Methods, devices, and memory media for slice support plmn selection while roaming away from home network

Abstract

A user equipment (UE) can receive a list of public land mobile networks (PLMNs) that support a given network slice in a given country, which is different from a home country of a home PLMN of the UE. When roaming in the given country, the UE can access a PLMN in the list if the given network slice is desired. The list can be provided by the home PLMN when the UE is in the home country; or the list can be provided via a visited PLMN when the UE is in the given country. The list can be received in response to a UE-initiated request, or pushed to the UE by the home PLMN. A validity timer period received with the list can indicate a duration of validity of the list. In an alternative scenario, the UE can receive the list from an authority server, e.g., an authority server belonging to a visited PLMN.

Description

TECHNICAL FIELD

[0001] This application relates to wireless communications, and more specifically, to mechanisms that enable a wireless device to perform improved slice support network selection while roaming away from a home network. BACKGROUND

[0002] The use of wireless communication systems is rapidly increasing. In addition, there are numerous different wireless communication technologies and wireless communication standards. Some examples of wireless communication standards include GSM, UMTS (e.g., associated with a WCDMA air interface or a TD-SCDMA air interface), LTE, LTE-Advanced (LTE-A), 3GPP2 CDMA2000 (e.g., lxRTT, lxEV-DO, HRPD, eHRPD), IEEE 802.11 (WLAN or Wi-Fi), IEEE 802.16 (WiMAX), Bluetooth, etc.

[0003] To perform cellular communications, a user equipment (UE) typically first selects and registers with a public land mobile network (PLMN), which will then provide cellular communications services to the UE. A PLMN is a land-based network provided by a particular operator in a particular country. For example, a PLMN in a given country can support a combination of cellular technologies, such as GSM / 2G, UMTS / 3G, and LTE / 4G.

[0004] A PLMN can support multiple network slices, e.g., logical (or virtual) end-to-end networks. Each network slice can provide a different set of functions and services. Different UEs can need or desire to access different network slices, or different sets of network slices. For example, a smart phone and a household electric meter can need to access different sets of network slices. Or a given UE can need to access different slices when reading email and when conducting a phone conversation. Each slice is uniquely identified by a corresponding S-NSSAI value. (S-NSSAI is an acronym for "Single-Network Slice Selection Assistance Information.")

[0005] When a UE is camped on its home PLMN, the UE can easily access any network slice supported by the home PLMN. However, in roaming scenarios, successful selection of and registration with a PLMN that supports a desired network slice can pose time-consuming and power-consuming challenges, because the UE can not know which PLMNs in a foreign country will support the network slice. The UE can need to repeatedly attempt to register with different PLMNs until a suitable PLMN is found. Thus, improvements in this area would be desirable.

[0006] One issue with providing network slices in 3GPP 5G is how to handle the impact of the so-called "service area" on PLMN selection when roaming far from the home PLMN. The home PLMN of a UE device is the PLMN to which the UE device (or the user identity module of the UE device) is subscribed.

[0007] One of the attributes in the Generic Network Slice Template (GST) as documented in GSMA 5G JA NG.116 is the service area. (GSM is an acronym for Global System for Mobiles. GSMA is an acronym for GSM Association. 5G JA is an acronym for 5G Joint Activity. NG is an acronym for Network Group.) This attribute specifies the areas in which a terminal (UE device) can access a given network slice. In other words, this attribute specifies a list of countries in which the service defined by a given network slice will be provided. This list is specific to the Network Slice Provider (NSP) and its roaming agreements.

[0008] If this list includes more than one country, a roaming agreement between the home PLMN (HPLMN) and the visited PLMN (VPLMN) is needed.

[0009] If the S-NSSAI of the HPLMN is only usable with specific PLMNs in the country in which the UE is roaming, the UE should perform a selection of one of these specific PLMNs before the S-NSSAI of the HPLMN can be used. (S-NSSAI can be interpreted as an identifier of a network slice. Thus, this patent can refer to the use of S-NSSAI as shorthand for using the network slice identified by the S-NSSAI.) The preferred PLMNs in the visited country can not necessarily be able to provide all possible network slices that the HPLMN has committed to its customers. Furthermore, the PLMNs in the list of preferred PLMNs can not necessarily be able to provide ubiquitous 5GS coverage in the visited country. Thus, the UE device can have to use non-preferred PLMNs in certain areas, and not all of these PLMNs can support the network slice expected by the UE device that is subscribed to the HPLMN.

[0010] Now, a roaming UE device will have to select a priority PLMN from a subscriber identity module (SIM) file or via an internally prioritized list of PLMNs without knowing whether the PLMN supports the desired S-NSSAI of the HPLMN, e.g., until (a) the S-NSSAI is indicated as allowed in the PLMN (e.g., in a registration accept message), or (b) the configured NSSAI of the PLMN is provided. (The "allowed" of an S-NSSAI can be much later than the registration procedure when the network slice is undergoing slice-specific authentication and authorization. In such cases, the UE can be informed whether the slice is allowed or rejected via a UE configuration update command.) The UE device can need to make repeated registration attempts to discover a PLMN that supports the desired S-NSSAI, thus wasting time and power, and causing disruption in the roaming service of the end user. SUMMARY

[0011] Various mechanisms are disclosed herein that allow a UE to perform S-NSSAI-aware PLMN selection.

[0012] In one set of embodiments, a method for operating a user equipment (UE) can include the following operations.

[0013] The method can include receiving a list of one or more public land mobile networks (PLMNs) that support a given network slice in a given country, where the given country is different from a home country of a home PLMN of the UE, where the given network slice is supported in the home PLMN.

[0014] The method can further include, in response to determining that the UE is located in the given country and desires access to the given network slice, accessing (or prioritizing access to) a PLMN of the list to use the given network slice.

[0015] In some embodiments, the processing element can transmit a registration request (or other message) to the home PLMN, e.g., when the UE is in the home country or when the UE is in the given country, where the list is received from the home PLMN after the registration request has been transmitted.

[0016] In some embodiments, the registration request can have an identification of one or more roaming countries including the given country.

[0017] In some embodiments, while the UE is in a given country, the processing element can send a registration request (or other message) to a roaming PLMN in the given country, the registration request including an identification of a second country different from the home country and different from the given country. The roaming PLMN can contact the home PLMN to obtain a list of one or more PLMNs that support the given network slice in the second country, and forward the list to the UE. The processing element can receive the list. The registration request (or other message) including the identification of the second country can be sent while the UE is in the given country (e.g., in anticipation of entering the second country in the future).

[0018] In some embodiments, the registration request can include one or more of: (a) a requested single network slice selection assistance information (S-NSSAI) value associated with the given network slice, where the requested S-NSSAI value includes an information element indicating whether the list of one or more PLMNs is requested; and (b) an identification of one or more roaming countries of the given country.

[0019] In some embodiments, the list can be received along with a validity timer period indicating a length of time for which the list is guaranteed to be valid.

[0020] In some embodiments, the processing element can receive a validity timer period indicating a time period after which the one or more PLMNs in the list will no longer support the given slice.

[0021] In some embodiments, the processing element can receive the list when: (a) the UE is associated with (e.g., camped on or connected to) the home PLMN in the home country; and (b) the UE has not made any request for the list.

[0022] In some embodiments, the processing element can receive the list from the home PLMN via: (a) a visited PLMN of the given country, or (b) a WiFi access point in the given country, or (c) a satellite-based internet connection in the given country.

[0023] In some embodiments, the processing element can send a retrieval request to an authority server while roaming in the given country, where the retrieval request includes an indication of a location of the UE and an identification of the given network slice, where the list is received after the retrieval request has been sent.

[0024] In some embodiments, the processing element can be configured to prioritize one or more PLMNs in the list for PLMN selection over preferred PLMNs (e.g., user preferred PLMNs and operator preferred PLMNs).

[0025] In some embodiments, the processing element can be configured to receive an updated list of one or more PLMNs that support the given network slice in the given country.

[0026] In some embodiments, the non-transitory memory medium can include program instructions executable by the UE that, when executed, cause the UE to perform at least a portion or all of the operations described above.

[0027] The techniques described herein can be implemented in and / or used with a number of different types of devices, including, but not limited to, cellular phones, tablet computers, wearable computing devices, portable media players, and any of various other computing devices.

[0028] This Summary is intended to provide a brief overview of some of the subject matter described in this document. Accordingly, it will be appreciated that the above-described features are merely examples and should not be construed to narrow the scope or spirit of the subject matter as described herein. Other features, aspects, and advantages of the subject matter described herein will become apparent from the following DETAILED DESCRIPTION, Figures, and Claims. BRIEF DESCRIPTION OF DRAWINGS

[0029] A better understanding of the present subject matter can be obtained when the following detailed description of various embodiments is considered in conjunction with the following drawings, in which:

[0030] Figure 1 An example wireless communication system is shown in accordance with some embodiments;

[0031] Figure 2 A base station (BS) in communication with a user equipment (UE) device is shown in accordance with some embodiments;

[0032] Figure 3 An example block diagram of a UE is shown in accordance with some embodiments;

[0033] Figure 4 An example block diagram of a BS is shown in accordance with some embodiments.

[0034] Figure 5 An example of a length indicator field in an S-NSSAI is shown in accordance with some embodiments.

[0035] Figure 6 An example of a transfer of an S-NSSAI roaming protocol initiated by a UE while in a home PLMN is shown in accordance with some embodiments.

[0036] Figure 7An example of transmission of a (and UE initiated) S-NSSAI roaming agreement selective when the UE is in the HPLMN is shown in accordance with some embodiments.

[0037] Figure 8 An example of transmission of a network initiated S-NSSAI roaming agreement when the UE is in the HPLMN is shown in accordance with some embodiments.

[0038] Figure 9 An example of using a validity timer to control or limit the validity period of the list of supported PLMNs is shown in accordance with some embodiments.

[0039] Figure 10 An example of sending a validity timer value to the UE as part of a configuration update command is shown in accordance with some embodiments.

[0040] Figure 11 An example of a mechanism for providing slice support PLMN identification information to a UE using an authority server is shown in accordance with some embodiments.

[0041] Figure 12 A method for operating a UE to access a PLMN that supports a desired network slice is shown in accordance with some embodiments.

[0042] Figure 13 A method for operating an access and mobility management function in a PLMN is shown in accordance with some embodiments.

[0043] Figure 14 A method for operating a base station is shown in accordance with some embodiments.

[0044] While the features described herein can be susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the disclosure to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the subject matter defined by the appended claims. DETAILED DESCRIPTION

[0045] Acronyms

[0046] Various acronyms are used throughout this disclosure. Definitions of the most prominent acronyms used throughout this disclosure can appear as follows:

[0047] • AMF: Access and Mobility Management Function

[0048] • BS: Base Station

[0049] • DL: Downlink

[0050] • GSM: Global System for Mobile

[0051] • GSMA: GSM Association

[0052] • HNSSF: Home NSSF

[0053] • HPLMN: Home Public Land Mobile Network

[0054] • LTE: Long Term Evolution

[0055] • NR: New Radio

[0056] • PDCCH: Physical Downlink Control Channel

[0057] • PLMN: Public Land Mobile Network

[0058] • PUSCH: Physical Uplink Shared Channel

[0059] • NSSAI: Network Slice Selection Assistance Information

[0060] • NSSF: Network Slice Selection

[0061] • RAT: Radio Access Technology

[0062] • RF: Radio Frequency

[0063] • S-NSSAI: Single Network Slice Selection Assistance Information

[0064] • SMF: Session Management Function

[0065] • UE: User Equipment

[0066] • UL: Uplink

[0067] • UMTS: Universal Mobile Telecommunications System

[0068] • VPLMN: Visited Public Land Mobile Network

[0069] Terminology

[0070] The following is a glossary of terms used in this disclosure.

[0071] Memory media—any device of any type of nontransitory memory device or storage device. The term "memory media" is intended to include mounting media such as CD-ROMs, floppy disks, or magnetic tape devices; computer system memory or random access memory such as DRAM, DDR RAM, SRAM, EDO RAM, Rambus RAM, etc.; non-volatile memory such as flash memory, magnetic media, e.g., hard disk drives or optical storage devices; registers or other similar types of memory elements, etc. Memory media may also include other types of nontransitory memory or combinations thereof. Furthermore, memory media may reside in a first computer system executing a program, or may reside in a different second computer system connected to the first computer system via a network such as the Internet. In the latter case, the second computer system may provide program instructions to the first computer for execution. The term "memory media" may include two or more memory media that may reside in different locations on different computer systems connected via a network, for example. Memory media may store program instructions (e.g., representing a computer program) that can be executed by one or more processors.

[0072] Carrier medium—the memory medium as described above, and physical transmission medium, such as buses, networks, and / or other physical transmission media for transmitting signals (such as electrical signals, electromagnetic signals, or digital signals).

[0073] Programmable hardware elements—including a variety of hardware devices comprising multiple programmable functional blocks connected via programmable interconnects. Examples include FPGAs (Field-Programmable Gate Arrays), PLDs (Programmable Logic Devices), FPOAs (Field-Programmable Object Arrays), and CPLDs (Complex PLDs). Programmable functional blocks can vary from fine-grained (combinatorial logic units or lookup tables) to coarse-grained (arithmetic logic units or processor cores). Programmable hardware elements may also be referred to as "configurable logic units."

[0074] Computer system—any of all types of computing or processing systems, including personal computer systems (PCs), mainframe computer systems, workstations, networked appliances, internet-connected appliances, personal digital assistants (PDAs), television systems, grid computing systems, or other devices or combinations thereof. In general, the term "computer system" can be broadly defined to encompass any device (or combination of devices) having at least one processor that executes instructions from a memory medium.

[0075] User equipment (UE) (or “UE device”) — any of various types of computer systems or devices that are mobile or portable and perform wireless communications. Examples of UE devices include mobile phones or smartphones (e.g., iPhone). TM Based on AndroidTM a telephone (e.g., iPhone®, cellular telephone), a portable computer (e.g., a TM PlayStation Portable TM Gameboy Advance TM iPhone TM ), a laptop computer, a wearable device (e.g., a smart watch, smart glasses), a PDA, a portable Internet device, a music player, a data storage device, or other handheld device, an unmanned aerial vehicle (UAV), an unmanned aerial vehicle controller (UAC), a vehicle, and / or the like. In general, the term "UE" or "UE device" can be broadly defined to encompass any electronic, computing, and / or

[0076] base station - the term "base station" is in the full breadth of its ordinary meaning, and at least includes a wireless communication station installed at a fixed location and used to communicate as part of a wireless telephone system or radio system.

[0077] processing element - refers to various elements or combinations of elements. Processing elements include, for example, circuitry such as, but not limited to, an ASIC (application specific integrated circuit), portions or circuits of individual processor cores, entire processor cores, individual processors, programmable hardware devices such as FPGAs (field programmable gate arrays), and / or larger portions of systems that include multiple processors.

[0078] channel - a medium used to pass information from a sender (transmiter) to a receiver. It should be noted that the characteristics of the term "channel" can differ depending on the different wireless protocols, and thus the term "channel" as used herein can be taken to be used in a manner consistent with the type of equipment to which the term is referenced to comply with standards. In some standards, the channel width can be variable (e.g., depending on device capabilities, band conditions, etc.). For example, LTE can support scalable bandwidths of 1.4MHz to 20MHz. In comparison, a WLAN channel can be 22MHz wide, while a Bluetooth channel can be 1Mhz wide. Other protocols and standards can include different definitions of a channel. Also, some standards can define and use multiple types of channels, e.g., different channels for uplink or downlink and / or different channels for different uses such as data, control information, etc.

[0079] band - the term "band" is in the full breadth of its ordinary meaning, and at least includes a segment of the frequency spectrum (e.g., radiofrequency spectrum) in which channels are used or set aside for the same purpose.

[0080] Automatic - refers to the performance of an action or operation by a computer system (e.g., software executed by a computer system) or device (e.g., circuit, programmable hardware element, ASIC, etc.) without user input directly specifying or performing the action or operation. Thus the term "automatic" as used herein in reference to action or operation of a computer system or device refers to the act of performing the action or operation without user input directly specifying or performing the action or operation. An automatic process may

[0081] Figure 1 and Figure 2 - communication system

[0082] Figure 1 A simplified exemplary wireless communication system according to one embodiment is illustrated. Note that Figure 1 The system of FIG. 1 is merely one example of a possible system, and features of the present disclosure can be implemented in any of various systems, as desired.

[0083] As shown, the exemplary wireless communication system includes a base station 102A that communicates with one or more user devices 106A, 106B through 106N, etc., over a transmission medium. Each of the user devices can be referred to herein as a "user equipment" (UE). Thus, the user devices 106 are referred to as UEs or UE devices.

[0084] The base station (BS) 102A can be a base transceiver station (BTS) or cell site ("cellular base station"), and can include hardware to enable wireless communication with the UEs 106A through 106N.

[0085] The communication area (or coverage area) of a base station can be referred to as a "cell." Base station 102A and UEs 106 can be configured to communicate

[0086] As illustrated, base station 102A can also be equipped to communicate with a network 100 (e.g., with a core network of a cellular service provider, a telecommunication network such as the Public Switched Telephone Network (PSTN), and / or the Internet, among various possibilities). Hence, base station 102A can facilitate communication between UEs and / or between UEs and the network 100. In particular, a cellular base station 102A can provide UEs 106 with various

[0087] Base stations 102A and other similar base stations (such as base stations 102B through 102N) operating according to the same or a different cellular communication standard can thus be provided as a network of cells that together can provide continuous or nearly continuous overlapping service to UEs 106A-N and similar devices throughout a wide geographic area.

[0088] Hence, while base station 102A can act as a "serving cell" for UEs 106A-N as Figure 1 illustrated in FIG. 1, each UE 106 can also be capable of receiving signals from (and possibly be within communication range of) one or more other cells (that can be provided by base stations 102B-N and / or any other base stations), which can be referred to as "neighboring cells." Such cells can also be capable of facilitating communication between user devices and / or between user devices and the network 100. Such cells can include "macro" cells, "micro" cells, "pico" cells, and / or any of various other sizes of cells providing service areas of any various granularity. For example, base stations 102A-B can be macro cells, while base station 102N can be a micro cell. Other configurations are also possible. Figure 1

[0089] ​Note that the UE 106 is capable of communicating using multiple wireless communication standards. For example, in addition to at least one cellular communication protocol (e.g., GSM, UMTS (associated with, e.g., WCDMA or TD-SCDMA air interfaces), LTE, LTE-A, NR, HSPA, 3GPP2 CDMA2000 (e.g., lxRTT, lxEV-DO, HRPD, eHRPD), etc.), the UE 106 can be configured to communicate using a wireless networking (e.g., Wi-Fi) and / or peer-to-peer wireless communication protocol (e.g., Bluetooth, Wi-Fi peer-to-peer, etc.). If desired, the UE 106 can also 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 broadcasting standards (such as ATSC-M / H or DVB-H), and / or any other wireless communication protocol. Other combinations of wireless communication standards (including more than two wireless communication standards) are also possible.

[0090] Figure 2 A user equipment 106 (e.g., one of device 106A-106N) in communication with a base station 102 in accordance with one embodiment is shown. The UE 106 can be a device with cellular communication capability such as a mobile phone, a hand-held device, a computer or a tablet computer or virtually any type of wireless device.

[0091] The UE 106 can include a processor configured to execute program instructions stored in memory. The UE 106 can perform any of the method embodiments described herein by executing such stored instructions. Alternatively, or in addition, the UE 106 can include a programmable hardware element such as an FPGA or a PLD, configured to perform any of the method embodiments described herein, or any portion of any of the method embodiments described herein.

[0092] The UE 106 can include one or more antennas to communicate using one or more wireless communication protocols or technologies. In some embodiments, the UE 106 can be configured to communicate using, for example, CDMA2000 (lxRTT / lxEV-DO / HRPD / eHRPD) or LTE using a single shared radio and / or GSM or LTE using a single shared radio. The shared radio can be coupled to a single antenna, or can be coupled to multiple antennas (e.g., for MIMO) for performing wireless communication. Generally, a radio can include any combination of a baseband processor, analog RF signal processing circuitry (e.g., including filters, mixers, oscillators, amplifiers, etc.) or digital processing circuitry (e.g., for digital modulation as well as other digital processing). Similarly, the radio can implement one or more receive and transmit chains using the aforementioned hardware. For example, the UE 106 can share one or more portions of receive and / or transmit chains between multiple wireless communication technologies such as those discussed above.

[0093] In some embodiments, the UE 106 can include separate transmit and / or receive chains (e.g., including separate antennas and other radio components) for each wireless communication protocol configured to be used for communication thereby. As another possibility, the UE 106 can include one or more radios shared between multiple wireless communication protocols, along with one or more radios used by a single wireless communication protocol exclusively. For example, the UE 106 can include a shared radio for communicating using either of LTE or NR (or LTE or lxRTT, or LTE or GSM), along with separate radios for communicating using each of Wi-Fi and Bluetooth. Other configurations are also possible.

[0094] Figure 3 - block diagram of a UE

[0095] Figure 3An example block diagram of a UE 106 is shown, in accordance with one embodiment. As shown, the UE 106 can include a system on a chip (SOC) 300, which can include portions for various purposes. For example, as shown, the SOC 300 can include a processor 302, which can execute program instructions for the UE 106, and a display circuitry 304, which can perform graphics processing and provide display signals to a display 360. The one or more processors 302 can also be coupled to memory management unit (MMU) 340, which can be configured to receive addresses from the one or more processors 302 and translate those addresses to locations in memory (e.g., memory 306, read only memory (ROM) 350, NAND flash memory 310) and / or to other circuitry or devices, such as the display circuitry 304, wireless communication circuitry 330, connector I / F 320, and / or display 360. The MMU 340 can be configured to perform memory protection and page table translation or set up. In some embodiments, the MMU 340 can be included as a portion of the processor 302.

[0096] As shown, the SOC 300 can be coupled to various other circuitries of the UE 106. For example, the UE 106 can include various types of memory including, for example, NAND flash memory 310, a connector interface 320 (e.g., for coupling to a computer system, a docking station, a charging station, etc.), a display 360, and wireless communication circuitry 330 (e.g., for LTE, LTE-A, NR, CDMA2000, Bluetooth, Wi-Fi, GPS, etc.). The UE can also include at least one SIM device, and can include two SIM devices, each providing a respective international mobile subscriber identity (IMSI) and associated functionality.

[0097] As shown, the UE device 106 can include at least one antenna (and in various possibilities, multiple antennas, for example for MIMO and / or for implementing different wireless communication technologies) for performing wireless communication with base stations, access points, and / or other devices. For example, the UE device 106 can use antenna 335 to perform wireless communication.

[0098] The UE 106 can also include and / or be configured for use with one or more user interface elements. User interface elements can include any of a variety of elements such as a display 360 (which can be a touchscreen display), a keyboard (which can be a discrete keyboard or can be implemented as part of a touchscreen display), a mouse, a microphone, and / or a speaker, one or more cameras, one or more buttons, and / or any of a variety of other elements capable of providing information to a user and / or receiving or interpreting user input.

[0099] As described herein, UE 106 may include hardware and software components for implementing functions such as those described herein for performing more efficient cellular base station scanning. The processor 302 of UE device 106 may be configured to implement some or all of the methods described herein, for example, by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium). In other embodiments, processor 302 may be configured as a programmable hardware element such as a FPGA (Field-Programmable Gate Array) or as an ASIC (Application-Specific Integrated Circuit). Alternatively (or in addition), in conjunction with one or more of other components 300, 304, 306, 310, 320, 330, 335, 340, 350, and 360, the processor 302 of UE device 106 may be configured to implement some or all of the features described herein.

[0100] Figure 4 - block diagram of a base station

[0101] Figure 4 An example block diagram of a base station 102 according to one embodiment is shown. Note that... Figure 4 The base station shown is merely one example of a possible base station. As illustrated, base station 102 may include a processor 404 capable of executing program instructions specific to base station 102. Processor 404 may also be coupled to a memory management unit (MMU) 440 or other circuitry or device, which may be configured to receive addresses from processor 404 and translate those addresses into locations in memory (e.g., memory 460 and read-only memory (ROM) 450).

[0102] Base station 102 may include at least one network port 470. Network port 470 may be configured to be coupled to a telephone network and provide access rights as described above. Figure 1 and Figure 2 The telephone network described herein includes multiple devices such as UE device 106.

[0103] Network port 470 (or an additional network port) may also be configured, or alternatively configured, to be coupled to a cellular network, such as the core network of a cellular service provider. The core network may provide mobility-related services and / or other services to multiple devices, such as UE device 106. In some cases, network port 470 may be coupled to a telephone network via the core network, and / or the core network may provide the telephone network (e.g., in other UE devices served by the cellular service provider).

[0104] The base station 102 can include at least one antenna 434, and possibly multiple antennas. The at least one antenna 434 can be configured to function as a wireless transceiver and can be further configured to communicate with UE devices 106 via the radio 430. The antenna 434 communicates with the radio 430 via a communication link 432. The communication link 432 can be a receive chain, a transmit chain, or both. The radio 430 can be configured to communicate via a variety of wireless communication standards including, but not limited to, LTE, LTE-A, NR, GSM, UMTS, CDMA2000, Wi-Fi, etc.

[0105] The base station 102 can be configured to communicate wirelessly using multiple wireless communication standards. In some cases, the base station 102 can include multiple radios that can enable the base station 102 to communicate according to multiple wireless communication technologies. For example, as one possibility, the base station 102 can include an LTE radio for performing communications according to LTE and a Wi-Fi radio for performing communications according to Wi-Fi. In such cases, the base station 102 can be capable of operating as both an LTE base station and a Wi-Fi access point. As another possibility, the base station 102 can include a multi-mode radio capable of performing communications according to any of a plurality of wireless communication technologies, such as LTE and NR, LTE and Wi-Fi, LTE and UMTS, LTE and CDMA2000, UMTS and GSM, etc.

[0106] As described further herein below, the BS 102 can include hardware and software components for implementing or supporting implementation of the features described herein. The processor 404 of the base station 102 can be configured, e.g., by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium), to implement or support implementation of part or all of the methods described herein. Alternatively, the processor 404 can be configured as a programmable hardware element, such as an FPGA (field programmable gate array), or as an ASIC (application specific integrated circuit), or combinations thereof. Alternatively (or additionally) the processor 404 of the base station 102, in conjunction with one or more of the other components 430, 432, 434, 440, 450, 460, 470, can be configured to implement or support implementation of part or all of the features described herein.

[0107] Interest area enhanced roaming PLMN selection using S-NSSAI

[0108] In some embodiments, knowledge of the “area of interest” for an S-NSSAI can be used to enhance roaming PLMN selection.

[0109] According to the prior art, when a UE is roaming in a country far from its HPLMN, the UE needs to attempt to select a visited PLMN (VPLMN) without knowing whether the PLMN supports the given mapping of S-NSSAI (e.g., S-NSSAI identifying a network slice of interest for use by the UE (or an application running on the UE)). The UE only knows this after completing a non-access stratum (NAS) registration procedure on the VPLMN. This lack of awareness can result in many redundant registration attempts to VPLMNs that do not support a given S-NSSAI.

[0110] 3GPP network slice support for roaming

[0111] Section 5.15.6 of 3rd Generation Partnership Project Technical Specification 23.501 (3GPP TS 23.501) version 16.3.0 sets forth the specification related to network slice support for roaming scenarios as follows.

[0112] Start of provisioning

[0113] If the UE only uses standard S-NSSAI values, the same S-NSSAI values can be used in the VPLMN as in the HPLMN.

[0114] If the VPLMN and the HPLMN have an SLA [Service Level Agreement] for supporting non-standard S-NSSAI values in the VPLMN, the NSSF [Network Slice Selection Function] of the VPLMN maps the subscribed S-NSSAI values to the corresponding S-NSSAI values to be used in the VPLMN. The S-NSSAI values to be used in the VPLMN are determined by the NSSF of the VPLMN based on the SLA. The NSSF of the VPLMN does not need to inform the HPLMN which values are used in the VPLMN.

[0115] According to the operator's policy and configuration in the AMF [Access and Mobility Management Function], the AMF can decide the S-NSSAI values to be used in the VPLMN and the mapping to the subscribed S-NSSAI.

[0116] If this mapping is stored in the UE, the UE constructs the requested NSSAI and provides the mapping of S-NSSAI in the requested NSSAI to the HPLMN S-NSSAI as described in clause 5.15.5.2.1 of TS 23.501.

[0117] The NSSF in the VPLMN determines the allowed NSSAI without interacting with the HPLMN.

[0118] The allowed NSSAI in the registration accept includes S-NSSAI values used in the VPLMN. The mapping information above is also provided to the UE with the allowed NSSAI as described in clause 5.15.4 of TS 23.501.

[0119] In the PDU session establishment procedure, the UE includes both of the following:

[0120] (a) S-NSSAI that matches an application within the NSSP in the URSP [UE Route Selection Policy] rule or within the UE local configuration that is triggering the PDU session request as defined in clause 6.1.2.2.1 of TS 23.503; the value of this S-NSSAI is used in the HPLMN; and

[0121] (b) S-NSSAI that belongs to the allowed NSSAI that is mapped to (a) using the mapping of allowed NSSAI to HPLMN S-NSSAI; the value of this S-NSSAI is used in the VPLMN.

[0122] For home routing case, the V-SMF [Visited Session Management Function] sends the PDU session establishment request message to the H-SMF [Home SMF] along with the S-NSSAI with the value used in the HPLMN (a).

[0123] When establishing a PDU [Protocol Data Unit] session, the CN [Core Network] provides the S-NSSAI with the value from the VPLMN corresponding to this PDU session to the AN [Access Network] as described in clause 5.15.5.3 of TS 25.501.

[0124] Network slice instance specific network functions in the VPLMN are selected by the VPLMN by using the S-NSSAI with the value used in the VPLMN and querying the NRF [Network Repository Function] that has been pre-configured or provided by the NSSF in the VPLMN. Network slice specific functions of the HPLMN, if applicable, are selected by the VPLMN via support from the appropriate NRF from the HPLMN by using the related S-NSSAI with the value used in the HPLMN as specified in clause 4.17.5 of TS 23.502 and identified for the SMF in clause 4.3.2.2.3.3 of TS 23.502.

[0125] End of provisioning

[0126] Length of S-NSSAI content

[0127] In some embodiments, an S-NSSAI (Single-Network Slice Selection Assistance Information) can include a length field and content. Depending on the value of the length field, the content can have different forms. For example, as shown in Figure 5 the length field can be an octet (i.e., a group of eight bits), with certain of the possible states of the octet corresponding to respective forms of the content. (SST stands for Slice / Service Type. SD stands for Slice Differentiator.) A first state corresponding to a hexadecimal value of 01 includes an SST; a second state corresponding to a hexadecimal value of 02 includes an SST and a mapped HPLMN SST; a third state corresponding to a hexadecimal value of 04 includes an SST and an SD; a fourth state corresponding to a hexadecimal value of 05 includes an SST, an SD, and a mapped HPLMN SST; and a fifth state corresponding to a hexadecimal value of 08 includes an SST, an SD, a first state corresponding to a hexadecimal value of 01 includes an SST, and a mapped HPLMN SD. Other states of the octet can be reserved and / or used to represent other possible forms of the content.

[0128] In some embodiments, the length field can be a second octet in a multi-octet S-NSSAI, e.g., as defined in 3GPP TS 24.501, Release 16.3.0.

[0129] H-NSSF for storing roaming agreements per S-NSSAI

[0130] In some embodiments, for each S-NSSAI value supported by an HPLMN, a home NSSF (i.e., a network slice selection function of the HPLMN) can store a data structure that includes: a list of regions (e.g., foreign countries or territories or states) such that each of these regions has one or more PLMNs that have agreed with the HPLMN to support the S-NSSAI; and for each such region, a corresponding list of identifiers that identify the one or more PLMNs. (Although we can speak of agreements between PLMNs, it will be understood that agreements can be established between the owners / operators of the PLMNs.) For example, for a given network slice identified by an S-NSSAI value V1, the list of regions can identify foreign countries corresponding to MCC value X and MCC value Y. (MCC is an acronym for Mobile Country Code.) In the country with MCC value X, the corresponding list of identifiers can identify PLMNs A X and B X that support S-NSSAI value V1. Similarly, in the country with MCC value Y, the corresponding list of identifiers can identify PLMNs E Y and F Y .

[0131] The above data structure can be referred to herein as a “roaming agreement structure”. The roaming agreement structure can be updated at any time when the roaming agreement is updated (e.g., added or removed or modified). For example, the list of PLMN identifiers for a particular country can be updated.

[0132] When the home NSSF updates the roaming agreement structure for any S-NSSAI, it can inform the AMF about the HPLMN.

[0133] In some embodiments, the home AMF can use the updated roaming agreement structure to perform (or initiate) a UE configuration update (UCU) procedure. For example, the home AMF can (a) send the updated list of roaming PLMN identifiers only for the affected S-NSSAI, instead of for all supported S-NSSAI, and / or (b) send it only for the affected area.

[0134] In some embodiments, when performing the UCU procedure, the home AMF can indicate the change related to each S-NSSAI in the set of allowed S-NSSAI: addition or deletion or modification of the content of the allowed S-NSSAI. Multiple update tasks can be performed in the same UCU procedure.

[0135] The specific mechanisms by which the roaming agreements are updated in the NSSF can be implementation dependent. For example, these roaming agreements can be updated by the operator in different ways, e.g., by updating the NSSF directly or via a network function (NF) such as an application function (AF), or by providing configuration options.

[0136] NSSF roaming agreement table

[0137] In some embodiments, the roaming agreement structure can be implemented as a table with a sub-table for each slice, e.g., as shown in Table 1 below. For example, for a network slice corresponding to S-NSSAI value a, the HPLMN can have a roaming agreement with PLMN 01 and 02 in country X, PLMN 03 in country Y, and PLMN 07 in country Z. For a network slice corresponding to S-NSSAI value b, the HPLMN can have a roaming agreement with PLMN 01 in country X, PLMN 04 and 05 in country Y, and PLMN 07 in country Z. The UE can utilize a GPS-derived location to determine which country it is located in at a given time, and access the list of PLMN identifiers corresponding to that country and the desired S-NSSAI value.

[0138] Table 1 : Roaming agreement table

[0139]

[0140] Roaming agreement for (UE initiated) S-NSSAI pushed in HPLMN

[0141] In some embodiments, the UE can send a registration request to the HPLMN. The registration request can include a list of S-NSSAIs that identify the corresponding network slices that the UE requests to access. Each of the listed S-NSSAIs can contain a new information element - "request-PLMN-list". The value of the "request-PLMN-list" IE for an S-NSSAI can be set to true or false based on whether the UE already has a list of supported PLMNs for the S-NSSAI (e.g., a list of PLMN identifiers of PLMNs that have roaming agreements to support the S-NSSAI) in its memory.

[0142] For S-NSSAIs in the list of requested S-NSSAIs that have a request-PLMN-list set to true, the home AMF can send an extract request to the home NSSF requesting the home NSSF to extract the corresponding list of supported PLMNs. In response to the query, the home NSSF can check its roaming agreement structure to extract the list of supported PLMNs for the S-NSSAI and send the extracted list to the home AMF.

[0143] The home AMF can send a registration accept message to the UE including a list of one or more allowed S-NSSAIs. (Generally, the list of allowed S-NSSAIs is provided by the serving PLMN, e.g., during a registration procedure, and indicates the S-NSSAI values that the UE can use in the serving PLMN.) As part of each allowed S-NSSAI, the home AMF can include a new information element (IE) containing the associated list of supported PLMNs.

[0144] The registration accept message can also include a list of one or more rejected S-NSSAIs, e.g., with a rejection reason and a rejection validity for each rejected S-NSSAI. (A rejected S-NSSAI is an S-NSSAI that the UE is not allowed to use on the PLMN that sent the rejection list.) In some embodiments, when roaming to a different country (other than the home country), the UE can check the list of supported PLMNs in the list of allowed S-NSSAIs and / or the list of supported PLMNs in the list of rejected S-NSSAIs and decide to stay registered in the current PLMN or switch to a different PLMN.

[0145] In some embodiments, the list of supported PLMNs can be sent as a new optional IE outside (e.g., after) its corresponding allowed S-NSSAI, taking into account the size of the list of supported PLMNs.

[0146] Supporting PLMN list

[0147] The list of supported PLMNs can be large. Sending the list of supported PLMNs for each S-NSSAI in the allowed NSSAI would consume a large amount of communication channel resources. Thus, the UE can set the "request-PLMN-list" IE for an S-NSSAI to false if the UE already has the corresponding list of supported PLMNs stored in its memory.

[0148] In some embodiments, the UE can specify one or more countries (e.g., as indicated by one or more corresponding MCCs) for which it is requesting the list of supported PLMNs. The one or more countries can be specified in the registration request or in some other message sent to the home PLMN (or VPLMN). Based on a user's future planned event (e.g., input from iCal, Siri, etc.), the UE can predict that the UE can be in a given foreign country (e.g., China next week) from a given future time, and thus selectively fetch the list of supported PLMNs only for the given country (e.g., the MCC equal to China). Thus, this is another technique for reducing the message size.

[0149] In some embodiments, a validity timer period can be added to the list of supported PLMNs for a given allowed S-NSSAI that is sent to the UE. The list of supported PLMNs is guaranteed to be valid at least for the amount of time indicated by the validity timer period (e.g., from the time of transmission of the list of supported PLMNs). Thus, the UE does not need to request the list of supported PLMNs for a given S-NSSAI if the validity timer period has not expired. When the UE receives the list of supported PLMNs for a given S-NSSAI, it can store the time of reception and the value of the validity timer period, so that it will be able to determine whether to request the PLMN list at the next registration. In some embodiments, the validity timer period can be a value of about a few hours and / or a few days. The validity timer can be continued after a reboot of the UE, e.g., by using non-volatile memory of the UE. (The start time of the validity timer and the validity timer period can be stored in the non-volatile memory.)

[0150] In some embodiments, the value of the list of supported PLMNs for a given allowed S-NSSAI should be valid in the UE until the expiration of the validity timer period, or until the UE receives a UE configuration update command with an updated list of supported PLMNs for the allowed S-NSSAI, even after a power cycle.

[0151] Transfer of UE initiated S-NSSAI roaming agreement in HPLMN

[0152] Figure 6An example is shown of the transfer of a UE-initiated S-NSSAI roaming agreement (as represented by a list of supporting PLMNs) while in a home PLMN, according to some embodiments. The example can involve a UE 610, an AMF 612, a NRF 614, and a NSSF 616. The AMF, NRF, and NSSF can be network functions or nodes of a home PLMN: the AMF represents an access and mobility management function; the NRF represents a network repository function; and the NSSF represents a network slice selection function.

[0153] At 1, the UE can send a registration request (e.g., with a registration request type value set to indicate an initial request by the UE at first power-up) to the AMF, e.g., via a base station such as a gNB of 3GPP 5G. The registration request can include: a requested S-NSSAI value “a” with request-PLMN-list set to true; and a requested S-NSSAI value “b” with request-PLMN-list set to true. (In some embodiments, the registration request can additionally or alternatively include an identification of one or more countries to be visited in the future, e.g., as discussed above.)

[0154] At 2, the AMF can send a request to the NRF for an IP address of the NSSF. The request is denoted as Nnrf_NFDiscovery_Request. The prefix “Nnrf” specifies the message as targeting the NRF.

[0155] At 3, the NRF can send a response (denoted as Nnrf_NFDiscovery_Response) to the AMF, including an IP address of the NSSF.

[0156] At 4, the AMF can send a request (denoted as Nnssf_NSSelection_Get_Request) to the NSSF, including: S-NSSAI value “a” with a request for a corresponding list of supporting PLMNs; and S-NSSAI value “b” with a request for a corresponding list of supporting PLMNs. The IP address received at 3 can be used to direct the NSSF. (In some embodiments, the request can additionally or alternatively include an identification of one or more countries to be visited in the future.)

[0157] At 5, the NSSF can check its roaming agreement database, and pull out the list of supporting PLMNs for S-NSSAI values “a” and “b.” (In some embodiments, the NSSF can pull out the list of supporting PLMNs for only one or more identified countries.)

[0158] At 6, the NSSF can send a response (indicated as Nnssf_NSSelection_Get_Response) to the AMF including: S-NSSAI value "a" with the corresponding list of supported PLMNs; and S-NSSAI value "b" with the corresponding list of supported PLMNs. (In some embodiments, the list of supported PLMNs sent to the AMF is limited to a list corresponding to one or more identified countries.)

[0159] At 7, the AMF can send a registration accept message including the allowed S-NSSAIs to the UE. The allowed S-NSSAIs can include: S-NSSAI value "a" with the corresponding list of supported PLMNs; and S-NSSAI value "b" with the corresponding list of supported PLMNs. (In some embodiments, the list of supported PLMNs sent to the UE can be limited to a list corresponding to one or more identified countries.)

[0160] In any of the various embodiments and examples presented herein, messages communicated between the UE and the AMF can be communicated via a base station (e.g., a gNB of 3GPP 5G NR), e.g., as shown in Figure 1 .

[0161] Transfer of selective (UE initiated) S-NSSAI roaming agreement in HPLMN

[0162] Figure 7 An example of the communication of a selective (and UE-initiated) S-NSSAI roaming protocol when in a HPLMN is shown, according to some embodiments. The example can involve a UE 610, an AMF 612, a NRF 614, and a NSSF 616.

[0163] At 1, the UE can send a registration request (initial request) to the AMF, e.g., via a base station such as a gNB of 3GPP 5G. The registration request can include: a requested S-NSSAI value "a" with request-PLMN-list set to true; and a requested S-NSSAI value "b" with request-PLMN-list set to false.

[0164] At 2, the AMF can send a request to the NRF for the IP address of the NSSF. (The request is indicated as Nnrf_NFDiscovery_Request.)

[0165] At 3, the NRF can send a response (indicated as Nnrf_NFDiscovery_Response) to the AMF including the IP address of the NSSF.

[0166] At 4, the AMF can send a request (indicated as Nnssf_NSSelection_Get_Request) to the NSSF including: the S-NSSAI value "a" with a request for the corresponding list of supported PLMNs. The IP address received at 3 can be used to point to the NSSF.

[0167] At 5, the NSSF can check its roaming agreement database and pull out the list of supported PLMNs for the S-NSSAI value "a".

[0168] At 6, the NSSF can send a response (indicated as Nnssf_NSSelection_Get_Response) to the AMF including: the S-NSSAI value "a" with the corresponding list of supported PLMNs.

[0169] At 7, the AMF can send a registration accept message including the allowed S-NSSAI to the UE. The allowed S-NSSAI itself includes: the S-NSSAI value "a" with the corresponding list of supported PLMNs.

[0170] Roaming agreement for (NW initiated) S-NSSAI pushed in HPLMN

[0171] In some embodiments, the NSSF of the HPLMN can update the list of supported PLMNs corresponding to an S-NSSAI in response to a roaming agreement change. The roaming agreement change can include: adding a new PLMN, e.g., in response to establishing a new agreement; removing an existing PLMN, e.g., in response to the end of an existing agreement; or modifying an existing PLMN.

[0172] The NSSF can notify the home AMF of the change in the list of supported PLMNs for a given S-NSSAI.

[0173] The home AMF can initiate a UE configuration update (UCU) command to (proactively) inform the UE of the updated status of the list of supported PLMNs corresponding to an S-NSSAI.

[0174] In some embodiments, the home AMF sends an update message to the UE including a list of S-NSSAIs and their corresponding list of supported PLMNs, where the list of S-NSSAIs includes only S-NSSAIs whose list of supported PLMNs has been updated. The update message does not include any S-NSSAIs whose list of supported PLMNs has not been updated. (If the list of supported PLMNs for an S-NSSAI has not been updated, there is no need to send the list of PLMNs to the UE, as the list of PLMNs present in the memory of the UE is still valid.)

[0175] The UE can delete the existing supported PLMN list for the S-NSSAI identified in the UCU command and replace the existing supported PLMN list with the received supported PLMN list corresponding to the S-NSSAI.

[0176] In alternative embodiments, when the roaming agreement change for a given S-NSSAI only impacts a single country, the home AMF can send to the UE a PLMN sub-list corresponding to the country and the given S-NSSAI instead of the entire PLMN list. The UE can then update only this sub-list instead of deleting and replacing the entire PLMN list corresponding to the given S-NSSAI.

[0177] In some embodiments, based on the supported PLMN list in the allowed S-NSSAI list and / or the supported PLMN list in the rejected S-NSSAI list, the UE can decide to remain registered in the current PLMN or to handover to a different PLMN.

[0178] In some embodiments, the mechanism by which the roaming agreement is updated in the NSSF is implementation dependent. The roaming agreement can be updated by the operator in different ways, for example, by updating the NSSF directly or via any other network function (NF).

[0179] Transfer of NW initiated selected S-NSSAI roaming agreement in HPLMN

[0180] Figure 8 An example of network-initiated transfer of S-NSSAI roaming agreement when the UE is in the HPLMN is shown, according to some embodiments. The example involves a UE 810, an AMF 812, and an NSSF 816. The AMF, NRF, and NSSF belong to the home PLMN of the UE.

[0181] At 1, the service provider can update the roaming agreement for a particular operator, for example, by adding a PLMN, removing a PLMN, or modifying a PLMN.

[0182] At 2, the NSSF can send to the AMF a notification message (denoted Nnssf_NSSAI Availability_Notify) that includes the S-NSSAI value "a" and the supported PLMN list for the S-NSSAI value "a".

[0183] At 3, the AMF can send to the UE a configuration update command that includes: an allowed S-NSSAI with a value equal to the S-NSSAI value "a"; and the supported PLMN list for the S-NSSAI value "a".

[0184] At 4, the UE can send a "UE configuration update complete" message to the AMF indicating that the update of the supported PLMN list associated with S-NSSAI value "a" has been successfully completed.

[0185] Roaming agreement according to validity timer period

[0186] In some embodiments, for each S-NSSAI, the corresponding supported PLMN list can have a corresponding validity timer period. The validity timer period is a time period during which the corresponding supported PLMN list is guaranteed to be valid. When the supported PLMN list is sent to the UE, the corresponding validity timer period is sent together with the supported PLMN list. These embodiments can be used, for example, in the case that the user of the UE has purchased a temporary roaming agreement when expecting to visit a foreign country. The temporary roaming agreement can have a limited duration, e.g., a limited number of hours, days, or weeks.

[0187] In some embodiments, the validity timer can be in terms of time. For example, a supported PLMN list (also referred to herein as a "roaming PLMN list") can be valid for a few hours, a few days, or a few weeks. After the validity period expires, the list becomes invalid. (The PLMNs in the list can no longer be usable by the UE.) This can be used in the case that the customer pays for a roaming contract that is valid for a few hours or a few days.

[0188] In some embodiments, the validity timer period can be provided to the UE as part of a registration accept, as shown in Figure 9 The UE 910 can send a registration request (initial request) to an AMF 912 of a home PLMN of the UE, the registration request including a list of requested S-NSSAI. For example, the list of requested S-NSSAI can include: S-NSSAI value "a" with request-PLMN-list set equal to true; and S-NSSAI value "b" with request-PLMN-list set equal to true. (Request-PLMN-list is an information element indicating whether the UE is requesting a supported PLMN list for the corresponding S-NSSAI value.) In response to the registration request, the AMF can send a registration accept message to the UE including a list of allowed S-NSSAI. For example, the list of allowed S-NSSAI can include: S-NSSAI value "a" with an associated supported PLMN list and an associated validity timer period; and S-NSSAI value "b" with an associated supported PLMN list and an associated validity timer period.

[0189] In some embodiments, the validity timer period can be provided to the UE as part of a configuration update command, as shown in Figure 10The AMF 1012 of the UE's home PLMN can send a UE configuration update command to the UE 1010 that includes the allowed S-NSSAI (S-NSSAI value "a" in the example shown), the associated list of supported PLMNs, and the associated validity timer period. The UE stores the allowed S-NSSAI, the list of supported PLMNs, and the validity timer period in its memory. The UE can respond by sending a UE configuration update complete message indicating that the configuration update has been successfully completed.

[0190] Roaming agreement for S-NSSAI pushed in VPLMN

[0191] A potential drawback of pushing the list of supported PLMNs to the UE in the HPLMN is due to the large size of the list. The UE can only access the list when it moves to a different country. If the UE is always located within the HPLMN, the transfer and storage of the list amounts to a waste of resources and memory.

[0192] In some embodiments, the list of supported PLMNs can be provided to the UE in the case where the UE sends a registration request to a visited PLMN (VPLMN) while roaming away from the home country. The registration request can include a list of one or more requested S-NSSAIs. Each S-NSSAI in the list can include, for example, a mapped HPLMN SST field in the second state, the fourth state, or the fifth state of the length indicator. Figure 5 The mapped HPLMN SST field in the second state, the fourth state, or the fifth state of the length indicator is shown.

[0193] In response to the registration request sent by the UE to the VPLMN, the AMF of the VPLMN can send a registration accept message to the UE that includes a list of one or more allowed S-NSSAIs and a list of one or more rejected S-NSSAIs. The registration accept message can also include: a list of supported PLMNs for each S-NSSAI in the list of allowed S-NSSAIs; and a list of supported PLMNs for each S-NSSAI in the list of rejected S-NSSAIs.

[0194] Based on the list of supported PLMNs in the list of allowed S-NSSAIs and / or the list of supported PLMNs in the list of rejected S-NSSAIs, the UE can decide to remain registered in the current PLMN or to switch to a different PLMN.

[0195] UE implementation according to NSSF roaming agreement table

[0196] In some embodiments, the UE can perform PLMN selection based on a roaming agreement table, an example of which is shown in Table 2 below.

[0197] Table 2: Roaming agreement table

[0198]

[0199] In country X, the UE can have a preference for PLMN 01 because this PLMN supports both S-NSSAI value a and S-NSSAI value b. (In other words, PLMN 01 supports slice a and slice b).

[0200] In country Y, the UE can have no preference. The UE can then follow a list of preferred PLMNs (PPLMNs) by default. However, once the user expresses an interest in utilizing a particular slice (e.g., by selecting a particular application on the UE), the UE can immediately move to a VPLMN that supports that slice. (The VPLMN that supports that slice can be communicated to the UE by a registration access message. This registration access message is sent by the V-AMF.) For example, if the user has expressed an interest in utilizing a slice corresponding to S-NSSAI value a while in country Y, the UE can attempt to register with PLMN 03.

[0201] In country Z, the UE can have a preference for PLMN 07.

[0202] In some embodiments, the UE can assign a higher priority to a slice PLMN (e.g., a VPLMN associated with a slice that the user has expressed an interest in) than any of the PLMNs on the PPLMN list until the service of the slice VPLMN expires (e.g., based on a validity timer) or until a PLMN change due to unavailability of the slice VPLMN.

[0203] UE implementation regarding PLMN selection based on supporting PLMN list

[0204] According to a general priority scheme for PLMN selection, the UE can select the PLMN with the highest priority in the following hierarchy:

[0205] EHPLMN > UPLMN > OPLMN > any other PLMN.

[0206] EHPLMN is an acronym for Equivalent HPLMN. An Equivalent HPLMN is a PLMN that is guaranteed to be equivalent to the (UE's) HPLMN in terms of supported network slices. UPLMN stands for User PLMN and represents the user-defined PLMN priority in a given roaming country. For example, a device software vendor can program a UE device with preferred PLMNs in a given roaming country. (The device SW vendor can define a rule that if a UE that is subscribed to Operator X roams to country Y, then PLMNs A and B are preferred.) OPLMN stands for Operator PLMN and corresponds to the PLMN priority specified by the operator's SIM card for a given country. The term "any other PLMN" means any PLMN that does not belong to the higher PLMN categories (i.e., EHPLMN, UPLMN, and OPLMN).

[0207] In some embodiments, according to the modified priority scheme for PLMN selection, the UE can select the PLMN with the highest priority in the following hierarchy:

[0208] EHPLMN > Slice PLMN > Preferred PLMN > Any other PLMN.

[0209] Slice PLMN refers to a PLMN that belongs to the list of supported PLMNs received from the network (e.g., home PLMN). Preferred PLMN refers to any PLMN in the UPLMN and OPLMN categories. "Any other PLMN" refers to any PLMN that does not belong to the categories with higher priority (i.e., EHPLMN, Slice PLMN, Preferred PLM).

[0210] Based on the list of supported PLMNs in the allowed S-NSSAI list and / or the list of supported PLMNs in the rejected S-NSSAI list, the UE can decide to stay registered in the current PLMN or switch to a different PLMN. This change can occur through reselection. Upon expiration of the SIM reselection timer with an initial value T SWITCH , reselection can be initiated. (The SIM reselection timer can be incremental, meaning that it is essentially telescopic. For example, the SIM reselection timer can start with an initial value of 3 minutes and in the next iteration, the initial value is increased to 5 minutes, then to 6 minutes, and so on.) The timer can be started when the UE camps on any PLMN. For example, the value of T SWITCH may be a number of minutes, such as 3 minutes or 5 minutes or 6 minutes or 8 minutes. Any of a variety of values can be used.

[0211] In some embodiments, the UE can perform PLMN selection based on a dynamic PLMN selection priority table, e.g., of the country in which the UE is currently roaming. The dynamic PLMN selection priority table can include one or more allowed S-NSSAIs per VPLMN (or one or more supporting VPLMNs per S-NSSAI).

[0212] The UE can maintain a priority list of supported (or allowed) S-NSSAIs received in the HPLMN.

[0213] The priority of a VPLMN with one or more supported (or allowed) S-NSSAIs can be incremented over PPLMNs (OPLMNs / UPLMNs). In the absence of a preferred PLMN available, a VPLMN that supports the largest number of slices (e.g., S-NSSAIs) in country X can be assigned the highest priority for PLMN selection when roaming in country X.

[0214] The UE can register with the highest priority PLMN based on the dynamic PLMN selection priority table.

[0215] In some embodiments, one or more exit criteria can be employed.

[0216] For example, when a user’s subscription to a slice expires or any expiration of an S-NSSAI occurs, the UE can restore the preferred PLMN (PPLMN) list, and reselection to the highest priority PLMN can be based on the SIM Elementary File (EF). SIM is an acronym for Subscriber Identity Module.

[0217] Another condition for the UE to move back from the dynamic PLMN selection priority table to the PPLMN list can be the unavailability of any slice preferred VPLMN. If none of the VPLMNs in the EHPLMN, slice PLMN, and PPLMN categories support the requested slice, the UE can select an arbitrary PLMN.

[0218] In some embodiments, the dynamic PLMN selection priority table can be configurable or reconfigurable, e.g., using a component of a registration accept message sent from a home AMF and routed through a V-AMF (i.e., an AMF of a visited PLMN).

[0219] Permission server based UE implementation

[0220] In some embodiments, a roaming UE 1110 can receive a list of supporting VPLMNs 1122 for a given network slice (corresponding to a given S-NSSAI) from an entitlement server 1112, e.g., as shown in Figure 11

[0221] ​If the UE fails to find an available EHPLMN while roaming in a given country, the UE can determine its current roaming location, as indicated at 1116. The current roaming location can be an identification of the country in which the UE is currently roaming. The UE can determine its current roaming location, e.g., using GPS coordinates of the UE and / or using WiFi-based positioning mechanisms. (GPS is an acronym for Global Positioning System.) For example, the UE can determine its approximate location based on the location of a WiFi access point to which it is connected.

[0222] In response to determining its current roaming location, the UE can send a fetch request 1118 to the authority server. The fetch request can include the current roaming location and an identification of a network slice that the UE desires to access. The network slice identification can be an S-NSSAI.

[0223] In response to receiving the fetch request 1118, the authority server 1112 can send a (secure) fetch request 1120 to the home operator 1114 (e.g., the HPLMN of the UE). The fetch request can include the current UE roaming location and an identification of the network slice.

[0224] In response to the fetch request 1120, the home operator 1114 can send a list of VPLMNs that support the identified network slice in the country corresponding to the current UE roaming location 1122 to the authority server. More generally, the home operator can send a set of supported slices, services, and supporting PLMNs to the authority server for the current UE roaming location.

[0225] In response to receiving the list of supporting PLMNs 1122, the authority server can forward the list of supporting PLMNs to the UE 1110. (The list of supporting PLMNs can be ordered to indicate a priority of preference.) The UE stores the list of supporting PLMNs in its memory.

[0226] When deciding on a VPLMN to camp on, the UE can prioritize VPLMNs in the list of supporting PLMNs over preferred PLMNs (of OPMN and UPLMN categories).

[0227] In case the list of supporting PLMNs is not available or the home PLMN provides one or more PLMNs that are not available at the current location, the UE can prioritize the SIM preferred PLMNs for camping and other services. The UE can receive an updated list of VPLMNs for the respective slice after registering on a PPLMN, or later attempt to use the PLMN list provided by the authority server to obtain services when the PLMNs provided by the HPLMN become available to the UE.

[0228] The authority server can be implemented as a cloud service for secure communication and routing of roaming service information between the home network and the UE.

[0229] Figure 12 : roaming network slice selection based on stored list of supporting plmn

[0230] In some embodiments, a method 1200 for operating a wireless user equipment (UE) device can include operations as shown in FIG. 12. (Method 1200 can also include any subset of the elements, embodiments, and features described above in connection with the user equipment 106.) For example, as described above in connection with the user equipment 106, a wireless UE device can be configured as variously described above. Method 1200 can be performed by a processing element of the UE device. Figure 12 In some embodiments, a method 1200 for operating a wireless user equipment (UE) device can include operations as shown in FIG. 12. (Method 1200 can also include any subset of the elements, embodiments, and features described above in connection with the user equipment 106.) For example, as described above in connection with the user equipment 106, a wireless UE device can be configured as variously described above. Method 1200 can be performed by a processing element of the UE device. Figures 1 to 11 Figure 3 At 1210, the processing element can receive a list of one or more public land mobile networks (PLMNs) that support a given network slice in a given country, where the given country is different from a home country of a home PLMN of the UE, where the given network slice is supported in the home PLMN. The list can be stored in a memory (e.g., a non-volatile memory) of the UE.

[0231] At 1215, in response to determining that the UE is located in the given country and desires access to the given network slice, the processing element can access (e.g., register or connect to) a PLMN of the list to use the given network slice. (Alternatively, in response to the determination, the processing element can prioritize access to the PLMNs of the list, e.g., over preferred PLMNs, e.g., as variously described above.) The UE can determine that it is located in the given country, e.g., by determining a GPS location of the UE and determining that the GPS location is in the given country.

[0232] In some embodiments, the act of accessing the PLMN of the list is preceded by an act of selecting the PLMN from the list using any of various selection criteria. For example, where the list (as received) is ordered according to selection priority, the processing element can select the first (or highest) PLMN on the list. As another example, the processing element can select the PLMN of the list that has the highest measured signal strength, signal-to-noise ratio (SINR), reference signal received power (RSRP), or any other measure of signal or connection quality.

[0233] In some embodiments, the processing element can access the PLMN of the list by sending a registration request (or a connection request or a random access preamble) to the PLMN. The registration request can include an identifier of the given network slice.

[0234] In some embodiments, the processing element can access the PLMN of the list by sending a registration request (or a connection request or a random access preamble) to the PLMN. The registration request can include an identifier of the given network slice.

[0235] ​In some embodiments, while in the home country or in a given country, the processing element can transmit a registration request (or other message) to the home PLMN, e.g., as described above in various places. After the registration request has been transmitted, a list can be received from the home PLMN. (The network slice selection function of the home PLMN can store and maintain the list.)

[0236] In some embodiments, the registration request (or other message) can include a requested S-NSSAI (single network slice selection assistance information) value associated with a given network slice, e.g., as described above in various places. The S-NSSAI value can include an information element (IE) indicating whether a list of one or more PLMNs is requested.

[0237] In some embodiments, the registration request (or other message) can include an identification of a given country, e.g., a mobile country code (MCC) of the given country. In some embodiments, the registration request can have an identification of one or more roaming countries of the given country, e.g., as described above in various places. Thus, the processing element can receive one or more lists corresponding to the one or more roaming countries, where each list includes one or more PLMNs that support a given network slice in the corresponding roaming country. Thus, the processing element can not be inundated with all lists for all countries or all lists for all network slices.

[0238] In some embodiments, while the UE is in a given country, the processing element can send a registration request (or other message) to a roaming PLMN in the given country, the registration request including an identification of a second country different from the home country and different from the given country. The roaming PLMN can contact the home NSSF to obtain a list of one or more PLMNs that support a given slice in the second country and forward the list to the UE. The processing element can receive the list, e.g., from a base station of the roaming PLMN. This registration request including the identification of the second country can be sent while the UE is in the given country, e.g., in anticipation of entering the second country in the future.

[0239] In some embodiments, the list can be received along with a validity timer period indicating a length of time for which the list is guaranteed to be valid, e.g., as described above in various places.

[0240] In some embodiments, the processing element can be configured to receive a validity timer period indicating a period of time after which one or more PLMNs in the list will no longer support a given slice. The validity timer can persist across reboots, e.g., as described above in various places.

[0241] In some implementations, the processing element may receive the list when: (a) the UE is associated with (e.g., pre-occupied or connected to) a home PLMN in its home country; and (b) the UE has not made any request for the list. For example, the home PLMN may update the list when establishing, terminating, or modifying a roaming agreement involving the home PLMN; and in response to such update, send the updated status of the list to the UE. The list may be received from the home PLMN (e.g., from the home PLMN's Access and Mobility Management Function (AMF)). The UE may communicate with the home PLMN via its base station (e.g., a 3GPP 5G gNB).

[0242] In some implementations, the processing element may receive a list from the home PLMN via: (a) a visiting PLMN in a given country, or (b) a WiFi access point in a given country.

[0243] In some implementations, the processing element may send an access request to the authorization server when roaming in a given country, for example, as described above. Figure 11 The acquisition request may include an identifier of the UE's location and an identifier of a given network slice. The processing element may receive a list of one or more PLMNs after the acquisition request has been sent.

[0244] In some implementations, the processing element may prioritize one or more PLMNs from a list over preferred PLMNs (e.g., user-preferred PLMNs and operator-preferred PLMNs) when selecting a PLMN.

[0245] In some implementations, the processing element may receive an updated list of one or more PLMNs that support a given network slice in a given country, for example, as described in the various descriptions above.

[0246] In some implementations, the method 1300 for operating the Access and Mobility Management Function (AMF) of a Home Public Land Mobile Network (PLMN) in the home country may include Figure 13 The operation shown. (Method 1300 may also include the above combined with...) Figures 1 to 12 Any subset of the described elements, implementations, and features. For example, AMF can be implemented by a processing element that executes program instructions.

[0247] At 1310, the processing element can retrieve a list of one or more roaming (or visited) Public Land Mobile Networks (PLMNs) supporting a given network slice in a given country, where the given country is different from the home country. For example, the AMF can retrieve the list from the Network Slice Selection Function (NSSF) of the home PLMN.

[0248] At 1315, the processing element can send the list to the user equipment (UE) contracted with the home PLMN. The list can be sent to the UE via a base station (e.g., a gNB of 3GPP 5G) or via the Internet.

[0249] In some implementations, the processing element may send a list in response to a registration request (or other message) received from the UE. The registration request (or other message) may indicate a given network slice and / or a given country. The network slice may be indicated, for example, using a Single Network Slice Selection Auxiliary Information (S-NSSAI) value.

[0250] In some implementations, the processing element can send the list to the UE without the UE making any request for the list. (Therefore, it can be said that the list is pushed to the UE.) For example, the processing element can send the list to the UE when the UE is associated with a home PLMN (e.g., pre-occupied or connected to it).

[0251] In some implementations, the processing element may send a list to the UE via a visited PLMN that the UE attempts to register with (or has connected to) in a given country.

[0252] In some implementations, the processing element may send the list to the authorization server of the visited PLMN to which the UE is connected, for example, as described in the various descriptions above. The authorization server may then forward the list to the UE.

[0253] In some implementations, the processing element may send a validity timer value (e.g., a validity timer value as described in any of the implementations above) along with a list to the UE.

[0254] In some implementations, the method 1400 for operating a base station (BS) may include Figure 14 The operation shown. (Method 1400 may also include the above combined with...) Figures 1 to 13 Any subset of the described elements, implementations, and features. (e.g., in combination) Figure 4 As described in base station 102, the base station can be configured as described in the various descriptions above. Method 1400 can be executed by the processing element of the base station.

[0255] At 1410, the processing element can receive a registration request (or other message) from the user equipment (UE) via the RF channel, wherein the registration request (or other message) includes an indication of a given network slice and / or an indication of a given country, for example, as described in the various above. The given network slice may be a slice that the UE is interested in using. The given country is different from the home country of the UE's home PLMN. The given country may be, for example, a country in which the UE is currently roaming, or a country that the UE expects to visit in the future. The base station may be a base station of the home PLMN, or a base station of a roaming PLMN in the given country.

[0256] At 1415, the processing element can transmit, to the UE over the RF channel, a registration accept message (or more generally, a response message), where the registration accept message (or response message) includes a list of one or more public land mobile networks in a given country that support a given network slice.

[0257] In some embodiments, the base station can be a base station that belongs to a home PLMN of the UE, e.g., as described in various places above.

[0258] In some embodiments, the base station can be a base station that belongs to a visited PLMN in the given country (e.g., a visited PLMN to which the UE has connected) or from which the registration request was sent. The UE can switch to another PLMN in the given country after receiving the list, e.g., to a PLMN selected from the list.

[0259] In some embodiments, the processing element can send a validity timer period along with the list, e.g., as described in various places herein.

[0260] Embodiments of the disclosure can be realized in any of various forms. For example, some embodiments can be realized as computer-implemented methods, computer-readable memory media, or apparatuses. Other embodiments can be realized using one or more custom-designed hardware devices such as ASICs. Other embodiments can be realized using one or more programmable hardware elements such as FPGAs.

[0261] Some embodiments can include an apparatus that includes an antenna, a radio coupled to the antenna, and a processing element operably coupled to the radio, where the apparatus is configured to implement any or all parts of the foregoing examples.

[0262] In some embodiments, an apparatus (e.g., a UE 106) can be configured to include a processor (or a set of processors) and a memory medium, where the memory medium stores program instructions, where the processor is configured to read and execute the program instructions from the memory medium, where the program instructions are executable to implement any of the various method embodiments described herein (or any combination of the method embodiments described herein, or any subset of any of the method embodiments described herein, or any combination of such subsets). The apparatus can be realized in any of various forms.

[0263] Yet another example embodiment can include an apparatus that includes means for performing any or all of the elements of any of the foregoing examples.

[0264] Yet another example embodiment can include an apparatus comprising a processing element configured to cause a device to perform any or all of the elements of any of the preceding examples.

[0265] Any of the methods described herein for operating a user equipment (UE) that communicates with a base station can be the basis for a corresponding method for operating a base station by interpreting each message / signal X received by the UE in the downlink as a message / signal X transmitted by the base station and each message / signal Y transmitted by the UE in the uplink as a message / signal Y received by the base station.

[0266] It is well understood that, by using personally identifiable information, one must follow the privacy policies and practices that are generally recognized as satisfying or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled in a manner that minimizes risks from unauthorized or improper access or use of data.

[0267] While the above embodiments have been described in considerable detail, variations and modifications of the above will readily occur to persons skilled in the art. The disclosure is intended to include all such variations and modifications. The above disclosure is to be construed as illustrative only and not limiting of the disclosure.

Claims

1. A user equipment (UE), comprising: At least one antenna; A wireless electronic system coupled to the at least one antenna; and A processing element coupled to the wireless electronic system, wherein the processing element is configured to: The UE sends a registration request to its home public land mobile network (PLMN), the registration request including a requested single network slice selection assistance information (S-NSSAI) value associated with a given network slice. After the registration request has been sent, a list of multiple PLMNs that support the given network slice in a given country is received, wherein the given country is different from the home country of the UE’s home PLMN, wherein the given network slice is supported in the home PLMN, and wherein the requested S-NSSAI value includes information elements indicating whether the list of multiple PLMNs is requested. as well as In response to determining that the UE is located in the given country and wishes to access the given network slice, it accesses a PLMN in the list to use the given network slice.

2. The UE according to claim 1, wherein the registration request includes: Includes the identifiers of one or more roaming countries for the given country.

3. The UE of claim 1, wherein the list is received together with a validity timer period, the validity timer period indicating the length of time during which the list is guaranteed to be valid.

4. The UE of claim 1, wherein the processing element is configured to receive a validity timer period, the validity timer period indicating a time period after which the plurality of PLMNs in the list will no longer support the given network slice.

5. The UE of claim 1, wherein the processing element is configured to receive the list when: (a) the UE is associated with the home PLMN in the home country; and (b) the UE has not made any request for the list.

6. The UE of claim 1, wherein the processing element is configured to receive the list from the home PLMN via: (a) Visit to the PLMN of the given country, or (b) WiFi access points in the given country; or (c) Satellite-based Internet connectivity in the given country.

7. The UE of claim 1, wherein the processing element is configured to: When roaming in the given country, the UE sends an access request to the authorization server, wherein the access request includes an indication of the UE's location and an identifier of the given network slice, wherein the list is received after the access request has been sent.

8. The UE of claim 1, wherein the processing element is configured to prioritize the plurality of PLMNs in the list over the user-preferred PLMN and the operator-preferred PLMN when selecting a PLMN.

9. The UE of claim 1, wherein the processing element is configured to receive an updated list of one or more PLMNs supporting the given network slice in the given country.

10. A method for operating a user equipment (UE), the method comprising: The UE sends a registration request to its home public land mobile network (PLMN), the registration request including a requested single network slice selection assistance information (S-NSSAI) value associated with a given network slice. After the registration request has been sent, a list of multiple PLMNs that support the given network slice in a given country is received, wherein the given country is different from the home country of the UE’s home PLMN, wherein the given network slice is supported in the home PLMN, and wherein the requested S-NSSAI value includes information elements indicating whether the list of multiple PLMNs is requested. as well as In response to determining that the UE is located in the given country and wishes to access the given network slice, it accesses a PLMN in the list to use the given network slice.

11. The method of claim 10, wherein the registration request comprises: Includes the identifiers of one or more roaming countries for the given country.

12. The method of claim 10, wherein the list is received from the home PLMN of the UE when: (a) the UE has reserved the home PLMN in the home country, and (b) the UE has not made any request for the list.

13. The method of claim 10, further comprising: When roaming in the given country, the UE sends an access request to the authorization server, wherein the access request includes an indication of the UE's location and an identifier of the given network slice, wherein the list is received after the access request has been sent.

14. A non-transitory memory medium storing program instructions, wherein the program instructions, when executed by a processing element, cause a user equipment (UE) to perform: The UE sends a registration request to its home public land mobile network (PLMN), the registration request including a requested single network slice selection assistance information (S-NSSAI) value associated with a given network slice. After the registration request has been sent, a list of multiple PLMNs that support the given network slice in a given country is received, wherein the given country is different from the home country of the UE’s home PLMN, wherein the given network slice is supported in the home PLMN, and wherein the requested S-NSSAI value includes information elements indicating whether the list of multiple PLMNs is requested. as well as In response to determining that the UE is located in the given country and wishes to access the given network slice, it accesses a PLMN in the list to use the given network slice.

15. The non-transitory memory medium according to claim 14, wherein the registration request includes: Includes the identifiers of one or more roaming countries for the given country.

16. The non-transitory memory medium of claim 14, wherein the list is received from the home PLMN of the UE when: (a) the UE has reserved the home PLMN in the home country, and (b) the UE has not made any request for the list.

17. The non-transitory memory medium of claim 14, wherein the program instructions, when executed by the processing element, cause the UE to perform: When roaming in the given country, the UE sends an access request to the authorization server, wherein the access request includes an indication of the UE's location and an identifier of the given network slice, wherein the list is received after the access request has been sent.

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