Apparatus and methods for paging enhancements associated with NTN-TN interworking

Abstract

Methods and apparatus for paging and responding in different networks, i.e., non-terrestrial networks (NTNs) to terrestrial networks (TNs), are described herein. A wireless transmit / receive unit, e.g., a wireless transmit / receive unit, WTRU, camping in an idle or inactive state monitors paging on an NTN network. And the WTRU receives the paging message on the NTN. The paging message provides an indication to respond on the TN network. The WTRU performs a cell reselection to the TN. The WTRU responds to the paging on the NTN network by transmitting a paging response message on the TN network.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 395,746, filed on August 5, 2022, the contents of which are hereby incorporated by reference into this document. Background Art

[0003] Mobile communications using wireless communications continue to evolve. The fifth generation may be referred to as 5G. Previous (legacy) mobile communications may be, for example, fourth generation (4G) Long Term Evolution (LTE). Summary of the invention

[0004] Systems, methods, and tools for paging and responding in different networks, such as a non-terrestrial network (NTN) to a terrestrial network (TN), a TN to an NTN, an NTN to another NTN, and the like, are described herein. For example, a wireless transmit / receive unit (WTRU) (e.g., camped in an idle or inactive state) may monitor for paging on a first network (e.g., NTN). The WTRU may receive a paging message on the NTN. The paging message may provide an indication to respond on a second network (e.g., TN). The WTRU may perform a cell reselection to the TN. The WTRU may respond to a paging on a first network (e.g., NTN) by transmitting a paging response message on a second network (e.g., TN).

[0005] Example A WTRU may receive a paging message from an NTN node. The paging message may indicate that the WTRU responds to the paging message, a first target TN cell, a second target TN cell, a first priority information associated with the first target TN cell, a second priority information associated with the second target TN cell, a first timing information associated with the first target TN cell, and a second timing information associated with the second target TN cell on the TN. The WTRU may select a TN cell from the first target TN cell and the second target TN cell based at least on the first priority information and the second priority information. The WTRU may apply the timing information associated with the selected TN cell. The WTRU may transmit an access request to the TN node associated with the selected TN cell to initiate a connection on the selected TN cell. The access request may indicate that the access request is triggered by the NTN node.

[0006] The selection of the TN cell from the first target TN cell and the second target TN cell may be further based on satisfaction of a condition. The condition may be satisfied if the paging message is scrambled with a radio network temporary identifier (RNTI) associated with the cell redirection. The paging message may include a service type indicator. The selection of the TN cell from the first target TN cell and the second target TN cell may be further based on the service type indicator.

[0007] The paging message may further indicate first uplink resources associated with the first target TN cell and second uplink resources associated with the second target TN cell.Transmitting the access request to the selected TN cell may involve transmitting the access request using uplink resources associated with the selected TN cell.

[0008] The first target TN cell may be associated with a first reference signal quality. The second target TN cell may be associated with a second reference signal quality. Selecting the TN cell from the first target TN cell and the second target TN cell may be further based on the first reference signal quality and the second reference signal quality.

[0009] The first target TN cell may be associated with a first frequency. The second target TN cell may be associated with a second frequency. Selecting the TN cell from the first target TN cell and the second target TN cell may be further based on a first difference between the first frequency and the target frequency and a second difference between the second frequency and the target frequency.

[0010] The WTRU may transmit a measurement report to the NTN node. The measurement report may indicate a request for first priority information associated with the first target TN cell and second priority information associated with the second target TN cell. The first priority information and the second priority information may be based on the measurement report.

[0011] Example A WTRU may identify one or more target TN cells. The WTRU may receive a paging message from an NTN node indicating: a TN cell in the one or more target TN cells, the WTRU responding to the paging message on the TN cell, and timing information associated with the TN cell. The WTRU may apply the timing information associated with the TN cell. The WTRU may transmit an access request to a TN node associated with the TN cell to initiate a connection on the TN cell. The access request may indicate that the access request is triggered by the NTN node.

[0012] After transmitting the access request, the WTRU may start a timer. In the event of a connection failure or no access response is received before the timer expires, the WTRU may transmit a response to the NTN node or monitor for subsequent paging messages from the NTN node. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented;

[0014] Figure 1B is an example of an embodiment in which Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within an illustrated communication system;

[0015] Figure 1C is an example of an embodiment in which Figure 1A A system diagram of an example Radio Access Network (RAN) and an example Core Network (CN) used within the illustrated communication system;

[0016] Figure 1D is an example of an embodiment in which Figure 1A A system diagram of another example RAN and another example CN used within the illustrated communication system;

[0017] Figure 2 An example of multiple interfaces in a non-terrestrial network is illustrated.

[0018] Figure 3 An example of a WTRU triggered transition from an idle state (such as the RRC_IDLE state) to a connected state (such as the RRC_CONNECTED state) is illustrated.

[0019] Figure 4 An example is illustrated where the network rejects a WTRU triggered transition from an idle state, such as the RRC_IDLE state, where the WTRU may attempt to establish a connection from the idle state.

[0020] Figure 5 An example of a WTRU triggered transition from an inactive state (such as the RRC_INACTIVE state) to a connected state (such as the RRC_CONNECTED state) is illustrated.

[0021] Figure 6 An example of a WTRU triggered transition from an inactive state (such as the RRC_INACTIVE state) to a connected state (such as the RRC_CONNECTED state) is illustrated.

[0022] Figure 7 An example of a rejection from the network when the WTRU attempts to resume a connection from an inactive state, such as the RRC_INACTIVE state, is illustrated.

[0023] Figure 8 An example of a network-triggered transition from an inactive state (such as the RRC_INACTIVE state) to a connected state (such as the RRC_CONNECTED state) is illustrated.

[0024] Fig. 9 An example of a Radio Access Network (RAN) based Notification Area (RNA) update procedure with WTRU context relocation is illustrated.

[0025] Fig.10An example of a periodic RNA update procedure without WTRU context relocation is illustrated.

[0026] Fig.11 An example of an RNA update procedure with a transition to an idle state, such as the RRC_IDLE state, is illustrated.

[0027] Fig.12 An example of a resume request is illustrated which may include a response with a release with redirection and may include a WTRU context relocation.

[0028] Fig.13 An example of a process for core network (CN) controlled sub-packets is illustrated.

[0029] Fig.14 An example of a process for sub-grouping based on WTRU ID is illustrated.

[0030] Fig.15 An example of the NTN-TN network layer is illustrated.

[0031] Fig.16 An example of paging a WTRU in the NTN using a paging response from a WTRU in the TN is illustrated.

[0032] Fig.17 An example procedure for paging a WTRU in an NTN cell with the response of a WTRU in a TN cell is illustrated. DETAILED DESCRIPTION

[0033] Figure 1A 1 is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content through sharing of system resources (including wireless bandwidth). For example, the communication system 100 may employ one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), zero tail unique word DFT spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, and filter bank multi-carrier (FBMC), etc.

[0034] like Figure 1AAs shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104 / 113, CN 106 / 115, public switched telephone network (PSTN) 108, Internet 110 and other networks 112, but it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d (any of which may be referred to as a “station” and / or “STA”) may be configured to send and / or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated process chain environment), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0035] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device that is configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106 / 115, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an eNode B, a Home Node B, a Home eNode B, a gNB, an NR Node B, a site controller, an access point (AP), a wireless router, and the like. Although the base stations 114a, 114b are each depicted as a single element, it should be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0036] Base station 114a may be part of RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as base station controllers (BSC), radio network controllers (RNC), relay nodes, etc. Base station 114a and / or base station 114b may be configured to send and / or receive wireless signals on one or more carrier frequencies (which may be referred to as cells (not shown)). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of a licensed spectrum and an unlicensed spectrum. A cell may provide coverage of wireless services to a specific geographic area, which may be relatively fixed or may change over time. The cell may be further divided into cell sectors. For example, the cell associated with base station 114a may be divided into three sectors. Therefore, in one embodiment, base station 114a may include three transceivers, i.e., one transceiver 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 send and / or receive signals in a desired spatial direction.

[0037] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0038] More specifically, as noted above, the communication system 100 may be a multiple access system and may employ one or more channel access schemes such as CDMA, TDMA, FDMA, OFDMA, and SC-FDMA. For example, the base station 114a in the RAN 104 / 113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may use Wideband CDMA (WCDMA) to establish the air interface 115 / 116 / 117. 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 ​​UL Packet Access (HSUPA).

[0039] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA) that may establish the air interface 116 using Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-APro).

[0040] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR radio access, which may establish the air interface 116 using New Radio (NR).

[0041] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may together implement LTE radio access and NR radio access, for example using the dual connectivity (DC) principle. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions transmitted to / from multiple types of base stations (e.g., eNBs and gNBs).

[0042] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), and GSM EDGE (GERAN).

[0043] Figure 1AThe base station 114b in may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in local areas such as commercial venues, homes, vehicles, campuses, industrial facilities, sky corridors (e.g., for use by drones), and roads. 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 picocell or a femtocell. As Figure 1A As shown, base station 114b may have a direct connection to Internet 110. Therefore, base station 114b may not need to access Internet 110 via CN 106 / 115.

[0044] The RAN 104 / 113 may be in communication with the CN 106 / 115, which may be any type of network configured to provide voice, data, applications and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not described in detail in the text and video, the CN 106 / 115 may be configured to provide voice, data, applications and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Figure 1A Although not shown in the figure, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may utilize NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0045] The CN 106 / 115 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and / or the Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired communication networks and / or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 / 113 or a different RAT.

[0046] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). Figure 1A The illustrated WTRU 102c may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0047] Figure 1B is a system diagram illustrating an example WTRU 102. Figure 1B As shown, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0048] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC) and state machine, etc. The processor 118 may perform signal decoding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, but it is understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0049] The send / receive element 122 may be configured to send a signal to a base station (e.g., base station 114a) or receive a signal from a base station via an air interface 116. For example, in one embodiment, the send / receive element 122 may be an antenna configured to send and / or receive an RF signal. In an embodiment, the send / receive element 122 may be a transmitter / detector configured to send and / or receive, for example, an IR, UV, or visible light signal. In another embodiment, the send / receive element 122 may be configured to send and / or receive both an RF signal and an optical signal. It should be understood that the send / receive element 122 may be configured to send and / or receive any combination of wireless signals.

[0050] Although the transmit / receive element 122 Figure 1B Although depicted as a single element in the figure, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0051] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. For example, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0052] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from and store data in any type of suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, and a secure digital (SD) memory card, among others. In other embodiments, the processor 118 may access information from and store data in a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0053] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel cadmium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0054] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or in lieu of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method while remaining consistent with an embodiment.

[0055] The processor 118 may also be coupled to other peripherals 138, which may include one or more software modules and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, module, FM radio unit, digital music player, media player, video game player module, Internet browser, virtual reality and / or augmented reality (VR / AR) device and activity tracker, etc. Peripheral device 138 may include one or more sensors, which may be one or more of the following: gyroscope, accelerometer, Hall effect sensor, magnetometer, orientation sensor, proximity sensor, temperature sensor, time sensor; geolocation sensor; altimeter, light sensor, touch sensor, magnetometer, barometer, gesture sensor, biometric sensor and / or humidity sensor.

[0056] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for both UL (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit for reducing and / or substantially eliminating self-interference via hardware (e.g., a choke) or via signal processing performed by a processor (e.g., a separate processor (not shown) or via the processor 118). In one embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for both UL (e.g., for transmission) or downlink (e.g., for reception)) may be concurrent and / or simultaneous.

[0057] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0058] The RAN 104 may include evolved Node-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of evolved Node-Bs while remaining consistent with an embodiment. The evolved Node-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the evolved Node-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the evolved Node-B 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0059] Each of the evolved Node Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, and scheduling of users in the UL and / or DL, among other things. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0060] Figure 1C The illustrated CN 106 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements is depicted as being part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0061] The MME 162 may be connected to each of the evolved Node-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, and selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0062] The SGW 164 may be connected to each of the evolved Node-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during an inter-evolved Node-B handover, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, and managing and storing the context of the WTRUs 102a, 102b, 102c.

[0063] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0064] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may be in communication with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers.

[0065] Although the WTRU Figures 1A to 1D Although described as wireless terminals, it is contemplated that in certain representative embodiments, such terminals may (eg, temporarily or permanently) use a wired communications interface with a communications network.

[0066] In a representative embodiment, the other network 112 may be a WLAN.

[0067] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for a BSS and one or more stations (STAs) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic to and / or out of the BSS. Traffic originating from outside the BSS and destined for the STA may be reached by the AP and may be delivered to the STA. Traffic originating from the STA and destined for a target outside the BSS may be transmitted to the AP to be delivered to the corresponding target. Traffic between STAs within the BSS may be transmitted by the AP, for example, wherein the source STA may transmit traffic to the AP, and the AP may deliver traffic to the target STA. Traffic between STAs within the BSS may be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic may be transmitted between the source STA and the target STA (e.g., directly between them) using direct link establishment (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (eg, all STAs in the STA) may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad hoc" communication mode.

[0068] When using the 802.11ac infrastructure operation mode or a similar operation mode, the AP may send beacons on a fixed channel (such as a primary channel). The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a width dynamically set via signaling. The primary channel may be an operating channel of the BSS and may be used by the STA to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access / collision avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. For CSMA / CA, a STA (e.g., each STA) (including the AP) may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0069] High throughput (HT) STAs may communicate using a 40 MHz wide channel (eg, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels) to form a 40 MHz wide channel.

[0070] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz channels and / or 80MHz channels can be formed by combining continuous 20MHz channels. 160MHz channels can be formed by combining 8 continuous 20MHz channels, or by combining two non-continuous 80MHz channels (this can be called 80+80 configuration). For 80+80 configuration, after channel coding, the data can pass through a segment parser that can divide the data into two streams. Each stream can be processed by inverse fast Fourier transform (IFFT) and time domain processing separately. These streams can be mapped to two 80MHz channels, and the data can be sent by sending STA. At the receiver of the receiving STA, the above-mentioned operation for 80+80 configuration can be reversed, and the combined data can be transmitted to the medium access control (MAC).

[0071] 802.11af and 802.11ah support operating modes below 1GHz. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support instrument type control / machine type communications, such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain long battery life).

[0072] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA (which supports the minimum bandwidth operating mode) from all STAs operating in the BSS. In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only support) a 1MHz mode, the primary channel may be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy, for example, because a STA (supporting only a 1MHz operating mode) is sending to the AP, the entire available band may be considered busy even if most of the band remains idle and may be available.

[0073] In the United States, the available frequency band for 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

[0074] Figure 1D 1 is a system diagram illustrating the RAN 113 and the CN 115 in accordance with an embodiment. As noted above, the RAN 113 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0075] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 180b may utilize beamforming to send signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may, for example, use multiple antennas to send wireless signals to and / or receive wireless signals from the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, gNB 180a may transmit multiple component carriers to WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum, while the remaining component carriers may be on licensed spectrum. In an embodiment, gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0076] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with parameter sets that may be scalable. For example, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmit time intervals (TTIs) of varying or scalable lengths (e.g., containing different numbers of OFDM symbols and / or varying absolute time lengths over time).

[0077] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c while not accessing other RANs (e.g., such as the eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with the gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as the eNodeB 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNodeBs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNodeB 160a, 160b, 160c may act as a mobility anchor for the WTRUs 102a, 102b, 102c, and the gNB 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0078] Each of the gNBs 180a, 180b, 180c may be associated with a specific cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b and routing of control plane information towards an access and mobility management function (AMF) 182a, 182b, etc. Figure 1D As shown, gNBs 180a, 180b, and 180c may communicate with each other via an Xn interface.

[0079] Figure 1DThe illustrated CN 115 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possible data networks (DNs) 185a, 185b. Although each of the foregoing elements is depicted as part of the CN 115, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0080] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, support of network slicing (e.g., handling of different PDU sessions with different requirements), selecting a specific SMF 183a, 183b, management of registration areas, termination of NAS signaling, mobility management, etc. The AMF 182a, 182b may use network slicing in order to customize CN support for the WTRU 102a, 102b, 102c based on the type of services utilized by the WTRU 102a, 102b, 102c. For example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced mobile broadband (eMBB) access, and / or services for machine type communication (MTC) access, etc. The AMF 162 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies, such as WiFi.

[0081] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 115 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 115 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b, and configure the service routing performed by the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy implementation and QoS, providing downlink data notification, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0082] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, and providing mobility anchoring, etc.

[0083] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to local data networks (DNs) 185a, 185b via the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and the N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0084] Given that Figures 1A to 1D as well as Figures 1A to 1D Corresponding to the description of the present invention, one or more or all of the functions described herein with reference to one or more of the following may be performed by one or more simulation devices (not shown): WTRU102a-d, base station 114a-b, evolved Node B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF182a-b, UPF 184a-b, SMF 183a-b, DN 185a-b and / or any other device described herein. The simulation device may be one or more devices configured to emulate one or more or all of the functions described herein. For example, the simulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0085] The simulation device may be designed to implement one or more tests of other devices in a laboratory environment and / or in an operator network environment. For example, one or more simulation devices may perform one or more functions or all functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. One or more simulation devices may perform one or more functions or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The simulation device may be directly coupled to another device for testing purposes and / or may use over-the-air wireless communications to perform testing.

[0086] One or more simulation devices can perform one or more (including all) functions without being implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation device can be used in a test scenario in a test laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network to implement testing of one or more components. One or more simulation devices can be test equipment. Direct RF coupling and / or wireless communication via RF circuits (e.g., which can include one or more antennas) can be used by the simulation device to send and / or receive data.

[0087] Non-terrestrial networks (NTNs) may facilitate the deployment of wireless networks in areas where land-based antennas may not be available, for example, due to geography or cost. NTNs coupled with TNs can enable ubiquitous network coverage (e.g., through 5G networks). NTN deployments can support basic calls and text messages anywhere in the world. NTNs, TNs, and low-orbit satellites can enable enhanced services (e.g., web browsing for NTNs).

[0088] The NTN may include an airborne or space platform that may transmit signals from a land-based gNB to a WTRU and vice versa (e.g., via a gateway (GW)). The NTN may support one or more WTRUs (e.g., power class 3 WTRUs). The WTRU may have an omnidirectional antenna and / or linear polarization. The WTRU may have a (e.g., very) small aperture antenna terminal (VSAT) with a directional antenna and / or circular polarization. The NTN may support support for LTE-based narrowband IoT (NB-IoT) and enhanced machine type communication (eMTC) type devices. The NTN WTRU may have GNSS capabilities.

[0089] Aerial platforms or space platforms may be classified according to orbit (e.g., low earth orbit (LEO) satellites with an altitude range of 300km-1500km, geosynchronous orbit (GEO) satellites with an altitude of 35,786km), medium earth orbit (MEO) satellites with an altitude range of 7000km-25000km, and high altitude platform stations (HAPS) with an altitude of 8km-50km). Satellite platforms may be (e.g., further) classified as having transparent payloads or regenerative payloads. Transparent satellite payloads may implement frequency conversion and / or RF amplification in the uplink and / or downlink. Multiple transparent satellites may be connected to land-based gNBs. Regenerative satellite payloads may implement a gNB (e.g., a full gNB) or a gNB distributed unit (DU) on a satellite. The regenerative payload may perform digital processing (e.g., including demodulation, decoding, re-encoding, re-modulation, and / or filtering) on ​​the signal.

[0090] One or more of the following radio interfaces may be defined (e.g., configured) in the NTN: a feeder link (e.g., a wireless link between a GW and a satellite); a service link (e.g., a radio link between a satellite and a WTRU); and / or an inter-satellite link (ISL) (e.g., a transmission link between satellites). The ISL may be supported by (e.g., only by) a regenerative payload. The ISL may be, for example, a radio (e.g., a 3GPP radio) or an optical interface.

[0091] Figure 2 Examples of multiple interfaces in an NTN are illustrated. An interface (e.g., a different 3GPP interface) may be used for (e.g., each) radio link (e.g., based on a satellite payload configuration). The NR-Uu radio interface may be used for a service link and / or a feeder link (e.g., for a transparent payload). The NR-Uu interface may be used on a service link (e.g., for a regenerative payload). A satellite radio interface (SRI) may be used for a feeder link (e.g., for a regenerative payload). A UP / CP protocol stack may be provided for a payload configuration (e.g., for each payload configuration).

[0092] NTN satellites can support multiple cells. A cell (e.g., each cell) may include one or more satellite beams. A satellite beam may cover a coverage area on the earth (e.g., like a terrestrial cell). A satellite beam may have a diameter range of 100km-1000km in a LEO deployment, and a diameter range of 200km-3500km in a GEO deployment. The beam coverage area in a GEO deployment may remain fixed relative to the earth. The area covered by a beam / cell in a LEO deployment may change over time (e.g., due to satellite movement). Beam movement may be classified as earth movement (e.g., if a LEO beam moves continuously on the earth), or may be classified as earth fixed (e.g., if the beam is manipulated to maintain coverage of a fixed position until a new cell exceeds the coverage area).

[0093] The round trip time (RTT) and / or maximum differential delay of the NTN platform may be larger than that of the terrestrial system (e.g., due to the altitude of the NTN platform and / or due to the beam diameter). In an example of a transparent NTN deployment, the RTT may range from 25.77 milliseconds (e.g., for LEO at 600 km altitude) to 541.46 milliseconds (e.g., for GEO), where the maximum differential delay may range from 3.12 milliseconds to 10.3 milliseconds. The RTT of the regenerated payload may be approximately half of that of the transparent payload. A transparent configuration may include both service and feeder links. The RTT of the regenerated payload may include (e.g., only include) the service link. The WTRU may perform timing precompensation (e.g., before initial access). For example, the WTRU may perform timing precompensation to reduce / minimize the impact on the existing network system (e.g., to avoid preamble ambiguity or to properly time the receive window).

[0094] Pre-compensation may involve the WTRU obtaining its position (e.g., via GNSS) and / or obtaining feeder link (e.g., or common) delay and satellite position (e.g., via satellite ephemeris data). Satellite ephemeris data may be broadcast (e.g., periodically) in system information (SI). Satellite ephemeris data may include satellite velocity, direction, and / or speed. The WTRU may estimate the distance to the satellite (e.g., and therefore estimate the delay). The WTRU may add a feeder link delay component to obtain the full WTRU-gNB RTT (e.g., UE-gNB RTT). The WTRU-gNB RTT may be used to offset timers, receive windows, and / or timing relationships. In some examples, frequency compensation may be performed by the network.

[0095] WTRU mobility and measurement reporting may be provided. The difference in RSRP between the cell center and the cell edge may not be as pronounced in NTNs as in terrestrial systems. Measurement-based mobility may be less reliable in NTN environments (e.g., based on larger areas of cell overlap). The network may utilize conditional handover and / or measurement report triggers that may depend on location and time. For example, enhanced mobility may be achieved in LEO deployments where a stationary WTRU (e.g., due to satellite movement) may perform mobility (e.g., approximately once every seven seconds) based on deployment characteristics.

[0096] Mobility, state transitions, and / or paging may be implemented for a WTRU in an idle state (e.g., RRC_IDLE), an inactive state (e.g., RRC_INACTIVE), and / or a connected state (e.g., RRC_CONNECTED). As used herein, the term idle state may be used interchangeably with the RRC_IDLE state, the term inactive state may be used interchangeably with the RRC_INACTIVE state, and the term connected state may be used interchangeably with the RRC_CONNECTED state.

[0097] Mobility can be implemented in an idle state (eg, RRC_IDLE). Cell selection can be implemented in an idle state (eg, RRC_IDLE).

[0098] Public land mobile network (PLMN) selection in a network (e.g., NR) may be based on (e.g., 3GPP) PLMN selection principles. For example, cell selection may occur on a transition from RM-DEREGISTERED to RM-REGISTERED, from CM-IDLE to CM-CONNECTED, and / or from CM-CONNECTED to CM-IDLE. Cell selection may be based on one or more of the following principles.

[0099] The WTRU non-access stratum (NAS) layer may identify the selected PLMN and / or equivalent PLMNs.

[0100] The cell selection may be based on a cell definition (CD) synchronization signal block (CD-SSB) located on a synchronization raster. The WTRU may search a network (e.g., NR) frequency band. Based on the CD-SSB, the WTRU may identify a strong cell (e.g., the strongest cell) for a carrier frequency (e.g., for each carrier frequency). The WTRU may read a cell system information broadcast to identify the PLMN. The WTRU may search a carrier (e.g., each carrier), for example, during initial cell selection, or may utilize stored information to shorten the search (e.g., stored information cell selection).

[0101] The WTRU may seek to identify a suitable cell. If the WTRU cannot identify a suitable cell, the WTRU may seek to identify an acceptable cell. The WTRU may find a suitable cell or an acceptable cell. The WTRU may camp on a suitable cell or an acceptable cell and start a cell reselection process. A suitable cell may be a cell whose measured cell attributes meet the cell selection criteria. The cell PLMN may be a selected PLMN (e.g., a registered PLMN or an equivalent PLMN). The cell may not be barred or reserved. The cell may not be part of a tracking area in a list of prohibited tracking areas for roaming. An acceptable cell may be a cell that is not barred and has measured cell attributes that meet the cell selection criteria.

[0102] The IAB-MT may apply cell selection as described for the WTRU. The IAB-MT may ignore cell barring or cell reservation indications included in the cell system information broadcast. If the cell system information broadcast indicates that the IAB supports the selected PLMN or the selected SNPN, the IAB-MT may consider (e.g., only consider) the cell as a candidate for cell selection.

[0103] The WTRU may transition to an idle state (e.g., RRC_IDLE). Upon transitioning to an idle state (e.g., RRC_IDLE) from a connected or inactive state (e.g., RRC_CONNECTED or RRC_INACTIVE), the WTRU may camp on a cell as a result of cell selection (e.g., based on the frequency assigned by the RRC in the state transition message, if any).

[0104] In multi-beam operation, cell quality may be derived among beams corresponding to the same cell.

[0105] Cell reselection may be implemented. A WTRU in an idle state (e.g., RRC_IDLE) may perform cell reselection. Cell reselection may be implemented based on one or more of the following. Cell reselection may be based on a CD-SSB located on a synchronization raster. The WTRU may measure attributes of a serving cell and a neighboring cell to enable the reselection process. A carrier frequency (e.g., only a carrier frequency) may be indicated for searching and measuring inter-frequency neighboring cells. Cell reselection may identify the cell that the WTRU should pre-occupy. Cell reselection may be based on a cell reselection criterion that may involve measurements of a serving cell and a neighboring cell. Intra-frequency reselection may be based on a ranking of cells. Inter-frequency reselection may be based on an absolute priority (e.g., where the WTRU may attempt to pre-occupy an available high frequency priority, such as the highest priority frequency available). A neighbor cell list (NCL) may be provided by a serving cell to handle specific cases of intra-frequency and inter-frequency neighboring cells. An exclusion list may be provided to prevent the WTRU from reselecting to specific intra-frequency and inter-frequency neighboring cells. An allowed list may be provided to request the WTRU to reselect only to certain (e.g., only certain) intra-frequency and inter-frequency neighboring cells. Cell reselection may be speed dependent. Prioritization may be service specific. Slice specific cell reselection information may be provided to facilitate the WTRU to reselect cells supporting a specific slice. In multi-beam operation, cell quality may be derived based on beams corresponding to the same cell.

[0106] May execute and / or provide state transitions. Figure 3 An example of a WTRU-triggered transition from an idle state to a connected state (e.g., RRC_IDLE state to RRC_CONNECTED state) is illustrated. Figure 3As shown, at 301, the WTRU may request to establish a connection from an idle state (e.g., RRC_IDLE). At 302 / 302a, the gNB may complete the RRC setup process. The scenario in which the gNB rejects the request is described below. At 303, the first NAS message from the WTRU may be transmitted to the AMF (e.g., piggybacked in RRCSetupComplete). At 304 / 304a / 305 / 305a, additional NAS messages may be exchanged between the WTRU and the AMF. At 306, the AMF may prepare WTRU context data (e.g., including PDU session context, security keys, WTRU radio capabilities, WTRU security capabilities, etc.). The AMF may transmit the context data to the gNB. At 307 / 307a, the gNB may activate AS security with the WTRU. At 308 / 308a, the gNB may perform reconfiguration to establish SRB2 and DRB for the WTRU, or to establish SRB2 and (e.g., optionally) DRB for the IAB-MT. At 309, the gNB may notify the AMF that the setup procedure is complete. The RRC messages at 301 and 302 may use SRB0. Subsequent messages may use SRB1. The messages at 307 and / or 307a may be integrity protected. At 308, 308a, and / or 309, the messages may be integrity protected and encrypted. A signaling (e.g., signaling only) connection may skip 308 (e.g., because SRB2 and DRB may not be established).

[0107] Figure 4 An example is illustrated in which the network rejects a WTRU-triggered request to transition from an idle state (e.g., RRC_IDLE), where the WTRU may attempt to set up and / or establish a connection from an idle state (e.g., RRC_IDLE). Figure 4 As shown, at 401, the WTRU may attempt to set up and / or establish a connection from an idle state (e.g., RRC_IDLE). At 402, the gNB may not be able to handle the process (e.g., due to congestion). At 403, the gNB may transmit a rejection message (such as RRCReject) to keep the WTRU in an idle state (e.g., RRC_IDLE). The rejection message may include a wait time.

[0108] Mobility may occur in an inactive state (e.g., RRC_INACTIVE state). An inactive state (e.g., RRC_INACTIVE) may be a state in which the WTRU remains CM-CONNECTED and may move within an area configured by the NG-RAN (e.g., RAN-based Notification Area (RNA)) without notifying the NG-RAN. In an inactive state (e.g., RRC_INACTIVE), the last serving gNB node may maintain / keep the WTRU context and the WTRU-associated NG connection with the serving AMF and UPF.

[0109] When the WTRU is in inactive mode (e.g., RRC_INACTIVE), the last serving gNB may receive DL data from the UPF or DL ​​WTRU associated signaling (e.g., except for the UE Context Release Command message) from the AMF. The last serving gNB may page the cell corresponding to the RNA. The last serving gNB may transmit an XnAP RAN page to a neighboring gNB (e.g., if the RNA includes cells of the neighboring gNB).

[0110] The last serving gNB may receive a WTRU CONTEXT RELEASE COMMAND message (e.g., UE CONTEXT RELEASE COMMAND message) while the WTRU is in an inactive mode (e.g., RRC_INACTIVE). The last serving gNB may page in the cell corresponding to the RNA. The last serving gNB may transmit an XnAP RAN page to a neighboring gNB (e.g., if the RNA includes the cell of the neighboring gNB), e.g., to indicate (e.g., explicitly indicate) that the neighboring gNB releases the WTRU.

[0111] The last serving gNB may receive the NG Reset message when the WTRU is in an inactive mode (e.g., RRC_INACTIVE). The last serving gNB may page the WTRU involved in the cell corresponding to the RNA. The last serving gNB may transmit an XnAP RAN page to a neighboring gNB (e.g., if the RNA includes the cell of the neighboring gNB), for example, to indicate (e.g., explicitly indicate) that the neighboring gNB releases the involved WTRU.

[0112] The AMF may provide core network assistance information to the NG-RAN node (e.g., to assist the NG-RAN node in deciding whether the WTRU may be transferred to an inactive state (e.g., RRC_INACTIVE), and / or to assist in configuration and paging of a WTRU in an inactive state (e.g., RRC_INACTIVE)). The core network assistance information may include one or more of the following: a registration area configured for the WTRU, a periodic registration update timer, a WTRU identity index value, a WTRU-specific discontinuous reception (DRX), an indication of whether the WTRU is configured with a mobile initiated connection only (MICO) mode by the AMF, expected WTRU behavior, WTRU radio capabilities for paging, PEI with paging subpacket assistance information, NR paging extended DRX (eDRX) information, and / or a paging cause indication for voice services.

[0113] The WTRU registration area may be used by the NG-RAN node when configuring RNA. The WTRU specific DRX and WTRU identity index values ​​may be used by the NG-RAN node for RAN paging. The NG-RAN node may use the periodic registration update timer to configure the periodic RNA update timer. The NG-RAN node may use the expected WTRU behavior to assist the WTRU RRC state transition decision. The NG-RAN node may use the WTRU radio capabilities for paging during RAN paging. The NG-RAN node may use PEI with paging sub-group assistance information for sub-group paging in an inactive state (e.g., RRC_INACTIVE). The PEI with paging sub-group assistance information may be included (e.g., if XnAP RAN paging is transmitted to a neighboring NG-RAN node). The NG-RAN node may use NR paging eDRX information to configure RAN paging (e.g., if the NR WTRU is in an inactive state (e.g., RRC_INACTIVE)). NR paging eDRX information for idle state (e.g., RRC_IDLE) and inactive state (e.g., RRC_INACTIVE) may be included (e.g., if XnAP RAN paging is transmitted to a neighboring NG-RAN node). The NG-RAN node may use the paging cause indication for voice services to determine whether to include a paging cause in the RAN paging for a WTRU in an inactive state (e.g., RRC_INACTIVE state). For example, if XnAP RAN paging is transmitted to a neighboring NG-RAN node, the paging cause may be included.

[0114] If the WTRU transitions to an inactive state (e.g., RRC_INACTIVE), the NG-RAN node may configure the WTRU with a periodic RNA update timer value. The periodic RNA update timer may expire without notification from the WTRU.

[0115] The WTRU may access gNBs other than the last serving gNB. The receiving gNB may trigger an XnAP to retrieve a WTRU context procedure (e.g., UE context procedure) to obtain the WTRU context from the last serving gNB. The receiving gNB may trigger an Xn-U address indication (e.g., including tunnel information for potential resumption of data from the last serving gNB). The gNB may (e.g., after a successful WTRU context retrieval) perform slice-aware admission control (e.g., in the event of receiving slice information). The receiving gNB may become the serving gNB. The serving gNB may trigger an NGAP path switch request and applicable RRC procedures. The serving gNB (e.g., after a path switch) may trigger the release of the WTRU context at the last serving gNB (e.g., using the XnAP UE context release procedure).

[0116] The WTRU may not be reachable at the last serving gNB. The gNB may fail the AMF initiated WTRU associated Level 1 procedure which allows the unsuccessful operation to be signaled in the corresponding response message. The gNB may trigger a NAS Non-Delivery Indication to report the non-delivery of any non-PDU Session related NAS PDUs received from the AMF.

[0117] The WTRU may access gNBs other than the last serving gNB. The receiving gNB may not find a valid WTRU context. The receiving gNB may perform establishment of a new RRC connection (e.g., instead of resuming a previous RRC connection). The WTRU context retrieval may fail, which may result in establishing a new RRC connection (e.g., if the serving AMF changes).

[0118] A WTRU in an inactive state (e.g., RRC_INACTIVE state) may initiate an RNA update procedure (e.g., if the WTRU moves out of a configured RNA). The receiving gNB may trigger the XnAP Retrieve WTRU Context procedure to obtain the WTRU context from the last serving gNB (e.g., if the gNB receives an RNA update request from the WTRU). The receiving gNB may decide to transfer the WTRU back to an inactive state (e.g., RRC_INACTIVE state), move the WTRU to a connected state (e.g., RRC_CONNECTED state), or transfer the WTRU to an idle state (e.g., RRC_IDLE). In the example of periodic RNA updates, the last serving gNB may decide not to relocate the WTRU context. The last serving gNB may not have passed the Retrieve WTRU Context procedure and may, for example, transfer the WTRU back to an inactive or idle state (e.g., RRC_INACTIVE or RRC_IDLE) using a release message (e.g., directly through an encapsulated RRCRelease message).

[0119] A WTRU in an inactive state (e.g., RRC_INACTIVE) may perform cell reselection. A WTRU in an inactive state (e.g., RRC_INACTIVE state) may be configured by the last serving NG-RAN node with an RNA. The RNA may cover a single or multiple cells. The RNA may be included in a CN registration area. Xn connectivity may be obtained within the RNA. A RAN-based Notification Area Update (RNAU) may be transmitted by the WTRU (e.g., periodically). If a cell that does not belong to the configured RNA is selected for cell reselection by the WTRU, an RNAU may be transmitted.

[0120] The RNA may be configured (e.g., based on a list of cells and / or a list of RAN areas). The RNA may be configured based on a list of cells. For example, the WTRU may have an explicit list of one or more cells that make up the RNA. The RNA may be configured based on a list of RAN areas. For example, the WTRU may be provided with at least one RAN area ID. The RAN area may be a subset of the CN tracking area, or the same as the CN tracking area. The RAN area may be specified by a RAN area ID (e.g., which may include a TAC and / or a RAN area code). A cell may broadcast one or more RAN area IDs in system information.

[0121] The NG-RAN may provide different RNA definitions to different WTRUs (e.g., but may not mix different definitions to the same WTRU at the same time). The WTRU may support one or more RNA configuration options.

[0122] The WTRU may participate in a state transition. A state transition may be a WTRU triggered transition from an inactive state to a connected state (eg, RRC_INACTIVE to RRC_CONNECTED).

[0123] Figure 5 An example of a WTRU-triggered transition from an inactive state to a connected state (e.g., RRC_INACTIVE to RRC_CONNECTED) is illustrated. For example, Figure 5 An example of a WTRU-triggered transition from RRC_INACTIVE to RRC_CONNECTED following a successful WTRU context retrieval is illustrated. Figure 5 As shown, at 501, the WTRU may resume from an inactive state (e.g., RRC_INACTIVE). The WTRU may provide an I-RNTI, which may be allocated by the last serving gNB. At 502, the gNB may (e.g., if the gNB identity included in the I-RNTI can be resolved) request the last serving gNB to provide WTRU context data (e.g., UE context data). At 503, the last serving gNB may provide the WTRU context data (e.g., UE context data). At 504 and 505, the gNB and the WTRU may complete the resumption of the connection (e.g., RRC connection). For example, if permission is granted, user data may be transmitted (e.g., at 505). At 506, the gNB may provide a forwarding address (e.g., to prevent loss of DL user data buffered in the last serving gNB). At 507 and 508, the gNB may perform a path switch. At 509, the gNB may trigger the release of WTRU resources at the last serving gNB (e.g., UE context release).

[0124] SRB0 may not be used after 501 (e.g., no security). For example, if the gNB decides to use a message (e.g., a single RRC message) to reject the recovery request and keep the WTRU in an inactive state (e.g., RRC_INACTIVE) without any reconfiguration, SRB0 may not be used. If the gNB decides to establish a connection (e.g., RRC Connected), SRB0 may not be used. SRB1 may be used (e.g., with integrity protection and ciphering as previously configured for that SRB). For example, if the gNB decides to reconfigure the WTRU (e.g., with a new DRX cycle or RNA), SRB1 may be used. If the gNB decides to transfer the WTRU to an idle state (e.g., RRC_IDLE), SRB1 may be used.

[0125] If the WTRU context is retrieved (eg, after 503), SRB1 may be (eg, only) used.

[0126] Figure 6 An example of a WTRU-triggered transition from an inactive state to a connected state (e.g., RRC_INACTIVE to RRC_CONNECTED) is illustrated. For example, Figure 6 An example of a WTRU-triggered transition from RRC_INACTIVE to RRC_CONNECTED following a WTRU context retrieval failure is illustrated. Figure 6 As shown, at 601, the WTRU may resume from an inactive state (e.g., RRC_INACTIVE). The WTRU may provide an I-RNTI, which may have been allocated by the last serving gNB. At 602, the gNB (e.g., if the gNB identity included in the I-RNTI can be resolved) may request the last serving gNB to provide WTRU context data (e.g., using Retrieve UE Context Failure). At 603, the last serving gNB may not retrieve or verify the WTRU context data (e.g., using Retrieve UE Context Request). At 604, the last serving gNB may indicate the failure to the gNB. At 605, the gNB may perform a fallback to establish a connection (e.g., RRC Connection), for example, by transmitting a message (e.g., RRCSetup). At 606, the connection may be established.

[0127] Figure 7 An example of a rejection from the network when a WTRU attempts to resume a connection from an inactive state (e.g., RRC_INACTIVE) is illustrated. Figure 7 As shown, at 701, the WTRU may attempt to recover the connection from an inactive state (e.g., RRC_INACTIVE). At 702, the gNB may not be able to handle the process (e.g., due to congestion). At 703, the gNB may transmit an RRCReject (e.g., with a waiting time) to keep the WTRU in an inactive state (e.g., RRC_INACTIVE).

[0128] The transition from the inactive state to the connected state (eg, RRC_INACTIVE to RRC_CONNECTED) may be network triggered. Figure 8 An example of a network-triggered transition from an inactive state to a connected state (eg, RRC_INACTIVE to RRC_CONNECTED) is illustrated. Figure 8As shown, at 801, a RAN paging trigger event may occur (e.g., incoming DL user plane, DL signaling from 5GC, etc.). At 802, RAN paging may be triggered (e.g., in a cell controlled by the last serving gNB, or through Xn RAN paging in cells controlled by other gNBs). RAN paging may be configured for the WTRU in the RNA. At 803, the WTRU may be paged using the I-RNTI. At 804, the WTRU may be successfully reached. The WTRU may attempt to recover from an inactive state (e.g., RRC_INACTIVE).

[0129] RNA updates may be performed. RNA updates may be WTRU triggered RNA update procedures (eg, involving context retrieval on Xn). RNA updates may be triggered by RNA removal of a configured WTRU. RNA updates may be triggered periodically.

[0130] Fig. 9 An example of an RNA update procedure (eg, with WTRU context relocation) is illustrated. Fig. 9 As shown, at 901, the WTRU may resume from an inactive state (e.g., RRC_INACTIVE). The WTRU may provide an I-RNTI, which may be allocated by the last serving gNB. The WTRU may provide an appropriate cause value (e.g., RAN Notification Area Update). At 902, the gNB (e.g., if the gNB identity included in the I-RNTI can be resolved) may request the last serving gNB to provide a WTRU context (e.g., using a Retrieve UE Context Request, e.g., providing the cause value received at 901). At 903, the last serving gNB may provide the WTRU context (e.g., using a Retrieve UE Context Response). The last serving gNB may decide to move the WTRU to an idle state (e.g., RRC_IDLE), as relative to Fig.11 As described at 1103-1105. Fig. 9 As illustrated, the WTRU may be within a previously configured RNA. The WTRU context in the last serving gNB may be maintained. The WTRU may remain in an inactive state (e.g., RRC_INACTIVE), as compared to Fig.10 As described at 1003-1004. At 904, the gNB may move the WTRU to a connected state (e.g., RRC_CONNECTED), as described with respect to Figure 8 As described at 804. Fig. 9As shown, the gNB may transfer the WTRU back to RRC_IDLE (e.g., in this case, an RRCRelease message may be transmitted by the gNB). The gNB may transfer the WTRU back to an inactive state (e.g., RRC_INACTIVE). At 905, the gNB may provide a forwarding address (e.g., to prevent loss of DL user data buffered in the last serving gNB). At 906 and 907, the gNB may perform a path switch. At 908, the gNB may maintain the WTRU in an inactive state (e.g., RRC_INACTIVE state). For example, the gNB may maintain the WTRU in an inactive state by transmitting a message with a suspend indication (e.g., RRCRelease). At 909, the gNB may trigger the release of the WTRU resources at the last serving gNB (e.g., using UE context release).

[0131] RNA update may be implemented. For example, if the WTRU is within the configured RNA and the last serving gNB decides not to relocate the WTRU context and keep the WTRU in an inactive state (e.g., RRC_INACTIVE), then an RNA update may occur.

[0132] Fig.10 An example of a periodic RNA update procedure without WTRU context relocation is illustrated. Fig.10 As shown, at 1001, the WTRU may resume from an inactive state (e.g., RRC_INACTIVE). The WTRU may provide an I-RNTI, which may be allocated by the last serving gNB. The WTRU may provide an appropriate cause value (e.g., RAN Notification Area Update). At 1002, the gNB (e.g., if the gNB identity included in the I-RNTI can be resolved) may request the last serving gNB to provide the WTRU context (e.g., using a Retrieve UE Context Request, e.g., providing the cause value received at 1001). At 1003, the last serving gNB may store the received information for use in the next recovery attempt (e.g., C-RNTI and PCI associated with the recovery cell). The last serving gNB may respond to the gNB with a Retrieve WTRU Context Failure message (e.g., a Retrieve UE Context Failure message, e.g., including an encapsulated RRCRelease message). The RRCRelease message may include a suspend indication. At 1004, the gNB may forward the RRCRelease message to the WTRU.

[0133] If the last serving gNB decides to move the WTRU to an idle state (e.g., RRC_IDLE), an RNA update may be implemented.

[0134] Fig.11An example of RNA update with a transition to an idle state (eg, RRC_IDLE) is illustrated. Fig.11 As shown, at 1101, the WTRU may resume from an inactive state (e.g., RRC_INACTIVE). The WTRU may provide an I-RNTI, which may be allocated by the last serving gNB. The WTRU may provide an appropriate cause value (e.g., RAN Notification Area Update). At 1102, the gNB (e.g., if the gNB identity included in the I-RNTI can be resolved) may request the last serving gNB to provide the WTRU context (e.g., using a Retrieve UE Context Request, e.g., providing the cause value received at 1101). At 1103, the last serving gNB may provide a RRCRelease message (e.g., in lieu of providing the WTRU context, e.g., except for the failure to retrieve the UE context) to move the WTRU to an idle state (e.g., RRC_IDLE). At 1104, the last serving gNB may delete the WTRU context (e.g., UE context). At 1105, the gNB may transmit a RRCRelease, which may trigger the WTRU to move to an idle state (e.g., RRC_IDLE).

[0135] The resume request response may include a release with redirection indication and / or WTRU context relocation. The network may respond to a resume request (e.g., a NAS procedure) triggered by the WTRU. For example, the network may respond with a release with redirection (e.g., with WTRU context relocation).

[0136] Fig.12 An example of a resume request and a response with a release with redirection and WTRU context relocation is illustrated. Fig.12 As shown, at 1201, the WTRU may resume from an inactive state (e.g., RRC_INACTIVE). The WTRU may provide an I-RNTI, which may be allocated by the last serving gNB. At 1202, the gNB (e.g., if the gNB identity included in the I-RNTI can be resolved) may request the last serving gNB to provide WTRU context data (e.g., using a Retrieve UE Context Request). At 1203, the last serving gNB may provide the WTRU context (e.g., using a Retrieve UE Context Response). At 1204, the gNB may move the WTRU to a connected state (e.g., RRC_CONNECTED), as shown with respect to Figure 8 As described at 804. See again Fig.12, the gNB may transfer the WTRU to an idle state (e.g., RRC_IDLE), in which case a message (e.g., an RRCRelease message) may be transmitted by the gNB. The gNB may transfer the WTRU to an inactive state (e.g., RRC_INACTIVE), for example including a release with a redirection indication. At 1205, the gNB may provide a forwarding address (e.g., to prevent loss of DL user data buffered in the last serving gNB). At 1206-1207, the gNB may perform a path switch. At 1208, the gNB may keep the WTRU in an inactive state (e.g., RRC_INACTIVE), for example, by transmitting an RRCRelease with a suspend indication (e.g., including redirection information). The redirection information may include a frequency layer, where the WTRU may perform cell selection based on entering the inactive state RRC_. At 1209, the gNB may trigger the release of the WTRU resources at the last serving gNB (e.g., using UE context release). Higher layers may trigger pending procedures, for example based on receiving a release with redirection. The WTRU may attempt to resume again after cell selection.

[0137] Paging may allow the network to reach WTRUs in an idle state and an inactive state (e.g., RRC_IDLE and in RRC_INACTIVE state) via paging messages. Paging may allow the network to notify WTRUs in an idle, inactive, and / or connected state (e.g., RRC_IDLE, RRC_INACTIVE, and RRC_CONNECTED states) via short messages about system information changes and / or ETWS / CMAS indications. Paging messages and short messages may be addressed with a P-RNTI on a physical downlink control channel (PDCCH). Paging messages may be transmitted on a paging control channel (PCCH). Short messages may be transmitted on the PDCCH (e.g., directly).

[0138] The WTRU may monitor the paging channel for CN initiated paging (e.g., when the WTRU is in idle state) (e.g., when in RRC_IDLE). The WTRU may monitor the paging channel for RAN initiated paging and CN initiated paging (e.g., when the WTRU is in inactive state with no SDT process in progress) (e.g., when in RRC_INACTIVE with no SDT process in progress). The WTRU may monitor the paging channel discontinuously. Paging DRX may support discrete or periodic monitoring. A WTRU in an idle state or inactive state (e.g., RRC_IDLE or RRC_INACTIVE) may monitor the paging channel during a paging occasion (PO) in a DRX cycle. For example, the paging DRX cycle may be configured by the network for CN initiated paging (e.g., a default cycle may be broadcast in system information). The paging DRX cycle may be configured by the network for CN initiated paging (e.g., a WTRU specific cycle may be configured via NAS signaling). The paging DRX cycle may be configured by the network for RAN initiated paging (e.g., a WTRU specific cycle may be configured via RRC signaling). The WTRU may use the shortest DRX cycle that is applicable. For example, a WTRU in an idle state (e.g., RRC_IDLE) may use the shorter of the first two DRX cycles. A WTRU in an inactive state (e.g., RRC_INACTIVE) may use the shortest of the first three DRX cycles.

[0139] The POs of the WTRU for CN initiated paging and RAN initiated paging may be based on the same WTRU ID, which may result in overlapping POs for both. The number of different POs in a DRX cycle may be configurable (e.g., via system information). The network may distribute the WTRUs to the POs based on their IDs.

[0140] A WTRU (e.g., when in a connected state such as RRC_CONNECTED, and / or when in an inactive state such as RRC_INACTIVE, with an ongoing SDT procedure) may monitor the paging channel in any PO signaled in the system information for SI change indications and / or PWS notifications. A WTRU (e.g., a WTRU in a connected state such as RRC_CONNECTED) may (e.g., in the case of a BA) monitor (e.g., only monitor) the paging channel on an active BWP with a configured common search space.

[0141] A WTRU (e.g., configured to operate with shared spectrum channel access) may be configured with multiple PDCCH monitoring occasions in the WTRU's PO to monitor for paging. The WTRU may detect a PDCCH transmission within the PO addressed by the WTRU's P-RNTI. The WTRU may not monitor subsequent PDCCH monitoring occasions within the PO.

[0142] A WTRU (eg, a WTRU in an idle or inactive state such as RRC_IDLE or RRC_INACTIVE) may use a paging cause (eg, if the paging cause is included in a paging message).

[0143] Paging optimization may be performed for a WTRU (e.g., a WTRU in CM_IDLE). The NG-RAN node may provide a list of recommended cells and NG-RAN nodes to the AMF as assistance information for subsequent paging (e.g., at WTRU context release). The AMF may provide paging attempt information. The paging attempt information may include a paging attempt count, an expected number of paging attempts, and / or a next paging area range. Each paging NG-RAN node may receive the same information during a paging attempt (e.g., if the paging attempt information is included in the paging message). The paging attempt count may be increased (e.g., by one) at each new paging attempt. The next paging area range (e.g., if any) may indicate whether the AMF plans to modify the paging area currently selected at the next paging attempt. The paging attempt count may be reset (e.g., if the WTRU changes its state to CM_CONNECTED).

[0144] Paging optimization may be performed for a WTRU that is in an inactive state (e.g., RRC_INACTIVE). The serving NG-RAN node may provide RAN paging area information (e.g., during RAN paging). The serving NG-RAN node may provide RAN paging attempt information. Each paging NG-RAN node may receive the same RAN paging attempt information during a paging attempt. The information may include, for example, one or more of: a paging attempt count, an expected number of paging attempts, and / or a next paging area range. The paging attempt count may be increased (e.g., incremented by one) at a paging attempt (e.g., each paging attempt). The next paging area range (e.g., if present) may indicate whether the serving NG_RAN node plans to modify the RAN paging area currently selected at the next paging attempt. If the WTRU leaves an inactive state (e.g., RRC_INACTIVE state), the paging attempt count may be reset.

[0145] WTRU power savings may be achieved for paging monitoring. WTRU power consumption (e.g., caused by false paging alerts) may be reduced by dividing a group of WTRUs monitoring the same PO into multiple subgroups. Using subgroups, for example, if the subgroup to which the WTRU belongs is paged (e.g., as indicated via an associated PEI), the WTRU may monitor the PDCCH in the PO for paging. The WTRU may monitor the WTRU's PO for paging (e.g., if the WTRU does not find its subgroup ID with a PEI configuration in the cell and / or if the WTRU cannot monitor the associated PEI opportunity corresponding to its PO).

[0146] The subgroups may have one or more of the following characteristics. The subgroups may be formed based on CN controlled subgroups. The subgroups may be based on the WTRU ID. Subgroups based on the WTRU ID may be used (e.g., if supported by the WTRU and the network). For example, if the AMF does not provide a CN controlled subgroup ID, subgroups based on the WTRU ID may be used. The RRC state (e.g., RRC_IDLE or RRC_INACTIVE state) may not affect the subgroup to which the WTRU belongs. Subgroup support for a cell may be broadcast in system information. For example, subgroup support may indicate one or more of the following: support for CN controlled subgroups, and / or support for subgroups based on the WTRU ID. The number of subgroups allowed in a cell (e.g., the total number of subgroups) may be limited (e.g., up to 8). The total number may represent the sum of CN controlled subgroups and WTRU ID based subgroups configured by the network. A WTRU configured with a CN controlled subgroup ID may apply the CN controlled subgroup ID (e.g., if the cell supports CN controlled subgroups). The WTRU may derive a sub-group ID based on the WTRU ID (eg, if the cell supports sub-grouping based on the WTRU ID).

[0147] The PEI associated with a subgroup may have one or more of the following characteristics. For example, if the WTRU supports PEI, the PEI may support subgrouping based on the WTRU ID. PEI monitoring may be limited (e.g., via system information) to the cell where the last connection was released, unless the network indicates that the WTRU may not update its last used cell information. A WTRU with PEI capability may store its last used cell information. One or more gNBs that support PEI monitoring of the last used cell functionality may provide the WTRU's last used cell information to the AMF (e.g., in a NG-AP WTRU Context Release Complete message for WTRUs with PEI capability). A WTRU that expects MBS group notification may ignore the PEI and may monitor paging in its PO.

[0148] CN controlled subgrouping may be implemented. For CN controlled subgrouping, the AMF may be responsible for assigning a subgroup ID to the WTRU. The total number of subgroups for CN controlled subgrouping may be configured (e.g., by operations and management (OAM)). One or more (e.g., up to 8) subgroups may be available for CN controlled subgrouping. CN controlled subgrouping support may be uniform within the RNA.

[0149] Fig.13 An example of a process for CN controlled sub-grouping is illustrated. Fig.13 As shown, at 1301, the WTRU may indicate that the WTRU supports CN controlled subgroups (e.g., via NAS signaling). At 1302, the AMF may determine a subgroup ID assignment for the WTRU (e.g., if the WTRU supports CN controlled subgroups). At 1303, the AMF may transmit the subgroup ID to the WTRU (e.g., via NAS signaling). At 1304, the AMF may notify the gNB about the CN assigned subgroup ID for paging the WTRU in an idle state and / or inactive state (e.g., RRC_IDLE and / or RRC_INACTIVE state). At 1305, the gNB may determine the PO and associated PEI timing for the WTRU (e.g., if a paging message for the WTRU is received from the CN and / or generated by the gNB). At 1306, the gNB may send the associated PEI (e.g., before the WTRU is paged in the PO) and / or may indicate the corresponding CN controlled subgroup of the WTRU that may be paged in the PEI.

[0150] WTRU ID based subgrouping may be implemented. The gNB and / or the WTRU may determine the subgroup ID for the WTRU ID based subgrouping based on the WTRU ID and / or the total number of subgroups of the WTRU ID based subgrouping in the cell. The total number of subgroups for the WTRU ID based subgrouping may be determined by the gNB for the cell (e.g., each cell). The number of subgroups for the WTRU ID based subgrouping (e.g., the total number of subgroups) may be different in different cells.

[0151] Fig.14 An example of a sub-grouping procedure based on a WTRU ID is illustrated. Fig.14As shown, at 1401, the gNB may determine the total number of subgroups of the subgroups based on the WTRU ID in the cell. At 1402, the WTRU may determine the WTRU subgroups. At 1403, the gNB may broadcast the total number of subgroups of the subgroups based on the WTRU ID in the cell. At 1404, the gNB may determine the PO and / or associated PEI timing for the WTRU (e.g., if a paging message for a WTRU with PEI capability is received at the gNB from the CN and / or generated by the gNB). At 1405, the gNB may send the associated PEI (e.g., before the WTRU is paged in the PO) and / or may indicate a corresponding subgroup derived based on the WTRU ID of the WTRU to be paged in the PEI.

[0152] Extended DRX may be implemented for idle and / or inactive states (e.g., RRC_IDLE and RRC_INACTIVE states). If extended DRX (eDRX) is used for idle or inactive states (e.g., RRC_IDLE and RRC_INACTIVE states), one or more of the following may apply. In an inactive state (e.g., RRC_INACTIVE), the eDRX configuration for RAN paging may be determined and configured by the NG-RAN. In an inactive state (e.g., RRC_INACTIVE), the WTRU may monitor RAN and CN paging. For an idle state (e.g., RRC_IDLE), eDRX for CN paging may be configured by upper layers. A WTRU in an idle state (e.g., RRC_IDLE state) may monitor CN paging. Information about whether eDRX is allowed on a cell for a WTRU in an idle and inactive state (e.g., RRC_IDLE and RRC_INACTIVE) may be provided separately for the idle and inactive states (e.g., RRC_IDLE and RRC_INACTIVE) (e.g., in system information). The maximum value of the eDRX cycle may be limited (e.g., 10485.76 seconds or 2.91 hours for the RRC_IDLE state and 10.24 seconds for the RRC_INACTIVE state). The minimum value of the eDRX cycle may be limited (e.g., 2.56 seconds for RRC_IDLE and RRC_INACTIVE states). A super SFN (H-SFN) may be broadcast by the cell. When the SFN wraps around, the SFN may be incremented by one. A paging superframe (PH) may refer to an H-SFN where the WTRU starts monitoring paging DRX during the paging time window (PTW) used in the RRC_IDLE state. The PH and PTW may be determined based on a formula provided by the AMF, WTRU and / or NG-RAN. For example, if the eDRX cycle is greater than the maximum eDRX cycle in the RRC-INACTIVE state (e.g., 10.24 seconds), the H-SFN, PH and PTW may be used. The WTRU may verify that the stored system information remains valid before establishing an RRC connection (e.g., if the eDRX cycle is longer than the system information modification period).

[0153] Measurements, mobility and / or service continuity may be specified for NTN-TN and NTN-NTN. For NTN-NTN mobility, cell reselection may be specified for NTN-NTN earth mobile cells. Cell reselection may be timing-based and / or location-based cell reselection. NTN-NTN handover for RRC_CONNECTED WTRUs in quasi-earth fixed cells and earth mobile cells may be configured to reduce signaling overhead. Cell reselection for RRC_IDLE / INACTIVE WTRUs may be configured to reduce WTRU power consumption (e.g., NTN-TN mobility may be prioritized). Xn / NG signaling may support feeder link switching and CHO (e.g., exchanging information between gNBs).

[0154] The network may include several layers, such as terrestrial networks, LEO, MEO and / or GEO satellites. Each layer may operate with different cell sizes and / or different air propagation delays. The GEO layer may have the largest cell coverage with the longest propagation delay. The MEO layer and LEO layer may have smaller cell coverage and shorter propagation delays. The terrestrial network may have the smallest cell coverage with the shortest propagation delay.

[0155] Fig.15 An example of the NTN-TN network layer is illustrated.

[0156] Although the examples involve TN to NTN coverage, these examples are applicable to any combination of network layers, such as LEO to GEO, TN to MEO to GEO, etc.

[0157] From a WTRU power saving perspective, the WTRU may consume less power on the NTN (e.g., if there is TN and NTN coverage). The NTN may have wider coverage than the TN. A WTRU camped on the NTN may reduce / minimize neighbor cell measurements, cell reselection, SI reading, etc., especially for mobile WTRUs.

[0158] From the perspective of NW paging load, paging can use fewer resources for WTRUs that are pre-occupied in NTN cells. NTN can provide wider coverage than TN. The WTRU cell location may be known to one cell or several cells. There may be no need to upgrade paging across multiple cells (for example, as in TN networks, where paging may first be transmitted to a subset of cells within the tracking / RAN area, then another subset, and so on, until it reaches the WTRU). A WTRU in a TN may perform cell reselection (for example, without notifying the network) in an idle state (for example, RRC_IDLE) within a tracking area and in an inactive state (for example, RRC_INACTIVE) within a RAN notification area. The network may page in multiple cells to find the WTRU location. A WTRU in an NTN (for example, in GEO) is unlikely to perform several cell reselections (for example, because the cell area is large). In other NTN layers (for example, LEO, Earth Mobile Layer), the cell location may be known. For example, in the case of cell reselection within a TA / RNA, multiple cells may be within a large geographic area. The WTRU may be paged on one or more cells.

[0159] From a latency point of view, there may be lower latency for a WTRU camping on a TN cell. The RRC setup / recovery process and / or data transfer may be subject to long propagation delays in the NTN. The TN may have lower signaling latency and / or higher data throughput. The notification and delivery of paging messages in the NTN may have longer latency than in the TN. The NTN may have fewer paging escalation instances.

[0160] Overlay network layers (eg, overlapping TN-NTN overlays) may be used to realize the power saving and paging load benefits of NTN without the disadvantages of longer latency, longer session setup time, and limited throughput.

[0161] A WTRU in an idle state or inactive state (e.g., RRC_IDLE or RRC_INACTIVE state) may use an NTN cell for paging. The WTRU may respond using a TN cell. An example of NTN paging with a TN response is shown in Fig.16 Example in.

[0162] Fig.16 An example of paging a WTRU in the NTN using a paging response from a WTRU in the TN is illustrated.

[0163] The WTRU may prioritize or pre-occupy the NTN. The network may provide (e.g., absolute) priority for the NTN frequency layer relative to the TN frequency layer (e.g., based on a cell reselection principle). An idle mode WTRU may pre-occupy the NTN (e.g., if the WTRU reselects to the highest priority layer available and if the WTRU meets the cell reselection criteria). The WTRU may use one or more techniques to prioritize or pre-occupy the NTN.

[0164] A mobile terminated call may be initiated on the TN (e.g., if the WTRU is camped on the NTN). Allowing the WTRU to camp on the NTN may reduce the paging load in the NW. For example, because the NTN cells are large, paging escalations (e.g., paging on the last known cell and then on multiple other cells in the area) and / or paging in multiple cells by default may be reduced / minimized compared to paging on the TN. There may be power saving benefits for a WTRU camped on the NTN. For example, because there may be less need to perform neighbor cell measurements, cell reselection, etc. (e.g., due to the relatively large geographical size of the NTN cells), especially if the WTRU is moving.

[0165] While camping on the NTN may provide power saving benefits to the WTRU and paging load benefits to the network, latency may increase due to longer signal propagation times. In some examples, an RRC connection establishment and / or call establishment may be performed on the NTN, followed by a handover from the NTN to the TN. The messages involved in the setup process (e.g., each message) may experience long delays, which may make the call setup time on the NTN significantly longer compared to the call setup on the TN. In some examples, a redirection (e.g., an option for moving from NR to LTE) may be performed. Redirection may incur relatively long latency due to the exchange of several RRC messages before the RAT change occurs. For example, latency may be improved if the change of RAT (e.g., NTN to TN) occurs at the earliest possible time. In response to receiving a page, the WTRU may perform a cell reselection or redirection to the TN. The WTRU response to the page in the TN may reduce the latency of the call setup, for example, because the WTRU and the network may incur / experience a shorter propagation delay (e.g., random access) starting from Msg1. Call setup may be performed on the TN (eg, only paging message delivery takes longer on the NTN). The likelihood of paging escalation between multiple cells may be reduced (eg, because in many cases the WTRU location is known to the network at the cell level).

[0166] Fig.17 An example procedure for paging a WTRU in an NTN cell with the response of a WTRU in a TN cell is illustrated.

[0167] like Fig.17 As shown, at 1701, the WTRU may camp on the NTN. The WTRU may receive an indication that a paging message is scheduled. For example, the WTRU may receive a PDCCH scrambled with a P-RNTI (e.g., or another P-RNTI used for this type of paging). The PDCCH may indicate that the paging message is scheduled. At 1702, the WTRU may receive a paging message from the NTN (e.g., on the PDSCH). The paging message may indicate that the WTRU responds to the paging message on the TN. At 1703, the WTRU may perform a cell change from the NTN to the TN (e.g., to camp on the TN cell). At 1704, the WTRU may transmit an access request to a TN node associated with the TN cell to initiate or resume, for example, a connection on the TN cell (e.g., an RRC connection). For example, the WTRU may transmit an access request to initiate or resume a connection on the TN cell using the cause "mt-access" (or other establishment cause for this type of MT access). At 1705, the WTRU may transmit a NAS paging response message (e.g., to the TN).

[0168] The paging message may indicate a cell change (e.g., from an NTN cell to a TN cell). The paging message may include a paging record. The paging record may include a list of WTRU identities (e.g., to address a specific WTRU). In some examples, the paging record list may (e.g., be extended to) include an indication (e.g., a 1-bit indication) associated with a WTRU ID included in the paging record. The WTRU may be configured to respond to the indication. For example, the WTRU may (e.g., based on receiving the indication) respond by triggering a cell change from NTN to TN (e.g., to transmit a paging response to the paging message).

[0169] The paging message may include an indication of one or more preferred target TN cells (e.g., preferred carrier frequencies or ARFCNs) and / or individual TN cell identities. For example, the paging message may indicate a first target TN cell and a second target TN cell. The paging message may indicate first priority information associated with the first target TN cell and second priority information associated with the second target TN cell.

[0170] Each target TN cell may be associated with a reference signal quality (e.g., a first target TN cell is associated with a first reference signal quality and a second target TN cell is associated with a second reference signal quality). For example, the preferred carrier frequency indication may include a threshold RSRP and / or RSRQ value (e.g., above which a cell on the carrier may be considered suitable for completing a paging response). The WTRU may select a TN cell based on the reference signal quality of the target TN cell (e.g., if the signal quality satisfies a threshold / condition). The WTRU may select a TN cell based on additional conditions (e.g., satisfying a best TN cell condition) or randomly select a TN cell (e.g., if multiple TN cells have signal levels above a threshold).

[0171] The WTRU may be configured (e.g., via signaling) to respond on other network types prior to receiving a paging indication. The WTRU may be configured with a preferred target TN cell (e.g., frequency, PCI, etc.) and / or one or more signal level thresholds for determining whether to respond on a TN cell. The configuration may be provided in an RRC release message that transmits the WTRU to an idle / inactive state, in an RRC reconfiguration message or broadcast signaling when the WTRU is in a connected state, in broadcast signaling when the WTRU is in an idle / inactive state, via higher layer or non-RAN level configuration (e.g., such as OAM), etc.

[0172] The paging message may include first timing information associated with the first target TN cell and second timing information associated with the second target TN cell. For example, the paging message may include the timing relationship between the NTN cell and the TN cell (e.g., to reduce synchronization time and / or to help determine the target SSB location). The WTRU may apply the timing information associated with the selected TN cell. For example, if the WTRU selects the first target TN cell, the WTRU may apply the first timing information. If the WTRU selects the second target TN cell, the WTRU may apply the second timing information.

[0173] The paging message may include a service type indication. The service type may be associated with the network type. For example, for some services, the WTRU may respond on the same cell, while for other services, the WTRU may move to another network or RAT type to respond.

[0174] The paging message may include a cell reselection priority indication (e.g., indicating priority information associated with available TN cells). For example, the cell reselection priority indication may indicate a priority for a serving (NTN) frequency (e.g., an indication that the frequency is considered to have a lower priority than a configured TN frequency) and / or a priority for a target (TN) frequency or frequencies (e.g., an indication that the target frequency is considered to have a higher priority than the NTN frequency). The cell reselection priority indication may include corresponding priority values ​​(e.g., explicit priority values) for the serving and / or target frequencies. The WTRU may perform a cell reselection evaluation using the assigned or determined priority values. For example, the WTRU may select a TN cell from a first target TN cell and a second target TN cell based at least on first priority information associated with the first target TN cell and second priority information associated with the second target TN cell.

[0175] The paging message may include an indication of the uplink resources to be used on the target cell when initiating a paging response. For example, the uplink resources may be a specific PRACH preamble or a RACH opportunity.

[0176] The WTRU may determine a target frequency and / or one or more target frequency priorities based on one or more potential target frequencies (e.g., based on the WTRU ID). The WTRU may perform a cell reselection to the determined frequency (e.g., based on the determined target frequency priority). For example, each target TN cell may be associated with a frequency (e.g., a first target TN cell is associated with a first frequency and a second target TN cell is associated with a second frequency). The WTRU may select a TN cell based on the associated frequencies. For example, if the first frequency is closer to the target frequency than the second frequency (e.g., if the difference between the first frequency and the target frequency is less than the difference between the second frequency and the target frequency), the WTRU may select the first target TN cell. If the second frequency is closer to the target frequency than the first frequency (e.g., if the difference between the first frequency and the target frequency is greater than the difference between the second frequency and the target frequency), the WTRU may select the second target TN cell.

[0177] The paging message may include an index to a configuration. The configuration may be pre-configured, for example, in the broadcast system information and / or in a table defined / configured in the specification. The broadcast information corresponding to the index may include information that the WTRU may apply when performing a change in network type. The paging message may indicate one of several pre-configured network change configurations.

[0178] The WTRU may store system information blocks for TN cells (e.g., known TN cells). The WTRU may use the system information blocks after receiving a paging message instructing the WTRU to respond on a TN. The WTRU may verify (e.g., by reading SIB1 of a known cell) that the stored system information is valid (e.g., when the WTRU is reselecting a TN cell). The stored system information may be associated with a validity time. If the timer is still running, the WTRU may consider the stored system information to be valid. In addition to the MIB, the WTRU may not need to read the system information (e.g., including SIB1) of the TN cell (e.g., because the MIB includes SFN information and forms part of the SSB). This may reduce the time required to perform a cell change and transmit a paging response on a TN cell.

[0179] The WTRU may be configured to monitor an RNTI (e.g., a redirected RNTI). The redirected type of RNTI may be similar to the P-RNTI (e.g., in the sense that the WTRU may monitor the P-RNTI and receive paging messages). The difference between the redirected RNTI and the P-RNTI may be that a paging notification scrambled with the redirected RNTI may be decoded by (e.g., only by) a WTRU that has been configured to use the redirected RNTI. The WTRU may be configured during a previous connection and / or based on hard coding in the WTRU (e.g., by the manufacturer or network operator).

[0180] The WTRU may select a TN cell based on the satisfaction of a condition. For example, the condition may be satisfied if the paging message is scrambled with an RNTI associated with a cell redirection (e.g., a redirection RNTI). Receipt of a paging indication scrambled with a redirection RNTI may (e.g., implicitly) indicate that the WTRU should respond on a different network type (e.g., as described herein, if the WTRU receives a paging message from an NTN, the WTRU may respond on a TN).

[0181] A WTRU may be assigned a CN controlled subgroup to operate using a PEI. The network may configure the WTRU to respond to a paging indication and a paging message. The WTRU's response to a paging message or a paging indication may be triggered by a PEI addressed to a subgroup (e.g., on another network type).

[0182] The paging may include an indication to perform (e.g., only perform) a redirection (e.g., in anticipation of service start). The indication may be used to update a priority, or to reselect to a particular frequency. The indication may not result in a paging response being initiated on the target frequency. The indication may (e.g., be configured to) cause the WTRU to perform a cell reselection and monitor for paging on the target frequency. The indication may be associated with a validity timer. The WTRU may reset the updated priority or cell reselection information determined based on the paging notification in the NTN RAT. If the WTRU has not received a paging message on the target frequency before the timer expires, the WTRU may return to camping on the NTN.

[0183] The paging may instruct the WTRU to transmit a measurement report, for example, to an NTN (e.g., an NTN cell). The measurement report may indicate a request for first priority information associated with a first target TN cell and second priority information associated with a second target TN cell. The priority information may be based on the measurement report. The measurement report may include a request for the best n TN cells (e.g., so that the network can perform redirection to a specific carrier or cell based on the reported measurements).

[0184] The indication to perform reselection / redirection / prioritization of a TN cell or carrier from an NTN carrier based on paging may be associated with a timer. The WTRU may transmit an access request to a TN cell. The WTRU may start a timer after transmitting the access request. The WTRU may fail to determine a suitable cell on the target carrier or cell, fail to successfully establish an RRC connection, and / or fail to receive a random access response by timer expiration (e.g., before the timer expires). The WTRU may transmit a response to the NTN (e.g., on an NTN cell) and / or continue to monitor for subsequent paging from the NTN (e.g., on an NTN cell) (e.g., under the condition that the connection fails or no access response is received before the timer expires). Other failure conditions may be used, such as RRC connection rejection on the target cell, RACH failure (e.g., the WTRU performs maximum allowed RACH retransmissions), failure to read system information on the target cell, fallback indicator in the random access response. The failure may cause the WTRU to return to the original cell and / or transmit a paging response on the original cell.

[0185] The WTRU may provide a paging response (e.g., after performing a cell change in response to receiving a paging message). The WTRU may attempt to perform an RRC connection establishment or an RRC connection recovery (e.g., to send a paging response message). The paging response message may include a service request, an extended service request, another NAS message, an RRC connection establishment request, and / or a recovery message.

[0186] The paging response message may indicate that the paging response (e.g., access request) is triggered by an NTN node. For example, the paging response message may include an indication of providing a paging response in response to a paging message received on another (e.g., NTN) cell. The paging response may include an identifier of another (e.g., NTN) cell. For example, the identifier of another (e.g., NTN) cell may be a physical cell identity, a tracking area code, and / or a RAN notification area code. The paging response message may include measurement results of other cells that the WTRU has detected and / or measured (e.g., such as a list of the best n cells). The WTRU may include timing information associated with the TN cell in the paging response. For example, the timing information may include the time since a paging indication or paging message was received on another network. The paging response message may include a service type indicator (e.g., an indication of the service type indicated in the paging message). The WTRU may select a TN cell based on the service type indicator. The paging response message may include an identifier included in a paging record and / or a paging record included in a paging message.

[0187] The RRC connection establishment or resumption message may include a cause value (eg, "mt-access-ntn"). The cause value may indicate that the connection is being established in response to paging on another network (eg, NTN).

[0188] The TN cell may provide a set of uplink resources (e.g., RACH resources or a set of PRACH preambles) for the WTRU to select when initiating access to the TN cell in response to a page on another network (e.g., NTN). For example, the TN cell may (e.g., directly) provide resources to the WTRU (e.g., before the WTRU selects the NTN). The TN cell may provide resources to the NTN cell. The NTN cell may forward resources to the WTRU.

[0189] Each TN cell may be associated with a different set of uplink resources. The WTRU may transmit an access request using the uplink resources associated with the selected TN cell. Sending a PRACH preamble using reserved resources or preambles may (e.g., implicitly) indicate that the WTRU is responding to a page on another network (e.g., NTN) and / or may separate accesses of WTRUs that have camped on a TN cell from WTRUs that respond in response to a page on another network (e.g., NTN).

[0190] Although the examples describe paging the WTRU on the NTN and the WTRU responding on the TN, the examples are equally applicable to the scenario where the network pages the WTRU on the TN and the WTRU responds on the NTN.

[0191] Although the examples describe TN and NTN, these examples are equally applicable to scenarios involving other networks or network layers. For example: a WTRU paged on the GEO layer may (e.g., be notified) respond on the LEO layer; a WTRU paged on the GEO layer may (e.g., be notified) respond on the MEO layer; a WTRU paged on the MEO layer and notified to respond on the TN; and so on.

[0192] The WTRU may be configured to be paged on a first layer (e.g., the GEO layer) and may respond on one or more other layers (e.g., depending on the priority and availability of cells at that layer). For example, the WTRU may (e.g., be configured to) be paged on the GEO layer and respond on the TN (e.g., if a suitable cell at the TN level is available), the LEO layer / cell (e.g., if a suitable cell at the LEO level is available), the MEO layer / cell (e.g., if a suitable cell at the MEO level is available), and / or the GEO layer / cell (e.g., where the WTRU is paged).

[0193] The WTRU may be configured to monitor paging at multiple layers. Each paging may be associated with a different configuration, such as DRX cycle, paging occasion, etc. For example, the WTRU may be paged in both the NTN and the TN, where the indication in the paging is responded in the TN.

[0194] Systems, methods, and tools for paging and responding in different networks (such as a non-terrestrial network (NTN) to a terrestrial network (TN), a TN to an NTN, an NTN to another NTN, etc.) are described herein. For example, a wireless transmit / receive unit (WTRU) (e.g., camped in an idle or inactive state) may (e.g., be configured to) monitor for paging on a first network (e.g., NTN). The WTRU may receive a paging message on the NTN. The paging message may provide an indication to respond on a second network (e.g., TN). The WTRU may perform a cell reselection to the TN. The WTRU may respond to a paging on a first network (e.g., NTN) by transmitting a paging response message on a second network (e.g., TN).

[0195] Example A WTRU may receive a paging message from an NTN node. The paging message may indicate that the WTRU responds to the paging message, a first target TN cell, a second target TN cell, a first priority information associated with the first target TN cell, a second priority information associated with the second target TN cell, a first timing information associated with the first target TN cell, and a second timing information associated with the second target TN cell on the TN. The WTRU may select a TN cell from the first target TN cell and the second target TN cell based at least on the first priority information and the second priority information. The WTRU may apply the timing information associated with the selected TN cell. The WTRU may transmit an access request to the TN node associated with the selected TN cell to initiate a connection on the selected TN cell. The access request may indicate that the access request is triggered by the NTN node.

[0196] The selection of the TN cell from the first target TN cell and the second target TN cell may be further based on satisfaction of a condition. The condition may be satisfied if the paging message is scrambled with a radio network temporary identifier (RNTI) associated with the cell redirection. The paging message may include a service type indicator. The selection of the TN cell from the first target TN cell and the second target TN cell may be further based on the service type indicator.

[0197] The paging message may further indicate first uplink resources associated with the first target TN cell and second uplink resources associated with the second target TN cell.Transmitting the access request to the selected TN cell may involve transmitting the access request using uplink resources associated with the selected TN cell.

[0198] The first target TN cell may be associated with a first reference signal quality. The second target TN cell may be associated with a second reference signal quality. Selecting the TN cell from the first target TN cell and the second target TN cell may be further based on the first reference signal quality and the second reference signal quality.

[0199] The first target TN cell may be associated with a first frequency. The second target TN cell may be associated with a second frequency. Selecting the TN cell from the first target TN cell and the second target TN cell may be further based on a first difference between the first frequency and the target frequency and a second difference between the second frequency and the target frequency.

[0200] The WTRU may transmit a measurement report to the NTN node. The measurement report may indicate a request for first priority information associated with the first target TN cell and second priority information associated with the second target TN cell. The first priority information and the second priority information may be based on the measurement report.

[0201] After transmitting the access request, the WTRU may start a timer. In the event of a connection failure or no access response is received before the timer expires, the WTRU may transmit a response to the NTN node or monitor for subsequent paging messages from the NTN node.

[0202] Example A WTRU may identify one or more target TN cells. The WTRU may receive a paging message from an NTN node indicating: a TN cell in the one or more target TN cells, the WTRU responding to the paging message on the TN cell, and timing information associated with the TN cell. The WTRU may apply the timing information associated with the TN cell. The WTRU may transmit an access request to a TN node associated with the TN cell to initiate a connection on the TN cell. The access request may indicate that the access request is triggered by the NTN node.

[0203] Although the features and elements described above are described in particular combinations, each feature or element may be used alone without the other features and elements of the preferred embodiments, or in various combinations with or without the other features and elements.

[0204] Although the implementation described herein may consider 3GPP specific protocols, it should be understood that the implementation described herein is not limited to such scenarios and is applicable to other wireless systems. For example, although the solution described herein considers LTE, LTE-A, New Radio (NR) or 5G specific protocols, it should be understood that the solution described herein is not limited to such scenarios and is also applicable to other wireless systems.

[0205] The processes described above may be implemented in a computer program, software, and / or firmware incorporated in a computer-readable medium for execution by a computer and / or processor. Examples of computer-readable media include, but are not limited to, electronic signals (sent via wired and / or wireless connections) and / or computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (such as, but not limited to, built-in hard disks and removable disks), magneto-optical media, and / or optical media (such as compact disk (CD)-ROM disks and / or digital versatile disks (DVDs)). A processor associated with the software may be used to implement a radio frequency transceiver for a WTRU, a terminal, a base station, an RNC, and / or any host computer.

[0206] It should be understood that the entity that performs the processes described herein can be a logical entity that can be implemented in the form of software (e.g., computer executable instructions) that is stored in the memory of a mobile device, network node, or computer system and executed on its processor. That is, the process can be implemented in the form of software (e.g., computer executable instructions) stored in the memory of a mobile device and / or a network node (such as a node or a computer system) that performs the process in question when executed by the processor of the node. It should also be understood that any sending and receiving processes shown in the figure can be performed by the communication circuit of the node under the control of the processor of the node and the computer executable instructions (e.g., software) executed by it.

[0207] The various techniques described herein can be implemented in combination with hardware or software, or in a combination of the two where appropriate. Therefore, the specific implementation and device of the subject matter described herein or some aspects or parts thereof may take the form of program code (e.g., instructions), which is embodied in a tangible medium, which includes any other machine-readable storage medium, wherein when the program code is loaded into a machine (such as a computer) and executed by the machine, the machine becomes a device for practicing the subject matter described herein. In the case where the program code is stored on a medium, it is possible that the program code under consideration is stored on one or more media that jointly perform the action under consideration, that is, the one or more media together contain the code for performing the action, but in the case where there is more than one single medium, it is not required that any particular part of the code be stored on any particular medium. In the case of program code execution on a programmable device, the computing device generally includes a processor, a storage medium (including volatile and non-volatile memory and / or storage elements) readable by the processor, at least one input device, and at least one output device. One or more programs may implement or utilize the process described in conjunction with the subject matter described herein, for example, by using an API, a reusable control, etc. Such programs are preferably implemented in a high-level procedural or object-oriented programming language to communicate with a computer system. However, if desired, the program can be implemented in assembly or machine language. In any case, the language can be a compiled or interpreted language and combined with a hardware implementation.

[0208] Although example embodiments may involve utilizing aspects of the subject matter described herein in the context of one or more stand-alone computing systems, the subject matter described herein is not so limited, but may be implemented in conjunction with any computing environment, such as a network or distributed computing environment. Still further, aspects of the subject matter described herein may be implemented in or across multiple processing chips or devices, and storage may similarly be affected across multiple devices. Such devices may include personal computers, network servers, handheld devices, supercomputers, or computers integrated into other systems, such as automobiles and airplanes.

[0209] In describing the preferred embodiments of the subject matter of the present disclosure as shown in the accompanying drawings, specific terminology is employed for the sake of clarity. However, the claimed subject matter is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner to achieve a similar purpose.

Claims

1. A wireless transmit / receive unit (WTRU), the WTRU comprising: A processor, wherein the processor is configured to: receiving a paging message from a non-terrestrial network (NTN) node, the paging message indicating that the WTRU, on a terrestrial network (TN), responded to the paging message, a first target TN cell, a second target TN cell, first priority information associated with the first target TN cell, second priority information associated with the second target TN cell, first timing information associated with the first target TN cell, and second timing information associated with the second target TN cell; selecting a TN cell from among the first target TN cell and the second target TN cell based at least on the first priority information and the second priority information; applying timing information associated with the selected TN cell; as well as An access request is transmitted to a TN node associated with the selected TN cell to initiate a connection on the selected TN cell, wherein the access request indicates that the access request is triggered by the NTN node.

2. The WTRU of claim 1 , wherein the processor is configured to select the TN cell from the first target TN cell and the second target TN cell further based on satisfaction of a condition, and wherein the condition is satisfied if the paging message is scrambled with a radio network temporary identifier (RNTI) associated with cell redirection.

3. The WTRU of claim 1 , wherein the paging message further comprises a service type indicator, and wherein the processor is configured to select the TN cell from among the first target TN cell and the second target TN cell further based on the service type indicator.

4. A WTRU according to claim 1, wherein the paging message further indicates a first uplink resource associated with the first target TN cell and a second uplink resource associated with the second target TN cell, and wherein the processor is configured to transmit the access request to the selected TN cell includes the processor being configured to transmit the access request using the uplink resource associated with the selected TN cell.

5. The WTRU of claim 1 , wherein the first target TN cell is associated with a first frequency, wherein the second target TN cell is associated with a second frequency, and wherein the processor is configured to select the TN cell from the first target TN cell and the second target TN cell further based on a first difference between the first frequency and a target frequency and a second difference between the second frequency and the target frequency.

6. A WTRU according to claim 1, wherein the processor is further configured to transmit a measurement report to the NTN node, wherein the measurement report indicates a request for the first priority information associated with the first target TN cell and the second priority information associated with the second target TN cell, and wherein the first priority information and the second priority information are based on the measurement report.

7. A method performed by a wireless transmit / receive unit (WTRU), the method comprising: receiving a paging message from a non-terrestrial network (NTN) node, the paging message indicating that the WTRU, on a terrestrial network (TN), responded to the paging message, a first target TN cell, a second target TN cell, first priority information associated with the first target TN cell, second priority information associated with the second target TN cell, first timing information associated with the first target TN cell, and second timing information associated with the second target TN cell; selecting a TN cell from among the first target TN cell and the second target TN cell based at least on the first priority information and the second priority information; applying timing information associated with the selected TN cell; as well as An access request is transmitted to a TN node associated with the selected TN cell to initiate a connection on the selected TN cell, wherein the access request indicates that the access request is triggered by the NTN node.

8. The method of claim 7, wherein selecting the TN cell from among the first target TN cell and the second target TN cell is further based on satisfaction of a condition, and wherein the condition is satisfied if the paging message is scrambled with a radio network temporary identifier (RNTI) associated with cell redirection.

9. The method of claim 7, wherein the paging message further includes a service type indicator, and wherein selecting the TN cell from among the first target TN cell and the second target TN cell is further based on the service type indicator.

10. The method of claim 7, wherein the paging message further indicates a first uplink resource associated with the first target TN cell and a second uplink resource associated with the second target TN cell, and wherein transmitting the access request to the selected TN cell comprises transmitting the access request using the uplink resource associated with the selected TN cell.

11. The method of claim 7, wherein the first target TN cell is associated with a first frequency, wherein the second target TN cell is associated with a second frequency, and wherein selecting the TN cell from the first target TN cell and the second target TN cell is further based on a first difference between the first frequency and a target frequency and a second difference between the second frequency and the target frequency.

12. The method of claim 7, wherein the method further comprises transmitting a measurement report to the NTN node, wherein the measurement report indicates a request for the first priority information associated with the first target TN cell and the second priority information associated with the second target TN cell, and wherein the first priority information and the second priority information are based on the measurement report.

13. A wireless transmit / receive unit (WTRU), the WTRU comprising: A processor, wherein the processor is configured to: identifying one or more target terrestrial network (TN) cells; receiving a paging message from a non-terrestrial network (NTN) node, the paging message indicating: a TN cell of the one or more target TN cells, the WTRU responding to the paging message on the TN cell, and timing information associated with the TN cell; applying the timing information associated with the TN cell; as well as An access request is transmitted to a TN node associated with the TN cell to initiate a connection on the TN cell, wherein the access request indicates that the access request is triggered by the NTN node.

14. The WTRU of claim 13, wherein the processor is further configured to: After transmitting the access request, starting a timer; and If the connection fails or no access response is received before the timer expires: transmit a response to the NTN node, or Monitor for subsequent paging messages from the NTN node.

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