Method for performing store and forward

Abstract

An embodiment of the present disclosure provides a method by which an AMF performs communication. The method comprises the steps of: receiving, from an SMF, a confirmation request message regarding reachability to a UE; determining whether a feeder link is connected, on the basis of information on feeder link availability; determining estimated connection time of the feeder link on the basis of the absence of the feeder link connection, wherein the feeder link is a link between a satellite and a gateway connected to the AMF for the transmission of downlink data for the UE, and the method comprises a step of transmitting a response message to the SMF on the basis of the confirmation request message, the response message including whether the feeder link has been determined to be connected, and the response message including an estimated connection time of the feeder link on the basis of the absence of the feeder link connection.

Description

How to perform STORE AND FORWARD

[0001] This specification relates to mobile communications.

[0002] 3GPP (3rd Generation Partnership Project) LTE (Long-Term Evolution) is a technology designed to enable high-speed packet communications. Numerous approaches have been proposed to achieve LTE's goals of reducing costs for users and operators, improving service quality, expanding coverage, and increasing system capacity. 3GPP LTE's high-level requirements include reduced cost per bit, improved service availability, flexible use of frequency bands, a simple architecture, open interfaces, and adequate power consumption for terminals.

[0003] The International Telecommunication Union (ITU) and 3GPP have begun work on developing requirements and specifications for new radio (NR) systems. 3GPP must identify and develop the technical components necessary to successfully standardize NR in a timely manner, meeting both urgent market needs and the longer-term requirements outlined by the ITU-R (ITU radio communication sector) International Mobile Telecommunications (IMT)-2020 process. NR must also be able to utilize any spectrum band up to at least 100 GHz, ensuring that it remains available for wireless communications well into the future.

[0004] NR aims to be a single technology framework that addresses all deployment scenarios, usage scenarios, and requirements, including enhanced mobile broadband (eMBB), massive machine type communications (mMTC), and ultra-reliable and low latency communications (URLLC). NR must be inherently forward-compatible.

[0005] A specific method for S&F is needed depending on whether the feeder link and service link are connected.

[0006] Downlink data is transmitted to the terminal after being buffered by the UPF or satellite.

[0007] Figure 1 illustrates an example of a communication system to which the implementation of this specification is applied.

[0008] Figure 2 illustrates an example of a wireless device to which the implementation of the present specification is applied.

[0009] Figure 3 shows an example of a UE to which the implementation of this specification is applied.

[0010] Figure 4 is a structural diagram of a next-generation mobile communications network.

[0011] Figure 5 shows an example of a 5G system structure to which the implementation of this specification is applied.

[0012] Figure 6 shows an example of basic satellite operation.

[0013] Figure 7 shows an example of S&F satellite operation.

[0014] Figure 8 shows an example of connection resumption in RRC_INACTIVE by the network.

[0015] Figures 9, 10 and 11 illustrate examples of procedures according to the first embodiment of the present specification.

[0016] Figure 12 shows an example of a procedure following the second embodiment of the present specification.

[0017] Figure 13 illustrates the AMF's procedure for the disclosure of this specification.

[0018] Figure 14 illustrates the SMF procedure for the disclosure of this specification.

[0019] Figure 15 illustrates the satellite procedure for the disclosure of this specification.

[0020] The following techniques, devices, and systems can be applied to various wireless multiple access systems. Examples of multiple access systems include code division multiple access (CDMA) systems, frequency division multiple access (FDMA) systems, time division multiple access (TDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and multicarrier frequency division multiple access (MC-FDMA) systems. CDMA can be implemented via wireless technologies such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA can be implemented via wireless technologies such as global system for mobile communications (GSM), general packet radio service (GPRS), or enhanced data rates for GSM evolution (EDGE). OFDMA can be implemented using wireless technologies such as IEEE (Institute of Electrical and Electronics Engineers) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, or E-UTRA (evolved UTRA). UTRA is part of UMTS (universal mobile telecommunications system). 3GPP (3rd generation partnership project) LTE (long-term evolution) is part of E-UMTS (evolved UMTS) that uses E-UTRA.3GPP LTE uses OFDMA in the downlink (DL) and SC-FDMA in the uplink (UL). Evolution of 3GPP LTE includes LTE-A (advanced), LTE-A Pro, and / or 5G NR (new radio).

[0021] For convenience of explanation, the implementation of this specification is primarily described in relation to a 3GPP-based wireless communication system. However, the technical features of this specification are not limited thereto. For example, the following detailed description is provided based on a mobile communication system corresponding to a 3GPP-based wireless communication system. However, aspects of this specification that are not limited to a 3GPP-based wireless communication system can be applied to other mobile communication systems.

[0022] For terms and technologies used in this specification that are not specifically described, reference may be made to wireless communication standard documents published prior to this specification.

[0023] As used herein, "A or B" can mean "only A," "only B," or "both A and B." Alternatively, as used herein, "A or B" can be interpreted as "A and / or B." For example, as used herein, "A, B or C" can mean "only A," "only B," "only C," or "any combination of A, B and C."

[0024] As used herein, a slash ( / ) or a comma can mean "and / or." For example, "A / B" can mean "A and / or B." Accordingly, "A / B" can mean "only A," "only B," or "both A and B." For example, "A, B, C" can mean "A, B, or C."

[0025] In this specification, “at least one of A and B” may mean “only A,” “only B,” or “both A and B.” Additionally, in this specification, the expressions “at least one of A or B” or “at least one of A and / or B” may be interpreted identically to “at least one of A and B.”

[0026] Additionally, in this specification, “at least one of A, B and C” can mean “only A”, “only B”, “only C”, or “any combination of A, B and C”. Additionally, “at least one of A, B or C” or “at least one of A, B and / or C” can mean “at least one of A, B and C”.

[0027] Additionally, parentheses used herein may mean "for example." Specifically, when indicated as "control information (PDCCH)", "PDCCH" may be proposed as an example of "control information." In other words, "control information" in this specification is not limited to "PDCCH," and "PDCCH" may be proposed as an example of "control information." Furthermore, even when indicated as "control information (i.e., PDCCH)", "PDCCH" may be proposed as an example of "control information."

[0028] Technical features individually described in a single drawing in this specification may be implemented individually or simultaneously.

[0029] Although not limited thereto, the various descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed herein may be applied to various fields requiring wireless communication and / or connectivity between devices (e.g., 5G).

[0030] Hereinafter, the present specification will be described in more detail with reference to the drawings. In the following drawings and / or description, the same reference numbers may refer to the same or corresponding hardware blocks, software blocks, and / or functional blocks, unless otherwise indicated.

[0031] Figure 1 illustrates an example of a communication system to which the implementation of this specification is applied.

[0032] The 5G usage scenario shown in FIG. 1 is only an example, and the technical features of this specification can be applied to other 5G usage scenarios not shown in FIG. 1.

[0033] The three main requirement categories for 5G are (1) enhanced mobile broadband (eMBB), (2) massive machine type communication (mMTC), and (3) ultra-reliable and low latency communications (URLLC).

[0034] Referring to FIG. 1, a communication system (1) includes wireless devices (100a to 100f), a base station (BS; 200), and a network (300). FIG. 1 illustrates a 5G network as an example of a network of the communication system (1), but the implementation of the present disclosure is not limited to a 5G system and can be applied to future communication systems beyond the 5G system.

[0035] The base station (200) and the network (300) may be implemented as wireless devices, and a particular wireless device may operate as a base station / network node in relation to other wireless devices.

[0036] Wireless devices (100a to 100f) refer to devices that perform communication using radio access technology (RAT) (e.g., 5G NR or LTE) and may also be referred to as communication / wireless / 5G devices. Wireless devices (100a to 100f) may include, but are not limited to, robots (100a), vehicles (100b-1 and 100b-2), extended reality (XR) devices (100c), portable devices (100d), home appliances (100e), IoT devices (100f), and artificial intelligence (AI) devices / servers (400). For example, vehicles may include vehicles having wireless communication capabilities, autonomous vehicles, and vehicles capable of performing vehicle-to-vehicle communication. Vehicles may include unmanned aerial vehicles (UAVs) (e.g., drones). XR devices may include AR / VR / mixed reality (MR) devices, and may be implemented in the form of head-mounted devices (HMDs) and heads-up displays (HUDs) mounted on vehicles, televisions, smartphones, computers, wearable devices, home appliances, digital signs, vehicles, robots, etc. Portable devices may include smartphones, smart pads, wearable devices (e.g., smart watches or smart glasses), and computers (e.g., laptops). Home appliances may include TVs, refrigerators, and washing machines. IoT devices may include sensors and smart meters.

[0037] In this specification, wireless devices (100a to 100f) may be referred to as user equipment (UE). The UE may include, for example, a mobile phone, a smartphone, a laptop computer, a digital broadcasting terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), a navigation system, a slate PC, a tablet PC, an ultrabook, a vehicle, a vehicle with autonomous driving functions, a connected car, a UAV, an AI module, a robot, an AR device, a VR device, an MR device, a holographic device, a public safety device, an MTC device, an IoT device, a medical device, a fintech device (or a financial device), a security device, a weather / environmental device, a 5G service-related device, or a 4th industrial revolution-related device.

[0038] For example, a UAV may be an aircraft that is unmanned and navigated by radio control signals.

[0039] For example, a VR device may include a device for implementing objects or backgrounds in a virtual environment. For example, an AR device may include a device that implements objects or backgrounds in a virtual world by connecting them to objects or backgrounds in the real world. For example, an MR device may include a device that implements objects or backgrounds in a virtual world by merging them with objects or backgrounds in the real world. For example, a holographic device may include a device that implements 360-degree stereoscopic images by recording and reproducing three-dimensional information using the light interference phenomenon that occurs when two laser lights, called holograms, meet.

[0040] For example, a public safety device may include an image relay device or imaging device that can be worn on the user's body.

[0041] For example, MTC devices and IoT devices may be devices that do not require direct human intervention or manipulation. Examples include smart meters, vending machines, thermometers, smart light bulbs, door locks, or various sensors.

[0042] For example, a medical device may be a device used for the purpose of diagnosing, treating, alleviating, curing, or preventing a disease. For example, a medical device may be a device used for diagnosing, treating, alleviating, or correcting an injury or damage. For example, a medical device may be a device used for the purpose of examining, replacing, or modifying a structure or function. For example, a medical device may be a device used for the purpose of regulating pregnancy. For example, a medical device may include a therapeutic device, a driving device, an (in vitro) diagnostic device, a hearing aid, or a surgical device.

[0043] For example, a security device may be a device installed to prevent potential hazards and maintain safety. For example, a security device may be a camera, closed-circuit television (CCTV), recorder, or black box.

[0044] For example, a fintech device may be a device capable of providing financial services, such as mobile payments. For example, a fintech device may include a payment device or a point-of-sale system.

[0045] For example, a weather / environment device may include a device that monitors or predicts the weather / environment.

[0046] Wireless devices (100a to 100f) can be connected to a network (300) via a base station (200). AI technology can be applied to the wireless devices (100a to 100f), and the wireless devices (100a to 100f) can be connected to an AI server (400) via the network (300). The network (300) can be configured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR) network, and a network after 5G. The wireless devices (100a to 100f) can communicate with each other via the base station (200) / network (300), but can also communicate directly (e.g., sidelink communication) without going through the base station (200) / network (300). For example, vehicles (100b-1, 100b-2) can communicate directly (e.g., vehicle-to-vehicle (V2V) / vehicle-to-everything (V2X) communication). Additionally, IoT devices (e.g., sensors) can communicate directly with other IoT devices (e.g., sensors) or other wireless devices (100a to 100f).

[0047] Wireless communication / connection (150a, 150b, 150c) can be established between wireless devices (100a to 100f) and / or between wireless devices (100a to 100f) and a base station (200) and / or between base stations (200). Here, the wireless communication / connection can be established through various RATs (e.g., 5G NR), such as uplink / downlink communication (150a), sidelink communication (150b) (or, device-to-device (D2D) communication), and base station-to-base station communication (150c) (e.g., relay, integrated access and backhaul (IAB)). Through the wireless communication / connection (150a, 150b, 150c), the wireless devices (100a to 100f) and the base station (200) can transmit / receive wireless signals to / from each other. For example, wireless communication / connection (150a, 150b, 150c) can transmit / receive signals through various physical channels. To this end, at least some of the various configuration information setting processes for transmitting / receiving wireless signals, various signal processing processes (e.g., channel encoding / decoding, modulation / demodulation, resource mapping / demapping, etc.), and resource allocation processes can be performed based on various proposals of the present specification.

[0048] AI is the study of artificial intelligence or the methodologies for creating it, while machine learning (ML) defines various problems in the field of AI and studies the methodologies for solving them. Machine learning is also defined as an algorithm that improves performance on a task through consistent experience.

[0049] A robot can be defined as a machine that automatically processes or operates a given task based on its own capabilities. Specifically, a robot capable of perceiving its environment, making decisions, and performing actions on its own can be called an intelligent robot. Robots can be categorized into industrial, medical, household, and military applications based on their intended use or field. Robots are equipped with a drive unit, including an actuator or motor, enabling them to perform various physical actions, such as moving robot joints. Furthermore, mobile robots include wheels, brakes, and propellers in their drive unit, enabling them to drive on the ground or fly in the air.

[0050] Autonomous driving refers to the technology of driving on one's own, while autonomous vehicles refer to vehicles that drive without, or with minimal, user intervention. For example, autonomous driving can include technologies such as lane keeping, automatic speed control like adaptive cruise control, autonomous driving along a set route, and autonomous driving based on a set destination. Vehicles encompass all types of vehicles: those with internal combustion engines, hybrid vehicles with both internal combustion engines and electric motors, and electric vehicles with only electric motors. These vehicles can include not only cars but also trains and motorcycles. Autonomous vehicles can be viewed as robots with autonomous driving capabilities.

[0051] Extended reality is a general term for VR, AR, and MR. VR technology provides real-world objects and backgrounds as CG images only, AR technology provides virtual CG images over images of real objects, and MR technology is a CG technology that mixes and combines virtual objects with the real world. MR technology is similar to AR in that it displays real and virtual objects together. However, there is a difference: while AR uses virtual objects to complement real objects, MR uses virtual and real objects equally.

[0052] NR supports multiple numerologies, or subcarrier spacing (SCS), to support diverse 5G services. For example, an SCS of 15 kHz supports wide areas in traditional cellular bands; an SCS of 30 kHz / 60 kHz supports dense urban areas, lower latency, and wider carrier bandwidth; and an SCS of 60 kHz or higher supports bandwidths greater than 24.25 GHz to overcome phase noise.

[0053] The NR frequency band can be defined by two types of frequency ranges (FR1 and FR2). The numerical values ​​of the frequency ranges can be changed. For example, the two types of frequency ranges (FR1 and FR2) can be as shown in Table 1 below. For convenience of explanation, among the frequency ranges used in NR systems, FR1 can mean the "sub-6GHz range," and FR2 can mean the "above 6GHz range," which can be referred to as millimeter wave (mmW).

[0054] Frequency Range DefinitionFrequency RangeSubcarrier SpacingFR1450MHz - 6000MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0055] As described above, the numerical value of the frequency range of the NR system can be changed. For example, FR1 may include a band from 410 MHz to 7125 MHz, as shown in Table 2 below. That is, FR1 may include frequency bands above 6 GHz (or 5850, 5900, 5925 MHz, etc.). For example, the frequency bands above 6 GHz (or 5850, 5900, 5925 MHz, etc.) included within FR1 may include unlicensed bands. Unlicensed bands can be used for various purposes, such as for communications for vehicles (e.g., autonomous driving).

[0056] Frequency Range DefinitionFrequency RangeSubcarrier SpacingFR1410MHz - 7125MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0057] Here, the wireless communication technology implemented in the wireless device of the present specification may include not only LTE, NR, and 6G, but also narrowband IoT (NB-IoT) for low-power communication. For example, NB-IoT technology may be an example of LPWAN (low power wide area network) technology and may be implemented with standards such as LTE Cat NB1 and / or LTE Cat NB2, and is not limited to the above-described names. Additionally or alternatively, the wireless communication technology implemented in the wireless device of the present specification may perform communication based on LTE-M technology. For example, LTE-M technology may be an example of LPWAN technology and may be called by various names such as eMTC (enhanced MTC). For example, LTE-M technology can be implemented by at least one of various standards such as 1) LTE CAT 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-BL (non-bandwidth limited), 5) LTE-MTC, 6) LTE MTC, and / or 7) LTE M, and is not limited to the above-described names. Additionally or alternatively, the wireless communication technology implemented in the wireless device of the present specification can include at least one of ZigBee, Bluetooth, and / or LPWAN considering low-power communication, and is not limited to the above-described names. For example, ZigBee technology can create PAN (personal area networks) related to small / low-power digital communication based on various standards such as IEEE 802.15.4, and can be called by various names.

[0058] Figure 2 illustrates an example of a wireless device to which the implementation of the present specification is applied.

[0059] In FIG. 2, the first wireless device (100) and / or the second wireless device (200) may be implemented in various forms depending on the use case / service. For example, {the first wireless device (100) and the second wireless device (200)} may correspond to at least one of {the wireless devices (100a to 100f) and the base station (200)}, {the wireless devices (100a to 100f) and the wireless devices (100a to 100f)}, and / or {the base station (200) and the base station (200)} of FIG. 1. The first wireless device (100) and / or the second wireless device (200) may be configured by various components, devices / parts, and / or modules.

[0060] The first wireless device (100) may include at least one transceiver, such as a transceiver (106), at least one processing chip, such as a processing chip (101), and / or one or more antennas (108).

[0061] The processing chip (101) may include at least one processor, such as a processor (102), and at least one memory, such as a memory (104). Additionally and / or alternatively, the memory (104) may be located external to the processing chip (101).

[0062] The processor (102) may control the memory (104) and / or the transceiver (106) and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed herein. For example, the processor (102) may process information in the memory (104) to generate first information / signal and transmit a wireless signal including the first information / signal via the transceiver (106). The processor (102) may receive a wireless signal including second information / signal via the transceiver (106) and store information obtained by processing the second information / signal in the memory (104).

[0063] A memory (104) may be operatively connected to the processor (102). The memory (104) may store various types of information and / or instructions. The memory (104) may store firmware and / or software code (105) that implements code, instructions and / or sets of instructions that, when executed by the processor (102), perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed herein. For example, the firmware and / or software code (105) may implement instructions that, when executed by the processor (102), perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed herein. For example, the firmware and / or software code (105) may control the processor (102) to perform one or more protocols. For example, the firmware and / or software code (105) may control the processor (102) to perform one or more air interface protocol layers.

[0064] Here, the processor (102) and memory (104) may be part of a communication modem / circuit / chip designed to implement a RAT (e.g., LTE or NR). A transceiver (106) may be connected to the processor (102) and may transmit and / or receive wireless signals via one or more antennas (108). Each transceiver (106) may include a transmitter and / or a receiver. The transceiver (106) may be used interchangeably with an RF (radio frequency) unit. In the present specification, the first wireless device (100) may represent a communication modem / circuit / chip.

[0065] The second wireless device (200) may include at least one transceiver, such as a transceiver (206), at least one processing chip, such as a processing chip (201), and / or one or more antennas (208).

[0066] The processing chip (201) may include at least one processor, such as a processor (202), and at least one memory, such as a memory (204). Additionally and / or alternatively, the memory (204) may be located external to the processing chip (201).

[0067] The processor (202) may control the memory (204) and / or the transceiver (206) and may be configured to implement the descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed herein. For example, the processor (202) may process information in the memory (204) to generate third information / signal and transmit a wireless signal including the third information / signal via the transceiver (206). The processor (202) may receive a wireless signal including fourth information / signal via the transceiver (206) and store information obtained by processing the fourth information / signal in the memory (204).

[0068] A memory (204) may be operatively connected to the processor (202). The memory (204) may store various types of information and / or instructions. The memory (204) may store firmware and / or software code (205) that implements instruction codes, commands and / or sets of instructions that, when executed by the processor (202), perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed herein. For example, the firmware and / or software code (205) may implement instructions that, when executed by the processor (202), perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed herein. For example, the firmware and / or software code (205) may control the processor (202) to perform one or more protocols. For example, the firmware and / or software code (205) may control the processor (202) to perform one or more air interface protocol layers.

[0069] Here, the processor (202) and memory (204) may be part of a communication modem / circuit / chip designed to implement a RAT (e.g., LTE or NR). A transceiver (206) may be connected to the processor (202) and may transmit and / or receive wireless signals via one or more antennas (208). Each transceiver (206) may include a transmitter and / or a receiver. The transceiver (206) may be used interchangeably with the RF unit. In the present specification, the second wireless device (200) may represent a communication modem / circuit / chip.

[0070] Hereinafter, hardware elements of the wireless device (100, 200) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (102, 202). For example, one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as a physical (PHY) layer, a media access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, a radio resource control (RRC) layer, and a service data adaptation protocol (SDAP) layer). One or more processors (102, 202) may generate one or more protocol data units (PDUs), one or more service data units (SDUs), messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed herein. One or more processors (102, 202) can generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data or information according to the descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed herein and provide the signals to one or more transceivers (106, 206). One or more processors (102, 202) can receive signals (e.g., baseband signals) from one or more transceivers (106, 206) and obtain PDUs, SDUs, messages, control information, data or information according to the descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed herein.

[0071] The one or more processors (102, 202) may be referred to as a controller, a microcontroller, a microprocessor, and / or a microcomputer. The one or more processors (102, 202) may be implemented by hardware, firmware, software, and / or a combination thereof. For example, one or more application specific integrated circuits (ASICs), one or more digital signal processors (DSPs), one or more digital signal processing devices (DSPDs), one or more programmable logic devices (PLDs), and / or one or more field programmable gate arrays (FPGAs) may be included in the one or more processors (102, 202). For example, the one or more processors (102, 202) may be configured by a set of a communication control processor, an application processor (AP), an electronic control unit (ECU), a central processing unit (CPU), a graphic processing unit (GPU), and a memory control processor.

[0072] One or more memories (104, 204) may be coupled to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. The one or more memories (104, 204) may be configured as random access memory (RAM), dynamic RAM (DRAM), read-only memory (ROM), erasable programmable ROM (EPROM), flash memory, volatile memory, nonvolatile memory, hard drive, register, cache memory, computer-readable storage media, and / or combinations thereof. The one or more memories (104, 204) may be located internally and / or externally to the one or more processors (102, 202). Additionally, the one or more memories (104, 204) may be coupled to the one or more processors (102, 202) via various technologies, such as wired or wireless connections.

[0073] One or more transceivers (106, 206) can transmit user data, control information, wireless signals / channels, etc., referred to in the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed herein to one or more other devices. One or more transceivers (106, 206) can receive user data, control information, wireless signals / channels, etc., referred to in the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed herein from one or more other devices. For example, one or more transceivers (106, 206) can be coupled to one or more processors (102, 202) and can transmit and receive wireless signals. For example, one or more processors (102, 202) can control one or more transceivers (106, 206) to transmit user data, control information, wireless signals, etc., to one or more other devices. Additionally, one or more processors (102, 202) may control one or more transceivers (106, 206) to receive user data, control information, wireless signals, etc. from one or more other devices.

[0074] One or more transceivers (106, 206) may be coupled to one or more antennas (108, 208). Additionally and / or alternatively, one or more transceivers (106, 206) may include one or more antennas (108, 208). One or more transceivers (106, 206) may be configured to transmit and receive user data, control information, wireless signals / channels, etc., as described in the descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed herein via one or more antennas (108, 208). In the present specification, one or more antennas (108, 208) may be multiple physical antennas or multiple logical antennas (e.g., antenna ports).

[0075] One or more transceivers (106, 206) may convert received user data, control information, wireless signals / channels, etc. from RF band signals to baseband signals in order to process the received user data, control information, wireless signals / channels, etc. using one or more processors (102, 202). One or more transceivers (106, 206) may convert processed user data, control information, wireless signals / channels, etc. from baseband signals to RF band signals using one or more processors (102, 202). For this purpose, one or more transceivers (106, 206) may include an (analog) oscillator and / or a filter. For example, one or more transceivers (106, 206) may up-convert an OFDM baseband signal to an OFDM signal via an (analog) oscillator and / or filter under the control of one or more processors (102, 202) and transmit the up-converted OFDM signal at a carrier frequency. One or more transceivers (106, 206) may receive an OFDM signal at a carrier frequency and down-convert the OFDM signal to an OFDM baseband signal via an (analog) oscillator and / or filter under the control of one or more processors (102, 202).

[0076] Although not illustrated in FIG. 2, the wireless device (100, 200) may further include additional components. The additional components (140) may be configured in various ways depending on the type of the wireless device (100, 200). For example, the additional components (140) may include at least one of a power unit / battery, an input / output (I / O) device (e.g., an audio I / O port, a video I / O port), a driving device, and a computing device. The additional components (140) may be connected to one or more processors (102, 202) via various technologies, such as a wired or wireless connection.

[0077] In the implementation of the present specification, a UE can operate as a transmitter in the uplink (UL) and as a receiver in the downlink (DL). In the implementation of the present specification, a base station can operate as a receiver in the UL and as a transmitter in the DL. For the sake of convenience of description, it is mainly assumed below that the first wireless device (100) operates as a UE and the second wireless device (200) operates as a base station. For example, a processor (102) connected to, mounted on, or released in the first wireless device (100) can be configured to perform UE operations according to the implementation of the present specification or to control a transceiver (106) to perform UE operations according to the implementation of the present specification. A processor (202) connected to, mounted on, or released in the second wireless device (200) can be configured to perform base station operations according to the implementation of the present specification or to control a transceiver (206) to perform base station operations according to the implementation of the present specification.

[0078] In this specification, a base station may be referred to as a Node B, an eNode B (eNB), or a gNB.

[0079] Figure 3 shows an example of a UE to which the implementation of this specification is applied.

[0080] Referring to FIG. 3, the UE (100) can correspond to the first wireless device (100) of FIG. 2.

[0081] The UE (100) includes a processor (102), memory (104), a transceiver (106), one or more antennas (108), a power management module (141), a battery (142), a display (143), a keypad (144), a SIM (Subscriber Identification Module) card (145), a speaker (146), and a microphone (147).

[0082] The processor (102) may be configured to implement the descriptions, functions, procedures, proposals, methods and / or flowcharts disclosed herein. The processor (102) may be configured to control one or more other components of the UE (100) to implement the descriptions, functions, procedures, proposals, methods and / or flowcharts disclosed herein. A layer of a radio interface protocol may be implemented in the processor (102). The processor (102) may include an ASIC, other chipsets, logic circuits and / or data processing devices. The processor (102) may be an application processor. The processor (102) may include at least one of a DSP, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), and a modem (modulator and demodulator). An example of the processor (102) is the SNAPDRAGON manufactured by Qualcomm®. TM Series processors, EXYNOS made by Samsung® TM Series processors, A-series processors made by Apple®, HELIO made by MediaTek® TM ATOM series processors made by Intel® TM It can be found in the series processors or the corresponding next-generation processors.

[0083] Memory (104) is operatively coupled to the processor (102) and stores various information for operating the processor (102). Memory (104) may include ROM, RAM, flash memory, memory cards, storage media, and / or other storage devices. When the implementation is implemented in software, the techniques described herein may be implemented using modules (e.g., procedures, functions, etc.) that perform the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein. The modules may be stored in memory (104) and executed by the processor (102). Memory (104) may be implemented within the processor (102) or external to the processor (102), in which case it may be communicatively coupled to the processor (102) via various methods known in the art.

[0084] A transceiver (106) is operably coupled to the processor (102) and transmits and / or receives a radio signal. The transceiver (106) includes a transmitter and a receiver. The transceiver (106) may include a baseband circuit for processing a radio frequency signal. The transceiver (106) controls one or more antennas (108) to transmit and / or receive a radio signal.

[0085] The power management module (141) manages the power of the processor (102) and / or the transceiver (106). The battery (142) supplies power to the power management module (141).

[0086] The display (143) outputs the results processed by the processor (102). The keypad (144) receives input to be used by the processor (102). The keypad (144) can be displayed on the display (143).

[0087] A SIM card (145) is an integrated circuit that securely stores an International Mobile Subscriber Identity (IMSI) and associated keys, and is used to identify and authenticate subscribers in mobile devices such as mobile phones and computers. Additionally, many SIM cards can store contact information.

[0088] The speaker (146) outputs sound-related results processed by the processor (102). The microphone (147) receives sound-related input to be used by the processor (102).

[0089] Figure 4 is a structural diagram of a next-generation mobile communications network.

[0090] 5GC (5G Core) may include various components, and in FIG. 5, some of them include AMF (Access and Mobility Management Function) (410), SMF (Session Management Function) (420), PCF (Policy Control Function) (430), UPF (User Plane Function) (440), AF (Application Function) (450), UDM (Unified Data Management) (460), and N3IWF (Non-3GPP (3rd Generation Partnership Project) Inter Working Function) (490).

[0091] The UE (100) is connected to a data network via UPF (440) through a Next Generation Radio Access Network (NG-RAN) including a gNB (20).

[0092] The UE (100) can also receive data services via untrusted non-3GPP access, such as a Wireless Local Area Network (WLAN). To connect the non-3GPP access to the core network, an N3IWF (490) may be deployed.

[0093] The illustrated N3IWF (490) performs the function of managing interworking between non-3GPP access and 5G system. When UE (100) is connected to non-3GPP access (e.g., WiFi, referred to as IEEE 801.11), UE (100) can be connected to 5G system through N3IWF (490). N3IWF (490) performs control signaling with AMF (410) and is connected to UPF (440) through N3 interface for data transmission.

[0094] The illustrated AMF (410) can manage access and mobility in a 5G system. The AMF (410) can perform functions to manage Non-Access Stratum (NAS) security. The AMF (410) can perform functions to handle mobility in the idle state.

[0095] The illustrated UPF (440) is a type of gateway through which user data is transmitted and received. The UPF node (440) can perform all or part of the user plane functions of the S-GW (Serving Gateway) and P-GW (Packet Data Network Gateway) of 4th generation mobile communications.

[0096] The UPF (440) acts as a boundary point between the next generation radio access network (NG-RAN) and the core network, and is an element that maintains a data path between the gNB (20) and the SMF (420). In addition, when the UE (100) moves across the area served by the gNB (20), the UPF (440) acts as a mobility anchor point. The UPF (440) can perform a function of handling PDUs. For mobility within the NG-RAN (Next Generation-Radio Access Network defined after 3GPP Release-15), the UPF can route packets. Additionally, the UPF (440) may also function as an anchor point for mobility with other 3GPP networks (RANs defined before 3GPP Release-15, e.g., UTRAN, E-UTRAN (Evolved-UMTS (Universal Mobile Telecommunications System) Terrestrial Radio Access Network)) or GERAN (GSM (Global System for Mobile Communication) / EDGE (Enhanced Data rates for Global Evolution) Radio Access Network). The UPF (440) may correspond to a termination point of a data interface toward a data network.

[0097] The illustrated PCF (430) is a node that controls the business operator's policy.

[0098] The illustrated AF (450) is a server for providing various services to the UE (100).

[0099] The illustrated UDM (460) is a type of server that manages subscriber information, such as the HSS (Home Subscriber Server) of 4th generation mobile communications. The UDM (460) stores and manages the subscriber information in a Unified Data Repository (UDR).

[0100] The illustrated SMF (420) can perform the function of allocating an IP (Internet Protocol) address of the UE. In addition, the SMF (420) can control a PDU (protocol data unit) session.

[0101] For reference, the drawing symbols for AMF (410), SMF (420), PCF (430), UPF (440), AF (450), UDM (460), N3IWF (490), gNB (20), or UE (100) may be omitted below.

[0102] 5G mobile communications support multiple numerologies, or subcarrier spacing (SCS), to support diverse 5G services. For example, a 15 kHz SCS supports wide areas in traditional cellular bands. A 30 kHz / 60 kHz SCS supports dense urban environments, lower latency, and wider carrier bandwidth. An SCS of 60 kHz or higher supports bandwidths greater than 24.25 GHz to overcome phase noise.

[0103] Figure 5 shows an example of a 5G system structure to which the implementation of this specification is applied.

[0104] The 5G system (5GS; 5G system) structure consists of the following network functions (NF; Network Function).

[0105] - AUSF (Authentication Server Function)

[0106] - AMF (Access and Mobility Management Function)

[0107] - DN (Data Network), 예를 들어 운영자 서비스, 인터넷 접속 또는 타사 서비스

[0108] - USDF (Unstructured Data Storage Function)

[0109] - NEF (Network Exposure Function)

[0110] - I-NEF (Intermediate NEF)

[0111] - NRF (Network Repository Function)

[0112] - NSSF (Network Slice Selection Function)

[0113] - PCF (Policy Control Function)

[0114] - SMF (Session Management Function)

[0115] - UDM (Unified Data Management)

[0116] - UDR (Unified Data Repository)

[0117] - UPF (User Plane Function)

[0118] - UCMF (UE radio Capability Management Function)

[0119] - AF (Application Function)

[0120] - UE (User Equipment)

[0121] - (R)AN ((Radio) Access Network)

[0122] - 5G-EIR (5G-Equipment Identity Register)

[0123] - NWDAF (Network Data Analytics Function)

[0124] - CHF (CHarging Function)

[0125] Additionally, the following network features may be considered:

[0126] - N3IWF (Non-3GPP InterWorking Function)

[0127] - TNGF (Trusted Non-3GPP Gateway Function)

[0128] - W-AGF (Wireline Access Gateway Function)

[0129] Figure 5 illustrates the 5G system architecture for a non-roaming case using a reference point representation showing how various network functions interact with each other.

[0130] For clarity of the point-to-point diagram in Figure 5, UDSF, NEF, and NRF are not illustrated. However, all network functions shown can interact with UDSF, UDR, NEF, and NRF as needed.

[0131] For clarity, the connection between UDR and other NFs (e.g., PCF) is not shown in Fig. 4. For clarity, the connection between NWDAF and other NFs (e.g., PCF) is not shown in Fig. 4.

[0132] The 5G system architecture includes the following benchmarks:

[0133] - N1: Reference point between UE and AMF.

[0134] - N2: Reference point between (R)AN and AMF.

[0135] - N3: Reference point between (R)AN and UPF.

[0136] - N4: Reference point between SMF and UPF.

[0137] - N6: Reference point between UPF and data network.

[0138] - N9: Reference point between two UPFs.

[0139] The following benchmarks illustrate the interactions that exist between NF services in NF.

[0140] - N5: Reference point between PCF and AF.

[0141] - N7: Reference point between SMF and PCF.

[0142] - N8: Reference point between UDM and AMF.

[0143] - N10: Reference point between UDM and SMF.

[0144] - N11: Reference point between AMF and SMF.

[0145] - N12: Reference point between AMF and AUSF.

[0146] - N13: Reference point between UDM and AUSF.

[0147] - N14: Reference point between two AMFs.

[0148] - N15: Reference point between PCF and AMF for non-roaming scenarios, and reference point between PCF and AMF of visited network for roaming scenarios.

[0149] - N16: Reference point between two SMFs (in case of roaming, between the SMF of the visited network and the SMF of the home network)

[0150] - N22: Reference point between AMF and NSSF.

[0151] In some cases, two NFs may need to be interconnected to serve a UE.

[0152] <Non-Terrestrial Networks >

[0153] NTN (Non-Terrestrial Network) refers to a network or network segment that uses RF resources mounted on satellites (or UAS platforms).

[0154] There are two common scenarios for NTNs that provide access to user equipment: transparent payload and regenerative payload.

[0155] NTNs are typically characterized by the following elements:

[0156] - One or more sat-gateways connecting the NTN to the public data network.

[0157] - GEO satellites are served by one or more satellite gateways deployed across the satellite's target coverage area (e.g., regional or continental coverage). We assume that a UE in a cell is served by only one sat-gateway.

[0158] Non-GEO satellites that provide continuous service from one or more satellite gateways at a time. The system ensures service and feeder link continuity between consecutively serving satellite gateways with sufficient time duration to allow for mobile anchoring and handover.

[0159] - Feeder link or wireless link between the satellite gateway and the satellite (or UAS platform).

[0160] - Service link or wireless link between user equipment and satellite (or UAS platform).

[0161] A satellite (or UAS platform) capable of implementing transparent or regenerative (including onboard processing) payloads. The satellite (or UAS platform) typically generates multiple beams for a designated service area, depending on its field of view. The beam's footprint is typically elliptical. The satellite's (or UAS platform's) field of view varies depending on the onboard antenna diagram and minimum elevation angle.

[0162] - Transparent payload: Radio frequency filtering, frequency conversion, and amplification. Therefore, the waveform signal repeated by the payload remains unchanged.

[0163] Regenerative payload: Radio frequency filtering, frequency conversion and amplification, demodulation / decoding, switching and / or routing, and coding / modulation. This is essentially equivalent to embedding all or part of a base station function (e.g., gNB) on a satellite (or UAS platform).

[0164] - Optionally, for satellite constellations, inter-satellite link (ISL) is available. This requires a regenerative payload on the satellite. ISL can operate in RF or wideband.

[0165] - User equipment is serviced by satellites (or UAS platforms) within the target service area.

[0166] For transparent satellites, the satellite amplifies signals transmitted from a ground station (gNB-NTN gateway) and transmits them to the terminal. Regenerative satellites, in addition to signal amplification, perform ground station functions such as routing, coding, modulation, and decoding / demodulation. NTN terminals have GPS capabilities and periodically receive location, time, and velocity information from NTN satellites.

[0167] Describes S&F operation in relation to communications via satellite.

[0168] <S&F (Store and Forward)>

[0169] In satellite-enabled 5G systems, S&F satellite operation is intended to provide delay-tolerant communication services to UEs that are within satellite coverage and have intermittent / transient satellite connectivity (e.g., when the satellite is not connected via a feeder link or is not connected to a terrestrial network via ISL).

[0170] Figure 6 shows an example of basic satellite operation.

[0171] Figure 7 shows an example of S&F satellite operation.

[0172] Figures 6 and 7 illustrate examples of “S&F satellite operation” in contrast to current assumptions for “normal / default satellite operation” of a satellite-enabled 5G system.

[0173] A service link may be a link between a terminal and a satellite, and a feeder link may be a link between a satellite and a base station.

[0174] - In "Normal / Default Satellite Operation" mode, for signaling and data traffic exchange between a UE with satellite access and a remote terrestrial network, the service link and feeder link must be active simultaneously. Therefore, a continuous end-to-end connection path exists between the UE, satellite, and terrestrial network when the UE interacts with the satellite via the service link.

[0175] - In contrast, in the "S&F satellite operation" mode, the end-to-end exchange of signal / data traffic is now handled as a combination of two non-temporally simultaneous steps (step A and step B). In step A, signal / data exchange between the UE and the satellite is performed. This can be performed even if the satellite is not simultaneously connected to the terrestrial network (i.e., the satellite can operate the service link without an active feeder link connection). In step B, a connection is established between the satellite and the terrestrial network, allowing communication between the satellite and the terrestrial network. Thus, the satellite moves from being connected to the UE in step A to being connected to the terrestrial network in step B.

[0176] The concept of "S&F" services is widely used in delay-tolerant and disruption-tolerant networking. In the 3GPP context, a service that can be integrated into an S&F service is SMS, which does not require end-to-end connectivity between endpoints (e.g., one endpoint may be a UE and another endpoint may be an application server). However, connectivity is only required between the endpoints and the SMSC, which acts as an intermediate node responsible for storage and dependency management.

[0177] S&F satellite operation support may be particularly suitable for providing delay-tolerant / non-real-time IoT satellite services using NGSO satellites.

[0178] Transparent and regenerative payloads are:

[0179] - Transparent payload: Electromagnetic waves transmitted from the Earth's surface are converted into electrical signals via the satellite receiving antenna. These signals are channel-filtered and amplified by a low-noise amplifier (LNA). The signals are then frequency-converted. Finally, a high-power amplifier (HPA) transmits the signals to the transmitting antenna, which generates regenerated electromagnetic waves directed toward the Earth's surface where the receiving station is located.

[0180] Regenerative payload: An onboard processor (OBP) is inserted between the LNA and the HPA. This OBP can convert the air interface between the uplink (from Earth to the satellite) and downlink (from the satellite to Earth). This allows it to correct erroneous bits or packets before retransmission, or to route packets between beams. Ultimately, thanks to the OBP (including all functions connected to the gNB CU or DU or CN), all network functions can be implemented at the expense of power and mass.

[0181] To support S&F functionality, a regenerative satellite (a satellite that can act as a ground base station) may be required, rather than a transparent satellite that simply forwards the terminal's signal.

[0182] After a terminal is connected to a 5GC via a satellite, if the satellite (or terminal) moves out of the satellite's coverage, the terminal transitions to the CM-IDLE (RRC_IDLE) state. Subsequently, when the terminal enters coverage of the same satellite or another satellite, it must transition to the CM-CONNECTED (RRC_CONNECTED) state to transmit and receive signaling and data with the satellite.

[0183] When the satellite base station is equipped with only NG-RAN without additional core network functions, RRC_INACTIVE mode (RRC inactive state) can be used to ensure that the terminal remains in CM-CONNECTED state for communication.

[0184] While maintaining a CM-CONNECTED state with the core network, the terminal can utilize RRC_INACTIVE mode with the base station that manages terminal mobility. Then, when there is no data transmission or reception, the terminal operates in 'CM-CONNECTED with RRC_INACTIVE' mode, and when there is data transmission or reception, the terminal can transition to RRC-CONNECTED (RRC connected state) and operate.

[0185] The AMF can obtain satellite coverage information. This information can be provided to the AMF by the network operator for O&M purposes. The AMF can determine whether satellites can cover a specific area at a specific time.

[0186] AMF can support satellite access for UEs with discontinuous coverage using satellite coverage availability information. Satellite coverage availability information can be provided to AMF by O&M.

[0187] Satellite coverage availability information provided to the AMF describes when and where satellite coverage is expected to be available in a given area. Satellite coverage availability information is not specific to a single UE and can be applied by the AMF to all UEs in the area.

[0188] S&F operations primarily target delay-tolerant / non-real-time Internet of Things (IoT) services. For example, existing technologies exist to support IoT devices in 5GS, including Control Plane CIoT 5GS Optimization, a method for transmitting small IoT data via NAS signaling.

[0189] For uplink, terminals in IDLE state transmit IoT data in a Control Plane Service Request (CSR) NAS message. For uplink, terminals in CONNECTED state transmit IoT data in a UL NAS Transport message.

[0190] For the downlink, the network transmits IoT data in DL NAS Transport messages. Without creating user plane resources for the UE within 5GS, the AMF transmits the received IoT data to the data network via the SMF and UPF, or to the AF via the NEF.

[0191] After a terminal connects to a 5GC via a satellite, if the satellite moves and leaves its coverage, the terminal transitions to the CM-IDLE (RRC_IDLE) state. Subsequently, when the terminal enters coverage of the same satellite or another satellite, the terminal must transition to the CM-CONNECTED (RRC_CONNECTED) state to transmit and receive signaling and data with the satellite.

[0192] If the satellite base station only has a base station (NG-RAN) without additional core network functions, the terminal can use RRC_INACTIVE mode to remain in a CM-CONNECTED state for communication. This allows the terminal to maintain a CM-CONNECTED state with the core network, and the base station to manage terminal mobility.

[0193] When there is no data transmission or reception from the terminal, the terminal operates in CM-CONNECTED and RRC_INACTIVE modes (states). To transmit or receive data, the terminal can transition to RRC-CONNECTED.

[0194] <Resuming connection from RRC_INACTIVE by network>

[0195] Figure 8 shows an example of connection resumption in RRC_INACTIVE by the network.

[0196] When the terminal is in CM-CONNECTED (CM-CONNECTED with RRC_INACTIVE) state through CN-based MT (Mobile Terminating) communication processing, high-latency communication is applied.

[0197] Connection resumption in Fig. 8 can be triggered by MT data or N1 procedure of SMF and UPF.

[0198] If the connection resumption in Figure 8 is triggered by another NF (e.g. SMSF, LMF, GMLC), the UPF (or SMF) in Figure 8 may be replaced by that NF (the service operations used by the other NF when communicating with the AMF may be different from the service operations used by the SMF / UPF).

[0199] NG-RAN (i.e. gNB) can perform RAN paging for UE based on N2 message of AMF.

[0200] Step 1a. When downlink data is received and the SMF / UPF is requested to perform buffering, the UPF / SMF confirms to the AMF the possibility of data delivery based on the following:

[0201] - In Namf_MT_EnableUEReachability, SMF can also transmit PPI, ARP and 5QI and / or QFI of the QoS flow of the PDU session that triggered the paging policy differentiation request.

[0202] - While waiting for a UE-triggered connection resumption indication or a rejection response from the AMF (including the expected maximum waiting time), if the SMF has a higher priority (i.e., a higher priority than the priority indicated to the AMF in the previous Namf_MT_EnableUEReachability (i.e., a higher priority than the priority indicated to the AMF in the previous Namf_MT_EnableUEReachability (i.e., a higher ARP priority level)) or the SMF derives different paging policy indicators based on additional data notifications, the SMF calls a new Namf_MT_EnableUEReachability to the AMF indicating the higher priority or different paging policy indicators. The information contained in the new Namf_MT_EnableUEReachability request overrides the information in the previous Namf_MT_EnableUEReachability request stored in the AMF. If the SMF receives an additional data notification message due to additional data packets for other QoS Flows associated with the same or lower priority than the priority indicated to the AMF in the previous Namf_MT_EnableUEReachability or if the SMF receives a second Namf_MT_EnableUEReachability request indicating a higher priority. If additional downlink data packets are received for this UE after sending the Namf_MT_EnableUEReachability message, the SMF buffers these downlink data packets and does not send a new Namf_MT_EnableUEReachability message.

[0203] - AMF determines whether the UE is reachable based on the stored eDRX value for RRC_INACTIVE state provided by NG-RAN. If the UE is not reachable, AMF stores the information received in the Namf_MT_EnableUEReachability request and provides the expected maximum waiting time in the response message based on the eDRX value for RRC_INACTIVE in AMF (steps 2-5 are postponed until the UE is reachable). If the UE is considered reachable, step 2 is executed immediately.

[0204] This processing is similar to CM-IDLE in eDRX. When AMF provides the expected maximum waiting time, it can take into account the time required for RRC-level procedures (e.g., RRC RNA update procedures) when the UE wakes up from an eDRX cycle.

[0205] Step 2. If the AMF determines that the UE can be reached, the AMF sends an N2 DL Data Notification message to the NG-RAN, requesting the resumption of the UE's RRC connection. The AMF may include the PPI, ARP, and 5QI and / or QFI parameters of the QoS flow of the PDU Session ID in the N2 DL Data Notification message to trigger and activate RAN paging.

[0206] Step 3. NG-RAN performs RAN paging for the UE considering the parameters provided by AMF.

[0207] Step 4. When the UE receives RAN paging, it initiates a UE-triggered connection resumption procedure and the NG-RAN notifies the CN including an N2 notification.

[0208] Step 5. UPF triggers a downlink data transmission if there is one. AMF transmits a downlink NAS message if there is one.

[0209] In high latency communication, when UPF performs MT data buffering, AMF can forward N2 message to RAN to check reachability of UE in RRC_INACTIVE state.

[0210] In an S&F operation scenario using RRC_INACTIVE mode, if MT data is available, the SMF can request the AMF to the NG-RAN for reachability of the UE. The AMF can then confirm the reachability of the UE to the RAN via an N2 message. The AMF can forward the user data to the NG-RAN that has the context of the UE, or, if Control Plane CIoT 5GS Optimization is used, forward the data to the NG-RAN via the control plane.

[0211] If the satellite is equipped with NG-RAN (regenerative satellite), AMF cannot know whether the satellite has a feeder link to a ground gateway (base station).

[0212] And, if data forwarding to the satellite is not possible, SMF / UPF has no way of knowing how long it will have to buffer the data.

[0213] To address these issues, a method may be proposed for AMF to support S&F operations with respect to the satellite's feeder link (e.g., Feeder Link Availability Information).

[0214] The method of selecting NG-RAN for store and forward operation of the proposed satellite may be composed of a combination of one or more operations / configurations / steps disclosed herein.

[0215] These procedures and / or messages may use existing procedures / messages, may extend existing procedures / messages, or may define and use new procedures / messages.

[0216] The satellite in this specification may be a satellite equipped with a base station function.

[0217] The satellite in this specification may be a regenerative satellite.

[0218] In this specification, S&F and store and forward are used interchangeably.

[0219] In this specification, UE (User Equipment) and terminal are used interchangeably.

[0220] This specification mainly describes the proposed content.

[0221] When the satellite serving a terminal changes, the network can ensure that the terminal can always establish an RRC connection (RRC_CONNECTION) through registration. In this case, the RRC connection procedure can be implemented through an inter-satellite link (ISL). Depending on the implementation method, an Xn interface can be raised on the ISL so that the base station can relay NAS signals. Alternatively, the ISL can be used as a transport layer, and an N2 interface can be implemented directly between the satellite and the AMF.

[0222] Through registration, the core network can receive the UE context of the terminal.

[0223] AMF can set a periodic registration timer for the terminal based on satellite coverage information. Based on this, the terminal can perform registration whenever the satellite changes.

[0224] In this specification, it is assumed and described that the Xn interface between satellites is implemented via ISL and that each satellite transmits signaling to the AMF via the Xn interface. To this end, it is assumed that each satellite has routing information for transmitting signaling to the AMF.

[0225] Alternatively, the satellite can establish a direct N2 interface via a multi-hop ISL between the satellite and the AMF.

[0226] For S&F operations, we assume that IoT terminals are not mobile. Alternatively, even if the terminals are mobile, we assume that the network (e.g., AMF) can determine when the terminal enters satellite coverage based on information about the terminal's mobility.

[0227] Satellites may have an inter-satellite Xn interface via ISL. Terminals can register and create PDU sessions via ISL. Terminals can transmit data via S&F mode.

[0228] Data transmission in this specification may be data transmission through the Control Plane via Control Plane 5GS CIoT Optimisation operations.

[0229] When a terminal transmits data through the control plane in an RRC connection (RRC_CONNECTED) state, the satellite NG-RAN cannot know whether the UL NAS Transport message included in the RRC message includes user data. Therefore, the terminal can include an indication indicating whether user data is included in the RRC message.

[0230] A satellite can operate in an RRC inactive state (RRC_INACTIVE mode) for a specific terminal. In this state, the satellite can retrieve the UE context from the NG-RAN that contains the UE context for the specific terminal. This then transitions to an RRC connected state. After this, the terminal and satellite can transmit and receive data.

[0231] AMF can obtain satellite coverage availability information and information about the satellite's feeder link (e.g., Feeder Link Availability Information).

[0232] The aforementioned information may be provisioned to the AMF through O&M. Alternatively, the aforementioned information may be received from an external AF via the control plane. Alternatively, the aforementioned information may be received from an additional NF that manages the information.

[0233] Feeder Link Availability Information may include the following information:

[0234] - ID and orbit information of each satellite

[0235] - Information on gateways connected to each AMF and location information of the gateways (Cell, TA, Geographical Location)

[0236] - Time-based connectable gateways for each satellite

[0237] Based on the above information, AMF can know the time when each satellite can connect to the feeder link through the ground gateway connected to each AMF.

[0238] Based on Feeder Link Availability Information and Satellite Coverage Availability Information, each AMF can know the time it will take to connect to its associated gateway before the satellite covers a specific area.

[0239] That is, each AMF can know which area will be covered and at what time the satellite passing through its connected gateway will cover in the future.

[0240] Then, when MT data needs to be forwarded, AMF can know whether a particular satellite passing through the gateway will cover the UE or not, and based on this, AMF can decide whether to forward the terminal's MT data to that satellite.

[0241] AMF can obtain the aforementioned feeder link availability information (and / or satellite coverage availability information) in the following ways:

[0242] - How to receive from Q&M: AMF can receive feeder link availability information from O&M along with Satellite Coverage Availability Information.

[0243] - Receiving from an external server: AMF can receive feeder link availability information from an external server (AF) by defining a new event through Event Exposure. Each AMF can receive feeder link availability information through direct communication with the AF.

[0244] - Retrieving from a new NF: A new NF (Network Function) can be defined to manage feeder link availability information. Each AMF can retrieve feeder link availability information from the new NF through a newly defined service operation or a new event.

[0245] The method performed by the AMF upon receiving feeder link availability information through the three methods described above is described below.

[0246] The first and second embodiments described below can be performed in combination with each other.

[0247] 1. First Example

[0248] Figures 9, 10 and 11 illustrate examples of procedures according to the first embodiment of the present specification.

[0249] For S&F for MT data, data can be transmitted using the method of 'UPF anchored Mobile Terminated Data Transport in Control Plane CIoT 5GS Optimisation' in 4.24.2 of TS 23.502 v18.2.0.

[0250] Alternatively, data can be transmitted via a common user plane. Data buffering on the satellite is assumed to be performed by the satellite's NG-RAN.

[0251] Step 1a. UPF can notify the SMF of the receipt of downlink data (MT data) by sending a data notification message.

[0252] Step 1b. SMF can send an ACK for the data notification message to UPF.

[0253] Step 2. If data buffering is set in SMF / UPF, SMF can check with AMF whether data transmission is possible.

[0254] SMF can request AMF to check the reachability of the terminal (Namf_MT_EnableUEReachability req).

[0255] Step 3. If the AMF knows that the terminal supports S&F, based on the Satellite Coverage Availability Information and / or Feeder Link Availability Information, the AMF can determine whether there is a feeder link between the gateway (the gateway currently associated with the AMF) and the satellite (the satellite with which the AMF has an association).

[0256] Based on Feeder Link Availability Information, the AMF can determine whether a feeder link between a gateway (the gateway currently connected to it) and a satellite (the satellite with which it has an association) is connected. Furthermore, based on Feeder Link Availability Information, the AMF can estimate the expected time when the feeder link will be connected.

[0257] Based on Satellite Coverage Availability Information, the AMF can determine whether a terminal is within the coverage of a given satellite. In other words, based on Satellite Coverage Availability Information, the AMF can determine whether a service link (the link between the terminal and the satellite) is connected. Furthermore, based on Satellite Coverage Availability Information, the AMF can determine the expected time when the service link will be connected.

[0258] Step 4a. If AMF determines that there is a feeder link between the satellite and the gateway (if connection is currently possible via the feeder link)

[0259] If the AMF determines that the satellite and gateway for data forwarding to the terminal are currently connected and the terminal is within satellite coverage, the AMF can send a response message to the SMF, indicating that the terminal is reachable. Based on this, the SMF can trigger data forwarding to the UPF.

[0260] If the AMF determines that a feeder link exists but the terminal is not in satellite coverage (the feeder link is connected but the service link is not), the AMF may send a response message to the SMF indicating that the satellite is capable of buffering data (it may later determine that the satellite is not capable of buffering).

[0261] In this case, based on the Satellite Coverage Availability Information, the AMF may include in the response message information about how long the data will be stored on the satellite when transmitting data to the satellite (e.g., the time when the terminal enters the coverage of the satellite, the expected time when the service link is connected).

[0262] The response message may include i) information indicating that a feeder link is connected, ii) information indicating that a service link is not connected, and iii) information about an expected time for the service link to be connected.

[0263] Upon receiving the response message, the SMF can decide whether to i) send the data to the satellite for buffering by the satellite or ii) have the core network perform further buffering.

[0264] If AMF determines that the core network should perform additional buffering, step 4b, described below, may be performed. Otherwise, step 4a may be followed by step 6.

[0265] Step 4b. If AMF determines that there is no feeder link between the satellite and the gateway (if connection is currently not possible via the feeder link),

[0266] When AMF receives an Extended Buffering Support Indication from SMF, based on the time when the satellite will be connected to the gateway, AMF may send a response message (a response to the request for confirmation of reachability of the terminal) to SMF including the Estimated Maximum Wait time (or the time when the satellite will be connected to the gateway).

[0267] Then, SMF can determine the maximum buffering time (Extended Buffering time) based on this.

[0268] SMF can transmit the maximum buffering time to UPF.

[0269] Based on the absence of a feeder link connection, SMF can allow UPF to continue buffering data.

[0270] The UPF may continue to buffer data for the maximum buffering time received from the UPF. After the maximum buffering time has elapsed, the UPF may discard the data.

[0271] If the AMF determines that no satellite has an association with it via the gateway (the gateway currently associated with it), it may send a failure indication to the SMF. In this case, subsequent steps may not be performed.

[0272] Before the extended buffering time expires, the SMF can additionally request the AMF to check the reachability of the terminal (Namf_MT_EnableUEReachability req) (i.e., Step 2 can be performed again).

[0273] SMF may determine that additional data buffering is possible.

[0274] SMF can check if there are satellites available for forwarding by sending a reachability check request.

[0275] Based on the AMF's response, the SMF can decide whether to i) forward the data, ii) continue buffering the data, or iii) discard the data.

[0276] If there is no connection to the feeder link and / or service link, the SMF may decide to discard the data.

[0277] If the SMF decides to discard data, it can send a corresponding instruction to the UPF. Based on this, the UPF can discard the data.

[0278] SMF can set a new maximum buffering time (Extended Buffering time) based on AMF's response and perform the above-mentioned procedure again accordingly.

[0279] Before (or after) the Estimated Maximum Wait time, the satellite may become connected to the gateway and be able to transmit data over the feeder link.

[0280] The SMF may request the AMF to re-verify reachability for the terminal at a point in time based on the Estimated Maximum Wait time (or the time when the satellite will connect to the gateway).

[0281] Step 5. Before the extended buffering time expires, steps 2 to 4 (step 4a or step 4b) can be performed.

[0282] If Step 4a is performed, Step 6 can be performed thereafter.

[0283] If data is transmitted via the User Plan, steps 6a.1 to 6a.6 may be performed.

[0284] If data is transmitted via 'Control Plane CIoT 5GS Optimisation', steps 6b.1 to 6b.4 may be performed.

[0285] Step 6a. If data is transmitted via the User Plane

[0286] Step 6a.1. SMF can send Namf_Communication_N1N2Message Transfer to AMF.

[0287] In case the response message that AMF transmits to SMF in Step 4a includes 'information on how long data will be stored in the satellite when transmitting data to the satellite' (e.g., time when the terminal enters the coverage of the satellite) (hereinafter, service link connection expected time information), the information may be included in the N2 SM information in the Namf_Communication_N1N2Message Transfer.

[0288] Step 6a.2. AMF can send an N2 message (e.g. PDU SESSION RESOURCE MODIFY REQUEST) to the satellite (NG-RAN Node).

[0289] If the N2 SM information in the Namf_Communication_N1N2Message Transfer received from the SMF includes service link connection expected time information, the N2 message may include N2 SM information including the service link connection expected time information. Then, the satellite can determine when to request paging (RAN paging in step 9a) to the terminal.

[0290] Step 6a.3. The satellite can transmit an N2 message response to the AMF.

[0291] Step 6a.4. AMF can send Nsmf_PDUSession_UpdateSMContext to SMF.

[0292] Nsmf_PDUSession_UpdateSMContext may contain an ACK for the N2 SM information in Step 6a.1.

[0293] Step 6a.5. SMF can send N4 session modification to UPF.

[0294] SMF can trigger transmission of data (downlink data) to UPF.

[0295] Step 6a.6. The UPF can transmit user plane PDUs (data) to the satellite.

[0296] UPF can transmit data to satellites.

[0297] Step 6b. When data is transmitted via 'Control Plane CIoT 5GS Optimisation'

[0298] Step 6b.1. SMF and UPF can perform N4 session modification procedures.

[0299] SMF can trigger transmission of data (downlink data) to UPF.

[0300] Step 6b.2. UPF can forward data (downlink data) to SMF.

[0301] Step 6b.3. SMF can send Namf_Communication_N1N2MessageTransfer from UPF to AMF.

[0302] The above Namf_Communication_N1N2MessageTransfer may include data and PDU session ID.

[0303] Step 6b.4. AMF can transmit NAS messages (NAS PDUs) containing data to the satellite.

[0304] AMF can recognize that there is no service link to the terminal based on satellite coverage availability information.

[0305] If the AMF recognizes that there is no service link, the NAS message may include the service link connection expected time information described above. The satellite can then determine when to request paging (RAN paging in step 9a) from the terminal.

[0306] Step 7. The satellite can store the received data (user data).

[0307] Step 8. The terminal can enter the satellite's coverage area. The satellite can determine that the terminal has entered the satellite's coverage area based on the information received in steps 6a.2 and 6b.4 (the service link connection time information described above).

[0308] Step 9. The satellite can perform paging. The terminal can perform the RRC Resume procedure via RRCResumeRequest, as described in 9.2.2.4.1 of TS 38.300 v17.5.0. The resume procedure can be applied as described in Figure 8.

[0309] The satellite can verify the base station ID through the terminal's I-RNTI (Inactive Radio Network Temporary Identifier) ​​information and obtain the UE context from Satellite A (the satellite that previously served the terminal). If the satellite has a UE context, the process of obtaining the UE context can be omitted.

[0310] When RRC Resume is completed, the terminal can enter the RRC connected (RRC_CONNECTED) state.

[0311] 'CM_CONNECTED & RRC_INACTIVE' state can be changed to 'CM_CONNECTED & RRC_ CONNECTED' state.

[0312] Step 10. The satellite can forward the stored data to the terminal.

[0313] Step 10a. Data can be transmitted to the terminal via user plane PDU.

[0314] Step 10b. If 'Control Plane CIoT 5GS Optimization' is used, data can be transmitted to the terminal via RRC DL messages.

[0315] 2. Second Example

[0316] Figure 12 shows an example of a procedure following the second embodiment of the present specification.

[0317] Figure 12 shows the contents of step 6.

[0318] Steps 1 to 5 can be applied to the contents of the first embodiment.

[0319] From Step 7 onwards, the contents of the first embodiment can be applied.

[0320] The second embodiment is related to Step 6 and is described below.

[0321] The second embodiment can be implemented when there is a connection to the feeder link and no connection to the service link.

[0322] Satellites have limited resources to buffer data.

[0323] Therefore, even if the SMF confirms the connection of the feeder link with the satellite from the AMF, a process may be needed to check whether the satellite can buffer the data before transmitting the data to the satellite.

[0324] AMF / SMF can provide additional support information to the satellite. Based on this additional support information, the satellite can determine whether data can be buffered and stored until it is delivered to the terminal.

[0325] The satellite can transmit its storage availability decision to the SMF. Based on this, the SMF can decide whether to transmit data to the satellite.

[0326] The satellite can receive the following information from the AMF / SMF and decide whether to store the data based on this information. The following information can be transmitted from the SMF to the AMF via step 6a.1 (or step 6b.3) of Example 2. The following information can then be transmitted from the AMF to the satellite:

[0327] - Whether data buffering is required

[0328] - Time until the terminal enters satellite coverage (time to buffer)

[0329] - Size of data to be buffered

[0330] The satellite may decide whether to buffer (or be able to buffer) data by considering the following information in addition to the aforementioned information:

[0331] - Capacity for buffering data storage on satellite

[0332] The satellite may transmit information to the AMF regarding whether data is stored (e.g., whether the satellite buffers data or whether the satellite can buffer data). The AMF may transmit information to the SMF regarding whether the satellite stores data (e.g., whether the satellite buffers data or whether the satellite can buffer data). This procedure may be performed through step 6a.4 (or step 6b.6) of Embodiment 2.

[0333] Before the SMF transmits data to the satellite base station to be buffered, the SMF can provide additional information to the satellite and receive information from the satellite about whether to buffer.

[0334] If data is transmitted via the User Plan, steps 6a.1 to 6a.6 may be performed.

[0335] If data is transmitted via 'Control Plane CIoT 5GS Optimisation', steps 6b.1 to 6b.6 may be performed.

[0336] Through Steps 1-5, the AMF can determine whether the feeder link is connected and whether the service link is disconnected. Furthermore, through Steps 1-5, the AMF can transmit this information to the SMF.

[0337] SMF can determine buffering on the satellite.

[0338] Step 6a. If data is transmitted via the User Plane

[0339] Step 6a.1. SMF can send Namf_Communication_N1N2Message Transfer to AMF.

[0340] In case the response message that AMF transmits to SMF in Step 4a includes 'information on how long data will be stored in the satellite when transmitting data to the satellite' (e.g., time when the terminal enters the coverage of the satellite) (hereinafter, service link connection expected time information), the information may be included in the N2 SM information in the Namf_Communication_N1N2Message Transfer.

[0341] The N2 SM information of Namf_Communication_N1N2Message Transfer may include information that buffering is required on the satellite and the size (size) of the data to be buffered.

[0342] Step 6a.2. AMF can send an N2 message (e.g. PDU SESSION RESOURCE MODIFY REQUEST) to the satellite (NG-RAN Node).

[0343] The N2 message may contain information that buffering is required on the satellite and the size (size) of the data to be buffered.

[0344] If the N2 SM information in the Namf_Communication_N1N2Message Transfer received from the SMF includes service link connection expected time information, the N2 message may include N2 SM information including the service link connection expected time information. Then, the satellite can determine when to request paging (RAN paging in step 9a) to the terminal.

[0345] Alternatively, even if the N2 SM information in the Namf_Communication_N1N2Message Transfer received from the SMF does not include service link connection expected time information, the AMF can recognize that there is no service link to the terminal and individually determine the service link connection expected time (service link connection expected time information). In this case, the service link connection expected time information can be included in the N2 message.

[0346] Based on the aforementioned service link connection time information, information on the need for buffering, information on the size of data requiring buffering, and the satellite's available buffering capacity, the satellite can determine whether to perform (or whether to enable) buffering. This decision can be communicated to the SMF via Steps 6a.3 and 6a.4.

[0347] If the satellite decides to buffer data, it can buffer the data upon receiving it. Once the service link is established, the satellite can transmit the data to the terminal.

[0348] Step 6a.3. The satellite can transmit an N2 message response to the AMF.

[0349] The N2 message response may include whether buffering is performed (possible) on the satellite determined by the satellite.

[0350] Step 6a.4. AMF can send Nsmf_PDUSession_UpdateSMContext to SMF.

[0351] Nsmf_PDUSession_UpdateSMContext may contain an ACK for the N2 SM information in Step 6a.1.

[0352] Nsmf_PDUSession_UpdateSMContext may include whether buffering is performed (possible) on the satellite determined by the satellite.

[0353] If information is received that buffering from the satellite is possible (or will be performed), Step 6a.5 and Step 6a.6 may be performed.

[0354] If information is received from the satellite that buffering is possible (or will be performed), Nsmf_PDUSession_UpdateSMContext may include information that data buffering from the satellite is allowed.

[0355] If the SMF receives information from the satellite that buffering is not possible (or will not be performed), it can instruct the UPF to discard the data.

[0356] Alternatively, if the SMF receives information from the satellite that buffering is not possible (i.e., buffering will not be performed), the SMF may extend the buffering time of the data being buffered by the UPF. In this case, the UPF may buffer the data for an extended period of time. The extended period may be the time it takes for the terminal to enter satellite coverage.

[0357] Step 6a.5. SMF can send N4 session modification to UPF.

[0358] SMF can trigger transmission of data (downlink data) to UPF.

[0359] Step 6a.6. The UPF can transmit user plane PDUs (data) to the satellite.

[0360] UPF can transmit data to satellites.

[0361] Satellites can perform data buffering. Once a service link is established, the satellite can transmit the buffered data to the terminal.

[0362] Step 6b. When data is transmitted via 'Control Plane CIoT 5GS Optimisation'

[0363] Step 6b.1. SMF and UPF can perform N4 session modification procedures.

[0364] Step 6b.2. UPF can forward data (downlink data) to SMF.

[0365] Step 6b.3. SMF can send Namf_Communication_N1N2MessageTransfer to AMF.

[0366] The above Namf_Communication_N1N2MessageTransfer may include data and PDU session ID.

[0367] The above Namf_Communication_N1N2MessageTransfer may include information that buffering is required on the satellite and the size (size) of the data to be buffered.

[0368] Step 6b.4. AMF can transmit NAS messages (NAS PDUs) containing data to the satellite.

[0369] AMF can recognize that there is no service link to the terminal based on satellite coverage availability information.

[0370] If the AMF recognizes that there is no service link, the NAS message may include the aforementioned service link connection expected time information. The satellite can then determine when to request paging (RAN paging in step 9a) from the terminal. The service link connection expected time information may be transmitted to the SMF via step 6b.3 or step 4a.1.

[0371] If the AMF recognizes that there is no service link, the NAS message may include information about the need for buffering on the satellite and the size of the data requiring buffering. This information may have been received from the SMF in step 6b.3. This information may be included in the NAS message based on the SMF's decision to have the satellite perform buffering.

[0372] The AMF can transmit information to the SMF via step 6b.3 (or step 4a.1) that the terminal is out of satellite coverage (indicating that data is buffered on the satellite). Based on this, the SMF can wait for a message indicating that the satellite has successfully buffered the data.

[0373] Based on the information about the expected time of connection to the aforementioned service link, information about the need for buffering on the satellite, information about the size of data requiring buffering, and information about the capacity available for buffering on the satellite, the satellite can decide whether to perform (or whether it is possible to perform) buffering.

[0374] Step 6b.5. The satellite can transmit an N2 Notify message to the AMF.

[0375] If the satellite decides not to perform buffering (data buffering is not allowed on the satellite), the satellite may send an N2 Notify message to the AMF indicating that it cannot buffer and deliver data to the terminal.

[0376] If the satellite determines that it can perform (or is capable of performing) buffering (if data buffering on the satellite is allowed), the satellite may send an N2 Notify message to the AMF indicating that it can buffer and deliver data to the terminal.

[0377] Step 6b.6. AMF can send Nsmf_PDUSession_UpdateSMContext to SMF.

[0378] If the satellite decides not to perform buffering (data buffering is not allowed on the satellite), Nsmf_PDUSession_UpdateSMContext may include information that data buffering is not allowed on the satellite.

[0379] If the satellite decides not to perform buffering (data buffering is not allowed on the satellite), the SMF may cause the UPF to discard the buffered data.

[0380] Alternatively, if the satellite determines that it will not perform buffering (data buffering is not permitted on the satellite), the SMF may extend the buffering time of the data being buffered by the UPF. In this case, the UPF may buffer the data for an extended period of time. The extended period may be the time it takes for the terminal to enter the satellite's coverage area.

[0381] If the satellite determines that it is (or can be) capable of performing buffering (if data buffering is allowed on the satellite), Nsmf_PDUSession_UpdateSMContext may include information that data buffering is allowed on the satellite.

[0382] The SMF that receives this information can decide whether to buffer the data on the satellite or in the core network (UPF).

[0383] Alternatively, a satellite can inform the AMF whether it will perform buffering. This may be based on the satellite's subscription to an event. Upon receiving this information, the AMF can then notify the SMF.

[0384] If the satellite decides to buffer data, it can buffer the data upon receiving it. Once the service link is established, the satellite can transmit the data to the terminal.

[0385] By obtaining information about the feeder links of satellites (e.g., feeder link availability information), AMF can obtain information about each satellite (satellite ID and orbit information) and gateway information (location information of gateways connected to each AMF (Cell, TA, Geographical Location), and gateways that can be connected by time zone for each satellite).

[0386] In addition to the area and time information that each satellite will serve, which can be obtained through the existing Satellite Coverage Availability Information, AMF can also provide information about the time when the feeder link for each satellite is available for connection through the ground gateway connected to AMF.

[0387] Based on the above information, when forwarding MT data to a terminal using the S&F function, it can be determined whether to forward the data to the satellite.

[0388] Based on the aforementioned information, the AMF can communicate an extended maximum wait time to the SMF. The AMF can then inform the terminal that data transmission is unavailable.

[0389] Based on the extended maximum waiting time, the SMF / UPF can determine how long to buffer data. The satellite can receive information from the AMF / SMF regarding how long data will be stored on the satellite (whether buffering is required) (e.g., the time until the terminal enters the satellite's coverage area). Based on this information, whether data should be buffered and the paging time can be determined.

[0390] The operations proposed in this specification can be applied by AMF to a terminal performing S&F operations of a satellite.

[0391] We assume that the satellite is equipped with NG-RAN and that the terminal supporting S&F functionality has no mobility. Alternatively, even if the terminal is mobile, we assume that the network (e.g., AMF) can determine the time when the terminal enters satellite coverage based on information about the terminal's mobility.

[0392] Satellites can communicate with each other via the satellite-to-satellite Xn interface via the ISL. Signaling messages, such as terminal registration to the network or creation of a PDU session, can be connected to the gateway via the ISL, and terminal data transmission can be operated via the S&F.

[0393] The proposed behavior can be used both when using the general user plane and when transmitting data as NAS messages via 'Control Plane CIoT 5GS Optimization'. The terminal can include an indication in the RRC message indicating whether user data is included.

[0394] The satellite can be a LEO or MEO satellite.

[0395] AMF can determine whether a specific area is within coverage that can be serviced at a specific time through Satellite Coverage Availability Information.

[0396] 1) The AMF can obtain information about the satellite's feeder link (e.g., feeder link availability information). This information can be provisioned to the AMF through O&M, like satellite coverage availability information, or received from an external AF through the control plane. Alternatively, it can be obtained through an additional NF that manages this information (either satellite coverage availability information or feeder link availability information). Feeder link availability information can include the following:

[0397] - ID and orbit information of each satellite

[0398] - Information on gateways connected to each AMF and location information of the gateways (Cell, TA, Geographical Location)

[0399] - Gateway that can be connected to each satellite by time zone

[0400] 2) Based on the above information, AMF can know the time when each satellite can connect to the feeder link through the ground gateway connected to each AMF and can know the ID of the corresponding satellite.

[0401] 3) Based on the satellite coverage availability information and feeder link availability information, AMF can determine whether there is a feeder link to a satellite with which it has an association through the gateway currently connected to it.

[0402] AMF can check whether there is a satellite that can service the area corresponding to the UE's stored location (stored in the UE context, etc.) and decide to use that satellite as the satellite to forward data (if there is one).

[0403] If the terminal is currently connected to the satellite, the AMF can trigger the action of forwarding MT data by sending a success response to the SMF regarding UE reachability.

[0404] 4) The SMF and / or AMF may transmit to the satellite information including the expected service link connection time (information on how long data will be stored on the satellite after transmission (e.g., the time until the terminal enters the satellite's coverage area)). Based on this information, the satellite can determine when to request paging from the terminal. At this time, the SMF may separately inform the satellite via the AMF that data buffering is required.

[0405] Additionally, information about the size of the data that requires buffering can also be transmitted to the satellite.

[0406] Based on this information, the satellite can respond to the SMF with an indication of whether to buffer data. If buffering is not permitted, the SMF can discard the buffered data with the UPF or increase the buffering time.

[0407] 5) If the feeder link is currently not connected, AMF can determine a specific time in the future when the feeder link will be connected based on the feeder link availability information and satellite coverage availability information.

[0408] Based on a specific time in the future when the feeder link is reachable, the AMF may communicate the estimated maximum wait time to the SMF in the response message to the Namf_MT_EnableUEReachability request. Alternatively, the AMF may communicate a failure indication to the SMF if data transfer via the S&F operation is not possible.

[0409] Based on this, SMF can decide whether to keep buffering data and when to re-request downlink data.

[0410] The following drawings are intended to illustrate specific examples of the present specification. The names of specific devices and the names of specific signals / messages / fields depicted in the drawings are provided for illustrative purposes only, and the technical features of this specification are not limited to the specific names used in the drawings.

[0411] Figure 13 illustrates the AMF's procedure for the disclosure of this specification.

[0412] 1. AMF can receive a confirmation request message for reachability for UE (User Equipment) from SMF (Session Management Function).

[0413] 2. Based on the feeder link availability information, AMF can decide whether to connect the feeder link.

[0414] 3. Based on the absence of connection of the above feeder link, AMF can determine the expected connection time of the above feeder link.

[0415] The above feeder link may be a link between a satellite for the UE for downlink data transmission and a gateway connected to the AMF.

[0416] 4. Based on the above confirmation request message, AMF can send a response message to the SMF.

[0417] The above response message may include whether the determined feeder link is connected.

[0418] Based on the absence of a connection to the feeder link, the response message may include an expected connection time for the feeder link.

[0419] Based on the above response message including the expected connection time, the AMF can receive a new confirmation request message for reachability for the UE from the SMF at a time based on the expected connection time of the feeder link.

[0420] The above AMF may be aware of the fact that the above UE supports S&F (Store and Forward).

[0421] The step of determining whether the feeder link is connected and the step of determining the expected connection time of the feeder link may be performed based on the AMF knowing that the UE supports S&F.

[0422] Based on the information about the coverage of the above satellite, AMF can decide whether to connect the service link.

[0423] Based on the absence of a connection to the above service link, AMF can determine the expected connection time of the above service link.

[0424] The above service link may be a link between the UE and the satellite for downlink data transmission.

[0425] The above response message may include whether the determined service link is connected.

[0426] Based on the absence of a connection to the above service link, the response message may include an expected connection time for the above service link.

[0427] Based on the presence of a connection to the above feeder link and the absence of a connection to the above service link, the AMF can receive a buffering-related message from the SMF.

[0428] The above buffering related message may include information that buffering of downlink data is required from the satellite, information about the size of the downlink data, and an expected connection time of the service link.

[0429] Based on the above buffering-related message, AMF can transmit a buffering message to the satellite.

[0430] The buffering message may include information that buffering of downlink data is required from the satellite, information about the size of the downlink data, and an expected connection time of the service link.

[0431] Based on the above buffering message, AMF can receive a buffering response message from the satellite.

[0432] The above buffering response message may include information on whether buffering of the downlink data is possible on the satellite.

[0433] The AMF can transmit information to the SMF as to whether buffering for the downlink data is possible.

[0434] The following drawings are intended to illustrate specific examples of the present specification. The names of specific devices and the names of specific signals / messages / fields depicted in the drawings are provided for illustrative purposes only, and the technical features of this specification are not limited to the specific names used in the drawings.

[0435] Figure 14 illustrates the SMF procedure for the disclosure of this specification.

[0436] 1. SMF can receive notifications about downlink data for UE (User Equipment) from UPF (User Plane Function).

[0437] 2. Based on the above notification, the SMF can send a message requesting confirmation of reachability for the UE to the AMF (Access and Mobility management Function).

[0438] 3. Based on the above confirmation request message, the SMF can receive a response message from the AMF.

[0439] The above response message may include whether the feeder link is connected.

[0440] The above feeder link may be a link between a satellite for the UE for transmission of the downlink data and a gateway connected to the AMF.

[0441] Based on the absence of a connection to the feeder link, the response message may include an expected connection time for the feeder link.

[0442] Based on the above response message including the expected connection time, the SMF can send a new confirmation request message for reachability for the UE to the AMF at a time based on the expected connection time of the feeder link.

[0443] The above response message may include whether the service link is connected.

[0444] The above service link may be a link between the UE and the satellite for downlink data transmission.

[0445] Based on the absence of a connection to the above service link, the response message may include an expected connection time for the above service link.

[0446] Based on the above response message, the SMF can decide whether to i) forward the downlink data to the UE, ii) buffer the downlink data, or iii) discard the downlink data.

[0447] Based on the fact that the response message includes information that the feeder link is connected, the SMF may decide to forward the downlink data to the UE.

[0448] Based on the SMF's decision to forward the downlink data to the UE, the SMF may transmit a message to the UPF triggering it to forward the downlink data to the UE.

[0449] Based on the lack of connectivity of the above feeder link, the SMF may send a message to the UPF instructing it to buffer the downlink data.

[0450] Based on the presence of a connection to the feeder link and the absence of a connection to the service link, the SMF may send a message to the UPF instructing it to buffer the downlink data.

[0451] Based on the above response message, the SMF may determine that buffering of downlink data from the satellite is required.

[0452] Based on the above response message, the SMF can send a buffering related message to the AMF.

[0453] Based on the above SMF determining that buffering of downlink data from the satellite is necessary, the buffering-related message may include information that buffering of downlink data from the satellite is necessary.

[0454] The above buffering related message may include information about the size of the downlink data and the expected connection time of the service link.

[0455] Based on the above buffering related message, the SMF can receive information from the AMF as to whether buffering for the downlink data is possible from the satellite.

[0456] Based on receiving information from the AMF that buffering of the downlink data is possible on the satellite, the SMF may transmit a message to the UPF triggering it to transmit the downlink data to the UE.

[0457] Based on the above response message including at least one of information that the feeder link is not connected and information that the service link is not connected, the SMF may decide to discard the downlink data.

[0458] Based on the SMF's decision to discard the downlink data, the SMF may send an instruction to the UPF to discard the downlink data.

[0459] Based on receiving information from the AMF that buffering of the downlink data is not possible on the satellite, the SMF can decide whether i) the UPF will buffer the downlink data or ii) discard the downlink data.

[0460] The above UE may be a UE supporting S&F.

[0461] The above satellite may be a regenerative satellite.

[0462] The following drawings are intended to illustrate specific examples of the present specification. The names of specific devices and the names of specific signals / messages / fields depicted in the drawings are provided for illustrative purposes only, and the technical features of this specification are not limited to the specific names used in the drawings.

[0463] Figure 15 illustrates the satellite procedure for the disclosure of this specification.

[0464] 1. Based on the presence of a feeder link connection and absence of a service link connection, the satellite can receive buffering messages from the Access and Mobility management Function (AMF).

[0465] The above feeder link may be a link between a satellite for UE (User Equipment) for downlink data transmission and a gateway connected to the AMF.

[0466] The above UE may be a UE supporting S&F.

[0467] The above satellite may be a regenerative satellite.

[0468] The above service link may be a link between the UE and the satellite for transmitting the downlink data.

[0469] The above buffering message may include information that buffering of downlink data is required from the satellite, information about the size of the downlink data, and an expected connection time of the service link.

[0470] Based on the buffering message and the buffering capacity available to the satellite, the satellite can determine whether buffering of the downlink data is possible on the satellite.

[0471] The satellite may transmit the result of the above decision to the AMF.

[0472] Based on determining that the satellite can buffer the downlink data, the satellite can receive the downlink data.

[0473] Based on the satellite determining that it is capable of buffering the downlink data, the satellite may buffer the downlink data.

[0474] Based on the connection of the above service link, the satellite can transmit the downlink data to the UE.

[0475] Hereinafter, a device for performing communication according to some embodiments of the present specification will be described.

[0476] For example, a device may include a processor, a transceiver, and memory.

[0477] For example, a processor may be configured to be operatively coupled with memory and a processor.

[0478] The operations performed by the processor include: receiving a confirmation request message for reachability of the UE from an SMF; determining whether a feeder link is connected based on feeder link availability information; determining an expected connection time of the feeder link based on the absence of a connection of the feeder link; and transmitting a response message to the SMF based on the confirmation request message, wherein the response message includes whether the determined feeder link is connected, and based on the absence of a connection of the feeder link, the response message may include an expected connection time of the feeder link.

[0479] Below, a processor of a device for providing communication according to some embodiments of the present specification is described.

[0480] The operations performed by the processor include: receiving a confirmation request message for reachability of the UE from an SMF; determining whether a feeder link is connected based on feeder link availability information; determining an expected connection time of the feeder link based on the absence of a connection of the feeder link; and transmitting a response message to the SMF based on the confirmation request message, wherein the response message includes whether the determined feeder link is connected, and based on the absence of a connection of the feeder link, the response message may include an expected connection time of the feeder link.

[0481] Hereinafter, a non-volatile computer-readable medium storing one or more commands for providing mobile communication according to some embodiments of the present specification is described.

[0482] According to some embodiments of the present disclosure, the technical features of the present disclosure may be implemented directly in hardware, software executed by a processor, or a combination of the two. For example, a method performed by a wireless device in wireless communication may be implemented in hardware, software, firmware, or any combination thereof. For example, the software may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or other storage media.

[0483] Some examples of storage media are coupled to the processor, allowing the processor to read information from the storage media. Alternatively, the storage media may be integrated into the processor. The processor and storage media may reside in an ASIC. In other examples, the processor and storage media may reside as separate components.

[0484] Computer-readable media may include tangible and non-volatile computer-readable storage media.

[0485] For example, nonvolatile computer-readable media may include random access memory (RAM), such as synchronized dynamic random access memory (SDRAM), read-only memory (ROM), non-volatile random access memory (NVRAM), read-only memory (EEPROM), flash memory, magnetic or optical data storage media, or any other media that can be used to store instructions or data structures. Nonvolatile computer-readable media may also include combinations of the above.

[0486] Additionally, the methods described herein can be realized at least in part by a computer-readable communication medium that carries or transmits code in the form of instructions or data structures and that can be accessed, read, and / or executed by a computer.

[0487] According to some embodiments of the present disclosure, a non-transitory computer-readable medium has one or more instructions stored thereon. The one or more stored instructions can be executed by a processor of a base station.

[0488] The stored one or more commands include: receiving a confirmation request message for reachability of a UE from an SMF; determining whether a feeder link is connected based on feeder link availability information; determining an expected connection time of the feeder link based on the absence of a connection of the feeder link; wherein the feeder link is a link between a satellite for the UE for downlink data transmission and a gateway connected to the AMF; and transmitting a response message to the SMF based on the confirmation request message, wherein the response message includes whether the determined feeder link is connected, and based on the absence of a connection of the feeder link, the response message includes an expected connection time of the feeder link.

[0489] This specification may have various effects.

[0490] For example, S&F operations may be performed in connection with feeder links and service links.

[0491] The effects that can be achieved through specific examples of this specification are not limited to the effects listed above. For example, a person with ordinary skill in the relevant technical field may understand or derive various technical effects from this specification. Accordingly, the specific effects of this specification are not limited to those explicitly described herein, but may include various effects that can be understood or derived from the technical features of this specification.

[0492] The claims set forth in this specification may be combined in various ways. For example, the technical features of the method claims of this specification may be combined to implement a device, and the technical features of the device claims of this specification may be combined to implement a method. Furthermore, the technical features of the method claims and the technical features of the device claims of this specification may be combined to implement a device, and the technical features of the method claims and the technical features of the device claims of this specification may be combined to implement a method. Other implementations are within the scope of the claims.

Claims

1. A method by which AMF (Access and Mobility management Function) performs communication, A step of receiving a confirmation request message for reachability for a UE (User Equipment) from a SMF (Session Management Function); A step of determining whether to connect a feeder link based on feeder link availability information; A step of determining an expected connection time of the feeder link based on the absence of connection of the feeder link; The above feeder link is a link between the satellite for the UE for downlink data transmission and the gateway connected to the AMF, A step of transmitting a response message to the SMF based on the above confirmation request message, The above response message includes whether the determined feeder link is connected, A method wherein the response message includes an expected connection time of the feeder link based on the absence of a connection of the feeder link.

2. In paragraph 1, A method further comprising the step of receiving a new confirmation request message for reachability for the UE at a time based on the expected connection time of the feeder link from the SMF, based on the response message including the expected connection time.

3. In paragraph 1 or 2, The above AMF is aware of the fact that the above UE supports S&F (Store and Forward), A method wherein the step of determining whether the feeder link is connected and the step of determining the expected connection time of the feeder link are performed based on the AMF knowing that the UE supports S&F.

4. In any one of the clauses 1 to 3, A step of determining whether to connect a service link based on information about the coverage of the above satellite; Further comprising a step of determining an expected connection time of the service link based on the absence of connection of the service link; The above service link is a link between the UE and the satellite for downlink data transmission, The above response message includes whether the determined service link is connected, A method wherein the response message includes an expected connection time of the service link based on the absence of a connection of the service link.

5. In paragraph 4, A step of receiving a buffering-related message from the SMF based on whether the feeder link is connected and the service link is not connected; The above buffering related message includes information that buffering of downlink data is required from the satellite, information about the size of the downlink data, and an expected connection time of the service link. A step of transmitting a buffering message to the satellite based on the buffering-related message; The buffering message includes information that buffering of downlink data is required from the satellite, information about the size of the downlink data, and an expected connection time of the service link. A step of receiving a buffering response message from the satellite based on the buffering message; The above buffering response message includes information on whether buffering for the downlink data is possible on the satellite, A method further comprising the step of transmitting information to the SMF as to whether buffering of the downlink data is possible.

6. As a method for SMF (Session Management Function) to perform communication, A step of receiving a notification for downlink data for UE (User Equipment) from UPF (User Plane Function); A step of transmitting a confirmation request message for reachability of the UE to an AMF (Access and Mobility management Function) based on the above notification; A step of receiving a response message from the AMF based on the above confirmation request message, The above response message includes whether the feeder link is connected, The above feeder link is a link between the satellite for the UE for transmission of the downlink data and the gateway connected to the AMF, A method wherein the response message includes an expected connection time of the feeder link based on the absence of a connection of the feeder link.

7. In paragraph 6, A method further comprising the step of transmitting a new confirmation request message for reachability for the UE to the AMF at a time based on the expected connection time of the feeder link, based on the response message including the expected connection time.

8. In paragraph 6 or 7, The above response message includes whether the service link is connected, The above service link is a method for transmitting downlink data between the UE and the satellite.

9. In paragraph 8, A method wherein the response message includes an expected connection time of the service link based on the absence of a connection of the service link.

10. In any one of paragraphs 6 to 8, A method further comprising the step of determining, based on the response message, i) whether to transmit the downlink data to the UE, ii) whether to buffer the downlink data, or iii) whether to discard the downlink data.

11. In any one of the clauses 6 to 8, A step of determining to transmit the downlink data to the UE based on the fact that the response message includes information that the feeder link is connected; A method further comprising the step of transmitting a message to the UPF to trigger the UPF to transmit the downlink data to the UE based on the SMF's determination to transmit the downlink data to the UE.

12. In any one of paragraphs 6 to 8, A method further comprising the step of transmitting a message instructing the UPF to buffer the downlink data based on the absence of a connection of the feeder link.

13. In paragraph 8, A method further comprising the step of transmitting a message instructing the UPF to buffer the downlink data based on whether the feeder link is connected and whether the service link is not connected.

14. In paragraph 9, A step of determining that buffering of downlink data from the satellite is necessary based on the above response message; A step of transmitting a buffering-related message to the AMF based on the above response message; Based on the above SMF determining that buffering of downlink data from the satellite is required, the buffering-related message includes information that buffering of downlink data from the satellite is required, The above buffering related message includes information about the size of the downlink data and the expected connection time of the service link, A method further comprising the step of receiving information from the AMF on whether buffering for the downlink data is possible on the satellite based on the buffering-related message.

15. In paragraph 14, A method further comprising the step of transmitting a message to the UPF to trigger the UPF to transmit the downlink data to the UE based on receiving information from the AMF that buffering of the downlink data is possible on the satellite.

16. In paragraph 8, A step of determining to discard the downlink data based on the response message including at least one of information that the feeder link is not connected and information that the service link is not connected; A method further comprising the step of transmitting an instruction to the UPF to discard the downlink data based on the SMF's decision to discard the downlink data.

17. In paragraph 9, A method further comprising the step of: i) determining whether the UPF buffers the downlink data or ii) discarding the downlink data, based on receiving information from the AMF that buffering of the downlink data is impossible on the satellite.

18. In any one of paragraphs 6 to 17, The above UE is a UE that supports S&F, The above satellite is a regenerative satellite.

19. As a method for satellite communication, A step of receiving a buffering message from an Access and Mobility management Function (AMF) based on whether there is a connection to a feeder link and no connection to a service link; The above feeder link is a link between a satellite for UE (User Equipment) for downlink data transmission and a gateway connected to the AMF, The above UE is a UE that supports S&F, The above satellite is a regenerative satellite, The above service link is a link between the UE and the satellite for transmitting the downlink data, The buffering message includes information that buffering of downlink data is required from the satellite, information about the size of the downlink data, and an expected connection time of the service link. A step of determining whether buffering of the downlink data is possible on the satellite based on the buffering message and the buffering capacity available to the satellite; A step of transmitting the result of the decision to the AMF; A step of receiving the downlink data based on determining that the satellite is capable of buffering the downlink data; A step of buffering the downlink data based on determining that the satellite is capable of buffering the downlink data; A method comprising the step of transmitting the downlink data to the UE based on the connection of the above service link.

20. As an AMF (Access and Mobility management Function) that performs communication, At least one transmitter and receiver; Contains at least one processor, The operation performed by the above processor is an AMF method according to any one of claims 1 to 5.

21. As a SMF (Session Management Function) that performs communication, At least one transmitter and receiver; Contains at least one processor, The operation performed by the above processor is an SMF method according to any one of claims 6 to 18.

22. As a satellite performing communications, At least one transmitter and receiver; Contains at least one processor, The operation performed by the above processor is a satellite according to the method of claim 19.

Images