Lossless data communication method

Abstract

One disclosure of the present disclosure provides a method by which a CU-UP performs communication. The method comprises the steps of: receiving a bearer context-related request message from a CU-CP of a source base station, wherein the request message includes an indirect path indication and the indirect path indication indicates that a path between a remote UE and the source base station is an indirect path; transmitting a response message to the CU-CP on the basis of the request message; transmitting downlink data to the remote UE; receiving, from a DU of the source base station, a transmission state message indicating that the downlink data has been successfully transmitted to a relay UE for the remote UE; the CU-UP skipping discarding of the downlink data by the transmission state message on the basis of the indirect path indication and buffering the downlink data on the basis of the indirect path indication; and transmitting the buffered downlink data to a target base station on the basis of handover of the remote UE from the source base station to the target base station.

Description

Lossless data communication method

[0001] This specification relates to mobile communications.

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

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

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

[0005] When a Remote UE is handed over, a method is required to transmit downlink data to the Remote UE without loss.

[0006] The CU-CP transmits an indirect path indication to the CU-UP, and the CU-UP buffers downlink data based on this and transmits it to the target base station.

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

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

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

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

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

[0012] Figure 6 shows an example of the overall architecture of NG-RAN.

[0013] Figure 7 shows logical nodes (CU-C, CU-U, and DU) within a logical gNB / en-gNB.

[0014] Figure 8 shows a deployment scenario of gNB.

[0015] Figure 9 shows a flowchart according to an embodiment of the present specification.

[0016] Figure 10 illustrates the CU-UP procedure for the disclosure of this specification.

[0017] Figure 11 illustrates the CU-CP procedure for the disclosure of this specification.

[0018] The following techniques, devices, and systems can be applied to various wireless multiple access systems. Examples of multiple access systems include code division multiple access (CDMA) systems, frequency division multiple access (FDMA) systems, time division multiple access (TDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and multicarrier frequency division multiple access (MC-FDMA) systems. CDMA can be implemented via wireless technologies such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA can be implemented via wireless technologies such as global system for mobile communications (GSM), general packet radio service (GPRS), or enhanced data rates for GSM evolution (EDGE). OFDMA can be implemented using wireless technologies such as IEEE (Institute of Electrical and Electronics Engineers) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, or E-UTRA (evolved UTRA). UTRA is part of UMTS (universal mobile telecommunications system). 3GPP (3rd generation partnership project) LTE (long-term evolution) is part of E-UMTS (evolved UMTS) that uses E-UTRA.3GPP LTE uses OFDMA in the downlink (DL) and SC-FDMA in the uplink (UL). Evolution of 3GPP LTE includes LTE-A (advanced), LTE-A Pro, and / or 5G NR (new radio).

[0019] For convenience of explanation, the implementation of this specification is primarily described in relation to a 3GPP-based wireless communication system. However, the technical features of this specification are not limited thereto. For example, the following detailed description is provided based on a mobile communication system corresponding to a 3GPP-based wireless communication system. However, aspects of this specification that are not limited to a 3GPP-based wireless communication system can be applied to other mobile communication systems.

[0020] 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.

[0021] As used herein, "A or B" can mean "only A," "only B," or "both A and B." Alternatively, as used herein, "A or B" can be interpreted as "A and / or B." For example, as used herein, "A, B or C" can mean "only A," "only B," "only C," or "any combination of A, B and C."

[0022] As used herein, a slash ( / ) or a comma can mean "and / or." For example, "A / B" can mean "A and / or B." Accordingly, "A / B" can mean "only A," "only B," or "both A and B." For example, "A, B, C" can mean "A, B, or C."

[0023] In this specification, “at least one of A and B” may mean “only A,” “only B,” or “both A and B.” Additionally, in this specification, the expressions “at least one of A or B” or “at least one of A and / or B” may be interpreted identically to “at least one of A and B.”

[0024] Additionally, in this specification, “at least one of A, B and C” can mean “only A”, “only B”, “only C”, or “any combination of A, B and C”. Additionally, “at least one of A, B or C” or “at least one of A, B and / or C” can mean “at least one of A, B and C”.

[0025] Additionally, parentheses used herein may mean "for example." Specifically, when indicated as "control information (PDCCH)", "PDCCH" may be proposed as an example of "control information." In other words, "control information" in this specification is not limited to "PDCCH," and "PDCCH" may be proposed as an example of "control information." Furthermore, even when indicated as "control information (i.e., PDCCH)", "PDCCH" may be proposed as an example of "control information."

[0026] Technical features individually described in a single drawing in this specification may be implemented individually or simultaneously.

[0027] Although not limited thereto, the various descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed herein may be applied to various fields requiring wireless communication and / or connectivity between devices (e.g., 5G).

[0028] Hereinafter, the present specification will be described in more detail with reference to the drawings. In the following drawings and / or description, the same reference numbers may refer to the same or corresponding hardware blocks, software blocks, and / or functional blocks, unless otherwise indicated.

[0029] Figure 1 illustrates an example of a communication system to which the implementation of this specification is applied.

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

[0031] The three main requirement categories for 5G are (1) enhanced mobile broadband (eMBB), (2) massive machine type communication (mMTC), and (3) ultra-reliable and low latency communications (URLLC).

[0032] Referring to FIG. 1, a communication system (1) includes wireless devices (100a to 100f), a base station (BS; 200), and a network (300). FIG. 1 illustrates a 5G network as an example of a network of the communication system (1), but the implementation of the present disclosure is not limited to a 5G system and can be applied to future communication systems beyond the 5G system.

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

[0034] Wireless devices (100a to 100f) refer to devices that perform communication using radio access technology (RAT) (e.g., 5G NR or LTE) and may also be referred to as communication / wireless / 5G devices. Wireless devices (100a to 100f) may include, but are not limited to, robots (100a), vehicles (100b-1 and 100b-2), extended reality (XR) devices (100c), portable devices (100d), home appliances (100e), IoT devices (100f), and artificial intelligence (AI) devices / servers (400). For example, vehicles may include vehicles having wireless communication capabilities, autonomous vehicles, and vehicles capable of performing vehicle-to-vehicle communication. Vehicles may include unmanned aerial vehicles (UAVs) (e.g., drones). XR devices may include AR / VR / mixed reality (MR) devices, and may be implemented in the form of head-mounted devices (HMDs) and heads-up displays (HUDs) mounted on vehicles, televisions, smartphones, computers, wearable devices, home appliances, digital signs, vehicles, robots, etc. Portable devices may include smartphones, smart pads, wearable devices (e.g., smart watches or smart glasses), and computers (e.g., laptops). Home appliances may include TVs, refrigerators, and washing machines. IoT devices may include sensors and smart meters.

[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 personal digital assistant (PDA), a portable multimedia player (PMP), a navigation system, a slate PC, a tablet PC, an ultrabook, a vehicle, a vehicle with autonomous driving functions, a connected car, a UAV, an AI module, a robot, an AR device, a VR device, an MR device, a holographic device, a public safety device, an MTC device, an IoT device, a medical device, a fintech device (or a financial device), a security device, a weather / environmental device, a 5G service-related device, or a 4th industrial revolution-related device.

[0036] For example, a UAV may be an aircraft that is unmanned and navigated by radio control signals.

[0037] For example, a VR device may include a device for implementing objects or backgrounds in a virtual environment. For example, an AR device may include a device that implements objects or backgrounds in a virtual world by connecting them to objects or backgrounds in the real world. For example, an MR device may include a device that implements objects or backgrounds in a virtual world by merging them with objects or backgrounds in the real world. For example, a holographic device may include a device that implements 360-degree stereoscopic images by recording and reproducing three-dimensional information using the light interference phenomenon that occurs when two laser lights, called holograms, meet.

[0038] For example, a public safety device may include an image relay device or imaging device that can be worn on the user's body.

[0039] For example, MTC devices and IoT devices may be devices that do not require direct human intervention or manipulation. Examples include smart meters, vending machines, thermometers, smart light bulbs, door locks, or various sensors.

[0040] For example, a medical device may be a device used for the purpose of diagnosing, treating, alleviating, curing, or preventing a disease. For example, a medical device may be a device used for diagnosing, treating, alleviating, or correcting an injury or damage. For example, a medical device may be a device used for the purpose of examining, replacing, or modifying a structure or function. For example, a medical device may be a device used for the purpose of regulating pregnancy. For example, a medical device may include a therapeutic device, a driving device, an (in vitro) diagnostic device, a hearing aid, or a surgical device.

[0041] For example, a security device may be a device installed to prevent potential hazards and maintain safety. For example, a security device may be a camera, closed-circuit television (CCTV), a recorder, or a black box.

[0042] For example, a fintech device may be a device capable of providing financial services, such as mobile payments. For example, a fintech device may include a payment device or a point-of-sale system.

[0043] For example, a weather / environment device may include a device that monitors or predicts the weather / environment.

[0044] Wireless devices (100a to 100f) can be connected to a network (300) via a base station (200). AI technology can be applied to the wireless devices (100a to 100f), and the wireless devices (100a to 100f) can be connected to an AI server (400) via the network (300). The network (300) can be configured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR) network, and a network after 5G. The wireless devices (100a to 100f) can communicate with each other via the base station (200) / network (300), but can also communicate directly (e.g., sidelink communication) without going through the base station (200) / network (300). For example, vehicles (100b-1, 100b-2) can communicate directly (e.g., vehicle-to-vehicle (V2V) / vehicle-to-everything (V2X) communication). Additionally, IoT devices (e.g., sensors) can communicate directly with other IoT devices (e.g., sensors) or other wireless devices (100a to 100f).

[0045] Wireless communication / connection (150a, 150b, 150c) can be established between wireless devices (100a to 100f) and / or between wireless devices (100a to 100f) and a base station (200) and / or between base stations (200). Here, the wireless communication / connection can be established through various RATs (e.g., 5G NR), such as uplink / downlink communication (150a), sidelink communication (150b) (or, device-to-device (D2D) communication), and base station-to-base station communication (150c) (e.g., relay, integrated access and backhaul (IAB)). Through the wireless communication / connection (150a, 150b, 150c), the wireless devices (100a to 100f) and the base station (200) can transmit / receive wireless signals to / from each other. For example, wireless communication / connection (150a, 150b, 150c) can transmit / receive signals through various physical channels. To this end, at least some of the various configuration information setting processes for transmitting / receiving wireless signals, various signal processing processes (e.g., channel encoding / decoding, modulation / demodulation, resource mapping / demapping, etc.), and resource allocation processes can be performed based on various proposals of the present specification.

[0046] AI is the study of artificial intelligence or the methodologies for creating it, while machine learning (ML) defines various problems in the field of AI and studies the methodologies for solving them. Machine learning is also defined as an algorithm that improves performance on a task through consistent experience.

[0047] A robot can be defined as a machine that automatically processes or operates a given task based on its own capabilities. Specifically, a robot capable of perceiving its environment, making decisions, and performing actions on its own can be called an intelligent robot. Robots can be categorized into industrial, medical, household, and military applications based on their intended use or field. Robots are equipped with a drive unit, including an actuator or motor, enabling them to perform various physical actions, such as moving robot joints. Furthermore, mobile robots include wheels, brakes, and propellers in their drive unit, enabling them to drive on the ground or fly in the air.

[0048] Autonomous driving refers to the technology of driving on one's own, while autonomous vehicles refer to vehicles that drive without, or with minimal, user intervention. For example, autonomous driving can include technologies such as lane keeping, automatic speed control like adaptive cruise control, autonomous driving along a set route, and autonomous driving based on a set destination. Vehicles encompass all types of vehicles: those with internal combustion engines, hybrid vehicles with both internal combustion engines and electric motors, and electric vehicles with only electric motors. These vehicles can include not only cars but also trains and motorcycles. Autonomous vehicles can be viewed as robots with autonomous driving capabilities.

[0049] Extended reality is a general term for VR, AR, and MR. VR technology provides real-world objects and backgrounds as CG images only, AR technology provides virtual CG images over images of real objects, and MR technology is a CG technology that mixes and combines virtual objects with the real world. MR technology is similar to AR in that it displays real and virtual objects together. However, there is a difference: while AR uses virtual objects to complement real objects, MR uses virtual and real objects equally.

[0050] NR supports multiple numerologies, or subcarrier spacing (SCS), to support diverse 5G services. For example, an SCS of 15 kHz supports wide areas in traditional cellular bands; an SCS of 30 kHz / 60 kHz supports dense urban areas, lower latency, and wider carrier bandwidth; and an SCS of 60 kHz or higher supports bandwidths greater than 24.25 GHz to overcome phase noise.

[0051] The NR frequency band can be defined by two types of frequency ranges (FR1 and FR2). The numerical values ​​of the frequency ranges can be changed. For example, the two types of frequency ranges (FR1 and FR2) can be as shown in Table 1 below. For convenience of explanation, among the frequency ranges used in NR systems, FR1 can mean the "sub-6GHz range," and FR2 can mean the "above 6GHz range," which can be referred to as millimeter wave (mmW).

[0052] Frequency Range DefinitionFrequency RangeSubcarrier SpacingFR1450MHz - 6000MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0053] As described above, the numerical value of the frequency range of the NR system can be changed. For example, FR1 may include a band from 410 MHz to 7125 MHz, as shown in Table 2 below. That is, FR1 may include frequency bands above 6 GHz (or 5850, 5900, 5925 MHz, etc.). For example, the frequency bands above 6 GHz (or 5850, 5900, 5925 MHz, etc.) included within FR1 may include unlicensed bands. Unlicensed bands may be used for various purposes, such as for communications for vehicles (e.g., autonomous driving).

[0054] Frequency Range DefinitionFrequency RangeSubcarrier SpacingFR1410MHz - 7125MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0055] Here, the wireless communication technology implemented in the wireless device of the present specification may include not only LTE, NR, and 6G, but also narrowband IoT (NB-IoT) for low-power communication. For example, NB-IoT technology may be an example of LPWAN (low power wide area network) technology and may be implemented with standards such as LTE Cat NB1 and / or LTE Cat NB2, and is not limited to the above-described names. Additionally or alternatively, the wireless communication technology implemented in the wireless device of the present specification may perform communication based on LTE-M technology. For example, LTE-M technology may be an example of LPWAN technology and may be called by various names such as eMTC (enhanced MTC). For example, LTE-M technology can be implemented by at least one of various standards such as 1) LTE CAT 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-BL (non-bandwidth limited), 5) LTE-MTC, 6) LTE MTC, and / or 7) LTE M, and is not limited to the above-described names. Additionally or alternatively, the wireless communication technology implemented in the wireless device of the present specification can include at least one of ZigBee, Bluetooth, and / or LPWAN considering low-power communication, and is not limited to the above-described names. For example, ZigBee technology can create PAN (personal area networks) related to small / low-power digital communication based on various standards such as IEEE 802.15.4, and can be called by various names.

[0056] Figure 2 illustrates an example of a wireless device to which the implementation of the present specification is applied.

[0057] In FIG. 2, the first wireless device (100) and / or the second wireless device (200) may be implemented in various forms depending on the use case / service. For example, {the first wireless device (100) and the second wireless device (200)} may correspond to at least one of {the wireless devices (100a to 100f) and the base station (200)}, {the wireless devices (100a to 100f) and the wireless devices (100a to 100f)}, and / or {the base station (200) and the base station (200)} of FIG. 1. The first wireless device (100) and / or the second wireless device (200) may be configured by various components, devices / parts, and / or modules.

[0058] 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).

[0059] The processing chip (101) may include at least one processor, such as a processor (102), and at least one memory, such as a memory (104). Additionally and / or alternatively, the memory (104) may be located external to the processing chip (101).

[0060] The processor (102) may control the memory (104) and / or the transceiver (106) and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed herein. For example, the processor (102) may process information in the memory (104) to generate first information / signal and transmit a wireless signal including the first information / signal via the transceiver (106). The processor (102) may receive a wireless signal including second information / signal via the transceiver (106) and store information obtained by processing the second information / signal in the memory (104).

[0061] A memory (104) may be operatively connected to the processor (102). The memory (104) may store various types of information and / or instructions. The memory (104) may store firmware and / or software code (105) that implements code, instructions and / or sets of instructions that, when executed by the processor (102), perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed herein. For example, the firmware and / or software code (105) may implement instructions that, when executed by the processor (102), perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed herein. For example, the firmware and / or software code (105) may control the processor (102) to perform one or more protocols. For example, the firmware and / or software code (105) may control the processor (102) to perform one or more air interface protocol layers.

[0062] Here, the processor (102) and memory (104) may be part of a communication modem / circuit / chip designed to implement a RAT (e.g., LTE or NR). A transceiver (106) may be connected to the processor (102) and may transmit and / or receive wireless signals via one or more antennas (108). Each transceiver (106) may include a transmitter and / or a receiver. The transceiver (106) may be used interchangeably with an RF (radio frequency) unit. In the present specification, the first wireless device (100) may represent a communication modem / circuit / chip.

[0063] 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).

[0064] The processing chip (201) may include at least one processor, such as a processor (202), and at least one memory, such as a memory (204). Additionally and / or alternatively, the memory (204) may be located external to the processing chip (201).

[0065] The processor (202) may control the memory (204) and / or the transceiver (206) and may be configured to implement the descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed herein. For example, the processor (202) may process information in the memory (204) to generate third information / signal and transmit a wireless signal including the third information / signal via the transceiver (206). The processor (202) may receive a wireless signal including fourth information / signal via the transceiver (206) and store information obtained by processing the fourth information / signal in the memory (204).

[0066] A memory (204) may be operatively connected to the processor (202). The memory (204) may store various types of information and / or instructions. The memory (204) may store firmware and / or software code (205) that implements instruction codes, commands and / or sets of instructions that, when executed by the processor (202), perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed herein. For example, the firmware and / or software code (205) may implement instructions that, when executed by the processor (202), perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed herein. For example, the firmware and / or software code (205) may control the processor (202) to perform one or more protocols. For example, the firmware and / or software code (205) may control the processor (202) to perform one or more air interface protocol layers.

[0067] Here, the processor (202) and memory (204) may be part of a communication modem / circuit / chip designed to implement a RAT (e.g., LTE or NR). A transceiver (206) may be connected to the processor (202) and may transmit and / or receive wireless signals via one or more antennas (208). Each transceiver (206) may include a transmitter and / or a receiver. The transceiver (206) may be used interchangeably with the RF unit. In the present specification, the second wireless device (200) may represent a communication modem / circuit / chip.

[0068] Hereinafter, hardware elements of the wireless device (100, 200) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (102, 202). For example, one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as a physical (PHY) layer, a media access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, a radio resource control (RRC) layer, and a service data adaptation protocol (SDAP) layer). One or more processors (102, 202) may generate one or more protocol data units (PDUs), one or more service data units (SDUs), messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed herein. One or more processors (102, 202) can generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data or information according to the descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed herein and provide the signals to one or more transceivers (106, 206). One or more processors (102, 202) can receive signals (e.g., baseband signals) from one or more transceivers (106, 206) and obtain PDUs, SDUs, messages, control information, data or information according to the descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed herein.

[0069] The one or more processors (102, 202) may be referred to as a controller, a microcontroller, a microprocessor, and / or a microcomputer. The one or more processors (102, 202) may be implemented by hardware, firmware, software, and / or a combination thereof. For example, one or more application specific integrated circuits (ASICs), one or more digital signal processors (DSPs), one or more digital signal processing devices (DSPDs), one or more programmable logic devices (PLDs), and / or one or more field programmable gate arrays (FPGAs) may be included in the one or more processors (102, 202). For example, the one or more processors (102, 202) may be configured by a set of a communication control processor, an application processor (AP), an electronic control unit (ECU), a central processing unit (CPU), a graphic processing unit (GPU), and a memory control processor.

[0070] One or more memories (104, 204) may be coupled to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. The one or more memories (104, 204) may be configured as random access memory (RAM), dynamic RAM (DRAM), read-only memory (ROM), erasable programmable ROM (EPROM), flash memory, volatile memory, nonvolatile memory, hard drive, register, cache memory, computer-readable storage media, and / or combinations thereof. The one or more memories (104, 204) may be located internally and / or externally to the one or more processors (102, 202). Additionally, the one or more memories (104, 204) may be coupled to the one or more processors (102, 202) via various technologies, such as wired or wireless connections.

[0071] One or more transceivers (106, 206) can transmit user data, control information, wireless signals / channels, etc., referred to in the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed herein to one or more other devices. One or more transceivers (106, 206) can receive user data, control information, wireless signals / channels, etc., referred to in the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed herein from one or more other devices. For example, one or more transceivers (106, 206) can be coupled to one or more processors (102, 202) and can transmit and receive wireless signals. For example, one or more processors (102, 202) can control one or more transceivers (106, 206) to transmit user data, control information, wireless signals, etc., to one or more other devices. Additionally, one or more processors (102, 202) may control one or more transceivers (106, 206) to receive user data, control information, wireless signals, etc. from one or more other devices.

[0072] One or more transceivers (106, 206) may be coupled to one or more antennas (108, 208). Additionally and / or alternatively, one or more transceivers (106, 206) may include one or more antennas (108, 208). One or more transceivers (106, 206) may be configured to transmit and receive user data, control information, wireless signals / channels, etc., as described in the descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed herein via one or more antennas (108, 208). In the present specification, one or more antennas (108, 208) may be multiple physical antennas or multiple logical antennas (e.g., antenna ports).

[0073] One or more transceivers (106, 206) may convert received user data, control information, wireless signals / channels, etc. from RF band signals to baseband signals in order to process the received user data, control information, wireless signals / channels, etc. using one or more processors (102, 202). One or more transceivers (106, 206) may convert processed user data, control information, wireless signals / channels, etc. from baseband signals to RF band signals using one or more processors (102, 202). For this purpose, one or more transceivers (106, 206) may include an (analog) oscillator and / or a filter. For example, one or more transceivers (106, 206) may up-convert an OFDM baseband signal to an OFDM signal via an (analog) oscillator and / or filter under the control of one or more processors (102, 202) and transmit the up-converted OFDM signal at a carrier frequency. One or more transceivers (106, 206) may receive an OFDM signal at a carrier frequency and down-convert the OFDM signal to an OFDM baseband signal via an (analog) oscillator and / or filter under the control of one or more processors (102, 202).

[0074] Although not illustrated in FIG. 2, the wireless device (100, 200) may further include additional components. The additional components (140) may be configured in various ways depending on the type of the wireless device (100, 200). For example, the additional components (140) may include at least one of a power unit / battery, an input / output (I / O) device (e.g., an audio I / O port, a video I / O port), a driving device, and a computing device. The additional components (140) may be connected to one or more processors (102, 202) via various technologies, such as a wired or wireless connection.

[0075] In the implementation of the present specification, a UE can operate as a transmitter in the uplink (UL) and as a receiver in the downlink (DL). In the implementation of the present specification, a base station can operate as a receiver in the UL and as a transmitter in the DL. For the sake of convenience of description, it is mainly assumed below that the first wireless device (100) operates as a UE and the second wireless device (200) operates as a base station. For example, a processor (102) connected to, mounted on, or released in the first wireless device (100) can be configured to perform UE operations according to the implementation of the present specification or to control a transceiver (106) to perform UE operations according to the implementation of the present specification. A processor (202) connected to, mounted on, or released in the second wireless device (200) can be configured to perform base station operations according to the implementation of the present specification or to control a transceiver (206) to perform base station operations according to the implementation of the present specification.

[0076] In this specification, a base station may be referred to as a Node B, an eNode B (eNB), or a gNB.

[0077] Figure 3 shows an example of a UE to which the implementation of this specification is applied.

[0078] Referring to FIG. 3, the UE (100) can correspond to the first wireless device (100) of FIG. 2.

[0079] The UE (100) includes a processor (102), memory (104), a transceiver (106), one or more antennas (108), a power management module (141), a battery (142), a display (143), a keypad (144), a SIM (Subscriber Identification Module) card (145), a speaker (146), and a microphone (147).

[0080] The processor (102) may be configured to implement the descriptions, functions, procedures, proposals, methods and / or flowcharts disclosed herein. The processor (102) may be configured to control one or more other components of the UE (100) to implement the descriptions, functions, procedures, proposals, methods and / or flowcharts disclosed herein. A layer of a radio interface protocol may be implemented in the processor (102). The processor (102) may include an ASIC, other chipsets, logic circuits and / or data processing devices. The processor (102) may be an application processor. The processor (102) may include at least one of a DSP, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), and a modem (modulator and demodulator). An example of the processor (102) is the SNAPDRAGON manufactured by Qualcomm®. TM Series processors, EXYNOS made by Samsung® TM Series processors, A-series processors made by Apple®, HELIO made by MediaTek® TM ATOM series processors made by Intel® TM It can be found in the series processors or the corresponding next-generation processors.

[0081] Memory (104) is operatively coupled to the processor (102) and stores various information for operating the processor (102). Memory (104) may include ROM, RAM, flash memory, memory cards, storage media, and / or other storage devices. When the implementation is implemented in software, the techniques described herein may be implemented using modules (e.g., procedures, functions, etc.) that perform the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein. The modules may be stored in memory (104) and executed by the processor (102). Memory (104) may be implemented within the processor (102) or external to the processor (102), in which case it may be communicatively coupled to the processor (102) via various methods known in the art.

[0082] A transceiver (106) is operably coupled to the processor (102) and transmits and / or receives a radio signal. The transceiver (106) includes a transmitter and a receiver. The transceiver (106) may include a baseband circuit for processing a radio frequency signal. The transceiver (106) controls one or more antennas (108) to transmit and / or receive a radio signal.

[0083] 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).

[0084] The display (143) outputs the results processed by the processor (102). The keypad (144) receives input to be used by the processor (102). The keypad (144) can be displayed on the display (143).

[0085] A SIM card (145) is an integrated circuit that securely stores an International Mobile Subscriber Identity (IMSI) and associated keys, and is used to identify and authenticate subscribers in mobile devices such as mobile phones and computers. Additionally, many SIM cards can store contact information.

[0086] 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).

[0087] Figure 4 is a structural diagram of a next-generation mobile communications network.

[0088] 5GC (5G Core) may include various components, and in FIG. 5, some of them include AMF (Access and Mobility Management Function) (410), SMF (Session Management Function) (420), PCF (Policy Control Function) (430), UPF (User Plane Function) (440), AF (Application Function) (450), UDM (Unified Data Management) (460), and N3IWF (Non-3GPP (3rd Generation Partnership Project) Inter Working Function) (490).

[0089] The UE (100) is connected to a data network via UPF (440) through a Next Generation Radio Access Network (NG-RAN) including a gNB (20).

[0090] The UE (100) can also receive data services via untrusted non-3GPP access, such as a Wireless Local Area Network (WLAN). To connect the non-3GPP access to the core network, an N3IWF (490) may be deployed.

[0091] The illustrated N3IWF (490) performs the function of managing interworking between non-3GPP access and 5G system. When UE (100) is connected to non-3GPP access (e.g., WiFi, referred to as IEEE 801.11), UE (100) can be connected to 5G system through N3IWF (490). N3IWF (490) performs control signaling with AMF (410) and is connected to UPF (440) through N3 interface for data transmission.

[0092] The illustrated AMF (410) can manage access and mobility in a 5G system. The AMF (410) can perform functions to manage Non-Access Stratum (NAS) security. The AMF (410) can perform functions to handle mobility in the idle state.

[0093] The illustrated UPF (440) is a type of gateway through which user data is transmitted and received. The UPF node (440) can perform all or part of the user plane functions of the S-GW (Serving Gateway) and P-GW (Packet Data Network Gateway) of 4th generation mobile communications.

[0094] The UPF (440) acts as a boundary point between the next generation radio access network (NG-RAN) and the core network, and is an element that maintains a data path between the gNB (20) and the SMF (420). In addition, when the UE (100) moves across the area served by the gNB (20), the UPF (440) acts as a mobility anchor point. The UPF (440) can perform a function of handling PDUs. For mobility within the NG-RAN (Next Generation-Radio Access Network defined after 3GPP Release-15), the UPF can route packets. Additionally, the UPF (440) may also function as an anchor point for mobility with other 3GPP networks (RANs defined before 3GPP Release-15, e.g., UTRAN, E-UTRAN (Evolved-UMTS (Universal Mobile Telecommunications System) Terrestrial Radio Access Network)) or GERAN (GSM (Global System for Mobile Communication) / EDGE (Enhanced Data rates for Global Evolution) Radio Access Network). The UPF (440) may correspond to a termination point of a data interface toward a data network.

[0095] The illustrated PCF (430) is a node that controls the business operator's policy.

[0096] The illustrated AF (450) is a server for providing various services to the UE (100).

[0097] The illustrated UDM (460) is a type of server that manages subscriber information, such as the HSS (Home Subscriber Server) of 4th generation mobile communications. The UDM (460) stores and manages the subscriber information in a Unified Data Repository (UDR).

[0098] The illustrated SMF (420) can perform the function of allocating an IP (Internet Protocol) address of the UE. In addition, the SMF (420) can control a PDU (protocol data unit) session.

[0099] For reference, the drawing symbols for AMF (410), SMF (420), PCF (430), UPF (440), AF (450), UDM (460), N3IWF (490), gNB (20), or UE (100) may be omitted below.

[0100] 5G mobile communications support multiple numerologies, or subcarrier spacing (SCS), to support diverse 5G services. For example, a 15 kHz SCS supports wide areas in traditional cellular bands. A 30 kHz / 60 kHz SCS supports dense urban environments, lower latency, and wider carrier bandwidth. An SCS of 60 kHz or higher supports bandwidths greater than 24.25 GHz to overcome phase noise.

[0101] Figure 5 shows an example of a 5G system structure to which the implementation of this specification is applied.

[0102] The 5G system (5GS; 5G system) structure consists of the following network functions (NF; Network Function).

[0103] - AUSF (Authentication Server Function)

[0104] - AMF (Access and Mobility Management Function)

[0105] - DN (Data Network), 예를 들어 운영자 서비스, 인터넷 접속 또는 타사 서비스

[0106] - USDF (Unstructured Data Storage Function)

[0107] - NEF (Network Exposure Function)

[0108] - I-NEF (Intermediate NEF)

[0109] - NRF (Network Repository Function)

[0110] - NSSF (Network Slice Selection Function)

[0111] - PCF (Policy Control Function)

[0112] - SMF (Session Management Function)

[0113] - UDM (Unified Data Management)

[0114] - UDR (Unified Data Repository)

[0115] - UPF (User Plane Function)

[0116] - UCMF (UE radio Capability Management Function)

[0117] - AF (Application Function)

[0118] - UE (User Equipment)

[0119] - (R)AN ((Radio) Access Network)

[0120] - 5G-EIR (5G-Equipment Identity Register)

[0121] - NWDAF (Network Data Analytics Function)

[0122] - CHF (CHarging Function)

[0123] Additionally, the following network features may be considered:

[0124] - N3IWF (Non-3GPP InterWorking Function)

[0125] - TNGF (Trusted Non-3GPP Gateway Function)

[0126] - W-AGF (Wireline Access Gateway Function)

[0127] Figure 5 illustrates the 5G system architecture for a non-roaming case using a reference point representation showing how various network functions interact with each other.

[0128] For clarity of the point-to-point diagram in Figure 5, UDSF, NEF, and NRF are not illustrated. However, all network functions shown can interact with UDSF, UDR, NEF, and NRF as needed.

[0129] 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.

[0130] The 5G system architecture includes the following benchmarks:

[0131] - N1: Reference point between UE and AMF.

[0132] - N2: Reference point between (R)AN and AMF.

[0133] - N3: Reference point between (R)AN and UPF.

[0134] - N4: Reference point between SMF and UPF.

[0135] - N6: Reference point between UPF and data network.

[0136] - N9: Reference point between two UPFs.

[0137] The following benchmarks illustrate the interactions that exist between NF services in NF.

[0138] - N5: Reference point between PCF and AF.

[0139] - N7: Reference point between SMF and PCF.

[0140] - N8: Reference point between UDM and AMF.

[0141] - N10: Reference point between UDM and SMF.

[0142] - N11: Reference point between AMF and SMF.

[0143] - N12: Reference point between AMF and AUSF.

[0144] - N13: Reference point between UDM and AUSF.

[0145] - N14: Reference point between two AMFs.

[0146] - N15: Reference point between PCF and AMF for non-roaming scenarios, and reference point between PCF and AMF of visited network for roaming scenarios.

[0147] - N16: Reference point between two SMFs (in case of roaming, between the SMF of the visited network and the SMF of the home network)

[0148] - N22: Reference point between AMF and NSSF.

[0149] In some cases, two NFs may need to be interconnected to serve a UE.

[0150] Figure 6 shows an example of the overall architecture of NG-RAN.

[0151] Referring to FIG. 6, a gNB may be composed of a gNB-CU (central unit) and one or more gNB-DUs (distributed units). The gNB-CU is a logical node that hosts the radio resource control (RRC), service data adaptation protocol (SDAP), and packet data convergence protocol (PDCP) protocols of the gNB, or the RRC and PDCP protocols of the en-gNB. The gNB-CU controls the operation of one or more gNB-DUs. The gNB-DU is a logical node that hosts the radio link control (RLC), media access control (MAC), and physical layers of the gNB or en-gNB. The operation of the gNB-DU is partially controlled by the gNB-CU. A single gNB-DU supports one or more cells. A single cell is supported by only one gNB-DU.

[0152] A gNB-CU and a gNB-DU are connected via the F1 interface. The gNB-CU terminates the F1 interface connected to the gNB-DU. The gNB-DU terminates the F1 interface connected to the gNB-CU. A gNB-DU is connected to only one gNB-CU. However, with a suitable implementation, a gNB-DU can be connected to multiple gNB-CUs. The F1 interface is a logical interface. For NG-RAN, the NG and Xn-C interfaces for a gNB consisting of a gNB-CU and one or more gNB-DUs terminate at the gNB-CU. For EN-DC, the S1-U and X2-C interfaces for a gNB consisting of a gNB-CU and one or more gNB-DUs terminate at the gNB-CU. A gNB-CU and a gNB-DU connected to it appear only as a gNB to other gNBs and the 5GC.

[0153] Figure 7 shows logical nodes (CU-C, CU-U, and DU) within a logical gNB / en-gNB.

[0154] Figure 7 is one of the possible deployment scenarios of the NG-RAN illustrated in Figure 6. Protocol termination of the NG and Xn interfaces is indicated by ovals in Figure 7. The "central entity" and "distributed entity" in Figure 7 represent physical network nodes.

[0155] Figure 8 shows a deployment scenario of gNB.

[0156] Figure 8 illustrates an example of the architecture and possible deployment scenarios of the NG-RAN described in Figures 6 and 7.

[0157] Figure 8-(a) illustrates a collapsed gNB deployment scenario. In this deployment scenario, all RAN protocols and functions are co-located. This deployment scenario corresponds to those currently used in LTE. Because this deployment scenario is similar to the LTE architecture, it ensures maximum backward compatibility with existing LTE deployment scenarios.

[0158] Figure 8-(b) illustrates a disaggregated deployment scenario. In this deployment scenario, RAN protocol functions are distributed across different locations, such as the CU and the DU. The DU hosts the RLC, MAC, and physical layers. The CU-CP hosts the RRC and PDCP-C protocols. The CU-UP hosts the PDCP-U (and SDAP) protocols. The DU and CU-CP can be connected via the F1-C interface. The DU and CU-UP can be connected via the F1-U interface. The CU-CP and CU-UP can be connected via the E1 interface.

[0159] According to the decoupled deployment scenario described in Figure 8-(b), the locations of different RAN functions can be optimally deployed based on the scenario and desired performance. For example, the CU-CP can be deployed close to the DU. Alternatively, the CU-CP can be co-located with the DU. In this case, low latency can be provided for critical CP procedures such as connection (re)establishment, handover, and state transition. On the other hand, the CU-UP can be centrally deployed in a regional or national data center. Therefore, the CU-UP is advantageous for cloud implementations and can provide a centralized termination point for UP traffic in dual connectivity and tight interworking scenarios. Additionally, additional CU-UPs can be deployed close to (or co-located with) the DU to provide a local termination point for UP traffic for applications requiring very low latency, such as ultra-reliable low latency communications (URLLC) traffic.

[0160] <relay 관련 Path Switching>

[0161] In relation to communication via Relay, path switching has the following scenarios:

[0162] - Switching from indirect path to direct path (Inter-gNB indirect-to-direct path switching) (i.e., remote UE-relay UE A-gNB X to remote UE-gNB Y)

[0163] - Inter-gNB direct-to-indirect path switching (i.e., remote UE-gNB X to remote UE-relay UE A-gNB Y)

[0164] - Intra-gNB indirect-to-indirect path switching (i.e., remote UE-relay UE A-gNB X to remote UE-relay UE B-gNB X)

[0165] - Inter-gNB indirect-to-indirect path switching (i.e., remote UE-relay UE A-gNB X to remote UE-relay UE B-gNB Y)

[0166] In the past, service continuity could be provided in direct-to-indirect path switching or indirect-to-direct path switching in an intra-gNB situation.

[0167] Path switching and indirect-to-indirect path switching in inter-gNB situations are problematic.

[0168] In the case of an indirect path situation (i.e., a situation where the NG-RAN and the Remote UE exchange data via the Relay UE), the NG-RAN receives information from the RLC located in the Relay UE regarding whether the downlink (DL) data has been properly delivered. Alternatively, in the case of an indirect path situation, the Remote UE receives information from the RLC located in the Relay UE regarding whether the uplink (UL) data has been properly delivered.

[0169] Therefore, in an indirect path situation, the NG-RAN cannot know whether the corresponding data was successfully delivered through the PC5 link (for DL). Or, the Remote UE cannot know whether the corresponding data was successfully delivered through the Uu link (for UL).

[0170] That is, DL data transmitted from the NG-RAN may fail to be transmitted on the PC5 link, and the NG-RAN may not be aware of the failure. Alternatively, UL data transmitted from the Remote UE may fail to be transmitted on the Uu link, and the Remote UE may not be aware of the failure.

[0171] If the NG-RAN (or Remote UE) receives ACK information from the RLC located in the Relay UE, the NG-RAN (or Remote UE) can delete the DL (or UL) data packet. In this case, if the DL (or UL) packet fails to be transmitted on the PC5 (or Uu) link, the NG-RAN (or Remote UE) cannot retransmit the packet to the Remote UE (or NG-RAN), which causes lossless delivery issues.

[0172] In cases where path switching occurs in an intra-gNB situation, UL / DL lossless delivery can be supported without separate standard support.

[0173] Proactive data forwarding has been proposed to support DL lossless delivery in inter-gNB situations (i.e., when the base station changes).

[0174] Proactive data forwarding refers to a method in which a source base station (Source NG-RAN) continuously buffers DL data packets successfully transmitted to a relay UE without deleting them, and then forwards the buffered DL data to the target base station (Target NG-RAN) during a handover process with a remote UE. This method can be applied when the base station (gNB) is not divided into CU-CP, CU-UP, and DU.

[0175] When the base station (gNB) is divided into CU-CP, CU-UP, and DU, the CU-UP does not know whether the bearer currently created / allocated for the remote UE is transmitted through the relay UE, and thus can delete the corresponding DL data packet based only on the ACK information sent by the relay UE's RLC. This can lead to a problem where DL lossless delivery is not guaranteed when the base station is changed.

[0176] To address these issues, the CU-UP needs to be aware that the Remote UE is currently connected via a Relay UE. Furthermore, the CU-UP needs to support proactive data forwarding.

[0177] According to the implementation of this specification, the CU-CP can notify the CU-UP that the Remote UE is currently connected via the Relay UE. Based on this, the CU-UP can buffer, without deleting, DL data packets successfully transmitted by the DU to the Relay UE. If a handover is performed in the future where the base station is changed, the CU-UP can transmit the buffered data packets to the target base station.

[0178] Then, even if the DL data packet fails to be transmitted on the PC5 link, the Remote UE can receive the packet from the target base station.

[0179] A method may be proposed for CU-CP to inform CU-UP that Remote UE has connected via Relay UE and proactive data forwarding is required.

[0180] Some of the service operations between core network functions (NFs) in the method proposed in this specification may be implemented by defining new service operations. Existing service operations may also be used for the operations in the method proposed in this specification.

[0181] In this specification, some new NG messages may be defined and used in the NG messages between the AMF and the NG-RAN. In addition, some new RRC messages may be defined and used in the RRC messages between the NG-RAN and the terminal in this specification.

[0182] Certain steps in this specification may be performed concurrently / in parallel, or may be performed in an out-of-order order.

[0183] The names of indications or parameter information in this specification are examples and may be interpreted as other names for the proposed procedure / purpose / method.

[0184] CU-CP may be a logical node constituting the base station that hosts the RRC (Radio Resource Control) protocol and the PDCP (Packet Data Convergence Protocol)-C protocol.

[0185] A CU-UP may be a logical node that constitutes a base station hosting a PDCP-U.

[0186] Figure 9 shows a flowchart according to an embodiment of the present specification.

[0187] During the Bearer Context Setup process for the Remote UE (or the Bearer Context Modification procedure or the Bearer Context Modification Request procedure), the CU-CP can send an indication to the CU-UP that the Remote UE has connected via the Relay UE. Based on this, the CU-UP can continue to buffer DL data that has been successfully transmitted to the Relay UE without deleting it.

[0188] Step 1. Steps 1 to 19 of the Remote UE Initial Access procedure of Clause 8.19.1 of TS 38.401 v17.5.0 may be performed.

[0189] Step 2. The CU-CP may request the CU-UP to create / allocate a bearer context for the Remote UE. At this time, the CU-CP may also transmit an indication to the CU-UP indicating that the Remote UE is connected via a Relay UE. The indication may be an indirect path indication indicating that the path to the Remote UE (the path between the Remote UE and the base station) is an indirect path.

[0190] The CU-CP can recognize that the connection between the Relay UE and the base station is for the Remote UE. In other words, the CU-CP can recognize that the path to the Remote UE is an indirect path. The CU-CP can transmit an indirect path indication to the CU-UP to inform them of this fact.

[0191] For DL ​​lossless delivery, even if the CU-UP receives a DDDS (Downlink Data Delivery Status) frame including a 'successfully delivered PDCP SN' from the DU, the CU-UP can continue to buffer DL data up to the corresponding PDCP SN without deleting it based on the aforementioned indication.

[0192] Instead of CU-CP sending an indication to CU-UP that Remote UE is connected via Relay UE, CU-CP sends N buffer The CU-UP can send information (or instructions) to buffer additional DL data packets. Then, the CU-UP can receive N from the 'successfully delivered PDCP SN' received from the DU. buffer DL data packets up to the PDCP SN excluding N are dropped, and subsequent DL data packets can continue to be buffered. That is, CU-UP is N buffer Additional DL data packets can be buffered.

[0193] Alternatively, instead of (or while transmitting) an indication to the CU-UP that the Remote UE is connected via the Relay UE, the CU-CP may additionally set a timer value for which the CU-UP should buffer DL data. Then, even if the CU-UP receives an indication from the DU that the corresponding PDCP PDU has been successfully transmitted to the Relay UE, the CU-CP may not discard the corresponding DL data, but may buffer it until the timer set by the CU-CP expires. The CU-UP may discard the corresponding DL data when the timer expires.

[0194] Alternatively, the CU-CP can explicitly inform the CU-UP that proactive data forwarding is required. In this case, the CU-UP may additionally buffer any number of DL data, depending on the CU-UP implementation, regardless of the 'successfully delivered PDCP SN' received from the DU.

[0195] In addition to the indication informing the CU-UP that the above Remote UE is connected via the Relay UE, the CU-CP may also transmit the above information to the CU-UP.

[0196] The action in Step 2 can be performed in a Bearer Context Modification procedure or a Bearer Context Modification Required procedure instead of a Bearer Context procedure.

[0197] Step 3. CU-UP can transmit the resource and bearer context information allocated for the above bearer to CU-CP.

[0198] Step 4. The remaining steps of the Remote UE Initial Access procedure in Clause 8.19.1 of TS 38.401 v17.5.0 can be performed.

[0199] Remote UE and NG-RAN can transmit and receive DL / UL data through Relay UE.

[0200] Step 5. If the DU successfully transmits DL data (DL data received from the CU-UP) to the Relay UE, the DU can notify the CU-UP of this fact through DDDS (downlink data delivery status).

[0201] DDDS may include 'Highest successfully delivered NR PDCP Sequence Number' and / or 'Number of successfully delivered out-of-sequence PDCP Sequence Number range'. 'Highest successfully delivered NR PDCP Sequence Number' may be the highest sequence number of successfully transmitted NR PDCP. 'Number of successfully delivered out-of-sequence PDCP Sequence Number range' may be the number of successfully transmitted PDCP sequence range.

[0202] The DU can transmit DL data for the Remote UE (DL data received from the CU-UP) to the Relay UE. When the Relay UE receives the data, the Relay UE can send an ACK to the DU. Based on the ACK, the DU can notify the CU-UP via DDDS that the DL data packet has been successfully transmitted to the Relay UE.

[0203] The aforementioned DDDS may be applied to the DL DATA DELIVERY STATUS (PDU Type 1) Format defined in TS 38.425 v17.3.0.

[0204] Table 3 shows an example of DDDS.

[0205]

[0206]

[0207] Regardless of whether the CU-CP informs the CU-UP in Step 2 that the Remote UE is connected via the Relay UE, the DU may inform the CU-UP via DDDS in Step 5 that data is being transmitted to the Remote UE via the Relay UE. Then, the CU-UP may continue to buffer DL data based on the information received from the DU in Step 5 even if it does not receive an indication from the CU-CP in Step 2.

[0208] Alternatively, depending on the DU implementation, the DU may set values ​​such as 'Highest successfully delivered NR PDCP Sequence Number' and / or 'Number of successfully delivered out of sequence PDCP Sequence Number range' to take proactive data forwarding into account when generating / determining the information to be included in the DDDS in Step 5.

[0209] For example, even if the DU successfully delivers DL data to the Relay UE, the DU may not include the PDCP SN information of the DL data in the 'Highest successfully delivered NR PDCP Sequence Number' and / or 'Number of successfully delivered out of sequence PDCP Sequence Number range' in the DDDS. In this case, the CU-UP may determine that the DL data corresponding to the PDCP SN has not yet been delivered to the Remote UE and may continue to buffer the DL data.

[0210] However, to ensure that the CU-UP can continuously transmit a certain amount of DL data to the DU, the DU may set values ​​such as 'Desired buffer size for the data radio bearer' and / or 'Desired Data Rate' in the DDDS of Step 5, taking proactive data forwarding into account. 'Desired buffer size for the data radio bearer' may be the desired buffer size for the data radio bearer. 'Desired Data Rate' may be the desired data rate.

[0211] Alternatively, the CU-CP may request the DU to perform actions that take proactive data forwarding into account (i.e., not including the PDCP SN information of the DL data in the 'Highest successfully delivered NR PDCP Sequence Number' and / or 'Number of successfully delivered out of sequence PDCP Sequence Number range' in the DDDS even though the DL data was successfully delivered to the Relay UE) through the UE Context Setup or UE Context Modification procedure.

[0212] Step 6. Even if the CU-UP receives the PDCP SN that was successfully transmitted to the Relay UE in Step 5 from the DU, the CU-UP may continue to buffer DL data for the corresponding PDCP SN without deleting it based on the indication received from the CU-CP in Step 2.

[0213] Step 7. Due to the movement of the Remote UE, the CU-CP of NG-RAN1 may decide to handover the Remote UE to NG-RAN2 (Xn-based handover or NG-based handover).

[0214] At this time, CU-CP of NG-RAN1 can also perform proactive data forwarding for DL ​​lossless delivery.

[0215] The CU-UP of NG-RAN1 can inform the CU-CP of NG-RAN1 of the PDCP SN information that has been successfully transmitted to the Relay UE so far. Then, the CU-CP of NG-RAN1 can forward the information to NG-RAN2 via the SN STATUS TRANSFER message.

[0216] Additionally, the CU-UP of NG-RAN1 can forward buffered data to NG-RAN2. At this time, the CU-UP can also forward the DL data that was still being buffered to NG-RAN2 even though it was successfully transmitted to the Relay UE in Step 6.

[0217] NG-RAN2 can receive a 'PDCP Status Report' from the Remote UE. Based on this, NG-RAN2 can additionally transmit to the Remote UE any DL data that requires retransmission among the DL data received from NG-RAN1.

[0218] According to the disclosure of this specification, the CU-UP of NG-RAN1 can buffer DL data that the DU successfully transmitted to the Relay UE without deleting it. Later, when the Remote UE is handed over to NG-RAN2, the CU-UP of NG-RAN1 can additionally transfer the buffered DL data to NG-RAN2. NG-RAN2 can additionally transfer to the Remote UE DL data that requires retransmission based on the 'PDCP Status Report' sent by the Remote UE among the DL data received from NG-RAN1. Through this method, the situation where some DL data is lost from the perspective of the Remote UE can be avoided.

[0219] The above drawings may be executed individually or together with other drawings.

[0220] The following actions can be performed:

[0221] - CU-CP can notify CU-UP that Remote UE has connected through Relay UE during Bearer Context Setup or Bearer Context Modification process for Remote UE.

[0222] - CU-UP can continue to buffer DL data that has been successfully transmitted to the Relay UE without deleting it based on the information received from CU-CP and DU.

[0223] - CU-UP can continuously transfer DL data that has been buffered to the Target NG-RAN in a handover situation for the Remote UE.

[0224] The following drawings are intended to illustrate specific examples of the present specification. The names of specific devices and the names of specific signals / messages / fields depicted in the drawings are provided for illustrative purposes only, and the technical features of this specification are not limited to the specific names used in the drawings.

[0225] Figure 10 illustrates the CU-UP procedure for the disclosure of this specification.

[0226] 1. CU-UP can receive a bearer context related request message from the CU-CP (CU-Control Plane) of the source base station.

[0227] The above request message may include an indirect path indication.

[0228] The above indirect path indication may indicate that the path between the Remote UE (User Equipment) and the source base station is an indirect path.

[0229] 2. Based on the above request message, CU-UP can send a response message to the CU-CP.

[0230] 3. CU-UP can transmit downlink data to the Remote UE.

[0231] 4. The CU-UP can receive a transmission status message from the DU (Distributed Unit) of the source base station notifying that the downlink data has been successfully transmitted to the Relay UE for the Remote UE.

[0232] Based on the above indirect path indication, the CU-UP can skip discarding the downlink data by the transmission status message.

[0233] 5. CU-UP can buffer the downlink data based on the above indirect path indication.

[0234] 6. Based on the Remote UE handing over from the source base station to the target base station, the CU-UP can transmit the buffered downlink data to the target base station.

[0235] The above request message may be a bearer context setup request or a bearer context modification request.

[0236] The above request message may include a timer.

[0237] CU-UP can drive the above timer.

[0238] The above buffering step can be performed until the timer expires.

[0239] Based on the expiration of the above timer, the CU-UP may discard the downlink data.

[0240] The above response message may include allocated resource and bearer context information.

[0241] The above transmission status message can be transmitted via a DDDS (downlink data delivery status) frame.

[0242] The above downlink data can be transmitted to the DU and the Relay UE.

[0243] CU-CP may be a logical node constituting the base station that hosts the RRC (Radio Resource Control) protocol and the PDCP (Packet Data Convergence Protocol)-C protocol.

[0244] A CU-UP may be a logical node that constitutes a base station hosting a PDCP-U.

[0245] The following drawings are intended to illustrate specific examples of the present specification. The names of specific devices and the names of specific signals / messages / fields depicted in the drawings are provided for illustrative purposes only, and the technical features of this specification are not limited to the specific names used in the drawings.

[0246] Figure 11 illustrates the CU-CP procedure for the disclosure of this specification.

[0247] 1. The CU-CP can send a bearer context related request message to the CU-UP (CU-User Plane) of the source base station.

[0248] 2. Based on the above request message, the CU-CP may include a step of transmitting a response message to the CU-CP.

[0249] The above request message may include an indirect path indication.

[0250] The above indirect path indication may indicate that the path between the Remote UE (User Equipment) and the source base station is an indirect path.

[0251] The above request message may include a timer.

[0252] The above timer may include time information for which the CU-UP buffers downlink data.

[0253] The above response message may include allocated resource and bearer context information.

[0254] CU-CP may be a logical node constituting the base station that hosts the RRC (Radio Resource Control) protocol and the PDCP (Packet Data Convergence Protocol)-C protocol.

[0255] A CU-UP may be a logical node that constitutes a base station hosting a PDCP-U.

[0256] Hereinafter, a device for performing communication according to some embodiments of the present specification will be described.

[0257] For example, a device may include a processor, a transceiver, and memory.

[0258] For example, a processor may be configured to be operatively coupled with memory and a processor.

[0259] The operations performed by the processor may include: receiving a bearer context related request message from a CU-CP of the source base station; the request message including an indirect path indication, the indirect path indication indicating that a path between a Remote UE and the source base station is an indirect path, and transmitting a response message to the CU-CP based on the request message; transmitting downlink data to the Remote UE; receiving a transmission status message from a DU of the source base station indicating that the downlink data has been successfully transmitted to a Relay UE for the Remote UE; skipping, based on the indirect path indication, the CU-UP discarding the downlink data by the transmission status message and buffering the downlink data based on the indirect path indication; and transmitting, based on the Remote UE's handover from the source base station to the target base station, the buffered downlink data to the target base station.

[0260] Below, a processor of a device for providing communication according to some embodiments of the present specification is described.

[0261] The operations performed by the processor may include: receiving a bearer context related request message from a CU-CP of the source base station; the request message including an indirect path indication, the indirect path indication indicating that a path between a Remote UE and the source base station is an indirect path, and transmitting a response message to the CU-CP based on the request message; transmitting downlink data to the Remote UE; receiving a transmission status message from a DU of the source base station indicating that the downlink data has been successfully transmitted to a Relay UE for the Remote UE; skipping, based on the indirect path indication, the CU-UP discarding the downlink data by the transmission status message and buffering the downlink data based on the indirect path indication; and transmitting, based on the Remote UE's handover from the source base station to the target base station, the buffered downlink data to the target base station.

[0262] Hereinafter, a non-volatile computer-readable medium storing one or more commands for providing mobile communication according to some embodiments of the present specification is described.

[0263] According to some embodiments of the present disclosure, the technical features of the present disclosure may be implemented directly in hardware, software executed by a processor, or a combination of the two. For example, a method performed by a wireless device in wireless communication may be implemented in hardware, software, firmware, or any combination thereof. For example, the software may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or other storage media.

[0264] Some examples of storage media are coupled to the processor, allowing the processor to read information from the storage media. Alternatively, the storage media may be integrated into the processor. The processor and storage media may reside in an ASIC. In other examples, the processor and storage media may reside as separate components.

[0265] Computer-readable media may include tangible and non-volatile computer-readable storage media.

[0266] For example, nonvolatile computer-readable media may include random access memory (RAM), such as synchronized dynamic random access memory (SDRAM), read-only memory (ROM), non-volatile random access memory (NVRAM), read-only memory (EEPROM), flash memory, magnetic or optical data storage media, or any other media that can be used to store instructions or data structures. Nonvolatile computer-readable media may also include combinations of the above.

[0267] Additionally, the methods described herein can be realized at least in part by a computer-readable communication medium that carries or transmits code in the form of instructions or data structures and that can be accessed, read, and / or executed by a computer.

[0268] According to some embodiments of the present disclosure, a non-transitory computer-readable medium has one or more instructions stored thereon. The one or more stored instructions can be executed by a processor of a base station.

[0269] The stored one or more commands may include: receiving a bearer context related request message from a CU-CP of the source base station; the request message including an indirect path indication, the indirect path indication indicating that a path between a Remote UE and the source base station is an indirect path; and transmitting a response message to the CU-CP based on the request message; transmitting downlink data to the Remote UE; receiving a transmission status message from a DU of the source base station indicating that the downlink data has been successfully transmitted to a Relay UE for the Remote UE; skipping, based on the indirect path indication, the CU-UP discarding the downlink data by the transmission status message and buffering the downlink data based on the indirect path indication; and transmitting, based on the Remote UE's handover from the source base station to the target base station, the buffered downlink data to the target base station.

[0270] This specification may have various effects.

[0271] For example, through the procedure disclosed in this specification, the Remote UE can receive data without loss during the handover process.

[0272] The effects that can be achieved through specific examples of this specification are not limited to the effects listed above. For example, a person with ordinary skill in the relevant technical field may understand or derive various technical effects from this specification. Accordingly, the specific effects of this specification are not limited to those explicitly described herein, but may include various effects that can be understood or derived from the technical features of this specification.

[0273] The claims set forth in this specification may be combined in various ways. For example, the technical features of the method claims of this specification may be combined to implement a device, and the technical features of the device claims of this specification may be combined to implement a method. Furthermore, the technical features of the method claims and the technical features of the device claims of this specification may be combined to implement a device, and the technical features of the method claims and the technical features of the device claims of this specification may be combined to implement a method. Other implementations are within the scope of the claims.

Claims

1. A method in which the CU-UP (Central Unit-User Plane) of the source base station performs communication, A step of receiving a bearer context related request message from a CU-CP (CU-Control Plane) of the source base station; The above request message includes an indirect path indication, The above indirect path indication indicates that the path between the Remote UE (User Equipment) and the source base station is an indirect path, A step of transmitting a response message to the CU-CP based on the request message; A step of transmitting downlink data to the Remote UE; A step of receiving a transmission status message from a DU (Distributed Unit) of the source base station notifying that the downlink data has been successfully transmitted to a Relay UE for the Remote UE; Based on the above indirect path indication, the CU-UP skips discarding the downlink data by the transmission status message, A step of buffering the downlink data based on the indirect path indication; A method comprising the step of transmitting the buffered downlink data to the target base station based on the handover of the Remote UE from the source base station to the target base station.

2. In paragraph 1, The above request message is a bearer context setup request or a bearer context modification request.

3. In paragraph 1 or 2, The above request message includes a timer, Step of driving the above timer; The above buffering step is performed until the timer expires, A method further comprising the step of discarding the downlink data based on the expiration of the timer.

4. In any one of the clauses 1 to 3, The above response message includes allocated resource and bearer context information.

5. In any one of paragraphs 1 to 4, The above transmission status message is transmitted through a DDDS (downlink data delivery status) frame.

6. In any one of paragraphs 1 to 5, A method in which the above downlink data is transmitted to the DU and the Relay UE.

7. In any one of paragraphs 1 to 6, The above CU-CP is a logical node that constitutes the base station that hosts the RRC (Radio Resource Control) protocol and the PDCP (Packet Data Convergence Protocol)-C protocol, The above CU-UP is a logical node that constitutes a base station hosting PDCP-U.

8. A method in which the CU-CP (Central Unit-Control Plane) of the source base station performs communication, A step of transmitting a bearer context related request message to the CU-UP (CU-User Plane) of the above source base station; A step of transmitting a response message to the CU-CP based on the request message, The above request message includes an indirect path indication, The above indirect path indication is a method of indicating that the path between a remote UE (User Equipment) and the source base station is an indirect path.

9. In paragraph 8, The above request message includes a timer, A method in which the above timer includes time information for the CU-UP to buffer downlink data.

10. In paragraph 8 or 9, The above response message includes allocated resource and bearer context information.

11. In any one of the clauses 8 to 10, The above CU-CP is a logical node that constitutes the base station that hosts the RRC (Radio Resource Control) protocol and the PDCP (Packet Data Convergence Protocol)-C protocol, The above CU-UP is a logical node that constitutes a base station hosting PDCP-U.

12. As a CU-UP (Central Unit-User Plane) of the source base station performing communication, Transmitter and receiver; Contains a processor, The operation performed by the above processor is a CU-UP method according to any one of claims 1 to 7.

13. As a CU-CP of a source base station performing communication, Transmitter and receiver; Contains a processor, The operation performed by the above processor is a CU-CP method according to any one of claims 8 to 11.

14. As an apparatus in mobile communication, at least one processor; and At least one memory storing instructions and being operably electrically connected to the at least one processor, A device wherein the operation performed based on the command being executed by the at least one processor is a method according to any one of claims 1 to 7.

15. A non-volatile computer-readable storage medium that records commands, A non-volatile computer-readable storage medium, wherein the instructions, when executed by one or more processors, cause the one or more processors to perform a method according to any one of claims 1 to 7.

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