WO2026035630A1 - Reachability in a wireless communication network - Google Patents

Abstract

Disclosed herein are systems, methods, and instrumentalities associated with enhancing a wireless transmit/receive unit's (WTRU's) operations (e.g., reachability) in a wireless communication network (e.g., in a non-terrestrial network). A WTRU may include a processor. The WTRU may be configured to receive configuration information from a network device. The configuration information may be associated with a notification channel. The WTRU may determine that the WTRU is in a coverage limited area. The WTRU may, based at least on the determination that the WTRU is in the coverage limited area and/or an indication, received from the network device, that the WTRU monitor the notification channel, monitor the notification channel for a first message from the network device.

Description

I5GSYS 2024P00548WO PATENT

REACHABILITY IN A WIRELESS COMMUNICATION NETWORK

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63/679,520, filed August 5, 2024, the contents of which is incorporated by reference herein.

BACKGROUND

[0002] Development of non-terrestrial networks (NTNs) may introduce challenges such as continuous timing advance (TA) drift, large cell sizes, and extended round trip times (RTT). Systems and methods for improving wireless transmit/receive unit (WTRU) operations within an NTN (e g., in coverage limited scenarios) may be desirable.

SUMMARY

[0003] Systems, methods, and instrumentalities are described herein related to reachability in a wireless communication network. An example device may include a processor. For example, a device (e.g., a wireless transmit/receive unit (WTRU)) may be configured to perform one or more of the following.

[0004] The device may receive configuration information from a network device. The configuration information may be associated with a notification channel. The device may determine that the device is in a coverage limited area. The device may, based at least on the determination that the device is in the coverage limited area and/or an indication, received from the network device, that the device monitor the notification channel, monitor the notification channel for a first message from the network device.

[0005] The device may send a second message to the network device that indicates a preference of the device to receive the first message from the network device via the notification channel. The device may receive a response from the network device associated with the preference. The response may include the indication that the device monitor the notification channel.

[0006] The device may indicate, in the second message, a time period for monitoring the notification channel or send a third message to the network device that indicates the time period for monitoring the notification channel. The device may indicate, in the second message, network parameters for monitoring the notification channel or send a third message to the network device that indicates the I5GSYS 2024P00548WO PATENT network parameters for monitoring the notification channel. The determination that the device is in the coverage limited area may be based on a determination that a signal strength is below a threshold. The threshold may be indicated in the configuration information. The device may monitor the notification channel for the first message from the network device further based on a determination that a time period has not expired. The time period may be indicated in the configuration information. The device may monitor the notification channel for the first message from the network device further based on a determination that a signal strength of a paging channel is below a threshold or based on a determination that a number of reference signals has been detected within a time period.

[0007] The second message to the network device may indicate that the device is monitoring the notification channel for the first message from the network device. The configuration information may indicate a first configuration associated with a sequenced-based notification configuration and/or a second configuration associated with a Physical Downlink Control Channel (PDCCH)-based notification configuration.

[0008] Disclosed herein are systems, methods, and instrumentalities associated with enhancing a WTRU’s operations (e.g., reachability) in a wireless communication network (e.g., an NTN). According to embodiments of the disclosure, the WTRU may receive configuration information from a network device regarding a notification channel. The WTRU may determine that it is in a coverage limited area of the network and, based on such a determination and an indication for the WTRU to monitor the notification channel while in the coverage limited area, the WTRU may monitor the notification channel for a first message from the network device.

[0009] In examples, the notification channel is different than a paging channel and the WTRU may be further configured to send a second message to the network regarding a preference to receive the message from the network device via the notification channel (e.g., rather than the paging channel). The WTRU may receive a response from the network device regarding the preference, and the response may include the indication (e.g., an approval) for the WTRU to monitor the notification channel while in the coverage limited area.

[0010] In examples, the WTRU may send an indication (e.g., in the second message described above or in a third message) to the network device regarding a time period for monitoring the notification channel. In examples, the coverage limited area may be served by an NTN. In examples, the WTRU may operate in an RRC IDLE state or an RRC INACTIVE state when monitoring for the message from the network device. I5GSYS 2024P00548WO PATENT

[0011] In examples, the WTRU may further receive the first message from the network device via the notification channel. Subsequent to receiving the first message, the WTRU may monitor for a paging message or initiate a random access procedure with the network device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1A is a system diagram illustrating an example communications system in which one or more disclosed embodiments can be implemented.

[0013] FIG. IB is a system diagram illustrating an example wireless transmit/receive unit (WTRU) that can be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0014] FIG. 1C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that can be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0015] FIG. ID is a system diagram illustrating a further example RAN and a further example CN that can be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0016] FIG. 2 is a diagram illustrating an example of integrating a notification/alert channel and/or a cooperative user into a communication network.

[0017] FIG. 3 is a diagram illustrating an example of predicting limited DL coverage.

[0018] FIG. 4 is a diagram illustrating an example of indicating a WTRU preference for how the WTRU may be reached.

[0019] FIG. 5 is a diagram illustrating an example of a WTRU transitioning between monitoring via a paging channel and monitoring a notification/alert channel.

DETAILED DESCRIPTION

[0020] A more detailed understanding can be had from the following description, given by way of example in conjunction with the accompanying drawings.

[0021] FIG. 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments can be implemented. The communications system 100 can be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 can enable multiple wireless users to access such I5GSYS 2024P00548WO PATENT content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 can employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block- filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0022] As shown in FIG. 1A, the communications system 100 can include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, a RAN 104/113, a CN 106/115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements. Each of the WTRUs 102a, 102b, 102c, 102d can be any type of device configured to operate and/or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which can be referred to as a “station” and/or a “STA”, can be configured to transmit and/or receive wireless signals and can include a user equipment (WTRU), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot orMi-Fi device, an Internet of Things (loT) device, awatch or other wearable, ahead-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d can be interchangeably referred to as a WTRU.

[0023] The communications systems 100 can include a base station 114a and/or abase station 114b. Each of the base stations 114a, 114b can be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106/115, the Internet 110, and/or the other networks 112. By way of example, the base stations 114a, 114b can be a base transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B, a base station, a NR NodeB, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b can include any number of interconnected base stations and/or network elements. I5GSYS 2024P00548WO PATENT

[0024] The base station 114a can be part of the RAN 104/113, which can also include other base stations and/or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and/or the base station 114b can be configured to transmit and/or receive wireless signals on one or more carrier frequencies, which can be referred to as a cell (not shown). These frequencies can be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell can provide coverage for a wireless service to a specific geographical area that can be relatively fixed or that can change over time. The cell can further be divided into cell sectors. For example, the cell associated with the base station 114a can be divided into three sectors. Thus, in one embodiment, the base station 114a can include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station 114a can employ multiple-input multiple output (MIMO) technology and can utilize multiple transceivers for each sector of the cell. For example, beamforming can be used to transmit and/or receive signals in desired spatial directions.

[0025] The base stations 114a, 114b can communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which can be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 can be established using any suitable radio access technology (RAT).

[0026] More specifically, as noted above, the communications system 100 can be a multiple access system and can employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104/113 and the WTRUs 102a, 102b, 102c can implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which can establish the air interface 115/116/117 using wideband CDMA (WCDMA). WCDMA can include communication protocols such as High-Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA can include High-Speed Downlink (DL) Packet Access (HSDPA) and/or High-Speed UL Packet Access (HSUPA).

[0027] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which can establish the air interface 116 using Long Term Evolution (LTE) and/or LTE- Advanced (LTE-A) and/or LTE- Advanced Pro (LTE-A Pro). I5GSYS 2024P00548WO PATENT

[0028] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can implement a radio technology such as NR Radio Access, which can establish the air interface 116 using New Radio (NR).

[0029] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c can implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles. Thus, the air interface utilized by WTRUs 102a, 102b, 102c can be characterized by multiple types of radio access technologies and/or transmissions sent to/from multiple types of base stations (e.g., a eNB and a base station).

[0030] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c can implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 IX, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

[0031] The base station 114b in FIG. 1A can be a wireless router, Home Node B, Home eNode B, or access point, for example, and can utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d can implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d can implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d can utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. As shown in FIG. 1A, the base station 114b can have a direct connection to the Internet 110. Thus, the base station 114b can not be required to access the Internet 110 via the CN 106/115.

[0032] The RAN 104/113 can be in communication with the CN 106/115, which can be any type of network configured to provide voice, data, applications, and/or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data can have varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error I5GSYS 2024P00548WO PATENT tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106/115 can provide call control, billing services, mobile location- based services, pre-paid calling, Internet connectivity, video distribution, etc., and/or perform high- level security functions, such as user authentication. Although not shown in FIG. 1A, it will be appreciated that the RAN 104/113 and/or the CN 106/115 can be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104/113 or a different RAT. For example, in addition to being connected to the RAN 104/113, which can be utilizing a NR radio technology, the CN 106/115 can also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0033] The CN 106/115 can also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and/or the other networks 112. The PSTN 108 can include circuit-switched telephone networks that provide plain old telephone service (POTS). The Internet 110 can include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP) and/or the internet protocol (IP) in the TCP/IP internet protocol suite. The networks 112 can include wired and/or wireless communications networks owned and/or operated by other service providers. For example, the networks 112 can include another CN connected to one or more RANs, which can employ the same RAT as the RAN 104/113 or a different RAT.

[0034] One or more (e.g., all) of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 can include multi-mode capabilities (e g., the WTRUs 102a, 102b, 102c, 102d can include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1A can be configured to communicate with the base station 114a, which can employ a cellular-based radio technology, and with the base station 114b, which can employ an IEEE 802 radio technology.

[0035] FIG. IB is a system diagram illustrating an example WTRU 102. As shown in FIG. IB, the WTRU 102 can include a processor 118, a transceiver 120, a transmit/receive element 122, a speaker/microphone 124, a keypad 126, a display/touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and/or other peripherals 138, among others. It will be appreciated that the WTRU 102 can include any subcombination of the foregoing elements while remaining consistent with an embodiment. I5GSYS 2024P00548WO PATENT

[0036] The processor 118 can be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 can perform signal coding, data processing, power control, input/output processing, and/or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 can be coupled to the transceiver 120, which can be coupled to the transmit/receive element 122. While FIG. IB depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 can be integrated together in an electronic package or chip.

[0037] The transmit/receive element 122 can be configured to transmit signals to, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, the transmit/receive element 122 can be an antenna configured to transmit and/or receive RF signals. In an embodiment, the transmit/receive element 122 can be an emitter/detector configured to transmit and/or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit/receive element 122 can be configured to transmit and/or receive both RF and light signals. It will be appreciated that the transmit/receive element 122 can be configured to transmit and/or receive any combination of wireless signals.

[0038] Although the transmit/receive element 122 is depicted in FIG. IB as a single element, the WTRU 102 can include any number of transmit/receive elements 122. More specifically, the WTRU 102 can employ MIMO technology. Thus, in one embodiment, the WTRU 102 can include two or more transmit/receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0039] The transceiver 120 can be configured to modulate the signals that are to be transmitted by the transmit/receive element 122 and to demodulate the signals that are received by the transmit/receive element 122. As noted above, the WTRU 102 can have multi-mode capabilities. Thus, the transceiver 120 can include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11, for example.

[0040] The processor 118 of the WTRU 102 can be coupled to, and can receive user input data from, the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128 (e.g., a liquid crystal display (LCD) display unit or organic light-emitting diode (OLED) display unit). The I5GSYS 2024P00548WO PATENT processor 118 can also output user data to the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128. In addition, the processor 118 can access information from, and store data in, any type of suitable memory, such as the non-removable memory 130 and/or the removable memory 132. The non-removable memory 130 can include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 can include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 can access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0041] The processor 118 can receive power from the power source 134, and can be configured to distribute and/or control the power to the other components in the WTRU 102. The power source 134 can be any suitable device for powering the WTRU 102. For example, the power source 134 can include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like.

[0042] The processor 118 can also be coupled to the GPS chipset 136, which can be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to, or in lieu of, the information from the GPS chipset 136, the WTRU 102 can receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and/or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 can acquire location information by way of any suitable location-determination method while remaining consistent with an embodiment. [0043] The processor 118 can further be coupled to other peripherals 138, which can include one or more software and/or hardware modules that provide additional features, functionality and/or wired or wireless connectivity. For example, the peripherals 138 can include an accelerometer, an e- compass, a satellite transceiver, a digital camera (for photographs and/or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a Virtual Reality and/or Augmented Reality (VR/AR) device, an activity tracker, and the like. The peripherals 138 can include one or more sensors, the sensors can be one or more of a gyroscope, an accelerometer, a hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light I5GSYS 2024P00548WO PATENT sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and/or a humidity sensor.

[0044] The WTRU 102 can include a full duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for both the UL (e.g., for transmission) and downlink (e.g., for reception) can be concurrent and/or simultaneous. The full duplex radio can include an interference management unit to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WTRU 102 can include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e.g., for transmission) or the downlink (e.g., for reception)).

[0045] FIG. 1C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As noted above, the RAN 104 can employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 can also be in communication with the CN 106.

[0046] The RAN 104 can include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 can include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c can each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c can implement MIMO technology. Thus, the eNode-B 160a, for example, can use multiple antennas to transmit wireless signals to, and/or receive wireless signals from, the WTRU 102a.

[0047] Each of the eNode-Bs 160a, 160b, 160c can be associated with a particular cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and/or DL, and the like. As shown in FIG. 1C, the eNode-Bs 160a, 160b, 160c can communicate with one another over an X2 interface.

[0048] The CN 106 shown in FIG. 1C can include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements are depicted as part of the CN 106, it will be appreciated that any of these elements can be owned and/or operated by an entity other than the CN operator.

[0049] The MME 162 can be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an SI interface and can serve as a control node. For example, the MME 162 can be responsible I5GSYS 2024P00548WO PATENT for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation/deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 162 can provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and/or WCDMA.

[0050] The SGW 164 can be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via the SI interface. The SGW 164 can generally route and forward user data packets to/from the WTRUs 102a, 102b, 102c. The SGW 164 can perform other functions, such as anchoring user planes during inter-eNode B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0051] The SGW 164 can be connected to the PGW 166, which can provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0052] The CN 106 can facilitate communications with other networks. For example, the CN 106 can provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 can include, or can communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 can provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which can include other wired and/or wireless networks that are owned and/or operated by other service providers.

[0053] Although the WTRU is described in FIGS. 1 A-1D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal can use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

[0054] In representative embodiments, the other network 112 can be a WLAN.

[0055] A WLAN in Infrastructure Basic Service Set (BSS) mode can have an Access Point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP can have an access or an interface to a Distribution System (DS) or another type of wired/wireless network that carries traffic in to and/or out of the BSS. Traffic to STAs that originates from outside the BSS can arrive through the AP and can be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS can be sent to the AP to be delivered to respective destinations. Traffic between STAs within the I5GSYS 2024P00548WO PATENT

BSS can be sent through the AP, for example, where the source STA can send traffic to the AP and the AP can deliver the traffic to the destination STA. The traffic between STAs within a BSS can be considered and/or referred to as peer-to-peer traffic. The peer-to-peer traffic can be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS can use an 802. l ie DLS or an 802.1 Iz tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode can not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS can communicate directly with each other. The IBSS mode of communication can sometimes be referred to herein as an “ad-hoc” mode of communication.

[0056] When using the 802.1 lac infrastructure mode of operation or a similar mode of operations, the AP can transmit a beacon on a fixed channel, such as a primary channel. The primary channel can be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling. The primary channel can be the operating channel of the BSS and can be used by the STAs to establish a connection with the AP. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) can be implemented, for example in in 802.11 systems. For CSMA/CA, the STAs (e.g., every STA), including the AP, can sense the primary channel. If the primary channel is sensed/detected and/or determined to be busy by a particular STA, the particular STA can back off. One STA (e.g., only one station) can transmit at any given time in a given BSS.

[0057] High Throughput (HT) STAs can use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadj acent 20 MHz channel to form a 40 MHz wide channel.

[0058] Very High Throughput (VHT) STAs can support 20MHz, 40 MHz, 80 MHz, and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz, channels can be formed by combining contiguous 20 MHz channels. A 160 MHz channel can be formed by combining 8 contiguous 20 MHz channels, or by combining two non-contiguous 80 MHz channels, which can be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, can be passed through a segment parser that can divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing, and time domain processing, can be done on each stream separately. The streams can be mapped on to the two 80 MHz channels, and the data can be transmitted by a transmitting STA. At the receiver of the receiving STA, the above described operation for the 80+80 configuration can be reversed, and the combined data can be sent to the Medium Access Control (MAC). I5GSYS 2024P00548WO PATENT

[0059] Sub 1 GHz modes of operation are supported by 802.1 laf and 802.11 ah. The channel operating bandwidths, and carriers, are reduced in 802.11af and 802.11ah relative to those used in 802.1 In, and 802.1 lac. 802.1 laf supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.1 lah can support Meter Type Control/Machine-Type Communications, such as MTC devices in a macro coverage area. MTC devices can have certain capabilities, for example, limited capabilities including support for (e.g., only support for) certain and/or limited bandwidths. The MTC devices can include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0060] WLAN systems, which can support multiple channels, and channel bandwidths, such as 802.1 In, 802.1 lac, 802.1 laf, and 802.1 lah, include a channel which can be designated as the primary channel. The primary channel can have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel can be set and/or limited by a STA, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In the example of 802.1 lah, the primary channel can be 1 MHz wide for STAs (e.g., MTC type devices) that support (e.g., only support) a 1 MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and/or other channel bandwidth operating modes. Carrier sensing and/or Network Allocation Vector (NAV) settings can depend on the status of the primary channel. If the primary channel is busy, for example, due to a STA (which supports only a 1 MHz operating mode), transmitting to the AP, the entire available frequency bands can be considered busy even though a majority of the frequency bands remains idle and can be available.

[0061] In the United States, the available frequency bands, which can be used by 802.1 lah, are from 902 MHz to 928 MHz. In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.1 lah is 6 MHz to 26 MHz depending on the country code.

[0062] FIG. ID is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As noted above, the RAN 113 can employ an NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 can also be in communication with the CN 115.

[0063] The RAN 113 can include base stations 180a, 180b, 180c, though it will be appreciated that the RAN 113 can include any number of base stations while remaining consistent with an I5GSYS 2024P00548WO PATENT embodiment. The base stations 180a, 180b, 180c can each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the base stations 180a, 180b, 180c can implement MIMO technology. For example, base stations 180a, 108b can utilize beamforming to transmit signals to and/or receive signals from the base stations 180a, 180b, 180c. Thus, the base station 180a, for example, can use multiple antennas to transmit wireless signals to, and/or receive wireless signals from, the WTRU 102a. In an embodiment, the base stations 180a, 180b, 180c can implement carrier aggregation technology. For example, the base station 180a can transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers can be on unlicensed spectrum while the remaining component carriers can be on licensed spectrum. In an embodiment, the base stations 180a, 180b, 180c can implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a can receive coordinated transmissions from base station 180a and base station 180b (and/or base station 180c).

[0064] The WTRUs 102a, 102b, 102c can communicate with base stations 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, the OFDM symbol spacing and/or OFDM subcarrier spacing can vary for different transmissions, different cells, and/or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c can communicate with base stations 180a, 180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing varying number of OFDM symbols and/or lasting varying lengths of absolute time).

[0065] The base stations 180a, 180b, 180c can be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and/or a non-standalone configuration. In the standalone configuration, WTRUs 102a, 102b, 102c can communicate with base stations 180a, 180b, 180c without also accessing other RANs (e.g., such as eNode-Bs 160a, 160b, 160c). In the standalone configuration, WTRUs 102a, 102b, 102c can utilize one or more of base stations 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c can communicate with base stations 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration WTRUs 102a, 102b, 102c can communicate with/connect to base stations 180a, 180b, 180c while also communicating with/connecting to another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b, 102c can implement DC principles to communicate with one or more base stations 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non-standalone configuration, eNode-Bs 160a, 160b, 160c can serve as a I5GSYS 2024P00548WO PATENT mobility anchor for WTRUs 102a, 102b, 102c and base stations 180a, 180b, 180c can provide additional coverage and/or throughput for servicing WTRUs 102a, 102b, 102c.

[0066] Each of the base stations 180a, 180b, 180c can be associated with a particular cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and/or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards User Plane Function (UPF) 184a, 184b, routing of control plane information towards Access and Mobility Management Function (AMF) 182a, 182b and the like. As shown in FIG. ID, the base stations 180a, 180b, 180c can communicate with one another over an Xn interface.

[0067] The CN 115 shown in FIG. ID can include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the foregoing elements are depicted as part of the CN 115, it will be appreciated that any of these elements can be owned and/or operated by an entity other than the CN operator.

[0068] The AMF 182a, 182b can be connected to one or more of the base stations 180a, 180b, 180c in the RAN 113 via an N2 interface and can serve as a control node. For example, the AMF 182a, 182b can be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e g., handling of different PDU sessions with different requirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of NAS signaling, mobility management, and the like. Network slicing can be used by the AMF 182a, 182b in order to customize CN support for WTRUs 102a, 102b, 102c based on the types of services being utilized WTRUs 102a, 102b, 102c. For example, different network slices can be established for different use cases such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, and/or the like. The AMF 162 can provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and/or non-3GPP access technologies such as WiFi.

[0069] The SMF 183a, 183b can be connected to an AMF 182a, 182b in the CN 115 via an Ni l interface. The SMF 183a, 183b can also be connected to a UPF 184a, 184b in the CN 115 via an N4 interface. The SMF 183a, 183b can select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b can perform other functions, such as I5GSYS 2024P00548WO PATENT managing and allocating WTRU IP address, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, and the like. A PDU session type can be IP -based, non-IP based, Ethernet-based, and the like.

[0070] The UPF 184a, 184b can be connected to one or more of the base stations 180a, 180b, 180c in the RAN 113 via an N3 interface, which can provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b can perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, and the like.

[0071] The CN 115 can facilitate communications with other networks. For example, the CN 115 can include, or can communicate with, an IP gateway (e g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 can provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which can include other wired and/or wireless networks that are owned and/or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c can be connected to a local Data Network (DN) 185a, 185b through the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0072] In view of Figures 1 A-1D, and the corresponding description of Figures 1 A-1D, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b, eNode-B 160a-c, MME 162, SGW 164, PGW 166, base station 180a-c, AMF 182a-b, UPF 184a-b, SMF 183a-b, DN 185a-b, and/or any other device(s) described herein, can be performed by one or more emulation devices (not shown). The emulation devices can be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices can be used to test other devices and/or to simulate network and/or WTRU functions.

[0073] The emulation devices can be designed to implement one or more tests of other devices in a lab environment and/or in an operator network environment. For example, the one or more emulation devices can perform the one or more, or all, functions while being fully or partially implemented and/or deployed as part of a wired and/or wireless communication network in order to test other devices within the communication network. The one or more emulation devices can perform the one or more, or all, functions while being temporarily implemented/deployed as part of a wired and/or I5GSYS 2024P00548WO PATENT wireless communication network. The emulation device can be directly coupled to another device for purposes of testing and/or can perform testing using over-the-air wireless communications.

[0074] The one or more emulation devices can perform the one or more, including all, functions while not being implemented/deployed as part of a wired and/or wireless communication network. For example, the emulation devices can be utilized in a testing scenario in a testing laboratory and/or a non-deployed (e.g., testing) wired and/or wireless communication network in order to implement testing of one or more components. The one or more emulation devices can be test equipment. Direct RF coupling and/or wireless communications via RF circuitry (e.g., which can include one or more antennas) can be used by the emulation devices to transmit and/or receive data.

[0075] Systems, methods, and instrumentalities are described herein related to reachability in a wireless communication network. An example device may include a processor. For example, a device (e.g., a WTRU) may be configured to perform one or more of the following.

[0076] The device may receive configuration information from a network device. The configuration information may be associated with a notification channel. The device may determine that the device is in a coverage limited area. The device may, based at least on the determination that the device is in the coverage limited area and/or an indication, received from the network device, monitor the notification channel for a first message from the network device.

[0077] The device may send a second message to the network device that indicates a preference of the device to receive the first message from the network device via the notification channel. The device may receive a response from the network device associated with the preference. The response may include the indication that the device monitor the notification channel while in the coverage limited area.

[0078] The device may indicate, in the second message, a time period for monitoring the notification channel or send a third message to the network device that indicates the time period for monitoring the notification channel. The device may indicate, in the second message, network parameters for monitoring the notification channel or send a third message to the network device that indicates the network parameters for monitoring the notification channel. The determination that the device is in the coverage limited area may be based on a determination that a signal strength is below a threshold. The threshold may be indicated in the configuration information. The device may monitor the notification channel for the first message from the network device further based on a determination I5GSYS 2024P00548WO PATENT that a time period has not expired. The time period may be indicated in the configuration information. The device may monitor the notification channel for the first message from the network device further based on a determination that a signal strength of a paging channel is below a threshold or based on a determination that a number of reference signals has been detected within a time period.

[0079] The second message to the network device may indicate that the device is monitoring the notification channel for the first message from the network device. The configuration information may indicate a first configuration associated with a sequenced-based notification configuration and/or a second configuration associated with a Physical Downlink Control Channel (PDCCH)-based notification configuration.

[0080] A non-terrestrial network (NTN) may include an aerial or space-borne platform. The aerial or space-borne platform may be used to transport signals between a land-based network device (e.g., a base station such as a gNB) and a WTRU via a gateway (GW). The aerial or space-borne platform may be classified in terms of orbits. For example, non-geosynchronous orbit (NGSO) satellites may be associated with a low-earth orbit (LEO) (e.g., with an altitude range of 300-1500km) while medium-earth orbit (MEO) satellites have an altitude range from 7000km to 25000km. The NGSO satellites may move continuously relative to the earth, while geosynchronous orbit (GSO) satellites may remain fixed relative to the early by maintaining an altitude of, for example, 35,786km.

[0081] Satellite platforms may be further classified as having a “transparent” payload or a “regenerative” payload. The platforms having a transparent satellite payload may implement frequency conversion and RF amplification in a uplink and/or a downlink, with multiple transparent satellites connected to one land-based gNB. The platforms having a regenerative satellite payload may implement a full random access network (e.g., a base station such as a gNB) or a nodeB distributed unit (DU) onboard the satellite. The platforms having a regenerative payload may perform digital processing on a signal such as, e.g., demodulation, decoding, re-encoding, re-modulation and/or filtering.

[0082] An NTN satellite may support multiple cells, where a (e.g., each) cell may include one or more satellite beams. The satellite beams may cover a footprint on the earth (e.g., a terrestrial cell), which may range in diameters from lOO-lOOOkm in NGSO deployments or 200-3500km in GSO deployments. Beam footprints in GSO deployments may remain fixed relative to the earth. In NGSO deployments, the area covered by a beam/cell may change over time due to satellite movement. This beam movement may be classified as “earth moving” if the beam moves continuously across the earth. I5GSYS 2024P00548WO PATENT

The beam movement may be classified as “earth fixed” if the beam is steered to maintain coverage of a fixed location (e.g., until a new cell overtakes the coverage area in a discrete and coordinated change).

[0083] The challenges of a non-terrestrial network may include continuous movements of NGSO satellites overhead, resulting in frequent and/or continuous timing advance (TA) drifts, cell sizes up to 3500km in diameter, and round trip times (RTT) several orders of magnitude larger than that of a terrestrial network (e.g., which may be up to 541.46ms).

[0084] Downlink (DL) coverage enhancements may accommodate satellite payload constraints (e.g., the DL may be unable to have all its beams active with a certain equivalent isotropic radiated power (EIRP) density per beam at a given time due to limited power and limited feeder link bandwidth. The DL coverage enhancements may maximize the number of beams that may be activated simultaneously and may ensure that (e.g., all) user terminals may be served across a satellite foot print. Such DL enhancement may also maximize the overall satellite throughput and/or ensure that all satellites’ radio cells be kept alive (e.g., even without traffic), thus allowing users to join and/or preventing negative impacts on end-user QoS. The DL enhancements may be implemented at a link level to improve a link margin of selected physical channels to accommodate EIRP reductions in frequency range 1 for a non-terrestrial network (FR1-NTN). A link margin improvement for physical channels (e.g., PDSCH and/or PDCCH) may be considered without impact on synchronization signal block (SSB) designs (e.g., apart from extended periodicity). The DL enhancements may be implemented at a system level to support efficient, dynamic and flexible power sharing between beams or different beam pattems/sizes (e.g., wide or narrow) across the satellite foot print for a FR1- NTN and/or a frequency range 2 for a non-terrestrial network (FR2-NTN).

[0085] Some NTN DL coverage enhancements may focus on improving line-of-sight (LOS) WTRUs that may experience poor DL coverage (e.g., due to EIRP density reduction that may be caused by satellite power sharing). There may be, however, other issues that may affect non-line-of- sight (NLOS) WTRUs (e.g., approximately 10% of rural WTRUs) such as, for example, clutter losses that may result in coverage drops (e.g., a drop of 18dB). Such drops may impact a WTRU’s ability to receive DL signaling (e.g., paging messages).

[0086] In an NTN, user actions (e.g., taking a phone outside of a briefcase or moving outdoors) may improve the coverage conditions of a WTRU. These actions may be referred to as “user cooperation.” To prompt such user cooperation, a notification or alert may be sent to a WTRU (e.g., on a heavily I5GSYS 2024P00548WO PATENT coverage enhanced channel) to trigger user actions (e.g., receive paging via a traditional paging channel) that may help improve channel conditions. Having the ability to reach a coverage limited (e.g., in the DL) WTRU may allow a network to transmit emergency signaling and/or alerts to the WTRU, which may have no alternative form of connection.

[0087] FIG. 2 illustrates an example of integrating a notification/alert channel and a cooperative user into a paging framework. To support the integration of the notification/alert channel (e.g., for an NTN) into the paging framework, one or more of the following aspects may be addressed. These aspects may include identifying satellite parameters (e.g., revised satellite parameters) to represent a power sharing case, and using the parameters to simulate and/or determine a channel or a revised target link margin. These aspects may include defining a notification channel associated with receiving paging in coverage limited scenarios, and/or defining a cooperative user. The examples provided herein may illustrate ways to define such a notification channel and demonstrate the systemlevel impact of integrating the notification channel into a communication network.

[0088] As mentioned above, a conventional wireless communication network such as an NTN may not have a notification channel and therefore, if a WTRU is not reachable, a paging escalation may be triggered (e g., a paging message may be sent out to increasingly larger areas), leading to large signaling overhead. Incorporating a notification or alert channel into such a network (e.g., into a paging framework used by the network) may improve the network coverage (e.g., DL coverage in an NTN) for heavily coverage-limited WTRUs.

[0089] According to embodiments of the present disclosure, a WTRU may receive configuration information associated with a notification channel (e.g., the configuration information may indicate one or more of monitoring cycle(s), monitoring occasion(s), radio network identified s) (RNTI), etc. associated with the notification channel). The WTRU may (e.g., prior to entering an RRC IDLE or RRC INACTIVE state) indicate a preference (e.g., to a network) regarding which future periods the WTRU may monitor the notification channel (e.g., based on DL coverage information). In a message (e.g., a release message), the network may indicate that the preference is approved, that the preference is rejected and the WTRU should monitor a paging channel, or that the preference is rejected and the WTRU should monitor a notification channel. The WTRU may monitor one or more channels according to the network indication (e.g., in the IDLE or INACTIVE state).

[0090] A WTRU may perform one or more of the following actions. I5GSYS 2024P00548WO PATENT

[0091] The WTRU may receive a notification channel configuration (e.g., the WTRU may receive configuration information associated with a notification channel as described herein). The notification channel configuration may include a set of occasions (e.g., network parameters) for monitoring the notification channel (e.g., time/frequency occasions, cycles, etc., similar to those of a paging channel). The notification channel configuration may indicate the characteristics of a notification alert (e.g., sequence-based or PDCCH-based). The notification channel configuration may include dedicated RNTIs that may be associated with the monitoring of the notification channel (e.g., if the notification channel is PDCCH based).

[0092] The WTRU may receive a request for assistance information (e.g., via a UEInformationRequest request). For example, the WTRU may receive a request for its preference on where the WTRU may be reached (e.g., on a paging channel or a notification channel) once released from an RRC Connected state (e.g., upon reception of an RRCRelease message).

[0093] The WTRU may determine a time period for monitoring the notification channel. For example, the determination may be made based on areas of poor DL coverage (e.g., the WTRU being in a coverage limited area), which may be calculated based on WTRU location and/or assistance/coverage information from a network (e.g., the outer 10% of the cell coverage area may result in poor DL coverage). The determination may be made based on historical measurement information (e.g., the WTRU’s measurements indicate a degrade X km from a cell edge, the WTRU is normally indoors from 9pm to 7am, etc.).

[0094] The WTRU may report the time period(s) in which the WTRU may monitor the notification channel. The WTRU may report its preference for being paged via the notification channel during those time periods. The WTRU may report (e.g., indicate) both information (e.g., the time period(s) and the preference) in the same message or in separate messages.

[0095] The network may (e.g., upon releasing a WTRU from the RRC Connected state via an RRCRelease or RRCReleasewithSuspend message) approve a WTRU preference, reject the WTRU preference and notify the WTRU to monitor a paging channel, or reject the WTRU preference and notify the WTRU to monitor a notification channel.

[0096] If the WTRU preference is approved, the WTRU may monitor the notification channel or the paging channel (e.g., according to configuration information received by the WTRU) during the I5GSYS 2024P00548WO PATENT reported periods. If the WTRU preference is rejected, the WTRU may monitor the channel (e.g., the notification channel or the paging channel) indicated in the RRCRelease message.

[0097] By reporting when the WTRU monitors the notification channel, WTRU-to-network synchronization may be improved and the chance of the WTRU remaining reachable at times of poor DL coverage may be increased. The reporting may reduce signaling overhead by reducing paging escalation. The reporting may lead to power saving (e.g., by avoiding unnecessary monitoring of the paging channel on which no signaling may be received).

[0098] When used herein, a notification or alert channel may refer to a channel used in downlink coverage-limited areas where a WTRU may not be able to receive paging or detect an SSB via normal means. The terms “notification channel”, “notification/alert channel,” or “alert channel” may be used interchangeably throughout this disclosure.

[0099] When used herein, a notification or alert may refer to a message received or transmitted by the WTRU over a notification channel. For example, the notification or alert may be used to notify a user that coverage under current conditions is too poor to receive/transmit data over a channel, and/or to prompt the user to improve channel conditions (e.g., via user actions). The terms “notification”, “notification/alert” and “alert” may be used interchangeably within this disclosure.

[0100] When used herein, a cooperative user may refer to a WTRU in a poor coverage condition that may be improved for the WTRU to resume and/or have a likelihood of successfully performing operations (e.g., paging and/or random access channel (RACH) operations). The coverage condition may be improved by user actions (e.g., taking a phone out of a bag) in response to the reception of a notification/alert.

[0101] When used herein, a non-cooperative user may refer to a WTRU in a poor coverage condition that may not be improved for the WTRU to resume and/or have a likelihood of successfully performing operations (e.g., paging and/or RACH operations).

[0102] The examples described herein may refer to a NTN, but the techniques disclosed in these examples may also apply to other networks (e.g., terrestrial networks, aerial networks, etc.).

[0103] A notification channel may refer to any type of channel (e.g., new or existing, PDCCH-based or sequence based, repetition-based, etc.) used to support coverage limited WTRUs. In examples, the notification (or alert) channel may support a downlink or both a downlink and an uplink. In examples, different notification channels may be used for the uplink and the downlink. A notification/alert may I5GSYS 2024P00548WO PATENT refer to a specific message or any message received by a WTRU over a notification/alert channel. A notification may be received over a non-notification channel (e.g., a legacy channel) and may be distinguished from other messages.

[0104] Terms such as “channel quality” or “cell quality” may describe a metric used to evaluate the strength of a radio quality of a WTRU connection. The radio quality of the WTRU connection may be based on LI measurements (e.g., SSB/CSI-RS), filtered L3 measurements (e.g., reference signal received power (RSRP)/ reference signal received quality (RSRQ)), or any other measurement or cell quality metric.

[0105] Support of a notification/alert channel may improve a WTRU operation in heavily coverage limited scenarios. For example, WTRU-NW synchronization may be improved, increasing the chance that the WTRU may remain reachable at times of poor coverage (e.g., when the WTRU is in a coverage limited area). As another example, WTRU signaling overhead due to repeated RACH failures may be reduced. As another example, network signaling overhead due to a lowered probability of paging escalation may be reduced. As another example, a WTRU power saving may be increased by avoiding unnecessary monitoring of a paging channel over which signaling may not be received. As another example, a WTRU may provide or be provided with information and/or configurations to support a DL notification channel (e.g., a notification channel) in a non-terrestrial network.

[0106] Configurations for DL notification channel may be specific to a serving cell and/or satellite, or may be provided for one or more neighboring cells/satellites. Configurations or one or more components of a DL notification channel may be common to multiple WTRUs reachable by broadcast signaling, may be dedicated to a WTRU, or may be specific to a group of WTRUs. The configurations or one or more components of a configuration for DL notification channel may apply currently or at a specified time or time period in the future. Information described herein may be indicated explicitly (e.g., via system information (SI)), provided via one or more configurations (e.g., via a DL notification channel configuration), and/or interpreted implicitly (e.g., via other information such as satellite assistance information contained within a ntnConfig message).

[0107] The techniques described herein may support an exchange of required/relevant information between a WTRU and a network to support DL notification channel, ensuring that the information is acquired/available when needed and remains up to date. I5GSYS 2024P00548WO PATENT

[0108] A WTRU may indicate its capabilities to support a DL notification channel. The WTRU may indicate these capabilities in response to a network request, upon satisfaction of a condition, or based on one or more WTRU actions. The contents of the capability indication may include one or more sub-capabilities.

[0109] In examples, the WTRU may notify the network of the WTRU’s capability to monitor and/or receive information on aDL notification channel. The WTRU may provide the capability information during a WTRU capability transfer (e.g., upon RRC connection setup), upon reception of a request from the network, prior to release from a connected state (e.g., upon or prior to reception of an RRC Release or release with suspend message), upon a tracking area update, upon a ran notification area update, upon transition to a DL notification channel, upon reception of paging, or upon initiation of RACH.

[0110] The WTRU may signal its capabilities for the DL notification channel via RRC signaling (e.g., via a capability transfer message or via WTRU assistance information). The WTRU may signal one or more aspects of its DL notification channel capabilities and/or indicate that one or more of its capabilities have changed (e.g., via UCI, SR, NAS, RACH messaging such as MSGA, MSG3 or MSG5, PUSCH, and/or a MAC CE). The capability information may indicate general support for the DL notification channel (e.g., a flag indicating that the DL notification channel is supported) or may indicate one or more specific capabilities. The signaling method selected by the WTRU may depend on whether a general indication or detailed information is provided.

[0111] In examples, the WTRU may indicate that the WTRU is capable of supporting the DL notification channel via a one-bit indication (e.g., a flag). The one-bit indication may imply that the WTRU may support the DL notification channel and possible configurations related to the DL notification channel (e g., coverage enhancements, resources monitoring periodicities and duration(s), etc.).

[0112] In examples, the WTRU may indicate specific capabilities related to the DL notification channel. For example, the WTRU may indicate support for the DL notification channel, support for a subset of frequency resources on the DL notification channel (e.g., a frequency range, frequency bands), support for a specific periodicity for monitoring the DL notification channel, support for specific monitoring durations (e g., the WTRU may monitor for X number of milliseconds or slots, etc.), support for sequence based DL notifications, and/or support for PDCCH-based DL notifications. I5GSYS 2024P00548WO PATENT

[0113] In examples, the WTRU may indicate support for aspects of the DL notification channel implicitly via an indication of other WTRU capability information. For example, the network may assume that, if the WTRU indicates support for repetitions, the WTRU may (e.g., also) support repetition enhancements during DL notification channel transmissions.

[0114] The DL notification channel capability information may be distinguished as being per WTRU, per frequency range (e.g., FR1 or FR2), or per band and/or band combination.

[0115] In examples, the WTRU may receive one or more configurations regarding support for the DL notification channel. These configurations may include configurations to support the monitoring, switching, and/or reception of DL notifications.

[0116] In examples, a WTRU may receive multiple (e.g., two) configurations for the DL notification channel (e.g., one configuration associated with sequence-based notifications, and another configuration associated with PDCCH-based notifications), wherein each configuration may have a different set of parameters or characteristics.

[0117] In examples, the WTRU may receive a configuration associated with the monitoring of a DL notification. The configuration for an UL notification channel may indicate whether monitoring resources are the same as for a paging channel, a set of occasions/resources to monitor for a DL notification channel (e.g., time/frequency occasions, cycles etc.), a set of DL coverage enhancements to receive a DL notification (e.g., a repetition factor, etc.), a start time to monitor the DL notification channel, an end time for monitoring the DL notification channel, a time period to monitor the DL notification channel, a periodicity configuration related to the monitoring of the DL notification channel (e.g., reference time, offset, on duration time, periodicity), one or more reference signals (e.g., to evaluate the signal quality of the DL notification channel), an RNTI (e.g., to receive data from the DL notification channel), characteristics of a DL notification (e.g., whether the notification is sequence-based or PDCCH-based), and/or DL coverage enhancements for receiving a DL notification (e.g., a number of repetitions used for the DL notification and/or a number of retransmissions used for the DL notification).

[0118] In examples, the WTRU may receive a configuration associated with switching from monitoring a paging channel to monitoring a DL notification channel. The configuration may include an indication that the WTRU may directly access the DL notification channel (e.g., without attempting to notify the network), an indication (e.g., a flag) that the WTRU may attempt to notify the network I5GSYS 2024P00548WO PATENT prior to switching to monitoring the DL notification channel, and/or an identifier for the WTRU to indicate that the WTRU is switching to monitoring the notification channel (e.g., a series of preambles, specific RNTIs, etc ).

[0119] In examples, the WTRU may receive a configuration for indicating a DL coverage loss. The configuration for indicating UL coverage loss may include the channel the WTRU may monitor for DL response (e.g., the paging channel or the UL notification channel), whether the WTRU may provide a preference based on a prediction, whether the WTRU may provide a preference based on a measurement, whether the WTRU may provide a preference based on fulfillment of a switching criteria, whether the WTRU may indicate a one-bit preference, and/or whether the WTRU may provide additional information within the preference.

[0120] In examples, methods to acquire or release DL notification channel may ensure that the WTRU has required information to determine when the WTRU may transition to a paging channel and to keep the information up to date.

[0121] In examples, the WTRU may be provided with a DL notification channel configuration upon being released to an RRC IDLE state (e.g., within an RRC Release message) or an RRC INACTIVE state (e.g., within an RRC Release with suspend message). In examples, configurations for a DL notification channel may be indicated/configured/provided via a system information block (SIB) (e.g., within satellite assistance information such as SIB 19, SIB31/32, a new SIB, or within an existing SIB), via a non-access stratum (NAS) message, via a MAC CE, via downlink control information (DCI), via a RACH message (e.g., MSG2, MSG4, and/or MSGB), via RRC signaling, and/or via a PDCCH/PUSCH transmission.

[0122] In examples, the WTRU may receive different components of a DL notification channel configuration via different signaling methods. For example, the WTRU may receive dedicated configuration aspects via RRC signaling (e.g., DL coverage enhancements to apply dedicated RNTIs), and other configurations or information via system information (e.g., the resources to monitor the DL notification channel, whether the DL notification channel is enabled for a given cell, etc.). If the WTRU is provided with a dedicated configuration for the DL notification channel, the WTRU may override other common configuration information (e.g., received via broadcast signaling) or may combine the dedicated configuration with one or more pieces of common configuration information. In another example, the WTRU may use (e.g., the most recently received) information in the configuration regardless of the signaling method. I5GSYS 2024P00548WO PATENT

[0123] In examples, a WTRU may receive a configuration based on a network decision (e.g., upon release to RRC IDLE or RRC INACTIVE) if the WTRU indicates that it may support a DL notification channel. In another example, the WTRU may request to be configured with a DL notification channel configuration. The WTRU may request a DL notification channel configuration, update an existing DL notification channel configuration, or apply a different DL notification channel configuration. For example, the WTRU may apply a different DL notification channel configuration if the WTRU detects that the DL coverage may be degrading for a serving cell (e.g., measurements have fallen below a threshold). The WTRU may apply a different DL notification channel configuration if the WTRU detects that the DL coverage may be degrading for one or more neighboring cells (e.g., measurements have fallen below a threshold). The WTRU may apply a different DL notification channel configuration if the WTRU may not find a suitable cell, the WTRU is about to enter a coverage gap, the WTRU updates the tracking area, the WTRU updates the RAN notification area, or after a time period. The WTRU may apply a different DL notification channel configuration based on one or more switching conditions to transition from a DL notification channel being satisfied.

[0124] A WTRU may connect to a cell (e.g., if the WTRU is not already connected) to receive and/or request a DL notification channel configuration. The WTRU may do so in response to detecting one or more of the following. For example, the WTRU may trigger a RACH and request a configuration for the DL notification channel. The WTRU may request the configuration as part of the RRC setup/resume procedure. In another example, the WTRU may use dedicated messaging to indicate to the network the WTRU is accessing the cell for acquiring a DL notification channel. For example, the WTRU may provide an explicit indication (e.g., via RACH, MAC CE, or UCI). As another example, the WTRU may use a dedicated RACH preamble, a dedicated RNTI, dedicated RACH occasions, a resume or establishment cause, or dedicated resources (e.g., time periods and/or frequencies).

[0125] Upon configuration of a DL notification channel, the WTRU may monitor for one or more trigger conditions to transition to the DL notification channel. The WTRU may release (e.g., not use) the configuration if the network indicates that it may not support a UL notification channel. In examples, the WTRU may release specific parts of the configuration.

[0126] In examples, different DL notification channel configurations may be provided for sequencebased DL notifications and PDCCH-based DL notifications. Each configuration may be I5GSYS 2024P00548WO PATENT independently configured or may share some common information. Each configuration may have its own (e.g., specific) monitoring configuration information (e.g., a set of resources), switching criteria, or other configuration information as described herein.

[0127] A WTRU may be configured with one configuration (e.g., a sequence-based notification or a PDCCH based notification) or multiple configurations (e.g., a sequence-based notification and a PDCCH based notification). If the WTRU is configured with both sequence-based and PDCCH-based DL notification channel configurations, the WTRU may (e.g., simultaneously) activate both configurations (e.g., the WTRU may monitor the DL notification channel for both) or activate one configuration at a time. The WTRU may activate both configurations, one configuration, or none depending on whether the associated triggering conditions may be satisfied to apply the respective configuration. If both triggering conditions may be satisfied and the WTRU is (e.g., only) capable of apply one configuration at a time, the WTRU may select one configuration based on factors such as a WTRU implementation, a configuration with a most conservative configuration (e.g., best improves DL coverage), or a designated configuration (e.g., a flag which may indicate a primary and/or secondary configuration).

[0128] A WTRU may more likely be in a DL coverage limited state during some time periods or conditions (e.g., when a WTRU is located at a cell edge or indoors). Due to WTRU location information, the deterministic nature of satellite movements and/or broadcasted assistance information (e.g., cell footprint, reference location, satellite ephemeris etc.), the periods or conditions in which the WTRU may be at a cell edge (e.g., likely in poor DL coverage) may be predicted ahead of time. Since the network may not have awareness of local coverage conditions or may not be able to track a precise WTRU location while the WTRU is in an IDLE/INACTIVE state, informing the network in advance regarding when the WTRU may be in those locations may help determine whether the WTRU is reachable via a paging or a notification channel.

[0129] An indication may be provided regarding a WTRU’s preference for a DL channel via which the WTRU may be reached in future time periods. Assistance information may be provided and used to determine DL coverage conditions. The WTRU may predict periods during which it may be in a coverage limited state. The WTRU may report its preference for monitoring a specific channel during a time period. The WTRU may take certain actions upon being released to an IDLE/INACTIVE state. [0130] FIG. 3 illustrates an example of predicting limited DL coverage. I5GSYS 2024P00548WO PATENT

[0131] A WTRU may predict (e.g., determine) whether the WTRU may be (e.g., will be) in a period of limited DL coverage and may not be able to receive paging. The DL coverage prediction may be used in a non-terrestrial network, where connections may be based on a line of sight (LoS) and factors that may cause poor coverage may include a free space propagation loss. When combined with additional assistance information provided in non-terrestrial networks (e.g., satellite footprint information for upcoming and neighboring satellites cells), the WTRU may predict the timing and/or duration of poor DL coverage.

[0132] In examples, the WTRU may receive one or more pieces of assistance information (e.g., to support DL coverage prediction). The assistance information may include information about the serving satellite, serving cell, and/or one or more neighboring satellite/cells. For example, the WTRU may receive information of beam switching patterns, beam power splitting/sharing patterns, cell reference locations, cell footprint information (e.g., radius), and/or satellite ephemeris (or other information contained within an ntn-config message).

[0133] The WTRU may receive the assistance information via broadcast signaling (e.g., existing system information blocks such as SIB 19, or a new system information block defined to provide coverage information). The WTRU may receive the assistance information in a dedicated manner (e.g., via a MAC CE, RRC signaling, or RACH signaling). For example, the WTRU may receive the additional assistance information to predict a future coverage state of the WTRU along with a request for a WTRU preference/prediction. In another example, a WTRU may determine beam switching or power splitting/sharing patterns through a reception of DL signals and by identifying one of the physical properties indicating the use of a given pattern.

[0134] The WTRU may determine a time period when the WTRU may monitor the notification channel. For example, the determination may be made based on areas of poor DL coverage, which the WTRU may calculate based on a WTRU location, assistance/coverage information received from a network (e.g., the outer 10% of the cell coverage area may result in poor DL coverage), or historical measurement information (e.g., the WTRU’ s measurements indicate a degrade X km from a cell edge, WTRU is normally indoors from 9pm to 7am, etc.).

[0135] The WTRU may have limitations on the extent to which it may indicate a future prediction. The limitation may be based on a network configured offset time for which the WTRU may provide a prediction, and/or based on other conditions such as the validity period of the assistance information that may be used to make the prediction. For example, the WTRU may consider the assistance I5GSYS 2024P00548WO PATENT information to be valid during a specific time period. The WTRU may consider the assistance information to be valid while the WTRU remains in the RRC Connected state, while the WTRU remains connected to a serving cell, and/or while the WTRU remains served by the same satellite. The WTRU may provide a prediction for a time period up until the expiry of the validity period of the assistance information.

[0136] In examples, prior to being released from an RRC connected state, the WTRU may provide a preference on where the WTRU may be reached while in an RRC IDLE or INACTIVE state. The preference indication may be requested by the network or triggered by the WTRU upon satisfaction of one or more criteria.

[0137] The WTRU may indicate (e.g., via a one bit indication) whether the WTRU prefers to be reached via a paging channel or a notification channel (e.g., upon release from the RRC connection state). The WTRU may include one or more pieces of additional information (e.g., to support a network response), such as whether the request is based on measurements, whether the request is due to a prediction, whether one or more switching criteria have been met, which switching criteria have been met, DL measurements, the time when the WTRU may monitor the channel, whether the WTRU prefers a sequence or PDCCH based notification channel configuration, and/or whether the WTRU is capable of receiving paging (e.g., if the WTRU remains monitoring the paging channel).

[0138] The WTRU may receive a request for assistance information (e.g., via a UEInformationRequest request). The request may be for the WTRU’ s preference on where the WTRU may be reached (e.g., on a paging channel or a notification channel) once the WTRU is released from an RRC Connected state (e.g., upon reception of the RRCRelease message).

[0139] The WTRU may trigger transmission of a preference for the channel via which the WTRU may be reached. The trigger may be on based on reception of a request, a WTRU action, or satisfaction of a criteria. For example, the WTRU may transmit a preference indication upon an explicit request from the network, (e.g., when the network knows it’s planning to switch off or do power sharing). The WTRU may transmit a preference indication based upon local measurements/historical data it may have reduced coverage. The WTRU may transmit a preference indication if the WTRU has local constraints (e.g., power source unavailability or low battery). The WTRU may transmit a preference indication if the WTRU has a wake-up receiver which may wake up the WTRU upon receiving a wake-up signal or notification alert. The WTRU may transmit a preference indication if a time period has expired (e.g., a backoff time has expired). I5GSYS 2024P00548WO PATENT

[0140] The WTRU may provide the preference in response to a WTRU information request by the network. The WTRU may include the preference for where the WTRU may be reached inside a WTRU assistance information response message. The WTRU may provide a response via one or more of an RRC message, a MAC CE, a NAS message, UCI, a PDCSH/PUCCH or RACH message (e.g., a preamble selection message, MSGA, MSG3).

[0141] The signaling method that the WTRU may choose to transmit the preference indication may depend on whether the WTRU may provide the preference in response to an explicit request from the network, the RRC state of the WTRU (e.g., whether the WTRU is in RRC connected state or the WTRU has been released), and/or whether the WTRU is only providing a simple (e.g., one bit) indication of the preferred channel or also providing additional information.

[0142] A network device may respond to the WTRU preference. The network response may be an acknowledgement (ACK)/ non-acknowledgement (NACK) of the WTRU preference. The network response may include additional information/commands for the WTRU to perform. The WTRU may take certain actions if the WTRU is unable to receive the network response (e.g., due to rapid loss of coverage) to ensure that the WTRU and the network remain aligned on when and how the WTRU may be reached.

[0143] In examples, the WTRU may expect and/or monitor for a DL response (e.g., after sending a preference indication). The network may provide the preference indication response upon releasing the WTRU from an RRC Connected state (e.g., upon release of the RRCRelease or RRCReleasewithSuspend). In examples (e.g., if the WTRU has been released from an RRC connection), the WTRU may monitor for a DL response on the paging channel or a DL notification channel. The channel that the WTRU may select to monitor may be based on one or more of the following configurations, indications, or criteria. The WTRU may default to monitoring for a response on a DL notification/alert channel or default to monitoring for a response on a paging channel. The WTRU may monitor a channel based on configuration information and/or monitor the channel indicated in a coverage failure indication message.

[0144] In response to a WTRU preference indication, the network may approve the WTRU preference, reject the WTRU preference and notify the WTRU to monitor a paging channel, or reject the WTRU preference and notify the WTRU to monitor a notification channel. If the WTRU preference is approved, the WTRU may monitor the notification channel or the paging channel according to configuration information during the reported periods. If the WTRU preference is I5GSYS 2024P00548WO PATENT rejected, the WTRU may monitor the channel (e.g., notification or paging) indicated in an RRCRelease message.

[0145] In examples, the network may request additional information from the WTRU to determine whether to approve or reject a WTRU preference. The WTRU may send a preference indication with (e.g., only) a preferred channel to be reached after reception of an RRC Release message. The network may respond with a message requesting one or more pieces of additional WTRU information (e.g., whether certain criteria are satisfied, whether the information is based on measurements vs. prediction, and/or other information)

[0146] In examples, the network may notify the WTRU to move to a channel after a specific offset time. For example, the WTRU may receive an approval for its preference, but may apply the preference only after a time period has elapsed.

[0147] In examples, upon transmission of the WTRU preference indication, the WTRU may monitor for a DL response for a given time period. For example, upon transmission of the WTRU preference, the WTRU may start a timer. If the WTRU does not receive a DL response at the timer expiry, the WTRU may declare that no response is available. In another example, the WTRU may wait up to X occasions for a DL response. If no response is received after X occasions, the WTRU may assume that no response is available. If the WTRU determines that no network response is available, the WTRU may apply the preferences indicated within the preference indication, monitor the paging channel, and/or monitor the DL notification channel. The actions that may be performed by the WTRU may be based on an explicit configuration (e.g., within the DL notification channel configuration), an indication (e.g., within a SIB), WTRU implementation, and/or a specified rule.

[0148] DL coverage may change over time due to beam power sharing, satellite movements, or user actions (e.g., walking into a building or putting a phone in your pocket). These changes may cause an IDLE/INACTIVE WTRU originally in good coverage to become unreachable on a paging channel and fall back to a more conservative notification/alert channel. In this case, the WTRU may use a mechanism to detect the change and notify the network that the WTRU is becoming unreachable on the current paging channel or that coverage has sufficiently improved for receiving paging. The notification may ensure synchronization between the network and the WTRU on where the WTRU may be reached. I5GSYS 2024P00548WO PATENT

[0149] Examples described herein may support the detection, transition, and indication of switching between a paging channel and a DL notification/alert channel. For example, a WTRU may detect an entry into a limited DL coverage state, transition from monitoring the paging channel to monitoring the DL notification/alert channel, and/or notify the network about the transition (e.g., via mapping of tracking areas and/or RAN notification areas to different channels).

[0150] A WTRU may switch to a DL notification channel to remain reachable to a network. The WTRU may (e.g., only) switch to the DL notification channel upon network approval, and/or if associated criteria are satisfied to ensure that the WTRU and network remain aligned on where the WTRU may be reached.

[0151 ] A WTRU may be configured with one or more criteria (e.g., within a DL notification channel configuration) for channel switching. Upon satisfaction of the configured criteria, the WTRU may switch from monitoring a paging channel to monitoring a DL notification channel. The criteria to switch to the DL notification channel may be based on measurements, predictions, failed transmission/receptions, and/or characteristics of an NTN deployment. For example, the criteria may be that the WTRU cannot (e.g., does not) detect paging, that the WTRU cannot (e.g., does not) detect a (e g., any) DL reference signal (e.g., an SSB), that the WTRU can detect (e.g., that the WTRU detects) fewer than X DI reference signals within a window, that a ratio of failed PDCCH receptions to successful PDCCH receptions exceeds a threshold, or that the WTRU may not (e.g., does not) find a suitable cell. The criteria may be based on an SSB reception, the number of SSBs detected within a window, in-sync (IS)/out-of-sync (OOS) indications, etc. The criteria may be based on the ratio of a number of failed PDCCH receptions to a number of successful PDCCH receptions for an SIB, or based on one or more conditions indicating that the WTRU may be in a coverage limited state (e.g., RSRP/DL pathloss thresholds T1 and T2, wherein the condition may be met if the current camped cell RSRP is < Tl, and the RSRP of all other detected neighboring cells is < T2). The criteria may be based on the WTRU measurement of a camped cell and a determination that the current camped cell RSRP is < TL The criteria may be based on the WTRU measurement of neighboring cells and a determination that the RSRP of all suitable neighboring cells is < T2. The WTRU may have a different set of criteria for sequence-based and PDCCH-based notification channels.

[0152] The WTRU may notify the network (e.g., via an indication) of when the WTRU has switched to monitoring the DL notification channel. The notification may occur if the WTRU preference has changed after having been released from the network, or if one or more of the associated switching I5GSYS 2024P00548WO PATENT criteria (e.g., conditions to switch from the paging channel to the DL notification channel) are satisfied while the WTRU is monitoring the paging channel.

[0153] A tracking area and/or RAN notification area ID/code may be mapped to a specific channel (e.g., a paging channel, a sequence-based DL notification channel, or a PDCCH-based notification channel). In examples, a network may broadcast different tracking area IDs for a (e.g., each) channel. If an area is not broadcast by the network, the WTRU may assume that the channel is not supported in the area.

[0154] A WTRU may declare (e.g., determine) a coverage limited state and trigger a tracking area update (TAU) or a RAN notification area update (RNAU) to a tracking area specific to a notification channel (e.g., to indicate that the WTRU may be in a coverage limited state and may switch to measuring the notification channel). Upon completion of the tracking area update, the WTRU may apply the associated DL notification channel configuration and monitor the channel according to the configuration. These operations may also be performed when the WTRU switches back to monitoring the paging channel (e.g., if the coverage conditions have improved).

[0155] A WTRU may indicate a transition to a DL notification channel via the use of dedicated resources. For example, the WTRU may indicate that it is now monitoring the DL notification channel by performing a transmission using a dedicated resume/setup cause, using different dedicated preambles, using an explicit indication within a MSGA/MSG3 message, or using a dedicated sequence.

[0156] A WTRU may have different behaviors and/or apply a different set of configurations while camped on a DL notification channel (e.g., as compared to a paging channel). For example, the monitoring behaviors and/or the applied DL coverage enhancements may be different for the DL notification channel. WTRU actions in response to the reception of a DL notification may differ from WTRU actions in response to the reception of a paging message.

[0157] A WTRU may perform one or more of the following actions while monitoring a DL notification channel (e.g., to ensure that the WTRU and the network are aligned with respect to where the WTRU may be reached) and/or upon receiving a DL notification. The WTRU may monitor the DL notification channel continuously (e.g., to be always reachable to the network). The WTRU may determine to continuously monitor the DL notification channel based on an explicit configuration or based on an absence of a configuration limiting the monitoring duration. If the WTRU is provided I5GSYS 2024P00548WO PATENT with one or more DL notification channel monitoring occasions (e.g., in the time domain), the WTRU may (e.g., implicitly) determine a time period during which the WTRU may monitor the DL notification channel (e.g., based on the pattern and time of the DL notification occasions). If the DL notification channel occasions are associated with a time period, the WTRU may monitor the DL notification channel configuration during that time period.

[0158] The WTRU may be configured with a time period to monitor the DL notification channel. For example, the WTRU may be provided with a start time and an end time. The WTRU may monitor the DL notification channel during the time period between the start time and the end time. The WTRU may be provided with a start time and a duration, where the WTRU may monitor the DL notification channel at the indicated time and for the indicated duration. The WTRU may be provided with a duration and may start the duration (e.g., a time period) upon switching to monitoring the DL notification channel. The time period may be maintained in the WTRU via a timer (e.g., a DL notification channel timer), wherein the WTRU may start the timer upon switching to monitoring the DL notification channel and, while the timer is running, the WTRU may monitor the DL notification channel.

[0159] The WTRU may monitor the DL notification channel periodically. For example, the WTRU may be provided with a reference time, an offset, an on duration, and/or a periodicity. The WTRU may monitor the DL notification channel after an offset from a reference time (e.g., a UTC time, an SFN, and/or a slot). While in the on duration, the WTRU may monitor the resources dedicated for the DL notification channel. The WTRU may monitor the DL notification channel again for successive on durations based on the configured periodicity. The WTRU may start (e.g., immediately) monitoring the DL notification channel (e.g., once one or more switching conditions are triggered or upon receiving a network approval or after an offset from when the switching conditions are triggered).

[0160] Upon reception of a notification channel message, the WTRU may attempt a cooperative user detection, monitor for a paging message, or initiate a RACH procedure.

[0161] According to embodiments of the present disclosure, a WTRU may receive configuration information for a DL notification/alert channel (e.g., a set of occasions to monitor the channel and/or an RNTI to decode signaling received via the channel). The WTRU may receive assistance information (e.g., satellite assistance information) regarding satellite/cell coverage for one or more cells (e.g., satellite ephemeris data, one or more reference locations, distance thresholds, and/or cell radii). The WTRU may acquire location information and/or estimate (e.g., in consideration with other I5GSYS 2024P00548WO PATENT assistance and/or historical information) when the WTRU may be in areas of limited coverage such as a cell edge (e.g., based on when the WTRU may be at a cell or satellite edge).

[0162] The WTRU may (e.g., prior to being released to an RRC IDLE/INACTIVE state) provide WTRU assistance information regarding which DL channel the WTRU may be reached (e.g., prefer to be reached) at future time periods. The assistance information may be based on WTRU/satellite location and/or satellite coverage information provided by the network. The network may approve a WTRU preference (e.g., indicated by the assistance information) for where to be reached (e.g., upon releasing the WTRU to the RRC IDLE/INACTIVE state), and the WTRU may monitor for DL signaling according to the assistance information/preference provided. The network may reject the WTRU preference and may explicitly direct the WTRU to monitor a particular channel.

[0163] FIG. 4 illustrates an example of indicating a WTRU preference for whether to be reached via a paging channel or a DL notification/alert channel.

[0164] The WTRU may perform one or more of operations to indicate a WTRU preference for a DL channel (e.g., the DL notification channel) via which the WTRU may be reached. The WTRU may receive notification channel configuration information. The notification channel configuration information may include a set of occasions (e.g., network parameters) to monitor a notification channel (e.g., time/frequency occasions, cycles, etc., which may be similar to those of a paging channel), characteristics of a notification alert (e.g., sequence-based or PDCCH-based), etc. The notification channel configuration information may indicate dedicated RNTIs associated with the monitoring of a notification channel (if the notification channel is PDCCH based).

[0165] The WTRU may receive a request for assistance information (e.g., a UEInformationRequest). The request may be for the WTRU’s preference on where the WTRU may be reached (e.g., on a paging channel or a notification channel) once the WTRU is released from an RRC Connected state (e.g., upon reception of an RRCRelease message).

[0166] The WTRU may acquire satellite coverage assistance information and determine the time period(s) when the WTRU may monitor the notification channel. For example, the determination may be based on areas of poor DL coverage (e.g., a coverage limited area), which the WTRU may calculate based on the WTRU location, assistance/coverage information from the network (e.g., the outer 10% of the cell coverage area may result in poor DL coverage), or historical measurement information (e.g., the WTRU’s measurements may indicate a degrade X km from a cell edge, or that the WTRU I5GSYS 2024P00548WO PATENT may be normally indoors from 9pm to 7am, etc.). The WTRU may report the time periods in which the WTRU may monitor the notification channel, and the WTRU’s preference to be paged via the notification channel during those periods. The WTRU may the time periods and the WTRU’s preference in the same message or in separate messages.

[0167] The network may (e.g., upon releasing the WTRU from RRC Connected via an RRCRelease or RRCReleasewithSuspend message) approve the WTRU preference, reject the WTRU preference and notify the WTRU to monitor the paging channel, or reject the WTRU preference and notify the WTRU to monitor the notification channel. If the WTRU preference is approved, the WTRU may monitor the notification channel or the paging channel based on corresponding configuration information during the reported periods. If the WTRU preference is rejected, the WTRU may monitor the channel (e.g., notification or paging) indicated in RRCRelease message.

[0168] According to embodiments of the present disclosure, a WTRU may receive configuration information for a notification channel (e.g., cycles, occasions, RNTIs, etc.). The WTRU may (e.g., prior to being released to an RRC IDLE/INACTIVE state) provide preference regarding which future periods the WTRU may monitor the notification channel (e.g., based on DL coverage information). The network may indicate (e.g., in a release message) that the WTRU preference is approved, that the WTRU preference is rejected and the WTRU should monitor a paging channel, or that the WTRU preference is rejected and the WTRU should monitor a notification channel. The WTRU may monitor a channel according to the network indication (e.g., in the IDLE/INACTIVE state).

[0169] By reporting when the WTRU may monitor the notification channel, WTRU-NW synchronization may be improved and the chance of the WTRU remaining reachable at times of poor DL coverage may be increased. The reporting may reduce signaling overhead by reducing paging escalation. The reporting may improve WTRU power saving by avoiding unnecessary monitoring of the paging channel on which signaling may not be received.

[0170] According to embodiments of the present disclosure, a WTRU may detect a coverage failure and transit from a paging channel to a DL notification/alert channel. The WTRU may receive configuration information for the DL notification/alert channel (e.g., a set of occasions to monitor the channel and/or an RNTI for decoding signaling received via the channel). The WTRU may receive configuration information related to detecting and indicating to the network whether the WTRU is in a coverage limited scenario. The configuration information may include criteria for determining whether the WTRU is in a coverage limited state (e.g., the criteria may include one or more I5GSYS 2024P00548WO PATENT measurement-based thresholds for evaluating the channel quality of the currently camped cell and/or one or more neighboring cells). The configuration information may include means for indicating whether the WTRU is transitioning to the notification/alert channel (e.g., via a set of dedicated tracking areas/RAN notification areas specific to the notification/alert channel).

[0171] The WTRU may begin to monitor the paging channel and/or perform cell (re)selection (e.g., upon being released to an RRC IDLE or RRC INACTIVE state). The WTRU may monitor serving and neighboring channel quality and compare that to the provided criteria to determine a coverage limited state. Upon detection that the DL coverage has deteriorated sufficiently for the WTRU to be considered coverage limited (e.g., one or more corresponding measurement thresholds have been satisfied), the WTRU may trigger a tracking area update and/or RAN notification area update to a tracking area/RAN notification area corresponding to the notification/alert channel (e.g., to notify the network that it may begin monitoring the notification/alert channel).

[0172] The WTRU may continue monitoring the channel quality (e.g., via the same or different set of measurement resources), and if the channel quality has sufficiently improved (e.g., the channel quality has improved above the criteria such as a measurement threshold), the WTRU may trigger a second tracking area and/or RAN notification area update corresponding to a tracking area/RAN notification area associated with the paging channel.

[0173] FIG. 5 illustrates an example of a WTRU transitioning from monitoring a paging channel to monitoring a notification/alert channel.

[0174] The WTRU may receive notification channel configuration information. The notification channel configuration information may include a set of occasions to monitor a notification channel (e.g., time/frequency occasions, cycles, etc., which may be similar to those of a paging channel). The notification channel configuration information may indicate characteristics of a notification alert (e.g., sequence-based or PDCCH-based). The notification channel configuration information may indicate a set of tracking areas (TA) or RAN notification areas (RNAs) associated with the notification channel and/or one or more conditions for the WTRU to determine that it is in a coverage limited state (e.g., RSRP/DL pathloss thresholds T1 and T2, wherein the condition may be met if the current camped cell RSRP is < Tl, and/or if the RSRP of all other detected neighboring cells is < T2).

[0175] The WTRU may be released to an IDLE/INACTIVE state (e.g., via the reception of an RRCRelease or RRCReleasewithSuspend message). The WTRU may measure the camped cell and I5GSYS 2024P00548WO PATENT may determine that the current camped cell RSRP is < Tl . The WTRU may measure one or more neighboring cells and determine that the RSRP of all suitable neighboring cells is < T2. The WTRU may declare a coverage limited state and trigger a TAU or an RNAU to a tracking area specific to the notification channel (e.g., to indicate that it is in a coverage limited state and is switching to measuring the notification channel). The WTRU may perform a RACH procedure and indicate it in MSG3/MSG5 or via a dedicated preamble. The WTRU may monitor the notification channel (e.g., according to the occasions provided within the notification channel configuration information).

[0176] One or more dedicated TAs/RANs may be associated with the notification channel. If the WTRU detects that DL coverage is deteriorating, the WTRU may perform a TAU or RNAU to notify the network that the WTRU may no longer be reached on the paging channel, and the WTRU may monitor the notification channel. By reporting when the WTRU may monitor the notification channel, WTRU-NW synchronization may be improved and the chance of the WTRU remaining reachable during times of poor DL coverage may be increased. If detected early, performing the notification in advance of losing coverage may allow the WTRU to apply procedures such as a TAU and/or an RNAU.

[0177] According to embodiments of the present disclosure, a WTRU may be configured to monitor a DL notification channel. The DL notification channel configuration may indicate monitoring occasions for the notification channel, DL coverage enhancements, criteria to switch from a paging channel to the DL notification channel, whether/how the WTRU may indicate its preference for where it may reached, etc.

[0178] The WTRU may receive separate configurations for a sequence-based DL notification channel and a PDCCH-based DL notification channel. The WTRU may update or request a DL notification upon satisfaction of one or more conditions including, for example, when the WTRU cannot find a suitable cell, when the WTRU fails to decode a paging message, when a DL RS cannot be detected, when DL coverage is degrading, when a TAU/RNAU is triggered, etc.

[0179] The WTRU may select between a sequence-based and a PDCCH-based DL notification channel depending on a configuration or satisfaction of one or more criteria (e.g., which channel may provide the best DL coverage).

[0180] The WTRU may use satellite assistance information to predict areas and/or periods of poor DL coverage. The WTRU may provide a preference of how it may be reached upon release from an I5GSYS 2024P00548WO PATENT

RRC Connected state (e.g., via a paging channel or via a sequence-based or a PDCCH-based DL notification channel). The WTRU may be configured to send a preference indication based on a prediction of DL coverage, measurements of DL coverage, satisfaction of a switching criteria, etc. The WTRU may automatically monitor a preferred channel upon the release or may wait for a network ACK/NACK of the preference.

[0181] The WTRU may be provided with one or more conditions for switching between monitoring a paging channel and monitoring a notification channel. The conditions may include whether the WTRU detects a DL RS, whether the WTRU fails decoding a page, whether the WTRU can find a suitable cell, etc. One or more dedicated tracking areas (TAs) or RAN Notification Areas (RNAs) may be associated with the DL notification channel. If the WTRU detects that DL coverage is deteriorating, the WTRU may perform a TAU or RNAU to notify the network that it may no longer be reached on the paging channel, and/or that it may monitor the notification channel.

[0182] The WTRU may monitor for the DL notification channel differently from monitoring the paging channel. For example, the WTRU may monitor the notification channel indefinitely, for a duration (e.g., subject to a timer), while certain conditions are satisfied, or periodically. Upon reception of a notification on the DL notification channel, the WTRU may attempt a cooperative user detection, may switch to monitoring the paging channel, or may trigger a RACH procedure.

[0183] Although features and elements described above are described in particular combinations, each feature or element may be used alone without the other features and elements of the preferred embodiments, or in various combinations with or without other features and elements.

[0184] Although the implementations described herein may consider 3GPP specific protocols, it is understood that the implementations described herein are not restricted to this scenario and may be applicable to other wireless systems. For example, although the solutions described herein consider LTE, LTE-A, New Radio (NR) or 5G specific protocols, it is understood that the solutions described herein are not restricted to this scenario and are applicable to other wireless systems as well.

[0185] The processes described above may be implemented in a computer program, software, and/or firmware incorporated in a computer-readable medium for execution by a computer and/or processor. Examples of computer-readable media include, but are not limited to, electronic signals (transmitted over wired and/or wireless connections) and/or computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, a read only memory (ROM), a I5GSYS 2024P00548WO PATENT random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as, but not limited to, internal hard disks and removable disks, magneto-optical media, and/or optical media such as compact disc (CD)-ROM disks, and/or digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, terminal, base station, RNC, and/or any host computer.

Claims

I5GSYS 2024P00548WO PATENT CLAIMS

1. A wireless transmit/receive unit (WTRU), comprising: a processor configured to: receive configuration information from a network device, wherein the configuration information is associated with a notification channel; determine that the WTRU is in a coverage limited area; and based at least on the determination that the WTRU is in the coverage limited area and an indication, received from the network device, that the WTRU monitor the notification channel, monitor the notification channel for a first message from the network device.

2. The WTRU of claim 1, wherein the processor is further configured to send a second message to the network device that indicates a preference of the WTRU to receive the first message from the network device via the notification channel.

3. The WTRU of claim 2, wherein the processor is further configured to receive a response from the network device associated with the preference, wherein the response includes the indication that the WTRU monitor the notification channel.

4. The WTRU of claim 2, wherein the processor is further configured to indicate, in the second message, a time period for monitoring the notification channel or send a third message to the network device that indicates the time period for monitoring the notification channel.

5. The WTRU of claim 2, wherein the processor is further configured to indicate, in the second message, network parameters for monitoring the notification channel or send a third message to the network device that indicates the network parameters for monitoring the notification channel.

6. The WTRU of claim 1, wherein the determination that the WTRU is in the coverage limited area is based on a determination that a signal strength is below a threshold, wherein the threshold is indicated in the configuration information.

7. The WTRU of claim 1, wherein the processor is further configured to: I5GSYS 2024P00548WO PATENT monitor the notification channel for the first message from the network device further based on a determination that a time period has not expired, wherein the time period is indicated in the configuration information.

8. The WTRU of claim 1, wherein the processor is configured to: monitor the notification channel for the first message from the network device further based on a determination that a signal strength of a paging channel is below a threshold or based on a determination that a number of reference signals has been detected within a time period.

9. The WTRU of claim 2, wherein the second message to the network device further indicates that the WTRU is monitoring the notification channel for the first message from the network device.

10. The WTRU of claim 1, wherein the configuration information indicates a first configuration associated with a sequenced-based notification configuration and a second configuration associated with a Physical Downlink Control Channel (PDCCH)-based notification configuration.

11. A method comprising: receiving configuration information from a network device, wherein the configuration information is associated with a notification channel; determining that a WTRU is in a coverage limited area; and based at least on the determination that the WTRU is in the coverage limited area and an indication, received from the network device, that the WTRU monitor the notification channel, monitoring the notification channel for a first message from the network device.

12. The method of claim 11, wherein the method further comprises sending a second message to the network device that indicates a preference of the WTRU to receive the first message from the network device via the notification channel.

13. The method of claim 12, wherein the method further comprises receiving a response from the network device associated with the preference, wherein the response includes the indication that the WTRU monitor the notification channel. I5GSYS 2024P00548WO PATENT

14. The method of claim 12, wherein the method further comprises indicating, in the second message, a time period for monitoring the notification channel or send a third message to the network device that indicates the time period for monitoring the notification channel.

15. The method of claim 12, wherein the method further comprises indicating, in the second message, network parameters for monitoring the notification channel or send a third message to the network device that indicates the network parameters for monitoring the notification channel.