Method and device for performing relay communication in wireless communication system

Abstract

Disclosed are a method and a device for performing communication in a wireless communication system according to various embodiments. The device may establish a first connection with a parent relay UE, establish a second connection with a remote UE or a child relay UE, and receive a first message through the second connection.

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

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

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

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

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

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

[0015] The technical problem that the present invention aims to solve is to provide a method for performing 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 comprises the steps of: forming a first connection with a parent relay UE; forming a second connection with a remote UE or a child relay UE; and receiving a first message through the second connection, wherein the first message may be a message in which a relay protocol header including the L2 ID (layer 2 identifier) ​​of the remote UE is added to an initial RRC (radio resource control) message of the remote UE.

[0018] Alternatively, based on whether the first relay UE is in an RRC idle state or an RRC inactive state, the first relay UE may forward the first message through the first connection.

[0019] Alternatively, based on the fact that the first relay UE is in an RRC connection state, the method may further include the steps of: transmitting a message requesting the assignment of a local ID to the remote UE through the first connection; receiving information about the local ID assigned to the remote UE through the first connection; and transmitting a second message through the first connection in which the relay protocol header reconstructed based on the local ID is added to the initial RRC message of the remote UE.

[0020] Alternatively, based on the fact that the first relay UE is in an RRC connection state, the method may further include the step of transmitting a message requesting the assignment of a local ID to the remote UE through the first connection; and the step of forwarding the first message through the first connection regardless of whether information regarding the local ID assigned to the remote UE is received.

[0021] Alternatively, the method may include the step of receiving a first RRC message through the first connection that includes a local ID of the remote UE assigned by a base station in accordance with a request for the assignment of the local ID; and the step of receiving a second RRC message through the first connection that responds to an initial RRC message of the remote UE, wherein the second RRC message may have a relay protocol header attached that includes the L2 ID of the remote UE and the local ID of the remote UE.

[0022] Alternatively, the first relay UE may establish a correspondence between the L2 ID of the remote UE and the local ID of the remote UE based on the message received first among the first RRC message and the second RRC message.

[0023] Alternatively, the first relay UE may establish a correspondence relationship between the L2 ID of the remote UE and the local ID of the remote UE by prioritizing the first RRC message among the first RRC message and the second RRC message.

[0024] Alternatively, the initial RRC message of the remote UE may be an RRCSetupRequest message, an RRCReestablishmentRequest message, or an RRCResume message.

[0025] Alternatively, the first relay UE may transmit information about the switched RRC state through the second connection based on the fact that the RRC state has been switched.

[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; forming a second connection with a remote UE or a child relay UE; and receiving a first message through said second connection, said first message may be an initial RRC (radio resource control) message of said remote UE to which a Relay Protocol header including a layer 2 identifier (L2 ID) of said remote UE has been added.

[0027] According to another aspect, a first relay UE (User Equipment) includes 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 to form a second connection with a remote UE or a child relay UE, and receives a first message through the second connection, and the first message may be a message in which a relay protocol header including the L2 ID (layer 2 identifier) ​​of the remote UE is added to an initial RRC (radio resource control) message of the remote UE.

[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 are executed by the at least one processor and cause the UE to form a first connection with a parent relay UE; form a second connection with a remote UE or a child relay UE; and receive a first message through the second connection, wherein the first message may be a message in which a relay protocol header including the L2 ID (layer 2 identifier) ​​of the remote UE is added to an initial RRC (radio resource control) message of the remote UE.

[0029] A method by a remote UE (User Equipment) according to another aspect comprises the steps of: forming a first connection with a parent relay UE; and transmitting a first message for a radio resource control (RRC) connection with a base station through the first connection, wherein the first message may be a message in which a relay protocol header including the layer 2 identifier (L2 ID) of the remote UE is added to the initial RRC message of the remote UE.

[0030] According to another aspect, a remote UE (User Equipment) comprises an RF (Radio Frequency) transceiver; and at least one processor connected to the RF transceiver, wherein the at least one processor controls the RF transceiver to form a first connection with a parent relay UE and transmits a first message for a radio resource control (RRC) connection with a base station through the first connection, and the first message may be a message in which a relay protocol header including the L2 ID (layer 2 identifier) ​​of the remote UE is added to the initial RRC message of 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, by enabling the initial RRC message of a remote UE to be delivered to a parent relay UE without a separate RRC connection state transition even when an intermediate relay UE is in an RRC idle state or RRC inactive state, the delay associated with the initial connection procedure in a multi-hop U2N relay communication environment can be effectively minimized.

[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] Figure 18 is a diagram illustrating the structure of a conventional SRAP header.

[0052] FIG. 19 is a diagram illustrating a method for a first relay UE to relay an initial RRC message of a received remote UE.

[0053] Figure 20 is a diagram illustrating how a remote UE transmits an initial RRC message.

[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 ) is an example.

[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 simply 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. The 5G ProSe intermediate U2N relay sets a locally configured timer for each discovery item depending on the implementation.

[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] Operation of intermediate relay UE according to RRC status during multi-hop relay operation

[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 a conventional SRAP header.

[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 direction can also be defined as a parent relay UE or parent UE, and a relay UE (and / or remote UE) connected in the downstream 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. 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 an 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 an RRC_CONNECTED state or may initiate an operation to become an RRC_CONNECTED state after receiving the 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 RRC UL message (e.g., an initial RRC message transmitted in the upstream or uplink direction). For example, the remote UE may transmit the initial RRC UL message to the first intermediate relay UE by adding an SRAP header as shown in FIG. 17 (a). 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 a 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; e.g., an initial RRC message delivered in the downstream or downlink direction) to the remote UE, and may include 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 add an SRAP header as shown in FIG. 17 (b) to the initial RRC UL message and transmit it to the last relay UE. 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 RRC UL 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 RRC UL message and / or the initial RRC DL 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 / RRC DL 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 / RRC DL 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 via 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] When this type of operation is applied to existing Rel-17 relay operations, the behavior of the intermediate relay UE may differ from the existing Rel-17 relay operation. The following describes in detail the behavior of the intermediate relay UE upon receiving an initial RRC message when the remote UE transmits it with an additional SRAP header.

[0234] If a remote UE includes its L2 ID in the initial RRC message and sends it to an intermediate relay UE, the remote UE may not be aware of the intermediate relay UE's RRC status (or state).

[0235] When following the operation of the existing Rel-17, when an intermediate relay UE establishes an SL connection or a direct connection (or PC5 connection) with a remote UE, it may report the L2 ID of the remote UE to the base station and request a local ID for the L2 ID of the remote UE from the base station. An intermediate relay UE in an RRC IDLE / INACTIVE state may receive an initial RRC message from the remote UE (e.g., a message for establishing an RRC connection with a base station through the relay UE, e.g., RRCSetupRequest, RRCReestablishmentRequest, RRCResume). In this case, the initial RRC message may not contain an SRAP header including the L2 ID of the remote UE, and the intermediate relay UE may request a local ID from the base station to be assigned a local ID for the L2 ID of the remote UE, and may attach an SRAP header including the local ID assigned by the base station to the initial RRC message of the remote UE and transmit it to the base station.

[0236] Alternatively, when the remote UE transmits the initial RRC message by including or appending an SRAP header containing its L2 ID, a method of transmission may be considered taking into account that the intermediate relay UE is in an RRC IDLE / INACTIVE state. An intermediate relay UE in an RRC IDLE / INACTIVE state that receives an initial RRC message from the remote UE containing or appending an SRAP header containing the remote UE's L2 ID may forward the received initial RRC message to its parent relay UE. Even in this case, the remote UE may not know the RRC state of the intermediate relay UE.

[0237] To combine the two methods described above, the following method may be considered. Here, the remote UE can always send an initial RRC message to the intermediate relay UE with an SRAP header containing its L2 ID attached.

[0238] An intermediate relay UE that receives an initial RRC message to which an SRAP header containing the L2 ID of a remote UE is appended (or included) may, if in the RRC CONNECTED state, report the value of the remote UE's L2 ID included in the SRAP header to the gNB and request the assignment of a local ID for the remote UE. When the intermediate relay UE is assigned the local ID of the remote UE from the gNB and assigned an SRB bearer to transmit the initial RRC message, the intermediate relay UE may reconstruct the SRAP header and transmit it toward the gNB. For example, the intermediate relay UE may reconstruct the SRAP header appended / included in the received initial RRC message and transmit the remote UE's initial RRC message to the gNB with the reconstructed SRAP header appended / included. At this time, the intermediate relay UE may reconstruct the SRAP header to be identical to the existing Rel-17 SRAP header structure as illustrated in FIG. 18.

[0239] Alternatively, if an intermediate relay UE that receives an initial RRC message with an attached (or included) SRAP header containing the L2 ID of the remote UE is in an RRC IDLE / INACTIVE state, the intermediate relay UE may forward the initial RRC message with the attached SRAP header containing the L2 ID of the remote UE (i.e., the received message as is) to its parent relay UE.

[0240] For example, an intermediate relay UE can determine the method of transmitting the initial RRC message of a remote UE containing the SRAP header based on its RRC connection state. When the intermediate relay UE is in an RRC connection state, it may first request the base station to assign a local ID corresponding to the L2 ID of the remote UE, receive the local ID and an SRB bearer to transmit the initial RRC message from the base station, and after reconstructing the SRAP header of the received initial RRC message based on the assigned local ID and SRB bearer, it may transmit the initial RRC message with the reconstructed SRAP header added / included to the base station. Alternatively, when the intermediate relay UE is in an RRC idle state or an RRC inactive state, the intermediate relay UE may transmit the received initial RRC message of the remote UE to the parent relay UE as is. In this case, the intermediate relay UE can store the association / mapping relationship between the L2 ID of the remote UE included in the SRAP header and the connection / link where the initial RRC message was received, and subsequently determine / specify which connection the message / data for the remote UE will be delivered to based on the association / mapping relationship.

[0241] As described above, the method of processing received messages may vary depending on the RRC status of the intermediate relay UE. This is because an intermediate relay UE in the RRC_CONNECTED state transmits received messages via the SRB according to the gNB settings, while an intermediate relay UE in the RRC_IDLE / INACTIVE state transmits messages via the specified SRB.

[0242] Meanwhile, the aforementioned remote UE can also be replaced by a case where a UE operating as an intermediate relay UE is RRC_CONNECTED. For example, an intermediate relay UE may send an initial RRC message to a parent relay UE that includes an SRAP header containing its L2 ID in order to switch from an RRC idle / inactive state to an RRC active state, and the parent relay UE may decide whether to transmit the initial RRC message as is or to reconstruct and transmit the SRAP header based on the methods described above.

[0243] Alternatively, the remote UE may always forward an initial RRC message to an intermediate relay UE by attaching an SRAP header containing its L2 ID. If the intermediate relay UE receiving this message is in the RRC_CONNECTED state, it may report the L2 ID value of the remote UE included in the received SRAP header to the base station as described above and request the assignment of a local ID for the remote UE. Separately from this operation, the intermediate relay UE in the RRC_CONNECTED state may forward the received initial RRC message as is to its parent relay UE. Since the RRC state of the parent relay UE is unknown, the initial RRC message with the SRAP header containing the remote UE's L2 ID attached may be transmitted / forwarded as is. The time at which the intermediate relay UE in the RRC_CONNECTED state receives the requested local ID and the time at which the remote UE's initial RRC DL data / message (e.g., an RRCSetup message) is received via an SRAP header containing the local ID and L2 ID may differ. For example, the intermediate relay UE may know the mapping relationship between the remote UE's L2 ID and local ID by receiving the local ID for the L2 ID of the remote UE it requested as an RRC dedicated message (e.g., an RRCReconfiguration message), or it may know the mapping relationship between the remote UE's L2 ID and local ID through an SRAP header containing the local ID and L2 ID attached to the remote UE's initial RRC DL message. In this case, the intermediate relay UE in the RRC_CONNECTED state can establish the mapping relationship between the local ID and L2 ID of the remote UE using whichever message is received first.Alternatively, since the RRC CONNECTED state is active, the establishment of a mapping relationship between the local ID and L2 ID via a dedicated message may take precedence. In this case, even if the intermediate relay UE knows the mapping relationship between the local ID and L2 ID through the DL SRAP header attached to the initial RRC DL message, it may withhold establishing the mapping relationship until it receives the local ID and L2 ID through a dedicated message. The intermediate relay UE may forward the received Initial RRC DL message from the remote UE to the child relay UE and / or the remote UE, or hold it. Alternatively, the intermediate relay UE may establish the mapping relationship between the local ID and L2 ID through the DL SRAP header attached to the Initial RRC DL message and overwrite the establishment of the local ID and L2 ID through a dedicated message. If the mapping relationship between the local ID and L2 ID included in the SRAP header attached to the Initial RRC DL message is different from the mapping relationship between the local ID and L2 ID set through the dedicated message, the intermediate relay UE may overwrite it with the value set through the dedicated message and report this to the gNB.

[0244] The SRAP header structures that can be supported may differ between intermediate relay UEs or between remote UEs. For example, a parent relay UE of a remote UE may only support the existing Rel-17 SRAP header structure. In this case, a problem may arise if the remote UE transmits a message (e.g., an Initial RRC message) that includes an SRAP header with a different structure according to the proposed method. For example, if a child relay UE and / or a remote UE transmits a message having an SRAP header structure that the intermediate relay UE does not support, the intermediate relay UE may inform the transmitting child relay UE and / or remote UE that it does not support the said SRAP header structure via a PC5-RRC message, etc. Alternatively, the intermediate relay UE may inform the child relay UE and / or remote UE of which SRAP header structure it can support as capability information during the PC5 establishment process. Or, the required SRAP header structure may vary depending on the RRC status of the intermediate relay UE. Therefore, the parent relay UE may inform the child relay UE of its RRC status. In this case, the SRAP header structure to be used by the child relay UE and / or remote UE may vary depending on the information regarding the RRC status above.

[0245] In addition, the aforementioned SRAP header is a header related to the inter-UE relay adaptation protocol, and may be defined as a relay protocol header or a relay adaptation protocol header, and the proposed methods can be applied to all headers configured for relay transmission-related identification in relay communication.

[0246] In this way, an intermediate relay UE that receives an initial RRC message from a remote UE can forward / transmit the initial RRC message of the remote UE after processing the initial RRC message in a different manner depending on its own RRC status. Accordingly, the remote UE can perform the procedure for an RRC connection regardless of the RRC status of the intermediate relay UE.

[0247] FIG. 19 is a diagram illustrating a method for a first relay UE to relay an initial RRC message of a received remote UE.

[0248] The first relay UE may be an intermediate relay UE that performs a multi-hop based U2N relay operation to relay data / messages between a base station (or, gNB) and a 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.

[0249] Meanwhile, in a multi-hop based U2N relay environment, an intermediate relay UE in the RRC_IDLE or RRC_INACTIVE state may not receive the Uu RRC configuration message 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 protocol (or relay protocol header) or SRAP header information. Below, the operations of the first relay UE are described in detail based on this.

[0250] Referring to FIG. 19, a first relay UE can form a first connection with a parent relay UE (S191). Here, the first connection may be a connection formed by the first relay UE with the parent relay UE to perform relay transmission in the uplink direction or upstream direction. The first connection may be a PC5 connection, and the first relay UE may transmit control signals and / or data signals to the parent relay UE through the first connection. Additionally, the parent relay UE may be a relay UE closer to the base station than the first relay UE, or may be a last relay UE or another intermediate relay UE connected directly or indirectly to the base station.

[0251] Next, the first relay UE can form a second connection with a remote UE or a child relay UE (S193). Here, the second connection may be a connection formed to perform a downlink direction relay transmission. For example, the first relay UE may form the second connection, which is a direct PC5 connection with the remote UE, or form the second connection with a child relay connected to the remote UE.

[0252] Next, the first relay UE can receive a first message through the second connection (S195). The first message may include an initial RRC message of the remote UE and a relay protocol header (or an SRAP header or an inter-UE relay protocol header). Here, the initial RRC message may be a message for the remote UE to establish, reset, or resume an RRC connection with a base station for multi-hop U2N relay communication. For example, unlike a conventional remote UE that transmits an initial RRC message for an RRC connection to a relay UE without an SRAP header, the remote UE may additionally add a relay protocol header containing the L2 ID of the remote UE to the initial RRC message and transmit it so that the first relay UE can establish a mapping relationship between the remote UE and a connection toward the remote UE even when the first relay UE is in an RRC idle state or RRC inactive state. Accordingly, the first relay UE can verify the identification information of the remote UE based on the relay protocol header of the first message, and can map / associate the identification information with the path where the first message was received.

[0253] Here, the initial RRC message of the remote UE may be an RRCSetupRequest message, an RRCReestablishmentRequest message, or an RRCResume message. For example, the initial RRC message may be an RRC message transmitted when the remote UE intends to establish a new RRC connection with the base station through relay UEs, as well as when it intends to perform a reset or resumption procedure. Therefore, the method of transmitting by including the remote UE's L2 ID in the relay protocol header can be commonly applied to various types of initial RRC messages.

[0254] For example, if the first relay UE is in an RRC idle state or RRC inactive state, the first relay UE can forward the first message through the first connection. For example, the first relay UE can transmit the first message, which includes a relay protocol header containing the L2 ID of the remote UE and an initial RRC message, to the parent relay UE as is or with substantially the same content.

[0255] Alternatively, if the first relay UE receives the first message through the second connection while in an RRC connection state, the first relay UE may transmit a message through the first connection requesting the assignment of a local ID for the remote UE. Here, the local ID may be an identifier assigned by the base station to identify the remote UE. Based on the L2 ID of the remote UE included in the received first message, the first relay UE may request a local ID corresponding to the L2 ID from the base station. Subsequently, the first relay UE may receive information regarding the local ID assigned to the remote UE through the first connection. Based on the received local ID, the first relay UE may reconfigure the relay protocol header (e.g., so as to correspond to an existing relay protocol header as shown in FIG. 18) and transmit a second message through the first connection, which adds the reconfigured relay protocol header to the initial RRC message of the remote UE. For example, the first relay UE may reconstruct the relay protocol header by replacing the L2 ID of the remote UE with a local ID in the relay protocol header included in the first message, and transmit the second message, which has the reconstructed relay protocol header added to the initial RRC message of the remote UE, toward the base station through the first connection. In this case, the reconstructed relay protocol header may be a header in a form identical to or compatible with the existing Rel-17 U2N SRAP structure.

[0256] Alternatively, the first relay UE, which is in an RRC connection state, may forward the first message even before receiving a message that assigns the local ID of the relay UE in response to the request for assignment of the local ID. For example, the first relay UE may forward the first message through the first connection regardless of whether it has received information regarding the local ID assigned to the remote UE. For example, the first relay UE does not necessarily have to perform the local ID assignment procedure and the first message delivery procedure sequentially, and may forward the first message toward the parent relay UE first or in parallel. Accordingly, even if the response to the local ID assignment is delayed, the initial RRC procedure of the remote UE can be reduced from being unnecessarily delayed.

[0257] For example, the first relay UE may receive a first RRC message (e.g., an RRCReconfiguration message) containing the local ID of the remote UE assigned by the base station in accordance with the request for assignment of the local ID, through the first connection. Additionally, the first relay UE may receive a second RRC message (e.g., an RRCSetup, RRCReconfiguration, RRCResume, RRCReestablishment message, or an initial RRC DL message) transmitted from the base station based on the initial RRC message of the remote UE through the first connection. Here, the second RRC message may be a message to which the relay protocol header including the L2 ID of the remote UE and the local ID of the remote UE is appended. For example, the second RRC message may be an initial RRC DL message (e.g., RRCSetup, RRCReconfiguration, RRCResume, RRCReestablishment message), and the first RRC message may be a dedicated RRC message (e.g., RRCReconfiguration message). Accordingly, the first relay UE can determine the correspondence between the L2 ID of the remote UE and the local ID through different procedures.

[0258] For example, the first relay UE can establish a correspondence relationship between the L2 ID of the remote UE and the local ID of the remote UE based on the message received first among the first RRC message and the second RRC message. For example, if a dedicated RRC message transmitted in response to a request for the assignment of a local ID is received first, the first relay UE can establish a mapping relationship between the L2 ID and the local ID using the information included in the dedicated RRC message. Conversely, if an initial RRC DL message is received first, the first relay UE can establish the mapping relationship first using the L2 ID and the local ID included in the relay protocol header attached to the initial RRC DL message.

[0259] Alternatively, the first relay UE may establish a correspondence relationship between the L2 ID of the remote UE and the local ID of the remote UE by prioritizing the first RRC message among the first RRC message and the second RRC message. For example, when the first relay UE is in an RRC connection state, the reliability or priority of the local ID information provided through the dedicated RRC message may be set higher. Accordingly, even if there is a mapping relationship temporarily identified by the initial RRC DL message, the confirmation of the final mapping relationship may be withheld until the dedicated RRC message is received, or the existing mapping relationship may be updated or overwritten according to the information after the dedicated RRC message is received. Furthermore, if the information obtained through the dedicated RRC message and the information obtained through the initial RRC DL message are different, the first relay UE may prioritize and apply the information based on the dedicated RRC message.

[0260] Alternatively, the first relay UE may transmit information regarding the switched RRC state to a child UE (e.g., child relay UE and / or remote UE) via the second connection based on the fact that its RRC state has switched. For example, if the first relay UE switches from an RRC idle state or RRC inactive state to an RRC connected state, or conversely switches from an RRC connected state to another state, it may notify the child relay UE or remote UE of the switched state. Accordingly, the child relay UE or remote UE may select a relay protocol header structure, message delivery method, or initial RRC message transmission method suitable for the current RRC state of the parent relay UE or the parent relay UE. For example, if it is indicated that the parent relay UE is in an RRC connected state, the child relay UE may expect message delivery in a manner that takes into account local ID assignment and header reconfiguration. Alternatively, if it is indicated that the parent relay UE is in an RRC idle state or RRC inactive state, the child relay UE may expect a method of delivering the initial RRC message as is upstream, with a header including an L2 ID added.

[0261] The aforementioned relay protocol header may be a header related to the inter-UE relay protocol or an SRAP header. Furthermore, the proposed methods described above are not limited to protocol headers of a specific name and can be applied to various types of headers configured for identification related to relay transmission in relay communication. For example, the header may include the L2 ID of the remote UE, local ID, link identification information, or a combination thereof, and based on the information included in the header, the intermediate relay UE and / or base station may determine which PC5 link can reach the remote UE or which connection should be used to deliver the message.

[0262] Figure 20 is a diagram illustrating how a remote UE transmits an initial RRC message.

[0263] Referring to FIG. 20, a remote UE can form a first connection with a parent relay UE (S201). Here, the first connection may be a connection formed by the remote UE with the parent relay UE to perform a communication procedure with a base station via multi-hop based U2N relay communication. The first connection may be a PC5 connection, and the remote UE can perform upstream or uplink relay transmission through the first connection. Meanwhile, the remote UE may form the first connection without prior knowledge of the parent relay UE's RRC status.

[0264] Next, the remote UE can transmit a first message through the first connection (S203). The first message may include an initial RRC message and a relay protocol header of the remote UE. Here, the initial RRC message may be a message for establishing, resetting, or resuming an RRC connection, and may be, for example, an RRCSetupRequest message, an RRCReestablishmentRequest message, or an RRCResume message. Additionally, the relay protocol header may include the L2 ID of the remote UE. Accordingly, an intermediate relay UE receiving the first message can map which remote UE and which connection the first message corresponds to based on the L2 ID included in the relay protocol header.

[0265] And / or, the remote UE may transmit the initial RRC message with a relay protocol header containing its L2 ID added, regardless of the RRC status of the parent relay UE or the intermediate relay UE. For example, the remote UE may generate and transmit the first message in the same manner without separately determining whether the parent relay UE is in an RRC connected state, an RRC idle state, or an RRC inactive state. Accordingly, it is possible to support both cases where the parent relay UE forwards the first message as is and cases where it performs a local ID assignment procedure using the information contained in the first message. Additionally, the relay protocol header containing the remote UE's L2 ID may be used as information for identifying the remote UE during the process in which the first message is transmitted by the parent relay UEs. For example, the intermediate relay UE may establish a mapping relationship to transmit a subsequent message to the remote UE by recognizing the correspondence between the L2 ID and a specific PC5 link. Therefore, a method in which a remote UE transmits a header containing its L2 ID along with an initial RRC message can support the initial RRC DL message of the base station responding to the initial RRC message to the remote UE in a multi-hop relay environment, even if some intermediate relay UEs are not in an RRC connection state.

[0266] A remote UE can form a first connection with a parent relay UE and transmit a first message through the first connection, the message including its initial RRC message and a relay protocol header including its L2 ID. Accordingly, the remote UE can perform / complete the RRC connection procedure with the base station even if some of the intermediate relay UEs remain in an RRC idle / inactive state.

[0267] Thus, the proposed invention enables the delivery of an initial RRC message from a remote UE to a parent relay UE without a separate RRC connection state transition, even when the intermediate relay UE is in an RRC idle state or RRC inactive state, thereby effectively minimizing the delay associated with the initial connection procedure in a multi-hop U2N relay communication environment. And / or, the proposed invention adds a relay protocol header containing the L2 ID of the remote UE to the initial RRC message, thereby enabling the intermediate relay UE to identify the remote UE and establish a correspondence with the PC5 link, and thereby effectively identify the transmission path of data and messages to the remote UE even when it is in an RRC idle state or RRC inactive state.

[0268] Example of a communication system to which the invention is applied

[0269] 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.

[0270] 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.

[0271] FIG. 21 illustrates a communication system to which the present invention is applied.

[0272] 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.

[0273] 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).

[0274] 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.

[0275] Example of a wireless device to which the present invention is applied

[0276] FIG. 22 illustrates a wireless device that can be applied to the present invention.

[0277] 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.

[0278] 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.

[0279] 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 “Operation of intermediate relay UE according to RRC state during multi-hop relay operation”. The operations may include controlling the RF transceiver to form a first connection with the parent relay UE, forming a second connection with the remote UE or child relay UE, and receiving a first message through the second connection, wherein the first message may be a message in which a Relay Protocol header containing the L2 ID (layer 2 identifier) ​​of the remote UE is added to the initial RRC (radio resource control) message of the remote UE.

[0280] Alternatively, a processing device may be configured including a processor (102) and a memory (104) for controlling a first relay 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 remote UE or a child relay UE, and receiving a first message through the second connection, wherein the first message may be a message in which a Relay Protocol header containing the L2 ID (layer 2 identifier) ​​of the remote UE is added to the initial RRC (radio resource control) message of the remote UE. Alternatively, at least one non-transient computer-readable medium may be configured that stores programs / instructions for performing the above-described operations.

[0281] 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.

[0282] Specifically, the second wireless device or remote UE (200) may include a processor (202) and a memory (204) connected to a transceiver or RF transceiver (206). The memory (204) may include at least one program capable of performing operations related to the embodiments described with reference to FIGS. 16 through 20 in the section “Operation of intermediate relay UE according to RRC state during multi-hop relay operation”. The operations include controlling the RF transceiver to form a first connection with the parent relay UE and transmitting a first message for a radio resource control (RRC) connection with the base station through the first connection, and the first message may be a message in which a Relay Protocol header including the L2 ID (layer 2 identifier) ​​of the remote UE is added to the initial RRC message of the remote UE.

[0283] 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.

[0284] 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.

[0285] One or more memories (104, 204) may be connected to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, code, instructions, and / or commands. One or more memories (104, 204) may be composed of ROM, RAM, EPROM, flash memory, hard drive, registers, cache memory, computer read storage media, and / or combinations thereof. One or more memories (104, 204) may be located inside and / or outside of one or more processors (102, 202). Additionally, one or more memories (104, 204) may be connected to one or more processors (102, 202) through various technologies such as wired or wireless connections.

[0286] 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.

[0287] Examples of wireless device applications to which the present invention is applied

[0288] 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).

[0289] 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).

[0290] 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.

[0291] 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.

[0292] Examples of vehicles or autonomous vehicles to which the present invention is applied

[0293] 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.

[0294] 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 correspond to blocks 110 / 130 / 140 of FIG. 23, respectively.

[0295] 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.

[0296] 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.

[0297] 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.

[0298] 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.

[0299] 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).

[0300] 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.

[0301] 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.

[0302] 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.

[0303] 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; A step of forming a second connection with a remote UE or a child relay UE; and It includes the step of receiving a first message through the second connection above, and A method in which the first message is a message in which a Relay Protocol header containing the L2 ID (layer 2 identifier) ​​of the remote UE is added to the initial RRC (radio resource control) message of the remote UE.

2. In Paragraph 1, A method in which the first relay UE forwards the first message through the first connection based on whether the first relay UE is in an RRC idle state or an RRC inactive state.

3. In Paragraph 1, Based on the fact that the first relay UE is in an RRC connection state, a step of transmitting a message requesting the assignment of a local ID to the remote UE through the first connection; A step of receiving information about a local ID assigned to the remote UE through the first connection; and A method further comprising the step of transmitting a second message through the first connection, wherein the relay protocol header reconstructed based on the local ID is added to the initial RRC message of the remote UE.

4. In Paragraph 1, Based on the fact that the first relay UE is in an RRC connection state, the step of transmitting a message requesting the assignment of a local ID to the remote UE through the first connection; and A method further comprising the step of forwarding the first message through the first connection regardless of whether information regarding the local ID assigned to the remote UE is received.

5. In Paragraph 4, A step of receiving a first RRC message through the first connection that includes the local ID of the remote UE assigned by the base station in accordance with the request for assignment of the local ID; and The method includes the step of receiving a second RRC message through the first connection in response to an initial RRC message of the remote UE. A method in which the second RRC message is appended with the relay protocol header including the L2 ID of the remote UE and the local ID of the remote UE.

6. In Paragraph 5, A method in which the first relay UE establishes a correspondence relationship between the L2 ID of the remote UE and the local ID of the remote UE based on the first message received among the first RRC message and the second RRC message.

7. In Paragraph 5, A method in which the first relay UE prioritizes the first RRC message among the first RRC message and the second RRC message to establish a correspondence relationship between the L2 ID of the remote UE and the local ID of the remote UE.

8. In Paragraph 1, A method in which the initial RRC message of the above remote UE is an RRCSetupRequest message, an RRCReestablishmentRequest message, or an RRCResume message.

9. In Paragraph 1, A method in which the first relay UE transmits information about the switched RRC state through the second connection based on the fact that the RRC state has been switched.

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; Form a second connection with a remote UE or child relay UE; and It includes receiving a first message through the second connection above, and At least one non-transient computer-readable recording medium, wherein the first message is an initial RRC (radio resource control) message of the remote UE to which a Relay Protocol header including the L2 ID (layer 2 identifier) ​​of the remote UE is added.

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 The above at least one processor controls the RF transceiver to form a first connection with a parent relay UE, forms a second connection with a remote UE or a child relay UE, and receives a first message through the second connection. The first message is a message in which a Relay Protocol header containing the L2 ID (layer 2 identifier) ​​of the remote UE is added to the initial RRC (radio resource control) message of the remote UE, for a first relay UE.

12. In Paragraph 1, A first relay UE that forwards the first message through the first connection based on the first relay UE being in an RRC idle or RRC inactive state.

13. In a processing device that controls a first relay UE (User Equipment), At least one processor; and The UE comprises 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 and based on the UE: Form a first connection with the parent relay UE; Form a second connection with a remote UE or child relay UE; and Receive the first message through the second connection above, and A processing device wherein the first message is a message in which a Relay Protocol header containing the L2 ID (layer 2 identifier) ​​of the remote UE is added to the initial RRC (radio resource control) message of the remote UE.

14. In a method using a remote UE (User Equipment), Step of forming a first connection with the parent relay UE; and It includes the step of transmitting a first message for an RRC (radio resource control) connection with a base station through the first connection above, A method in which the first message is a message in which a Relay Protocol header including the L2 ID (layer 2 identifier) ​​of the remote UE is added to the initial RRC message of the remote UE.

15. In the case of a remote UE (User Equipment), RF (Radio Frequency) transceiver; and It includes at least one processor connected to the above RF transceiver, and The above at least one processor controls the RF transceiver to form a first connection with the parent relay UE, and transmits a first message for an RRC (radio resource control) connection with the base station through the first connection, and The above first message is a message in which a Relay Protocol header containing the L2 ID (layer 2 identifier) ​​of the remote UE is added to the initial RRC message of the remote UE.

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