Support for high-latency communication using SBI between ran and cn

Abstract

Provided are a method and apparatus related to support for high-latency communication using a service based interface (SBI) between a radio access network (RAN) and a core network (CN). A base station receives, from a session management node, a subscription to an event related to enhanced discontinuous reception (eDRX), and on the basis of occurrence of the event, transmits, to the session management node, information notifying that buffering of downlink data is necessary. The base station transmits, to the session management node, information related to a start of application of the eDRX to a user equipment (UE), and on the basis of the UE being reachable, transmits, to the session management node, information related to an end of the application of the eDRX to the UE.

Description

Support for high-latency communication using SBI between RAN and CN

[0001] This specification relates to support for high-latency communication using a Service Based Interface (SBI) between a Radio Access Network (RAN) and a Core Network (CN).

[0002] 3GPP (3rd Generation Partnership Project) New Radio (NR) targets a single technical framework that addresses all deployment, use, and requirements, including enhanced Mobile Broadband (eMBB), massive Machine Type Communications (mmTC), and Ultra-Reliable and Low Latency Communications (URLLC). Additionally, NR must be able to utilize any spectrum band up to at least 100 GHz that can be used for wireless communication in the distant future. NR must be inherently forward compatible.

[0003] 3GPP NR introduced the Service-Based Architecture (SBA), a new core network for 5G based on an open and modular service platform. The SBA provides a cloud-native service framework in which mobile core network functions (authentication, mobility management, etc.) are supported by Network Functions (NFs) and independent software applications that can run on commercial off-the-shelf hardware hosted on cloud infrastructure. NFs interconnected on a logically shared infrastructure or service bus provide services that other authorized NFs can access through Application Programming Interfaces (APIs) called Service-Based Interfaces (SBIs). Services exposed by an NF (Service Producer) to another NF (Service Consumer) are described using API specifications that identify accessible service data sets and indicate authorized operations on these service data.

[0004] 6G is the successor to 5G cellular technology. 6G networks can utilize higher frequencies than 5G networks and will provide significantly higher capacity and much lower latency. The 6G technology market is expected to drive massive improvements in imaging, presence technology, and location awareness. Working in conjunction with Artificial Intelligence (AI), 6G computing infrastructure will be able to identify the best places for computing to occur. This includes decisions regarding data storage, processing, and sharing.

[0005] In one embodiment, a method performed by a base station is provided. The method comprises: receiving a subscription to an event related to an enhanced discontinuous reception (eDRX) from a session management node; transmitting information indicating that buffering of downlink data is required to the session management node based on the occurrence of the event; transmitting information related to the start of the application of the eDRX to a User Equipment (UE) to the session management node; and transmitting information related to the end of the application of the eDRX to the session management node based on whether the UE is reachable.

[0006] In another aspect, a device for implementing the above method is provided.

[0007] FIG. 1 shows an example of a communication system to which the implementation of the present specification is applied.

[0008] FIG. 2 shows an example of a wireless device to which the implementation of the present specification applies.

[0009] FIG. 3 shows an example of a UE to which the implementation of the present specification applies.

[0010] FIG. 4 shows an example of a 5G system structure to which the implementation of the present specification is applied.

[0011] FIGS. 5 and 6 illustrate examples of a PDU session establishment procedure to which the implementation of the present specification applies.

[0012] Figure 7 shows an example of the logical architecture of an O-RAN to which the implementation of the present specification applies.

[0013] FIG. 8 illustrates an example of a method performed by a base station to which an implementation of the present disclosure is applied.

[0014] FIGS. 9 and FIGS. 10 illustrate examples of procedures related to the first implementation of the present specification.

[0015] FIGS. 11 and FIGS. 12 illustrate examples of procedures related to the second implementation of the present specification.

[0016] FIGS. 13 and FIGS. 14 illustrate examples of procedures related to the third implementation of the present specification.

[0017] The following techniques, devices, and systems may 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 Multi-Carrier Frequency Division Multiple Access (MC-FDMA) systems. CDMA may be implemented through wireless technologies such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented through 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 through 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) using E-UTRA.3GPP LTE uses OFDMA in the downlink (DL) and SC-FDMA in the uplink (UL). Evolutions of 3GPP LTE include LTE-A (Advanced), LTE-A Pro, and / or 5G NR (New Radio).

[0018] For convenience of explanation, the implementation of this specification is described primarily in relation to 3GPP-based wireless communication systems. However, the technical characteristics 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, but aspects of this specification that are not limited to 3GPP-based wireless communication systems may be applied to other mobile communication systems.

[0019] 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.

[0020] In this specification, "A or B" may mean "only A," "only B," or "both A and B." Alternatively, in this specification, "A or B" may be interpreted as "A and / or B." For example, in this specification, "A, B or C" may mean "only A," "only B," "only C," or "any combination of A, B and C."

[0021] A slash ( / ) or a comma used in this specification may mean "and / or." For example, "A / B" may mean "A and / or B." Accordingly, "A / B" may mean "only A," "only B," or "both A and B." For example, "A, B, C" may mean "A, B or C."

[0022] 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 as synonymous with "at least one of A and B."

[0023] Additionally, in this specification, "at least one of A, B and C" may mean "only A," "only B," "only C," or "any combination of A, B and C." Furthermore, "at least one of A, B or C" or "at least one of A, B and / or C" may mean "at least one of A, B and C."

[0024] Additionally, parentheses used in this specification 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."

[0025] Technical features described individually within a single drawing in this specification may be implemented individually or simultaneously.

[0026] Although not limited thereto, the various descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in this specification may be applied to various fields where wireless communication and / or connectivity between devices (e.g., 5G) is required.

[0027] The present specification will be described in more detail below with reference to the drawings. In the following drawings and / or description, the same reference numerals may refer to the same or corresponding hardware blocks, software blocks, and / or function blocks unless otherwise indicated.

[0028] The present specification will describe embodiments based on the structure, procedures, messages, etc. of a 5G mobile communication system. However, this is merely an example, and the embodiments of the present specification are not limited thereto. For example, the embodiments of the present specification can be extended to an evolved form of a 6G mobile communication system. For example, the 5G-based messages described in the embodiments of the present specification may be defined as other existing messages, new messages, or parameters.

[0029] FIG. 1 shows an example of a communication system to which the implementation of the present specification is applied.

[0030] The 5G usage scenario shown in FIG. 1 is merely an example, and the technical features of this specification may be applied to other 5G usage scenarios not shown in FIG. 1.

[0031] The three main requirement categories for 5G are (1) enhanced Mobile BroadBand (eMBB) category, (2) massive Machine Type Communication (mMTC) category, and (3) Ultra-Reliable and Low Latency Communications (URLLC) category.

[0032] Referring to FIG. 1, the 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 the network of the communication system (1), but the implementation of the present specification is not limited to a 5G system and may be applied to future communication systems beyond a 5G system.

[0033] The base station (200) and the network (300) can be implemented as wireless devices, and a specific wireless device can operate as a base station / network node in relation to another wireless device.

[0034] Wireless devices (100a to 100f) represent 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), Internet-Of-Things (IoT) devices (100f), and Artificial Intelligence (AI) devices / servers (400). For example, vehicles may include vehicles with wireless communication capabilities, autonomous vehicles, and vehicles capable of performing communication between vehicles. Vehicles may include unmanned aerial vehicles (UAVs) (e.g., drones). XR devices may include AR (Augmented Reality) / VR (Virtual Reality) / MR (Mixed Reality) devices and may be implemented in the form of HMDs (Head-Mounted Devices) and HUDs (Head-Up Displays) 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., smartwatches 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.

[0035] 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 PDA (Personal Digital Assistant), a PMP (Portable Multimedia Player), a navigation system, a slate PC, a tablet PC, an ultrabook, a vehicle, a vehicle with autonomous driving capabilities, a connected car, a UAV, an AI module, a robot, an AR device, a VR device, an MR device, a hologram device, a public safety device, an MTC device, an IoT device, a medical device, a fintech device (or financial device), a security device, a weather / environment device, a 5G service-related device, or a device related to the Fourth Industrial Revolution.

[0036] Wireless devices (100a to 100f) can be connected to a network (300) through a base station (200). AI technology may be applied to the wireless devices (100a to 100f), and the wireless devices (100a to 100f) can be connected to an AI server (400) through 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) may communicate with each other through the base station (200) / network (300), but they may 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., V2V (Vehicle-to-Vehicle) / V2X (Vehicle-to-everything) communication). Also, IoT devices (e.g., sensors) can communicate directly with other IoT devices (e.g., sensors) or other wireless devices (100a to 100f).

[0037] Wireless communication / connections (150a, 150b, 150c) can be established between wireless devices (100a to 100f) and / or between wireless devices (100a to 100f) and base station (200) and / or between base station (200). Here, the wireless communication / connections can be established through various RATs (e.g., 5G NR), such as uplink / downlink communication (150a), sidelink communication (150b) (or D2D (Device-To-Device) communication), and communication between base stations (150c) (e.g., relay, IAB (Integrated Access and Backhaul)). Through the wireless communication / connections (150a, 150b, 150c), wireless devices (100a to 100f) and base station (200) can transmit / receive wireless signals to / from each other. For example, wireless communication / connection (150a, 150b, 150c) may transmit / receive signals through various physical channels. To this end, based on various proposals in this specification, at least some of the following may be performed: a process for setting various configuration information for transmitting / receiving wireless signals, a process for various signal processing (e.g., channel encoding / decoding, modulation / demodulation, resource mapping / demapping, etc.), and a resource allocation process.

[0038] NR supports multiple numerologies or subcarrier spacings (SCS) to support various 5G services. For example, when the SCS is 15 kHz, it supports a wide area in traditional cellular bands; when the SCS is 30 kHz / 60 kHz, it supports dense-urban areas, lower latency, and wider carrier bandwidth; and when the SCS is 60 kHz or higher, it supports a bandwidth greater than 24.25 GHz to overcome phase noise.

[0039] The NR frequency band can be defined by two types of frequency ranges (FR1, FR2). The numerical values ​​of the frequency ranges may change. For example, the two types of frequency ranges (FR1, FR2) may be as shown in Table 1 below. For convenience of explanation, among the frequency ranges used in the NR system, FR1 may mean "sub 6GHz range" and FR2 may mean "above 6GHz range" and may be referred to as Millimeter Wave (mmW).

[0040] Frequency Range Definition Frequency Range Subcarrier Spacing FR1 450 MHz - 6000 MHz 15, 30, 60 kHz FR2 24 250 MHz - 52600 MHz 60, 120, 240 kHz

[0041] As described above, the numerical values ​​of the frequency range of the NR system may change. For example, FR1 may include a band of 410 MHz to 7125 MHz as shown in Table 2 below. That is, FR1 may include a frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or higher. For example, the frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or higher included within FR1 may include an unlicensed band. The unlicensed band may be used for various purposes, for example, for communication for vehicles (e.g., autonomous driving).

[0042] Frequency Range Definition Frequency Range Subcarrier Spacing FR1 4 10 MHz - 7 125 MHz 15, 30, 60 kHz FR2 24 250 MHz - 5 2600 MHz 60, 120, 240 kHz

[0043] Here, the wireless communication technology implemented in the wireless device of this specification may include LTE, NR, and 6G, as well as NarrowBand IoT (NB-IoT) for low-power communication. For example, NB-IoT technology may be an example of Low Power Wide Area Network (LPWAN) technology and may be implemented according to standards such as LTE Cat NB1 and / or LTE Cat NB2, but is not limited to the names mentioned above. Additionally, or generally, the wireless communication technology implemented in the wireless device of this specification may perform communication based on LTE-M technology. For example, LTE-M technology may be an example of LPWAN technology and may be referred to by various names such as eMTC (enhanced MTC). For example, LTE-M technology may be implemented in 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 names mentioned above. Additionally or generally, wireless communication technology implemented in the wireless device of this specification may include at least one of ZigBee, Bluetooth, and / or LPWAN with consideration for low-power communication, and is not limited to the names mentioned above. For example, ZigBee technology may create Personal Area Networks (PANs) related to small / low-power digital communication based on various standards such as IEEE 802.15.4, and may be referred to by various names.

[0044] FIG. 2 shows an example of a wireless device to which the implementation of the present specification applies.

[0045] 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 example / service. For example, {the first wireless device (100) and the second wireless device (200)} may correspond to at least one of {wireless devices (100a–100f) and base station (200)}, {wireless devices (100a–100f) and wireless devices (100a–100f)} and / or {base station (200) and base station (200)} of FIG. 1. The first wireless device (100) and / or the second wireless device (200) may be composed of various components, devices / parts and / or modules.

[0046] 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).

[0047] 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 generally, the memory (104) may be placed outside the processing chip (101).

[0048] The processor (102) can control the memory (104) and / or the transceiver (106) and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed herein. For example, the processor (102) may process information within the memory (104) to generate a first information / signal and transmit a wireless signal containing the first information / signal through the transceiver (106). The processor (102) may receive a wireless signal containing a second information / signal through the transceiver (106) and process the second information / signal to store the obtained information in the memory (104).

[0049] Memory (104) may be connected to the processor (102) so as to be operable. Memory (104) may store various types of information and / or instructions. Memory (104) may store firmware and / or software code (105) that implements code, instructions, and / or a set of instructions that perform the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in this specification when executed by the processor (102). For example, firmware and / or software code (105) may implement instructions that perform the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in this specification when executed by the processor (102). For example, firmware and / or software code (105) may control the processor (102) to perform one or more protocols. For example, firmware and / or software code (105) may control the processor (102) to perform one or more wireless interface protocol layers.

[0050] Here, the processor (102) and memory (104) may be part of a communication modem / circuit / chip designed to implement RAT (e.g., LTE or NR). A transceiver (106) may be connected to the processor (102) and may transmit and / or receive a wireless signal through one or more antennas (108). Each transceiver (106) may include a transmitter and / or receiver. The transceiver (106) may be interchangeably used with an RF (Radio Frequency) unit. In this specification, the first wireless device (100) may represent a communication modem / circuit / chip.

[0051] 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).

[0052] 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 placed outside the processing chip (201).

[0053] The processor (202) can control the memory (204) and / or the transceiver (206) and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed herein. For example, the processor (202) may process information within the memory (204) to generate a third information / signal and transmit a wireless signal containing the third information / signal through the transceiver (206). The processor (202) may receive a wireless signal containing a fourth information / signal through the transceiver (206) and process the fourth information / signal to store the obtained information in the memory (204).

[0054] Memory (204) may be connected to the processor (202) so as to be operable. Memory (204) may store various types of information and / or instructions. Memory (204) may store firmware and / or software code (205) that implements code, instructions, and / or sets of instructions that perform descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification when executed by the processor (202). For example, firmware and / or software code (205) may implement instructions that perform descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification when executed by the processor (202). For example, firmware and / or software code (205) may control the processor (202) to perform one or more protocols. For example, firmware and / or software code (205) may control the processor (202) to perform one or more wireless interface protocol layers.

[0055] 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 transmit and / or receive a wireless signal through one or more antennas (208). Each transceiver (206) may include a transmitter and / or receiver. The transceiver (206) may be interchangeably used with an RF unit. In this specification, the second wireless device (200) may represent a communication modem / circuit / chip.

[0056] 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 PHY (physical) layer, a MAC (Media Access Control) layer, an RLC (Radio Link Control) layer, a PDCP (Packet Data Convergence Protocol) layer, an RRC (Radio Resource Control) layer, and an SDAP (Service Data Adaptation Protocol) layer). One or more processors (102, 202) may generate one or more PDUs (Protocol Data Units), one or more SDUs (Service Data Units), messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in this specification. One or more processors (102, 202) may generate a signal (e.g., baseband signal) including a PDU, SDU, message, control information, data, or information according to the description, function, procedure, proposal, method, and / or operation flowchart disclosed in this specification and provide it to one or more transceivers (106, 206). One or more processors (102, 202) may receive a signal (e.g., baseband signal) from one or more transceivers (106, 206) and may obtain a PDU, SDU, message, control information, data, or information according to the description, function, procedure, proposal, method, and / or operation flowchart disclosed in this specification.

[0057] One or more processors (102, 202) may be referred to as a controller, a microcontroller, a microprocessor, and / or a microcomputer. 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 one or more processors (102, 202). For example, one or more processors (102, 202) may be composed of a set of communication control processors, application processors (APs), electronic control units (ECUs), central processing units (CPUs), graphic processing units (GPUs), and memory control processors. One or more memories (104, 204) may be connected to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. One or more memories (104, 204) may be composed of Random Access Memory (RAM), Dynamic RAM (DRAM), Read-Only Memory (ROM), Erasable Programmable ROM (EPROM), flash memory, volatile memory, non-volatile memory, hard drive, register, cache memory, computer read storage media, and / or combinations thereof.One or more memories (104, 204) may be located inside and / or outside of one or more processors (102, 202). Additionally, one or more memories (104, 204) may be connected to one or more processors (102, 202) through various technologies such as wired or wireless connections.

[0058] One or more transceivers (106, 206) may transmit user data, control information, wireless signals / channels, etc., as described in the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in this specification to one or more other devices. One or more transceivers (106, 206) may receive user data, control information, wireless signals / channels, etc., as described in the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in this specification from one or more other devices. For example, one or more transceivers (106, 206) may be connected to one or more processors (102, 202) and may transmit and receive wireless signals. For example, one or more processors (102, 202) may 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) can control one or more transceivers (106, 206) to receive user data, control information, wireless signals, etc. from one or more other devices.

[0059] One or more transceivers (106, 206) may be connected to one or more antennas (108, 208). Additionally and / or generally, 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., mentioned in the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed herein through one or more antennas (108, 208). In this specification, one or more antennas (108, 208) may be a plurality of physical antennas or a plurality of logical antennas (e.g., antenna ports).

[0060] One or more transceivers (106, 206) can convert received user data, control information, wireless signals / channels, etc. from RF band signals to baseband signals in order to process received user data, control information, wireless signals / channels, etc. using one or more processors (102, 202). One or more transceivers (106, 206) can convert processed user data, control information, wireless signals / channels, etc. from baseband signals to RF band signals using one or more processors (102, 202). To this end, one or more transceivers (106, 206) may include (analog) oscillators and / or filters. For example, one or more transceivers (106, 206) can up-convert an OFDM baseband signal into an OFDM signal through 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) can receive an OFDM signal at a carrier frequency and down-convert the OFDM signal into an OFDM baseband signal through an (analog) oscillator and / or filter under the control of one or more processors (102, 202).

[0061] Although not illustrated in FIG. 2, the wireless device (100, 200) may 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., audio I / O port, video I / O port), a driving unit, and a computing unit. The additional components (140) may be connected to one or more processors (102, 202) through various technologies, such as wired or wireless connections.

[0062] In an implementation of the present specification, the UE may operate as a transmitting device in the uplink and as a receiving device in the downlink. In an implementation of the present specification, the base station may operate as a receiving device in the UL and as a transmitting device in the DL. For technical convenience, it is generally assumed 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 to the first wireless device (100) may be configured to perform UE operations according to an implementation of the present specification or to control a transceiver (106) to perform UE operations according to an implementation of the present specification. A processor (202) connected to, mounted on, or released to the second wireless device (200) may be configured to perform base station operations according to an implementation of the present specification or to control a transceiver (206) to perform base station operations according to an implementation of the present specification.

[0063] In this specification, the base station may be referred to as Node B, eNode B, or gNB.

[0064] FIG. 3 shows an example of a UE to which the implementation of the present specification applies.

[0065] Referring to FIG. 3, the UE (100) can correspond to the first wireless device (100) of FIG. 2.

[0066] The UE (100) includes a processor (102), memory (104), 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).

[0067] The processor (102) may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operation 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 operation flowcharts disclosed herein. Layers of a wireless 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 processor, EXYNOS made by Samsung® TM Series processors, A Series processors made by Apple®, HELIO made by MediaTek® TM Series processors, ATOM made by Intel® TM It can be found in series processors or corresponding next-generation processors.

[0068] Memory (104) is coupled to the processor (102) so as to be operable and stores various information for operating the processor (102). Memory (104) may include ROM, RAM, flash memory, memory card, storage medium and / or other storage device. When the implementation is implemented in software, the technology described herein may be implemented using modules (e.g., procedures, functions, etc.) that perform the descriptions, functions, procedures, proposals, methods and / or operation flowcharts disclosed herein. Modules may be stored in memory (104) and executed by the processor (102). Memory (104) may be implemented within the processor (102) or outside the processor (102), in which case it may be communicatively coupled to the processor (102) through various methods known in the technology.

[0069] A transceiver (106) is coupled to operate with a processor (102) and transmits and / or receives a wireless signal. The transceiver (106) includes a transmitter and a receiver. The transceiver (106) may include a baseband circuit for processing a wireless frequency signal. The transceiver (106) controls one or more antennas (108) to transmit and / or receive a wireless signal.

[0070] 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).

[0071] The display (143) outputs the result 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).

[0072] A SIM card (145) is an integrated circuit for securely storing an International Mobile Subscriber Identity (IMSI) and associated keys, and is used to identify and authenticate a subscriber in a mobile device such as a mobile phone or computer. Additionally, contact information can be stored on many SIM cards.

[0073] 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).

[0074] FIG. 4 shows an example of a 5G system structure to which the implementation of the present specification is applied.

[0075] The 5G system (5GS) structure consists of the following network functions (NF).

[0076] - AUSF (Authentication Server Function)

[0077] -AMF (Access and Mobility Management Function)

[0078] - DN (Data Network), for example, operator services, internet access, or third-party services

[0079] - USDF (Unstructured Data Storage Function)

[0080] - NEF (Network Exposure Function)

[0081] - I-NEF (Intermediate NEF)

[0082] - NRF (Network Repository Function)

[0083] - NSSF (Network Slice Selection Function)

[0084] - PCF (Policy Control Function)

[0085] - SMF (Session Management Function)

[0086] - UDM (Unified Data Management)

[0087] - UDR (Unified Data Repository)

[0088] - UPF (User Plane Function)

[0089] - UCMF (UE radio Capability Management Function)

[0090] - AF (Application Function)

[0091] - UE (User Equipment)

[0092] - (R)AN ((Radio) Access Network)

[0093] - 5G-EIR (5G-Equipment Identity Register)

[0094] - NWDAF (Network Data Analytics Function)

[0095] - CHF (CHarging Function)

[0096] 또한, 다음과 같은 네트워크 기능이 고려될 수 있다.

[0097] - N3IWF (Non-3GPP InterWorking Function)

[0098] - TNGF (Trusted Non-3GPP Gateway Function)

[0099] - W-AGF (Wireline Access Gateway Function)

[0100] Figure 4 shows the 5G system structure in a non-roaming case using a reference point representation showing how various network functions interact with each other.

[0101] In Figure 4, UDSF, NEF, and NRF are not described for clarity of the point-to-point diagram. However, all network functions shown can interact with UDSF, UDR, NEF, and NRF as needed.

[0102] 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.

[0103] The 5G system structure includes the following reference points.

[0104] - N1: Reference point between UE and AMF.

[0105] - N2: Reference point between (R)AN and AMF.

[0106] - N3: Reference point between (R)AN and UPF.

[0107] - N4: Reference point between SMF and UPF.

[0108] - N6: Reference point between the UPF and the data network.

[0109] - N9: Reference point between two UPFs.

[0110] The following reference points show the interactions that exist between the NF services of NF.

[0111] - N5: Reference point between PCF and AF.

[0112] - N7: Reference point between SMF and PCF.

[0113] - N8: Reference point between UDM and AMF.

[0114] - N10: Reference point between UDM and SMF.

[0115] - N11: Reference point between AMF and SMF.

[0116] - N12: Reference point between AMF and AUSF.

[0117] - N13: Reference point between UDM and AUSF.

[0118] - N14: Reference point between two AMFs.

[0119] - N15: Reference point between PCF and AMF for non-roaming scenarios, reference point between PCF and AMF of the visited network for roaming scenarios.

[0120] - N16: Reference point between two SMFs (in the case of roaming, between the SMF of the visited network and the SMF of the home network)

[0121] - N22: Reference point between AMF and NSSF.

[0122] In some cases, two NFs may need to be connected to each other to service the UE.

[0123] The procedure for establishing a PDU session related to the implementation of this specification is described.

[0124] FIGS. 5 and 6 illustrate examples of a PDU session establishment procedure to which the implementation of the present specification applies.

[0125] PDU session establishment may fall under the following:

[0126] - Procedure for establishing a PDU session initiated by the UE

[0127] - PDU session handover between 3GPP and non-3GPP initiated by the UE

[0128] - PDU session handover from EPS initiated by UE to 5GS.

[0129] - Procedure for establishing a PDU session triggered by the network

[0130] A PDU session may be (a) associated with a single access type at any given time, namely either a 3GPP access or a non-3GPP access, or (b) associated with multiple access types simultaneously, namely one 3GPP access and one non-3GPP access. A PDU session associated with multiple access types is called a Multi Access (MA) PDU session and may be requested by an Access Traffic Steering, Switching, Splitting (ATSS) enabled UE.

[0131] Figures 5 and 6 specify a procedure for establishing a PDU session associated with a single connection type at a given time.

[0132] In the procedure shown in Figures 5 and 6, it is assumed that the AMF has already retrieved user subscription data from the UDM, unless the UE is urgently registered, since the UE is already registered with the AMF.

[0133] First, the procedure of Fig. 5 will be explained.

[0134] (1) Step 1: To establish a new PDU session, the UE generates a new PDU session ID.

[0135] The UE initiates the PDU session establishment procedure requested by the UE by transmitting a Non-Access Stratum (NAS) message containing a PDU session establishment request message within an N1 SM container. The PDU session establishment request message includes a PDU session ID, a Requested PDU Session Type, a Requested Session and Service Continuity (SSC) Mode, 5G SM Capability, Protocol Configuration Options (PCO), an SM PDU DN Request Container, and a UE Integrity Protection Maximum Data Rate.

[0136] If the PDU session establishment is a request to establish a new PDU session, the request type indicates "Initial Request". If the request refers to an existing PDU session transitioning between a 3GPP connection and a non-3GPP connection, or a PDU session handover from an existing Packet Data Network (PDN) connection in the EPC, the request type indicates "Existing PDU Session". If the PDU session establishment is a request to establish a PDU session for an emergency service, the request type indicates "Emergency Request". If the request refers to an existing PDU session for an emergency service transitioning between a 3GPP connection and a non-3GPP connection, or a PDU session handover from an existing PDN connection for an emergency service in the EPC, the request type indicates "Existing Emergency PDU Session".

[0137] The UE includes an S-NSSAI from the allowed NSSAI of the current connection type. If a Mapping of Allowed NSSAI is provided to the UE, the UE provides both the S-NSSAI of the visited VPLMN from the allowed NSSAI and the corresponding S-NSSAI of the HPLMN from the mapping of the allowed NSSAI.

[0138] (2) Step 2: The AMF selects an SMF. If the request type indicates an "initial request" or if the request is due to a handover from a non-3GPP connection provided by an EPS or another AMF, the AMF stores the connection type of the PDU session, as well as the association of the S-NSSAI(s), the Data Network Name (DNN), the PDU session ID, and the SMF ID.

[0139] If the request type is "Initial Request" and the message also includes a previous PDU session ID representing an existing PDU session, the AMF selects an SMF and saves the new PDU session ID, S-NSAI(s), and the association of the selected SMF ID.

[0140] If the request type indicates an "existing PDU session," the AMF selects an SMF based on the SMF-ID received from the UDM. The AMF updates the connection type stored for the PDU session.

[0141] If the request type indicates an "existing PDU session" that refers to an existing PDU session moving between a 3GPP connection and a non-3GPP connection, and the serving PLMN S-NSSAI of the PDU session exists in the allowed NSSAI of the target connection type, the PDU session establishment procedure may be performed in the following cases.

[0142] - When the SMF ID corresponding to the PDU session ID and the AMF belong to the same PLMN;

[0143] - If the SMF ID corresponding to the PDU session ID belongs to the HPLMN;

[0144] Otherwise, the AMF rejects the request to establish a PDU session with an appropriate reason for rejection.

[0145] AMF rejects requests from urgently registered UEs where the request type does not indicate "urgent request" or "existing urgent PDU session".

[0146] (3) Step 3: If the AMF is not associated with an SMF for a PDU session ID provided by the UE (e.g., when the request type indicates "initial request"), the AMF calls the Create SMContext request procedure (e.g., Nsmf_PDUSession_CreateSMContext Request). If the AMF is already associated with an SMF for a PDU session ID provided by the UE (e.g., when the request type indicates "existing PDU session"), the AMF calls the Update SMContext request procedure (e.g., Nsmf_PDUSession_UpdateSMContext Request).

[0147] The AMF transmits the S-NSSAI of the serving PLMN from the allowed NSSAI to the SMF. For a roaming scenario of a Local Breakout (LBO), the AMF also transmits the corresponding S-NSSAI of the HPLMN from the mapping of the allowed NSSAI to the SMF.

[0148] The AMF ID is the UE's GUAMI and uniquely identifies the AMF serving the UE. The AMF transmits the PDU Session ID along with an N1 SM container containing the PDU session establishment request message received from the UE. The Generic Public Subscription Identifier (GPSI) is included if available in the AMF.

[0149] If a UE in a restricted service state is registered for emergency services without providing a SUPI, the AMF provides a PEI instead of a SUPI. If a UE in a restricted service state is registered for emergency services while providing a SUPI but is not authenticated, the AMF indicates that the SUPI is not authenticated. If the SMF does not receive a SUPI from a UE or if the AMF indicates that the SUPI is not authenticated, the UE is determined to be unauthenticated.

[0150] AMF can include a PCF ID in Nsmf_PDUSession_CreateSMContext. This PCFID identifies the H-PCF (Home PCF) in the non-roaming case and the V-PCF (Visited PCF) in the LBO roaming case.

[0151] (4) Step 4: If session management subscription data for S-NSSAI of the corresponding SUPI, DNN, HPLMN is unavailable, SMF can retrieve the session management subscription data from UDM and be notified when this subscription data is modified.

[0152] (5) Step 5: SMF sends a create SM context response message (e.g., Nsmf_PDUSession_CreateSMContext Response) or an update SM context response message (e.g., Nsmf_PDUSession_UpdateSMContext Response) to AMF in accordance with the request received in Step 3.

[0153] If SMF receives the Nsmf_PDUSession_CreateSMContext Request in step 3 and can process the PDU session establishment request, SMF creates an SM context and responds to AMF by providing the SM context ID.

[0154] If the SMF decides not to accept the establishment of a PDU session, the SMF rejects the UE request via a NAS SM signal containing the relevant SM rejection cause by responding to the AMF with an Nsmf_PDUSession_CreateSMContext Response. The SMF also indicates to the AMF that the PDU session ID is considered released and that the SMF proceeds to step 20 below and the PDU session establishment procedure is stopped.

[0155] (6) Step 6: Optional secondary authentication / authorization may be performed.

[0156] (7a) Step 7a: When using dynamic policy and charging control (PCC) in a PDU session, the SMF can perform PCC selection.

[0157] (7b) Step 7b: SMF can establish an SM policy association with PCF and obtain a basic PCC rule for the PDU session by performing the SM policy association establishment procedure.

[0158] (8) Step 8: SMF selects one or more UPFs.

[0159] (9) Step 9: SMF can provide information about the satisfied policy control request trigger conditions by performing the SM policy association modification procedure initiated by SMF.

[0160] (10) Step 10: If the request type indicates an “initial request,” the SMF may initiate an N4 Session Establishment procedure with the selected UPF. Otherwise, the SMF may initiate an N4 Session Modification procedure with the selected UPF.

[0161] In step 10a, SMF can send an N4 session establishment / modification request to UPF and provide packet detection, enforcement, and reporting rules installed in UPF for the PDU session. In step 10b, UPF can confirm by sending an N4 session establishment / modification response.

[0162] (11) Step 11: SMF sends an N1N2 message transfer message (e.g., Namf_Communication_N1N2 Message Transfer) to AMF.

[0163] The N1N2 message delivery message may include N2 SM information. The N2 SM information carries the following information that the AMF will transmit to the (R)AN.

[0164] - CN Tunnel Info: Corresponds to the core network address of the N3 tunnel corresponding to the PDU session;

[0165] - One or more QoS (Quality of Service) profiles and their corresponding QFI (QoS Flow ID);

[0166] - PDU Session ID: Indicates to the UE the association between the RAN resource and the PDU session for the UE;

[0167] - S-NSSAI with a value for the serving PLMN (i.e., HPLMN S-NSSAI, or VPLMN S-NSSAI in the case of LBO roaming);

[0168] - User plane security enforcement information determined by SMF;

[0169] - Maximum data rate for UE integrity protection received in PDU session establishment request message: When integrity protection is indicated as "Preferred" or "Required" in user plane security enforcement information

[0170] - RSN (Redundancy Sequence Number) Parameter

[0171] The N1N2 message delivery message may include an N1 SM container. The N1 SM container includes a PDU session establishment acceptance message that the AMF will provide to the UE. The PDU session establishment acceptance message includes an S-NSSAI from an allowed NSASI. In the case of an LBO roaming scenario, the PDU session establishment acceptance message includes an S-NSSAI from an allowed NSSAI for the VPLMN, and also includes the corresponding S-NSSAI for the HPLMN from the mapping of the allowed NSSAI received by the SMF in step 3.

[0172] If necessary for QoS flows related to QoS rules and QoS profiles, multiple QoS rules, QoS flow levels, and QoS parameters may be included in the PDU session establishment acceptance message and N2 SM information within the N1 SM container.

[0173] If PDU session establishment fails between steps 5 and 11, the N1N2 message delivery message contains an N1 SM container containing a PDU session establishment rejection message, but does not contain N2 SM information. (R)AN sends a NAS message containing a PDU session establishment rejection message to the UE. In this case, steps 12-17 below are omitted.

[0174] (12) Step 12: The AMF sends a NAS message containing a PDU session ID destined for the UE, a message accepting the establishment of a PDU session, and N2 SM information received from the SMF to (R)AN within the N2 PDU session request message.

[0175] (13) Step 13: (R)AN can perform AN-specific signal exchanges with the UE regarding information received from the SMF. For example, in the case of NG-RAN, it can perform RRC connection reconfiguration with the UE to set up necessary NG-RAN resources in relation to the QoS rules for the PDU session request received by the UE in Step 12.

[0176] (R)AN forwards the NAS message (PDU session ID, N1 SM container (PDU session establishment acceptance message)) received in step 12 to the UE. (R)AN provides the NAS message to the UE only if the AN-specific signal exchange with the UE includes the addition of (R)AN resources related to the received N2 command.

[0177] If N2 SM information is not included in step 11, steps 14–16b and step 17 below are omitted.

[0178] The procedure of Fig. 6 following the procedure of Fig. 5 is described.

[0179] (14) Step 14: (R)AN sends an N2 PDU session response message to AMF. The N2 PDU session response message may include a PDU session ID, cause, N2 SM information (PDU session ID, AN tunnel information, list of accepted / rejected QFIs, user plane enforcement policy notifications), etc.

[0180] (15) Step 15: AMF sends an update SM context request message (e.g., Nsmf_PDUSession_UpdateSMContext Request) to SMF. AMF forwards the N2 SM information received from (R)AN to SMF.

[0181] (16a) Step S16a: SMF initiates the N4 session modification procedure with UPF. SMF provides AN tunnel information and the corresponding forwarding rule to UPF.

[0182] (16b) Step S16b: UPF provides the N4 session modification response to SMF.

[0183] After this step, UPF can deliver the DL packet that may have been buffered for this PDU session to the UE.

[0184] (16c) Step 16c: If the SMF is not yet registered for this PDU session, the SMF can register with the UDM for the given PDU session.

[0185] (17) Step 17: SMF sends an update SM context response message (e.g., Nsmf_PDUSession_UpdateSMContext Response) to AMF.

[0186] After this step, AMF delivers the relevant events subscribed to by SMF.

[0187] (18) Step 18: At any time after Step 5, if the establishment of the PDU session fails during the procedure, the SMF may notify the AMF by calling Nsmf_PDUSession_SMContextStatusNotify (release). The SMF may also release the created N4 session, the assigned PDU session address (e.g., IP address), and, if possible, release the association with the PCF. In this case, Step 19 below is omitted.

[0188] (19) Step 19: For PDU session type IPv6 or IPv4v6, the SMF can generate an IPv6 Router Advertisement and send it to the UE.

[0189] (20) Step 20: SMF can perform SM policy association modifications initiated by SMF.

[0190] (21) Step 21: If the establishment of a PDU session fails after Step 4, and the SMF no longer processes the UE's PDU session, the SMF may unsubscribe from the modification of the session management subscription data.

[0191] This specification describes the enhanced Discontinuous Reception (eDRX) related to the implementation of this specification.

[0192] The UE and the network can negotiate the use of an extended idle mode DRX to reduce power consumption through NAS signaling while available for Mobile Terminating (MT) data and / or network outgoing procedures within a scheduled delay that depends on the DRX cycle value.

[0193] The UE and the network can negotiate the use of extended idle mode DRX as follows.

[0194] If the UE decides to request an extended idle mode DRX, the UE may include an extended idle mode DRX parameter information element in the registration request message. The UE may also include a UE-specific DRX parameter information element for a normal idle mode DRX. The extended DRX parameter information element may include the extended idle mode DRX cycle length.

[0195] The AMF may decide whether to accept or reject a UE request to enable the Extended Idle Mode DRX. If the AMF accepts the Extended Idle Mode DRX, it may provide Extended Idle Mode DRX parameter values ​​different from those requested by the UE, based on the operator policy and, where possible, the Extended Idle Mode DRX cycle length value in the UDM's subscription data. Taking into account the RAT-specific Subscribed Paging Time Window, the UE's current RAT, and local policy, the AMF allocates the Paging Time Window length to be used and may provide this value to the UE during the subscription update process, along with the Extended Idle Mode DRX cycle length in the Extended DRX parameter information element. If the AMF accepts the use of the Extended Idle Mode DRX, the UE may apply the Extended Idle Mode DRX based on the received Extended Idle Mode DRX length, the UE's current RAT, and the RAT-specific Paging Time Window length. If the relevant acceptance message does not include extended DRX parameter information elements because the AMF rejected the request or the request was received by an AMF that does not support extended idle mode DRX, the UE may apply a normal DRX. A paging time window may be applied to extended DRX lengths longer than 10.24 seconds.

[0196] For RAT types that support extended DRX for CM-CONNECTED with RRC_INACTIVE status, the AMF can pass the UE's accepted idle mode eDRX value to the NG-RAN. If the UE supports eDRX in RRC_INACTIVE, based on the UE's radio capabilities, the NG-RAN sets the eDRX cycle to the UE's idle mode eDRX cycle value of the RRC Inactive Assistance Information provided by the AMF to the UE in RRC_INACTIVE.

[0197] If an eDRX cycle is applied to RRC_INACTIVE, and the eDRX cycle lasts for 10.24 seconds or less, the RAN may buffer DL packets until the duration of the eDRX cycle selected by the NG-RAN. If an indication of CN-based MT communication processing support is received in the RRC disable help information, the NG-RAN may select an eDRX cycle longer than 10.24 seconds. In this case, depending on the implementation, the NG-RAN may pass an indication in the N2 message to the AMF that the UE is transitioning to the RRC_INACTIVE state and the eDRX values ​​determined by the NG-RAN for RRC_INACTIVE (i.e., the eDRX cycle length and the paging time window length). The CN processes MT communication considering the indication and may apply high-latency communication. The AMF may reply to the NG-RAN that the indication in the N2 message has been considered and that MT signaling or data has been buffered by the core network based on high-latency communication.

[0198] In the case of NR, the NG-RAN may request the CN to handle MT communication for UEs set to eDRX for the RRC_INACTIVE state through CN-based MT communication processing procedures and connection deactivation procedures. This allows the CN to apply high-latency communication capabilities. The NG-RAN may provide the AMF with the determined eDRX values ​​for RRC_INACTIVE (i.e., eDRX cycle length and paging time window length) (e.g., >10.24 seconds). Based on the NG-RAN's request, the AMF may respond to the NG-RAN, notify other NFs (e.g., SMF and UPF) involved in downlink data or signaling processing, and trigger data buffering. Based on local policies and / or indications from the AMF (e.g., CN-based MT processing indications), the SMF may trigger the UPF to provide the DL data size upon arrival of DL data when data buffering is executed by the UPF.

[0199] When MT data or signaling arrives for a UE in the RRC_INACTIVE state, other NFs may communicate with the AMF to deliver the MT data or signaling. The AMF calculates the reachability of the UE based on the eDRX value for the RRC_INACTIVE state provided by the NG-RAN, and if the UE is deemed reachable, it may trigger NG-RAN paging via an N2 RAN paging request message. Otherwise, the AMF stores the information received from the NF request and may respond to the requesting NF to apply high-latency communication capabilities based on the eDRX value for RRC_INACTIVE (e.g., the estimated maximum latency is calculated based on the eDRX value for RRC_INACTIVE). If the AMF determines that the UE has become reachable for paging, the AMF may use the stored information to send an N2 RAN paging request message. If the UPF / SMF provides downlink data size information, the AMF may provide that information to the NG-RAN.

[0200] When the UE resumes the RRC connection (e.g., including the Mobile Originated (MO) small data transmission procedure), if the NG-RAN sends an indication to the CN to handle MT communication, the NG-RAN may indicate to the AMF that the UE is now reachable for downlink data and / or signaling. The AMF then uses high-latency communication capabilities to inform other NFs that the UE is now reachable, and MT data and signaling can be delivered to the UE.

[0201] High-latency communication can be used to handle MT communication for UEs that are unreachable due to the use of power-saving functions or discontinuous coverage. 'High latency' may refer to the initial response time before normal packet exchange is established. That is, it may be the time it takes for the UE to wake up from power-saving state and respond to an initial downlink packet or signal.

[0202] High-latency communication may be supported through extended buffering of downlink data in the UPF, SMF, or NEF when the UE is unreachable while using power saving features in the CM-IDLE or RRC_INACTIVE state, or when using satellite access with discontinuous coverage. For sessions anchored by the UPF, when the AN is released or when the NG-RAN indicates via the AMF that the UE is in the extended DRX for RRC_INACTIVE, the SMF may set the user data Forwarding Action Rule and the user data Buffering Action Rule to the UPF. The rules may include instructions on whether UPF buffering is applied or whether user data should be forwarded to the SMF for buffering in the SMF. For sessions anchored by the NEF, only extended buffering in the NEF may be supported. When using Control Plane CIoT 5GS Optimization, during Network Triggered Service Request procedures or MT Data Transport procedures, the AMF may provide the SMF with an Estimated Maximum Wait Time if the SMF indicates support for extended buffering. The SMF may determine the Extended Buffering Time based on the received Estimated Maximum Wait Time or local settings.

[0203] High-latency communication can also be supported through notification procedures. The following procedures are available based on different monitoring events:

[0204] - UE Reachability;

[0205] - Availability after DDN (Downlink Data Notification) failure;

[0206] - Downlink Data Delivery Status.

[0207] The AF can request a one-time "UE Reachability" notification when attempting to transmit data to a UE using the power saving function. The SCS / AS / AF can then wait for data transmission until it receives notification that the UE is reachable.

[0208] The AF may request recurring "Availability after DDN failure" notifications, where each UE reachability notification is triggered by a preceding DDN failure. That is, when a UE becomes reachable, the AF may request a UE reachability notification by sending a downlink packet. Such downlink packets may be discarded by the UPF, SMF, or NEF.

[0209] If you want an indication that DL data has been buffered, or when buffered DL data has been delivered to the UE, AF may request a repeated "Downlink Data Delivery Status" notification.

[0210] When MICO (Mobile Initiated Connection Only) mode or Extended Idle Mode DRX is enabled, AF can determine when a UE transitions to idle mode through Idle Status Indication. When requesting to receive "UE Reachability" or "Availability after DDN failure" notifications, AF may also request Idle Status Indication. If UDM and AMF support Idle Status Indication, when a UE with MICO mode or Extended Idle Mode DRX enabled transitions to idle mode, AMF may include in the notification to NEF the time the UE transitioned to idle mode, active time, periodic registration update timer granted to the UE by AMF, eDRX cycle length, and suggested number of downlink packets if values ​​are provided to SMF.

[0211] AF can provide UDM with parameters related to high-latency communication for various methods through NEF. UDM can additionally pass parameters to other NFs (e.g., AMF or SMF).

[0212] If the AMF recognizes that some signaling or data is pending in the network for a UE known to be unreachable for a long time, such as an Extended Idle Mode DRX, an Extended DRX for RRC_INACTIVE, or a UE with MICO enabled, the AMF may maintain the N2 connection for at least the Extended Connected Time and provide the Extended Connected Time value to the RAN via an NG-AP message. The Extended Connected Time value may indicate the minimum time the RAN must keep the UE in the RRC_CONNECTED state, regardless of inactivity. During a handover between RAN nodes, if some signaling or data is still pending, the target AMF may transmit the Extended Connected Time value to the target RAN node.

[0213] As described above, the NG-RAN can transmit information related to the eDRX (e.g., eDRX value) while requesting the CN to buffer DL data. Upon arrival of DL data, the AMF can determine whether the UE is currently reachable based on the eDRX information received from the NG-RAN, and then request RAN paging from the NG-RAN. Accordingly, it is possible to support eDRX of 10.24 seconds or longer for UEs in the RRC_INACTIVE state. However, since the AMF determines whether the current UE is reachable by considering the eDRX value sent by the NG-RAN and / or the transition time to the RRC_CONNECTED state, if the AMF incorrectly sets the corresponding timer value, unnecessary delays may occur or there is a possibility of DL data loss. Additionally, because the SMF or UPF must first verify UE reachability via the AMF before delivering buffered DL data to the NG-RAN, service operations may occur frequently between core network functions. To avoid this, core network functions such as SMF or UPF need to directly determine whether the UE is reachable, and / or core network functions need to directly notify the RAN of the occurrence of buffered DL data.

[0214] A Service Based Interface (SBI) related to the implementation of this specification is described.

[0215] For example, SBI can use a request-response-based message exchange structure. A first NF, which is a service consumer, can generate an HTTP (HyperText Transfer Protocol) request message and send it to a second NF, which is a service producer, and after processing the request, the second NF can send an HTTP response message back to the first NF.

[0216] An HTTP request message may include at least one of an HTTP method (at least one of POST, GET, PUT, PATCH, DELETE), a Uniform Resource Identifier (URI), HTTP headers, and a message body. The message body may be written in JSON format. An HTTP response message may include at least one of a status code, HTTP headers, and a message body.

[0217] URIs for service requests can follow the format "{apiRoot} / {apiName} / {apiVersion} / {resourceUri}". apiRoot can be the address of the service producer. apiName can be the service name (e.g., nudm-sdm, nsmf-pdusession). apiVersion can be the API version (e.g., v1). resourceUri can represent the path to a specific resource.

[0218] SBI can support both synchronous and asynchronous communication. In synchronous communication, the service consumer can wait until it receives a response after sending a request. In asynchronous communication, the service consumer sends a callback URI included in the request message, and the service producer can immediately reply with an acceptance response (e.g., HTTP 201 Created) and notify the result via the callback URI when processing is complete.

[0219] In SBI, to receive notifications when a specific event occurs, a service consumer can send an event subscription request to a service producer. The request may include a URI to receive the notification. When a subscribed event occurs, the service producer can send a notification message to the service consumer using the HTTP POST method.

[0220] As an example of SBI-based message exchange, in the UE registration process, the AMF can send an authentication request message to the AUSF via the "POST / nausf-auth / v1 / ue-authentications" URI for user authentication. The AUSF can reply to the AMF with a response message containing an authentication vector. Subsequently, the AMF can send a registration request to the UDM via the "PUT / nudm-uecm / v1 / {supi} / registrations / amf-3gpp-access" URI to store user registration information. The UDM can reply to the AMF with a response indicating that registration is complete.

[0221] In 5G, SBI was defined within the 5GC (5G Core) to facilitate standardization in a form suitable for providing services in a cloud environment. However, between NG-RAN and 5GC, the conventional point-to-point NG-AP protocol was defined without introducing SBI. Meanwhile, as 3GPP proceeded with standardization for NG-RAN, the standardization process involved dividing NG-RAN into CU (Centralized Unit)-CP (Control Plane) / CU-UP (User Plane) / DU (Distributed Unit).

[0222] Figure 7 shows an example of the logical architecture of an O-RAN to which the implementation of the present specification applies.

[0223] Referring to Fig. 7, O-RAN (Open RAN) aims for a cloud-based RAN and defines interfaces (e.g., A1, E2) that are not defined in 3GPP standards. Given this situation, there is a possibility that SBI will be used in 6G between the RAN and the core network and / or between RANs.

[0224] Therefore, in situations where SBI is used between the RAN and the core network and / or between RANs in 6G, a method may be required for the RAN to request buffering of DL data from a network function responsible for session management in 6G (e.g., 6G SMF), and then notify the RAN when the DL data arrives.

[0225] According to the implementation of the present specification, in order to support eDRX of 10.24 seconds or more for a UE in the RRC_INACTIVE state in 6G, a method may be proposed in which the RAN and the session management network function (e.g., 6G SMF, which can be simply referred to as the session management node hereinafter) can directly exchange service operations.

[0226] According to an implementation of the present specification, a method may be proposed in which the RAN notifies the session management node that DL data buffering is required in the core network and performs an event subscription for the arrival of DL data to the session management node.

[0227] According to the implementation of the present specification, when DL data for a UE that has entered power saving mode arrives, a method may be proposed in which a session management node immediately notifies the RAN and / or notifies it only when it is determined that the current UE is reachable based on information received from the RAN.

[0228] According to the implementation of the present specification, when the RAN supports long eDRX, a method may be proposed in which a session management node performs an event subscription related to long eDRX to the RAN in advance and performs the following action based on an event notification received from the RAN.

[0229] The method described herein may be applied only when a session management node or a network function responsible for the user plane in 6G (e.g., 6G UPF) is buffering DL data to be sent to the UE. Alternatively, the method described herein may be applied only when other core network functions in 6G (e.g., 6G SMSF (Short Message Service Function), 6G LMF (Location Management Function), 6G GMLC (Gateway Mobile Location Center)) have DL signaling to be sent to the UE. Alternatively, the method described herein may be applied in both cases.

[0230] In this specification, RAN, 6G RAN, RAN NF, 6G RAN NF, base station, etc. may be used interchangeably. In this specification, SMF, 6G SMF, SM NF, 6G SM NF, etc. may be used interchangeably.

[0231] The service operations between core network NFs and between a RAN and core network NFs and / or a RAN described in this specification may be at least one of service operations that existed in conventional 5G and / or service operations that will be newly defined in 6G. The messages between a RAN and a UE described in this specification may be at least one of RRC messages that existed in conventional 5G and / or RRC messages that will be newly defined in 6G or messages of a protocol that may be newly defined in 6G.

[0232] In the methods and / or procedures described herein, multiple steps may be performed simultaneously and / or in parallel. In the methods and / or procedures described herein, multiple steps may be performed in a different order than that described in the drawings. In the methods and / or procedures described herein, some steps may be omitted without loss of generality.

[0233] The names of information, indications, and / or parameters described in this specification are merely illustrative. The names of information, indications, and / or parameters described in this specification may be replaced with other names or interpreted as such for the procedures, purposes, and methods proposed in this specification.

[0234] The following drawings are made to illustrate a specific example of the present disclosure. The names of specific devices or specific signals / messages / fields described in the drawings are presented as examples, and therefore the technical features of the present disclosure are not limited to the specific names used in the following drawings.

[0235] FIG. 8 illustrates an example of a method performed by a base station to which an implementation of the present disclosure is applied.

[0236] In step S800, the method includes the step of receiving a subscription to an event related to eDRX from a session management node.

[0237] In some implementations, the base station and the session management node can perform service operations through a service-based direct interface.

[0238] In some implementations, the eDRX may include a long eDRX having a cycle period of 10.24 seconds or more.

[0239] In some implementations, the event may include at least one of i) when the base station decides to apply long eDRX when the UE transitions to an inactive state, ii) when the base station decides that buffering of the downlink data is required in the core network, iii) when the reachable UE changes to an unreachable state, or iv) when the unreachable UE changes to a reachable state.

[0240] In step S810, the method includes the step of transmitting information indicating that buffering of downlink data is required to the session management node based on the occurrence of the event.

[0241] In some implementations, along with information indicating that buffering of the downlink data is required, at least one of i) information indicating that it has been decided to apply eDRX in an inactive state for the UE, ii) an eDRX value determined by the base station for the UE, iii) an estimated maximum wait time, or iv) the current RRC state of the UE may be transmitted together.

[0242] In some implementations, buffering of the downlink data may be performed at the session management node based on information indicating that buffering of the downlink data is required.

[0243] In step S820, the method includes the step of transmitting information related to the initiation of the application of the eDRX to the UE to the session management node.

[0244] In some implementations, information regarding the initiation of the application of the eDRX may be transmitted in response to an event subscription of the session management node regarding the reachability of the UE.

[0245] In some implementations, at least one of the NF service instance ID, NF service set ID, NF set ID, service name, and notification target address of the base station may be transmitted to the session management node.

[0246] In step S830, the method includes the step of transmitting information related to the termination of the application of the eDRX to the UE to the session management node, based on what the UE is reachable.

[0247] In some implementations, after transmitting information regarding the termination of the application of the eDRX to the UE, a message may be received from the session management node notifying of the arrival of the downlink data and / or requesting a transition to a connection state for the UE. The message may include paging policy differentiation information for the downlink data.

[0248] In some implementations, the base station may have at least one of the NF ID of the session management node for the active session of the UE or information related to service capability regarding whether the session management node can support buffering of the downlink data for high-latency communication.

[0249] In some implementations, the session management node may have at least one of the NF ID of the base station for the active session of the UE, and information related to service capability regarding whether the base station can support a UE having an eDRX period of 10.24 seconds or more in an inactive state.

[0250] Additionally, the method described in Fig. 8 from the perspective of a base station can be performed by the second wireless device (200) shown in Fig. 2.

[0251] The base station includes one or more transceivers, one or more processors, and one or more memories that can be connected to operate with the one or more processors and store instructions for performing the method described in FIG. 8 based on execution by the at least one processor.

[0252] More specifically, the base station receives subscriptions for events related to eDRX from the session management node.

[0253] In some implementations, the base station and the session management node can perform service operations through a service-based direct interface.

[0254] In some implementations, the eDRX may include a long eDRX having a cycle period of 10.24 seconds or more.

[0255] In some implementations, the event may include at least one of i) when the base station decides to apply long eDRX when the UE transitions to an inactive state, ii) when the base station decides that buffering of the downlink data is required in the core network, iii) when the reachable UE changes to an unreachable state, or iv) when the unreachable UE changes to a reachable state.

[0256] Based on the occurrence of the above event, the base station transmits information to the session management node indicating that buffering of downlink data is required.

[0257] In some implementations, along with information indicating that buffering of the downlink data is required, at least one of i) information indicating that it has been decided to apply eDRX in an inactive state for the UE, ii) an eDRX value determined by the base station for the UE, iii) an estimated maximum wait time, or iv) the current RRC state of the UE may be transmitted together.

[0258] In some implementations, buffering of the downlink data may be performed at the session management node based on information indicating that buffering of the downlink data is required.

[0259] The base station transmits information related to the initiation of the application of the eDRX to the UE to the session management node.

[0260] In some implementations, information regarding the initiation of the application of the eDRX may be transmitted in response to an event subscription of the session management node regarding the reachability of the UE.

[0261] In some implementations, at least one of the NF service instance ID, NF service set ID, NF set ID, service name, and notification target address of the base station may be transmitted to the session management node.

[0262] Based on the reachability of the above UE, the base station transmits information related to the termination of the application of the eDRX to the above UE to the above session management node.

[0263] In some implementations, after transmitting information regarding the termination of the application of the eDRX to the UE, a message may be received from the session management node notifying of the arrival of the downlink data and / or requesting a transition to a connection state for the UE. The message may include paging policy differentiation information for the downlink data.

[0264] In some implementations, the base station may have at least one of the NF ID of the session management node for the active session of the UE or information related to service capability regarding whether the session management node can support buffering of the downlink data for high-latency communication.

[0265] In some implementations, the session management node may have at least one of the NF ID of the base station for the active session of the UE, and information related to service capability regarding whether the base station can support a UE having an eDRX period of 10.24 seconds or more in an inactive state.

[0266] Various implementations and / or embodiments of this specification are described below.

[0267] 1. First implementation

[0268] FIGS. 9 and FIGS. 10 illustrate examples of procedures related to the first implementation of the present specification.

[0269] According to the first embodiment of this specification, an SM NF (e.g., 6G SMF) may subscribe to events regarding whether Long eDRX is applied, whether DL data buffering is applied in a CN NF (e.g., SM NF or UP NF (e.g., 6G UPF)), UE reachability, etc., to a RAN (e.g., 6G RAN / base station). Additionally, according to the first embodiment of this specification, based on event notifications sent by the RAN, the SM NF (e.g., 6G SMF) may perform DL data buffering and / or forward DL data notifications to the RAN.

[0270] The RAN may possess information such as the NF ID of the serving SM NF (e.g., 6G SMF) for the UE's active session (e.g., PDU session) and service capability regarding whether the CN NF (e.g., SM NF or UP NF) can support DL data buffering for high-latency communication. The SM NF may possess information such as the NF ID of the serving RAN for the UE's active session and service capability regarding whether the RAN can support a UE in an inactive state (e.g., RRC_INACTIVE) having an eDRX cycle of 10.24 seconds or more. The RAN and / or SM NF may obtain the above-mentioned information through an NF service registration / discovery procedure with an NR (Network Repository) NF (e.g., 6G NRF). Alternatively, the RAN and / or SM NF may obtain the above-mentioned information from an MM (Mobility Management) NF (e.g., 6G AMF) during the UE registration and / or PDU session establishment procedure.

[0271] Some procedures / steps of the first implementation of this specification may correspond to some procedures / steps described in FIG. 8.

[0272] First, the procedure of Fig. 9 is explained.

[0273] 1) Step S900: Assume that the UE has established a session with the network and is receiving services. For example, the session establishment procedure may follow the PDU session establishment procedure of FIGS. 5 and FIGS. 6 described above.

[0274] 2) Step S910: The SM NF can perform an event subscription to obtain Long eDRX information from the UE's serving RAN. For example, the SM NF can send an Nran_EventExposure_Subscribe message to the RAN for the event subscription.

[0275] For example, SM NF can perform an event subscription to be notified to SM NF when the following event occurs.

[0276] - Where the RAN decides to apply Long eDRX when the UE transitions to an inactive state (e.g., RRC_INACTIVE) and / or where the RAN decides that DL data buffering needs to be performed in a CN NF (e.g., SM NF or UP NF);

[0277] - Cases where a previously reachable UE is no longer reachable, or vice versa

[0278] SM NF may request one or more of the following information from RAN in addition to Long eDRX information.

[0279] - eDRX value determined by the RAN for the UE;

[0280] - Time until the UE becomes reachable again (e.g., estimated maximum wait time);

[0281] - UE's current RRC status

[0282] 3) Step S920: The RAN may decide to transition the UE to an inactive state and, at the same time, apply eDRX for 10.24 seconds or longer. For example, the RAN may decide to buffer DL data in a CM NF (e.g., SM NF or UP NF).

[0283] 4) Step S930: The RAN may notify the SM NF that it has decided to apply Long eDRX to the UE while it is disabled. For example, the RAN may send an Nran_EventExposure Notify message to the SM NF to notify that Long eDRX is enabled (e.g., Long eDRX enabled). Additionally, the RAN may also notify that DL data buffering needs to be performed at the CN NF (e.g., SM NF or UP NF). Additionally, if the SM NF further requests it, the RAN may send to the SM NF at least one of the eDRX value determined by the RAN for the UE, the time until the UE becomes reachable again (e.g., estimated maximum wait time), or the UE's current RRC status.

[0284] 5) Step S940: SM NF may start buffering DL data associated with a specific session of the UE (e.g., PDU session). Buffering of DL data may be performed based on information received in Step S930.

[0285] If DL data buffering for the above session needs to be performed in the UP NF rather than the SM NF, the SM NF may notify the UP NF that buffering is needed for the DL data associated with the UE's above session through N4 signaling (or a newly defined signaling between the SM NF and the UP NF).

[0286] 6) Step S950: The SM NF can perform event subscription to obtain reachability information for the UE from the UE's serving RAN. For example, the SM NF can send an Nran_EventExposure_Subscribe message to the RAN for event subscription.

[0287] The event subscription for obtaining reachability information for the UE in step S950 can be performed together with the event subscription for obtaining Long eDRX information in step S910. In this case, step S950 can be omitted.

[0288] 7) Step S960: The RAN may transition the UE to a disabled state. For example, the RAN may deliver an RRCR remove message containing SuspendConfig to the UE. SuspendConfig may contain information necessary for the UE to transition to a disabled state, such as eDRX values.

[0289] The UE can transition to a disabled state after receiving a message. If SuspendConfig contains an eDRX value of 10.24 seconds or longer, it can enter power saving mode for that time.

[0290] 8) Step S970: The RAN can notify the SM NF that the UE has transitioned to an inactive state and has entered power saving mode due to the application of Long eDRX. For example, the RAN can send an Nran_EventExposure Notify message to the SM NF to notify of the UE's transition to an inactive state and / or the start of Long eDRX.

[0291] If the expected maximum waiting time is received in step S930, SM NF may execute a timer set to that value.

[0292] The procedure of Fig. 10, which is performed following the procedure of Fig. 9, is described.

[0293] 1) Step S1000: SM NF or UP NF can receive DL data related to a specific session of the UE (e.g., PDU session).

[0294] When DL data buffering is being performed in the UP NF, the UP NF may notify the SM NF of the arrival of DL data and together transmit paging policy differentiation information consisting of one or more of the following.

[0295] - PPI (Paging Policy Indicator)

[0296] - ARP (Allocation and Retention Priority)

[0297] - 5QI (5G QoS Identifier)

[0298] DL data size

[0299] - QFI (QoS Flow Identifier)

[0300] - PDU Session ID

[0301] When DL data buffering is performed in SM NF, SM NF can directly configure paging policy differentiation information composed of one or more of the information described above.

[0302] 2) Step S1010: The RAN can determine whether the current UE is reachable. The RAN can determine whether the current UE is reachable based on the eDRX value determined in Step S920 of FIG. 9. For example, the RAN can execute a timer set to the eDRX value in Step S960 of FIG. 9, and when the timer expires, determine that the UE is currently reachable and perform Step S1020 described below.

[0303] If the SM NF receives the estimated maximum wait time in step S930 of FIG. 9, the SM NF, which is not the RAN, can also determine whether the UE is reachable. For example, if the timer related to the estimated maximum wait time executed in S970 of FIG. 9 has not yet expired, the SM NF may determine that the UE is not currently reachable and may request additional buffering of DL data until that time by transmitting the estimated wait time value, which consists of the remaining time until the timer expires, to the UP NF. For example, if the timer related to the estimated maximum wait time executed in S970 of FIG. 9 has expired, the SM NF may determine that the UE is currently reachable and perform step S1030, which will be described later.

[0304] 3) Step S1020: If the RAN determines in Step S1010 that the UE is currently reachable, it may notify the SM NF that the UE has exited power saving mode (or that the UE may transition to a connected state (e.g., RRC_CONNECTED) or that the Long eDRX for the UE has ended). For example, the RAN may send an Nran_EventExposure Notify message to the SM NF to notify that the UE has exited power saving mode, that the UE may transition to a connected state, or that the Long eDRX for the UE has ended.

[0305] At this time, information such as the NF Service Instance ID, NF Service Set ID, NF Set ID, Service name, and Notification Target Address may be transmitted together to the SM NF. This information may be used when the SM NF notifies the RAN of the arrival of DL data and requests the UE to transition to a connected state in step S1030, which will be described later. This information may be provided to the SM NF in step S930 or step S970 of FIG. 9.

[0306] 4) Step S1030: SM NF may send an Nran_MT_SendData Request message to RAN to notify that DL data has arrived for a specific session of the UE and that the UE must be transitioned to a connection state to deliver it. Additionally, paging policy differentiation information related to the buffered DL data may be sent to RAN.

[0307] 5) Step S1040: The RAN sends a RAN paging message, and the UE receiving it may initiate a resumption procedure to transition to a connection state. If the UE connects to a new RAN other than the RAN that sent the RAN paging, the UE context may be transferred to the new RAN through a UE context retrieval procedure, and information regarding the serving SM NF (e.g., 6G SMF) may also be transferred during this process.

[0308] 6) Step S1050: The RAN can respond to the SM NF by sending an Nran_MT_SendData Response message. Through this, the RAN can inform the SM NF that the UE is currently connected and is capable of sending and receiving data.

[0309] When the UP NF is buffering DL data, the SM NF that receives the Nran_MT_SendData Response message can notify the UP NF via N4 signaling (or a newly defined signaling between the SM NF and the UP NF) that the UE is currently connected and can now send and receive data.

[0310] 7) Step S1060: The SM NF or UP NF may transfer the buffered DL data to the UE via the RAN. If the UE has UL data to transmit to the network, the UL data may be transferred to the UP NF via the RAN.

[0311] 2. Second implementation

[0312] FIGS. 11 and FIGS. 12 illustrate examples of procedures related to the second implementation of the present specification.

[0313] According to the second implementation of the present specification, the RAN may request DL data buffering from the SM NF (e.g., 6G SMF) and provide an estimated maximum wait time value. The SM NF may determine whether the UE is currently reachable based on the information received from the RAN, and may notify the RAN of the arrival of DL data only if it determines that the UE is reachable.

[0314] The RAN may have information such as the NF ID of the serving SM NF (e.g., 6G SMF) for the UE's active session (e.g., PDU session), and service capability regarding whether the CN NF (e.g., SM NF or UP NF) can support DL data buffering for high-latency communication. The SM NF may have information such as the NF ID of the serving RAN for the UE's active session, and service capability regarding whether the RAN can support a UE in an inactive state (e.g., RRC_INACTIVE) having an eDRX cycle of 10.24 seconds or more. The RAN and / or SM NF may obtain the above information through an NF service registration / discovery procedure with an NR NF (e.g., 6G NRF). Alternatively, the RAN and / or SM NF may obtain the above information from an MM NF (e.g., 6G AMF) during the UE registration and / or PDU session establishment procedure.

[0315] First, the procedure of Fig. 11 is explained.

[0316] 1) Step S1100: Assume that the UE is receiving services by establishing a session with the network. For example, the session establishment procedure may follow the PDU session establishment procedure of FIGS. 5 and FIGS. 6 described above.

[0317] 2) Step S1110: The RAN may decide to transition the UE to an inactive state (e.g., RRC_INACTIVE) and, at the same time, apply eDRX for 10.24 seconds or longer. For example, the RAN may decide to buffer DL data in a CM NF (e.g., SM NF or UP NF).

[0318] 3) Step S1120: The RAN may send an Nsmf_PDUSession_BufferMTData Request message to the SM NF. The RAN may notify the SM NF or UP NF via the Nsmf_PDUSession_BufferMTData Request message that the UE will transition to an inactive state with an eDRX of 10.24 seconds or longer. The RAN may notify the SM NF or UP NF via the Nsmf_PDUSession_BufferMTData Request message that DL data related to a specific session of the UE needs to be buffered.

[0319] Additionally, the Nsmf_PDUSession_BufferMTData Request message may include the time it takes for the UE to return to a connected state (e.g., RRC_CONNECTED) (e.g., estimated maximum wait time). This time may take into account both the eDRX value that the RAN sets for the UE and the time it takes for the RAN to transition the UE from an inactive state to a connected state. Additionally, the Nsmf_PDUSession_BufferMTData Request message may include notification target address information that the SM NF will use to notify the RAN when DL data subsequently arrives at the SM NF or UP NF.

[0320] 4) Step S1130: The SM NF may start buffering DL data related to a specific session of the UE. Buffering of DL data may be performed based on information received in Step S1120. If DL data buffering for said session needs to be performed by the UP NF rather than the SM NF, the SM NF may notify the UP NF that buffering is needed for DL ​​data related to the specific session of the UE through N4 signaling (or a newly defined signaling between the SM NF and the UP NF).

[0321] Additionally, SM NF can execute a timer set to the expected maximum waiting time value received in step S1120.

[0322] 5) Step S1140: The SM NF can notify the RAN that DL data buffering has started in the SM NF or UP NF by sending an Nsmf_PDUSession_BufferMTData Response message.

[0323] 6) Step S1150: The RAN may transition the UE to a disabled state. For example, the RAN may deliver an RRCR remove message containing SuspendConfig to the UE. SuspendConfig may contain information necessary for the UE to transition to a disabled state, such as eDRX values.

[0324] The UE can transition to a disabled state after receiving a message. If SuspendConfig contains an eDRX value of 10.24 seconds or longer, it can enter power saving mode for that time.

[0325] The procedure of Fig. 12, which is performed following the procedure of Fig. 11, is described.

[0326] 1) Step S1200: SM NF or UP NF can receive DL data related to a specific session of the UE (e.g., PDU session).

[0327] When DL data buffering is being performed in the UP NF, the UP NF may notify the SM NF of the arrival of DL data and together transmit paging policy differentiation information consisting of one or more of the following.

[0328] - PPI (Paging Policy Indicator)

[0329] - ARP (Allocation and Retention Priority)

[0330] - 5QI (5G QoS Identifier)

[0331] DL data size

[0332] - QFI (QoS Flow Identifier)

[0333] - PDU Session ID

[0334] When DL data buffering is performed in SM NF, SM NF can directly configure paging policy differentiation information composed of one or more of the information described above.

[0335] 2) Step S1210: The SM NF can determine whether the UE is reachable. For example, if the timer related to the estimated maximum waiting time executed in S1130 of FIG. 11 has not yet expired, the SM NF may determine that the UE is not currently reachable and may request additional buffering of DL data until that time by passing an estimated waiting time value, which consists of the remaining time until the timer expires, to the UP NF. For example, if the timer related to the estimated maximum waiting time executed in S1130 of FIG. 11 has expired, the SM NF may determine that the UE is currently reachable and perform the step S1220 described below.

[0336] 3) Step S1220: SM NF may send an Nsmf_PDUSession_ArriveMTData Notify message to RAN to notify that DL data has arrived for a specific session of the UE and that the UE must be transitioned to a connected state to deliver it. Additionally, paging policy differentiation information related to the buffered DL data may be sent to RAN.

[0337] 4) Step S1230: The RAN sends a RAN paging message, and the UE receiving it may initiate a resumption procedure to transition to a connected state. If the UE connects to a new RAN other than the RAN that sent the RAN paging, the UE context may be transferred to the new RAN through a UE context retrieval procedure, and information regarding the serving SM NF (e.g., 6G SMF) may also be transferred during this process.

[0338] 5) Step S1240: The RAN can notify the SM NF that the UE is currently connected and is capable of sending and receiving data. For example, the RAN can use the Nsmf_PDUSession_UpdateSMContext procedure.

[0339] When the UP NF is buffering DL data, the SM NF can notify the UP NF through N4 signaling (or a newly defined signaling between the SM NF and the UP NF) that the UE is currently connected and can now transmit and receive data.

[0340] 6) Step S1250: The SM NF or UP NF may transfer the buffered DL data to the UE via the RAN. If the UE has UL data to transmit to the network, the UL data may be transferred to the UP NF via the RAN.

[0341] 3. Third implementation

[0342] FIGS. 13 and FIGS. 14 illustrate examples of procedures related to the third implementation of the present specification.

[0343] According to the third implementation of this specification, the RAN may request DL data buffering from the SM NF (e.g., 6G SMF) and provide binding indication information to be used for DL ​​data notification. The SM NF may notify the RAN of the arrival of DL data based on the binding indication received from the RAN, and the RAN may determine whether the UE is reachable and notify the SM NF accordingly.

[0344] The RAN may have information such as the NF ID of the serving SM NF (e.g., 6G SMF) for the UE's active session (e.g., PDU session), and service capability regarding whether the CN NF (e.g., SM NF or UP NF) can support DL data buffering for high-latency communication. The SM NF may have information such as the NF ID of the serving RAN for the UE's active session, and service capability regarding whether the RAN can support a UE in an inactive state (e.g., RRC_INACTIVE) having an eDRX cycle of 10.24 seconds or more. The RAN and / or SM NF may obtain the above information through an NF service registration / discovery procedure with an NR NF (e.g., 6G NRF). Alternatively, the RAN and / or SM NF may obtain the above information from an MM NF (e.g., 6G AMF) during the UE registration and / or PDU session establishment procedure.

[0345] First, the procedure of Fig. 13 is explained.

[0346] 1) Step S1300: Assume that the UE has established a session with the network and is receiving services. For example, the session establishment procedure may follow the PDU session establishment procedure of FIGS. 5 and FIGS. 6 described above.

[0347] 2) Step S1310: The RAN may decide to transition the UE to an inactive state (e.g., RRC_INACTIVE) and, at the same time, apply eDRX for 10.24 seconds or longer. For example, the RAN may decide to buffer DL data in a CM NF (e.g., SM NF or UP NF).

[0348] 3) Step S1320: The RAN may send an Nsmf_PDUSession_BufferMTData Request message to the SM NF. The RAN may notify via the Nsmf_PDUSession_BufferMTData Request message that the UE will transition to an inactive state with an eDRX of 10.24 seconds or longer. The RAN may notify the SM NF or UP NF via the Nsmf_PDUSession_BufferMTData Request message that DL data related to a specific session of the UE needs to be buffered.

[0349] In addition, the Nsmf_PDUSession_BufferMTData Request message may further include binding marker information to be used later when the SM NF notifies the RAN of the arrival of DL data. For example, the binding marker information may include information such as the RAN's NF service instance ID, NF service set ID, NF set ID, service name, and notification target address to be used when the SM NF notifies the RAN of the arrival of DL data and requests a transition to a connection state for the UE in step S1410 of FIG. 14, which will be described later.

[0350] 4) Step S1330: The SM NF may start buffering DL data related to a specific session of the UE. Buffering of DL data may be performed based on information received in Step S1320. If DL data buffering for said session needs to be performed by the UP NF rather than the SM NF, the SM NF may notify the UP NF that buffering is needed for DL ​​data related to the specific session of the UE through N4 signaling (or a newly defined signaling between the SM NF and the UP NF).

[0351] 5) Step S1340: The SM NF can notify the RAN that DL data buffering has started in the SM NF or UP NF by sending an Nsmf_PDUSession_BufferMTData Response message.

[0352] 6) Step S1350: The RAN may transition the UE to a disabled state. For example, the RAN may deliver an RRCR remove message containing SuspendConfig to the UE. SuspendConfig may contain information necessary for the UE to transition to a disabled state, such as eDRX values.

[0353] The UE can transition to a disabled state after receiving a message. If SuspendConfig contains an eDRX value of 10.24 seconds or longer, it can enter power saving mode for that time.

[0354] The procedure of Fig. 14, which is performed following the procedure of Fig. 13, is described.

[0355] 1) Step S1400: SM NF or UP NF can receive DL data related to a specific session of the UE (e.g., PDU session).

[0356] When DL data buffering is being performed in the UP NF, the UP NF may notify the SM NF of the arrival of DL data and together transmit paging policy differentiation information consisting of one or more of the following.

[0357] - PPI (Paging Policy Indicator)

[0358] - ARP (Allocation and Retention Priority)

[0359] - 5QI (5G QoS Identifier)

[0360] DL data size

[0361] - QFI (QoS Flow Identifier)

[0362] - PDU Session ID

[0363] When DL data buffering is performed in SM NF, SM NF can directly configure paging policy differentiation information composed of one or more of the information described above.

[0364] 2) Step S1410: Based on the binding indication information received in Step S1320 of FIG. 13, SM NF can send an Nran_MT_SendData Request message to RAN to notify that DL data has arrived for a specific session of UE and that UE must be transitioned to a connected state to deliver it. Additionally, paging policy differentiation information related to the buffered DL data can be transmitted to RAN.

[0365] 3) Step S1420: The RAN can determine whether the current UE is reachable. The RAN can determine whether the current UE is reachable based on the eDRX value determined in Step S1310 of FIG. 13. For example, the RAN can execute a timer set to the eDRX value in Step S1350 of FIG. 13, and if the timer expires, determine that the UE is currently reachable and perform Step S1430 described below. If the timer expires, the RAN determines that the UE is currently reachable, skips Step S1430 described below, and performs Step S1440 described below.

[0366] 4) Step S1430: If it is determined in Step S1420 that the UE is not yet reachable, the RAN may request additional buffering until the SM NF by transmitting an estimated maximum wait time value, which consists of the time until the timer expires. The estimated maximum wait time value may be transmitted via the Nran_MT_SendData Reject message. If the UP NF is buffering DL data, the SM NF may transmit this back to the UP NF to request additional buffering.

[0367] 5) Step S1440: If the UE is determined to be reachable, the RAN sends a RAN paging message, and the UE receiving it may initiate a resumption procedure to transition to a connected state. If the UE connects to a new RAN other than the RAN that sent the RAN paging, the UE context may be transferred to the new RAN through a UE context retrieval procedure, and information regarding the serving SM NF (e.g., 6G SMF) may also be transferred during this process.

[0368] 6) Step S1450: If Step S1430 is omitted, the RAN may respond to the SM NF via the Nran_MT_SendData Response message. Through this, the RAN may inform the SM NF that the UE is currently connected and capable of sending and receiving data.

[0369] 7) Step S1460: If Step S1430 is performed, the RAN may initiate the Nsmf_PDUSession_UpdateSMContext procedure to inform the SM NF that the UE is currently connected and capable of transmitting and receiving data.

[0370] If the UP NF is buffering DL data, after step S1450 or step S1460, the SM NF may notify the UE that it is currently connected and that data transmission and reception is possible from now on through N4 signaling (or a newly defined signaling between the SM NF and the UP NF).

[0371] 8) Step S1470: The SM NF or UP NF may transfer the buffered DL data to the UE via the RAN. If the UE has UL data to transmit to the network, the UL data may be transferred to the UP NF via the RAN.

[0372] The implementation of this specification described above explains the case where an SM NF or UP NF buffers DL data to be sent to a UE, but this is merely an example. The implementation of this specification is also applicable when other CN NFs (e.g., 6G SMSF, 6G LMF, 6G GMLC) have DL signaling to be sent to a UE.

[0373] For example, in the first implementation described above, the CN NF may pre-subscribe to the RAN for events asking for information such as whether buffering of DL signaling is required or whether the UE is in a reachable state. Based on the event notifications transmitted by the RAN, the CN NF may perform additional actions such as buffering DL signaling and / or DL ​​signaling notifications.

[0374] For example, in the implementation 2 described above, the RAN may notify the CN NF, as in step S1120 of FIG. 11, when it decides to apply eDRX to the UE. When DL signaling to be transmitted to the UE arises, the CN NF may not transmit it immediately to the RAN, but may first determine whether the UE is reachable based on the estimated maximum wait time received from the RAN. If it is determined that the UE is reachable, the CN NF may notify the RAN that DL signaling has arrived and, when the UE transitions to a connected state through RAN paging and UE resumption procedures, transmit the DL signaling to the UE via the RAN.

[0375] For example, in the implementation 3 described above, the RAN may notify the CN NF, as in step S1320 of FIG. 13, when it decides to apply eDRX to the UE. If there is DL signaling to be transmitted to the UE, the CN NF may transmit it immediately to the RAN. After the UE transitions to a connected state and the RAN notifies the CN NF, the CN NF may transmit the DL signaling to the UE. If the UE is unreachable, the RAN may notify the CN NF of the expected maximum wait time, as in step S1430 of FIG. 14.

[0376] This specification may have various effects.

[0377] For example, the RAN can determine whether the UE is reachable and notify the SM NF directly. For example, the RAN can calculate the time until the UE becomes reachable and transmit it directly to the SM NF.

[0378] For example, it can prevent the discarding of DL data due to incorrect settings of the expected maximum wait time, incorrect judgment of UE reachability, and / or unnecessary signaling exchanges between the RAN and SM NF.

[0379] The effects obtainable through the specific examples of this specification are not limited to those listed above. For example, there may be various technical effects that a person with ordinary skill in the related art can understand or derive 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.

[0380] The claims described in this specification may be combined in various ways. For example, the technical features of the method claims in this specification may be combined to be implemented as a device, and the technical features of the device claims in this specification may be combined to be implemented as a method. Furthermore, the technical features of the method claims and the technical features of the device claims in this specification may be combined to be implemented as a device, and the technical features of the method claims and the technical features of the device claims in this specification may be combined to be implemented as a method. Other implementations are within the scope of the following claims.

Claims

1. In a method performed by a base station, A step of receiving subscriptions for events related to eDRX (enhanced discontinuous reception) from a session management node; A step of transmitting information indicating that buffering of downlink data is required to the session management node based on the occurrence of the above event; A step of transmitting information related to the initiation of the application of the eDRX to the UE (User Equipment) to the session management node; and A method comprising the step of transmitting information related to the termination of the application of the eDRX to the UE to the session management node, based on whether the UE is reachable.

2. In Paragraph 1, A method in which the above base station and the above session management node perform service operations through a service-based direct interface.

3. In Paragraph 1, The above eDRX is a method comprising a long eDRX having a cycle period of 10.24 seconds or more.

4. In Paragraph 1, The above event comprises at least one of the following: i) when the base station decides to apply long eDRX when the UE transitions to an inactive state; ii) when the base station decides that buffering of the downlink data is required in the core network; iii) when the reachable UE changes to an unreachable state; or iv) when the unreachable UE changes to a reachable state.

5. In Paragraph 1, A method in which, along with information indicating that buffering of the downlink data is required, at least one of i) information indicating that it has been decided to apply eDRX in an inactive state for the UE, ii) an eDRX value determined by the base station for the UE, iii) an estimated maximum wait time, or iv) the current radio resource control (RRC) status of the UE is transmitted together.

6. In Paragraph 1, A method for performing buffering of the downlink data at the session management node based on information indicating that buffering of the downlink data is required.

7. In Paragraph 1, A method in which information related to the initiation of the application of the above eDRX is transmitted in response to an event subscription of the session management node regarding the reachability of the above UE.

8. In Paragraph 1, A method in which at least one of the NF (network function) service instance ID, NF service set ID, NF set ID, service name, and notification target address of the base station is transmitted to the session management node.

9. In Paragraph 1, A method of receiving, after transmitting information regarding the termination of the application of the eDRX to the UE, a notification of the arrival of the downlink data from the session management node and / or a message requesting a transition to a connection state for the UE.

10. In Paragraph 9, The above message is a method including paging policy differentiation information for the downlink data.

11. In Paragraph 1, A method in which the base station has at least one of the NF ID of the session management node for the active session of the UE or information related to service capability regarding whether the session management node can support buffering of the downlink data for high-latency communication.

12. In Paragraph 1, A method in which the session management node has at least one of the NF ID of the base station for the active session of the UE, and information related to service capability regarding whether the base station can support a UE having an eDRX cycle of 10.24 seconds or more in an inactive state.

13. Regarding the base station At least one processor; and A base station comprising at least one memory that can be operably connected to at least one processor and stores an instruction to perform the method of claims 1 through 9 based on execution by at least one processor.

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