Selecting secondary mobile network with DualSteer functionality and registering with secondary mobile network

Abstract

An embodiment of a method implemented by a wireless transmit-receive unit (WTRU) includes: receiving information related to a secondary mobile network (SMN) and including an indication of SMN selection rules from a primary mobile network (PMN) registered by the WTRU; selecting an SMN in response to the trigger and an SMN selection rule; registering to the selected SMN; and requesting establishment of a multi-access protocol data unit (MA-PDU) session having a DualSteer functionality and having one access branch on the registered SMN and another access branch on the registered PMN.

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 422,311, filed on November 3, 2022, the content of which is incorporated herein by reference. Summary of the Invention

[0003] This disclosure relates to information that can be related to 5G cellular and 5G core networks and can be applicable to consumer electronic devices, smartphones, tablets, head - mounted displays, connected vehicles, drones, set - top boxes, and core networks.

[0004] ATSSS and DualSteer.

[0005] PLMN selection, network selection in SNPN access mode, secondary MN selection, registration process, PDU session establishment process, PDU session modification process, and WTRU configuration update process.

[0006] And in order to implement the DualSteer function, embodiments are proposed in the following areas.

[0007] An architecture for implementing the DualSteer function on two different mobile networks.

[0008] A process for a WTRU to select a primary mobile network and register with the primary mobile network.

[0009] A modified MA PDU session establishment process - triggers related to receiving responses, content - to - message, and actions.

[0010] A process for a WTRU to select a secondary mobile network and register with the secondary mobile network.

[0011] The behavior / actions of a WTRU when operating on a secondary mobile network.

[0012] An embodiment of a method includes: a WTRU receiving information of at least one SMN; the WTRU initiating an MA - PDU session with DualSteer function; the WTRU selecting one of the at least one SMN; registering the WTRU with the selected one of the at least one SMN; and the WTRU performing at least one operation related to the one of the at least one SMN with which the WTRU is registered.

[0013] Another embodiment of a method implemented by a WTRU includes: receiving information related to an SMN and including an indication of an SMN selection rule from a PMN registered by the WTRU; selecting an SMN in response to a trigger and the SMN selection rule; registering with the selected SMN; and requesting to establish an MA-PDU session having a DualSteer function and having one access branch on the registered SMN and another access branch on the registered PMN.

[0014] An embodiment of a method implemented by a WTRU includes: receiving information related to an SMN from a PMN; selecting a PMN in response to the information related to the SMN; registering with the selected PMN; and requesting to establish an MA-PDU session having a DualSteer function and having one access branch on the registered PMN and another access branch in response to a trigger and based on QoS-related factors and the information related to the SMN. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] A more detailed understanding can be obtained from the following description given by way of example in conjunction with the accompanying drawings, in which like reference numerals in the figures represent like elements and in which:

[0016] Figure 1A is a system diagram showing an exemplary communication system in which one or more disclosed embodiments can be implemented;

[0017] Figure 1B is a system diagram showing an example wireless transmit / receive unit (WTRU) that can be used within the communication system shown in Figure 1A ;

[0018] Figure 1C is a system diagram showing an example radio access network (RAN) and an example core network (CN) that can be used within the communication system shown in Figure 1A ;

[0019] Figure 1D is a system diagram showing yet another example RAN and yet another example CN that can be used within the communication system shown in Figure 1A ;

[0020] Figure 2 is a diagram of a service data flow through dual connectivity according to an embodiment;

[0021] Figure 3 is a diagram of steps for enabling the DualSteer function for an MA PDU session according to an embodiment;

[0022] Figure 4It is a timing diagram of the MA PDU session setup with DualSteer function according to an embodiment;

[0023] Figure 5 It is a diagram of the architecture of the DualSteer session and DualSteer operation according to an embodiment;

[0024] Figure 6 It is a diagram of how the SMN information is stored in the EF; and

[0025] Figure 7 It is a flowchart of a method (e.g., implementable by a WTRU) for selecting a secondary mobile network (SMN), registering with the SMN, and then performing operations related to the SMN.

[0026] Figure 8 It is a flowchart of a method for requesting the establishment of an MA-PDU session with DualSteer function, which includes selecting and registering with an SMN.

[0027] Figure 9 It is a flowchart of a method for requesting the establishment of an MA-PDU session with DualSteer function, which includes selecting and registering with a PMN. Detailed Description

[0028] Abbreviations and Acronyms

[0029] 5QI 5G QoS Identifier

[0030] AMF Access and Mobility Management Function

[0031] ATSSS Access Traffic Steering, Switching and Shunting

[0032] DN Data Network

[0033] DC Dual Connectivity

[0034] DRB Data Radio Bearer

[0035] EF Elementary File

[0036] eNB Evolved Node B (base station)

[0037] gNB Next Generation Node B (base station)

[0038] GPRS General Packet Radio Service

[0039] HAPS High Altitude Platform Station

[0040] HARQ Hybrid Automatic Repeat Request

[0041] HPLMN Home Public Land Mobile Network

[0042] LADN Local Area Data Network

[0043] LTE Long Term Evolution

[0044] MA-PDU Multi-Access PDU

[0045] MCC Mobile Country Code

[0046] MCG Master Cell Group

[0047] ME Mobile Equipment

[0048] MM Mobility Management

[0049] MN Mobile Network

[0050] MNC Mobile Network Code

[0051] MT Mobile Terminal

[0052] NAS Non-Access Stratum

[0053] NID Network ID

[0054] NPN Non-Public Network

[0055] NR New Radio

[0056] NSSAI Network Slice Selection Assistance Information

[0057] NTN Non-Terrestrial Network

[0058] PDU Protocol Data Unit

[0059] PLMN Public Land Mobile Network

[0060] PMF Performance Measurement Function

[0061] PMN Primary Mobile Network

[0062] PNI-NPN Public Network Integrated NPN

[0063] QoS Quality of Service

[0064] RAN Radio Access Network

[0065] RAT Radio Access Technology

[0066] RF Radio Frequency

[0067] SA-PDU Single-Access PDU

[0068] SCG Secondary Cell Group

[0069] SDAP Service Data Adaptation Protocol

[0070] SDF Service Data Flow

[0071] SM Session Management

[0072] SMF Session Management Function

[0073] SMN Secondary Mobile Network

[0074] SNPN Standalone NPN

[0075] S-NSSAI Single NSSAI

[0076] SO-SNPN Subscriber-Owned SNPN

[0077] SST Slice / Service Type

[0078] TE Terminal Equipment

[0079] UE User Equipment

[0080] UPF User Plane Function

[0081] URI Uniform Resource Identifier

[0082] USIM Universal Subscriber Identity Module

[0083] VPLMN Visited PLMN

[0084] WTRU Wireless Transmit / Receive Unit

[0085] Figure 1A FIG. is a diagram illustrating an example communication system 100 that may implement one or more of the disclosed embodiments. The communication system 100 may be a multi-access system that provides content such as voice, data, video, messaging, broadcast, etc. to a plurality of wireless users. The communication system 100 may enable a plurality of wireless users to access such content through shared system resources including wireless broadband. 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.

[0086] As 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 will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d 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 one of which may be referred to as a station (STA)) may be configured to transmit 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 smartphone, a laptop computer, 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, a medical device and application (e.g., remote surgery), an industrial device and application (e.g., a robot and / or other wireless devices operating in the context of an industrial and / or automation processing chain), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any one of the WTRUs 102a, 102b, 102c, 102d may be interchangeably referred to as a UE.

[0087] The communication system 100 may further include base stations 114a and / or base stations 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 eNodeB (eNB), a master Node B, a master eNodeB, 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, etc. Although 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.

[0088] Base station 114a may be part of RAN 104, which may also include other base stations and / or network elements (not shown), such as base station controllers (BSCs), radio network controllers (RNCs), relay nodes, etc. Base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as cells (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide wireless service coverage to a specific geographical area that may be relatively fixed or may change over time. A cell may also be divided into cell sectors. For example, the cell associated with base station 114a may be divided into three sectors. Thus, in one embodiment, base station 114a may include three transceivers, i.e., one for each sector of the cell. In an embodiment, 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 transmit and / or receive signals in a desired spatial direction.

[0089] Base stations 114a, 114b may communicate with one or more of WTRUs 102a, 102b, 102c, 102d via air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, millimeter wave, infrared (IR), ultraviolet (UV), visible light, etc.). Any suitable radio access technology (RAT) may be used to establish air interface 116.

[0090] More specifically, as described above, 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, base station 114a in RAN 104 and WTRUs 102a, 102b, 102c may implement radio technologies, such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA) that may use Wideband CDMA (WCDMA) to establish 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).

[0091] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as Evolved UMTS Terrestrial Radio Access (E-UTRA) which may use Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-A Pro (LTE-A Pro) to establish the air interface 116.

[0092] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as NR radio access which may use NR to establish the air interface 116.

[0093] 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 jointly implement LTE radio access and NR radio access using, for example, the dual connectivity (DC) principle. Thus, the air interfaces used by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions to / from multiple types of base stations (e.g., eNBs and gNBs).

[0094] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wi-Fi), IEEE 802.16 (i.e., 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 Rate for GSM Evolution (EDGE), GSM EDGE (GERAN), etc.

[0095] Figure 1AThe base station 114b therein may be, for example, a wireless router, a master Node B, a master eNode B, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a local area such as a commercial premise, a home, a vehicle, a campus, an industrial facility, an aviation corridor (e.g., for drones), a road, etc. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-a, LTE-a Pro, NR, etc.) to establish a pico cell or a femto cell. As Figure 1A shown, the base station 114b may be directly connected to the Internet 110. Thus, the base station 114b may not need to access the Internet 110 via the CN 106.

[0096] The RAN 104 may communicate 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, fault tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 may provide call control, billing services, location-based services for mobile, prepaid calling, Internet connectivity, video distribution, etc., and / or perform advanced security functions such as user authentication. Although Figure 1A not shown, it will be appreciated that the RAN 104 and / or the CN 106 may communicate directly or indirectly with other RANs employing the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104 that may be utilizing the NR radio technology, the CN 106 may also communicate with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0097] CN 106 can also act as a gateway for the WTRU 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 Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and / or Internet Protocol (IP) in the TCP / IP Internet protocol suite. The network 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, the network 112 may include another CN connected to one or more RANs, and the other CN may employ the same RAT or a different RAT as the RAN 104.

[0098] Some or all of the WTRU 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRU 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, Figure 1A the illustrated WTRU 102c may be configured to communicate with a base station 114a that may employ a cellular-based radio technology and with a base station 114b that may employ an IEEE 802 radio technology.

[0099] Figure 1B is a system diagram showing an exemplary WTRU 102. As Figure 1B shown, the WTRU 102 may include a processor 118, a transceiver 120, transmit / receive elements 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, a non-removable memory 130, a removable memory 132, a power supply 134, a Global Positioning System (GPS) chipset 136, and / or other peripheral devices 138, etc. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with the embodiments.

[0100] The processor 118 can be a general-purpose processor, a dedicated processor, a conventional processor, a digital signal processor (DSP), multiple 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) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 can perform signal encoding, data processing, power control, input / output processing, and / or any other functions that enable the WTRU 102 to operate in a wireless environment. The processor 118 can be coupled to a transceiver 120, which can be coupled to a transmit / receive element 122. Although Figure 1B the processor 118 and the transceiver 120 are depicted as separate components, it will be appreciated that the processor 118 and the transceiver 120 can be integrated together in an electronic package or chip.

[0101] The transmit / receive element 122 can be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) via an air interface 116. For example, in one embodiment, the transmit / receive element 122 can be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 can be a transmitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In another embodiment, the transmit / receive element 122 can be configured to transmit and / or receive both RF signals and optical signals. It will be appreciated that the transmit / receive element 122 can be configured to transmit and / or receive any combination of wireless signals.

[0102] Although the transmit / receive element 122 is depicted as a single element in Figure 1B the WTRU 102 can include any number of transmit / receive elements 122. More specifically, the WTRU 102 can employ MIMO technology. Thus, in one embodiment, the WTRU 102 can include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals via the air interface 116.

[0103] The transceiver 120 can be configured to modulate the signals to be transmitted by the transmit / receive element 122 and demodulate the signals received by the transmit / receive element 122. As described above, the WTRU 102 can have multi-mode capabilities. Thus, the transceiver 120 can include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs (e.g., such as NR and IEEE 802.11).

[0104] 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. Additionally, the processor 118 may access information from and store data in any type of suitable memory such as non-removable memory 130 and / or removable memory 132. The non-removable memory 130 may include random access memory (RAM), 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, etc. In other embodiments, the processor 118 may access information from and store data in a memory that is not actually located on the WTRU 102, such as on a server or a home computer (not shown).

[0105] The processor 118 may receive power from a power supply 134 and may be configured to distribute power to and / or control power to other components in the WTRU 102. The power supply 134 may be any suitable device for powering the WTRU 102. For example, the power supply 134 may include one or more dry cells (e.g., nickel cadmium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), a solar cell, a fuel cell, etc.

[0106] The processor 118 may also be coupled to a 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 instead of information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) via an air interface 116 and / or may 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 obtain location information by any suitable location determination method while remaining consistent with the embodiments.

[0107] The processor 118 may also be coupled to other peripheral devices 138, which may include one or more software and / or hardware modules that provide additional features, functions, and / or wired or wireless connections. For example, the peripheral devices 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, Modules, FM radio units, digital music players, media players, video game player modules, Internet browsers, virtual reality and / or augmented reality (VR / AR) devices, activity trackers, etc. Peripheral device 138 may include one or more sensors. The sensors may be one or more of a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geographical location sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, a humidity sensor, etc.

[0108] The WTRU 102 may include a full-duplex radio, where some or all of the transmission and reception of signals (e.g., associated with a particular subframe 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 to reduce and / or substantially eliminate self-interference via hardware (e.g., chokes) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio, where some or all of the transmission and reception of signals (e.g., associated with a particular subframe for either UL (e.g., for transmission) or DL (e.g., for reception)).

[0109] Figure 1C is a system diagram showing the RAN 104 and the CN 106 according to an embodiment. As described above, the RAN 104 may employ E-UTRA radio technology to communicate with the WTRU 102a, 102b, 102c via the air interface 116. The RAN 104 may also communicate with the CN 106.

[0110] The RAN 104 may include eNode-Bs 160a, 160b, 160c, but it will be understood that the RAN 104 may include any number of eNode-Bs while remaining consistent with the embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRU 102a, 102b, 102c via the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, for example, the eNode-B 160a may use multiple antennas to transmit wireless signals to the WTRU 102a and / or receive wireless signals from that WTRU.

[0111] Each of eNode-Bs 160a, 160b, and 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, user scheduling in the UL and / or DL, etc. As Figure 1C shown, eNode-Bs 160a, 160b, and 160c may communicate with each other via the X2 interface.

[0112] Figure 1C The CN 106 shown 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 described as part of the CN 106, it will be appreciated that any of these elements may be owned and / or operated by entities other than the CN operator.

[0113] The MME 162 may be connected to each of eNode-Bs 162a, 162b, and 162c in the RAN 104 via the S1 interface and may act 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 the initial attachment of the WTRUs 102a, 102b, 102c, etc. The MME 162 may provide control plane functions for handover between the RAN 104 and other RANs (not shown) employing other radio technologies such as GSM and / or WCDMA.

[0114] The SGW 164 may be connected to each of eNode Bs 160a, 160b, and 160c in the RAN 104 via the S1 interface. The SGW 164 may generally route and forward user data packets to and from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions such as anchoring the user plane during handover between eNode-Bs, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, etc.

[0115] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to a packet switched network such as the Internet 110 to facilitate communication between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0116] CN 106 can facilitate communication with other networks. For example, CN 106 can provide the WTRUs 102a, 102b, 102c with access to a circuit-switched network such as the PSTN 108 to facilitate communication between the WTRUs 102a, 102b, 102c and traditional landline communication devices. For example, CN 106 can include, or communicate with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between CN 106 and the PSTN 108. Additionally, CN 106 can provide the WTRUs 102a, 102b, 102c with access to other networks 112, which can include other wired and / or wireless networks owned and / or operated by other service providers.

[0117] Although the WTRU is depicted as a wireless terminal in Figures 1A to 1D it is envisioned that in some representative embodiments, such a terminal can (e.g., temporarily or permanently) use a wired communication interface with the communication network.

[0118] In a representative embodiment, the other network 112 can be a WLAN.

[0119] A WLAN in infrastructure basic service set (BSS) mode can have an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP can access a distribution system (DS) or another type of wired / wireless network that loads and / or unloads traffic to / from the BSS or has an interface thereto. Traffic destined for an STA from outside the BSS can reach the STA through the AP and can be delivered to the STA. Traffic from an STA to a destination outside the BSS can be sent to the AP for delivery to the corresponding destination. Traffic between STAs within the BSS can be sent through the AP, e.g., where the source STA can send traffic to the AP and the AP can deliver the traffic to the destination STA. Traffic between STAs within the BSS can be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic can be sent between the source STA and the destination STA using direct link setup (DLS) (e.g., sent directly between them). In some representative embodiments, DLS can use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN using independent BSS (IBSS) mode may not have an AP, and STAs within the IBSS or using the IBSS (e.g., all STAs) can communicate directly with each other. The IBSS communication mode can sometimes be referred to as an "ad hoc" communication mode in this document.

[0120] When operating in 802.11ac infrastructure mode or a similar operating mode, the AP can transmit beacons on a fixed channel, such as the primary channel. The primary channel can be of a fixed width (e.g., a bandwidth of 20 MHz wide) or dynamically set width. The primary channel can be the operating channel of the BSS and can be used by the STA to establish a connection with the AP. In some representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) can be implemented, for example, in an 802.11 system. For CSMA / CA, STAs including the AP (e.g., each STA) can sense the primary channel. If a particular STA senses / detects the primary signal and / or determines the primary signal to be busy, the particular STA can back off. One STA (e.g., only one station) can transmit in a given BSS at any given time.

[0121] High Throughput (HT) STAs can communicate using a 40 MHz wide channel, e.g., by combining the primary 20 MHz channel with an adjacent or non - adjacent 20 MHz channel to form a 40 MHz wide channel.

[0122] Very High Throughput (VHT) STAs can support channels that are 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz wide. 40 MHz and / or 80 MHz channels can be formed by combining contiguous 20 MHz channels. A 160 MHz channel can be formed by combining eight contiguous 20 MHz channels or by combining two non - contiguous 80 MHz channels, which can be referred to as an 80 + 80 configuration. For the 80 + 80 configuration, after channel coding, the data can be passed through a fragment parser that can divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time - domain processing can be performed separately on each stream. The streams can be mapped to two 80 MHz channels and the data can be transmitted by the transmitting STA. At the receiver of the receiving STA, the above operations for the 80 + 80 configuration can be reversed and the combined data can be sent to the Media Access Control (MAC).

[0123] 802.11af and 802.11ah support operation modes below 1 GHz. The channel operation bandwidth and carrier are reduced in 802.11af and 802.11ah as compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV white space (TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support meter type control / machine type communication (MTC), such as MTC devices in a macro coverage area. The MTC device may have certain capabilities, for example, limited capabilities, including supporting (e.g., only supporting) certain and / or limited bandwidths. The MTC device may include a battery with a battery life higher than a threshold (e.g., to maintain a very long battery life).

[0124] A WLAN system that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) includes a channel that can be designated as a primary channel. The primary channel may have a bandwidth equal to the maximum common operation bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or restricted by the STA that supports the minimum bandwidth operation mode among all STAs operating in the BSS. In an example of 802.11ah, for an STA that supports (e.g., only supports) the 1 MHz mode (e.g., an MTC type device), the primary channel may be 1 MHz wide, even if the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operation modes. Carrier sensing and / or network allocation vector (NAV) setting may depend on the state of the primary channel. If the primary channel is busy, for example, due to an STA (which only supports the 1 MHz operation mode) transmitting to the AP, all available bands may be considered busy even if most of the available bands remain idle.

[0125] In the United States, the available band that can be used by 802.11ah is 902 MHz to 928 MHz. In Korea, the available band is 917.5 MHz to 923.5 MHz. In Japan, the available band is 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.11ah is 6 MHz to 26 MHz, depending on the country code.

[0126] Figure 1DFIG. 0 is a system diagram showing RAN 104 and CN 106 according to an embodiment. As described above, RAN 104 may employ NR radio technology to communicate with WTRU 102a, 102b, 102c via air interface 116. RAN 104 may also communicate with CN 106.

[0127] RAN 104 may include gNBs 180a, 180b, 180c, but it will be understood that RAN 104 may include any number of gNBs while remaining consistent with the embodiment. Each of gNBs 180a, 180b, 180c may include one or more transceivers for communicating with WTRU 102a, 102b, 102c via air interface 116. In one embodiment, gNBs 180a, 180b, 180c may implement MIMO technology. For example, gNBs 180a, 108b may utilize beamforming to transmit signals to and / or receive signals from gNBs 180a, 180b, 180c. Thus, for example, gNB 180a may use multiple antennas to transmit wireless signals to WTRU102a and / or receive wireless signals from that WTRU. In an embodiment, 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 located on unlicensed spectrum while the remaining component carriers may be located 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).

[0128] WTRU 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using transmissions associated with scalable parameter sets. For example, the OFDM symbol interval and / or the OFDM subcarrier interval may vary for different transmissions, different cells, and / or different portions of the radio transmission spectrum. WTRU 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using various or scalable length subframes or transmission time intervals (TTIs) (e.g., containing different numbers of OFDM symbols and / or lasting different lengths of absolute time).

[0129] gNBs 180a, 180b, 180c can be configured to communicate with WTRUs 102a, 102b, 102c in stand-alone configuration and / or non-stand-alone configuration. In stand-alone configuration, WTRUs 102a, 102b, 102c can communicate with gNBs 180a, 180b, 180c without also accessing another RAN (e.g., such as eNode Bs 160a, 160b, 160c). In stand-alone configuration, WTRUs 102a, 102b, 102c can use one or more of gNBs 180a, 180b, 180c as a mobility anchor. In stand-alone configuration, WTRUs 102a, 102b, 102c can communicate with gNBs 180a, 180b, 180c using signals in the unlicensed band. In non-stand-alone configuration, WTRUs 102a, 102b, 102c can communicate / connect with gNBs 180a, 180b, 180c while also communicating / connecting with another RAN (such as eNode-Bs 160a, 160b, 160c). For example, WTRUs 102a, 102b, 102c can 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 non-stand-alone configuration, eNode-Bs 160a, 160b, 160c can act as the mobility anchor for WTRUs 102a, 102b, 102c, and gNBs 180a, 180b, 180c can provide additional coverage and / or throughput to serve WTRUs 102a, 102b, 102c.

[0130] Each of gNBs 180a, 180b, 180c can be associated with a specific cell (not shown) and can be configured to handle radio access network resource management decisions, handover decisions, user scheduling in UL and / or DL, support for network slicing, DC, interworking between NR and E-UTRA, routing of user plane data towards user plane functions (UPFs) 184a, 184b, routing of control plane information towards access and mobility management functions (AMFs) 182a, 182b, etc. As Figure 1D shown, gNBs 180a, 180b, 180c can communicate with each other via the Xn interface.

[0131] Figure 1DThe CN 106 shown may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possibly data networks (DN) 185a, 185b. Although the foregoing elements are described as part of the CN 106, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0132] The AMF 182a, 182b may be connected via an N2 interface to one or more of the gNBs 180a, 180b, 180c in the RAN 104 and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, supporting network slicing (e.g., handling different protocol data unit (PDU) sessions with different requirements), selecting a particular SMF 183a, 183b, managing the registration area, terminating non-access stratum (NAS) signaling, mobility management, etc. The AMF 182a, 182b may use network slicing in order to customize the CN support for the WTRUs 102a, 102b, 102c based on the type of service that the WTRUs 102a, 102b, 102c are utilizing. For example, different network slices may be established for different use cases, such as services that rely on ultra-reliable low-latency (URLLC) access, services that rely on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, etc. The AMF 182a, 182b may provide control plane functions for handovers 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).

[0133] The SMF 183a, 183b may be connected via an N11 interface to the AMF 182a, 182b in the CN 106. The SMF 183a, 183b may also be connected via an N4 interface to the UPF 184a, 184b in the CN 106. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating WTRU 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.

[0134] UPF 184a and 184b can be connected via the N3 interface to one or more of gNBs 180a, 180b, 180c in RAN 104, which can provide the WTRUs 102a, 102b, 102c with access to a packet switched network, such as the Internet 110, to facilitate communication between the WTRUs 102a, 102b, 102c and IP-enabled devices. UPF 184, 184b can perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering DL packets, providing mobile anchoring, etc.

[0135] CN 106 can facilitate communication with other networks. For example, CN 106 can include, or communicate with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that is an interface between CN 106 and the PSTN 108. Additionally, CN 106 can provide the WTRUs 102a, 102b, 102c with access to other networks 112, which can include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c can be connected to DNs 185a, 185b via UPF 184a, 184b through the N3 interface to UPF 184a, 184b and the N6 interface between UPF 184a, 184b and local DNs 185a, 185b.

[0136] In view of Figures 1A to 1D and Figures 1A to 1D the corresponding descriptions, one or more of the functions described herein with respect to one or more or all of the following can be performed by one or more emulation devices (not shown): WTRUs 102a to 102d, base stations 114a to 114b, eNode-Bs 160a to 160c, MME 162, SGW 164, PGW 166, gNBs 180a to 180c, AMF 182a to 182b, UPF 184a to 184b, SMF 183a to 183b, DNs 185a to 185b, and / or any other device described herein. The emulation device(s) can be one or more devices configured to emulate one or more or all of the functions described herein. For example, the emulation device(s) can be used to test other devices and / or simulate network and / or WTRU functionality.

[0137] The simulation device can be designed to implement one or more tests on other devices in a laboratory environment and / or an operator network environment. For example, one or more simulation devices can perform one or more or all functions when 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 can perform one or more or all functions when temporarily implemented / deployed as part of a wired and / or wireless communication network. The simulation device can be directly coupled to another device for testing purposes and / or use over-the-air wireless communication to perform tests.

[0138] One or more simulation devices can perform one or more (including all) functions when not implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation device can be used to test test scenarios in a laboratory and / or an undeployed (e.g., for testing) wired and / or wireless communication network, in order to implement testing of one or more components. One or more simulation devices can be test equipment. The simulation device can transmit and / or receive data using direct RF coupling and / or wireless communication via an RF circuit (e.g., which can include one or more antennas).

[0139] The following is a description of how a WTRU (also referred to as a UE) operates on a primary mobile network (PMN) according to an embodiment.

[0140] A WTRU with DualSteer capabilities, where the WTRU:

[0141] · Receives a first set of secondary mobile network (SMN) information related to a second mobile network from a first mobile network;

[0142] · Selects the first mobile network based on the first set of SMN information;

[0143] · Registers with the first mobile network;

[0144] · Is triggered to start a multi-access protocol data unit (MA-PDU) session based on the QoS requirements of a service data flow (SDF) and the first set of SMN information; and

[0145] · Sends a PDU session establishment request that includes the DualSteer capabilities of the WTRU, the preferred MA-PDU session type of the WTRU, the access types supported by the WTRU for a second 3GPP access branch, and the access type that the WTRU "prefers" for the second 3GPP access branch based on factors such as the QoS requirements of an SDF.

[0146] The following is a description of the registration handling at the Access and Mobility Management Function (AMF) of the Primary Mobile Network (PMN) according to an embodiment.

[0147] An AMF with DualSteer capability:

[0148] · Provide a first set of SMN information related to the second mobile network and an indication that the AMF supports the DualSteer function to the RAN and / or WTRU;

[0149] · Receive a registration request from the WTRU, the registration request having an indication that the WTRU supports the DualSteer function; and

[0150] · Send a registration response to the WTRU, where the response indicates whether the AMF accepts or rejects the registration request from the WTRU.

[0151] The following is a description of the Protocol Data Unit (PDU) session establishment handling at the Session Management Function (SMF) of the Primary Mobile Network (PMN) according to an embodiment.

[0152] An SMF capable of DualSteer:

[0153] · Receive a PDU session establishment request from the WTRU, the PDU session establishment request including one or more of the following: an indication that the request is for a MA-PDU session, DualSteer capability, a preferred MA-PDU session type, the access types supported by the second 3GPP access branch, and the preferred access type of the second 3GPP access branch;

[0154] · Check the requested MA-PDU session type, and if the requested MABU session type is "one branch over 3GPP and another branch over non-3GPP" and the WTRU has registered both accesses, the SMF establishes user plane resources over 3GPP access and over non-3GPP access; and

[0155] · Check the requested MA-PDU session type, and if the requested MABU session type is "two branches over 3GPP" and the WTRU has only registered one 3GPP access branch, the SMF establishes user plane resources over that 3GPP access branch and sends a PDU session establishment response to the WTRU over that 3GPP access branch. The response may include one or more preferred Secondary Mobile Networks (SMNs) and / or one or more preferred access types and / or one or more SMN / access type combinations.

[0156] The following is a description of how the WTRU operates on a Secondary Mobile Network (SMN) according to an embodiment.

[0157] A DualSteer-capable WTRU registered to a first mobile network:

[0158] · Receive a first set of SMN information related to a second mobile network from the first mobile network;

[0159] · Receive a PDU session establishment response from the first mobile network, the PDU session establishment response including

[0160] o 1) An indication that the PDU session should be a MA-PDU session with DualSteer functionality, and

[0161] o 2) A second set of SMN information related to the second mobile network (the second mobile network may be the same as the second mobile network related to the first set of SMN mentioned previously, but is usually different);

[0162] · Select a second mobile network based on the first set of SMN information, the second set of SMN information, and a set of SMN selection rules;

[0163] · Register to the selected second mobile network, including in the registration request

[0164] o 1) An indication that the registration is for an SMN, and

[0165] o 2) The identity of the first mobile network;

[0166] · Deregister from the selected second mobile network based on connectivity, location, and / or finding a better SMN / access technology combination; and

[0167] · Switch the second 3GPP access branch from a source (e.g., previously selected) SMN to a target (e.g., newly selected) SMN.

[0168] The following is a description of the registration handling at the access mobility management function (AMF) of the secondary mobile network according to an embodiment.

[0169] An AMF with DualSteer capabilities:

[0170] · Receive a registration request from the WTRU, the registration request including an indication that the WTRU is requesting to use a mobile network for the second 3GPP access branch and an indication of the WTRU's primary mobile network;

[0171] · Use the indication received in the registration request to help determine whether to accept or reject the registration request; and

[0172] · Send a registration response to the WTRU, which indicates whether the registration is accepted or rejected. If rejected, the AMF will provide a (rejection) cause value and an indication of how long the mobile network should not be used as a secondary mobile network.

[0173] · The registration request also includes the identification of the source SMN / access technology combination and a list of PDU session IDs requested to be transferred to the second mobile network.

[0174] In the current versions of some smartphone technologies, the WTRU provides both its session management (SM) and mobility management (MM) functions to the core network. During the initial registration process and the mobility registration update process, the WTRU sends WTRU MM core network capability information to the access and mobility management function (AMF) in a non-access stratum (NAS) message. Similarly, the WTRU includes its 5GSM core network capabilities in the PDU session establishment / modification request. This latter message includes the access traffic steering, switching, and splitting (ATSSS) capabilities of the WTRU.

[0175] If the WTRU needs to access services that require registration, they may need to perform registration to the network. To perform this registration, according to an embodiment, the WTRU performs a series of steps:

[0176] · Public land mobile network (PLMN) selection or standalone non-public network (SNPN) selection - The process by which the WTRU selects a mobile network. This network can be a public network or a non-public network. The WTRU is configured with the priority of each mobile network. For example, the home PLMN can be configured with the highest priority. The WTRU follows rules to determine how to select from the available networks at a given location and when to look for a higher-priority network. For example, if the WTRU is in a visited PLMN (e.g., the WTRU is roaming), the WTRU periodically looks for its home PLMN, which is a higher-priority mobile network.

[0177] · Cell selection - The process by which the WTRU initially selects the best cell on the selected network and then "camped on" the cell.

[0178] · Cell reselection - The process by which the WTRU continuously evaluates the cell quality and decides to "camp on" a different cell if necessary.

[0179] · Registration - The process of notifying the network of the presence of the WTRU and providing some rough location information.

[0180] The WTRU may support carrier aggregation (CA); CA is typically provided via a single 3GPP access (e.g., New Radio (NR) or Long Term Evolution (LTE)), but allows the WTRU to receive via two or more cells. Each cell is on a different frequency carrier. The use of these two cells is managed entirely within the radio access network (RAN).

[0181] The WTRU may also support dual connectivity (DC); DC allows the WTRU to receive / transmit via two (or more) 3GPP accesses (or 3GPP access branches). The accesses may be NR (gNB) or LTE (eNB). In 5G, the initial deployment has one branch on LTE and a second branch on NR. However, the current deployment of DC also supports two branches on NR. In this case, the two branches are on different frequency bands (e.g., FR1 and FR2). To use DC, the WTRU typically requires a radio frequency (RF) front end to support both accesses. In dual connectivity, one branch is the primary branch (and part of the master cell group (MCG)), and the other branch is the secondary branch (and part of the secondary cell group (SCG)).

[0182] The WTRU may also support communication via a satellite link. This allows the WTRU to receive / transmit via a transparent satellite / repeater link (where the satellite / repeater is on a different orbit: GEO, MEO, LEO, HAPS). The WTRU may require an RF front end to communicate via the transparent satellite / repeater.

[0183] The WTRU may support various combinations of dual connectivity and carrier aggregation. The WTRU may have dual connectivity on two 3GPP access branches, and each of the access branches may use carrier aggregation. The set of cells on one access branch is called a cell group. Additionally, the WTRU may have dual connectivity with one branch or two branches on a transparent satellite / repeater link. For example, the following scenarios are supported:

[0184] o Branch 1: NR Branch 2: GEO satellite

[0185] o Branch 1: NR Branch 2: LEO / MEO satellite

[0186] o Branch 1: GE0 Branch 2: LEO / MEO satellite

[0187] Some technologies have allowed WTRUs with dual connectivity (DC) to operate on two 3GPP access branches. But DC does have some limitations. In DC, the WTRU is configured on how to map data radio bearers (DRBs) across the two access branches

[0188] · MCG bearers: The data bearers pass through the primary branch

[0189] ·SCG bearer: The data bearer is through the secondary branch

[0190] · Split bearer: The data bearer is split between the primary branch and the secondary branch. All processing is performed on the radio link control (RLC) layer in the primary branch, and all processing is performed under the (packet data convergence protocol) PDCP layer in the secondary branch.

[0191] In each case, the air transmission of the radio bearer is carried out on a single access branch.

[0192] Figure 2 Figure 200 shows how a downlink (DL) service data flow (SDF) travels through a 5G network and is transmitted via a data radio bearer (DRB).

[0193] At the entry point (user plane function (UPF)) 202, the group 204 of SDF 205 1 to 204 5 (each group can include a single or multiple SDFs) is mapped to the QoS flow 206 1 to 206 5 . These QoS flows 206 1 to 206 5 The traffic on reaches the SDAP layer 208 of the RAN layer, where the traffic is mapped to the DRB, i.e., DRB1 210 1 and DRB2 210 2 , and is transmitted over the radio interface via a single radio access branch 212 1 and 212 2 . It should be noted that for some technologies, the SDF is mapped to a single QoS flow 206, the QoS flow is mapped to a single DRB 210, and the DRB is transmitted over the air via a single 3GPP radio access branch 212. Therefore, different SDFs 205 may rely on dual connectivity (DC) and can be transmitted via different 3GPP accesses, but a single SDF stream 205 generally cannot be split / switched / steered / copied over 2 different 3GPP accesses.

[0194] Effectively, the traffic from the SDF 205 can only pass through one 3GPP access branch 212. The selection of the access branch can be changed through RAN layer reconfiguration, but this may be a very slow process.

[0195] Engineers have started to study the use cases and requirements where the SDF 205 can be split / switched / steered / copied over two (or more) 3GPP radio access branches 212. The objectives of this study include:

[0196] · Study additional use cases and potential service requirements for upper layer steering, splitting, and handover of 5GS supported WTRU traffic (e.g., related to the same data session, related to the same service data flow (SDF), related to the same application flow) across two (or more) 3GPP access links, assuming the WTRU subscribes only to a public land mobile network (PLMN), including the following scenarios:

[0197] · A single PLMN, PLMN plus (standalone) non-public network (NPN), two PLMNs

[0198] · The same or different 3GPP radio access technologies (RATs) (NR or NTN, plus one of NR, NTN, or LTE)

[0199] For the PLMN plus PLMN / NPN scenario, the two networks can be managed by the same operator or different operators (assuming a commercial agreement between them).

[0200] According to an embodiment, a new function is described that supports steering, handover, splitting, and duplication of traffic from a single SDF 205 across two 3GPP accesses (e.g., access branches) that can be different mobile networks.

[0201] Some technologies support the ATSSS function, which allows the WTRU to split / steer / handover / duplicate the traffic of a service data flow (SDF) across 3GPP access and non-3GPP access. 3GPP can also support dual connectivity (DC), which allows the WTRU to have a first SDF 205 on one 3GPP access 212 and a second SDF 205 on a second 3GPP access 212, but this does not allow splitting / steering / handover / duplication of the traffic of one of these SDFs. The 3GPP accesses 212 supported by dual connectivity (DC) can be terrestrial and non-terrestrial, and these accesses can be through a PLMN and an SNPN.

[0202] In at least some technologies, what is lacking is the flexibility to split / steer / handover / duplicate the traffic of a service data flow (SDF) 205 across two (or more) 3GPP accesses (including non-terrestrial 3GPP and SNPN).

[0203] A feasibility study has been conducted to identify use cases that may require this additional flexibility and to determine the associated new requirements (e.g., FS-DualSteer) arising from these use cases.

[0204] This new DualSteer function has two (or more) 3GPP accesses (e.g., for a single SDF 205) - one 3GPP access via the "first or primary mobile network (PMN)" and another 3GPP access via the second or secondary mobile network (SMN). In each case, the mobile network can be of a different type: PLMN, SNPN, Public Network Integrated NPN (PNI-NPN), etc. The primary mobile network can be a home mobile network or a visited mobile network. The secondary mobile network can be different from the primary mobile network. In this case, the behavior of the WTRU on the primary mobile network is improved to allow support for the DualSteer function. Additionally, the behavior of the WTRU on the secondary mobile network is completely different from its behavior on the primary mobile network, and these behaviors are generally defined. For example, the WTRU typically needs to know how to prioritize mobile networks. Once the WTRU knows the priority, the WTRU follows new rules to start looking for and selecting a secondary mobile network for DualSteer operation. Once the WTRU has found and selected a secondary mobile network, the WTRU operates on that secondary mobile network. Thus, the WTRU "knows" how to register with and deregister from the secondary mobile network (SMN), and also "knows" how to handle handovers of the secondary mobile network (e.g., from a source secondary mobile network to a target secondary mobile network).

[0205] The following common terms are used in this document.

[0206] The term mobile network (MN) is used to refer to any type of mobile network, including Public Land Mobile Network (PLMN), Non-Public Network (NPN), Standalone NPN (SNPN), and / or Public Network Integrated NPN (PNI-NPN).

[0207] The term second MN or secondary MN (SMN) is used to refer to the mobile network that provides the second (or other) 3GPP access.

[0208] The term first MN or primary MN (PMN) is used to refer to a home mobile network or a visited mobile network. It is the mobile network with which the WTRU first registers.

[0209] The term DualSteer function is used to mean a function that allows the WTRU and the User Plane Function (UPF) to apply steering modes to split, direct, switch, or duplicate traffic across two (or more) 3GPP access legs. The following steering modes can be supported: master-slave, minimum latency, load balancing, priority-based, and / or duplication.

[0210] The terms 3GPP access, 3GPP access branch, and 3GPP access path are used interchangeably. A 3GPP access branch can be via terrestrial access (e.g., NR and / or LTE) or via non-terrestrial access (e.g., GEO satellite, MEO satellite, LEO satellite, and / or HAPS).

[0211] The term PLMN selection is used to refer to the traditional PLMN selection process, e.g., as defined in previous technical versions.

[0212] The term primary MN selection is used to refer to the MN selection process that is specifically for finding an MN that supports the DualSteer function.

[0213] The term secondary MN selection is used to refer to the MN selection process that is specifically for finding a secondary MN.

[0214] The term SMN information is used to refer to information related to the SMN that: 1) can help the WTRU perform SMN selection, 2) can help the WTRU make a primary MN selection, and 3) can help the WTRU determine when to perform a cell reselection process for the SMN.

[0215] And the term PDU session assistance information is used to refer to information provided by the WTRU to the network (e.g., in a PDU session establishment request or a PDU session modification request) to help the network establish a MA-PDU session.

[0216] To implement the DualSteer function, embodiments are disclosed in the following areas:

[0217] · Architectures for implementing the DualSteer function on two different mobile networks

[0218] · Processes for the WTRU to select and register to a primary mobile network

[0219] · Modified MA-PDU session establishment process - new triggers related to receiving responses, new content to messages, new actions

[0220] · Processes for the WTRU to select and register to a secondary mobile network (SMN)

[0221] · Behavior / actions of the WTRU when operating on a secondary mobile network (SMN)

[0222] Applicable benefits that the disclosed embodiments may share include enabling the DualSteer function on a secondary mobile network (SMN), which can allow the WTRU and UPF to utilize the dual-radio capabilities of many devices to effectively split / direct / switch / copy traffic from a single session. The embodiments seek to improve how the WTRU selects a secondary mobile network and when the WTRU selects a secondary mobile network (SMN).

[0223] In the following description of the DualSteer function according to an embodiment, it is initially assumed that the WTRU is not registered on any MN. To enable the DualSteer function for a particular SDF, a number of communications or steps occur between the WTRU and one or more MNs to allow the setup and maintenance of a multi-access protocol data unit (MA-PDU) session with two (or more) 3GPP access branches (for the purpose of example, the communications / steps are described in connection with the setup and maintenance of an MA-PDU session with two 3GPP access branches). According to an embodiment, these communications / steps are shown in Figure 3 and Figure 4 and are described below in connection with these figures.

[0224] Figure 3 FIG. 300 is a diagram of the communications / steps for enabling the DualSteer function for an MA-PDU session according to an embodiment.

[0225] Figure 4 FIG. 400 is a diagram of an MA-PDU session setup with the DualSteer function according to an embodiment.

[0226] Referring to Figure 3 , at 302, the WTRU 304 receives a first set of one or more SMN information entries (Information 1) from the AMF 305 for network MN1, and at 306, determines an SMN list as described herein based on the first set of one or more SMN message entries (Information 1). This information (Information 1) may include and / or indicate information such as an SMN ID, the priority of the SMN, the access technology for the SMN, etc. Some of this information may be configured in the WTRU 304, while other information in this information may be provided by the network. In the latter case, the SMN information may be provided via RAN system information / along with RAN system information, or provided via a previous registration of the WTRU 304 with the mobile network (in which case it is assumed that the WTRU stores the previously received SMN information).

[0227] At 308, the WTRU 304 selects MN1 (also referred to as the primary MN), and at 310, the WTRU registers with this MN1. The selection and registration may be modified (and in this example, are modified) to enable the DualSteer function.

[0228] At 312, the WTRU 304 determines that it needs to initiate a MA-PDU session, and thus, it sends a MA-PDU session establishment request to the session management function (SMF) 314 of the MN1 via the 3GPP access 1 (MN1). The enhanced request message allows for setting up the session via two 3GPP accesses (e.g., two 3GPP access branches).

[0229] Still at 312 and at 316, the WTRU 304 receives a MA-PDU session establishment response that includes a second set of one or more SMN information entries (Information 2), which, as described herein, for example, includes and / or indicates an SMN list. After receiving the MA-PDU session establishment response, the WTRU 304 triggers activities related to the second 3GPP access branch and uses the received SMN information (Information 1 and / or Information 2) to assist the WTRU in selecting an SMN / access technology combination. The information (Information 1 and / or Information 2) may include information such as SMN ID, service area restrictions, time restrictions, edge application server capabilities, etc.

[0230] Still at 316, the WTRU 304 performs SMN selection based on Information 1, based on Information 2, and / or based on one or more other triggers (such as QoS, expected data rate, etc.).

[0231] At 318, the WTRU 304 registers with the selected SMN via the AMF 319, and at 320, the MA-PDU session establishment is completed for the selected SMN via the SMF 321.

[0232] And at 322, the WTRU 304 follows the SMN rules to determine when to deregister from the SMN with which the WTRU is currently registered and / or otherwise when to switch the established MA-PDU session to a different SMN.

[0233] Reference Figure 4 , according to an embodiment, is described in connection with FIG. 400 Figure 3 of the process (or a process similar thereto).

[0234] At 402, the WTRU 304 ( Figure 3 ) selects a PMN, for example, based on whether the PMN supports the DualSteer function.

[0235] At 404, the WTRU 304 registers with the selected PMN.

[0236] At 406, the WTRU 304 issues a service request to the PMN with which the WTRU is registered, and the service request includes a request to establish a MA-PDU session.

[0237] At 408, the WTRU 304 receives a MA-PDU session establishment response from the PMN, the MA-PDU session establishment response including one or more SMN information entries, the one or more SMN information entries including and / or indicating an SMN list, and the PMN establishes a part of the MA-PDU session associated with the first 3GPP access branch 410.

[0238] After receiving the MA-PDU session establishment response from the PMN, at 411, the WTRU 304 triggers an activity associated with the second 3GPP access branch 412 and uses the received SMN information to assist the WTRU in selecting an SMN for the second 3GPP access branch. The information may include and / or indicate an SMN ID, service area restrictions, time restrictions, edge application server capabilities, etc.

[0239] At 414, the WTRU 304 selects an SMN based on the received SMN information and / or based on one or more other triggers such as QoS, expected data rate, etc.

[0240] At 416, the WTRU 304 registers with the selected SMN.

[0241] At 418, the WTRU 304 requests a service from the SMN to which the WTRU is registered, the service request including a request to establish the second 3GPP access branch 412 of the MA-PDU.

[0242] And at 420, the second 3GPP access branch 412 is established in the SMN.

[0243] Thereafter, the WTRU 304 transmits and receives data through one or both of the first 3GPP access branch 410 and the second 3GPP access branch 412. For example, the WTRU 304, PMN, and SMN may cooperate to transmit data corresponding to an SDF, or even corresponding to a single SDF, through one or both of the 3GPP access branches 410 and 412. Also, in the case of transmitting data through both the first 3GPP access branch 410 and the second 3GPP access branch 412, the WTRU 304, PMN, and SMN may cooperate to determine which part of the data is transmitted through each of the first access branch and the second access branch.

[0244] According to an embodiment, an architecture supporting the DualSteer function for two 3GPP access branches (Access 1 and Access 2) on different MNs (Primary Mobile Network (PMN) and Secondary Mobile Network (SMN)) is described below.

[0245] Figure 5 is a diagram of the architecture of a wireless communication system 500 supporting the DualSteer function according to an embodiment.

[0246] System 500 is coupled to data network 501 and includes a WTRU 502, a secondary mobile network (SMN) 504, and a primary mobile network (PMN) 506, where the SMN and PMN are conceptually separated by dashed line 508. Even if not explicitly stated, the described functions and / or operations may be implemented on circuitry configured to perform such functions and / or operations. And interface N can be any type of suitable interface, such as an air interface.

[0247] WTRU 502 includes circuitry 510 configured to support and implement the DualSteer function and circuitry 512 configured to support and implement a performance measurement function (PMF). For example, circuitry 510 and 512 can be part of the same microprocessor or microcontroller, or can be part of two or more microprocessors or microcontrollers.

[0248] SMN 504 is configured to implement a second 3GPP access branch (Access 2) 514 and includes an access and mobility management function (AMF) 516, a session management function (V-SMF) 518, and a user plane function (V-UPF) 520. Interface N1 couples WTRU 502 and AMF 516 via the second 3GPP access branch 514, and interface N2 couples the second access branch to the AMF. Interface N2 couples the second 3GPP access branch 514 to AMF 516, and interface N3 couples the second access branch to V-UPF 520.

[0249] PMN 506 is configured to implement a first 3GPP access branch (Access 1) 522 and includes an Access and Mobility Management Function (AMF) 524, a Session Management Function (H-SMF) 526, a User Plane Function (H-UPF) 528, and a Policy Control Function (H-PCF) 530. The H-UPF 528 includes circuitry 532 configured to support and implement the DualSteer function and circuitry 534 configured to support and implement a Performance Measurement Function (PMF). For example, the circuitry 532 and 534 can be part of the same microprocessor or microcontroller, or can be part of two or more microprocessors or microcontrollers. Interface N1 couples the WTRU 502 and the AMF 524 via the first 3GPP access branch 522, interface N2 couples the first access branch to the AMF 524, interface N3 couples the first access branch to the H-UPF 528, interface N4 couples the H-UPF 528 to the H-SMF 526, interface N6 couples the H-UPH 528 to the data network 501, interface N7 couples the H-SMF to the H-PCF 530, interface N9 couples the V-UPF520 to the H-UPF, interface N11 couples the AMF 524 to the H-SMF, and interface N16 couples the V-SMF 518 to the H-SMF.

[0250] Still referring to Figure 5 , to support the DualSteer function in which the first 3GPP access is through MN1 and the second 3GPP access is through MN2, the embodiment relies on the home routed roaming architecture as described above in connection with Figure 5 where MN1 acts as the HPLMN and MN2 acts as the VPLMN. The DualSteer function 510 is located in the WTRU 502 and in the H-UPF528 of the primary MN 506. The WTRU 502 maintains two registrations: one registration through the primary MN 506 and a second registration through the SMN 504. User plane traffic is forwarded from the SMN 504 to the primary MN 506 via the N9 interface, similar to how user plane traffic is forwarded to the home network in the case of home routed roaming.

[0251] Regarding providing SMN information to the WTRU 502, the WTRU receives the SMN information of the SMN list.

[0252] For each SMN, according to the embodiment, the SMN information can include one or more of the following:

[0253] · SMN ID: The identifier of the SMN. For example, this can be a fully qualified domain name (FQDN), a 5- or 6-digit combination of the mobile country code (MCC) and mobile network code (MNC) assigned to a PLMN, or a combination of the PLMN ID and NID assigned to an SNPN.

[0254] · Available network slices. These can be identified by single network slice selection assistance information (S-NSSAI).

[0255] · Alternatively, available network slice types. These can be identified by slice / service type (SST).

[0256] · The priority associated with the SMN (e.g., the priority of the WTRU 502 using the SMN compared to other SMNs).

[0257] · SMN type: PLMN, SNPN.

[0258] · Access types supported by the SMN: This can be an indication of whether the SMN supports one or a combination of the following: NR, LTE, and / or satellite. For satellite access, the information can also include details about the satellite type: LEO, MEO, GEO.

[0259] · Service area restrictions: The locations where the services provided by the SMN are available. For example, the restrictions can be defined based on the following: geofencing, one or more tracking areas, one or more base stations, one or more cells of a base station.

[0260] · Time restrictions: The time when the services provided by the SMN are available. The services of the SMN can be obtained during a specific time (e.g., peak hours). Alternatively, the services can be obtained based on the expected satellite coverage (e.g., the satellite can provide 1 hour of coverage at a specific location every 2 days).

[0261] · List of edge application servers: The SMN can host multiple edge application servers or can access an edge data network hosting edge application servers. These can be identified by FQDN or URI.

[0262] · List of FQDNs and / or URIs that identify available domains and / or services.

[0263] · List of DNs (including LADN) served by the SMN.

[0264] · QoS performance: The SMN information can provide an indication of the QoS performance of a particular SMN / access technology combination. The QoS performance can be based on the reliability of the SMN / access technology combination. For example, this can be a measure of the packet loss rate on the SMN / access technology. Alternatively, the QoS performance can be based on the latency of the SMN / access technology combination. For example, this can be a measure of the latency between the WTRU and the UPF on the SMN / access technology.

[0265] · Traffic identification: The SMN information can provide an indication of the type of traffic to be sent over the SMN or the SMN / access technology combination. The traffic type can be identified by one or more SDFs, one or more SDF types, and / or one or more 5QI values.

[0266] It should be noted that if some of the SMN information is shared among multiple SMNs, the list can include an identifier that identifies a set of multiple SMNs. For example, an FQDN template (such as *.operator1.com) can refer to multiple SMNs with matching SMN IDs. There may also be wildcards for indicating "any SMN that supports DualSteer".

[0267] Figure 6 FIG. 600 is a diagram of a WTRU 604 according to an embodiment and how SMN information is stored on the WTRU in an elementary file (EF). The WTRU 604 includes a universal subscriber identity module (USIM) 602, a mobile device (ME) 606, a mobile terminal (MT) circuit 608, and a terminal equipment (TE) circuit 610.

[0268] According to an embodiment, the SMN information can be received by one or a combination of the following methods.

[0269] In a first method, the SMN information can be stored in an elementary file (EF) maintained in the universal subscriber identity module (USIM) 602 and available to the WTRU 604. Alternatively, the elementary file (EF) can be maintained in the mobile device (ME) 606 and available to the WTRU 604.

[0270] In a second method, the SMN information can be provided via non-access stratum (NAS) signaling by another MN (e.g., the primary MN). The SMN information can be provided by a registration acceptance message, a service acceptance message, a PDU session establishment response message, and / or a PDU session modification response message and / or a WTRU configuration update command. Alternatively, the SMN information can be obtained from other MNs via a new NAS signaling exchange (e.g., DualSteer request / response). As another alternative, the SMN information can be obtained via a policy container as part of the policy information provided to the WTRU 604.

[0271] More generally, the SMN information can be split, where some of the SMN information is provided by a first method and other SMN information is provided by a second method.

[0272] Regarding DualSteer assistance information for a WTRU to receive one or more SMNs from a primary MN, the WTRU 604 can receive DualSteer assistance information from the primary MN to assist the DualSteer function.

[0273] A first example of receiving DualSteer assistance information from the primary MN can be receiving an indication of whether the MN supports the DualSteer function.

[0274] A second example of receiving DualSteer assistance information from the primary MN can be receiving an indication of a list of preferred SMNs.

[0275] A third example of receiving DualSteer assistance information from the primary MN can be receiving SMN information.

[0276] Regarding a modified function that allows the WTRU 604 to select a primary MN and register with that primary MN to support DualSteer operation, the WTRU performs MN selection to pre-empt a cell of the primary MN. During the MN selection process, the WTRU 604 will consider an MN as a candidate for MN selection only if the MN supports the DualSteer function. Alternatively, during the MN selection process, the WTRU 604 will consider an MN as a candidate for MN selection only if (the MN supports the DualSteer function) and (the MN is allowed on the list of preferred SMNs). For example, if a PLMN is not on the "Forbidden PLMN" list, not on the "Forbidden PLMN for GPRS service" list, not on the "PLMN not allowed to operate at the current WTRU location" list, and not on the "MN not allowed to operate as a secondary PLMN" list, then the WTRU 604 can determine that the PLMN is allowed. As another alternative during the MN selection process, the WTRU 604 will consider an MN as a candidate for MN selection only if (the MN supports the DualSteer function) and (the MN is allowed on the list of preferred SMNs) and (the WTRU supports the access technology of the MN on the list of preferred SMNs). For example, the WTRU 604 may only support NR and LTE, and thus, will not consider any SMN in the list of preferred SMNs that is only accessible via non-terrestrial access.

[0277] If the WTRU supports DualSteer, then in the first option, the WTRU can always follow the process selected by the primary MN. In the second option, the WTRU can decide to follow the primary MN selection process only when a service data flow (SDF) requires the DualSteer function. For example, after power-on, the WTRU can follow the traditional MN selection process. In the registration acceptance message, DualSteer assistance information can be provided to the WTRU. If at a later time, the WTRU determines that it needs to establish a MA-PDU session with the DualSteer function, it first evaluates the DualSteer assistance information to determine whether the registered MN supports the DualSteer function, and if so, evaluates whether the WTRU can use any MN on the preferred SMN list. For example, if the MN on the preferred SMN list is on the WTRU's "forbidden PLMN" list, or the PLMN on the preferred SMN list uses an access technology not supported by the WTRU, the WTRU may not be able to use any MN. In this case, the WTRU can be triggered to perform a new primary MN selection.

[0278] In both the first and second options, once the WTRU selects the primary MN, it sends an initial registration request to the AMF of the primary MN. Subsequently, the WTRU updates its registration with the primary mobile network:

[0279] · Periodically update to remain reachable (periodic registration update); or

[0280] · Update when moving (mobility registration update); or

[0281] · Update its capabilities or renegotiate protocol parameters (mobility registration update).

[0282] In all registration requests, the WTRU can include an indication that the WTRU has the DualSteer function.

[0283] Regarding a new trigger for a WTRU to initiate or establish a MA-PDU session with DualSteer functionality, the WTRU may determine that a certain service data flow (SDF) requires DualSteer functionality. This determination implemented by the WTRU is not efficient because enabling DualSteer when it is not needed penalizes the WTRU and wastes radio resources. For the WTRU, DualSteer operation will generally require the WTRU to preoccupy on two 3GPP cells, and thus results in additional power consumption. Similarly, having the WTRU use the DualSteer functionality can cause the WTRU to use radio resources on two 3GPP access branches. Such use may reduce the radio resources available to other WTRUs. Thus, in an embodiment, it is proposed that the WTRU only initiate (through its registered MN) a MA-PDU session with DualSteer functionality when one or more of the following trigger conditions are met:

[0284] · The WTRU is using 3GPP access 1 and is registered to an MN that supports DualSteer functionality. That is, the registered MN supports DualSteer functionality

[0285] · The WRTU is registered to the registered MN, and the WTRU can use an MN on the preferred SMN list associated with the registered MN.

[0286] · The QoS requirements of the SDF cannot be met over 3GPP access 1. In one alternative, the WTRU can make this decision (whether to initiate a MA-PDU session with DualSteer functionality through its registered MN) based on information broadcast by the cell of 3GPP access 1. For example, this can include an indication of the current load in the cell, the current number of WTRUs being served in the cell, the percentage of radio resources used in the cell, the percentage of radio resources idle in the cell, etc. In a second alternative, the WTRU can make this decision (whether to initiate a MA-PDU session with DualSteer functionality through its registered MN) based on measurements made by the WTRU. For example, this can include the received signal quality in the cell, statistical measurements related to hybrid automatic repeat request (HARQ), etc. In a third alternative, the WTRU can make this decision (whether to initiate a MA-PDU session with DualSteer functionality through its registered MN) based on conditions known to the WTRU. For example, this can include the location of the WTRU, knowledge that the WTRU is at the cell edge, knowledge that an edge application server is available on the SMN, etc.

[0287] · Availability of a second 3GPP access. This can be based on service area restrictions included in the SMN information. Alternatively, this can be based on time restrictions included in the SMN information. For example, if the WTRU “knows” that the DualSteer function will be via non-terrestrial access, the WTRU can only request an MA-PDU session when that non-terrestrial access is available.

[0288] · The WTRU receives a device trigger message for an application on the WTRU. The payload included in the device trigger request message contains information about which application on the WTRU is expected to trigger an MA-PDU session establishment request. The device trigger can also include an indication that the downlink traffic associated with the triggered application requires the DualSteer function.

[0289] As part of the MA-PDU session establishment request, the WTRU can include PDU session assistance information as described herein. For example, the PDU session assistance information can include one or more of the following:

[0290] · The DualSteer function, and an indication of the steering functions supported by the DualSteer function and the steering modes supported by each steering function;

[0291] · Preferred MA-PDU session type: Different MA-PDU session types can be supported: Option 1: One branch is on 3GPP access and one branch is on non-3GPP access; Option 2: Both branches are on 3GPP access;

[0292] · The access type supported by the second 3GPP access branch;

[0293] · Preferred access type of the second 3GPP access branch;

[0294] · Requirements of the second 3GPP access branch;

[0295] · A PLMN on the WTRU's “forbidden PLMN” list, or the WTRU's “forbidden PLMN for GPRS service” list, or the WTRU's “PLMN not allowed to operate at the current WTRU location” list, or the WTRU's “MN not allowed to operate as a secondary MN” list.

[0296] This information can be used by the Session Management Function (SMF). The SMF can use the preferred MA-PDU session type to determine what type of MA-PDU session to set up. If the preferred MA-PDU session type == "Option 1: One branch is on 3GPP access and one branch is on non-3GPP access", the SMF can establish user plane resources on 3GPP access and non-3GPP access in a conventional manner. If the preferred MA-PDU session type == "Option 2: Both branches are on 3GPP access", the SMF can establish user plane resources on the 3GPP access branch and then send a PDU session establishment response to the WTRU on the same 3GPP access branch. The response can include one or more preferred secondary MNs and / or one or more preferred access types and / or one or more SMN / access type combinations.

[0297] In some cases, the WTRU can initiate a Single Access PDU (SA-PDU) session for an SDF and then determine that a Multi-Access PDU (MA-PDU) session is needed, or at least prefer the MA-PDU session. For example, this can occur when one or more of the QoS parameters exchanged between the WTRU and the network are modified, or when the WTRU determines that the QoS flow of the SA-PDU session no longer meets the QoS requirements. In such a case, the WTRU can decide to move the SDF to an MA-PDU session using a PDU session modification request. The PDU session modification request can include PDU session assistance information.

[0298] Regarding the function for selecting a secondary MN (SMN), once the WTRU receives a PDU session establishment response (or PDU session modification response) to establish an MA-PDU session using the DualSteer function, the WTRU uses the available SMN information and starts SMN selection.

[0299] The WTRU selects an SMN from multiple SMN / access technology combinations (if available and permitted) using one or more of the following SMN selection rules.

[0300] · In the first SMN selection rule, the WTRU selects an MN / access technology combination based on the priority of the MN in the network-provided list of preferred SMNs;

[0301] · In the second SMN selection rule, the WTRU selects an MN / access technology combination based on the WTRU's preference for SMN type: the WTRU may prefer to register to an SNPN rather than a PLMN (and vice versa);

[0302] · In the third SMN selection rule, the WTRU selects an MN / access technology combination based on the WTRU's preference for the access type: the WTRU may preferably register on one access type. For example, the WTRU may preferably register on a GEO satellite with a second 3GPP access;

[0303] · In the fourth SMN selection rule, the WTRU selects an MN / access technology combination based on cell strength: In traditional systems, an PLMN / access technology combination is mainly selected to provide a connection to the services offered by the mobile network. In this case, PLMN selection and cell selection are independent processes. As long as the quality of the cell is above a minimum threshold, the WTRU selects a PLMN based on established priority rules. Once registered on the home PLMN, the WTRU generally will not search for other PLMNs, even if there are higher priority PLMNs. It is expected that when the DualSteer function is enabled, the second 3GPP access branch will be mainly used to assist the first 3GPP access branch, thus allowing to direct / split / switch / copy SDFs over two 3GPP accesses (access branches). The ultimate goal is to improve user plane performance. In such cases, the advantage of jointly selecting the SMN / access technology combination for the cell pre-empted by the WTRU may be to produce the greatest improvement in user plane performance. For example, assume that SMN1 has a higher priority than SMN2, and the best cell on SMN1 is CellA, while the best cell on SMN2 is CellB. If the signal quality of CellB on SMN2 is better than the signal quality of CellA on SMN1, then if the WTRU selects SMN2 for the DualSteer function, user plane performance can be improved. In an embodiment, the WTRU determines the signal quality of multiple SMN / access technologies. The WTRU can decide to determine the signal quality of all SMN / access technologies, or only determine the signal quality of the configured K highest priority SMN / access technology combinations. For each SMN / access technology combination, the WTRU determines the strongest cell, and the WTRU selects the SMN / access technology combination that provides the best signal quality. In another embodiment, the WTRU determines the signal quality of multiple SMN / access technologies. The WTRU can decide to determine the signal quality of all SMN / access technologies, or only determine the signal quality of the configured K highest priority SMN / access technology combinations. For each SMN / access technology combination, the WTRU determines the strongest cell, and the WTRU selects the SMN / access technology combination that provides the best trade-off between priority and signal quality. For example, for each SMN / access technology combination, the WTRU can assign a priority value (P) and a signal strength value (S). The WTRU can then combine (e.g., mathematically, such as by addition or multiplication) P and S to determine a new ranking criterion (R), and select the SMN / access technology combination with the highest ranking (R). In yet another embodiment, the WTRU is configured with a minimum signal level for the SMN / access technology combination. The WTRU determines the signal quality of each SMN / access technology combination in priority order (i.e., the first SMN / access technology combination is the combination with the highest priority).If the signal level of the (highest priority) SMN / access technology combination is higher than (or equal to) the configured minimum signal level, the WTRU selects that SMN / access technology combination. Conversely, if the signal level of the (highest priority) SMN / access technology combination is lower than the configured minimum signal level, the WTRU proceeds to the next SMN / access technology combination (the SMN / access technology combination with the second highest priority).

[0304] · In the fifth SMN selection rule, the WTRU selects an MN / access technology combination based on service area restrictions: The WTRU can use its location to determine whether it is within the service area restrictions of an SMN / access technology. The WTRU can give preference to an SMN whose service area restriction defines a service area that includes the current WTRU location. That is, the WTRU is located at a position where it is allowed to receive service.

[0305] · In the fourth SMN selection rule, the WTRU selects an MN / access technology combination based on time restrictions: The WTRU can give preference to an SMN whose time restriction allows operation at the current time.

[0306] · In the seventh SMN selection rule, the WTRU selects an MN / access technology combination based on the availability of edge application servers for an SMN. The WTRU can give preference to an SMN that hosts or can access an edge application server to obtain SDF services.

[0307] · In the eighth SMN selection rule, the WTRU selects an MN / access technology combination based on the connection to one or more data networks (DNs). The WTRU can give preference to an SMN that has a connection to these DNs.

[0308] · In the ninth SMN selection rule, the WTRU selects an MN / access technology combination based on the supported network slice or network slice type. The WTRU can give preference to an SMN that supports a specific slice (e.g., identified by an S-NSSAI) or a specific slice type (e.g., identified by an SST).

[0309] · In the tenth SMN selection rule, the WTRU selects an MN / access technology combination based on support for an application area. That is, the operator of the SMN may have a commercial agreement with an application provider associated with that application area. The WTRU can give preference to these SMNs that support a specific application area.

[0310] · In the eleventh SMN selection rule, the WTRU selects an MN / access technology combination based on meeting one or more QoS requirements of the SDF. As a first example, the SDF may have a reliability requirement. In this case, the WTRU may select an MN / access technology combination with higher reliability or with reliability above a threshold. The measure of SMN reliability may be determined by the MN and broadcast as part of the system information, or this may be included in the SMN information. Alternatively, an indication of SMN reliability may be preconfigured in the WTRU. That is, the WTRU may be preconfigured with relative reliability information of one or more SMNs (e.g., terrestrial reliability > GEO satellite reliability > LEO satellite reliability > HAPS reliability). As a second example, the SDF may have a latency requirement. In this case, the WTRU may select an MN / access technology combination with lower latency or with latency below a threshold. The measure of latency may be determined by the MN and broadcast as part of the system information, or this (the measure of latency) may be included in the SMN information. Alternatively, this may be preconfigured in the WTRU. That is, the WTRU may be preconfigured with relative latency information (e.g., GEO satellite latency > LEO satellite latency > HAPS latency > terrestrial latency).

[0311] · In the twelfth SMN selection rule, the WTRU selects an MN / access technology combination based on policy information. The WTRU may be configured with a policy indicating which mobile network, or access technology, or mobile network / access technology combination should be selected. The policy may be used for a specific SDF, a group of SDFs, a specific type of SDF, a group of types of SDFs, a specific application, a group of applications, a specific 5QI, or a group of 5QI values.

[0312] It should be understood that additional SMN selection rules may be defined, where these additional SMN selection rules rely on SMNs that support other network capabilities (currently defined or to be defined in future mobile networks).

[0313] Regarding the WTRU performing registration on the selected secondary MN (SMN), once the WTRU has selected an SMN / access technology combination, the WTRU selects a suitable cell on the SMN / access technology combination and pre-empts that cell.

[0314] If the SMN is different from the primary MN, the WTRU attempts to register to the selected SMN (which has established a first 3GPP access with the primary MN) via a second 3GPP access. The registration request may include an indication that the MN is being used as the SMN. The WTRU may also provide an indication that the primary MN is being used for a MA-PDU session. The AMF of the SMN may use this information to determine whether to accept or reject the WTRU's request to register to the SMN. The network may wish to limit the number of WTRUs that use its network as the secondary 3GPP branch for DualSteer. For example, the network may be overloaded or may have limited resources, and the network may prefer to reserve its resources for its own WTRUs (WTRUs that use the network as the primary MN). In such a case, the network (AMF) may respond with a registration rejection and provide a suitable reason (e.g., "SMN rejection - overloaded" or "SMN rejection - limited resources" or "SMTN rejection – reserved"). The network (AMF) may additionally include the duration for which the MN should not be used as the secondary MN.

[0315] If the SMN is the same as the primary MN, the WTRU also attempts to register to the selected SMN (which has established a first 3GPP access with the primary MN) via a second 3GPP access. The registration request may include an indication that the registration is for a MA-PDU session with DualSteer functionality. The AMF of the SMN may use this information to determine whether to accept or reject the registration to the SMN. The network may wish to limit the number of WTRUs that use its network as the secondary 3GPP branch for DualSteer. For example, the network may be overloaded or may have limited resources, and the network may prefer to reserve its resources for its own WTRUs (WTRUs that use the network as the primary MN). In such a case, the network (AMF) may respond with a registration rejection and provide a suitable reason (e.g., "SMN rejection - overloaded" or "SMN rejection - limited resources" or "SMTN rejection – reserved"). The network (AMF) may additionally include the duration for which the MN should not be used as the secondary MN.

[0316] In both cases (where the SMN is different from the primary MN and where the SMN is the same as the primary MN), if the registration is successful, the WTRU will receive a registration acceptance message. The registration acceptance message may include an indication to the WTRU to start a cell reselection process for a second 3GPP access. Alternatively, the registration acceptance message may indicate to the WTRU to delay the cell reselection process. In one option according to an embodiment, the registration acceptance message may include the value of the delay (e.g., duration), and the WTRU will delay the cell reselection process by that amount. In a second option according to an embodiment, the WTRU will rely on service area restriction information and / or time restriction information included in the SMN information to determine when to start the cell reselection process. For example, the WTRU may delay the cell reselection process until the WTRU location is within a restricted service area. As another example, the WTRU may perform the cell reselection process only based on a time restriction (only when the service of the SMN is available).

[0317] In both cases (where the SMN is different from the primary MN and where the SMN is the same as the primary MN), if the registration is unsuccessful, the WTRU will receive a registration rejection message. Based on the rejection reason, the WTRU may add the SMN to the list of "MNs not allowed to operate as secondary MNs". The WTRU may then return to SMN selection and select the next highest priority SMN / access technology combination. In this case, the registration rejection message may include an appropriate rejection reason value, as well as an indication of how long the MN should be on the list of "MNs not allowed to operate as secondary MNs". Alternatively, for each rejection reason value, the WTRU may be pre-configured with a duration of how long the MN should be on the list of "MNs not allowed to operate as secondary MNs". For example, rejection reason "1" implies duration "T1", rejection reason "2" implies duration "T2", etc.

[0318] Regarding WTRU operation on a selected secondary MN (SMN), when the WTRU registers on the SMN, the WTRU performs a set of operations / actions specific to the SMN.

[0319] A first such operation is to deregister from the SMN. When the WTRU registers to the SMN, it follows rules to determine when to deregister from the SMN (and possibly select and register to another SMN), and when to switch from one SMN / access technology combination to another SMN / access technology combination.

[0320] The WTRU may deregister from the SMN based on one or more of the following conditions:

[0321] · The WTRU loses connection to the SMN;

[0322] · The WTRU location is outside the service area restriction provided in the SMN information;

[0323] · The time limit causes the WTRU not to use the SMN to obtain the DualSteer function;

[0324] · The WTRU determines that another SMN / access technology combination is more suitable for the DualSteer function. This can be based on the cell signal strength, similar to the situation described elsewhere in this document for the initial SMN selection;

[0325] · The WTRU receives a message from the SMN that the SMN no longer "wants" to support and / or no longer supports the DualSteer function of the WTRU;

[0326] · The WTRU no longer needs the DualSteer function. In this case, the WTRU can modify the PDU session so that all QoS flows pass through the SA-PDU session;

[0327] · The WTRU can periodically evaluate whether a higher-priority SMN / access technology combination is available. If so, the WTRU can use the result of this evaluation as a trigger to deregister from the current SMN and possibly register to the SMN of the higher-priority SMN / access technology combination; and

[0328] · The WTRU no longer has traffic that requires the DualSteer function. If the DualSteer function is triggered for a specific SDF, the WTRU can decide to deregister from the SMN if the SDF has ended. If the DualSteer function is triggered for a group of SDFs, the WTRU can decide to deregister from the SMN if the group of SDFs has ended. If the DualSteer function is triggered for a type of SDF, the WTRU can decide to deregister from the SMN if there are no more SDFs of this type. If the DualSteer function is triggered for a specific 5QI, the WTRU can decide to deregister from the SMN if there is no longer any traffic associated with that specific 5QI.

[0329] Subsequently, if necessary, the WTRU can start the SMN selection again to select a new SMN / access technology combination. This allows the WTRU to deregister from one SMN (SMN1) and select and register to a new SMN (SMN2).

[0330] A second such operation according to an embodiment involves transferring a second 3GPP access branch from a source SMN / access technology combination to a target SMN / access technology combination. In particular, when the WTRU enables the DualSteer function on the primary MN and the SMN, it may determine that another SMN / access technology combination is more suitable for the DualSteer function. This can be based on cell signal strength, similar to the situation described elsewhere in this document for initial SMN selection. In this case, the WTRU may "want" to move the second 3GPP access branch to the target SMN / access technology combination. When a better SMN / access technology combination is found, the WTRU can register with the new SMN (referred to as the target SMN). As part of the registration message to the new SMN, the WTRU can provide the source SMN / access technology combination and the primary MN. The target SMN will evaluate whether it is willing to accept the registration from the WTRU. If the target SMN accepts the WTRU's registration request and the registration of the WTRU to the target SMN is successful, the AMF of the target SMN responds to the WTRU with a registration acceptance message. After receiving the registration acceptance message, the WTRU deregisters from the source SMN and selects a suitable cell on the target SMN. The WTRU can then send a PDU session modification request to the primary MN to request the primary MN to re-establish the MA-PDU session with the target SMN. Then, the SMF of the target SMN sets the QoS flow of the MA-PDU session. Alternatively, the WTRU can then send a PDU session establishment request to the target SMN to request the re-establishment of the MA-PDU session. Then, the SMF of the target SMN sets the QoS flow of the MA-PDU session.

[0331] A third such operation according to an embodiment involves a more seamless mechanism for transferring a second 3GPP access branch from a source SMN / access technology combination to a target SMN / access technology combination. In particular, when the WTRU enables the DualSteer function on the primary MN and the SMN, the WTRU may determine that another SMN / access technology combination is more suitable for the DualSteer function. This may be based on cell signal strength, similar to the case described elsewhere in this document for initial SMN selection. In such a case, the WTRU may "want" to move the second 3GPP access branch to the target SMN / access technology combination. Since the primary use of the SMN is mainly to improve the user plane performance of a particular SDF rather than to provide the WTRU with a connection to the data network, this third operation allows the WTRU to switch SMNs more seamlessly. The WTRU may periodically monitor the SMN / access technology combination and determine that an SMN switch is needed. This may be based on cell signal strength, similar to the case described elsewhere in this document for initial SMN selection. When a better SMN / access technology combination is found, the WTRU may register with the new SMN (referred to as the target SMN). As part of the registration message, the WTRU may provide the source SMN / access technology combination and the primary MN. The WTRU may also include a list of PDU session IDs to be transferred to the target SMN. The target SMN will evaluate whether it "wishes" to accept the registration from the WTRU. If so, the target SMN may retrieve the SMF context from the source SMN and set the SMF context in the target SMN. If the registration is successful, the target SMN responds to the WTRU with a registration acceptance message. After receiving this message, the WTRU registers with the source SMN and selects a suitable cell in the target SMN. Then, the SMF of the target SMN sets the QoS flows of the MA-PDU session.

[0332] When registering to the SMN, there can be advantages in reducing some control plane procedures on the SMN. For example, the number of registration updates on the SMN can be reduced. Registration updates can be used for 1) making the PLMN aware that the WTRU is still reachable, 2) providing an indication of the registration area where the WTRU is located, and 3) updating the WTRU capabilities. For UL transmissions via a secondary 3GPP access, the first two uses (1) and (2) may not be required. The WTRU can instead "decide" to perform a registration update or a service request procedure before the uplink transmission. For DL transmissions, the network can rely on the primary MN to signal the WTRU to perform a registration update or a service request procedure. This signal can be added by the UPF in the header of the user plane traffic and sent via the primary MN. Similarly, paging requests sent via the SMN can be avoided. Instead, the network can rely on the primary MN to signal the WTRU to perform a service request procedure. This signal can be added by the UPF in the header of the user plane traffic and sent via the primary MN. More generally, the WTRU and the UPF can use the primary MN to transmit control plane messages related to the secondary MN. The exchange on the primary MN is carried out between the WTRU and the UPF via the header in the user plane traffic.

[0333] Figure 7 is a flowchart 700 of a method for selecting a secondary mobile network (SMN), registering to the SMN, and then performing operations related to the SMN with a WTRU (such as Figure 1B WTRU 102).

[0334] At step 702, a WTRU (such as Figure 1B WTRU 102) receives information of at least one SMN.

[0335] At step 704, the WTRU initiates a MA-PDU session with DualSteer functionality. The WTRU can initiate the MA-PDU session with the primary MN selected and registered by the WTRU. For example, the WTRU and / or the primary mobile network can establish a 3GPP access branch for communication between the WTRU and the primary mobile network (e.g., one or more SDFs).

[0336] At step 706, the WTRU selects an SMN from at least one SMN.

[0337] At step 708, the WTRU registers to the selected SMN.

[0338] At step 710, the WTRU performs at least one operation related to the SMN registered with the WTRU. For example, the WTRU and / or the secondary mobile network may establish another 3GPP access branch for communication between the WTRU and the secondary mobile network (e.g., one or more service data flows (SDFs)), where the 3GPP access branch is part of an MA-PDU session with DualSteer functionality and allows data to flow via that MA-PDU session (e.g., one or more SDFs).

[0339] Figure 8 is a flowchart 800 of a method for requesting to establish an MA-PDU session with DualSteer functionality, the method including selecting and registering with an SMN.

[0340] At 802, the WTRU receives from the PMN registered with the WTRU information related to the SMN and including an indication of SMN selection rules (e.g., rules for selecting an MN / access technology combination).

[0341] At 804, the WTRU selects an SMN in response to a trigger and the SMN selection rules. Examples of triggers include selecting an SMN that can accommodate specific QoS requirements and / or expected data rates for a particular SDF.

[0342] At 806, the WTRU registers with the selected SMN.

[0343] And, at 808, the WTRU requests to establish an MA-PDU session with DualSteer functionality and having one access branch on the registered SMN and another access branch on the registered PMN. For example, each of one or both access branches may be a respective 3GPP access branch.

[0344] Figure 9 is a flowchart 900 of a method for requesting to establish an MA-PDU session with DualSteer functionality, the method including selecting and registering with a PMN.

[0345] At 902, the WTRU receives from the PMN information related to the SMN. For example, such information may indicate the ID of the SMN, the priority of the SMN, the type of the SMN, the access types supported by the SMN, the service area provided by the SMN, the availability of the services provided by the SMN, the DNs served by the SMN, the QoS performance of the SMN, and / or the types of traffic to be sent and / or received via the SMN.

[0346] At 904, the WTRU selects a PMN in response to the information related to the SMN.

[0347] At 906, the WTRU registers to the selected PMN.

[0348] Also, at 908, in response to a trigger (e.g., an expected data rate), and based on QoS-related factors and information related to the SMN, a request is made to establish a MA-PDU session with DualSteer functionality and having one access branch on the registered PMN and another access branch.

[0349] Although the features and elements have been described above in particular combinations, one of ordinary skill in the art will understand that each feature or element can be used alone or in any combination with other features and elements. Additionally, the methods described herein can be implemented in a computer program, software, or firmware incorporated into a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted via wired or wireless connections) and computer-readable storage media. Examples of non-transitory 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 internal 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 the software can 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 (WTRU), the method comprises: receiving, from a primary mobile network (PMN) registered by the WTRU, information related to a secondary mobile network (SMN) and including an indication of an SMN selection rule; selecting an SMN in response to a trigger and the SMN selection rule; registering to the selected SMN; and requesting to establish a multi - access protocol data unit (MA - PDU) session having a DualSteer function, having one access branch on the registered SMN and having another access branch on the registered PMN.

2. The method according to claim 1, wherein, the information indicates an identifier (ID) of the SMN, a priority of the SMN, and / or an access technology related to the SMN.

3. The method according to any one of claims 1 to 2, wherein, the SMN selection rule indicates a rule for selecting a combination of a mobile network (MN) and an access technology.

4. The method according to any one of claims 1 to 3, wherein, the trigger includes a quality of service (QoS) requirement of a service data flow (SDF).

5. The method according to any one of claims 1 to 4, wherein, the trigger includes an expected data rate of the SDF.

6. The method according to any one of claims 1 to 5, wherein, the access branch includes at least one 3GPP access branch.

7. The method according to any one of claims 1 to 6, the method further comprises registering to the PMN.

8. The method according to any one of claims 1 to 7, the method further comprises: transmitting and / or receiving protocol data units (PDUs) using an established MA - PDU session having a DualSteer function, wherein the PDUs are transmitted and received using the access branch on the registered SMN and using the other access branch on the registered PMN.

9. The method according to any one of claims 1 to 8, the method further comprises deregistering from the selected SMN in response to another trigger.

10. The method according to claim 9, wherein, the another trigger includes identifying another SMN that provides a higher QoS than the selected SMN.

11. The method according to any one of claims 9 to 10, wherein, the another trigger includes losing connection with the registered SMN, being outside the service area of the registered SMN, and / or determining that the DualSteer function is not required.

12. A wireless transmit - receive unit (WTRU) configured to: receive, from a primary mobile network (PMN) registered by the WTRU, information related to a secondary mobile network (SMN) and including an indication of an SMN selection rule; select an SMN in response to a trigger and the SMN selection rule; register to the selected SMN; and Request to establish a multi-access protocol data unit (MA-PDU) session with DualSteer functionality, having one access branch on a registered SMN and another access branch on a registered PMN.

13. The WTRU according to claim 12, wherein, the information indicates an identifier (ID) of the SMN, a priority of the SMN, and / or an access technology associated with the SMN.

14. The WTRU according to any one of claims 12 to 13, wherein, the SMN selection rule indicates a rule for selecting a combination of a mobile network (MN) and an access technology.

15. The WTRU according to any one of claims 12 to 14, wherein, the trigger includes a quality of service (QoS) requirement for a service data flow (SDF).

16. The WTRU according to any one of claims 12 to 15, wherein, the trigger includes an expected data rate of the SDF.

17. The WTRU according to any one of claims 12 to 16, wherein, the access branch includes at least one 3GPP access branch.

18. The WTRU according to any one of claims 12 to 17, the WTRU is further configured to register the WTRU to the PMN.

19. The WTRU according to any one of claims 12 to 18, the WTRU is further configured to transmit and / or receive protocol data units (PDUs) using an established MA-PDU session with DualSteer functionality, wherein the PDUs are transmitted and received using the access branch on the registered SMN and the other access branch on the registered PMN.

20. The WTRU according to any one of claims 12 to 19, the WTRU is further configured to deregister from the selected SMN in response to another trigger.

21. The WTRU according to claim 20, wherein, the another trigger includes identifying another SMN that provides higher QoS than the selected SMN.

22. The WTRU according to any one of claims 20 to 21, wherein, the another trigger includes losing connection with the registered SMN, being outside the service area of the registered SMN, and / or determining that the DualSteer functionality is not required.

23. A method for implementation by a wireless transmit-receive unit (WTRU), the method comprises: receiving information related to a secondary mobile network (SMN) from a primary mobile network (PMN); selecting the PMN in response to the information related to the SMN; registering to the selected PMN; and requesting to establish a multi-access protocol data unit (MA-PDU) session with DualSteer functionality, having one access branch on the registered PMN and another access branch, in response to a trigger and based on factors related to quality of service (QoS) and the information related to the SMN.

24. The method according to claim 23, wherein, The information indicates an identifier (ID) of the SMN, a priority of the SMN, a type of the SMN, an access type supported by the SMN, a service area provided by the SMN, an availability of a service provided by the SMN, a data network (DN) served by the SMN, a QoS performance of the SMN, and / or a type of traffic to be sent and / or received via the SMN.

25. The method according to any one of claims 23 to 24, wherein, the triggering includes an expected data rate.

26. The method according to any one of claims 23 to 25, wherein, at least one of the access branches includes a 3GPP access branch.

27. The method according to any one of claims 23 to 26, wherein, each of the access branches includes a corresponding 3GPP access branch.

28. The method according to any one of claims 23 to 27, the method further comprising deregistering from the selected PMN and selecting another PMN in response to another trigger.

29. The method according to any one of claims 23 to 28, the method further comprising receiving an indication from the PMN that the PMN supports the DualSteer function.

30. The method according to any one of claims 23 to 29, the method further comprises: initiating a service data flow (SDF) using the DualSteer function; and selecting the PMN in response to initiating the SDF.

31. The method according to any one of claims 23 to 30, wherein, requesting to establish the MA-PDU session includes: transmitting an MA-PDU session request identifying an access type supported by the second 3GPP access branch.

32. The method according to any one of claims 23 to 31, the method further comprises: selecting and registering to an SMN; and transmitting and / or receiving a PDU using an established MA-PDU session having the DualSteer function and having one access branch on the registered PMN and another access branch on the registered SMN.

33. A wireless transmit-receive unit (WTRU) configured to: receive information related to a secondary mobile network (SMN) from a primary mobile network (PMN); select the PMN in response to the information related to the SMN; register to the selected PMN; and request to establish a multi-access protocol data unit (MA-PDU) session having the DualSteer function and having one access branch on the registered PMN and another access branch in response to a trigger and based on quality of service (QoS)-related factors and the information related to the SMN.

34. The WTRU according to claim 33, wherein, The information indicates an identifier (ID) of the SMN, a priority of the SMN, a type of the SMN, an access type supported by the SMN, a service area provided by the SMN, an availability of a service provided by the SMN, a data network (DN) served by the SMN, a QoS performance of the SMN, and / or a type of traffic to be sent and / or received via the SMN.

35. The WTRU according to any one of claims 33 to 34, wherein, the trigger includes an expected data rate.

36. The WTRU according to any one of claims 33 to 35, wherein, at least one of the access branches includes a 3GPP access branch.

37. The WTRU according to any one of claims 33 to 36, wherein, each of the access branches includes a respective 3GPP access branch.

38. The WTRU according to any one of claims 33 to 37, the WTRU is further configured to: deregister from the selected PMN; and select another PMN in response to another trigger.

39. The WTRU according to any one of claims 33 to 38, the WTRU is further configured to receive an indication from the PMN that the PMN supports the DualSteer function.

40. The WTRU according to any one of claims 33 to 39, the WTRU is further configured to: initiate a service data flow (SDF) using the DualSteer function; and select the PMN in response to initiating the SDF.

41. The WTRU according to any one of claims 33 to 40, wherein, the WTRU is configured to request establishment of the MA-PDU session by transmitting a MA-PDU session request identifying an access type supported by a second 3GPP access branch.

42. The WTRU according to any one of claims 33 to 41, the WTRU is further configured to: select and register to an SMN; and transmit and / or receive PDUs using an established MA-PDU session having the DualSteer function and having one access branch on the registered PMN and another access branch on the registered SMN.

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