Relay-based communication

Abstract

One disclosure of the present specification provides a method. The method may comprise the steps of: receiving, from a DU of a base station, a sidelink user equipment (UE) information message transmitted by a second relay UE via a first relay UE; and transmitting, to the DU of the base station, a request message related to a UE context.

Description

Relay-based communication

[0001] This specification relates to mobile communications.

[0002] 3GPP (3rd Generation Partnership Project) LTE (Long-Term Evolution) is a technology designed to enable high-speed packet communications. Numerous approaches have been proposed to achieve LTE's goals of reducing costs for users and operators, improving service quality, expanding coverage, and increasing system capacity. 3GPP LTE's high-level requirements include reduced cost per bit, improved service availability, flexible use of frequency bands, a simple architecture, open interfaces, and adequate power consumption for terminals.

[0003] The International Telecommunication Union (ITU) and 3GPP have begun work on developing requirements and specifications for New Radio (NR) systems. 3GPP must identify and develop the technical components necessary to successfully standardize NR, meeting both urgent market needs and the longer-term requirements outlined by the ITU Radio communication sector (ITU-R) International Mobile Telecommunications (IMT)-2020 process. NR must also be able to utilize any spectrum band up to at least 90 GHz, ensuring that it remains available for wireless communications well into the future.

[0004] NR aims to be a single technology framework that addresses all deployment scenarios, usage scenarios, and requirements, including enhanced Mobile Broadband (eMBB), massive Machine Type Communications (mMTC), and Ultra-Reliable and Low Latency Communications (URLLC). NR must be inherently forward-compatible.

[0005] U2N (UE-to-Network) relay, where a remote UE (User Equipment) connects to a base station via a relay UE, has been introduced. However, previous discussions focused only on single-hop scenarios, where a remote UE connects to a single relay UE. The problem is that there is no effective solution for multi-hop scenarios, where a remote UE connects to multiple relay UEs.

[0006] According to one embodiment of the present disclosure, a method is provided. The method may include the steps of: receiving a sidelink UE information message transmitted by a second relay User Equipment (UE) through a first relay UE from a base station's DU; and transmitting a request message related to a UE context to the base station's DU.

[0007] According to one embodiment, a device implementing the method is provided.

[0008] According to one embodiment of the present disclosure, a method is provided. The method may include: a second relay UE receiving an RRC setup request message from a remote UE; and a second relay UE transmitting a sidelink UE information message to a base station via a first relay.

[0009] According to one embodiment, a device implementing the method is provided.

[0010] Figure 1 illustrates an example of a communication system to which the implementation of this specification is applied.

[0011] Figure 2 illustrates an example of a wireless device to which the implementation of the present specification is applied.

[0012] Figure 3 shows an example of a UE to which the implementation of this specification is applied.

[0013] Figure 4 shows an example of a 5G system structure to which the implementation of this specification is applied.

[0014] FIGS. 5A to 5E illustrate examples of RACH procedures applicable to one embodiment of the present disclosure.

[0015] FIGS. 6A to 6C are first examples of procedures related to initial connection of a remote UE according to one embodiment of the disclosure of the present specification.

[0016] FIGS. 7A to 7C are a second example of a procedure related to initial connection of a remote UE according to one embodiment of the disclosure of the present specification.

[0017] FIG. 8A and FIG. 8B are examples of procedures related to path switching according to one embodiment of the disclosure of the present specification.

[0018] FIG. 9 illustrates an example of a procedure according to one embodiment of the disclosure of the present specification.

[0019] The following techniques, devices, and systems can be applied to various wireless multiple access systems. Examples of multiple access systems include Code Division Multiple Access (CDMA) systems, Frequency Division Multiple Access (FDMA) systems, Time Division Multiple Access (TDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single Carrier Frequency Division Multiple Access (SC-FDMA) systems, and Multi-Carrier Frequency Division Multiple Access (MC-FDMA) systems. CDMA can be implemented using wireless technologies such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can be implemented using wireless technologies such as Global System for Mobile communications (GSM), General Packet Radio Service (GPRS), or Enhanced Data rates for GSM Evolution (EDGE). OFDMA can be implemented using wireless technologies such as IEEE (Institute of Electrical and Electronics Engineers) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, or Evolved UTRA (E-UTRA). UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3GPP (3rd Generation Partnership Project) Long-Term Evolution (LTE) is part of E-UMTS (Evolved UMTS) that utilizes E-UTRA.3GPP LTE uses OFDMA in the downlink (DL) and SC-FDMA in the uplink (UL). Evolution of 3GPP LTE includes LTE-A (Advanced), LTE-A Pro, and / or 5G NR (New Radio).

[0020] For convenience of explanation, the implementation of this specification is primarily described in relation to a 3GPP-based wireless communication system. However, the technical features of this specification are not limited thereto. For example, the following detailed description is provided based on a mobile communication system corresponding to a 3GPP-based wireless communication system, but aspects of this specification that are not limited to a 3GPP-based wireless communication system can be applied to other mobile communication systems.

[0021] For terms and technologies used in this specification that are not specifically described, reference may be made to wireless communication standard documents published prior to this specification.

[0022] As used herein, "A or B" can mean "only A," "only B," or "both A and B." Alternatively, as used herein, "A or B" can be interpreted as "A and / or B." For example, as used herein, "A, B or C" can mean "only A," "only B," "only C," or "any combination of A, B and C."

[0023] As used herein, a slash ( / ) or a comma can mean "and / or." For example, "A / B" can mean "A and / or B." Accordingly, "A / B" can mean "only A," "only B," or "both A and B." For example, "A, B, C" can mean "A, B, or C."

[0024] In this specification, “at least one of A and B” may mean “only A,” “only B,” or “both A and B.” Additionally, in this specification, the expressions “at least one of A or B” or “at least one of A and / or B” may be interpreted identically to “at least one of A and B.”

[0025] Additionally, in this specification, “at least one of A, B and C” can mean “only A”, “only B”, “only C”, or “any combination of A, B and C”. Additionally, “at least one of A, B or C” or “at least one of A, B and / or C” can mean “at least one of A, B and C”.

[0026] Additionally, parentheses used herein may mean "for example." Specifically, when indicated as "control information (PDCCH)", "PDCCH" may be proposed as an example of "control information." In other words, "control information" in this specification is not limited to "PDCCH," and "PDCCH" may be proposed as an example of "control information." Furthermore, even when indicated as "control information (i.e., PDCCH)", "PDCCH" may be proposed as an example of "control information."

[0027] Technical features individually described in a single drawing in this specification may be implemented individually or simultaneously.

[0028] Although not limited thereto, the various descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed herein may be applied to various fields requiring wireless communication and / or connectivity between devices (e.g., 5G).

[0029] Hereinafter, the present specification will be described in more detail with reference to the drawings. In the following drawings and / or description, the same reference numbers may refer to the same or corresponding hardware blocks, software blocks, and / or functional blocks, unless otherwise indicated.

[0030] Figure 1 illustrates an example of a communication system to which the implementation of this specification is applied.

[0031] The 5G usage scenario shown in FIG. 1 is only an example, and the technical features of this specification can be applied to other 5G usage scenarios not shown in FIG. 1.

[0032] The three main requirement categories for 5G are (1) enhanced mobile broadband (eMBB), (2) massive machine type communication (mMTC), and (3) ultra-reliable and low latency communications (URLLC).

[0033] Referring to FIG. 1, a communication system (1) includes wireless devices (100a to 100f), a base station (BS; 200), and a network (300). FIG. 1 illustrates a 5G network as an example of a network of the communication system (1), but the implementation of the present disclosure is not limited to a 5G system and can be applied to future communication systems beyond the 5G system.

[0034] The base station (200) and the network (300) may be implemented as wireless devices, and a particular wireless device may operate as a base station / network node in relation to other wireless devices.

[0035] The wireless devices (100a to 100f) represent devices that perform communication using Radio Access Technology (RAT) (e.g., 5G NR or LTE) and may also be referred to as communication / wireless / 5G devices. The wireless devices (100a to 100f) may include, but are not limited to, a robot (100a), a vehicle (100b-1 and 100b-2), an extended reality (XR) device (100c), a portable device (100d), a home appliance (100e), an Internet-of-Things (IoT) device (100f), and an artificial intelligence (AI) device / server (400). For example, the vehicles may include vehicles having wireless communication capabilities, autonomous vehicles, and vehicles capable of performing vehicle-to-vehicle communication. The vehicles may include unmanned aerial vehicles (UAVs) (e.g., drones). XR devices may include AR (Augmented Reality) / VR (Virtual Reality) / MR (Mixed Reality) devices, and may be implemented in the form of HMD (Head-Mounted Device) and HUD (Head-Up Display) mounted on vehicles, televisions, smartphones, computers, wearable devices, home appliances, digital signs, vehicles, robots, etc. Portable devices may include smartphones, smart pads, wearable devices (e.g., smart watches or smart glasses), and computers (e.g., laptops). Home appliances may include TVs, refrigerators, and washing machines. IoT devices may include sensors and smart meters.

[0036] In this specification, wireless devices (100a to 100f) may be referred to as user equipment (UE). The UE may include, for example, a mobile phone, a smartphone, a laptop computer, a digital broadcasting terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), a navigation system, a slate PC, a tablet PC, an ultrabook, a vehicle, a vehicle with autonomous driving function, a connected car, a UAV, an AI module, a robot, an AR device, a VR device, an MR device, a hologram device, a public safety device, an MTC device, an IoT device, a medical device, a fintech device (or a financial device), a security device, a weather / environmental device, a 5G service-related device, or a 4th industrial revolution-related device.

[0037] Wireless devices (100a to 100f) can be connected to a network (300) via a base station (200). 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, and a network after 5G. 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 (200) / network (300). For example, vehicles (100b-1, 100b-2) can communicate directly (e.g., vehicle-to-vehicle (V2V) / vehicle-to-everything (V2X) communication). Additionally, IoT devices (e.g., sensors) can communicate directly with other IoT devices (e.g., sensors) or other wireless devices (100a to 100f).

[0038] Wireless communication / connection (150a, 150b, 150c) can be established between wireless devices (100a to 100f) and / or between wireless devices (100a to 100f) and a base station (200) and / or between base stations (200). Here, the wireless communication / connection can be established through various RATs (e.g., 5G NR), such as uplink / downlink communication (150a), sidelink communication (150b) (or, D2D (Device-To-Device) communication), and base station-to-base station communication (150c) (e.g., relay, IAB (Integrated Access and Backhaul)). Through the wireless communication / connection (150a, 150b, 150c), the wireless devices (100a to 100f) and the base station (200) can transmit / receive wireless signals to / from each other. For example, wireless communication / connection (150a, 150b, 150c) can transmit / receive signals through various physical channels. To this end, at least some of the 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 specification.

[0039] NR supports multiple numerologies, or subcarrier spacings (SCS), to support diverse 5G services. For example, an SCS of 15 kHz supports wide areas in traditional cellular bands; an SCS of 30 kHz / 60 kHz supports dense urban areas, lower latency, and wider carrier bandwidth; and an SCS of 60 kHz or higher supports bandwidths greater than 24.25 GHz to overcome phase noise.

[0040] The NR frequency band can be defined by two types of frequency ranges (FR1 and FR2). The numerical values ​​of the frequency ranges can be changed. For example, the two types of frequency ranges (FR1 and FR2) can be as shown in Table 1 below. For convenience of explanation, 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," which can be called millimeter wave (mmW).

[0041] Frequency Range DefinitionFrequency RangeSubcarrier SpacingFR1450MHz - 6000MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0042] 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 2 below. That is, FR1 may include frequency bands above 6 GHz (or 5850, 5900, 5925 MHz, etc.). For example, the frequency bands above 6 GHz (or 5850, 5900, 5925 MHz, etc.) included within FR1 may include unlicensed bands. Unlicensed bands may be used for various purposes, such as for communications for vehicles (e.g., autonomous driving).

[0043] Frequency Range DefinitionFrequency RangeSubcarrier SpacingFR1410MHz - 7125MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0044] Here, the wireless communication technology implemented in the wireless device of the present specification may include not only LTE, NR, and 6G, but also Narrowband IoT (NB-IoT) for low-power communication. For example, NB-IoT technology may be an example of LPWAN (Low Power Wide Area Network) technology and may be implemented 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 of the present specification may perform communication based on LTE-M technology. For example, LTE-M technology may be an example of LPWAN technology and may be called by various names such as eMTC (enhanced MTC). 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 MTC, 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 of the present specification can include at least one of ZigBee, Bluetooth, and / or LPWAN considering low-power communication, and is not limited to the above-described names. For example, ZigBee technology can create PANs (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.

[0045] Figure 2 illustrates an example of a wireless device to which the implementation of the present specification is applied.

[0046] In FIG. 2, the first wireless device (100) and / or the second wireless device (200) may be implemented in various forms depending on the use case / service. For example, {the first wireless device (100) and the second wireless device (200)} may correspond to at least one of {the wireless devices (100a to 100f) and the base station (200)}, {the wireless devices (100a to 100f) and the wireless devices (100a to 100f)}, and / or {the base station (200) and the base station (200)} of FIG. 1. The first wireless device (100) and / or the second wireless device (200) may be configured by various components, devices / parts, and / or modules.

[0047] The first wireless device (100) may include at least one transceiver, such as a transceiver (106), at least one processing chip, such as a processing chip (101), and / or one or more antennas (108).

[0048] The processing chip (101) may include at least one processor, such as a processor (102), and at least one memory, such as a memory (104). Additionally and / or alternatively, the memory (104) may be located external to the processing chip (101).

[0049] The processor (102) may control the memory (104) and / or the transceiver (106) and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed herein. For example, the processor (102) may process information in the memory (104) to generate first information / signal and transmit a wireless signal including the first information / signal via the transceiver (106). The processor (102) may receive a wireless signal including second information / signal via the transceiver (106) and store information obtained by processing the second information / signal in the memory (104).

[0050] A memory (104) may be operatively connected to the processor (102). The memory (104) may store various types of information and / or instructions. The memory (104) may store firmware and / or software code (105) that implements code, instructions and / or sets of instructions that, when executed by the processor (102), perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed herein. For example, the firmware and / or software code (105) may implement instructions that, when executed by the processor (102), perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed herein. For example, the firmware and / or software code (105) may control the processor (102) to perform one or more protocols. For example, the firmware and / or software code (105) may control the processor (102) to perform one or more air interface protocol layers.

[0051] Here, the processor (102) and memory (104) may be part of a communication modem / circuit / chip designed to implement a RAT (e.g., LTE or NR). A transceiver (106) may be connected to the processor (102) and may transmit and / or receive wireless signals via one or more antennas (108). Each 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 specification, the first wireless device (100) may represent a communication modem / circuit / chip.

[0052] The second wireless device (200) may include at least one transceiver, such as a transceiver (206), at least one processing chip, such as a processing chip (201), and / or one or more antennas (208).

[0053] The processing chip (201) may include at least one processor, such as a processor (202), and at least one memory, such as a memory (204). Additionally and / or alternatively, the memory (204) may be located external to the processing chip (201).

[0054] The processor (202) may control the memory (204) and / or the transceiver (206) and may be configured to implement the descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed herein. For example, the processor (202) may process information in the memory (204) to generate third information / signal and transmit a wireless signal including the third information / signal via the transceiver (206). The processor (202) may receive a wireless signal including fourth information / signal via the transceiver (206) and store information obtained by processing the fourth information / signal in the memory (204).

[0055] A memory (204) may be operatively connected to the processor (202). The memory (204) may store various types of information and / or instructions. The memory (204) may store firmware and / or software code (205) that implements code, instructions and / or sets of instructions that, when executed by the processor (202), perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed herein. For example, the firmware and / or software code (205) may implement instructions that, when executed by the processor (202), perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed herein. For example, the firmware and / or software code (205) may control the processor (202) to perform one or more protocols. For example, the firmware and / or software code (205) may control the processor (202) to perform one or more air interface protocol layers.

[0056] Here, the processor (202) and memory (204) may be part of a communication modem / circuit / chip designed to implement a RAT (e.g., LTE or NR). A transceiver (206) may be connected to the processor (202) and may transmit and / or receive wireless signals via one or more antennas (208). Each transceiver (206) may include a transmitter and / or a receiver. The transceiver (206) may be used interchangeably with the RF unit. In the present specification, the second wireless device (200) may represent a communication modem / circuit / chip.

[0057] Hereinafter, hardware elements of the wireless device (100, 200) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (102, 202). For example, one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as a physical (PHY) layer, a Media Access Control (MAC) layer, a Radio Link Control (RLC) layer, a Packet Data Convergence Protocol (PDCP) layer, a Radio Resource Control (RRC) layer, and a Service Data Adaptation Protocol (SDAP) layer). One or more processors (102, 202) may generate one or more Protocol Data Units (PDUs), one or more Service Data Units (SDUs), messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed herein. 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 descriptions, functions, procedures, proposals, methods and / or operational flowcharts 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.

[0058] The one or more processors (102, 202) may be referred to as a controller, a microcontroller, a microprocessor, and / or a microcomputer. The one or more processors (102, 202) may be implemented by hardware, firmware, software, and / 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), and / or one or more Field Programmable Gate Arrays (FPGAs) may be included in the one or more processors (102, 202). For example, the one or more processors (102, 202) may be configured by a set of a communication control processor, an Application Processor (AP), an Electronic Control Unit (ECU), a Central Processing Unit (CPU), a Graphic Processing Unit (GPU), and a Memory Control Processor. 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 random access memory (RAM), dynamic RAM (DRAM), read-only memory (ROM), erasable programmable ROM (EPROM), flash memory, volatile memory, nonvolatile memory, hard drive, register, cache memory, computer readable storage media and / or combinations thereof.One or more memories (104, 204) may be located internally and / or externally to one or more processors (102, 202). Additionally, one or more memories (104, 204) may be connected to one or more processors (102, 202) via various technologies, such as wired or wireless connections.

[0059] One or more transceivers (106, 206) can transmit user data, control information, wireless signals / channels, etc., referred to in the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed herein to one or more other devices. One or more transceivers (106, 206) can receive user data, control information, wireless signals / channels, etc., referred to in the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed herein from one or more other devices. For example, one or more transceivers (106, 206) can be coupled 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, wireless signals, etc., 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, wireless signals, etc. from one or more other devices.

[0060] One or more transceivers (106, 206) may be coupled to one or more antennas (108, 208). Additionally and / or alternatively, one or more transceivers (106, 206) may include one or more antennas (108, 208). One or more transceivers (106, 206) may be configured to transmit and receive user data, control information, wireless signals / channels, etc., as described in the descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed herein via one or more antennas (108, 208). In the present disclosure, one or more antennas (108, 208) may be multiple physical antennas or multiple logical antennas (e.g., antenna ports).

[0061] One or more transceivers (106, 206) may 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 processed user data, control information, wireless signals / channels, etc. from baseband signals to RF band signals using one or more processors (102, 202). For this purpose, one or more transceivers (106, 206) may include an (analog) oscillator and / or a filter. For example, one or more transceivers (106, 206) may up-convert an OFDM baseband signal to an OFDM signal via an (analog) oscillator and / or filter under the control of one or more processors (102, 202) and transmit the up-converted OFDM signal at a carrier frequency. One or more transceivers (106, 206) may receive an OFDM signal at a carrier frequency and down-convert the OFDM signal to an OFDM baseband signal via an (analog) oscillator and / or filter under the control of one or more processors (102, 202).

[0062] Although not illustrated in FIG. 2, the wireless device (100, 200) may further include additional components. The additional components (140) may be configured in various ways depending on the type of the wireless device (100, 200). For example, the additional components (140) may include at least one of a power unit / battery, an input / output (I / O) device (e.g., an audio I / O port, a video I / O port), a driving device, and a computing device. The additional components (140) may be connected to one or more processors (102, 202) via various technologies, such as a wired or wireless connection.

[0063] In the implementation of this specification, a UE can operate as a transmitter in the uplink and as a receiver in the downlink. In the implementation of this specification, a base station can operate as a receiver in the UL and as a transmitter in the DL. For the sake of convenience of description, it is mainly assumed below that the first wireless device (100) operates as a UE and the second wireless device (200) operates as a base station. For example, a processor (102) connected to, mounted on, or released in the first wireless device (100) can be configured to perform UE operations according to the implementation of this specification or to control a transceiver (106) to perform UE operations according to the implementation of this specification. A processor (202) connected to, mounted on, or released in the second wireless device (200) can be configured to perform base station operations according to the implementation of this specification or to control a transceiver (206) to perform base station operations according to the implementation of this specification.

[0064] In this specification, a base station may be referred to as a Node B, an eNode B (eNB), or a gNB.

[0065] Figure 3 shows an example of a UE to which the implementation of this specification is applied.

[0066] Referring to FIG. 3, the UE (100) can correspond to the first wireless device (100) of FIG. 2.

[0067] The UE (100) includes a processor (102), memory (104), a transceiver (106), one or more antennas (108), a power management module (141), a battery (142), a display (143), a keypad (144), a SIM (Subscriber Identification Module) card (145), a speaker (146), and a microphone (147).

[0068] The processor (102) may be configured to implement the descriptions, functions, procedures, proposals, methods and / or flowcharts disclosed herein. The processor (102) may be configured to control one or more other components of the UE (100) to implement the descriptions, functions, procedures, proposals, methods and / or flowcharts disclosed herein. A layer of a radio interface protocol may be implemented in the processor (102). The processor (102) may include an ASIC, other chipsets, logic circuits and / or data processing devices. The processor (102) may be an application processor. The processor (102) may include at least one of a DSP, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), and a modem (modulator and demodulator). An example of the processor (102) is the SNAPDRAGON manufactured by Qualcomm®. TM Series processors, EXYNOS made by Samsung® TM Series processors, A-series processors made by Apple®, HELIO made by MediaTek® TM ATOM series processors made by Intel® TM It can be found in the series processors or the corresponding next-generation processors.

[0069] Memory (104) is operatively coupled to the processor (102) and stores various information for operating the processor (102). Memory (104) may include ROM, RAM, flash memory, memory cards, storage media, and / or other storage devices. When the implementation is implemented in software, the techniques described herein may be implemented using modules (e.g., procedures, functions, etc.) that perform the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein. The modules may be stored in memory (104) and executed by the processor (102). Memory (104) may be implemented within the processor (102) or external to the processor (102), in which case it may be communicatively coupled to the processor (102) via various methods known in the art.

[0070] A transceiver (106) is operably coupled to the processor (102) and transmits and / or receives a radio signal. The transceiver (106) includes a transmitter and a receiver. The transceiver (106) may include a baseband circuit for processing a radio frequency signal. The transceiver (106) controls one or more antennas (108) to transmit and / or receive a radio signal.

[0071] The power management module (141) manages the power of the processor (102) and / or the transceiver (106). The battery (142) supplies power to the power management module (141).

[0072] The display (143) outputs the results processed by the processor (102). The keypad (144) receives input to be used by the processor (102). The keypad (144) can be displayed on the display (143).

[0073] A SIM card (145) is an integrated circuit that securely stores an International Mobile Subscriber Identity (IMSI) and associated keys, and is used to identify and authenticate subscribers in mobile devices such as mobile phones and computers. Additionally, many SIM cards can store contact information.

[0074] The speaker (146) outputs sound-related results processed by the processor (102). The microphone (147) receives sound-related input to be used by the processor (102).

[0075] Figure 4 shows an example of a 5G system structure to which the implementation of this specification is applied.

[0076] The 5G system (5GS; 5G system) structure consists of the following network functions (NF; Network Function).

[0077] - AUSF (Authentication Server Function)

[0078] -AMF (Access and Mobility Management Function)

[0079] - DN (Data Network), for example, operator services, Internet access, or third-party services.

[0080] - USDF (Unstructured Data Storage Function)

[0081] - NEF (Network Exposure Function)

[0082] - I-NEF (Intermediate NEF)

[0083] - NRF (Network Repository Function)

[0084] - NSSF (Network Slice Selection Function)

[0085] - PCF (Policy Control Function)

[0086] - SMF (Session Management Function)

[0087] - UDM (Unified Data Management)

[0088] - UDR (Unified Data Repository)

[0089] - UPF (User Plane Function)

[0090] - UCMF (UE radio Capability Management Function)

[0091] - AF (Application Function)

[0092] - UE (User Equipment)

[0093] - (R)AN ((Radio) Access Network)

[0094] - 5G-EIR (5G-Equipment Identity Register)

[0095] - NWDAF (Network Data Analytics Function)

[0096] - CHF (CHarging Function)

[0097] 또한, 다음과 같은 네트워크 기능이 고려될 수 있다.

[0098] - N3IWF (Non-3GPP InterWorking Function)

[0099] - TNGF (Trusted Non-3GPP Gateway Function)

[0100] - W-AGF (Wireline Access Gateway Function)

[0101] Figure 4 illustrates the 5G system architecture for a non-roaming case using a reference point representation showing how various network functions interact with each other.

[0102] For clarity of the point-to-point diagram in Figure 4, UDSF, NEF, and NRF are not illustrated. However, all network functions shown can interact with UDSF, UDR, NEF, and NRF as needed.

[0103] For clarity, the connection between UDR and other NFs (e.g., PCF) is not shown in Fig. 4. For clarity, the connection between NWDAF and other NFs (e.g., PCF) is not shown in Fig. 4.

[0104] The 5G system architecture includes the following benchmarks:

[0105] - N1: Reference point between UE and AMF.

[0106] - N2: Reference point between (R)AN and AMF.

[0107] - N3: Reference point between (R)AN and UPF.

[0108] - N4: Reference point between SMF and UPF.

[0109] - N6: Reference point between UPF and data network.

[0110] - N9: Reference point between two UPFs.

[0111] The following benchmarks illustrate the interactions that exist between NF services in NF.

[0112] - N5: Reference point between PCF and AF.

[0113] - N7: Reference point between SMF and PCF.

[0114] - N8: Reference point between UDM and AMF.

[0115] - N10: Reference point between UDM and SMF.

[0116] - N11: Reference point between AMF and SMF.

[0117] - N12: Reference point between AMF and AUSF.

[0118] - N13: Reference point between UDM and AUSF.

[0119] - N14: Reference point between two AMFs.

[0120] - N15: Reference point between PCF and AMF for non-roaming scenarios, and reference point between PCF and AMF of visited network for roaming scenarios.

[0121] - N16: Reference point between two SMFs (in case of roaming, between the SMF of the visited network and the SMF of the home network)

[0122] - N22: Reference point between AMF and NSSF.

[0123] In some cases, two NFs may need to be interconnected to serve a UE.

[0124] <Random Access Channel (RACH) 절차>

[0125] FIGS. 5A to 5E illustrate examples of RACH procedures applicable to one embodiment of the present disclosure.

[0126] Referring to FIGS. 5A to 5E, a RACH procedure according to an embodiment of the present disclosure is described. The embodiments of FIGS. 5A to 5E may be combined with various embodiments of the present disclosure.

[0127] In one embodiment of the present disclosure, when RF requirements (e.g., Tx RF performance requirements and / or Rx RF performance requirements) are described, the UE can satisfy these RF requirements. For example, the UE can be tested to satisfy the RF requirements (e.g., Tx RF performance requirements and / or Rx RF performance requirements) according to one embodiment of the present disclosure. In one embodiment of the present disclosure, a UE that satisfies these RF requirements can perform a RACH procedure. When the UE transmits a message, data, signaling, etc. to the gNB, the UE satisfies the Tx RF performance requirements described in the first embodiment of the present specification. When the UE receives a message, data, signaling, etc. from the gNB, the UE satisfies the Rx RF performance requirement described in the first embodiment of the present specification.

[0128] To connect a UE to a 5G network, the UE and the 5G network must be synchronized in both uplink and downlink. Downlink synchronization occurs when the UE successfully decodes the SSB transmitted by the gNB. To establish uplink synchronization and RRC connection, the UE must perform a RACH random access procedure.

[0129] Two types of random access procedures are supported: a four-step Random Access (RA) type using MSG1 and a two-step RA type using MSGA.

[0130] Two types of RA procedures can support Contention Based Random Access (CBRA) and Contention Free Random Access (CFRA), as shown in Figures 5a to 5e below, respectively. The UE can select the random access type when initiating a random access procedure depending on network settings.

[0131] Referring to FIGS. 5a and 5c, a four-step RA type using MSG1 is described.

[0132] MSG1 of the 4-step RA type includes a preamble of the PRACH. The UE transmits MSG1. After transmitting MSG1, the UE monitors the network for a response within a set period of time.

[0133] For the CBRA example of FIG. 5a, when the UE receives a random access response (MSG2) from the gNB, the UE can transmit MSG3 using the UL grant scheduled by the response message. The UE can then monitor contention resolution. If contention resolution is not successful after (re)transmitting MSG3, the UE performs MSG1 transmission again.

[0134] For the CFRA example in Figure 5c, a dedicated preamble for MSG1 transmission is allocated by the network. The gNB transmits the RA preamble allocation to the UE. The UE transmits MSG1, which includes a random access preamble, to the gNB. Upon receiving a random access response from the network, the UE terminates the random access procedure.

[0135] Referring to Figures 5b, 5d, and 5e, a two-step RA type is described. The MSGA of the two-step RA type includes a random access preamble of the PRACH and a PUSCH payload. After the UE transmits the MSGA, the UE monitors the network's response within a configured window.

[0136] For CBRA according to the example of Fig. 5b, if the UE successfully resolves the contention after receiving a network response (e.g., MSGB), the UE terminates the random access procedure. If a fallback indication is received within the MSGB, the UE performs MSG3 transmission using the UL grant reserved in the fallback indication, as shown in Fig. 5e, and monitors contention resolution. If the contention resolution is not successful after the MSG3 (re)transmission, the UE performs MSGA transmission again.

[0137] For CFRA according to the example of FIG. 5d, the UE can receive an RA preamble allocation and a PUSCH allocation from the gNB. Then, dedicated preamble and PUSCH resources can be configured for MSGA transmission. The UE transmits the MSGA. When the UE receives a network response, the UE terminates the random access procedure.

[0138] If the random access procedure of type 2 RA is not completed after several MSGA transmissions, the UE may be configured to transition to CBRA of type 4 RA.

[0139] Additional measures to support ProSe (Proximity-based Services) are being discussed (e.g., Study on System Enhancement for Proximity-based Services in 5GS - Phase 3 (FS_5G_ProSe_Ph3) - SP-231798). Examples of objectives discussed in relation to Proximity-based Services include:

[0140] The purpose of this work item is to define 5G system enhancements to support multi-hop UE-to-Network relay and UE-to-UE relay services, following the conclusions drawn from TR 23.700-03.

[0141] The specific objectives are as follows:

[0142] - WT#1: Improves ProSe to support multi-hop UE-to-Network relay.

[0143] - WT#2: Enhances ProSe to support layer 3 multi-hop UE-UE relay for IP PDU types based on the IETF MANET protocol.

[0144] - WT#3: Enhances ProSe to support Layer 3 multi-hop UE-UE relay for Ethernet PDU types and unstructured PDU types, based on Release 18 PC5 protocol.

[0145] UE-to-Network relay can include both Layer-3 and Layer-2 relay.

[0146] Additional work items have been discussed to support ProSe (Proximity-based Services) via multi-hop in 5GS. For example, the objectives of New WID on NR sidelink multi-hop relay (NR_SL_relay_enh2) - RP-241609 are as follows:

[0147] The aim is to specify the solution required to support multi-hop layer 2 UE-network relay for a single indirect path via SL relay UE, based on conventional relay functionality (e.g. Rel-17 / 18 SL relay functionality).

[0148] 1. Develop a mechanism to support up to two additional hop relays for a Rel-17 U2N relay. This work can begin with a single additional hop relay (e.g., remote UE -> first relay UE -> last relay UE -> gNB). Further verification can be conducted to ensure ease of expansion to two additional hop relays (e.g., remote UE -> first relay UE -> second relay UE -> last relay UE -> gNB). The essential criteria for a given mechanism are that it can easily expand to two additional hop relays and be forward compatible with future relay expansions. The following examples can be considered:

[0149] A. Relay search and (re)selection

[0150] B. Signaling support for relay UE and remote UE authentication when SA2 determines it is necessary.

[0151] C. Impact on SRAP and QoS Handling for Multi-Hop

[0152] D. Control Plane Procedures

[0153] The following service continuity scenarios within the Next Generation NodeB (gNB) for multi-hop U2N relay can be considered (for remote UEs):

[0154] Top priority:

[0155] A. Multi-hop indirect to direct path switching within gNB using existing frameworks

[0156] B. Switching from multi-hop indirect to single-hop indirect path within gNB using existing framework

[0157] Second priority in order of importance:

[0158] C. Path transition from a direct path to a multi-hop indirect path within a gNB.

[0159] D. Path transition from single-hop indirect to multi-hop indirect path within gNB

[0160] Scenarios C and D may imply that the path is switched to a target indirect path consisting of the last relay UE in "direct" RRC connection mode and all other intermediate relays in the same cell in "indirect" RRC connection mode.

[0161] U2N (UE-to-Network) relay, where a remote UE (User Equipment) connects to a base station via a relay UE, has been introduced. However, previous discussions focused only on single-hop scenarios, where a remote UE connects to a single relay UE. The problem is that there is no effective solution for multi-hop scenarios, where a remote UE connects to multiple relay UEs.

[0162] For example, in the 3GPP standard Rel-17, a standard specification for U2N Relay was developed, in which a Remote UE receives services from a base station by connecting to the base station through a Relay UE. In the 3GPP standard Rel-18, a standard specification for Multi-path Relay, in which a Remote UE receives services from the network through a direct path using a Uu link with a base station and an indirect path using a PC5 link with a Relay UE, was discussed. In addition, a standard specification for U2U Relay, in which a Remote UE connects to another Remote UE through a Relay UE, was discussed. However, because the relay-related standard work conducted in Rel-17 and Rel-18 was conducted only for a single-hop situation, there is a problem that there is a limitation in the coverage extension of the Remote UE.

[0163] To solve this, technologies to support a multi-hop relay situation in which n relays can participate have been discussed through standards work called 5G_ProSe_Ph3 (System Enhancement for Proximity-based Services in 5GS -Phase 3 - S2-2407371) and NR_SL_relay_multihop (NR sidelink multi-hop relay - RP-250188) in Rel-19. One of the objectives related to the multi-hop relay situation is to develop a control plane procedure to support multi-hop relay operation. However, according to the prior art, there is a problem that the control plane procedure to support multi-hop relay operation is not discussed at all.

[0164] For example, in a situation where the base station is divided into a gNB-Central Unit (CU) and a gNB-Distributed Unit (DU), a method to support multi-hop UE-to-Network relaying is needed.

[0165] In some implementations, for signaling and data transmission between the U2N Remote UE and the base station, the gNB-CU may transmit information related to the multi-hop U2N Relay operation to the gNB-DU.

[0166] In some implementations, for routing using SRAP header, the gNB-Central Unit (CU) and / or gNB-Distributed Unit (DU) may allocate and / or configure mapping / routing information to egress PC5 / Uu Relay RLC channel for specific U2N Remote UEs on a per-peer UE or per-DL / UL basis to each U2N Relay UE.

[0167] In the disclosure of this specification, UE (User Equipment) and terminal may be used as terms having the same meaning.

[0168] In the disclosure of this specification, terms such as UE-to-Network Relay, ProSe UE-to-Network Relay, Relay, Relay UE, UE-NW Relay, 5G ProSe UE-to-Network Relay, 5G ProSe UE-to-NW Relay, 5G ProSe UE-to-Network Relay UE, U2N Relay, U2N Relay UE, etc. may be used as terms having the same meaning.

[0169] In the disclosure of this specification, Remote UE, 5G Remote UE, 5G ProSe Remote UE, U2N Remote UE, etc. may be used as terms with the same meaning.

[0170] In the disclosure of this specification, a UE that is not a UE-to-Network Relay may also be referred to as a Remote UE or UE.

[0171] In the disclosure of this specification, in order to provide network connection services to Remote UEs, a U2N Relay directly connected to the Remote UE and the base station may exist. A U2N Relay located on the path between the Remote UE and the U2N Relay directly connected to the base station may be referred to as an Intermediate U2N Relay.

[0172] The description related to U2N (UE-to-Network) Relay in this specification may be a description related to Layer-2 U2N Relay. However, this is only an example, and the description related to U2N (UE-to-Network) Relay may be applied to all types of UE-to-Network Relay (e.g., Layer-2 UE-to-Network Relay, Layer-3 UE-to-Network Relay).

[0173] In this specification, the description related to U2N Relay and the description related to the section between U2N Remote UE and U2N Relay located at the last hop (i.e. U2N Relay directly connected to the base station) can also be applied to multi-hop UE-to-UE relay operation.

[0174] In this specification, descriptions related to prior art are omitted, and the contents proposed in this specification are mainly described. For ProSe-related operations and procedures, reference may be made to TS 23.304 V18.4.0, TS 24.554 V18.4.0, TS 33.536 V18.0.0, TS 33.503 V18.2.0, TS 38.300 V18.1.0, TS 38.401 V18.1.0, TS 38.331 V18.1.0, TS 38.351 V18.1.0, etc.

[0175] The method for supporting multi-hop UE-to-network relaying proposed in this disclosure may be composed of a combination of one or more of the following operations / configurations / steps.

[0176] For some or all of the NG messages between the AMF and the NG-RAN described in the disclosure of this specification, new NG messages may be defined and used. In addition, new RRC messages may be defined and used for some or all of the RRC messages between the NG-RAN and the UE described below.

[0177] In the procedures described in the disclosure of this specification, certain steps may be performed concurrently / in parallel or may be performed in an alternate order.

[0178] In the disclosure of this specification, the names of indications and / or parameter information are examples for explanation. The names of indications and / or parameter information may be interpreted as being replaced with other names for the relevant procedures / purposes / methods.

[0179] 1. First example of disclosure of this specification

[0180] A first example of the disclosure of this specification describes an example of initial access of a U2N remote UE using multi-hop U2N relay operation.

[0181] In the various examples below, the description or operation for U2N Relay UE#3 (e.g., 3-hop U2N Relay UE) may also be applied to 2-hop U2N Relay UEs or more hops of U2N Relay UEs (e.g., intermediate UE-to-Network Relay UEs).

[0182] In this specification, a UE can perform a relay role (an Intermediate U2N Relay role or a U2N Relay role that is directly connected to a base station as Uu) to enable a U2N Remote UE to receive network connection services. In addition, the UE can also communicate with a network through another U2N Relay (e.g., can perform a U2N Remote UE role) to receive connection services to the network (e.g., to transmit and receive its own traffic through the network). In particular, the UE can perform both the Intermediate U2N Relay role and the U2N Remote UE role simultaneously. This can be applied throughout this specification.

[0183] For reference, in FIGS. 6A to 6C and 7A to 7C, U2N Relay UE#2 can act as an Intermediate U2N Relay to enable U2N Remote UE to receive network connection services. In addition, U2N Relay UE#2 can communicate with the network via U2N Relay UE#1 to receive network connection services.

[0184] Below, a first example of the procedure is described with reference to examples of FIGS. 6a to 6c.

[0185] The following drawings are intended to illustrate specific examples of the present specification. The names of specific devices and the names of specific signals, messages, and fields depicted in the drawings are provided for illustrative purposes only, and the technical features of this specification are not limited to the specific names used in the drawings.

[0186] FIGS. 6A to 6C are first examples of procedures related to initial connection of a remote UE according to one embodiment of the disclosure of the present specification.

[0187] Figures 6a to 6c are examples of procedures related to initial connection of a U2N remote UE via multi-hop U2N relay operation.

[0188] Additionally, the U2N Remote UE can act as an Intermediate U2N relay to enable the New U2N Remote UE to receive network connection services. Furthermore, the U2N Remote UE itself can communicate with the network via U2N Relay UE#1 and U2N Relay UE#2 to receive network connection services.

[0189] Step 1: A U2N Remote UE can discover a U2N Relay UE that can provide connectivity to the network.

[0190] Although it is assumed in FIGS. 6a to 6c that the U2N Remote UE is connected to the base station via U2N Relay UE#1 and U2N Relay UE#2, this is merely an example. The description in FIGS. 6a to 6c can also be applied to a situation where the U2N Remote UE is connected to the network via n U2N Relay UEs (i.e., n-hop).

[0191] In this process, Relay UE#2 can transmit information related to Relay UE#1 to U2N Remote UE. In addition, Relay UE#2 can also transmit information related to Relay UE#2 to U2N Remote UE. For example, Relay UE#2 can transmit serving cell information of U2N Relay UE to be used / referenced for (re)selecting U2N Relay UE and information for accessing the corresponding cell to U2N Remote UE. In the above, it refers to serving cell information of U2N Relay UE#1, and serving cell information of U2N Relay UE#2 can also be transmitted to U2N Remote UE.

[0192] For existing input parameters used / transmitted during the discovery process, TS 23.304 V18.5.0 may be referenced. Additionally, some or all of the following information may be exchanged / transmitted to the U2N Remote UE during the discovery process:

[0193] - Number of hops (n): The number of U2N Relay UEs required for the U2N Remote UE to connect to the network; and / or

[0194] - Information about each node involved in the network connection (e.g., User Info ID) and L2 ID of each node (e.g., L2 IDs for U2N Remote UE, U2N Relay UE#1, U2N Relay UE#2)

[0195] Step 2: U2N Remote UE can first create a new PC5 connection with U2N Relay UE#2 or change / update an existing PC5 connection to connect to the network.

[0196] In Figures 6a to 6c, it is assumed that a U2N Remote UE transmits a Direct Communication Request message to U2N Relay UE#2 to create a new PC5 connection. Similarly, U2N Relay UE#2 can sequentially transmit a Direct Communication Request message to U2N Relay UE#1.

[0197] For example, in step 2a, the U2N Remote UE may send a Direct Communication Request message to the U2N Relay UE#2. In step 2b, the U2N Relay UE#2 may send a Direct Communication Request message (including support information for the U2N Relay UE#2) to the U2N Relay UE#1. In step 2c, the U2N Relay UE#1 may send a Direct Communication Accept message to the U2N Relay UE#2. In step 2d, the U2N Relay UE#2 may send a Direct Communication Accept message to the U2N Remote UE.

[0198] At this time, when the U2N Relay UE#2 accesses the base station as a Remote UE, there may be a UE context for the U2N Relay UE#2 that the base station (e.g., gNB-CU and / or gNB-DU) allocated / configured and stored. In addition, there may be a UE context when the U2N Relay UE#2 accesses the base station as an Intermediate U2N Relay UE for multi-hop U2N operation. In order for the base station to identify these two UE contexts as UE contexts for the same UE (e.g., U2N Relay UE#2) (e.g., when the same UE accesses the base station as a Remote UE and when the same UE accesses the base station as an Intermediate U2N Relay UE, so that the base station does not recognize the same UE as different UEs), a Direct Communication Request message including Assistance information for U2N Relay UE#2 may be transmitted to the U2N relay UE#1. For example, Assistance information for U2N Relay UE#2 may include some or all of the following information:

[0199] - Local ID assigned / set by the base station when U2N Relay UE#2 connects to the base station as a Remote UE

[0200] - C-RNTI assigned / set by the base station when U2N Relay UE#2 connects to the base station as a Remote UE

[0201] - L2 ID used or to be used when U2N Relay UE#2 connects to the base station as a Remote UE; and / or

[0202] - L2 ID to be used when U2N Relay UE#2 connects to the base station as an Intermediate U2N Relay UE (i.e. L2 ID for U2N Relay UE#2)

[0203] If U2N Relay UE#1, which has received the Direct Communication Request message, accepts the creation or change / update of the PC5 connection with U2N Relay UE#2, U2N Relay UE#1 responds with a Direct Communication Accept message (e.g., step 2c). Similarly, U2N Relay UE#2 can sequentially transmit Direct Communication Accept messages to U2N Remote UEs (e.g., step 2d).

[0204] Unlike the above, a unicast link may be formed between U2N Remote UEs and U2N Relays in various ways. For example, a unicast link may be formed hop-by-hop (i.e., a U2N Remote UE and U2N Relay UE#2 form a unicast link, and a U2N Relay UE#2 and U2N Relay UE#1 form a unicast link), and an end-to-end unicast link may be formed between a U2N Remote UE and a U2N Relay UE#1. This can be applied throughout this specification.

[0205] For existing input parameters included in the Direct Communication Request message and / or Direct Communication Accept message, TS 23.304 V18.5.0 may be referenced.

[0206] Step 3: The U2N Remote UE can attempt to create an RRC connection by sending an RRCSetupRequest message to the base station via U2N Relay #2.

[0207] Additionally, the previously defined PC5 Relay RLC channel configuration (e.g., SL-RLC0) may be used for transmitting / receiving SRB0 messages (e.g., RRCSetupRequest, RRCSetup, etc.) of U2N Remote UEs. Alternatively, a separate PC5 Relay RLC channel configuration for multi-hop U2N relay operation may be newly defined.

[0208] Step 4: If U2N Relay UE#2 is in RRC_IDLE or RRC_INACTIVE state, U2N Relay UE#2 may perform state transition to RRC_CONNECTED.

[0209] For example, after U2N Relay UE#2 receives the RRCSetupRequest message of U2N Remote UE, it can transition to RRC_CONNECTED state using the procedure of Figure 8.19.1-1 or Figure 8.19.3-1 of TS 38.401 V18.1.0.

[0210] In this process, the base station can allocate a local ID to the U2N Relay UE#2 that has accessed the network as a U2N Remote UE. In addition, the base station can allocate / configure information related to mapping / routing SRBs and DRBs related to the local ID for U2N Relay UE#2 to a specific egress PC5 / Uu Relay RLC channel to the U2N Relay UE#2 and U2N Relay UE#1. In this process, the U2N Relay UE#1 can also directly inform the base station of an L2 ID (e.g., L2 ID for U2N Relay UE#1 in multi-hop U2N relay operation) to be used when participating as a U2N Relay UE (e.g., Intermediate U2N Relay UE or Last U2N Relay UE) in a multi-hop U2N relay operation.

[0211] Prior to Step 4, U2N Relay UE#2 may have already transitioned to RRC_CONNECTED state using the procedure in Figure 8.19.1-1 or Figure 8.19.3-1 of TS 38.401 V18.1.0.

[0212] The U2N Relay UE#2 may not include the Assistance information for U2N Relay UE#2 in the Direct Communication Request message in Step 2. For example, the U2N Relay UE#2 may transmit a SidelinkUEInformationNR message to the base station as in Step 4a immediately after transitioning to the RRC_CONNECTED state. In this case, the U2N Relay UE#2 may also transmit the SidelinkUEInformationNR message to the base station including the L2 ID (i.e., L2 ID for U2N Relay UE#2) to be used when the U2N Relay UE#2 participates as the Intermediate U2N Relay UE (or Last U2N Relay UE) in the multi-hop U2N relay operation. The base station (e.g., gNB-CU) may combine the above information (e.g., L2 ID for U2N Relay UE#2) with the information about the entire path transmitted by the U2N Relay UE#1 in Step 6. Based on this, the base station (e.g., gNB-CU) can know that U2N Relay UE#2 participated as an Intermediate U2N Relay UE in the connection to the network of the U2N Remote UE. The base station (e.g., gNB-CU) can derive the gNB-DU UE F1AP ID and the gNB-CU UE F1AP ID that identify the UE context for U2N Relay UE#2 within the gNB-CU and gNB-DU.

[0213] For reference, in the disclosure of this specification, the sidelinkUEinformationNR message may also be referred to as a UE information message. The name sidelinkUEinformationNR is merely an example, and the sidelinkUEinformationNR message may relate to a message that a UE transmits containing information related to a U2N relay.

[0214] Alternatively, the gNB already knows that U2N Relay UE#2 is accessing via U2N Relay UE#1. U2N Relay UE#2 can inform the gNB of its L2 ID (i.e., L2 ID for U2N Relay UE#2 in multi-hop U2N relay operation) to use when participating as a U2N Relay UE (i.e., Intermediate U2N Relay UE or Last U2N Relay UE) in a multi-hop U2N relay operation. In this case, the gNB may know that the entire path of a U2N Remote UE accessing the gNB via U2N Relay UE#2 is formed as U2N Remote UE->U2N Relay UE#2 -> U2N Relay UE#1->gNB.

[0215] NOTE: A U2N Relay UE#2 in RRC_IDLE or RRC_INACTIVE state may select U2N Relay UE#1 as the Serving Relay of U2N Relay UE#2 by referring to the entire path selected in Step 1, without performing a separate Relay discovery process to (re)select U2N Relay UE(s) that can provide connectivity to the network.

[0216] Step 5: U2N Relay UE#2 can forward the RRCSetupRequest message received in Step 3 to U2N Relay UE#1 (via the specified PC5 Relay RLC channel configuration).

[0217] Step 6: Upon receiving the RRCSetupRequest message from the U2N Relay UE#2, the U2N Relay UE#1 can transmit a SidelinkUEInformationNR message to the base station (e.g., gNB-CU via gNB-DU). By transmitting the SidelinkUEInformationNR message to the base station (e.g., gNB-CU via gNB-DU), the U2N Relay UE#1 can request the setup / creation of a Uu Relay RLC channel for transmitting RRC messages.

[0218] During this process, U2N Relay UE#1 can also transmit the L2 ID of each node involved in the network connection (Path) for U2N Remote UE (e.g., L2 ID for U2N Remote UE, L2 ID for U2N Relay UE#1, and / or L2 ID for U2N Relay UE#2). Alternatively, the gNB-CU can generate information about the entire path itself. For example, in the process of the U2N Relay UE (e.g., U2N Relay UE#2) located at the first hop transitioning to the RRC_CONNECTED state in Step 4, the gNB-CU may generate information about the entire path by combining the L2 ID of each node involved in the network connection (Path) for the U2N Relay UE (i.e., U2N Relay UE#2) located at the first hop (e.g., L2 ID for U2N Relay UE#1 in FIGS. 6a to 6c) with the L2 ID for U2N Relay UE#2 received in Step 4a and the L2 ID for U2N Remote UE.

[0219] Additionally, U2N Relay UE#1 may have received Assistance information for U2N Relay UE#2 in Step 2. In this case, U2N Relay UE#1 may transmit a SidelinkUEInformationNR message including Assistance information for U2N Relay UE#2 to the base station. Based on the information included in the SidelinkUEInformationNR message, the gNB-CU may know that U2N Relay UE#2 has participated in the path as an Intermediate U2N Relay UE. Additionally, the gNB-CU may derive the gNB-DU UE F1AP ID and the gNB-CU UE F1AP ID, which identify the UE context for U2N Relay UE#2 within the gNB-CU and the gNB-DU.

[0220] A gNB-CU receiving a SidelinkUEInformationNR message may allocate and / or configure a local ID for the U2N Remote UE. As in the UE-to-Network Relay operation in TS 38.351 V18.1.0, the gNB-CU may route data and / or signaling of the U2N Remote UE through the local ID allocated / configured in Step 6 across all sections between the U2N Remote UE and the base station. For this purpose, the gNB-CU may use the Local ID value defined in TS 38.331 V18.1.0 (e.g., INTEGER (0..255)). Alternatively, a separate Local ID may be defined for the Multi-hop U2N Relay operation to distinguish it from the existing Single-hop U2N Relay operation. Alternatively, the base station may separately set / allocate i) a Local ID for DL ​​to be used for routing DL data and / or signaling transmitted to the U2N Remote UE and ii) a Local ID for UL to be used for routing UL data and / or signaling transmitted by the U2N Remote UE to the base station.

[0221] Step 7: The gNB-CU may send a UE context modification request message to the gNB-DU.

[0222] For example, the gNB-CU can forward the SidelinkUEInformationNR message received in Step 6 to the gNB-DU via the F1AP UE CONTEXT MODIFICATION REQUEST message of the U2N Relay UE#1.

[0223] Additionally, the gNB-CU can request the gNB-DU to allocate / set the Uu Relay RLC channel configuration required to transmit the SRB0 / 1 message to the U2N Remote UE. The gNB-DU can allocate / set the Uu Relay RLC channel configuration and respond to the gNB-CU via an F1AP UE CONTEXT MODIFICATION RESPONSE message.

[0224] The gNB-CU may send the Local ID for U2N Remote UE to the gNB-DU while requesting the gNB-DU to allocate / set the Uu Relay RLC channel configuration required to transmit the SRB0 / 1 message for the U2N Remote UE. Based on the Local ID for U2N Remote UE and the Uu Relay RLC channel configuration allocation / configuration information in Step 11, the gNB-DU may know that the U2N Remote UE is accessing the gNB-DU via U2N Relay UE#2 and U2N Relay UE#1. If the Local ID for the U2N Remote UE is allocated / set differently for DL / UL in Step 6, a Uu Relay RLC channel configuration may be allocated / generated for each Local ID.

[0225] Additionally, the gNB-CU may request the gNB-DU to allocate / configure the PC5 Relay RLC channel configuration between U2N Relay UE#2 and U2N Relay UE#1, which is required to transmit the SRB0 / 1 message for the U2N Remote UE, via the F1AP UE CONTEXT MODIFICATION REQUEST message. In this case, the gNB-CU may also transmit the Local ID for U2N Remote UE to the gNB-DU to indicate that the PC5 Relay RLC channel is for the U2N Remote UE. Furthermore, the gNB-CU may also transmit the Peer UE Information for U2N Relay UE#2 to the gNB-DU to indicate that the PC5 Relay RLC channel is created / allocated from U2N Relay UE#1 to U2N Relay UE#2. For example, the Peer UE Information information may include one or more of the following information:

[0226] - gNB-CU UE F1AP ID allocated / configured by gNB-CU for U2N Relay UE#2;

[0227] - gNB-DU UE F1AP ID allocated / configured by gNB-DU for U2N Relay UE#2;

[0228] - L2 ID for U2N Relay UE#2; and / or

[0229] - Local ID for U2N Relay UE#2.

[0230] The gNB-CU may have obtained the following information in Step 6 via the F1AP UE CONTEXT MODIFICATION REQUEST message from the U2N Relay UE#1. For example, the gNB-CU may have obtained the L2 ID (i.e., L2 IDs for U2N Remote UE, U2N Relay UE#1, and U2N Relay UE#2) or UE F1AP IDs (i.e., gNB-CU / gNB-DU UE F1AP IDs for U2N Remote UE, U2N Relay UE#1, and U2N Relay UE#2) of each node involved in the network connection (Path) for the U2N Remote UE. In this case, the gNB-CU may also forward these L2 IDs or UE F1AP IDs to the gNB-DU. This information may also be provided to the gNB-DU via Step 13a, 14a, or 16, etc. instead of Step 7.

[0231] NOTE: The PC5 Relay RLC channel for the U2N Remote UE may be allocated / configured differently for DL / UL. Alternatively, if the Local ID for the U2N Remote UE is allocated / configured differently for DL / UL in Step 6, a PC5 Relay RLC channel configuration may be allocated / created for each Local ID.

[0232] Step 8: The gNB-CU may send an RRCReconfiguration message to the U2N Relay UE#1 containing one or more of the following information so that the gNB-CU can route the SRB0 / 1 message of the U2N Remote UE:

[0233] A. Local ID for U2N Remote UE allocated / set in Step 6 to distinguish / identify U2N Remote UE in Uu link or Uu Relay RLC channel between U2N Relay UE#1 and base station;

[0234] B. Uu Relay RLC channel configuration required for transmitting the SRB0 / 1 message for the U2N Remote UE received by the gNB-CU from the gNB-DU in Step 7;

[0235] C. PC5 Relay RLC channel configuration between U2N Relay UE#2 and U2N Relay UE#1 for transmitting the SRB0 / 1 message for the U2N Remote UE received by the gNB-CU from the gNB-DU in Step 7; and / or

[0236] D. SRAP information for mapping / routing each SRAP Data PDU belonging to SRB0 / 1 to a specific egress PC5 / Uu Relay RLC channel. Or, SRAP information for mapping / routing SRAP Data PDUs transmitted through a specific ingress PC5 / Uu Relay RLC channel for SRB0 / 1 to a specific egress Uu / PC5 Relay RLC channel. The information may be allocated / configured for each Local ID for U2N Remote UE, or for each pair of Local ID for U2N Remote UE and Peer UE Information for U2N Relay UE#2. If the PC5 Relay RLC channel for U2N Remote UE is allocated / configured differently for DL / UL, the gNB-CU may also transmit information related to whether the SRAP information is for DL ​​transmission or UL transmission to U2N Relay UE#1.

[0237] Step 9: U2N Relay UE#1 can send the RRCReconfigurationComplete message to the gNB-CU via the gNB-DU.

[0238] For example, U2N Relay UE#1 may complete allocation / configuration of egress PC5 / Uu Relay RLC channel configuration for transmitting Bearer and / or SRB0 / 1 message of U2N Remote UE to be used in RRC connection with base station based on RRCReconfiguration message received in Step 8. Thereafter, U2N Relay UE#1 may transmit RRCReconfigurationComplete message to gNB-CU via gNB-DU to notify that egress PC5 / Uu Relay RLC channel configuration has been allocated / configured.

[0239] Step 10: U2N Relay UE#1 can send an RRCSetupRequest message to gNB-DU.

[0240] For example, U2N Relay UE#1 can transmit the RRCSetupRequest message received in Step 5 to gNB-DU through the configuration allocated / set in Step 8. At this time, based on the information received in Step 8 (e.g., Local ID for U2N Remote UE, BEARER ID for SRB0, etc.), U2N Relay UE#1 can configure an SRAP header and transmit the SRAP header to gNB-DU, as in the UE-to-Network Relay operation in TS 38.351 V18.1.0. At this time, in order for gNB-DU to distinguish between the existing Single-hop U2N Relay operation and the Multi-hop U2N Relay operation, U2N Relay UE#1 can perform the following operations. For example, U2N Relay UE#1 may explicitly include an indication in the SRAP header indicating that it is a multi-hop U2N Relay operation and / or the number of U2N Relay UEs required for the U2N Remote UE to connect to the network (i.e., Number of hops (n)). Alternatively, U2N Relay UE#1 may implicitly inform the gNB-DU of a separate Local ID for the multi-hop U2N Relay operation defined in Step 6 by including it in the RRCSetupRequest message.

[0241] Step 11: gNB-DU can send INITIAL UL RRC MESSAGE TRANSFER to gNB-CU.

[0242] For example, the gNB-DU can determine that the U2N Remote UE is accessing the gNB-DU for the first time based on the BEARER ID (e.g., SRB0) in the SRAP header received in Step 10. In addition, based on information such as the Uu Relay RLC channel through which the RRCSetupRequest message was transmitted, the gNB-DU can determine that the U2N Remote UE is accessing via U2N Relay UE#1. In addition, based on additional information included in the SRAP header (e.g., indication indicating a multi-hop U2N Relay operation and / or Number of hops (n), Local ID for U2N Remote UE, etc.), the gNB-DU can determine that an Intermediate U2N Relay UE(s) currently exists between the U2N Remote UE and U2N Relay UE#1. Alternatively, by comparing the information such as the Uu Relay RLC channel to which the RRCSetupRequest message was transmitted and the Local ID information included in the SRAP header with the Local ID for U2N Remote UE and / or Uu Relay RLC channel allocation / creation request information received from the gNB-CU in Step 7, the gNB-DU may know that the U2N Remote UE is accessing the gNB-DU via U2N Relay UE#2 and U2N Relay UE#1.

[0243] The gNB-DU may determine that it can service the above U2N Remote UE. In this case, the gNB-DU may allocate / create a lower layer configuration for the PC5 Relay RLC channel between the U2N Remote UE and the Intermediate U2N Relay UE, rather than between the U2N Remote UE and the U2N Relay UE#1. The gNB-DU may transmit the lower layer configuration for the PC5 Relay RLC channel between the U2N Remote UE and the Intermediate U2N Relay UE to the gNB-CU via the F1AP INITIAL UL RRC MESSAGE TRANSFER message. In addition, the lower layer configuration information for the PC5 Relay RLC channel thus allocated / created may be stored and / or kept in the U2N Remote UE's context within the gNB-DU. Additionally, the gNB-DU may send the gNB-DU UE F1AP ID for U2N Relay UE#1 and the Local ID for U2N Remote UE included in the SRAP header received in Step 10 to the gNB-CU via the INITIAL UL RRC MESSAGE TRANSFER message. If, based on the information in Step 4, Step 7, and / or Step 11, the gNB-DU may determine that the entire path of the U2N Remote UE is formed as U2N Remote UE→U2N Relay UE#2→U2N Relay UE#1→gNB, the gNB-DU may also send the INITIAL RRC MESSAGE TRANSFER to the gNB-CU, including the gNB-DU UE F1AP ID for the U2N Relay UE located in the first hop (i.e., U2N Relay UE#2).

[0244] Based on the SidelinkUEInformationNR message received in Step 4 and / or Step 6 and the F1AP INITIAL UL RRC MESSAGE TRANSFER message received in Step 11, the gNB-CU can know that the U2N Remote UE is connected to the base station via U2N Relay UE#2 and U2N Relay UE#1. The gNB-CU can derive the gNB-DU UE F1AP ID and the gNB-CU UE F1AP ID, which identify the UE context for U2N Relay UE#2 and U2N Relay UE#1 within the gNB-CU and gNB-DU, respectively, as follows:

[0245] - gNB-DU UE F1AP ID and gNB-CU UE F1AP ID for U2N Relay UE#1

[0246] - gNB-DU UE F1AP ID and gNB-CU UE F1AP ID for U2N Relay UE#2

[0247] Step 12: The gNB-CU can send a DL RRC MESSAGE TRANSFER message to the gNB-DU.

[0248] For example, the gNB-CU may decide to establish an RRC connection with a U2N Remote UE. In this case, the gNB-CU may generate an RRCSetup message and send an F1AP DL RRC MESSAGE TRANSFER message containing the RRCSetup message to the gNB-DU.

[0249] The gNB-DU can configure the SRAP header by referring to the SRB Mapping InfoIE included in the F1AP DL RRC MESSAGE TRANSFER message. The gNB-DU can forward the RRCSetup message to the U2N Remote UE via U2N Relay UE#1 and U2N Relay UE#2.

[0250] The gNB-CU can include SRAP information mapping each SRB and DRB to be used by the U2N Remote UE to a specific egress PC5 Relay RLC channel in the RRCSetup message during the PC5 connection between the U2N Remote UE and the U2N Relay UE#2 (e.g., the first PC5 connection). In addition, to inform the U2N Remote UE that the PC5 Relay RLC channel is to the U2N Relay UE#2, the gNB-CU can also include L2 ID for U2N Relay UE#2 information in the SRAP configuration and transmit it to the U2N Remote UE.

[0251] Step 13: In Steps 7~9, the PC5 / Uu Relay RLC channel for transmitting the SRB1 message of the U2N Remote UE may not be allocated / configured to the U2N Relay UE#1. In this case, in Step 13a, the gNB-CU may request the gNB-DU to allocate / configure the PC5 Relay RLC channel configuration for the PC5 connection between the U2N Relay UE#1 and the U2N Relay UE#2 and / or the Uu Relay RLC channel configuration between the U2N Relay UE#1 and the gNB-DU for transmitting the SRB1 message through the F1AP UE Context Modification procedure. At this time, in order to inform the U2N Relay UE#1 that the PC5 Relay RLC channel is created / allocated from the U2N Relay UE#1 to the U2N Relay UE#2, the U2N Relay UE#1 may also transmit Peer UE Information for the U2N Relay UE#2. Peer UE Information for Relay UE#2 may include some or all of the following information:

[0252] - gNB-CU UE F1AP ID allocated / configured by gNB-CU for U2N Relay UE#2;

[0253] - gNB-DU UE F1AP ID allocated / configured by gNB-DU for U2N Relay UE#2;

[0254] - L2 ID for U2N Relay UE#2; and / or

[0255] - Local ID for U2N Relay UE#2.

[0256] In order to forward the PC5 / Uu Relay RLC channel configuration received from the gNB-DU in Step 13a to the U2N Relay UE#1, the gNB-CU may execute the RRC Reconfiguration process as in Step 13b. In addition, the gNB-CU may allocate / configure SRAP information, information for mapping / routing each SRAP Data PDU belonging to SRB1 to a specific egress PC5 / Uu Relay RLC channel, to the U2N Relay UE#1. Alternatively, the gNB-CU may allocate / configure SRAP information, information for mapping / routing SRAP Data PDUs transmitted through a specific ingress PC5 / Uu Relay RLC channel for SRB1 to a specific egress Uu / PC5 Relay RLC channel, to the U2N Relay UE#1. The above information can be allocated / set per Local ID for U2N Remote UE, or per pair of Local ID for U2N Remote UE and Peer UE Information for U2N Relay UE#2.

[0257] Step 14: If the PC5 Relay RLC channel for forwarding the SRB1 message of the U2N Remote UE is not allocated / configured to the U2N Relay UE#2, the gNB-CU may send a UE context modification message to the gNB-DU in Step 14a. For example, the gNB-CU may request the gNB-DU to allocate / configure the PC5 Relay RLC channel configuration for the PC5 connection between the U2N Relay UE#1 and the U2N Relay UE#2 for forwarding the SRB1 message through the F1AP UE Context Modification procedure. And / or, the gNB-CU may request the gNB-DU to allocate / configure the PC5 Relay RLC channel configuration for the PC5 connection between the U2N Relay UE#2 and the U2N Remote UE. If a PC5 Relay RLC channel configuration for the PC5 connection between U2N Relay UE#1 and U2N Relay UE#2 was allocated / created in Step 7 or Step 13a, the gNB-DU may also allocate / configure the same configuration for U2N Relay UE#2. The gNB-DU may transmit the allocated / configured configuration to the gNB-CU.

[0258] In Step 11, the gNB-DU may have allocated / configured the PC5 Relay RLC channel configuration for the PC5 connection between the U2N Relay UE#2 and the U2N Remote UE. In this case, the gNB-DU can allocate / configure the configuration for the U2N Relay UE#2. The gNB-DU can then transmit the allocated / configured configuration to the gNB-CU.

[0259] At this time, in order to notify that this is a PC5 Relay RLC channel created / allocated from U2N Relay UE#2 to U2N Relay UE#1, the gNB-CU may also transmit to gNB-DU the Peer UE Information related to U2N Relay UE#1. For example, the gNB-CU may also transmit to gNB-DU a UE context modification request message including Peer UE Information related to U2N Relay UE#1. In order to notify that this is a PC5 Relay RLC channel created / allocated from U2N Relay UE#2 to U2N Remote UE, the gNB-CU may also transmit to gNB-DU the Peer UE Information related to U2N Remote UE. For example, the gNB-CU may also transmit to gNB-DU a UE context modification request message including Peer UE Information related to U2N Remote UE.

[0260] Step 14b may be performed so that the gNB-CU can forward the PC5 Relay RLC channel configuration received from the gNB-DU in Step 14a to the U2N Relay UE#2. For example, the gNB-CU may perform an RRC Reconfiguration process. For example, the gNB-CU may transmit a message related to RRC reconfiguration to the U2N Relay UE#2 via the gNB-DU and the U2N Relay UE#1.

[0261] Additionally, the gNB-CU may allocate / configure SRAP information for mapping / routing each SRAP Data PDU belonging to SRB1 to a specific egress PC5 Relay RLC channel to the U2N Relay UE#2. Alternatively, the gNB-CU may also allocate / configure SRAP information for mapping / routing SRAP Data PDUs transmitted through a specific ingress PC5 Relay RLC channel for SRB1 to a specific egress PC5 Relay RLC channel to the U2N Relay UE#2. The above information may be allocated / configured for each Local ID for U2N Remote UE, or for each pair of Local ID for U2N Remote UE and each Peer UE Information.

[0262] In some implementations, it is also possible for the gNB-CU to differentiate between the PC5 Relay RLC channel for UL and the PC5 Relay RLC channel for DL ​​by separately setting Peer UE Information for the same Local ID for U2N Remote UEs. For example, in Figures 6a to 6c, the gNB-CU can transmit the following SRAP configuration to U2N Relay UE#2:

[0263] i) SRAP for UL

[0264] - Local ID for U2N Remote UE

[0265] - Peer UE Information for U2N Relay UE#1

[0266] - PC5 Relay RLC channel

[0267] ii) SRAP for DL

[0268] - Local ID for U2N Remote UE

[0269] - Peer UE Information for U2N Remote UE

[0270] - PC5 Relay RLC channel

[0271] The PC5 Relay RLC channel for the U2N Remote UE may be allocated / configured differently for DL ​​and UL, respectively. In this case, the gNB-CU may transmit information to the U2N Relay UE#2 regarding whether the SRAP information is for DL ​​or UL transmission. This may take the form of allocating / configuring different Local IDs for the DL and UL to the U2N Remote UE.

[0272] Note that Steps 13 and 14 may be performed concurrently / in parallel, or in an out-of-order manner.

[0273] Step 15: The U2N Remote UE can send an RRCSetupComplete message to the base station.

[0274] For example, the U2N Remote UE may transmit an RRCSetupComplete message to the base station after completing Bearer allocation / configuration and / or PC5 Relay RLC channel allocation / configuration to be used in the RRC connection with the base station according to the RRCSetup message received in Step 12. The U2N Remote UE may also transmit an RRCSetupComplete message containing a Registration Request message for registration with the network.

[0275] Based on the information received in Step 12, the U2N Remote UE can configure the SRAP header of the RRCSetupComplete message into a format suitable for transmitting an SRB1 message. The U2N Remote UE can transmit the RRCSetupComplete message to the base station via U2N Relay UE#2 and U2N Relay UE#1.

[0276] Step 16: The base station forwards the Registration Request message received in Step 15 to the AMF, and the AMF may transmit a Registration Accept message for the UE to the base station. The gNB-CU may decide to additionally create and / or allocate SRBs and / or DRBs to exchange data and / or signaling with the U2N Remote UE based on the information received from the AMF. In this case, the gNB-CU may perform the process of Step 13 and / or Step 14 to allocate / configure PC5 / Uu Relay RLC channel configuration information for the additionally created / allocated SRBs and / or DRBs. The gNB-CU may transmit this PC5 / Uu Relay RLC channel configuration information to the U2N Relay UE#1 and / or the U2N Relay UE#2.

[0277] Step 17: The gNB-CU may send a UE context modification message to the gNB-DU in Step 17a. For example, the gNB-CU may request the gNB-DU to allocate / set PC5 Relay RLC channel configuration information for SRBs and / or DRBs in the PC5 connection (e.g., the first PC5 connection) between the U2N Remote UE and the U2N Relay UE#2 through the F1AP UE Context Modification procedure of the U2N Remote UE. The gNB-DU may send the PC5 Relay RLC channel configuration information to the gNB-CU. During this process, the gNB-CU may also send Peer UE Information to the gNB-DU to notify that the PC5 Relay RLC channel is created / allocated toward the U2N Relay UE#2.

[0278] In Step 17b, the gNB-CU may request the U2N Remote UE to create an SRB and / or DRB for transmitting and / or receiving signaling and / or data through an RRC Reconfiguration process. For this purpose, the gNB-CU may allocate / configure PDCP and SDAP configurations for the SRB and / or DRB together. In addition, the gNB-CU may transmit, to the U2N Remote UE, PC5 Relay RLC channel configuration information for the SRB and / or DRB in the PC5 connection (e.g., the first PC5 connection) between the U2N Remote UE and the U2N Relay UE#2, which is allocated / configured by the gNB-DU in Step 17a. Based on the configuration information received from the gNB-CU, the U2N Remote UE may allocate / configure a PC5 Relay RLC channel toward the U2N Relay UE#2.

[0279] Step 18: UL / DL data for U2N Remote UE is transmitted through U2N Relay UE#1 and U2N Relay UE#2.

[0280] Step 19: A new U2N Remote UE may attempt to connect to the network by repeating Steps 1 to 18 of FIGS. 6a to 6c. In this case, the existing U2N Remote UE may perform the role of U2N Relay UE#3. The U2N Relay UE#3 (e.g., the existing U2N Remote UE in FIGS. 6a to 6c) may be in RRC_IDLE or RRC_INACTIVE state. In this case, when the existing U2N Remote UE receives an RRCSetupRequest message from the new U2N Remote UE, it may repeat Steps 3 to 17 of FIGS. 6a to 6c to transition to the RRC_CONNECTED state and then perform the role of U2N Relay UE#3.

[0281] NOTE: U2N Relay UE#3 in RRC_IDLE or RRC_INACTIVE state can select U2N Relay UE#1 and U2N Relay UE#2 as Serving Relays of U2N Relay UE#3 by referring to the entire path selected in Step 1, without executing a separate Relay discovery process to (re)select U2N Relay UE(s) that can provide connection to the network.

[0282] The following drawings are intended to illustrate specific examples of the present specification. The names of specific devices and the names of specific signals, messages, and fields depicted in the drawings are provided for illustrative purposes only, and the technical features of this specification are not limited to the specific names used in the drawings.

[0283] FIGS. 7A to 7C are a second example of a procedure related to initial connection of a remote UE according to one embodiment of the disclosure of the present specification.

[0284] Figures 7a to 7c are examples of procedures related to initial connection of a U2N remote UE via multi-hop U2N relay operation.

[0285] Step 1~3: Can be performed in the same manner as steps 1~3 of FIGS. 6a to 6c.

[0286] Step 4: If U2N Relay UE#2 is in RRC_IDLE or RRC_INACTIVE state, U2N Relay UE#2 may perform state transition to RRC_CONNECTED.

[0287] For example, after U2N Relay UE#2 receives the RRCSetupRequest message of U2N Remote UE, it can transition to RRC_CONNECTED state using the procedure of Figure 8.19.1-1 or Figure 8.19.3-1 of TS 38.401 V18.1.0.

[0288] In this process, the base station can allocate a local ID to the U2N Relay UE#2 that has accessed the network as a U2N Remote UE. In addition, the base station can allocate / configure information related to mapping / routing SRBs and DRBs related to the local ID for U2N Relay UE#2 to a specific egress PC5 / Uu Relay RLC channel to the U2N Relay UE#2 and U2N Relay UE#1. In this process, the U2N Relay UE#1 can also directly inform the base station of an L2 ID (e.g., L2 ID for U2N Relay UE#1 in multi-hop U2N relay operation) to be used when participating as a U2N Relay UE (e.g., Intermediate U2N Relay UE or Last U2N Relay UE) in a multi-hop U2N relay operation.

[0289] Prior to Step 4, U2N Relay UE#2 may have already transitioned to RRC_CONNECTED state using the procedure in Figure 8.19.1-1 or Figure 8.19.3-1 of TS 38.401 V18.1.0.

[0290] In Step 4a, U2N Relay UE#2 can send SidelinkUEInformationNR message to base station (e.g. gNB-CU via gNB-DU). By sending SidelinkUEInformationNR message, U2N Relay UE#2 can request base station to set up / create Uu Relay RLC channel for sending RRCSetupRequest message of U2N Remote UE.

[0291] In this process, U2N Relay UE#2 can also directly transmit to the base station its L2 ID (i.e., L2 ID for U2N Relay UE#2 in multi-hop U2N relay operation) to be used when participating as a U2N Relay UE (i.e., Intermediate U2N Relay UE or Last U2N Relay UE) in a multi-hop U2N relay operation. The gNB already knows that U2N Relay UE#2 is accessing through U2N Relay UE#1. U2N Relay UE#2 can inform the gNB of its L2 ID (i.e., L2 ID for U2N Relay UE#2 in multi-hop U2N relay operation) to be used when participating as a U2N Relay UE (i.e., Intermediate U2N Relay UE or Last U2N Relay UE) in a multi-hop U2N relay operation. In this case, the gNB may know that the entire path of the U2N Remote UE accessing the gNB through the U2N Relay UE#2 is formed as U2N Remote UE->U2N Relay UE#2 -> U2N Relay UE#1->gNB.

[0292] Additionally, the U2N Relay UE#2 can transmit to the base station the L2 IDs of each node involved in the network connection (Path) for the U2N Remote UE (e.g., L2 IDs for U2N Remote UE, U2N Relay UE#1, and U2N Relay UE#2). For example, the U2N Relay UE#2 can transmit to the base station a sidelinkUEinformationNR message including the L2 IDs of each node (e.g., L2 IDs for U2N Remote UE, U2N Relay UE#1, and U2N Relay UE#2). The U2N Relay UE#2 can also explicitly receive information about the entire path from the U2N Remote UE or U2N Relay UE#1 in Step 1 or Step 2. Alternatively, U2N Relay UEs located in the section between a U2N Relay UE located at the first hop (e.g., a U2N Relay UE directly connected to a U2N Remote UE, e.g., U2N Relay UE#2 in FIGS. 7a to 7c) and a U2N Relay UE located at the last hop (e.g., a U2N Relay UE directly connected to a base station, e.g., U2N Relay UE#1 in Figure 3-1-2) may transmit their L2 IDs to the U2N Relay UE located at the first hop (i.e., U2N Relay UE#2) in Step 1 or Step 2. Based on this, the U2N Relay UE#2 may generate information about the entire path by combining it with the L2 ID for the U2N Remote UE.Alternatively, in Step 4, when the U2N Relay UE (e.g., U2N Relay UE#2) located at the first hop transitions to the RRC_CONNECTED state, the gNB-CU may generate information about the entire path by combining the L2 ID (e.g., L2 ID for U2N Relay UE#1 in FIGS. 7a to 7c) of each node involved in the network connection (Path) for the U2N Relay UE (e.g., U2N Relay UE#2) located at the first hop with the L2 IDs for U2N Relay UE#2 and U2N Remote UE received at Step 4a.

[0293] Based on the information contained in the SidelinkUEInformationNR message, the gNB-CU can determine that the U2N Relay UE#2 has joined the path as an Intermediate U2N Relay UE. In addition, the gNB-CU can derive the gNB-DU UE F1AP ID and the gNB-CU UE F1AP ID, which identify the UE context for the U2N Relay UE#2 within the gNB-CU and the gNB-DU.

[0294] Additionally, the gNB-CU receiving the SidelinkUEInformationNR message can allocate / configure a local ID for the U2N Remote UE. As in the UE-to-Network Relay operation in TS 38.351 V18.1.0, the gNB-CU can route data and / or signaling of the U2N Remote UE through the local ID allocated / configured in Step 4 in all sections between the U2N Remote UE and the base station. For this purpose, the Local ID value defined in TS 38.331 V18.1.0 (e.g., INTEGER (0..255)) can be used. Alternatively, a separate Local ID can be defined for the Multi-hop U2N Relay operation to distinguish it from the existing Single-hop U2N Relay operation. Alternatively, the base station may separately set / allocate i) a Local ID for DL ​​to be used for routing DL data and / or signaling transmitted to the U2N Remote UE and ii) a Local ID for UL to be used for routing UL data and / or signaling transmitted by the U2N Remote UE to the base station.

[0295] NOTE: A U2N Relay UE#2 in RRC_IDLE or RRC_INACTIVE state may select U2N Relay UE#1 as the Serving Relay of U2N Relay UE#2 by referring to the entire path selected in Step 1, without performing a separate Relay discovery process to (re)select U2N Relay UE(s) that can provide connectivity to the network.

[0296] Step 5: The gNB-CU may send a UE context modification request message to the gNB-DU.

[0297] For example, the gNB-CU can forward the SidelinkUEInformationNR message received in Step 4a to the gNB-DU via the F1AP UE CONTEXT MODIFICATION REQUEST message of the U2N Relay UE#2.

[0298] Additionally, the gNB-CU can request the gNB-DU to allocate / set the Uu Relay RLC channel configuration required to transmit the SRB0 / 1 message to the U2N Remote UE. The gNB-DU can allocate / set the Uu Relay RLC channel configuration and respond to the gNB-CU via an F1AP UE CONTEXT MODIFICATION RESPONSE message.

[0299] The gNB-CU may send the Local ID for U2N Remote UE to the gNB-DU while requesting the gNB-DU to allocate / set the Uu Relay RLC channel configuration required to transmit the SRB0 / 1 message for the U2N Remote UE. Based on the Local ID for U2N Remote UE and the Uu Relay RLC channel configuration allocation / configuration information in Step 10, the gNB-DU may know that the U2N Remote UE is accessing the gNB-DU via U2N Relay UE#2 and U2N Relay UE#1. If the Local ID for the U2N Remote UE is allocated / set differently for DL / UL in Step 4, a Uu Relay RLC channel configuration may be allocated / generated for each Local ID.

[0300] Additionally, the gNB-CU may request the gNB-DU to allocate / configure the PC5 Relay RLC channel configuration between U2N Relay UE#2 and U2N Relay UE#1, which is required to transmit the SRB0 / 1 message for the U2N Remote UE, via the F1AP UE CONTEXT MODIFICATION REQUEST message. In this case, the gNB-CU may also transmit the Local ID for U2N Remote UE to the gNB-DU to indicate that the PC5 Relay RLC channel is for the U2N Remote UE. Furthermore, the gNB-CU may also transmit the Peer UE Information for U2N Relay UE#2 to the gNB-DU to indicate that the PC5 Relay RLC channel is created / allocated from U2N Relay UE#1 to U2N Relay UE#2. For example, the Peer UE Information information may include one or more of the following information:

[0301] - gNB-CU UE F1AP ID allocated / configured by gNB-CU for U2N Relay UE#2;

[0302] - gNB-DU UE F1AP ID allocated / configured by gNB-DU for U2N Relay UE#2;

[0303] - L2 ID for U2N Relay UE#2; and / or

[0304] - Local ID for U2N Relay UE#2.

[0305] The gNB-CU may have obtained the following information in Step 4 or Step 4a via the F1AP UE CONTEXT MODIFICATION REQUEST message from the U2N Relay UE#1. For example, the gNB-CU may have obtained the L2 ID (i.e., L2 IDs for U2N Remote UE, U2N Relay UE#1, and U2N Relay UE#2) or UE F1AP IDs (i.e., gNB-CU / gNB-DU UE F1AP IDs for U2N Remote UE, U2N Relay UE#1, and U2N Relay UE#2) of each node involved in the network connection (Path) for the U2N Remote UE. In this case, the gNB-CU may forward these L2 IDs or UE F1AP IDs to the gNB-DU. This information may also be provided to the gNB-DU in Step 7, 12a, 13a, or 15 instead of Step 5.

[0306] NOTE: The PC5 Relay RLC channel for the U2N Remote UE may be allocated / configured differently for DL / UL. Alternatively, if the Local ID for the U2N Remote UE is allocated / configured differently for DL / UL in Step 4, a PC5 Relay RLC channel configuration may be allocated / created for each Local ID.

[0307] Step 6: The gNB-CU may send an RRCReconfiguration message to the U2N Relay UE#1 containing one or more of the following information so that the gNB-CU can route the SRB0 / 1 message of the U2N Remote UE:

[0308] A. Local ID for U2N Remote UE allocated / set in Step 4 to distinguish / identify U2N Remote UE in Uu link or Uu Relay RLC channel between U2N Relay UE#1 and base station;

[0309] B. Uu Relay RLC channel configuration required for transmitting the SRB0 / 1 message for the U2N Remote UE received by the gNB-CU from the gNB-DU in Step 5;

[0310] C. PC5 Relay RLC channel configuration between U2N Relay UE#2 and U2N Relay UE#1 for transmitting the SRB0 / 1 message for the U2N Remote UE received by the gNB-CU from the gNB-DU in Step 5; and / or

[0311] D. SRAP information for mapping / routing each SRAP Data PDU belonging to SRB0 / 1 to a specific egress PC5 / Uu Relay RLC channel. Or, SRAP information for mapping / routing SRAP Data PDUs transmitted through a specific ingress PC5 / Uu Relay RLC channel for SRB0 / 1 to a specific egress Uu / PC5 Relay RLC channel. The information may be allocated / configured for each Local ID for U2N Remote UE, or for each pair of Local ID for U2N Remote UE and Peer UE Information for U2N Relay UE#2. If the PC5 Relay RLC channel for U2N Remote UE is allocated / configured differently for DL / UL, the gNB-CU may also transmit information related to whether the SRAP information is for DL ​​transmission or UL transmission to U2N Relay UE#1.

[0312] Step 7: The gNB-CU may send a UE context modification message to the gNB-DU to allocate / configure a PC5 Relay RLC channel to U2N Relay UE#2 for forwarding the SRB0 / 1 message of the U2N Remote UE.

[0313] For example, the UE context modification message transmitted by the gNB-CU in step 7 may be a UE context modification request message.

[0314] For example, the gNB-CU can request the gNB-DU to allocate / configure the PC5 Relay RLC channel configuration for the PC5 connection between U2N Relay UE#1 and U2N Relay UE#2 for SRB0 / 1 message delivery to the gNB-DU through the F1AP UE Context Modification procedure. In addition, the gNB-CU can request the gNB-DU to allocate / configure the PC5 Relay RLC channel configuration for the PC5 connection between U2N Relay UE#2 and U2N Remote UE for SRB1 message delivery of the U2N Remote UE. If the gNB-DU allocates / creates the PC5 Relay RLC channel configuration for the PC5 connection between U2N Relay UE#1 and U2N Relay UE#2 in Step 5, the gNB-DU can allocate / configure the same configuration to U2N Relay UE#2. Alternatively, the gNB-DU may allocate / create different PC5 Relay RLC channel configurations for the PC5 connection from U2N Relay UE#1 to U2N Relay UE#2 and different PC5 Relay RLC channel configurations for the PC5 connection from U2N Relay UE#2 to U2N Relay UE#1 (for example, the gNB-DU may allocate / create different PC5 Relay RLC channel configurations for the UL direction and the DL direction).At this time, the gNB-CU may also transmit Peer UE Information for U2N Relay UE#1 to the gNB-DU to inform that this is a PC5 Relay RLC channel created / allocated from U2N Relay UE#2 to U2N Relay UE#1. The gNB-CU may also transmit Peer UE Information for U2N Remote UE to the gNB-DU to inform that this is a PC5 Relay RLC channel created / allocated from U2N Relay UE#2 to U2N Remote UE.

[0315] For example, Peer UE Information for U2N Relay UE#1 may be the Layer 2 (L2) ID of U2N Relay UE#1. For example, Peer UE Information for U2N Remote UE may be the L2 ID of the U2N Remote UE.

[0316] For example, Peer UE Information for U2N Relay UE#1 may be information related to the upstream direction (e.g., toward U2N Relay UE#1) of the UE (e.g., U2N Relay UE#2) involved in the UE context modification message. Or, Peer UE Information for U2N Remote UE may be information related to the downstream direction (e.g., toward the remote UE) of the UE (e.g., U2N Relay UE#2) involved in the UE context modification message.

[0317] For example, the UE context modification message may include PC5 control plane traffic type information including Signaling Radio Bearer (SRB)0 and / or SRB1.

[0318] Step 8: The gNB-CU can send an RRC reset message to U2N Relay UE#2.

[0319] For example, in order to forward the PC5 Relay RLC channel configuration received from the gNB-DU in Step 7 to the U2N Relay UE#2, the gNB-CU may perform an RRC Reconfiguration process. In addition, the gNB-CU may allocate / configure SRAP information for mapping / routing each SRAP Data PDU belonging to SRB0 / 1 to a specific egress PC5 Relay RLC channel, or SRAP information for mapping / routing SRAP Data PDUs transmitted through a specific ingress PC5 Relay RLC channel for SRB0 / 1 to a specific egress PC5 Relay RLC channel, to the U2N Relay UE#2. One or more of the above two pieces of SRAP information may be allocated / configured for each Local ID for U2N Remote UE, or for each pair of Local ID for U2N Remote UE and each Peer UE Information.

[0320] In some implementations, it is also possible for the gNB-CU to differentiate between the PC5 Relay RLC channel for UL and the PC5 Relay RLC channel for DL ​​by separately setting Peer UE Information for the same Local ID for U2N Remote UEs. For example, in Figures 7a to 7c, the gNB-CU can transmit the following SRAP configuration to U2N Relay UE#2:

[0321] i) SRAP for UL

[0322] - Local ID for U2N Remote UE

[0323] - Peer UE Information for U2N Relay UE#1

[0324] - PC5 Relay RLC channel

[0325] ii) SRAP for DL

[0326] - Local ID for U2N Remote UE

[0327] - Peer UE Information for U2N Remote UE

[0328] - PC5 Relay RLC channel

[0329] The PC5 Relay RLC channel for the U2N Remote UE may be allocated / configured differently for DL ​​and UL, respectively. In this case, the gNB-CU may transmit information to the U2N Relay UE#2 regarding whether the SRAP information is for DL ​​or UL transmission. This may take the form of allocating / configuring different Local IDs for the DL and UL to the U2N Remote UE.

[0330] Note that Steps 13 and 14 may be performed concurrently / in parallel, or in an out-of-order manner.

[0331] Step 9: U2N Relay UE#1 can send an RRCSetupRequest message to gNB-DU.

[0332] For example, U2N Relay UE#1 can transmit the RRCSetupRequest message received in Step 3 to gNB-DU through the configuration allocated / set in Step 8. At this time, based on the information received in Step 8 (e.g., Local ID for U2N Remote UE, BEARER ID for SRB0, etc.), U2N Relay UE#1 can configure an SRAP header and transmit the SRAP header to gNB-DU, as in the UE-to-Network Relay operation in TS 38.351 V18.1.0. At this time, in order for gNB-DU to distinguish between the existing Single-hop U2N Relay operation and the Multi-hop U2N Relay operation, U2N Relay UE#1 can perform the following operations. For example, U2N Relay UE#1 may explicitly include an indication in the SRAP header that it is a multi-hop U2N Relay operation and / or the number of U2N Relay UEs required for the U2N Remote UE to connect to the network (i.e., Number of hops (n)). Alternatively, U2N Relay UE#1 may implicitly notify the gNB-DU of the multi-hop U2N Relay operation by including a separate Local ID defined in Step 4 in the SRAP header. In this case, U2N Relay UE#1 may forward the RRCSetupRequest message of the U2N Remote UE, sent by U2N Relay UE#2, to the gNB-DU based on the configuration allocated / set in Step 6.

[0333] Step 10: gNB-DU can send INITIAL UL RRC MESSAGE TRANSFER to gNB-CU.

[0334] For example, the gNB-DU can determine that the U2N Remote UE is accessing the gNB-DU for the first time based on the BEARER ID (e.g., SRB0) in the SRAP header received in Step 9. In addition, based on information such as the Uu Relay RLC channel through which the RRCSetupRequest message was transmitted, the gNB-DU can determine that the U2N Remote UE is accessing via U2N Relay UE#1. In addition, based on additional information included in the SRAP header (e.g., indication indicating a multi-hop U2N Relay operation and / or Number of hops (n), Local ID for U2N Remote UE, etc.), the gNB-DU can determine that an Intermediate U2N Relay UE(s) currently exists between the U2N Remote UE and U2N Relay UE#1. Alternatively, by comparing the information such as the Uu Relay RLC channel to which the RRCSetupRequest message was transmitted and the Local ID information included in the SRAP header with the Local ID for U2N Remote UE and / or Uu Relay RLC channel allocation / creation request information received from the gNB-CU in Step 5, the gNB-DU may know that the U2N Remote UE is accessing the gNB-DU via U2N Relay UE#2 and U2N Relay UE#1.

[0335] The gNB-DU may determine that it can service the above U2N Remote UE. In this case, the gNB-DU may allocate / create a lower layer configuration for a PC5 Relay RLC channel between the U2N Remote UE and the first hop U2N Relay UE (e.g., U2N Relay UE#2), rather than between the U2N Remote UE and U2N Relay UE#1. The gNB-DU may transmit the lower layer configuration for the PC5 Relay RLC channel to the gNB-CU via an F1AP INITIAL UL RRC MESSAGE TRANSFER message. In addition, the lower layer configuration information for the PC5 Relay RLC channel thus allocated / created may be stored and / or kept in the U2N Remote UE's context within the gNB-DU. Additionally, the gNB-DU may send the gNB-DU UE F1AP ID for the U2N Relay UE located at the last hop (e.g., U2N Relay UE#1) and the Local ID for U2N Remote UE included in the SRAP header received in Step 9 to the gNB-CU via the INITIAL UL RRC MESSAGE TRANSFER message. If, based on the information in Step 4, Step 5, and / or Step 10, the gNB-DU may determine that the entire path of the U2N Remote UE is formed as U2N Remote UE→U2N Relay UE#2→U2N Relay UE#1→gNB, the gNB-DU may also send the INITIAL RRC MESSAGE TRANSFER to the gNB-CU, including the gNB-DU UE F1AP ID for the U2N Relay UE located at the first hop (i.e., U2N Relay UE#2).

[0336] Based on the SidelinkUEInformationNR message received in Step 4 and the F1AP INITIAL UL RRC MESSAGE TRANSFER message received in Step 10, the gNB-CU can determine that the U2N Remote UE is accessing the base station via U2N Relay UE#2 and U2N Relay UE#1. The gNB-CU can derive the gNB-DU UE F1AP ID and the gNB-CU UE F1AP ID, which identify the UE context for U2N Relay UE#2 and U2N Relay UE#1 within the gNB-CU and gNB-DU, respectively, as follows:

[0337] - gNB-DU UE F1AP ID and gNB-CU UE F1AP ID for U2N Relay UE#1

[0338] - gNB-DU UE F1AP ID and gNB-CU UE F1AP ID for U2N Relay UE#2

[0339] Step 11: The gNB-CU can send a DL RRC MESSAGE TRANSFER message to the gNB-DU.

[0340] For example, the gNB-CU may decide to establish an RRC connection with a U2N Remote UE. In this case, the gNB-CU may generate an RRCSetup message and send an F1AP DL RRC MESSAGE TRANSFER message containing the RRCSetup message to the gNB-DU.

[0341] The gNB-DU can configure the SRAP header by referring to the SRB Mapping InfoIE included in the F1AP DL RRC MESSAGE TRANSFER message. The gNB-DU can forward the RRCSetup message to the U2N Remote UE via U2N Relay UE#1 and U2N Relay UE#2.

[0342] The gNB-CU can include SRAP information mapping each SRB and DRB to be used by the U2N Remote UE to a specific egress PC5 Relay RLC channel in the RRCSetup message during the PC5 connection between the U2N Remote UE and the U2N Relay UE#2 (e.g., the first PC5 connection). In addition, to inform the U2N Remote UE that the PC5 Relay RLC channel is to the U2N Relay UE#2, the gNB-CU can also include L2 ID for U2N Relay UE#2 information in the SRAP configuration and transmit it to the U2N Remote UE.

[0343] Step 12~18: Steps 13~19 of the above drawings 6a to 6c can be referenced.

[0344] 2. Second example of disclosure of this specification

[0345] In the second example of the disclosure of the present specification, an example of route switching to a multi-hop indirect route is described. For example, an example of route switching from a direct route or a single-hop indirect route to a multi-hop indirect route is described.

[0346] In the second example of the disclosure of this specification, the description or operation for U2N Relay UE#2 (e.g., 2-hop U2N Relay UE) may also be applied to a 3-hop or more hop U2N Relay UE (e.g., intermediate UE-to-Network Relay UE).

[0347] The following drawings are intended to illustrate specific examples of the present specification. The names of specific devices and the names of specific signals, messages, and fields depicted in the drawings are provided for illustrative purposes only, and the technical features of this specification are not limited to the specific names used in the drawings.

[0348] FIG. 8A and FIG. 8B are examples of procedures related to path switching according to one embodiment of the disclosure of the present specification.

[0349] Figures 8a and 8b illustrate examples of procedures involved in switching from a direct path or a single-hop indirect path to a multi-hop indirect path. The examples in Figures 8a and 8b illustrate the intra-DU case. For example, an example is provided where path switching is performed within the same DU.

[0350] Below, steps 0a and 1a are examples of a case where a U2N remote UE switches from a direct path to a multi-hop indirect path. Steps 0b and 1b are examples of a case where a U2N remote UE switches from a single-hop indirect path to a multi-hop indirect path.

[0351] Step 0: For direct path (e.g., Step 0a) (e.g., path switching from a direct path to a multi-hop indirect path), it is assumed that the U2N Remote UE is connected to the base station via the Uu cell of the base station. Or, for indirect path (e.g., Step 0b) (e.g., path switching from a single-hop indirect path to a multi-hop indirect path), it is assumed that the U2N Remote UE is connected to the base station via the U2N Relay UE#4. Therefore, UL / DL data related to the U2N Remote UE can be transmitted via the Uu cell or the U2N Relay UE#4.

[0352] Step 1: The base station can transmit the measurement configuration to the U2N remote UE (Step 1a-1 or Step 1b-1). Based on the measurement configuration, the U2N remote UE can perform measurement (Step 1a-2 or Step 1b-2). The U2N remote UE can report the measurement results to the base station (Step 1a-3 or Step 1b-3). Although steps 1a and 1b are illustrated in FIGS. 8a and 8b, in the examples below, step 1a is divided into 1a-1, 1a-2, and 1a-3 and explained, and step 1b is divided into 1b-1, 1b-2, and 1b-3 and explained.

[0353] (Step 1a-1 or Step 1b-1) The base station can set / assign a measurement configuration to the U2N Remote UE to support connected mode mobility of the U2N Remote UE.

[0354] (Step 1a-2 or Step 1b-2) The U2N Remote UE can perform measurements on Uu links (i.e., direct paths) that can be directly connected to the serving base station and / or the Uu cells of neighboring base stations of the U2N Remote UE. In addition, through the serving U2N Relay UE and / or neighboring U2N Relay UE, the U2N Remote UE can perform measurements on Uu / PC5 link(s) of the indirect path that can be connected to the serving base station and / or neighboring base stations of the U2N Remote UE (i.e., indirect paths).

[0355] In this process, for path switching to a multi-hop indirect path using multiple candidate U2N Relay UEs, the U2N Remote UE can also perform measurements on the Intermediate U2N Relay UE supporting the multi-hop relay operation. It can be assumed that all Intermediate U2N Relay UEs involved in the multi-hop relay operation are in the RRC_CONNECTED state. Therefore, instead of obtaining the PC5 link quality between all nodes involved in a specific multi-hop relay operation, the U2N Remote UE can only perform measurements on the PC5 link between the Intermediate U2N Relay UE and the U2N Remote UE located nearby. At this time, the U2N Remote UE can also obtain quality information on the PC5 link between the Intermediate U2N Relay UE and the U2N Remote UE located nearby through the Multi-hop Relay Discovery or Multi-hop Relay Communication procedure that the U2N Remote UE previously executed / performed. Alternatively, the U2N Remote UE may obtain quality information about the PC5 link between the Intermediate U2N Relay UE and the U2N Remote UE located nearby through the currently created / formed U2U Relay communication or Multi-hop Relay Communication. Additionally, during the measurement and / or Relay discovery process, the U2N Relay UE#2 may transmit Multi-hop selection assistance information to the U2N Remote UE.Multi-hop selection assistance information transmitted by U2N Relay UE#2 may include one or more of the following information: Based on one or more of the following information, U2N Remote UE may also know that U2N Relay UE#2 is connected to the network via multi-hop U2N relay operation:

[0356] - U2N Relay indication that UE#2 is currently connected to the network via multi-hop relay operation;

[0357] - Number of hops (n): The number of U2N Relay UEs required for U2N Relay UE#2 to connect to the network;

[0358] - Information about each node involved in the network connection (e.g. User Info ID) and L2 ID of each node (i.e. L2 IDs for U2N Relay UE#1 and U2N Relay UE#2);

[0359] - Local ID assigned / set by the base station during the process of U2N Relay UE#2 connecting to the network as a Remote UE; and / or

[0360] - L2 ID used when U2N Relay UE#2 connects to the network as a Remote UE.

[0361] Alternatively, the U2N Remote UE may perform a relay discovery process for a new multi-hop relay operation, thereby receiving quality information about each PC5 link. For example, the U2N Remote UE may perform a relay discovery process for a multi-hop relay operation based on an explicit indication included in the base station's measurement configuration. Alternatively, the U2N Remote UE may determine whether to perform a relay discovery process for a multi-hop relay operation based on the measurement configuration.

[0362] (Step 1a-3 or Step 1b-3) If one or more of the following events occur, the U2N Remote UE may notify the base station of the occurred event and / or measurement result:

[0363] i) The U2N Remote UE may be currently connected via a direct path. In this case, if the link quality of a) a Uu link (i.e., direct path) that can be directly connected via the Uu cell of the serving base station and / or neighboring base stations of the U2N Remote UE, excluding the current serving Uu cell, and b) a Uu / PC5 link(s) that can be connected to the serving base station and / or neighboring base stations of the U2N Remote UE via a neighboring U2N Relay UE (i.e., indirect path) are greater than / higher / better than a threshold value in the measurement configuration;

[0364] ii) The U2N Remote UE may currently be connected via a direct path. In this case, if the Uu link quality via the current serving Uu cell is lower / worse / less than the threshold value in the measurement configuration;

[0365] iii) The U2N Remote UE may be currently connected via an indirect path. In this case, if the link quality of the Uu link (i.e., direct path) that can be directly connected via the Uu cell of the serving base station and / or neighboring base stations of the U2N Remote UE and the Uu / PC5 link(s) that can be connected to the serving base station and / or neighboring base stations of the U2N Remote UE via neighboring U2N Relay UEs, excluding the current serving U2N Relay UE (i.e., indirect path) is greater than / higher / better than the threshold value in the measurement configuration;

[0366] iv) If the U2N Remote UE is currently connected via an indirect path, the link quality for the Uu / PC5 link(s) (i.e., the indirect path) via the current serving U2N Relay UE is less than / lower than / worse than the threshold value in the measurement configuration; and / or

[0367] v) If the link quality of the PC5 connection between the U2N Remote UE and U2N Relay UE#2 discovered through Step 1a-2 or Step 1b-2 is greater than / higher / better than the threshold value in the measurement configuration.

[0368] The measurement results transmitted by the U2N Remote UE to the base station may include one or more of the following information:

[0369] a) The quality of the Uu link (i.e., direct path) that can be directly connected through the Uu cell of the serving base station and / or surrounding base station of the U2N Remote UE, the ID of the Uu cell, and / or the gNB ID of the serving base station and / or surrounding base station of the U2N Remote UE;

[0370] b) link quality for Uu / PC5 link(s) (e.g., indirect path) that can be connected to the serving base station and / or surrounding base stations of the U2N Remote UE via the current serving U2N Relay UE and / or surrounding U2N Relay UE, the serving cell ID of the U2N Relay UE, the gNB ID of the serving base station of the U2N Relay UE, and / or an identifier for the U2N Relay UE (e.g., L2 ID);

[0371] c) Link quality of all PC5 links (e.g., first to third PC5 connections) located between the U2N Remote UE and the U2N Relay UE#1 and / or identifier(s) for the U2N Relay UE associated with each PC5 link (e.g., L2 ID). It is also possible to report link quality values ​​to the base station only for some PC5 links.

[0372] d) Multi-hop selection assistance information received by the U2N Remote UE from the U2N Relay UE#2 during Step 1a-2 or Step 1b-2.

[0373] Step 2: The gNB-CU can decide the path switching of the U2N Remote UE.

[0374] For example, based on the measurement results received in Step 1 (e.g., L2 ID for Target U2N Relay UE#2 and / or Multi-hop selection assistance information, etc.), the gNB-CU may know that the Target U2N Relay UE#2 is currently in RRC_CONNECTED state and is connected to the base station via Target U2N Relay UE#1. The gNB-CU may decide to switch the path of the U2N Remote UE to a 2-hop indirect path via Target U2N Relay UE#2 and Target U2N Relay UE#1 (which may be connected to the same base station) (e.g., intra-gNB path switching). Here, the Target U2N Relay UE#1 or the Target U2N Relay UE#2 may be the same U2N Relay UE#3 that was involved in the existing single-hop relay operation, or may be a new U2N Relay UE.

[0375] Step 3: The gNB-CU can send a UE context modification message to the gNB-DU.

[0376] For example, the gNB-CU may decide to perform indirect path switching to a 2-hop indirect path through Target U2N Relay UE#1 and Target U2N Relay UE#2 in Step 2. In this case, in order to allocate / configure information (e.g., local ID and L2 ID for the U2N Remote UE, Uu Relay RLC channel configuration and PC5 Relay RLC channel configuration for relaying signaling and / or data of the U2N Remote UE, and / or bearer mapping configuration, etc.) to U2N Relay UE#1, the gNB-CU may perform an F1AP UE Context Modification process of the U2N Relay UE#1 in Step 3a. The gNB-CU may request the gNB-DU to allocate / configure PC5 / Uu Relay RLC channel configuration information for SRB and / or DRB transmission of the U2N Remote UE. At this time, the local ID for the U2N Remote UE may be newly allocated / configured by the gNB-CU. Alternatively, the local ID allocated / configured by the gNB-CU during the process of setting up / allocating single-hop relay operation (i.e., before Step 0b) may be reused as the local ID for the U2N Remote UE. In addition, to notify that the PC5 Relay RLC channel is created / allocated from U2N Relay UE#1 to U2N Relay UE#2, the gNB-CU may also transmit Peer UE Information for U2N Relay UE#2 to the gNB-DU.Peer UE Information for U2N Relay UE#2 may include one or more of the following information:

[0377] - gNB-CU UE F1AP ID allocated / configured by gNB-CU for U2N Relay UE#2

[0378] - gNB-DU UE F1AP ID assigned / configured by gNB-DU for U2N Relay UE#2

[0379] - L2 ID for U2N Relay UE#2

[0380] - Local ID for U2N Relay UE#2

[0381] Additionally, the gNB-CU may provide the gNB-DU with the L2 ID (i.e., L2 IDs for U2N Remote UE, U2N Relay UE#1, and U2N Relay UE#2) or UE F1AP IDs (i.e., gNB-CU / gNB-DU UE F1AP IDs for U2N Remote UE, U2N Relay UE#1, and U2N Relay UE#2) of each node involved in the network connection (Path) for the U2N Remote UE through the F1AP UE CONTEXT MODIFICATION REQUEST message of the U2N Relay UE#1 in Step 3a. This information may be provided to the gNB-DU through Steps 4a, 5, etc. instead of Step 3a. Alternatively, the gNB-DU may know this information through the SRAP header that the U2N Remote UE sends to the gNB-DU in Step 8.

[0382] The gNB-DU can send the PC5 / Uu Relay RLC channel configuration to the gNB-CU. To forward the PC5 / Uu Relay RLC channel configuration received from the gNB-DU in Step 3a to the U2N Relay UE#1, the gNB-CU can perform an RRC Reconfiguration process in Step 3b. For example, the gNB-CU can send an RRC Reconfiguration message to the U2N Relay UE#1. In addition, the gNB-CU can allocate / configure SRAP information for mapping / routing each SRAP Data PDU belonging to the SRB and / or DRB of the U2N Remote UE to a specific egress PC5 / Uu Relay RLC channel to the U2N Relay UE#1. Alternatively, the gNB-CU may allocate / configure SRAP information for mapping / routing SRAP Data PDUs transmitted through a specific ingress PC5 / Uu Relay RLC channel to a specific egress Uu / PC5 Relay RLC channel to the U2N Relay UE#1. The information may be allocated / configured per Local ID for U2N Remote UE, or per pair of Local ID for U2N Remote UE and Peer UE Information for U2N Relay UE#2.

[0383] Step 4: Step 3 can be performed for the Target U2N Relay UE#2 to allocate / configure information required for the Target U2N Relay UE#2 to serve the U2N Remote UE (e.g., local ID and L2 ID for the U2N Remote UE, PC5 Relay RLC channel configurations towards the U2N Remote UE and U2N Relay UE#1 for relaying signaling and / or data of the U2N Remote UE, and / or bearer mapping configuration, etc.). For example, the gNB-CU can request the gNB-DU to allocate / configure PC5 Relay RLC channel configurations for SRB and / or DRB transmission of the U2N Remote UE through the F1AP UE Context Modification process of the U2N Relay UE#2 as in Step 3a.

[0384] The gNB-DU can transmit PC5 Relay RLC channel configurations to the gNB-CU. To forward the PC5 Relay RLC channel configurations received from the gNB-DU in Step 4a to the U2N Relay UE#2, the gNB-CU can execute the RRC Reconfiguration process of the U2N Relay UE#2 as in Step 3b. During this process, the gNB-CU can also transmit Peer UE Information to notify that the PC5 Relay RLC channel is created / allocated to the U2N Relay UE#1 and the U2N Remote UE, respectively.

[0385] Step 5: The gNB-CU can send UE context modification information to the gND-DU.

[0386] For example, in order to allocate / configure information (e.g., local ID for U2N Remote UE, L2 IDs for Target U2N Relay UE#2 and Target U2N Relay UE#1, PC5 Relay RLC channel configuration towards U2N Relay UE#2 for relaying signaling and / or data of the U2N Remote UE, and / or bearer mapping configuration, etc.) to the U2N Remote UE, the gNB-CU may perform an F1AP UE Context Modification process. For example, the gNB-CU may request the gNB-DU to allocate / configure PC5 Relay RLC channel configurations for SRB and / or DRB transmission of the U2N Remote UE through the F1AP UE Context Modification process of the U2N Remote UE. Additionally, the gNB-CU may send Path Info to the gNB-DU in an F1AP UE CONTEXT MODIFICATION REQUEST message so that the gNB-DU can configure / allocate the Path switch configuration within the RRCReconfiguration message to be sent to the U2N Remote UE. For example, the Path Info may include one or more of the following information:

[0387] i. Timer value to be used by the U2N Remote UE while performing path switching on a multi-hop indirect path. The U2N Remote UE must complete path switching before the timer expires;

[0388] ii. Identifiers for Intermediate U2N Relay UEs involved in 2-hop relay operation (e.g., L2 ID);

[0389] iii. Local ID for U2N Remote UE (i.e., local ID for U2N Remote UE to be included in SRAP header). The local ID information of U2N Remote UE may be the local ID assigned / configured by the base station during the process of setting up / allocating single-hop relay operation (e.g., before Step 0b), or the base station may assign / configure a new local ID for 2-hop relay operation;

[0390] The gNB-DU can allocate / set PC5 Relay RLC channel configurations, etc. for the U2N Remote UE at the request of the gNB-CU, and then transmit the PC5 Relay RLC channel configurations, etc. to the gNB-CU.

[0391] Step 6: Based on the information received from the gNB-DU in Step 5, the gNB-CU may transmit to the U2N Remote UE the information (e.g., Path switch configuration) required to perform switching to the 2-hop indirect path via Target U2N Relay UE#1 and Target U2N Relay UE#2. For example, the gNB-CU may transmit an RRCReconfiguration message including this information to the U2N Remote UE via the direct path (Step 6a) or via U2N Relay UE#4 (Step 6b). The RRCReconfiguration message may include one or more of the following information:

[0392] i) Path switch configuration allocated / configured by the gNB-DU in Step 5. The path switch configuration may include one or more of the following:

[0393] i-1) Timer value to be used while U2N Remote UE performs path switching with multi-hop indirect path;

[0394] i-2) Identifiers for Intermediate U2N Relay UEs involved in 2-hop relay operation (e.g., L2 ID); and / or

[0395] i-3) Local ID for U2N Remote UE;

[0396] ii) Information for mapping / routing each SRAP Data PDU belonging to the SRB and DRB to be used by the U2N Remote UE, U2N Relay UE#2, and U2N Relay UE#1, respectively, to a specific egress PC5 Relay RLC channel in each PC5 connection between the U2N Remote UE and the U2N Relay UE#1 (e.g., the first PC5 connection and the second PC5 connection). This may be information for mapping / routing a specific ingress PC5 Relay RLC channel to an egress PC5 Relay RLC channel for each SRB and DRB. Each PC5 Relay RLC channel may be allocated / configured differently for DL / UL. In this case, the gNB-CU may specify whether the SRAP information is for DL ​​transmission or UL transmission. Alternatively, the gNB-CU may allocate / configure a PC5 Relay RLC channel configuration differently for each Peer UE Information and transmit it to each node; and / or

[0397] iii) PC5 Relay RLC channel configuration information and / or Split QoS information for SRB and DRB to be used by U2N Remote UE, U2N Relay UE#2, and U2N Relay UE#1, respectively, in each PC5 connection between U2N Remote UE and U2N Relay UE#1 (i.e., first PC5 connection and second PC5 connection).

[0398] Step 7: U2N Remote UE can perform PC5 connection establishment procedure.

[0399] For example, a U2N Remote UE can create an end-to-end PC5 connection with U2N Relay UE#1 via U2N Relay UE#2 or update an existing PC5 connection using the Clause 16.12.7 procedure of TS 38.300 V18.1.0 or a separately defined PC5 connection creation procedure for multi-hop relay.

[0400] Unlike the above, a unicast PC5 link may be formed between U2N Remote UE and U2N Relay UE in various ways. For example, a unicast PC5 link may be formed hop-by-hop (e.g., U2N Remote UE and U2N Relay UE#2 form a unicast PC5 link, U2N Relay UE#2 and U2N Relay UE#1 form a unicast PC5 link). A U2N Remote UE and U2N Relay UE#1 may also form an end-to-end unicast PC5 link. This can be applied throughout this specification.

[0401] Step 8: To finalize the path switching procedure, the U2N Remote UE can send an RRCReconfigurationComplete message to the gNB-CU through U2N Relay UE#2, U2N Relay UE#1, and gNB-DU.

[0402] Based on additional information included in the SRAP header of the RRCReconfigurationComplete message sent by the U2N Remote UE (e.g., indication of multi-hop U2N Relay operation and / or Number of hops (n), and / or Local ID for U2N Remote UE, etc.), the gNB-DU may know that the current U2N Remote UE is being accessed via U2N Relay UE#2 and U2N Relay UE#1.

[0403] Step 9: Switching from a single-hop indirect path to a 2-hop indirect path may also be performed. In this case, in Step 9a, the base station may perform an RRC Reconfiguration process to release information used by the U2N Relay UE#3 to serve the U2N Remote UE (e.g., Uu Relay RLC channel configuration and PC5 Relay RLC channel configuration for relaying signaling and / or data of the U2N Remote UE, and / or bearer mapping configuration, etc.). Step 9a may be performed at any time after Step 6. If the target U2N Relay UE#1 is switching to the same 3-hop indirect path as the U2N Relay UE#3, Step 9a may be omitted.

[0404] In Step 9b, U2N Relay UE#3 or U2N Remote UE can release the PC5 connection between U2N Relay UE#3 and U2N Remote UE. If Target U2N Relay UE#2 is switched to the same 2-hop indirect path as U2N Relay UE#3, Step 9b may be omitted.

[0405] Step 10: The U2N Remote UE can connect to the base station via U2N Relay UE#1 and U2N Relay UE#2. Therefore, UL / DL data can be transmitted via U2N Relay UE#1 and U2N Relay UE#2.

[0406] In the second example of the disclosure of this specification, an example of Intra-DU path switching is described in which U2N Relay UE#1, U2N Relay UE#2, and U2N Relay UE#3 are connected to a gNB-CU via the same gNB-DU. However, this is merely an example, and the second example of the disclosure of this specification may also be applied to an Inter-DU case in which U2N Relay UE#1 and U2N Relay UE#2 are connected to a gNB-CU via a different gNB-DU than U2N Relay UE#3. For example, in a situation where U2N Relay UE#3 is connected to gNB-DU#1, and U2N Relay UE#1 and U2N Relay UE#2 are connected via gNB-DU#2, since U2N Relay UE#1 and U2N Relay UE#2 are already in RRC_CONNECTED state, gNB-CU can know that U2N Relay UE#1 and U2N Relay UE#2 are connected via gNB-DU#2. Therefore, in Steps 3 and 4 of the second example of the disclosure of the present specification, gNB-CU can request gNB-DU#2 to allocate / set up PC5 / Uu Relay RLC channel, etc. for U2N Relay UE#1 and U2N Relay UE#2 through F1AP UE Context Modification procedure. In addition, gNB-CU can execute F1AP UE Context Setup procedure of U2N Remote UE towards gNB-DU#2 in Step 5. The gNB-CU executes Step 6 via gNB-DU#1, and the U2N Remote UE executes Step 8 via gNB-DU#2. For inter-DU path switching, the procedure in Clause 8.19.4.1 of TS 38.401 V18.1.0 can be referred to.

[0407] Unlike what is described in the examples of the first and / or second examples of the disclosure of this specification, the names related to the UEs may be used as follows. Considering the number of hops from the Remote UE, U2N Relay UE#3 may be referred to as a 1-hop U2N Relay UE (or the first U2N Relay UE or #1 U2N Relay UE or hop#1 U2N Relay UE). U2N Relay UE#2 may be referred to as a 2-hop U2N Relay UE (or the second U2N Relay UE or #2 U2N Relay UE or hop#2 U2N Relay UE). U2N Relay UE #1 may be referred to as a 3-hop U2N Relay UE (or the third U2N Relay UE or #3 U2N Relay UE or hop# U2N Relay UE or last hop U2N Relay UE).

[0408] 3. Application examples of the disclosure of this specification

[0409] Hereinafter, with reference to the example of FIG. 9, an example to which the first example and / or the second example of the disclosure of the present specification are applied is described.

[0410] The following drawings are intended to illustrate specific examples of the present specification. The names of specific devices and the names of specific signals, messages, and fields depicted in the drawings are provided for illustrative purposes only, and the technical features of this specification are not limited to the specific names used in the drawings.

[0411] FIG. 9 illustrates an example of a procedure according to one embodiment of the disclosure of the present specification.

[0412] For reference, the procedure illustrated in FIG. 9 is merely an example, and the scope of the disclosure of this specification is not limited by the example in FIG. 9.

[0413] For example, with respect to the example of FIG. 9, the operations described in the examples of FIGS. 1 to 8B may also be applied. For example, even if operations, contents, etc. are not directly described in the example of FIG. 9, operations, contents, etc. described in various examples of the disclosure of this specification may be applied. For example, the second relay UE, the first relay UE, and the base station may perform the operations described above with reference to FIGS. 6A to 8B.

[0414] In the example of FIG. 9, the base station may include a DU and a CU. For example, the DU may be a gNB-DU. The CU may be a gNB-CU.

[0415] Additionally, although the remote UE is not shown in the example of FIG. 9, the operations of the remote UE according to FIGS. 6a to 8b and / or the operations of the new remote UE may be performed.

[0416] In the example of FIG. 9, the second relay UE can access the base station via the first relay UE. The second relay UE can be connected to a remote UE (not shown in FIG. 9). The remote UE can be connected to the base station based on a multi-hop indirect path via the second relay UE and the first relay UE, through operations according to the example of FIG. 9.

[0417] Before step (S901) is performed, steps 1 to 3 of FIGS. 6A to 6C or steps 1 to 3 of FIGS. 7A to 7C may be performed. For example, the second relay UE may receive a first direct communication request message from a remote UE. The second relay UE may transmit a second direct communication request message to the first relay UE. The second relay UE may receive a second direct communication acceptance message from the first relay UE. The second relay UE may transmit a first direct communication acceptance message to the remote UE.

[0418] In some implementations, the second direct communication request message may include information regarding that the second relay UE has accessed the base station as a remote UE or information regarding that the second relay UE will access the base station as an intermediate relay UE.

[0419] In step (S901), the second relay UE may transmit a UE information message to the CU of the base station via the first relay UE and the DU of the base station. For example, the UE information message may be a sidelink UE information message (e.g., SidelinkUEInformaitonNR).

[0420] Before step (S901) is performed, the second relay UE may receive an RRC setup request message from the remote UE. The second relay UE may perform step (S901) based on receiving the RRC setup request message.

[0421] For example, the CU of the base station can receive a sidelink UE information message transmitted by the second relay UE through the first relay UE from the DU of the base station.

[0422] For example, the UE information message, the sidelink UE information message, may include one or more of an identity associated with the second relay UE, an identity associated with the first relay UE, and / or an identity associated with a remote UE. For example, the sidelink UE information message may include a destination identity for sidelink communication transmission of the second relay UE. For example, since the second relay UE performs sidelink communication with a remote UE and performs sidelink communication with the first relay UE, the sidelink UE information message may include an identity associated with the first relay UE (e.g., an L2 ID of the first relay UE) and an identity associated with the remote UE (e.g., an L2 ID of the remote UE) as destination identities.

[0423] In step (S902), the CU of the base station may transmit a request message related to the UE context to the DU of the base station. For example, the request message related to the UE context may be a UE context modification message or a UE context modification request message.

[0424] In some implementations, the request message related to the UE context may be a message related to the second relay UE. For example, the description related to step 7 of the examples of FIGS. 7A to 7C may apply to the request message related to the UE context of step (S902).

[0425] In some implementations, a request message related to a UE context may include information related to a first relay UE, or information related to a remote UE.

[0426] For example, information related to the first relay UE may be information related to the Layer 2 (L2) ID or upstream of the first relay UE. For example, information related to the remote UE may be information related to the L2 ID or downstream of the remote UE.

[0427] In some implementations, a request message related to the UE context may also be sent to the second relay to establish a relay RLC channel for transmitting SRB0 messages and / or SRB1 messages to the remote UE.

[0428] In some implementations, the request message related to the UE context may include PC5 control plane traffic type information including Signaling Radio Bearer (SRB)0 and / or SRB1.

[0429] In some implementations, the CU of the base station may determine, based on a sidelink UE information message, that the remote UE accessing the base station via the second relay UE accesses via the second relay UE, the first UE.

[0430] In some implementations, the CU of the base station may set the local ID of the remote UE. The CU of the base station may also transmit the local ID of the remote UE to the DU of the base station.

[0431] In some implementations, based on the CU of the base station transmitting the local ID of the remote UE to the DU of the base station, the DU of the base station may perform the following actions. For example, the DU of the base station may receive a Radio Resource Control (RRC) setup request message from the second relay UE. In this case, the DU of the base station may recognize, based on the local ID of the remote UE, that the remote UE accesses via the second relay UE and the first UE. For example, the descriptions related to steps 9 and 10 of FIGS. 7A to 7C may be applied.

[0432] According to one embodiment of the disclosure of the present specification, a gNB-CU can allocate / configure a Local ID for a U2N Remote UE on a per-UL / DL basis. The gNB-CU can notify nodes participating in multi-hop U2N relaying of the allocated / configured Local ID for the U2N Remote UE.

[0433] According to one embodiment of the disclosure of the present specification, for signaling and / or data transmission to a U2N Remote UE, a gNB-CU may allocate / configure egress PC5 / Uu Relay RLC channel configuration information for each Bearer per DL / UL (or per Peer UE) to an Intermediate U2N Relay UE (e.g., a 2-hop U2N Relay UE to an (n-1)-hop U2N Relay UE).

[0434] According to one embodiment of the disclosure of the present specification, an Intermediate U2N Relay UE (e.g., a 2-hop U2N Relay UE to an (n-1)-hop U2N Relay UE) may transmit to the gNB-CU an L2 ID used when the UE is connected to the network in the Remote UE role, so that the gNB-CU can know that a particular UE is participating in multi-hop U2N relaying for other Remote UEs as an Intermediate U2N Relay UE.

[0435] According to one embodiment of the disclosure of the present specification, an n-hop U2N Relay UE may transmit an RRCSetupRequest message of a U2N Remote UE to a gNB-DU. In this case, the n-hop U2N Relay UE may also transmit an indication to the gNB-DU, including in the SRAP header, that the U2N Remote UE has accessed the gNB-DU via multi-hop U2N relaying.

[0436] This specification may have various effects.

[0437] For example, in a multi-hop U2N relaying scenario, the gNB-CU may provide all U2N Relay UEs and gNB-DUs that have participated / involved in transmitting signaling and / or data of the U2N Remote UE with local ID information for the U2N Remote UE and mapping / routing information to the egress Uu / PC5 Relay RLC channel for each bearer. Accordingly, the signaling and / or data of the U2N Remote UE may be efficiently transmitted to the network, and / or the signaling and / or data from the network may be efficiently transmitted to the U2N Remote UE. In addition, for UL / DL data transmission of the U2N Remote UE, a PC5 Relay RLC channel for each PC5 connection may be effectively configured / allocated. Accordingly, transmission failure of UL / DL data for the U2N Remote UE may be prevented, and UL / DL data for the U2N Remote UE may be effectively transmitted.

[0438] The effects that can be achieved through the specific examples of this specification are not limited to the effects listed above. For example, a person with ordinary skill in the relevant technical field may understand or derive various technical effects from this specification. Accordingly, the specific effects of this specification are not limited to those explicitly described herein, but may include various effects that can be understood or derived from the technical features of this specification.

[0439] For reference, the operation of the terminal (e.g., UE, remote UE, relay UE, etc.) described in this specification can be implemented by the devices of FIGS. 1 to 3 described above. For example, the terminal (e.g., UE, remote UE, relay UE, etc.) can be the first device (100) or the second device (200) of FIG. 2. For example, the operation of the terminal (e.g., UE, remote UE, relay UE, etc.) described in this specification can be processed by one or more processors (102 or 202). The operation of the terminal described in this specification can be stored in one or more memories (104 or 204) in the form of instructions / programs (e.g., instructions, executable codes) executable by one or more processors (102 or 202). One or more processors (102 or 202) may control one or more memories (104 or 204) and one or more transceivers (105 or 206), and execute instructions / programs stored in one or more memories (104 or 204) to perform operations of a terminal (e.g., UE) described in the disclosure of this specification.

[0440] In addition, commands for performing operations of a terminal (e.g., UE, AIoT device, etc.) described in the disclosure of this specification may be stored in a non-volatile computer-readable storage medium. The storage medium may be included in one or more memories (104 or 204). In addition, the commands recorded in the storage medium may be executed by one or more processors (102 or 202) to perform operations of a terminal (e.g., UE, remote UE, relay UE, etc.) described in the disclosure of this specification.

[0441] For reference, the operations of a network node (e.g., AIoTF, AMF, SMF, UPF, PCF, NEF, UDM, DN, AF, etc.) or a base station (e.g., NG-RAN, gNB, gNB-DU, gNB-CU, DU, CU, CU-UP, CU-CP, etc.) described in this specification may be implemented by the devices of FIGS. 1 to 3 described below. For example, the network node or the base station may be the first device (100) or the second device (200) of FIG. 2. For example, the operations of the network node or the base station described in this specification may be processed by one or more processors (102 or 202). The operations of the terminal described in this specification may be stored in one or more memories (104 or 204) in the form of instructions / programs (e.g., instructions, executable codes) executable by one or more processors (102 or 202). One or more processors (102 or 202) may control one or more memories (104 or 204) and one or more transceivers (106 or 206), and execute instructions / programs stored in one or more memories (104 or 204) to perform operations of a network node or base station as described in the disclosure of this specification.

[0442] Additionally, the instructions for performing the operations of the network node or base station described in the disclosure of this specification may be stored in a non-volatile (or non-transitory) computer-readable storage medium having the instructions recorded thereon. The storage medium may be included in one or more memories (104 or 204). In addition, the instructions recorded in the storage medium may be executed by one or more processors (102 or 202) to perform the operations of the network node or base station described in the disclosure of this specification.

[0443] Although the preferred embodiments have been described above by way of example, the disclosure of this specification is not limited to such specific embodiments, and may be modified, changed, or improved in various forms within the scope described in the spirit and claims of this specification.

[0444] In the exemplary system described above, the methods are described based on a flowchart as a series of steps or blocks. However, the order of the steps described is not limited, and some steps may occur in a different order or simultaneously with other steps described above. Furthermore, those skilled in the art will understand that the steps depicted in the flowchart are not exclusive, and other steps may be included, or one or more steps in the flowchart may be deleted without affecting the scope of the invention.

[0445] The claims set forth in this specification may be combined in various ways. For example, the technical features of the method claims of this specification may be combined to implement a device, and the technical features of the device claims of this specification may be combined to implement a method. Furthermore, the technical features of the method claims and the technical features of the device claims of this specification may be combined to implement a device, and the technical features of the method claims and the technical features of the device claims of this specification may be combined to implement a method. Other implementations are within the scope of the claims.

Claims

1. A step in which a second relay User Equipment (UE) receives a sidelink UE information message transmitted through a first relay UE from a DU of a base station. The sidelink UE information message includes at least one of an identity associated with the second relay UE, an identity associated with the first relay UE, and / or an identity associated with a remote UE; and comprising a step of transmitting a request message related to a UE context to a DU of the base station, The request message related to the above UE context is related to the second relay UE, A method wherein a request message related to the UE context includes information related to the first relay UE or information related to a remote UE.

2. In paragraph 1, A method wherein a request message related to the UE context is transmitted to the second relay to set up a relay RLC channel for transmitting an SRB0 message and / or an SRB1 message to the remote UE.

3. In paragraph 1 or 2, The request message related to the above UE context is: A method comprising PC5 control plane traffic type information including Signaling Radio Bearer(SRB)0 and / or SRB1.

4. In any one of paragraphs 1 to 3, A method further comprising the step of determining that the remote UE accessing the base station through the second relay UE accesses the base station through the second relay UE and the first UE, based on the sidelink UE information message.

5. In any one of paragraphs 1 to 4, A step of setting a local ID of the above remote UE; and A method further comprising the step of transmitting the local ID of the remote UE to the DU of the base station.

6. In paragraph 5, A method in which the local ID of the remote UE is used to recognize that the remote UE accesses via the second relay UE and the first UE when the DU of the base station receives a Radio Resource Control (RRC) setup request message from the second relay UE.

7. In any one of paragraphs 1 to 6, Information related to the first relay UE is information related to the Layer 2 (L2) ID or upstream of the first relay UE, and A method in which the information related to the above remote UE is information related to the L2 ID or downstream of the above remote UE.

8. At least one transceiver; at least one processor; and comprising one or more memories capable of storing instructions and being operable to connect to at least one processor; A device wherein at least one processor is adapted to perform a method according to any one of claims 1 to 7.

9. A step in which a second relay User Equipment (UE) receives a Radio Resource Control (RRC) setup request message from a remote UE; and The second relay UE comprises a step of transmitting a sidelink UE information message to the base station via the first relay, The sidelink UE information message includes at least one of an identity associated with the second relay UE, an identity associated with the first relay UE, and / or an identity associated with a remote UE, and The sidelink UE information message is used by the CU of the base station to transmit a request message related to a UE context including information related to the first relay UE or information related to a remote UE to the DU of the base station.

10. In paragraph 9, A step in which a second relay UE receives a first direct communication request message from a remote UE; A step in which the second relay UE transmits a second direct communication request message to the first relay UE; A step in which the second relay UE receives a first direct communication acceptance message from the first relay UE; A method further comprising the step of the second relay UE transmitting a first direct communication acceptance message to the remote UE.

11. In paragraph 9 or 10, A method wherein the second direct communication request message includes information related to the second relay UE accessing the base station as a remote UE or information related to the second relay UE accessing the base station as an intermediate relay UE.

12. In any one of paragraphs 9 to 11, Information related to the first relay UE is information related to the Layer 2 (L2) ID or upstream of the first relay UE, and A method in which the information related to the above remote UE is information related to the L2 ID or downstream of the above remote UE.

13. At least one transceiver; at least one processor; and comprising one or more memories capable of storing instructions and being operable to connect to at least one processor; A device wherein at least one processor is adapted to perform a method according to any one of claims 9 to 12.

14. At least one processor; and At least one memory capable of storing instructions and being operable to connect to at least one processor, A device wherein at least one processor is adapted to perform a method according to any one of claims 9 to 12.

15. A non-transitory computer-readable storage medium that records commands, A CRM wherein the above instructions, when executed by at least one processor, cause the at least one processor to perform a method according to any one of claims 9 to 12.

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