Multi-path management method

Abstract

According to an embodiment of the invention, a method for remote UE to perform communication is provided. The method comprises the steps of: communicating with a first base station through a direct path without relaying via a relay UE; receiving first SIB information from the first base station; establishing a first PC5 link with the relay UE; communicating with the first base station over an indirect path via the relay UE based on the first PC5 link; receiving a notification message from the relay UE, the notification message including information indicating that the relay UE has performed cell reselection and second SIB information received by the relay UE from a second base station, and the second base station managing a target cell of the cell reselection; and determining whether multipath communication through the direct path and the indirect path is possible based on the first SIB information and the second SIB information.

Description

Technical Field

[0001] This specification relates to mobile communications. Background Art

[0002] The 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is a technology for enabling high-speed packet communications. Many schemes have been proposed for the LTE goal, including those aimed at reducing user and provider costs, improving service quality, and expanding and improving coverage and system capacity. As upper layer requirements, 3GPP LTE requires reduced cost per bit, increased service availability, flexible use of frequency bands, simple structure, open interfaces, and sufficient power consumption of terminals.

[0003] Development of requirements and specifications for New Radio (NR) systems has begun in the International Telecommunication Union (ITU) and 3GPP. 3GPP must identify and develop technical components for successful standardization of new RATs that will meet both immediate market needs and longer-term requirements set forth by the ITU Radiocommunication Sector (ITU-R) International Mobile Telecommunications (IMT)-2020 process in a timely manner. In addition, NR should be able to use any spectrum band in the range of at least up to 100 GHz that can be used for wireless communications even in the more distant future.

[0004] The goal of NR is a single technology framework that addresses all use cases, requirements and deployment scenarios, including enhanced mobile broadband (eMBB), massive machine type communications (mMTC), ultra-reliable and low latency communications (URLLC), etc. NR should be inherently forward compatible. Summary of the invention

[0005] Technical issues

[0006] There is a discussion about multipath using both an indirect path between a remote UE and a base station through a relay of a relay UE and a direct path between a remote UE and a base station without a relay of a relay UE. For multipath, a base station managing a serving cell of a remote UE and a base station managing a serving cell of a relay UE must be the same.

[0007] When communication is being performed through multipaths, if cell reselection and handover of the relay UE are performed, the base station for the relay UE may become different, which is problematic.

[0008] Technical Solution

[0009] When performing cell reselection and handover of the relay UE, the remote UE may be made aware of this fact so that the remote UE may decide whether to maintain the multipath. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1An example of a communication system to which implementations of the present disclosure are applied is shown.

[0011] Figure 2 An example of a wireless device to which implementations of the present disclosure are applied is shown.

[0012] Figure 3 An example of a UE to which implementations of the present disclosure are applied is shown.

[0013] Figure 4 is a block diagram of the next generation cellular network.

[0014] Figure 5a and Figure 5b The Layer 2 link establishment procedure for unicast mode of ProSe direct communication via PC5 reference point is illustrated.

[0015] Figure 6 The layer 2 release process through the PC5 reference point is shown.

[0016] Figure 7 This example illustrates a scenario where both direct and indirect paths serve the UE via the same NG-RAN.

[0017] Figure 8 This example illustrates a scenario where two different indirect paths serve a UE via the same NG-RAN.

[0018] Fig. 9 This example illustrates a scenario where a UE is served by a direct path and an indirect path via two different NG-RANs.

[0019] Fig.10 This example illustrates a scenario where two different indirect paths serve the UE via two different NG-RANs.

[0020] Fig.11 A flow chart according to an embodiment of the present specification is shown.

[0021] Fig.12 A flow chart according to an embodiment of the present specification is shown.

[0022] Fig.13 The process of the remote UE for the disclosure of this specification is shown.

[0023] Fig.14 A process for a relay UE disclosed in this specification is shown.

[0024] Fig.15 A process for a first base station disclosed in this specification is shown. DETAILED DESCRIPTION

[0025] 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 multi-carrier frequency division multiple access (MC-FDMA) systems. CDMA can be implemented by radio technologies such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can be implemented by radio technologies such as Global System for Mobile Communications (GSM), General Packet Radio Service (GPRS), or Enhanced Data Rate for GSM Evolution (EDGE). OFDMA can be implemented by radio technologies such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, or Evolved UTRA (E-UTRA). UTRA is part of Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is a part of Evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE adopts OFDMA in DL and SC-FDMA in UL. The evolutions of 3GPP LTE include LTE-A (Advanced), LTE-A Pro and / or 5G NR (New Radio).

[0026] For the convenience of description, the implementation of the present disclosure is mainly described with respect to a 3GPP-based wireless communication system. However, the technical features of the present disclosure are not limited thereto. For example, although the following detailed description is given based on a mobile communication system corresponding to a 3GPP-based wireless communication system, various aspects of the present disclosure that are not limited to a 3GPP-based wireless communication system are applicable to other mobile communication systems.

[0027] For terms and techniques not specifically described among the terms and techniques used in the present disclosure, reference may be made to wireless communication standard documents published prior to the present disclosure.

[0028] In the present disclosure, "A or B" may mean "only A", "only B", or "both A and B". In other words, "A or B" in the present disclosure may be interpreted as "A and / or B". For example, "A, B, or C" in the present disclosure may mean "only A", "only B", "only C", or "any combination of A, B, and C".

[0029] In the present disclosure, a slash ( / ) or a comma (,) may mean "and / or". For example, "A / B" may mean "A and / or B". Thus, "A / B" may mean "only A", "only B", or "both A and B". For example, "A, B, C" may mean "A, B, or C".

[0030] In the present disclosure, "at least one of A and B" may mean "only A", "only B", or "both A and B". In addition, the expression "at least one of A or B" or "at least one of A and / or B" in the present disclosure may be interpreted as being the same as "at least one of A and B".

[0031] Additionally, in the disclosure, “at least one of A, B, and C” may 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” may mean “at least one of A, B, and C.”

[0032] In addition, the brackets used in the present disclosure may mean "for example". In detail, when it is shown as "control information (PDCCH)", "PDCCH" may be proposed as an example of "control information". In other words, the "control information" in the present disclosure is not limited to "PDCCH", and "PDCCH" may be proposed as an example of "control information". In addition, even when it is shown as "control information (ie, PDCCH)", "PDCCH" may be proposed as an example of "control information".

[0033] The technical features described separately in one drawing in the present disclosure may be implemented separately or simultaneously.

[0034] Although not limited thereto, the various descriptions, functions, processes, suggestions, methods and / or operational flowcharts of the present disclosure disclosed herein may be applied to various fields requiring wireless communication and / or connection between devices (e.g., 5G).

[0035] Hereinafter, the present 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 descriptions may represent the same and / or corresponding hardware blocks, software blocks and / or functional blocks.

[0036] Figure 1 An example of a communication system to which an implementation of the present disclosure is applied is shown.

[0037] Figure 1 The 5G usage scenarios shown are only exemplary. The technical features of the present disclosure can be applied to Figure 1 Other 5G usage scenarios not shown.

[0038] The three main requirement categories for 5G include (1) enhanced mobile broadband (eMBB) category, (2) massive machine type communications (mMTC) category, and (3) ultra-reliable and low latency communications (URLLC) category.

[0039] Reference Figure 1 , the communication system 1 includes wireless devices 100a to 100f, a base station (BS) 200, and a network 300. Figure 1 A 5G network is shown as an example of a network of the communication system 1 , but implementations of the present disclosure are not limited to the 5G system and may be applied to future communication systems other than the 5G system.

[0040] BS 200 and network 300 may be implemented as wireless devices, and certain wireless devices may operate as BSs / network nodes relative to other wireless devices.

[0041] The wireless devices 100a to 100f represent devices that perform communication using a radio access technology (RAT) (e.g., 5G new RAT (NR) or LTE), and may be referred to as communication / radio / 5G devices. The wireless devices 100a to 100f may include, but are not limited to, a robot 100a, vehicles 100b-1 and 100b-2, an extended reality (XR) device 100c, a handheld device 100d, a home appliance 100e, an IoT device 100f, and an artificial intelligence (AI) device / server 400. For example, a vehicle may include a vehicle with a wireless communication function, an autonomous driving vehicle, and a vehicle capable of performing communication between vehicles. A vehicle may include an unmanned vehicle (UAV) (e.g., a drone). An XR device may include an AR / VR / mixed reality (MR) device, and may be implemented in the form of a head mounted device (HMD), a head up display (HUD) installed in a vehicle, a television, a smart phone, a computer, a wearable device, a home appliance device, a digital signage, a vehicle, a robot, and the like. Handheld devices may include smart phones, smart pads, wearable devices (e.g., smart watches or smart glasses), and computers (e.g., notebooks). Home appliances may include televisions, refrigerators, and washing machines. IoT devices may include sensors and smart meters.

[0042] In the present disclosure, the wireless devices 100a to 100f may be referred to as user equipment (UE). For example, the UE may include a cellular phone, a smart phone, a laptop computer, a digital broadcast terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), a navigation system, a slate personal computer (PC), a tablet PC, an ultrabook, a vehicle, a vehicle with an autonomous driving function, 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 device related to 5G services, or a device related to the field of the fourth industrial revolution.

[0043] For example, a UAV may be an aerial vehicle that is flown without humans aboard and is controlled by wireless signals.

[0044] For example, a VR device may include a device for realizing an object or background of a virtual world. For example, an AR device may include a device realized by connecting an object or background of a virtual world to an object or background of a real world. For example, an MR device may include a device realized by merging an object or background of a virtual world into an object or background of a real world. For example, a holographic device may include a device for realizing a 360-degree stereoscopic image by recording and reproducing stereoscopic information using a light interference phenomenon generated when two lasers meet, called holography.

[0045] For example, a public safety device may include an image relay device or an image device that may be wearable on a user's body.

[0046] For example, MTC devices and IoT devices may be devices that do not require direct human intervention or manipulation. For example, MTC devices and IoT devices may include smart meters, vending machines, thermometers, smart light bulbs, door locks, or various sensors.

[0047] For example, a medical device may be a device for the purpose of diagnosing, curing, alleviating, treating or preventing a disease. For example, a medical device may be a device for the purpose of diagnosing, curing, alleviating or correcting an injury or trauma. For example, a medical device may be a device for the purpose of inspecting, replacing or modifying a structure or function. For example, a medical device may 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.

[0048] For example, the safety device may be a device installed to prevent possible danger and maintain safety. For example, the safety device may be a camera, a closed-circuit TV (CCTV), a recorder or a black box.

[0049] For example, a fintech device may be a device that is capable of providing financial services such as mobile payments. For example, a fintech device may include a payment device or a point of sale (POS) system.

[0050] For example, weather / environmental devices may include devices for monitoring or predicting weather / environmental conditions.

[0051] The wireless devices 100a to 100f may be connected to the network 300 via the BS 200. AI technology may be applied to the wireless devices 100a to 100f, and the wireless devices 100a to 100f may be connected to the AI ​​server 400 via the network 300. The network 300 may be configured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR) network, and a super 5G network. Although the wireless devices 100a to 100f may communicate with each other via the BS 200 / network 300, the wireless devices 100a to 100f may perform direct communication (e.g., side link communication) with each other without passing through the BS 200 / network 300. For example, the vehicles 100b-1 and 100b-2 may perform direct communication (e.g., vehicle-to-vehicle (V2V) / vehicle-to-everything (V2X) communication). An IoT device (e.g., a sensor) may perform direct communication with other IoT devices (e.g., sensors) or other wireless devices 100a to 100f.

[0052] Wireless communication / connection 150a, 150b, and 150c may be established between wireless devices 100a to 100f and / or between wireless devices 100a to 100f and BS200 and / or between BS200. In this document, wireless communication / connection may be established through 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 may send / receive radio signals to each other through wireless communication / connection 150a, 150b, and 150c. For example, wireless communication / connection 150a, 150b, and 150c may send / receive signals through various physical channels. To this end, at least a portion of various configuration information configuration processes for sending / receiving radio signals, various signal processing processes (e.g., channel coding / decoding, modulation / demodulation, and resource mapping / demapping), and resource allocation processes may be performed based on various proposals of the present disclosure.

[0053] AI refers to the field that studies artificial intelligence or the methods that can create it, while machine learning refers to the field that defines the various problems solved in the field of AI and the methods to solve them. Machine learning is also defined as algorithms that increase the performance of a task through steady experience with the task.

[0054] A robot means a machine that automatically processes or operates a given task through its own capabilities. In particular, a robot that has the ability to recognize the environment and determine the actions to be performed by itself can be called an intelligent robot. According to the purpose or field of use, robots can be classified as industrial, medical, household, military, etc. Robots can perform various physical operations, such as moving robot joints using actuators or motors. Mobile robots also include driven wheels, brakes, propellers, etc., allowing them to travel on the ground or fly in the air.

[0055] Autonomous driving means the technology of self-driving, and autonomous vehicles mean vehicles that are driven without user control or with minimal user control. For example, autonomous driving may include maintaining a lane while in motion, automatically adjusting speed (e.g., adaptive cruise control), automatically driving along a set route, and automatically setting a route when a destination is set. Vehicles cover vehicles equipped with an internal combustion engine, hybrid vehicles equipped with an internal combustion engine and an electric motor, and electric vehicles equipped with an electric motor, and may include trains, motorcycles, etc. as well as cars. Autonomous vehicles may be considered robots with autonomous driving capabilities.

[0056] Extended reality is collectively referred to as VR, AR, and MR. VR technology provides real-world objects and backgrounds only through computer graphics (CG) images. AR technology provides virtual CG images on top of real object images. MR technology is a CG technology that combines virtual objects into the real world. MR technology is similar to AR technology in that they display real objects and virtual objects together. However, the difference is that in AR technology, virtual objects are used as a supplementary form of real objects, while in MR technology, virtual objects and real objects are used as equal individuals.

[0057] NR supports multiple parameter sets (and / or multiple subcarrier spacing (SCS)) to support various 5G services. For example, if the SCS is 15kHz, wide areas can be supported in traditional cellular bands, and if the SCS is 30kHz / 60kHz, dense cities, lower latency, and wider carrier bandwidths can be supported. If the SCS is 60kHz or higher, bandwidths greater than 24.25GHz can be supported to overcome phase noise.

[0058] The NR frequency band may be defined as two types of frequency ranges, namely, FR1 and FR2. The numerical values ​​of the frequency ranges may vary. For example, the two types of frequency ranges (FR1 and FR2) may be as shown in Table 1 below. For ease of explanation, in the frequency range used in the NR system, FR1 may mean "range below 6 GHz", FR2 may mean "range above 6 GHz" and may be referred to as millimeter wave (mmW).

[0059] [Table 1]

[0060] Frequency range specification Corresponding frequency range Subcarrier spacing FR1 450MHz-6000MHz 15, 30, 60kHz FR2 24250MHz-52600MHz 60, 120, 240kHz

[0061] As described above, the numerical value of the frequency range of the NR system may be changed. For example, as shown in Table 2 below, FR1 may include a frequency band of 410 MHz to 7125 MHz. That is, FR1 may include a frequency band of 6 GHz (or 5850 MHz, 5900 MHz, 5925 MHz, etc.) or higher. For example, a frequency band of 6 GHz (or 5850 MHz, 5900 MHz, 5925 MHz, etc.) or higher included in FR1 may include an unlicensed frequency band. The unlicensed frequency band may be used for various purposes, such as for communication of vehicles (e.g., autonomous driving).

[0062] [Table 2]

[0063] Frequency range specification Corresponding frequency range Subcarrier spacing FR1 410MHz-7125MHz 15, 30, 60kHz FR2 24250MHz-52600MHz 60, 120, 240kHz

[0064] Here, the radio communication technology implemented in the wireless device in the present disclosure may include narrowband Internet of Things (NB-IoT) technology 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, which may be implemented in specifications such as LTE Cat NB1 and / or LTE Cat NB2, and may not be limited to the above names. Additionally and / or alternatively, the radio communication technology implemented in the wireless device in the present disclosure may be based on LTE-M technology communication. For example, LTE-M technology may be an example of LPWAN technology and is referred to as 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 may not be limited to the above names. Additionally and / or alternatively, the radio communication technology implemented in the wireless device in the present disclosure may include at least one of ZigBee, Bluetooth, and / or LPWAN considering low power communication, and may not be limited to the above names. For example, ZigBee technology may generate a personal area network (PAN) associated with small / low power digital communication based on various specifications such as IEEE 802.15.4, and may be referred to as various names.

[0065] Figure 2 An example of a wireless device to which an implementation of the present disclosure is applied is shown.

[0066] exist Figure 2 In the embodiment, the first wireless device 100 and / or the second wireless device 200 may be implemented in various forms according to 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 BS200}, {wireless devices 100a to 100f and wireless devices 100a to 100f} and / or {BS200 and BS200}. The first wireless device 100 and / or the second wireless device 200 may be configured by various elements, devices / components and / or modules.

[0067] The first wireless device 100 may include at least one transceiver (eg, transceiver 106 ), at least one processing chip (eg, processing chip 101 ), and / or one or more antennas 108 .

[0068] The processing chip 101 may include at least one processor (eg, the processor 102 ) and at least one memory (eg, the memory 104 ). Additionally and / or alternatively, the memory 104 may be located outside the processing chip 101 .

[0069] The processor 102 may control the memory 104 and / or the transceiver 106, and may be adapted to implement the descriptions, functions, processes, suggestions, methods, and / or operational flow charts described in the present disclosure. For example, the processor 102 may process the information in the memory 104 to generate first information / signals, and then send a radio signal including the first information / signals through the transceiver 106. The processor 102 may receive a radio signal including second information / signals through the transceiver 106, and then store information obtained by processing the second information / signals in the memory 104.

[0070] The memory 104 may be operably 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 codes, commands, and / or command sets that, when executed by the processor 102, perform the descriptions, functions, processes, suggestions, methods, and / or operational flow charts disclosed in the present disclosure. For example, the firmware and / or software code 105 may implement instructions that, when executed by the processor 102, perform the descriptions, functions, processes, suggestions, methods, and / or operational flow charts disclosed in the present disclosure. For example, the firmware and / or software code 105 may control the processor 102 to execute one or more protocols. For example, the firmware and / or software code 105 may control the processor 102 to execute one or more layers of a radio interface protocol.

[0071] In this document, the processor 102 and the memory 104 may be part of a communication modem / circuit / chip designed to implement a RAT (e.g., LTE or NR). The transceiver 106 may be connected to the processor 102 and transmit and / or receive radio signals through one or more antennas 108. Each transceiver 106 may include a transmitter and / or a receiver. The transceiver 106 may be used interchangeably with a radio frequency (RF) unit. In the present disclosure, the first wireless device 100 may represent a communication modem / circuit / chip.

[0072] The second wireless device 200 may include at least one transceiver (eg, transceiver 206 ), at least one processing chip (eg, processing chip 201 ), and / or one or more antennas 208 .

[0073] The processing chip 201 may include at least one processor (eg, the processor 202 ) and at least one memory (eg, the memory 204 ). Additionally and / or alternatively, the memory 204 may be located outside the processing chip 201 .

[0074] The processor 202 may control the memory 204 and / or the transceiver 206, and may be adapted to implement the descriptions, functions, processes, suggestions, methods and / or operational flow charts described in the present disclosure. For example, the processor 202 may process the information in the memory 204 to generate third information / signals, and then send a radio signal including the third information / signals through the transceiver 206. The processor 202 may receive a radio signal including fourth information / signals through the transceiver 106, and then store the information obtained by processing the fourth information / signals in the memory 204.

[0075] The memory 204 may be operably 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 codes, commands, and / or command sets that, when executed by the processor 202, perform the descriptions, functions, processes, suggestions, methods, and / or operational flow charts disclosed in the present disclosure. For example, the firmware and / or software code 205 may implement instructions that, when executed by the processor 202, perform the descriptions, functions, processes, suggestions, methods, and / or operational flow charts disclosed in the present disclosure. For example, the firmware and / or software code 205 may control the processor 202 to execute one or more protocols. For example, the firmware and / or software code 205 may control the processor 202 to execute one or more layers of a radio interface protocol.

[0076] In this document, the processor 202 and the memory 204 may be part of a communication modem / circuit / chip designed to implement a RAT (e.g., LTE or NR). The transceiver 206 may be connected to the processor 202 and transmit and / or receive radio signals through one or more antennas 208. Each transceiver 206 may include a transmitter and / or a receiver. The transceiver 206 may be used interchangeably with an RF unit. In the present disclosure, the second wireless device 200 may represent a communication modem / circuit / chip.

[0077] In the following, the hardware elements of the wireless devices 100 and 200 will be described in more detail. One or more protocol layers may be implemented by one or more processors 102 and 202, but are not limited thereto. For example, the one or more processors 102 and 202 may implement one or more layers (e.g., functional layers such as a physical (PHY) layer, a medium 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). The 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 operational flow charts disclosed in the present disclosure. The one or more processors 102 and 202 may generate a signal (e.g., a baseband signal) including a PDU, SDU, message, control information, data, or information according to the description, function, procedure, suggestion, method, and / or operational flowchart disclosed in the present disclosure, and provide the generated signal to the one or more transceivers 106 and 206. The one or more processors 102 and 202 may receive a signal (e.g., a baseband signal) from the one or more transceivers 106 and 206, and obtain the PDU, SDU, message, control information, data, or information according to the description, function, procedure, suggestion, method, and / or operational flowchart disclosed in the present disclosure.

[0078] One or more processors 102 and 202 may be referred to as controllers, microcontrollers, microprocessors, or microcomputers. The 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 the one or more processors 102 and 202. For example, the one or more processors 102 and 202 may be configured by a collection of a communication control processor, an application processor (AP), an electronic control unit (ECU), a central processing unit (CPU), a graphics processing unit (GPU), and a memory control processor.

[0079] One or more memories 104, 204 may be associated with the 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 include random access memory (RAM), dynamic RAM (DRAM), read-only memory (ROM), erasable programmable ROM (EPROM), flash memory, volatile memory, non-volatile memory, hard drive, register, cache memory, computer-readable storage medium and / or a combination thereof. The one or more memories 104, 204 may be located inside and / or outside the one or more processors 102, 202. In addition, the one or more memories 104, 204 may be connected to the one or more processors 102, 202 via various technologies such as wired or wireless connections.

[0080] One or more transceivers 106, 206 may send user data, control information, wireless signals / channels, etc. mentioned in the description, features, processes, suggestions, methods, and / or operation flow charts disclosed herein to one or more other devices. The one or more transceivers 106, 206 may receive user data, control information, wireless signals / channels, etc. mentioned in the description, features, processes, suggestions, methods, and / or operation flow charts disclosed 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 send and receive wireless signals. For example, the one or more processors 102, 202 may control the one or more transceivers 106, 206 to send user data, control information, wireless signals, etc. to one or more other devices. In addition, 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.

[0081] 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 send and receive user data, control information, wireless signals / channels, etc. mentioned in the descriptions, features, processes, suggestions, methods, and / or operational flow charts 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).

[0082] The one or more transceivers 106, 206 may convert the received user data, control information, radio signal / channel, etc. from the RF band signal to the baseband signal so as to process the received user data, control information, radio signal / channel, etc. using the one or more processors 102, 202. The one or more transceivers 106, 206 may convert the processed user data, control information, radio signal / channel, etc. from the baseband signal to the RF band signal using the one or more processors 102, 202. To this end, the one or more transceivers 106, 206 may include an (analog) oscillator and / or a filter. For example, the one or more transceivers 106, 206 may up-convert the OFDM baseband signal into an OFDM signal via the (analog) oscillator and / or the filter under the control of the one or more processors 102, 202, and transmit the up-converted OFDM signal at a carrier frequency. The one or more transceivers 106 , 206 may receive an OFDM signal at a carrier frequency and, under the control of the one or more processors 102 , 202 , down-convert the OFDM signal via an (analog) oscillator and / or a filter to an OFDM baseband signal.

[0083] although Figure 2 1 , the wireless devices 100 and 200 may further include additional components. The additional components 140 may be configured differently depending on the type of the wireless devices 100 and 200. For example, the additional components 140 may include at least one of a power supply unit / battery, an input / output (I / O) device (e.g., an audio I / O port, a video I / O port), a drive device, and a computing device. The additional components 140 may be coupled to the one or more processors 102 and 202 via various technologies such as a wired or wireless connection.

[0084] In an implementation of the present disclosure, a UE may operate as a transmitting device in an uplink (UL) and as a receiving device in a downlink (DL). In an implementation of the present disclosure, a BS may operate as a receiving device in an UL and as a transmitting device in a DL. Hereinafter, for convenience of description, it is mainly assumed that the first wireless device 100 acts as a UE and the second wireless device 200 acts as a 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 an implementation of the present disclosure or control a transceiver 106 to perform UE behavior according to an implementation of the present 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 an implementation of the present disclosure or control a transceiver 206 to perform BS behavior according to an implementation of the present disclosure.

[0085] In this disclosure, a BS is also referred to as a Node B (NB), an eNode B (eNB), or a gNB.

[0086] Figure 3 An example of a UE to which an implementation of the present disclosure is applied is shown.

[0087] Figure 3 An example of a UE to which an implementation of the present disclosure is applied is shown.

[0088] Reference Figure 3 , UE 100 may correspond to Figure 2 A first wireless device 100 is provided.

[0089] 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 keypad 144 , a subscriber identity module (SIM) card 145 , a speaker 146 , and a microphone 147 .

[0090] The processor 102 may be adapted to implement the descriptions, functions, processes, suggestions, methods and / or operational flow charts disclosed in the present disclosure. The processor 102 may be adapted to control one or more other components of the UE 100 to implement the descriptions, functions, processes, suggestions, methods and / or operational flow charts disclosed in the present disclosure. The layers of the 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, a GPU, a modem (modulator and demodulator). Examples of the processor 102 can be found at MANUFACTURED BY SNAPDRAGON TMSeries processors, Manufactured by EXYNOS TM Series processors, A series of processors manufactured by Made by HELIO TM Series processors, ATOM manufactured TM series processors or corresponding to the next generation processors.

[0091] The memory 104 is operatively coupled to the processor 102 and stores various information to operate the processor 102. The memory 104 may include ROM, RAM, flash memory, memory card, storage medium, and / or other storage devices. When the embodiment is implemented in software, the techniques described herein may be implemented using modules (e.g., procedures, functions, etc.) that execute the descriptions, functions, processes, suggestions, methods, and / or operational flow charts disclosed in the present disclosure. The modules may be stored in the memory 104 and executed by the processor 102. The memory 104 may be implemented within the processor 102 or external to the processor 102, in which case these may be communicatively coupled to the processor 102 via various means known in the art.

[0092] The transceiver 106 is operatively connected to the processor 102 and transmits and / or receives radio signals. The transceiver 106 includes a transmitter and a receiver. The transceiver 106 may include a baseband circuit to process radio frequency signals. The transceiver 106 controls one or more antennas 108 to transmit and / or receive radio signals.

[0093] 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.

[0094] The display 143 outputs a result processed by the processor 102. The keypad 144 receives an input to be used by the processor 102. The keypad 144 may be displayed on the display 143.

[0095] The SIM card 145 is an integrated circuit designed to securely store the International Mobile Subscriber Identity (IMSI) number and its associated keys used to identify and authenticate subscribers on mobile telephony devices such as mobile phones and computers. Contact information can also be stored on many SIM cards.

[0096] 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.

[0097] Figure 4 is a block diagram of the next generation cellular network.

[0098] The 5G Core (5GC) may include various components, some of which are shown in FIG. 5 , such as an access and mobility management function (AMF) (410), a session management function (SMF) (420), a policy control function (PCF) (430), a user plane function (UPF) (440), an application function (AF) (450), a unified data management (UDM) (460), and a non-3rd Generation Partnership Project (3GPP) interworking function (N3IWF) (490).

[0099] UE 100 is connected to a data network via UPF 440 through a next generation radio access network (NG-RAN) including gNB 20.

[0100] Data services may also be provided to the UE 100 via an untrusted non-3GPP access, such as a wireless local area network (WLAN). To connect the non-3GPP access to the core network, a N3IWF 490 may be deployed.

[0101] The illustrated N3IWF 490 performs the function of managing interworking between non-3GPP access and 5G system. When the UE 100 is associated with a non-3GPP access (e.g., WiFi, also known as IEEE 801.11), the UE 100 can be associated with a 5G system via the N3IWF 490. The N3IWF 490 communicates with the AMF 410 for control signaling and communicates with the UPF 440 via the N3 interface for data transmission.

[0102] The AMF 410 shown can manage access and mobility in the 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 an idle state.

[0103] The UPF 440 shown is a gateway through which user data is sent and received. The UPF node 440 may perform all or part of the user plane functions of a serving gateway (S-GW) and a packet data network gateway (P-GW) of the fourth generation mobile communication.

[0104] The UPF 440 acts as a demarcation point between the Next Generation Radio Access Network (NG-RAN) and the core network, and is an element that maintains the 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. The UPF 440 can perform the function of processing PDUs. For mobility within the NG-RAN (a next-generation radio access network defined in 3GPP Release 15 and subsequent releases), the UPF can route packets. The UPF 440 can also serve as an anchor for mobility with other 3GPP networks (RANs defined before 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 (Enhanced Data Rates for Global Evolution) Radio Access Network). The UPF 440 may correspond to a termination point for a data interface to a data network.

[0105] The PCF 430 shown is a node that controls the operator's policy.

[0106] The illustrated AF 450 is a server for providing a plurality of services to the UE 100 .

[0107] The illustrated UDM 460 is a type of server that manages subscriber information, such as a Home Subscriber Server (HSS) in fourth generation mobile communications. The UDM 460 stores and manages subscriber information in a Unified Data Repository (UDR).

[0108] The illustrated SMF 420 may perform the function of assigning an Internet Protocol (IP) address to a UE. The SMF 420 may also control a Protocol Data Unit (PDU) session.

[0109] As a reference point, the reference numerals of AMF 410, SMF 420, PCF 430, UPF 440, AF 450, UDM 460, N3IWF 490, gNB 20, or UE 100 may be omitted herein.

[0110] The fifth generation of mobile communications supports multiple parameter sets or subcarrier spacing (SCS) to support various 5G services. For example, SCS of 15kHz supports wide-area coverage in traditional cellular bands; SCS of 30kHz / 60kHz supports dense cities, lower latency and wider carrier bandwidth; and SCS of 60kHz or higher supports bandwidth greater than 24.25GHz to overcome phase noise.

[0111] <Layer 2 Link Establishment>

[0112] Figure 5a and Figure 5b The Layer 2 link establishment procedure for unicast mode of ProSe direct communication via PC5 reference point is illustrated.

[0113] 1. The UE determines the destination layer 2 ID for signal reception for PC5 unicast link establishment.

[0114] 2. The ProSe application layer of UE-1 provides application information for PC5 unicast communication. The application information includes ProSe service information and the application layer ID of the UE. The application layer ID of the target UE may be included in the application information.

[0115] The ProSe application layer of UE-1 may provide ProSe application requirements for the unicast communication. UE-1 determines PC5 QoS parameters and PFI.

[0116] If UE-1 decides to reuse the existing PC5 unicast link, the UE triggers the Layer 2 Link Modification procedure.

[0117] 3. UE-1 initiates the unicast layer 2 link establishment process by sending a direct communication request message. The direct communication request message includes:

[0118] - Source user information: the application layer ID of the originating UE (ie, the application layer ID of UE-1).

[0119] - If the ProSe application layer provides the application layer ID of the target UE in step 2, the following information is included:

[0120] - Target user information: Application layer ID of the target UE (eg, application layer ID of UE-2).

[0121] -ProSe service information: Information about the ProSe identifier requesting Layer 2 link establishment.

[0122] - Security information: Information established for security

[0123] The target layer 2 ID can be a broadcast or unicast layer 2 ID. If a unicast layer 2 ID is used, the target user information must be included in the direct communication request message.

[0124] UE-1 sends a direct communication request message via PC5 by broadcast or unicast using the source layer 2ID and the target layer 2ID.

[0125] The default PC5 DRX configuration can be used for sending and receiving this message.

[0126] 4. Security with UE-1 is established as follows:

[0127] 4a. If the target user information is included in the direct communication request message, the target UE (eg, UE-2) responds by establishing security with UE-1.

[0128] 4b. If the target user information is not included in the direct communication request message, the UE that wants to use the ProSe service notified through the PC5 unicast link with UE- 1 responds by establishing security with UE- 1 .

[0129] If security protection is enabled, UE-1 sends the following information to the target UE:

[0130] - If using IP communication:

[0131] - IP address configuration: In case of IP communication, IP address configuration is required for the link, and the IP address configuration indicates one of the following values:

[0132] - "DHCPv4 Server": if the initiating UE supports only IPv4 address allocation mechanisms (e.g., acts as a DHCPv4 server), or

[0133] - "IPv6 router": if the originating UE supports only IPv6 address allocation mechanisms (eg, acts as an IPv6 router).

[0134] - "DHCPv4 server and IPv6 router", if the initiating UE supports both IPv4 and IPv6 address allocation mechanisms, or

[0135] - "Not support address allocation", if the initiating UE supports neither IPv4 nor IPv6 address allocation mechanism.

[0136] - Link-local IPv6 address: If UE-1 does not support the IPv6 IP address allocation mechanism, for example, the IP address configuration indicates "address allocation not supported", this is a locally formed link-local IPv6 address.

[0137] -QoS information: Information about PC5 QoS flows. For each PC5 QoS flow, it includes PFI and corresponding PC5 QoS parameters (e.g., PQI and conditional other parameters (e.g., MFBR / GFBR, etc.)), and optionally includes a ProSe identifier.

[0138] -Optional PC5 QoS rules.

[0139] The target layer 2 ID is set to the source layer 2 ID of the received direct communication request message.

[0140] Upon receiving the Security Setup Procedure message, UE-1 obtains the Layer 2 ID of the peer UE for future communication of signaling and data traffic on this unicast link.

[0141] 5. The target UE that has successfully established security with UE-1 sends a direct communication acceptance message to UE-1:

[0142] 5a. (Layer 2 Link Establishment Towards UE) If the target user information is included in the direct communication request message, if the application layer ID of the target UE (eg, UE-2) matches, UE-2 responds with a direct communication accept message.

[0143] 5b. (Layer 2 link establishment for ProSe service) If the target user information is not included in the direct communication request message, the UE interested in using the notified ProSe service responds to the request by sending a direct communication accept message (UE-2 and UE-4 in Figure 5).

[0144] The direct communication acceptance message contains:

[0145] -Source user information: the application layer ID of the UE that sends the direct communication acceptance message.

[0146] -QoS Information: Information about PC5 QoS flows. For each PC5 QoS flow, it contains the PFI requested by UE-1 and the corresponding PC5 QoS parameters (e.g., PQI and conditional other parameters (e.g., MFBR / GFBR, etc.)), and optionally the associated ProSe identifier.

[0147] -Optional PC5 QoS rules.

[0148] - If using IP communication:

[0149] -IP Address Configuration: For IP communication, this link requires an IP address configuration and indicates one of the following values:

[0150] - "DHCPv4 Server", if the target UE only supports IPv4 address allocation mechanisms, e.g., acting as a DHCPv4 server, or

[0151] - "IPv6 Router", if the target UE supports only IPv6 address allocation mechanisms, e.g., acts as an IPv6 router, or

[0152] - "DHCPv4 server and IPv6 router", if the target UE supports both IPv4 and IPv6 address allocation mechanisms, or

[0153] - "Address allocation not supported", if the target UE supports neither the IPv4 nor the IPv6 address allocation mechanism.

[0154] - Link-local IPv6 address: If the target UE does not support the IPv6 IP address allocation mechanism, e.g., "address allocation not supported" is indicated in the IP address configuration, and UE-1 includes a link-local IPv6 address in the direct communication request message, this is a locally formed link-local IPv6 address. The target UE shall include a non-conflicting link-local IPv6 address.

[0155] If both UEs (eg, the initiating UE and the target UE) are selected to use link-local IPv6 addresses, they must disable duplicate address detection.

[0156] If the initiating UE or the target UE indicates that it supports IPv6 routing, the address configuration procedure is performed after the layer 2 link is established and the link-local IPv6 address is ignored.

[0157] The ProSe layer of the UE that establishes the PC5 unicast link forwards the PC5 link identifier assigned to the unicast link and the PC5 unicast link related information to the AS layer. The PC5 unicast link related information includes layer 2 ID information (e.g., source layer 2 ID and target layer 2 ID). This allows the AS layer to maintain the PC5 link identifier together with the PC5 unicast link related information.

[0158] Two UEs may negotiate the PC5 DRX configuration at the AS layer, and may configure the PC5 DRX parameter values ​​for each source and target layer 2 ID pair at the AS layer.

[0159] 6. ProSe data is sent via a unicast link configured as follows:

[0160] The PC5 link identifier and PFI are provided to the AS layer together with the ProSe data.

[0161] Optionally, layer 2 ID information (eg, source layer 2 ID and destination layer 2 ID) is additionally provided to the AS layer.

[0162] UE- 1 sends ProSe data using a source Layer 2 ID (eg, the Layer 2 ID of UE- 1 for this unicast link) and a destination Layer 2 ID (eg, the Layer 2 ID of the peer UE for this unicast link).

[0163] Since the PC5 unicast link is bidirectional, the peer UE of UE-1 can send ProSe data to UE-1 through the unicast link with UE-1.

[0164] <Layer 2 Link Release>

[0165] Figure 6 The layer 2 release process through the PC5 reference point is shown.

[0166] 0. UE-1 and UE-2 have an established unicast link.

[0167] 1. UE-1 sends a Disconnect Request message to UE-2 to release the layer 2 link and delete all context data related to the layer 2 link. The Disconnect Request message includes security information.

[0168] 2. UE-2 receiving the Disconnect Request message responds with a Disconnect Response message and deletes all context data related to the layer 2 link. The Disconnect Response message includes security information.

[0169] The ProSe layer of each UE notifies the AS layer that the unicast link has been released. The ProSe layer indicates the released unicast link using the PC5 link identifier. This allows the AS layer to delete the context associated with the released unicast link.

[0170] After connecting to the 5G ProSe UE to network relay, the 5G ProSe remote UE continues to measure the signal strength of the 5G ProSe UE to network relay and PC5 unicast link for relay reselection.

[0171] <Problems to be Solved by the Disclosure of This Specification>

[0172] A method for supporting ProSe (Proximity-based Services) in 5GS is discussed. A method for receiving network connection services through UE-to-network relay is discussed. The UE-to-network relay can be a layer 2 UE-to-network relay or a layer 3 UE-to-network relay. For details, please refer to TS 23.304 V17.3.0.

[0173] The UE can receive connection services from the network in the following ways:

[0174] - Direct path (direct network communication): UE receives services directly from the network without going through the UE-to-network relay.

[0175] - Indirect path (indirect network communication): The UE receives services from the network indirectly through the UE-to-network relay.

[0176] Previously, the following scenarios were considered impossible:

[0177] - The UE receives network connection services through one or more layer 2 UE-to-network relays and simultaneously receives network connection services through a direct path.

[0178] -The UE receives network connection services via two or more Layer 2 UE-to-network relays.

[0179] Even when the UE receives network connection services through the layer 2 UE to network relay, the UE can perform RRC and NAS operations with the NG-RAN and the core network (via the layer 2 UE to network relay). In the above scenario, the UE has multiple RRC connections and NAS connections through 3GPP access (e.g., the Uu interface between the UE and the NG-RAN in the case of a direct path and the Uu interface between the layer 2 UE to network relay and the NG-RAN in the case of an indirect path), which was not allowed before.

[0180] A scenario in which a UE receives services from a network through multiple paths may be considered. Figures 7 to 10 A scenario is illustrated in which a UE receives services from a network via two paths (a direct path or an indirect path).

[0181] Figure 7 This example illustrates the case where both direct and indirect paths serve the UE via the same NG-RAN.

[0182] Figure 8 This example illustrates a scenario where two different indirect paths serve a UE via the same NG-RAN.

[0183] Fig. 9 This example illustrates a scenario where a UE is served by a direct path and an indirect path via two different NG-RANs.

[0184] Fig.10 This example illustrates a scenario where two different indirect paths serve the UE via two different NG-RANs.

[0185] exist Figures 7 to 10 In the present invention, it is assumed that for all paths (direct path or indirect path), the connection / communication between the UE and the network on the path is 3GPP access (e.g., Uu interface). For example, in the case of a direct path, the connection / communication between the UE and the network is performed through 3GPP access. And, in the case of an indirect path, the connection / communication between the UE to the network relay and the network is performed through 3GPP access.

[0186] Figures 7 to 10 Two paths are shown, but this can be extended to three or more paths.

[0187] exist Figures 7 to 10 In FIG. 4 , multiple paths are shown as being served by the same PLMN. However, multiple paths may be served by different PLMNs.

[0188] It may be assumed that a UE using multiple paths supports both non-roaming and roaming cases.

[0189] To improve reliability or data rate, there is discussion on using multi-path transmission, ie, one direct network communication path (direct path) and one indirect network communication path (indirect path) via a UE to a network relay.

[0190] Multipath support can improve communication stability and throughput. Multiple paths can be utilized simultaneously. Switching between multiple paths is also possible.

[0191] A terminal can connect to the same gNB using one direct path and one indirect path (Layer 2 UE to Network Relay or indirect path via another UE). Here, the solution used for Layer 2 UE to Network Relay can be reused for another UE.

[0192] In this specification, if no indirect path is specifically mentioned, it is assumed to be relayed via layer 2 UE to network.

[0193] If the remote UE uses multipath (e.g., multiple paths), both paths must be able to connect to the same base station. For example, the base station to which the remote UE's serving cell related to the direct path belongs and the base station to which the relay UE's serving cell belongs must be the same. Figure 7 In this case, the terminal and the network can communicate through multiple paths.

[0194] exist Figure 7 In the state of , if the relay UE receives service from another base station due to cell reselection or handover, the remote UE can no longer communicate through the multipath. Therefore, a method is needed to effectively support the remote UE using multipath to quickly release the PC5 connection with the relay UE and search for a new relay UE.

[0195] <Disclosure of this specification>

[0196] If cell reselection is performed for the relay UE, the relay UE may receive SIB1 from the new serving cell. The relay UE may then quickly transmit SIB1 to the remote UE to determine whether the remote UE can perform multipath transmission.

[0197] Alternatively, if a handover is performed for a relay UE, the base station (base station managing the direct path) may determine that multipath transmission is no longer possible for the remote UE. In this case, the base station (base station managing the direct path) may notify the remote UE of the suspension of multipath transmission via the direct path.

[0198] The method for supporting UE using multipath in this specification may be composed of a combination of one or more of the following operations / configurations / steps.

[0199] The method for supporting UE using multipath in this specification assumes that in the case of indirect network communication, network connection service is received through layer 2 UE to network relay. However, the method proposed in this specification can be extended to the case of providing indirect network communication service through layer 3 UE to network relay.

[0200] The path in this specification assumes that it is a path through NG-RAN (which can be only gNB, or can be both gNB and ng-eNB). However, the proposed method can also be extended to paths through non-3GPP access.

[0201] In the case of an indirect path, the contents of the present specification can be applied not only to a one-hop case (e.g., when a UE (or a remote UE) receives services from a network via one UE-to-network relay), but also to a multi-hop case (e.g., when a UE (or a remote UE) receives services from a network via multiple UE-to-network relays).

[0202] In this specification, a path may mean a communication path, a routing path, a connection path, etc.

[0203] In this specification, UE (User Equipment) and terminal are used interchangeably. In addition, UE to network relay, ProSe UE to network relay, relay, relay UE, UE-NW relay, 5G ProSe UE to network relay, 5G ProSe UE to NW relay, 5G ProSe UE to network relay UE, etc. can be used interchangeably. In addition, remote UE, 5G remote UE, etc. can be used interchangeably.

[0204] In this specification, it is assumed that each path has a different section between the UE and the NG-RAN, and it is assumed that the subsequent section (for example, the section between the NG-RAN and the 5G CN) does not differ between the paths. However, even if the path between the NG-RAN and the 5G CN (which is a control plane-related path and / or a data plane-related path) is different for each path, the contents of this specification can be applied.

[0205] The methods proposed in this specification may be interpreted as being performed or supported when the remote UE uses the relay UE for multipath purposes. The methods proposed in this specification may require one or more of the following assumptions / preconditions:

[0206] - The remote UE and the relay UE may explicitly or implicitly identify each other through relay discovery operations and / or PC5 unicast link formation / modification operations and / or message exchanges with the network that the relay UE supports an indirect path for the remote UE for multipath usage / purpose.

[0207] - The base station may explicitly or implicitly identify that the remote UE uses the indirect path for multipath usage / purpose.

[0208] For layer 2 UE to network relay related operations and procedures, refer to TS 23.304 V17.3.0, TS 38.300 V17.0.0, and TS 38.331 V17.0.0.

[0209] In this specification, the expressions 'a cell belongs to a base station' and 'a base station manages a cell' may be interpreted as having the same meaning. A base station may manage multiple cells.

[0210] The following describes a case where cell reselection for the relay UE is performed and a case where handover is performed.

[0211] I. According to the process of cell reselection

[0212] The following figures are created to illustrate specific examples of this specification. The names of specific devices or specific signals / messages / fields described in the figures are provided for illustrative purposes only, so the technical features of this specification are not limited to the specific names used in the following figures.

[0213] Fig.11 A flow chart according to an embodiment of the present specification is shown.

[0214] When performing cell reselection for the relay UE, the remote UE can check whether the direct path and the indirect path through the relay UE can be served by the same base station. Based on the result of the check, the remote UE can determine whether multipath transmission is possible.

[0215] Step 1: The PC5 connection between the remote UE and the relay UE may be continuously maintained.

[0216] The remote UE may be in RRC_IDLE, RRC_INACTIVE or RRC_CONNECTED state. The relay UE may be in RRC_IDLE or RRC_INACTIVE state.

[0217] If the remote UE can only use the direct path due to NAS message exchange (e.g., registration update, SMS send / receive, etc.) or signaling with the network, the remote UE may be in the RRC_CONNECTED state. At this point, the remote UE may continue to maintain the PC5 unicast link with the relay UE, but may not use the indirect path through the relay UE.

[0218] Step 2: The relay UE may reselect a serving cell (eg, serving cell).

[0219] Regarding UE cell reselection, UE operations may refer to TS23.304V17.3.0 and TS 38.331V17.0.0.

[0220] The base station to which the newly reselected serving cell of the relay UE belongs may be the same as or different from the base station to which the serving cell of the direct path for the remote UE belongs.

[0221] For example, the serving cell of the remote UE may be the first cell. The relay UE served by the second cell may select the third cell through cell reselection. Due to the cell reselection, the serving cell of the relay UE may be changed from the second cell to the third cell. At this time, the base station managing the first cell (the base station to which the first cell belongs) and the base station managing the third cell (the base station to which the third cell belongs) may be the same or different.

[0222] Step 3: The relay UE may receive SIB1 for the cell reselected in step 2.

[0223] For example, the relay UE may receive SIB1 from the base station to which the third cell belongs. SIB1 may include the ID of the third cell. The ID of the third cell may include the ID of the base station to which the third cell belongs.

[0224] Step 4: The relay UE may notify the remote UE that the serving cell has been reselected via a notification message side link.

[0225] At this time, the SIB1 information received in step 3 may be included and sent to the remote UE. The notification message sidelink may include the SIB1 information received in step 3.

[0226] Alternatively, the relay UE may send a Uu messaging sidelink including SIB1 to the remote UE immediately after notifying the remote UE through the notification message sidelink that the serving cell has been reselected.

[0227] Alternatively, the relay UE may include the cell identity of the cell reselected by the relay UE in the notification message side link.Alternatively, the relay UE may include the gNB-ID-Length (which indicates the length of the gNB ID in the cell identity, which is 36 bits long) in the notification message side link.

[0228] Alternatively, the relay UE may include in the notification message side link the gNB ID of the base station to which the cell reselected by the relay UE belongs.

[0229] If the base station or PLMN supports multipath operation, the base station or PLMN may also include gNB-ID-Length and / or gNB-ID in SIB1 (e.g., in PLMN-IdentityInfoList).

[0230] PLMNs capable of performing UE-to-network relay operations may each configure / provide the UE (remote UE and / or relay UE) with the gNB-ID-Length in use. The UE (remote UE and / or relay UE) may then extract the base station ID from the cell identity. Here, the PLMN may correspond to "PLMNs in which the UE is authorized for 5G ProSe Layer 3 and / or Layer 2 remote UE relay services" for relay UEs and "PLMNs in which the UE is authorized to use 5G ProSe Layer 2 UE-to-network relay for 5G ProSe Layer 2 remote UEs" for remote UEs (see clause 5.1.4.1 of TS 23.304 V17.3.0). This may apply throughout the specification.

[0231] For example, the relay UE may send a notification message side link to the remote UE. The notification message side link may include the SIB1 received from the third cell in step 3. Alternatively, the notification message side link may include the cell ID of the third cell. The above notification message side link may include the gNB ID of the base station to which the third cell belongs.

[0232] The notification message side link and the Uu message transmission side link are described below. The traditional notification message side link can be extended for the embodiments of the present disclosure.

[0233] The notification message sidelink may be used to send a notification message to a U2N (UE to Network) remote UE to which the U2N relay UE is connected.

[0234] The notification message sidelink may include NotificationMessageSidelink-r17. notificationMessageSidelink-r17 may include criticalExtensions(CHOICE{notificationMessageSidelink-r17, NotificationMessageSidelink-r17-IEs, criticalExtensionsFuture}). NotificationMessageSidelink-r17-IEs may include indicationType-r17(relayUE-Uu-RLF, relayUE-HO, relayUE-CellReselection, relayUE-Uu-RRC-Failure), lateNonCriticalExtension, nonCriticalExtension.

[0235] The Uu messaging sidelink may be used for sidelink transmission of paging messages and system information messages.

[0236] The Uu messaging sidelink may be sent from a L2 U2N relay UE to a L2 U2N remote UE.

[0237] The Uu message transfer side link may include UuMessageTransferSidelink-r17. UuMessageTransferSidelink-r17 may include criticalExtensions(CHOICE{uuMessageTransferSidelink-r17, UuMessageTransferSidelink-r17-IEs, criticalExtensionsFuture}). UumessageTransferSidelink-r17-IEs are sl-PagingDelivery-r17(octet string (including PagingRecord)), sl-SIB1-Delivery-r17(octet string (including SIB1)), sl-SystemInformationDelivery-r17(octet string (including SystemInformation)), which may include lateNonCriticalExtension(octet string) and nonCriticalExtension.

[0238] The Uu message delivery side link may include sl-PagingDelivery, sl-SIB1-Delivery, and sl-SystemInformationDelivery. In RRC_IDLE or RRC_INACTIVE state, sl-PagingDelivery may be used to deliver paging records related to L2 U2N remote UEs. In RRC_IDLE or RRC_INACTIVE state, sl-SIB1-Delivery may be used to deliver SIB1 to L2 U2N remote UEs. In RRC_IDLE or RRC_INACTIVE state, sl-SystemInformationDelivery may be used to deliver SIBs to L2 U2N remote UEs.

[0239] Step 5: The remote UE may receive the SIB1 of the serving cell for the direct path.

[0240] Step 5 can be performed before step 1 or between steps 1 and 4.

[0241] For example, the remote UE may receive SIB1 from the first cell.

[0242] Step 6: Based on the information received in steps 4 and 5, the remote UE may determine whether multi-path (direct path and indirect path via relay UE) transmission is possible.

[0243] The remote UE may compare i) the ID of the base station to which the serving cell of the direct path of the remote UE belongs and ii) the ID of the base station to which the serving cell of the relay UE belongs, and if the two IDs are the same, the remote UE may decide to continue to maintain the PC5 connection with the relay UE. For example, the remote UE may decide to continue to use / maintain the indirect path via the relay UE.

[0244] For example, the remote UE may determine whether the base station to which the first cell belongs and the base station to which the third cell belongs are the same base station based on the SIB1 received from the first cell and the SIB1 of the third cell received from the relay UE. If they are the same base station, the remote UE may decide to continue to maintain the PC5 connection with the relay UE. The remote UE may decide to continue to use / maintain the indirect path via the relay UE.

[0245] However, if the remote UE determines that the remote UE and the relay UE belong to different base stations, step 7 may be performed.

[0246] Step 7: The remote UE may release the PC5 connection and / or perform relay reselection.

[0247] The remote UE may perform one or more of the following actions:

[0248] Step 7-1: The remote UE may release the PC5 connection with the existing relay UE.

[0249] To this end, the AS (Access Stratum) layer of the remote UE may release the PC5-RRC connection with the relay UE, and then notify the upper layer (e.g., ProSe layer) of this (the PC5-RRC connection with the relay UE has been released). The upper layer of the remote UE may then send and receive a PC5-S message to the relay UE to release the PC5 connection.

[0250] Alternatively, the AS (Access Stratum) layer of the remote UE may provide information such as PC5 connection release, multipath unavailable, or indirect path unavailable to the upper layer. The upper layer of the remote UE may then send and receive a PC5-S message to the relay UE to release the PC5 connection. Afterwards, the PC5-RRC connection may also be released.

[0251] Alternatively, the PC5 connection may be released locally in the remote UE.

[0252] Step 7-2: The remote UE may discover / select a new relay UE to establish a PC5 unicast link. The base station to which the serving cell of the new relay UE belongs may be the same as the base station to which the serving cell of the remote UE belongs.

[0253] The remote UE can search / select a new relay UE whose serving cell is a cell belonging to the base station serving the remote UE (e.g., a relay UE in the cell of the same base station) through a direct path to establish a PC5 unicast link (e.g., establish an indirect path).

[0254] The remote UE may select a new relay UE for the new indirect path.

[0255] The remote UE may communicate with the base station via multiple paths using the new indirect path through the new relay UE and the existing direct path.

[0256] This operation may be performed when the remote UE deems it necessary to use the multipath (eg, when data transmission / reception through the multipath is required, when a request for the multipath is received from an upper layer, etc.).

[0257] Step 7-1 may be performed before step 7-2. Alternatively, step 7-2 may be performed before step 7-1.

[0258] The above process may also be applied when the relay UE is in the RRC_CONNECTED state. For example, when the handover process of the relay UE is in progress, the relay UE may receive a new SIB1 from the target node while sending a response to the RRC reconfiguration received from the source NG-RAN to the target node (i.e., RRC reconfiguration complete). As in step 4 above, the relay UE may notify the remote UE via a notification message side link that the handover of the relay UE has been completed. In addition, the relay UE may also send the SIB1 information received from the target node to the remote UE.

[0259] Instead of the relay UE providing the remote UE with the serving cell / base station information of the relay UE through the PC5-RRC message, such as including SIB1 in the notification message side link or delivering SIB1 immediately after the notification message side link, as in step 4 above, an additional parameter notification procedure may be performed (see clause 6.5.1.3 of TS23.304 V17.3.0). For example, the remote UE may request the relay UE to notify the relay UE of the cell change through an additional parameter notification request. For example, after the relay UE receives the additional parameter notification request from the remote UE, if the relay UE performs a cell reselection procedure or a handover procedure, the relay UE may send a message such as relay discovery additional information to the remote UE while delivering the new serving cell information (e.g., NCGI) of the relay UE. In addition, the relay discovery additional information message may include gNB-ID-Length (which indicates the length of the gNB ID in the cell identity, which is 36 bits long) and the NGCI. Alternatively, the relay discovery additional information message may include the gNB ID of the base station to which the serving cell of the relay UE belongs. For this purpose, the additional parameter announcement procedure and / or the relay discovery additional information message in clause 6.5.1.3 of TS 23.304 V17.3.0 may be extended.

[0260] Although described for the case where the serving cell of the relay UE changes, it can also be applied to the case where the serving cell changes as the remote UE performs cell reselection. As a result, when the serving cell for one or more of the remote UE and the relay UE changes, the remote UE can check whether the cell to which it belongs and the cell to which the relay UE belongs belong to the same base station. Therefore, if they do not belong to the same base station, it can be determined that multipath can no longer be used through the existing relay UE. If the remote UE is in the RRC_IDLE state, the above check (whether the cell to which the remote UE belongs and the cell to which the relay UE belongs belong to the same base station) may not be performed.

[0261] II. According to the switching process

[0262] Fig.12 A flow chart according to an embodiment of the present specification is shown.

[0263] If handover is performed for the relay UE while the remote UE performs multipath transmission through a direct path and an indirect path through the relay UE, the base station may determine whether the remote UE can continuously perform multipath transmission.

[0264] Step 0: The remote UE can send and receive data with NG-RAN#1 through both indirect and direct paths.

[0265] The relay UE and the remote UE may be in RRC_CONNECTED state and both may be connected to NG-RAN#1. Multipath communication may be performed between the remote UE and NG-RAN#1 through a direct path (a path between the remote UE and NG-RAN#1) and an indirect path (a path between the remote UE and NG-RAN#1 through the relay UE). The PC5 connection between the remote UE and the relay UE may be continuously maintained.

[0266] Step 1: The relay UE may perform measurement based on the measurement configuration received from NG-RAN#1 and report the measurement result to NG-RAN#1.

[0267] The measurement may be a measurement for a cell. The relay UE may perform measurement for a cell belonging to NG-RAN#1. The relay UE may measure the signal strength of a cell belonging to NG-RAN#1. The relay UE may perform measurement for a cell belonging to NG-RAN#2. The relay UE may measure the signal strength of a cell belonging to NG-RAN#2.

[0268] The relay UE can report the measurement results to NG-RAN#1.

[0269] Step 2: Based on the measurement results, NG-RAN#1 may decide to perform handover for the relay UE.

[0270] NG-RAN#1 can select the target node for handover. Fig.12 In the example, the target node can be a cell belonging to NG-RAN#2.

[0271] If the target node is a cell belonging to NG-RAN#1 (e.g., intra-NG-RAN handover), steps 3a and 3b may be omitted.

[0272] Step 3: NG-RAN#1 may initiate an Xn-based handover procedure to NG-RAN#2.

[0273] Alternatively, NG-RAN#1 can initiate an NG-based handover procedure to NG-RAN#2.

[0274] Step 3a: NG-RAN#1 may send a handover request to NG-RAN#2.

[0275] Step 3b: NG-RAN#2 may send a handover request Ack to NG-RAN#1.

[0276] The handover request Ack may include a handover command.

[0277] Step 4: NG-RAN#1 may send an RRC reconfiguration message to the remote UE via the direct path. The RRC reconfiguration may include information on multipath disconnection due to handover of the relay UE (Multipath disconnection due to relay HO).

[0278] NG-RAN#1 may know that it cannot send data to the remote UE via the indirect path through the relay UE due to the handover. Therefore, NG-RAN#1 may determine to stop multipath transmission to the remote UE. It may stop DL data transmission towards the indirect path through the relay UE.

[0279] NG-RAN#1 may send an RRC reconfiguration message to the remote UE via the direct path. The RRC reconfiguration message may include information indicating that multipath transmission is no longer possible as the relay UE switches to NG-RAN#2.

[0280] Alternatively, instead of NG-RAN#1 notifying the remote UE of the multipath transmission interruption directly via the direct path, NG-RAN#1 may notify the remote UE of the multipath transmission interruption via an indirect path through the relay UE. In order to notify the remote UE of the multipath transmission interruption via the indirect path, one of the following processes may be performed. In addition, multiple of the following processes may be performed together:

[0281] 1) A relay UE that has received an RRC reconfiguration (including a handover command) from NG-RAN#2 may forward the SIB1 received from NG-RAN#2 to the remote UE, such as Fig.11 as shown in step 4.

[0282] 1-1) Alternatively, NG-RAN#1 may include the authorized 5G ProSe in the handover request message. Then, NG-RAN#2 may confirm that the UE switched via the authorized 5G ProSe is capable of relay operation. Then, NG-RAN#2 may include the gNB-ID in the handover command message and send it to NG-RAN#1. NG-RAN#1 may forward the handover command to the relay UE. Then, when the relay UE notifies the remote UE that the relay UE has switched via the notification message side link, the relay UE may send the gNB ID of the base station to which the cell to which it has switched belongs to to the remote UE.

[0283] 1-2) If the base station or PLMN supports multipath operation, the base station or PLMN may include the gNB-ID-Length and / or gNB-ID in SIB1 (e.g., in PLMN-IdentityInfoList). PLMNs capable of performing UE-to-network relay operations may each set / supply the gNB-ID-Length they use to the UE (remote UE and / or relay UE). The UE (remote UE and / or relay UE) may then extract the base station ID from the cell identity. Here, the PLMN may correspond to "the PLMN to which the UE is authorized to relay services for 5G ProSe Layer 3 and / or Layer 2 remote UEs" in the case of a relay UE, and may correspond to "for 5G ProSe Layer 2 remote UEs, indicating that the UE is authorized to use the PLMN for 5G ProSe Layer 2 UE-to-network relay" in the case of a remote UE (see clause 5.1.4.1 of TS23.304V17.3.0).

[0284] 2) NG-RAN#1 may send an indication to the remote UE requesting to stop multipath transmission while sending the handover command message received from NG-RAN#2 in step 3 to the relay UE. The relay UE may then send the indication together with the notification message sidelink to the remote UE. Alternatively, the relay UE may release the PC5 connection with the remote UE. Regarding the PC5 connection release, step 5-1 described below may be applied.

[0285] 2-1) Alternatively, instead of requesting an indication to stop multipath transmission to the remote UE, NG-RAN#1 may send an indication to release the PC5 connection with the remote UE. Then, based on the indication to release the PC5 connection with the remote UE, the relay UE may release the PC5 connection with the remote UE. Regarding the release of the PC5 connection, step 5-1 described below may be applied.

[0286] 3) The handover command received by NG-RAN#1 from NG-RAN#2 may include the target cell ID information. NG-RAN#1 may include the target cell ID information in the notification message side link and send it to the remote UE. NG-RAN#1 may additionally include the gNB-ID-Length (which indicates the length of the gNB ID in the cell identity, which is 36 bits long) in the notification message side link.

[0287] 4) In step 3a, while sending an XnAP Handover Request or NGAP Handover Required message to NG-RAN#2, NG-RAN#1 may send it together with the ID of the remote UE and an indication requesting to stop multipath transmission for the remote UE. After receiving the message, NG-RAN#2 may include the indication requesting to stop multipath transmission for the remote UE and the ID of the remote UE received from NG-RAN#1 in a Handover Command message and send it to NG-RAN#1. Then, NG-RAN#1 may send a Handover Command message including the ID of the remote UE and the indication to the relay UE. Then, the relay UE may send the above indication to the remote UE via PC5. Alternatively, the relay UE may release the PC5 connection with the remote UE. Regarding the release of the PC5 connection, step 5-1 described below may be applied.

[0288] Step 5: The remote UE may release the PC5 connection and / or perform relay reselection.

[0289] The remote UE that received the RRC message in step 4 may stop UL data transmission using the indirect path through the relay UE. The remote UE may perform one or more of the following actions.

[0290] Step 5-1: The remote UE may release the PC5 connection with the existing relay UE.

[0291] To this end, the AS (Access Stratum) layer of the remote UE may release the PC5-RRC connection with the relay UE, and then notify the upper layer (e.g., ProSe layer) of this (the PC5-RRC connection with the relay UE has been released). The upper layer of the remote UE may then release the PC5 connection by sending a PC5-S message to the relay UE and receiving a PC5-S message from the relay UE.

[0292] Alternatively, the AS (Access Stratum) layer of the remote UE may provide information such as PC5 connection release, multipath unavailable, or indirect path unavailable to the upper layer. The upper layer of the remote UE may then release the PC5 connection by sending a PC5-S message to the relay UE and receiving a PC5-S message from the relay UE. Afterwards, the PC5-RRC connection may also be released.

[0293] Alternatively, the PC5 connection may be released locally in the remote UE.

[0294] Step 5-2: The remote UE may search / select a new relay UE to establish a PC5 unicast link. The base station to which the serving cell of the new relay UE belongs may be the same as the base station to which the serving cell of the remote UE belongs.

[0295] The remote UE can establish a PC5 unicast link (e.g., establish an indirect path) by searching / selecting a new relay UE (e.g., a relay UE in the cell of the same base station) via a direct path, wherein the serving cell of the new relay UE is a cell belonging to the base station serving the remote UE.

[0296] The remote UE may select a new relay UE for the new indirect path.

[0297] This operation may be performed when it is considered that the remote UE needs to use the multipath (eg, when data transmission / reception via the multipath is required, when a request for the multipath is received from an upper layer, etc.).

[0298] Step 5-1 may be performed before step 5-2. Alternatively, step 5-2 may be performed before step 5-1.

[0299] Step 6: The remaining steps of the Xn-based handover procedure may be performed according to clause 4.9.1.2 of TS 23.502 V17.4.0. Alternatively, the remaining steps of the NG-based handover procedure may be performed according to clause 4.9.1.3 of TS 23.502 V17.4.0.

[0300] A handover for the relay UE may be performed. The serving cell of the relay UE may be changed from a cell belonging to NG-RAN#1 to a cell belonging to NG-RAN#2 through the handover.

[0301] Steps 4 and 5 can be performed simultaneously with step 6.

[0302] According to the disclosure of this specification, when the mobility of the relay UE occurs due to the cell reselection or switching of the relay UE, the remote UE can quickly determine the new base station to which the relay UE is connected, and determine whether to maintain the PC5 connection with the relay UE. In addition, when the PC5 connection with the existing relay UE is released, a new relay UE capable of multipath transmission can be immediately selected, thereby realizing fast multipath transmission support for the remote UE.

[0303] Fig.13 The process of the remote UE for the disclosure of this specification is shown.

[0304] 1. The remote UE may perform communication with the first base station via a direct path without relaying of the relay UE.

[0305] 2. The remote UE may receive a first SIB (System Information Block) from the first base station.

[0306] 3. The remote UE may establish a first PC5 (device-to-device communication) link with the relay UE.

[0307] 4. The remote UE may perform communication with the first base station through an indirect path via the relay UE based on the first PC5 link.

[0308] 5. The remote UE may receive the notification message from the relay UE.

[0309] The notification message may include information that the relay UE has performed cell reselection.

[0310] The notification message may include a second SIB received by the relay UE from the second base station.

[0311] The second base station may manage the target cell for cell reselection.

[0312] 6. The remote UE may determine whether communication via a multipath including a direct path and an indirect path is possible based on the first SIB and the second SIB.

[0313] The steps to determine whether communication via multipath is possible are:

[0314] - the remote UE may determine that communication via multiple paths is possible based on the first base station and the second base station being identical, or

[0315] - The remote UE determines that communication via multipath is not possible based on the first base station and the second base station being different.

[0316] The first SIB may include an ID (identification) of the first base station.

[0317] The second SIB may include an ID of the second base station.

[0318] Based on determining that communication via the multipath is not possible, the remote UE may release the first PC5 link.

[0319] Based on determining that communication via multipath is not possible, the remote UE establishes a second PC5 link with the new relay UE.

[0320] The first SIB and the second SIB may be SIB1 (system information block type 1).

[0321] Fig.14 A process for a relay UE disclosed in this specification is shown.

[0322] 1. The relay UE may relay communications via an indirect path between the first base station and the remote UE.

[0323] The first base station may manage an existing serving cell of the relay UE.

[0324] 2. The relay UE may perform cell reselection from the existing serving cell to the target cell.

[0325] The second base station may manage the target cell.

[0326] 3. The relay UE may receive a SIB (System Information Block) from the second base station.

[0327] 4. The relay UE may send a notification message to the remote UE.

[0328] The multiple paths may include: i) a direct path between the remote UE and the first base station without relaying of the relay UE, and ii) an indirect path.

[0329] The notification message may include information that the relay UE has performed cell reselection.

[0330] The notification message may include the SIB.

[0331] The notification message may include an ID (identification) of the second base station.

[0332] The SIB may be SIB1 (System Information Block Type 1).

[0333] Fig.15 A process for a first base station disclosed in this specification is shown.

[0334] 1. A first base station may perform communication with a remote UE (User Equipment) via multiple paths.

[0335] The multiple paths may include: i) a direct path between the remote UE and the first base station without relaying of the relay UE, and ii) an indirect path between the remote UE and the first base station through relaying of the relay UE.

[0336] 2. The first base station may receive the cell measurement result from the relay UE.

[0337] 3. The first base station may determine handover to a target cell for the relay UE based on the result of the cell measurement.

[0338] The second base station may manage the target cell.

[0339] 4. The first base station may send a request for handover to the second base station based on the determination of handover.

[0340] 5. The first base station may receive a handover command from the second base station.

[0341] 6. The first base station may send an RRC (Radio Resource Control) reconfiguration message to the remote UE.

[0342] The RRC reconfiguration message may include information to release the multipath due to the handover.

[0343] The first base station may cease communicating via the indirect path.

[0344] The command may include an ID (identification) of the second base station.

[0345] The command may include an indication requesting that transmission via the multipath be stopped.

[0346] Hereinafter, an apparatus for performing communication according to some embodiments of the present specification will be described.

[0347] For example, the target V-SMF may include a processor, a transceiver, and a memory.

[0348] For example, a processor may be configured to be operatively coupled to a memory and a processor.

[0349] The processor can execute: performing communication with a first base station via a direct path without relaying by a relay UE; receiving a first SIB (system information block) from the first base station; establishing a first PC5 (device-to-device communication) link with the relay UE; based on the first PC5 link, performing communication with the first base station through an indirect path via the relay UE; receiving a notification message from the relay UE; wherein the notification message includes information that the relay UE has performed cell reselection, wherein the notification message includes a second SIB received by the relay UE from a second base station, wherein the second base station manages a target cell for the cell reselection, and determines whether communication via multiple paths including the direct path and the indirect path is possible based on the first SIB and the second SIB.

[0350] Hereinafter, a processor for providing communication according to some embodiments of the present specification will be described.

[0351] The processor is configured to: perform communication with a first base station via a direct path without relaying by a relay UE; receive a first SIB (system information block) from the first base station; establish a first PC5 (device-to-device communication) link with the relay UE; based on the first PC5 link, perform communication with the first base station through an indirect path via the relay UE; receive a notification message from the relay UE; wherein the notification message includes information that the relay UE has performed cell reselection, wherein the notification message includes a second SIB received by the relay UE from a second base station, wherein the second base station manages a target cell for the cell reselection, and determines whether communication via multiple paths including the direct path and the indirect path is possible based on the first SIB and the second SIB.

[0352] Hereinafter, a non-transitory computer-readable medium storing one or more instructions for providing a multicast service in wireless communication according to some embodiments of the present specification will be described.

[0353] According to some embodiments of the present disclosure, the technical features of the present disclosure may be directly implemented as hardware, software executed by a processor, or a combination of the two. For example, in wireless communications, the method performed by the wireless device may be implemented in hardware, software, firmware, or any combination thereof. For example, the software may reside in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or other storage medium.

[0354] Some examples of storage media are coupled to a processor so that the processor can read information from the storage media. Alternatively, the storage medium can be integrated into the processor. The processor and the storage medium can reside in an ASIC. For another example, the processor and the storage medium can reside as separate components.

[0355] Computer readable media may include tangible and non-volatile computer readable storage media.

[0356] For example, the non-volatile computer readable medium may include a random access memory (RAM), such as a synchronous dynamic random access memory (SDRAM), a read-only memory (ROM), or a 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 the non-volatile computer readable medium may also include a combination of the above.

[0357] Furthermore, the methods described herein may be implemented at least in part by a computer-readable communication medium that carries or carries code in the form of instructions or data structures and that can be accessed, read, and / or executed by a computer.

[0358] 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 may be executed by a processor of a base station.

[0359] The stored one or more instructions cause the processor to: perform communication with a first base station via a direct path without relaying by a relay UE; receive a first SIB (system information block) from the first base station; establish a first PC5 (device-to-device communication) link with the relay UE; based on the first PC5 link, perform communication with the first base station through an indirect path via the relay UE; receive a notification message from the relay UE; wherein the notification message includes information that the relay UE has performed cell reselection, wherein the notification message includes a second SIB received by the relay UE from a second base station, wherein the second base station manages a target cell for the cell reselection, and determines whether communication via multiple paths including the direct path and the indirect path is possible based on the first SIB and the second SIB.

[0360] This description can have various effects.

[0361] For example, when cell reselection or handover is performed for a relay UE, multipath communication can be efficiently performed by allowing the remote UE to recognize this fact.

[0362] The effects that can be obtained through the specific examples of this specification are not limited to the effects listed above. For example, there may be various technical effects that can be understood or derived from this specification by ordinary technicians in the relevant field. Therefore, the specific effects of this specification are not limited to those effects explicitly described herein, and may include various effects that can be understood or derived from the technical characteristics of this specification.

[0363] The claims described herein may be combined in various ways. For example, the technical features of the method claims of this specification may be combined and implemented as a device, and the technical features of the device claims of this specification may be combined and implemented as a method. In addition, the technical features of the method claims of this specification and the technical features of the device claims may be combined and implemented as a device, and the technical features of the method claims of this specification and the technical features of the device claims may be combined and implemented as a method. Other embodiments are within the scope of the appended claims.

Claims

1. A method for performing communication performed by a remote user equipment UE, the method comprising: performing communication with the first base station via a direct path without a relay of the relay UE; receiving a first system information block SIB from the first base station; Establishing a first device-to-device communication PC5 link with the relay UE; performing communication with the first base station via an indirect path via the relay UE based on the first PC5 link; receiving a notification message from the relay UE; The notification message includes information that the relay UE has performed cell reselection. The notification message includes a second SIB received by the relay UE from the second base station, The second base station manages the target cell for cell reselection. Based on the first SIB and the second SIB, it is determined whether communication via a multipath including the direct path and the indirect path is possible.

2. The method according to claim 1, in, The steps of determining whether communication via the multipath is possible are: determining that communication via the multipath is possible based on the first base station and the second base station being the same, or Based on the first base station and the second base station being different, it is determined that communication via the multipath is impossible.

3. The method according to claim 1 or 2, in, The first SIB includes an identification ID of the first base station, The second SIB includes the ID of the second base station.

4. The method according to any one of claims 1 to 3, further comprising: Based on determining that communication via the multipath is not possible, the first PC5 link is released.

5. The method according to any one of claims 1 to 4, further comprising: Based on determining that communication via the multipath is not possible, a second PC5 link is established with a new relay UE.

6. The method according to any one of claims 1 to 5, in, The first SIB and the second SIB are system information block type 1 SIB1.

7. A method for performing communication performed by a relay user equipment UE, the method comprising: relaying communications via an indirect path between the first base station and the remote UE; The first base station manages the existing serving cell of the relay UE. performing cell reselection from an existing serving cell to a target cell; The second base station manages the target cell. receiving a system information block SIB from the second base station; sending a notification message to the remote UE, The multipath includes: i) a direct path between the remote UE and the first base station without relaying by the relay UE, and ii) the indirect path, The notification message includes information that the relay UE has performed the cell reselection. The notification message includes the SIB.

8. The method according to claim 7, in, The step of sending the notification message is performed based on the remote UE performing communication via multiple paths.

9. The method according to claim 7 or 8, in, The notification message includes an identification ID of the second base station.

10. The method according to any one of claims 7 to 9, in, SIB is system information block type 1 SIB1.

11. A remote user equipment (UE) for performing communication, the remote UE comprising: Transceiver; as well as processor, The processor performs operations as a method according to any one of claims 1 to 6.

12. A method for performing communication performed by a first base station, the method comprising: performing communication with a remote user equipment UE via multiple paths; The multipath includes: i) a direct path between the remote UE and the first base station without relaying of the relay UE, and ii) an indirect path between the remote UE and the first base station through relaying of the relay UE, receiving a cell measurement result from the relay UE; Determine, based on a result of the cell measurement, a handover from the relay UE to a target cell; The second base station manages the target cell. Based on the determination of the handover, sending a request for the handover to the second base station; receiving a command for the handover from the second base station; sending a radio resource control (RRC) reconfiguration message to the remote UE, The RRC reconfiguration message includes information about releasing the multipath due to the switching.

13. The method according to claim 12, further comprising: Communications via the indirect path are stopped.

14. The method according to claim 12 or 13, in, The command includes an identification ID of the second base station.

15. The method according to any one of claims 12 to 14, in, The command includes an indication requesting to stop transmission via the multipath.

16. A first base station for performing communication, the first base station comprising: Transceiver; as well as processor, The processor performs operations as a method according to any one of claims 12 to 15.

17. A device in mobile communication, the device comprising: at least one processor; as well as at least one memory storing instructions and being operatively connected to the at least one processor, Wherein, based on the instruction, the at least one processor operates, and the instruction performs the operation of the method according to any one of claims 1 to 6.

18. A non-volatile computer-readable storage medium having recorded instructions, in, The instructions, upon being executed by one or more processors, cause the one or more processors to perform operations as the method according to any one of claims 1 to 6.

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