the UE.

[0406] 8. The AMF may decide to invoke the AUSF to authenticate the UE. In this case, the AMF may select the AUSF based on the SUPI or SUCI.

[0407] The AUSF may perform UE authentication. The AUSF may select a UDM and bring authentication data in the UDM. The authentication packet may be encapsulated in a NAS authentication message, and the NAS authentication message may be encapsulated in an EAP / 5G-NAS packet. After successful authentication:

[0408] In step 8h, the AUSF can send the anchor key (SEAF key) to the AMF, which the AMF uses to derive the NAS security key and the security key for the N3IWF (N3IWF key). The UE can also derive the anchor key (SEAF key) and use it to derive the NAS security key and the security key for the N3IWF (N3IWF key). The N3IWF key can be used by the UE and N3IWF to establish an IPsec security association (step 11).

[0409] In step 8h, the AUSF may also include a SUPI if the AMF provided the AUSF with a SUCI in step 8a.

[0410] Reference 4: EAP-AKA' or 5G-AKA can be allowed for UE authentication via non-3GPP access. Figures 8a, 8b, and 8c show only the authentication flow using EAP-AKA'. Authentication methods other than EAP-AKA' or 5G-AKA can be allowed not only for UEs accessing SNPN services via PLMN, but also for UEs accessing SNPN services directly via untrusted non-3GPP access.

[0411] 9a. The AMF can send a NAS security mode command to the UE to activate NAS security. If EAP-AKA' authentication is successfully performed in step 8, the AMF can encapsulate the EAP-Success received from the AUSF in a NAS security mode command message.

[0412] 9b. The N3IWF may convey a NAS security mode command message to the UE within an EAP / 5G-NAS packet.

[0413] 9c. The UE can complete EAP-AKA' authentication (if initiated in step 8), generate a NAS security context and N3IWF key, and send a NAS security mode complete message in an EAP / 5G-NAS packet.

[0414] 9d. The N3IWF can relay the NAS Security Mode Complete message to the AMF.

[0415] 10a. Upon receiving NAS security mode completion, the AMF may send an NGAP initial context setup request message including the N3IWF key.

[0416] 10b. This can trigger the N3IWF to send an EAP-Success to the UE, which completes the EAP-5G session. No further EAP-5G packets are exchanged.

[0417] 11. An IPsec SA can be established between the UE and the N3IWF using the common N3IWF key generated by the UE in step 9c and received by the N3IWF in step 10a. This IPsec SA can be referred to as the "signaling IPsec SA." After the signaling IPsec SA is established, the N3IWF can send an NGAP initial context setup response to inform the AMF that the UE context (including AN security) has been created. The signaling IPsec SA must be configured to operate in tunnel mode, and the N3IWF can assign an "internal" IP address to the UE. If the N3IWF receives an indication that the UE supports MOBIKE (see step 3), the N3IWF can include a notification payload in the IKE_AUTH response message sent in step 11a indicating that MOBIKE must be supported as specified in RFC 4555.

[0418] All subsequent NAS messages exchanged between the UE and the N3IWF must be sent via the signaling IPsec SA and can be transmitted via TCP / IP. The UE can send NAS messages in TCP / IP packets whose source address is the UE's "internal" IP address and whose destination address is the NAS_IP_ADDRESS received in step 11a. The N3IWF can send NAS messages in TCP / IP packets whose source address is the NAS_IP_ADDRESS and whose destination address is the UE's "internal" IP address. The TCP connection used for reliable NAS transmission between the UE and the N3IWF can be initiated by the UE immediately after the signaling IPsec SA is established in step 11a. The UE can send a TCP connection request with the specified TCP port number and NAS_IP_ADDRESS.

[0419] 12. The AMF can determine the subset of requested NSSAIs allowed by the subscribed S-NSSAI. After the AMF detects that the N3IWF used by the UE is not compatible with this subset, it can proceed to steps 15-19. Otherwise, that is, if the N3IWF supports the subset of requested NSSAIs allowed by the subscribed S-NSSAI(s), the AMF can proceed to steps 13 and 14 and skip steps 15-19.

[0420] Note 5: The AMF may consider subscribed S-NSSAI(s) before deciding to trigger the UE PCF to avoid triggering the UE PCF to update the UE policy for requested S-NSSAI(s) to which the UE is not subscribed.

[0421] 13. The AMF may send a NAS Registration Accept message in the N2 message sent to the N3IWF. The N2 message may include an Allowed NSSAI for the UE's access type. The allowed NSSAI is a subset of the slices supported by the selected N3IWF.

[0422] 14. The N3IWF can deliver the NAS registration accept message to the UE via the established signaling IPsec SA. If the N3IWF receives the NAS registration accept message before the IPsec SA is established, the N3IWF stores it and can deliver it to the UE only after the signaling IPsec SA is established.

[0423] Steps 15 to 19 may apply when the AMF detects that the N3IWF used by the UE is not compatible with the subset of requested NSSAIs allowed by the subscribed S-NSSAI(s).

[0424] Depending on the AMF implementation, if the AMF detects that the UE continues to register using the same N3IWF several times, the AMF may accept the UE registration instead of rejecting the UE registration and allow the use of S-NSSAI supported by the selected N3IWF.

[0425] The AMF can perform the above operation not only when the UE requests registration through the same N3IWF but also when the UE requests registration multiple times through other N3IWFs. That is, when the UE requests registration multiple times through other N3IWFs, the AMF can accept the UE registration instead of rejecting the UE registration and allow the use of S-NSSAI supported by the selected N3IWF.

[0426] The AMF can operate as follows to find out that the terminal has rejected the registration request several times via the same or another N3IWF.

[0427] The AMF may generally store the UE context in consideration of the UE's re-registration even if the UE is deregistered. Similarly, when the UE requests registration through an N3IWF that does not support slices, the AMF may store the UE context while rejecting the UE registration request. In addition, if the AMF rejects the registration request because the N3IWF does not support the slice requested by the UE, the AMF may store information such as how many rejections have been made and which N3IWF the UE selected.

[0428] If necessary, the AMF can send target N3IWF information to the terminal while giving a registration rejection before approving the terminal's request. For example, the current N3IWF does not support any of the slices requested by the terminal. In this case, the AMF can send target N3IWF information to the terminal so that the terminal can select an N3IWF that supports the default slice to allow the terminal to use the default slice in the subscriber information. When the terminal then makes a registration request through the target N3IWF, the Allowed NSSAI to be used by the terminal can be determined from the slices supported by the target N3IWF.

[0429] For this reason, the AMF can reject the terminal's registration request and store the requested NSSAI information requested by the terminal. Also, if the AMF sends target N3IWF information to the terminal, the AMF can store the sent target N3IWF information in the terminal context. Based on this information, when the terminal sends a registration request again, the AMF can determine that the terminal is making a repeated registration request. In this case, the AMF can decide whether to accept only some of the slices requested by the terminal.

[0430] 15. If the UE registration request includes an indication that the UE supports N3IWF selection based on the slice that the UE wants to use over untrusted non-3GPP access, the AMF can trigger the UE PCF to update the N3IWF selection related policy for the UE included in the ANDSP. The UE PCF is the PCF that creates the UE Policy Association.

[0431] Note 6: It is assumed that the UE informs the PCF whether it supports the extended home N3IWF identifier configuration and slice-specific N3IWF prefix configuration as part of the UE policy update procedure. Details are specified in the 3-step specification.

[0432] Note 6: It can be assumed that the UE informs the PCF whether it supports the extended home N3IWF identifier configuration and slice-specific N3IWF prefix configuration as part of the UE policy update procedure.

[0433] 16. The PCF may update the UE policy. The AMF may start a locally configured timer to detect the completion of the policy update.

[0434] 17. If the timer started in step 16 expires, the AMF may send a UE registration rejection via the N3IWF indicating that the N3IWF selected by the UE is not suitable for the requested slice that the UE is allowed to access. The AMF may optionally include target N3IWF information (FQDN and / or IP address) in the registration rejection message and provide it to the UE.

[0435] NOTE 7: The AMF can determine the target N3 IWFs that support the subset of requested NSSAIs allowed by the subscribed S-NSSAI based on the list of supported TAs and the corresponding list of supported slices for each TA obtained in the N2 interface management procedure.

[0436] 18. If supported by the UE and the UE received the target N3IWF information in step 17, the UE connects to the target N3IWF; otherwise, the UE can perform N3IWF selection again using the updated N3IWF selection information received in step 16. The UE can only use the target N3IWF information included in the registration rejection for N3IWF selection immediately after the rejected registration, and the UE does not store the target N3IWF information for future use.

[0437] When registering with UDM, AMF can provide UDM with the access type set to 'Non-3GPP access' and the RAT type determined as specified.

[0438] NOTE 8: When the UE accesses the SNPN service via the PLMN via 3GPP access, the access type and RAT type can be set to "Untrusted Non-3GPP access".

[0439] III. Third Example

[0440] (1) General

[0441] There are the following problems:

[0442] The AMF may release the UE policy association before sending a Registration Reject. However, if the association is not released, the association may still be maintained even if the UE is not registered in the network.

[0443] In the case of untrusted non-3GPP access, the AMF can inform the PCF that the N3IWF selection information must be updated. On the other hand, in the case of trusted non-3GPP access, the AMF can inform the PCF that the TNGF selection information must be updated. Since the AMF also reports the connection type and RAT type based on the PCRT, it does not appear that a separate notification is necessary. Based on this information, it is up to the PCF to decide whether to update the entire ANDSP or all the WLANSP or N3IWF selection information.

[0444] If the AMF provides target N3IWF / TNAN information in Registration Reject, the UE can use the target N3IWF / TNAN information if the UE supports it. However, if the UE changes the Requested NSSAI, the target N3IWF / TNAN information is no longer valid.

[0445] The following method can be proposed:

[0446] Instead of informing the N3IWF selection update / TNGF selection update, the AMF can inform the PCF that a UE policy update is required for both untrusted non-3GPP access and trusted non-3GPP access.

[0447] -AMF may release UE policy connection before sending Registration Reject.

[0448] If the UE receives target N3IWF / TNAN information via a Registration Reject message, the UE may use the same Requested NSSAI as the network slice included in the Requested NSSAI of the previous Registration Request message.

[0449] (2) Select N3IWF

[0450] The UE may perform a procedure to select an N3IWF.

[0451] When the UE supports connection with not only the ePDG but also the N3IWF, the UE may perform a procedure to select one of the N3IWF or the ePDG, i.e., to select a non-3GPP access node.

[0452] In both of the above cases, the UE can be configured by the HPLMN with the same information, including:

[0453] 1) ePDG Identifier Configuration: This can include the FQDN or IP address of the ePDG in the HPLMN. This can only be used if the UE supports connection with the ePDG and attempts to select an ePDG. It can be ignored in all other cases.

[0454] 2) N3IWF Identifier Configuration: It may contain the FQDN or IP address of the N3IWF in the HPLMN.

[0455] 3) Extended Home N3IWF Identifier Configuration: It may contain one or more tuples of the FQDN / IP address of the N3IWF in the HPLMN and the S-NSSAI supported by this N3IWF.

[0456] 4) Non-3GPP Access Node Selection Information: This includes a PLMN priority list and, for each PLMN, (i) a "Preference" parameter indicating whether an ePDG or N3IWF is preferred in this PLMN, and (ii) an FQDN parameter. It can indicate whether a TA / Location Area ID FQDN or an Operator Identifier FQDN should be used when searching for an ePDG or N3IWF address in this PLMN. The PLMN list should include the HPLMN and may include an "All PLMNs" item that matches all PLMNs to which the UE is connected, except for the HPLMN.

[0457] 5) Slice-specific N3IWF prefix configuration: It can include one or more tuples configured as follows:

[0458] -Supported S-NSSAI Inventory

[0459] - prefixed N3IWF OI or TA FQDN prefix.

[0460] Reference 1: It can be assumed that the extended home N3IWF identifier configuration and slice-specific N3IWF prefix configuration are provided to the UE as part of the ANDSP.

[0461] The ePDG identifier configuration, N3IWF identifier configuration, extended home N3IWF identifier configuration, and slice-specific N3IWF prefix configuration are optional parameters, whereas the non-3GPP access node selection information is mandatory and may include at least the HPLMN and "any PLMN" entries.

[0462] If the ePDG identifier configuration is configured in the UE, when the UE decides to select an ePDG in the HPLMN, the UE can use the ePDG identifier configuration to find the IP address of the HPLMN. The ePDG of the HPLMN can be specified and the FQDN parameter of the HPLMN can be ignored in the non-3GPP access node selection information.

[0463] If an N3IWF identifier configuration or an extended home N3IWF identifier configuration is configured in the UE, when the UE decides to select an N3IWF in the HPLMN, the UE may use the extended home N3IWF identifier configuration if available, otherwise it may use the N3IWF identifier configuration to find the IP address of the N3IWF in the HPLMN and ignore the FQDN parameter of the HPLMN in the non-3GPP access node selection information.

[0464] The PCF of the HPLMN may take into account the S-NSSAI to which the UE subscribes when providing the extended home N3IWF identifier configuration and / or slice-specific N3IWF prefix configuration to the UE.

[0465] If the UE does not support the extended home N3IWF identifier configuration and slice-specific N3IWF prefix configuration, the HPLMN can provide the UE with non-3GPP access node selection information and N3IWF identifier configuration taking into account the UE's subscribed S-NSSAI.

[0466] Reference 2: If the HPLMN deploys various N3IWFs using different TAs that support different S-NSSAIs, the HPLMN can configure the UE with an N3IWF identifier configuration so that the UE can select an N3IWF that supports the UE's subscribed S-NSSAI.

[0467] The UE may be configured by the VPLMN with the following information applicable to V-PLMN:

[0468] Slice-specific N3IWF prefix configuration: Can contain one or more tuples configured as follows:

[0469] -Supported S-NSSAI Inventory

[0470] - prefixed N3IWF OI or TA FQDN prefix.

[0471] To enable the V-PCF to provide the UE with a per-slice N3IWF prefix configuration, the AMF may provide the V-PCF with the NSSAI configured for the serving PLMN during the UE policy connection setup / modification procedure.

[0472] Note 3: In the non-roaming case, the UE PCF can receive the NSSAI already subscribed from the UDR. Therefore, in the non-roaming case, the AMF does not need to provide the configured NSSAI to the PCF.

[0473] Reference 4: PCF (V-PCF in case of roaming) is information on slices supported by different N3IWFs of the serving PLMN and can be assumed to be locally configured.

[0474] During the registration procedure, the AMF can determine whether the N3IWF selected by the UE is suitable for the S-NSSAI(s) requested by the UE taking into account the UE subscriber information.

[0475] If the AMF determines that the N3IWF selected by the UE is not suitable, the AMF may determine that the UE must select another N3IWF. In this case, the AMF may perform the following:

[0476] If the UE supports slice-based N3IWF selection, it may trigger a UE Policy Association Establishment or UE Policy Association Update procedure to provide the UE with updated N3IWF selection information. When the AMF receives a notification from the PCF that the UE policy information update for the UE has been completed, if the UE is not registered via 3GPP access, the AMF may release the UE policy association before proceeding to registration denial.

[0477] The AMF may send a registration rejection message to the UE. If the UE supports it, the AMF may include target N3IWF information (FQDN and / or IP address) in the registration rejection message so that the UE can use the target N3IWF information to select an N3IWF to register with 5GC. If the UE wants to include the same Requested NSSAI as the previous registration request in the new registration request, the UE (if supported) can use the target N3IWF information (FQDN and / or IP address) to select an N3IWF and register with 5GC.

[0478] The target N3IWF information may only apply to the single N3IWF selection performed by the UE immediately after receiving the registration rejection message. When performing registration, if the UE uses the target N3IWF information, the UE may include the same Requested NSSAI as that included in the previous registration request. The UE may send a registration request including the same Requested NSSAI as that included in the previous registration request.

[0479] The previous Registration Request message refers to a registration request that triggered a Registration Reject including target N3IWF information, i.e., the previous Registration Request can trigger a Registration Reject including target N3IWF information.

[0480] If the terminal wishes to change the Requested NSSAI and request registration, a new N3IWF selection process can be performed using the N3IWF selection procedure instead of the target N3IWF information. That is, the target N3IWF information can be used only if the Requested NSSAI is sent in the same way or a subset of the previous Requested NSSAI is sent to the Requested NSSAI.

[0481] The AMF can determine the N3IWF based on the obtained list of supported TAs and the corresponding list of supported slices for each TA.

[0482] (3) Access network selection procedure

[0483] The following steps are performed by a UE when the UE attempts to select and connect to a PLMN via trusted non-3GPP access. The UE can perform these steps before connecting to a trusted non-3GPP access network. This differs from untrusted non-3GPP access, in which the UE first connects to a non-3GPP access network to obtain an IP configuration and then proceeds with PLMN selection and ePDG / N3IWF selection. In the case of trusted non-3GPP access, the UE uses 3GPP-based authentication to connect to non-3GPP access, so it can first select a PLMN and then attempt to connect to non-3GPP access.

[0484] Step 1: The UE can configure a list of available PLMNs for which reliable connectivity is supported. This list can include PLMNs included in PLMN List-2 and PLMN List-3 advertised by all discovered non-3GPP access networks. Supported reliable connectivity types for each PLMN can also be included.

[0485] a. The available PLMN inventory may include:

[0486] -PLMN-a: "S2a connectivity", "5G connectivity"

[0487] -PLMN-b: "5G connectivity"

[0488] -PLMN-c: "S2a connectivity", "5G connectivity"

[0489] -PLMN-d: "S2a connection"

[0490] Step 2: The UE may select a PLMN included in the available PLMN list as follows:

[0491] a. If the UE is connected to a PLMN via 3GPP access and this PLMN is included in the available PLMN list, the UE may select this PLMN. If this PLMN is not included in the available PLMN list but is included in the UE's "Non-3GPP Access Node Selection Information," the UE may select this PLMN to perform a combined ePDG / N3IWF selection procedure.

[0492] b. Otherwise (the UE is not connected to a PLMN via 3GPP access, or the UE is connected to a PLMN via 3GPP access but this PLMN is not in the list of available PLMNs or in the "Non-3GPP access node selection information"), the UE may determine the country in which it is located using an implementation identification means.

[0493] i) If the UE decides to locate in the Home Country:

[0494] The UE may select an HPLMN if it is included in the available PLMN list. Alternatively, if the available PLMN list includes an E-HPLMN, the UE may select an E-HPLMN (Equivalent HPLMN). If the available PLMN list does not include an HPLMN or an E-HPLMN, the UE may abort the procedure and attempt connection via an unreliable non-3GPP access (i.e., perform an N3IWF selection procedure).

[0495] ii) If the UE decides to locate in the Visited State:

[0496] The UE can determine whether PLMN selection is mandatory in the visited country as follows:

[0497] If the UE has IP connectivity (e.g., if the UE is connected via 3GPP access), the UE can send a DNS query and receive a DNS response indicating whether to select a PLMN in the visited state. The DNS response may also include a lifetime indicating how long the DNS response can be cached. The FQDN of the DNS query should be different from the visited state FQDN used for ePDG / N3IWF selection. The DNS response does not include a list of PLMNs that support reliable connectivity in the visited state, but only an indication of whether to select a PLMN in the visited state.

[0498] If the UE does not have IP connectivity (e.g., the UE is not connected via 3GPP access), the UE may use a previously received cached DNS response or a local configuration indicating which visited countries require PLMN selection.

[0499] If the UE determines that PLMN selection is not required in the visited country and the available PLMN list includes an HPLMN or E-HPLMN, the UE may select one of the HPLMN or E-HPLMN. It may be included in the available PLMN list.

[0500] Otherwise, the UE may select a PLMN in the visited state by first considering the PLMNs in the User Controlled PLMN Selector list and then considering the PLMNs in the Operator Controlled PLMN Selector list. The UE may select the highest priority PLMN in the PLMN selector list that is also included in the available PLMN list.

[0501] If the available PLMN list does not include a PLMN that is also included in the PLMN Selector list, the UE may abort the procedure and attempt to connect via an unreliable non-3GPP access.

[0502] c. The UE can select a PLMN-c that supports "S2a connectivity" and "5G connectivity".

[0503] Step 3: The UE can select a reliable connection type ('S2a connection' or '5G connection') to connect to the selected PLMN as follows:

[0504] a. If the available PLMN list indicates that 'S2a connection' and '5G connection' are both supported for the selected PLMN, the UE shall select '5G connection' as this is the preferred reliable access type.

[0505] b. On the other hand, if the available PLMN list indicates that only one type of reliable connection ('S2a connection' or '5G connection') is supported for the selected PLMN, the UE may select this type of reliable connection.

[0506] c. The UE can select "5G connectivity" with PLMN-c. There may be two non-3GPP access networks that support "5G connectivity" to PLMN-c: WLAN access network 2 and WLAN access network 4.

[0507] Step 4: Finally, the UE can select a non-3GPP access network to connect to as follows:

[0508] a. The UE prioritizes available non-3GPP access networks. In the case of WLAN access, the UE can configure a prioritized WLAN access network list using WLANSP rules (if provided) and specified procedures. If the UE receives an extended WLANSP rule that supports the selection of trusted access that supports the network slice it intends to use, the UE can connect to the TNGF that supports the SSID(s) and S-NSSAI required by the UE. If the UE is not provided with a WLANSP rule, the UE can configure a prioritized list of WLAN access networks using an implementation-specific procedure. In the case of other types of non-3GPP access, the UE can configure this prioritized list using access-specific information.

[0509] b. From the prioritized list of non-3GPP access networks, the UE may select the highest priority non-3GPP access network that supports a reliable connection of the selected type to the selected PLMN.

[0510] c. The UE may select WLAN access network 2 or WLAN access network 4, which has the highest priority in the priority list of non-3GPP access networks.

[0511] d. The UE may initiate a specified 5GC registration procedure via the selected non-3GPP access network.

[0512] e.If the AMF detects that the UE is using an incorrect TNGF, the AMF can trigger a UE policy update to reject the UE registration.

[0513] During the registration procedure, the AMF may determine whether the TNGF selected by the UE is suitable for the S-NSSAI(s) requested by the UE in consideration of the UE joining. If the AMF determines that another TNGF must be selected, the AMF may:

[0514] If the UE supports slice-based TNGF selection, it may trigger a UE Policy Association Establishment or UE Policy Association Update procedure to provide the UE with updated TNGF selection information. If the AMF is notified by the PCF that the UE policy information update for the UE has been completed, if the UE is not registered via 3GPP access, and UE policy association is not required, the AMF may release the UE policy association before proceeding to registration denial.

[0515] In order for the V-PCF to provide the UE with slice-specific TNGF selection information in a roaming situation, the AMF may provide the V-PCF with the NSSAI configured for the serving PLMN during the UE policy-related configuration / update procedure.

[0516] The AMF may send a registration rejection message to the UE. If the UE supports it, the AMF may include target TNAN information (SSID, TNGF ID) in the registration rejection message so that the UE can use the target TNAN information to reattempt registration to 5GC. If the UE wants to include the same Requested NSSAI as the previous registration request in the new registration request, the UE may attempt to register to 5GC using the target TNAN information (if supported by the UE).

[0517] The UE may select a TNAN using the target TNAN information. The selected TNAN may be the same as the previous TNAN, or may be different from the previous TNAN.

[0518] The UE may send a registration request message to the selected TNAN. In this case, the registration request message may be sent to the AMF via the TNGF of the selected TNAN. This TNGF may be different from the TNGF involved in the previous registration request message.

[0519] The target TNAN information can only be applied to the single TNAN selection performed by the UE immediately after receiving the registration rejection message. When performing registration, if the UE uses the target TNAN information, the UE can include the same Requested NSSAI as that previously included in the registration request. The UE can send a registration request including the same Requested NSSAI as that previously included in the registration request.

[0520] The previous Registration Request message refers to a registration request that triggered a Registration Reject including target TNAN information, that is, the previous Registration Request can trigger a Registration Reject including target TNAN information.

[0521] If the terminal wishes to change the Requested NSSAI and request registration, a new WLAN selection process according to the WLANSP rules can be performed instead of the target TNAN information. That is, the target TNAN information can be used only if the Requested NSSAI is sent in the same way or if a subset of the previous Requested NSSAI is sent in the Requested NSSAI.

[0522] The AMF can determine the TNGF based on the obtained list of supported TAs and the corresponding list of supported slices for each TA.

[0523] IV. Fourth Example

[0524] (1) General

[0525] A method is needed to prevent registration request loops and AMF rejections when there are errors in policy updates, provided UE policies, etc. The following methods can be proposed for this purpose.

[0526] If the AMF detects that the UE is attempting registration several times without selecting an appropriate N3IWF, the AMF accepts the UE registration and only S-NSSAIs supported by the selected N3IWF may be included in the allowed NSSAI.

[0527] The question arises as to whether the PCF needs to inform the AMF of the completion of policy transmission. The following methods can be proposed to address this issue.

[0528] - According to the updated WID, once the policy transmission is complete, the PCF can notify the AMF.

[0529] In the case of untrusted non-3GPP access, the AMF can inform the PCF that the N3IWF selection information must be updated. On the other hand, in the case of trusted non-3GPP access, the AMF can inform the PCF that the TNGF selection information must be updated. The AMF also reports the RAT type and connection type based on PCRT, so no separate notification is required. Based on this information, it is up to the PCF to decide whether to update the entire ANDSP or all the WLANSP or N3IWF selection information.

[0530] AMF can notify PCF to update UE policy instead of notifying N3IWF / TNGF selection information update

[0531] (2) Registration procedures for untrusted non-3GPP access

[0532] A fourth embodiment will be described below with reference to Figures 8a, 8b and 8c.

[0533] The signal flows in Figures 8a, 8b and 8c do not show all the details of the registration procedure over untrusted non-3GPP access, but mainly show the steps performed between the UE and the N3IWF.

[0534] 1. The UE can connect to an untrusted non-3GPP access network through an appropriate authentication procedure and receive an IP address assignment. For example, a non-3GPP authentication method can be used. EAP includes no authentication (in the case of a free WLAN), a pre-shared key, a user name / password, etc. When the UE decides to connect to a 5GC network, a UE that does not operate in SNPN access mode for the NWu interface can select an N3IWF from the 5G PLMN. When the UE decides to connect to a 5GC network, a UE that operates in SNPN access mode for the NWu interface can select an N3IWF in the SNPN.

[0535] Reference 1: UE selection of N3IWF supporting S-NSSAI required for UE can be activated based on ANDSP configuration.

[0536] 2. The UE can initiate an IKE initial exchange and proceed with IPsec Security Association (SA) setup with the selected N3IWF. All subsequent IKE messages after step 2 can be encrypted and integrity protected using the IKE SA established in this step.

[0537] 3. The UE can initiate the IKE_AUTH exchange by sending an IKE_AUTH Request message. The AUTH payload is not included in the IKE_AUTH Request message. This may indicate that the IKE_AUTH exchange should use EAP signaling (EAP-5G signaling in this case). If the UE supports MOBIKE, it should include a Notify payload in the IKE_AUTH Request, which may indicate that MOBIKE is supported. Also, if the UE is provisioned with an N3IWF root certificate, it must include a CERTREQ payload in the IKE_AUTH Request message to request the N3IWF certificate. For WLAN access, if the UE has an MPS subscription, the UE can include a Notify payload in the IKE_AUTH Request indicating the MPS subscription.

[0538] Note 2: Depending on operator policy, the N3IWF may use the current MPS subscription indication to give priority to this UE.

[0539] 4. The N3IWF can respond with an IKE_AUTH response message including an EAP-Request / 5G-Start packet. The EAP-Request / 5G-Start packet can inform the UE to start an EAP-5G session, i.e., to start sending NAS messages encapsulated in EAP-5G packets. If the N3IWF receives a CERTREQ payload from the UE, the N3IWF must include a CERT payload in the IKE_AUTH response message containing the N3IWF's certificate.

[0540] 5. The UE shall send an IKE_AUTH request including an EAP response / 5G-NAS packet containing an access network parameter (AN parameter) and a registration request message. The AN parameter may include information used by the N3IWF to select an AMF in the 5G core network. For example, this information may include the GUAMI, the selected PLMN ID (or PLMN ID and NID, see clause 5.30 of TS 23.501 [2]), the requested NSSAI, and the establishment cause. The establishment cause may provide the reason for requesting a signaling connection with the 5GC. Whether and how the UE includes the requested NSSAI as part of the AN parameter may depend on the value of the access stratum connection establishment NSSAI inclusion mode parameter. The registration request may include an indication that the UE supports N3IWF selection based on the slice the UE desires to use over untrusted non-3GPP access (i.e., an indication that the UE supports extended home N3IWF identifier configuration and slice-specific N3IWF prefix configuration).

[0541] Note 3: Because the UE includes the corresponding ID in the first IKE_AUTH, the N3IWF does not send an EAP-Identity request.

[0542] 6. The N3IWF can select an AMF based on the received AN parameters and local policies. The N3IWF can transmit the registration request received from the UE to the selected AMF in an N2 message. This message can include N2 parameters including the selected PLMN ID, the optionally selected NID, and the configuration cause.

[0543] Note 4: The selected NID may be present when the UE connects to the SNPN via an untrusted non-3GPP access.

[0544] 7. The selected AMF may decide to request SUCI by sending a NAS Identity Request message to the UE. This NAS message and all subsequent NAS messages may be encapsulated in EAP / 5G-NAS packets and sent to the UE.

[0545] 8. The AMF may decide to invoke the AUSF to authenticate the UE. In this case, the AMF may select the AUSF based on the SUPI or SUCI.

[0546] The AUSF may perform UE authentication. The AUSF may select a UDM and bring authentication data in the UDM. The authentication packet may be encapsulated in a NAS authentication message, and the NAS authentication message may be encapsulated in an EAP / 5G-NAS packet. After successful authentication:

[0547] In step 8h, the AUSF can send the anchor key (SEAF key) to the AMF, which the AMF uses to derive the NAS security key and the security key for the N3IWF (N3IWF key). The UE can also derive the anchor key (SEAF key) and use it to derive the NAS security key and the security key for the N3IWF (N3IWF key). The N3IWF key can be used by the UE and N3IWF to establish an IPsec security association (step 11).

[0548] In step 8h, the AUSF may also include a SUPI if the AMF provided the AUSF with a SUCI in step 8a.

[0549] Reference 5: EAP-AKA' or 5G-AKA can be allowed for UE authentication via non-3GPP access. Figures 8a, 8b, and 8c show only the authentication flow using EAP-AKA'. Authentication methods other than EAP-AKA' or 5G-AKA can be allowed not only for UEs accessing SNPN services via PLMN, but also for UEs accessing SNPN services directly via untrusted non-3GPP access.

[0550] 9a. The AMF can send a NAS security mode command to the UE to activate NAS security. If EAP-AKA' authentication is successfully performed in step 8, the AMF can encapsulate the EAP-Success received from the AUSF in a NAS security mode command message.

[0551] 9b. The N3IWF may convey a NAS security mode command message to the UE within an EAP / 5G-NAS packet.

[0552] 9c. The UE can complete EAP-AKA' authentication (if initiated in step 8), generate a NAS security context and N3IWF key, and send a NAS security mode complete message in an EAP / 5G-NAS packet.

[0553] 9d. The N3IWF can relay the NAS Security Mode Complete message to the AMF.

[0554] 10a. Upon receiving NAS security mode completion, the AMF may send an NGAP initial context setup request message including the N3IWF key.

[0555] 10b. This can trigger the N3IWF to send an EAP-Success to the UE, which completes the EAP-5G session. No further EAP-5G packets are exchanged.

[0556] 11. An IPsec SA can be established between the UE and the N3IWF using the common N3IWF key generated by the UE in step 9c and received by the N3IWF in step 10a. This IPsec SA can be referred to as the "signaling IPsec SA." After the signaling IPsec SA is established, the N3IWF can send an NGAP initial context setup response to inform the AMF that the UE context (including AN security) has been created. The signaling IPsec SA must be configured to operate in tunnel mode, and the N3IWF can assign an "internal" IP address to the UE. If the N3IWF receives an indication that the UE supports MOBIKE (see step 3), the N3IWF can include a notification payload in the IKE_AUTH response message sent in step 11a indicating that MOBIKE must be supported as specified in RFC 4555.

[0557] All subsequent NAS messages exchanged between the UE and the N3IWF must be sent via the signaling IPsec SA and can be transmitted via TCP / IP. The UE can send NAS messages in TCP / IP packets whose source address is the UE's "internal" IP address and whose destination address is the NAS_IP_ADDRESS received in step 11a. The N3IWF can send NAS messages in TCP / IP packets whose source address is the NAS_IP_ADDRESS and whose destination address is the UE's "internal" IP address. The TCP connection used for reliable NAS transmission between the UE and the N3IWF can be initiated by the UE immediately after the signaling IPsec SA is established in step 11a. The UE can send a TCP connection request with the specified TCP port number and NAS_IP_ADDRESS.

[0558] 12. The AMF can determine the subset of requested NSSAIs allowed by the subscribed S-NSSAI. After the AMF detects that the N3IWF used by the UE is not compatible with this subset, it can proceed to steps 15-19. Otherwise, that is, if the N3IWF supports the subset of requested NSSAIs allowed by the subscribed S-NSSAI(s), the AMF can proceed to steps 13 and 14 and skip steps 15-19.

[0559] Note 5: The AMF may consider subscribed S-NSSAI(s) before deciding to trigger the UE PCF to avoid triggering the UE PCF to update the UE policy for requested S-NSSAI(s) to which the UE is not subscribed.

[0560] 13. The AMF may send a NAS Registration Accept message in the N2 message sent to the N3IWF. The N2 message may include an Allowed NSSAI for the UE's access type. The allowed NSSAI is a subset of the slices supported by the selected N3IWF.

[0561] 14. The N3IWF can deliver the NAS registration accept message to the UE via the established signaling IPsec SA. If the N3IWF receives the NAS registration accept message before the IPsec SA is established, the N3IWF stores it and can deliver it to the UE only after the signaling IPsec SA is established.

[0562] Steps 15 to 19 may apply when the AMF detects that the N3IWF used by the UE is not compatible with the subset of requested NSSAIs allowed by the subscribed S-NSSAI(s).

[0563] Depending on the AMF implementation, if the AMF detects that the UE continues to register using the same N3IWF several times, the AMF may accept the UE registration instead of rejecting the UE registration and allow the use of S-NSSAI supported by the selected N3IWF.

[0564] 15. If the UE registration request includes an indication that the UE supports N3IWF selection based on the slice that the UE wants to use over untrusted non-3GPP access, the AMF can trigger the UE PCF to update the policy for the UE. The UE PCF is the PCF that creates the UE Policy Association.

[0565] Whether the PCF updates the entire ANDSP or only the N3IWF selection information can be determined by the PCF taking into account the assigned PSI and operator policy.

[0566] It can be assumed that the UE informs the PCF whether it supports the extended home N3IWF identifier configuration and slice-specific N3IWF prefix configuration as part of the UE policy update procedure.

[0567] 16. The PCF may update the UE policy. When the UE policy update is completed, the PCF may notify the AMF.

[0568] 17. The AMF may send a UE registration rejection to the UE via the N3IWF, indicating that the N3IWF selected by the UE is not suitable for the requested slice that the UE is allowed to access. The AMF may optionally provide the UE with target N3IWF information (FQDN and / or IP address) via the registration rejection message.

[0569] The AMF can determine the target N3IWF that supports the subset of requested NSSAIs allowed by the subscribed S-NSSAI based on the list of supported TAs and the corresponding list of supported slices for each TA obtained in the N2 interface management procedure.

[0570] 18. If supported by the UE and the UE received the target N3IWF information in step 17, the UE connects to the target N3IWF. Otherwise, the UE can perform N3IWF selection again using the updated N3IWF selection information received in step 16. The target N3IWF information included in the registration rejection can only be used for N3IWF selection immediately after the registration rejection. The UE does not store the target N3IWF information for future use. When the UE performs registration, if it uses the target N3IWF information, the UE must include the same Requested NSSAI as the one previously included in the registration request.

[0571] When registering with UDM, AMF can provide UDM with the access type set to 'Non-3GPP access' and the determined RAT type.

[0572] Even when the UE accesses the SNPN service via the PLMN via 3GPP access, the access type and RAT type can be set to 'untrusted non-3GPP access'.

[0573] (3) Registration Procedures for Trusted Non-3GPP Access

[0574] 9a, 9b, 9c, and 9d illustrate registration via trusted non-3GPP access according to an embodiment of the present disclosure.

[0575] A UE can connect to a trusted non-3GPP access network (TNAN) using the EAP-based procedure shown in Figures 9a, 9b, 9c, and 9d, and also register with 5GC through this TNAN. This procedure is very similar to the 5GC registration procedure for untrusted non-3GPP access. The link between the UE and the TNAN is any data link (L2) that supports EAP encapsulation. The interface between the TNAP and the TNGF is an AAA interface, such as PPP, PANA, Ethernet, IEEE 802.3, or IEEE 802.11.

[0576] A UE that does not operate in SNPN access mode for the 0.Yt interface can select a PLMN and TNAN to connect to this PLMN using the Trusted Non-3GPP Access Network Selection procedure. During this procedure, the UE can search for PLMNs for which the TNAN supports trusted connections (e.g., "5G connection").

[0577] A UE operating in SNPN access mode for the Yt interface can use a specified Trusted Non-3GPP access network selection procedure to select an SNPN and a TNAN to connect to this SNPN. During this procedure, the UE can search for an SNPN that supports a trusted connection (e.g., "5G connection") to which the TNAN can be trusted.

[0578] Note 1: In this release, if the trusted non-3GPP access is also a trusted WLAN access, the UE can be configured to select a TNAN (SSID and TNGF) associated with a non-3GPP TA (tracking area) that supports one or more of the S-NSSAIs to which the UE has subscribed (e.g., using WLANSP rules).

[0579] 1. A layer 2 connection can be established between the UE and the TNAP. In the case of PPP, this step can correspond to PPP LCP negotiation. For other types of non-3GPP access (e.g., Ethernet), this step is not necessary.

[0580] 2-3. The EAP procedure can be initiated. The EAP message can be encapsulated in a Layer 2 packet (e.g., an IEEE802.3 / 802.1x packet, an IEEE802.11 / 802.1x packet, a PPP packet, etc.). The NAI provided by the UE that does not operate in SNPN access mode for the Yt interface can indicate that the UE requests "5G connection" to a specific PLMN. (Example: NAI="any_username>@nai.5gc.mnc <mnc>.mcc <mcc>.3gppnetwork.org”). In the case of WLAN access, if the UE has an MPS subscription, the UE must also include an MPS subscription indication in the user name portion of the NAI. The NAI provided by a UE operating in SNPN access mode for the Yt interface can indicate that the UE requests a “5G connection” to a specific SNPN (e.g., NAI="<any_username> @nai.5gc.nid <nid>.mnc <mnc>.mcc <mcc>.3gppnetwork.org”). If the WLANSP rules include information including the TNGF ID to be used for a specific slice and the UE supports this information, the UE can construct the NAI realm taking the TNGF ID into account (e.g., NAI="<any_username> @tngfid<TNGF ID> .nai.5gc.mnc <mnc>.mcc <mcc>.3gppnetwork.org"). This NAI can trigger the TNAP to send an AAA request to the TNGF, which acts as an AAA proxy. EAP packets between the TNAP and the TNGF can be encapsulated in AAA messages. The AAA request can also include a TNAP identifier, which can be treated as user location information.

[0581] Note 2: When the trusted non-3GPP access is a trusted WLAN access, it can be assumed that the TNAP selects a TNGF based on the area served by the UE and the SSID selected by the UE. In distribution, the TNGF supports tracking areas and can be reached via various SSIDs concatenated with a set of slices. Alternatively, the SSID can provide access to one or more TNGFs. (s) can support other tracking areas and other sets of slices.

[0582] Note 3: After receiving an MPS subscription indication from a UE according to operator policy, the TNAN may prioritize this UE.

[0583] The terminal may send EAP signaling to the TNAN. The EAP signaling may include information for the TNGF. The TNAN may select a TNGF based on the information for the TNGF.

[0584] 4-10. The EAP-5G procedure can be performed for untrusted non-3GPP access via modifications such as:

[0585] The registration request may include an indication that the UE supports TNGF selection based on the slice the UE desires to use via trusted non-3GPP access (i.e., an indication that the UE supports extended WLANSP rules).

[0586] After successful authentication, a TNGF key (instead of an N3IWF key) can be generated in the UE and AMF. The TNGF key can be sent from the AMF to the TNGF in step 10a (within the N2 initial context setup request). The TNGF can derive a TNAP key to be provided to the TNAP. The TNAP key can vary depending on the non-3GPP access technology.

[0587] In step 5, the UE shall include the requested NSSAI in the AN parameter only if allowed by the conditions defined for trusted non-3GPP access. The UE shall also include the UE Id in the AN parameter (e.g., 5G-GUTI if available from a previous registration for the same PLMN or SNPN). If a UE in SNPN access mode for the Yt interface performs a registration procedure for UE onboarding, the UE shall include an indication in the AN parameter that the connection request is for onboarding.

[0588] Since the UE has not yet been assigned an IP address in the N2 message sent in step -6b, the TNGF may include a UE Location Information (ULI) containing a "null" IP address (e.g., 0.0.0.0). After the UE has been assigned an IP address, the TNGF may include this address in a subsequent N2 message. This N2 message may also include the selected PLMN ID, the optionally selected NID, and the configuration cause.

[0589] Note 4: The selected NID may exist when the UE is connected to the SNPN via Trusted non-3GPP access.

[0590] -When a UE in SNPN access mode for the Yt interface performs a registration procedure for UE onboarding, the interaction between the AMF and the AUSF (steps 8a and 8c) can be replaced by the 5GC architecture used for UE onboarding.

[0591] In step 10a, after receiving the TNGF key from the AMF, the TNGF must send an EAP-Request / 5G-Notification packet containing "TNGF Contact Info" containing the TNGF's IP address to the UE. In step 10c, after receiving an EAP-Response / 5G-Notification packet from the UE, the TNGF must send a message 10d containing an EAP-Success packet.

[0592] 11. The TNAP key can be used to establish Layer 2 security between the UE and the TNAP. A four-way handshake is performed to establish a security context between the WLAN AP and the UE that is used to protect unicast and multicast traffic over the air.

[0593] 12. The UE may receive IP configuration from the TNAN (eg, with DHCP).

[0594] 13. At this point, the UE has successfully connected to the TNAN and obtained an IP configuration. The UE can establish a security NWt connection with the TNGF as follows:

[0595] The UE can initiate an IKE_INIT exchange using the TNGF's IP address received during EAP-5G signaling in step 10b. The UE can then initiate an IKE_AUTH exchange to provide its identity. The identity provided by the UE in the IKEv2 signaling must be the same as the UE ID included in the AN parameter in step 5. This allows the TNGF to find the TNGF key previously generated for this UE during authentication in step 8. The TNGF key can be used for mutual authentication. NULL encryption can be negotiated between the UE and the TNGF.

[0596] In step 13c, the TNGF can provide the UE with (a) an "inner" IP address, (b) the NAS_IP_ADDRESS and TCP port number, and (c) a DSCP value. After this step, an IPsec SA can be established between the UE and the TNGF. This is called the "signaling IPsec SA" and can operate in tunnel mode. Operating in tunnel mode enables the use of MOBIKE

[40] to re-establish the IPsec SA when the UE's IP address changes during a mobility event. All IP packets exchanged between the UE and the TNGF via the "signaling IPsec SA" must carry this DSCP value. The UE and the TNGF can map the DSCP value to a QoS level supported by the underlying non-3GPP access network (e.g., EDCA access class

[48] ). Mapping DSCP values ​​to QoS levels of non-3GPP access networks is outside the scope of 3GPP.

[0597] Immediately after the "Signaling IPsec SA" is set up, the UE shall set up a TCP connection with the TNGF using the NAS_IP_ADDRESS and TCP port number received in step 13c. The UE shall send the NAS message in a TCP / IP packet whose source address is the UE's "internal" IP address and whose target address is the NAS_IP_ADDRESS. The TNGF shall send the NAS message in a TCP / IP packet whose source address is the NAS_IP_ADDRESS and whose target address is the UE's "internal" IP address.

[0598] This completes the setup of the NWt connection between the UE and the TNGF. All subsequent NAS messages between the UE and the TNGF can be transmitted over this NWt connection (i.e., encapsulated in TCP / IP / ESP).

[0599] 14. After the NWt connection is successfully established, the TNGF can respond to the AMF with an N2 initial context establishment response message.

[0600] 15. The AMF may determine the subset of requested NSSAIs allowed by the subscribed S-NSSAI. After the AMF detects that the TNGF used by the UE is not compatible with this subset, it may proceed to steps 17-21. Otherwise, that is, if the TNGF supports the subset of requested NSSAIs allowed by the subscribed S-NSSAI, the AMF may proceed to step 16 and skip steps 17-21.

[0601] Note 5: The criteria by which the AMF determines that the TNGF used by the UE is incompatible with the subset of requested NSSAIs allowed by the subscribed S-NSSAI(s) are based on local AMF policy. For example, the AMF can determine that the TNGF used by the UE is compatible if there is one commonly supported slice.

[0602] 16. The NAS Registration Accept message is sent by the AMF and can be delivered to the UE via the configured NWt connection. The UE can then use the TNAN to (a) transmit non-smooth offload traffic and (b) establish one or more PDU sessions.

[0603] Steps 17 to 21 may apply when the AMF detects that the TNGF used by the UE is not compatible with the subset of requested NSSAIs allowed by the subscribed S-NSSAI(s).

[0604] If the AMF detects that the UE continues to register using the same TNGF multiple times based on the AMF implementation, the AMF may accept the UE registration instead of rejecting it and allow the use of S-NSSAI supported by the selected TNGF.

[0605] 17. If the UE registration request includes an indication that the UE supports TNGF selection based on the slice the UE wants to use via trusted non-3GPP access, the AMF may trigger the UE PCF to update the policy for the UE. The AMF may request the PCF to be notified when the PCF has completed the UE policy update.

[0606] Whether the PCF updates the entire ANDSP or only the WLANSP can be determined by the PCF taking into account the assigned PSI and operator policy.

[0607] Note 6: It is assumed that the UE will inform the PCF whether it supports extended WLANSP or ANDSP as part of the UE policy update procedure. The details can be specified by CT WG1.

[0608] 18. The PCF can update the UE policy.

[0609] 19. Once the UE policy update is completed, the PCF may inform the AMF of this.

[0610] 20. The AMF can send a UE registration rejection via the TNGF indicating that the selected TNGF is not suitable for the requested slice that the UE is allowed to access. The AMF can provide the UE with target TNAN information (SSID, TNGF ID) in the registration rejection message instructing the UE to construct an NAI based on the TNGF ID.

[0611] Note 7: The AMF can determine the target TNGFs that support the requested subset of NSSAIs allowed by the subscribed S-NSSAI based on the list of supported TAs and the corresponding list of supported slices for each TA obtained through the N2 interface management procedure.

[0612] 21. If supported by the UE and the UE receives the target TNAN information in step 20, the UE can connect to the target TNAN. Otherwise, the UE can perform TNAN selection again using the updated WLAN SP rules received in step 18.

[0613] If the target TNAN information includes a TNGF ID, the UE can construct an NAI based on the TNGF ID. The UE can use the target TNAN information of the registration rejection only for TNAN selection immediately after the registration rejection. The UE does not store the target TNAN information for future use. When the UE performs registration, if it uses the target TNAN information, the UE can include the same Requested NSSAI as the one previously included in the registration request.

[0614] The following drawings are created to explain a specific example of the present specification. The names of specific devices and names of specific signals / messages / fields shown in the drawings are provided for illustrative purposes only, and the technical features of the present specification are not limited to the specific names used in the following drawings.

[0615] FIG. 10 illustrates the UE procedure for the present disclosure.

[0616] 1. The UE sends a first registration request message to a specific non-3GPP Access Network (AN) node via a non-3GPP (Third Generation Partnership Project) access.

[0617] The first registration request message includes a Requested Network Slice Selection Assistance Information (NSSAI).

[0618] 2. Based on the fact that the specific non-3GPP AN node does not support the Requested NSSAI, the UE receives a registration rejection message from an Access and Mobility management Function (AMF).

[0619] The registration rejection message includes target non-3GPP AN node information.

[0620] 3. Send a second registration request message.

[0621] The second registration request message includes the Requested NSSAI based on the step of transmitting the second registration request message using the target non-3GPP AN node information.

[0622] The specific non-3GPP AN node is a Non-3GPP Interworking Function (N3IWF) or a Trusted Non-3GPP Gateway Function (TNGF).

[0623] The second registration request message is the first registration request message received after receiving the registration rejection message.

[0624] Based on the fact that the specific non-3GPP AN node is an N3IWF, the UE selects the N3IWF.

[0625] The first registration request message is sent based on the selection.

[0626] Based on the fact that the specific non-3GPP AN node is an N3IWF, the UE selects a new N3IWF using the target non-3GPP AN node information.

[0627] The second registration request message is sent based on the selection.

[0628] Based on the fact that the specific non-3GPP AN node is a TNGF, the UE selects a first Trusted Non-3GPP Access Network (TNAN) that includes the TNGF.

[0629] The first registration request message is sent based on the selection.

[0630] Based on the fact that the specific non-3GPP AN node is a TNGF, the UE selects a second TNAN using the target non-3GPP AN node information.

[0631] The second registration request message is sent based on the selection.

[0632] The second TNAN is the same as the first TNAN.

[0633] Based on the fact that the specific non-3GPP AN node is a TNGF, the UE sends EAP signaling including information for the TNGF to the first TNAN.

[0634] The following drawings are created to explain a specific example of the present specification. The names of specific devices and names of specific signals / messages / fields shown in the drawings are provided for illustrative purposes only, and the technical features of the present specification are not limited to the specific names used in the following drawings.

[0635] FIG. 11 illustrates the AMF procedure for the present disclosure.

[0636] 1. The AMF receives a first registration request message for a UE (User Equipment) via a non-3GPP (non-Third Generation Partnership Project) access from a specific non-3GPP AN (Access Network) node.

[0637] The first registration request message includes a Requested Network Slice Selection Assistance Information (NSSAI).

[0638] 2. Based on the fact that the specific non-3GPP AN node does not support the Requested NSSAI, the AMF sends a registration rejection message to the UE.

[0639] The registration rejection message includes target non-3GPP AN node information.

[0640] 3. The AMF receives a second registration request message.

[0641] Based on the UE sending the second registration request message using the target non-3GPP AN node information, the second registration request message includes the Requested NSSAI.

[0642] The specific non-3GPP AN node is a Non-3GPP Interworking Function (N3IWF) or a Trusted Non-3GPP Gateway Function (TNGF).

[0643] The second registration request message is the first registration request message sent after the registration rejection message is sent.

[0644] Based on the fact that the specific non-3GPP AN node is an N3IWF, the N3IWF is determined by the selection of the UE.

[0645] Based on the fact that the specific non-3GPP AN node is an N3IWF, the UE selects a new N3IWF using the target non-3GPP AN node information.

[0646] The second registration request message is received from the new N3IWF.

[0647] Based on the fact that the specific non-3GPP AN node is a TNGF, a first Trusted Non-3GPP Access Network (TNAN) including the TNGF is determined by the selection of the UE.

[0648] Based on the fact that the specific non-3GPP AN node is a TNGF, the UE selects a second TNAN using the target non-3GPP AN node information.

[0649] The second registration request message is sent from a new TNGF of the second TNAN.

[0650] The second TNAN is the same as the first TNAN.

[0651] Based on the fact that the specific non-3GPP AN node does not support the Requested NSSAI, the AMF determines to use a non-3GPP AN node different from the specific non-3GPP AN node for the UE.

[0652] The registration reject message is based on the determination.

[0653] Hereinafter, a device for performing communication according to some embodiments of the present specification will be described.

[0654] For example, the NAS layer of a UE includes a processor, a transceiver, and a memory.

[0655] For example, a processor may be configured to be operatively coupled with a memory and a processor.

[0656] The operations performed by the processor include: sending a first registration request message to a specific non-3GPP AN (Access Network) node via a non-3GPP access; the first registration request message includes a Requested NSSAI, and receiving a registration rejection message from an AMF based on the specific non-3GPP AN node not supporting the Requested NSSAI; and the registration rejection message includes target non-3GPP AN node information, and sending a second registration request message including the Requested NSSAI using the target non-3GPP AN node information.

[0657] The following describes a processor of a target V-SMF for providing communication according to some embodiments of the present disclosure.

[0658] The operations performed by the processor include: sending a first registration request message to a specific non-3GPP AN (Access Network) node via a non-3GPP access; receiving a registration rejection message from an AMF based on the first registration request message including a Requested NSSAI and the specific non-3GPP AN node not supporting the Requested NSSAI, and the registration rejection message including target non-3GPP AN node information, and sending a second registration request message, where the second registration request message includes the Requested NSSAI based on the step of sending the second registration request message using the target non-3GPP AN node information being performed.

[0659] Hereinafter, a non-volatile computer-readable medium having one or more instructions stored thereon for providing mobile communications according to some embodiments of the present disclosure will be described.

[0660] According to some embodiments of the present disclosure, technical features of the present disclosure may be embodied directly in hardware, in software executed by a processor, or in a combination of the two. For example, the methods performed by a wireless device in wireless communication may be embodied in hardware, software, firmware, or any combination thereof. For example, software may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or other storage medium.

[0661] An example of a storage medium may be coupled to the processor such that the processor can read information from the storage medium. Alternatively, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. In another example, the processor and the storage medium may reside as discrete components.

[0662] Computer readable media includes any type of non-volatile computer readable storage media.

[0663] For example, non-volatile computer readable media include random access memory (RAM), such as synchronized dynamic random access memory (SDRAM), read-only memory (ROM), non-volatile random access memory (NVRAM), read-only memory (EEPROM), flash memory, magnetic or optical data storage media or other media that can be used to store instructions or data structures, and combinations of the above.

[0664] Additionally, the methods described herein may be embodied at least in part by a computer-readable communication medium that carries code in the form of instructions or data structures and that can be accessed, read, and / or executed by a computer.

[0665] According to some embodiments of the present disclosure, a non-transitory computer-readable medium has one or more instructions stored thereon, the one or more instructions being executable by a processor of a base station.

[0666] The stored one or more instructions include a step of sending a first registration request message to a specific non-3GPP AN (Access Network) node via a non-3GPP access; a step of receiving a registration rejection message from an AMF based on the first registration request message including a Requested NSSAI and the specific non-3GPP AN node not supporting the Requested NSSAI; and a step of sending a second registration request message, the registration rejection message including target non-3GPP AN node information, based on which the step of sending the second registration request message using the target non-3GPP AN node information is performed, the second registration request message including the Requested NSSAI.

[0667] The specification has a variety of effects.

[0668] For example, it is possible to solve the problem of a terminal's registration request being repeatedly rejected when the terminal attempts to register.

[0669] The effects that can be obtained through a specific example of the present specification are not limited to the effects listed above. For example, there may be various technical effects that a person having ordinary skill in the related art can understand or derive from the present specification. Therefore, the specific effects of the present specification are not limited to those explicitly described in the present specification, but may include various effects that can be understood or derive from the technical features of the present specification.

[0670] The claims described herein may be combined in various ways. For example, the technical features of the method claims herein may be combined and embodied in an apparatus, and the technical features of the apparatus claims herein may be combined and embodied in a method. Furthermore, the technical features of the method claims herein and the technical features of the apparatus claims herein may be combined and embodied in an apparatus, and the technical features of the method claims herein and the technical features of the apparatus claims herein may be combined and embodied in a method. Other implementations are within the scope of the following claims:< / mcc> < / mnc> < / mcc> < / mnc> < / nid> < / mcc> < / mnc>

Claims

1. A method for a UE (User Equipment) to perform communication, comprising: sending a first registration request message to a specific non-3GPP Access Network (AN) node via a non-3GPP (Third Generation Partnership Project) access; The first registration request message includes a Requested Network Slice Selection Assistance Information (NSSAI), receiving a registration reject message from an Access and Mobility management Function (AMF) based on the specific non-3GPP AN node not supporting the Requested NSSAI; the registration rejection message includes target non-3GPP AN node information; sending a second registration request message; The method, wherein the step of transmitting the second registration request message using the target non-3GPP AN node information is performed, and the second registration request message includes the Requested NSSAI.

2. The method of claim 1, wherein the specific non-3GPP AN node is a Non-3GPP Interworking Function (N3IWF) or a Trusted Non-3GPP Gateway Function (TNGF).

3. The method of claim 1 or 2, wherein the second registration request message is the first registration request message received after receiving the registration rejection message.

4. selecting the N3IWF based on the fact that the specific non-3GPP AN node is an N3IWF; The method of claim 1 , wherein the first registration request message is sent based on the selection.

5. selecting a new N3IWF using the target non-3GPP AN node information based on the specific non-3GPP AN node being an N3IWF; The method of claim 1 , wherein the second registration request message is sent based on the selection.

6. The method further includes selecting a first Trusted Non-3GPP Access Network (TNAN) including the TNGF based on the fact that the specific non-3GPP AN node is a TNGF; The method of claim 1 , wherein the first registration request message is sent based on the selection.

7. and selecting a second TNAN using the target non-3GPP AN node information based on the specific non-3GPP AN node being a TNGF; The method of claim 1 , wherein the second registration request message is sent based on the selection.

8. The method of claim 7 , wherein the second TNAN is the same as the first TNAN.

9. The method according to any one of claims 1 to 3, further comprising the step of: sending EAP signaling including information for the TNGF to a first TNAN based on the specific non-3GPP AN node being a TNGF.

10. A method for an Access and Mobility Management Function (AMF) to perform communication, comprising: receiving a first registration request message of a User Equipment (UE) via a non-Third Generation Partnership Project (non-3GPP) access from a specific non-3GPP Access Network (AN) node; The first registration request message includes a Requested Network Slice Selection Assistance Information (NSSAI), sending a registration reject message to the UE based on the specific non-3GPP AN node not supporting the Requested NSSAI; the registration rejection message includes target non-3GPP AN node information; receiving a second registration request message; The method includes the Requested NSSAI based on the UE sending the second Registration Request message using the target non-3GPP AN node information.

11. The method of claim 10, wherein the specific non-3GPP AN node is a Non-3GPP Interworking Function (N3IWF) or a Trusted Non-3GPP Gateway Function (TNGF).

12. The method according to claim 10 or 11, wherein the second registration request message is the first registration request message sent after the registration rejection message is sent.

13. The method according to any one of claims 10 to 12, wherein the N3IWF is determined by the selection of the UE, based on the specific non-3GPP AN node being an N3IWF.

14. Based on the fact that the specific non-3GPP AN node is an N3IWF, the UE selects a new N3IWF using the target non-3GPP AN node information; The method of any one of claims 10 to 12, wherein the second registration request message is received from the new N3IWF.

15. The method according to claim 10 to 12, wherein, based on the specific non-3GPP AN node being a TNGF, a first TNAN (Trusted Non-3GPP Access Network) including the TNGF is determined by the selection of the UE.

16. Based on the specific non-3GPP AN node being a TNGF, the UE selects a second TNAN using the target non-3GPP AN node information; 13. The method of claim 10, wherein the second registration request message is sent from a new TNGF of the second TNAN.

17. 17. The method of claim 16, wherein the second TNAN is the same as the first TNAN.

18. The method further includes determining, for the UE, to use a non-3GPP AN node other than the specific non-3GPP AN node based on the specific non-3GPP AN node not supporting the Requested NSSAI; The method of any one of claims 10 to 17, wherein the registration reject message is based on the determination.

19. A non-access stratum (NAS) layer of a user equipment (UE) that performs communication, a transceiver, and a processor, A V-PCF in which the processor-executed operations are the method of any one of claims 1 to 8.

20. An AMF (Access and Mobility management Function) that performs communication, a transceiver, and a processor, The H-PCF, wherein the processor-executed operations are the method of any one of claims 9 to 17.

21. An apparatus in mobile communications, comprising: at least one processor; and at least one memory that stores instructions and is operably electrically coupled to the at least one processor; The apparatus, wherein the actions performed upon the instructions being executed by the at least one processor are the method of any one of claims 1 to 8.

22. A non-volatile computer-readable storage medium that stores instructions, A non-volatile computer-readable storage medium, the instructions, when executed by one or more processors, causing the one or more processors to perform the method of any one of claims 1 to 8.

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