Wireless transmit-receive unit and implementation method thereof

Abstract

A wireless transmit-receive unit and a method of implementing the same are provided. The method includes receiving a message from an AMF of a network, the message including allowed network slice selection assistance information (NSSAI), where the message is a registration accept message or a configuration update message, where a replacement single NSSAI (S-NSSAI) is part of the allowed NSSAI, where the message includes an indication that the replacement S-NSSAI is a replacement of a second S-NSSAI; and transmitting a request for PDU session establishment to the network, wherein the request includes the replacement S-NSSAI. In some cases, the network may have a limit on the number of connections that it may maintain (e.g., for a given area, a maximum capacity may exist). Thus, such restrictions need to be handled in a most efficient manner possible such that devices that wish to connect to the network or have a current connection to the network are provided with the best possible opportunity to achieve their communication targets.

Description

[0001] This divisional application is a divisional application with the application date of March 28, 2023, application number 202380034544.7, and invention name “Slice registration and PDU session establishment control”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of U.S. Provisional Application No. 63 / 324,354, filed on March 28, 2022, and U.S. Provisional Application No. 63 / 338,688, filed on May 5, 2022, the contents of which are incorporated herein by reference. Background Art

[0004] In some cases, wireless systems need to be continually modified to address new use cases and improve efficiency. In one specific area, methods are needed to address network slicing and packet data unit (PDU) management. Summary of the invention

[0005] In some cases, a network may have limitations on the number of connections it can maintain (e.g., there may be a maximum capacity for a given area). Therefore, there is a need to handle such limitations in the most efficient way possible so that devices that wish to connect to the network or have a current connection to the network are provided with the best possible opportunity to achieve their communication goals. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] A more detailed understanding may be obtained from the following description given by way of example in conjunction with the accompanying drawings, in which like reference numerals indicate like elements, and in which:

[0007] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented;

[0008] Figure 1B is an example of a method that can be used according to one or more of the methods described herein. Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within the communication system shown;

[0009] Figure 1C is an example of a method that can be used according to one or more of the methods described herein. Figure 1A A system diagram of an example radio access network (RAN) and an example core network (CN) used within the illustrated communication system;

[0010] Figure 1D is an example of a method that can be used according to one or more of the methods described herein. Figure 1A A system diagram of an additional example RAN and an additional example CN used within the illustrated communication system;

[0011] Figure 2 An example of how to transmit an unsolicited indication to a WTRU is illustrated;

[0012] Figure 3 An example of a WTRU assisted PDU session early admission control procedure is illustrated; and

[0013] Figure 4 An example of a WTRU process of receiving a network-indicated replacement slice and managing the associated PDU session is illustrated. DETAILED DESCRIPTION

[0014] One or more of the following abbreviations may be used herein: Access and Mobility Function (AMF); Access Network (AN); Attention (AT); Early Admission Control (EAC); Mobility Management (MM); Mobile Terminal (MT); Network Slice Admission Control Function (NSACF); Non-Access Stratum (NAS); Network Slice Selection Assistance Information (NSSAI); Protocol Data Unit (PDU); Performance Management Function (PMF); Registration Area (RA); Radio Access Network (RAN); Radio Resource Control (RRC); Routing Descriptor (RSD); Session Management (SM); Session Management Function (SMF); Single NSSAI (S-NSSAI); Slice Specific Service Area (SSAA); Tracking Area (TA); Terminal Equipment (TE); Unified Access Control (UAC); Unified Data Management (UDM); User Data Repository (UDR); User Equipment (UE); User Plane Function (UPF); and UE Routing Policy (URSP).

[0015] Figure 1A 1 is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content through sharing of system resources (including wireless bandwidth). For example, the communication system 100 may 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 discrete Fourier transform spread OFDM (ZT-UW-DFT-S-OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multi-carrier (FBMC), etc.

[0016] like Figure 1AAs shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network (CN) 106, a public switched telephone network (PSTN) 108, the Internet 110 and other networks 112, but it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may 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 may be referred to as a station (STA)) may be configured to send and / or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, 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 device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated process chain environment), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0017] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may 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, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an evolved Node B (eNB), a Home Node B, a Home evolved Node B, a next generation Node B such as a gNode B (gNB), a new radio (NR) Node B, 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 may include any number of interconnected base stations and / or network elements.

[0018] The base station 114a may be part of the RAN 104, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay node, etc. The base station 114a and / or the base station 114b may be configured to send and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of licensed and unlicensed spectrums. A cell may provide coverage of wireless services to a specific geographic area, which may be relatively fixed or may change over time. The cell may be further divided into cell sectors. For example, a cell associated with the base station 114a may be divided into three sectors. Therefore, in one embodiment, the base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to send and / or receive signals in a desired spatial direction.

[0019] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may 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 may be established using any suitable radio access technology (RAT).

[0020] More specifically, as noted above, the communication system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base station 114a in the RAN 104 and the WTRUs 102a, 102b, 102c may implement a radio technology, such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), that may use Wideband CDMA (WCDMA) to establish the air interface 116. WCDMA may include communication protocols, such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High Speed ​​Uplink (UL) Packet Access (HSUPA).

[0021] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-A Pro).

[0022] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology (such as NR radio access) that may establish the air interface 116 using NR.

[0023] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may together implement LTE radio access and NR radio access, for example using the dual connectivity (DC) principle. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions transmitted to / from multiple types of base stations (e.g., eNBs and gNBs).

[0024] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may 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, CDMA2000 1X, 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), etc.

[0025] Figure 1AThe base station 114b in the may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in local areas such as commercial venues, homes, vehicles, campuses, industrial facilities, sky corridors (e.g., for use by drones), roads, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement radio technologies 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 may implement radio technologies such as IEEE 802.15 to establish a wireless personal area network (WPAN). In another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or a femtocell. As Figure 1A As shown, the base station 114b may have a direct connection to the Internet 110. Therefore, the base station 114b may not be required to access the Internet 110 via the CN 106.

[0026] The RAN 104 may be in communication with the CN 106, which may 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 may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not described in detail in the accompanying drawings, the CN 106 may be 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. Figure 1A Although not shown in the figure, it will be appreciated that the RAN 104 and / or the CN 106 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104, which may utilize NR radio technology, the CN 106 may also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0027] The CN 106 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and / or the Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired communication networks and / or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 or a different RAT.

[0028] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). Figure 1A The illustrated WTRU 102c may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0029] Figure 1B is a system diagram illustrating an example WTRU 102. Figure 1B As shown, the WTRU 102 may include, among other things, 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. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0030] The processor 118 may 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 associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal decoding, 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 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, but it is understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0031] The send / receive element 122 may be configured to send a signal to a base station (e.g., base station 114a) or receive a signal from the base station via an air interface 116. For example, in one embodiment, the send / receive element 122 may be an antenna configured to send and / or receive an RF signal. In an embodiment, the send / receive element 122 may be a transmitter / detector configured to send and / or receive, for example, an IR, UV or visible light signal. In another embodiment, the send / receive element 122 may be configured to send and / or receive both an RF signal and an optical signal. It should be understood that the send / receive element 122 may be configured to send and / or receive any combination of wireless signals.

[0032] Although the transmit / receive element 122 Figure 1B 1 as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0033] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. For example, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0034] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from and store data in any type of suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may 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 may access information from and store data in a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0035] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control power to other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may 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, etc.

[0036] The processor 118 may also be coupled to the GPS chipset 136, which may 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 may receive location information from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method while remaining consistent with an embodiment.

[0037] The processor 118 may also be coupled to other peripherals 138, which may include one or more software modules and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, module, FM radio unit, digital music player, media player, video game player module, Internet browser, virtual reality and / or augmented reality (VR / AR) device, activity tracker, etc. The peripheral device 138 may include one or more sensors. The sensor may be one or more of the following: 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, a humidity sensor, etc.

[0038] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with specific subframes for both UL (e.g., for transmission) and DL (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit for reducing and / or substantially eliminating self-interference via signal processing performed by hardware (e.g., a choke) or via a processor (e.g., a separate processor (not shown) or via the processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with specific subframes for both UL (e.g., for transmission) or DL ​​(e.g., for reception)) may be concurrent and / or simultaneous.

[0039] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0040] The RAN 104 may include evolved Node-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of evolved Node-Bs while remaining consistent with an embodiment. The evolved Node-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the evolved Node-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the evolved Node-B 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0041] Each of the evolved Node Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, etc. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0042] Figure 1C The illustrated CN 106 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (PGW) 166. Although the foregoing elements are depicted as part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0043] The MME 162 may be connected to each of the evolved Node-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may 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, etc. The MME 162 may 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.

[0044] The SGW 164 may be connected to each of the evolved Node-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during inter-evolved Node-B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, and the like.

[0045] The SGW 164 may be connected to the PGW 166, which may 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.

[0046] The CN 106 may facilitate communications with other networks. For example, the CN 106 may 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 may include, or may be in communication with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers.

[0047] Although the WTRU Figures 1A to 1D Although described as wireless terminals, it is contemplated that in certain representative embodiments, such terminals may (eg, temporarily or permanently) use a wired communication interface with a communication network.

[0048] In a representative embodiment, the other network 112 may be a WLAN.

[0049] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for a BSS and one or more stations (STA) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic to and / or carries traffic away from the BSS. Traffic originating from outside the BSS and leading to the STA may be reached by the AP and may be delivered to the STA. Traffic originating from the STA and leading to a destination outside the BSS may be transmitted to the AP to be delivered to the corresponding destination. Traffic between STAs within the BSS may be transmitted by the AP, for example, wherein the source STA may transmit traffic to the AP, and the AP may deliver traffic to the target STA. Traffic between STAs within the BSS may be considered and / or referred to as point-to-point traffic. Point-to-point traffic may be transmitted between the source STA and the target STA (e.g., directly between them) using a direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (eg, all STAs in the STA) may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad hoc" communication mode.

[0050] When using the 802.11ac infrastructure operation mode or a similar operation mode, the AP may send beacons on a fixed channel (such as a primary channel). The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a dynamically set width. The primary channel may be an operating channel of the BSS and may be used by the STA to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access / collision avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. For CSMA / CA, a STA (e.g., each STA) (including the AP) may listen to the primary channel. If the primary channel is listened / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0051] High throughput (HT) STAs may communicate using a 40 MHz wide channel, for example, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0052] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz channels and / or 80MHz channels can be formed by combining continuous 20MHz channels. 160MHz channels can be formed by combining 8 continuous 20MHz channels, or by combining two non-continuous 80MHz channels (this can be called 80+80 configuration). For 80+80 configuration, after channel coding, the data can pass through a segment parser that can divide the data into two streams. Each stream can be processed by inverse fast Fourier transform (IFFT) and time domain processing separately. These streams can be mapped to two 80MHz channels, and data can be sent by sending STA. At the receiver of the receiving STA, the above-mentioned operation for 80+80 configuration can be reversed, and the combined data can be transmitted to the medium access control (MAC).

[0053] 802.11af and 802.11ah support operating modes below 1 GHz. 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 5MHz, 10MHz, and 20MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support meter type control / machine type communication (MTC), such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0054] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA (which supports the minimum bandwidth operating mode) from all STAs operating in the BSS. In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only support) a 1MHz mode, the primary channel may be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy, for example, because a STA (which only supports a 1MHz operating mode) is transmitting to the AP, all available bands may be considered busy even if most of the available bands remain idle.

[0055] In the United States, the available frequency band for 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

[0056] Figure 1D1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with an embodiment. As noted above, the RAN 104 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0057] The RAN 104 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 104 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may 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 may implement MIMO technology. For example, the gNBs 180a, 180b may utilize beamforming to send signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may, for example, use multiple antennas to send wireless signals to and / or receive wireless signals from the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, gNB 180a may transmit multiple component carriers to WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum, while the remaining component carriers may be on licensed spectrum. In an embodiment, gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0058] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable parameter sets. For example, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmit time intervals (TTIs) of varying or scalable lengths (e.g., containing varying numbers of OFDM symbols and / or varying absolute time lengths).

[0059] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c while not accessing other RANs (e.g., such as the eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchors. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with the gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as the eNode-B 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNode-B 160a, 160b, 160c may act as a mobility anchor for the WTRUs 102a, 102b, 102c, and the gNB 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0060] Each of the gNBs 180a, 180b, 180c may be associated with a specific cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, support of network slicing, interworking between DC, NR, and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b, routing of control plane information towards an access and mobility management function (AMF) 182a, 182b, etc. Figure 1D As shown, gNBs 180a, 180b, and 180c may communicate with each other via an Xn interface.

[0061] Figure 1DThe illustrated CN 106 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possible data networks (DNs) 185a, 185b. Although the aforementioned elements are depicted as part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0062] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via the N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, support of network slicing (e.g., handling of different protocol data unit (PDU) sessions with different requirements), selecting a specific SMF 183a, 183b, management of registration areas, termination of non-access stratum (NAS) signaling, mobility management, etc. The AMF 182a, 182b may use network slicing to customize CN support for the WTRU 102a, 102b, 102c based on the type of services utilized by the WTRU 102a, 102b, 102c. For example, different network slices may 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 MTC access, etc. The AMF 182a, 182b may provide a control plane function for switching between the RAN 104 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.

[0063] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 106 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 106 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b, and configure traffic routing through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing DL data notifications, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0064] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via the N3 interface, which may 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 may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering DL packets, providing mobility anchoring, etc.

[0065] The CN 106 may facilitate communications with other networks. For example, the CN 106 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to the DNs 185a, 185b via the UPFs 184a, 184b via the N3 interfaces to the UPFs 184a, 184b and the N6 interfaces between the UPFs 184a, 184b and the local DNs 185a, 185b.

[0066] Given that Figures 1A to 1D as well as Figures 1A to 1D Corresponding to the description of the present invention, one or more or all of the functions described herein with reference to one or more of the following items may be performed by one or more simulation devices (not shown): WTRU102a to 102d, base station 114a to 114b, evolved Node B 160a to 160c, MME 162, SGW 164, PGW 166, gNB180a to 180c, AMF 182a to 182b, UPF 184a to 184b, SMF 183a to 183b, DN 185a to 185b and / or any other device described herein. The simulation device may be one or more devices configured to mimic one or more or all of the functions described herein. For example, the simulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0067] The simulation device may be designed to implement one or more tests of other devices in a laboratory environment and / or in an operator network environment. For example, one or more simulation devices may perform one or more functions 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. One or more simulation devices may perform one or more functions or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The simulation device may be directly coupled to another device for the purpose of testing and / or performing tests using over-the-air wireless communications.

[0068] One or more simulation devices can perform one or more (including all) functions without being implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation device can be used in a test scenario in a test laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network to implement testing of one or more components. One or more simulation devices can be test equipment. Direct RF coupling and / or wireless communication via RF circuits (e.g., which can include one or more antennas) can be used by the simulation device to send and / or receive data.

[0069] A registration area is a set of tracking areas. A registration area may be defined by a tracking area identifier (TAI) list (e.g., a list of tracking areas). When a WTRU registers with a network (e.g., transmits a registration request to a network node such as an AMF), the network (e.g., AMF) may assign a registration area (e.g., the set of tracking areas in the TAI list) to the WTRU and may take into account information such as the WTRU's expected mobility pattern when assigning the TAI list.

[0070] The configured Network Slice Selection Assistance Information (NSSAI) is a list or set of one or more slices that the WTRU can access. The WTRU may receive the configured NSSAI in a Registration Accept message or a WTRU Configuration Update message.

[0071] The requested NSSAI is a list or set of one or more slices that the WTRU transmits to the network in order to request registration with the slices in the list. The WTRU may transmit the requested NSSAI to the network in a registration request message.

[0072] The allowed NSSAI is a list or set of one or more slices that the WTRU can access in the registration area of ​​the WTRU. In other words, it is a list of slices that the WTRU can use in the registration area of ​​the WTRU.

[0073] A rejected single NSSAI (S-NSSAI) is an information element that the network may transmit to the WTRU in a registration accept message and / or a WTRU configuration update message. A rejected S-NSSAI may indicate that the WTRU was included in one or more slices in the requested NSSAI, but the network determined that the WTRU may not access.

[0074] As disclosed herein, the phrases "attempting to register with a slice" and "including a slice (eg, S-NSSAI) in a requested NSSAI" can be used interchangeably. Additionally, the terms slice and S-NSSAI can be used interchangeably.

[0075] The S-NSSAIs provided by the WTRU in the requested NSSAI that are neither in the allowed NSSAI nor provided as rejected S-NSSAIs may not be considered rejected by the WTRU (e.g., the WTRU may request registration of these S-NSSAIs again the next time the WTRU transmits a requested NSSAI).

[0076] When a WTRU registers with a slice, it may use at least some minimal resources of the slice. For example, the WTRU may transmit at least periodic NAS messages to the AMF that is part of the slice. However, the WTRU may or may not use the user plane resources of the slice or other resources of the slice, such as SMS and / or location services.

[0077] The WTRU may select up to 8 slices (e.g., S-NSSAI) from its configured NSSAI to register. When the WTRU selects a slice to register, the WTRU shall transmit a registration request to the network, and the requested NSSAI information element of the registration request shall include the slice selected for registration.

[0078] Various events may trigger the WTRU to register with the slice.

[0079] In one example of a trigger for registration, the WTRU may be configured to always attempt to register to a specific slice unless the WTRU knows that the slice is unavailable. For example, the WTRU may attempt to register to a specific slice immediately or shortly after power-up.

[0080] In one example of a trigger for registration, the WTRU may be configured to attempt to register to a specific slice when registered in a specific PLMN.

[0081] In one example of a trigger for registration, the WTRU may be configured to attempt to register to a specific slice when one or more specific application traffic is initiated.

[0082] In one example of a trigger for registration, the WTRU may be configured to attempt to register to a specific slice when the WTRU is in a specific location.

[0083] In one example of a trigger for registration, the WTRU may be configured to attempt to register to a specific slice when a specific application is installed.

[0084] In one example of a trigger for registration, the WTRU may be configured to attempt to register to a specific slice when prompted by a user interface such as a GUI. For example, a user may indicate via a GUI that a specific service is desired.

[0085] Once the WTRU is registered with a slice, the WTRU may determine to establish a PDU session in the slice. The WTRU may establish a PDU session by transmitting a PDU session establishment request to the network. The PDU session establishment request is a NAS-SM message that may be transmitted to the SMF of the network slice associated with the network slice.

[0086] The PDU session establishment request may include an S-NSSAI associated with the PDU session and a data network name (DNN) associated with the PDU session. If the S-NSSAI is not included in the PDU session establishment request, the network may determine the S-NSSAI for the PDU session. If the DNN is not included in the PDU session establishment request, the network may determine the DNN for the PDU session.

[0087] Various events may trigger the WTRU to send a PDU session establishment request to the network.

[0088] In one example of a trigger for a PDU session establishment, a WTRU-hosted application may request the WTRU to establish a PDU session. The request from the WTRU-hosted application may include a DNN and an S-NSSAI, and the WTRU may transmit the same DNN and S-NSSAI to the network in the PDU session establishment request. For example, a WTRU hosted in the TE portion of the WTRU may invoke an AT command such as +CGDCONT (syntax for requesting a PDU session or PDP context) to request the MT portion of the WTRU to transmit a PDU session establishment request to the network (e.g., an AT may be used to initiate a command line to be transmitted from the TE to a terminal adapter).

[0089] In one example of a trigger for PDU session establishment, an application hosted by the WTRU may generate uplink traffic that causes the WTRU to evaluate UE routing selection policy (URSP) rules to determine the desired characteristics of the PDU session that will be used to transmit the uplink traffic to the network. The result of the URSP evaluation may be that the WTRU determines to use an existing PDU session or a new PDU session to transmit the uplink traffic to the network. If the WTRU determines to establish a new PDU session, the WTRU will transmit a PDU session establishment request to the network. The URSP rules may also be used to determine what DNN and S-NSSAI to include in the PDU session establishment request.

[0090] In one example of a trigger for PDU session establishment, the WTRU may be configured with a DNN / S-NSSAI combination and when the WTRU is registered to the S-NSSAI in the combination, the WTRU may always establish PDU sessions towards these DNN / S-NSSAI combinations. The WTRU may choose to establish these PDU sessions even if there is no WTRU application that will use the PDU session to transmit or receive traffic.

[0091] In one example of a trigger for PDU session establishment, the WTRU may receive a device trigger that triggers the WTRU to establish a PDU session. The device trigger may be a NAS or SMS message. The device trigger message may include a DNN and / or an S-NSSAI, and the WTRU may include the DNN and / or S-NSSAI in the PDU session establishment request.

[0092] The Network Slice Admission Control Function (NSACF) monitors and controls the number of registered WTRUs per network slice and / or the number of PDU sessions per network slice for network slices subject to Network Slice Admission Control (NSAC). The NSACF may be configured with the maximum number of WTRUs and / or the maximum number of PDU sessions allowed to be served per S-NSSAI subject to the NSAC. The NSACF may also be configured with information indicating the applicable access type (e.g., 3GPP access type, non-3GPP access type, or both) for the S-NSSAI. The NSACF may have the same or similar hardware as a WTRU, base station, network function network node, etc., as described herein; similarly, it may run virtually from hardware operating different functions concurrently.

[0093] The NSACF may track the current number of WTRUs registered for the network slice so that it can ensure that it does not exceed the maximum number of WTRUs allowed to register with the network slice.

[0094] The AMF may trigger a request to the NSACF for NSAC for the maximum number of WTRUs when the registration status of the WTRU for a network slice subject to NSAC is changing (e.g., during WTRU registration, WTRU deregistration procedure, network slice specific authentication and authorization procedure, network slice specific re-authentication or re-authorization procedure triggered by an AAA server, slice specific authorization revocation procedure triggered by an AAA server and / or a WTRU configuration update procedure).

[0095] When the maximum number of registrations for a slice has been reached, the NSACF may indicate to the AMF that the request to register to the slice should be rejected, and a reason code may be provided to the WTRU indicating that the reason why the slice registration was rejected is that the maximum number of registrations for the slice has been reached. A backoff timer may also be communicated to the WTRU and may be used by the WTRU to detect when the WTRU may attempt to register to the slice again.

[0096] The NSACF may track the current number of PDU Sessions per network slice so that it may ensure that it does not exceed the maximum number of PDU Sessions allowed to be served by the network slice. When an event related to the 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 the network slice has been reached and if so, the NSACF may apply an admission control policy.

[0097] When the maximum number of PDU sessions for a slice has been reached, the NSACF may indicate to the SMF that the PDU session establishment request should be rejected and a reason code may be provided to the WTRU indicating that the reason the PDU session was rejected is that the maximum number of PDU sessions for the slice has been reached. A backoff timer may also be communicated to the WTRU and may be used by the WTRU to detect when the WTRU may again attempt to establish a PDU session in the slice.

[0098] During the PDU session establishment / release process, the anchor SMF triggers a request to the NSACF for the maximum number of PDU sessions controlled by each network slice.

[0099] For a given wireless system (e.g., a 5G system), unified access control (UAC) is where a WTRU is able to determine whether a particular new access attempt is allowed based on barring parameters broadcast by a base station and based on information configured in the WTRU (e.g., access class and access identity information). UAC cannot be used to selectively bar WTRUs that are not fully utilizing the resources of a slice or PDU session.

[0100] The AMF may be configured to perform Early Admission Control (EAC) as follows: The configuration for the Early Admission Control (EAC) update procedure may indicate to the AMF the activation or deactivation of the EAC mode for the S-NSSAI subject to NSAC. The EAC mode means the number of WTRUs for which the AMF is required to perform a per network slice availability check and update procedure before the S-NSSAI subject to NSAC is included in the allowed NSSAI and transmitted to the WTRU. The EAC mode may only be applicable to the AMF when the update flag is set to increase.

[0101] As described in the above examples, a WTRU may sometimes register to a slice because some conditions have been met (e.g., power on or application installation, etc.), however, the WTRU may not actually be using the resources of the slice other than NAS messaging. For example, the WTRU may not establish a PDU session in the slice. Such a WTRU may remain registered for a long period of time before establishing a PDU session, transmitting PDUs / packets, etc. In terms of management of network resources, this type of behavior may lead to inefficient and / or unfair allocation of resources in the network and is therefore undesirable. As previously explained, the number of WTRUs that can register to the network slice may be limited by the NSACF. It would be an inefficient use of network resources if WTRUs that are not using the resources of a slice other than the resources of the slice required to maintain a NAS connection with the AMF were counted towards the registration quota of the slice. For example, when the registration quota is reached, this may result in a second WTRU's registration request for the slice being rejected, even if the second WTRU actually wants to use the slice for communication. Methods are needed to allow the network to be able to detect when a WTRU is underutilizing the resources of a network slice so that the WTRU can deregister from that slice. For a WTRU that registers to one or more slices but then does not use that slice for communications, additional system inefficiencies may arise from suboptimal selection of serving AMF and registration area.

[0102] Similarly, as described in the above example, a WTRU may sometimes establish a PDU session because some conditions are met (e.g., a request from an application), however, the WTRU may not actually be using the PDU session. For example, the WTRU may establish a PDU session and proceed for a long period of time before using the PDU session to transmit or receive data, or may not use the PDU session at all to transmit and receive data. This type of behavior is undesirable in terms of management of network resources. For example, when the PDU session quota is reached, this may result in a second WTRU's PDU session establishment request for the slice being rejected, even if the second WTRU actually wishes to use the PDU session for communication. As previously explained, the number of WTRUs that can establish PDU sessions in a network slice may be limited by the NSACF. If WTRUs that are not using an established PDU session are counted towards the PDU session quota for the slice, it would be an inefficient use of network resources. One or more methods are needed to allow the network to have the ability to detect when a WTRU is underutilizing a PDU session so that the PDU session can be terminated.

[0103] To address the above and other issues, methods are described herein that provide solutions to these and other issues. In addition, these techniques can be used to further address problems that exist in existing wireless systems (e.g., 5G systems) and other wireless systems. Such approaches can enable wireless systems to operate more efficiently, use less power, operate at higher speeds, operate at higher capacity, etc.

[0104] As described above, when the WTRU attempts to establish a PDU session, the PDU session request may be rejected and a cause code may be transmitted to the WTRU, indicating that the reason why the PDU session establishment request was rejected is that the maximum number of PDU sessions has been reached.

[0105] It may be advantageous to indicate to the WTRU when a slice has reached its PDU session limit. For example, the network may transmit this indication to the WTRU when transmitting a NAS message such as a Registration Accept message or a WTRU Configuration Update message to the WTRU. By proactively providing this indication to the WTRU, undesired PDU session establishment requests may be avoided.

[0106] In addition, the network may extend the EAC (early admission control) concept to include PDU session admission control. Therefore, the NSACF may configure the SMF to activate the EAC also for the PDU sessions assigned to the S-NSSAI, referred to herein as the P-EAC. The SMF may subscribe to P-EAC notifications, such as when the SMF performs a first network slice availability check and update process. The NSACF may set thresholds to trigger the activation or deactivation of the P-EAC in the SMF. These thresholds may be set based on WTRU-related analysis or network slice load analysis. For example, WTRU communication analysis and expected WTRU behavior analysis, such analysis may be requested for a specific PDU session when the WTRU is in a specific location and at a specific time. These analyses may include session inactivity times and application traffic start and stop times, as well as predictions of the number of WTRUs and PDU sessions associated with the S-NSSAI, which may be used by the NSACF to set the threshold.

[0107] When the SMF is configured with P-EAC (for example, when the NSACF transmits an EAC notification to the SMF), if the P-EAC flag is activated, the SMF may perform a "number of PDU sessions for each network slice availability check" operation after the PDU session context is created and before the SMF accepts the establishment of the PDU session (for example, after successful DN authentication / authorization or if PDU session authentication / authorization is not required).

[0108] The SMF may use the P-EAC notification from the NSACF and the SMF may provide the WTRU with an early indication of a PDU session modification command that may have reached the PDU session limit (e.g., providing a grace period within a PCO (Protocol Configuration Option) Information Element (IE) or a dedicated IE). In addition, the SMF may use the information from the NSACF to provide the WTRU with an indication of what S-NSSAI the PDU session may be moved to before the grace period expires. This may be done by providing a newly configured NSSAI with a tagged S-NSSAI.

[0109] The WTRU may use some indication, such as an indication that the PDU session limit has been reached or a P-EAC indication, to move the PDU session to a different S-NSSAI or if an additional access network (AN) is available and the EAC is not applicable to the additional AN (e.g., the EAC is applicable to 3GPP AN but not to non-3GPP access networks). The WTRU may move the PDU session to a different access network. For example, the WTRU may move the PDU session from a first S-NSSAI / AN combination to a second S-NSSAI / AN combination, where the S-NSSAI of both the first combination and the second combination are the same. This may be done because the AN of the second combination is not limited.

[0110] Figure 2 An example of how to transmit an active indication to a WTRU (e.g., regarding a PDU session or slice), such as described herein, is illustrated. As shown, at 201, the AMF may receive a notification from the NSACF that a slice (e.g., identified by an S-NSSAI) has reached its PDU session limit. When the AMF responds to a registration request from the WTRU, the AMF may notify the WTRU that the slice (e.g., identified by an S-NSSAI) has reached its PDU session limit. For example, the AMF may choose to wait to notify the WTRU until the WTRU enters connected mode by transmitting a registration request. Alternatively, the AMF may notify the WTRU that the slice (e.g., identified by an S-NSSAI) has reached its PDU session limit by transmitting a WTRU Configuration Update message to the WTRU. For example, if the WTRU is already in connected mode, the AMF may choose to transmit the WTRU configuration update message to the WTRU, or if the WTRU is in idle mode, the AMF may choose to initiate a paging procedure for the WTRU so that the AMF may transmit the WTRU configuration update message to the WTRU. These different example scenarios are shown as different options in the figure.

[0111] At 202a, the WTRU may transmit a registration request to the AMF. For example, the registration request may be a mobility registration update. The AMF may detect that the S-NSSAI identified as having reached its PDU session limit at 201 is in the WTRU's requested NSSAI.

[0112] At 203a, the AMF transmits a registration accept message to the WTRU. The registration accept message includes an indication that the S-NSSAI has reached its PDU session limit and, in some instances, an associated backoff timer. The indication indicates that the WTRU is prohibited from attempting to transmit a PDU session establishment request for the slice until the associated backoff timer expires or until the limit is cleared. The existing PDU session is maintained. If the registration accept message includes an indication that the maximum number of WTRUs per network slice has been reached, the AMF may transmit a list of S-NSSAIs in the configured NSSAI, which the WTRU may use when attempting a new registration (e.g., a mobility registration). Some methods may use a network slice transfer mechanism for the WTRU to move the PDU session to a target slice when the maximum number of WTRUs for the slice is reached, however, this is an area where improvement is needed because there are legacy wireless system designs that do not have a mechanism for how the target slice is selected (e.g., among several slices). For example, the network (e.g., the AMF) may provide a list of target S-NSSAIs in the configured NSSAI, and the WTRU may select based on its needs. If the network wants to implement specific network slices as targets, the network may mark those S-NSSAIs within the configured NSSAI.

[0113] At 202b, the AMF may detect that the WTRU is registered to the S-NSSAI identified at 201 as having reached its PDU session limit, which S-NSSAI is among the allowed NSSAIs of the WTRU.

[0114] At 203b, the AMF may transmit a WTRU Configuration Update message to the WTRU. The WTRU Configuration Update message may include an indication that the S-NSSAI has reached its PDU session limit and, in some instances, an associated backoff timer. The indication indicates that the WTRU is prohibited from attempting to transmit a PDU session establishment request for the slice until the associated backoff timer expires or until the limit is cleared. The existing PDU session is maintained.

[0115] The limit may be cleared by the network (e.g., before the back-off timer expires) at 204. The limit may be cleared by the AMF transmitting a NAS message such as a Registration Accept or WTRU Configuration Update to the WTRU without an indication that the S-NSSAI has reached its PDU session limit, with an indication that the S-NSSAI has reached its PDU session limit without a back-off timer, or with an indication explicitly indicating that the limit has been removed.

[0116] Alternatively, the indication from the NSACF at 201 may have indicated to the AMF that the slice is approaching its PDU sessions and all WTRUs or a specific one or more WTRUs will be limited in the number of PDU sessions they establish within the slice.

[0117] The REGISTRATION ACCEPT message at 203a or the WTRU CONFIGURATION UPDATE message at 203b may be used by the AMF to indicate to the WTRU that the WTRU is limited in the number of PDU sessions that it may establish in the slice. The AMF may also provide the WTRU with a limit value (e.g., an integer value) and in some instances a backoff timer that may be used to determine when the limit may be considered for removal, and possibly a list of slice replacements (e.g., a mapping), as described herein. Furthermore, as described above, the limit may also be removed via an indication from the AMF.

[0118] When the network has indicated to the WTRU that a slice has reached its PDU session limit, the WTRU may behave differently when evaluating URSP rules. For example, if the backoff timer associated with the PDU session limit indication for the slice is still running (e.g., the limit has not been removed), the WTRU may consider all routing descriptors (RSDs) including the S-NSSAI to be invalid until the backoff timer expires or the limit is removed. In another example, if the WTRU receives an EAC indication for an S-NSSAI, then the WTRU may consider all RSDs including the S-NSSAI to be invalid or of lower priority until the EAC indication has been removed.

[0119] Alternatively, when the network has indicated to the WTRU that there is a limit on how many PDU sessions the WTRU may establish in a slice, the WTRU may behave differently when evaluating the URSP rules. For example, if the backoff timer associated with the WTRU's PDU session limit indicated for the slice is still running and / or the limit has not been removed, then if the RSD does not match an existing PDU session and if the number of PDU sessions that the WTRU has established in the slice has reached the maximum value indicated by the network, then the WTRU may consider all RSDs including the S-NSSAI to be invalid. The WTRU may consider the limit to be in place until the backoff timer expires or the limit has been removed.

[0120] As described above, the WTRU may be registered to a slice by not using resources of a slice other than the resources of the slice required to maintain a NAS connection and registration with the AMF.

[0121] The NSACF may detect that the WTRU has been registered to the slice for a relatively long time but has not established a PDU session. In such a scenario, the NSACF may trigger (e.g., transmit a message when this occurs, or may establish such a rule before this occurs) the AMF to deregister the WTRU from the slice and provide the WTRU with a different slice (e.g., a less important slice, a lower priority, or a slice not subject to NSAC) that may be used instead.

[0122] Figure 2 The example flow shown may also be used to describe how to configure the WTRU with an alternate S-NSSAI that is currently being underutilized by the WTRU. The example is as follows.

[0123] At 201, the AMF may receive a notification from the NSACF that the WTRU is registered to a slice (eg, identified by an S-NSSAI) but has not established a PDU session for a relatively long period of time. The notification may include a replacement S-NSSAI.

[0124] At 202a, the WTRU transmits a registration request to the AMF. For example, the registration request may be a mobility registration update. The AMF may detect that the S-NSSAI identified at 1 in the WTRU's requested NSSAI has been underutilized by the WTRU. In addition to the NSACF notification, the AMF may consider any of: a registration quota threshold (e.g., configured / enabled per slice), and / or whether the WTRU has (e.g., unused) PDU sessions for the slice before initiating logic for handling slices that are not used / underutilized by the WTRU.

[0125] At 203a, the AMF may transmit a registration accept message to the WTRU. The registration accept message includes a replacement S-NSSAI in the allowed NSSAI. The registration accept message also indicates to the WTRU that the S-NSSAI has been replaced with the replacement S-NSSAI. The replacement S-NSSAI may not be in the configured NSSAI of the WTRU, however, the indication from the network may be interpreted by the WTRU as an indication that the WTRU may consider the replacement S-NSSAI to be equivalent to the S-NSSAI in the current PLMN. If the WTRU has an existing PDU session in the S-NSSAI, the WTRU may consider the PDU session to be terminated. In response to the slice being replaced, the WTRU may remove the replaced slice from its configured NSSAI or mark it as inaccessible for a period of time. Alternatively, the AMF may transmit a registration acceptance for allowed NSSAIs excluding unused / underutilized slices with an indication / reason of "unused / underutilized slices" and / or a timer that controls when the WTRU may attempt to re-register for the slice.

[0126] At 202b, the AMF may detect that the S-NSSAI identified at 1 among the allowed NSSAIs of the WTRU has been underutilized by the WTRU.

[0127] At 203b, the AMF may transmit a WTRU configuration update message to the WTRU. The WTRU configuration update message includes a replacement S-NSSAI in the allowed NSSAI. The WTRU configuration update message may also indicate to the WTRU that the S-NSSAI has been replaced with the replacement S-NSSAI. The replacement S-NSSAI may not be in the configured NSSAI of the WTRU, however, the indication from the network may be interpreted by the WTRU as an indication that the WTRU may consider the replacement S-NSSAI to be equivalent to the S-NSSAI in the current PLMN. If the WTRU has more than one PDU session in the S-NSSAI, the WTRU may consider the PDU session to be terminated and the WTRU may attempt to establish a new PDU session with the replacement S-NSSAI. If a re-registration timer for unused / underutilized slices is provided, the WTRU may not attempt to re-register until the timer expires.

[0128] Note that the replacement S-NSSAI associated with the S-NSSAI may be encoded as an S-NSSAI information element.

[0129] At 204, the restriction on registering to the S-NSSAI may be cleared and the WTRU's association with the replacement NSSAI may be cleared by repeating 201 to 203 above without the replacement S-NSSAI.

[0130] When the WTRU deregisters, the WTRU may delete the information about the replacement S-NSSAI.

[0131] The RSD of the URSP rule may include an S-NSSAI replacement trigger flag. The S-NSSAI replacement trigger flag may indicate to the WTRU that under certain conditions, the WTRU may replace the S-NSSAI in the RSD with a replacement S-NSSAI. The condition that triggers the WTRU to perform the replacement may be a UAC broadcast indication indicating that the S-NSSAI is prohibited, an indication from the AMF that the EAC is active for the S-NSSAI, or a situation where the WTRU previously attempted to establish a PDU session for the slice and the backoff timer associated with the rejection is still running.

[0132] The benefit of providing the WTRU with an alternative S-NSSAI is that if the network wants the WTRU to select a different slice, the network can avoid updating all of the configured NSSAI, allowed NSSAI, and URSP rules.

[0133] In another example, the WTRU may implement slice inactivity tracking, such as where the WTRU may actively track the activity / usage of the slices and if there is no activity / usage for a predetermined time, the WTRU will deregister itself from those slices.

[0134] After successfully registering with the core network, the WTRU may have received a list of allowed NSSAIs and a negotiated value for the slice inactivity timer. The slice inactivity timer duration may be mutually agreed / negotiated between the WTRU and the network (e.g., 5G core network) via NAS signaling.

[0135] The slice inactivity timer may track inactivity for each slice present in the allowed NSSAI, such as if the slice has been registered with the core network, however, no PDU session has been established for it, or a PDU session has been established without any data activity for the slice inactivity duration.

[0136] A slice inactivity timer may be started per allowed S-NSSAI in order to track the activity of each individual slice. If there is no activity (S-NSSAI) for a slice, the WTRU may deregister itself from that slice by triggering a NAS signaling procedure (e.g., mobility registration request) that excludes the inactive slices (S-NSSAI) from the requested NSSAI. In this way, the WTRU may be able to proactively exclude slices (S-NSSAI) for which no PDU sessions are established or for which there is no data activity for the slice inactivity duration.

[0137] In some cases, PDU sessions may be selectively transferred.

[0138] The WTRU may provide assistance information to help the network (e.g., a functional node, a WTRU acting as a relay, a base station, an AMF, an SMF, etc.) predict traffic activity on a PDU session by using the concept of NAS Release Assistance Information (NAS-RAI). For example, the NAS-RAI may indicate that no uplink or downlink data transmission is expected for a period of time on the associated PDU session. The network, such as the SMF, may use this information to determine the priority of what PDU sessions may be transferred to another network slice or may be torn down. When determining what PDU sessions may be transferred to another network slice or may be torn down, a network function, such as the AMF or SMF, may use this information in isolation or in combination with slice load and WTRU-specific analysis as described herein. In addition, the network may use this information to determine the duration of a back-off timer given to the WTRU to control admission to a network slice. In addition, the network may provide the WTRU with a prediction of when the PDU session may be torn down (e.g., in the form of a grace period) based on the EAC and / or P-EAC.

[0139] The WTRU may use the NAS release information on every Modify PDU Session Establishment Request or only after the WTRU has been notified by the network that it may reach the EAC or P-EAC. Figure 3 An example of a call flow is provided as to how this mechanism may be used, as explained in further detail herein.

[0140] The RAI indication may be an access stratum indication that is included by the WTRU when transmitting data to the network. The RAI may be an access stratum indication that indicates to the base station that no subsequent uplink or downlink data transmission (e.g., an acknowledgement or response from an application server) is expected, and therefore the base station may release the RRC connection of the WTRU. This may be communicated to the AMF via an N2 WTRU Context Release Request. The AMF may indicate to the SMF that the PDU Session is not expected to see activity for a relatively long time, and the SMF may use this indication to determine to release the PDU Session.

[0141] In addition, the WTRU may include the NAS-RAI (Non Access Stratum Indication) which indicates to the AMF that no subsequent uplink or downlink data transmission is expected for a long time, allowing the release of the PDU Session. The AMF may indicate to the SMF that the PDU Session is not expected to see activity for a relatively long time, and the SMF may use the indication to determine to release the PDU Session. Alternatively, the SMF may use the NAS-RAI indication to deactivate the PDU Session once there is no further downlink data, and thus the PDU will not be counted towards the maximum number of PDU Sessions in the slice. The SMF may update the NSACF with the reduced flag.

[0142] Figure 3 An example of WTRU assisted PDU session early admission control is illustrated. Figure 3 In the example process of , the network provides a grace period to the WTRU. In response to a registration request from the WTRU, the network may provide a grace period to the WTRU. For example, the network may choose to wait to transmit the grace period to the WTRU until the WTRU enters connected mode by transmitting a registration request. Alternatively, the network may transmit the grace period to the WTRU by transmitting a WTRU configuration update message to the WTRU. For example, if the WTRU is already in connected mode, the network may choose to transmit the WTRU configuration update message to the WTRU, or if the WTRU is in idle mode, the network may choose to initiate a paging procedure for the WTRU so that the network may transmit the WTRU configuration update message to the WTRU. These different example scenarios are shown as different options in the figure.

[0143] At 300a and / or 300b, the NSACF and / or other network functions (e.g., the AMF or SMF) involved in the EAC process may derive early admission control thresholds based on network analysis (e.g., WTRU-related analysis and / or network slice analysis and / or any analysis described herein).

[0144] At 301a (eg, conditionally), the WTRU may request establishment of a PDU session and the WTRU may provide NAS release assistance information from the beginning.

[0145] At 302, the NSACF may transmit an early admission control notification to the SMF so that the SMF sets the P-EAC flag

[0146] At 302a (eg, conditionally), the WTRU may issue a registration request (eg, a mobility registration).

[0147] At 302b (e.g., conditionally), the AMF may provide a grace period to the WTRU, which is derived from network analysis and possibly from the NAS-RAI transmitted by the WTRU. In some examples, the grace period may be a time value indicating when the PDU session will be released if the network detects no activity on the PDU session.

[0148] At 302c (eg, conditionally), the AMF may provide a grace period to the WTRU using a message (eg, a UE Configuration Update (UCU) command), the grace period being derived from network analysis and possibly from a NAS-RAI transmitted by the WTRU.

[0149] At 301b (eg, conditionally), the WTRU may request establishment of a PDU session and the WTRU may provide NAS release assistance information based on information received on the UCU or Registration Accept message.

[0150] At 303, the SMF may trigger the number of PDU sessions checked for each network slice before accepting the PDU session establishment request.

[0151] At 304 and 305, the NSACF may indicate whether the limit has been reached.

[0152] At 306a (e.g., conditionally), the SMF may accept the establishment of the PDU session requested by the WTRU if the number of PDU sessions per slice has not been reached. Based on network analysis as described herein, the SMF may communicate to the WTRU a prediction as to when the limit on the number of PDU sessions per network slice may be reached, such as a grace period in the form of a timer indicating an estimate as to when the limit may be reached.

[0153] At 306b (eg, conditionally) (eg, assuming that the acceptance at 306a did not occur), the SMF may derive a backoff timer value. This value may be based on analysis information obtained from a network data analysis function (NWDAF) and the NAS-RAI received from the WTRU.

[0154] At 306c (e.g., conditionally), the SMF may deny establishment of the PDU session requested by the WTRU if the number of PDU sessions per slice has been reached. Based on network analysis as described herein, the SMF may transmit a backoff timer to the WTRU indicating a prediction as to when a new PDU session may be requested.

[0155] In one example, the WTRU may receive information indicating that the reason a slice to which the WTRU is registered is restricted is that the slice has reached a PDU session limit. When the WTRU evaluates the URSP rules, the WTRU may consider all RSDs associated with the restricted slice to be invalid unless the RSD describes a PDU session that has been established. Later, the WTRU may detect that the restriction has been removed and no longer consider the restriction during URSP evaluation. The WTRU may detect / determine that the restriction has been removed based on a message from the network or when a timer expires.

[0156] In one example, the WTRU may receive information indicating that the reason a slice is restricted is that the maximum number of slices has been reached for the WTRU. The WTRU may receive a replacement slice name (e.g., a replacement S-NSSAI), terminate a PDU session associated with the restricted slice, register with the replacement slice and / or establish a PDU session in the replacement slice. When the WTRU evaluates URSP rules, the WTRU may consider the restricted S-NSSAI to be equivalent to the replacement S-NSSAI. Later, the WTRU may detect / determine that the restriction has been removed and no longer consider the restriction during URSP evaluation. The WTRU may detect / determine that the restriction has been removed based on a message from the network or when a timer expires.

[0157] In some instances, upon receiving a replacement slice, the WTRU may assume that the PDU session for that slice is terminated (e.g., no PDU session will exist until it is re-established).

[0158] In some instances, the WTRU may receive a set of replacement slices and upon a triggering event (e.g., as described herein), may transfer the PDU session to the replacement slices and interrupt use of the existing slices.

[0159] In some instances, upon receiving an indication of a replacement / alternative slice and / or upon a triggering event occurring, the WTRU may immediately stop using the current slice or shortly thereafter. In some instances, the S-NSSAI may be considered a slice type and the slice ID may never be seen by the WTRU. The slice ID may change without the WTRU's knowledge. When a replacement slice is received, the WTRU may (e.g., immediately or soon after) stop using the PDU session associated with the current S-NSSAI and establish a new PDU session with the replacement S-NSSAI.

[0160] The RSD of the URSP rule may include an S-NSSAI replacement trigger flag. The S-NSSAI replacement trigger flag may indicate to the WTRU that under certain conditions, the WTRU may replace the S-NSSAI in the RSD with a replacement S-NSSAI. The conditions that trigger the WTRU to perform the replacement may be a UAC broadcast indication indicating that the S-NSSAI is prohibited, an indication from the AMF that the EAC is active for the S-NSSAI, and / or a situation where the WTRU previously attempted to establish a PDU session for the slice and the backoff timer associated with the rejection is still running.

[0161] The benefit of providing the WTRU with an alternative S-NSSAI is that if the network wants the WTRU to select a different slice, the network can avoid updating all of the configured NSSAI, allowed NSSAI and / or URSP rules.

[0162] The NSACF can use network analysis such as WTRU information or slice congestion to set thresholds for network slice admission control.

[0163] By extending the concept of early admission control notification, the SMF / AMF can provide an indication to the WTRU as to when a slice has reached its limit on the number of WTRUs or number of PDU sessions.

[0164] The WTRU may provide assistance information to help the network such as AMF or SMF predict traffic activity on a PDU session by reusing the concept of NAS releasing assistance information.

[0165] The network, such as the SMF, may use the NAS-RAI to determine priorities regarding what PDU sessions may be transferred to another network slice or may be torn down. A network function, such as the AMF or SMF, may use this information in isolation or in combination with slice load and WTRU specific analysis as described herein when determining what PDU sessions may be transferred to another network slice or may be torn down.

[0166] The network, such as the AMF or SMF, may use NAS-RAI information to determine the duration of the back-off timer given to the WTRU to control admission to the network slice. In addition, the AMF and / or the SMF may provide the WTRU with a prediction of when the PDU session may be torn down, for example in the form of a grace period, based on the EAC and / or P-EAC.

[0167] The WTRU may use the NAS release information on every Modify PDU Session Establishment Request or only after the WTRU has been notified by the network that it is possible to reach EAC or P-EAC.

[0168] In one example method, the AMF may receive a notification that a slice has reached its PDU session limit. The AMF may detect the limit after the WTRU is registered to the slice and the WTRU later transmits a registration request that will be at or above the limit, or the AMF decides to proactively transmit a WTRU configuration update once the limit is reached or before the limit is reached. The WTRU may receive an indication that the S-NSSAI has reached its PDU session limit and an associated backoff timer. The indication indicates that the WTRU is prohibited from attempting to transmit a PDU session establishment request for the slice until the associated backoff timer expires or until the limit is cleared. Later, when new application traffic is initiated, the indication affects the URSP rule evaluation (e.g., invalidating some RSDs). The WTRU may receive an indication that the condition has been cleared.

[0169] In one example method, the AMF may receive a notification that a slice has reached its registration limit. The WTRU may attempt to register to the slice, or the AMF may proactively transmit a WTRU configuration update message to the WTRU registered to the slice. The WTRU may receive an indication that the S-NSSAI has reached its registration limit and a replacement S-NSSAI that the WTRU may use in place of the S-NSSAI. The WTRU may subsequently use the replacement slice in a process such as a PDU session establishment. The WTRU may receive an indication that the condition has been cleared and the WTRU may go back to using the initial S-NSSAI.

[0170] Figure 4An example of a replacement slice process is illustrated. At 401, the WTRU may receive information including a first allowed network slice selection assistance information (NSSAI) list, wherein the allowed NSSAI list is associated with at least a first single NSSAI (S-NSSAI). In some instances, the received information may further include one or more data network names (DNNs). At 402, the WTRU may receive a configuration update message indicating a second S-NSSAI (e.g., a replacement slice) associated with a second allowed NSSAI list. The configuration update message may also indicate that the second S-NSSAI is associated with the first S-NSSAI because it is its replacement slice. At 403, the WTRU may determine that a triggering event has occurred, such as receiving a unified access control (UAC) broadcast, receiving an AMF indication, determining that a backoff timer has expired, and / or receiving an indication of the second S-NSSAI. At 405, the WTRU may transmit a protocol data unit (PDU) session establishment request including the second S-NSSAI based on the triggering event. In some instances, the PDU session establishment request includes a DNN from one or more DNNs previously received. These exchanges may be performed between the WTRU and the network (e.g., AMF, SMF, base station, etc.). In some instances, there may be a PDU session that initially uses the first S-NSSAI, which may be terminated upon receipt of a message indicating the second S-NSSAI; further, a PDU session establishment request may be transmitted to replace the initial PDU session that was once in use with the first S-NSSAI. In some instances, the WTRU may transmit a registration request for the slice before transmitting the PDU request. In some instances, the WTRU does not need to transmit a registration request; because the network adds the replacement slice to the allowed NSSAI, it means that the WTRU has been registered to the slice without the WTRU requesting registration.

[0171] As described herein, all embodiments and examples are intended to be combinable, meaning that steps or features from one example may be optionally used in the method of another example. Further, all aspects of the embodiments and examples disclosed herein may be optional.

[0172] As described herein, a higher layer may refer to one or more layers in a protocol stack, or a specific sublayer within a protocol stack. A protocol stack may include one or more layers in a WTRU or a network node (e.g., an eNB, a gNB, other functional entities, etc.), each of which may have one or more sublayers. Each layer / sublayer may be responsible for one or more functions. Each layer / sublayer may communicate directly or indirectly with one or more of the other layers / sublayers. In some cases, the layers may be numbered, such as layer 1, layer 2, and layer 3. For example, layer 3 may include one or more of the following: non-access stratum (NAS), Internet protocol (IP), and / or radio resource control (RRC). For example, layer 2 may include one or more of the following: packet data convergence control (PDCP), radio link control (RLC), and / or medium access control (MAC). For example, layer 3 may include physical (PHY) layer type operations. The larger the number of a layer, the higher the layer is relative to other layers (e.g., layer 3 is higher than layer 1). In some cases, the foregoing examples may be referred to as layers / sublayers themselves, regardless of the layer number, and may be referred to as higher layers as described herein. For example, from highest to lowest, a higher layer may refer to one or more of the following layers / sublayers: a NAS layer, an RRC layer, a PDCP layer, an RLC layer, a MAC layer, and / or a PHY layer. Any reference to a higher layer in conjunction with a process, device, or system herein will refer to a layer higher than the layer of the process, device, or system. In some cases, references to a higher layer herein may refer to a function or operation performed by one or more layers described herein. In some cases, references to a higher layer herein may refer to information transmitted or received by one or more layers described herein. In some cases, references to a higher layer herein may refer to a configuration transmitted and / or received by one or more layers described herein.

[0173] Although features and elements are described above in specific combinations, it will be understood by those of ordinary skill in the art that each feature or element may be used alone or in any combination with other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (sent via a wired or wireless connection) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (such as built-in hard disks and removable disks), magneto-optical media, and optical media (such as CD-ROM disks and digital versatile disks (DVDs)). A processor associated with software may be used to implement a radio frequency transceiver for a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. A method implemented by a wireless transmit receive unit (WTRU), the method comprising: receiving a message from an AMF of a network, the message comprising allowed network slice selection assistance information (NSSAI), wherein the message is a registration accept message or a configuration update message, wherein a replacement single NSSAI (S-NSSAI) is part of the allowed NSSAI, wherein the message includes an indication that the replacement S-NSSAI is a replacement for a second S-NSSAI; and A request for PDU session establishment is transmitted to the network, wherein the request includes the replacement S-NSSAI.

2. The method of claim 1, wherein the message comprises a mapping for a list of multiple replacement S-NSSAIs, wherein the mapping comprises the replacement S-NSSAI and a current S-NSSAI.

3. The method according to claim 1, further comprising: A registration message is transmitted before receiving the message associated with the second S-NSSAI.

4. The method according to claim 1, further comprising: Evaluate UE Routing Selection Policy (URSP) rules, and consider the second S-NSSAI to be equal to the replacement S-NSSAI when evaluating the URSP rules.

5. The method of claim 4, wherein evaluating the URSP rules results in determining a third S-NSSAI.

6. The method of claim 4, wherein evaluating URSP rules results in determining to transmit the PDU session establishment to the network.

7. The method of claim 5, wherein the third S-NSSAI is the replacement S-NSSAI.

8. A wireless transmit receive unit (WTRU), the WTRU comprising: a processor operatively coupled to a receiver, the processor and the receiver configured to receive a message from an AMF of a network, the message comprising allowed network slice selection assistance information (NSSAI), wherein the message is a registration accept message or a configuration update message, wherein a replacement single NSSAI (S-NSSAI) is part of the allowed NSSAI, wherein the message includes an indication that the replacement S-NSSAI is a replacement for a second S-NSSAI; and A processor operatively coupled to a transmitter, the processor and the transmitter configured to transmit a request for a PDU session establishment to the network, wherein the request includes the replacement S-NSSAI.

9. The WTRU of claim 8, wherein the message includes a mapping for a list of multiple replacement S-NSSAIs, wherein the mapping includes the replacement S-NSSAIs and a current S-NSSAI.

10. The WTRU of claim 8, wherein the processor and the transmitter are configured to transmit a registration message prior to receiving the message related to the second S-NSSAI.

11. The WTRU of claim 8, wherein the processor is configured to evaluate UE Routing Selection Policy (URSP) rules and consider the second S-NSSAI to be equivalent to the replacement S-NSSAI when evaluating the URSP rules.

12. The WTRU of claim 11 , wherein evaluating the URSP rules results in determining a third S-NSSAI.

13. The WTRU of claim 11, wherein evaluating URSP rules results in a determination to transmit the PDU session establishment to the network. The method of claim 12 , wherein the third S-NSSAI is the replacement S-NSSAI.

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