Method by which apparatus carries out communication in wireless communication system and apparatus therefor

Abstract

An apparatus according to various embodiments may form a first connection with a relay UE for a connection with a base station through the relay UE, and receive an RRC reconfiguration message from the base station through the first connection.

Description

A method for a device to perform communication in a wireless communication system and a device for the same

[0001] The present invention relates to a method for a terminal or base station to perform an operation related to handover in a wireless communication system, and to a device for doing so.

[0002] A wireless communication system is a multiple access system that supports communication with multiple users by sharing available system resources (e.g., bandwidth, transmission power, etc.). Examples of multiple access systems include CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), SC-FDMA (single carrier frequency division multiple access), and MC-FDMA (multi carrier frequency division multiple access) systems.

[0003] Sidelink (SL) refers to a communication method in which User Equipment (UE) establishes a direct link to directly exchange voice or data between terminals without passing through a Base Station (BS). SL is being considered as a solution to address the burden on base stations caused by rapidly increasing data traffic.

[0004] V2X (vehicle-to-everything) refers to a communication technology that exchanges information with other vehicles, pedestrians, and infrastructure-equipped objects through wired or wireless communication. V2X can be classified into four types: V2V (vehicle-to-vehicle), V2I (vehicle-to-infrastructure), V2N (vehicle-to-network), and V2P (vehicle-to-pedestrian). V2X communication can be provided through PC5 interfaces and / or Uu interfaces.

[0005] Meanwhile, as more communication devices require larger communication capacities, the need for improved mobile broadband communication compared to existing Radio Access Technology (RAT) is emerging. Accordingly, communication systems considering services or terminals sensitive to reliability and latency are being discussed; next-generation radio access technology that incorporates improved mobile broadband communication, Massive Machine Type Communication (MTC), and Ultra-Reliable and Low Latency Communication (URLC) can be referred to as new radio access technology (new RAT) or new radio (NR). Vehicle-to-everything (V2X) communication can also be supported in NR.

[0006] Figure 1 is a diagram illustrating a comparison between V2X communication based on RAT prior to NR and V2X communication based on NR.

[0007] Regarding V2X communication, prior to NR, RATs mainly discussed methods for providing safety services based on V2X messages such as BSM (Basic Safety Message), CAM (Cooperative Awareness Message), and DENM (Decentralized Environmental Notification Message). V2X messages can include location information, dynamic information, attribute information, etc. For example, a terminal can transmit a CAM of the periodic message type and / or a DENM of the event-triggered message type to another terminal.

[0008] For example, the CAM may include basic vehicle information such as dynamic state information of the vehicle, such as direction and speed, static data of the vehicle, such as dimensions, external lighting conditions, and route history. For example, a terminal may broadcast the CAM, and the latency of the CAM may be less than 100ms. For example, in the event of an unexpected situation such as a vehicle breakdown or accident, the terminal may generate a DENM and transmit it to other terminals. For example, all vehicles within the transmission range of the terminal may receive the CAM and / or DENM. In this case, the DENM may have a higher priority than the CAM.

[0009] Since then, regarding V2X communication, various V2X scenarios have been presented in NR. For example, various V2X scenarios may include vehicle platooning, advanced driving, extended sensors, remote driving, etc.

[0010] For example, based on vehicle platooning, vehicles can dynamically form groups and move together. For example, to perform platoon operations based on vehicle platooning, vehicles belonging to said group can receive periodic data from the lead vehicle. For example, vehicles belonging to said group can use said periodic data to reduce or increase the distance between vehicles.

[0011] For example, based on enhanced driving, vehicles can be semi-automated or fully automated. For example, each vehicle can adjust trajectories or maneuvers based on data acquired from local sensors of nearby vehicles and / or nearby logical entities. Additionally, for example, each vehicle can mutually share driving intentions with nearby vehicles.

[0012] For example, based on extended sensors, raw data or processed data or live video data acquired through local sensors can be exchanged between vehicles, logical entities, pedestrian terminals and / or V2X application servers. Thus, for example, a vehicle can perceive an environment that is enhanced compared to the environment it can detect using its own sensors.

[0013] For example, based on remote driving, a remote driver or V2X application can operate or control a remote vehicle for a person unable to drive or for a remote vehicle located in a dangerous environment. For example, in cases where the route is predictable, such as in public transportation, cloud computing-based driving can be used for the operation or control of the remote vehicle. Additionally, access to a cloud-based back-end service platform, for example, can be considered for remote driving.

[0014] Meanwhile, methods to specify service requirements for various V2X scenarios, such as vehicle platooning, enhanced driving, extended sensors, and remote driving, are being discussed in NR-based V2X communication.

[0015] The technical problem that the present invention aims to solve is to provide a method for performing handover more accurately and efficiently.

[0016] The technical problems are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which the present invention belongs from the description below.

[0017] A method by a remote UE (User Equipment) according to one aspect comprises the steps of: forming a first connection with a relay UE for a connection with a base station through a relay UE; and receiving an RRC (Radio Resource Control) reset message from the base station through the first connection, wherein the RRC reset message may include setting information related to a conditional handover that is triggered based on the reception of a notification message by the relay UE.

[0018] Alternatively, the method may include the step of receiving a notification message containing information regarding a cause value and a first cell ID (cell identifier) ​​related to the handover of the relay UE through the first connection, wherein the conditional handover may be triggered based on the fact that the setting information includes a cell ID identical to the first cell ID.

[0019] Alternatively, based on the conditional handover being triggered, the remote UE may transmit an RRC reset completion message toward the target base station through the first connection without performing a RACH (random access channel) procedure toward the target base station corresponding to the first cell ID.

[0020] Alternatively, the above notification message may be received based on the fact that the relay UE has completed a handover procedure or a conditional handover procedure to the target base station corresponding to the first cell ID.

[0021] Alternatively, the method may further include the step of receiving a notification message containing information regarding a cause value and a first cell ID (cell identifier) ​​related to the handover of the relay UE through the first connection, wherein the conditional handover may not be triggered based on the fact that the setting information does not include a cell ID identical to the first cell ID.

[0022] Alternatively, the method further includes the step of receiving a notification message containing information regarding a cause value and a first cell ID (cell identifier) ​​related to the handover of the relay UE through the first connection; and based on the fact that the setting information does not include a cell ID identical to the first cell ID, the remote UE can trigger a re-selection procedure of the relay UE without performing the conditional handover.

[0023] Alternatively, the above setting information may include information about at least one candidate target base station associated with the conditional handover.

[0024] Alternatively, the relay UE may be a UE associated with a UAV (Unmanned Aerial Vehicle) or a UE associated with an AAM (Advanced Air Mobility).

[0025] According to another aspect, at least one non-transient computer-readable recording medium comprises instructions for performing operations when executed by at least one processor, said operations include forming a first connection with said relay UE for connection with a base station through said relay UE (User Equipment); and receiving an RRC (Radio Resource Control) reset message from said base station through said first connection, said RRC reset message may include configuration information related to a conditional handover triggered based on the reception of a notification message from said relay UE.

[0026] According to another aspect, a remote UE (User Equipment) comprises an RF (Radio Frequency) transceiver; and at least one processor connected to the RF transceiver, wherein the at least one processor controls the RF transceiver to form a first connection with the relay UE for connection with a base station through the relay UE, and receives an RRC (Radio Resource Control) reset message from the base station through the first connection, and the RRC reset message may include configuration information related to a conditional handover that is triggered based on the reception of a notification message from the relay UE.

[0027] According to another aspect, a processing device controlling a remote UE (User Equipment) comprises at least one processor; and at least one memory connected to the at least one processor and storing instructions, wherein the instructions, based on execution by the at least one processor, cause the UE to: form a first connection with the relay UE for connection with the base station through the relay UE; and receive an RRC (Radio Resource Control) reset message from the base station through the first connection. The RRC reset message may include configuration information related to a conditional handover that is triggered based on the reception of a notification message by the relay UE.

[0028] A method by a relay UE (User Equipment) according to another aspect may include the steps of: forming a first connection with a remote UE for a U2N (UE-to-Network) relay; receiving a Radio Resource Control (RRC) reset message from a base station; performing a handover procedure for a target base station based on the RRC reset message; and transmitting a notification message through the first connection to trigger a conditional handover of the remote UE based on the completion of the handover procedure.

[0029] A base station according to another aspect comprises a Radio Frequency (RF) transceiver; and at least one processor connected to the RF transceiver, wherein the at least one processor controls the RF transceiver to form a first connection with a remote UE for a U2N (UE-to-Network) relay, receives a Radio Resource Control (RRC) reset message from the base station, performs a handover procedure for a target base station based on the RRC reset message, and transmits a notification message through the first connection to trigger a conditional handover of the remote UE based on the completion of the handover procedure.

[0030] According to one embodiment of the present invention, handover can be performed more accurately and efficiently in a wireless communication system. According to one example, service continuity of a remote UE can be effectively supported by ensuring the execution of a rapid handover procedure to the target gNB of the relay UE while maintaining a connection with the relay UE, even in an environment where frequent HO of the relay UE may be performed.

[0031] The effects obtainable from various embodiments are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description below.

[0032] The drawings attached to this specification are intended to provide an understanding of the present invention, to illustrate various embodiments of the invention, and to explain the principles of the invention together with the description in the specification.

[0033] Figure 1 is a diagram illustrating a comparison between V2X communication based on RAT prior to NR and V2X communication based on NR.

[0034] Figure 2 shows the structure of an LTE system.

[0035] Figure 3 shows the structure of the NR system.

[0036] Figure 4 shows the structure of a wireless frame of NR.

[0037] Figure 5 shows the slot structure of an NR frame.

[0038] FIG. 6 shows a communication structure that can be provided in a 6G system according to one embodiment of the present disclosure.

[0039] FIG. 7 shows an electromagnetic spectrum according to one embodiment of the present disclosure.

[0040] Figure 8 shows the radio protocol architecture for SL communication.

[0041] Figure 9 shows a terminal performing V2X or SL communication.

[0042] Figure 10 shows a resource unit for V2X or SL communication.

[0043] FIG. 11 shows an example of a BWP according to one embodiment of the present disclosure.

[0044] FIG. 12 illustrates a procedure in which a terminal performs V2X or SL communication according to a resource allocation mode, according to one embodiment of the present disclosure.

[0045] Figure 13 is a diagram illustrating the control plane procedure of an L2 U2N relay (UE-to-Network Relay).

[0046] FIGS. 14 to 18 are drawings for explaining the U2X system.

[0047] FIGS. 19 to 23 are drawings for explaining group mobility.

[0048] FIGS. 24 and 25 are diagrams illustrating how a relay UE and a remote UE perform a handover procedure.

[0049] FIG. 26 is a diagram illustrating how a remote UE performs a handover procedure while maintaining a connection with a relay UE.

[0050] Figure 27 is a diagram illustrating how a relay UE performs a handover procedure.

[0051] FIG. 28 illustrates a communication system to which the present invention is applied.

[0052] FIG. 29 illustrates a wireless device that can be applied to the present invention.

[0053] FIG. 30 illustrates another example of a wireless device to which the present invention applies. The wireless device may be implemented in various forms depending on the use-example / service.

[0054] FIG. 31 illustrates a vehicle or autonomous vehicle to which the present invention is applied.

[0055] A wireless communication system is a multiple access system that supports communication with multiple users by sharing available system resources (e.g., bandwidth, transmission power, etc.). Examples of multiple access systems include CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), SC-FDMA (single carrier frequency division multiple access), and MC-FDMA (multi carrier frequency division multiple access) systems.

[0056] Sidelink refers to a communication method in which User Equipment (UE) establishes a direct link to directly exchange voice or data between terminals without passing through a Base Station (BS). Sidelink is being considered as a solution to address the burden on base stations caused by rapidly increasing data traffic.

[0057] V2X (vehicle-to-everything) refers to a communication technology that exchanges information with other vehicles, pedestrians, and infrastructure-equipped objects through wired or wireless communication. V2X can be classified into four types: V2V (vehicle-to-vehicle), V2I (vehicle-to-infrastructure), V2N (vehicle-to-network), and V2P (vehicle-to-pedestrian). V2X communication can be provided through PC5 interfaces and / or Uu interfaces.

[0058] Meanwhile, as more communication devices require larger communication capacities, the need for improved mobile broadband communication compared to existing Radio Access Technology (RAT) is emerging. Accordingly, communication systems considering services or terminals sensitive to reliability and latency are being discussed; next-generation radio access technology that incorporates improved mobile broadband communication, Massive MTC, and URLLC (Ultra-Reliable and Low Latency Communication) can be referred to as new radio access technology (new RAT) or new radio (NR). Vehicle-to-everything (V2X) communication can also be supported in NR.

[0059] The following technologies can be used in various wireless communication systems such as CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), and SC-FDMA (single carrier frequency division multiple access). CDMA can be implemented using wireless technologies such as UTRA (universal terrestrial radio access) or CDMA2000. TDMA can be implemented using wireless technologies such as GSM (global system for mobile communications), GPRS (general packet radio service), and EDGE (enhanced data rates for GSM evolution). OFDMA can be implemented using wireless technologies such as IEEE (institute of electrical and electronics engineers) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, and E-UTRA (evolved UTRA). IEEE 802.16m is an evolution of IEEE 802.16e and provides backward compatibility with systems based on IEEE 802.16e. UTRA is part of UMTS (universal mobile telecommunications system). 3GPP (3rd generation partnership project) LTE (long term evolution) is part of E-UMTS (evolved UMTS) which uses E-UTRA (evolved-UMTS terrestrial radio access), employing OFDMA in the downlink and SC-FDMA in the uplink.LTE-A (advanced) is an evolution of 3GPP LTE.

[0060] 5G NR is a successor technology to LTE-A and is a new clean-slate type mobile communication system with characteristics such as high performance, low latency, and high availability. 5G NR can utilize all available spectrum resources, ranging from low frequency bands below 1 GHz to mid-frequency bands from 1 GHz to 10 GHz, and high frequency (millimeter wave) bands above 24 GHz.

[0061] For clarity of explanation, the description focuses on LTE-A or 5G NR, but the technical concept of the embodiment(s) is not limited thereto.

[0062] Figure 2 shows the structure of an applicable LTE system. This can be called an E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network), or an LTE (Long Term Evolution) / LTE-A system.

[0063] Referring to FIG. 2, the E-UTRAN includes a base station (20; Base Station, BS) that provides a control plane and a user plane to a terminal (10). The terminal (10) may be fixed or mobile and may be referred to by other terms such as MS (Mobile Station), UT (User Terminal), SS (Subscriber Station), MT (Mobile Terminal), or Wireless Device. The base station (20) refers to a fixed station that communicates with the terminal (10) and may be referred to by other terms such as eNB (evolved-NodeB), BTS (Base Transceiver System), or Access Point.

[0064] Base stations (20) can be connected to each other through an X2 interface. The base station (20) is connected to the EPC (Evolved Packet Core, 30) through the S1 interface, more specifically to the MME (Mobility Management Entity) through the S1-MME and to the S-GW (Serving Gateway) through the S1-U.

[0065] The EPC (30) consists of an MME, an S-GW, and a P-GW (Packet Data Network-Gateway). The MME holds information regarding the terminal's connection information or capabilities, and this information is primarily used for managing the terminal's mobility. The S-GW is a gateway with an E-UTRAN as its endpoint, and the P-GW is a gateway with a PDN as its endpoint.

[0066] The layers of the Radio Interface Protocol between a terminal and a network can be classified into L1 (Layer 1), L2 (Layer 2), and L3 (Layer 3) based on the lower three layers of the Open System Interconnection (OSI) model, which is widely known in communication systems. Among these, the Physical Layer, belonging to Layer 1, provides Information Transfer Services using a physical channel, while the Radio Resource Control (RRC) layer, located at Layer 3, performs the role of controlling radio resources between the terminal and the network. To this end, the RRC layer exchanges RRC messages between the terminal and the base station.

[0067] Figure 3 shows the structure of the NR system.

[0068] Referring to FIG. 3, the NG-RAN may include gNBs and / or eNBs that provide user plane and control plane protocol termination to terminals. FIG. 7 illustrates a case where only gNBs are included. The gNBs and eNBs are connected to each other via Xn interfaces. The gNBs and eNBs are connected to the 5G Core Network (5GC) via NG interfaces. More specifically, they are connected to the access and mobility management function (AMF) via NG-C interfaces and to the user plane function (UPF) via NG-U interfaces.

[0069] Figure 4 shows the structure of a wireless frame of NR.

[0070] Referring to FIG. 4, radio frames can be used for uplink and downlink transmission in NR. The radio frame has a length of 10 ms and can be defined as two 5 ms half-frames (HF). A half-frame may contain five 1 ms subframes (SF). A subframe may be divided into one or more slots, and the number of slots within a subframe may be determined by the subcarrier spacing (SCS). Each slot may contain 12 or 14 OFDM(A) symbols according to the cyclic prefix (CP).

[0071] When normal CP is used, each slot may contain 14 symbols. When extended CP is used, each slot may contain 12 symbols. Here, the symbols may include OFDM symbols (or CP-OFDM symbols) and SC-FDMA (Single Carrier - FDMA) symbols (or DFT-s-OFDM (Discrete Fourier Transform-spread-OFDM) symbols).

[0072] Table 1 below shows the number of symbols per slot ((N) according to the SCS setting (u) when normal CP is used. slot symb ), number of slots per frame((N frame,u slot ) and the number of slots per subframe((N subframe,u slot ) exemplifies.

[0073] SCS (15*2 u )N slot symb N frame,u slot N subframe,u slot 15KHz (u=0)1410130KHz (u=1)1420260KHz (u=2)14404120KHz (u=3)14808240KHz (u=4)1416016

[0074] Table 2 shows the number of symbols per slot, the number of slots per frame, and the number of slots per subframe according to the SCS when an extended CP is used.

[0075] SCS (15*2 u )N slot symb N frame,u slot N subframe,u slot 60KHz (u=2)12404

[0076] In an NR system, the OFDM(A) numerology (e.g., SCS, CP length, etc.) can be configured differently among multiple cells that are merged into a single terminal. Accordingly, the (absolute time) interval of a time resource (e.g., subframe, slot, or TTI) (collectively referred to as TU (Time Unit) for convenience) composed of the same number of symbols can be configured differently among the merged cells.

[0077] In NR, multiple numerologies or SCSs may be supported to support various 5G services. For example, if the SCS is 15 kHz, a wide area in traditional cellular bands may be supported, and if the SCS is 30 kHz / 60 kHz, dense-urban, lower latency, and wider carrier bandwidth may be supported. If the SCS is 60 kHz or higher, a bandwidth greater than 24.25 GHz may be supported to overcome phase noise.

[0078] The NR frequency band can be defined by two types of frequency ranges. The two types of frequency ranges may be FR1 and FR2. The numerical values ​​of the frequency ranges may change, for example, as shown in Table 3 below. Among the frequency ranges used in an NR system, FR1 may mean "sub 6GHz range" and FR2 may mean "above 6GHz range" and may be referred to as millimeter wave (mmW).

[0079] Frequency Range designationCorresponding frequency rangeSubcarrier Spacing (SCS)FR1450MHz - 6000MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0080] As described above, the numerical value of the frequency range of the NR system may change. For example, FR1 may include a band of 410 MHz to 7125 MHz as shown in Table 4 below. That is, FR1 may include a frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or higher. For example, the frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or higher included within FR1 may include an unlicensed band. The unlicensed band may be used for various purposes, for example, for communication for vehicles (e.g., autonomous driving).

[0081] Frequency Range designationCorresponding frequency rangeSubcarrier Spacing (SCS)FR1410MHz - 7125MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0082] Figure 5 shows the slot structure of an NR frame.

[0083] Referring to FIG. 5, a slot contains multiple symbols in the time domain. For example, in the case of a normal CP, one slot may contain 14 symbols, but in the case of an extended CP, one slot may contain 12 symbols. Alternatively, in the case of a normal CP, one slot may contain 7 symbols, but in the case of an extended CP, one slot may contain 6 symbols.

[0084] A carrier includes multiple subcarriers in the frequency domain. A Resource Block (RB) can be defined as multiple (e.g., 12) consecutive subcarriers in the frequency domain. A Bandwidth Part (BWP) can be defined as multiple consecutive (P)RBs ((Physical) Resource Blocks) in the frequency domain and can correspond to a single numerology (e.g., SCS, CP length, etc.). A carrier can include up to N (e.g., 5) BWPs. Data communication can be performed through the active BWPs. Each element can be referred to as a Resource Element (RE) in a resource grid and can be mapped to a single complex symbol.

[0085] Meanwhile, a wireless interface between terminals or a wireless interface between a terminal and a network may be composed of L1, L2, and L3 layers. In various embodiments of the present disclosure, L1 layer may refer to the physical layer. Additionally, for example, L2 layer may refer to at least one of the MAC layer, RLC layer, PDCP layer, and SDAP layer. Additionally, for example, L3 layer may refer to the RRC layer.

[0086] FIG. 6 illustrates a communication structure that can be provided in a 6G system according to one embodiment of the present disclosure. The embodiment of FIG. 6 can be combined with various embodiments of the present disclosure.

[0087] New network characteristics in 6G may be as follows.

[0088] - Satellite Integrated Network

[0089] - Connected Intelligence: Unlike previous generations of wireless communication systems, 6G is innovative and will update wireless evolution from "connected things" to "connected intelligence." AI can be applied at each stage of the communication process (or at each step of the signal processing described below).

[0090] - Seamless integration of wireless information and energy transfer

[0091] - Ubiquitous Super 3D Connectivity: Connectivity to the network and core network functions of drones and very low Earth orbit satellites will create Super 3D connectivity in 6G ubiquitous.

[0092] Some general requirements regarding the new network characteristics of 6G mentioned above may be as follows.

[0093] - Small cell networks

[0094] - Ultra-dense heterogeneous network

[0095] - High-capacity backhaul

[0096] - Radar technology integrated with mobile technology: High-precision localization (or location-based services) through communication is one of the functions of 6G wireless communication systems. Therefore, radar systems will be integrated with 6G networks.

[0097] - Softwarization and virtualization

[0098] The core implementation technologies of the 6G system are described below.

[0099] - Artificial Intelligence: Introducing AI into communications can streamline and enhance real-time data transmission. AI can determine how complex target tasks are performed using numerous analyses. In other words, AI can increase efficiency and reduce processing latency. Time-consuming tasks such as handover, network selection, and resource scheduling can be performed instantly using AI. AI can also play a significant role in M2M, machine-to-human, and human-to-machine communication. Furthermore, AI can enable rapid communication in Brain-Computer Interfaces (BCI). AI-based communication systems can be supported by metamaterials, intelligent structures, intelligent networks, intelligent devices, intelligent cognitive radios, self-sustaining wireless networks, and machine learning.

[0100] - THz Communication: Data transmission rates can be increased by expanding bandwidth. This can be achieved by using sub-THz communication with wide bandwidth and applying advanced large-scale MIMO technology. THz waves, also known as sub-millimeter radiation, generally refer to a frequency band between 0.1 THz and 10 THz with corresponding wavelengths ranging from 0.03 mm to 3 mm. The 100 GHz-300 GHz band range (Sub-THz band) is considered the primary portion of the THz band for cellular communication. Adding the Sub-THz band to the mmWave band increases 6G cellular communication capacity. Among the defined THz bands, the 300 GHz-3 THz band is located in the far-infrared (IR) frequency band. Although the 300 GHz-3 THz band is part of the optical band, it lies at the boundary of the optical band and immediately following the RF band. Therefore, this 300 GHz-3 THz band exhibits similarities to RF.

[0101] FIG. 7 illustrates an electromagnetic spectrum according to one embodiment of the present disclosure. The embodiment of FIG. 7 may be combined with various embodiments of the present disclosure. Key characteristics of THz communication include (i) a widely available bandwidth to support very high data transmission rates, and (ii) high path loss occurring at high frequencies (highly directional antennas are indispensable). The narrow beam width generated by highly directional antennas reduces interference. The small wavelength of THz signals allows a much larger number of antenna elements to be integrated into devices and BSs operating in this band. This enables the use of advanced adaptive array techniques that can overcome range limitations.

[0102] - Large-scale MIMO technology

[0103] - Hologram beamforming (HBF)

[0104] - Optical wireless technology

[0105] - Free Space Optical Transmission Backhaul Network (FSO backhaul network)

[0106] - Quantum communication

[0107] - Cell-free communication

[0108] - Integration of wireless information and power transmission

[0109] - Integration of wireless communication and sensing

[0110] - Integrated access and backhaul network

[0111] - Big data analysis

[0112] - Reconfigurable intelligent metasurface

[0113] - Metaverse

[0114] - blockchain

[0115] - Unmanned Aerial Vehicle (UAV): UAVs or drones will be a critical element in 6G wireless communication. In most cases, high-speed data wireless connectivity can be provided using UAV technology. Base station (BS) entities can be installed on UAVs to provide cellular connectivity. UAVs can possess specific features not found in fixed BS infrastructure, such as easy deployment, robust line-of-sight links, and controlled degrees of freedom for mobility. During emergencies, such as natural disasters, the deployment of ground communication infrastructure is not economically feasible, and sometimes services cannot be provided in volatile environments. UAVs can easily handle these situations. UAVs will become a new paradigm in the field of wireless communication. This technology facilitates the three fundamental requirements of wireless networks: eMBB, URLLC, and mMTC. UAVs can also support various purposes, such as enhancing network connectivity, fire detection, disaster emergency services, security and surveillance, pollution monitoring, parking monitoring, and accident monitoring. Therefore, UAV technology is recognized as one of the most critical technologies for 6G communication.

[0116] - Autonomous Driving (Self-Driving): V2X (Vehicle to Everything), a core element in building autonomous driving infrastructure, refers to technologies that enable vehicles to communicate and share with various elements on the road for autonomous driving, such as wireless communication between vehicles (Vehicle to Vehicle, V2V) and between vehicles and infrastructure (Vehicle to Infrastructure, V2I). Fast transmission speeds and low-latency technologies are essential to maximize autonomous driving performance and ensure high safety. Furthermore, future autonomous driving may go beyond merely delivering warning or guidance messages to the driver to actively intervene in vehicle operation and directly control the vehicle in dangerous situations. Since the amount of information to be transmitted and received may become massive for this purpose, it is expected that 6G will be able to maximize autonomous driving through faster transmission speeds and lower latency compared to 5G.

[0117] FIG. 8 illustrates a radio protocol architecture for SL communication. Specifically, FIG. 8 (a) shows the user plane protocol stack of NR, and FIG. 8 (b) shows the control plane protocol stack of NR.

[0118] The Sidelink Synchronization Signal (SLSS) and synchronization information are described below.

[0119] SLSS is an SL-specific sequence that may include PSSS (Primary Sidelink Synchronization Signal) and SSSS (Secondary Sidelink Synchronization Signal). The PSSS may be referred to as S-PSS (Sidelink Primary Synchronization Signal), and the SSSS may be referred to as S-SSS (Sidelink Secondary Synchronization Signal). For example, length-127 M-sequences may be used for S-PSS, and length-127 Gold sequences may be used for S-SSS. For example, a terminal may use S-PSS to detect a primary signal and obtain synchronization. For example, a terminal may use S-PSS and S-SSSS to obtain detailed synchronization and detect a synchronization signal ID.

[0120] PSBCH (Physical Sidelink Broadcast Channel) may be a (broadcast) channel through which basic (system) information that a terminal must know first is transmitted before transmitting or receiving SL signals. For example, the basic information may include information related to SLSS, Duplex Mode (DM), TDD UL / DL (Time Division Duplex Uplink / Downlink) configuration, information related to resource pools, types of applications related to SLSS, subframe offsets, broadcast information, etc. For example, to evaluate PSBCH performance, in NR V2X, the payload size of PSBCH may be 56 bits, including a 24-bit CRC.

[0121] S-PSS, S-SSS, and PSBCH may be included in a block format that supports periodic transmission (e.g., SL SS (Synchronization Signal) / PSBCH block, hereinafter S-SSB (Sidelink-Synchronization Signal Block)). The S-SSB may have the same numerology (i.e., SCS and CP lengths) as the PSCCH (Physical Sidelink Control Channel) / PSSCH (Physical Sidelink Shared Channel) within the carrier, and the transmission bandwidth may be within a (pre-)set SL BWP (Sidelink BWP). For example, the bandwidth of the S-SSB may be 11 RB (Resource Block). For example, the PSBCH may span 11 RB. Additionally, the frequency position of the S-SSB may be (pre-)set. Therefore, the terminal does not need to perform hypothesis detection at the frequency to discover the S-SSB in the carrier.

[0122] Meanwhile, in an NR SL system, multiple numerologies having different SCS and / or CP lengths may be supported. In this case, as the SCS increases, the length of the time resource for the transmitting terminal to transmit S-SSBs may decrease. Consequently, the coverage of S-SSBs may decrease. Therefore, to ensure S-SSB coverage, the transmitting terminal may transmit one or more S-SSBs to the receiving terminal within a single S-SSB transmission cycle according to the SCS. For example, the number of S-SSBs transmitted by the transmitting terminal to the receiving terminal within a single S-SSB transmission cycle may be pre-configured or configured for the transmitting terminal. For example, the S-SSB transmission cycle may be 160ms. For example, an S-SSB transmission cycle of 160ms may be supported for all SCSs.

[0123] For example, if the SCS is 15 kHz at FR1, the transmitting terminal may transmit one or two S-SSBs to the receiving terminal within one S-SSB transmission cycle. For example, if the SCS is 30 kHz at FR1, the transmitting terminal may transmit one or two S-SSBs to the receiving terminal within one S-SSB transmission cycle. For example, if the SCS is 60 kHz at FR1, the transmitting terminal may transmit one, two, or four S-SSBs to the receiving terminal within one S-SSB transmission cycle.

[0124] For example, if the SCS is 60 kHz at FR2, the transmitting terminal can transmit 1, 2, 4, 8, 16, or 32 S-SSBs to the receiving terminal within one S-SSB transmission cycle. For example, if the SCS is 120 kHz at FR2, the transmitting terminal can transmit 1, 2, 4, 8, 16, 32, or 64 S-SSBs to the receiving terminal within one S-SSB transmission cycle.

[0125] Meanwhile, when the SCS is 60 kHz, two types of CP may be supported. Additionally, depending on the CP type, the structure of the S-SSB transmitted by the transmitting terminal to the receiving terminal may differ. For example, the CP type may be Normal CP (NCP) or Extended CP (ECP). Specifically, for example, if the CP type is NCP, the number of symbols mapping PSBCH within the S-SSB transmitted by the transmitting terminal may be 9 or 8. On the other hand, for example, if the CP type is ECP, the number of symbols mapping PSBCH within the S-SSB transmitted by the transmitting terminal may be 7 or 6. For example, PSBCH may be mapped to the first symbol within the S-SSB transmitted by the transmitting terminal. For example, the receiving terminal receiving the S-SSB may perform Automatic Gain Control (AGC) operation during the first symbol interval of the S-SSB.

[0126] Figure 9 shows a terminal performing V2X or SL communication.

[0127] Referring to FIG. 9, in V2X or SL communication, the term terminal may primarily refer to a user's terminal. However, if network equipment such as a base station transmits and receives signals according to the communication method between terminals, the base station may also be considered a type of terminal. For example, terminal 1 may be a first device (100), and terminal 2 may be a second device (200).

[0128] For example, terminal 1 can select a resource unit corresponding to a specific resource within a resource pool, which represents a set of resources. Then, terminal 1 can transmit an SL signal using the said resource unit. For example, terminal 2, which is a receiving terminal, can be configured with a resource pool in which terminal 1 can transmit a signal, and can detect terminal 1's signal within said resource pool.

[0129] Here, if terminal 1 is within the connection range of the base station, the base station may inform terminal 1 of the resource pool. On the other hand, if terminal 1 is outside the connection range of the base station, another terminal may inform terminal 1 of the resource pool, or terminal 1 may use a pre-configured resource pool.

[0130] Generally, a resource pool can be composed of multiple resource units, and each terminal can select one or more resource units to use for its SL signal transmission.

[0131] Figure 10 shows a resource unit for V2X or SL communication.

[0132] Referring to FIG. 10, the total frequency resources of the resource pool can be divided into NF units, and the total time resources of the resource pool can be divided into NT units. Thus, a total of NF * NT resource units can be defined within the resource pool. FIG. 10 illustrates an example where the resource pool is repeated in a period of NT subframes.

[0133] As shown in FIG. 10, a single resource unit (e.g., Unit #0) may appear repeatedly over time. Alternatively, to obtain diversity effects in the time or frequency dimension, the index of the physical resource unit to which a single logical resource unit is mapped may change in a predetermined pattern over time. In this structure of resource units, a resource pool may refer to a set of resource units that a terminal intending to transmit an SL signal can use for transmission.

[0134] Resource pools can be subdivided into several types. For example, depending on the content of the SL signals transmitted from each resource pool, resource pools can be classified as follows.

[0135] (1) A Scheduling Assignment (SA) may be a signal containing information such as the location of the resource used by the transmitting terminal for transmission of the SL data channel, the Modulation and Coding Scheme (MCS) or Multiple Input Multiple Output (MIMO) transmission method required for demodulation of the data channel, and Timing Advance (TA). The SA may also be multiplexed and transmitted together with the SL data on the same resource unit, in which case the SA resource pool may refer to a resource pool in which the SA is multiplexed and transmitted together with the SL data. The SA may also be called the SL control channel.

[0136] (2) A Physical Sidelink Shared Channel (PSSCH) may be a resource pool used by a transmitting terminal to transmit user data. If SA is multiplexed and transmitted along with SL data on the same resource unit, only the form of the SL data channel excluding SA information can be transmitted from the resource pool for the SL data channel. In other words, REs (Resource Elements) that were used to transmit SA information on individual resource units within the SA resource pool can still be used to transmit SL data in the resource pool of the SL data channel. For example, the transmitting terminal can transmit by mapping the PSSCH to a succession of PRBs.

[0137] (3) The discovery channel may be a resource pool for a transmitting terminal to transmit information such as its ID. Through this, the transmitting terminal can enable adjacent terminals to discover it.

[0138] Even if the content of the SL signal described above is the same, different resource pools may be used depending on the transmission and reception attributes of the SL signal. For example, even if the same SL data channel or discovery message is used, it may be divided into different resource pools depending on the method of determining the transmission timing of the SL signal (e.g., whether it is transmitted at the time of reception of the synchronization reference signal or whether it is transmitted by applying a certain timing advance at the time of reception), the method of resource allocation (e.g., whether the base station assigns the transmission resource of an individual signal to the individual transmission terminal or whether the individual transmission terminal selects the individual signal transmission resource itself from within the resource pool), the signal format (e.g., the number of symbols occupied by each SL signal in one subframe, or the number of subframes used for the transmission of one SL signal), the signal strength from the base station, the transmission power strength of the SL terminal, etc.

[0139] FIG. 11 illustrates an example of a BWP according to an embodiment of the present disclosure. The embodiment of FIG. 11 may be combined with various embodiments of the present disclosure. In the embodiment of FIG. 11, it is assumed that there are three BWPs.

[0140] Referring to FIG. 11, the common resource block (CRB) may be a numbered carrier resource block extending from one end of the carrier band to the other. And, the PRB may be a numbered resource block within each BWP. Point A may indicate a common reference point for the resource block grid.

[0141] A BWP can be configured by point A, an offset from point A (NstartBWP), and a bandwidth (NsizeBWP). For example, point A may be an external reference point of the PRB of a carrier where the subcarrier 0 of all numerologies (e.g., all numerologies supported by the network on that carrier) is aligned. For example, the offset may be the PRB interval between the lowest subcarrier in a given numerology and point A. For example, the bandwidth may be the number of PRBs in a given numerology.

[0142] SLSS (Sidelink Synchronization Signal) is a sidelink-specific sequence and may include PSSS (Primary Sidelink Synchronization Signal) and SSSS (Secondary Sidelink Synchronization Signal). The PSSS may be referred to as S-PSS (Sidelink Primary Synchronization Signal), and the SSSS may be referred to as S-SSS (Sidelink Secondary Synchronization Signal). For example, length-127 M-sequences may be used for S-PSS, and length-127 Gold sequences may be used for S-SSS. For example, a terminal may use S-PSS to detect the initial signal and obtain synchronization. For example, a terminal may use S-PSS and S-SSSS to obtain detailed synchronization and detect the synchronization signal ID.

[0143] The PSBCH (Physical Sidelink Broadcast Channel) may be a (broadcast) channel through which basic (system) information that the terminal must know first is transmitted before transmitting or receiving SL signals. For example, the basic information may include information related to SLSS, Duplex Mode (DM), TDD UL / DL (Time Division Duplex Uplink / Downlink) configuration, information related to resource pools, types of applications related to SLSS, subframe offsets, broadcast information, etc. For example, to evaluate PSBCH performance, in NR V2X, the payload size of the PSBCH may be 56 bits, including a 24-bit CRC (Cyclic Redundancy Check).

[0144] S-PSS, S-SSS, and PSBCH may be included in a block format that supports periodic transmission (e.g., SL SS (Synchronization Signal) / PSBCH block, hereinafter S-SSB (Sidelink-Synchronization Signal Block)). The S-SSB may have the same numerology (i.e., SCS and CP lengths) as the PSCCH (Physical Sidelink Control Channel) / PSSCH (Physical Sidelink Shared Channel) within the carrier, and the transmission bandwidth may be within a (pre-)set SL BWP (Sidelink BWP). For example, the bandwidth of the S-SSB may be 11 RB (Resource Block). For example, the PSBCH may span 11 RB. Additionally, the frequency position of the S-SSB may be (pre-)set. Therefore, the terminal does not need to perform hypothesis detection at the frequency to discover the S-SSB in the carrier.

[0145] FIG. 12 illustrates a procedure in which a terminal performs V2X or SL communication according to a resource allocation mode, according to one embodiment of the present disclosure. The embodiment of FIG. 12 may be combined with various embodiments of the present disclosure.

[0146] Referring to FIG. 12(a), in resource allocation mode 1, the base station may schedule SL resources to be used by the terminal for SL transmission. For example, in step S1200, the base station may transmit information related to SL resources and / or information related to UL resources to the first terminal. For example, the UL resources may include PUCCH resources and / or PUSCH resources. For example, the UL resources may be resources for reporting SL HARQ feedback to the base station.

[0147] For example, the first terminal may receive information related to a dynamic grant (DG) resource and / or information related to a configured grant (CG) resource from the base station. For example, the CG resource may include a CG type 1 resource or a CG type 2 resource. In this specification, the DG resource may be a resource that the base station sets / assigns to the first terminal via downlink control information (DCI). In this specification, the CG resource may be a (periodic) resource that the base station sets / assigns to the first terminal via DCI and / or RRC messages. For example, in the case of a CG type 1 resource, the base station may transmit an RRC message containing information related to the CG resource to the first terminal. For example, in the case of a CG type 2 resource, the base station may transmit an RRC message containing information related to the CG resource to the first terminal, and the base station may transmit DCI related to the activation or release of the CG resource to the first terminal.

[0148] In step S1210, the first terminal may transmit a PSCCH (e.g., Sidelink Control Information or 1st-stage SCI) to the second terminal based on the resource scheduling. In step S1220, the first terminal may transmit a PSSCH (e.g., 2nd-stage SCI, MAC PDU, data, etc.) associated with the PSCCH to the second terminal. In step S1230, the first terminal may receive a PSFCH associated with the PSCCH / PSSCH from the second terminal. For example, HARQ feedback information (e.g., NACK information or ACK information) may be received from the second terminal via the PSFCH. In step S1240, the first terminal may transmit / report the HARQ feedback information to the base station via a PUCCH or PUSCH. For example, the HARQ feedback information reported to the base station may be information generated by the first terminal based on HARQ feedback information received from the second terminal. For example, the HARQ feedback information reported to the base station may be information generated by the first terminal based on a pre-set rule. For example, the DCI may be a DCI for scheduling SL.

[0149] Referring to FIG. 12(b), in resource allocation mode 2, the terminal can determine an SL transmission resource within an SL resource set by the base station / network or a preset SL resource. For example, the set SL resource or the preset SL resource may be a resource pool. For example, the terminal may autonomously select or schedule a resource for SL transmission. For example, the terminal may perform SL communication by selecting a resource itself within the set resource pool. For example, the terminal may select a resource itself within a selection window by performing a sensing and resource (re)selection procedure. For example, the sensing may be performed on a subchannel basis. For example, in step S1210, the first terminal, having selected a resource itself within the resource pool, may use the resource to transmit PSCCH (e.g., SCI (Sidelink Control Information) or 1st-stage SCI) to the second terminal. In step S1220, the first terminal can transmit PSSCH (e.g., 2nd-stage SCI, MAC PDU, data, etc.) associated with the PSCCH to the second terminal. In step S1230, the first terminal can receive PSFCH associated with the PSCCH / PSSCH from the second terminal.

[0150] Referring to FIG. 12 (a) or (b), for example, the first terminal may transmit an SCI to the second terminal over the PSCCH. Or, for example, the first terminal may transmit two consecutive SCIs (e.g., 2-stage SCIs) to the second terminal over the PSCCH and / or PSSCH. In this case, the second terminal may decode the two consecutive SCIs (e.g., 2-stage SCIs) to receive the PSSCH from the first terminal. In this specification, an SCI transmitted over the PSCCH may be referred to as the 1st SCI, the 1st SCI, the 1st-stage SCI, or the 1st-stage SCI format, and an SCI transmitted over the PSSCH may be referred to as the 2nd SCI, the 2nd SCI, the 2nd-stage SCI, or the 2nd-stage SCI format.

[0151] Referring to FIG. 12 (a) or (b), in step S1230, the first terminal can receive PSFCH. For example, the first terminal and the second terminal can determine a PSFCH resource, and the second terminal can use the PSFCH resource to transmit HARQ feedback to the first terminal.

[0152] Referring to FIG. 12(a), in step S1240, the first terminal can transmit SL HARQ feedback to the base station via PUCCH and / or PUSCH.

[0153] Figure 13 is a diagram illustrating the control plane procedure of an L2 U2N relay (UE-to-Network Relay).

[0154] The PC5-RRC side PC5 unicast link setup procedure of Rel-16 NR V2X can be reused to set up a secure unicast link for layer 2 UE-to-Network relaying between the remote UE and the relay UE before the remote UE establishes a Uu RRC connection with the network through the relay UE.

[0155] For both in-coverage and out-of-coverage situations, when the remote UE initiates the first RRC message to establish a connection with the gNB, the PC5 L2 configuration for transmission between the remote UE and the U2N relay UE can be based on the RLC / MAC configuration defined in the standard. The establishment of the remote UE's Uu SRB1 / SRB2 and DRB follows the legacy Uu configuration procedure for the L2 U2N relay.

[0156] A specified scenario (TS 38.300) describes the control plane procedure of the L2 U2N relay as follows.

[0157] In step S1300, the remote UE and the relay UE perform a discovery procedure and can establish a PC5-RRC connection in step S1301 based on the existing Rel-16 procedure.

[0158] In step S1302, the remote UE can send the first RRC message (i.e., RRCSetupRequest) to establish a connection with the gNB via the Relay UE using the default L2 configuration of PC5. The gNB responds to the remote UE with an RRCSetup message (S1303). The delivery of the RRCSetup to the remote UE uses the default configuration of PC5. If the relay UE was not started in RRC_CONNECTED, it must perform its own connection setup upon receiving the message for the default L2 configuration of PC5.

[0159] In step S1304, the gNB and the relay UE perform the relay channel setup procedure via Uu. Depending on the configuration of the gNB, the relay / remote UE establishes an RLC channel to relay SRB1 to the remote UE via PC5. This step prepares the relay channel for SRB1.

[0160] In step S1305, a remote UE SRB1 message (e.g., RRCSetupComplete message) is transmitted to the gNB via the relay UE using the SRB1 relay channel through PC5. Then, the remote UE establishes an RRC connection through Uu.

[0161] In steps S1306 and S1307, the remote UE and gNB establish security according to legacy procedures, and security messages are transmitted through the Relay UE.

[0162] In steps S1308 and S1309, the gNB sends RRCReconfiguration to the remote UE via the relay UE to configure the relay SRB2 / DRB. The remote UE sends RRCReconfigurationComplete to the gNB in ​​response via the relay UE.

[0163] In step S1310, the gNB establishes an additional RLC channel between the gNB and the relay UE for traffic relay. Depending on the configuration of the gNB, the relay / remote UE establishes an additional RLC channel between the remote UE and the relay UE for traffic relay.

[0164] In the above scenario, in addition to the connection setup procedure, for the L2 UE-to-Network relay:

[0165] - The RRC reconfiguration and RRC disconnection procedures can reuse legacy RRC procedures along with the message content / configuration design left in the WI stage.

[0166] The RRC connection reset and resumption procedures can reuse existing RRC procedures as a baseline by considering the connection setup procedure of the L2 U2N relay above to handle specific parts of the relay, along with the message content / configuration design. The message content / configuration may be defined later.

[0167] Unmanned Aerial Vehicle (UAV)-to-everything (U2X)

[0168] FIGS. 14 to 18 are drawings for explaining the U2X system.

[0169] The key points of the proposed U2X solution in a given scenario (TR 23.700-58) are as follows.

[0170] - U2X can support BRID and Direct DAA by utilizing the V2X mechanism defined in TS 23.287. In this case, both LTE PC5 and NR PC5 defined in TS 23.285 are supported, and RAT selection can be performed based on U2XP.

[0171] - Communication Mode: BRID (Broadcasting UAV identification) can use Broadcast communication mode. DAA can use Broadcast communication mode to advertise UAV information. Broadcast via PC5 or Unicast via PC5 can be used between two or more UAVs for DAA collision resolution. Unicast via Uu via U2X AS may not be supported by the aforementioned U2X solution. Groupcast mode for NR-based PC5 may not be supported by the aforementioned U2X solution. If NR PC5 is selected, connectionless groupcast communication may be used by DAA. Meanwhile, application layer managed groupcast may not be considered in this release due to the lack of explicit requirements.

[0172] - U2X can be supported on a U2X Application Server that interfaces with the carrier network via NEF, just as in the case of a V2X Application Server.

[0173] Meanwhile, in the above-mentioned predetermined scenario / solution, a dedicated service set can be defined, and multiple deployment scenarios need to be allowed when the U2X AS and USS providing the UAV are the same or different entities.

[0174] - A U2X policy (U2XP) may be defined to provide configuration parameters to a UE for U2X communication via a PC5 reference point or a Uu reference point. These configuration parameters may be pre-configured in the ME (Mobile Equipment), configured in the UICC (Universal IC Card), pre-configured in the ME and configured in the UICC, provided / updated by the U2X application server via the PCF (Policy Control Function) and / or V1 reference point, or provided / updated to the UE by the PCF. Here, the UE needs to consider the U2X policy according to priority, in the order of those provided / updated by the PCF, those provided / updated by the U2X application server via the V1 reference point, those configured in the UICC, and those pre-configured in the ME. A de-conflicting policy may be a policy indicating the communication mode (unicast or broadcast) for conflict resolution, the communication frequency for conflict resolution, etc.

[0175] - As with V2X, the Tx profile or NR Tx profile can be determined based on the U2XP mapping of the U2X service type.

[0176] - Both UAVs with UICC and UAVs without UICC (i.e., not subscribed to an MNO) can be supported. Here, UAVs without UICC can perform U2X communication only if they are approved as "Not provided by E-UTRA" and "Not provided by NR".

[0177] - U2X communication parameters of the U2X application server or PCF can be transmitted through the UAV-C UE.

[0178] - In addition to existing parameters for V2X, geographic area, altitude restrictions, and validity period timers can be set as wireless parameters for PC5 RATs (e.g., LTE PC5, NR PC5). Such additional information / parameters may be necessary to policy-control PC5 usage based on the specific location of the UAV.

[0179] - The definition of DAA / UAV service types may fall outside the scope of the specified scenarios described above.

[0180] - To use PC5-based communication for BRID and DAA in a UAV equipped with UICC, UUAA certification / authorization must be successfully completed as defined in TS 23.256 and authorization must be obtained via U2XP. However, the U.S. Federal Aviation Administration does not require specific authorization for the use of PC5 for BRID or DAA. For UAVs without UICC, the use of PC5-based communication for BRID and DAA can only be authorized by U2XP. Meanwhile, U2X services may be identified as one of ITS-AID (ITS Application Identifier), PSID (Provider Service Identifier), or AID (Application Identifier) ​​according to values ​​specifically defined for aviation applications.

[0181] As with TS 23.287, security for broadcast U2X communication through PC5 reference points can be supported in U2X application layer schemes developed by other SDOs.

[0182] Referring to FIG. 14, a non-roaming 5G system architecture for U2X communication via PC5 can be configured as shown in FIG. 14. Here, the non-roaming 5G system architecture for U2X communication via PC5 may apply the reference point of TS 23.287 and may have the following differences.

[0183] - U2X1: As a reference point between the UE, UAV-C, and the U2X application server, this reference point may be outside the scope of the aforementioned predetermined scenario.

[0184] - U2X5: As a reference point between U2X applications within the UE, this reference point may not be specific / designated in releases of certain scenarios.

[0185] - N1: In addition to the related functions defined in TS 23.501 for N1, in the case of U2X services, it can also be used to transfer U2X policies and parameters (including service acceptance) from AMF to UE, and to transfer PC5 functions for UE's U2X functions and U2X information from UE to AMF.

[0186] - N2: In addition to the related functions defined in TS 23.501 for N2, in the case of U2X services, it can also be used to transmit U2X policies and parameters (including service acknowledgments) from AMF to NG-RAN.

[0187] - The above-described solution can support UAV UEs that utilize Uu connectivity and UAV UEs that do not utilize Uu connectivity (i.e., UAV UEs that can use Uu or UAV UEs that do not use Uu). UAVs that do not utilize Uu capabilities can use U2X for BRID and DAA and can be configured via U2X1 through transmissions outside the scope of 3GPP. Meanwhile, UAV UEs that do not utilize Uu capabilities can be part of the 3GPP ecosystem as they use U2X1 for configuration by the U2X application server and implement the PC5 connectivity specified by 3GPP.

[0188] The roaming 5G system architecture for U2X communication via PC5 can be configured as illustrated in FIGS. 15 and FIG. 16. Specifically, FIG. 15 illustrates the roaming 5G system architecture for U2X communication via PC5 in a local breakout scenario, and FIG. 16 illustrates the roaming 5G system architecture for U2X communication via PC5 in a home routing scenario.

[0189] The 5G system architecture between PLMNs (Public Land Mobile Networks) for U2X communication via PC5 reference points may be as follows.

[0190] - For U2X communication between PLMNs via a PC5 reference point, PC5 parameters need to be set in a consistent manner among UEs within a specific region.

[0191] - The architecture for the Inter-PLMN PC5 may be similar to that defined in the non-roaming 5G system architecture for U2X communication via PC5 described with reference to Fig. 14.

[0192] AF-based service parameter provisioning for U2X communication can be defined as follows.

[0193] - As defined in TS 23.287, a 5G system may provide NEF services to enable communication between the PLMN's NF and the U2X application server. Specifically, a high-level view of AF-based service parameter provisioning for U2X communication can be shown as illustrated in Fig. 17. Service parameters may also be pre-configured in the UAV using methods outside the scope of 3GPP (e.g., when not utilizing Uu functions).

[0194] In a U2X scenario, the following points can be considered.

[0195] - Use / Application of U2X for BRID: Message content for BRID may be defined according to regional regulations for BRID (e.g., message set of ASTM F3411.19 or ASD-STAN prEN 4709-002 P1) and optionally according to the regional mean of compliance documents.

[0196] - U2X Usage / Purpose for DAA: Message content for DAA is defined according to regional regulations regarding DAA and may fall outside the scope of the specified scenarios described above.

[0197] The procedures and mechanisms of TS 23.287 can be applied to U2X scenarios. Specifically, the procedure for broadcasting via PC5 for DAA collision resolution can be performed as shown in FIG. 18. Meanwhile, the procedure for broadcasting via PC5 for DAA collision resolution may be based on the premise that a U2X policy including a DAA collision resolution policy (e.g., unicast or broadcast communication for collision resolution, communication frequency) is provisioned in the UAV.

[0198] Specifically, the procedure for broadcasting via PC5 to resolve DAA collisions according to FIG. 18 can be performed as follows.

[0199] 1. UAV1 can receive a broadcast message from UAV2 that may include an application layer DAA payload (e.g., CAA level UAV ID, UAV2's USS address, speed, direction of travel, location, etc.).

[0200] - Note 1: A USS address (Unmanned aerial system Traffic Management (UTM) Service Supplier address) is not required when collisions between UAVs are resolved locally, but it may be required when USS adjustment of the UAVs involved in the collision is necessary.

[0201] 2. UAV1 can deliver a DAA payload to the upper layer. The application layer can detect a collision by methods such as comparing its own trajectory and position with the broadcast message received from UAV2. When the application layer of UAV1 detects a collision, a collision avoidance / collision resolution procedure with UAV2 can be initiated.

[0202] 3. Optionally, UAV1 may notify its USS (UTM Service Supplier) of the detected collision, including the ID of peer UAV 2.

[0203] 4. UAV1 can select a communication mode (broadcast or unicast) for DAA collision resolution based on inputs received from the application layer and the DAA policy. If the broadcast collision resolution method is selected, the following messages may be exchanged between UAVs.

[0204] 5. UAV1 broadcasts a message (e.g., PC5-S message) (e.g., collision clearing request message), which is part of the U2X function and may include a DAA function indicating whether the UAV can participate in communication for specific parameters (e.g., collision clearing information), a protocol, a DAA collision clearing policy (broadcast-based, collision clearing message frequency), a collision detection warning, the corresponding CAA level UAV ID and the ID of another UAV that has detected a collision, and specific parameters (e.g., trajectory correction information to avoid collision). (UAV1 broadcasts a message (eg PC5-S message), eg deconfliction request message and may include DAA capability, which is part of U2X capability and indicates whether the UAV is able to engage in communication for deconflicting protocol, DAA deconflicting policy (broadcast based, deconflicting message frequency), collision detection alert, its CAA-level UAV IDs and the one(s) from other detected conflicting UAV(s), and deconflicting specific parameters (eg trajectory correction information to avoid collision))

[0205] 6. UAV2 may broadcast a message (e.g., PC5-S message) to provide the agreed-upon DAA collision resolution policy, updated trajectory, and other information (e.g., message collision resolution status response, collision resolution alert, CAA level UAV ID of the participating UAV from the receiving UAV). Subsequent broadcast messages may be exchanged between UAVs according to the agreed-upon message frequency until traffic collision resolution (e.g., mutual location / trajectory monitoring) is reached.

[0206] The impact on services, entities, and interfaces related to the aforementioned U2X may be as shown in Tables 5 and 6 below.

[0207] 1. UE: In addition to the functions defined in TS 23.501, the UE supports the following functions: - Reporting U2X functions (including DAA functions) and PC5-based U2X functions to the 5GC via the N1 reference point. - Indicating UE-based U2X policy provisioning requests via the UE Policy Container. - Receiving U2X parameters from the 5GC via the N1 reference point. - Performing U2X communication procedures via the PC5 reference point. - Configuring parameters for U2X communication. These parameters can be pre-configured in the UE, or, if within coverage, provisioned or updated via signaling through the HPLMN's PCF or the U2X1 reference point of the U2X application server. 2. AMF: In addition to the functions defined in TS 23.501, the AMF performs the following functions: - Obtain U2X-related subscriber information from the UDM and store it as part of the UE context data. - Select a PCF that supports U2X policy / parameter provisioning and report the U2X PC5 capabilities to the selected PCF. - Obtain U2X-related PC5 QoS information from the PCF and store it as part of the UE context data. - Provide the UE's communication permission status to the NG-RAN for U2X communication via the PC5 reference point. - Provide PC5 QoS parameters related to U2X communication to the NG-RAN. 3. PCF: In addition to the functions defined in TS 23.501, it provision parameters required for U2X communication to the UE and AMF, including the functions specified in TS 23.287. 4. UDM: Performs subscriber management functions for U2X communication via the PC5 reference point. 5. U2X Application Server: TS 23.Implements a subset of the V2X AS functions defined in 287: - Includes AF functions and can support the following minimum functions: - For U2X service parameter provisioning, the U2X AS provides U2X communication parameters to 5GC and UAV UEs (via UAVC if necessary) via PC5 and Uu reference points. 6. UDR: Includes U2X service parameter storage functions in addition to the functions defined in TS 23.501. 7. NRF: Discovers PCFs considering U2X functions in addition to the functions defined in TS 23.501. 8. NEF: Performs U2X service parameter support functions for the U2X AS.

[0208] U2X Subscription dataNR U2X Services AuthorizationIndicates whether the UE is authorized to use the NR sidelink for U2X services as UAV UE, UAV-C UE, or Authority UE.LTE sidelink (ie PC5) communication for U2X services.LTE UE-PC5-AMBRAMBR of UE's LTE sidelink (ie PC5) communication for U2X services.

[0209] In addition, recent discussions regarding the aforementioned scenario are as shown in Table 7 below.

[0210] Measurement reporting is based on LTE principles, and similar events H1 (the altitude of an airborne UE rises above a threshold) and H2 (the altitude of an airborne UE falls below a threshold) are introduced. Whether further improvements to NR are necessary is a subject for future research (FFS). Research is needed on the scaling of RRM parameters (e.g., what parameters they are, what the purpose / benefits of scaling are, and how they can be achieved). - Research is needed on methods to limit excessive measurements and measurement reporting (FFS). - Research is needed on whether user consent is required for position reporting in the CONNECTED state (FFS). - Research is needed on the vertical movement of UAV UEs and the accompanying mobility (FFS). - Rel-18 NR supports altitude, position, and velocity reporting for UAV UEs. The required accuracy and reporting mechanisms, as well as whether further improvements are needed, are subjects for future research. - Flight path planning reporting is scheduled to be introduced, similar to LTE, and location lists (3D position information) and timestamps are adopted as the basic content for flight path reporting. Whether timestamps are mandatory or optional in NR is FFS. Whether further improvements are needed is also FFS. - A feature similar to LTE (number of Triggering Cells) has been introduced. Whether number of trigger beams is required in NR is FFS. Research is needed on methods to prevent measurement reports from being transmitted primarily when the reporting entity is reportOnLeave (FFS). - Waypoints are locations planned by the UE along the flight path and are described through the existing parameter type LocationCoordinates defined in TS 37.355. - Timestamps provide the UTC time corresponding to the estimated time of arrival at the waypoint and are used as a baseline. Regarding granularity, FFS. - There are no requirements regarding the spatial distribution of waypoints.- The UE indicates that flight path information is available via the RRCReconfigurationComplete, RRCReestablishmentComplete, RRCResumeComplete, or RRCSetupComplete messages. Flight path reporting is based on the UE information request / response procedure. - The UE indicates to the network that a new flight path is available (regardless of whether it is initial or updated), reusing the general request / response procedure for flight path reporting. - UAI messages may also be used by the UE to indicate that flight path information is available. - The trigger conditions for flight path updates are determined by FFS. The maximum number of waypoints within the flight path plan is left to FFS. - When Event H1 or H2 is triggered, the content of the measurement report is configurable by the network (i.e., it may include the altitude and location information of the UAV UE and / or RSRP / RSRQ measurement results). Whether the altitude of a UAV UE must be reported and the parameters / IEs used for altitude reporting are FFS.- In NR Rel-18 UAVs, the combined use of altitude-dependent conditions and RSRP / RSRQ / SINR-based conditions is supported for measurement reporting triggers. Combinations of existing events are used. Altitude-based parameter scaling is not supported as part of Rel-18 NR.- The Number of triggering cells mechanism is not applied to inter-RAT scenarios, i.e., event B1 and B2 triggering.- The application of the Number of triggering cells mechanism is not limited to FR1 only. That is, the Number of triggering cells mechanism is applicable to both FR1 and FR2 (depending on network configuration).- The UE must not ignore or bypass the Number of triggering cells mechanism if it is configured.- The NumberOfTriggeringBeams mechanism is not introduced.- No alternative mechanism is introduced for the Number of triggering cells mechanism. - No additional mechanism is introduced based on the changed number of cells. - No prohibit timer mechanism is introduced for interference control purposes (e.g., Number of triggering cells). - ReportOnLeave is not triggered by cells that were not previously included in the measurement report for the Number of triggering cells. - Support for altitude-dependent multiple configurations to improve measurement and measurement reporting. The UE applies the corresponding configuration based on altitude. The proposed solution aims to prevent RAN4 impact. How this is configured (e.g., different MO configurations or different parameters, etc.) is FFS. Specific parameters and details are FFS. - Altitude-dependent multiple configurations are supported at the parameter / field level (i.e., different fields / values ​​within the same MO), where different values ​​(or value ranges) of the parameter / field are applied based on altitude or altitude range. - For MO configuration parameters, at least the following items are configurable to have altitude-dependent multiple configurations / values ​​per specific altitude area: SSB-ToMeasure. The specified method is FFS. For UE's L1 and L3 measurement operations, FFS.- For MR configuration parameters, at least the following items can be configured to have multiple altitude-dependent configurations / values ​​per specific altitude range: Event A4 threshold and number of triggering cells. The specified method is FFS (e.g., can be achieved through event combinations).- If multiple altitude-dependent configurations are provided, the UE applies new values ​​when moving to a new altitude (or altitude range) (similar to RRC reconstruction). Codes, field descriptions, etc., apply as in existing specifications.- If altitude-specific values ​​are not explicitly configured for a particular altitude, whether to continue using the previous value or to consider the parameter disabled must be reviewed on a case-by-case basis, and this can be clarified through code, field descriptions, or procedure text as necessary.

[0211] FIGS. 19 to 23 are drawings for explaining group mobility.

[0212] The path switching relationship between the relay UE and the remote UE and the operation related to the relay UE's HO, which are performed via SL communication, may be as described in a given scenario (e.g., TS 38.300). Meanwhile, when the relay UE performs an HO, the relay UE may transmit a notification message to the remote UE containing the cause value of the HO, and the remote UE that receives this may perform RRCR establishment for the direct / indirect path (e.g., a procedure for reselecting the relay UE).

[0213] The following describes in detail how to perform a group handover (HO) between a relay UE and a remote UE.

[0214] Both the evolved ProSe Remote UE (wearable device) and the evolved ProSe UE-to-Network relay UE move from one eNB to another (i.e., mobility situation). The evolved ProSe Remote UE can remain connected to the same evolved ProSe UE-to-Network relay UE. When the evolved ProSe UE-to-Network relay UE undergoes a handover between serving cells, all evolved ProSe Remote UEs being served by that relay UE must also be considered for handover; this is to ensure that the context of these terminals maintains its position within the network alongside the context of the relay UE. Various options can be considered to support this type of group mobility.

[0215] Here, "groups" of UEs can be identified by the serving eNB, and the group identification method is the subject of discussion in RAN2 / SA2. Once a group is identified, the eNB can prepare group handovers for the most likely target cells by utilizing various input information, such as measurement reports. This can increase the time available for handover execution, reduce the risk of handover failure, and improve the accuracy of resource allocation in target cells.

[0216] Referring to FIG. 19, the “group handover command” method may be a method of combining reconfiguration messages for relay UEs and remote UEs into one and transmitting it over the air.

[0217] The serving (source) eNB can combine RRCConnectionReconfiguration commands for mobility triggers for evolved ProSe UE-to-Network relay UEs and evolved ProSe Remote UEs and transmit them as a single transport over the Uu interface. The evolved ProSe Remote UE should receive only its own configuration information. The handling of evolved ProSe Remote UEs that are not handed over with the evolved ProSe UE-to-Network relay UE may be subject to future review.

[0218] The PC5-S message can be used for message delivery between an evolved ProSe UE-to-Network relay UE and an evolved ProSe Remote UE via a sidelink. Whether this message will deliver RRC reconfiguration messages through a transparent container or be defined as a new message may be subject to future review.

[0219] The exact sequence of operations from steps 6a to 8b in Fig. 19 may be changed later, for example, to a case where the evolved ProSe UE-to-Network relay UE sends its own "handover complete" message first before receiving "reconfiguration complete" messages from all evolved ProSe Remote UEs.

[0220] A “group handover response” method may be performed. For example, as illustrated in FIG. 20, an evolved ProSe UE-to-Network relay UE may collect a response to an RRC reconfiguration message received from each evolved ProSe Remote UE and then transmit it over the wireless section as a single combined transmission. Here, the evolved ProSe UE-to-Network relay UE may be responsible for transmitting the group handover response to the target eNB simultaneously with the completion of the handover for itself.

[0221] Referring to FIG. 21, a separate handover procedure including relationship information between an evolved ProSe Remote UE and an evolved ProSe UE-to-Network relay UE can be performed. This method (hereinafter, Method 1) can be applied only when a PC5 interface is used between an evolved ProSe Remote UE and an evolved ProSe UE-to-Network relay UE.

[0222] In this method 1, X2 signaling (e.g., Handover Request, Handover Request ACK, UE Context Release) and S1 signaling (e.g., Path Switch Request, Path Switch Request ACK) for the evolved ProSe UE-to-Network relay UE and the evolved ProSe Remote UE, respectively, may be transmitted separately. Additionally, relationship information between the evolved ProSe UE-to-Network relay UE and the evolved ProSe Remote UE may be included in the HANDOVER REQUEST message. The target eNB must wait until it receives Handover Request messages from both the evolved ProSe UE-to-Network relay UE and the evolved ProSe Remote UE, and must prepare resources for all relevant UEs by taking all relevant information into account.

[0223] The specific procedure of the above-described method 1 may be as follows.

[0224] 1. eNB1 determines the group handover between the evolved ProSe UE-to-Network relay UE and the evolved ProSe Remote UE.

[0225] 2. eNB1 sends a HANDOVER REQUEST message containing relationship information between the evolved ProSe UE-to-Network relay UE and the evolved ProSe Remote UE (e.g., a list of evolved ProSe UE-to-Network relay UE IDs and evolved ProSe Remote UE IDs) to trigger a handover of the evolved ProSe UE-to-Network relay UE from the cellular link of eNB1 to the cellular link of eNB2.

[0226] 3. eNB1 sends a HANDOVER REQUEST message containing relationship information between the evolved ProSe UE-to-Network relay UE and the evolved ProSe Remote UE to trigger a handover of the evolved ProSe Remote UE from the relay link of eNB1 to the relay link of eNB2.

[0227] 4. After receiving all HANDOVER REQUEST messages regarding the relationship information of the related evolved ProSe UE-to-Network relay UE and the evolved ProSe Remote UE, eNB2 performs admission control and prepares resources for the UEs.

[0228] 5. eNB2 sends a HANDOVER REQUEST ACKNOWLEDGE message to eNB1 for the evolved ProSe UE-to-Network relay UE.

[0229] 6. eNB2 sends a HANDOVER REQUEST ACKNOWLEDGE message for the evolved ProSe Remote UE to eNB1.

[0230] 7. The advanced ProSe UE-to-Network relay UE and the advanced ProSe Remote UE move together to the eNB2.

[0231] 8. eNB2 triggers the Path Switch procedure for the evolved ProSe UE-to-Network relay UE.

[0232] 9. eNB2 triggers the pass switch procedure for the advanced ProSe Remote UE.

[0233] 10. eNB2 triggers the UE context release procedure toward eNB1 for the evolved ProSe UE-to-Network relay UE.

[0234] 11. eNB2 triggers the UE context release procedure toward eNB1 for the evolved ProSe Remote UE.

[0235] 12. eNB1 releases resources for the advanced ProSe UE-to-Network relay UE and the advanced ProSe Remote UE.

[0236] Method 2 may be a method for performing a group handover between an evolved ProSe Remote UE and an evolved ProSe UE-to-Network relay UE. Method 2 may be applied only when a PC5 interface is used between the evolved ProSe Remote UE and the evolved ProSe UE-to-Network relay UE. In Method 2, the evolved ProSe Remote UE and the evolved ProSe UE-to-Network relay UE can be moved together from eNB1 to eNB2 through a group X2 handover procedure. To this end, Group Handover Request and Group Handover Request ACK messages may be introduced.

[0237] As illustrated in FIG. 22, the above-described method 2 can be performed as follows.

[0238] 1. eNB1 determines the group handover.

[0239] 2. eNB1 sends a GROUP HANDOVER REQUEST message to eNB2 for the evolved ProSe UE-to-Network relay UE and the evolved ProSe Remote UE.

[0240] 3. eNB2 performs admission control and prepares resources for the evolved ProSe UE-to-Network relay UE and the evolved ProSe Remote UE.

[0241] 4. eNB2 sends a GROUP HANDOVER REQUEST ACKNOWLEDGE message to eNB1.

[0242] 5. The advanced ProSe UE-to-Network relay UE and the advanced ProSe Remote UE move together to the eNB2.

[0243] 6. eNB2 triggers the Path Switch procedure for the evolved ProSe UE-to-Network relay UE.

[0244] 7. eNB2 triggers the pass switch procedure for the advanced ProSe Remote UE.

[0245] 8. eNB2 triggers the UE context release procedure toward eNB1 for the evolved ProSe UE-to-Network relay UE.

[0246] 9. eNB2 triggers the UE context release procedure toward eNB1 for the evolved ProSe Remote UE.

[0247] 10. eNB1 releases resources for the advanced ProSe UE-to-Network relay UE and the advanced ProSe Remote UE.

[0248] Alternatively, as illustrated in FIG. 23, the group handover procedure may be performed through a combination of the above-described method 1 and method 2.

[0249] Below, we will explain in detail how to perform HO procedures in relation to a remote UE when a moving UAV UE operates as a relay UE in an environment where frequent HO procedures are performed.

[0250] In the following, it is assumed that a UAV / AAM (Unmanned Aerial Vehicle / Advanced Air Mobility) UE can perform the operation of a relay UE, and that a general user / occupant UE on board the UAV / AAM UE performs the operation as a remote UE. L2 relay operation is assumed, and it is assumed that the relay UE and the remote UE are connected via SL or directly through the PC5 interface.

[0251] Service continuity support for remote UEs residing within the UAV

[0252] In the case of UAV UEs, frequent handovers (HO) may occur due to severe fluctuations and ground signal interference. For example, since UAV UEs move at high speeds in the air at high altitudes, severe channel fluctuations may occur, leading to significant interference from ground signals. In current Sidelink Relay (SL Relay) operations, when a handover occurs to a relay UE, a notification message is sent to the remote UE, and the remote UE can perform re-establishment by finding a direct or indirect path (new or the same). This operation (e.g., the operation for the re-establishment of the remote UE) may result in a problem where the service continuity of the remote UE cannot be sufficiently supported in an environment where the relay UE performs frequent handovers.

[0253] Considering these issues, the following describes in detail a method for supporting service continuity for the UE of the user / occupant or a remote UE aboard the UAV / AAM.

[0254] FIGS. 24 and 25 are diagrams illustrating how a relay UE and a remote UE perform a handover procedure.

[0255] 1. Method 1: How to set CHO on each of the Remote UE and Relay UE

[0256] Referring to FIG. 24, the remote UE and the relay UE receive configuration information for a conditional handover (CHO) from the serving gNB (or, serving base station, serving cell, source gNB) and can perform the conditional handover procedure based on the configuration information.

[0257] Specifically, the remote UE and the relay UE may perform the following steps as a procedure related to the conditional handover according to Method 1.

[0258] (1) Step 1

[0259] When a measurement reporting by a relay UE is triggered (e.g., when the Uu signal strength between the relay UE and the base station is below a set threshold), the relay UE may report the measurement value to the serving base station (or, serving gNB). For example, the relay UE may measure the cell quality of neighboring cells based on SSB and / or CSI-RS and transmit measurement information or a measurement report regarding the measured cell quality of neighboring cells to the base station.

[0260] (2) Step 2

[0261] The serving gNB (=source gNB) can determine the CHO for the relay UE and the remote UE based on measurement reports reported from the relay UE. For example, the serving gNB can determine the CHO for the relay UE and the remote UE if, based on the measurement reports, it is determined that a CHO for the relay UE is necessary, or if it is predicted that the relay UE is in a situation with severe channel fluctuations (or if it is identified as a UAV UE).

[0262] (3) Step 3

[0263] A serving gNB can transmit a handover request message for a relay UE and a remote UE to at least one candidate target gNB ( / cell). For example, when the serving gNB determines the CHO for the relay UE and the remote UE, it can transmit a handover request message for the relay UE and the remote UE to at least one candidate target gNB. In this case, the handover request message may include information about the UE type (relay UE / remote UE) and information about the (connection) relationship between the relay UE and the remote UE. Alternatively, the serving gNB may include the handover request message for the remote UE and the handover request message for the relay UE in a single handover request message and transmit it to at least one candidate target gNB, or transmit the handover request message for the remote UE and the handover request message for the relay UE as separate messages to at least one candidate target gNB.

[0264] (4) Step 4

[0265] At least one candidate target gNB determines whether to allow an HO (or CHO) after performing admission control when it receives a HANDOVER REQUEST message from a serving base station. For example, at least one candidate target gNB may determine whether to allow a CHO based on the HANDOVER REQUEST message.

[0266] (5) Step 5

[0267] At least one candidate target gNB capable of accepting a CHO (or HO) (e.g., target gNB(A) and candidate target gNB(B)) may transmit a HANDOVER REQUEST ACKNOWLEDGE or HANDOVER REQUEST ACKNOWLEDGE message for a remote UE and a relay UE to the serving gNB (or serving gNB). In this case, the HANDOVER REQUEST ACKNOWLEDGE message for each of the remote UE and the relay UE may be transmitted to the serving gNB as a single message or as individual messages. Here, the HANDOVER REQUEST ACKNOWLEDGE message may include an RRCReconfiguration message for the remote UE and / or the relay UE, or configuration information for the RRCReconfiguration message. For example, the HANDOVER REQUEST ACKNOWLEDGE message may include information regarding the RRCReconfiguration for each of the remote UE and the relay UE through a separate RRCReconfiguration container for each relay UE and the remote UE. For example, candidate target gNB(s) can send an RRCReconfiguration message or a HANDOVER REQUEST ACKNOWLEDGE message to the serving gNB using separate RRCReconfiguration containers for the relay UE and the remote UE, respectively.

[0268] (6) Step 6a / b and step 7a / b

[0269] When the serving gNB receives a HANDOVER REQUEST ACKNOWLEDGE message for the remote UE and relay UE from candidate target gNBs (e.g., target gNB (A) and candidate target gNB (B)), it may transmit an RRCReconfiguration message received from the candidate target gNB(s) to each of the remote UE(s) and relay UE(s) (Step 6a, Step 6b). The remote UE and relay UE(s) that receive the RRCReconfiguration message may continue to communicate with the current serving gNB, but may store the configuration or configuration information configured for communication with the configured candidate target gNBs (or target gNBs). For example, the remote UE and relay UE may obtain CHO configurations (e.g., trigger conditions for CHO execution or conditions for CHO execution) and information about at least one candidate target gNB (e.g., cell ID for at least one candidate target gNB) from the RRCReconfiguration message.

[0270] Alternatively, the RRCReconfiguration message for the remote UE may set an event other than channel event information consisting of general signal strength (e.g., when the signal strength with a candidate gNB( / cell) measured by the remote UE is below a set threshold) as the execution condition / trigger condition for the CHO. For example, the case where the remote UE receives a specific signal (e.g., a notification message) from the relay UE may be set as the CHO execution condition through the RRCReconfiguration message. Meanwhile, the execution condition for the CHO for the relay UE may be, as in the past, when the signal quality with a serving cell below a first threshold is measured and the signal quality with a candidate target cell above a second threshold is measured.

[0271] Each of the above remote UE and the above relay UE may send an RRCReconfigurationComplete message (or, RRC reset complete message) to the serving gNB based on the reception of the RRCReconfiguration message for the CHO configuration (Step 7a, Step 7b).

[0272] (7) Step 8

[0273] A serving gNB can transmit contexts (e.g., Sequence Numbers; SNs) for relay UEs and remote UE(s) for which CHO operations have been determined / set to at least one candidate target gNB. For example, the serving gNB can transmit an Early status Transfer or Early status Transfer message containing DL COUNT values ​​for relay UEs and remote UE(s) to the candidate target gNB(s). Here, the DL COUNT values ​​are values ​​for PDCP SNs and HFNs (Hyper Frame Numbers), and these SN / HFN pairs may be the sequence number and HFN of the first PDCP SDU that the source gNB forwards to the candidate target gNB or target gNB.

[0274] (8) Step 9

[0275] The relay UE can evaluate conditions for executing a CHO (e.g., CHO execution conditions set by an RRCReconfiguration message). For example, the CHO execution conditions may be when the Uu link signal strength between the relay UE and the serving gNB is below a set first threshold, or when the Uu link signal strength between the relay UE and the serving gNB is below a set first threshold and the Uu link signal strength between candidate target gNBs is above a set second threshold.

[0276] (9) Steps 10, 11, 12

[0277] When the CHO is executed, the relay UE may terminate the connection with the current serving gNB, select one of at least one configured candidate target gNB (e.g., target gNB (A)) (stored), and perform a RACH procedure on the selected target gNB (A) (Steps 10 and 11). For example, if the CHO execution condition set by the RRCReconfiguration message is satisfied, the relay UE may select one candidate target gNB from among at least one candidate target gNB set by the RRCReconfiguration message (e.g., target gNB (A) among the candidate target gNBs where the Uu link signal strength is above a set threshold), and perform a RACH procedure on the selected target gNB (A). At this time, the relay UE may send an RRCReconfigurationComplete message to the selected target gNB (A). For example, after the relay UE successfully / completes the RACH procedure with the selected target gNB (A), it can send an RRCReconfigurationComplete message to the selected target gNB (A) (Step 12).

[0278] (10) Step 13

[0279] When a relay UE completes the CHO execution (e.g., sending an RRCReconfigurationComplete message to a candidate target gNB), it may send a notification message to the remote UE(s) connected to it. In this case, the notification message may display CHO or HO as the cause value, and may include the target gNB / cell ID value connected (completed) by the relay UE through the CHO execution and be sent to the remote UE(s). For example, the notification message may set / display CHO as the cause value and include information regarding the cell ID of the target gNB (A) connected through the CHO execution.

[0280] (11) Step 14

[0281] If the gNB / cell ID value included in the notification message received from the relay UE, where the cause value is CHO, contains a cell ID that it stores (e.g., a cell ID for a candidate target cell included in a configured CHO-related configuration), the remote UE can trigger the execution of a CHO according to the configured CHO-related configuration. For example, if the remote UE has a gNB / cell ID identical to that of a target gNB / cell for which the relay UE has already performed a CHO, and this gNB / cell ID is included in the configured CHO-related configuration, the remote UE can transmit an RRCReconfigurationComplete message directed toward a target gNB having the target gNB / cell ID through the relay UE.

[0282] If a remote UE receives a notification message from a relay UE and checks the relay UE's CHO execution information (e.g., target gNB / cell ID information for which the relay UE completed the HO) in the message, but the said CHO execution information may not be included in the CHO-related settings stored by the remote UE, the remote UE may trigger a relay reselection (or relay UE reselection) procedure or perform a direct / indirect connection reestablishment procedure. For example, if the cell ID included in the notification message is not included in the remote UE's CHO-related settings (e.g., provided in an RRCReconfiguration message), the remote UE may perform a relay reselection procedure or a direct / indirect connection reestablishment procedure without a CHO trigger according to the said CHO-related settings.

[0283] (12) Step 15a / b / c

[0284] When the target gNB (A) receives an RRCReconfigurationComplete message from the relay UE and the remote UE (Step 12, Step 14), it can send a HANDOVER SUCCESS message to the serving gNB (Step 15a). Upon receiving this, the serving gNB can perform an SN Status Transfer for the information after the early status transfer was sent in the previous step 8 (Step 15b). The serving gNB can release the information related to the Early status transfer sent in the previous step 8 by sending a HANDOVER CANCEL message to another candidate target gNB (Step 15c).

[0285] 2. Method 2

[0286] Referring to FIG. 25, the source gNB or serving gNB can set CHO to the remote UE and set HO to the relay UE. In this case, the procedure according to Method 2 may be as follows.

[0287] (1) Step 1

[0288] When a measurement reporting by a relay UE is triggered (e.g., when the Uu signal strength between the relay UE and the base station is below a set threshold), the relay UE may report the measurement value to the base station (or, serving gNB). For example, the relay UE may measure the cell quality of neighboring cells based on SSB and / or CSI-RS and transmit measurement information or a measurement report regarding the measured cell quality of neighboring cells to the base station.

[0289] (2) Step 2

[0290] The serving gNB (=source gNB) can determine the CHO for the remote UE based on measurement reports reported from the relay UE. For example, the serving gNB can determine whether there is a possibility of an HO for the relay UE. If it is determined that an HO may occur for the relay UE, the serving gNB first selects at least one candidate target gNB (e.g., target gNB(A) and candidate target gNB(B)) to determine the CHO for the remote UE. For example, it is determined that an HO may occur for the relay UE due to unstable Uu signal strength between the current relay UE and the serving gNB, and there may be uncertainty as to which target gNB the relay UE should move to due to severe channel interference and fluctuation. In this case, the serving gNB can first determine the CHO for the remote UE connected to the relay UE.

[0291] (3) Step 3a, 3b, 3c

[0292] As described above, if it is determined that a HOW of the relay UE may occur due to an unstable Uu signal strength between the current relay UE and the serving gNB, and if it is uncertain which target gNB the relay UE should move to due to severe interference and fluctuation in the channel, the serving gNB may preferentially determine a CHO for the remote UE connected to the relay UE. In this case, the serving gNB may transmit a HANDOVER REQUEST message for the CHO of the remote UE(s) to at least one candidate target gNB (Step 3a). At this time, the HANDOVER REQUEST message transmitted may include information about the type of UE (e.g., remote UE) and / or information related to which relay UE the remote UE is connected to.

[0293] When the above at least one candidate target gNB (e.g., target gNB(A) and candidate target gNB(B)) receives the HANDOVER REQUEST message, it may perform admission control (Step 3b) and then send a HANDOVER REQUEST ACKNOWLEDGE message for the remote UE to the serving gNB (Step 3c).

[0294] (4) Step 4a / b

[0295] The serving gNB can transmit an RRCReconfiguration message for CHO configuration received from at least one candidate target gNB (e.g., target gNB(A) and candidate target gNB(B)) to the remote UE(s) (Step 4a). The RRCReconfiguration message may include SL-RLC configuration information that can be used when connecting to at least one candidate target gNB (e.g., connecting to at least one candidate target gNB through the current relay UE), C-RNTI values ​​that can be used in the target gNB / cell, etc. Additionally, it may be indicated that the condition triggering the execution of the configured CHO (e.g., CHO execution condition) may be a message received from the relay UE (e.g., a notification message). For example, the RRCReconfiguration message may include CHO configuration information that sets the reception of a notification message regarding the execution of the relay UE's HO as the CHO execution condition.

[0296] When the remote UE receives an RRCReconfiguration message containing the above CHO-related configuration information, it sends an RRCReconfigurationComplete message to the serving gNB (Step 4b) and can maintain the transmission and reception of data / messages with the current serving gNB.

[0297] (5) Step 5

[0298] When the serving gNB receives an RRCReconfigurationComplete message from a remote UE, it transmits information regarding the status of the remote UE (e.g., SN number, etc.) to at least one candidate target gNB. For example, the serving gNB may transmit an Early status Transfer or Early status Transfer message containing DL COUNT values ​​for the relay UE and the remote UE(s) to at least one candidate target gNB. Here, the DL COUNT value may be a value representing the PDCP SN and HFN (Hyper Frame Number), and the SN / HFN pair may be the sequence number and HFN of the first PDCP SDU that the source gNB forwards to at least one candidate target gNB.

[0299] (6) Step 6

[0300] After setting the CHO for the remote UE, the serving gNB can determine the HO for the relay UE based on the relay UE's measurement report or measurement information.

[0301] (7) Step 7a / b

[0302] The serving gNB determines the target gNB of the relay UE (e.g., target gNB (A)) and can send a HANDOVER REQUEST message to the target gNB (step 7a). When the target gNB receives the HANDOVER REQUEST message, the target gNB performs admission control and can send a HANDOVER REQUEST ACKNOWLEDGE message to the serving gNB that allows the relay UE's HO (step 7b).

[0303] (8) Step 8a / b / c

[0304] The serving gNB can transmit an HO-related RRCReconfiguration message received from the target gNB (e.g., an RRCReconfiguration message containing HO-related configuration information) to the relay UE (Step 8a). For example, the RRCReconfiguration message may include HO configuration information such as information related to synchronization for the target gNB related to HO execution, cell ID, C-RNTI, and RACH configuration information.

[0305] When the relay UE receives the above HO-related RRCReconfiguration message, it may perform an operation (e.g., a RACH procedure) to detach the connection with the current serving gNB( / cell) and attach the connection with the configured target gNB( / cell) (Step 8b). At this time, it may send an RRCReconfigurationComplete message to the target gNB (Step 8c). For example, the relay UE may send an RRCReconfigurationComplete message to the target gNB when the RACH procedure for the connection with the target gNB( / cell) is completed.

[0306] (9)Step 9

[0307] The relay UE may send a notification message to the remote UE when it has completed the HO (or when it has received the HO command or is performing the HO command). The notification message may include a cause value for the relay UE's HO and may include information on a cell ID for the target gNB (e.g., target gNB (A)) on which the relay UE completes or performs the HO.

[0308] (10) Step 10, 11

[0309] When a remote UE receives an HO-related notification message from a relay UE, it may compare the cell ID for the relay UE's target gNB (e.g., target gNB (A)) included in the notification message with the cell ID for a candidate target gNB included in its CHO-related configuration. For example, if the cell ID for the target gNB included in the notification message and the cell ID for the candidate target gNB included in the CHO-related configuration are the same, the remote UE may trigger a CHO execution based on the CHO-related configuration (step 10).

[0310] In this case, the remote UE can transmit an RRCReconfigurationComplete message toward the candidate target gNB (e.g., target gNB (A)) through the relay UE based on information about the candidate target gNB included in the CHO-related information (e.g., information about synchronization for the candidate target gNB related to CHO execution, C-RNTI, RACH configuration information, etc.) (step 11).

[0311] In contrast, if there is no cell ID among at least one candidate target gNB (e.g., target gNB (A)) included in the CHO-related configuration that is identical to the cell ID for the target gNB included in the notification message, the remote UE may trigger a relay reselection procedure or perform connection establishment through a direct / indirect path.

[0312] (11) Step 12

[0313] When the target gNB (A) receives an RRCReconfigurationComplete message from the remote UE, it may send a HANDOVER SUCCESS message to the serving gNB. When the serving gNB receives the HANDOVER SUCCESS message, it may perform an SN Status Transfer for information after the delivery of the remote UE's early status transfer in step 5 described above. The serving gNB may send a HANDOVER CANCEL message to another candidate target gNB to release the previously transmitted information related to the early status transfer.

[0314] In this way, when the UAV / AAM UE is a relay UE and the user UE on board the UAV UE is a remote UE, the service continuity of the onboard user UE can be effectively supported by applying the proposed method 1 or method 2.

[0315] For example, a user UE aboard a UAV / AAM UE may find it difficult to locate other relay UEs or maintain a connection with the gNB via a direct path (i.e., a Uu link directly connected to the gNB) due to shielded air conditions. Additionally, frequent HOs may occur due to the rapid mobility of the UAV / AAM UE and air channel conditions (frequently changing environments, heavy interference). In this case, if only an alert / notification regarding the HO from the relay UE (= UAV / AAM UE) is transmitted to the remote UE (= onboard user UE) as before, and the remote UE performs connection establishment based on said alert / notification, it may not effectively support service continuity for the onboard user UE. Meanwhile, the SL signal strength between the relay UE and the remote UE may not be in a dynamic environment. Therefore, it may not be useful for the remote UE to maintain a connection with the same relay UE while using the previously used CHO triggering conditions. In addition, the current method of delivering HO-related RRCReconfiguration messages to each remote UE and relay UE, as in the Group HO method, may be insufficient to support the service continuity of the remote UE in a dynamic environment where the appropriate target gNB / cell may change while delivering HO-related RRCReconfiguration messages to each relay UE / remote UE.

[0316] In contrast, the proposed method 1 and / or method 2 can first transmit / set a CHO setting for at least one candidate target gNB to the remote UE, and then rapidly select an appropriate target gNB based on a signal change between the relay UE and the serving gNB. Therefore, the proposed method 1 and / or method 2 can effectively support the service continuity of the remote UE in a dynamic one-channel environment of the UAV / AAM UE.

[0317] For example, the proposed method 1 and / or method 2 can ensure rapid connection of the relay UE to the target gNB even if frequent HOs of the relay UE are performed due to rapid fluctuations in signal strength between the serving gNB and the relay UE by providing the remote UE with CHO setting information for at least one candidate target gNB as a trigger condition for receiving a notification message regarding the HO performance of the relay UE, thereby effectively ensuring service continuity.

[0318] FIG. 26 is a diagram illustrating how a remote UE performs a handover procedure while maintaining a connection with a relay UE.

[0319] As described above, the remote UE is the UE of the passenger aboard the UAV, and can transmit and receive data with the serving base station / gNB through an SL connection or a direct connection with the UAV UE. For example, the UAV UE, which is the UE mounted on the UAV, can relay data / messages between the passenger UE and the base station as a relay UE for the passenger UE. As described above, since the UAV UE moves at high speed in the air, the radio channel environment of the UAV UE may change rapidly and frequent handovers may be performed. Even in this case, since the connection quality of the SL connection between the UAV UE and the remote UE (passenger UE) is continuously maintained, there may be no need to disconnect the connection between the UAV UE and the remote UE as before, even if the HO operation of the UAV UE is performed. For example, it is necessary to support a handover procedure for connecting the remote UE to the target gNB of the UAV UE while maintaining the connection with the said UAV UE. In the following, a method for a remote UE to perform a conditional handover while maintaining a connection with a relay UE is described in detail according to Method 1 and / or Method 2 described with reference to FIG. 24 and / or FIG. 25.

[0320] Specifically, referring to FIG. 26, a remote UE can establish a first connection with the relay UE for connection with a base station through the relay UE (S261). For example, as described with reference to FIG. 13, the remote UE can search for a relay UE through a discovery procedure for connection with a serving base station / serving gNB, establish an SL connection with the discovered relay UE (e.g., a UAV UE directly connected to the serving base station / serving gNB), and perform an RRC connection with the serving base station based on the established SL connection.

[0321] Next, the remote UE can receive an RRC (Radio Resource Control) reset message from the base station through the first connection (S263). For example, as described above, if it is detected that the channel state of the relay UE is in an environment where it is rapidly changing based on measurement reports of the relay UE, etc. (e.g., when moving at high speed in the air at a high altitude as a UAV UE) (e.g., when the channel state / channel quality changes by more than a certain threshold rate of change), the base station may determine a conditional handover for the remote UE connected to the relay UE. For example, as shown in FIG. 24 or FIG. 25, after determining a conditional handover for the remote UE, the base station may select at least one candidate target base station and send a handover request message for the remote UE to the selected at least one candidate target base station. Subsequently, the base station receives a message related to the approval of a handover (handover request confirmation message) from at least one candidate target base station, and based on the received message, can transmit an RRC reset message containing configuration information related to a conditional handover to the remote UE. At this time, the remote UE can transmit an RRC reset completion message to the base station through the relay UE in response to the reception of the RRC reset message.

[0322] As described above, the RRC reset message may include configuration information related to a conditional handover in which a trigger condition based on the reception of a notification message by the relay UE is set. For example, the RRC reset message may include configuration information for a conditional handover in which only a trigger condition based on the reception of a notification message by the relay UE is set. Additionally, the configuration information may include at least one cell ID for at least one candidate target cell to perform the conditional handover.

[0323] For example, when a notification message regarding the execution of a handover of the relay UE is received, the remote UE may trigger the execution of a conditional handover if the received notification message satisfies a specific condition. As described above, the specific condition may be satisfied if the notification message has a cause value for the handover of the relay UE, and the cell ID included in the notification message is identical to any one of the cell IDs for the at least one candidate target cell.

[0324] Specifically, the remote UE may receive a notification message through the first connection containing information regarding a cause value related to the handover of the relay UE and a first cell ID (cell identifier) ​​(S265). Here, the first cell ID may be an ID for a target base station where the relay UE completes or performs a handover. For example, the relay UE may transmit the notification message to the remote UE when it has completed the execution of a conditional handover to a target base station (in the case of Method 1 described above) or the execution of a handover (in the case of Method 2 described above). In this case, the remote UE may determine whether to trigger the conditional handover set by the configuration information based on the reception of the notification message. For example, if the first cell ID included in the notification message is the same as the cell ID included in the configuration information, the remote UE may trigger the conditional handover. In this case, the remote UE can transmit an RRC reset complete message toward the target base station corresponding to the first cell ID through the first connection while maintaining the first connection with the relay UE. For example, when the execution of the conditional handover is triggered, the remote UE can form an RRC connection with the target base station by transmitting an RRC reset complete message toward the target base station without performing a separate RACH procedure.

[0325] In contrast, if the first cell ID included in the notification message is different from at least one cell ID included in the configuration information, the remote UE may not trigger a conditional handover according to the configuration information. In this case, the remote UE may perform / trigger a procedure to re-select the relay UE based on the reception of the notification message.

[0326] Figure 27 is a diagram illustrating how a relay UE performs a handover procedure.

[0327] As described above, the relay UE can be a UAV UE or an AAM UE that relays data between a UE of a passenger aboard a UAV or AAM and a base station. Since the relay UE can move at high speeds at high altitudes, the channel state may fluctuate rapidly. Such rapid fluctuations in the channel state can be recognized or predicted by the base station through measurement reports from the relay UE. Upon predicting or detecting rapid fluctuations in the relay UE's channel state, the base station may transmit an RRC reset message to the relay UE and / or remote UE that includes configuration information related to a conditional handover for the relay UE and / or remote UE.

[0328] Specifically, referring to FIG. 27, a relay UE can establish a first connection with a remote UE for U2N (UE-to-Network) relay (S271). For example, as described with reference to FIG. 13, the relay UE can be directly connected to a serving base station / serving gNB, discover a remote UE through a discovery procedure, and establish an SL connection with the discovered remote UE. In this case, the relay UE can relay messages / data between the remote UE and the serving base station.

[0329] Next, the relay UE can receive an RRC (Radio Resource Control) reset message (via the Uu interface) from the base station (i.e., the serving base station) (S273). For example, as described above, the relay UE can measure the signal quality for the serving base station and the signal quality for neighboring base stations, and transmit a measurement report regarding the measured signal quality to the base station. Based on the measurement report, the serving base station can determine a handover or conditional handover for the relay UE and transmit an RRC reset message to the relay UE that includes configuration information regarding the configuration information of the target base station (e.g., RACH resources, the cell ID of the target base station, C-RNTI, etc.). Meanwhile, if the base station predicts that the channel state of the relay UE will change rapidly based on the measurement report, it can determine a conditional handover for the remote UE connected to the relay UE and transmit an RRC reset message to the remote UE via the relay UE that includes configuration information related to the conditional handover. Meanwhile, an RRC reset message for the remote UE can be delivered to the remote UE in advance before the handover decision for the relay UE.

[0330] Next, the relay UE can perform a handover procedure for the target base station based on the RRC reset message (S275). As described above, the relay UE can perform a RACH procedure for the target base station based on the RRC reset message, and when the execution of the RACH procedure is completed, it can complete the handover procedure by sending an RRC reset completion message to the target base station.

[0331] Next, the relay UE may perform a handover procedure to the target base station, or, when the handover procedure is completed, transmit a notification message having a cause value for the execution of the relay UE's handover procedure to the remote UE through the first connection (S277). Here, the notification message may include information regarding the cause value for the relay UE's handover and the cell ID for the target cell, as described above. Additionally, as described above, the notification message may be a message for triggering the execution of a conditional handover for the remote UE. For example, the remote UE may trigger the execution of a conditional handover for the remote UE when the remote UE receives the notification message and the cell ID included in the notification message is the same as the cell ID included in the configuration information for the conditional handover.

[0332] In contrast, if the first cell ID included in the notification message is different from at least one cell ID included in the configuration information, the conditional handover may not be triggered in the remote UE, and the remote UE may perform / trigger a procedure to re-select the relay UE. In this case, the first connection between the relay UE and the remote UE may be disconnected.

[0333] In this way, the proposed invention can effectively ensure that a handover procedure to a dynamic target gNB is performed while maintaining a connection with the relay UE by pre-setting a conditional handover for the remote UE when it is predicted that frequent HOs will be performed by the relay UE. Furthermore, the proposed invention can effectively support the service continuity of the remote UE by ensuring that a rapid handover procedure to the relay UE's target gNB is performed while maintaining a connection with the relay UE, even in an environment where frequent HOs may be performed by the relay UE.

[0334] Example of a communication system to which the invention is applied

[0335] Although not limited thereto, the various descriptions, functions, procedures, proposals, methods, and / or flowcharts of the invention disclosed in this document may be applied to various fields requiring wireless communication / connection (e.g., 5G) between devices.

[0336] Examples are provided in more detail below with reference to the drawings. In the following drawings and descriptions, the same reference numerals may represent the same or corresponding hardware blocks, software blocks, or function blocks unless otherwise described.

[0337] FIG. 28 illustrates a communication system to which the present invention is applied.

[0338] Referring to FIG. 28, the communication system (1) to which the present invention applies includes a wireless device, a base station, and a network. Here, the wireless device refers to a device that performs communication using wireless access technology (e.g., 5G NR (New RAT), LTE (Long Term Evolution)) and may be referred to as a communication / wireless / 5G device. Although not limited thereto, the wireless device may include a robot (100a), a vehicle (100b-1, 100b-2), an XR (eXtended Reality) device (100c), a hand-held device (100d), a home appliance (100e), an IoT (Internet of Thing) device (100f), and an AI device / server (400). For example, the vehicle may include a vehicle equipped with wireless communication functions, an autonomous vehicle, a vehicle capable of performing inter-vehicle communication, etc. Here, the vehicle may include an Unmanned Aerial Vehicle (UAV) (e.g., a drone). XR devices include AR (Augmented Reality) / VR (Virtual Reality) / MR (Mixed Reality) devices and can be implemented in the form of HMDs (Head-Mounted Devices), HUDs (Head-Up Displays) equipped in vehicles, televisions, smartphones, computers, wearable devices, home appliances, digital signage, vehicles, robots, etc. Portable devices may include smartphones, smartpads, wearable devices (e.g., smartwatches, smart glasses), computers (e.g., laptops, etc.). Home appliances may include TVs, refrigerators, washing machines, etc. IoT devices may include sensors, smart meters, etc. For example, base stations and networks may be implemented as wireless devices, and a specific wireless device (200a) may operate as a base station / network node to other wireless devices.

[0339] Wireless devices (100a to 100f) can be connected to a network (300) through a base station (200). Artificial Intelligence (AI) technology may be applied to the wireless devices (100a to 100f), and the wireless devices (100a to 100f) can be connected to an AI server (400) through the network (300). The network (300) can be configured using a 3G network, a 4G (e.g., LTE) network, or a 5G (e.g., NR) network. The wireless devices (100a to 100f) may communicate with each other through the base station (200) / network (300), but they may also communicate directly (e.g., sidelink communication) without going through the base station / network. For example, vehicles (100b-1, 100b-2) can communicate directly (e.g., V2V (Vehicle to Vehicle) / V2X (Vehicle to everything) communication). Also, IoT devices (e.g., sensors) can communicate directly with other IoT devices (e.g., sensors) or other wireless devices (100a to 100f).

[0340] Wireless communication / connection (150a, 150b, 150c) can be established between wireless devices (100a~100f) / base station (200) and base station (200) / base station (200). Here, wireless communication / connection can be achieved through various wireless access technologies (e.g., 5G NR), such as uplink / downlink communication (150a), sidelink communication (150b) (or D2D communication), and inter-base station communication (150c) (e.g., relay, IAB (Integrated Access Backhaul)). Through wireless communication / connection (150a, 150b, 150c), wireless devices and base stations / wireless devices, and base stations and base stations can transmit / receive wireless signals to / from each other. For example, wireless communication / connection (150a, 150b, 150c) can transmit / receive signals through various physical channels. To this end, based on various proposals of the present invention, at least some of the following may be performed: various configuration information setting processes for transmitting / receiving wireless signals, various signal processing processes (e.g., channel encoding / decoding, modulation / demodulation, resource mapping / demapping, etc.), resource allocation processes, etc.

[0341] Example of a wireless device to which the present invention is applied

[0342] FIG. 29 illustrates a wireless device that can be applied to the present invention.

[0343] Referring to FIG. 29, the first wireless device (100) and the second wireless device (200) can transmit and receive wireless signals through various wireless access technologies (e.g., LTE, NR). Here, {the first wireless device (100), the second wireless device (200)} may correspond to {wireless device (100x), base station (200)} and / or {wireless device (100x), wireless device (100x)} of FIG. 28.

[0344] The first wireless device (100) includes one or more processors (102) and one or more memories (104), and may additionally include one or more transceivers (106) and / or one or more antennas (108). The processor (102) controls the memory (104) and / or transceivers (106) and may be configured to implement the descriptions, functions, procedures, proposals, methods and / or flowcharts of operation disclosed in this document. For example, the processor (102) may process information within the memory (104) to generate a first information / signal and then transmit a wireless signal containing the first information / signal through the transceiver (106). Additionally, the processor (102) may receive a wireless signal containing a second information / signal through the transceiver (106) and then store information obtained from the signal processing of the second information / signal in the memory (104). The memory (104) may be connected to the processor (102) and may store various information related to the operation of the processor (102). For example, the memory (104) may store software code containing instructions for performing some or all of the processes controlled by the processor (102) or for performing the descriptions, functions, procedures, proposals, methods, and / or operation sequence diagrams disclosed in this document. Here, the processor (102) and the memory (104) may be part of a communication modem / circuit / chipset designed to implement wireless communication technology (e.g., LTE, NR). The transceiver (106) may be connected to the processor (102) and may transmit and / or receive wireless signals through one or more antennas (108). The transceiver (106) may include a transmitter and / or receiver. The transceiver (106) may be combined with an RF (Radio Frequency) unit. In the present invention, the wireless device may refer to a communication modem / circuit / chipset.

[0345] Specifically, the first wireless device or remote UE (100) may include a processor (102) connected to a transceiver (106) and a memory (104). The memory (104) may include at least one program capable of performing operations related to the embodiments described in FIGS. 24 through 27. The operations may include forming a first connection with the relay UE (User Equipment) for connection with the base station through the relay UE and receiving an RRC (Radio Resource Control) reset message from the base station through the first connection, and the RRC reset message may include setting information related to a conditional handover triggered based on the reception of a notification message from the relay UE.

[0346] Alternatively, a processing device may be configured including a processor (102) and a memory (104) for controlling a remote UE. In this case, the processing device may include at least one processor; and at least one memory connected to the at least one processor and storing instructions that perform operations when executed by the at least one processor. The operations may include forming a first connection with the relay UE for connection with the base station through the relay UE (User Equipment) and receiving an RRC (Radio Resource Control) reset message from the base station through the first connection, and the RRC reset message may include setting information related to a conditional handover triggered based on the reception of a notification message from the relay UE. Alternatively, at least one non-transient computer-readable medium may be configured that stores programs / instructions for performing the above-described operations.

[0347] The second wireless device (200) includes one or more processors (202) and one or more memories (204), and may additionally include one or more transceivers (206) and / or one or more antennas (208). The processor (202) controls the memory (204) and / or transceivers (206) and may be configured to implement the descriptions, functions, procedures, proposals, methods and / or operation sequences disclosed in this document. For example, the processor (202) may process information within the memory (204) to generate a third information / signal and then transmit a wireless signal containing the third information / signal through the transceiver (206). Additionally, the processor (202) may receive a wireless signal containing a fourth information / signal through the transceiver (206) and then store information obtained from the signal processing of the fourth information / signal in the memory (204). The memory (204) may be connected to the processor (202) and may store various information related to the operation of the processor (202). For example, the memory (204) may store software code containing instructions for performing some or all of the processes controlled by the processor (202) or for performing the descriptions, functions, procedures, proposals, methods, and / or operation sequence diagrams disclosed in this document. Here, the processor (202) and the memory (204) may be part of a communication modem / circuit / chip designed to implement wireless communication technology (e.g., LTE, NR). The transceiver (206) may be connected to the processor (202) and may transmit and / or receive wireless signals through one or more antennas (208). The transceiver (206) may include a transmitter and / or receiver. The transceiver (206) may be interchangeable with an RF unit. In the present invention, the wireless device may refer to a communication modem / circuit / chip.

[0348] Specifically, the second wireless device or relay UE (200) may include a processor (202) and a memory (204) connected to a transceiver or RF transceiver (206). The memory (204) may include at least one program capable of performing operations related to the embodiments described in FIGS. 24 through 27. The operations may include forming a first connection with a remote UE for U2N (UE-to-Network) relay, receiving an RRC (Radio Resource Control) reset message from a base station, performing a handover procedure to a target base station based on the RRC reset message, and transmitting a notification message through the first connection to trigger a conditional handover of the remote UE based on the completion of the handover procedure.

[0349] Hereinafter, hardware elements of the wireless device (100, 200) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (102, 202). For example, one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as PHY, MAC, RLC, PDCP, RRC, SDAP). One or more processors (102, 202) may generate one or more Protocol Data Units (PDUs) and / or Service Data Units (SDUs) according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed in this document. One or more processors (102, 202) may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed in this document. One or more processors (102, 202) may generate a signal (e.g., baseband signal) containing a PDU, SDU, message, control information, data, or information according to the functions, procedures, proposals, and / or methods disclosed in this document and provide it to one or more transceivers (106, 206). One or more processors (102, 202) may receive a signal (e.g., baseband signal) from one or more transceivers (106, 206) and may obtain a PDU, SDU, message, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this document.

[0350] One or more processors (102, 202) may be referred to as a controller, microcontroller, microprocessor, or microcomputer. One or more processors (102, 202) may be implemented by hardware, firmware, software, or a combination thereof. For example, one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), one or more Digital Signal Processing Devices (DSPDs), one or more Programmable Logic Devices (PLDs), or one or more Field Programmable Gate Arrays (FPGAs) may be included in one or more processors (102, 202). The descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this document may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, etc. Firmware or software configured to perform the descriptions, functions, procedures, proposals, methods, and / or operation sequences disclosed in this document may be contained in one or more processors (102, 202) or stored in one or more memories (104, 204) and driven by one or more processors (102, 202). The descriptions, functions, procedures, proposals, methods, and / or operation sequences disclosed in this document may be implemented using firmware or software in the form of code, instructions, and / or sets of instructions.

[0351] One or more memories (104, 204) may be connected to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, code, instructions, and / or commands. One or more memories (104, 204) may be composed of ROM, RAM, EPROM, flash memory, hard drive, registers, cache memory, computer read storage media, and / or combinations thereof. One or more memories (104, 204) may be located inside and / or outside of one or more processors (102, 202). Additionally, one or more memories (104, 204) may be connected to one or more processors (102, 202) through various technologies such as wired or wireless connections.

[0352] One or more transceivers (106, 206) may transmit user data, control information, wireless signals / channels, etc., as mentioned in the methods and / or operation flowcharts, etc., of this document to one or more other devices. One or more transceivers (106, 206) may receive user data, control information, wireless signals / channels, etc., as mentioned in the descriptions, functions, procedures, proposals, methods and / or operation flowcharts, etc., disclosed in this document from one or more other devices. For example, one or more transceivers (106, 206) may be connected to one or more processors (102, 202) and may transmit and receive wireless signals. For example, one or more processors (102, 202) may control one or more transceivers (106, 206) to transmit user data, control information, or wireless signals to one or more other devices. Additionally, one or more processors (102, 202) may control one or more transceivers (106, 206) to receive user data, control information, or wireless signals from one or more other devices. Additionally, one or more transceivers (106, 206) may be connected to one or more antennas (108, 208), and one or more transceivers (106, 206) may be configured to transmit and receive user data, control information, wireless signals / channels, etc., as described in the descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed in this document through one or more antennas (108, 208). In this document, one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers (106, 206) can convert the received wireless signal / channel, etc. from an RF band signal to a baseband signal in order to process the received user data, control information, wireless signal / channel, etc. using one or more processors (102, 202).One or more transceivers (106, 206) can convert user data, control information, wireless signals / channels, etc. processed using one or more processors (102, 202) from baseband signals to RF band signals. To this end, one or more transceivers (106, 206) may include (analog) oscillators and / or filters.

[0353] Examples of wireless device applications to which the present invention is applied

[0354] FIG. 30 illustrates another example of a wireless device to which the present invention applies. The wireless device may be implemented in various forms depending on the use-example / service (see FIG. 28).

[0355] Referring to FIG. 30, the wireless device (100, 200) corresponds to the wireless device (100, 200) of FIG. 29 and may be composed of various elements, components, units / parts, and / or modules. For example, the wireless device (100, 200) may include a communication unit (110), a control unit (120), a memory unit (130), and additional elements (140). The communication unit may include a communication circuit (112) and transceiver(s) (114). For example, the communication circuit (112) may include one or more processors (102, 202) and / or one or more memories (104, 204) of FIG. 30. For example, the transceiver(s) (114) may include one or more transceivers (106, 206) and / or one or more antennas (108, 208) of FIG. 29. The control unit (120) is electrically connected to the communication unit (110), the memory unit (130), and additional elements (140) and controls the general operation of the wireless device. For example, the control unit (120) may control the electrical / mechanical operation of the wireless device based on a program / code / command / information stored in the memory unit (130). Additionally, the control unit (120) may transmit information stored in the memory unit (130) to an external (e.g., another communication device) via a wireless / wired interface through the communication unit (110), or store information received from an external (e.g., another communication device) via a wireless / wired interface through the communication unit (110) in the memory unit (130).

[0356] The additional element (140) can be configured in various ways depending on the type of wireless device. For example, the additional element (140) may include at least one of a power unit / battery, an input / output unit (I / O unit), a driving unit, and a computing unit. Although not limited thereto, the wireless device may be implemented in the form of a robot (Fig. 28, 100a), a vehicle (Fig. 28, 100b-1, 100b-2), an XR device (Fig. 28, 100c), a portable device (Fig. 28, 100d), a home appliance (Fig. 28, 100e), an IoT device (Fig. 28, 100f), a digital broadcasting terminal, a hologram device, a public safety device, an MTC device, a medical device, a fintech device (or financial device), a security device, a climate / environment device, an AI server / device (Fig. 28, 400), a base station (Fig. 28, 200), a network node, etc. Wireless devices can be used in a movable or fixed location depending on the use—e.g., service.

[0357] In FIG. 30, various elements, components, units / parts, and / or modules within the wireless device (100, 200) may be entirely interconnected via a wired interface, or at least a portion may be wirelessly connected via a communication unit (110). For example, within the wireless device (100, 200), the control unit (120) and the communication unit (110) may be wired, and the control unit (120) and the first unit (e.g., 130, 140) may be wirelessly connected via the communication unit (110). Additionally, each element, component, unit / part, and / or module within the wireless device (100, 200) may include one or more additional elements. For example, the control unit (120) may be composed of one or more sets of processors. For example, the control unit (120) may be composed of a set of a communication control processor, an application processor, an Electronic Control Unit (ECU), a graphics processing processor, a memory control processor, etc. As another example, the memory unit (130) may be composed of RAM (Random Access Memory), DRAM (Dynamic RAM), ROM (Read Only Memory), flash memory, volatile memory, non-volatile memory and / or a combination thereof.

[0358] Examples of vehicles or autonomous vehicles to which the present invention is applied

[0359] FIG. 31 illustrates a vehicle or autonomous vehicle to which the present invention applies. The vehicle or autonomous vehicle may be implemented as a mobile robot, a vehicle, a train, an aerial vehicle (AV), a ship, etc.

[0360] Referring to FIG. 31, a vehicle or autonomous vehicle (100) may include an antenna unit (108), a communication unit (110), a control unit (120), a driving unit (140a), a power supply unit (140b), a sensor unit (140c), and an autonomous driving unit (140d). The antenna unit (108) may be configured as part of the communication unit (110). Blocks 110 / 130 / 140a to 140d each correspond to blocks 110 / 130 / 140 of FIG. 30.

[0361] The communication unit (110) can transmit and receive signals (e.g., data, control signals, etc.) with external devices such as other vehicles, base stations (e.g., base stations, roadside base stations (Roadside units), etc.), and servers. The control unit (120) can perform various operations by controlling elements of the vehicle or autonomous vehicle (100). The control unit (120) may include an Electronic Control Unit (ECU). The driving unit (140a) can drive the vehicle or autonomous vehicle (100) on the ground. The driving unit (140a) may include an engine, motor, power train, wheels, brakes, steering device, etc. The power supply unit (140b) supplies power to the vehicle or autonomous vehicle (100) and may include wired / wireless charging circuits, batteries, etc. The sensor unit (140c) can obtain vehicle status, surrounding environment information, user information, etc. The sensor unit (140c) may include an IMU (inertial measurement unit) sensor, a collision sensor, a wheel sensor, a speed sensor, an inclination sensor, a weight detection sensor, a heading sensor, a position module, a vehicle forward / reverse sensor, a battery sensor, a fuel sensor, a tire sensor, a steering sensor, a temperature sensor, a humidity sensor, an ultrasonic sensor, an illuminance sensor, a pedal position sensor, etc. The autonomous driving unit (140d) may implement technologies such as maintaining the driving lane, technologies for automatically adjusting speed such as adaptive cruise control, technologies for automatically driving along a predetermined path, and technologies for automatically setting a path and driving when a destination is set.

[0362] For example, the communication unit (110) can receive map data, traffic information data, etc. from an external server. The autonomous driving unit (140d) can generate an autonomous driving path and a driving plan based on the acquired data. The control unit (120) can control the drive unit (140a) so that the vehicle or the autonomous vehicle (100) moves along the autonomous driving path according to the driving plan (e.g., speed / direction control). During autonomous driving, the communication unit (110) can acquire the latest traffic information data from an external server non-periodically and can acquire surrounding traffic information data from surrounding vehicles. Additionally, during autonomous driving, the sensor unit (140c) can acquire vehicle status and surrounding environment information. The autonomous driving unit (140d) can update the autonomous driving path and the driving plan based on the newly acquired data / information. The communication unit (110) can transmit information regarding the vehicle location, autonomous driving path, driving plan, etc. to an external server. An external server can predict traffic information data in advance using AI technology, etc., based on information collected from vehicles or autonomous vehicles, and can provide the predicted traffic information data to vehicles or autonomous vehicles.

[0363] Here, the wireless communication technology implemented in the wireless device (XXX, YYY) of this specification may include LTE, NR, and 6G, as well as Narrowband Internet of Things for low-power communication. For example, NB-IoT technology may be an example of LPWAN (Low Power Wide Area Network) technology and may be implemented according to standards such as LTE Cat NB1 and / or LTE Cat NB2, but is not limited to the names mentioned above. Additionally, or generally, the wireless communication technology implemented in the wireless device (XXX, YYY) of this specification may perform communication based on LTE-M technology. For example, LTE-M technology may be an example of LPWAN technology and may be referred to by various names such as eMTC (enhanced Machine Type Communication). For example, LTE-M technology may be implemented in at least one of various standards such as 1) LTE CAT 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-BL (non-Bandwidth Limited), 5) LTE-MTC, 6) LTE Machine Type Communication, and / or 7) LTE M, and is not limited to the names mentioned above. Additionally or generally, wireless communication technology implemented in the wireless device (XXX, YYY) of this specification may include at least one of ZigBee, Bluetooth, and Low Power Wide Area Network (LPWAN) with consideration for low-power communication, and is not limited to the names mentioned above. As an example, ZigBee technology can create personal area networks (PANs) related to small / low-power digital communication based on various standards such as IEEE 802.15.4, and may be referred to by various names.

[0364] The embodiments described above are combinations of the components and features of the present invention in a specific form. Each component or feature should be considered optional unless otherwise explicitly stated. Each component or feature may be implemented in a form not combined with other components or features. Additionally, it is possible to construct embodiments of the present invention by combining some components and / or features. The order of operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment, or may be replaced with corresponding components or features of another embodiment. It is obvious that embodiments may be constructed by combining claims that do not have an explicit citation relationship in the claims, or that new claims may be included by amendment after filing.

[0365] In this document, embodiments of the present invention are described primarily with a focus on the signal transmission and reception relationship between a terminal and a base station. This transmission and reception relationship is extended in the same or similar manner to signal transmission and reception between a terminal and a relay or between a base station and a relay. Specific operations described in this document as being performed by a base station may, in some cases, be performed by an upper node. That is, it is self-evident that various operations performed for communication with a terminal in a network consisting of multiple network nodes including a base station may be performed by the base station or other network nodes other than the base station. The base station may be replaced by terms such as fixed station, Node B, eNode B (eNB), and access point. Additionally, the terminal may be replaced by terms such as User Equipment (UE), Mobile Station (MS), and Mobile Subscriber Station (MSS).

[0366] Embodiments according to the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of implementation by hardware, one embodiment of the present invention may be implemented by one or more ASICs (application specific integrated circuits), DSPs (digital signal processors), DSPDs (digital signal processing devices), PLDs (programmable logic devices), FPGAs (field programmable gate arrays), processors, controllers, microcontrollers, microprocessors, etc.

[0367] In the case of implementation by firmware or software, an embodiment of the present invention may be implemented in the form of a module, procedure, function, etc., that performs the functions or operations described above. Software code may be stored in a memory unit and executed by a processor. The memory unit may be located inside or outside the processor and may exchange data with the processor by various means already known.

[0368] It is obvious to those skilled in the art that the present invention may be embodied in other specific forms without departing from the features of the invention. Accordingly, the foregoing detailed description should not be interpreted restrictively in all respects but should be considered exemplary. The scope of the invention shall be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the invention are included within the scope of the invention.

[0369] The embodiments of the present invention as described above can be applied to various mobile communication systems.

Claims

1. In a method using a remote UE (User Equipment), A step of forming a first connection with the relay UE for a connection with the base station through the relay UE; and The method includes the step of receiving an RRC (Radio Resource Control) reset message from the base station through the first connection. A method in which the above RRC reset message includes configuration information related to a conditional handover triggered based on the reception of a notification message of the relay UE.

2. In Paragraph 1, The method further includes the step of receiving a notification message containing information regarding a cause value and a first cell ID (cell identifier) ​​related to the handover of the relay UE through the first connection. A method in which the above conditional handover is triggered based on the fact that the above setting information includes a cell ID identical to the first cell ID.

3. In Paragraph 2, A method in which, based on the conditional handover being triggered, the remote UE transmits an RRC reset completion message toward the target base station through the first connection without performing a RACH (random access channel) procedure toward the target base station corresponding to the first cell ID.

4. In Paragraph 2, A method in which the above notification message is received at the target base station corresponding to the first cell ID based on the relay UE completing a handover procedure or a conditional handover procedure.

5. In Paragraph 1, The method further includes the step of receiving a notification message containing information regarding a cause value and a first cell ID (cell identifier) ​​related to the handover of the relay UE through the first connection. A method in which the above conditional handover is not triggered based on the fact that the above setting information does not include a cell ID identical to the first cell ID.

6. In Paragraph 1, The method further includes the step of receiving a notification message containing information regarding a cause value and a first cell ID (cell identifier) ​​related to the handover of the relay UE through the first connection. A method in which, based on the fact that the above setting information does not include a cell ID identical to the first cell ID, the remote UE triggers a re-selection procedure of the relay UE without performing the conditional handover.

7. In Paragraph 1, A method comprising the above setting information including information about at least one candidate target base station associated with the conditional handover.

8. In Paragraph 1, A method in which the above relay UE is a UE associated with a UAV (Unmanned Aerial Vehicle) or a UE associated with an AAM (Advanced Air Mobility).

9. In at least one non-transient computer-readable recording medium, Includes instructions that perform operations when executed by at least one processor, The above operations are, Forming a first connection with said relay UE for connection with a base station through relay UE (User Equipment); and It includes receiving an RRC (Radio Resource Control) reset message from the base station through the first connection, At least one non-transient computer-readable recording medium, wherein the above RRC reset message includes setting information related to a conditional handover triggered based on the reception of a notification message of the relay UE.

10. In the case of a remote UE (User Equipment), RF (Radio Frequency) transceiver; and It includes at least one processor connected to the above RF transceiver, and The above at least one processor controls the RF transceiver to form a first connection with the relay UE for connection with the base station through the relay UE, and receives an RRC (Radio Resource Control) reset message from the base station through the first connection. The above RRC reset message includes configuration information related to a conditional handover that is triggered based on the reception of a notification message from the relay UE, for a remote UE.

11. In Paragraph 10, The above at least one processor receives a notification message through the first connection containing information about a cause value and a first cell ID (cell identifier) ​​related to the handover of the relay UE, and The above conditional handover is triggered based on the fact that the above setting information includes a cell ID identical to the first cell ID, for a remote UE.

12. In a processing device for controlling a remote UE (User Equipment), At least one processor; and The remote UE includes at least one memory connected to the at least one processor and storing instructions, wherein the instructions are executed by the at least one processor. Forming a first connection with the relay UE for connection with the base station through the relay UE; and A Radio Resource Control (RRC) reset message is received from the base station through the first connection, and A processing device in which the above RRC reset message includes setting information related to a conditional handover triggered based on the reception of a notification message of the relay UE.

13. In a method using a relay UE (User Equipment), A step of forming a first connection with a remote UE for a U2N (UE-to-Network) relay; A step of receiving an RRC (Radio Resource Control) reset message from a base station; A step of performing a handover procedure for a target base station based on the above RRC reset message; and A method of transmitting a notification message through the first connection to trigger a conditional handover of the remote UE based on the completion of the handover procedure.

14. In Paragraph 13, A method in which the above notification message includes information regarding the cause value for the handover of the relay UE and the cell ID (cell identifier) ​​of the target base station.

15. In a relay UE (User Equipment), RF (Radio Frequency) transceiver; and It includes at least one processor connected to the above RF transceiver, and A relay UE, wherein at least one processor controls the RF transceiver to form a first connection with a remote UE for a U2N (UE-to-Network) relay, receives a Radio Resource Control (RRC) reset message from a base station, performs a handover procedure for a target base station based on the RRC reset message, and transmits a notification message through the first connection to trigger a conditional handover of the remote UE based on the completion of the handover procedure.

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