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

Abstract

Disclosed are a method for a first relay terminal to perform relay communication and a device therefor in a wireless communication system according to various embodiments, the first relay terminal forming a first relay connection and a second relay connection for a multi-hop-based relay. Disclosed are a method and a device therefor, the method comprising the steps of: receiving a first message through the first relay connection formed with a first device; and forwarding the first message through the second relay connection.

Description

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

[0001] The present invention relates to a method for forwarding a discovery message for a multi-hop-based relay by a relay terminal in a wireless communication system and a device therefor.

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

[0003] Sidelink (SL) refers to a communication method that establishes a direct link between user equipment (UE), allowing voice or data to be exchanged directly between terminals without going through a base station (BS). SL is being considered as a solution to address the burden on base stations due to rapidly increasing data traffic.

[0004] V2X (vehicle-to-everything) refers to a communication technology that exchanges information with other vehicles, pedestrians, and infrastructure-based objects through wired / wireless communication. V2X can be divided 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 the PC5 interface and / or Uu interface.

[0005] Meanwhile, as more and more communication devices demand greater communication capacity, the need for improved mobile broadband communication compared to existing radio access technology (RAT) is emerging. Accordingly, communication systems that consider services or terminals sensitive to reliability and latency are being discussed. Next-generation wireless access technologies that consider improved mobile broadband communication, massive machine type communication (MTC), and ultra-reliable and low latency communication (URLLC) can be called new radio access technology (RAT) or new radio (NR). NR can also support vehicle-to-everything (V2X) communication.

[0006] Figure 1 is a diagram for comparing and explaining V2X communication based on RAT before NR and V2X communication based on NR.

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

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

[0009] Since then, various V2X scenarios have been proposed in NR in relation to V2X communications. For example, various V2X scenarios may include vehicle platooning, advanced driving, extended sensors, and remote driving.

[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 in the group can receive periodic data from the lead vehicle. For example, vehicles in the group can use this periodic data to narrow or widen the gap between vehicles.

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

[0012] For example, based on extended sensors, raw data, 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 its environment better than it can perceive using its own sensors.

[0013] For example, based on remote driving, a remote driver or V2X application can operate or control the remote vehicle for people who cannot drive or for remote vehicles located in hazardous environments. For example, in cases where the route is predictable, such as public transportation, cloud computing-based driving can be utilized to operate or control the remote vehicle. Additionally, access to a cloud-based back-end service platform, for example, can be considered for remote driving.

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

[0015] The technical problem to be solved by the present invention is to provide a method for performing relay communication more accurately and efficiently.

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

[0017] A method for performing relay communication by a first relay terminal that has formed a first relay connection and a second relay connection for multi-hop-based relay in a wireless communication system according to one aspect comprises the steps of: receiving a first message through the first relay connection formed with a first device; and performing forwarding of the first message through the second relay connection, wherein, based on the first message being a message requesting initial connection between the first device and a network, the first relay terminal can forward the first message further including a local ID (identification) related to the first relay terminal.

[0018] Alternatively, the method further comprises a step of transmitting a request message requesting an RRC connection between the network and the first relay UE through the second relay connection based on the fact that the first relay terminal is not directly connected to the network.

[0019] Alternatively, based on the local ID assigned from the network based on the request message, the first relay terminal is characterized in that it performs forwarding for the first message.

[0020] Alternatively, the request message is characterized in that it further includes information on which hop the first relay terminal is from the network.

[0021] Alternatively, the first message is characterized in that it further includes type information on whether the first device is a relay terminal or a remote terminal.

[0022] Alternatively, the first message is characterized in that it is an RRCSetupRequest message, an RRCReestablishment message, or an RRCResume message requesting an RRC (Radio Resource Control) connection between the first device and the network.

[0023] Alternatively, the first message requesting the initial connection is characterized in that it is an RRC (Radio Resource Control) message transmitted through SRB0 (Signalling Radio Bearer 0) or SRB1 (Signalling Radio Bearer 0).

[0024] Alternatively, the local ID is characterized in that it is included in the SRAP (sidelink relay adaptation protocol) header of the first message.

[0025] Alternatively, based on the fact that the first message is a message from a device other than the first device, the first relay terminal is characterized in that it forwards the first message that does not include a local ID associated with the first relay terminal.

[0026] Alternatively, the multi-hop based relay is characterized as a U2N (User equipment to Network) relay for transmitting and receiving data between a remote terminal and a network.

[0027] According to another aspect, a non-transitory computer-readable storage medium having recorded thereon instructions for performing the method for performing the relay described above may be provided.

[0028] According to another aspect, a first relay terminal may be provided that performs the method for performing the relay described above.

[0029] According to another aspect, a processing device may be provided for controlling a first relay terminal for performing the method for performing the relay described above.

[0030] In another aspect, a method for performing relay communication by a second relay terminal that has formed a second relay connection and a third relay connection for multi-hop-based relay in a wireless communication system comprises the steps of: receiving a second message forwarding a first message for a first device by the first relay terminal through the second relay connection formed with the first relay terminal; and performing forwarding of the second message through the third relay connection, wherein the second message may include a local ID associated with the first relay terminal based on the first message being a message requesting an initial connection between the first device and a network.

[0031] A second relay terminal may be provided that performs the method for performing the relay described above according to another aspect.

[0032] According to one embodiment of the present invention, relay communication can be performed more accurately and efficiently in a wireless communication system.

[0033] The effects that can be obtained in various embodiments are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art to which the present invention pertains from the description below.

[0034] The drawings attached to this specification are intended to provide an understanding of the present invention, illustrate various embodiments of the present invention, and together with the description of the specification serve to explain the principles of the present invention.

[0035] Figure 1 is a diagram for comparing and explaining V2X communication based on RAT before NR and V2X communication based on NR.

[0036] Figure 2 shows the structure of the LTE system.

[0037] Figure 3 shows the structure of the NR system.

[0038] Figure 4 shows the structure of a radio frame of NR.

[0039] Figure 5 shows the slot structure of an NR frame.

[0040] FIG. 6 illustrates a communication structure that can be provided in a 6G system according to one embodiment of the present disclosure.

[0041] FIG. 7 illustrates an electromagnetic spectrum according to one embodiment of the present disclosure.

[0042] Figure 8 shows a radio protocol architecture for SL communication.

[0043] Figure 9 shows a terminal performing V2X or SL communication.

[0044] Figure 10 shows resource units for V2X or SL communication.

[0045] FIG. 11 illustrates an example of a BWP according to one embodiment of the present disclosure.

[0046] FIG. 12 illustrates a procedure for a terminal to perform V2X or SL communication according to a resource allocation mode, according to one embodiment of the present disclosure.

[0047] Figure 13 is a diagram for explaining the control plane procedure of L2 U2N relay (UE-to-Network Relay).

[0048] Figure 14 is a diagram for explaining the control plane procedure of L2 U2U relay (UE-to-UE Relay).

[0049] FIG. 15 and FIG. 16 are diagrams for explaining a procedure for U2U relay selection (UE-to-UE Relay Selection) without relay discovery.

[0050] Figure 17 schematically illustrates a flat protocol stack for L2 U2U relay.

[0051] Figure 18 is a diagram for explaining the operation of a multi-hop based U2N relay.

[0052] Figure 19 is a diagram for explaining a method for a first relay terminal to perform multi-hop based relay communication.

[0053] Figure 20 is a drawing for explaining a method for a second relay terminal to perform multi-hop based relay communication.

[0054] Figure 21 illustrates a communication system applied to the present invention.

[0055] Figure 22 illustrates a wireless device applicable to the present invention.

[0056] Figure 23 illustrates another example of a wireless device applicable to the present invention. The wireless device may be implemented in various forms depending on the use case / service.

[0057] Figure 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 code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and multi-carrier frequency division multiple access (MC-FDMA).

[0059] Sidelink refers to a communication method that establishes a direct link between user equipment (UE), allowing voice or data to be exchanged directly between terminals without going through a base station (BS). Sidelink is being considered as a solution to address the burden on base stations due to rapidly increasing data traffic.

[0060] V2X (vehicle-to-everything) refers to a communication technology that exchanges information with other vehicles, pedestrians, and infrastructure-based objects through wired / wireless communication. V2X can be divided 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 the PC5 interface and / or Uu interface.

[0061] Meanwhile, as more and more communication devices demand greater communication capacity, the need for improved mobile broadband communication compared to existing radio access technology (RAT) is emerging. Accordingly, communication systems that consider services or terminals sensitive to reliability and latency are being discussed. Next-generation wireless access technologies that consider improved mobile broadband communication, massive MTC, and URLLC (Ultra-Reliable and Low Latency Communication) can be called new radio access technology (RAT) or new radio (NR). NR can also support V2X (vehicle-to-everything) communication.

[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 with wireless technologies such as UTRA (universal terrestrial radio access) or CDMA2000. TDMA can be implemented with wireless technologies such as GSM (global system for mobile communications) / GPRS (general packet radio service) / EDGE (enhanced data rates for GSM evolution). OFDMA can be implemented with 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, providing 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 a part of E-UMTS (evolved UMTS) that 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, the successor to LTE-A, is a new clean-slate mobile communications system featuring high performance, low latency, and high availability. 5G NR can utilize all available spectrum resources, from low-frequency bands below 1 GHz, mid-frequency bands between 1 GHz and 10 GHz, and high-frequency (millimeter wave) bands above 24 GHz.

[0064] For clarity, the description will focus on LTE-A or 5G NR, but the technical ideas of the embodiment(s) are not limited thereto.

[0065] Figure 2 illustrates the architecture of an applicable LTE system. This may be referred to as an Evolved-UMTS Terrestrial Radio Access Network (E-UTRAN) or a Long Term Evolution (LTE) / LTE-A system.

[0066] Referring to FIG. 2, the E-UTRAN includes a base station (20; 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 a mobile station (MS), a user terminal (UT), a subscriber station (SS), a mobile terminal (MT), a wireless device, etc. 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 an evolved-NodeB (eNB), a base transceiver system (BTS), an access point, etc.

[0067] Base stations (20) can be connected to each other via the X2 interface. The base station (20) is connected to an EPC (Evolved Packet Core, 30) via the S1 interface, more specifically, to an MME (Mobility Management Entity) via the S1-MME, and to an S-GW (Serving Gateway) via 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 about terminal access and capabilities, and this information is primarily used for terminal mobility management. The S-GW is a gateway with the E-UTRAN as its endpoint, and the P-GW is a gateway with the PDN as its endpoint.

[0069] The layers of the radio interface protocol between the terminal and the network can be divided into L1 (Layer 1), L2 (Layer 2), and L3 (Layer 3) based on the three lower layers of the Open System Interconnection (OSI) standard model, which is widely known in communication systems. Among these, the physical layer belonging to Layer 1 provides an information transfer service using a physical channel, and the RRC (Radio Resource Control) layer located in Layer 3 controls 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 a gNB and / or an eNB that provides user plane and control plane protocol termination to the UE. FIG. 7 illustrates a case where only a gNB is included. The gNB and eNB are connected to each other via an Xn interface. The gNB and eNB are connected to the 5th generation core network (5G Core Network: 5GC) via the NG interface. More specifically, the gNB is connected to the access and mobility management function (AMF) via the NG-C interface, and the gNB is connected to the user plane function (UPF) via the NG-U interface.

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

[0073] Referring to FIG. 4, radio frames can be used for uplink and downlink transmission in NR. A radio frame has a length of 10 ms and can be defined as two 5 ms half-frames (Half-Frames, HF). A half-frame can include five 1 ms sub-frames (Subframes, SF). A sub-frame can be divided into one or more slots, and the number of slots within a sub-frame can be determined by the Subcarrier Spacing (SCS). Each slot can include 12 or 14 OFDM (A) symbols depending on the cyclic prefix (CP).

[0074] When normal CP is used, each slot can contain 14 symbols. When extended CP is used, each slot can contain 12 symbols. Here, the symbols can include OFDM symbols (or CP-OFDM symbols), 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)) depending on 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 illustrates the number of symbols per slot, the number of slots per frame, and the number of slots per subframe according to SCS when 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, OFDM(A) numerology (e.g., SCS, CP length, etc.) may be set differently between multiple cells that are merged into a single terminal. Accordingly, the (absolute time) interval of a time resource (e.g., subframe, slot, or TTI) (conveniently referred to as TU (Time Unit)) consisting of the same number of symbols may be set differently between the merged cells.

[0080] In NR, multiple numerologies, or SCSs, can be supported to support various 5G services. For example, a 15 kHz SCS can support wide areas in traditional cellular bands, while a 30 kHz / 60 kHz SCS can support dense urban areas, lower latency, and wider carrier bandwidth. A 60 kHz or higher SCS can support bandwidths greater than 24.25 GHz to overcome phase noise.

[0081] The NR frequency band can be defined by two types of frequency ranges. The two types of frequency ranges can be FR1 and FR2. The numerical values ​​of the frequency ranges can be changed, and for example, the two types of frequency ranges can be as shown in Table 3 below. Among the frequency ranges used in the NR system, FR1 can mean the "sub 6 GHz range", and FR2 can mean the "above 6 GHz range" and can be called 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 can be changed. For example, FR1 may include a band from 410 MHz to 7125 MHz, as shown in Table 4 below. That is, FR1 may include a frequency band above 6 GHz (or 5850, 5900, 5925 MHz, etc.). For example, the frequency band above 6 GHz (or 5850, 5900, 5925 MHz, etc.) included within FR1 may include an unlicensed band. The unlicensed band may be used for various purposes, such as for vehicular communications (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 Figure 5, a slot includes multiple symbols in the time domain. For example, in the case of a normal CP, one slot may include 14 symbols, but in the case of an extended CP, one slot may include 12 symbols. Alternatively, in the case of a normal CP, one slot may include 7 symbols, but in the case of an extended CP, one slot may include 6 symbols.

[0087] A carrier includes multiple subcarriers in the frequency domain. An RB (Resource Block) can be defined as multiple (e.g., 12) consecutive subcarriers in the frequency domain. A BWP (Bandwidth Part) can be defined as multiple consecutive (P)RBs ((Physical) Resource Blocks) in the frequency domain, and can correspond to one numerology (e.g., SCS, CP length, etc.). A carrier can include up to N (e.g., 5) BWPs. Data communication can be performed through activated BWPs. Each element can be referred to as a Resource Element (RE) in the resource grid, and one complex symbol can be mapped to it.

[0088] Meanwhile, the wireless interface between terminals or between terminals and a network may be composed of an L1 layer, an L2 layer, and an L3 layer. In various embodiments of the present disclosure, the L1 layer may refer to a physical layer. Furthermore, for example, the L2 layer may refer to at least one of a MAC layer, an RLC layer, a PDCP layer, and an SDAP layer. Furthermore, for example, the L3 layer may refer to an RRC layer.

[0089] FIG. 6 illustrates a communication structure that can be provided in a 6G system according to an 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 include:

[0091] - Satellite integrated network

[0092] - Connected Intelligence: Unlike previous generations of wireless communication systems, 6G is revolutionary, upgrading the wireless evolution from "connected objects" to "connected intelligence." AI can be applied at every stage of the communication process (or at every signal processing step, as described below).

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

[0094] - Ubiquitous super 3D connectivity: Access to networks and core network functions of drones and very low Earth orbit satellites will create super 3D connectivity in 6G ubiquitous.

[0095] Some general requirements for the new network characteristics of 6G, such as the 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 communications is a key feature of 6G wireless communication systems. Therefore, radar systems will be integrated with 6G networks.

[0100] - Softwarization and virtualization

[0101] Below, the core implementation technologies of the 6G system are described.

[0102] - Artificial Intelligence: Incorporating AI into communications can streamline and improve real-time data transmission. AI can use numerous analytics to determine how complex target tasks should be performed. This means AI can increase efficiency and reduce processing delays. Time-consuming tasks such as handovers, network selection, and resource scheduling can be performed instantly using AI. AI can also play a crucial role in machine-to-machine (M2M), machine-to-human, and human-to-machine communications. Furthermore, AI can facilitate rapid communication in brain-computer interfaces (BCIs). 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 (terahertz communication): Data rates can be increased by increasing the bandwidth. This can be achieved by using sub-THz communication with wide bandwidths and applying advanced massive MIMO technology. THz waves, also known as sub-millimeter waves, typically refer to the frequency range between 0.1 THz and 10 THz, with corresponding wavelengths ranging from 0.03 mm to 3 mm. The 100 GHz to 300 GHz band (sub-THz band) is considered a key part of the THz spectrum for cellular communications. Adding the sub-THz band to the mmWave band will increase the capacity of 6G cellular communications. Among the defined THz bands, 300 GHz to 3 THz lies in the far infrared (IR) frequency band. While part of the optical band, the 300 GHz to 3 THz band lies at the boundary of the optical band, immediately following the RF band. Therefore, this 300 GHz to 3 THz band exhibits similarities to RF.

[0104] Figure 7 illustrates the electromagnetic spectrum according to one embodiment of the present disclosure. The embodiment of Figure 7 can be combined with various embodiments of the present disclosure. Key characteristics of THz communications include (i) a widely available bandwidth to support very high data rates, and (ii) high path loss at high frequencies (highly directional antennas are essential). The narrow beamwidth generated by the highly directional antenna reduces interference. The small wavelength of THz signals allows for a much larger number of antenna elements to be integrated into devices and base stations operating in this band. This enables the use of advanced adaptive array techniques to 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 surface

[0116] - metaverse

[0117] - Block chain

[0118] Unmanned aerial vehicles (UAVs): UAVs, or drones, will be a key element in 6G wireless communications. In most cases, high-speed data wireless connectivity can be provided using UAV technology. Base stations (BSs) can be installed on UAVs to provide cellular connectivity. UAVs may offer specific capabilities not found in fixed BS infrastructure, such as easy deployment, robust line-of-sight links, and controlled mobility. During emergencies such as natural disasters, deploying terrestrial communications infrastructure is not economically feasible and sometimes cannot provide services in volatile environments. UAVs can easily handle these situations. UAVs will become a new paradigm in wireless communications. This technology facilitates three fundamental requirements for wireless networks: enhanced mobile broadband (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 important technologies for 6G communications.

[0119] - Autonomous driving (self-driving): V2X (vehicle to everything), a key element in building autonomous driving infrastructure, can be a technology that allows cars to communicate and share with various elements on the road for autonomous driving, such as vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) wireless communication. Fast transmission speeds and low-latency technologies are essential to maximize autonomous driving performance and ensure high safety. Furthermore, in the future, autonomous driving will go beyond simply providing warnings or guidance messages to drivers and may require active intervention in vehicle operation and direct control of the vehicle in dangerous situations. To this end, the amount of information that needs to be transmitted and received may become enormous, so 6G is expected to maximize autonomous driving with faster transmission speeds and lower latency than 5G.

[0120] Figure 8 illustrates a radio protocol architecture for SL communication. Specifically, Figure 8 (a) illustrates the user plane protocol stack of NR, and Figure 8 (b) illustrates the control plane protocol stack of NR.

[0121] Below, the SL synchronization signal (Sidelink Synchronization Signal, SLSS) and synchronization information are described.

[0122] SLSS is an SL-specific sequence and may include a Primary Sidelink Synchronization Signal (PSSS) and a Secondary Sidelink Synchronization Signal (SSSS). The PSSS may be referred to as a Sidelink Primary Synchronization Signal (S-PSS), and the SSSS may be referred to as a Sidelink Secondary Synchronization Signal (S-SSS). For example, length-127 M-sequences may be used for the S-PSS, and length-127 Gold sequences may be used for the S-SSS. For example, a terminal may detect an initial signal and acquire synchronization using the S-PSS. For example, a terminal may acquire detailed synchronization and detect a synchronization signal ID using the S-PSS and the S-SSS.

[0123] PSBCH (Physical Sidelink Broadcast Channel) may be a (broadcast) channel that transmits basic (system) information that a terminal must know first before transmitting or receiving an SL signal. For example, the basic information may be information related to SLSS, duplex mode (DM), TDD UL / DL (Time Division Duplex Uplink / Downlink) configuration, resource pool-related information, type of application related to SLSS, subframe offset, broadcast information, etc. For example, in NR V2X, for evaluating PSBCH performance, 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 supporting periodic transmission (e.g., SL SS (Synchronization Signal) / PSBCH block, hereinafter referred to as S-SSB (Sidelink-Synchronization Signal Block)). The S-SSB may have the same numerology (i.e., SCS and CP length) as the PSCCH (Physical Sidelink Control Channel) / PSSCH (Physical Sidelink Shared Channel) in the carrier, and the transmission bandwidth may be within a (pre-)configured SL BWP (Sidelink BWP). For example, the bandwidth of the S-SSB may be 11 RBs (Resource Blocks). For example, the PSBCH may span 11 RBs. And, the frequency location of the S-SSB may be (pre-)configured. Therefore, the terminal does not need to perform hypothesis detection in the frequency to discover the S-SSB in the carrier.

[0125] Meanwhile, in the 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 a transmitting terminal to transmit an S-SSB may become shorter. Accordingly, the coverage of the S-SSB may decrease. Therefore, in order to ensure the coverage of the S-SSB, the transmitting terminal may transmit one or more S-SSBs to a receiving terminal within one S-SSB transmission period according to the SCS. For example, the number of S-SSBs that the transmitting terminal transmits to the receiving terminal within one S-SSB transmission period may be pre-configured or configured for the transmitting terminal. For example, the S-SSB transmission period may be 160 ms. For example, an S-SSB transmission period of 160 ms may be supported for all SCSs.

[0126] For example, when the SCS is 15 kHz at FR1, the transmitting terminal can transmit one or two S-SSBs to the receiving terminal within one S-SSB transmission period. For example, when the SCS is 30 kHz at FR1, the transmitting terminal can transmit one or two S-SSBs to the receiving terminal within one S-SSB transmission period. For example, when the SCS is 60 kHz at FR1, the transmitting terminal can transmit one, two, or four S-SSBs to the receiving terminal within one S-SSB transmission period.

[0127] For example, when 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 period. For example, when 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 period.

[0128] Meanwhile, when the SCS is 60 kHz, two types of CP may be supported. In addition, the structure of the S-SSB transmitted by the transmitting terminal to the receiving terminal may be different depending on the CP type. For example, the CP type may be Normal CP (NCP) or Extended CP (ECP). Specifically, for example, when the CP type is NCP, the number of symbols to which the PSBCH is mapped within the S-SSB transmitted by the transmitting terminal may be 9 or 8. On the other hand, for example, when the CP type is ECP, the number of symbols to which the PSBCH is mapped within the S-SSB transmitted by the transmitting terminal may be 7 or 6. For example, the 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 an Automatic Gain Control (AGC) operation in the first symbol section of the S-SSB.

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

[0130] Referring to FIG. 9, the term "terminal" in V2X or SL communication may primarily refer to a user's terminal. However, if a network device, such as a base station, transmits and receives signals according to a 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 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 a signal from terminal 1 within the resource pool.

[0132] Here, if terminal 1 is within the connection range of the base station, the base station can 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 can inform terminal 1 of the resource pool, or terminal 1 can use a pre-configured resource pool.

[0133] In general, a resource pool can be composed of multiple resource units, and each terminal can select one or multiple resource units to use for its SL signal transmission.

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

[0135] Referring to Figure 10, the entire frequency resources of the resource pool can be divided into NF units, and the entire time resources of the resource pool can be divided into NT units. Therefore, a total of NF * NT resource units can be defined within the resource pool. Figure 13 illustrates an example where the resource pool repeats with a cycle of NT subframes.

[0136] As shown in Figure 10, a single resource unit (e.g., Unit #0) may appear periodically and repeatedly. Alternatively, to achieve diversity effects in the time or frequency dimensions, 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 resource unit structure, a resource pool may refer to a set of resource units that a terminal wishing to transmit an SL signal can use for transmission.

[0137] Resource pools can be subdivided into several categories. For example, based on the content of the SL signal transmitted from each resource pool, resource pools can be categorized as follows:

[0138] (1) Scheduling Assignment (SA) may be a signal that includes information such as the location of resources used by a transmitting terminal for transmission of an SL data channel, MCS (Modulation and Coding Scheme) or MIMO (Multiple Input Multiple Output) transmission method required for demodulation of other data channels, and TA (Timing Advance). SA may also be transmitted multiplexed with SL data on the same resource unit, in which case the SA resource pool may mean a resource pool in which SA is multiplexed with SL data and transmitted. SA may also be called an SL control channel.

[0139] (2) The SL data channel (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 together with SL data on the same resource unit, only the SL data channel excluding SA information may be transmitted from the resource pool for the SL data channel. In other words, the REs (Resource Elements) that were used to transmit SA information on individual resource units within the SA resource pool may still be used to transmit SL data in the resource pool of the SL data channel. For example, the transmitting terminal may transmit the PSSCH by mapping it to consecutive PRBs.

[0140] (3) A discovery channel may be a resource pool for transmitting terminals to transmit information such as their IDs. Through this, transmitting terminals can enable neighboring terminals to discover them.

[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 properties of the SL signal. For example, even if it is the same SL data channel or discovery message, it may be again divided into different resource pools depending on the transmission timing determination method of the SL signal (for example, whether it is transmitted at the time of reception of a synchronization reference signal or whether it is transmitted by applying a certain timing advance at the time of reception), the resource allocation method (for example, whether the base station designates transmission resources for individual signals to individual transmitting terminals or whether individual transmitting terminals independently select individual signal transmission resources within the resource pool), the signal format (for example, the number of symbols each SL signal occupies in one subframe or the number of subframes used for 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 can 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 Figure 11, a common resource block (CRB) may be a carrier resource block numbered from one end of a carrier band to the other. Furthermore, a PRB may be a numbered resource block within each BWP. Point A may indicate a common reference point for the resource block grid.

[0144] The BWP can be set by Point A, an offset from Point A (NstartBWP), and a bandwidth (NsizeBWP). For example, Point A can be an outer reference point of a PRB of a carrier where subcarrier 0 of all numerologies (e.g., all numerologies supported by the network on that carrier) are aligned. For example, the offset can be the PRB spacing between the lowest subcarrier in a given numerology and Point A. For example, the bandwidth can be the number of PRBs in a given numerology.

[0145] SLSS (Sidelink Synchronization Signal) is a SL (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 detect an initial signal (signal detection) and obtain synchronization using S-PSS. For example, the terminal can obtain detailed synchronization using S-PSS and S-SSS and detect a synchronization signal ID.

[0146] PSBCH (Physical Sidelink Broadcast Channel) may be a (broadcast) channel that transmits basic (system) information that a terminal must know first before transmitting or receiving an SL signal. For example, the basic information may be information related to SLSS, duplex mode (DM), TDD UL / DL (Time Division Duplex Uplink / Downlink) configuration, resource pool-related information, type of application related to SLSS, subframe offset, broadcast information, etc. For example, in order to evaluate PSBCH performance, in NR V2X, the payload size of 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 supporting periodic transmission (e.g., SL SS (Synchronization Signal) / PSBCH block, hereinafter referred to as S-SSB (Sidelink-Synchronization Signal Block)). The S-SSB may have the same numerology (i.e., SCS and CP length) as the PSCCH (Physical Sidelink Control Channel) / PSSCH (Physical Sidelink Shared Channel) in the carrier, and the transmission bandwidth may be within a (pre-)configured SL BWP (Sidelink BWP). For example, the bandwidth of the S-SSB may be 11 RBs (Resource Blocks). For example, the PSBCH may span 11 RBs. And, the frequency location of the S-SSB may be (pre-)configured. Therefore, the terminal does not need to perform hypothesis detection in the frequency to discover the S-SSB in the carrier.

[0148] FIG. 12 illustrates a procedure for a terminal to perform V2X or SL communication according to a resource allocation mode, according to an embodiment of the present disclosure. The embodiment of FIG. 12 may be combined with various embodiments of the present disclosure.

[0149] Referring to (a) of FIG. 12, 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, a first terminal may receive information related to a dynamic grant (DG) resource and / or information related to a configured grant (CG) resource from a base station. For example, a CG resource may include a CG type 1 resource or a CG type 2 resource. In this specification, a DG resource may be a resource that a base station configures / allocates to the first terminal via downlink control information (DCI). In this specification, a CG resource may be a (periodic) resource that a base station configures / allocates to the first terminal via DCI and / or an RRC message. For example, in the case of a CG type 1 resource, the base station may transmit an RRC message including 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 including information related to the CG resource to the first terminal, and the base station may transmit a DCI related to activation or release of the CG resource to the first terminal.

[0151] In step S1510, the first terminal may transmit a PSCCH (e.g., Sidelink Control Information (SCI) 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.) related to the PSCCH to the second terminal. In step S1230, the first terminal may receive a PSFCH related to 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 HARQ feedback information to the base station via a PUCCH or a PUSCH. For example, the HARQ feedback information reported to the base station may be information generated by the first terminal based on the 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 rule set in advance. For example, the DCI may be DCI for scheduling SL.

[0152] Referring to (b) of FIG. 12, in resource allocation mode 2, a terminal can determine an SL transmission resource within the SL resources set by the base station / network or within the preset SL resources. For example, the set SL resources or the preset SL resources may be a resource pool. For example, the terminal can autonomously select or schedule resources for SL transmission. For example, the terminal can perform SL communication by selecting a resource by itself within the set resource pool. For example, the terminal can select a resource by itself within a selection window by performing sensing and resource (re)selection procedures. For example, the sensing can be performed on a subchannel basis. For example, in step S1210, a first terminal that has selected a resource by itself within the resource pool can transmit a PSCCH (e.g., Sidelink Control Information (SCI) or 1st-stage SCI) to a second terminal using the resource. In step S1220, the first terminal may transmit a PSSCH (e.g., 2nd-stage SCI, MAC PDU, data, etc.) related to the PSCCH to the second terminal. In step S1230, the first terminal may receive a PSFCH related to the PSCCH / PSSCH from the second terminal.

[0153] Referring to (a) or (b) of FIG. 12, for example, a first terminal may transmit an SCI to a second terminal on a PSCCH. Or, for example, the first terminal may transmit two consecutive SCIs (e.g., 2-stage SCIs) to the second terminal on the PSCCH and / or the 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 on a PSCCH may be referred to as a 1st SCI, a 1st SCI, a 1st-stage SCI, or a 1st-stage SCI format, and an SCI transmitted on a PSSCH may be referred to as a 2nd SCI, a 2nd SCI, a 2nd-stage SCI, or a 2nd-stage SCI format.

[0154] Referring to (a) or (b) of FIG. 12, in step S1530, the first terminal may receive a PSFCH. For example, the first terminal and the second terminal may determine PSFCH resources, and the second terminal may use the PSFCH resources to transmit HARQ feedback to the first terminal.

[0155] Referring to (a) of FIG. 12, in step S1540, the first terminal may transmit SL HARQ feedback to the base station via PUCCH and / or PUSCH.

[0156] Meanwhile, the aforementioned sidelink can be defined as terminal-to-terminal communication or direct terminal-to-terminal communication. In this case, the PSCCH can be defined as a physical control channel for direct terminal-to-terminal communication, the PSSCH as a physical data channel or physical shared channel for direct terminal-to-terminal communication, and the PSFCH as a physical feedback transmission channel for direct terminal-to-terminal communication.

[0157] Figure 13 is a diagram for explaining the control plane procedure of L2 U2N relay (UE-to-Network Relay).

[0158] The PC5-RRC aspect PC5 unicast link establishment procedure of Rel-16 NR V2X can be reused to establish a secure unicast link for L2 U2N relay (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 via the relay UE.

[0159] For both in-coverage and out-of-coverage scenarios, when a remote UE initiates the first RRC message to establish a connection with a gNB, the PC5 L2 configuration for transmissions between the remote UE and the U2N relay UE can be based on the RLC / MAC configuration defined in the standard. The establishment of Uu SRB1 / SRB2 and DRB of the remote UE follows the legacy Uu configuration procedure for the L2 U2N relay.

[0160] A given scenario (TS 38.300) describes the control plane procedures of an L2 U2N relay as follows:

[0161] In step S1300, the remote UE and the relay UE can perform a discovery procedure and establish a PC5-RRC connection in step S1301 based on the existing Rel-16 procedure.

[0162] In step S1302, the remote UE can transmit 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 RRCSetup delivery to the remote UE uses the default configuration of PC5. If the relay UE is not initiated in RRC_CONNECTED, it must perform its own connection establishment upon receiving the message for the default L2 configuration of PC5.

[0163] In step S1304, the gNB and the relay UE perform a relay channel setup procedure via Uu. Depending on the configuration of the gNB, the relay / remote UE establishes an RLC channel for relaying SRB1 to the remote UE via PC5. This step prepares the relay channel for SRB1.

[0164] In step S1305, a remote UE SRB1 message (e.g., an RRCSetupComplete message) is transmitted to the gNB via the relay UE using the SRB1 relay channel over PC5. The remote UE is then RRC connected over Uu.

[0165] In steps S1306 and S1307, the remote UE and the gNB establish security according to legacy procedures, and the security message is transmitted through the Relay UE.

[0166] In steps S1308 and S1309, the gNB transmits RRCReconfiguration to the remote UE via the relay UE to set up the relay SRB2 / DRB. The remote UE responds by transmitting RRCReconfigurationComplete to the gNB via the relay UE.

[0167] 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.

[0168] In the above scenario, in addition to the connection setup procedure, for L2 UE-to-Network relay:

[0169] - RRC reconfiguration and RRC disconnection procedures can reuse legacy RRC procedures with message content / configuration design left in the WI phase.

[0170] - The RRC connection re-establishment and RRC connection resumption procedures can be reused as a baseline by considering the connection establishment procedure of the L2 U2N relay above to handle relay-specific parts along with the message content / structure design. The message content / structure can be defined later.

[0171] Figure 14 is a diagram for explaining the control plane procedure of L2 U2U relay (UE-to-UE Relay).

[0172] According to a given scenario, the control plane procedure of L2 U2U relay (UE-to-UE Relay) can be performed as follows.

[0173] 1. L2 U2U Remote UE, L2 U2U Relay UE, and Peer L2 U2U Remote UE can perform Discovery procedure or Unified Discovery procedure.

[0174] 2a. L2 U2U Remote UE can establish / modify PC5-RRC connection with selected L2 U2U Relay UE.

[0175] 2b. L2 U2U Relay UE can establish / modify PC5-RRC connection with peer L2 U2U Remote UE.

[0176] 3. The L2 U2U Relay UE allocates two Local IDs, which can be delivered to each L2 U2U Remote UE via the RRCReconfigurationSidelink message. One Local ID is for identifying the L2 U2U Remote UE (or source remote UE), and the other Local ID is for identifying the Peer L2 U2U Remote UE (or target remote UE). When the Local IDs are delivered, the L2 ID of the Peer L2 U2U Remote UE can also be delivered to the U2U Remote UE (or target remote UE) to associate the Local ID with the L2 ID of the Peer U2U Remote UE.

[0177] 4. L2 U2U Remote UE can establish an end-to-end PC5-RRC connection with a Peer L2 U2U Remote UE via an L2 U2U Relay UE. For end-to-end establishment, fixed indices (i.e., 0 / 1 / 2 / 3) for end-to-end SL-SRB 0 / 1 / 2 / 3 can be defined, respectively, and specific PC5 Relay RLC channel settings to be used in each hop.

[0178] 5. L2 U2U Remote UE can send all QoS profiles for end-to-end QoS flow to L2 U2U Relay UE via PC5-RRC message.

[0179] 6. L2 U2U Relay UEs can perform QoS Split only for PDBs. However, the method of splitting PDBs depends on the L2 U2U Relay UE implementation.

[0180] 7. The L2 U2U Relay UE sends the segmented QoS value (i.e., PDB) to the L2 U2U Remote UE via a PC5-RRC message.

[0181] 8. The L2 U2U Remote UE or the serving gNB of the L2 U2U Remote UE can derive the PDCP and SDAP configuration for the end-to-end SL-DRB. The L2 U2U Remote UE can provide some of the configuration related to reception to its peer L2 U2U Remote UE using the end-to-end RRCReconfigurationSidelink message. The end-to-end bearer IDs of the SL-SRB and SL-DRB can be used as inputs for L2 U2U relay ciphering and integrity protection in the SL PDCP.

[0182] 9a. The L2 U2U Remote UE or the serving gNB of the L2 U2U Remote UE derives the first hop configuration for the SL-DRB, and the L2 U2U Remote UE may provide the configuration related to reception at the first hop (i.e., Rx by the relay UE) to the L2 U2U Relay UE using a per-hop RRCReconfigurationSidelink message.

[0183] 9b. The L2 U2U Relay UE or the serving gNB of the L2 U2U Relay UE can derive the second-hop configuration (e.g., PC5 Relay RLC channel configuration) for each SL-DRB. The Relay UE can provide the Peer L2 U2U Remote UE with the configuration related to reception at the second hop (i.e., RX of the Peer Remote UE) using the hop-by-hop RRCReconfigurationSidelink message.

[0184] 10. L2 U2U Remote UE and Peer L2 U2U Remote UE transmit and receive data through L2 U2U Relay UE.

[0185] Below, we describe a method for performing U2U relay selection without a discovery procedure.

[0186] FIG. 15 and FIG. 16 are diagrams for explaining a procedure for U2U relay selection (UE-to-UE Relay Selection) without relay discovery.

[0187] Referring to a given scenario (TR 23.752 section 6.8), when a source UE wants to communicate with a target UE, the source UE may first try to find the target UE by transmitting a Direct Communication Request or Solicitation message containing target UE information. If the source UE cannot reach the target UE directly, the source UE may try to discover a UE-to-UE relay to reach the target UE, and may also trigger the relay to discover the target UE. The source UE may integrate the discovery of the target UE and / or the discovery / selection of a U2U relay based on the following two alternatives:

[0188] - Alternative 1: U2U relay discovery / selection can be integrated into the unicast link setup procedure (see clause 6.3.3 of TS 23.287).

[0189] - Alternative 2: U2U relay discovery / selection can be integrated into the Model B direct discovery procedure.

[0190] A new field may be added to the Direct Communication Request or Solicitation message to indicate whether a relay is available for communication. This new field may be defined as Relay_indication. When a (source) UE broadcasts a Direct Communication Request or Solicitation message, the request message may include Relay_indication indicating whether a U2U relay is available. Meanwhile, for Release 17, the value of Relay_indication may be assumed to be limited to a single hop.

[0191] When the U2U relay receives the request message with the Relay_indication set, the U2U relay can decide whether to forward the request message (i.e., modify the message and broadcast it nearby). For example, the U2U relay can decide whether to forward the request message by considering the Application ID, authorization policy (e.g., Relay for a specific ProSe service), current traffic load of the Relay, and radio conditions between the Source UE and the Relay UE if there is a Relay Service Code.

[0192] Alternatively, multiple U2U relays may be used to reach the target UE (case 1), or the target UE may directly receive the request message from the source UE (case 2). In this case, the target UE may choose whether to respond to either the first or the second case. For example, the target UE may choose whether to respond to either the first or the second case based on signal strength, local policy (e.g., traffic load of the UE-UE relay), relay service code (if any), and / or operator policy (e.g., always preferring direct communication or only using some specific UE-UE relays).

[0193] Alternatively, the source UE may receive responses to the request message from multiple U2U relays, or may receive responses to the request message directly from the target UE. In this case, the source UE may select a communication path (direct path or indirect path) based on signal strength or operator policy (e.g., always preferring direct communication or using only certain UE-UE relays).

[0194] Figure 17 schematically illustrates a flat protocol stack for L2 U2U relay.

[0195] Figure 17(a) illustrates a user plane protocol stack for an L2 U2U relay, and Figure 17(b) illustrates a control plane protocol stack for an L2 U2U relay.

[0196] A given scenario (TR 38.836) defines the Architecture and Protocol Stack of a Layer-2 relay as follows:

[0197] For L2 UE-to-UE Relay architecture, the protocol stack can be similar to L2 UE-to-Network Relay except that the termination points are two Remote UEs. The protocol stacks for the user plane and the control plane of the L2 UE-to-UE Relay architecture can be configured as shown in Fig. 17. The adaptation layer can be supported over the second PC5 link (i.e., the PC5 link between the Relay UE and the Destination UE) for L2 UE-to-UE Relay. For L2 UE-to-UE Relay, the adaptation layer can be positioned above the RLC sublayer for both CP and UP over the second PC5 link. Sidelink SDAP / PDCP and RRC are terminated between the two Remote UEs, while RLC, MAC, and PHY can be terminated on each PC5 link.

[0198] For the first hop of L2 UE-to-UE Relay,

[0199] - N:1 mapping can be supported by the first hop PC5 adaptation layer between the Remote UE SL Radio Bearer and the first hop PC5 RLC channel for relay.

[0200] - The adaptation layer for the first PC5 hop between the Source Remote UE and the Relay UE may be supported to identify traffic destined for different Destination Remote UEs.

[0201] For the second hop of L2 UE-to-UE Relay,

[0202] - The second hop PC5 adaptation layer can be used to support bearer mapping between the ingress RLC channel through the first PC5 hop and the egress RLC channel through the second PC5 hop at the Relay UE.

[0203] - The PC5 adaptation layer can support N:1 bearer mapping between multiple incoming PC5 RLC channels over the first PC5 hop and one egress PC5 RLC channel over the second PC5 hop and can support remote UE identification functionality.

[0204] For L2 UE-to-UE relay,

[0205] - The identification information of the Remote UE end-to-end Radio Bearer can be included in the adaptation layer of the first and second PC5 hops.

[0206] - In addition, the identification information of the Source Remote UE and / or the identification information of the Destination Remote UE may be candidate information to be included in the Adaptation Layer determined in the WI stage.

[0207] Meanwhile, an RRC connection between a source remote UE and a network can be established based on the messages / parameters described below. Specifically, the source remote UE can request an RRC connection to the network via an RRCSetupRequest message. The RRCSetupRequest message can be transmitted using SRB0 (RLC-SAP: TM, Logical channel: CCCH). The RRCSetupRequest message can include an establishmentCause value of the RRC connection based on information provided from a higher layer and UE identification information (UE identity included to facilitate contention resolution by lower layers). In addition, the source remote UE can receive an RRCSetup message for establishing an SRB1 (RLC-SAP: TM, Logical channel: CCCH) from the network. The RRCSetup message may include information for setting up an RLC bearer for SRB1, mac-CellGroupConfig, PhysicalCellGroupConfig and spCellConfig (masterCellGroup), configuration information for sidelink communication (sl-ConfigDedicatedNR), configuration for the remote UE (sl-L2remoteUE-Config: Contains dedicated configurations used for L2 U2N relay related operation. The network configures only the SRAP configuration used for the SRB1 and local UE ID). Here, sl-L2remoteUE-Config may be used to configure L2 U2N relay operation related configurations (e.g., SRAP-Config) used by the L2 U2N remote UE.sl-L2remoteUE-Config may contain identification information for the remote UE (the C-RNTI to the L2 U2N remote UE). SL-SRAP-Config is used to set configurable SRAP parameters used between the L2 U2N relay UE and the L2 U2N remote UE, and may contain a local ID (sl-LocalIdentity) associated with the connection between them (see 3GPP TS 38.331, TS 38.351).

[0208] Although the above describes U2U relay and U2N relay operations based on a single hop (i.e., one relay UE), U2U relay and U2N relay operations may also be performed based on a multi-hop using multiple relay UEs rather than a single relay UE. Therefore, the following describes in detail a method for performing U2U relay and U2N relay operations based on a multi-hop using multiple relay UEs rather than a single relay UE.

[0209] How to establish a connection for multi-hop U2N operation

[0210] Figure 18 is a diagram for explaining the operation of a multi-hop based U2N relay.

[0211] The operation of multi-hop based U2N relay is likely to be addressed in SL relay of a given scenario (3GPP rel-19). Multi-hop based U2N relay operation may be a structure in which data is transmitted / received from the network (or gNB) to the remote UE via multiple hops in the existing U2N operation.

[0212] Referring to Fig. 18 (a), a remote UE can be connected to a network through multiple hops configured through relay UE2 and relay UE1. To be connected to the network through a multi-hop-based relay, the remote UE can form an SL connection or relay connection with relay UE2 as described above, and relay UE2 can also form an SL connection or relay connection with relay UE1. A method for performing an RRC connection in a multi-hop-based U2N relay can be defined as follows.

[0213] (1) In multi-hop U2N relay operation, the discovery message, RRCReconfigurationSidelink, and / or RRCReconfigurationCompleteSidelink message may include a current hop count (and / or a total hop count) indicating how many hops away the relay UE is from the current network (gNB) to which it is directly connected (and / or how many hops away it is from the gNB).

[0214] (2) RRC messages related to multi-hop U2N relay operation

[0215] An RRC message (e.g., an RRCSetupRequest / RRCSetup message) may include at least one of the following information for multihop U2N relay:

[0216] 1) UE type information

[0217] In the conventional single-hop U2N operation, the RRCSetupRequest (or RRC Reestablishment Request, RRC Resume Request) message transmitted by the remote UE and / or relay UE does not include parameters / information indicating the UE type. This is because the UE connected to the relay UE is naturally a remote UE, and the network can determine that the RRCSetupRequest message, which is not received via the RACH, is a message from the remote UE even if the UE type information is not included. In this case, the gNB can configure SL-ConfigDedicatedNR, SL-L2remoteUE-Config, etc. for the remote UE based on the RRCSetupRequest message. Specifically, the gNB can configure the SL RLC channel ID (SL-RLC-ChannelID) to be used for U2N relay communication to the remote UE through SL-ConfigDedicatedNR, and configure the C-RNTI value (sl-UEIdentityRemote) and SRAP of the remote UE through SL-L2remoteUE-Config (sl-SRAP-Configremote). A local ID can be configured in the SRAP configuration. In this case, the remote UE can be allocated the RLC channel ID, local ID, and C-RNTI value to be used for relay communication through the RRCSetup message of the gNB even by transmitting an RRCSetupRequest message that does not include separate UE type information.

[0218] Meanwhile, since the RRCSetupRequest message is transmitted through the RACH, increasing the number of bits may be limited. However, in the case of the RRCSetupRequest message transmitted by the remote UE through the relay UE, since it is a message transmitted by the relay UE that is already RRC-connected to the gNB, the number of bits may not be limited as much as in the case of the RRCSetupRequest message transmitted through the RACH. Accordingly, the bit size and contents of the RRCSetupRequest message transmitted by the relay UE ( / relay UE1) for connection (or direct connection) with the gNB and the RRCSetupRequest message transmitted by the remote UE through the relay UE (that is already in a CONNECTED state with the gNB) may be configured differently.

[0219] Specifically, in multi-hop U2N relay operation, the RRCSetupRequest message transmitted by the remote UE and / or the relay UE needs to further include information about the UE type. This is because it is necessary to distinguish whether the RRCSetupRequest message is for the relay UE or the remote UE. For example, the setting information set by the gNB (or network) through the RRCSetup message may differ depending on whether the sender of the RRCSetupRequest message is the relay UE or the remote UE. Therefore, the gNB needs to confirm or identify the type of UE that transmitted the RRCSetupRequest message.

[0220] 2) Local ID information (and / or hop count information)

[0221] In multi-hop U2N relay operation, the RRCSetupRequest message transmitted by the remote UE and / or relay UE may need to further include information about which hop the relay UE / remote UE is connected to from (and / or from) the relay UE directly connected to the gNB.

[0222] In a multi-hop U2N relay operation, a relay UE1 may have multiple relay UEs (e.g., relay UE2, relay UE3) connected in parallel. For example, referring to FIG. 18 (b), the relay UE1 may form a relay connection with relay UE2 and also form a relay connection with relay UE3. In this case, when the gNB receives the RRCSetupRequest message transmitted by the remote UE through relay UE1, the gNB cannot know whether the remote UE is connected to relay UE2 or relay UE3. Therefore, the RRCSetupRequest message needs to additionally include information regarding which relay UE it is forwarded through.

[0223] For example, in the case of a conventional single-hop U2N operation, the initial RRCSetup ( / RRCReestablishment / RRCResume) request message transmitted by the remote UE may be transmitted via SRB0 (and / or SL-RLC0) or SRB1 (and / or SL-RLC1). In this case, the RRCSetup request message does not include the SRAP header. This is because the remote UE does not know its own local ID and bearer configuration before being allocated the local ID and bearer configuration. In addition, even if the RRCSetup request message is transmitted without information about the local ID and bearer configuration, the gNB can distinguish which relay UE the remote UE is connected to when requesting the RRCSetupRequest message. However, in a multi-hop U2N relay via multiple relay UEs, if a relay UE other than relay UE1 (e.g., relay UE2) transmits a message (RRCSetupRequest, RRCReestablishmentRequest, RRCResumeRequest) related to the initial access of a remote UE to the gNB, the relay UE2 needs to inform which relay UE transmits / forwards the message related to the initial access. For this purpose, even if the message ( / RRCSetupRequest, RRCReestablishmentRequest, RRCResumeRequest) is received via SRB0 ( / SL-RLC0) or SRB1 ( / SL-RLC1), the relay UE that is not directly connected to the gNB (e.g., relay UE2, not relay UE1) needs to attach its own local ID to the SRAP header of the message and transmit it.

[0224] Meanwhile, it can be assumed that the initial access to the gNB in ​​a multi-hop U2N relay via multiple relay UEs is sequential. For example, a remote UE may transmit an initial RRCSetupRequest message (initial access) to a relay UE that is connected to itself via SL or relay, and the relay UE may be in an IDLE / INACTIVE state (or an RRC IDLE / INACTIVE state). In this case, the relay UE may first transmit its own RRCSetupRequest message (the relay UE) to another relay UE that is connected to itself via SL before forwarding the RRCSetupRequest message received from the remote UE. If the relay UE completes the RRC setup based on the RRCSetup received from the network, the relay UE may forward the RRCSetupRequest message received from the remote UE toward the gNB (to another relay UE). That is, if a local ID is assigned for the relay UE, the relay UE can forward the RRCSetup message received from the remote UE toward the gNB.

[0225] In other words, when a relay UE that is not directly connected to the gNB receives an RRC message related to the initial connection of a remote UE, the relay UE may first be allocated a local ID related to itself by transmitting an RRCSetupRequest message of the relay UE to the next hop relay UE before forwarding the RRC message of the remote UE. The relay UE that has been allocated a local ID may transmit the RRC message of the remote UE by including an SRAP header including its local ID in the RRC message of the remote UE.

[0226] At this time, the method of forwarding the RRC message of the remote UE by including the SRAP header including the local ID of the remote UE may be conceptually different from the method of including the local ID in the existing SRAP header. For example, the local ID included in the SRAP of the message generated / transmitted by the remote UE is the local ID of the remote UE, but in the RRC message related to the initial connection of the remote UE, it may be the local ID of the relay UE that (first) forwards the RRC message, not the remote UE. Meanwhile, the local ID included in the RRC message for the initial connection of the remote UE may be the local ID of a relay UE that is directly connected to the remote UE among a plurality of relay UEs (i.e., the relay UE that performs the forwarding first). For example, the RRC message for the initial connection of the remote UE may include only the local ID of the relay UE that is directly connected to the remote UE and may be forwarded to the network.

[0227] The operation of the proposed invention as described above can be applied only to the initial RRC message transmitted by the remote UE (e.g., RRCSetupRequest message). For example, the operation of the proposed invention described above can be applied only to a limited extent to the message transmitted via SL_RLC0 or SL_RLC1.

[0228] Alternatively, the proposed operation can be equally applied to the operation in which a relay UE (e.g., in RRC idle state) that is not directly connected to the gNB accesses (or initially connects) the gNB in ​​a multi-hop U2N relay operation. Alternatively, it can be applied starting from the relay UE corresponding to the second hop from the relay UE that is not directly connected to the gNB. For example, when the connection is in the order of gNB - relay UE1 - relay UE2 - relay UE3 - remote UE, the proposed operation can be applied to relay UE2 and / or relay UE3. For example, the gNB can be aware of the existence of relay UE1 that is directly connected to it, but relay UE2, which is connected to relay UE1 via SL, does not have a local ID assigned to relay UE1 (or between relay UE1 and relay UE2). When relay UE3 transmits an RRCSetupRequest message to gNB for initial connection, relay UE2, which has received the RRCSetupRequest message of relay UE3, can forward / transmit the RRCSetupRequest message of relay UE3 by including its own local ID in the SRAP header of the RRCSetupRequest message of relay UE3.

[0229] Figure 19 is a diagram for explaining a method for a first relay terminal to perform multi-hop based relay communication.

[0230] A multi-hop-based relay may be a relay communication that connects a remote terminal and a network through at least two relays. In this case, the remote terminal and the network may transmit and receive data / messages, etc. through the multi-hop-based relay. The first relay terminal may form a first relay connection, a first direct connection, or a first SL connection with a first device for the multi-hop-based relay, and may form a second relay connection, a second direct connection, or a second SL connection with a second relay terminal, which is another relay terminal. The first relay terminal may forward messages / data transmitted from the first relay connection through the second relay connection, or forward messages / data transmitted from the second relay connection through the first relay connection. Here, the first device may be another relay terminal forming the multi-hop, or may be a remote terminal.

[0231] Referring to FIG. 19, the first relay terminal may receive a first message through the first relay connection formed with the first device (S191). The first message may be a message generated / transmitted by the first device. The first message may include data to be transmitted to the network as described above. Alternatively, the first message may be an RRC message transmitted to the network or a message from the remote UE including data for the network. For example, the RRC message may be a RCSetupRequest message, an RRCReestablishment message, or an RRCResume message related to an initial RRC connection between the first device and the network. That is, the first message may include an RRC (Radio Resource Control) control message transmitted through SRB0 (Signalling Radio Bearer 0) or SRB1 (Signalling Radio Bearer 0).

[0232] Alternatively, if the first message is a message generated and transmitted by the first device, the first message may further include type information regarding whether the first device is a relay terminal or a remote terminal. For example, if the first device is a relay terminal, the first message may include type information regarding the relay terminal, and if the first device is a remote terminal, the first message may include type information regarding the remote terminal. This is because, as described above, in relay communication via multi-hop, a relay terminal can also transmit a message for RRC connection with a network, and the RRC setting method of a base station may differ depending on whether it is a relay terminal or a remote terminal.

[0233] Next, when the first relay terminal is not directly connected (or has an RRC connection) with the network (i.e., is in an RRC idle state or an RRC inactive state), the first relay terminal may transmit an RRC setup request message (RRCSetupRequest message, or request message) to the network to request an RRC connection with the first relay terminal (S193). For example, the first relay terminal that is not directly connected with the network may transmit its RRC setup request message through the second relay connection based on reception of the first message. In this case, the first relay terminal may receive an RRCSetup message for establishing an RRC connection from the network through the second relay connection, and the RRCSetup message may include a local ID for the first relay terminal or related to the second relay terminal. The request message may further include type information indicating that the RRC connection request is for the relay terminal. Alternatively, the request message may further include information about which hop the first relay terminal is in the multi-hop based relay (from the network or from a relay terminal directly connected to the network).

[0234] Meanwhile, if the first relay terminal has already established an RRC connection with the network, the first relay terminal may not perform an operation of transmitting the request message.

[0235] Next, the first relay terminal can perform forwarding for the first message via the second relay connection (S195). Here, the second relay connection may be a connection formed with another relay terminal (hereinafter, a third relay terminal) for the multi-hop relay.

[0236] Alternatively, the first relay terminal may forward the first message in a different manner depending on the type of the first message. For example, the first relay terminal may determine whether to forward the first message by additionally including its own local ID (identification) based on whether the first message is a message requesting an initial connection between the first device and a network. For example, if the first message is a message requesting an initial connection between the first device and a network (an RRCSetupRequest message, an RRCReestablishment message, or an RRCResume message), the first relay terminal may further include its own local ID in the first message, and transmit the first message (or the second message) including its own local ID through the second relay connection. Alternatively, if the first message is an RRC (Radio Resource Control) message transmitted through SRB0 (Signalling Radio Bearer 0) or SRB1 (Signalling Radio Bearer 0) between the first device and the network, the first relay terminal may further include its local ID in the first message and forward the first message (or the second message) further including its local ID through the second relay connection.

[0237] In contrast, if the first message is not an RRC message for initial connection with the network (i.e., if it is a message including data of the first device), the first relay terminal may forward the first message without including its own local ID in the first message. In this case, since the first message already includes a local ID for the first device, the first relay terminal does not need to additionally include a separate local ID for itself in the first message to forward the first message.

[0238] Alternatively, if the first message is a message requesting an RRC connection of a device other than the first device, the first relay terminal may forward the first message without including its own local ID in the first message. For example, if the first device is a relay terminal and the first message is a message requesting an RRC connection to a remote terminal connected to the relay terminal, the first message may already include a local ID for the first device, which is the relay terminal. In this case, the first relay terminal may forward the first message through the second relay connection without replacing or adding its own local ID to the first message. That is, only the local ID for the relay terminal that has directly formed a relay connection with the device that transmitted the first message may be included in the first message and forwarded.

[0239] Figure 20 is a drawing for explaining a method for a second relay terminal to perform multi-hop based relay communication.

[0240] The second relay terminal may be a relay terminal that forms a second relay connection with the first relay terminal for the multi-hop relay, as described with reference to FIG. 19. Alternatively, the second relay terminal may form a third relay connection (or directly connect to a network) with another relay terminal for the multi-hop-based relay.

[0241] Referring to FIG. 20, the second relay terminal can receive a second message forwarded by the first relay terminal through the second relay connection (S201). The second message may be a message forwarding the first message generated by the first device as described above. As described above, based on the fact that the first message is a message requesting an initial connection between the first device and a network, the second message may further include a local ID associated with the first relay terminal.

[0242] Next, the second relay terminal can perform forwarding for the second message through the third relay connection (S203).

[0243] In this way, the proposed invention can clearly identify the relay connection related to the RRC message in the network by further including a local ID for the relay terminal in the RRC message of the first device for initial connection in a multi-hop based relay. Alternatively, the proposed invention can ensure an RRC setting corresponding to the transmission subject of the RRC request message in the network by further including type information about the transmission subject of the RRC message in the RRC message for initial connection in a multi-hop based relay.

[0244] Examples of communication systems to which the invention applies

[0245] Although not limited thereto, the various descriptions, functions, procedures, proposals, methods and / or operational flowcharts of the present invention disclosed in this document may be applied to various fields requiring wireless communication / connection (e.g., 5G) between devices.

[0246] Hereinafter, more specific examples will be provided with reference to the drawings. In the drawings / descriptions below, the same drawing reference numerals may represent identical or corresponding hardware blocks, software blocks, or functional blocks, unless otherwise described.

[0247] Figure 21 illustrates a communication system applied to the present invention.

[0248] Referring to FIG. 21, a communication system (1) applied to the present invention includes a wireless device, a base station, and a network. Here, the wireless device refers to a device that performs communication using a 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 Things) device (100f), and an AI device / server (400). For example, the vehicle may include a vehicle equipped with a wireless communication function, an autonomous vehicle, a vehicle capable of performing vehicle-to-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 HMD (Head-Mounted Device), HUD (Head-Up Display) installed in a vehicle, television, smartphone, computer, wearable device, home appliance, digital signage, vehicle, robot, etc. Mobile devices can include smartphone, smart pad, wearable device (e.g., smart watch, smart glass), computer (e.g., laptop, etc.), etc. Home appliances can include TV, refrigerator, washing machine, etc. IoT devices can include sensors, smart meters, etc. For example, base stations and networks can also be implemented as wireless devices, and a specific wireless device (200a) can act as a base station / network node to other wireless devices.

[0249] Wireless devices (100a to 100f) can be connected to a network (300) via a base station (200). Artificial Intelligence (AI) technology can be applied to the wireless devices (100a to 100f), and the wireless devices (100a to 100f) can be connected to an AI server (400) via the network (300). The network (300) can be configured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR) network, etc. The wireless devices (100a to 100f) can communicate with each other via the base station (200) / network (300), but can 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). In addition, IoT devices (e.g., sensors) can communicate directly with other IoT devices (e.g., sensors) or other wireless devices (100a to 100f).

[0250] Wireless communication / connection (150a, 150b, 150c) can be established between wireless devices (100a~100f) / base stations (200), and base stations (200) / base stations (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 communication between base stations (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 each other. For example, wireless communication / connection (150a, 150b, 150c) can transmit / receive signals through various physical channels. To this end, at least some of 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.), and resource allocation processes can be performed based on various proposals of the present invention.

[0251] Examples of wireless devices to which the present invention is applied

[0252] Figure 22 illustrates a wireless device applicable to the present invention.

[0253] 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)} can correspond to {the wireless device (100x), the base station (200)} and / or {the wireless device (100x), the wireless device (100x)} of FIG. 21.

[0254] A first wireless device (100) includes one or more processors (102) and one or more memories (104), and may further include one or more transceivers (106) and / or one or more antennas (108). The processor (102) controls the memories (104) and / or the transceivers (106), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in this document. For example, the processor (102) may process information in the memory (104) to generate first information / signal, and then transmit a wireless signal including the first information / signal via the transceiver (106). In addition, the processor (102) may receive a wireless signal including second information / signal via the transceiver (106), and then store information obtained from 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 perform some or all of the processes controlled by the processor (102), or may store software code including commands for performing the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts 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 via one or more antennas (108). The transceiver (106) may include a transmitter and / or a receiver. The transceiver (106) may be used interchangeably with an RF (Radio Frequency) unit. In the present invention, a wireless device may also mean a communication modem / circuit / chipset.

[0255] Specifically, the first wireless device or first relay terminal (100) may include a processor (102) and a memory (104) connected to a transceiver (106). The memory (104) may include at least one program capable of performing operations related to the embodiments described in FIGS. 18 to 20.

[0256] The processor (102) controls the transceiver (106) to receive a first message through the first relay connection formed with the first device, and forward the first message further including a local ID (identification) related to the first relay terminal through the second relay connection based on the first message being a message requesting an initial connection between the first device and a network.

[0257] Alternatively, a processing device may be configured including a processor (102) and a memory (104). In this case, at least one processor; and at least one memory connected to the at least one processor and storing instructions, wherein the instructions, based on being executed by the at least one processor, cause the first relay terminal to: receive a first message through the first relay connection formed with the first device, and forward the first message, further including a local ID (identification) associated with the first relay terminal, through the second relay connection based on the first message being a message requesting an initial connection between the first device and a network.

[0258] The second wireless device (200) includes one or more processors (202), one or more memories (204), and may further include one or more transceivers (206) and / or one or more antennas (208). The processor (202) controls the memories (204) and / or the transceivers (206), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in this document. For example, the processor (202) may process information in the memory (204) to generate third information / signals, and then transmit a wireless signal including the third information / signals via the transceivers (206). Furthermore, the processor (202) may receive a wireless signal including fourth information / signals via the transceivers (206), and then store information obtained from signal processing of the fourth information / signals 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 perform some or all of the processes controlled by the processor (202), or may store software code including commands for performing the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts 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 via one or more antennas (208). The transceiver (206) may include a transmitter and / or a receiver. The transceiver (206) may be used interchangeably with an RF unit. In the present invention, a wireless device may also mean a communication modem / circuit / chip.

[0259] Specifically, the second wireless device or second relay terminal (200) may include a processor (202) and a memory (204) connected to a transceiver (206). The memory (204) may include at least one program capable of performing operations related to the embodiments described in FIGS. 18 to 20.

[0260] The processor (202) controls the transceiver (206) to receive a second message, in which the first relay terminal forwards a first message to the first device through the second relay connection formed with the first relay terminal, and to perform forwarding of the second message through the third relay connection. Here, based on the fact that the first message is a message requesting an initial connection between the first device and a network, the second message may include a local ID associated with the first relay terminal.

[0261] Hereinafter, the 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 one or more Service Data Units (SDUs) according to the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts 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 operation flowcharts disclosed in this document. One or more processors (102, 202) can generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data or information according to the functions, procedures, proposals and / or methods disclosed herein, and provide the signals to one or more transceivers (106, 206). One or more processors (102, 202) can receive signals (e.g., baseband signals) from one or more transceivers (106, 206) and obtain PDUs, SDUs, messages, control information, data or information according to the descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed herein.

[0262] One or more processors (102, 202) may be referred to as a controller, a microcontroller, a microprocessor, or a 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 operational 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. The descriptions, functions, procedures, suggestions, methods and / or operation flowcharts disclosed in this document may be implemented using firmware or software configured to perform one or more processors (102, 202) or stored in one or more memories (104, 204) and executed by one or more processors (102, 202). The descriptions, functions, procedures, suggestions, methods and / or operation flowcharts disclosed in this document may be implemented using firmware or software in the form of codes, instructions and / or sets of instructions.

[0263] One or more memories (104, 204) may be coupled to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. The one or more memories (104, 204) may be configured as ROM, RAM, EPROM, flash memory, hard drives, registers, cache memory, computer-readable storage media, and / or combinations thereof. The one or more memories (104, 204) may be located internally and / or externally to the one or more processors (102, 202). Additionally, the one or more memories (104, 204) may be coupled to the one or more processors (102, 202) via various technologies, such as wired or wireless connections.

[0264] One or more transceivers (106, 206) can transmit user data, control information, wireless signals / channels, etc., as mentioned in the methods and / or flowcharts of this document, to one or more other devices. One or more transceivers (106, 206) can receive user data, control information, wireless signals / channels, etc., as mentioned in the descriptions, functions, procedures, proposals, methods and / or flowcharts of this document, from one or more other devices. For example, one or more transceivers (106, 206) can be connected to one or more processors (102, 202) and can transmit and receive wireless signals. For example, one or more processors (102, 202) can 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 coupled 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, or the like, as referred to in the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed herein, via 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 received user data, control information, wireless signals / channels, etc. from RF band signals to baseband signals in order to process the received user data, control information, wireless signals / channels, etc. using one or more processors (102, 202).One or more transceivers (106, 206) may convert user data, control information, wireless signals / channels, etc. processed by one or more processors (102, 202) from baseband signals to RF band signals. For this purpose, one or more transceivers (106, 206) may include an (analog) oscillator and / or filter.

[0265] Examples of wireless devices to which the present invention is applied

[0266] Figure 23 illustrates another example of a wireless device applicable to the present invention. The wireless device may be implemented in various forms depending on the use case / service (see Figure 21).

[0267] 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 / units, 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 an additional element (140). The communication unit may include a communication circuit (112) and a 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 the additional elements (140) and controls the overall operation of the wireless device. For example, the control unit (120) may control the electrical / mechanical operation of the wireless device based on the program / code / command / information stored in the memory unit (130). In addition, the control unit (120) may transmit information stored in the memory unit (130) to an external device (e.g., another communication device) via a wireless / wired interface through the communication unit (110), or store information received from an external device (e.g., another communication device) via a wireless / wired interface in the memory unit (130).

[0268] The additional element (140) may be configured in various ways depending on the type of the 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 a financial device), a security device, a climate / environmental device, an AI server / device (Fig. 21, 400), a base station (Fig. 21, 200), a network node, etc. Wireless devices may be mobile or stationary depending on the use / service.

[0269] 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 some 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 a first unit (e.g., 130, 140) may be wirelessly connected via the communication unit (110). In addition, each element, component, unit / part, and / or module within the wireless device (100, 200) may further include one or more elements. For example, the control unit (120) may be composed of a set of one or more 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.

[0270] Examples of vehicles or autonomous vehicles to which the present invention is applied

[0271] Figure 24 illustrates a vehicle or autonomous vehicle applicable to the present invention. The vehicle or autonomous vehicle may be implemented as a mobile robot, car, train, manned / unmanned aerial vehicle (AV), ship, etc.

[0272] 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 a part of the communication unit (110). Blocks 110 / 130 / 140a to 140d correspond to blocks 110 / 130 / 140 of FIG. 23, respectively.

[0273] 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, road side units, etc.), and servers. The control unit (120) can control elements of the vehicle or autonomous vehicle (100) to perform various operations. The control unit (120) can include an ECU (Electronic Control Unit). The drive unit (140a) can drive the vehicle or autonomous vehicle (100) on the ground. The drive unit (140a) can include an engine, a motor, a power train, wheels, brakes, a steering device, etc. The power supply unit (140b) supplies power to the vehicle or autonomous vehicle (100) and can include a wired / wireless charging circuit, a battery, 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 incline sensor, a weight detection sensor, a heading sensor, a position module, a vehicle forward / backward 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 a technology for maintaining a driving lane, a technology for automatically controlling speed such as adaptive cruise control, a technology for automatically driving along a set path, a technology for automatically setting a path and driving when a destination is set, etc.

[0274] 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 route and driving plan based on the acquired data. The control unit (120) can control the drive unit (140a) so that the vehicle or autonomous vehicle (100) moves along the autonomous driving route according to the driving plan (e.g., speed / direction control). During autonomous driving, the communication unit (110) can irregularly / periodically acquire the latest traffic information data from an external server and can acquire surrounding traffic information data from surrounding vehicles. In addition, 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 route and driving plan based on newly acquired data / information. The communication unit (110) can transmit information regarding the vehicle location, autonomous driving route, driving plan, etc. to the external server. External servers can predict traffic information data in advance using AI technology or other technologies based on information collected from vehicles or autonomous vehicles, and provide the predicted traffic information data to the vehicles or autonomous vehicles.

[0275] Here, the wireless communication technology implemented in the wireless device (XXX, YYY) of the present specification may include not only LTE, NR, and 6G, but also Narrowband Internet of Things for low-power communication. At this time, for example, NB-IoT technology may be an example of LPWAN (Low Power Wide Area Network) technology, and may be implemented with standards such as LTE Cat NB1 and / or LTE Cat NB2, and is not limited to the above-described names. Additionally or alternatively, the wireless communication technology implemented in the wireless device (XXX, YYY) of the present specification may perform communication based on LTE-M technology. At this time, for example, LTE-M technology may be an example of LPWAN technology, and may be called by various names such as eMTC (enhanced Machine Type Communication). For example, LTE-M technology can be implemented by 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 above-described names. Additionally or alternatively, the wireless communication technology implemented in the wireless device (XXX, YYY) of the present specification can include at least one of ZigBee, Bluetooth, and Low Power Wide Area Network (LPWAN) considering low-power communication, and is not limited to the above-described names. For example, ZigBee technology can create PAN (personal area networks) related to small / low-power digital communication based on various standards such as IEEE 802.15.4, and can be called by various names.

[0276] The embodiments described above are combinations of components and features of the present invention in a predetermined form. Each component or feature should be considered optional unless explicitly stated otherwise. Each component or feature may be implemented without being combined with other components or features. Furthermore, it is also possible to form an embodiment 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 self-evident that claims that do not have an explicit citation relationship in the patent claims may be combined to form an embodiment or may be incorporated as a new claim through a post-application amendment.

[0277] In this document, embodiments of the present invention have been described primarily focusing on the signal transmission and reception relationship between a terminal and a base station. This transmission and reception relationship is equally / similarly extended to signal transmission and reception between a terminal and a relay or a base station and a relay. Certain operations described as being performed by a base station in this document may, in some cases, be performed by its upper node. That is, it is obvious that various operations performed for communication with a terminal in a network composed 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. In addition, the terminal may be replaced by terms such as UE (User Equipment), MS (Mobile Station), MSS (Mobile Subscriber Station).

[0278] Embodiments of the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of hardware implementation, an embodiment of the present invention may be implemented by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, etc.

[0279] When implemented via firmware or software, an embodiment of the present invention may be implemented in the form of modules, procedures, functions, etc. that perform the functions or operations described above. The software code may be stored in a memory unit and executed by a processor. The memory unit may be located within or outside the processor and may exchange data with the processor via various known means.

[0280] It will be apparent to those skilled in the art that the present invention can be embodied in other specific forms without departing from the scope of the invention. Therefore, the above detailed description should not be construed as limiting in any respect, but rather as illustrative. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all modifications within the scope of equivalents of the present invention are intended to be included within the scope of the present invention.

[0281] The embodiments of the present invention as described above can be applied to various mobile communication systems.

Claims

1. In a method for performing relay communication by a first relay terminal that has formed a first relay connection and a second relay connection for multi-hop based relay in a wireless communication system, A step of receiving a first message through the first relay connection formed with the first device; and A step of performing forwarding for the first message through the second relay connection is included, A method wherein the first relay terminal forwards the first message, which further includes a local ID (identification) associated with the first relay terminal, based on the first message being a message requesting an initial connection between the first device and a network.

2. In paragraph 1, A method characterized in that it further comprises a step of transmitting a request message requesting an RRC connection between the network and the first relay UE through the second relay connection based on the fact that the first relay terminal is not directly connected to the network.

3. In paragraph 2, A method characterized in that the first relay terminal performs forwarding for the first message based on the local ID assigned from the network based on the request message.

4. In paragraph 2, A method, characterized in that the request message further includes information on which hop the first relay terminal is from the network.

5. In paragraph 1, A method, characterized in that the first message further includes type information on whether the first device is a relay terminal or a remote terminal.

6. In paragraph 1, A method, characterized in that the first message is an RRCSetupRequest message, an RRCReestablishment message, or an RRCResume message requesting an RRC (Radio Resource Control) connection between the first device and the network.

7. In paragraph 1, A method, characterized in that the first message requesting the initial connection is an RRC (Radio Resource Control) message transmitted via SRB0 (Signalling Radio Bearer 0) or SRB1 (Signalling Radio Bearer 0).

8. In paragraph 1, A method, characterized in that the local ID is included in the SRAP (sidelink relay adaptation protocol) header of the first message.

9. In paragraph 1, A method characterized in that, based on the fact that the first message is a message from a device other than the first device, the first relay terminal forwards the first message that does not include a local ID associated with the first relay terminal.

10. In paragraph 1, A method characterized in that the above multi-hop based relay is a U2N (User equipment to Network) relay for transmitting and receiving data between a remote terminal and a network.

11. A computer-readable recording medium recording a program for performing the method described in paragraph 1.

12. In a first relay terminal that forms a first relay connection and a second relay connection for multi-hop based relay in a wireless communication system, RF (Radio Frequency) transmitter and receiver; and A processor connected to the RF transceiver, A first relay terminal, wherein the processor controls the RF transceiver to receive a first message through the first relay connection formed with the first device, and forwards the first message further including a local ID (identification) associated with the first relay terminal through the second relay connection based on the first message being a message requesting an initial connection between the first device and a network.

13. In a processing device for controlling a first relay terminal that forms a first relay connection and a second relay connection for multi-hop based relay in a wireless communication system, at least one processor; and At least one memory connected to said at least one processor and storing instructions, said instructions being executed by said at least one processor, wherein said first relay terminal: A processing device that receives a first message through the first relay connection formed with the first device, and forwards the first message further including a local ID (identification) associated with the first relay terminal through the second relay connection based on the first message being a message requesting an initial connection between the first device and a network.

14. In a method for performing relay communication by a second relay terminal that has formed a second relay connection and a third relay connection for multi-hop based relay in a wireless communication system, A step of receiving a second message for forwarding a first message to a first device by the first relay terminal through the second relay connection formed with the first relay terminal; and A step of performing forwarding for the second message through the third relay connection is included, A method wherein the second message includes a local ID associated with the first relay terminal, based on the first message being a message requesting an initial connection between the first device and the network.

15. In a second relay terminal that forms a second relay connection and a third relay connection for multi-hop based relay in a wireless communication system, RF (Radio Frequency) transmitter and receiver; and A processor connected to the RF transceiver, The processor controls the RF transceiver to receive a second message for forwarding a first message to the first device through the second relay connection formed with the first relay terminal, and performs forwarding for the second message through the third relay connection. A second relay terminal, wherein the second message includes a local ID (identification) associated with the first relay terminal, based on the first message being a message requesting an initial connection between the first device and the network.

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