Method and apparatus for accessing a core network via a gateway function - Patent Application 20070122997

Abstract

Techniques are provided for accessing a core network via an access point and a gateway function. For example, the method includes: determining one or more candidate gateway functions for accessing the core network via the access point; sending a request for use of the one or more candidate gateway functions to the one or more candidate gateway functions or to a core network function for accessing the core network; and receiving a request response for each candidate gateway function from the gateway function or from the core network function, the request response being configured to indicate whether access to the core network via the respective gateway function has been denied and, in the case of denial, to indicate a reason for the denial. The method may be performed by a terminal device (e.g., user equipment UE). Also provided is a corresponding method that may be performed by a network device.

Description

[Technical Field]

[0001] This application claims the benefit of priority to Indian Provisional Patent Application No. 202211045684 filed on August 10, 2022, the contents of which are incorporated herein by reference as if reproduced in their entirety.

[0002] The present disclosure relates generally to wireless communication systems, and more particularly to accessing a core network in a wireless communication system. Even more particularly, the present disclosure provides a method and apparatus for accessing a core network via an access point and gateway function. [Background technology]

[0003] Wireless communication systems are constantly being developed. Higher data rates and higher quality of service are constantly being demanded. Reliability requirements are constantly increasing, and methods and means are constantly being developed to ensure reliable connections and data traffic while minimizing transmission delays.

[0004] Developing networks enables new services to customers. One of the services is network slicing, which allows for the provision of connectivity, quality of service, and data processing solutions tailored to specific customer requirements. A network slice is a logical end-to-end virtual network that can be dynamically created and provides specific capabilities and characteristics. Multiple network slices can be created on a common shared physical network infrastructure to run services that may have different requirements in terms of latency, reliability, throughput, and mobility.

[0005] Furthermore, various options have been developed for accessing a communication system via different access points, which differ, among other things, in their support of different slices. Depending on the slice required by the terminal device, a suitable access gateway should be selected. The use of an access gateway requires determining whether a particular access gateway satisfies the slicing requirements of the terminal device. Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, there is a need to exchange information about the slicing requirements for various access gateways. [Means for solving the problem]

[0007] According to a first aspect of the present disclosure, there is provided a method for operating a terminal device in a communication network. The communication network includes a core network and an access point. The method includes determining one or more candidate gateway functions for accessing the core network via the access point. The method further includes sending to the one or more candidate gateway functions or to a core network function a request for use of the one or more gateway functions to access the core network. The method further includes receiving a request response for each candidate gateway function from the gateway function or from the core network function, the request response being configured to indicate whether access to the core network via the respective gateway function has been denied and, if so, a reason for the denial.

[0008] In some embodiments, the reason for the rejection includes non-support of one or more slices by the gateway function.

[0009] In some embodiments, the core network is a 3GPP core network, the access point is a non-3GPP access point, and the gateway function is for at least one of trusted non-3GPP access and non-trusted non-3GPP access.

[0010] In some embodiments, the gateway function includes at least one of a Non-3GPP Interworking Function (N3IWF) and a Trusted Non-3GPP Gateway Function (TNGF).

[0011] In some embodiments, the method further includes determining a set of one or more slices for use by the terminal device, the request being configured to indicate the set of the one or more slices.

[0012] In some embodiments, each of the one or more slices is identified by a corresponding Single Network Slice Selection Assistance Information (S-NSSAI).

[0013] In some embodiments, the request response is configured to indicate a subset of the determined set of slices, and access via the respective gateway function is denied (or allowed) to the indicated subset.

[0014] In some embodiments, multiple candidate gateway functions are determined, and sending a request to a second of the candidate gateway functions occurs before receiving a request response from a first of the candidate gateway functions.

[0015] In some embodiments, multiple candidate gateway functions are determined, and sending the request to a second of the candidate gateway functions occurs after receiving a request response from a first of the candidate gateway functions.

[0016] In some embodiments, the request comprises a registration or authentication request and / or the request response comprises a registration or authentication response.

[0017] In such a case, the method may further include: selecting one candidate gateway function from the determined one or more candidate gateway functions; and sending a registration or authentication request to a core network function via the selected gateway function.

[0018] In some embodiments, the core network functions include an Access and Mobility Management Function (AMF).

[0019] According to a second aspect of the present disclosure, there is provided a method for operating a network device in a communication network. The communication network includes a core network and an access point. The method includes receiving a request by a terminal device for use of a gateway function in accessing the core network via the access point. The method further includes transmitting a request response configured to indicate whether access by the terminal device to the core network via the gateway function has been denied, and, if so, to indicate a reason for the denial.

[0020] In some embodiments, the reason for the rejection includes non-support of one or more slices by the gateway function.

[0021] In some embodiments, the core network is a 3GPP core network, the access point is a non-3GPP access point, and the gateway function is for at least one of trusted non-3GPP access and non-trusted non-3GPP access.

[0022] In some embodiments, the gateway function includes at least one of a Non-3GPP Interworking Function (N3IWF) and a Trusted Non-3GPP Gateway Function (TNGF).

[0023] In some embodiments, the request is configured to indicate a set of one or more slices for use by the terminal device.

[0024] In some embodiments, each of the one or more slices is identified by a corresponding single network slice selection assistance information (S-NSSAI).

[0025] In some embodiments, the method further includes determining a subset of the indicated set of slices, wherein the request response is configured to indicate the determined subset, and wherein access via the gateway function is denied (or allowed) for the indicated subset.

[0026] In some embodiments, the network device includes a core network function, and the network device receives the request via a gateway function. Determining the subset may include obtaining gateway slicing information for the requested gateway function; retrieving terminal slicing information from the received request based on the indicated set of one or more slices; and determining the subset of allowed slices based on an overlap between the gateway slicing information and the terminal slicing information.

[0027] In some embodiments, the method further includes, in response to determining that the overlap is a true subset of the indicated set, identifying an alternative gateway functionality based on the terminal slicing information. In such a case, the request response may be configured to indicate the alternative gateway functionality.

[0028] In some embodiments, the network device includes a gateway function.

[0029] In some embodiments, the method further includes sending an authentication request for authentication of the terminal device to an Access and Mobility Management Function (AMF); receiving an authentication response from the AMF indicating a reason for rejection; and including the reason for rejection in the request response to the terminal device.

[0030] In some embodiments, the network device includes a core network function.

[0031] In some embodiments, the request comprises a registration or authentication request and / or the request response comprises a registration or authentication response.

[0032] In some embodiments, the core network functions include an access and mobility management function (AMF).

[0033] According to a third aspect of the present disclosure, there is provided a terminal device for use in a communication network including a core network and an access point, the terminal device comprising: at least one processor; and at least one memory containing computer program code, which, when executed with the at least one process, causes the terminal device to perform at least the steps of the method according to the first aspect.

[0034] Specifically, the method is configured to cause the terminal device to determine one or more candidate gateway functions for accessing the core network via the access point; to send to the one or more candidate gateway functions or to a core network function a request for the use of the one or more gateway functions for accessing the core network; and to receive from the gateway function or to the core network function a request response for each candidate gateway function, the request response indicating whether access to the core network via the respective gateway function has been denied, and, if denied, indicating a reason for the denial.

[0035] In some embodiments, the reason for the rejection includes non-support of one or more slices by the gateway function.

[0036] In some embodiments, the core network is a 3GPP core network, the access point is a non-3GPP access point, and the gateway function is for at least one of trusted non-3GPP access and non-trusted non-3GPP access.

[0037] In some embodiments, the gateway function includes at least one of a Non-3GPP Interworking Function (N3IWF) and a Trusted Non-3GPP Gateway Function (TNGF).

[0038] In some embodiments, the computer program code further causes the terminal device to determine a set of one or more slices for use by the terminal device, and the request is configured to indicate the set of one or more slices.

[0039] In some embodiments, each of the one or more slices is identified by a corresponding single network slice selection assistance information (S-NSSAI).

[0040] In some embodiments, the request response is configured to indicate a subset of the determined set of slices, and access via the respective gateway function is denied (or allowed) to the indicated subset.

[0041] In some embodiments, multiple candidate gateway functions are determined, and sending the request to a second of the candidate gateway functions occurs before or after receiving a request response from a first of the candidate gateway functions.

[0042] In some embodiments, the request comprises a registration or authentication request and / or the request response comprises a registration or authentication response.

[0043] In some embodiments, the computer program code further causes the terminal device to select one candidate gateway function from the determined one or more candidate gateway functions; and send a registration or authentication request to a core network function via the selected gateway function.

[0044] In some embodiments, the core network functions include an access and mobility management function (AMF).

[0045] According to a fourth aspect of the present disclosure, there is provided a network device for use in a communications network including a core network and an access point, the network device comprising: at least one processor; and at least one memory containing computer program code that, when executed with the at least one process, causes the network device to perform at least the steps of the method according to the second aspect.

[0046] Specifically, the network device receives a request by a terminal device for use of a gateway function in accessing a core network via an access point; and transmits a request response to the terminal device configured to indicate whether access by the terminal device to the core network via the gateway function has been denied, and, if denied, to indicate the reason for the denial.

[0047] In some embodiments, the reason for the rejection includes non-support of one or more slices by the gateway function.

[0048] In some embodiments, the core network is a 3GPP core network, the access point is a non-3GPP access point, and the gateway function is for at least one of trusted non-3GPP access and non-trusted non-3GPP access.

[0049] In some embodiments, the gateway function includes at least one of a Non-3GPP Interworking Function (N3IWF) and a Trusted Non-3GPP Gateway Function (TNGF).

[0050] In some embodiments, the request is configured to indicate a set of one or more slices for use by the terminal device.

[0051] In some embodiments, each of the one or more slices is identified by a corresponding single network slice selection assistance information (S-NSSAI).

[0052] In some embodiments, the computer program code further causes the network device to determine a subset of the indicated set of slices, and the request response is configured to indicate the determined subset, and access via the gateway function is denied (or allowed) for the indicated subset.

[0053] In some embodiments, the network device includes a core network function, and the network device receives the request via a gateway function, and determining the subset includes obtaining gateway slicing information for the requested gateway function; retrieving terminal slicing information from the received request based on the indicated set of one or more slices; and determining the subset of slices based on an overlap between the gateway slicing information and the terminal slicing information.

[0054] In some embodiments, the computer program code is further configured to cause the network device to, in response to determining that the overlap is a true subset of the indicated set, identify an alternate gateway functionality based on the terminal slicing information, and the request response to indicate the alternate gateway functionality.

[0055] In some embodiments, the network device includes a gateway function.

[0056] In some embodiments, the computer program code further causes the network device to send an authentication request to an Access and Mobility Management Function (AMF) for authentication of the terminal device, receive an authentication response from the AMF indicating a reason for denial, and include the reason for denial in the request response to the terminal device.

[0057] In some embodiments, the network device includes a core network function.

[0058] In some embodiments, the request comprises a registration or authentication request and / or the request response comprises a registration or authentication response.

[0059] In some embodiments, the core network functions include an access and mobility management function (AMF).

[0060] In a fifth aspect, there is provided a non-transitory computer-readable medium comprising computer-executable instructions that, when executed on one or more processors, perform the steps of the method according to the first or second aspect.

[0061] The above aspects and features may be implemented in a system, apparatus, method, article, and / or non-transitory computer-readable medium, depending on the desired configuration. The present disclosure may be implemented in and / or used with several different types of devices, including, but not limited to, mobile phones, tablet computers, wearable computing devices, portable media players, and any of a variety of other computing devices.

[0062] This summary is intended to provide a brief overview of some of the aspects and features according to the present disclosure. It should therefore be understood that the above features are merely examples and should not be construed as narrowing the scope of the present disclosure in any way. Other features, aspects, and advantages of the present disclosure will become apparent from the following detailed description, drawings, and claims.

[0063] List of abbreviations In this disclosure, the following abbreviations are used and should be understood in accordance with the given definitions: 3GPP 3rd Generation Partnership Project (3 rd Generation Partnership Project) 5G 5th Generation (Mobile Communication Network) (5 th Generation (Mobile Communication Network) 5GC 5G Core 5GS 5G System AF Application Function AMF Access and Mobility Management Function AN: Access Network APN Access Point Name AUSF Authentication Server Function BS Base Station CDMA Code Division Multiple Access CN Core Network CP Control Plane eNB Evolved NodeB EAP Extensible Authentication Protocol EPC Evolved Packet Core ePCO Extended PCO EPS Evolved Packet System ETSI European Telecommunications Standards Institute E-UTRAN Evolved UMTS Terrestrial Radio Access FQDN Fully Qualified Domain Name IE Information Element IKE Internet Key Exchange IP Internet Protocol IPSec IP Security LTE Long Term Evolution MME Mobility Management Entity N3IWF Non-3GPP Interworking Function NAS Non-Access Stratum NR New Radio NSSAI Network Slice Selection Assistance Information NSSF Network Slice Selection Function PCF Policy Control Function PCO Protocol Configuration Options PDN Packet Data Network PDP Packet Data Protocol PGW PDN Gateway PGW-C PGW Control Function PLMN Public Land Mobile Network RAN Radio Access Network RCS Rich Communication Services RRC Radio Resource Control (Protocol) RSD Route Selection Descriptor SGW Serving Gateway SIM Subscriber Identity Module SMF Session Management Function S-NSSAI Single NSSAI TNGF Trusted Non-3GPP Gateway Function TS Technical Specification UDM Unified Data Management UE User Equipment UPF User Plane Function URLLC: Ultra-Reliable Low Latency Communication URSP UE Route Selection Policy VoNR Voice over NR

[0064] The present disclosure may be better understood from the following detailed description of various embodiments when considered in conjunction with the following drawings. [Brief explanation of the drawings]

[0065] [Figure 1] 1 is a schematic diagram of an exemplary communication system comprising a base station and a plurality of communication devices; [Figure 2] 1 is a schematic diagram of an exemplary mobile communication device. [Figure 3] FIG. 2 is a schematic diagram of an exemplary control device. [Figure 4] FIG. 2 is a schematic diagram of another exemplary communication system with access points, gateway functions, and core network functions. [Figure 5] FIG. 2 is a diagram of a communication flow between a terminal device and a network device according to one embodiment. [Figure 6] FIG. 10 is a diagram of communication flow between elements according to another embodiment. [Figure 7] 1 is a flow diagram of a method according to one embodiment. [Figure 8] 1 is a flow diagram of a method according to another aspect. [Figure 9] FIG. 10 is a diagram of a communication flow between a terminal device and a network device according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0066] Before describing the examples in detail, certain general principles of wireless communication systems and mobile communication devices will be briefly described with reference to Figures 1-3 to aid in understanding the technology underlying the examples being described.

[0067] In a wireless communication system 100 as shown in FIG. 1, mobile communication devices or terminal devices (e.g., user equipment (UE)) 102, 104, 105 are provided wireless access via at least one base station (e.g., next generation NB, gNB) or similar wireless transmitting and / or receiving node, such as an access point. The base station may be controlled or assisted by at least one appropriate controller apparatus to enable its operation and management of mobile communication devices communicating with the base station. The controller apparatus may be located within a radio access network (e.g., wireless communication system 100) or a core network (CN) (not shown) and may be realized as one central apparatus or its functions may be distributed across several apparatuses. The controller apparatus may be part of a base station and / or may be provided by a separate entity, such as a radio network controller. In FIG. 1, controllers 108 and 109 are shown for controlling respective macro-level base stations 106 and 107. The controllers of the base stations may be interconnected with other control entities. The controllers are typically provided with memory capacity and at least one data processor. The controllers and functions may be distributed among multiple control units. In some systems, the control device may additionally or alternatively be located within a radio network controller.

[0068] In Figure 1, base stations 106 and 107 are shown connected to a wider communications network 113 via a gateway 112. Further gateway functions may be provided to connect to other networks.

[0069] As used herein, the term “base station” has its ordinary full-range meaning and includes, at a minimum, a wireless communications station installed at a fixed location and used to communicate as part of a wireless telephone or radio system. The communication area (or coverage area) of a base station is sometimes referred to as a “cell.” The base station and UE may be configured to communicate over a transmission medium using any of various radio access technologies (RATs), also referred to as wireless communications technologies, or telecommunications standards described below. As shown in FIG. 1, one of the base stations may act as a “serving cell” for the UE, but each UE may be able to receive signals from (possibly within communication range of) one or more other cells, which may be referred to as “neighboring cells” (which may be served by the base station and / or any other base stations).

[0070] Small base stations 116, 118, and 120 may also be connected to network 113, for example, by a separate gateway function and / or via a macro-level station controller. Base stations 116, 118, and 120 may be pico-level or femto-level base stations, etc. In an example, stations 116 and 118 are connected via gateway 111, while station 120 is connected via controller device 108. In some embodiments, small stations may not be provided. Small base stations 116, 118, and 120 may be part of a second network, for example, a WLAN, and may be WLAN APs. Communication devices 102, 104, 105 may access the communication system based on various access techniques, such as code division multiple access (CDMA) or wideband CDMA (WCDMA). Other non-limiting examples include time division multiple access (TDMA), frequency division multiple access (FDMA), and various forms of FDMA such as interleaved frequency division multiple access (IFDMA), single carrier frequency division multiple access (SC-FDMA), and orthogonal frequency division multiple access (OFDMA), spatial division multiple access (SDMA), etc.

[0071] An example of a wireless communication system is the architecture standardized by the Third Generation Partnership Project (3GPP). The latest 3GPP-based development is often referred to as Long Term Evolution (LTE) for Universal Mobile Telecommunications System (UMTS) radio access technology. Various development stages of the 3GPP specifications are called releases. More recent developments of LTE are often referred to as LTE Advanced (LTE-A). LTE (LTE-A) employs a radio mobile architecture known as Evolved Universal Terrestrial Radio Access Network (E-UTRAN) and a core network known as Evolved Packet Core (EPC). The base station in such a system is known as an evolved or enhanced Node B (eNB) and provides E-UTRAN functions such as user plane packet data convergence, radio link control, medium access control, physical layer protocols (PDCP / RLC / MAC / PHY), and control plane radio resource control (RRC) protocol termination for communication devices. Other examples of radio access systems include those provided by base stations in systems based on technologies such as Wireless Local Area Networks (WLANs) and / or Worldwide Interoperability for Microwave Access (WiMax). A base station can provide coverage for an entire cell or similar radio service area. Core network elements include a Mobility Management Entity (MME), a Serving Gateway (S-GW), and a Packet Gateway (P-GW).

[0072] An example of a suitable communication system is the 5G or NR concept. The network architecture in NR may be similar to that of LTE-Advanced. Base stations in NR systems may be known as next-generation Node Bs (gNBs). Changes to the network architecture may depend on the need to support various radio technologies and more granular QoS support, as well as some on-demand requirements for QoS levels, for example, to support QoE from the user's perspective. Network-aware services and applications, as well as service- and application-aware networks, may also bring about changes to the architecture. These are related to information-centric network (ICN) and user-centric content distribution network (UC-CDN) approaches. NR may use multiple-input, multiple-output (MIMO) antennas and more base stations or nodes than LTE (the so-called small cell concept), including macro sites that operate in conjunction with small stations and possibly also employ various radio technologies for better coverage and enhanced data rates.

[0073] Future networks may utilize network function virtualization (NFV), a network architecture concept that proposes virtualizing network node functions into "building blocks" or entities that can be operatively connected or linked together to provide services. A virtualized network function (VNF) may include one or more virtual machines that execute computer program code using standard or generic-type servers instead of customized hardware. Cloud computing or data storage may also be utilized. In wireless communications, this may mean that node operations are performed, at least in part, in a server, host, or node operatively coupled to a remote radio head. It is also possible that node operations may be distributed among multiple servers, nodes, or hosts. It should also be understood that the distribution of labor between core network operations and base station operations may differ from or even exist in LTE.

[0074] An exemplary 5G Core Network (CN) includes functional entities. The CN is connected to the UE via a Radio Access Network (RAN). A User Plane Function (UPF), whose role may be referred to as a PDU Session Anchor (PSA), is responsible for forwarding frames back and forth between a Data Network (DN) and a tunnel established over 5G toward the UE that exchanges traffic with the DN.

[0075] The UPF is controlled by a Session Management Function (SMF) that receives policies from a Policy Control Function (PCF). The CN may also include an Access & Mobility Function (AMF) or an Access and Mobility Management Function (AMF).

[0076] A possible mobile communication device will now be described in more detail with reference to FIG. 2, which shows a schematic partial cross-sectional view of a communication device 200. Such communication devices are often referred to as user equipment (UE) or terminal devices. A suitable mobile communication device may be provided by any device capable of sending and receiving wireless signals. Non-limiting examples include mobile devices such as mobile stations (MS), or what are known as cell phones or smartphones, computers equipped with wireless interface cards or other wireless interface functionality (e.g., USB dongles), personal digital assistants (PDAs), or tablets equipped with wireless communication capabilities, or any combination thereof. Mobile communication devices may provide communication of data to carry communications such as voice, electronic mail (email), text messages, multimedia, and the like. Thus, a user may be offered and provided with numerous services via the user's communication device. Non-limiting examples of these services include two-way or multi-way calls, data communication, or multimedia services, or simply access to a data communication network system such as the Internet. A user may also be provided with broadcast or multicast data. Non-limiting examples of content include downloads, television and radio programs, videos, advertisements, various alerts, and other information.

[0077] In industrial applications, the communication device may be a modem integrated into an industrial actuator (e.g., a robotic arm) and / or a modem acting as an Ethernet hub acting as a connection point for one or more connected Ethernet devices (the connections may be wired or wireless connections).

[0078] A mobile device is typically provided with at least one data processing entity 201, at least one memory 202, and possibly other components 203 for use in executing software- and hardware-assisted tasks it is designed to perform, including controlling access to and communication with access systems and other communication devices. The data processing, storage, and other associated control devices may be provided on a suitable circuit board and / or within a chipset. This feature is indicated by reference numeral 204. A user may control the operation of the mobile device by using a suitable user interface, such as a keypad 205, voice commands, a touch-sensitive screen or pad, or a combination thereof. A display 208, a speaker, and a microphone may also be provided. Additionally, the mobile communication device may include appropriate connectors (either wired or wireless) to other devices and / or for connecting external accessories, such as hands-free devices, to the communication device 200.

[0079] The communications device 200 may receive signals over an air or wireless interface 207 by means of suitable equipment for reception, and may transmit signals by means of suitable equipment for transmitting wireless signals. In Figure 2, a transceiver unit is shown schematically by block 206. The transceiver unit 206 may be provided, for example, by using a radio unit and an associated antenna arrangement. The antenna arrangement may be internal or external to the mobile device.

[0080] Communications device 200 may additionally or alternatively be configured to communicate using one or more global navigation satellite systems (GNSS, such as GPS or GLONASS), one or more mobile television broadcast standards (e.g., ATSC-M / H or DVB-H), and / or any other wireless communications protocol, as desired. Other combinations of wireless communications standards (including three or more wireless communications standards) are possible.

[0081] 2 includes a set of components configured to perform a core function. For example, the set of components may be implemented as a system-on-chip (SOC) that may include portions for various purposes. Alternatively, the set of components may be implemented as individual components or groups of components for various purposes. The set of components may be communicatively coupled (e.g., communicatively, directly or indirectly) to various other circuits of the communication device 200.

[0082] The communications device 200 may include at least one antenna that communicates with a transmitter and a receiver (e.g., transceiver unit 206). Alternatively, the transmit and receive antennas may be separate. The communications device 200 may also include a processor (e.g., at least one data processing entity 201) configured to provide signals to and receive signals from the transmitter and receiver, respectively, and to control functionality of the communications device 200. The processor may be configured to control functionality of the transmitter and receiver by causing control signaling via electrical leads to the transmitter and receiver. Similarly, the processor may be configured to control other elements of the communications device 200 by causing control signaling via electrical leads connecting the processor to other elements, such as a display (e.g., display 208) or memory (e.g., at least one memory 202). A processor may be embodied in various ways, such as, for example, a circuit, at least one processing core, one or more microprocessors with an associated digital signal processor, one or more processors without a digital signal processor, one or more coprocessors, one or more multi-core processors, one or more controllers, processing circuits, one or more computers, various other processing elements including integrated circuits (such as, for example, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), and / or the like), or some combination thereof. Thus, in some examples, a processor may comprise multiple processors or processing cores.

[0083] The communications device 200 may be capable of operating with one or more air interface standards, communications protocols, modulation types, access types, and / or the like. Signals sent and received by the processor may include signaling information according to the air interface standard of the applicable cellular system and / or any number of different wired or wireless networking techniques, including, but not limited to, Wi-Fi, wireless local access network (WLAN) techniques such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, 802.16, 802.3, ADSL, DOCSIS, and / or the like. Additionally, these signals may include speech data, user-generated data, user-requested data, and / or the like.

[0084] For example, communication device 200 and / or the cellular modem therein may be capable of operating according to various first-generation (1G), second-generation (2G or 2.5G), third-generation (3G), fourth-generation (4G), fifth-generation (5G), Internet Protocol Multimedia Subsystem (IMS) communication protocols (e.g., Session Initiation Protocol (SIP) and / or the like). For example, communication device 200 may be capable of operating according to 2G wireless communication protocols IS-136, Time Division Multiple Access (TDMA), Global System for Mobile communications (GSM), IS-95, Code Division Multiple Access (CDMA), and / or the like. Additionally, for example, communication device 200 may be capable of operating according to 2.5G wireless communication protocols General Packet Radio Service (GPRS), Enhanced Data GSM Environment (EDGE), and / or the like. Further, for example, communication device 200 may be capable of operating according to a 3G wireless communication protocol, such as Universal Mobile Telecommunications System (UMTS), Code Division Multiple Access 2000 (CDMA2000), Wideband Code Division Multiple Access (WCDMA), Time Division Synchronous Code Division Multiple Access (TD-SCDMA), and / or the like. Additionally, communication device 200 may be capable of operating according to a 3.9G wireless communication protocol, such as Long Term Evolution (LTE), Evolved Universal Terrestrial Radio Access Network (E-UTRAN), and / or the like. Additionally, for example, communication device 200 may be capable of operating according to a 4G wireless communication protocol, such as LTE-Advanced, 5G, and / or the like, as well as similar wireless communication protocols that may subsequently be developed.

[0085] It is understood that the processor may include circuitry for implementing the audio / video and logic functions of communication device 200. For example, the processor may comprise a digital signal processor device, a microprocessor device, an analog-to-digital converter, a digital-to-analog converter, and / or the like. The control and signal processing functions of communication device 200 may be allocated among these devices according to their respective capabilities. The processor may additionally comprise an internal voice coder (VC), an internal data modem (DM), and / or the like. Furthermore, the processor may include functionality for operating one or more software programs, which may be stored in memory. Generally, the processor and the stored software instructions may be configured to cause communication device 200 to perform actions. For example, the processor may be capable of operating a connectivity program, such as a web browser. The connectivity program may enable communication device 200 to send and receive web content, such as location-based content, according to protocols such as Wireless Application Protocol (WAP), Hypertext Transfer Protocol (HTTP), and / or the like.

[0086] Communications device 200 may also include a user interface, including, for example, an earphone or speaker, a ringer, a microphone, a display, a user input interface, and / or the like, which may be operably coupled to the processor. The display may include a touch-sensitive display, as described above, on which a user can touch and / or gesture to make selections, input values, and / or the like. The processor may also include user interface circuitry configured to control at least some functions of one or more elements of the user interface, such as the speaker, ringer, microphone, and display. The processor and / or user interface circuitry comprising the processor may be configured to control one or more functions of one or more elements of the user interface through computer program instructions, e.g., software and / or firmware, stored in, for example, volatile memory, non-volatile memory, and / or the like, accessible to the processor. Communications device 200 may also include a battery for powering various circuitry associated with a mobile terminal, such as a circuit that provides mechanical vibration as a detectable output. The user input interface may include devices that allow communication device 200 to receive data, such as a keypad (e.g., keypad 206) and / or other input devices. The keypad can be a virtual keyboard presented on a display or an externally coupled keyboard.

[0087] Communication device 200 may also include one or more mechanisms for sharing and / or obtaining data. For example, communication device 200 may include a short-range radio frequency (RF) transceiver and / or interrogator, so that data may be shared with and / or obtained from electronic devices according to RF techniques. Communication device 200 may also include other short-range transceivers, such as an infrared (IR) transceiver, a Bluetooth™ (BT) transceiver operating using Bluetooth™ wireless technology, a wireless universal serial bus (USB) transceiver, a Bluetooth™ low energy transceiver, a ZigBee transceiver, an ANT transceiver, a cellular device-to-device transceiver, a wireless local area link transceiver, and / or any other short-range wireless technology. Communication device 200, and more specifically, the short-range transceiver, may be capable of transmitting data to and / or receiving data from electronic devices within the vicinity of the device, e.g., within 10 meters. The communication device 200, which includes a Wi-Fi or wireless local area networking modem, may also be capable of transmitting data to and / or receiving data from electronic devices according to various wireless networking techniques, including WLAN techniques such as 6LoWpan, Wi-Fi, Wi-Fi low power, IEEE 802.11 techniques, IEEE 802.15 techniques, IEEE 802.16 techniques, and / or the like.

[0088] Communication device 200 may include memory, such as one or more subscriber identity modules (SIMs), one or more universal subscriber identity modules (USIMs), one or more removable user identity modules (R-UIMs), one or more eUICCs, one or more UICCs, and / or the like, that can store information elements related to mobile subscribers. In addition, communication device 200 may include other removable and / or fixed memory. Communication device 200 may include volatile and / or nonvolatile memory. For example, volatile memory may include random access memory (RAM), including dynamic RAM and / or static RAM, on-chip or off-chip cache memory, and / or the like. Non-volatile memory may be embedded and / or removable and may include, for example, read-only memory, flash memory, magnetic storage devices, such as hard disks, floppy disk drives, magnetic tapes, optical disk drives and / or optical media, non-volatile random access memory (NVRAM), and / or the like. Like volatile memory, non-volatile memory may include a cache area for temporarily storing data. At least a portion of the volatile and / or non-volatile memory may be embedded in the processor. The memory may store one or more software programs, instructions, information, data, and / or the like that may be used by the device to perform the operations disclosed herein.

[0089] The memory may include an identifier, such as an International Mobile Equipment Identification (IMEI) code, that can uniquely identify communication device 200. The memory may include an identifier, such as an International Mobile Equipment Identification (IMEI) code, that can uniquely identify communication device 200. In an exemplary embodiment, the processor may be configured to use computer code stored in the memory to cause the processor to perform the operations disclosed herein.

[0090] Some of the embodiments disclosed herein may be implemented in software, hardware, application logic, or a combination of software, hardware, and application logic. The software, application logic, and / or hardware may reside on, for example, a memory, a processor, or an electronic component. In some exemplary embodiments, the application logic, software, or instruction set is maintained on any of a variety of conventional computer-readable media. In the context of this document, a "computer-readable medium" may be any non-transitory medium that can contain, store, communicate, propagate, or transmit instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer or data processor circuitry; in the example depicted in FIG. 2, the computer-readable medium may include a non-transitory computer-readable storage medium, which may be any medium that can contain or store instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer.

[0091] In some embodiments, communications device 200 (i.e., user equipment (UE) in a network) comprises a processor (e.g., at least one data processing entity 201) and a memory (e.g., at least one memory 202). The memory includes computer program code that causes communications device 200 to process according to the methods described below with reference to FIG.

[0092] FIG. 3 illustrates an exemplary embodiment of a controller of a communications system for coupling to and / or controlling a core network function, e.g., AMF / SMF. Further examples of a controller may be coupled to and / or for controlling a station of an access system, e.g., a base station, eNB, or gNB, or a relay or core network node, e.g., MME, S-GW, or P-GW, a core network function, e.g., AMF / SMF, or a RAN node, e.g., a server or host. The method may be implanted within a single controller or across two or more controllers. The controller may be integrated with or external to a core network or RAN node or module. In some embodiments, a base station comprises a separate controller unit or module. In other embodiments, the controller may be another network element, e.g., a radio network controller or spectrum controller. In some embodiments, each base station may have such a controller, as well as a controller provided within a radio network controller. The controller 300 may be configured to provide control of communications within a coverage area of ​​the system. The control device 300 comprises at least one memory 301, at least one data processing unit 302, 303 and an input / output interface 304. The control device may be connected via an interface to a receiver and a transmitter of a base station. The receiver and / or the transmitter may be realized as a radio front end or a remote radio head.

[0093] Generally, the controller 300 has an antenna for transmitting and receiving radio signals. A radio frequency (RF) transceiver module coupled to the antenna receives RF signals from the antenna, converts them to baseband signals, and sends them to a processor (e.g., at least one data processing unit 302, 303). The RF transceiver also converts baseband signals received from the processor to RF signals and sends them to the antenna. The processor processes the received baseband signals and invokes various functional modules to perform functions within the controller 300. A memory (e.g., at least one memory 301) stores program instructions and data for controlling the operation of the controller 300. In the example of FIG. 3, the controller 300 also includes a protocol stack and a set of control functional modules and circuits. A PDU session handling circuit handles PDU session establishment and modification procedures. A policy control module configures policy rules for the UE. A configuration and control circuit provides various parameters for configuring and controlling the UE for related functions, including mobility management and session management. Suitable processors include, by way of example, special purpose processors, digital signal processors (DSPs), multiple microprocessors, one or more microprocessors associated with a DSP core, controllers, microcontrollers, application specific integrated circuits (ASICs), field programmable gate array (FPGA) circuits, and other types of integrated circuits (ICs), and / or state machines.

[0094] In some embodiments, the controller 300 (i.e., base station or wireless transmitting and / or receiving point equipment) comprises a processor (e.g., at least one data processing unit 302, 303) and a memory (e.g., at least one memory 301). The memory includes computer program code that causes the controller 300 to process according to the methods described further below with reference to FIG.

[0095] 4 shows a schematic diagram of an exemplary communication system 400. The system includes a terminal device (e.g., user equipment) 410 that communicates with an access point 420 via a first interface Y1. The access point 420 communicates with a gateway function 430 (e.g., a Non-3GPP Inter-Working Function, N3IWF) via a second interface Y2. The gateway function 430 communicates with core network functions. In particular, it communicates with an Access and Mobility Management Function (AMF) 440 via a third interface N2. The gateway function 430 further communicates with a User Plane Function (UPF) 450. The gateway function 430 provides access to the core network for the terminal device 410 via the access point 420.

[0096] 4 shows a gateway function 430 in the form of an N3IWF that provides non-trusted access. Other non-limiting examples of gateway functions include a trusted non-3GPP gateway function, TNGF.

[0097] 5 shows a diagram of a communication flow between a terminal device and a network device according to one embodiment. In this example, user equipment (UE) communication is shown via one candidate gateway function to a non-3GPP access point (trusted or non-trusted) and a core network function, which determines whether access to the core network via the candidate gateway function is permitted or denied, and in the case of denial, indicates the reason for the denial.

[0098] In step 1a, the UE connects to a non-3GPP access point using an authentication procedure, which typically results in an IP address being assigned.

[0099] In step 1b, for the UE to attach to the 5G network, the UE selects an N3IWF (for non-trusted access) or a TNGF (for trusted access) in the 5G public land mobile network (PLMN). Details of the N3IFW selection are described in clause 6.3.6 of TS 23.501.

[0100] In steps 2-5, the UE proceeds to establish an IPsec Security Association (SA) with the selected TNGF or N3IWF. Additionally or alternatively, it initiates an IKE_AUTH authentication procedure (according to the defined specifications of the selected TNGF or N3IWF).

[0101] In step 6, the TNGF or N3IWF selects an AMF based on the received access point parameters and local policies as specified in clause 6.3.5 of 3GPP TS 23.501. The TNGF or N3IWF should then forward the Registration Request received from the UE to the selected AMF in an N2 message.

[0102] In steps 7 and 8, the AMF may verify the identity and authentication of the UE using the authentication server function AUSF.

[0103] Thus, the core network function receives a request from the terminal device via the gateway function, where the request includes an authentication request.

[0104] In the illustrated example, a core network function (AMF) obtains gateway slicing information for an N3IWF, which indicates the slices supported by that N3IWF. Additionally, the AMF retrieves terminal slicing information, which indicates the slices required by the terminal device. Based on the overlap between the gateway slicing information and the terminal slicing information, the AMF can determine a subset of the (requested) slices that are indicated as supported (or rejected).

[0105] For example, the AMF obtains slicing subscription information from the Unified Data Management (UDM) and obtains the permitted / rejected NSSAI from the Network Slice Selection Function (NSSF). The slicing information may be indicated by the Network Slice Selection Assistance Information (NSSAI).

[0106] The AMF then determines that the TNGF or N3IWF selected by the UE does not support the slicing requirements. In step 9, the AMF rejects the UE's registration. It conveys the reason for the rejection (e.g., "Slice inappropriate / invalid TNGF selected" or "Slice inappropriate / invalid N3IWF selected") by an Extensible Authentication Protocol (EAP) message in a Registration Reject. The UE can then resume discovery and selection of another TNGF or N3IWF. The request response includes an authentication response.

[0107] In some embodiments, the AMF may convey information indicating another suitable TNGF or N3IWF that may satisfy the NSSAI needs of the UE, i.e., terminal slicing information. The UE may then directly connect to the provided TNGF or N3IWF.

[0108] In summary, the gateway function (TNGF or N3IWF) selects a core network function (AMF) to proceed with UE registration to 5GS. The AMF receives the allowed / rejected NSSAI for the UE (from the network slice selection function NSSF). It also knows the S-NSSAIs supported by the TNGF or N3IWF and can therefore determine whether the UE's initial TNGF or N3IWF selection was inappropriate in terms of slicing requirements. The registration is rejected, and the AMF can insert an indication of the reason for the rejection (e.g., a reason code) to indicate to the UE that the selected TNGF / N3IWF does not meet the terminal's slicing requirements.

[0109] In addition to this information, the AMF may also suggest one or more suitable alternative TNGF / N3IWFs to which the UE can connect (or search for).

[0110] The UE may restart the TNGF / N3IWF discovery and selection procedure, or if the AMF proposes any TNGF / N3IWF, the UE may directly select the TNGF / N3IWF provided by the AMF.

[0111] 6 shows a diagram of communication flow between elements according to another embodiment. In this example, user equipment (UE) communication is directed to one candidate gateway function for accessing the core network via a non-3GPP access point (trusted or non-trusted), and the candidate gateway function decides whether access to the core network via the candidate gateway function is permitted or denied, and in the case of denial, indicates the reason for the denial.

[0112] In step 1a, the UE connects to a non-3GPP access point using an authentication procedure, which typically results in an IP address being assigned.

[0113] In step 1b, for the UE to attach to the 5GC network, the UE selects a candidate gateway function in the 5G PLMN, for example, the N3IWF, as described in clause 6.3.6 of TS 23.501. Alternatively, for trusted access, the TNGF can be selected.

[0114] In steps 2 and 3, the UE proceeds to establish an IPsec Security Association (SA) with the selected N3IWF (or TNGF), specifically, it can initiate an IKE_AUTH authentication procedure (according to the defined specification for that TNGF or N3IWF).

[0115] In step 4, an EAP / Signaling request is sent from the N3IWF (or TNGF) to the UE.

[0116] In step 5, the UE replies with an EAP Response to the TNGF / N3IWF. In response, the UE may send the requested NSSAI to the TNGF / N3IWF, depending on the operator's policy on NSSAI inclusion in the AS (3GPP TS 23.501, section 5.15.9). Alternatively, the requested NSSAI may be provided via another L2 message (secure transaction).

[0117] In step 6, based on the requested NSSAI information (S-NSSAI list), the TNGF / N3IWF can determine that it cannot support any of the S-NSSAIs requested by the UE, in which case it simply "REJECTs" the UE's request with a reason code indicating that the S-NSSAIs are not appropriate for the slices the UE wants to use.

[0118] The UE then initiates another discovery and selection of another TNGF / N3IWF.

[0119] In summary, this embodiment provides a UE that exposes a list of S-NSSAIs that it wants to use (during TNGF / N3IWF selection), and the TNGF / N3IWF can simply reject the UE request when it finds that the TNGF / N3IWF does not support the requested S-NSSAIs.

[0120] This reduces signaling procedures and therefore contributes to efficiency. The UE can reselect the TNGF / N3IWF even before starting any AMF connection. Reselection can be triggered based on a requested but not allowed NSSAI.

[0121] 7 shows a flow diagram of a method 700 according to one aspect. The method 700 is for operating a terminal device in a communication network having a core network and an access point. An example of the network includes a 3GPP core network, such as a 5GC network. An example of the access point includes a non-3GPP access point. An example of a gateway function includes a trusted non-3GPP access function or a non-trusted non-3GPP access function, such as a trusted non-3GPP gateway function (TNGF) or a non-3GPP interworking function (N3IWF), respectively. An example of a core network function includes an access and mobility management function (AMF).

[0122] The method 700 includes (at step 710) determining one or more candidate gateway functions for accessing a core network via an access point.

[0123] The method 700 further includes (at step 720) sending, to one or more candidate gateway functions or to a core network function, a request for use of the one or more gateway functions to access the core network. The request may indicate, for example, a set of one or more slices for use by the terminal device, as determined by the user device. The slices may be identified by corresponding Single Network Slice Selection Assistance Information (S-NSSAI).

[0124] Method 700 further includes receiving (at step 730) a request response for each candidate gateway function from the gateway function or from the core network function. The request response is configured to indicate whether access to the core network via the respective gateway function is denied, and, if so, a reason for the denial. For example, the reason for the denial may include that the gateway function does not support one or more of the indicated slices. For example, the request response may indicate a subset of the determined set of slices, for which access via the respective gateway function is denied (or allowed).

[0125] Steps 720 and 730 may be repeated for each of the candidate gateway functions, and such iterations may occur in parallel or successively with one another.

[0126] 8 shows a flow diagram of a method 800 for operating a network device in a communication network. The communication network includes a core network and an access point.

[0127] As mentioned above, an example of a network includes a 3GPP core network such as a 5GC network. An example of an access point includes a non-3GPP access point. An example of a gateway function includes a trusted non-3GPP access function or a non-trusted non-3GPP access function, such as a trusted non-3GPP gateway function (TNGF) or a non-3GPP interworking function (N3IWF), respectively. An example of a core network function includes an access and mobility management function (AMF).

[0128] The method 800 includes (at step 810) receiving a request for use of a gateway function by a terminal device in accessing a core network via an access point. The request may indicate, for example, a set of one or more slices for use by the terminal device, as determined by the user device. The slices may be identified by corresponding single network slice selection assistance information (S-NSSAI).

[0129] In some examples, method 800 may include an optional step 820 (shown in dotted lines) of determining a subset of the indicated set of slices to which access is denied (or allowed). Determining the subset includes obtaining gateway slicing information for the requested gateway function and retrieving terminal slicing information from the received request based on the indicated set of one or more slices: the subset of slices is determined based on the overlap between the gateway slicing information and the terminal slicing information.

[0130] The method 800 further includes (at step 830) sending a request response to the terminal device configured to indicate whether access to the core network via the gateway function is denied, and, in the case of denial, to indicate a reason for the denial. For example, the reason for the denial may include that the gateway function does not support one or more of the indicated slices.

[0131] If optional step 820 is performed, the request response may indicate a subset of slices of the determined set, for which access via the respective gateway function is denied (or allowed).

[0132] 9 shows a diagram of a communication flow between a terminal device and a network device according to another embodiment. In this example, multiple candidate gateway functions are contacted by the UE. A request is sent to the 5GC, which decides how to respond to the request, including determining the reason for the rejection.

[0133] The communication flow begins with steps 1-6, which correspond to steps 1-6 defined in clause 6.13.2.1 of 3GPP TR 23700-17:

[0134] In step 1, the UE performs discovery of candidate N3IWFs in accordance with clause 6.3.6 of 3GPP TS 23.501 (Rel-17), including PLMN selection (possibly taking into account the need to select an N3IWF in the home country), selection between N3IWFs and EPDGs, and up to the point where the UE receives the IP addresses of the candidate N3IWFs from the DNS; using the S-NAPTR DNS procedure, the UE can discover which N3IWFs support the Slice Support Get request procedure based on dedicated S-NAPTR "Service Parameter" (equivalent to "x-3gpp-sgw:x-s5-gtp" defined in 3GPP TS 29.303).

[0135] In step 2, the UE sends a Slice Support Get request to the first candidate N3IWF. The Slice Support Get request can optionally include a set of slices (S-NSSAI) that the UE wants to use (indicating to the N3IWF that it does not need to reply with slices outside of this set).

[0136] In step 3, the (first) N3IWF sends a Slice Support Get response containing the set of slices (S-NSSAI) that the N3IWF supports. This set of slices (S-NSSAI) is restricted to include only a subset of the set of slices (S-NSSAI) that the UE indicated in the Slice Support Get request. It may also include caching information that tells the UE how long the UE should consider this information valid.

[0137] In steps 4 and 5, steps 2 and 3 are repeated for the second candidate N3IWF.

[0138] The Slice Support Get service can be designed as an (HTTPs) API exposed by the N3IWF to the UE and is defined by 3GPP. A Transport Layer Security (TLS) connection can be used between the UE and the N3IWF for steps 2 to 5. The Slice Support Get service is not meant to change the state of the N3IWF (since the UE only gets information). The N3IWF is assumed to provide a server certificate and is performed over IKE in the R17 specification.

[0139] In step 6, the UE selects an N3IWF to contact to access 5GC based on the information received from the N3IWF in the Slice Support Get response. In this case, the request includes an authentication request, and the UE sends the authentication request to the core network function via the selected gateway function.

[0140] Thus, steps 1-6 correspond to the respective steps defined in clause 6.13.2.1 of 3GPP TR 23700-17:

[0141] In step 7, the UE connects to the 5GC on the selected N3IWF, here the first candidate (N3IWF1), per 3GPP 23.502 (Rel-17), clause 4.12.2.2 steps 2-7. It should be noted that in this embodiment (selecting the preferred gateway function before initiating registration with the core network function), the computationally intensive Internet Key Exchange Security Association Initialization (IKE_SA_Init) procedure is performed only once, thereby reducing computational requirements.

[0142] It should also be noted that since the UE contacts the N3IWF based on currently configured information, it is possible to select the N3IWF based on the tracking area.

[0143] In step 8, the AMF can verify the identity and authentication of the UE using the AUSF. The AMF obtains slicing subscription information from the UDM and the allowed / rejected NSSAI from the NSSF. The AMF determines that the N3IWF selected by the UE does not support the slicing requirements.

[0144] In step 9, the AMF rejects the UE's registration. The Registration Reject carries a dedicated reason. Examples of such indications of the reason for the rejection include "the selected N3IWF does not match the allowed NSSAI." Additionally, the AMF may optionally provide information (FQDN or IP address) about another suitable alternative N3IWF that may satisfy the UE's NSSAI needs. The indication of the alternative N3IWF is denoted as "alt_N3IWF" in Figure 9.

[0145] Thus, in step 9, the UE receives a request response from the core network function in response to the request sent to the core network function, the request response being configured to indicate whether connection access to the core network via the respective gateway function has been denied and, in case of denial, the reason for the denial.

[0146] In step 10, the UE may resume discovery and selection of another / alternative N3IWF based on the information received from the AMF.

[0147] It should be understood that the apparatus may comprise or be coupled to other units or modules, such as radio components or radio heads, used in or for transmitting and / or receiving. Although the apparatus is described as one entity, the different modules and memories may be realized in one or more physical or logical entities.

[0148] It should be noted that although the embodiments are described in the context of LTE and 5G NR, similar principles may be applied with respect to other networks and communication systems in which fast connection re-establishment is desired to be implemented. Thus, although particular embodiments are described above by way of example with reference to particular exemplary architectures of wireless networks, technologies and standards, the embodiments may be applied to any other suitable form of communication system other than those shown and described herein.

[0149] Also, it should be noted that although the above describes exemplary embodiments herein, there are several changes and modifications that can be made to the disclosed solutions without departing from the scope of the present disclosure.

[0150] In general, various exemplary embodiments may be implemented in hardware or special-purpose circuits, software, logic, or any combination thereof. Some aspects of the present disclosure may be implemented in hardware, and other aspects may be implemented in firmware or software that may be executed by a controller, microprocessor, or other computing device, although the present disclosure is not limited thereto. Although various aspects of the present disclosure may be illustrated and described as block diagrams, flow diagrams, or using some other graphical representation, it is well understood that these blocks, apparatuses, systems, techniques, or methods described herein may be implemented in, by way of non-limiting examples, hardware, software, firmware, special-purpose circuits or logic, general-purpose hardware or controller, or other computing device, or combinations thereof.

[0151] Exemplary embodiments of the present disclosure may be implemented by computer software executable by a data processor of a mobile device, such as in a processor entity, or by hardware, or a combination of software and hardware. Computer software or programs, also referred to as program products, including software routines, applets, and / or macros, may be stored on any device-readable data storage medium and include program instructions for performing specific tasks. A computer program product may include one or more computer-executable components configured to perform embodiments when the program is executed. The one or more computer-executable components may be at least one software code or portion thereof.

[0152] Further, in this regard, it should be noted that any block of logic flow as shown in the figures may represent program steps or interconnected logic circuits, blocks, and functions, or a combination of program steps, logic circuits, blocks, and functions. Software may be stored on physical media, such as memory chips or blocks of memory implemented within a processor, magnetic media such as hard disks or floppy disks, and optical media, e.g., DVDs and their data variants, CDs, etc. Physical media are non-transitory media.

[0153] The memory may be any type of memory suitable for the local technology environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and removable memory. The data processor may be any type of data processor suitable for the local technology environment and may include, by way of non-limiting examples, one or more of a general purpose computer, a special purpose computer, a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), an FPGA, a gate-level circuit, and a processor based on a multi-core processor architecture.

[0154] Exemplary embodiments of the present disclosure may be practiced in a variety of components, such as integrated circuit modules. Integrated circuit design is generally a highly automated process. Complex and powerful software tools are available to convert logic-level designs into semiconductor circuit designs ready to be etched and formed on semiconductor substrates.

[0155] The above description provides a complete and informative description of exemplary embodiments of the present disclosure, by way of non-limiting example. However, various modifications and adaptations will become apparent to those skilled in the art in light of the above description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings of the present invention will still fall within the scope of the present disclosure, as defined by the appended claims. In fact, further embodiments exist that include combinations of one or more of the embodiments with any of the other embodiments described above.

Claims

1. 1. A method of operating a terminal device, comprising: selecting a candidate gateway function for accessing a core network via an access point; sending a request for use of a candidate gateway function to a candidate gateway function or to a network function of a core network; receiving a response to the request from the candidate gateway function or from a network function of the core network, the response including an indication that access to the core network via the candidate gateway function has been denied and an indication of a reason for the denial of the request, the indication of the reason for the denial indicating non-support of one or more network slices by the candidate gateway function; A method comprising:

2. 2. The method of claim 1, wherein the candidate gateway functions include a Non-3GPP Interworking Function (N3IWF) or a Trusted Non-3GPP Gateway Function (TNGF).

3. 3. The method of claim 1, further comprising determining a set of one or more network slices for use by the terminal device, wherein the request includes an identifier of the set of one or more network slices.

4. 4. The method of claim 3, wherein each network slice of the one or more network slices is identified by a corresponding single network slice assistance information (S-NSSAI).

5. The method of claim 3 or 4, wherein the response includes an identifier of a subset of network slices of the determined set of one or more network slices for use by the terminal device.

6. The method of claim 1 , wherein the request comprises a registration request and the response comprises a registration response.

7. The method of claim 1 , wherein the request comprises an authentication request and the response comprises an authentication response.

8. The method of claim 1 , wherein the network functions of the core network include an Access and Mobility Management Function (AMF).

9. receiving, by the network device, a request for use of a gateway function to access a core network via an access point of the communications network; sending, by the network device, a response to the request, the response including an indication that use of the gateway function by the terminal device to access the core network via the gateway function has been denied and an indication of a reason for the denial of the request, the indication of the reason for the denial indicating non-support of one or more network slices by the candidate gateway function; A method comprising:

10. 10. The method of claim 9, wherein the gateway function comprises a Non-3GPP Interworking Function (N3IWF) or a Trusted Non-3GPP Gateway Function (TNGF).

11. The method of claim 9 or 10, wherein the request includes an identifier of a set of one or more network slices for use by the terminal device.

12. 12. The method of claim 11, wherein each network slice of the one or more network slices is identified by a corresponding single network slice selection assistance information (S-NSSAI).

13. 13. The method of claim 11 or 12, further comprising determining a subset of network slices of the set of one or more network slices for use by the terminal device, wherein the response includes an identifier of the determined subset.

14. Determining the subset Obtaining gateway slicing information by a network device for a gateway function; retrieving, by the network device, terminal slicing information based on the identifiers of the set of one or more network slices; determining, by the network device, a subset of network slices based on an overlap between the gateway slicing information and the terminal slicing information; 14. The method of claim 13, comprising:

15. 15. The method of claim 14, further comprising, in response to determining that the overlap is a true subset of the indicated set, identifying an alternate gateway function based on the terminal slicing information, wherein the request response is configured to indicate the alternate gateway function.

16. 16. The method of claim 9, wherein the network device includes a gateway function.

17. Sending, by the network device, an authentication request to an Access and Mobility Management Function (AMF) for authenticating the terminal device; receiving, by the network device, from the AMF, an authentication response including an indication of a reason for the rejection; including an indication of the reason for the rejection in the response sent to the terminal device; 17. The method of claim 16, further comprising:

18. 14. The method of claim 9, wherein the network device comprises a network function of a core network.

19. 20. The method of claim 17, wherein the request comprises a registration request and the response comprises a registration response.

20. 20. The method of claim 17, wherein the request comprises an authentication request and the response comprises an authentication response.

21. 21. The method of claim 18, wherein the network functions of the core network include an Access and Mobility Management Function (AMF).

22. 1. A terminal device for use in a communications network including a core network and an access point, comprising: at least one processor; and at least one memory containing computer program code which, when executed by the at least one processor, causes the terminal device to perform the method of any one of claims 1 to 8. Terminal device.

23. 1. A network device for a communication network including a core network and an access point, comprising: at least one processor; and at least one memory containing computer program code which, when executed by the at least one processor, causes the network device to perform the method of any one of claims 9 to 21. Network devices.

24. A non-transitory computer-readable medium comprising computer-executable instructions that, when executed by at least one processor of a terminal device, cause the terminal device to perform the method of any one of claims 1 to 8.

25. 22. A non-transitory computer-readable medium comprising computer-executable instructions that, when executed by at least one processor of a network device, cause the network device to perform the method of any one of claims 9 to 21.

26. A computer program comprising computer executable instructions which, when the program is executed by a terminal device, cause the terminal device to perform the method of any one of claims 1 to 8.

27. 22. A computer program comprising computer executable instructions which, when the program is executed by a network device, cause the terminal device to perform the method of any one of claims 9 to 21.

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