Replacing network slices in wireless communication network

Abstract

A method for a first network function ("NF") to determine a network slice replacement is also provided. The method includes receiving, from a second NF, a request for a notification of when a network slice is to be replaced; determining that the network slice is to be replaced and determining an alternative network slice of the network slice to be replaced; and sending a notification message to the second NF, wherein the notification message comprises a notification that the network slice is to be replaced.

Description

Technical Field

[0001] The subject matter disclosed herein generally relates to the field of replacing network slices in a wireless communication network. This document defines a first network function "NF" for wireless communication, a method for the first NF to determine the replacement of a network slice, a second NF for wireless communication, and a method for the second NF to determine the replacement of a network slice. Background Art

[0002] In wireless communication networks, the fifth generation (5G) network system (also abbreviated as 5GS) features network slicing. Network slicing enables network operators to divide ("slice") network resources into finer-grained logical networks, known as network slices. Such network slices can provide customized network connectivity (or network features) to customers or application service providers.

[0003] A network slice is a logical network that includes: a set of network functions and the corresponding resources (such as computing, storage, and network) necessary to provide certain network functions and network characteristics. A network slice may include a core network (5G core network 5GC) control plane and user plane network functions (NFs) and an access network (such as a 5G radio access network or a fixed access network).

[0004] A user equipment (UE) may be configured with network slice related information, which is referred to as network slice selection assistance information (NSSAI). NSSAI may consist of a single or multiple S-NSSAIs (single network slice selection assistance information). The UE requests registration to a network slice by sending a NAS registration request message to the 5GC (e.g., AMF), which includes a requested NSSAI, which contains a list of one or more S-NSSAIs that the UE wants to register with. The 5GC (e.g., AMF) may send one or more of the following elements related to the UE's network slice configuration to the UE in a registration accept message or in a UE configuration update command message: allowed NSSAI, configured NSSAI, rejected NSSAI, or pending NSSAI. NSSAI is a list of one or more S-NSSAIs. Summary of the invention

[0005] If an existing network slice or network slice instance cannot serve a particular PDU session, or if an existing network slice instance cannot meet the performance requirements of the application using it, the network operator may want to replace this network slice with an alternative network slice. Such a replacement may be temporary. The network slice to be replaced can be identified by the old / previous / first S-NSSAI (also known as S-NSSAI#1). The alternative network slice can be identified by an alternative S-NSSAI (also known as S-NSSAI#2). In a specific scenario, when the UE roams in a visited PLMN (e.g., V-PLMN), the UE can use a home-routed PDU session, where the PDU session is anchored in the home PLMN (e.g., H-PLMN) and the PDU session is established through one S-NSSAI in the V-PLMN and another S-NSSAI in the H-PLMN. The H-PLMN should be able to replace the S-NSSAI used in the H-PLMN. Regardless of roaming, the AMF needs to know that the first network slice needs to be replaced with an alternative network slice.

[0006] The present invention discloses a process for replacing a network slice in a wireless communication network. The process can be implemented by a first network function "NF" for wireless communication, a method for the first NF to determine the replacement of a network slice, a second NF for wireless communication, and a method for the second NF to determine the replacement of a network slice.

[0007] A first network function "NF" for wireless communication is provided, comprising: a processor; and a memory coupled to the processor, the processor being configured to cause the device to determine the replacement of a network slice by: receiving a request for notification when a network slice is to be replaced from a second NF; determining that the network slice is to be replaced and determining an alternative network slice to replace the network slice; and sending a notification message to the second NF, the notification message including the notification that the network slice is to be replaced. The first network function may include a network slice selection function (NSSF). The second NF may be an access and mobility management function (AMF).

[0008] A method for a first network function "NF" to determine a replacement of a network slice is also provided. The method includes: receiving a request for notification when a network slice is to be replaced from a second NF; determining that a network slice is to be replaced and determining an alternative network slice to replace the network slice; and sending a notification message to the second NF, the notification message including a notification that the network slice is to be replaced.

[0009] A second network function "NF" for wireless communication is also provided, comprising: a processor; and a memory coupled to the processor. The processor is configured to cause the device to determine the replacement of a network slice by: sending a request to a first NF for a notification when the network slice is to be replaced; and receiving a notification message from the first NF, the notification message including a notification that the network slice is to be replaced.

[0010] A method for a second network function "NF" to determine the replacement of a network slice is also provided, the method comprising: sending a request to a first NF for a notification of when the network slice is to be replaced; and receiving a notification message from the first NF, the notification message including the notification that the network slice is to be replaced.

[0011] The methods and apparatus defined herein provide a mechanism by which a second network function (such as an AMF) can be notified of a change in a network slice. Such a mechanism improves the operation of a wireless communication network by facilitating a change to an alternative network slice when a network slice in a first set of network slices needs to be replaced. The mechanism tends to ensure that a PDU session established on a network slice is transferred to an alternative network slice and that service continuity can be ensured and may include maintaining quality of service. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to describe the manner in which the advantages and features of the present disclosure can be obtained, the description of the present disclosure is presented by reference to certain devices and methods shown in the accompanying drawings. Each of these drawings depicts only certain aspects of the present disclosure and therefore should not be considered to limit its scope. These drawings may have been simplified for clarity and are not necessarily drawn to scale.

[0013] Methods and apparatus for replacing a network slice in a wireless communication network will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0014] Figure 1 Embodiments of a wireless communication system for replacing a network slice in a wireless communication network are described;

[0015] Figure 2 Depicted is a user equipment device that may be used to implement the methods described herein;

[0016] Figure 3 depicts further details of a network node that may be used to implement the methods described herein;

[0017] Figure 4 An example 5GS architecture for a UE associated with two network slices is shown;

[0018] Figure 5An architecture that can be applied to the solution described herein is shown, where a UE is associated with two network slices;

[0019] Figure 6 shows the signaling flow for the procedure of triggering S-NSSAI replacement by NSSF;

[0020] Figure 7 A method for a first network function "NF" to determine a replacement of a network slice is shown;

[0021] Figure 8 A method for a second network function "NF" to determine a replacement for a network slice is shown. DETAILED DESCRIPTION

[0022] As will be understood by those skilled in the art, aspects of the present disclosure may be embodied as systems, devices, methods or program products. Therefore, the arrangements described herein may be implemented in full hardware form, full software form (including firmware, resident software, microcode, etc.) or in the form of a combination of software and hardware aspects.

[0023] For example, the disclosed methods and apparatus may be implemented as a hardware circuit including custom very large scale integration ("VLSI") circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. The disclosed methods and apparatus may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices, etc. As another example, the disclosed methods and apparatus may include one or more physical or logical executable code blocks, which may be organized as objects, procedures, or functions, for example.

[0024] In addition, the method and apparatus may take the form of a program product embodied in one or more computer-readable storage devices storing machine-readable code, computer-readable code, and / or program code (hereinafter referred to as code). The storage device may be tangible, non-transient, and / or non-transmitting. The storage device may not embody a signal. In some arrangements, the storage device only uses a signal to access the code.

[0025] Any combination of one or more computer readable media may be utilized. The computer readable medium may be a computer readable storage medium. The computer readable storage medium may be a storage device storing code. The storage device may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micromechanical or semiconductor system, device or apparatus, or any suitable combination of the foregoing.

[0026] More specific examples of storage devices (a non-exhaustive list) would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory ("RAM"), a read-only memory ("ROM"), an erasable programmable read-only memory ("EPROM" or flash memory), a portable compact disk read-only memory ("CD-ROM"), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer-readable storage medium may be any tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device.

[0027] References to examples or similar language of a particular method or device throughout this specification mean that the specific features, structures, or characteristics associated with the example are included in at least one implementation of the methods and devices described herein. Therefore, unless otherwise expressly stated, references to features or similar language of examples of a particular method or device may (but not necessarily) all refer to the same example, but rather represent "one or more but not all examples". Unless otherwise expressly stated, the terms "include", "comprise", "have" and their variations mean "including but not limited to". Unless otherwise expressly stated, the list of enumerated items does not mean that any or all items are mutually exclusive. Unless otherwise expressly stated, the terms "one", "an" and "the" also refer to "one or more".

[0028] As used herein, a list with the conjunction "and / or" includes any single item in the list or a combination of items in the list. For example, a list of A, B, and / or C includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C, or a combination of A, B, and C. As used herein, a list using the term "one or more" includes any single item in the list or a combination of items in the list. For example, one or more of A, B, and C includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C, or a combination of A, B, and C. As used herein, a list using the term "one of" includes one and only one of any single item in the list. For example, "one of A, B, and C" includes only A, only B, or only C, and does not include a combination of A, B, and C. As used herein, "a member selected from the group consisting of A, B, and C" includes one and only one of A, B, or C, and does not include a combination of A, B, and C. As used herein, “a member selected from the group consisting of A, B and C and combinations thereof” includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C, or a combination of A, B and C.

[0029] In addition, the features, structures or characteristics described herein may be combined in any suitable manner. In the following description, many specific details are provided, such as examples of programming, software modules, user selections, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc., to provide a thorough understanding of the present disclosure. However, those skilled in the relevant art will recognize that the disclosed methods and apparatus may be practiced without one or more of the specific details, or may be practiced using other methods, components, materials, etc. In other cases, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the present disclosure.

[0030] Aspects of the disclosed methods and apparatus are described below with reference to schematic flow charts and / or schematic block diagrams of methods, apparatuses, systems, and program products. It will be understood that each block in the schematic flow charts and / or schematic block diagrams and the combination of blocks in the schematic flow charts and / or schematic block diagrams can be implemented by code. The code can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device to produce a machine, so that instructions executed by the processor of the computer or other programmable data processing device create components for implementing the functions / actions specified in the schematic flow charts and / or schematic block diagrams.

[0031] The code may also be stored in a storage device that can direct a computer, other programmable data processing apparatus, or other device to operate in a specific manner, so that the instructions stored in the storage device produce a product including instructions for implementing the functions / actions specified in the schematic flowchart and / or schematic block diagram.

[0032] The code may also be loaded onto a computer, other programmable data processing apparatus, or other device so that a series of operating steps are executed on the computer, other programmable apparatus, or other device to produce a computer-implemented process, so that the code executed on the computer or other programmable apparatus provides a process for implementing the functions / actions specified in the schematic flowchart and / or schematic block diagram.

[0033] The flowchart and / or schematic block diagram in the figure illustrate the possible implementation architecture, function and operation of the device, system, method and program product. In this regard, each block in the flowchart and / or schematic block diagram can represent a module, segment or part of the code, which includes one or more executable instructions for implementing the code of (multiple) specified logical functions.

[0034] It should also be noted that in some alternative implementations, the functions indicated in the blocks may not occur in the order indicated in the figure. For example, two consecutively displayed blocks may actually be executed substantially concurrently, or the blocks may sometimes be executed in reverse order, depending on the functions involved. Other steps and methods that are equivalent in function, logic or effect to one or more blocks or portions thereof in the illustrated figure may be envisioned.

[0035] The description of the elements in each figure can refer to the elements in the previous figure. In all figures, similar numbers represent similar elements.

[0036] Figure 1 An embodiment of a wireless communication system 100 for replacing network slices in a wireless communication network is depicted. In one embodiment, the wireless communication system 100 includes a remote unit 102 and a network unit 104. Although a specific number of remote units 102 and network units 104 may be used in a variety of communication environments, the wireless communication system 100 may be used to replace network slices in a wireless communication network. Figure 1 Although not depicted in FIG. 1 , those skilled in the art will recognize that any number of remote units 102 and network units 104 may be included in the wireless communication system 100 .

[0037] In one embodiment, the remote unit 102 may include a computing device such as a desktop computer, a laptop, a personal digital assistant (“PDA”), a tablet, a smartphone, a smart TV (e.g., a TV connected to the Internet), a set-top box, a game console, a security system (including a security camera), a vehicle computer, a network device (e.g., a router, a switch, a modem), an aircraft, a drone, etc. In some embodiments, the remote unit 102 includes a wearable device such as a smart watch, a fitness band, an optical head-mounted display, etc. In addition, the remote unit 102 may be referred to as a subscriber unit, a mobile device, a mobile station, a user, a terminal, a mobile terminal, a fixed terminal, a subscriber station, a UE, a user terminal, a device, or other terms used in the art. The remote unit 102 may communicate directly with one or more network units 104 via UL communication signals. In some embodiments, the remote unit 102 may communicate directly with other remote units 102 via sidelink communications.

[0038] The network elements 104 may be distributed over a geographical area. In some embodiments, the network elements 104 may also be referred to as access points, access terminals, base stations, base stations, Node-Bs, eNBs, gNBs, home Node-Bs, relay nodes, devices, core networks, air servers, radio access nodes, APs, NRs, network entities, access and mobility management functions (“AMFs”), unified data management functions (“UDMs”), unified data repositories (“UDRs”), UDM / UDRs, policy control functions (“PCFs”), radio access networks (“RANs”), network slice selection functions (“NSSFs”), operations, maintenance, and management (“OAMs”) , session management function ("SMF"), user plane function ("UPF"), application function, authentication server function ("AUSF"), security anchor function ("SEAF"), trusted non-3GPP gateway function ("TNGF"), application function, service enabler architecture layer ("SEAL") function, vertical application enabler server, edge enabler server, edge configuration server, mobile edge computing platform function, mobile edge computing application, application data analysis enabler server, SEAL data delivery server, middleware entity, network slice capability management server, or any other term used in the art. The network element 104 is typically part of a radio access network that includes one or more controllers that are communicatively coupled to one or more corresponding network elements 104. The radio access network is typically communicatively coupled to one or more core networks that may be coupled to other networks, such as the Internet and the public switched telephone network. These and other elements of the radio access and core networks are not shown, but are generally well known to those of ordinary skill in the art.

[0039] In one implementation, the wireless communication system 100 complies with the New Radio (NR) protocol standardized in 3GPP, wherein the network unit 104 transmits on the downlink (DL) using an orthogonal frequency division multiplexing ("OFDM") modulation scheme, and the remote unit 102 transmits on the uplink (UL) using a single carrier frequency division multiple access ("SC-FDMA") scheme or an OFDM scheme. More generally, however, the wireless communication system 100 may implement some other open or proprietary communication protocol, such as WiMAX, IEEE 802.11 variants, GSM, GPRS, UMTS, LTE variants, CDMA2000, ZigBee, Sigfoxx, and other protocols. The present disclosure is not intended to be limited to any particular wireless communication system architecture or protocol implementation.

[0040] The network unit 104 may serve multiple remote units 102 within a service area (eg, a cell or cell sector) via wireless communication links. The network unit 104 sends DL communication signals to serve the remote units 102 in the time, frequency, and / or spatial domains.

[0041] Figure 2 A user equipment device 200 that can be used to implement the methods described herein is depicted. The user equipment device 200 is used to implement one or more of the solutions described herein. The user equipment device 200 conforms to one or more of the user equipment devices described in the embodiments of this document. Specifically, the user equipment device 200 may include a remote unit 102, or may be implemented as a UE 410 or UE 610 described herein. The user equipment device 200 includes a processor 205, a memory 210, an input device 215, an output device 220, and a transceiver 225.

[0042] The input device 215 and the output device 220 may be combined into a single device, such as a touch screen. In some implementations, the user equipment apparatus 200 does not include any input device 215 and / or output device 220. The user equipment apparatus 200 may include one or more of the following: a processor 205, a memory 210, and a transceiver 225, and may not include an input device 215 and / or an output device 220.

[0043] As shown, the transceiver 225 includes at least one transmitter 230 and at least one receiver 235. The transceiver 225 can communicate with one or more cells (or wireless coverage areas) supported by one or more base stations. The transceiver 225 can be operable on an unlicensed spectrum. In addition, the transceiver 225 can include multiple UE panels supporting one or more beams. In addition, the transceiver 225 can support at least one network interface 240 and / or application interface 245. (Multiple) application interface 245 can support one or more APIs. (Multiple) network interface 240 can support 3GPP reference points, such as Uu, N1, PC5, etc. As understood by a person of ordinary skill in the art, other network interfaces 240 can be supported.

[0044] The processor 205 may include any known controller capable of executing computer-readable instructions and / or capable of performing logical operations. For example, the processor 205 may be a microcontroller, a microprocessor, a central processing unit (“CPU”), a graphics processing unit (“GPU”), an auxiliary processing unit, a field programmable gate array (“FPGA”), or a similar programmable controller. The processor 205 may execute instructions stored in the memory 210 to perform the methods and routines described herein. The processor 205 is communicatively coupled to the memory 210, the input device 215, the output device 220, and the transceiver 225.

[0045] Processor 205 may control user equipment device 200 to implement the user equipment device behaviors described herein. Processor 205 may include an application processor (also referred to as a "main processor") that manages application domain and operating system ("OS") functions and a baseband processor (also referred to as a "baseband radio processor") that manages radio functions.

[0046] Memory 210 may be a computer-readable storage medium. Memory 210 may include volatile computer storage media. For example, memory 210 may include RAM, including dynamic RAM ("DRAM"), synchronous dynamic RAM ("SDRAM"), and / or static RAM ("SRAM"). Memory 210 may include non-volatile computer storage media. For example, memory 210 may include a hard drive, flash memory, or any other suitable non-volatile computer storage device. Memory 210 may include volatile and non-volatile computer storage media.

[0047] The memory 210 may store data related to implementing the traffic class field as described herein. The memory 210 may also store program code and related data, such as an operating system or other controller algorithms operating on the device 200.

[0048] Input device 215 may include any known computer input device, including a touch panel, buttons, keyboard, stylus, microphone, etc. Input device 215 may be integrated with output device 220, for example as a touch screen or similar touch-sensitive display. Input device 215 may include a touch screen so that text can be entered using a virtual keyboard displayed on the touch screen and / or by handwriting on the touch screen. Input device 215 may include two or more different devices, such as a keyboard and a touch panel.

[0049] The output device 220 may be designed to output visual, auditory, and / or tactile signals. The output device 220 may include an electronically controllable display or display device capable of outputting visual data to a user. For example, the output device 220 may include, but is not limited to, a liquid crystal display ("LCD"), a light emitting diode ("LED") display, an organic LED ("OLED") display, a projector, or a similar display device capable of outputting images, text, and the like to a user. As another non-limiting example, the output device 220 may include a wearable display that is separate from but communicatively coupled to the rest of the user device apparatus 200, such as a smart watch, smart glasses, a head-up display, and the like. In addition, the output device 220 may be a component of a smartphone, a personal digital assistant, a television, a tablet computer, a notebook computer, a personal computer, a vehicle dashboard, and the like.

[0050] Output device 220 may include one or more speakers for producing sound. For example, output device 220 may produce an audible alarm or notification (e.g., a buzzer or beep). Output device 220 may include one or more tactile devices for producing vibration, motion, or other tactile feedback. All or part of output device 220 may be integrated with input device 215. For example, input device 215 and output device 220 may form a touch screen or similar touch-sensitive display. Output device 220 may be located near input device 215.

[0051] The transceiver 225 communicates with one or more network functions of the mobile communication network via one or more access networks. The transceiver 225 operates under the control of the processor 205 to send messages, data and other signals, and also receive messages, data and other signals. For example, the processor 205 can selectively activate the transceiver 225 (or part thereof) at a specific time to send and receive messages.

[0052] The transceiver 225 includes at least one transmitter 230 and at least one receiver 235. One or more transmitters 230 can be used to provide uplink communication signals to the base unit of the wireless communication network. Similarly, one or more receivers 235 can be used to receive downlink communication signals from the base unit. Although only one transmitter 230 and one receiver 235 are shown, the user equipment device 200 can have any appropriate number of transmitters 230 and receivers 235. In addition, (multiple) transmitters 230 and (multiple) receivers 235 can be any appropriate type of transmitter and receiver. The transceiver 225 may include a first transmitter / receiver pair used to communicate with a mobile communication network through a licensed radio spectrum and a second transmitter / receiver pair used to communicate with a mobile communication network through an unlicensed radio spectrum.

[0053] A first transmitter / receiver pair that can be used to communicate with a mobile communication network via a licensed radio spectrum and a second transmitter / receiver pair that can be used to communicate with a mobile communication network via an unlicensed radio spectrum can be combined into a single transceiver unit, such as a single chip that performs functions for both licensed and unlicensed radio spectrum. The first transmitter / receiver pair and the second transmitter / receiver pair can share one or more hardware components. For example, some of the transceivers 225, transmitter 230, and receiver 235 can be implemented as physically separate components that access shared hardware resources and / or software resources, such as, for example, a network interface 240.

[0054] One or more transmitters 230 and / or one or more receivers 235 may be implemented and / or integrated into a single hardware component, such as a multi-transceiver chip, a system on a chip, an application specific integrated circuit ("ASIC"), or other type of hardware component. One or more transmitters 230 and / or one or more receivers 235 may be implemented and / or integrated into a multi-chip module. Other components (such as a network interface 240 or other hardware components / circuits) may be integrated into a single chip with any number of transmitters 230 and / or receivers 235. Transmitters 230 and receivers 235 may be logically configured as transceivers 225 using one or more common control signals, or configured as modular transmitters 230 and receivers 235 implemented in the same hardware chip or multi-chip module.

[0055] Figure 3 Depicted are further details of a network node 300 that can be used to implement the methods described herein. The network node 300 can be an implementation of an entity in a wireless communication network, for example, in one or more wireless communication networks described herein. The network node 300 can include a network element 104, or can be implemented as one of the network functions described herein. Specifically, the network node 300 can be an implementation of an AMF 520, a V-NSSF 532, a H-NSSF 534, an AMF 620, a V-NSSF 632, a H-NSSF 634, or a V-SMF 652 as described herein. The network node 300 includes a processor 305, a memory 310, an input device 315, an output device 320, and a transceiver 325.

[0056] The input device 315 and the output device 320 may be combined into a single device, such as a touch screen. In some implementations, the network node 300 does not include any input device 315 and / or output device 320. The network node 300 may include one or more of the following: a processor 305, a memory 310, and a transceiver 325, and may not include an input device 315 and / or an output device 320.

[0057] As shown, the transceiver 325 includes at least one transmitter 330 and at least one receiver 335. Here, the transceiver 325 communicates with one or more remote units 200. In addition, the transceiver 325 can support at least one network interface 340 and / or application interface 345. (Multiple) application interface 345 can support one or more APIs. (Multiple) network interface 340 can support 3GPP reference points such as Uu, N1, N2 and N3. As understood by those of ordinary skill in the art, other network interfaces 340 can be supported.

[0058] The processor 305 may include any known controller capable of executing computer-readable instructions and / or capable of performing logical operations. For example, the processor 305 may be a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, an FPGA, or a similar programmable controller. The processor 305 may execute instructions stored in the memory 310 to perform the methods and routines described herein. The processor 305 is communicatively coupled to the memory 310, the input device 315, the output device 320, and the transceiver 325.

[0059] Memory 310 may be a computer-readable storage medium. Memory 310 may include volatile computer storage media. For example, memory 310 may include RAM, including dynamic RAM ("DRAM"), synchronous dynamic RAM ("SDRAM"), and / or static RAM ("SRAM"). Memory 310 may include non-volatile computer storage media. For example, memory 310 may include a hard drive, flash memory, or any other suitable non-volatile computer storage device. Memory 310 may include both volatile and non-volatile computer storage media.

[0060] The memory 310 may store data related to establishing a multipath unicast link and / or mobile operation. For example, the memory 310 may store parameters, configurations, resource allocations, policies, etc. described herein. The memory 310 may also store program codes and related data, such as an operating system or other controller algorithms operating on the network node 300.

[0061] Input device 315 may include any known computer input device, including a touch panel, buttons, keyboard, stylus, microphone, etc. Input device 315 may be integrated with output device 320, for example as a touch screen or similar touch sensitive display. Input device 315 may include a touch screen so that text can be entered using a virtual keyboard displayed on the touch screen and / or by handwriting on the touch screen. Input device 315 may include two or more different devices, such as a keyboard and a touch panel.

[0062] Output device 320 may be designed to output visual, auditory and / or tactile signals. Output device 320 may include an electronically controllable display or display device capable of outputting visual data to a user. For example, output device 320 may include, but is not limited to, an LCD display, an LED display, an OLED display, a projector, or a similar display device capable of outputting images, text, etc. to a user. As another non-limiting example, output device 320 may include a wearable display that is separate from the rest of network node 300 but communicatively coupled, such as a smart watch, smart glasses, a head-up display, etc. In addition, output device 320 may be a component of a smart phone, a personal digital assistant, a television, a desktop computer, a notebook (laptop) computer, a personal computer, a vehicle dashboard, etc.

[0063] Output device 320 may include one or more speakers for producing sound. For example, output device 320 may produce an audible alarm or notification (e.g., a buzzer or beep). Output device 320 may include one or more tactile devices for producing vibration, motion, or other tactile feedback. All or part of output device 320 may be integrated with input device 315. For example, input device 315 and output device 320 may form a touch screen or similar touch-sensitive display. Output device 320 may be located near input device 315.

[0064] The transceiver 325 includes at least one transmitter 330 and at least one receiver 335. One or more transmitters 330 can be used to communicate with the UE, as described herein. Similarly, one or more receivers 335 can be used to communicate with network functions in the PLMN and / or RAN, as described herein. Although only one transmitter 330 and one receiver 335 are shown, the network node 300 can have any suitable number of transmitters 330 and receivers 335. In addition, the (multiple) transmitters 330 and (multiple) receivers 335 can be any suitable type of transmitter and receiver.

[0065] The fifth generation (5G) network system (also abbreviated as 5GS) features network slicing. Network slicing enables network operators to divide ("slice") network resources into finer-grained logical networks, known as network slices. Such network slices can provide customized network connections (or network functions) to customers or application service providers.

[0066] A network slice is a logical network that includes a set of network functions and the corresponding resources (e.g., computing, storage, network) necessary to provide certain network functions and network features. A network slice may include core network (5G core network 5GC) control plane and user plane network functions (NF) and access network (e.g., 5G radio access network or fixed access network).

[0067] A user equipment (UE) may be configured with network slice related information, which is referred to as network slice selection assistance information (NSSAI). NSSAI may include a single or multiple S-NSSAIs (single network slice selection assistance information). The UE requests registration to a network slice by sending a NAS registration request message to the 5GC (e.g., AMF), which includes a requested NSSAI, which contains a list of one or more S-NSSAIs that the UE wants to register with. The 5GC (e.g., AMF) may send one or more of the following elements related to the UE's network slice configuration to the UE in a registration accept message or in a UE configuration update command message: allowed NSSAI, configured NSSAI, rejected NSSAI, or pending NSSAI. NSSAI is a list of one or more S-NSSAIs.

[0068] Figure 4 An example 5GS architecture 400 is shown for a UE 410 associated with two network slices 440, 450. The network slices are deployed in Figure 4 The network slice instance-1 440 (e.g., "NSI-1") represented by a dotted line in FIG. Figure 4 4. The example architecture 400 is a network slice instance-2 450 ("NSI-2") represented by a dashed line in FIG. 4. According to the example architecture 400, the (radio) access network ((R)AN) 420 is part of both slices 440, 450 and is therefore shared. The core network (CN) part 430 of the network slices (or NSIs) 440, 450 has common control plane network functions (CCNFs). Each network slice has dedicated CN network functions, such as SMF1 442, UPF1 444 and other NFs 446 belonging to NSI-1 440 and SMF2 452, UPF2 454 and other NFs 456 belonging to NSI-2 450.

[0069] Figure 4 Also shown are interfaces for communication between different functions, which are labeled N2, N3, N4, and N11. Note that Figure 4 Not including all NFs and all reference points. More information about the functionality of NFs (e.g. AMF, NSSF, SMF, UPF, etc.), reference points, and 5GS can be found in: 3GPP TS 23.501, V17.6.0, 2022-09, “System Architecture for the 5G System”; and 3GPP TS 23.502, V17.6.0, 2022-09, “Procedures for the 5G System”.

[0070] 3GPP TR 23.700-41, V1.1.0, 2022-10, "Study on enhancement of networkslicing, Phase 3, (Release 18)" addresses some scenarios and presents some candidate solutions for the support of network slice service continuity during UE mobility due to non-support of network slices in the target RAN node or resource limitations of network slices. Those scenarios occur because network slices do not need to be available in all tracking areas (TAs) of the network, and these solutions focus on achieving slice remapping within the radio access network (RAN) or based on deployment improvements.

[0071] The following scenarios (or events) may occur in the network, causing the need to change the network slice, for example, the first network slice (S-NSSAI-1) may be exchanged with the second network slice (S-NSSAI-2):

[0072] No mobility scenario 1: The network slice or network slice instance is overloaded or undergoing planned maintenance in the CN (e.g., network slice termination);

[0073] No mobility scenario 2: The network performance of the network slice cannot meet the SLA agreed with the network slice customer, so the UE should use another network slice that will better meet the SLA;

[0074] Mobility scenarios, especially in case of Inter-Registration Area (RA) mobility, where the network slice or network slice instance is overloaded in the target CN.

[0075] If an existing network slice or network slice instance cannot serve a particular PDU session, or if an existing network slice instance cannot meet the performance requirements of the application using it, the network operator may want to replace this network slice with an alternative network slice. This replacement may be temporary. The network slice to be replaced can be identified by the old / previous / first S-NSSAI (also referred to as S-NSSAI#1). The alternative network slice can be identified by an alternative S-NSSAI (also referred to as S-NSSAI#2). In a specific scenario, when the UE roams in a visited PLMN (e.g., a V-PLMN), the UE can use a home-routed PDU session, where the PDU session is anchored in the home PLMN (e.g., an H-PLMN) and the PDU session is established through the S-NSSAI in the V-PLMN and the S-NSSAI in the H-PLMN. The UE's allowed NSSAI contains the V-PLMN S-NSSAI and a mapping of the V-PLMN S-NSSAI to the H-PLMN S-NSSAI. The H-PLMN should be able to replace the S-NSSAI used in the H-PLMN in certain circumstances. It is not clear how the H-PLMN can trigger the replacement of the H-PLMN S-NSSAI with the alternative H-PLMN S-NSSAI (temporarily). The AMF needs to be aware that the first network slice needs to be replaced with the alternative network slice, regardless of roaming or not.

[0076] 3GPP TR 23.700-41, V1.1.0, 2022-10, “Study on enhancement of networkslicing, Phase 3, (Release 18)” describes two solutions on how network slice replacement can be triggered.

[0077] In the first solution, the AMF requests assistance information from the PCF, which is assumed to be the access and mobility management PCF, such as AM-PCF. The disadvantage of this solution is that the AM-PCF uses per-UE associated signaling exchanges with the AMF, which means that the AM-PCF needs to signal the need for S-NSSAI replacement for each UE individually. Another disadvantage is that the AM-PCF in the V-PLMN is not aware of the situation of a specific network slice in the H-PLMN and therefore cannot initiate the replacement of the H-PLMN S-NSSAI.

[0078] In the second solution, the PCF responsible for session management in the H-PLMN (e.g., SM-PCF) triggers the SMF in the H-PLMN (e.g., H-SMF) to initiate re-establishment of the existing PDU session through the alternative S-NSSAI. The disadvantage of this solution is that it uses signaling on a per-UE basis instead of signaling on a per-S-NSSAI basis. In addition, since the SM-PCF is unaware of the network slice configuration in the network, it is not clear how to make the SM-PCF in the H-PLMN aware of the alternative S-NSSAI. In addition, if NAS SM signaling is used to indicate to the UE that the old H-PLMN S-NSSAI will be replaced by the alternative S-NSSAI, the AMF (in the V-PLMN) is unaware of the alternative S-NSSAI and the alternative S-NSSAI cannot be included in the new allowed NSSAI.

[0079] It should also be noted that in the roaming case, it is currently unclear how the H-PLMN can trigger the replacement of the H-PLMN S-NSSAI with the alternative H-PLMN S-NSSAI (temporarily).

[0080] A method is provided herein for triggering a (possibly temporary) replacement of a network slice (e.g., identified by an S-NSSAI) due to a mobility or non-mobility scenario as described above. It is assumed that the old / first S-NSSAI should be replaced as a whole, for example due to the decommissioning of a network slice, for example due to maintenance. The method and apparatus described herein advantageously minimize signaling overhead by signaling the replacement of the old S-NSSAI with an alternative S-NSSAI on a network slice basis rather than on a per-UE basis.

[0081] As described herein, the Network Slice Selection Function (NSSF) determines that a (possibly only temporary) replacement of the old network slice (S-NSSAI) is required, and in addition, the NSSF determines which alternative network slice (S-NSSAI) value is to be used. Specifically for roaming scenarios, the V-NSSF may request the H-NSSF to notify the H-PLMN S-NSSAI when and / or whether it should be replaced by an alternative H-PLMN S-NSSAI. The proposed solution may have the following significant features: As described herein, the NSSF may determine that a (temporary) replacement of the old S-NSSAI is required; determine an alternative NSSAI value; and notify the AMF that the S-NSSAI currently in use should be replaced by the alternative S-NSSAI value.

[0082] The NSSF may determine that (temporary) replacement of the old S-NSSAI is required based on:

[0083] Local triggers in NSSF, including triggers from the operations and maintenance (OAM) system;

[0084] · analysis received from NWDAF; and / or

[0085] Instructions received from NEF or AF.

[0086] Figure 5 An architecture 500 is shown which may be applied to the solution described herein, wherein a UE is associated with two network slices, namely one in the V-PLMN and one in the H-PLMN. Figure 5 AMF 520, V-NSSF 532, H-NSSF 534 and NWDAF 543 are shown. AMF 520 is connected to the NSSF via the N22 reference point (or also called interface), and in the case of roaming, is connected to the visited NSSF 532 (e.g., V-NSSF). V-NSSF 532 is connected to the NSSF in the home PLMN 514 (e.g., H-NSSF 534) via the N31 reference point. H-NSSF 534 is connected to the network data analysis function (NWDAF) 543 in the H-PLMN 514 via the N34 reference point.

[0087] NSSF supports the following features:

[0088] Selecting a set of network slice instances to serve the UE;

[0089] Determine the allowed NSSAIs and their mapping to subscribed S-NSSAIs (if required);

[0090] Determine the configured NSSAI and its mapping to the subscribed S-NSSAI (if required);

[0091] Determine the set of AMFs that will be used to serve the UE, or based on configuration, determine a list of candidate AMFs, possibly by querying the NRF;

[0092] NSSF can provide support for network slice restrictions and network slice instance restrictions based on NWDAF analysis.

[0093] In addition to the above, the NSSF described in this article provides the following additional features:

[0094] Determine that the (old / first) S-NSSAI must be replaced by an alternative S-NSSAI; and additionally the alternative S-NSSAI value. This decision may be based on new data analysis received from the NWDAF regarding overload or congestion of the S-NSSAI (e.g. in the user plane or control plane) or that the S-NSSAI cannot meet the negotiated service level agreement (SLA) for the service provided by the S-NSSAI.

[0095] Provide a notification service to the consumer NF (e.g. AMF, V-NSSF) to indicate that (1) the old S-NSSAI needs to be replaced by an alternative S-NSSAI (e.g. temporary) and (2) the replacement has been terminated and the old S-NSSAI can be used again. This includes triggering the S-NSSAI replacement procedure, as described below with reference to Figure 6 described.

[0096] Please note that the "alternative" S-NSSAI functionality or "compatible" S-NSSAI functionality refers to functionality supported by the network and the UE where the first S-NSSAI of a PDU session may be exchanged with another (second) S-NSSAI, where the second S-NSSAI may or may not be part of the network slice currently configured for the UE. The alternative S-NSSAI may be denoted S-NSSAI#2, while the S-NSSAI to be replaced is denoted S-NSSAI#1. In the case of roaming, the concepts H-PLMN S-NSSAI#1 and H-PLMN S-NSSAI#2 are used to show that these are network slices in the H-PLMN.

[0097] It should also be noted that while this document uses the term PLMN to refer to a public network, the solutions described herein may also be applicable to non-public networks, such as SNPNs.

[0098] Figure 6 A signaling flow 600 is shown for triggering a procedure for replacement of S-NSSAI by NSSF. The signaling flow 600 includes the AMF requesting the NSSF to notify the AMF when replacement of the S-NSSAI is required. The figure shows a roaming case with a visited PLMN (V-PLMN) 612 and a home PLMN (H-PLMN) 614. However, the present method is also applicable to non-roaming cases when only a single NSSF is used. The "H-" in front of the network function (NF) name indicates that the NF is located in the H-PLMN 614, while the "V-" in front of the NF name indicates that the NF is located in the V-PLMN 612.

[0099] Figure 6UE 610, AMF 620, V-NSSF 632, H-NSSF 634, H-OAM 641, H-NWDAF 643 and H-NEF / AF 645, V-SMF 652, H-SMF1 654a and H-SMF2 654b are shown. Process 600 starts at step 671, and AMF 620 serves one or more network slices. One or more UEs are registered in AMF 620, where AMF 620 maintains the mobility management (MM) context of the UE, and the MM context contains the allowed NSSAI with the S-NSSAI set. AMF 620 can request / subscribe to (V-)NSSF 632 to receive notifications about events (or requirements) that one or more currently provided network slices (e.g., S-NSSAI sets provided or served by the AMF) need to be replaced (or exchanged) with one or more alternative network slices.

[0100] For example, AMF 620 may use the Nnssf_NSSAIAvailability_Subscribe service operation and include a new parameter or a new event to indicate whether replacement of any S-NSSAI part in the S-NSSAI set is required. In another example, AMF 620 may use a new service operation to request a notification from NSSF. For example, in the case of a roaming UE, AMF 620 may indicate whether V-PLMN S-NSSAI and / or H-PLMN S-NSSAI (e.g., S-NSSAI#1) should be monitored for replacement. Typically, AMF 620 may request a network slice set (i.e., a list of S-NSSAIs), and NSSF 632 shall provide a replacement notification for the network slice set. The network slice set corresponds to a network slice served by the AMF.

[0101] Additionally or alternatively, when there is a UE (e.g., roaming) serving the AMF 620 that uses a PDU session for home routed (HR) traffic, the AMF 620 may subscribe only to notifications for the H-PLMN S-NSSAI. If the UE's "SMF selection subscription data" indicates that home routed traffic for a particular S-NSSAI is preferred (i.e., LBO is not allowed), the AMF 620 determines that the H-PLMN S-NSSAI will be involved, and the AMF 620 determines to subscribe to the NSSF for a replacement of the H-PLMN S-NSSAI, optionally in addition to subscribing to a replacement of the V-PLMN S-NSSAI. In other words, for a UE (e.g., roaming) that uses a local breakout (LBO) session, the AMF 620 does not need to subscribe to notifications related to the H-PLMN S-NSSAI replacement.

[0102] AMF 620 may determine a specific NSSF connection to support a new function that triggers the S-NSSAI replacement process. For this purpose, the NSSF that supports the new function may register its new function with the NRF. AMF 620 requests from the NRF to resolve the NSSF that supports the function triggered by the S-NSSAI replacement. The NRF will return one or more NSSFs that support the new function to the AMF 620.

[0103] At 672, in a non-roaming case (i.e., for an S-NSSAI served by a V-PLMN 612), the NSSF 632 may determine that the original and / or old S-NSSAI (i.e., the V-PLMN S-NSSAI) needs to be replaced. The NSSF also determines an alternative S-NSSAI to replace the original / old S-NSSAI. The NSSF may receive a trigger for replacement of the original / old S-NSSAI by any of the methods described in steps 674a, 674b, or 674c described in detail below, except that the OAM system, NWDAF, and NEF / AF are located in the V-PLMN, i.e., in the same network where the NSSF is located.

[0104] If the NSSF determines that the original / old S-NSSAI is to be replaced, the NSSF proceeds to step 676 .

[0105] At 673, in the roaming case, when there is a UE that has registered an S-NSSAI from the H-PLMN 614 (i.e., H-PLMN S-NSSAI), the (V-)NSSF 632 may discover the NSSF in the H-PLMN (i.e., H-NSSF 634) and establish a signaling association with the H-NSSF 634. The (V-)NSSF 632 may use the Nnssf_NSSAIAvailability_Subscribe service operation and include a new parameter or a new event to indicate whether replacement of any S-NSSAI part in the S-NSSAI set is required.

[0106] At 674, H-NSSF 634 may locally determine that the original / old S-NSSAI#1 becomes unavailable (or fails to meet the SLA), and may determine that the S-NSSAI must be replaced. AMF 620 may additionally determine an alternative S-NSSAI (e.g., S-NSSAI#2) that should replace S-NSSAI#1. The reason why S-NSSAI#1 becomes unavailable may be a non-mobility event (e.g., OAM or NF reconfiguration, S-NSSAI#1 will be closed due to network maintenance).

[0107] The AMF 620 may use one of the following inputs or processes to obtain information in order to trigger S-NSSAI #1 replacement:

[0108] 674a: The OAM system 641 of the H-PLMN 614 may trigger the replacement of S-NSSAI #1 with the alternative S-NSSAI #2.

[0109] 674b: The NSSF may have subscribed to the NWDAF 643 to receive new data analytics regarding overload or congestion of the S-NSSAI (eg, in the user plane or control plane) or the S-NSSAI's inability to meet the negotiated service level agreement (SLA) for the service provided by the S-NSSAI.

[0110] 674c: The NSSF may receive a request from an application function (AF) 645 directly or via a network development function (NEF) 645 for a need to replace S-NSSAI #1. One reason for the AF 645 to trigger a temporary replacement of S-NSSAI #1 may be unsatisfactory quality of experience (e.g., QoE). The request from the AF or NEF 645 may also include S-NSSAI #2 to replace S-NSSAI #1.

[0111] After one or more triggering events in 674a, 674b, or 674c, (H-)NSSF 634 may be able to determine an alternative network slice (e.g., S-NSSAI #2) that may replace S-NSSAI #1. (H-)NSSF 634 determines the alternative S-NSSAI #2 based on local configuration or stored input from various AMFs (from the same PLMN, e.g., H-PLMN in this case) regarding available S-NSSAIs and their tracking area deployments.

[0112] At 675, H-NSSF 634 sends a notification to (V-)NSSF 632 to indicate that H-PLMN S-NSSAI#1 will be replaced by alternative H-PLMN S-NSSAI#2. H-NSSF 634 may also send an H-PLMN NRF responsible for the resolution of the NF in alternative H-PLMN S-NSSAI#2. The Nnssf_NSSAIAvailability_Notify service operation may be used for this purpose, with new parameters indicating that H-PLMN S-NSSAI#1 will be replaced by alternative H-PLMN S-NSSAI#2. Alternatively, a new notification message may be used for this purpose. Note that the H-NSSF will also notify the AMF in the H-PLMN that S-NSSAI#1 needs to be replaced, but this is not shown in the figure because the notification to the AMF in the same network (e.g., H-PLMN in this example) is shown in step 676.

[0113] At 676, the (V-)NSSF 632 sends a notification to the AMF 620 to indicate: (1) if the NSSF is triggered by step 672, the V-PLMN S-NSSAI is to be replaced; or (2) if the NSSF is triggered by step 675, the H-PLMN S-NSSAI#1 is to be replaced in the roaming case. In addition, the NSSF may indicate an alternative S-NSSAI (e.g., an alternative V-PLMN S-NSSAI or an alternative H-PLMN S-NSSAI#2) to the AMF. In the roaming case, the NSSF may also include an H-PLMN NRF responsible for the resolution of the NF in the alternative H-PLMN S-NSSAI#2. The Nnssf_NSSAIAvailability_Notify service operation may be used for this purpose, with a new parameter indicating that a specific S-NSSAI (e.g., a V-PLMN S-NSSAI or H-PLMN S-NSSAI#1) is to be replaced by an alternative H-PLMN S-NSSAI#2. Alternatively, a new notification message may be used for this purpose.

[0114] When network slice replacement, for example, S-NSSA#1 (e.g., V-PLMN S-NSSAI or H-PLMN S-NSSAI) is triggered by NSSF and the alternative network slice is S-NSSAI#2, AMF 620 determines that the existing established PDU session on S-NSSA#1 should be transferred to the alternative network slice S-NSSAI#2. Here, "transfer of PDU session" means that the PDU session can be re-established on the alternative network slice S-NSSAI#2 (e.g., alternative V-PLMN S-NSSAI or alternative H-PLMN S-NSSAI).

[0115] At 677, the AMF 620 may trigger a configuration update of the network slice of the UE 610, for example, by using a UE Configuration Update (UCU) procedure. The AMF 620 may update the allowed NSSAI, configured NSSAI, and rejected NSSAI in the UE 610.

[0116] The AMF 620 may send at least one of the following information to the UE 610 (e.g., as part of the allowed NSSAI):

[0117] V-PLMN S-NSSAI in the allowed NSSAI;

[0118] · Mapping of V-PLMN S-NSSAI to alternative H-PLMN S-NSSAI #2; and

[0119] · Mapping / replacement of alternative H-PLMN S-NSSAI#1 to H-PLMN S-NSSAI#2.

[0120] Note that AMF 620 may also send a request to NSSF for: newly configured NSSAI, allowed NSSAI (e.g., including S-NSSAI-2), and / or rejected NSSAI. AMF 620 may include the associated mapping information of S-NSSAI#2 to S-NSSAI#1 as an input parameter in the request message.

[0121] At 678a (which may be performed after step 677 succeeds, or in parallel with step 677), the AMF 620 performs an internal check to determine whether there is an established PDU session (e.g., a home routing PDU session) associated with the S-NSSAI to be replaced (e.g., H-PLMN S-NSSAI#1). If so, the AMF 620 may send signaling to the anchor SMF (e.g., H-SMF1 654a) of the PDU session to trigger the anchor SMF to release or modify the PDU session caused by the replacement of the S-NSSAI (e.g., replacement of H-PLMN S-NSSAI#1). The AMF 620 sends a signaling request for session management to the anchor SMF to update the H-SMF (654a or 654b) that the PDU session needs to be reallocated to a different S-NSSAI. The AMF 620 includes an indication that the PDU session needs to be reallocated from the H-PLMN S-NSSAI#1, and / or additionally the H-PLMN S-NSSAI#2 may be included. The AMF 620 may trigger this step using the Nsmf_PDUSession_UpdateSMContext request service operation.

[0122] At 678b, in a roaming scenario, the V-SMF 652 forwards the message (Nsmf_PDUSession_UpdateSMContext Request) received in step 677a to the H-SMF (eg, H-SMF1 654a).

[0123] At 679, the H-SMF determines to trigger a release of the PDU session (e.g., in the case where the PDU session is of SSC mode 1 or 2 type) or a PDU session modification (e.g., in the case where the PDU session is of SSC mode 3 type). The H-SMF 654a sends NAS SM signaling to the UE to release or modify the PDU session by establishing a new PDU session on the appropriate S-NSSAI.

[0124] At 680a, UE 610 requests establishment of a new PDU session, including mapping H-PLMN S-NSSAI#2 to H-PLMN S-NSSAI#1.

[0125] At 680b, the AMF 620 selects an anchor SMF (e.g., H-SMF2 654b) in the network slice identified by the H-PLMN S-NSSAI#2. The AMF 620 may use the NRF services in the H-PLMN, where the AMF 620 may know the NRF identity in the H-PLMN from step 676. During the establishment of a new PDU session, the AMF 620 uses the alternative S-NSSAI (e.g., alternative H-PLMN S-NSSAI#2) to resolve the H-SMF for the HR PDU session. The AMF 620 uses this H-PLMN NRF to resolve a new SMF in the H-PLMN (e.g., H-SMF2 654b), which will be used for the alternative H-PLMN S-NSSAI#2, as indicated in step 676.

[0126] The AMF 620 sends a session management request message to the V-SMF 652 to create a new PDU session, wherein the AMF 620 may include an indication that the H-PLMN S-NSSAI#2 is mapped to the H-PLMN S-NSSAI#1. For example, the AMF 620 may request a service operation using Nsmf_PDUSession_CreateSMContext.

[0127] At 680c, V-SMF 652 further forwards the message received in step 680b to H-SMF2 654b.

[0128] Note that the solution also applies to the scenario where the UE is registered to S-NSSAI#1 and no PDU session is established on S-NSSAI#1. In other words, as long as the AMF 620 maintains any UE context with allowed NSSAI (including S-NSSAI#1 (or H-PLMN S-NSSAI#1)), the AMF 620 can subscribe / request to be notified by the (V-)NSSF when S-NSSAI#1 (or H-PLMN S-NSSAI#1) must be replaced.

[0129] The benefit of the solution described herein is that the (temporary) replacement of network slices is monitored, maintained and determined by the NSSF, which has a global overview of the deployment of network slices in the network (e.g. PLMN or SNPN). When the NSSF determines that a replacement of the S-NSSAI is required, the AMF 620 requests / subscribes to notifications from the NSSF. The NSSF in the serving network (e.g. V-NSSF 632) can exchange with the NSSF in the home network (e.g. H-NSSF 634) to determine whether the S-NSSAI in the home network 614 needs to be replaced.

[0130] In another embodiment, the NSSF may determine that the network slice (e.g., S-NSSAI#1) for which the replacement has been determined and notify the AMF that it no longer needs to be replaced. In other words, the NSSF determines that the replacement of S-NSSAI#1 with S-NSSAI#2 can be terminated, and S-NSSAI#1 can be used normally.

[0131] In such a case, the method performed by NSSF includes:

[0132] · Determine that replacing S-NSSAI#1 with S-NSSAI#2 can be terminated, and S-NSSAI#1 can be used normally. This is similar to Figure 6 672 or 674 in which the NSSF determines that S-NSSAI #1 can be used again without replacement. In one example, the determination can be based on analysis of new or existing network data received from the NWDAF indicating network slice availability or low load / congestion for S-NSSAI #1.

[0133] Send a notification to the consumer NF (e.g. AMF 620 or V-NSSF 632) that the replacement of S-NSSAI#1 is not required or has been terminated. This is similar to Figure 6 Step 675 or 676 in which the parameters in the notification message indicate that S-NSSAI#1 can be reused without replacing it.

[0134] Continue to monitor whether network slices or other network slice replacements are needed.

[0135] When the AMF receives the notification that the replacement of the network slice is terminated, the AMF creates a new allowed NSSAI, configured NSSAI and / or rejected NSSAI, where the alternative S-NSSAI (e.g. S-NSSAI #2) is removed from the allowed NSSAI or configured NSSAI, and the mapping of S-NSSAI #2 to S-NSSAI #1 is also removed. S-NSSAI #1 may be included in the allowed NSSAI and / or configured NSSAI, just as it was before the S-NSSAI replacement procedure had been performed. The AMF triggers the network slice configuration procedure to the UE. The AMF may use the UCU procedure for this purpose, such as Figure 6 As shown in step 677 in .

[0136] In addition, the AMF triggers an update procedure to the anchor SMF serving the PDU Session associated with the alternative S-NSSAI #2. The AMF may indicate to the anchor SMF that the PDU Session on S-NSSAI #2 must be terminated and re-established on S-NSSAI #2. In one example, this is consistent with Figure 6 The process shown in steps 678, 679 and 680 is the same, but the parameters in the message are different:

[0137] • The new parameter indicates that the PDU session needs to be reallocated from S-NSSAI#2 to S-NSSAI#1, rather than an indication that the PDU session needs to be reallocated from S-NSSAI#1 to S-NSSAI#2.

[0138] When the UE triggers re-establishment of the PDU session in step 680a, the UE does not send the mapping information of S-NSSAI#2 to S-NSSAI#1 because the mapping information should have been deleted in the UE in step 677.

[0139] Therefore, a first network function "NF" for wireless communication is provided, comprising: a processor; and a memory coupled to the processor, the processor being configured to cause the apparatus to determine replacement of a network slice by: receiving a request for notification when a network slice is to be replaced from a second NF; determining that the network slice is to be replaced and determining an alternative network slice to replace the network slice; and sending a notification message to the second NF, the notification message including the notification that the network slice is to be replaced. The first network function may include a network slice selection function (NSSF). The second NF may be an access and mobility management function (AMF).

[0140] The method defined herein provides a mechanism by which a second network function (such as an AMF) can be notified of a change in a network slice. Such a mechanism improves the operation of a wireless communication network by facilitating a change to an alternative network slice when a network slice in a first set of network slices needs to be replaced. The mechanism tends to ensure that a PDU session established on a network slice is transferred to an alternative network slice, and it can ensure service continuity, and it can include maintaining quality of service. The quality of service can be defined in a service level agreement (SLA).

[0141] The request for notification of when a network slice is to be replaced may also include at least one of the following: a request for an indication of an alternative network slice to replace the network slice; and a first set of network slices for which the notification must be provided, wherein the network slice is a member of the first set of network slices. The first set of network slices may include a list of network slices. The first set of network slices may include a list of S-NSSAIs. The first set of network slices may include any network slices served by the second NF. Determining that a network slice is to be replaced may include determining that at least one network slice in the first set of network slices is to be replaced.

[0142] The notification message sent to the second NF may additionally include an indication of the identity of the alternative network slice.

[0143] Determining that a network slice is to be replaced and determining an alternative network slice to replace the network slice in a roaming situation may include sending a request for notification to a third NF in a home network to request a notification of replacement of the network slice. The third NF may include a home NSSF (H-NSSF). The home network may be a home public land mobile network (H-PLMN).

[0144] Determining that a network slice is to be replaced and determining an alternative network slice for replacing the network slice may include: receiving a notification about unavailability or a serious condition of the network slice from a fourth NF. The fourth NF may include a network function, an application function, or a network data analysis function (NWDAF).

[0145] The first NF may determine that the network slice to be replaced can be reused; wherein the first NF sends a notification to the second NF that the network slice to be replaced can be reused.

[0146] The second NF may be an Access and Mobility Management Function “AMF”. The second NF may be a Visited Network Slice Selection Function “V-NSSF”.

[0147] Figure 7A method 700 for a first network function "NF" to determine a replacement of a network slice is shown. The method 700 includes: receiving 710 a request for notification when a network slice is to be replaced from a second NF; determining 720 that the network slice is to be replaced and determining an alternative network slice to replace the network slice; and sending 730 a notification message to the second NF, the notification message including a notification that a network slice in a first set of network slices is to be replaced.

[0148] In some embodiments, the method 700 may be performed by a processor that executes program code, such as a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, an FPGA, etc.

[0149] The method defined in this document provides a mechanism by which a second network function (such as an AMF) can be notified of a change in a network slice. Such a mechanism improves the operation of the wireless communication network by facilitating the change to an alternative network slice when a network slice in a first set of network slices needs to be replaced. The mechanism tends to ensure that PDU sessions established on the network slice are transferred to the alternative network slice, and it can ensure service continuity, and it may include maintaining quality of service. The quality of service can be defined in a service level agreement (SLA). The first network function may include a network slice selection function (NSSF). The second NF may be an access and mobility management function (AMF).

[0150] The request for notification of when a network slice is to be replaced may also include at least one of the following: a request for an indication of an alternative network slice to replace the network slice; and a first set of network slices for which the notification must be provided, wherein the network slice is a member of the first set of network slices. The first set of network slices may include a list of network slices. The first set of network slices may include a list of S-NSSAIs. The first set of network slices may include any network slices served by the second NF. Determining that a network slice is to be replaced may include determining that at least one network slice from the first set of network slices is to be replaced.

[0151] The notification message sent to the second NF may additionally include an indication of the identity of the alternative network slice.

[0152] Determining that a network slice is to be replaced and determining an alternative network slice to replace the network slice in a roaming situation may include sending a request for notification to a third NF in a home network to request notification of replacement of a network slice in the first set of network slices. The third NF may include a home NSSF (H-NSSF). The home network may be a home public land mobile network (H-PLMN).

[0153] Determining that a network slice is to be replaced and determining an alternative network slice for replacing the network slice may include: receiving a notification about unavailability or a serious condition of the network slice from a fourth NF. The fourth NF may include a network function, an application function, or a network data analysis function (NWDAF).

[0154] The first NF may determine that the network slice to be replaced can be used again; and wherein the first NF sends a notification to the second NF that the network slice to be replaced can be used again.

[0155] The second NF may be an Access and Mobility Management Function “AMF”. The second NF may be a Visited Network Slice Selection Function “V-NSSF”.

[0156] A second network function "NF" for wireless communication is also provided, comprising: a processor; and a memory coupled to the processor. The processor is configured to cause the device to determine the replacement of a network slice by: sending a request to a first NF for a notification when the network slice is to be replaced; and receiving a notification message from the first NF, the notification message including a notification that the network slice is to be replaced.

[0157] The method defined in this document provides a mechanism by which a second network function (such as an AMF) can be notified of a change in a network slice. Such a mechanism improves the operation of the wireless communication network by facilitating the change to an alternative network slice when a network slice in a first set of network slices needs to be replaced. The mechanism tends to ensure that PDU sessions established on the network slice are transferred to the alternative network slice, and it can ensure service continuity, and it can include maintaining the quality of service. The quality of service can be defined in a service level agreement (SLA). The second NF can be a access network slice selection function "V-NSSF". The first network function can include a network slice selection function (NSSF).

[0158] The request for notification of when a network slice is to be replaced may also include at least one of: a request for an indication of an alternative network slice to replace the network slice; and notification of a first set of network slices for which it must be provided, wherein the network slice is a member of the first set of network slices. The first set of network slices may include a list of network slices. The first set of network slices may include a list of S-NSSAIs. The first set of network slices may include any network slice served by the second NF.

[0159] The notification received from the first NF that the network slice is to be replaced also includes an identification of an alternative network slice to replace the network slice.

[0160] The second NF may also include determining that a packet data unit "PDU" session needs to be reallocated to an alternative network slice and sending a modification request to the fifth NF.

[0161] The PDU Session Modification Request may identify an alternative network slice. The alternative network slice replaces a network slice of the first set of network slices. The fifth NF may be an anchor session management function (SMF, which is the home SMF, H-SMF in the case of roaming with a home-routed PDU session). A PDU Session Modification Request may be sent to the H-SMF when the H-PLMN S-NSSAI must be replaced with an alternative H-PLMN S-NSSAI.

[0162] Figure 8 A method 800 for a second network function "NF" to determine a replacement of a network slice is shown, the method 800 comprising: sending 810 a request to a first NF for a notification of when the network slice is to be replaced; and receiving 820 a notification message from the first NF, the notification message comprising a notification that the network slice is to be replaced.

[0163] In some embodiments, the method 800 may be performed by a processor that executes program code, such as a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, an FPGA, etc.

[0164] The method defined in this document provides a mechanism by which a second network function (such as an AMF) can be notified of a change in a network slice. Such a mechanism improves the operation of the wireless communication network by facilitating the change to an alternative network slice when a network slice in a first set of network slices needs to be replaced. The mechanism tends to ensure that PDU sessions established on the network slice are transferred to the alternative network slice, and it can ensure service continuity, and it may include maintaining the quality of service. The quality of service can be defined in a service level agreement (SLA). The second NF can be an access and mobility management function "AMF". The second NF can be a access network slice selection function "V-NSSF". The first network function may include a network slice selection function (NSSF).

[0165] The request for notification of when a network slice is to be replaced may also include at least one of: a request for an indication of an alternative network slice to replace it; and notification of a first set of network slices for which it must be provided, wherein the network slice is a member of the first set of network slices. The first set of network slices may include a list of network slices. The first set of network slices may include a list of S-NSSAIs. The first set of network slices may include any network slice served by the second NF.

[0166] The notification message received from the first NF including the notification that the network slice is to be replaced may also include an identifier of an alternative network slice to replace the network slice.

[0167] The method may also include: determining that a packet data unit "PDU" session needs to be reallocated to an alternative network slice, and sending a modification request to the fifth NF. The PDU session modification request may identify the alternative network slice. The alternative network slice replaces the network slice of the first network slice set. The fifth NF may be an anchor session management function (SMF, which is the home SMF, i.e., H-SMF, in the case of roaming with a home-routed PDU session). When the H-PLMN S-NSSAI must be replaced with the alternative H-PLMN S-NSSAI, the PDU session modification request may be sent to the H-SMF.

[0168] The NSSF as described herein may be arranged to: receive a request (e.g. from a consumer NF, such as an AMF or V-NSSF) for notification of whether one or more network slices (e.g. an old S-NSSAI) are to be replaced with an alternative S-NSSAI and which alternative S-NSSAI value; send a request to another NSSF in the H-PLMN (e.g. to the H-NSSF) for notification of replacement of the H-PLMN S-NSSAI that must be replaced; determine (e.g. in the H-NSSF) the alternative S-NSSAI that should replace the old S-NSSAI; send a notification to the consumer NF (e.g. an AMF or V-NSSF) that the old S-NSSAI must be replaced with the alternative S-NSSAI; and determine that replacement of the old S-NSSAI is no longer required or that it is terminated; and send a corresponding notification to the consumer NF.

[0169] The AMF as described herein may be arranged to: determine to request a notification from the NSSF (V-NSSF or H-NSSF) regarding an event when any serving S-NSSAI (e.g., V-PLMN S-NSSAI, H-PLMN S-NSSAI) must be replaced by an alternative S-NSSAI; receive a notification (e.g., from the NSSF) that a specific S-NSSAI (e.g., V-NSSAI or H-NSSAI) must be replaced; and, in the event that the H-PLMN S-NSSAI must be replaced with an alternative H-PLMN S-NSSAI, send a PDU session modification request to the H-SMF.

[0170] Therefore, a method for a first network function (NF, such as NSSF) to determine a replacement of a network slice is provided, the method comprising: receiving a request from a second NF for a notification to determine whether one or more network slices in a first set must be replaced and which alternative network slice to replace; determining that at least one network slice from the first set must be replaced and an alternative S-NSSAI; sending a notification message to the second NF, the notification message comprising at least one of the following: a notification that a network slice from the first set must be replaced and a replacement alternative network slice.

[0171] Determining that at least one network slice from the first set must be replaced and the alternative S-NSSAI may include sending a request for notification to a third NF (e.g., H-NSSF) in the H-PLMN to request a notification of a replacement that the H-PLMN S-NSSAI must be replaced.

[0172] Determining that at least one network slice from the first set must be replaced and the alternative S-NSSAI may include receiving a notification from a fourth NF (e.g., NWDAF, NF, or AF) that the network slice is unavailable.

[0173] The second NF can be an AMF or a visiting NSSF.

[0174] It should be noted that the above methods and apparatus illustrate rather than limit the present invention, and that those skilled in the art will be able to design many alternative arrangements without departing from the scope of the appended claims. The word "comprising" does not exclude the presence of elements or steps other than those listed in the claims, "a" or "an" does not exclude a plurality, and a single processor or other unit may perform the functions of several units described in the claims. Any reference signs in the claims should not be construed as limiting their scope.

[0175] Furthermore, although examples have been given in the context of specific communication standards, these examples are not intended to limit the communication standards to which the disclosed methods and apparatus may be applied. For example, although specific examples have been given in the context of 3GPP, the principles disclosed herein may also be applied to another wireless communication system, and indeed to any communication system that uses routing rules.

[0176] The method may also be embodied in a set of instructions stored on a computer readable medium which, when loaded into a computer processor, digital signal processor (DSP) or the like, causes the processor to perform the method described above.

[0177] The described methods and apparatus may be practiced in other specific forms. The described methods and apparatus should be considered in all respects as merely illustrative and not restrictive. Therefore, the scope of the present invention is indicated by the appended claims rather than the foregoing description. All changes that belong to the equivalent meaning and scope of the claims should be included within their scope.

[0178] The following abbreviations are relevant to the areas covered by this document: 5GS, 5th Generation System; 5GC, 5th Generation Core Network; AMF, Access and Mobility Management Function; AS, Access Stratum; BS, Base Station; DSCP, Differentiated Services Code Point; eNB, Evolved Node-B; EPC, Evolved Packet Core; EPS, Evolved Packet System; FQDN, Fully Qualified Domain Name; gNB, 5G Node B; ID, Identity; IE, Information Element; LTE, Long Term Evolution; NAS, Non-Access Stratum; MM, Mobility Management; MO, Mobile Originated; MPS, Multimedia Priority Service; MT, Mobile Terminated; NAS, Non-Access Stratum; NEF, Network Exposure Function; NPN, Non Public Network; NR, New Radio; NRF, Network Repository Function; NSSAA, Network Slice Secondary Authentication and Authorization; NSSF, Network slice selection function; PDCP, packet data convergence protocol; PDU, protocol data unit; PLMN, public land mobile network; RA, registration area; RAN, radio access network; RAT, radio access technology / type; SM, session management; SMF, session management function; SMS, short message service; SNPN, standalone non-public network; SUCI, subscription hidden identifier; SUPI, subscription permanent identifier; TA, tracking area; UDM, unified data management; UCU, UE configuration update; UE, user equipment; UICC, universal integrated circuit card; UMTS, universal mobile telecommunications system; URL, uniform resource locator; URSP, UE routing policy; USIM, universal subscriber identity module; and (E)-UTRAN, (evolved) universal terrestrial radio access network.

Claims

1. A first network function "NF" for wireless communication, comprising: processor; as well as a memory coupled to the processor, the processor being configured to cause the apparatus to determine a replacement of a network slice by: receiving a request from the second NF for notification of when the network slice is to be replaced; determining that the network slice is to be replaced and determining an alternative network slice to replace the network slice; as well as A notification message is sent to the second NF, wherein the notification message includes a notification that the network slice is to be replaced.

2. The first NF according to claim 1, wherein the request for notification of when the network slice is to be replaced further comprises at least one of: a request for an indication of the alternative network slice to replace the network slice; and Notification of a first set of network slices for which provision must be made, wherein the network slice is a member of the first set of network slices.

3. The first NF according to claim 2, wherein the notification message sent to the second NF further includes an indication of the identity of the alternative network slice.

4. The first NF according to any preceding claim, wherein determining that the network slice is to be replaced and determining an alternative network slice to replace the network slice in a roaming situation comprises: A request for notification is sent to a third NF in the home network to request a notification of replacement of the network slice.

5. The first NF according to any preceding claim, wherein determining that the network slice is to be replaced and determining an alternative network slice to replace the network slice comprises: Receive a notification from the fourth NF regarding unavailability or serious condition of the network slice.

6. The first NF according to any preceding claim, wherein the first NF determines that the network slice to be replaced can be used again; and wherein the first NF sends a notification to the second NF that the network slice to be replaced can be used again.

7. The first NF according to any preceding claim, wherein the second NF is an Access and Mobility Management Function (AMF).

8. The first NF according to any one of claims 1 to 6, wherein the second NF is a access network slice selection function "V-NSSF".

9. A method for a first network function (NF) to determine a replacement of a network slice, the method comprising: receiving a request from the second NF for notification of when the network slice is to be replaced; determining that the network slice is to be replaced and determining an alternative network slice to replace the network slice; as well as A notification message is sent to the second NF, wherein the notification message includes a notification that the network slice is to be replaced.

10. The method of claim 9, wherein the request for notification of when the network slice is to be replaced further comprises at least one of: a request for an indication of the alternative network slice to replace the network slice; and Notification of a first set of network slices for which provision must be made, wherein the network slice is a member of the first set of network slices.

11. A method according to claim 10, wherein the notification message sent to the second NF further includes an indication of the identity of the alternative network slice.

12. The method according to any one of claims 9, 10 or 11, wherein determining that the network slice is to be replaced and determining an alternative network slice to replace the network slice in a roaming situation comprises: A request for notification is sent to a third NF in the home network to request notification of replacement of the network slice in the first set of network slices.

13. The method according to any one of claims 9 to 12, wherein determining that the network slice is to be replaced and determining an alternative network slice to replace the network slice comprises: Receive a notification from the fourth NF regarding unavailability or serious condition of the network slice.

14. The method according to any one of claims 9 to 13, wherein the first NF determines that the network slice to be replaced can be used again; and wherein the first NF sends a notification to the second NF that the network slice to be replaced can be used again.

15. The method according to any one of claims 9 to 14, wherein the second NF is an Access and Mobility Management Function (AMF).

16. The method according to any one of claims 9 to 14, wherein the second NF is a access network slice selection function "V-NSSF".

17. A second network function "NF" for wireless communication, comprising: processor; as well as a memory coupled to the processor, the processor being configured to cause the apparatus to determine a replacement of a network slice by: Sending a request to the first NF for notification of when the network slice is to be replaced; A notification message is received from the first NF, wherein the notification message includes a notification that the network slice is to be replaced.

18. The second NF of claim 17, wherein the request for notification of when the network slice is to be replaced further comprises at least one of: a request for an indication of the alternative network slice to replace the network slice; and Notification of a first set of network slices for which provision must be made, wherein the network slice is a member of the first set of network slices.

19. The second NF according to claim 18, wherein the notification message received from the first NF and including the notification that the network slice is to be replaced also includes an identifier of an alternative network slice to replace the network slice.

20. The second NF according to claim 17, 18 or 19, further comprising: Determine that the packet data unit "PDU" session needs to be reallocated to the alternative network slice, and send a modification request to the fifth NF.

21. A method for a second network function (NF) to determine a replacement of a network slice, the method comprising: Sending a request to the first NF for notification of when the network slice is to be replaced; A notification message is received from the first NF, wherein the notification message includes a notification that the network slice is to be replaced.

22. The method of claim 21, wherein the request for notification of when the network slice is to be replaced further comprises at least one of: a request for an indication of the alternative network slice to replace the network slice; and Notification of a first set of network slices for which provision must be made, wherein the network slice is a member of the first set of network slices.

23. The method of claim 22, wherein the notification message received from the first NF including a notification that a network slice is to be replaced also includes an identifier of an alternative network slice to replace the network slice.

24. The method of claim 21, 22 or 23, further comprising: Determine that the packet data unit "PDU" session needs to be reallocated to the alternative network slice, and send a modification request to the fifth NF.

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