Systems and methods associated with dynamic mobile network selection

Abstract

Described herein are systems, methods, and instrumentalities associated with dynamic policy updates, A wireless transmit / receive unit (WTRU) (e.g., a roaming WTRU) may receive steering of roaming (SoR) information and / or information regarding a mobile network search timer. The SoR information may indicate at least a first mobile network and a second mobile network. The WTRU may receive a first message from the first mobile network indicating a congestion condition associated with the first mobile network and a back-off timer. The WTRU may start the mobile network search timer and the back-off timer. Based on a determination that the mobile network search timer has expired before the expiration of the back-off timer, the WTRU may initiate a mobile network selection procedure, wherein the second mobile network may be selected as a result of the mobile network selection procedure.

Description

I5GCN_2023P00645WO PATENT SYSTEMS AND METHODS ASSOCIATED WITH DYNAMIC MOBILE NETWORK SELECTION CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No.63 / 530,189, filed August 1, 2023, the disclosure of which is incorporated herein by reference in its entirety. BACKGROUND

[0002] A large number of wireless transmit / receive units (WTRUs) (e.g., roaming WTRUs) may cause congestion in a wireless communication network such as a visited public land mobile network (VPLMN), and the WTRUs may be stuck with the congested network while another network in the visited location may be available to provide services to the WTRUs. Systems and methods are desirable to handle these situations. SUMMARY

[0003] Described herein are systems, methods, and instrumentalities associated with slice-based mobile network selection. A wireless transmit / receive unit (WTRU) as described herein may be configured to receive information that may indicate that a network slice may be available via at least a first mobile network and a second mobile network. The WTRU may be further configured to send a message to the first mobile network and receive a response from the first mobile network. The message sent to the first mobile network may indicate the network slice, and the response received from the first mobile network may indicate that the first mobile network is congested. The response may further indicate a back-off time period associated with accessing the first mobile network. Upon receiving the response, the WTRU may be configured to start monitoring for an expiration of the back-off time period and an expiration of a network search time period. After the expiration of the network search time period but before the expiration of the back-off time period, the WTRU may send a registration request associated with the network slice to the second mobile network.

[0004] In examples, the information received by the WTRU that indicates the network slice availability may further indicate the network search time period. In examples, the information received by the WTRU may further indicate that the first mobile network has a higher priority than the second mobile network, and the WTRU may send the message to the first mobile network based on the indication.

[0005] In examples, the message sent to the first mobile network may include a request to register with the first mobile network or to establish a protocol data unit (PDU) session via the first mobile network. In examples, after the expiration of the back-off time period, the WTRU may be configured to re-send the request to register with the first mobile network or to establish the PDU session via the first mobile network.I5GCN_2023P00645WO PATENT

[0006] In examples, the information received by the WTRU that indicates the network slice availability may be received from a home public land mobile network (HPLMN) and may include steering of roaming (SoR) information. In examples, at least one of the first mobile network or the second mobile network may be a visitor public land mobile network (VPLMN).

[0007] In examples, the registration request sent by the WTRU to the second mobile network may include assistance information associated with the network slice (e.g., the assistance information may include single network slice selection assistance information (S-NSSAI)). In examples, the WTRU may monitor for the expiration of the back-off time period and the expiration of the network search time period by starting a first timer associated with the back-off time period and a second timer associated with the network search time period.

[0008] In examples, the WTRU may be further configured to search for the second mobile network after the expiration of the network search time period and before the expiration of the back-off time period. In examples, the registration request sent to the second mobile network may include information about a rejection cause (e.g., a rejection cause code) associated with the first mobile network.

[0009] A network device (e.g., a mobile network device such as a VPLMN device) as described herein may be configured to receive, from a WTRU, a first request to access a network slice provided by the mobile network and determine that the mobile network may be congested with respect to the network slice. The network device may then send a response to the WTRU, wherein the response may indicate that the mobile network is congested and further indicate a time period for the WTRU to refrain from accessing the mobile network for the network slice. After the expiration of the time period, the network device may receive a second request from the WTRU to access the network slice provided by the mobile network. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG.1A is a system diagram illustrating an example communications system in which one or more disclosed embodiments can be implemented.

[0011] FIG.1B is a system diagram illustrating an example wireless transmit / receive unit (WTRU) that can be used within the communications system illustrated in FIG.1A according to an embodiment.

[0012] FIG.1C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that can be used within the communications system illustrated in FIG.1A according to an embodiment.I5GCN_2023P00645WO PATENT

[0013] FIG.1D is a system diagram illustrating a further example RAN and a further example CN that can be used within the communications system illustrated in FIG.1A according to an embodiment.

[0014] FIG.2 illustrates an example of configuring and using a PLMN search time period.

[0015] FIG.3 illustrates an example of using a PLMN search time period.

[0016] FIG.4 illustrates example operations associated with a registration rejection in a VPLMN. DETAILED DESCRIPTION

[0017] A more detailed understanding can be had from the following description, given by way of example in conjunction with the accompanying drawings.

[0018] FIG.1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments can be implemented. The communications system 100 can be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 can enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 can employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single- carrier FDMA (SC-FDMA), zero-tail unique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0019] As shown in FIG.1A, the communications system 100 can include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a RAN 104 / 113, a CN 106 / 115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d can be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which can be referred to as a “station” and / or a “STA”, can be configured to transmit and / or receive wireless signals and can include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercialI5GCN_2023P00645WO PATENT and / or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d can be interchangeably referred to as a UE.

[0020] The communications systems 100 can include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b can be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106 / 115, the Internet 110, and / or the other networks 112. By way of example, the base stations 114a, 114b can be a base transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B, a gNB, a NR NodeB, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b can include any number of interconnected base stations and / or network elements.

[0021] The base station 114a can be part of the RAN 104 / 113, which can also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and / or the base station 114b can be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which can be referred to as a cell (not shown). These frequencies can be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell can provide coverage for a wireless service to a specific geographical area that can be relatively fixed or that can change over time. The cell can further be divided into cell sectors. For example, the cell associated with the base station 114a can be divided into three sectors. Thus, in one embodiment, the base station 114a can include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station 114a can employ multiple-input multiple output (MIMO) technology and can utilize multiple transceivers for each sector of the cell. For example, beamforming can be used to transmit and / or receive signals in desired spatial directions.

[0022] The base stations 114a, 114b can communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which can be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 can be established using any suitable radio access technology (RAT).

[0023] More specifically, as noted above, the communications system 100 can be a multiple access system and can employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104 / 113 and the WTRUs 102a, 102b, 102c can implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which can establish the air interface 115 / 116 / 117 using wideband CDMA (WCDMA). WCDMAI5GCN_2023P00645WO PATENT can include communication protocols such as High-Speed Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA can include High-Speed Downlink (DL) Packet Access (HSDPA) and / or High-Speed UL Packet Access (HSUPA).

[0024] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which can establish the air interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro).

[0025] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can implement a radio technology such as NR Radio Access, which can establish the air interface 116 using New Radio (NR).

[0026] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c can implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles. Thus, the air interface utilized by WTRUs 102a, 102b, 102c can be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., an eNB and a gNB).

[0027] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c can implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA20001X, CDMA2000 EV-DO, Interim Standard 2000 (IS- 2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

[0028] The base station 114b in FIG.1A can be a wireless router, Home Node B, Home eNode B, or access point, for example, and can utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d can implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d can implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d can utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. As shown in FIG.1A, the base station 114b can have a direct connection to the Internet 110. Thus, the base station 114b cannot be required to access the Internet 110 via the CN 106 / 115.I5GCN_2023P00645WO PATENT

[0029] The RAN 104 / 113 can be in communication with the CN 106 / 115, which can be any type of network configured to provide voice, data, applications, and / or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data can have varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106 / 115 can provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not shown in FIG.1A, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 can be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which can be utilizing a NR radio technology, the CN 106 / 115 can also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0030] The CN 106 / 115 can also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or the other networks 112. The PSTN 108 can include circuit-switched telephone networks that provide plain old telephone service (POTS). The Internet 110 can include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP) and / or the internet protocol (IP) in the TCP / IP internet protocol suite. The networks 112 can include wired and / or wireless communications networks owned and / or operated by other service providers. For example, the networks 112 can include another CN connected to one or more RANs, which can employ the same RAT as the RAN 104 / 113 or a different RAT.

[0031] One or more (e.g., all) of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 can include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d can include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG.1A can be configured to communicate with the base station 114a, which can employ a cellular- based radio technology, and with the base station 114b, which can employ an IEEE 802 radio technology.

[0032] FIG.1B is a system diagram illustrating an example WTRU 102. As shown in FIG.1B, the WTRU 102 can include a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138, among others. It will be appreciated that WTRU 102 can include any sub-combination of the foregoing elements while remaining consistent with an embodiment.I5GCN_2023P00645WO PATENT

[0033] The processor 118 can be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 can perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 can be coupled to the transceiver 120, which can be coupled to the transmit / receive element 122. While FIG.1B depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 can be integrated together in an electronic package or chip.

[0034] The transmit / receive element 122 can be configured to transmit signals to, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 can be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 can be an emitter / detector configured to transmit and / or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit / receive element 122 can be configured to transmit and / or receive both RF and light signals. It will be appreciated that the transmit / receive element 122 can be configured to transmit and / or receive any combination of wireless signals.

[0035] Although the transmit / receive element 122 is depicted in FIG.1B as a single element, the WTRU 102 can include any number of transmit / receive elements 122. More specifically, the WTRU 102 can employ MIMO technology. Thus, in one embodiment, the WTRU 102 can include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0036] The transceiver 120 can be configured to modulate the signals that are to be transmitted by the transmit / receive element 122 and to demodulate the signals that are received by the transmit / receive element 122. As noted above, the WTRU 102 can have multi-mode capabilities. Thus, the transceiver 120 can include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11, for example.

[0037] The processor 118 of the WTRU 102 can be coupled to, and can receive user input data from, the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or organic light-emitting diode (OLED) display unit). The processor 118 can also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 can access information from, and store data in, any type of suitable memory, such as the non-removableI5GCN_2023P00645WO PATENT memory 130 and / or the removable memory 132. The non-removable memory 130 can include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 can include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 can access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0038] The processor 118 can receive power from the power source 134, and can be configured to distribute and / or control the power to the other components in the WTRU 102. The power source 134 can be any suitable device for powering the WTRU 102. For example, the power source 134 can include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li- ion), etc.), solar cells, fuel cells, and the like.

[0039] The processor 118 can also be coupled to the GPS chipset 136, which can be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to, or in lieu of, the information from the GPS chipset 136, the WTRU 102 can receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and / or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 can acquire location information by way of any suitable location-determination method while remaining consistent with an embodiment.

[0040] The processor 118 can further be coupled to other peripherals 138, which can include one or more software and / or hardware modules that provide additional features, functionality and / or wired or wireless connectivity. For example, the peripherals 138 can include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photographs and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a Virtual Reality and / or Augmented Reality (VR / AR) device, an activity tracker, and the like. The peripherals 138 can include one or more sensors, the sensors can be one or more of a gyroscope, an accelerometer, a hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0041] The WTRU 102 can include a full duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for both the UL (e.g., for transmission) and downlinkI5GCN_2023P00645WO PATENT (e.g., for reception) can be concurrent and / or simultaneous. The full duplex radio can include an interference management unit to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WTRU 102 can include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e.g., for transmission) or the downlink (e.g., for reception)).

[0042] FIG.1C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As noted above, the RAN 104 can employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 can also be in communication with the CN 106.

[0043] The RAN 104 can include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 can include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c can each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c can implement MIMO technology. Thus, the eNode-B 160a, for example, can use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a.

[0044] Each of the eNode-Bs 160a, 160b, 160c can be associated with a particular cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, and the like. As shown in FIG.1C, the eNode-Bs 160a, 160b, 160c can communicate with one another over an X2 interface.

[0045] The CN 106 shown in FIG.1C can include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements are depicted as part of the CN 106, it will be appreciated that any of these elements can be owned and / or operated by an entity other than the CN operator.

[0046] The MME 162 can be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and can serve as a control node. For example, the MME 162 can be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 162 can provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.I5GCN_2023P00645WO PATENT

[0047] The SGW 164 can be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via the S1 interface. The SGW 164 can generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 can perform other functions, such as anchoring user planes during inter-eNode B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0048] The SGW 164 can be connected to the PGW 166, which can provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0049] The CN 106 can facilitate communications with other networks. For example, the CN 106 can provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 can include, or can communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 can provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which can include other wired and / or wireless networks that are owned and / or operated by other service providers.

[0050] Although the WTRU is described in FIGS.1A-1D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal can use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

[0051] In representative embodiments, the other network 112 can be a WLAN.

[0052] A WLAN in Infrastructure Basic Service Set (BSS) mode can have an Access Point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP can have an access or an interface to a Distribution System (DS) or another type of wired / wireless network that carries traffic in to and / or out of the BSS. Traffic to STAs that originates from outside the BSS can arrive through the AP and can be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS can be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS can be sent through the AP, for example, where the source STA can send traffic to the AP and the AP can deliver the traffic to the destination STA. The traffic between STAs within a BSS can be considered and / or referred to as peer-to-peer traffic. The peer-to- peer traffic can be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS can use an 802.11e DLS or an 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode cannot have an AP, and the STAs (e.g., all ofI5GCN_2023P00645WO PATENT the STAs) within or using the IBSS can communicate directly with each other. The IBSS mode of communication can sometimes be referred to herein as an “ad-hoc” mode of communication.

[0053] When using the 802.11ac infrastructure mode of operation or a similar mode of operations, the AP can transmit a beacon on a fixed channel, such as a primary channel. The primary channel can be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling. The primary channel can be the operating channel of the BSS and can be used by the STAs to establish a connection with the AP. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) can be implemented, for example in 802.11 systems. For CSMA / CA, the STAs (e.g., every STA), including the AP, can sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA can back off. One STA (e.g., only one station) can transmit at any given time in a given BSS.

[0054] High Throughput (HT) STAs can use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHz wide channel.

[0055] Very High Throughput (VHT) STAs can support 20MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. The 40 MHz, and / or 80 MHz, channels can be formed by combining contiguous 20 MHz channels. A 160 MHz channel can be formed by combining 8 contiguous 20 MHz channels, or by combining two non- contiguous 80 MHz channels, which can be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, can be passed through a segment parser that can divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing, and time domain processing, can be done on each stream separately. The streams can be mapped on to the two 80 MHz channels, and the data can be transmitted by a transmitting STA. At the receiver of the receiving STA, the above described operation for the 80+80 configuration can be reversed, and the combined data can be sent to the Medium Access Control (MAC).

[0056] Sub 1 GHz modes of operation are supported by 802.11af and 802.11ah. The channel operating bandwidths, and carriers, are reduced in 802.11af and 802.11ah relative to those used in 802.11n, and 802.11ac.802.11af supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah can support Meter Type Control / Machine-Type Communications, such as MTC devices in a macro coverage area. MTC devices can have certain capabilities, for example, limited capabilities including support for (e.g., only support for) certain and / or limited bandwidths.I5GCN_2023P00645WO PATENT The MTC devices can include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0057] WLAN systems, which can support multiple channels, and channel bandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include a channel which can be designated as the primary channel. The primary channel can have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel can be set and / or limited by a STA, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In the example of 802.11ah, the primary channel can be 1 MHz wide for STAs (e.g., MTC type devices) that support (e.g., only support) a 1 MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or Network Allocation Vector (NAV) settings can depend on the status of the primary channel. If the primary channel is busy, for example, due to a STA (which supports only a 1 MHz operating mode), transmitting to the AP, the entire available frequency bands can be considered busy even though a majority of the frequency bands remains idle and can be available.

[0058] In the United States, the available frequency bands, which can be used by 802.11ah, are from 902 MHz to 928 MHz. In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.11ah is 6 MHz to 26 MHz depending on the country code.

[0059] FIG.1D is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As noted above, the RAN 113 can employ an NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 can also be in communication with the CN 115.

[0060] The RAN 113 can include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 can include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c can each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c can implement MIMO technology. For example, gNBs 180a, 108b can utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a, for example, can use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c can implement carrier aggregation technology. For example, the gNB 180a can transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers can be on unlicensed spectrum while the remaining component carriers can be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180cI5GCN_2023P00645WO PATENT can implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a can receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0061] The WTRUs 102a, 102b, 102c can communicate with gNBs 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing can vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c can communicate with gNBs 180a, 180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing varying number of OFDM symbols and / or lasting varying lengths of absolute time).

[0062] The gNBs 180a, 180b, 180c can be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In the standalone configuration, WTRUs 102a, 102b, 102c can communicate with gNBs 180a, 180b, 180c without also accessing other RANs (e.g., such as eNode-Bs 160a, 160b, 160c). In the standalone configuration, WTRUs 102a, 102b, 102c can utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c can communicate with gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration WTRUs 102a, 102b, 102c can communicate with / connect to gNBs 180a, 180b, 180c while also communicating with / connecting to another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b, 102c can implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non- standalone configuration, eNode-Bs 160a, 160b, 160c can serve as a mobility anchor for WTRUs 102a, 102b, 102c and gNBs 180a, 180b, 180c can provide additional coverage and / or throughput for servicing WTRUs 102a, 102b, 102c.

[0063] Each of the gNBs 180a, 180b, 180c can be associated with a particular cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards User Plane Function (UPF) 184a, 184b, routing of control plane information towards Access and Mobility Management Function (AMF) 182a, 182b and the like. As shown in FIG.1D, the gNBs 180a, 180b, 180c can communicate with one another over an Xn interface.

[0064] The CN 115 shown in FIG.1D can include at least one AMF 182a, 182b, at least one UPF 184a,184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the foregoing elements are depicted as part of the CN 115, it will be appreciated that any of these elements can be owned and / or operated by an entity other than the CN operator.I5GCN_2023P00645WO PATENT

[0065] The AMF 182a, 182b can be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and can serve as a control node. For example, the AMF 182a, 182b can be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling of different PDU sessions with different requirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of NAS signaling, mobility management, and the like. Network slicing can be used by the AMF 182a, 182b in order to customize CN support for WTRUs 102a, 102b, 102c based on the types of services being utilized WTRUs 102a, 102b, 102c. For example, different network slices can be established for different use cases such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, and / or the like. The AMF 162 can provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies such as WiFi.

[0066] The SMF 183a, 183b can be connected to an AMF 182a, 182b in the CN 115 via an N11 interface. The SMF 183a, 183b can also be connected to a UPF 184a, 184b in the CN 115 via an N4 interface. The SMF 183a, 183b can select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b can perform other functions, such as managing and allocating WTRU IP address, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, and the like. A PDU session type can be IP-based, non-IP based, Ethernet-based, and the like.

[0067] The UPF 184a, 184b can be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, which can provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP- enabled devices. The UPF 184, 184b can perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, and the like.

[0068] The CN 115 can facilitate communications with other networks. For example, the CN 115 can include, or can communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 can provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which can include other wired and / or wireless networks that are owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c can be connected to a local Data Network (DN) 185a, 185b through the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.I5GCN_2023P00645WO PATENT

[0069] In view of Figures 1A-1D, and the corresponding description of Figures 1A-1D, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b, eNode-B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-b, UPF 184a-b, SMF 183a-b, DN 185a-b, and / or any other device(s) described herein, can be performed by one or more emulation devices (not shown). The emulation devices can be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices can be used to test other devices and / or to simulate network and / or WTRU functions.

[0070] The emulation devices can be designed to implement one or more tests of other devices in a lab environment and / or in an operator network environment. For example, the one or more emulation devices can perform the one or more, or all, functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. The one or more emulation devices can perform the one or more, or all, functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The emulation device can be directly coupled to another device for purposes of testing and / or can perform testing using over-the-air wireless communications.

[0071] The one or more emulation devices can perform the one or more, including all, functions while not being implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices can be utilized in a testing scenario in a testing laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network in order to implement testing of one or more components. The one or more emulation devices can be testing equipment. Direct RF coupling and / or wireless communications via RF circuitry (e.g., which can include one or more antennas) can be used by the emulation devices to transmit and / or receive data.

[0072] As described herein, a WTRU may include a terminal equipment (TE) part and / or a mobile termination (MT) part. The TE part of the WTRU may run applications that may use a mobile network to send and receive data. The MT part of the WTRU may include modem logic that may be used to communicate with the mobile network. Functionality in the TE part of the WTRU may use AT (Attention) commands to communicate with logics in the MT part of the WTRU.

[0073] A registration area associated with a WTRU and / or a network device may include a set of tracking areas. The registration area may be defined by a tracking area identity (TAI) list (e.g., a list of tracking areas). If a WTRU registers with a network (e.g., by sending a registration request to an AMF), the network (e.g., an AMF) may allocate a registration area (e.g., a set of tracking areas in a TAI List) to the WTRU and may obtainI5GCN_2023P00645WO PATENT information regarding the WTRU such as the WTRU’s expected mobility pattern (e.g., when the AMF allocates the TAI list).

[0074] When referred to herein, configured network slice selection assistance information (NSSAI) for a WTRU may indicate a list and / or collection of slices that the WTRU may access. The WTRU may receive such configured NSSAI in a registration accept / response message, a configuration update message, etc. When referred to herein, requested NSSAI may include or indicate a list and / or collection of slices that a WTRU may want to access. The WTRU may send such requested NSSAI to a network device (e.g., in order to register with one or more of the slices indicated in the requested NSSAI). The WTRU may send the requested NSSAI to the network device in a registration request message, for example.

[0075] When referred to herein, allowed NSSAI may indicate a list and / or collection of slices that a WTRU may access (e.g., use) in the WTRU’s registration area. When referred to herein, rejected NSSAI (e.g., single NSSAI (S-NSSAI) may indicate a slice that the WTRU has included in requested NSSAI, but has been determined by a network device to be inaccessible to the WTRU. Such rejected NSSAI may be included in an information element sent to the WTRU from the network device (e.g., in a registration accept message or a configuration update message).

[0076] When referred to herein, attempting to register with a slice may mean including or indicating a slice (e.g., such as S-NSSAI associated with the slice) in a requested NSSAI. Further, the terms “slice” and “S- NSSAI” may be used interchangeably herein. The terms “slice” and “network slice” may also be used interchangeably herein.

[0077] A WTRU may provide in requested NSSAI one or more S-NSSAIs that may not be a part of allowed NSSAI or rejected NSSAI. In such a situation, the WTRU may not regard the one or more S-NSSAIs as rejected S-NSSAI(s) and may request to register the S-NSSAI(s) (e.g., when the WTRU sends the requested NSSAI).

[0078] If a WTRU is registered with a slice, the WTRU may use resources associated with that slice. For example, the WTRU may send periodic NAS messages to an AMF which may be part of the slice. The WTRU may or may not use user plane resources of the slice or other resources of the slice (e.g., resources associated with SMS and / or location services).

[0079] A WTRU may select and register with one or more slices (e.g., up to 8 slices with associated S- NSSAIs) from configured NSSAI. When selecting a slice to register with, the WTRU may send a registrationI5GCN_2023P00645WO PATENT request to the network (e.g., to a network device such as an SMF). A requested NSSAI information element of the registration request may include the slice selected by the WTRU for registration.

[0080] Various events may trigger a WTRU to send a registration request associated with a slice. As examples, the triggering events may include one or more of the following. The WTRU may be configured to always attempt to register with a slice unless the WTRU is aware that the slice is not available. The WTRU may be configured to attempt to register with a slice after (e.g., immediately or shortly after) powering up. The WTRU may be configured to attempt to register with slice when the WTRU registers with a certain PLMN. The WTRU may be configured to attempt to register with a slice when certain application traffic starts. The WTRU may be configured to attempt to register with a slice if the WTRU is in a certain location. The WTRU may be configured to attempt to register with a slice if certain applications are installed and / or running on the WTRU. The WTRU may be configured to attempt to register with a slice when prompted (e.g., by a user via a user interface such as a graphical user interface or GUI). For example, the WTRU may attempt to register with a slice if a user indicates, via a GUI, that a certain service is requested.

[0081] Various events may trigger the establishment of PDU sessions. For example, after a WTRU is registered with a slice, the WTRU may establish a PDU session in the slice. The WTRU may establish the PDU session by sending a PDU session establishment request to the network. The PDU session establishment request (e.g., an NAS-SM message) may be sent to a session management function (SMF) of the slice (a network slice may be referred to herein as a slice). The PDU session establishment request may include an S- NSSAI that may be associated with the PDU session and / or a DNN that may be associated with the PDU session. If an S-NSSAI is not included in the PDU session establishment request, the network may determine an S-NSSAI for the PDU session. If a DNN is not included in the PDU session establishment request, the network may determine a DNN for the PDU session.

[0082] Various events may trigger a WTRU to send a PDU session establishment request to the network. As examples, the triggering events may include one or more of the following. A WTRU hosted application may request that the WTRU establish a PDU session. The request from the WTRU hosted application may include a DNN and / or an S-NSSAI, and the WTRU may send the DNN and / or S-NSSAI to the network in the PDU session establishment request. For example, a component hosted in a TE part of the WTRU may invoke an AT command (e.g., +CGDCONT) to request that a component hosted in an MT part of the WTRU send a PDU session establishment request to the network.

[0083] A WTRU hosted application may generate uplink traffic that may cause the WTRU to evaluate UE route selection policy (URSP) rules to determine the characteristics of a requested PDU session via which theI5GCN_2023P00645WO PATENT uplink traffic may be sent to the network. As a result of the URSP evaluation, the WTRU may determine to use an existing PDU session or establish a new PDU session to send the uplink traffic to the network. If the WTRU determines to establish a new PDU session, the WTRU may send a PDU session establishment request to the network and the URSP rules may be used to determine what DNN and / or S-NSSAI to include in the PDU session establishment request.

[0084] A WTRU may be configured with a combination of DNN / S-NSSAI, and the WTRU may establish a PDU session associated with the DNN / S-NSSAI combination if the WTRU is registered with the S-NSSAI in the DNN / S-NSSAI combination. In some examples, the WTRU may choose to establish a PDU session even if it is not used by any WTRU application to send or receive traffic.

[0085] A WTRU may receive a device trigger for the WTRU to establish a PDU session. The device trigger may be included in an NAS message and / or an SMS message, which may include a DNN and / or an S-NSSAI that the WTRU may include in a PDU session establishment request.

[0086] A network slice admission control function (NSACF) may monitor and / or control the number of registered WTRUs per network slice and / or the number of PDU sessions per network slice for the network slices that may be subject to network slice admission control (NSAC). The NSACF may be configured with a maximum number of WTRUs and / or a maximum number of PDU sessions that may be served per S-NSSAI (e.g., for the network slices that are subject to NSAC). The NSACF may be configured with information indicating applicable access type(s) for a S-NSSAI (e.g., 3GPP access type(s) and / or non-3GPP access type(s)). The NSACF may keep track of the current number of WTRUs registered for a network slice to ensure that the number of registered WTRUs does not exceed the maximum number of WTRUs allowed to register with the network slice.

[0087] A network device or function, such as an AMF, may trigger a request to an NSACF for NSAC for a number of WTRUs (e.g., a maximum number of WTRUs) if those WTRUs’ registration status for a network slice subject to NSAC is changing. This operation may occur, for example, during a WTRU registration procedure, during a WTRU deregistration procedure, during a network slice-specific authentication and / or authorization procedure, during an AAA (Authentication, Authorization, and Accounting) server triggered network slice-specific re-authentication and re-authorization procedure, during an AAA server triggered slice- specific authorization revocation procedure, and / or during a WTRU configuration update procedure.

[0088] If the maximum number of registrations for a slice has been reached, the NSACF may indicate to the AMF that a request to register with a slice may be rejected. A cause code may be provided to a WTRU indicating that its slice registration was rejected because the maximum number of registrations for the slice hasI5GCN_2023P00645WO PATENT been reached. Information regarding a back-off time period (e.g., implemented via a back-off timer) may be sent to the WTRU and used by the WTRU to determine if the WTRU may try to register with the slice again.

[0089] The NSACF may keep track of the current number of PDU sessions per network slice to ensure that it does not exceed the maximum number of PDU sessions allowed to be served by the network slice. If an event related to a WTRU causes the current number of PDU sessions established within the network slice to increase, the NSACF may check whether the maximum number of PDU sessions per network slice for that network slice has been reached and if it has, the NSACF may apply an admission control policy.

[0090] If the maximum number of PDU sessions for a slice has been reached, the NSACF may indicate to another network device or function such as an SMF that a PDU session establishment request may be rejected, and a cause code may be provided to the WTRU. Such a cause code may indicate that the PDU session was rejected because the maximum number of PDU sessions for the slice has been reached. Information regarding a back-off time period (e.g., implemented via a back-off timer) may be sent to a WTRU and the back-off time period may be used by the WTRU to detect when the WTRU may try to establish a PDU session in the slice again. An anchor SMF may request the NSACF to provide information regarding a maximum number of PDU sessions per network slice control during a PDU session establishment / release procedure.

[0091] Congestion control may be performed at an NAS level. The congestion control may be applied in general (e.g., for all NAS messages), per DNN and / or S-NSSAI, or for a specific group of WTRUs. The congestion control may be achieved by providing the WTRU with a back-off time period (e.g., via a timer T3346). To avoid a large number of WTRUs initiating deferred requests simultaneously, the network (e.g., core network) may select (e.g., for each WTRU) a back-off time period (e.g., a back-off timer value) so that deferred requests (e.g., by multiple WTRUs) may be space apart rather than synchronized. If a WTRU receives a back- off time period value, the WTRU may not initiate NAS signaling with regards to applied congestion control until the back-off time period expires, until the WTRU receives a mobile terminated request from the network, until the WTRU initiates signaling for emergency services or a high priority access, or until the WTRU enters a new PLMN that may not be part of an equivalent PLMN list.

[0092] Under an overload condition, an AMF may reject NAS messages from WTRUs that are using an access network (e.g., the rejection may be associated with cause code #22 for congestion). If an NAS request is rejected, the AMF may provide a mobility management back-off time period (e.g., a back-off timer value) to the corresponding WTRU. During the back-off time period (e.g., while the mobility management back-off timer is running on the WTRU), the WTRU may not initiate an NAS request, for example, except for a deregistrationI5GCN_2023P00645WO PATENT procedure and / or procedures that may not be subject to congestion control (e.g., for high priority access, emergency services, and / or mobile terminated services). If the WTRU receives a paging request or an NAS notification message from the AMF while the mobility management back off timer is running, the WTRU may stop the mobility management back-off timer and may initiate a service request procedure or a mobility registration update procedure over a 3GPP access and / or a non-3GPP access as applicable.

[0093] DNN based congestion control may be designed and / or implemented to avoid and / or handle congestion (e.g., NAS session management signaling congestion) for WTRUs. DNN based congestion control may involve configuring and / or sending a back-off time period (e.g., via a back-off timer value) from the network to a WTRU. The back-off time period may be associated with a DNN. The back-off time period may indicate how long the WTRU should wait before generating NAS Session Management signaling associated with the DNN. DNN based congestion control may be applied regardless of whether or not an S-NSSAI is present in the NAS SM signaling message that is sent from the WTRU.

[0094] A network device or function such as an SMF may apply DNN based congestion control towards a WTRU by rejecting a PDU session establishment request message and / or a PDU session modification request message from the WTRU (e.g., except for request messages sent for purposes of reporting a 3GPP packet switch (PS) data off status change for a specific DNN with a running back-off timer). The SMF may release one or more PDU sessions belonging to a congested DNN by sending a PDU session release command message to the WTRU with a DNN back-off time period (e.g., timer T3396). If the DNN back-off timer is included in the PDU session release command message, a cause value indicating “reactivation requested” may not be set.

[0095] If the DNN based congestion control is activated at an AMF (e.g., via operations, administration and maintenance (OAM) configuration), the AMF may provide a NAS transport error message for an NAS transport message that may carry an SM message. The NAS transport error message may include or indicate a DNN back-off time period (e.g., timer T3396).

[0096] S-NSSAI based congestion control may be designed and / or implemented to avoid and / or to handle congestion (e.g., NAS signaling congestion) for WTRUs that may or may not be associated with an S-NSSAI regardless of the presence of a DNN. This may be done, for example, by configuring and / or using a back-off time period (e.g., a back-off timer). If the S-NSSAI based congestion control is activated at an AMF (e.g., via OAM configuration) and an S-NSSAI is determined as congested, the AMF may apply the S-NSSAI based congestion control towards a WTRU for a WTRU-initiated session management request. In this case, the AMF may provide an NAS transport error message for the NAS transport message that may carry the SM message. The NAS transport error message may include / indicate a back-off time period (e.g., for timer T3584 and / orI5GCN_2023P00645WO PATENT T3585) and / or one or more rejection causes (e.g., cause #67 for insufficient resources for a specific slice and / or a DNN, cause #69 for insufficient resources for a specific slice, etc.).

[0097] A WTRU may associate a configured / received back-off time period (e.g., for timer T3584 and / or T3585) with an S-NSSAI and / or a DNN (e.g., the WTRU may have no S-NSSAI or DNN, may have no S- NSSAI, may have S-NSSAI only, or may have an S-NSSAI and a DNN). The S-NSSAI and / or a DNN may have been indicated / included in an uplink NAS mobility management (MM) message that carries an NAS session management (SM) request message for a congested PLMN (e.g., a congested S-NSSAI or DNN). The back-off time period value may be received, for example, in a downlink NAS mobility management (MM) message that may be sent from an AMF to the WTRU.

[0098] A WTRU such as a roaming WTRU may be registered with a VPLMN. The WTRU may request access to a network slice (e.g., in order to access a service and / or an application) that may not be offered by the VPLMN or may not be accessible via that VPLMN. An HPLMN may send information (e.g., slice aware SoR information) to the WTRU (e.g., the roaming WTRU). The information (e.g., slice aware SoR information) may include / indicate one or more (e.g., preferred) PLMNs for one or more specific S-NSSAIs. The specific S- NSSAIs may be part of the WTRU’s subscription.

[0099] If a WTRU is camped in a VPLMN and attempts to access a network slice that may not be available via the VPLMN, the WTRU may perform a PLMN selection procedure. The WTRU may use information such as slice aware SoR information to determine which PLMN(s) to prioritize in the PLMN search procedure. For example, the WTRU may prioritize PLMNs associated with a network slice as indicated by the slice aware SoR information. As a result of the PLMN selection procedure, the WTRU may perform a registration procedure with a PLMN that may support the network slice. The WTRU may attempt to establish a PDU session in the network slice (e.g., while or after registering with the PLMN).

[0100] During a registration or PDU establishment procedure, the WTRU may receive an indication or a response from a network indicating that the network may be congested. The WTRU may refrain from accessing the network for a back-off time period (e.g., by running a back-off timer) in response to being informed about the congestion situation. In an example approach, the WTRU may not perform a PLMN search during the back-off time period. Such an approach, however, may be inefficient because it may result in a situation where slice aware SoR information may steer the WTRU to register with a PLMN with an expectation that a slice may be available in the PLMN, but the WTRU may be forced to wait for the back-off time period to expire before the WTRU may perform the PLMN search. The WTRU may be caught in this situation even if theI5GCN_2023P00645WO PATENT slice aware SoR information includes / indicates the identity of another PLMN that may not be congested and / or may offer access to the network slice.

[0101] In a scenario where a large number of WTRUs (e.g., roaming WTRUs) are configured to apply slice- based PLMN selection, an overload may occur in a VPLMN (e.g., taking into consideration that the WTRUs may use slice-aware SoR information to camp on the VPLMN), and the WTRUs may be rejected by the VPLMN with a cause related to the congestion (e.g., cause #22 for congestion, cause #67 for insufficient resources for specific slice and DNN, cause #69 for insufficient resources for specific slice, etc.). This may result in a large number of WTRUs (e.g., roaming WTRUs) being stuck with the congested VPLMN and the congestion may limit uplink traffic (e.g., uplink signaling) associated with a slice, while downlink (DL) signaling from the slice may still be possible. Similar issues may exist for a VPLMN selection that is based on SoR information (e.g., provided by an HPLMN / UDM) and / or for updates of operator controlled prioritized lists of PLMNs (OPLMN lists). For example, if congestion occurs, a WTRU (e.g., a roaming WTRU) may be stuck with a congested VPLMN without an HPLMN being aware of it, even though another VPLMN in the visited area may not be congested and may be able to provide services to the WTRU.

[0102] A WTRU may use information (e.g., slice-aware SoR information) provided by another device or entity (e.g., a network device) to make slice-based network (e.g., VPLMN) selection. The WTRU may select the actions to take in a congestion situation (e.g., a congestion associated with a PLMN) based on information that may be included in the provided information (e.g., slice-aware SoR information). Such information (e.g., slice- aware SoR information) may be provided by an HPLMN, a UDM, and / or the like.

[0103] A network (e.g., an HPLMN) may provide steering related information such as slice-aware SoR information to a WTRU (e.g., a roaming WTRU). The slice aware SoR information may indicate one or more PLMNs (e.g., preferred PLMNs) for an S-NSSAI (e.g., a network slice) that may be in the WTRU’s subscription. The WTRU may be configured to support slice-based PLMN selection and may ensure, during a cell selection process (e.g., an initial cell selection process at power up or a recovery process arising from a lack of coverage), that the WTRU may select a suitable (e.g., the highest priority) network for one or more selected slices based on the received slice-aware SoR information. In examples, if the most suitable network (e.g., the highest priority network) is not available, the WTRU may camp on the next suitable (e.g., a lower priority) network based on a certain order (e.g., a priority order) of the available networks. The one or more selected network slices may be a subset of the network slices listed in a configured NSSAI. The WTRU may determine the one or more selected slice based on configuration information.I5GCN_2023P00645WO PATENT

[0104] An HPLMN or UDM may provide additional information (e.g., along with slice-aware SoR information) to a WTRU that may assist the WTRU with VPLMN selection (e.g., if a registration request by the WTRU to a certain VPLMN is rejected by that VPLMN). The additional information may include information regarding a PLMN search start time period (e.g., a PLMN search start timer) that the WTRU may start if it receives an indication of a back-off time period (e.g., a back-off timer value) from a network (e.g., a congested network that the WTRU is trying to access). The WTRU may stop the PLMN search start time period (e.g., the PLMN search start timer) if the WTRU determines that the back-off time period has expired (e.g., if the WTRU stops the back-off timer). The expiration of the back-off time period may prompt the WTRU to re-send a request to register with the congested network or to establish a PDU session via the congested network.

[0105] Upon starting the PLMN search start time period (e.g., by starting the corresponding timer) and determining that the search start time period has expired (e.g., before the expiration of the back-off time period described herein), the WTRU may start a PLMN search procedure (e.g., the PLMN search start timer may be used to control the WTRU’s behavior with respect to the PLMN search). For example, if the WTRU attempts to register with a PLMN (e.g., a VPLMN) based on slice-aware SoR information, the WTRU may be rejected by the PLMN because of a congestion condition in the PLMN (e.g., a mobility management or session management related congestion condition). In this situation, the WTRU may be allowed to search for another PLMN (e.g., another VPLMN) to gain access to a network slice (e.g., a requested network slice), and the PLMN search start time period may be used by a network (e.g., a home network) to control the amount of time that the WTRU may wait before attempting to search for the other PLMN (e.g., if the WTRU is also running a back-off timer associated with the congested PLMN and the back-off timer has not expired).

[0106] FIG.2 shows an example procedure for configuring a WTRU with a PLMN search start time period (e.g., a PLMN search start timer). FIG.3 shows an example of using (e.g., by a WTRU) a PLMN search start time period (e.g., a PLMN search start timer). As shown in FIG.2, a WTRU may, at 1, be configured to support slice-aware SoR information and / or a PLMN search start time period, which may be implemented via a PLMN search start timer. For example, the WTRU may start the PLMN search start timer if the WTRU receives an indication of a back-off time period (e.g., a back-off timer value) from a network. The WTRU may stop the PLMN search start timer upon expiration of the back-off time period (e.g., if the WTRU stops running the back- off timer). The WTRU may start a PLMN search procedure upon starting the PLMN search start timer and determining that the timer has expired.

[0107] As shown in FIG.2, the WTRU may send, at 2, a registration request message to a network device such as an AMF. The registration request message may indicate (e.g., in a mobility management (MM)I5GCN_2023P00645WO PATENT capability IE) that the WTRU may support a PLMN search start time period (e.g., a PLMN search start timer). The WTRU may use other NAS and / or MM procedures to inform the network that the WTRU may support the PLMN search start time period. Such NAS / MM procedures may include, for example, a UL NAS transport procedure, a service request procedure, a mobility registration procedure, etc.

[0108] Also as shown in FIG.2, the AMF may, at 3, respond to the registration request from the WTRU with a registration accept message. The registration accept message may include slice aware SoR information (e.g., related to a PLMN, a stand-alone non-public network (SNPN), and / or a hosting network). The registration accept message may include information regarding the PLMN search start time period, which may be included in an SoR information container. Other NAS messages and / or procedures may also be used to provide the slice aware SoR information and / or the information regarding the PLMN search start time period. These other procedures and / or messages may include, for example, a DL NAS transport procedure, a configuration update command, an SoR, a WTRU parameter update procedure, etc. The AMF may coordinate with an SoR application function (SoR-AF) to obtain the slice-aware SoR information and / or the information regarding the PLMN search start time period for the WTRU. This approach may differ from other approaches under which a WTRU may, based on the reception of a rejection with a cause related to congestion, stay on a current PLMN until a back-off time period expires.

[0109] In examples, information regarding the PLMN search start time period may be configured in a universal integrated circuit card with SIM (USIM) element file (EF), which may be provided by the AMF at 4 via an NAS signaling procedure. In examples, the WTRU may, based on the reception of updated contents for USIM EF (e.g., via an NAS signaling procedure), update a stored USIM EF at 5.

[0110] FIG.3 illustrates how a PLMN search start time period (e.g., a search start timer) may be used by a WTRU (e.g., a roaming WTRU), for example, if the WTRU receives a rejection from a VPLMN due to mobility management or session management congestions (e.g., cause #22, #67, #69, etc.). In response to receiving the rejection, the WTRU may start a PLMN search start timer (e.g., indicating a search start time period) and, upon the expiration of the PLMN search start timer (e.g., but before the expiration of the back-off timer described herein), may select the next available VPLMN (e.g., based on slice-aware SoR information) to gain access to a requested network slice. In some examples, the selected VPLMN may be associated with a lower priority than that of the rejected VPLMN. In some examples, the PLMN search start timer may be configured locally in the WTRU, in which case local configuration information related to the PLMN search start timer may override information provided by a network. In some examples, information regarding the PLMN search startI5GCN_2023P00645WO PATENT timer value may be received from the network and the network-provided information may override local configurations.

[0111] As shown in FIG.3, the WTRU may obtain slice-aware SoR information that may be associated with one or more networks (e.g., preferred networks) per slice or S-NSSAI. The SoR information may be pre- configured, provided by a home network or provided by a visiting network. Information about a slice needed or prioritized by the WTRU may be determined based on prior information (e.g., a prior request) received from a PLMN (e.g., the last serving PLMN that have rejected the WTRU with respect to the slice). The information about the slice needed or prioritized by the WTRU may also be provided by an application running on the WTRU. In either case, the WTRU may select a VPLMN (e.g., a VPLMN with the highest priority) based on the information about the slice requested or desired by a user.

[0112] As shown by 1 of FIG.3, the WTRU may be in a visited location (e.g., the WTRU may be roaming) and may select a VPLMN based on Slice-based PLMN Selection (SbPS) information received from an HPLMN / UDM. At 2, the WTRU may send a registration request message (or a session management layer message such as a PDU session establishment request, a PDU session modification request, or another UL NAS signaling message) to a network device associated with a first VPLMN (e.g., VPLMN-1). Prior to sending the registration request message, the WTRU may have received a registration reject message or a session management reject message from another VPLMN. The rejection from the other VPLMN may have indicated a congestion condition (e.g., as a cause for the rejection). As such, the registration message (or session management layer message) sent to the network at 2 may include rejection cause information (e.g., a cause code), re-attempt indicator information, an identifier (ID) of the VPLMN that has sent the rejection message to the WTRU, an S-NSSAI (e.g., indicative of a network slice desired by the WTRU) that may be associated with the rejection message from the other VPLMN, etc. For instance, the information included in the registration message may indicate a Current Access Type Back-off timer (CATBO) and / or an All PLMNs Back-off timer (ABO). The information (e.g., the registration request) provided by the WTRU may be passed (e.g., transparently) to an HPLMN, a UDM and / or an SoR-AF at 2a, and may assist the receiving device (e.g., the UDM / SoR-AF / H-PCF) with reconstructing slice-aware SoR information and / or a UE route selection policy (URSP) (e.g., by taking into consideration the congestion situation at the visited location). For example, the HPLMN / UDM may lower a priority of a VPLMN or remove a congested VPLMN from the reconstructed slice- aware SoR information or reconstruct new URSP rules that may lower the priority of the slice(s) under congestion in the visited location for the congested VPLMN.I5GCN_2023P00645WO PATENT

[0113] The registration request from the WTRU (e.g., which may indicate a desired network slice) may be rejected by VPLMN-1 at 3 if it is experiencing an overload and / or congestion condition. The rejection may include a cause code (e.g., #22 for congestion, #67 for insufficient resources for specific slice and / or DNN, or #69 insufficient resources for specific slice) that may indicate the cause of the rejection or congestion. Information regarding a back-off time period (e.g., implemented via a mobility management back-off timer) may be sent by an AMF to the WTRU. With the back-off time period (e.g., while the mobility management back-off timer such as T3396 / T3584 / T3585 is running), the WTRU may not initiate an NAS request towards VPLMN-1 except for performing a deregistration procedure, procedures that may not be subject to congestion control (e.g., procedures associated with high priority access, emergency services, etc.) and / or mobile terminated services. Procedures that may not be accepted by the network may include a session management procedure (e.g., a PDU session establishment request or a PDU session modification request). The response from the congested network may be sent via a session management reject message such as a PDU session establishment reject message or a PDU session modification reject message. The response (e.g., including rejection information) from the network may also be provided to the WTRU via other NAS signaling messages including, e.g., a WTRU configuration update command, a service reject message, etc.

[0114] As shown in FIG.2, the WTRU may have also been configured with a PLMN search start time period (e.g., a PLMN search start timer) by an HPLMN / UDM. The WTRU may start the PLMN search start time period (e.g., the corresponding timer) with a value provided by the HPLMN / UDM (e.g., as part of SoR configuration information). At the expiry of the PLMN search start time period (e.g., but before the expiry of a back-off timer described herein), the WTRU may trigger a PLMN selection procedure at 4 based on a slice requested by a user and / or configured slice-aware SoR information. In example implementations of the PLMN selection procedure, the WTRU may consider the congested network (e.g., VPLMN-1) as having the lowest priority for network selection and may camp on another available network (e.g., VPLMN-2) that may provide access to the slice requested by the user. In example implementations of the PLMN selection procedure, the WTRU may consider the congested network (e.g., VPLMN-1) as having the lowest priority network for network selection, select a second network (e.g., VPLMN-2, which may be indicated by SoR information as having a lower priority than VPLMN-1), and perform a registration procedure with the second network. The WTRU may camp on the second network (e.g., VPLMN-2) and may use the registration with the second network to access the slice requested by the user.

[0115] In example implementations of the PLMN selection procedure, the WTRU may, in response to receiving a rejection message from a first network (e.g., VPLMN-1) with a cause code indicative of aI5GCN_2023P00645WO PATENT congestion condition, send a deregistration message, a service request message or another UL NAS message to an AMF of the first network at 5 (e.g., the AMF may pass the message to an HPLMN / UDM). The WTRU may provide additional information to the AMF of the first network at 5a. Such additional information may include a rejection cause from the first network (e.g., VPLMN-1), a re-attempt indicator IE (e.g., to indicate whether a back-off time period is applied in the registered PLMN or all PLMNs), and / or an indication of whether the back- off time period is applied in a current access type (e.g., either or both of a 3GPP access type and a non-3GPP access type). The additional information may also include an ID of the first network (e.g., VPLMN-1) and / or an S-NSSAI. For example, the information sent at 5 or 5a of FIG.3 may indicate one or more timer values (e.g., a CATBO value and / or an ABO value, which may be part of a congestion re-attempt indicator IE of a rejection message). Such an IE may indicate whether a back-off timer may be applied in a registered PLMN, in all PLMNs, in a registered SNPN or in all equivalent SNPNs. The IE may additionally indicate whether the back-off timer may be applied in a current access type or in both a 3GPP access type and a non-3GPP access type.

[0116] The AMF in the first network (e.g., VPLMN-1) may forward the information received from the WTRU to an HPLMN / UDM / H-PCF at 6. The HPLMN / UDM may forward the received information to an SoR-AF at 7, which may use the information (e.g., received from the WTRU via VPLMN-1) to reconstruct slice-aware SoR information (e.g., by taking into consideration the congestion situation, availability of network slices and / or VPLMNs, etc.). The UDM may share the received information with an H-PCF, which may use the shared information to reconstruct an updated URSP at 8 (e.g., by considering the slice requested by a user and its availability or non-availability in VPLMN-1). The updated slice-aware SoR information and / or URSP may be delivered back to the WTRU. In response to receiving the updated information, the WTRU may take actions including, for example, selecting a different VPLMN or performing a session establishment with a different S- NSSAI that may not be congested in the VPLMN. After informing the HPLMN / UDM about the rejection experienced in VPLMN-1 and if the WTRU is configured with a PLMN search start time period as illustrated in FIG.2, the WTRU may proceed to perform the action shown at 4 of FIG.3.

[0117] A WTRU may be configured to perform one or more of the following. The WTRU may receive steering of roaming (SoR) information and / or information regarding a PLMN search start time period (e.g., a PLMN search start timer) from a first network (e.g., from a HPLMN). The SoR information may indicate that at least a second PLMN (e.g., a first VPLMN) and a third PLMN (e.g., a second VPLMN) may be associated with a network slice (e.g., with corresponding S-NSSAI). The SoR information may indicate that the second PLMN may be higher in priority than the third PLMN. The WTRU may send an NAS message to the second PLMN to initiate a PDU session establishment or registration procedure. The NAS message may include the S-NSSAII5GCN_2023P00645WO PATENT associated with the second PLMN. The WTRU may receive an NAS response message from the second PLMN that may include information regarding a back-off time period (e.g., a back-off timer) and / or a rejection cause code (e.g., the rejection cause code may indicate that the rejection cause is congestion).

[0118] The WTRU may monitor for the back-off time period (e.g., by starting a back-off timer) and / or a PLMN search start time period (e.g., by starting a search start timer). Based on a determination that the PLMN search start time period has expired (e.g., before the back-off time period expires), the WTRU may initiate a PLMN selection procedure. The WTRU may select the third PLMN during the PLMN selection procedure and may send a registration message to the third PLMN. The registration message may include the S-NSSAI associated with the third PLMN.

[0119] Information regarding the PLMN search start time period (e.g., a corresponding timer) may be received in an SoR container. The information regarding the PLMN search start time period may also be received in an NAS message. The information regarding the PLMN search start time period may be stored in a USIM of the WTRU. The WTRU may send an indication to the network to indicate that the WTRU may support the PLMN search start time period. The registration message sent to the third PLMN may include information about the rejection cause code received from the second PLMN. The WTRU may receive a registration response from the third PLMN that may include SoR information (e.g., new or updated SoR information).

[0120] FIG.4 illustrates examples of actions (e.g., core network actions) that may be associated with congestion handling at a visited location. As shown in FIG.4, a WTRU may obtain slice-aware SoR information associated with a network (e.g., a preferred network) per slice (e.g., per S-NSSAI). The slice-aware SoR information may be pre-configured or provided by a home network or a visiting network. Information about a slice needed or prioritized by the WTRU may be determined based on a prior request from a PLMN (e.g., the last serving PLMN that may have rejected the WTRU with respect to the slice). Information about a slice needed or prioritized by the WTRU may also be provided by an application running on the WTRU. In either case, the WTRU may use the information to select the highest priority VPLMN based on a slice requested by a user.

[0121] Also as shown in FIG.4, the WTRU may be in a visited location, as shown by 1 of FIG.4, and may send a registration request message at 2 to a selected VPLMN along with information (e.g., a flag such as an SbPS Flag) that may indicate that the WTRU supports slice-based PLMN selection (e.g., the selection of the VPLMN may be based on slice-aware SoR information from an HPLMN).

[0122] The registration request from the WTRU may be rejected by the VPLMN at 3 if the VPLMN is experiencing an overload and / or congestion condition. The rejection response from the VPLMN (e.g., from anI5GCN_2023P00645WO PATENT AMF of the VPLMN) may include a cause code indicative of the congestion condition (e.g., #22 for congestion, #67 for insufficient resources for specific slice and / or DNN, or #69 for insufficient resources for specific slice). The AMF may send information regarding a back-off time period (e.g., a mobility management back-off timer) to the WTRU. During the back-off time period (e.g., while the mobility management back-off timer such as T3396 / T3584 / T3585 is running), the WTRU may refrain from accessing the VPLMN. For example, the WTRU may not initiate an NAS request to the VPLMN except for performing a deregistration procedure and / or procedures that may not be subject to congestion control (e.g., these procedures may be associated with high priority access, emergency services and / or mobile terminated services). The VPLMN AMF may use the information (e.g., an SbPS flag) received from the WTRU to decide whether to inform an HPLMN / UDM / H-PCF about the overload and / or congestion condition experienced by the VPLMN. Such information may be shared by the VPLMN without dependency on the information (e.g., the SbPS flag) received from the WTRU.

[0123] The VPLMN AMF may inform the HPLMN UDM / H-PCF about the registration rejection at 4. The VPLMN AMF may also send additional information to the HPLMN UDM / H-PCF. Such information may include a reject cause from the VPLMN, a re-attempt indicator IE (e.g., to indicate whether the back-off timer is applied in the registered PLMN or all PLMNs), and / or an indication of whether the back-off time period is applied in the current access type (e.g., either or both of a 3GPP access type and a non-3GPP access type). The information may also include a subscription permanent identifier (SUPI), an access type, a VPLMN ID and / or an S-NSSAI.

[0124] The HPLMN / UDM may forward the received information to an SoR-AF at 5. The SoR-AF may use the updated information received from the VPLMN to reconstruct slice-aware SoR information at 6, e.g., by taking into consideration the congestion experienced at the reported VPLMN, and / or the availability of network slices and / or other VPLMNs. For example, the HPLMN / UDM may lower the priority of a VPLMN or remove the congested VPLMN from the reconstructed slice-aware SoR information. The UDM may share the information with an H-PCF, which may use the information to construct an updated URSP. The URSP may consider the slice requested by a user and the availability or non-availability of a slice in the VPLMN. For example, a reconstructed URSP rule may lower the priority of slices that may be under congestion in the visited location (e.g., for the congested VPLMN).

[0125] The updated / reconstructed slice aware SoR information and / or URSP rules may be delivered back to the WTRU via a VPLMN at 7. In response to receiving the updated information, the WTRU may take actions such as, for example, selecting a network associated with a different VPLMN, performing session establishment with a different S-NSSAI that may not be congested in the VPLMN, re-evaluating the URSP (e.g., which may lead to the selection of an un-congested slice or S-NSSAI), etc.I5GCN_2023P00645WO PATENT

[0126] A network device such as a VPLMN AMF may be configured to perform one or more of the following operations. The network device may receive information (e.g., an SbPS flag) from a WTRU, which may indicate that the WTRU may support slice-based PLMN selection and / or that the selection of a VPLMN may be based on slice-aware SoR information provided by an HPLMN. The network device may determine that an overload or congestion condition may have occurred in the VPLMN and may reject a registration request from the WTRU with a cause code indicative of the congestion condition (e.g., #22 for congestion, #67 for insufficient resources for specific slice and / or DNN or #69 for insufficient resources for specific slice). The network device may use the information provided by the WTRU (e.g., an SbPS flag) to determine if it may inform an HPLMN / UDM / H-PCF about the congestion situation. The network device may inform the HPLMN UDM / H-PCF about the registration rejection along with additional information. For example, the additional information may include a reject cause, a session management (SM) re-attempt indicator information element (IE) (e.g., which may indicate whether a back-off timer may be applied in the registered PLMN or all PLMNs). The additional information may also indicate whether a back-off time period may be applied in a current access type (e.g., either or both of a 3GPP access type and a non-3GPP access type). The additional information may also include a SUPI, an access type, a VPLMN ID and / or an S-NSSAI. An SoR-AF may use updated information received from the VPLMN to reconstruct slice-aware SoR information, e.g., by considering the congestion situation, the availability of slices and VPLMNs, etc. A UDM may share the reconstructed information with an H-PCF, which may use this information to construct an updated URSP that may consider the slice requested by a user and / or the available or non-availability of a slice in the VPLMN.

[0127] The network device may receive the updated slice-aware SoR information and / or URSP rules and may send the slice-aware SoR information and / or URSP rules to the WTRU. In response to receiving the updated information, the WTRU may take certain actions such as, e.g., selecting a different VPLMN, performing session establishment with a different S-NSSAI that may not be congested in the VPLMN, re- evaluating the URSP rules (e.g., which may lead to the selection of an uncongested slice or S-NSSAI), etc.

[0128] Although features and elements described above are described in particular combinations, each feature or element may be used alone without the other features and elements of the preferred embodiments or in various combinations with or without other features and elements. Although the implementations described herein may consider 3GPP specific protocols, it is understood that the implementations described herein are not restricted to this scenario and may be applicable to other wireless systems. For example, although the solutions described herein consider LTE, LTE-A, New Radio (NR) or 5G specific protocols, it isI5GCN_2023P00645WO PATENT understood that the solutions described herein are not restricted to this scenario and are applicable to other wireless systems as well.

[0129] The processes described above may be implemented in a computer program, software, and / or firmware incorporated in a computer-readable medium for execution by a computer and / or processor. Examples of computer-readable media include, but are not limited to, electronic signals (transmitted over wired and / or wireless connections) and / or computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as, but not limited to, internal hard disks and removable disks, magneto-optical media, and / or optical media such as compact disc (CD)-ROM disks, and / or digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, terminal, base station, RNC, and / or any host computer.

Claims

I5GCN_2023P00645WO PATENT CLAIMS 1. A wireless transmit / receive unit (WTRU), comprising: a processor configured to: receive information that indicates that a network slice is available via at least a first mobile network and a second mobile network; send a message to the first mobile network, wherein the message indicates the network slice; receive a response from the first mobile network, wherein the response indicates that the first mobile network is congested with respect to the network slice, the response further indicating a back- off time period associated with accessing the first mobile network for the network slice; start monitoring for an expiration of the back-off time period and an expiration of a network search time period; and after the expiration of the network search time period but before the expiration of the back-off time period, send a registration request associated with the network slice to the second mobile network.

2. The WTRU of claim 1, wherein the information received by the WTRU further indicates the network search time period.

3. The WTRU of claim 1 or 2, wherein the information received by the WTRU further indicates that the first mobile network has a higher priority than the second mobile network, and wherein the processor is configured to send the message to the first mobile network based on the indication that the first mobile network has the higher priority than the second mobile network.

4. The WTRU of any of claims 1-3, wherein the message sent to the first mobile network includes a request to register with the first mobile network or to establish a protocol data unit (PDU) session via the first mobile network.

5. The WTRU of claim 4, wherein, after the expiration of the back-off time period, the processor is further configured to re-send the request to register with the first mobile network or to establish the PDU session via the first mobile network.I5GCN_2023P00645WO PATENT 6. The WTRU of any of claims 1-5, wherein the information is received from a home public land mobile network (HPLMN) and includes steering of roaming (SoR) information, and wherein at least one of the first mobile network or the second mobile network is a visitor public land mobile network (VPLMN).

7. The WTRU of any of claims 1-6, wherein the registration request sent to the second mobile network includes assistance information associated with the network slice.

8. The WTRU of claim 7, wherein the assistance information includes single network slice selection assistance information (S-NSSAI).

9. The WTRU of any of claims 1-8, wherein the processor being configured to start monitoring for the expiration of the back-off time period and the expiration of the network search time period comprises the processor being configured to start a first timer associated with the back-off time period and a second timer associated with the network search time period.

10. The WTRU of any of claims 1-9, wherein the processor is further configured to search for the second mobile network after the expiration of the network search time period and before the expiration of the back-off time period.

11. The WTRU of any of claims 1-10, wherein the registration request sent to the second mobile network includes information about a rejection cause code associated with the first mobile network.

12. A method implemented by a wireless transmit / receive unit (WTRU), the method comprising: receiving information that indicates that a network slice is available via at least a first mobile network and a second mobile network; sending a message to the first mobile network, wherein the message indicates the network slice; receiving a response from the first mobile network, wherein the response indicates that the first mobile network is congested with respect to the network slice, the response further indicating a back-off time period associated with accessing the first mobile network for the network slice; starting to monitor for an expiration of the back-off time period and an expiration of a network search time period; andI5GCN_2023P00645WO PATENT after the expiration of the network search time period but before the expiration of the back-off time period, sending a registration request associated with the network slice to the second mobile network.

13. The method of claim 12, wherein the received information further indicates the network search time period.

14. The method of claim 12 or 13, wherein the received information further indicates that the first mobile network has a higher priority than the second mobile network, and wherein the message is sent to the first mobile network based on the indication that the first mobile network has the higher priority than the second mobile network.

15. The method of any of claims 12-14, wherein the message sent to the first mobile network includes a request to register with the first mobile network or to establish a protocol data unit (PDU) session via the first mobile network.

16. The method of claim 15, further comprising re-sending the request to register with the first mobile network or to establish the PDU session via the first mobile network after the expiration of the back-off time period.

17. The method of any of claims 12-16, wherein the information is received from a home public land mobile network (HPLMN) and includes steering of roaming (SoR) information, and wherein at least one of the first mobile network or the second mobile network is a visitor public land mobile network (VPLMN).

18. The method of any of claims 12-17, wherein the registration request sent to the second mobile network includes assistance information associated with the network slice.

19. The method of any of claims 12-18, wherein starting to monitor for the expiration of the back-off time period and the expiration of the network search time period comprises starting a first timer associated with the back-off time period and a second timer associated with the network search time period.I5GCN_2023P00645WO PATENT 20. The method of any of claims 12-19, further comprising searching for the second mobile network after the expiration of the network search time period and before the expiration of the back-off time period.

21. A device associated with a mobile network, comprising: a processor configured to: receive, from a wireless transmit / receive unit (WTRU), a first request to access a network slice provided by the mobile network; determine that the mobile network is congested with respect to the network slice; send a response to the WTRU, wherein the response indicates that the mobile network is congested with respect to the network slice, the response further indicating a time period for the WTRU to refrain from accessing the mobile network for the network slice; and receive, after an expiration of the time period, a second request from the WTRU to access the network slice provided by the mobile network.

22. The device of claim 21, wherein the mobile network is a visitor public land mobile network for the WTRU.

Images