Lossless data communication method

Abstract

One disclosure of the present disclosure provides a method in 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, the request message comprising an indirect path indication, and the indirect path indication indicating that a path between a remote UE and the source base station is an indirect path; sending a response message to the CU-CP based on the request message; transmitting downlink data to the remote UE; receiving, from the DU of the source base station, a transmission status message indicating that downlink data has been successfully transmitted to a relay UE for a remote UE; the CU-UP skips dropping of downlink data due to a transmission state message based on the indirect path indication, and buffers the downlink data based on the indirect path indication; and transmitting the cached downlink data to the target base station based on a handover of the remote UE from the source base station to the target base station.

Description

Technical Field

[0001] This manual relates to mobile communications. Background Technology

[0002] The 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is a technology designed to enable high-speed packet communication. Numerous proposals have been put forward for LTE objectives, including those aimed at reducing costs for users and providers, improving quality of service, and expanding and improving coverage and system capacity. As upper-layer requirements, 3GPP LTE needs to reduce cost per bit, increase service availability, allow flexible use of frequency bands, have a simple architecture, open interfaces, and sufficient power consumption for terminals.

[0003] Requirements and specifications for New Radio (NR) systems have begun to be developed within the International Telecommunication Union (ITU) and 3GPP. 3GPP must identify and develop technical components that will be successfully standardized in the new RAT to meet both pressing market demands and the longer-term requirements outlined in the ITU Radiocommunication Sector (ITU-R) International Mobile Telecommunications (IMT)-2020 process. Furthermore, NR should be able to utilize any spectrum band within at least 100 GHz that can be used for wireless communication even in the more distant future.

[0004] The goal of NR is to address all use cases, requirements, and deployment scenarios with a single technology framework, including enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), ultra-reliable and low-latency communications (URLLC), and more. NR should be inherently backward compatible.

[0005] When a remote UE is switched, a method is needed to send downlink data to the remote UE without loss. Summary of the Invention

[0006] Technical solution

[0007] The CU-CP sends an indirect path indication to the CU-UP, and the CU-UP buffers the downlink data based on this and sends it to the target base station. Attached Figure Description

[0008] Figure 1 An example of a communication system that applies the implementation of this disclosure is shown.

[0009] Figure 2 An example of a wireless device that applies the implementation of this disclosure is shown.

[0010] Figure 3 An example of a UE that applies the implementation of this disclosure is shown.

[0011] Figure 4 This is a block diagram of the next-generation cellular network.

[0012] Figure 5 An example 5G system architecture is illustrated, showing an implementation method that can be applied to this specification.

[0013] Figure 6 An example of the overall architecture of NG-RAN is shown.

[0014] Figure 7 The logical nodes (CU-C, CU-U, and DU) within the logical gNB / en-gNB are illustrated.

[0015] Figure 8 This illustrates a deployment scenario for gNB.

[0016] Figure 9 A flowchart illustrating an embodiment according to the present disclosure is provided.

[0017] Figure 10 The CU-UP process disclosed in this specification is illustrated.

[0018] Figure 11 The CU-CP process disclosed in this specification is illustrated. Detailed Implementation

[0019] The following technologies, devices, and systems can be applied to a variety of 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 can be implemented using radio technologies such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can be implemented using radio technologies such as Global System for Mobile Communications (GSM), Universal Packet Radio Service (GPRS), or Enhanced Data Rate Evolution of GSM (EDGE). OFDMA can be implemented using radio technologies such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, or Evolved UTRA (E-UTRA). UTRA is part of the Universal Mobile Telecommunications System (UMTS). The 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is part of the Evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE employs OFDMA in DL and SC-FDMA in UL. The evolution of 3GPP LTE includes LTE-A (Advanced), LTE-A Pro, and / or 5G NR (New Radio).

[0020] For ease of description, the implementation of this disclosure is primarily described with respect to 3GPP-based wireless communication systems. However, the technical features of this disclosure are not limited thereto. For example, although the following detailed description is given of mobile communication systems corresponding to 3GPP-based wireless communication systems, the aspects of this disclosure, which are not limited to 3GPP-based wireless communication systems, are applicable to other mobile communication systems.

[0021] For any terms and techniques used in this disclosure that are not specifically described in this disclosure, please refer to previously published wireless communication standards documents.

[0022] In this disclosure, "A or B" may mean "A only", "B only", or "both A and B". In other words, "A or B" in this disclosure may be interpreted as "A and / or B". For example, "A, B or C" in this disclosure may mean "A only", "B only", "C only", or "any combination of A, B and C".

[0023] In this disclosure, a forward slash ( / ) or a comma (,) can mean "and / or". For example, "A / B" can mean "A and / or B". Therefore, "A / B" can mean "A only", "B only", or "both A and B". For example, "A, B, C" can mean "A, B, or C".

[0024] In this disclosure, "at least one of A and B" may mean "only A", "only B" or "both A and B". Furthermore, the expressions "at least one of A or B" or "at least one of A and / or B" in this disclosure may be interpreted as the same as "at least one of A and B".

[0025] Additionally, in the disclosure, "at least one of A, B, and C" may mean "A only", "B only", "C only" 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".

[0026] Furthermore, the brackets used in this disclosure may mean "for example". Specifically, when shown as "Control Information (PDCCH)", "PDCCH" can be cited as an example of "Control Information". In other words, "Control Information" in this disclosure is not limited to "PDCCH", and "PDCCH" can be cited as an example of "Control Information". Additionally, even when shown as "Control Information (i.e., PDCCH)", "PDCCH" can be cited as an example of "Control Information".

[0027] The technical features described individually in one of the accompanying drawings of this disclosure may be implemented individually or simultaneously.

[0028] Not limited thereto, the various descriptions, functions, processes, suggestions, methods and / or operation flowcharts disclosed herein can be applied to various fields requiring wireless communication and / or connectivity between devices (e.g., 5G).

[0029] In the following description, this disclosure will be described in more detail with reference to the accompanying drawings. Unless otherwise indicated, the same reference numerals in the following drawings and / or description may denote the same and / or corresponding hardware blocks, software blocks and / or functional blocks.

[0030] Figure 1 An example of a communication system that applies the implementation of this disclosure is shown.

[0031] Figure 1 The 5G use cases shown are merely illustrative, and the technical features of this disclosure can be applied to... Figure 1 Other 5G use cases not shown.

[0032] The three main requirement categories for 5G include (1) Enhanced Mobile Broadband (eMBB), (2) Massive Machine-Type Communications (mMTC), and (3) Ultra-Reliable and Low-Latency Communications (URLLC).

[0033] Reference Figure 1 The communication system 1 includes wireless devices 100a to 100f, a base station (BS) 200, and a network 300. Although Figure 1 An example of a 5G network as a network of communication system 1 is shown, but the implementation of this disclosure is not limited to 5G systems and can be applied to future communication systems other than 5G systems.

[0034] BS 200 and network 300 can be implemented as wireless devices, and a particular wireless device can operate as a BS / network node relative to other wireless devices.

[0035] Wireless devices 100a to 100f represent devices that perform communication using radio access technology (RAT) (e.g., 5G New RAT (NR) or LTE) and may be referred to as communication / radio / 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, handheld devices 100d, home appliances 100e, 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 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 displays (HMDs), head-up displays (HUDs) installed in vehicles, televisions, smartphones, computers, wearable devices, home appliances, digital signage, vehicles, robots, etc. Handheld devices may include smartphones, smart tablets, wearable devices (e.g., smartwatches or smart glasses), and computers (e.g., laptops). Home appliances may include televisions, refrigerators, and washing machines. IoT devices may include sensors and smart meters.

[0036] In this disclosure, wireless devices 100a to 100f may be referred to as user equipment (UE). For example, a UE may include a cellular phone, smartphone, laptop computer, digital broadcasting terminal, personal digital assistant (PDA), portable multimedia player (PMP), navigation system, Slate PC, tablet PC, ultrabook, vehicle, vehicle with autonomous driving capability, connected car, UAV, AI module, robot, AR device, VR device, MR device, holographic device, public safety device, MTC device, IoT device, medical device, fintech device (or financial device), security device, weather / environment device, device related to 5G services, or device related to the Fourth Industrial Revolution.

[0037] For example, a UAV can be an aircraft that flies wirelessly via control signals without a crew.

[0038] For example, a VR device may include means for realizing objects or backgrounds in a virtual world. For example, an AR device may include means for connecting objects or backgrounds in a virtual world to objects or backgrounds in a real world. For example, a MR device may include means for incorporating objects or backgrounds in a virtual world into objects or backgrounds in a real world. For example, a holographic device may include means for recording and reproducing stereoscopic information using the light interference phenomenon produced when two lasers meet, known as holography, to create a 360-degree stereoscopic image.

[0039] For example, public safety devices may include image relay devices or image devices that can be worn on the user's body.

[0040] For example, MTC devices and IoT devices can be devices that do not require direct human intervention or manipulation. For example, MTC devices and IoT devices can include smart meters, vending machines, thermometers, smart light bulbs, door locks, or various sensors.

[0041] For example, a medical device can be a device for the purpose of diagnosing, treating, alleviating, treating, or preventing disease. For example, a medical device can be a device for the purpose of diagnosing, treating, alleviating, or correcting injury or trauma. For example, a medical device can be a device for the purpose of examining, replacing, or modifying a structure or function. For example, a medical device can be a device for regulating pregnancy. For example, a medical device may include a device for treatment, a device for operation, a device for (in vitro) diagnosis, a hearing aid, or a device for surgery.

[0042] For example, a safety device can be a device installed to prevent potential dangers and maintain safety. For example, a safety device can be a camera, closed-circuit television (CCTV), a recorder, or a black box.

[0043] For example, a fintech device can be a device capable of providing financial services such as mobile payments. For instance, a fintech device may include a payment device or a point-of-sale (POS) system.

[0044] For example, weather / environment devices may include devices for monitoring or predicting weather / environment.

[0045] Wireless devices 100a to 100f can connect to network 300 via BS 200. AI technology can be applied to wireless devices 100a to 100f, and wireless devices 100a to 100f can connect to AI server 400 via network 300. Network 300 can be configured using 3G, 4G (e.g., LTE), 5G (e.g., NR), and super 5G networks. Although wireless devices 100a to 100f can communicate with each other via BS 200 / network 300, wireless devices 100a to 100f can also perform direct communication with each other without going through BS 200 / network 300 (e.g., sidelink communication). For example, vehicles 100b-1 and 100b-2 can perform direct communication (e.g., vehicle-to-vehicle (V2V) / vehicle-to-everything (V2X) communication). IoT devices (e.g., sensors) can perform direct communication with other IoT devices (e.g., sensors) or other wireless devices 100a to 100f.

[0046] Wireless communication / connections 150a, 150b, and 150c can be established between wireless devices 100a to 100f and / or between wireless devices 100a to 100f and BS 200 and / or between BS200. In this document, wireless communication / connections can be established via various RATs (e.g., 5G NR), such as uplink / downlink communication 150a, sidelink communication or device-to-device (D2D) communication 150b, inter-base station communication 150c (e.g., relay, integrated access and backhaul (IAB)), etc. Wireless devices 100a to 100f and BS200 / wireless devices 100a to 100f can send / receive radio signals to each other via wireless communication / connections 150a, 150b, and 150c. For example, wireless communication / connections 150a, 150b, and 150c can send / receive signals via various physical channels. Therefore, at least a portion of the various configuration information configuration processes, various signal processing processes (e.g., channel coding / decoding, modulation / demodulation, and resource mapping / demapping), and resource allocation processes used for transmitting / receiving radio signals can be performed based on various proposals of this disclosure.

[0047] AI refers to the field of studying artificial intelligence or the methods that can create it, while machine learning refers to the field that defines the various problems solved within AI and the methods for solving them. Machine learning is also defined as algorithms that improve the performance of a task through stable experience with that task.

[0048] A robot is a machine that automatically processes or operates a given task through its own capabilities. In particular, robots capable of recognizing their environment and autonomously determining the actions they must perform can be called intelligent robots. Depending on their purpose or field of use, robots can be classified as industrial, medical, domestic, military, etc. Robots can perform various physical operations, such as moving their joints using actuators or motors. Mobile robots also include driven wheels, brakes, propellers, etc., allowing them to move on the ground or fly in the air.

[0049] Autonomous driving refers to the technology of driving itself, and autonomous vehicles refer to vehicles driven without user control or with minimal user control. For example, autonomous driving can include maintaining a lane while in motion, automatically adjusting speed (e.g., adaptive cruise control), driving automatically along a set route, and automatically setting a route when a destination is set. Vehicles encompass vehicles equipped with internal combustion engines, hybrid vehicles equipped with both internal combustion engines and electric motors, and electric vehicles equipped with electric motors, and can include trains, motorcycles, and automobiles. Autonomous vehicles can be considered as robots with autonomous driving capabilities.

[0050] Extended reality is collectively referred to as VR, AR, and MR. VR technology provides real-world objects and backgrounds solely through computer graphics (CG) images. AR technology provides virtual CG images on top of real-world object images. MR technology is a CG technique that combines virtual objects into the real world. MR technology is similar to AR technology in that it displays real and virtual objects together. However, the difference lies in that in AR technology, virtual objects serve as a supplementary form to real objects, while in MR technology, virtual and real objects are treated as equal entities.

[0051] NR supports multiple parameter sets (and / or multiple subcarrier spacings (SCS)) to support a variety of 5G services. For example, a 15kHz SCS can support wide areas in traditional cellular bands, while a 30kHz / 60kHz SCS can support dense urban areas, lower latency, and wider carrier bandwidth. A 60kHz or higher SCS can support bandwidths greater than 24.25GHz to overcome phase noise.

[0052] NR bands can be defined as two types of frequency ranges, namely FR1 and FR2. The numerical values ​​of the frequency ranges can vary. For example, the two types of frequency ranges (FR1 and FR2) can be shown in Table 1 below. For ease of explanation, in the frequency ranges used in NR systems, FR1 can mean "the range below 6 GHz" and FR2 can mean "the range above 6 GHz" and can be referred to as millimeter wave (mmW).

[0053] [Table 1]

[0054] As mentioned above, the frequency range of the NR system can be varied. For example, as shown in Table 2 below, FR1 can include a frequency band from 410MHz to 7125MHz. That is, FR1 can include a frequency band of 6GHz (or 5850MHz, 5900MHz, 5925MHz, etc.) or higher. For example, the 6GHz (or 5850MHz, 5900MHz, 5925MHz, etc.) or higher frequency band included in FR1 can include unlicensed frequency bands. Unlicensed frequency bands can be used for various purposes, such as for vehicle communications (e.g., autonomous driving).

[0055] [Table 2]

[0056] Here, the radio communication technologies implemented in the wireless devices of this disclosure may include narrowband Internet of Things (NB-IoT) technologies for low-power communication, as well as LTE, NR, and 6G. For example, NB-IoT technology may be an example of low-power wide-area network (LPWAN) technology, implemented in specifications such as LTE Cat NB1 and / or LTE Cat NB2, and is not limited to the names mentioned above. Additionally and / or alternatively, the radio communication technologies implemented in the wireless devices of this disclosure may be based on LTE-M technology. For example, LTE-M technology may be an example of LPWAN technology and referred to by various names such as enhanced machine-type communication (eMTC). For example, LTE-M technology may be implemented in at least one of various specifications such as 1) LTE Cat 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-bandwidth limited (non-BL), 5) LTE-MTC, 6) LTE machine-type communication, and / or 7) LTE M, and is not limited to the names mentioned above. Additionally and / or alternatively, the radio communication technologies implemented in the wireless devices of this disclosure may include at least one of ZigBee, Bluetooth, and / or LPWAN, which take into account low-power communication, and may not be limited to the names mentioned above. For example, ZigBee technology may generate personal area networks (PANs) associated with small / low-power digital communication based on various specifications such as IEEE 802.15.4, and may be referred to by various names.

[0057] Figure 2 An example of a wireless device that applies an implementation of the present disclosure is shown.

[0058] exist Figure 2 In this context, the first wireless device 100 and / or the second wireless device 200 may be implemented in various forms depending on the usage / service. For example, {the first wireless device 100 and the second wireless device 200} may correspond to... Figure 1 At least one of {wireless devices 100a to 100f and BS 200}, {wireless devices 100a to 100f and wireless devices 100a to 100f} and / or {BS 200 and BS 200}. The first wireless device 100 and / or the second wireless device 200 may be configured from various elements, devices / components and / or modules.

[0059] The first wireless device 100 may include at least one transceiver (e.g., transceiver 106), at least one processing chip (e.g., processing chip 101), and / or one or more antennas 108.

[0060] The processing chip 101 may include at least one processor (e.g., processor 102) and at least one memory (e.g., memory 104). Additionally and / or alternatively, the memory 104 may be located outside the processing chip 101.

[0061] Processor 102 can control memory 104 and / or transceiver 106, and can be adapted to implement the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts described in this disclosure. For example, processor 102 can process information in memory 104 to generate first information / signal, and then transmit a radio signal including the first information / signal via transceiver 106. Processor 102 can receive a radio signal including a second information / signal via transceiver 106, and then store the information obtained by processing the second information / signal in memory 104.

[0062] Memory 104 may be operatively connected to processor 102. Memory 104 may store various types of information and / or instructions. Memory 104 may store firmware and / or software code 105 that implements code, commands, and / or command sets, which, when executed by processor 102, perform the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in this disclosure. For example, firmware and / or software code 105 may implement instructions that, when executed by processor 102, perform the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in this disclosure. For example, firmware and / or software code 105 may control processor 102 to execute one or more protocols. For example, firmware and / or software code 105 may control processor 102 to execute one or more layers of a radio interface protocol.

[0063] In this document, processor 102 and memory 104 may be part of a communication modem / circuit / chip designed to implement RAT (e.g., LTE or NR). Transceiver 106 may be connected to processor 102 and transmit and / or receive radio signals via one or more antennas 108. Each transceiver 106 may include a transmitter and / or a receiver. Transceiver 106 may be used interchangeably with radio frequency (RF) units. In this disclosure, first wireless device 100 may represent a communication modem / circuit / chip.

[0064] The second wireless device 200 may include at least one transceiver (e.g., transceiver 206), at least one processing chip (e.g., processing chip 201), and / or one or more antennas 208.

[0065] The processing chip 201 may include at least one processor (e.g., processor 202) and at least one memory (e.g., memory 204). Additionally and / or alternatively, the memory 204 may be located outside the processing chip 201.

[0066] Processor 202 can control memory 204 and / or transceiver 206, and can be adapted to implement the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts described in this disclosure. For example, processor 202 can process information in memory 204 to generate third information / signal, and then transmit a radio signal including the third information / signal via transceiver 206. Processor 202 can receive a radio signal including a fourth information / signal via transceiver 106, and then store the information obtained by processing the fourth information / signal in memory 204.

[0067] Memory 204 may be operatively connected to processor 202. Memory 204 may store various types of information and / or instructions. Memory 204 may store firmware and / or software code 205 that implements code, commands, and / or command sets, which, when executed by processor 202, perform the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in this disclosure. For example, firmware and / or software code 205 may implement instructions that, when executed by processor 202, perform the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in this disclosure. For example, firmware and / or software code 205 may control processor 202 to execute one or more protocols. For example, firmware and / or software code 205 may control processor 202 to execute one or more layers of a radio interface protocol.

[0068] In this document, processor 202 and memory 204 may be part of a communication modem / circuit / chip designed to implement RAT (e.g., LTE or NR). Transceiver 206 may be connected to processor 202 and transmit and / or receive radio signals via one or more antennas 208. Each transceiver 206 may include a transmitter and / or a receiver. Transceiver 206 may be used interchangeably with an RF unit. In this disclosure, second wireless device 200 may represent a communication modem / circuit / chip.

[0069] The hardware elements of wireless devices 100 and 200 will be described in more detail below. One or more protocol layers may be implemented by one or more processors 102 and 202, but are not limited thereto. For example, these one or more processors 102 and 202 may implement one or more layers (e.g., functional layers such as the Physical (PHY) layer, Media Access Control (MAC) layer, Radio Link Control (RLC) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Resource Control (RRC) layer, and Service Data Adaptation Protocol (SDAP) layer). These one or more processors 102 and 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, processes, suggestions, methods, and / or operation flowcharts disclosed in this disclosure. The one or more processors 102 and 202 may generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, or information, according to the descriptions, functions, procedures, suggestions, methods, and / or operation flowcharts disclosed in this disclosure, and provide the generated signals to the one or more transceivers 106 and 206. The one or more processors 102 and 202 may receive signals (e.g., baseband signals) from the one or more transceivers 106 and 206, and acquire PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods, and / or operation flowcharts disclosed in this disclosure.

[0070] One or more processors 102 and 202 may be referred to as controllers, microcontrollers, microprocessors, or microcomputers. These one or more processors 102 and 202 may be implemented by hardware, firmware, software, or a combination thereof. As an 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), or one or more field-programmable gate arrays (FPGAs) may be included in these one or more processors 102 and 202. For example, these one or more processors 102 and 202 may be configured as a collection of communication control processors, application processors (APs), electronic control units (ECUs), central processing units (CPUs), graphics processing units (GPUs), and memory control processors.

[0071] One or more memories 104, 204 may be associated with one or more processors 102, 202 and may store various forms of data, signals, messages, information, programs, code, instructions, and / or commands. These memories 104, 204 may include random access memory (RAM), dynamic RAM (DRAM), read-only memory (ROM), erasable programmable ROM (EPROM), flash memory, volatile memory, non-volatile memory, hard disk drive, registers, cache memory, computer-readable storage media, and / or combinations thereof. These memories 104, 204 may be located internally and / or externally to the processors 102, 202. Furthermore, these memories 104, 204 may be coupled to the processors 102, 202 via various technologies such as wired or wireless connections.

[0072] One or more transceivers 106, 206 may transmit user data, control information, wireless signals / channels, etc., as described herein, to one or more other devices. The one or more transceivers 106, 206 may receive user data, control information, wireless signals / channels, etc., as described herein, from one or more other devices. For example, the one or more transceivers 106, 206 may be associated with the one or more processors 102, 202 and may transmit and receive wireless signals. For example, the one or more processors 102, 202 may control the one or more transceivers 106, 206 to transmit user data, control information, wireless signals, etc., to one or more other devices. Furthermore, the one or more processors 102, 202 may control the one or more transceivers 106, 206 to receive user data, control information, wireless signals, etc., from one or more other devices.

[0073] One or more transceivers 106, 206 may be associated with one or more antennas 108, 208. Additionally and / or alternatively, the one or more transceivers 106, 206 may include one or more antennas 108, 208. The 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, features, processes, suggestions, methods, and / or operation flowcharts disclosed herein via the one or more antennas 108, 208. As used herein, the one or more antennas 108, 208 may be multiple physical antennas or multiple logical antennas (e.g., antenna ports).

[0074] One or more transceivers 106, 206 can convert received user data, control information, radio signals / channels, etc., from RF band signals to baseband signals so that the received user data, control information, radio signals / channels, etc., can be processed by the one or more processors 102, 202. The one or more transceivers 106, 206 can use the one or more processors 102, 202 to convert the processed user data, control information, radio signals / channels, etc., from baseband signals to RF band signals. For this purpose, the one or more transceivers 106, 206 may include (analog) oscillators and / or filters. For example, the one or more transceivers 106, 206 can, under the control of the one or more processors 102, 202, upconvert OFDM baseband signals to OFDM signals via (analog) oscillators and / or filters, and transmit the upconverted OFDM signals at a carrier frequency. One or more transceivers 106, 206 can receive OFDM signals at a carrier frequency and, under the control of one or more processors 102, 202, down-convert the OFDM signals to OFDM baseband signals via (analog) oscillators and / or filters.

[0075] although Figure 2 As not shown, wireless devices 100 and 200 may also include additional components. Additional component 140 may be configured differently depending on the type of wireless devices 100 and 200. For example, additional component 140 may include at least one of a power unit / battery, input / output (I / O) devices (e.g., audio I / O ports, video I / O ports), drive devices, and computing devices. Additional component 140 may be coupled to one or more processors 102 and 202 via various technologies such as wired or wireless connections.

[0076] In the implementation of this disclosure, the UE can operate as a transmitting device in the uplink (UL) and as a receiving device in the downlink (DL). In the implementation of this disclosure, the BS can operate as a receiving device in the UL and as a transmitting device in the DL. For ease of description, it is primarily assumed below that the first wireless device 100 acts as the UE and the second wireless device 200 acts as the BS. For example, a processor 102 connected to, installed on, or started in the first wireless device 100 may be adapted to perform UE behavior according to the implementation of this disclosure or to control the transceiver 106 to perform UE behavior according to the implementation of this disclosure. A processor 202 connected to, installed on, or started in the second wireless device 200 may be adapted to perform BS behavior according to the implementation of this disclosure or to control the transceiver 206 to perform BS behavior according to the implementation of this disclosure.

[0077] In this disclosure, BS is also referred to as Node B (NB), eNode B (eNB), or gNB.

[0078] Figure 3 An example of a UE that applies the implementation of this disclosure is shown.

[0079] Reference Figure 3 UE 100 can correspond to Figure 2 The first wireless device 100.

[0080] The UE 100 includes a processor 102, a memory 104, a transceiver 106, one or more antennas 108, a power management module 141, a battery 142, a display 143, a keyboard 144, a subscriber identification module (SIM) card 145, a speaker 146, and a microphone 147.

[0081] Processor 102 may be adapted to implement the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in this disclosure. Processor 102 may be adapted to control one or more other components of UE 100 to implement the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in this disclosure. A layer of the radio interface protocol may be implemented in processor 102. Processor 102 may include an ASIC, other chipsets, logic circuits, and / or data processing means. Processor 102 may be an application processor. Processor 102 may include at least one of a DSP, CPU, GPU, and modem (modulator and demodulator). Examples of processor 102 can be found in […]. Manufacturing SNAPDRAGON TM Series processors EXYNOS manufactured TM Series processors A series of processors manufactured HELIO manufactured TM Series processors Manufactured ATOM TM This series of processors or the corresponding next-generation processors.

[0082] Memory 104 is operatively coupled to processor 102 and stores various information to operate processor 102. Memory 104 may include ROM, RAM, flash memory, memory card, storage medium, and / or other storage devices. When the implementation is software-based, the techniques described herein may be implemented using modules (e.g., procedures, functions, etc.) that perform the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed herein. Modules may be stored in memory 104 and executed by processor 102. Memory 104 may be implemented within or outside processor 102, in which case it may be communicatively coupled to processor 102 via various means known in the art.

[0083] Transceiver 106 is operatively coupled to processor 102 and transmits and / or receives radio signals. Transceiver 106 includes a transmitter and a receiver. Transceiver 106 may include baseband circuitry for processing radio frequency signals. Transceiver 106 controls one or more antennas 108 to transmit and / or receive radio signals.

[0084] The power management module 141 manages the power of the processor 102 and / or transceiver 106. The battery 142 supplies power to the power management module 141.

[0085] Display 143 outputs the results processed by processor 102. Keyboard 144 receives input to be used by processor 102. Keyboard 144 can be displayed on display 143.

[0086] The SIM card 145 is an integrated circuit designed to securely store the International Mobile Subscriber Identity (IMSI) number and its associated key used for identifying and authenticating subscribers on mobile devices such as mobile phones and computers. Contact information can also be stored on many SIM cards.

[0087] Speaker 146 outputs the sound-related results processed by processor 102. Microphone 147 receives the sound-related input to be used by processor 102.

[0088] Figure 4 This is a block diagram of the next-generation cellular network.

[0089] The 5G core (5GC) can include various components, some of which are in Figure 5 The diagram shows functions such as Access and Mobility Management Function (AMF) (410), Session Management Function (SMF) (420), Policy Control Function (PCF) (430), User Plane Function (UPF) (440), Application Function (AF) (450), Unified Data Management (UDM) (460) and Non-3GPP Interoperability Function (N3IWF) (490).

[0090] UE 100 connects to the data network via UPF 440 through a next-generation radio access network (NG-RAN) including gNB 20.

[0091] Data services can also be provided to UE 100 via untrusted non-3GPP access (such as wireless local area network (WLAN)). To connect the aforementioned non-3GPP access to the core network, an N3IWF 490 can be deployed.

[0092] The N3IWF 490 shown performs the function of managing interoperability between non-3GPP access and 5G systems. When UE 100 is associated with a non-3GPP access (e.g., WiFi, also known as IEEE 801.11), UE 100 can associate with a 5G system via the N3IWF 490. The N3IWF 490 communicates with the AMF 410 for control signaling and with the UPF 440 via the N3 interface for data transmission.

[0093] The AMF 410 shown can manage access and mobility in 5G systems. The AMF 410 can perform functions for managing Non-Access Stratum (NAS) security. The AMF 410 can perform functions for handling mobility in idle states.

[0094] The UPF 440 shown is a gateway through which user data is sent and received. The UPF node 440 can perform all or part of the user plane functions of a Serving Gateway (S-GW) and Packet Data Network Gateway (P-GW) for fourth-generation mobile communications.

[0095] The UPF 440 acts as a boundary between the Next Generation Radio Access Network (NG-RAN) and the core network, and is an element that maintains the data path between gNB 20 and SMF 420. Additionally, the UPF 440 acts as a mobility anchor when the UE 100 moves across the area served by gNB 20. The UPF 440 can perform PDU processing functions. For mobility within the NG-RAN (Next Generation Radio Access Network as defined in 3GPP Release 15 and later), the UPF can route packets. The UPF 440 can also be used as an anchor for mobility with other 3GPP networks (RANs defined prior to 3GPP Release 15, such as UTRAN, E-UTRAN (Evolved UMTS (Universal Mobile Telecommunications System) Terrestrial Radio Access Network) or GERAN (Global System for Mobile Communications (GSM) / EDGE (Global Evolution Enhanced Data Rate) Radio Access Network). The UPF 440 can correspond to the termination point of the data interface to the data network.

[0096] The PCF 430 shown is a node that controls the operator's policies.

[0097] The AF 450 shown is a server used to provide multiple services to UE 100.

[0098] The UDM 460 shown is a type of server that manages subscriber information, such as the Home Subscriber Server (HSS) in fourth-generation mobile communications. The UDM 460 stores and manages subscriber information in a unified data repository (UDR).

[0099] The SMF 420 shown can perform the function of assigning Internet Protocol (IP) addresses to UEs. The SMF 420 can also control Protocol Data Unit (PDU) sessions.

[0100] For reference purposes, the reference numerals for AMF 410, SMF 420, PCF 430, UPF 440, AF 450, UDM460, N3IWF 490, gNB 20, or UE 100 may be omitted in this document.

[0101] Fifth-generation mobile communication supports multiple parameter sets or subcarrier spacings (SCS) to support a variety of 5G services. For example, a 15kHz SCS supports wide-area coverage in traditional cellular bands; a 30kHz / 60kHz SCS supports dense urban areas, lower latency, and wider carrier bandwidth; and a 60kHz or higher SCS supports bandwidths greater than 24.25GHz to overcome phase noise.

[0102] Figure 5 An example 5G system architecture is illustrated, showing an implementation method that can be applied to this specification.

[0103] The architecture of a 5G system (5GS; 5G system) consists of the following network functions (NFs).

[0104] -AUSF (Authentication Server Functionality)

[0105] -AMF (Access and Mobility Management Function)

[0106] -DN (Data Network), such as carrier services, internet access, or third-party services.

[0107] -USDF (Unstructured Data Storage Function)

[0108] -NEF (Network Open Functionality)

[0109] -I-NEF (middle NEF)

[0110] -NRF (Network Storage Function)

[0111] -NSSF (Network Slice Selection Function)

[0112] -PCF (Policy Control Function)

[0113] -SMF (Session Management Function)

[0114] -UDM (Unified Data Management)

[0115] -UDR (Unified Data Repository)

[0116] -UPF (User Plane Function)

[0117] -UCMF (UE Radio Capability Management Function)

[0118] -AF (Application Function)

[0119] -UE (User Equipment)

[0120] - (R)AN (Radio Access Network)

[0121] -5G-EIR (5G Device Identifier Register)

[0122] -NWDAF (Network Data Analysis Function)

[0123] -CHF (Billing Function)

[0124] In addition, the following network functions can be considered.

[0125] -N3IWF (Non-3GPP interoperability function)

[0126] -TNGF (Trusted Non-3GPP Gateway Function)

[0127] -W-AGF (Wired Access Gateway Function)

[0128] Figure 5 The architecture of a 5G system in a non-roaming scenario is shown using reference points that illustrate how various network functions interact with each other.

[0129] exist Figure 5 For clarity of the point-to-point diagram, UDSF, NEF, and NRF are not described. However, all network functions shown can interact with UDSF, UDR, NEF, and NRF as needed.

[0130] For clarity, the connection between UDR and other NFs (e.g., PCF) is not shown in [the original text]. Figure 5 As shown in the image. For clarity, Figure 5 The connection between NWDAF and other NFs (e.g., PCF) is not shown.

[0131] The 5G system architecture includes the following reference points.

[0132] -N1: Reference point between UE and AMF.

[0133] -N2: (R) Reference point between AN and AMF.

[0134] -N3: (R) Reference point between AN and UPF.

[0135] -N4: Reference point between SMF and UPF.

[0136] -N6: Reference point between UPF and data network.

[0137] -N9: Reference point between two UPFs.

[0138] The following reference points illustrate the interactions that exist between NF services.

[0139] -N5: Reference point between PCF and AF.

[0140] -N7: Reference point between SMF and PCF.

[0141] -N8: Reference point between UDM and AMF.

[0142] -N10: Reference point between UDM and SMF.

[0143] -N11: Reference point between AMF and SMF.

[0144] -N12: Reference point between AMF and AUSF.

[0145] -N13: Reference point between UDM and AUSF.

[0146] -N14: Reference point between the two AMFs.

[0147] -N15: The reference point between the PCF and AMF in non-roaming scenarios, and the reference point between the PCF and AMF of the visited network in roaming scenarios.

[0148] -N16: Reference point between two SMFs (in the case of roaming, between the visiting SMF and the home SMF).

[0149] -N22: Reference point between AMF and NSSF.

[0150] In some cases, it may be necessary to connect two NFs to each other to serve the UE.

[0151] Figure 6 An example of the overall architecture of NG-RAN is shown.

[0152] Reference Figure 6A gNB can consist of a gNB-CU (Central Unit) and one or more gNB-DUs (Distributed Units). The gNB-CU is the logical node that hosts the gNB's RRC (Radio Resource Control), SDAP (Service Data Adaptation Protocol), and PDCP (Packet Data Convergence Protocol) protocols, or the en-gNB's RRC and PDCP protocols. The gNB-CU controls the operation of one or more gNB-DUs. The gNB-DU is the logical node that hosts the gNB or en-gNB's RLC (Radio Link Control), MAC (Media Access Control), and physical layer protocols. The operation of the gNB-DU is partially controlled by the gNB-CU. One gNB-DU supports one or more cells. A cell is supported by only one gNB-DU.

[0153] gNB-CU and gNB-DU are connected via an 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 appropriate implementation, a gNB-DU can be connected to multiple gNB-CUs. The F1 interface is a logical interface. In the NG-RAN case, 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. In the EN-DC case, 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. The gNB-CU and the gNB-DUs connected to it appear as gNBs only to other gNBs and 5GCs.

[0154] Figure 7 The logical nodes (CU-C, CU-U, and DU) within the logical gNB / en-gNB are illustrated.

[0155] Figure 7 yes Figure 6 This is one of the possible deployment scenarios for NG-RAN. The protocol for the NG and Xn interfaces terminates at... Figure 7 The middle part is represented by an ellipse. Figure 7 The central entity and distributed entities in the diagram represent physical network nodes.

[0156] Figure 8 This illustrates a deployment scenario for gNB.

[0157] Figure 8 Examples Figure 6 and Figure 7 Examples of NG-RAN architecture and possible deployment scenarios described in the document.

[0158] Figure 8(a) illustrates a folded gNB deployment scenario. In this deployment scenario, all RAN protocols and functions are in the same location. This deployment scenario corresponds to the deployment scenario used in current LTE. Because this deployment scenario is similar to the LTE architecture, maximum backward compatibility with existing LTE deployment scenarios is guaranteed.

[0159] Figure 8 (b) illustrates a decomposed deployment scenario. In this scenario, RAN protocol functions are distributed across different locations such as CU and DU. DU hosts RLC, MAC, and physical layer protocols. CU-CP hosts RRC and PDCP-C protocols. CU-UP hosts PDCP-U (and SDAP) protocols. DU and CU-CP can be connected via the F1-C interface. DU and CU-UP can be connected via the F1-U interface. CU-CP and CU-UP can be connected via the E1 interface.

[0160] according to Figure 8 The decomposed deployment scenario described in (b) allows for optimization and deployment of different RAN functions 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 deployed co-located with the DU. In this case, short latency can be provided for critical CP processes such as connection (re)establishment, handover, and state transition. On the other hand, the CU-UP can be centralized and deployed in a regional or national data center. Therefore, the CU-UP is advantageous for cloud implementation and can provide a centralized endpoint for UP services in the context of dual connectivity and tight interoperability. Furthermore, additional CU-UPs can be deployed near the DU (or in the same location as the DU) to provide a local endpoint for UP services for applications requiring very low latency, such as Ultra-Reliable Low Latency Communication (URLLC) services.

[0161] <Relay-related path switching>

[0162] Regarding communication via relays, path switching includes the following scenarios: - Switching from an indirect path to a direct path (inter-gNB indirect-to-direct path switching) (e.g., remote UE relaying UE A-gNB X to remote UE-gNB Y) - Handover from direct path to indirect path (Inter-gNB direct-to-indirect path switching) (e.g., remote UE-gNB X to remote UE-relay UE A-gNB Y) - Handover from indirect path to indirect path (Intra-gNB indirect-to-indirect path switching) (e.g., remote UE relay UE A-gNB X to remote UE relay UE B-gNB X) - Handover from indirect path to indirect path (inter-gNB indirect-to-indirect path switching) (e.g., remote UE relay UE A-gNB X to remote UE relay UE B-gNB Y) Traditionally, within a gNB, service continuity can be provided during transitions from a direct path to an indirect path (direct-to-indirect path handover) or from an indirect path to a direct path (indirect-to-direct path handover).

[0163] In the case of gNBs, path switching and switching from an indirect path to an indirect path (indirect-to-indirect path switching) are problematic.

[0164] In indirect path scenarios (e.g., where the NG-RAN and remote UE exchange data via a relay UE), has the NG-RAN properly delivered DL (downlink) data received from the RLC located in the relay UE? Alternatively, in indirect path scenarios, has the remote UE properly delivered UL (uplink) data received from the RLC located in the relay UE?

[0165] Therefore, in the case of an indirect path, the NG-RAN may not know whether the corresponding data has been successfully delivered via the PC5 link (for DL). Alternatively, the remote UE may not know whether the corresponding data has been successfully delivered via the Uu link (for UL).

[0166] For example, the transmission of DL data from the NG-RAN may fail on the PC5 link, and the NG-RAN may be unaware of the failure. Alternatively, the transmission of UL data from a remote UE may fail on the Uu link, and the remote UE may be unaware of the failure.

[0167] When the NG-RAN (or remote UE) receives an ACK message from the RLC located in the relay UE, the NG-RAN (or remote UE) may delete the DL (or UL) data packet. In this case, if the DL (or UL) packet cannot be sent via the PC5 (or Uu) link, the NG-RAN (or remote UE) may not resend the packet to the remote UE (or NG-RAN), thus lossless delivery is problematic.

[0168] When a path change occurs within a gNB, UL / DL lossless delivery can be supported without separate specification support.

[0169] In the case of gNBs (e.g., when the base station changes), proactive data forwarding has been proposed to support lossless delivery in deep learning.

[0170] Proactive data forwarding refers to the following scheme: the source base station (source NG-RAN) continuously buffers DL data packets successfully sent to the relay UE without deleting the DL data packets, and then the source base station delivers the buffered DL data to the target base station (target NG-RAN) during the handover process of the remote UE. This scheme can be applied when the base station (gNB) is not classified as CU-CP, CU-UP, or DU.

[0171] When a base station (gNB) is divided into CU-CP, CU-UP, and DU, CU-UP can delete the corresponding DL data packets based solely on the ACK information sent by the relay UE's RLC, because CU-UP is unaware whether the bearer created / assigned for the current remote UE was sent through the relay UE. Then, when the base station is changed, a problem may arise where lossless DL delivery cannot be guaranteed.

[0172] To address this issue, the CU-UP needs to know that the current remote UE is accessing via a relay UE. Additionally, the CU-UP needs to know that proactive data forwarding should be supported.

[0173] According to embodiments of this disclosure, the CU-CP can notify the CU-UP that the current remote UE is accessing via a relay UE. Based on this, the CU-UP can cache DL data packets successfully transmitted by the DU to the relay UE without deleting them. When a handover occurs later with a changed base station, the CU-UP can send the cached data packets to the target base station.

[0174] Then, even if the transmission of DL data packets fails via the PC5 link, the remote UE can still receive the packets from the target base station.

[0175] A method can be proposed for CU-CP to notify CU-UP that a remote UE has been accessed through a relay UE and needs to actively forward data.

[0176] In the methods proposed in this disclosure, some service operations between core NFs (Network Functions) can be used by defining new service operations. Existing service operations can also be used in the operations of the methods proposed in this disclosure.

[0177] In the NG messages between the AMF and NG-RAN of this disclosure, some can be used by defining new NG messages. Additionally, in the RRC messages between the NG-RAN and UE of this disclosure, some can be used by defining new RRC messages.

[0178] In this disclosure, some steps may be performed simultaneously / in parallel, or in reverse order.

[0179] The names of the indications or parameter information in this disclosure are examples and may be interpreted by other names used for the proposed process / purpose / scheme.

[0180] CU-CP can be a logical node of a base station that constitutes the managed RRC (Radio Resource Control) protocol and the PDCP (Packet Data Convergence Protocol-C) protocol.

[0181] CU-UP can be a logical node that constitutes a base station hosting PDCP-U.

[0182] Figure 9 A flowchart illustrating an embodiment according to the present disclosure is provided.

[0183] During the bearer context establishment process (or bearer context modification process or bearer context modification required process) for a remote UE, the CU-CP can send an indication to the CU-UP that the remote UE has been accessed through the relay UE. Based on this, the CU-UP can continuously cache the DL data successfully sent to the relay UE without deleting it.

[0184] Step 1. You can perform steps 1 to 19 of the remote UE initial access procedure in Clause 8.19.1 of TS 38.401 v17.5.0.

[0185] Step 2. The CU-CP can request the CU-UP to create / assign a bearer context for the remote UE. At this time, the CU-CP can also send an indication to the CU-UP that the remote UE is accessing through a relay UE. This indication can be an indirect path indication, which indicates that the path used for the remote UE (the path between the remote UE and the base station) is an indirect path.

[0186] The CU-CP can identify whether the connection between the relay UE and the base station is for a remote UE. For example, the CU-CP can identify whether the path to the remote UE is an indirect path. The CU-CP can send an indirect path indication to the CU-UP to notify it of this fact.

[0187] For lossless DL delivery, even if the CU-UP receives a DDDS (Downlink Data Delivery Status) frame from the DU that includes "PDCP SN successfully delivered", the CU-UP can continue to cache DL data until the PDCP SN based on the aforementioned indication, without deleting it.

[0188] Instead of sending an indication to CU-UP that a remote UE is accessing via a relay UE, CU-CP can send an additional buffer N to CU-UP. buffer Information (or instructions) for each DL data packet. Then, CU-UP can delete DL data packets up to the PDCP SN, which is obtained by subtracting N from the 'successfully delivered PDCP SN' received from the DU. buffer The data obtained can then be cached for subsequent DL data groups. For example, CU-UP can additionally cache N... buffer Each DL data group.

[0189] Alternatively, instead of (or simultaneously) the CU-CP sending an indication to the CU-UP that a remote UE is accessing via a relay UE, the CU-CP can additionally configure a timer value for the CU-UP to cache DL data. Then, even if the DU receives an indication that the PDCP PDU has been successfully sent to the relay UE, the CU-UP can cache the corresponding DL data until the timer configured by the CU-CP expires, without deleting the DL data. When the timer expires, the CU-UP can delete the DL data.

[0190] Alternatively, the CU-CP can explicitly notify the CU-UP that proactive data forwarding is required. In this case, the CU-UP can additionally cache any number of DL data based on its implementation, regardless of the "successfully delivered PDCPSN" received from the DU.

[0191] In addition to informing the CU-UP that a remote UE is accessing via a relay UE, the CU-CP can also deliver information to the CU-UP.

[0192] Step 2 can be performed during the bearer context modification process or during the process required to modify the bearer context, rather than during the bearer context process.

[0193] Step 3. CU-UP can send the resources and bearer context information allocated for the bearer to CU-CP.

[0194] Step 4. The remaining steps of the remote UE initial access procedure of Clause 8.19.1 of TS 38.401 v17.5.0 can be performed.

[0195] Remote UEs and NG-RANs can send and receive DL / UL data via relay UEs.

[0196] Step 5. When the DU successfully sends DL data (DL data received from the CU-UP) to the relay UE, the DU can notify the CU-UP of this fact via DDDS (Downlink Data Delivery Status).

[0197] DDDS can include 'the highest successfully delivered NR PDCP sequence number' and / or 'the number of PDCP sequence number ranges successfully delivered out of sequence'. 'The highest successfully delivered NR PDCP sequence number' can be the highest sequence number of successfully transmitted NR PDCPs. 'The number of PDCP sequence number ranges successfully delivered out of sequence' can be the number of successfully transmitted PDCP sequence ranges.

[0198] The DU can send DL data (received from the CU-UP) to the relay UE for the remote UE. When the relay UE receives the data, it can send an Ack to the DU. The DU can then use the Ack to notify the CU-UP via DDDS that the DL data packet has been successfully sent to the relay UE.

[0199] For the DDDS mentioned above, the content in the DL data delivery status (PDU type 1) format defined in TS 38.425 v17.3.0 can be applied.

[0200] Table 3 shows an example of DDDS.

[0201] [Table 3]

[0202] Regardless of whether the CU-CP notifies the CU-UP that the remote UE has accessed through the relay UE in step 2, the DU can notify the CU-UP via DDDS in step 5 that data is being sent to the remote UE through the relay UE. Then, even if no indication is received from the CU-CP in step 2, the CU-UP can continue to cache DL data based on the information received from the DU in step 5.

[0203] Alternatively, according to the DU implementation, when generating / determining the information included in the DDDS in step 5, the DU can configure values ​​such as 'highest successfully delivered NR PDCP sequence number' and / or 'number of PDCP sequence number ranges that were not successfully delivered in sequence', taking into account active data forwarding.

[0204] For example, even though the DU has successfully delivered DL data to the relay UE, the DU may not include the PDCPSN information of the DL data in the DDDS for 'highest successfully delivered NR PDCP sequence number' and / or 'number of PDCP sequence number ranges not successfully delivered in sequence'. In this case, the CU-UP can determine that the DL data corresponding to the PDCP SN has not yet been delivered to the remote UE, and the CU-UP can continue to cache the DL data.

[0205] However, in order for the CU-UP to continue sending a certain amount of DL data toward the DU, considering active data forwarding, in step 5 of the DDDS, the DU can be configured with values ​​such as 'desired buffer size for the data radio bearer' and / or 'desired data rate'. 'Desired buffer size for the data radio bearer' can be the desired buffer size for the data radio bearer. 'Desired data rate' can be the desired data rate.

[0206] Alternatively, the CU-CP may request the DU to perform an operation that takes into account active data forwarding through the UE context setting or UE context modification procedure (e.g., not including the PDCPSN information of the corresponding DL data in the 'highest successfully delivered NR PDCP sequence number' and / or 'number of PDCP sequence number ranges that were not successfully delivered in sequence' in the DDDS, even if the DL data has been successfully delivered to the relay UE).

[0207] Step 6. Even if the CU-UP receives the PDCPSN successfully sent to the relay UE from the DU in step 5, the CU-UP may continue to cache the DL data for the PDCPSN based on the instruction received from the CU-CP in step 2, without deleting it.

[0208] Step 7. Due to the movement of the remote UE, the CU-CP of NG-RAN1 can decide to perform a handover for the remote UE to NG-RAN2 (Xn-based handover or NG-based handover).

[0209] At this point, the CU-CP of NG-RAN1 can perform active data forwarding together for lossless delivery of DL.

[0210] The CU-UP of NG-RAN1 can notify the CU-CP of NG-RAN1 of the PDCP SN information that has been successfully sent to the relay UE so far. Then, the CU-CP of NG-RAN1 can deliver the corresponding information to NG-RAN2 via the SN STATUS TRANSFER message.

[0211] Additionally, the CU-UP of NG-RAN1 can deliver cached data to NG-RAN2. At this time, the CU-UP can also deliver persistently cached DL data to NG-RAN2, even if it was successfully sent to the relay UE in step 6.

[0212] NG-RAN2 can receive 'PDCP status reports' from remote UEs. Based on this, NG-RAN2 can send additional DL data that needs to be retransmitted from the DL data received from NG-RAN1 to the remote UE.

[0213] According to the disclosure in this specification, the CU-UP of NG-RAN1 can cache DL data successfully transmitted from the DU to the relay UE without deleting it. When the remote UE later switches to NG-RAN2, the CU-UP of NG-RAN1 can additionally deliver the cached DL data to NG-RAN2. NG-RAN2 can then additionally send to the remote UE any DL data that needs to be retransmitted from the DL data received from NG-RAN1, based on the 'PDCP status report' sent by the remote UE. This method avoids the loss of some DL data from the perspective of the remote UE.

[0214] The attached diagram can be executed independently or in conjunction with other diagrams. Figure 1 Start execution.

[0215] The following operations can be performed: - CU-CP can notify CU-UP that a remote UE has accessed through a relay UE during the bearer context establishment or bearer context modification process for a remote UE.

[0216] - CU-UP can continuously cache DL data successfully sent to the relay UE based on information received from CU-CP and DU, without deleting it.

[0217] - CU-UP can deliver continuously cached DL data to the target NG-RAN in the event of a handover to a remote UE.

[0218] The following figures are created to illustrate specific examples of this specification. Since the specific names of the devices or signals / messages / fields described in the figures are presented as examples, the technical features of this specification are not limited to the specific names used in the following figures.

[0219] Figure 10 The CU-UP process disclosed in this specification is shown.

[0220] 1. The CU-UP can receive request messages related to the bearer context from the central unit-control plane (CU-CP) of the source base station.

[0221] The request message may include an indirect path indication.

[0222] Indirect path indication can indicate that the path between a remote user equipment (UE) and a source base station is an indirect path.

[0223] 2. CU-UP can send response messages to CU-CP based on request messages.

[0224] 3. CU-UP can send downlink data to remote UEs.

[0225] 4. The CU-UP can receive a delivery status message from the distributed unit (DU) of the source base station, which notifies that downlink data has been successfully sent to the relay UE for the remote UE.

[0226] CU-UP can skip dropping downlink data based on delivery status messages, based on indirect path indication.

[0227] 5. CU-UP can cache downlink data based on indirect path indications.

[0228] 6. CU-UP can send cached 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.

[0229] The request message can be a host context creation request or a host context modification request.

[0230] The request message may include a timer.

[0231] CU-UP can start a timer.

[0232] The caching process can be performed until the timer expires.

[0233] CU-UP can discard downlink data based on the expiration of a timer.

[0234] The response message may include allocated resources and hosting context information.

[0235] Delivery status messages can be sent via downlink data delivery status (DDDS) frames.

[0236] Downlink data can be sent to the DU and the relay UE.

[0237] CU-CP can be a logical node of a base station that constitutes the Managed Radio Resource Control (RRC) protocol and the Packet Data Convergence Protocol (PDCP)-C protocol.

[0238] CU-UP can be a logical node that constitutes a base station hosting PDCP-U.

[0239] The following figures are created to illustrate specific examples of this specification. Since the specific names of the devices or signals / messages / fields described in the figures are presented as examples, the technical features of this specification are not limited to the specific names used in the following figures.

[0240] Figure 11 The CU-CP process disclosed in this specification is shown.

[0241] 1. The CU-CP can send a request message related to the bearer context to the CU-UP of the source base station.

[0242] 2. CU-CP can send response messages to CU-CP based on request messages.

[0243] The request message may include an indirect path indication.

[0244] Indirect path indication can indicate that the path between the remote UE and the source base station is an indirect path.

[0245] The request message may include a timer.

[0246] The timer can include timing information for CU-UP buffering downlink data.

[0247] The response message may include allocated resources and hosting context information.

[0248] CU-CP can be a logical node that constitutes the base station hosting the RRC protocol and the PDCP-C protocol.

[0249] CU-UP can be a logical node that constitutes a base station hosting PDCP-U.

[0250] In the following, a device for performing communication according to some embodiments of this specification will be described.

[0251] For example, a device may include a processor, a transceiver, and memory.

[0252] For example, the processor can be configured to be operationally coupled to memory and processor.

[0253] The processor can perform the following actions: receiving a bearer context-related request message from the central unit-control plane (CU-CP) of the source base station; wherein the request message includes an indirect path indication, wherein the indirect path indication indicates that the path between the remote user equipment (UE) and the source base station is an indirect path; sending a response message to the CU-CP based on the request message; sending downlink data to the remote UE; receiving a delivery status message from the distributed unit (DU) of the source base station, the delivery status message notifying that the downlink data has been successfully sent to the relay UE for the remote UE; skipping the discarding of the downlink data according to the delivery status message based on the indirect path indication; caching the downlink data based on the indirect path indication; and sending the cached 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.

[0254] In the following sections, a processor for providing communication according to some embodiments of this specification will be described.

[0255] The processor is further configured to: receive a bearer context-related request message from the central unit-control plane (CU-CP) of the source base station; wherein the request message includes an indirect path indication, wherein the indirect path indication indicates that the path between the remote user equipment (UE) and the source base station is an indirect path; send a response message to the CU-CP based on the request message; send downlink data to the remote UE; receive a delivery status message from the distributed unit (DU) of the source base station, the delivery status message notifying that the downlink data has been successfully sent to the relay UE for the remote UE; skip discarding the downlink data according to the delivery status message based on the indirect path indication; cache the downlink data based on the indirect path indication; and send the cached 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.

[0256] In the following, a non-volatile computer-readable medium storing one or more instructions for providing multicast services in wireless communication will be described according to some embodiments of this specification.

[0257] According to some embodiments of this disclosure, the technical features of this disclosure can be directly implemented as hardware, software executed by a processor, or a combination of both. For example, in wireless communication, a method executed by a wireless device can be implemented in hardware, software, firmware, or any combination thereof. For example, software can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or other storage media.

[0258] Some examples of storage media are coupled to a processor, allowing the processor to read information from the storage media. Alternatively, the storage media can be integrated into the processor. The processor and storage media can reside in an ASIC. Yet another example is that the processor and storage media can reside as separate components.

[0259] Computer-readable media can include tangible and non-volatile computer-readable storage media.

[0260] For example, non-volatile computer-readable media may include random access memory (RAM), such as synchronous dynamic random access memory (SDRAM), read-only memory (ROM), or non-volatile random access memory (NVRAM). Read-only memory (EEPROM), flash memory, magnetic or optical data storage media, or other media that can be used to store instructions or data structures, or non-volatile computer-readable media may also include combinations of the above.

[0261] Furthermore, the methods described herein can be implemented at least in part through a computer-readable communication medium that carries or transmits code in the form of instructions or data structures and can be accessed, read, and / or executed by a computer.

[0262] According to some embodiments of this disclosure, a non-transitory computer-readable medium has one or more instructions stored thereon. The stored one or more instructions can be executed by a processor of a base station.

[0263] One or more stored instructions cause the processor to perform the following operations: receive a request message related to the bearer context from the central unit-control plane (CU-CP) of the source base station; wherein the request message includes an indirect path indication indicating that the path between the remote user equipment (UE) and the source base station is an indirect path; send a response message to the CU-CP based on the request message; send downlink data to the remote UE; receive a delivery status message from the distributed unit (DU) of the source base station, the delivery status message notifying that the downlink data has been successfully sent to the relay UE for the remote UE; skip discarding the downlink data according to the delivery status message based on the indirect path indication; cache the downlink data based on the indirect path indication; and send the cached 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.

[0264] This instruction manual can have various effects.

[0265] For example, S&F operations related to the connection of feeder links and service links can be performed.

[0266] The effects achievable through the specific examples in this specification are not limited to those listed above. For instance, there may be various technical effects that a person skilled in the art can understand or derive from this specification. Therefore, 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.

[0267] The claims described herein can be combined in various ways. For example, the technical features of the method claims of this specification can be combined and implemented as a device, and the technical features of the device claims of this specification can be combined and implemented as a method. Furthermore, the technical features of the method claims and the device claims of this specification can be combined and implemented as a device, and the technical features of the method claims and the device claims of this specification can be combined and implemented as a method. Other embodiments are within the scope of the appended claims.

Claims

1. A method for performing communication by a central unit-user plane (CU-UP) of a source base station, the method comprising: Receive a request message related to the bearer context from the central unit-control plane (CU-CP) of the source base station; The request message includes an indirect path indication. The indirect path indication indicates that the path between the remote user equipment (UE) and the source base station is an indirect path. A response message is sent to the CU-CP based on the request message; Send downlink data to the remote UE; The delivery status message is received from the distributed unit (DU) of the source base station, which informs that the downlink data has been successfully sent to the relay UE for the remote UE. Based on the indirect path indication, skip discarding the downlink data according to the delivery status message; The downlink data is cached based on the indirect path indication; and Based on the handover of the remote UE from the source base station to the target base station, the cached downlink data is sent to the target base station.

2. The method according to claim 1, in, The request message is a bearer context establishment request or a bearer context modification request.

3. The method according to claim 1 or claim 2, wherein the method further... include: in, The request message includes a timer. Start the timer; The caching step is performed until the timer expires; as well as The downlink data is discarded based on the expiration of the timer.

4. The method according to any one of claims 1 to 3, in, The response message includes allocated resources and bearer context information.

5. The method according to any one of claims 1 to 4, in, The delivery status message is sent via a downlink data delivery status (DDDS) frame.

6. The method according to any one of claims 1 to 5, in, The downlink data is sent to the DU and the relay UE.

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

8. A method for performing communication by a central unit-control plane (CU-CP) of a source base station, the method comprising: Send a request message related to the bearer context to the central unit-user plane CU-UP of the source base station; as well as A response message is sent to the CU-CP based on the request message. The request message includes an indirect path indication. The indirect path indication indicates that the path between the remote user equipment (UE) and the source base station is an indirect path.

9. The method according to claim 8, in, The request message includes a timer, and The timer includes time information for the downlink data cached by the CU-UP.

10. The method according to claim 8 or claim 9, in, The response message includes allocated resources and bearer context information.

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

12. A central unit-user plane (CU-UP) of a source base station for performing communications, the CU-UP comprising: transceiver; as well as processor, The processor performs an operation as described in any one of claims 1 to 7.

13. A central unit-control plane (CU-CP) for a source base station to perform communication, the CU-CP comprising: transceiver; as well as processor, The processor performs the operation as described in any one of claims 8 to 11.

14. A device for mobile communication, the device comprising: At least one processor; as well as At least one memory, which stores instructions and is operatively electrically connectable to the at least one processor. The instruction is operated by the at least one processor and performs an operation as described in any one of claims 1 to 7.

15. A non-volatile computer-readable storage medium, said non-volatile computer-readable storage medium having instructions recorded thereon. in, The instructions are based on being executed by one or more processors to cause the one or more processors to perform an operation as described in any one of claims 1 to 7.

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