Method for performing relay communication in wireless communication system, and device therefor

Abstract

A device according to various embodiments may: establish a first connection with a parent relay UE; establish a second connection with a child relay UE; receive an initial radio resource control (RRC) message of a remote UE through the second connection; transfer the initial RRC message of the remote UE through the first connection; and transmit, through the first connection, a first message including identification information for notifying, on the basis of switching from an RRC idle state or an RRC inactive state to an RRC connected state, a base station that the first relay UE is an intermediate relay UE related to the remote UE.

Description

Method for performing relay communication in a wireless communication system and device for the same

[0001] This relates to a method for performing multi-hop relay in a wireless communication system and 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, various V2X scenarios regarding V2X communication 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 multi-hop U2N relay communication 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 first relay UE (User Equipment) according to one aspect may include the steps of: forming a first connection with a parent relay UE; forming a second connection with a child relay UE; receiving an initial RRC (radio resource control) message of a remote UE through the second connection; transmitting the initial RRC message of the remote UE through the first connection; and transmitting a first message through the first connection that includes identification information to inform a base station that the first relay UE is an intermediate relay UE associated with the remote UE, based on the fact that the first relay UE has transitioned from an RRC idle state or an RRC inactive state to an RRC connection state.

[0018] Alternatively, the identification information may include first identification information for identifying the remote UE and second identification information for identifying the second connection associated with the remote UE.

[0019] Alternatively, the first identification information may be a local ID (identifier) ​​assigned to the remote UE, and the second identification information may be the L2 (layer 2) ID of the child relay UE.

[0020] Alternatively, the method further includes the step of receiving control data through the first connection to notify the first relay UE, which is in the RRC idle state or the RRC inactive state, of a state change of the remote UE, wherein the state change may include information regarding a change in the RRC state of the remote UE or the release of the relay operation of the remote UE.

[0021] Alternatively, the above control data may be included in a control PDU (Protocol Data Unit) associated with the inter-UE relay adaptation protocol.

[0022] Alternatively, the above control data may be included in an inter-UE RRC message.

[0023] Alternatively, based on the reception of the control data, the first relay UE may release both the local ID associated with the remote UE and the configuration information of the second connection associated with the remote UE.

[0024] Alternatively, the control data may include a field for the number of multiple remote UEs corresponding to the state change information, and an ID (identifier) ​​field for each of the multiple remote UEs.

[0025] Alternatively, the first relay UE may receive configuration information for the second connection for multi-hop based U2N (UE-to-Network) relay communication through the first connection based on the transmission of the first message containing the identification information.

[0026] 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 may include forming a first connection with a parent relay UE (User Equipment); forming a second connection with a child relay UE; receiving an initial RRC (radio resource control) message from a remote UE through the second connection; transmitting the initial RRC message from the remote UE through the first connection; and transmitting a first message through the first connection that includes identification information to inform a base station that the first relay UE is an intermediate relay UE associated with the remote UE, based on the first relay UE transitioning from an RRC idle state or an RRC inactive state to an RRC connection state.

[0027] According to another aspect, a first relay 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 a parent relay UE and a second connection with a child relay UE, receives an initial RRC (radio resource control) message from a remote UE through the second connection, transmits the initial RRC message from the remote UE through the first connection, and transmits a first message through the first connection that includes identification information to inform a base station that the first relay UE is an intermediate relay UE associated with the remote UE, based on the transition from an RRC idle state or an RRC inactive state to an RRC connection state.

[0028] According to another aspect, a processing device controlling a first relay 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 first relay UE to: form a first connection with a parent relay UE (User Equipment); form a second connection with a child relay UE; receive an initial RRC (radio resource control) message from a remote UE through the second connection; transmit the initial RRC message from the remote UE through the first connection; and transmit a first message through the first connection that includes identification information to inform a base station that the first relay UE is an intermediate relay UE associated with the remote UE, based on the first relay UE transitioning from an RRC idle state or an RRC inactive state to an RRC connection state.

[0029] A method by a base station according to another aspect comprises the steps of: forming a first connection directly connected to a last relay UE; receiving an initial RRC message of a remote UE through the first connection; and receiving a first message of a first relay UE through the first connection, and based on the first message including first identification information of the remote UE and second identification information for a second connection associated with the remote UE, the base station can identify the first relay UE as an intermediate relay UE associated with the remote UE.

[0030] 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 directly connected to a last relay UE, receives an initial RRC message of a remote UE through the first connection, receives a first message of a first relay UE through the first connection, and based on the first message including first identification information of the remote UE and second identification information for a second connection associated with the remote UE, the base station can identify the first relay UE as an intermediate relay UE associated with the remote UE.

[0031] According to one embodiment of the present invention, multi-hop U2N relay communication can be performed more accurately and efficiently. For example, since a base station can clearly identify that a relay UE that has switched to an RRC connection state on a multi-hop U2N path is an intermediate relay UE, appropriate settings for the connection formed on the relay UE can be performed quickly and accurately.

[0032] 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.

[0033] 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.

[0034] Figure 1 is a diagram illustrating a comparison between V2X communication based on RAT prior to NR and V2X communication based on NR.

[0035] Figure 2 shows the structure of an LTE system.

[0036] Figure 3 shows the structure of the NR system.

[0037] Figure 4 shows the structure of a wireless frame of NR.

[0038] Figure 5 shows the slot structure of an NR frame.

[0039] FIG. 6 shows a communication structure that can be provided in a 6G system according to one embodiment of the present disclosure.

[0040] FIG. 7 shows an electromagnetic spectrum according to one embodiment of the present disclosure.

[0041] Figure 8 shows the radio protocol architecture for SL communication.

[0042] Figure 9 shows a terminal performing V2X or SL communication.

[0043] Figure 10 shows a resource unit for V2X or SL communication.

[0044] FIG. 11 shows an example of a BWP according to one embodiment of the present disclosure.

[0045] 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.

[0046] Figure 13 is a diagram illustrating the control plane procedure of an L2 U2N relay (UE-to-Network Relay).

[0047] Figure 14 is a diagram illustrating a 5G ProSe multi-hop U2N relay discovery procedure using Model A discovery.

[0048] Figure 15 is a diagram illustrating a 5G ProSe multi-hop U2N relay discovery procedure using Model B discovery.

[0049] Figure 16 is a diagram illustrating the operation of a multi-hop based U2N relay.

[0050] FIG. 17 is a diagram illustrating the structure of an SRAP header according to one embodiment.

[0051] FIG. 18 is a diagram illustrating the structure of an SRAP control PDU according to one embodiment.

[0052] FIG. 19 is a diagram illustrating how a first relay UE performs multi-hop based U2N relay communication.

[0053] Figure 20 is a diagram illustrating how a base station performs multi-hop based U2N relay communication.

[0054] FIG. 21 illustrates a communication system to which the present invention is applied.

[0055] FIG. 22 illustrates a wireless device that can be applied to the present invention.

[0056] FIG. 23 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.

[0057] FIG. 24 illustrates a vehicle or autonomous vehicle to which the present invention is applied.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] Figure 3 shows the structure of the NR system.

[0071] 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.

[0072] Figure 4 shows the structure of a wireless frame of NR.

[0073] 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).

[0074] 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).

[0075] 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.

[0076] 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

[0077] 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.

[0078] SCS (15*2 u )N slot symb N frame,u slot N subframe,u slot 60KHz (u=2)12404

[0079] 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.

[0080] 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.

[0081] 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).

[0082] Frequency Range designationCorresponding frequency rangeSubcarrier Spacing (SCS)FR1450MHz - 6000MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0083] 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).

[0084] Frequency Range designationCorresponding frequency rangeSubcarrier Spacing (SCS)FR1410MHz - 7125MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0085] Figure 5 shows the slot structure of an NR frame.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] New network characteristics in 6G may be as follows.

[0091] - Satellite Integrated Network

[0092] - 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).

[0093] - Seamless integration of wireless information and energy transfer

[0094] - 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.

[0095] Some general requirements regarding the new network characteristics of 6G mentioned above may be as follows.

[0096] - Small cell networks

[0097] - Ultra-dense heterogeneous network

[0098] - High-capacity backhaul

[0099] - 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.

[0100] - Softwarization and virtualization

[0101] The core implementation technologies of the 6G system are described below.

[0102] - 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.

[0103] - 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.

[0104] 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.

[0105] - Large-scale MIMO technology

[0106] - Hologram beamforming (HBF)

[0107] - Optical wireless technology

[0108] - Free Space Optical Transmission Backhaul Network (FSO backhaul network)

[0109] - Quantum communication

[0110] - Cell-free communication

[0111] - Integration of wireless information and power transmission

[0112] - Integration of wireless communication and sensing

[0113] - Integrated access and backhaul network

[0114] - Big data analysis

[0115] - Reconfigurable intelligent metasurface

[0116] - Metaverse

[0117] - blockchain

[0118] - 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.

[0119] - 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.

[0120] 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.

[0121] The Sidelink Synchronization Signal (SLSS) and synchronization information are described below.

[0122] 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-SSS to obtain detailed synchronization and detect a synchronization signal ID.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] Figure 9 shows a terminal performing V2X or SL communication.

[0130] 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).

[0131] 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.

[0132] 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.

[0133] 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.

[0134] Figure 10 shows a resource unit for V2X or SL communication.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] (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.

[0139] (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.

[0140] (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.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] 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-SSS to obtain detailed synchronization and detect the synchronization signal ID.

[0146] 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).

[0147] 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.

[0148] 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.

[0149] 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.

[0150] 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.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] Figure 13 is a diagram illustrating the control plane procedure of an L2 U2N relay (UE-to-Network Relay).

[0157] 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.

[0158] 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.

[0159] A specified scenario (TS 38.300) describes the control plane procedure of the L2 U2N relay as follows.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] 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.

[0165] 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.

[0166] 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.

[0167] In the above scenario, in addition to the connection setup procedure, for the L2 UE-to-Network relay:

[0168] - The RRC reconfiguration and RRC disconnection procedures can reuse legacy RRC procedures along with the message content / configuration design left in the WI stage.

[0169] - 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.

[0170] 5G ProSe Multi-hop U2N Relay Discovery Procedure

[0171] Figure 14 is a diagram illustrating a 5G ProSe (Proximity-based Services) multi-hop U2N relay discovery procedure using Model A discovery.

[0172] The 5G ProSe remote UE, 5G ProSe intermediate U2N relay, and 5G ProSe U2N relay are (pre)configured or provisioned with relevant information to support multi-hop U2N relay discovery. If the 5G ProSe remote UE, 5G ProSe intermediate U2N relay, and 5G ProSe U2N relay belong to different PLMNs, it can be ensured that their respective HPLMNs are provided with a consistent configuration.

[0173] 1. If the 5G ProSe U2N relay has been successfully registered and authorized by the 5GS and is configured to operate as a multi-hop U2N relay in the current area, the discovery procedure may be initiated. Otherwise, 5G ProSe multi-hop U2N relay discovery must not be performed, and no notification message is transmitted.

[0174] 2. The 5G ProSe U2N relay transmits a 5G ProSe U2N relay Discovery Announcement message. To support multi-hop U2N relay discovery, the 5G ProSe U2N relay can set the Hop-Count to 1 and set the Announcer Info to its own User Info ID.

[0175] 3. The 5G ProSe intermediate U2N relay generates a discovery entry based on the received 5G ProSe U2N relay discovery notification message. This is provided that the message satisfies the AS layer criteria and that the Hop-Count is smaller than the (pre)configured maximum hop count for the relevant RSC (Reference Signal Carrier) and the optional Hop-Limit within the message.

[0176] The discovery entry contains the following information: RSC, (optional) Root relay Info, Announcer Info, Hop-Count, (optional) Cumulative QoS for the PC5 link, (optional) NCGI, (optional) RRC Container. Announcer Info is set to the Announcer Info of the received message. Root relay Info is set to the Root relay Info of the received message. Hop-Count is set to the value of the received message.

[0177] If accumulated QoS information exists in the received discovery message, it is updated based on the QoS of the PC5 link between the 5G ProSe intermediate U2N relay and the message sender. If a discovery entry with the same RSC and (optional) Root relay Info already exists, and the Hop-Count of the received message is smaller than the Hop-Count of the stored discovery entry, the 5G ProSe intermediate U2N relay updates the discovery entry with that message. In this case, the Announcer Info and Hop-Count are set to the values ​​of the newly received discovery message.

[0178] Meanwhile, depending on the implementation, the 5G ProSe intermediate U2N relay may decide to update the discovery item by considering the Hop-Count instead of or together with the Hop-Count and accumulated PC5 QoS information.

[0179] 4a. The 5G ProSe intermediate U2N relay sends a 5G ProSe U2N relay discovery notification message using the information from the stored discovery entry. The Hop-Count value is incremented by 1, and the Announcer Info is set to the User Info of the corresponding 5G ProSe intermediate U2N relay. If this message is received by a 5G ProSe remote UE, and the Hop-Count within the message is less than or equal to the (pre)configured maximum hop count and optional Hop-Limit for the relevant RSC, it is used for relay (re)selection. Additionally, the 5G ProSe remote UE may consider the accumulated PC5 link QoS. For relay reselection, the Root relay Info can be used to prioritize the relay providing a connection to the same 5G ProSe U2N relay.

[0180] 4b. The 5G ProSe intermediate U2N relay transmits a 5G ProSe U2N relay discovery notification message using the information of the stored discovery item, and this message can reach another 5G ProSe intermediate U2N relay.

[0181] 5. The 5G ProSe intermediate U2N relay discards a message if the Hop-Count of the received message is not less than the (pre)configured maximum hop count and optional Hop-Limit for the relevant RSC.

[0182] 6. Depending on the implementation, the 5G ProSe intermediate U2N relay sets a locally configured timer for each discovery item.

[0183] If a 5G ProSe intermediate U2N relay does not have an active PC5 link with the relay identified by the Announcer Info of the discovery item and has not received a new notification message from that relay, remove the discovery item and stop sending the related 5G ProSe U2N relay discovery notification message.

[0184] Depending on the configuration, the 5G ProSe intermediate U2N relay may need to establish a Layer-2 link before sending a 5G ProSe U2N relay discovery notification message to the relay identified by the Announcer Info of the discovery item.

[0185] Figure 15 is a diagram illustrating a 5G ProSe multi-hop U2N relay discovery procedure using Model B discovery.

[0186] 1. The 5G ProSe Remote UE determines a Hop-Limit for discovery based on policy configurations (e.g., mapping between the maximum number of hops and the RSC) or QoS requirements. If the Hop-Limit is determined based on a configuration associated with the RSC, the 5G ProSe Remote UE does not include the Hop-Limit in the Solicitation message. Otherwise, the 5G ProSe Remote UE includes the Hop-Limit in the Solicitation message.

[0187] 2a. The 5G ProSe Remote UE transmits a 5G ProSe U2N relay discovery solicitation message. The 5G ProSe U2N relay discovery solicitation message additionally includes the following information elements (IE) compared to the existing single-hop 5G ProSe U2N relay discovery solicitation message: an indication that multi-hop relay is supported, a hop count, and a Hop-Limit. Target Info may include the User Info IDs of the U2N relay and the intermediate U2N relay.

[0188] 3a. If the received Solicitation message contains an indication that a multi-hop relay is supported, the RSC within the message matches one of the (pre-)configured RSCs of the intermediate U2N relay, and the Target Info matches the User Info ID of the corresponding 5G ProSe intermediate U2N relay, the intermediate U2N relay may decide to send a 5G ProSe U2N relay discovery Solicitation message. If the hop count (corresponding to the number of relays included in the message) contained in the received Solicitation message reaches the Hop-Limit or the (pre-)configured maximum hop number associated with the RSC, the 5G ProSe intermediate U2N relay must discard the message. If the 5G ProSe intermediate U2N relay has already discovered or established a PC5 link with one or more 5G ProSe U2N relays, it may send a Response message instead of sending a Solicitation message. For example, steps 4a through 7a described below are omitted, and step 8a is performed directly. The Response message additionally includes the User Info ID of the U2N relay and path information to the U2N relay, and the path information is a list of User Info IDs of intermediate U2N relays (in order). If the same Remote UE and U2N relay User Info ID information is received from different ProSe UEs, the 5G ProSe intermediate U2N relay may select a Solicitation message to send to the next hop based on various criteria (e.g., hop count, delay, channel quality of the received message, etc.).

[0189] 4a. When a 5G ProSe intermediate U2N relay transmits a Solicitation message, it additionally includes its User Info ID in the message. For example, the message contains routing information consisting of an ordered list of User Info IDs and Layer-2 IDs of the relays that relayed the Solicitation message. The hop count is incremented by 1. The Solicitation message may include cumulative QoS information for the PC5 link. If the received Solicitation message contains cumulative QoS information, such information is updated to include the PC5 link QoS between the 5G ProSe intermediate relay and the child UE (intermediate relay UE or remote UE).

[0190] 2b.~5b. Solicitation messages from the same Remote UE are transmitted through a list of 5G ProSe intermediate U2N relays in a different order.

[0191] 6~7. If the RSC included in the Solicitation message matches one of the (pre)configured RSCs for the 5G ProSe U2N relay and the Target Info matches the User Info ID of the 5G ProSe U2N relay, the 5G ProSe U2N relay sends a 5G ProSe U2N relay Discovery Response message to the 5G ProSe intermediate U2N relay. The Response message additionally includes path information. The Response message may include received PC5 link cumulative QoS information.

[0192] The 5G ProSe U2N relay can select a path based on criteria such as the PC5 signal strength of each received message, the number of hops to the remote UE, path information, and cumulative QoS.

[0193] Meanwhile, the decision on when the 5G ProSe U2N relay will send a relay discovery response message depends on the implementation.

[0194] 8~9. When a 5G ProSe U2N relay discovery response message is received, if the User Info ID of the received 5G ProSe intermediate U2N relay is included in the route information, the 5G ProSe intermediate U2N relay delivers the response message. The response message additionally includes route information consisting of a list of User Info IDs of the intermediate U2N relays and the remote UE, following the order from the remote UE to the last 5G ProSe intermediate U2N relay.

[0195] Based on the path information, the relay discovery response message is transmitted along the path, and each 5G ProSe intermediate U2N relay determines next-hop information (User Info ID and Layer-2 ID, etc.) and transmits the message. The response message may include received accumulated PC5 QoS information.

[0196] 10. When a remote UE receives multiple Discovery Response messages within a pre-configured time window, it may perform relay path selection based on, for example, path information, PC5 signal strength between the remote UE and an adjacent intermediate U2N relay, cumulative QoS, number of hops to the 5G ProSe U2N relay, etc.

[0197] Meanwhile, if the 5G ProSe Remote UE does not receive any response within a pre-configured time, it can increase the Hop-Limit and resend the discovery message according to application requirements.

[0198] The following describes the Indirect path failure information procedure. The purpose of this procedure is to notify the network of an indirect path failure experienced by the MP remote UE.

[0199] In the case of MP (multipath), if one of the following conditions is satisfied and MCG transmission and indirect path transmission are stopped (if not suspended), the MP remote UE initiates a procedure to report an indirect path failure:

[0200] 1> When an SL indirect path failure occurs on the PC5 unicast link due to a sidelink radio link failure, or when a NotificationMessageSidelink is received from an L2 U2N Relay UE (except when indicating relayUE-HO), an SL indirect path addition / change failure, or when a request for PC5-RRC connection release by an upper layer occurs, or

[0201] 1> Cases where an N3C indirect path failure is detected, including an N3C connection failure, a Uu failure of an N3C relay UE using an N3C indirect path, or an N3C indirect path addition / change failure.

[0202] When the procedure is initiated, the UE performs the following:

[0203] 1> If the procedure is initiated to report an SL indirect path failure:

[0204] 2> Initialize the sidelink specific MAC of the L2 U2N relay UE;

[0205] 2> Stop T421 if it is running;

[0206] 1> Suspend indirect path transmission for all SRBs and DRBs;

[0207] 1> Initiates the transmission of the IndirectPathFailureInformation message.

[0208] Next, the determination of the failure type may be as follows.

[0209] An L2 U2N Remote UE with an SL indirect path configured must set the indirect path failure type according to the following conditions:

[0210] 1> If the UE initiates the transmission of the IndirectPathFailureInformation message due to 5. T421 expiry:

[0211] 2>Set failureTypeIndirectPath to t421-Expiry;

[0212] 1> When the UE initiates the transmission of an IndirectPathFailureInformation message due to the reception of a NotificationMessageSidelink containing indicationType:

[0213] 2>Set failureTypeIndirectPath to the indicationType value received from NotificationMessageSidelink (excluding relayUE-CellReselection);

[0214] 1> When the UE initiates the transmission of an IndirectPathFailureInformation message due to a sidelink radio link failure:

[0215] 2>Set failureTypeIndirectPath to sl-Failure;

[0216] 1> When the UE initiates the transmission of an IndirectPathFailureInformation message due to a PC5-RRC connection release caused by a request from the upper layer 5:

[0217] 2> Set failureTypeIndirectPath to sl-PC5-Release;

[0218] 1> If the (target) L2 U2N Relay UE identified by the sl-IndirectPathRelayUE-Identity specified in the received sl-IndirectPathAddChange changes the serving cell to a cell other than the target cell specified by the sl-IndirectPathCellIdentity in sl-IndirectPathAddChange during path addition or modification; or

[0219] 1> If the UE initiates the transmission of an IndirectPathFailureInformation message due to an N3C Indirect path addition / change failure:

[0220] 2>Set failureTypeIndirectPath to indirectPathAddChangeFailure;

[0221] The N3C remote UE must be configured with the indirect path failure type as follows:

[0222] 1> If the UE initiates the transmission of an IndirectPathFailureInformation message due to an N3C connection failure:

[0223] 2>Set failureTypeIndirectPath to n3c-Failure;

[0224] 1> When the UE initiates the transmission of an IndirectPathFailureInformation message due to a Uu radio link failure on the N3C indirect path:

[0225] 2>Set failureTypeIndirectPath to relayUE-Uu-RLF;

[0226] Method for reporting the status of a relay UE / remote UE

[0227] FIG. 16 is a diagram illustrating multi-hop based U2N relay operation, FIG. 17 is a diagram illustrating the structure of an SRAP header according to one embodiment, and FIG. 18 is a diagram illustrating the structure of an SRAP control PDU according to one embodiment.

[0228] Referring to FIG. 16, a remote UE can be connected to a base station (gNB) through a first intermediate relay UE, a second intermediate relay UE, and a last relay UE. Meanwhile, in multi-hop based U2N relay communication, a relay UE connected in the upstream or uplink (UL) direction can be defined as a parent relay UE or parent UE, and a relay UE (and / or remote UE) connected in the downstream or downlink (DL) direction can be defined as a child relay UE or child UE. For example, from the perspective of the second intermediate relay UE, the last relay UE can be defined as a parent relay UE or parent UE, and the first intermediate relay UE can be defined as a child relay UE or child UE.

[0229] A remote UE may transmit an initial RRC message (e.g., an RRCSetupRequest, RRCReestablishmentRequest, or RRCResumeRequest message) toward a first intermediate relay UE via a specified SL-RLC0 (and / or SRB0). Upon receiving this, the first intermediate relay UE may transmit the received initial RRC message to a second intermediate relay UE via the specified SL-RLC0. At this time, both the first intermediate relay UE and the second intermediate relay UE may be in an RRC_IDLE state (or RRC idle state) or an RRC_INACTIVE state (or RRC inactive state). In a similar manner, an initial RRC message for establishing an RRC connection initiated by the remote UE may be transmitted to a last relay UE. At this time, the last relay UE may be in the RRC_CONNECTED state, or may initiate an operation to become the RRC_CONNECTED state after receiving an RRC message from the remote UE.

[0230] The local ID for the remote UE may be a value assigned by the gNB. However, since the intermediate relay UE may be in the RRC_IDLE state or the RRC_INACTIVE state, the gNB may not be able to inform the intermediate relay UE of the local ID for the remote UE via the Uu RRC message. Therefore, when the remote UE transmits an initial RRC message toward the gNB, the remote UE may include the L2 ID of the remote UE in the SRAP header (Sidelink Relay Adaptation Protocol header) that transmits the initial UL RRC message. For example, the remote UE may add an SRAP header, as shown in FIG. 17 (a), to the initial UL RRC message and transmit it to the first intermediate relay UE. Upon receiving this, the first intermediate relay UE and the second intermediate relay UE can determine which remote UE can be connected to via which PC5 link (via the SRAP header). For example, the first intermediate relay UE and / or the second intermediate relay UE can store the correspondence / mapping relationship between the PC5 link and the L2 ID of the remote UE.

[0231] When the first RRC message (or initial RRC message) is delivered to the gNB, the gNB may assign a local ID for the remote UE. The gNB may transmit an initial RRC DL message (e.g., an RRCSetup, RRCReestablishment, or RRCResume message) to the remote UE, including the local ID for the remote UE and the L2 ID of the remote UE in the SRAP header of the initial RRC DL message. For example, the gNB may transmit to the last relay UE an SRAP header as shown in FIG. 17 (b) added to the initial UL RRC message. Here, the UE ID may refer to the local ID. The first intermediate relay UE and the second intermediate relay UE that receive the message can determine which local ID value corresponds to the L2 ID of the remote UE stored through the previously received initial RRC message (or initial UL RRC message). For example, the first intermediate relay UE and the second intermediate relay UE can correspond / map the local ID and the L2 ID of the remote UE based on the initial UL RRC message and / or the initial DL RRC message.

[0232] For example, an intermediate relay UE in the RRC_IDLE state or RRC_INACTIVE state (e.g., a first intermediate relay UE and / or a second intermediate relay UE) can store information regarding which PC5 link is reachable to the remote UE and a local ID value that can be mapped to the PC5 link, based on an initial UL / DL RRC message transmitted via SRB0. Additionally, an intermediate relay UE that has stored the linkage / mapping relationship between the PC5 link and the local ID (and / or the L2 ID of the remote UE) through the SRAP header of the initial UL / DL RRC message can determine which PC5 link to transmit the message through when it subsequently receives a message containing the local ID (e.g., UE ID). For example, if the linkage / mapping relationship between the local ID and the PC5 link is established through the initial RRC message, the subsequently transmitted UL / DL message may be transmitted including only the local ID of the remote UE, as in the existing Rel-17 U2N SRAP structure. For example, unlike the initial RRC message, subsequent UL / DL messages may not need to include the remote UE's L2 ID in the SRAP header.

[0233] In this mode of operation, if the L2 ID of the remote UE changes during operation, or if the remote UE is no longer in the RRC_CONNECTED state and is released, or transitions to the RRC_IDLE state or RRC_INACTIVE state, a method may be required for the intermediate relay UE to know this. For example, this is because it may be difficult to detect changes in the state of the remote UE using only the values ​​included in the SRAP header of the initial RRC message described earlier.

[0234] Specifically, since the method by which an intermediate relay UE determines the local ID and which PC5 link to forward the data with that local ID using the SRAP header of the initial RRC UL / DL message described above is not established through RRC messages from the gNB, there may be a disadvantage in that changes in the remote UE cannot be detected. For example, the L2 ID of a remote UE may be changed periodically for security reasons. If the L2 ID of a remote UE changes, the remote UE in the RRC_CONNECTED state can report the changed L2 ID to the gNB through its SUI (Sidelink UE Information).

[0235] Additionally, when an intermediate relay UE that was in the RRC_IDLE or RRC_INACTIVE state transitions to the RRC_CONNECTED state, the intermediate relay UE needs to inform the gNB that it is the intermediate relay UE used for communication between the gNB and the remote UE. This is because while the intermediate relay UE is in the RRC_IDLE or RRC_INACTIVE state, the gNB may not be aware of the existence of the intermediate relay UE, but once the intermediate relay UE enters the RRC_CONNECTED state, configuration for relay communication (e.g., RLC configuration, MAC configuration, and / or PHY configuration) needs to be performed for the intermediate relay UE. Therefore, the intermediate relay UE that has entered the RRC_CONNECTED state needs to report the following information to receive configuration for relay operation. Additionally, if the intermediate relay UE knows its own hop count and / or the total hop count to the remote UE, the intermediate relay UE may also report the total hop count value.

[0236] An intermediate relay UE that has switched to an RRC connection state can transmit information to the gNB that can identify the local ID for the currently stored remote UE and the PC5 link mapped to the local ID.

[0237] - For example, the PC5 destination L2 ID (e.g., the L2 ID of the relay UE in the direction of the remote UE currently directly connected to the intermediate relay UE and PC5) may be reported. As illustrated in FIG. 16, when a second intermediate relay UE in the RRC_IDLE or RRC_INACTIVE state becomes RRC_CONNECTED, the second intermediate relay UE may need to report to the gNB the L2 ID (or local ID) of the remote UE and the L2 ID of the first intermediate relay UE that can be associated with it. For example, the first intermediate relay UE may report the ID (or L2 ID) of the first intermediate relay UE that is the next intermediate relay UE in the direction of the remote UE. Alternatively, if the next UE of the intermediate relay UE that has switched to the RRC connected state is a remote UE, the ID (or L2 ID) of the remote UE may be reported to the gNB. For example, if the next UE of an intermediate relay UE that has switched to an RRC connection state is a remote UE, the intermediate relay UE may report the L2 ID of the remote UE and / or the local ID of the remote UE to the gNB.

[0238] Upon receiving this, the gNB can determine that the intermediate relay UE is an intermediate relay UE being used for a remote UE that is already in the RRC_CONNECTED state. Additionally, the gNB can determine which links of the intermediate relay UE require configuration to be performed to support relay communication. For example, the gNB can identify the direct connection (or PC5 link) associated with the intermediate relay UE and perform RLC configuration, MAC configuration, and / or PHY configuration to support relay communication for the identified direct connection.

[0239] Meanwhile, since an intermediate relay UE in the RRC_IDLE or RRC_INACTIVE state may not be able to detect changes in the state of the remote UE, the following describes in detail how the intermediate relay UE can detect changes in the state of the remote UE.

[0240] A remote UE connected to an intermediate relay UE in the RRC_IDLE or RRC_INACTIVE state may transition from the RRC_CONNECTED state to the RRC_IDLE or RRC_INACTIVE state, or the remote UE may release an operation related to the relay. In this case, the intermediate relay UE in the RRC_IDLE or RRC_INACTIVE state cannot detect this change in the state of the remote UE. For example, the intermediate relay UE cannot detect whether the remote UE no longer maintains the RRC_CONNECTED state or no longer performs relay operations through the intermediate relay UE. If the remote UE no longer performs relay / remote operations through the intermediate relay UE, the intermediate relay UE needs to release the local ID and / or mapping information associated with the remote UE that it stores. Here, the mapping information may include the L2 ID of the remote UE, association information between the links, and related settings to support relay operations, and the related settings may be RLC settings, MAC settings, and / or PHY settings. The following methods may be used to notify of changes in the state of the remote UE.

[0241] (1) Method of using SRAP control PDU

[0242] The gNB may provide information to the intermediate relay UE regarding a state change of the remote UE (release of remote / relay operation, transition to RRC_IDLE state or RRC_INACTIVE state) using an SRAP control PDU as illustrated in FIG. 18 (a). For example, the gNB may generate a control SRAP PDU containing the ID of the remote UE (e.g., UE ID), and the UE ID may be a local ID. The control SRAP PDU may indicate, through an “F” bit or an “R” bit, that the control SRAP PDU is a control PDU for releasing the remote UE (or a control PDU for notifying a state change). Additionally, as illustrated in FIG. 18 (a), the control SRAP PDU may include the number of remote UEs that have been released (or have a state change) and may include the local ID of each individual remote UE. For example, “Number of remote UEs” may indicate the number of remote UEs that need to be released, and based on the value of “Number of remote UEs”, the size of the control SRAP PDU (e.g., a size corresponding to the number of local ID fields of individual remote UEs included in the control SRAP PDU) may be determined / identified.

[0243] The control SRAP PDU described above can be transmitted to the last relay UE by the gNB. The last relay UE can generate a reconfigured SRAP control PDU based on the UE ID values ​​included in the SRAP control PDU. For example, assuming that the control SRAP PDU includes UE IDs 1, 2, 3, 4, and 5, UE IDs 1, 2, and 3 may be transmitted via PC5 Link 1 (e.g., if the remote UE corresponding to each of UE IDs 1, 2, and 3 must be reached via PC5 Link 1), and UE IDs 4 and 5 may be transmitted via PC5 Link 2 (e.g., if the remote UE corresponding to each of UE IDs 4 and 5 must be reached via PC5 Link 2). In this case, the last relay UE can generate a new control SRAP PDU based on the control SRAP PDU received from the gNB and transmit it through a PC5 link that can reach each remote UE. For example, the last relay UE can transmit a first control SRAP PDU through PC5 link 1, which is reconfigured / generated to include UE IDs 1, 2, and 3 respectively, with the number of remote UEs for PC5 link 1 set to 3, and transmit a second control SRAP PDU through PC5 link 2, which is reconfigured / generated to include UE IDs 4 and 5 respectively, with the number of remote UEs for PC5 link 2 set to 2.

[0244] In relation to the operation of reconstructing such an SRAP PDU, each intermediate relay UE that receives the SRAP PDU may also perform an operation similar to that of the last relay UE described above. For example, each intermediate relay UE may identify the PC5 link that must be used to reach the corresponding remote UE based on the ID of the remote UE included in the SRAP PDU it received, and reconstruct the SRAP PDU based on the identification result. This is because, if the IDs of the remote UEs are different, the remote UEs may be connected to the intermediate relay UE through different PC5 links. For example, a message corresponding to the ID of the first remote UE may need to be transmitted through the first PC5 link, and a message corresponding to the ID of the second remote UE may need to be transmitted through the second PC5 link.

[0245] Alternatively, as illustrated in FIG. 18(b), the gNB may generate a separate control SRAP PDU for each remote UE from the beginning and deliver it to the last relay UE. Upon receiving this, the last relay UE may determine which PC5 link the control SRAP PDU should be transmitted through based on the UE ID. For example, the said PC5 link may be an egress link that must be used to reach the remote UE corresponding to the UE ID. This is because the egress link corresponding to the local ID may be a value determined by the gNB's settings. Since the intermediate relay UE that receives the control SRAP PDU from the last relay UE can also independently verify the local ID and determine the egress link that maps to it, the control SRAP PDU can be delivered toward the remote UE. For example, the intermediate relay UE may specify the link / connection to deliver the control SRAP PDU based on the correspondence between the local ID and the egress link.

[0246] An intermediate relay UE that receives such a control SRAP PDU may release the corresponding local ID it stores (e.g., the local ID of a remote UE) and all information associated with said local ID. Here, said all information may include information related to the remote UE corresponding to said local ID, association information between said local ID and a link (e.g., a PC5 link), and / or related configuration information for supporting relay operation (e.g., RLC configuration, MAC configuration, and / or PHY configuration).

[0247] (2) How to use RRC messages

[0248] Information regarding the state change or release of the remote UE described above may also be transmitted / delivered via RRC messages. The gNB may transmit a Uu RRC message to the last relay UE containing information corresponding to or identical to the information contained in the control PDU (e.g., the local ID of the remote UE and an indication to show that the corresponding setting is to remove / delete / release all settings related to the remote UE). Upon receiving the Uu RRC message, the last relay UE may determine which PC5 link to transmit the message through based on the local ID of the remote UE. Additionally, the last relay UE may generate a necessary SL RRC message (e.g., an RRCReconfigurationSidelink message) and transmit it through the relevant PC5 link. An intermediate relay UE that receives the SL RRC message may also perform operations similar to those of the last relay UE described above. This is because the intermediate relay UE may have multiple PC5 links, and different remote UEs may be connected along each PC5 link.

[0249] The proposed method described above can be applied to other operations utilizing multi-hop. For example, such other operations may include multi-hop operations in IAB (Integrated Access and Backhaul), NTN (Non-Terrestrial Network), and / or IoT (Internet of Things) environments. Additionally, the PC5 link may be replaced with a simple link. For example, the simple link may be a wireless or wired link for inter-node connection. Furthermore, it is evident that the local ID value may be replaced with a value capable of identifying the final destination UE. For example, the value capable of identifying the final destination UE may include an identifier or address capable of distinguishing the final destination UE. Accordingly, the proposed method may be applied for the purpose of notifying changes in the state of a destination and / or releasing related information in a structure that is not under direct control from the gNB. For example, a change in the state of the destination may include a change in the connection state of the destination node or destination UE, a transition to an inactive state, or a disconnection, and the related information may include identifier information associated with the destination, link mapping information, and / or configuration information for communication support.

[0250] As described above, when an intermediate relay UE in the RRC_IDLE or RRC_INACTIVE state supports / allows relay operation for a remote UE in the RRC_CONNECTED state, the intermediate relay UE cannot receive Uu RRC configuration messages directly from the gNB. Therefore, in order for the intermediate relay UE to support multi-hop, the intermediate relay UE can directly configure the necessary mapping configuration using the SRAP header information included in the initial UL RRC message transmitted by the remote UE and the initial DL RRC message transmitted by the gNB to the remote UE. For example, the mapping configuration may be for determining the correspondence between the identification information of the remote UE and the PC5 link, and / or the data transmission path toward a specific remote UE. However, even if the configuration is made in this manner, if the remote UE becomes in the RRC_IDLE or RRC_INACTIVE state, the question arises as to how to release the remote UE-related configuration configured on the intermediate relay UE. Considering these issues, the intermediate relay UE can remove settings for remote UEs that are no longer needed through the proposed SRAP control PDU or RRC message. This method allows for the proper cleanup of remote UE configuration information that is unnecessarily maintained and enables the relevant settings of the intermediate relay UE to be properly managed even after a change in the state of the remote UE.

[0251] FIG. 19 is a diagram illustrating how a first relay UE performs multi-hop based U2N relay communication.

[0252] The first relay UE may be an intermediate relay UE that performs a multi-hop based U2N relay operation for relaying data / messages between a base station (or, gNB) and a remote UE as described in “Method for indicating the status of a relay UE / remote UE”. For example, the first relay UE may form a direct connection, SL connection, or PC5 connection with a parent UE or parent relay UE in the upstream direction toward the base station as an intermediate relay UE, and form a direct connection, SL connection, or PC5 connection with a child UE (e.g., child relay UE or remote UE) in the downstream direction toward the remote UE.

[0253] Meanwhile, in a multi-hop based U2N relay environment, an intermediate relay UE in the RRC_IDLE or RRC_INACTIVE state may not be able to receive Uu RRC configuration messages directly from the gNB. Therefore, such an intermediate relay UE can independently establish and store a correspondence relationship between the remote UE and the downlink based on header information included in the initial RRC UL message transmitted by the remote UE and the initial RRC DL message transmitted by the gNB toward the remote UE, such as header information related to the inter-UE relay adaptation protocol or SRAP header information. Below, the operations of the first relay UE are described in detail based on this.

[0254] Referring to FIG. 19, the first relay UE can form a first connection with a parent relay UE (S191). For example, the parent relay UE may be a higher relay UE that is closer to the base station than the first relay UE, a last relay UE that is directly connected to the base station, or another intermediate relay UE. For example, the parent relay UE may be a relay UE that is directly connected in the upstream direction as described above. The first connection may be a link that allows the first relay UE to transmit messages or data (e.g., data or messages from a child relay UE or remote UE) in the direction toward the base station, or to receive messages or data (e.g., data or messages from the parent relay UE or base station) from the parent relay UE (or, in the downstream direction).

[0255] The first relay UE can form a second connection with a child relay UE (S193). For example, the child relay UE may be a subordinate relay UE connected in the direction of a remote UE, and a path to finally reach the remote UE may be formed through the second connection. The second connection may be a link for the first relay UE to transmit a message or data in the direction of the remote UE or downstream, or to receive a message or data in the upstream direction.

[0256] Next, the first relay UE can receive an initial RRC message from the remote UE through the second connection (S195). Here, the first relay UE may be in an RRC (Radio Resource Control) idle state or an RRC inactive state. The initial RRC message may be a message generated by the remote UE to establish or re-establish a connection with a base station, and may include an RRCSetupRequest, an RRCReestablishmentRequest, and / or an RRCResumeRequest. For example, the initial RRC message may reach the first relay UE via a child relay UE (or the child relay UE and the child relay UE's child relay UE). As described above, the initial RRC message may be a message that includes or has an inter-UE relay adaptation protocol (or SRAP) header containing the L2 ID of the remote UE. In this case, the first relay UE may map the L2 ID of the remote UE to the second connection.

[0257] Next, the first relay UE can transmit the initial RRC message of the remote UE through the first connection (S197). Here, unlike before, the first relay UE can transmit the initial RRC message of the remote UE even in the RRC idle state or the RRC inactive state. For example, the first relay UE can transmit the initial RRC message to the base station in a multi-hop manner by transmitting the initial RRC message toward the parent relay UE. In this case, the first relay UE can recognize or store the correspondence / mapping relationship between the L2 ID corresponding to the remote UE (e.g., the L2 ID of the remote UE included in the SRAP header added to the initial RRC message) and the second connection during the transmission of the initial RRC message. In this case, even if the first relay UE is in the RRC idle state or the RRC inactive state, it can recognize, based on the corresponding relationship / mapping relationship, that the message / data containing the L2 ID or local ID of the remote UE is the message / data to be transmitted through the second connection.

[0258] Additionally, the first relay UE may receive, through the first connection, an initial RRC configuration message (e.g., an RRCReconfiguration message) containing configuration information related to relay communication for the remote UE (e.g., configuration information for forming an indirect RRC path between the remote UE and the base station through at least one relay UE) in response to the initial RRC message of the remote UE. The RRC configuration message may include or be supplemented with an SRAP header (or an inter-UE relay adaptation protocol header) containing a local ID assigned to the remote UE and an L2 ID for the remote UE. In this case, the first relay UE may store a correspondence / mapping relationship between the local ID included in the SRAP header and the L2 ID of the remote UE, and may transmit the initial RRC configuration message through the second connection mapped to the L2 ID of the remote UE. For example, the first relay UE may form a second-1 connection and a second-2 connection in the downstream direction, map the second-1 connection to a first L2 ID, and map the second-2 connection to a second L2 ID. In this case, the first relay UE may transmit the RRC setup message through the second-2 connection if the second L2 ID is included in the SRAP header of the RRC setup message. In this way, even if the first relay UE is in an RRC idle or RRC inactive state, it can clearly identify which connection the message / data destined for the remote UE should be delivered through based on the mapping relationship.

[0259] For example, as described above, a first relay UE in the RRC_IDLE state or RRC_INACTIVE state can store information regarding which second connection can be used to reach a specific remote UE and a local ID value associated with that second connection through the header of the initial UL / DL RRC message (SRAP header or inter-UE relay adaptation protocol header). Once this association is established, the first relay UE can subsequently determine which second connection to use to deliver the message based solely on the local ID value. Therefore, the header of subsequent UL / DL messages may include only the local ID of the remote UE, and the L2 ID of the remote UE may not need to be included every time.

[0260] Next, the first relay UE may transmit a first message through the first connection to indicate that the first relay UE is an intermediate relay UE, based on the transition from the RRC idle state or the RRC inactive state to the RRC connected state (S199). The first message may include identification information to inform the base station that the first relay UE is an intermediate relay UE. For example, the first message may be a report message that allows the base station to recognize that the first relay UE previously supported relay operations for a remote UE in the RRC idle state or the RRC inactive state. For example, the first message may be transmitted / reported to the base station through the first connection and the parent relay UE. Alternatively, the first message may be transmitted together with an initial RRC message for the RRC connection of the first relay UE, or may be included in the initial RRC message. Here, the identification information may include first identification information for identifying the remote UE and second identification information for identifying the second connection associated with the remote UE. For example, the first identification information may be the L2 ID of the remote UE obtained from the SRAP header of the initial RRC message of the remote UE, or the local ID of the remote UE obtained from the SRAP header of the initial RRC setup message. The second identification information may be the L2 ID of the child relay UE that has formed the second connection in the direction of the remote UE or downstream direction associated with the local ID of the remote UE. In this case, the base station can use the local ID and the second identification information to identify which link the first relay UE is performing the operation of an intermediate relay UE for which remote UE.In this way, when the first relay UE transmits the first message containing the identification information to the base station through the first connection, the base station can clearly identify that the second connection is a connection with another relay UE directed toward the remote UE. In this case, the base station may provide the first relay UE with configuration information to support relay operations to be performed through the second connection. For example, the configuration information may include relay-related configuration information for data transmission, control data transmission, and / or remote UE support through the second connection. For example, the base station may perform configurations for RLC channels / MAC / PHY, etc., for multi-hop based U2N relay communication for the second connection based on the identification information, and may transmit the configuration information for RLC channels / MAC / PHY, etc., configured for the second connection to the first relay UE.

[0261] Alternatively, the first relay UE may receive control data via the first connection that includes state change information regarding an RRC state change for the remote UE or the release of a relay operation (or remote operation) of the remote UE while in the RRC idle state or the RRC inactive state. For example, the state change information may be information or an indicator indicating when the remote UE no longer maintains an RRC connection state, or when a relay operation for the remote UE is no longer required. Such control data may be intended to allow the first relay UE, which is in the RRC idle state or the RRC inactive state, to clean up information related to the remote UE that is no longer needed. For example, the control data may be included in a control PDU associated with an inter-UE relay adaptation protocol. Alternatively, the control data may be included in an inter-UE RRC message. For example, the inter-UE RRC message may be RRC-based control data that can be transmitted between relay UEs or between nodes in the direction of the relay UE and the remote UE. In this case as well, the inter-UE RRC message may include information instructing or notifying a change in the state of the remote UE or the release of a relay operation for the remote UE. Such control data may be a message generated by a base station and transmitted to the first relay UE.

[0262] For example, the control data may include a field for the number of multiple remote UEs corresponding to the state change information and an ID (identifier) ​​field for each of the multiple remote UEs. For example, the field for the number of multiple remote UEs may indicate the number of remote UEs subject to a state change or relay operation release. Additionally, each ID field may include a value for identifying each of the multiple remote UEs, for example, a local ID or L2 ID corresponding to each remote UE. Through this, the first relay UE can collectively receive and process state change information for multiple remote UEs using a single control data.

[0263] Figure 20 is a diagram illustrating how a base station performs multi-hop based U2N relay communication.

[0264] In a multi-hop based U2N relay environment, the base station can receive an initial RRC message from a remote UE through a Uu link or Uu connection directly connected to the last relay UE, and subsequently identify the intermediate relay UE associated with the multi-hop based U2N relay based on a first message transmitted after the intermediate relay UE transitions to the RRC_CONNECTED state. For example, since the intermediate relay UE was previously in the RRC_IDLE or RRC_INACTIVE state, it may be difficult for the base station to provide relay-related settings to the intermediate relay UE through direct Uu RRC signaling; however, the existence of the intermediate relay UE and its association with the remote UE can be recognized through the first message. This is explained step-by-step below.

[0265] Referring to FIG. 20, a base station may form a first connection directly connected to a last relay UE (S201). For example, the last relay UE may be a relay UE that communicates directly with the base station in a multi-hop relay path formed in the direction of a remote UE. Additionally, the first connection may be a Uu link between the base station and the last relay UE. For example, one or more intermediate relay UEs may exist below the last relay UE, and a remote UE or another sub-relay UE may be connected below the one or more intermediate relay UEs.

[0266] Next, the base station may receive an initial RRC message from the remote UE through the first connection (S203). For example, the initial RRC message may be a message generated by the remote UE to establish, reset, or resume a connection with the base station, and may include an RRCSetupRequest, an RRCReestablishmentRequest, or an RRCResumeRequest. The initial RRC message may be transmitted to the base station in a multi-hop manner from the remote UE through one or more intermediate relay UEs and last relay UEs. For example, the remote UE may include its L2 ID in header information, such as an SRAP header or a header related to the inter-UE relay adaptation protocol, while transmitting the initial RRC message. The intermediate relay UEs may use the L2 ID to store which remote UE is reachable through which PC5 link. However, the base station may not directly recognize the existence of each intermediate relay UE in the RRC_IDLE state or RRC_INACTIVE state even after receiving the initial RRC message.

[0267] And / or, the base station may assign a local ID to the remote UE upon the request of the last relay UE (or may assign a local ID to the remote UE after receiving the initial RRC message). Additionally, the base station may transmit an initial DL RRC message, such as an RRCSetup, RRCReestablishment, or RRCResume message, toward the remote UE. In this case, the header of the initial DL RRC message may include a local ID for the remote UE and an L2 ID of the remote UE. Accordingly, intermediate relay UEs on the path may associate the previously stored L2 ID of the remote UE with the newly transmitted local ID to form a mapping relationship between the local ID of a specific remote UE and a direct connection link (e.g., a connection toward the downstream direction or toward the remote UE).

[0268] Next, the base station may receive a first message from a first relay UE containing identification information through the first connection (S205). As described above, the identification information may include a first identification information which is a local ID for the remote UE and a second identification information which is an L2 ID of a child relay UE (or a local ID of the child relay UE) for identifying a second connection associated with the L2 ID. For example, the first message may be a message that is triggered for transmission by the first relay UE when the first relay UE, which previously supported relay operations for the remote UE in the RRC_IDLE state or RRC_INACTIVE state, subsequently switches to the RRC_CONNECTED state.

[0269] For example, while the first relay UE is in the RRC_IDLE state or RRC_INACTIVE state, it may be difficult for the base station to directly determine which remote UE the first relay UE was actually operating as an intermediate relay UE for. Therefore, the first message transmitted after the first relay UE switches to the RRC_CONNECTED state may be necessary as a message for the base station to identify which remote UE the first relay UE is acting as an intermediate relay UE via which link.

[0270] For example, a base station can identify that the first relay UE is an intermediate relay UE for the remote UE based on the first identification information and the second identification information. For example, the base station can use the first identification information to identify which remote UE the first relay UE supports relay operations for, and use the second identification information to identify which link / connection the first relay UE has formed with the remote UE. Therefore, the base station does not merely recognize the last relay UE, but can also recognize through the first message that the first relay UE is an intermediate relay UE actually performing relay functions on a multi-hop path. For example, based on the identification result, the base station can provide settings for supporting relay communication to the first relay UE. The settings may be RLC, MAC, and / or PHY related settings to support data transmission or control information transmission through a second connection associated with the remote UE. In addition, if the first relay UE additionally knows its own hop count or the total hop count value to the remote UE, such information may also be included in the first message. In this case, the base station can determine the number of hops or path characteristics of the relay path more specifically.

[0271] Alternatively, the base station may transmit control data to notify the first relay UE in the RRC idle state or RRC inactive state of a change in the state of the remote UE when the remote UE switches from an RRC connected state to an RRC idle state or RRC inactive state, or when the U2N relay communication is interrupted (e.g., release of relay operation). Here, the control data may be included in a control PDU or inter-UE RRC message associated with an adaptation protocol and transmitted through the first connection so that it can be delivered to the first relay UE in the RRC idle state or RRC inactive state.

[0272] In this way, the proposed method allows the base station to clearly identify that the relay UE that has switched to an RRC connection state on a multi-hop U2N path is an intermediate relay UE, thereby enabling the appropriate setting for the connection formed on the relay UE to be performed quickly and accurately. Additionally, by newly defining control data that can instruct an intermediate relay UE not in an RRC connection state to change the state of the remote UE, the proposed method can ensure that the intermediate relay UE has the opportunity to appropriately release the setting for the remote UE to which the state change has been instructed.

[0273] Example of a communication system to which the invention is applied

[0274] 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.

[0275] 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.

[0276] FIG. 21 illustrates a communication system to which the present invention is applied.

[0277] Referring to FIG. 21, 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.

[0278] 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).

[0279] 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.

[0280] Example of a wireless device to which the present invention is applied

[0281] FIG. 22 illustrates a wireless device that can be applied to the present invention.

[0282] Referring to FIG. 22, 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. 21.

[0283] 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.

[0284] Specifically, the first wireless device or the first relay 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 with reference to FIGS. 16 through 20 in the section “Method for indicating the status of a relay UE / remote UE”. The operations may include controlling the transceiver (106) to form a first connection with a parent relay UE, forming a second connection with a child relay UE, receiving an initial RRC (radio resource control) message of the remote UE through the second connection, transmitting the initial RRC message of the remote UE through the first connection, and transmitting a first message through the first connection that includes identification information to indicate to a base station that the first relay UE is an intermediate relay UE associated with the remote UE, based on the transition from an RRC idle or RRC inactive state to an RRC connection state.

[0285] Alternatively, a processing device may be configured including a processor (102) and a memory (104) for controlling the 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 a parent relay UE, forming a second connection with a child relay UE, receiving an initial RRC (radio resource control) message from the remote UE through the second connection, transmitting the initial RRC message from the remote UE through the first connection, and transmitting a first message through the first connection that includes identification information to inform the base station that the first relay UE is an intermediate relay UE associated with the remote UE, based on the transition from an RRC idle or RRC inactive state to an RRC connection state. Alternatively, at least one non-transient computer-readable medium may be configured that stores programs / instructions for performing the above-described operations.

[0286] 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.

[0287] Specifically, the second wireless device or base station (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 with reference to FIGS. 16 through 20 in the section “Method for indicating the status of a relay UE / remote UE”. The operations include controlling the RF transceiver (206) to form a first connection directly connected to the last relay UE, receiving an initial RRC message of the remote UE through the first connection, and receiving a first message of the first relay UE through the first connection, and based on the first message containing first identification information of the remote UE and second identification information for a second connection associated with the remote UE, the base station may identify the first relay UE as an intermediate relay UE associated with the remote UE.

[0288] 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.

[0289] 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.

[0290] One or more memories (104, 204) may be connected to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. One or more memories (104, 204) may be composed of 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.

[0291] 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.

[0292] Examples of wireless device applications to which the present invention is applied

[0293] FIG. 23 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. 21).

[0294] Referring to FIG. 23, the wireless device (100, 200) corresponds to the wireless device (100, 200) of FIG. 22 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. 23. For example, the transceiver(s) (114) may include one or more transceivers (106, 206) and / or one or more antennas (108, 208) of FIG. 22. 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 the outside (e.g., another communication device) via a wireless / wired interface through the communication unit (110), or store information received from the outside (e.g., another communication device) via a wireless / wired interface through the communication unit (110) in the memory unit (130).

[0295] 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. 21, 100a), a vehicle (Fig. 21, 100b-1, 100b-2), an XR device (Fig. 21, 100c), a portable device (Fig. 21, 100d), a home appliance (Fig. 21, 100e), an IoT device (Fig. 21, 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. 21, 400), a base station (Fig. 21, 200), a network node, etc. Wireless devices can be used in a movable or fixed location depending on the use—e.g., service.

[0296] In FIG. 23, 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.

[0297] Examples of vehicles or autonomous vehicles to which the present invention is applied

[0298] FIG. 24 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.

[0299] Referring to FIG. 24, 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. 23.

[0300] 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.

[0301] 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.

[0302] 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.

[0303] 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.

[0304] 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).

[0305] 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.

[0306] 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.

[0307] 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.

[0308] The embodiments of the present invention as described above can be applied to various mobile communication systems.

Claims

1. In a method using the first relay UE (User Equipment), Step of forming a first connection with the parent relay UE; Step of forming a second connection with the child relay UE; A step of receiving an initial RRC (radio resource control) message from a remote UE through the second connection above; A step of transmitting an initial RRC message of the remote UE through the first connection; and A method comprising the step of transmitting a first message through the first connection, the message including identification information for notifying a base station that the first relay UE is an intermediate relay UE associated with the remote UE, based on the fact that the first relay UE has transitioned from an RRC idle state or an RRC inactive state to an RRC connected state.

2. In Paragraph 1, A method comprising the above identification information including a first identification information for identifying the remote UE and a second identification information for identifying the second connection associated with the remote UE.

3. In Paragraph 2, A method in which the first identification information is a local ID (identifier) ​​assigned to the remote UE, and the second identification information is the L2 (layer 2) ID of the child relay UE.

4. In Paragraph 1, The method further includes the step of receiving control data through the first connection to notify the first relay UE, which is in the RRC idle state or the RRC inactive state, of a change in the state of the remote UE. A method in which the above state change is for a change in the RRC state of the remote UE or for the release of a relay operation of the remote UE.

5. In Paragraph 4, The above control data is included in a control PDU (Protocol Data Unit) associated with the inter-UE relay adaptation protocol.

6. In Paragraph 4, The above control data is included in the inter-UE RRC message, method.

7. In Paragraph 4, A method in which, based on the reception of the above control data, the first relay UE releases both the local ID associated with the remote UE and the configuration information of the second connection associated with the remote UE.

8. In Paragraph 4, The control data comprises a field for the number of multiple remote UEs corresponding to the state change, and an ID (identifier) ​​field for each of the multiple remote UEs.

9. In Paragraph 1, A method in which the first relay UE receives configuration information for the second connection for multi-hop based U2N (UE-to-Network) relay communication through the first connection based on the transmission of the first message containing the identification information.

10. 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, Form a first connection with the parent relay UE (User Equipment); Form a second connection with the child relay UE; Receive an initial RRC (radio resource control) message from the remote UE through the second connection above; Transmit an initial RRC message of the remote UE through the first connection; and At least one non-transient computer-readable recording medium comprising transmitting a first message through the first connection, the message including identification information for notifying a base station that the first relay UE is an intermediate relay UE associated with the remote UE, based on the first relay UE transitioning from an RRC idle state or an RRC inactive state to an RRC connected state.

11. In the first relay UE (User Equipment), RF (Radio Frequency) transceiver; and It includes at least one processor connected to the above RF transceiver, and A first relay UE, wherein at least one processor controls the RF transceiver to form a first connection with a parent relay UE and a second connection with a child relay UE, receives an initial RRC (radio resource control) message of a remote UE through the second connection, transmits the initial RRC message of the remote UE through the first connection, and transmits a first message through the first connection that includes identification information to notify a base station that the first relay UE is an intermediate relay UE associated with the remote UE, based on the transition from an RRC idle state or an RRC inactive state to an RRC connection state.

12. In a processing device that controls a first relay UE (User Equipment), At least one processor; and The first relay 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. Form a first connection with the parent relay UE (User Equipment); Form a second connection with the child relay UE; Receive an initial RRC (radio resource control) message from the remote UE through the second connection above; Transmit an initial RRC message of the remote UE through the first connection; and A processing device that transmits a first message containing identification information to notify a base station that the first relay UE is an intermediate relay UE associated with the remote UE, based on the fact that the first relay UE has transitioned from an RRC idle state or an RRC inactive state to an RRC connected state.

13. In the method using a base station, A step of forming a first connection directly connected to the last relay UE (User Equipment); A step of receiving an initial RRC message of a remote UE through the first connection; and The method includes the step of receiving a first message of a first relay UE through the first connection, and A method in which, based on the fact that the first message contains first identification information of the remote UE and second identification information of a second connection associated with the remote UE, the base station identifies the first relay UE as an intermediate relay UE associated with the remote UE.

14. In Paragraph 1, A method in which the base station transmits configuration information for the second connection for the multi-hop based U2N (UE-to-Network) relay through the first connection based on the first identification information and the second identification information.

15. Regarding base stations, 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 directly connected to the last relay UE (User Equipment), receives an initial RRC message from the remote UE through the first connection, and receives a first message from the first relay UE through the first connection. A base station that identifies the first relay UE as an intermediate relay UE associated with the remote UE, based on the fact that the first message contains first identification information of the remote UE and second identification information of a second connection associated with the remote UE.

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