WO2025174174A1 - Relay communication support - Google Patents

Abstract

One embodiment of the present specification provides a method. The method may comprise the steps of: transmitting an RRC setup request message to a base station through a first relay UE; receiving an RRC setup message from the base station through the first relay UE; receiving measurement configuration information related to communication between UEs from the base station through the first relay UE; and transmitting, to the first relay UE, measurement configuration information for each of a plurality of relay UEs including the first relay UE.

Description

Relay communication support

This specification relates to mobile communications.

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.

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. Furthermore, NR must be able to utilize any spectrum band up to at least 130 GHz, ensuring that it remains available for wireless communications well into the future.

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.

Prior art has lacked a method for effectively supporting UE-to-Network (U2N) relay, where a remote UE connects to a base station via a relay UE. For example, there is a problem in that relay communication cannot be effectively supported in multi-hop relay situations.

According to one embodiment of the present disclosure, a method is provided. The method may include the steps of: transmitting an RRC setup request message to a base station via a first relay UE; receiving an RRC setup message from the base station via the first relay UE; receiving measurement configuration information related to inter-UE communication from the base station via the first relay UE; and transmitting measurement configuration information for each of a plurality of relay UEs including the first relay UE to the first relay UE.

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

According to one embodiment of the present disclosure, a method is provided. The method may include the steps of: receiving an RRC setup request message from a remote UE via a plurality of relay UEs including a first relay UE; transmitting the RRC setup message to the remote UE via the plurality of relay UEs; transmitting measurement configuration information related to inter-UE communication to the remote UE via the plurality of relay UEs; and determining whether to switch a path of the first relay UE to a direct path, a multi-hop indirect path, or a single-hop indirect path based on a measurement result of the remote UE and a measurement result of each of the plurality of relay UEs.

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

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

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

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

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

Figure 5 illustrates an example of the architecture of a UE-to-Network Relay.

FIG. 6 is an example of a connection establishment procedure of a U2U remote UE according to one embodiment of the disclosure of the present specification.

Figure 7 illustrates an example of a UE-to-Network relay discovery procedure according to Model A.

Figure 8 illustrates an example of a UE-to-Network relay discovery procedure according to Model B.

Figures 9a and 9b illustrate an example of a procedure according to the first example of the disclosure of the present specification.

Figures 10a and 10b illustrate an example of a procedure according to the second example of the disclosure of the present specification.

Figure 11 shows an example of a procedure according to the third example of the disclosure of the present specification.

FIG. 12 illustrates an example of a procedure according to one embodiment of the disclosure of the present specification.

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). 3rd Generation Partnership Project (3GPP) Long-Term Evolution (LTE) is a subset of E-UMTS (Evolved UMTS) that uses E-UTRA. 3GPP LTE uses OFDMA in the downlink (DL) and SC-FDMA in the uplink (UL). Evolutions of 3GPP LTE include LTE-A (Advanced), LTE-A Pro, and/or 5G NR (New Radio).

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.

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.

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."

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."

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.”

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”.

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."

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

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).

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.

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

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.

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).

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.

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.

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.

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.

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).

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.

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.

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).

Frequency range definition Frequency range Subcarrier spacing FR1 450MHz - 6000MHz 15, 30, 60kHz FR2 24250MHz - 52600MHz 60, 120, 240kHz

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).

Frequency range definition Frequency range Subcarrier spacing FR1 410MHz - 7125MHz 15, 30, 60kHz FR2 24250MHz - 52600MHz 60, 120, 240kHz

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.

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

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.

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).

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).

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).

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.

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.

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).

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).

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).

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.

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.

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.

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, non-volatile memory, hard drive, register, cache memory, computer readable storage media and/or combinations thereof. The one or more memories (104, 204) may be located internally and/or externally to the one or more processors (102, 202). Additionally, the one or more memories (104, 204) may be coupled to the one or more processors (102, 202) via various technologies, such as wired or wireless connections.

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.

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).

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).

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.

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.

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

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

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

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).

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). Examples of processors (102) can be found in the SNAPDRAGON ^TM series processors made by Qualcomm®, the EXYNOS ^TM series processors made by Samsung®, the A series processors made by Apple®, the HELIO ^TM series processors made by MediaTek®, the ATOM ^TM series processors made by Intel®, or their corresponding next-generation processors.

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.

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.

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).

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).

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.

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).

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

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

- AUSF (Authentication Server Function)

-AMF (Access and Mobility Management Function)

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

- USDF (Unstructured Data Storage Function)

- NEF (Network Exposure Function)

- I-NEF (Intermediate NEF)

- NRF (Network Repository Function)

- NSSF (Network Slice Selection Function)

- PCF (Policy Control Function)

- SMF (Session Management Function)

-UDM (Unified Data Management)

-UDR (Unified Data Repository)

- UPF (User Plane Function)

- UCMF (UE radio Capability Management Function)

- AF (Application Function)

- UE (User Equipment)

- (R)AN ((Radio) Access Network)

- 5G-EIR (5G-Equipment Identity Register)

- NWDAF (Network Data Analytics Function)

- CHF (CHarging Function)

Additionally, the following network features may be considered:

- N3IWF (Non-3GPP InterWorking Function)

- TNGF (Trusted Non-3GPP Gateway Function)

- W-AGF (Wireline Access Gateway Function)

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.

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.

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.

The 5G system architecture includes the following benchmarks:

- N1: Reference point between UE and AMF.

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

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

- N4: Reference point between SMF and UPF.

- N6: Reference point between UPF and data network.

- N9: Reference point between two UPFs.

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

- N5: Reference point between PCF and AF.

- N7: Reference point between SMF and PCF.

- N8: Reference point between UDM and AMF.

- N10: Reference point between UDM and SMF.

- N11: Reference point between AMF and SMF.

- N12: Reference point between AMF and AUSF.

- N13: Reference point between UDM and AUSF.

- N14: Reference point between two AMFs.

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

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

- N22: Reference point between AMF and NSSF.

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

< UE-to-Network Relay >

Figure 5 illustrates an example of the architecture of a UE-to-Network Relay.

Referring to FIG. 5, UE-to-Network Relay supports network connection of a remote UE.

The PC5 link is the interface between the UE and the UE-to-network relay. The Uu link is the interface between the UE-to-network relay and the base station.

If the UE has established a PC5 link with a UE-to-network relay, the UE is considered a remote UE.

A UE-to-Network Relay entity can provide network connectivity for remote UEs. UE-to-Network Relay can be used for both public safety services and commercial services (e.g., interactive services).

When a UE (e.g., a remote UE) successfully establishes a PC5 link to a UE-to-Network Relay, the UE (e.g., a remote UE) may be considered a Remote UE for that particular UE-to-Network Relay. The Remote UE may be located within NG-RAN coverage or outside NG-RAN coverage.

A UE-to-Network Relay can relay unicast traffic (UL and DL traffic) between a remote UE and the network. A UE-to-Network Relay must provide a general function capable of relaying all IP traffic.

For unicast traffic between Remote UEs and UE-to-Network Relays, one-to-one direct communication can be used.

Referring to the example of Fig. 6, the connection establishment procedure for L2 U2U Remote UE is described.

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.

FIG. 6 is an example of a connection establishment procedure of a U2U remote UE according to one embodiment of the disclosure of the present specification.

Referring to the example of Fig. 6, an example of a control plane procedure for L2 U2U relay is described.

An L2 U2U remote UE must establish an end-to-end SL-SRB (Signaling Radio Bearer)/DRB (Data Radio Bearer) with its peer L2 U2U remote UE before transmitting user plane data.

For reference, in the disclosure of this specification, sidelink or SL is an example of terminal-to-terminal communication, and the scope of the disclosure of this specification is not limited by the terms sidelink or SL. For example, any other term related to terminal-to-terminal communication may be used instead of sidelink or SL in the disclosure of this specification.

The high-level connection establishment procedure illustrated in the example of Figure 6 can be applied to L2 U2U relay UEs and L2 U2U remote UEs:

1. A discovery procedure can be performed.

For example, an L2 U2U remote UE, an L2 U2U relay UE, and a peer L2 U2U remote UE perform a discovery procedure or an integrated discovery procedure.

2a. An L2 U2U remote UE can establish a PC5 connection with an L2 U2U relay UE. For example, an L2 U2U remote UE can establish/modify a PC5-RRC connection with a selected L2 U2U relay UE (e.g., as specified in TS 23.304 V18.0.0).

2a. An L2 U2U relay UE can establish a PC5 connection with a peer L2 remote relay UE. For example, an L2 U2U relay UE can establish/modify a PC5-RRC connection with a peer L2 U2U remote UE (e.g., as specified in TS 23.304 V18.0.0).

3. The U2U relay UE can assign local IDs to the U2U remote UE and the peer U2U remote UE via an RRC reconfiguration message (e.g., RRCReconfigurationSidelink). For example, the L2 U2U relay UE can assign two local IDs, which can be conveyed to each L2 U2U remote UE via an RRCReconfigurationSidelink message. For example, one local ID identifies the L2 U2U remote UE, and the other local ID identifies the peer L2 U2U remote UE. When the local IDs are conveyed, the L2 ID of the peer L2 U2U remote UE can also be conveyed to the U2U remote UE to create an association (e.g., association) between the local IDs and the L2 ID of the peer L2 U2U remote UE.

4. End-to-end PC5 connection establishment can be performed. For example, an L2 U2U remote UE can establish an end-to-end PC5-RRC connection with a peer L2 U2U remote UE via an L2 U2U relay UE. For end-to-end connection establishment, fixed indices (i.e., 0/1/2/3) are defined for end-to-end SL-SRB 0/1/2/3, respectively, and the designated PC5 Relay RLC channel configuration is used at each hop. Sidelink UE functions can be exchanged between L2 U2U remote UEs via PC5-RRC (e.g., SL-SRB3) messages.

5. L2 U2U remote UE can send information related to end-to-end QoS to relay UE. L2 U2U remote UE can send all QoS profiles for end-to-end QoS flow to L2 U2U relay UE via PC5-RRC.

6. L2 U2U relay UE can perform QoS split only for PDB.

7. U2U relay can transmit information related to split QoS to remote UE.

For example, an L2 U2U relay UE can send a segmented QoS value (i.e., PDB) to an L2 U2U remote UE via a PC5-RRC message.

8. End-to-end RRC reconfiguration related to terminal-to-terminal communication may be performed. For example, the L2 U2U remote UE or the serving gNB of the L2 U2U remote UE may derive PDCP and SDAP configurations for the end-to-end SL-DRB and provide some of the configurations related to reception to the peer L2 U2U remote UE using the end-to-end RRCRecfigurationSidelink message. The end-to-end bearer IDs for the SL-SRB and SL-DRB may be used as inputs for L2 U2U relay encryption and decryption in PDCP.

9a. RRC reconfiguration related to terminal-to-terminal communication may be performed. For example, the serving gNB of the L2 U2U remote UE or the L2 U2U remote UE may derive the first-hop configuration for the SL-DRB (e.g., PC5 relay RLC channel configuration) and provide the L2 U2U relay UE with the configuration related to reception on the first hop (i.e., Rx by the relay UE) using a hop-by-hop RRCReconfigurationSidelink message.

9b. RRC reconfiguration related to terminal-to-terminal communication may be performed. For example, the serving gNB of the L2 U2U relay UE or the L2 U2U relay UE derives the second-hop configuration (e.g., PC5 relay RLC channel configuration) for each SL-DRB and provides the configuration related to receiving data packets at the second hop (i.e., RX of the peer remote UE) to the peer L2 U2U Remote UE using the hop-by-hop RRCRecfigurationSidelink message.

For reference, in the example of FIG. 6, the first hop may be related between a U2U remote UE and a U2U relay UE, and the second hop may be related between a U2U relay UE and a peer U2U remote UE.

10. L2 U2U remote UE and peer L2 U2U remote UE can transmit and receive data through L2 U2U relay UE.

Describes an example of UE-to-network relay discovery.

UE-to-Network Relay Discovery is applicable to both Layer 3 and Layer 2 UE-to-Network Relay Discovery for public safety and commercial services. To perform 5G ProSe UE-to-Network Relay Discovery, remote UEs and UE-to-Network Relays can be pre-configured or provisioned with relevant information as described in 3GPP TS 23.304 V18.0.0 S5.1.

In UE-to-Network relay discovery, the UE can use preset or provisioned information for the relay discovery procedure.

A Relay Service Code (RSC) is used in UE-to-Network Relay discovery and indicates the connection service that a UE-to-Network Relay provides to a Remote UE. As defined in 3GPP TS 23.304 V18.4.0 S5.1.4, RSCs (including dedicated RSCs for emergency services) can be configured in the UE-to-Network Relay and the Remote UE. The UE-to-Network Relay and the Remote UE can be aware of whether an RSC provides Layer-2 or Layer-3 UE-to-Network Relay services and whether it is an RSC for emergency services, according to the policies specified in 3GPP TS 23.304 V18.4.0 S5.1.4. A UE-to-Network Relay that supports multiple RSCs can advertise the RSCs using multiple discovery messages, one RSC per discovery message.

Additional information not directly used for discovery may be advertised using the PC5-D protocol stack as a single or separate discovery message of type "Relay Discovery Additional Information" as defined in 3GPP TS 23.304 V18.4.0 S5.8.3.1.

Below, examples of the Model A discovery procedure and the Model B discovery procedure are described with reference to FIGS. 7 and 8.

For example, Model A may be a unidirectional discovery procedure. According to Model A, an "Announcing UE" may periodically broadcast a discovery message announcing its presence and available services. A "Monitoring UE" that receives this message can utilize this information to establish direct communication with the "Announcing UE."

For example, Model B may be a two-way discovery procedure. According to Model B, a "Discoverer UE" broadcasts a query message requesting a specific service, and the "Discoveree UE" that receives the message can announce its presence and service through a response message. Through this interaction, the Discoverer UE can locate a suitable Discoveree UE and establish direct communication.

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.

Figure 7 illustrates an example of a UE-to-Network relay discovery procedure according to Model A.

An example of a UE-to-Network relay discovery procedure using Model A is described. Figure 7 is an example of a UE-to-Network discovery procedure using Model A.

1. The UE-to-Network relay can send a UE-to-Network relay discovery announcement message. The UE-to-Network relay discovery announcement message can include a discovery message type, announcer information, and RSC. The UE-to-Network relay discovery announcement message can be sent based on the source layer-2 ID and the destination layer-2 ID.

For 5G Proximity based Services (ProSe) Layer 3 UE-to-Network relay, the Layer 3 UE-to-Network relay may include the RSC in the UE-to-Network relay discovery announcement message only if the S-NSSAI associated with the RSC belongs to the allowed NSSAIs of the UE-to-Network relay.

Remote UE1 to remote UE3 can determine a destination layer-2 ID for signal reception.

Remote UE1 to remote UE3 can monitor announcement messages based on the UE-to-Network RSC corresponding to the desired service.

Optionally, the 5G ProSe UE-to-Network Relay may also send a Relay Discovery Additional Information message as defined in 3GPP TS 23.304 V18.4.0 S6.5.1.3. The parameters included in this message and the source Layer-2 ID and destination Layer-2 ID used to send and receive the message are described in 3GPP TS 23.304 V18.4.0 Section 5.8.3.

The remote UE can select a UE-to-Network relay based on the information received in step 1.

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.

Figure 8 illustrates an example of a UE-to-Network relay discovery procedure according to Model B.

An example of a 5G ProSe UE-to-Network relay discovery procedure using Model B is described. FIG. 8 is an example of a 5G ProSe UE-to-Network relay discovery procedure using Model B.

1. A remote UE may send a UE-to-Network Relay Discovery Request message. The 5G ProSe UE-to-Network Discovery Request message includes a Discovery message type, discoverer information, an RSC, and optionally, target information, and may be sent using the source layer-2 ID and target layer-2 ID described in 3GPP TS 23.304 V18.4.0 S5.8.3. A remote UE that wishes to discover a 5G ProSe UE-to-Network Relay may send a request message including an RSC associated with the desired connection service. The RSC may be based on policies/parameters specified in 3GPP TS 23.304 V18.4.0 S5.1.4.1.

2. If the RSC included in the request message matches a (pre-)configured RSC of the 5G ProSe UE-to-network relay, and if there is target information included in the request message, and if the target information matches the 5G ProSe UE-to-network relay, the 5G ProSe UE-to-network relay (e.g., relay 1 and relay 2) may respond to the 5G ProSe remote UE with a UE-to-network relay discovery response message. The 5G ProSe UE-to-network relay discovery response message includes a discovery message type, discovery (discoveree) information, and RSC, and may be transmitted using a source layer-2 ID and a target layer-2 ID.

For Layer-3 UE-to-Network relays, a 5G ProSe UE-to-Network relay can respond to the matching RSC in the UE-to-Network Relay Discovery Request message only if the S-NSSAI associated with the RSC belongs to the allowed NSSAI of the 5G ProSe UE-to-Network relay.

The 5G ProSe remote UE can select a 5G ProSe UE-to-Network relay based on the information received in step 2.

Additional measures need to be discussed for 5GS to support ProSe (Proximity based Services).

For example, further 5G system enhancements to support proximity services need to be discussed. For example, ProSe needs to be enhanced to support multi-hop over the NR PC5 reference point. Multi-hop support is needed for UE-to-network relay and/or UE-to-UE relay.

Additionally, the following Wayforward (RP-233998, Way forward on SL Multi-hop Relay) and WID document (RP-241609) were approved. Accordingly, the RAN Working Group also needs to discuss additional measures to support ProSe (Proximity-based Services) in 5GS.

For example, NR SL multi-hop relay operation needs to be supported.

For example, in relation to NR SL multihop relay operation, one or more of the following needs to be discussed:

- For example, L2 U2N SL Relay (only single indirect U2N path via SL Relay UE is supported) needs to be discussed.

- For example, starting with specifying one additional hop relay (i.e. on top of Rel-18), expansion to two additional hop relays needs to be discussed.

- For example, a forward-compatible solution needs to be discussed to support two additional hop relays and allow for future expansion of additional relays.

Accordingly, a method to support service continuity in multi-hop UE-to-Network relaying is needed.

In the prior art, a method has been discussed to support U2N Relay, in which a Remote UE accesses a base station via a Relay UE to receive services. Furthermore, a method has been discussed to support Multi-path Relay, in which a Remote UE receives services from the network via a direct path using a Uu link with a base station and an indirect path using a PC5 link with a Relay UE. Furthermore, a method has been discussed to support U2U Relay, in which a Remote UE connects to another Remote UE via a Relay UE.

However, in the prior art, the relay-related scheme only considers a single hop situation, so there is a problem that the coverage extension of the remote UE is limited according to the prior art.

To address the limitation of expanding the coverage of remote UEs, multi-hop relaying, in which n relays can participate, is required. However, conventional technology lacks a method for effectively supporting multi-hop relaying.

For example, there is a problem that service continuity is not guaranteed in a multi-hop relay situation.

Accordingly, in a multi-hop relay situation, due to changes in PC5 link(s) and/or Uu link quality, it is necessary to provide service continuity to remote UEs based on path switching. For example, path switching may include switching from a multi-hop relay situation to a direct path or a single-hop indirect path, or vice versa. Various examples of methods for providing service continuity to remote UEs are described below.

According to various examples of this specification, path switching from a direct path or a single-hop indirect path to a multi-hop indirect path, or from a multi-hop indirect path to a direct path or a single-hop indirect path, may be supported. For example, a method for setting/assigning a measurement configuration to a U2N Remote UE to support path switching may be described.

For example, a U2N Remote UE can measure the link quality of each PC5 link through a discovery process or communication procedure with each U2N Relay UE involved in a multi-hop indirect path. The U2N Remote UE can report measurement results, including the measured link quality for each PC5 link, to the base station.

For example, the base station can decide to switch to a new multi-hop indirect path based on the measurement results. The base station can allocate/configure the information required to create a new multi-hop indirect path (e.g., mapping/routing information to the egress PC5/Uu Relay RLC channel for a specific bearer, PC5 Relay RLC channel configuration information, Local IDs for U2N Remote UE and Last hop U2N Relay, etc.). For reference, egress may refer to the direction going out from a node (e.g., a remote UE or a relay UE), and ingress may refer to the direction coming into a node (e.g., a remote UE or a relay UE). For example, the egress PC5/Uu Relay RLC channel may refer to an RLC channel used by a specific relay/remote UE on the transmitting side when transmitting a signal to another relay UE/remote UE.

In this specification, UE (User Equipment) and terminal are used as terms with the same meaning.

Also, 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. are used with the same meaning.

Additionally, Remote UE, 5G Remote UE, 5G ProSe Remote UE, U2N Remote UE, etc. are used as terms with the same meaning.

Additionally, a UE that is not a UE-to-Network Relay may be referred to as a Remote UE or simply as a UE.

In this specification, in order to provide network connection services to a Remote UE, a U2N Relay located on a path between a Remote UE and a U2N Relay directly connected to a base station may be referred to as an Intermediate U2N Relay.

According to various examples in this specification, the description related to U2N (UE-to-Network) Relay is written based on Layer-2 U2N Relay, but this is only an example. In other words, the description related to U2N Relay according to various examples in this specification can be applied to all types of UE-to-Network Relay (e.g., Layer-2 UE-to-Network Relay, Layer-3 UE-to-Network Relay).

Additionally, while various examples in this specification focus on U2N Relays, these are merely examples. For example, the sections described in various examples in this specification for the section between a U2N Remote UE and a U2N Relay located at the last hop (i.e., a U2N Relay directly connected to a base station) can also be applied to multi-hop UE-to-UE relay operations.

In this specification, PC5 connection may be used as a term with the same meaning as PC5 unicast link, Sidelink unicast link, unicast link, unicast connection, etc.

In this specification, unlike the prior art, the description focuses on the contents proposed in various examples of the disclosure of this specification, and the description of the same contents/operations as the prior art will be omitted. For example, with regard to ProSe-related operations and procedures, reference will basically be made to TS 23.304 V18.0.0, TS 24.554 V18.0.0, TS 33.536 V18.0.0, TS 33.503 V18.2.0, TS 38.300 V18.0.0, TS 38.401 V18.0.0, TS 38.331 V18.0.0, TS 38.351 V18.0.0, etc.

The method for supporting multi-hop UE-to-network relaying proposed in various examples of the disclosure of this specification may be composed of a combination of one or more of the operations/configurations/steps described below.

For the NG messages between AMF and NG-RAN described below, new NG messages may be defined and used for some NG messages. Additionally, for some RRC messages between NG-RAN and UE described below, new RRC messages may be defined and used.

In the procedures according to the various examples of the disclosure of this specification, certain steps may be performed concurrently/in parallel or may be performed in a reversed order.

The names of indications, parameters, and information suggested in various examples of the disclosure of this specification are examples, and the names of indications, parameters, and information may be interpreted as being replaced with other names for the proposed procedure/purpose/method.

For reference, in various examples disclosed herein, a remote UE may perform an RRC connection establishment procedure with a base station via a relay UE. For example, the remote UE may transmit an RRC setup request message via the relay UE and receive an RRC setup message from the base station via the relay UE.

1. First example of disclosure of this specification

In the first example of the disclosure of this specification, an example of path switching from a multi-hop indirect path to a direct path or a single-hop indirect path is described.

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

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.

Figures 9a and 9b illustrate an example of a procedure according to the first example of the disclosure of the present specification.

Referring to FIGS. 9a and 9b, an example of a procedure for path switching from a multi-hop indirect path to a direct path or a single-hop indirect path is described.

Step 0: Assume that the U2N Remote UE is connected to the base station via U2N Relay UE#1, U2N Relay UE#2, and U2N Relay UE#3. Therefore, the U2N Remote UE can transmit or receive UL/DL data via U2N Relay UE#1, U2N Relay UE#2, and U2N Relay UE#3.

Step 1: The base station (e.g., NG-RAN) can transmit measurement settings to the U2N remote UE. The U2N remote UE can perform measurements based on the measurement settings and report the measurement results to the base station.

For example, based on the measurement configuration set/allocated (Step 1a) by the base station (e.g., NG-RAN), the U2N Remote UE can perform measurement (Step 1b), and then report the measurement results to the base station (Step 1c).

Step 1 may include steps 1a to 1c. Steps 1a to 1c are described below.

Step 1a: The base station can set/assign a measurement configuration to the U2N Remote UE to support connected mode mobility of the U2N Remote UE. The base station can transmit the measurement configuration to the U2N Remote UE.

In step 1a, one or more of the following A to E may be used as a method to continuously check the link quality of the PC5 connection between the U2N Remote UE and the U2N Relay UE#1:

A. The base station of the U2N Remote UE can transmit the measurement configuration for relays (e.g., U2N Relay UE#2, U2N Relay UE#3) that are not directly connected to the base station to the remote UE. For example, the base station of the U2N Remote UE can configure/assign the measurement configuration for U2N Relay UE#2 and U2N Relay UE#3 together in the process of configuring/assigning the measurement configuration to the U2N Remote UE. For example, the base station can transmit the measurement configuration of U2N Relay UE#2 and the measurement configuration of U2N Relay UE#3 that it configures/assigns to the U2N Remote UE. Then, the U2N Remote UE can transmit the measurement configuration to each U2N Relay UE by transmitting an RRCReconfigurationSidelink message including the measurement configuration of U2N Relay UE#2 and the measurement configuration of U2N Relay UE#3. The remote UE can transmit the measurement configuration for the U2N Relay UE#2 through the U2N Relay UE#3. For example, when the U2N Remote UE transmits an RRCReconfigurationSidelink message including the measurement configuration of the U2N Relay UE#2 and the measurement configuration of the U2N Relay UE#3, the U2N Relay UE#3 can receive the measurement configuration of the U2N Relay UE#3 and transmit the measurement configuration of the U2N Relay UE#2 to the U2N Relay UE#2.

B. A U2N Remote UE can also directly configure/assign measurement configurations for relays that are not directly connected to a base station (e.g., U2N Relay UE#2, U2N Relay UE#3). For example, if a base station of a U2N Remote UE configures/assigns a measurement configuration to the U2N Remote UE, the U2N Remote UE can directly configure/assign a measurement configuration for U2N Relay UE#2 and a measurement configuration for U2N Relay UE#3 based on the measurement configuration. The U2N Remote UE can deliver the measurement configurations to each U2N Relay UE by transmitting an RRCReconfigurationSidelink message including the measurement configurations of U2N Relay UE#2 and U2N Relay UE#3. The Remote UE can deliver the measurement configuration for U2N Relay UE#2 through U2N Relay UE#3. For example, when a U2N Remote UE transmits an RRCReconfigurationSidelink message including the measurement settings of U2N Relay UE#2 and the measurement settings of U2N Relay UE#3, U2N Relay UE#3 can receive the measurement settings of U2N Relay UE#3 and transmit the measurement settings of U2N Relay UE#2 to U2N Relay UE#2.

C. U2N Relay UE#2 and/or U2N Relay UE#3 may be in RRC_CONNECTED state. In this case, U2N Relay UE#2 and/or U2N Relay UE#3 may receive measurement configurations through their respective base stations to which they are currently RRC connected. For example, each base station may allocate/configure measurement configurations for the PC5 connection between U2N Relay UE#3 and U2N Relay UE#2 (i.e., the second PC5 connection) and/or the PC5 connection between U2N Relay UE#2 and U2N Relay UE#1 (i.e., the third PC5 connection). In this case, U2N Relay UE#2 or U2N Relay UE#3 may forward some or all of the following information to the corresponding base station for the U2N Remote UE and U2N Relay UE#1 pair:

- i) Information related to the SL-SRB and/or SL-DRB currently allocated/created for the U2N Remote UE and U2N Relay UE#1 pair (e.g., Bearer ID, RLC Channel ID, etc.)

- ii) L2 IDs and/or Local IDs for the U2N Remote UE and U2N Relay UE#1 pair.

- iii) Information related to U2N Relay UEs located between the U2N Remote UE and U2N Relay UE#1 pair (e.g., L2 ID(s) for each U2N Relay UE(s), etc.)

D. For a U2N Relay UE#2 or U2N Relay UE#3 in RRC_IDLE or RRC_INACTIVE state, the base station of each U2N Relay UE#2 or U2N Relay UE#3 or the base station of the U2N Remote UE may transmit measurement configuration information via SIB. Or. The measurement configuration information may be (pre-)configured within the U2N Relay UE#2 or U2N Relay UE#3 in RRC_IDLE or RRC_INACTIVE state. Or, while the U2N Relay UE#2 or U2N Relay UE#3 is in RRC_CONNECTED state, the U2N Relay UE#2 or U2N Relay UE#3 may store the measurement configuration information most recently allocated by the base station, and then the U2N Relay UE#2 or U2N Relay UE#3 may continue to use the stored measurement configuration.

E. Instead of the Measurement configuration, the threshold configuration for operating as a U2N Relay UE as defined in TS 38.331 V18.0.0 may be used, for example, SL-RelayUE-Config and/or SL-RelayUE-ConfigU2U may be used. Alternatively, a separate threshold configuration may be defined for Multi-hop U2N Relay operation to distinguish it from the existing Single-hop U2U Relay operation or Single-hop U2N Relay operation. Below are examples of SL-RelayUE-Config and SL-RelayUE-ConfigU2U:

- SL-RelayUE-Config may contain configuration information of the NR sidelink U2N relay UE.

-- ASN1START
-- TAG-SL-RELAYUE-CONFIG-START

SL-RelayUE-Config-r17::= SEQUENCE {
threshHighRelay-r17 RSRP-Range OPTIONAL, -- Need R
threshLowRelay-r17 RSRP-Range OPTIONAL, -- Need R
hystMaxRelay-r17 Hysteresis OPTIONAL, -- Cond ThreshHighRelay
hystMinRelay-r17 Hysteresis OPTIONAL -- Cond ThreshLowRelay
}

-- TAG-SL-RELAYUE-CONFIG-STOP
-- ASN1STOP

Table 3 is an example of the SL-RelayUE-Config information element.

SL-RelayUE-ConfigU2U may contain configuration information of an NR sidelink U2U relay UE.

-- ASN1START
-- TAG-SL-RELAYUE-CONFIGU2U-START

SL-RelayUE-ConfigU2U-r18::= SEQUENCE {
sl-RSRP-Thresh-DiscConfig-r18 SL-RSRP-Range-r16 OPTIONAL, -- Need R
sl-hystMaxRelay-r18 Hysteresis OPTIONAL, -- Cond SL-RSRP-ThreshRelay
sd-RSRP-Thresh-DiscConfig-r18 SL-RSRP-Range-r16 OPTIONAL, -- Need R
sd-hystMaxRelay-r18 Hysteresis OPTIONAL -- Cond SD-RSRP-ThreshRelay
}

-- TAG-SL-RELAYUE-CONFIGU2U-STOP
-- ASN1STOP

Table 4 is an example of the SL-RelayUE-ConfigU2U information element.

Step 1b: U2N Remote UE can perform measurements. U2N Relay UE#2 and/or U2N Relay UE#3 can perform measurements.

For example, a U2N Remote UE can perform measurements for a direct path and measurements for an indirect path. For example, a U2N Remote UE can perform measurements for a Uu link (i.e., direct path) that can be directly connected to the Uu cell of the U2N Remote UE's serving base station and/or neighboring base stations, and measurements for a Uu/PC5 link(s) that can be connected to the U2N Remote UE's serving base station and/or neighboring base stations through neighboring U2N Relay UEs (i.e., indirect path).

Additionally, to continuously check the link quality of the PC5 connections between the U2N Remote UE and the U2N Relay UE#1, the U2N Relay UE#2 and/or the U2N Relay UE#3 may perform measurements. For example, the U2N Relay UE#2 and/or the U2N Relay UE#3 may perform measurements based on the Measurement configuration information obtained based on one or more of the methods A to E of Step 1a.

In Step 1b, measurements described in Step 1a-2 or Step 1b-2 of the examples of FIGS. 10a and 10b may be performed. For example, measurements may also be performed on multiple PC5 links involved in multi-hop relay operation for path switching to a multi-hop indirect path using multiple candidate U2N Relay UEs.

Step 1c: If one or more of the following events occur, the U2N Remote UE may notify the base station of the event and/or measurement result:

I) An event where the link quality for a Uu link (e.g., direct path) that can be directly connected to the Uu cell of the serving base station and/or surrounding base stations of the U2N Remote UE and/or the link quality for a Uu/PC5 link(s) that can be connected to the serving base station and/or surrounding base stations of the U2N Remote UE through surrounding U2N Relay UEs (e.g., indirect path) is greater than/higher/better than the threshold value in the measurement configuration.

II) An event where the link quality of the PC5 connections between the U2N Remote UE and the U2N Relay UE#1 is lower/lower/worse than the threshold value in the measurement configuration. For this, the U2N Relay UE#2 and/or the U2N Relay UE#3 may notify the U2N Remote UE of an event where the link quality of the PC5 connection between the U2N Relay UE#3 and the U2N Relay UE#2 (e.g., the second PC5 connection) and/or the PC5 connection between the U2N Relay UE#2 and the U2N Relay UE#1 (e.g., the third PC5 connection) falls below the threshold value in the measurement configuration via the RRCReconfigurationSidelink message. When the above event occurs, the U2N Relay UE#2 and/or the U2N Relay UE#3 may notify the U2N Remote UE of the identifier of the U2N Relay UE where the event occurred (e.g., L2 ID), information about the PC5 connection where the event occurred (e.g., ID for PC5 link, link quality, etc.). Alternatively, the U2N Relay UE#2 and/or the U2N Relay UE#3 may always notify the U2N Remote UE of the quality value for the PC5 link regardless of the event II). Alternatively, when the event II) occurs, the U2N Relay UE#2 and/or the U2N Relay UE#3 may directly notify the base station through the U2N Relay UE#1.

The measurement results reported by the U2N Remote UE to the base station may include one or more of the following (a) to (d):

(a) link quality of a Uu link (e.g., 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, etc.

(b) link quality for Uu/PC5 link(s) (i.e., indirect path) that can be connected to the serving base station of the U2N Remote UE and/or the surrounding base station through the 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 the identifier for the U2N Relay UE (e.g., L2 ID), etc.

(c) the ID of the PC5 link where the event II) occurred, the quality of the PC5 link, and/or the identifier for the U2N Relay UE where the event II) occurred (e.g., L2 ID);

(d) link quality of all PC5 links (i.e., 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);

Step 2: The base station (e.g., NG-RAN#1) can decide the path switching of the remote UE.

For example, the base station (e.g., NG-RAN#1) may decide to switch (e.g., intra-gNB path switching) the path of the U2N Remote UE to a direct path through the Uu cell of the base station (i.e., NG-RAN#1) or a single hop indirect path (e.g., an indirect path that can be connected to NG-RAN#1) through the Target U2N Relay UE based on the measurement results received in Step 1. For reference, in the examples of FIGS. 9a and 9b, the Target U2N Relay UE may be U2N Relay UE#1 to U2N Relay UE#3 that were involved in the multi-hop relay operation, or may be a new U2N Relay UE#4.

For another example, a base station (e.g., NG-RAN#1) may decide to switch the path of a U2N Remote UE to a direct path via a Uu cell of another base station (e.g., NG-RAN#2) located nearby or to a single hop indirect path via a Target U2N Relay UE (which may be connected to NG-RAN#2) (i.e., inter-gNB path switching). In this process, the Source NG-RAN (e.g., NG-RAN#1) may determine the path type (e.g., direct path or indirect path) that the U2N Remote UE should use to the Target NG-RAN (e.g., NG-RAN#2) and may transmit a HANDOVER REQUEST message including the path type to the Target NG-RAN. In case of switching to an indirect path, the Target NG-RAN may also determine whether to use a single hop indirect path or an n-hop indirect path during the process of selecting a Target U2N Relay. Alternatively, in the case of switching to an indirect path, the Source NG-RAN may decide whether to use a single-hop indirect path or an n-hop indirect path. During this process, the Source NG-RAN may also forward the measurement results received in Step 1 to the Target NG-RAN.

The examples in FIGS. 9a and 9b assume the case of intra-gNB path switching, and assume switching from a 3-hop indirect path to a direct path or a single hop indirect path.

Step 3: If the base station determines indirect path switching to the target U2N Relay UE in Step 2, and the target U2N Relay UE is in RRC_CONNECTED state, the base station may perform an RRC reconfiguration procedure with the target U2N Relay UE. For example, through the RRC Reconfiguration procedure, the base station may transmit information required for the target U2N Relay UE to serve the U2N Remote UE (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, bearer mapping configuration, etc.) to the target U2N Relay UE. If the target U2N Relay UE is in RRC_IDLE or RRC_INACTIVE state, the operation according to Step 3 may be performed in Step 6b.

The local ID for the U2N Remote UE may be newly allocated/configured by the base station, or the local ID allocated/configured by the base station or U2N Relay UE#1 to U2N Relay UE#3 during the process of setting up/assigning 3-hop relay operation (i.e., before Step 0) may be reused.

Step 4: The base station may transmit an RRCReconfiguration message containing path switching settings to the remote UE.

For example, the base station may transmit an RRCReconfiguration message containing information (e.g., path switch configuration) necessary to perform switching to a direct path or a single-hop indirect path to the U2N Remote UE via U2N Relay UE#1, U2N Relay UE#2, and U2N Relay UE#3. For example, the path switching configuration may include some or all of the following information i to ii:

i. In case of switching to direct path, Uu cell ID

ii. In case of switching to a single-hop indirect path, L2 ID of the target U2N Relay UE, serving cell ID of the target U2N Relay UE, local ID for the U2N Remote UE, PC5 Relay RLC channel configuration, bearer mapping configuration, etc.

For switching to a direct path, steps 5a and 6a may be performed.

For switching to a single-hop indirect path, steps 5b and 6b may be performed.

Step 5a: If switching to a direct path, the U2N Remote UE can perform random access to the base station via the Uu cell. For example, the U2N Remote UE can transmit a random access preamble to the base station. The base station can then transmit a response message related to the random access to the U2N Remote UE.

Step 6a: To finalize the path switching procedure, the U2N Remote UE may send an RRC Reconfiguration Complete (e.g., RRCReconfigurationComplete) message to the base station.

Step 5b: In case of switching to a single hop indirect path, the U2N Remote UE can create a PC5 connection with the Target U2N Relay UE or, if an existing PC5 connection with the Target U2N Relay UE exists, update the existing PC5 connection.

Step 6b: To finalize the path switching procedure, the U2N Remote UE can send an RRCReconfigurationComplete message to the base station through the Target U2N Relay UE.

Step 7: The base station can perform an RRC reconfiguration procedure with U2N Relay UE#1.

For example, the base station may perform an RRC Reconfiguration process to release information used by the U2N Relay UE#1 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, bearer mapping configuration, etc.). In the examples of FIGS. 9a and 9b, step 7 is illustrated as being performed after step 6a or step 6b, but this is merely an example. Step 7 may be performed at any point after step 4. If switching to a single-hop indirect path is performed and the target U2N Relay UE is U2N Relay UE#1, step 7 may be omitted.

Step 8: U2N Relay UE#1 or U2N Remote UE can release the PC5 connection between U2N Relay UE#1 and U2N Remote UE. If the target U2N Relay UE is U2N Relay UE#3 and switching to a single-hop indirect path is performed, Step 8 may be omitted. The PC5 connection may be released through signaling exchange between UEs or may be released locally. The description related to releasing the PC5 connection may be applied throughout this specification.

Step 9a: In the case of direct path switching (i.e., Step 9a), the U2N Remote UE can connect to the base station via the base station's Uu cell. Therefore, UL/DL data related to the U2N Remote UE can be transmitted to or received from the base station via the Uu cell.

Step 9b: In the case of indirect path switching (i.e., Step 9b), the U2N Remote UE can be connected to the base station via the Target U2N Relay UE. Therefore, UL/DL data related to the U2N Remote UE can be transmitted to or received from the base station via the Target U2N Relay UE.

2. Second example of disclosure of this specification

According to a second example of the disclosure of the present specification, path switching from a direct path (or a single-hop indirect path) to a multi-hop indirect path can be performed.

In the second example of the disclosure of this specification, the description or operation for U2N Relay UE#3 (i.e., 3-hop U2N Relay UE) can also be applied to U2N Relay UEs of 2-hop or more hops (i.e., intermediate UE-to-Network Relay UE).

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.

Figures 10a and 10b illustrate an example of a procedure according to the second example of the disclosure of the present specification.

The examples in FIGS. 10A and 10B are examples of procedures involved in route switching from a direct route (or a single-hop indirect route) to a multi-hop indirect route.

Step 0: In the case of a direct path (i.e., Step 0a), the U2N Remote UE can connect to the base station via the Uu cell of the base station. In this case, the U2N Remote UE can transmit or receive UL/DL data via the Uu cell. In the case of a single-hop indirect path (i.e., Step 0b), the U2N Remote UE can connect to the base station via U2N Relay UE#4. In this case, the U2N Remote UE can transmit or receive UL/DL data via U2N Relay UE#4.

Step 1: The base station can set/allocate the measurement configuration (Step 1a-1 or Step 1b-1). The U2N Remote UE can perform measurements (Step 1a-2 or Step 1b-2) based on the measurement configuration. The U2N Remote UE can report the measurement results to the base station (Step 1a-3 or Step 1b-3).

(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. The base station can transmit the measurement configuration to the U2N Remote UE.

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

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 multiple PC5 links involved in the multi-hop relay operation. The U2N Remote UE can obtain quality information for each PC5 link through the Multi-hop Relay Discovery or Multi-hop Relay Communication procedure that the U2N Remote UE has previously executed/performed. Alternatively, the U2N Remote UE can obtain quality information for each PC5 link through the currently created/formed U2U Relay communication or Multi-hop Relay Communication.

Alternatively, the U2N Remote UE can acquire quality information of each PC5 link by performing a relay discovery process for a new multi-hop relay operation, as shown in the example below. Relay discovery-related operations, such as those shown in the example below, may also be performed by the U2N Remote UE based on an explicit indication included in the measurement configuration of the base station. Alternatively, the U2N Remote UE may determine on its own whether to perform relay discovery-related operations based on the measurement configuration.

(Relay discovery with Model A) The procedure of Clause 6.3.2.4.2 of TS 23.304 V18.5.0 may be performed, or a separate Relay discovery with Model A procedure for multi-hop relay operation may be defined. The discovery procedure according to the example of Fig. 7 may also be performed.

For example, U2N Relay UE#2 identifies a U2N Relay UE located nearby (e.g., through a previously executed/performed Multi-hop Relay Discovery or Multi-hop Relay Communication procedure or through a Relay Discovery Announcement message transmitted by a nearby U2N Relay UE) and measures/measures the link quality on the PC5 link with the U2N Relay UE. In FIGS. 10A and 10B , U2N Relay UE#2 may transmit a Relay Discovery Announcement message including the L2 ID of the nearby relay UE and quality information of the PC5 link between the nearby relay and U2N Relay UE#2 to nearby U2N relay UEs (e.g., U2N Relay UE#1 and U2N Relay UE#3). For example, a relay discovery announcement message transmitted by a U2N relay UE may include an L2 ID of a U2N Relay UE#1 and/or an L2 ID of a U2N Relay UE#3, quality information of a PC5 link between a U2N Relay UE#1 and a U2N Relay UE#2, and/or quality information of a PC5 link to a U2N Relay UE#3. The U2N Relay UE#3 forwards a Relay Discovery Announcement message including identifiers (e.g., L2 IDs) of U2N Relay UE(s) located nearby, quality information of a PC5 link between the U2N Relay UE#3 and the corresponding U2N Relay UE, and information received from the U2N Relay UE#2 to neighboring nodes (e.g., other relay UEs and/or remote UEs). A U2N Remote UE may receive a Discovery Announcement message from a U2N Relay UE#3. Based on the Relay Discovery Announcement message transmitted by Relay UE#3, the U2N Remote UE can determine that the U2N Remote UE can connect to the base station through U2N Relay UE#1, U2N Relay UE#2, and U2N Relay UE#3, and can obtain current link quality information on each PC5 link. For the existing input parameters used/transmitted in the Relay discovery with Model A process, please refer to TS 23.304.

Additionally, the relay UE and/or remote UE may additionally exchange/transmit some or all of the following information during the discovery process.

A. U2N Relay UE lists base stations that can directly provide Uu link (or network connection service) and/or information indicating the current Uu link quality and/or availability of Uu link with the base station and/or information indicating that the UE can directly provide network connection service.

B. A list of base stations to which a U2N Relay UE can connect through an n-hop relay operation, but cannot directly provide a Uu link (or network connection service), and/or information indicating the current link quality of Uu/PC5 links involved in the n-hop relay operation to the base stations, and/or information indicating that the Uu link is unavailable, and/or information indicating that the UE cannot directly provide a network connection service, and/or information indicating that the UE can operate as an Intermediate U2N Relay UE.

Based on a request from a U2N Remote UE, or based on (pre-)configuration information present in each U2N Relay UE, or based on an indication transmitted by the base station (e.g., using SIB or via a dedicated RRC message), each U2N Relay UE may include the A information and/or the B information in the Relay Discovery Announcement message.

(Relay discovery with Model B) The procedure of Clause 6.3.2.4.3 of TS 23.304 may be performed, or a separate Relay discovery with Model B procedure for multi-hop relay operation may be defined. The discovery procedure according to the example of Fig. 8 may also be performed.

For example, a U2N Remote UE can send a Relay Discovery Solicitation message for a new multi-hop relay operation to U2N Relay UE#3. U2N Relay UE#3 can then send the Relay Discovery Solicitation message and the U2N Remote UE's request together to U2N Relay UE#2.

Afterwards, the U2N Relay UE#2 can transmit a Relay Discovery Solicitation message to the U2N Relay UE#1 and receive a Relay Discovery Response message from the U2N Relay UE#1. Then, the U2N Relay UE#2 can measure the link quality of the PC5 link between the U2N Relay UE#2 and the U2N Relay UE#1 and transmit a Relay Discovery Response message including the measurement result to the U2N Relay UE#3. The U2N Relay UE#3 can measure the link quality of the PC5 link between the U2N Relay UE#3 and the U2N Relay UE#2. Then, the Relay UE#3 can transmit to the U2N Remote UE the Relay Discovery Response message including the PC5 link quality information between the U2N Relay UE#3 and the U2N Relay UE#2 and the PC5 link quality information between the U2N Relay UE#2 and the U2N Relay UE#1.

For the existing input parameters used/transmitted in the Relay discovery with Model B process, please refer to TS 23.304.

Additionally, the relay UE and/or remote UE may additionally exchange/transmit some or all of the following information during the discovery process.

A. A list of base stations that a U2N Relay UE can directly provide a Uu link (or network connection service) to, and/or information indicating the current Uu link quality with the base stations and/or the availability of the Uu link and/or information indicating that the U2N Remote UE can directly provide a network connection service. A Relay Discovery Solicitation message containing information such as a list of base stations to which the U2N Remote UE wishes to connect via a multi-hop relay operation may be transmitted. In this case, each U2N Relay UE may also include an indication in the Relay Discovery Response message indicating whether it can provide a Uu link to the corresponding base station.

B. A list of base stations to which a U2N Relay UE can connect through n-hop relay operation, but cannot directly provide a Uu link (or network connection service), and/or current link quality of Uu/PC5 links involved in n-hop relay operation to the base stations, and/or information indicating that the Uu link is not available, and/or information indicating that the UE cannot directly provide a network connection service, and/or information indicating that the UE can operate as an Intermediate U2N Relay UE.

Based on a request from a U2N Remote UE, or based on (pre-)configuration information present in each U2N Relay UE, or based on an indication transmitted by the base station (e.g., using SIB or via a dedicated RRC message), each U2N Relay UE may include the A information and/or the B information in the Relay Discovery Announcement message.

(Step 1a-3 or Step 1b-3) If any or all of the following events occur, the U2N Remote UE may notify the base station of the events and/or measurement results:

I) If the U2N Remote UE is currently connected via a direct path, the link quality of the Uu link (i.e., direct path) that can be directly connected via the Uu cell of the U2N Remote UE's serving base station and/or surrounding base stations, excluding the current serving Uu cell, and/or the link quality of the Uu/PC5 link(s) that can be connected to the U2N Remote UE's serving base station and/or surrounding base stations via surrounding U2N Relay UEs (i.e., indirect path) is greater than/higher/better than the threshold value in the measurement configuration.

II) If the U2N Remote UE is currently connected via a direct path, and the Uu link quality via the current serving Uu cell is smaller/lower/worse than the threshold value in the measurement configuration.

III) If the U2N Remote UE is currently connected via an indirect path, the link quality for 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 link quality for 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) are greater than/higher/better than the threshold value in the measurement configuration.

IV) If the U2N Remote UE is currently connected via an indirect path, if 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.

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

A U2N Remote UE can report measurement results to the base station, including some or all of the following:

(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, etc.

(b) link quality to the serving base station of the U2N Remote UE and/or link quality for Uu/PC5 link(s) (i.e., indirect path) that can be connected to the surrounding base station through the current serving U2N Relay UE and/or surrounding U2N Relay UE, serving cell ID of the U2N Relay UE, gNB ID of the serving base station of the U2N Relay UE, and/or identifier for the U2N Relay UE (e.g., L2 ID), etc.

(c) Link quality of all PC5 links (i.e., 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). For link quality, the U2N Remote UE may only report values for some PC5 links to the base station.

Step 2: The base station (e.g., NG-RAN#1) may decide to switch the path of the U2N Remote UE to a 3-hop indirect path that can connect to NG-RAN#1 based on the measurement results received in Step 1 (i.e., intra-gNB path switching). In the examples of FIGS. 10a and 10b, the 3-hop indirect path may be an indirect path through Target U2N Relay UE#1, Target U2N Relay UE#2, and Target U2N Relay UE#3. Target U2N Relay UE#1, Target U2N Relay UE#2, or Target U2N Relay UE#3 may be U2N Relay UE#4 that was involved in the existing single-hop relay operation, or may be a new U2N Relay UE.

Alternatively, the base station (e.g., NG-RAN#1) may decide to switch the path of the U2N Remote UE to a 3-hop indirect path via Target U2N Relay UE#1, Target U2N Relay UE#2, and Target U2N Relay UE#3, which may connect to another base station (e.g., NG-RAN#2) located nearby (i.e., inter-gNB path switching). In this case, the Source NG-RAN (i.e., NG-RAN#1) may decide the path type (e.g., direct path or indirect path) that the U2N Remote UE should use to the Target NG-RAN (i.e., NG-RAN#2) and transmit a HANDOVER REQUEST message including the path type to the Remote UE.

When switching to an indirect path, the target NG-RAN may decide whether to use a single-hop indirect path or an n-hop indirect path during the process of selecting the target U2N Relay. Alternatively, the source NG-RAN may decide whether to use a single-hop indirect path or an n-hop indirect path. During this process, the source NG-RAN may also forward the measurement results received in Step 1 to the target NG-RAN.

In Figures 10a and 10b, the case of intra-gNB path switching is assumed, and switching from a direct path or a single-hop indirect path to a 3-hop indirect path is assumed.

Step 3: The base station can decide to switch the indirect path to a 3-hop indirect path through Target U2N Relay UE#1, Target U2N Relay UE#2, and Target U2N Relay UE#3 in Step 2. In this case, if Target U2N Relay UE#1 is in RRC_CONNECTED state, the base station can transfer the information required for Target U2N Relay UE#1 to serve U2N Remote UE (e.g., local ID and L2 ID for U2N Remote UE, Uu Relay RLC channel configuration and PC5 Relay RLC channel configuration for relaying signaling and/or data of U2N Remote UE, bearer mapping configuration, etc.) to Target U2N Relay UE#1 through RRC Reconfiguration process. If Target U2N Relay UE#1 is in RRC_IDLE or RRC_INACTIVE state, Step 3 can be performed in Step 6.

The local ID for the U2N Remote UE may be newly allocated/configured by the base station, or the local ID allocated/configured by the base station during the process of setting up/allocating single-hop relay operation (e.g., before Step 0b) may be reused. The local ID for the U2N Relay UE#1 may be allocated/configured by the base station and passed on to the U2N Relay UE#1, or may be allocated/configured by the U2N Remote UE, U2N Relay UE#1, U2N Relay UE#2, or U2N Relay UE#3 during Step 5.

Step 4: The base station may include the information (e.g., path switch configuration) required to switch to the 3-hop indirect path via Target U2N Relay UE#1, Target U2N Relay UE#2, and Target U2N Relay UE#3 in the RRCReconfiguration message and transmit it to the U2N Remote UE via the direct path (Step 4a) or via U2N Relay UE#4 (Step 4b). For example, the path switch configuration may include some or all of the following information:

i. Identifiers for U2N Relay UEs involved in 3-hop relay operation (e.g., L2 ID)

ii. Mapping/routing information to be used by U2N Remote UE, U2N Relay UE#3, U2N Relay UE#2, and U2N Relay UE#1 in each PC5 connection (e.g., first PC5 connection, second PC5 connection, third PC5 connection) between U2N Remote UE and U2N Relay UE#1, respectively. For example, the mapping/routing information may be information for mapping/routing each SRAP Data PDU belonging to an SRB and DRB to a specific egress PC5 Relay RLC channel. For example, this information 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.

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#3, U2N Relay UE#2, and U2N Relay UE#1, respectively, in each PC5 connection (i.e., first PC5 connection, second PC5 connection, third PC5 connection) between U2N Remote UE and U2N Relay UE#1.

iv. Local ID pair to be used in PC5 connection between U2N Remote UE and U2N Relay UE#1 (e.g., local ID for U2N Remote UE and local ID for U2N Relay UE#1 to be included in SRAP header). For the local ID information of the U2N Remote UE, the local ID allocated/configured by the base station in the process of configuring/allocating single-hop relay operation (e.g., before Step 0b) may be reused. Alternatively, the base station may newly allocate/configure the local ID information of the U2N Remote UE for 3-hop relay operation. The local ID for the U2N Relay UE#1 may be included in the path switch configuration if allocated/configured by the base station in Step 3, and the U2N Remote UE, U2N Relay UE#1, U2N Relay UE#2, or U2N Relay UE#3 may allocate/configure the path switch configuration in Step 5.

Information related to the Second PC5 connection and/or the Third PC5 connection may be received by the U2N Remote UE or the Target U2N Relay UE#1 in Step 3 or Step 4. The U2N Remote UE or the Target U2N Relay UE#1 may also transmit an RRCReconfigurationSidelink message containing information related to the Second PC5 connection and/or the Third PC5 connection to the Target U2N Relay UE#2 and/or the Target U2N Relay UE#3.

Step 5: U2N Remote UE can create an end-to-end PC5 connection with U2N Relay UE#1 via U2N Relay UE#3 and U2N Relay UE#2, or update an existing PC5 connection, using Clause 16.12.7 procedure of TS 38.300 V18.0.0 or based on a separately defined PC5 connection creation procedure for multi-hop relay.

Unlike the above examples, the PC5 unicast link may be formed between the U2N Remote UE and the U2N Relay UE in various ways. For example, the PC5 unicast link may be formed hop-by-hop (e.g., the U2N Remote UE and the U2N Relay UE#3 form a PC5 unicast link, the U2N Relay UE#3 and the U2N Relay UE#2 form a PC5 unicast link, the U2N Relay UE#2 and the U2N Relay UE#1 form a PC5 unicast link). In addition, the U2N Remote UE and the U2N Relay UE#1 may form an end-to-end PC5 unicast link. This can be applied throughout the present specification.

Step 6: To finalize the path switching procedure, the U2N Remote UE can send an RRCReconfigurationComplete message to the base station through U2N Relay UE#3, U2N Relay UE#2, and U2N Relay UE#1.

Note that steps 7a and 7b may be performed when switching from a single-hop indirect path to a multi-hop indirect path.

Step 7a: In case of switching from a single-hop indirect path to a 3-hop indirect path, the base station may perform an RRC Reconfiguration process to release information used by the U2N Relay UE#4 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, bearer mapping configuration, etc.). Step 7a may be executed at any time after Step 4. If the switching is to a 3-hop indirect path including the U2N Relay UE#4, Step 7a may be omitted.

Step 7b: U2N Relay UE#4 or U2N Remote UE can release the PC5 connection between U2N Relay UE#4 and U2N Remote UE. If the Target U2N Relay UE#3 of the 3-hop indirect path is the same as U2N Relay UE#4, Step 7b may be omitted.

Step 8: The U2N Remote UE can connect to the base station through U2N Relay UE#1, U2N Relay UE#2, and U2N Relay UE#3. Therefore, the U2N Remote UE can transmit UL/DL data to the base station or receive it from the base station through U2N Relay UE#1, U2N Relay UE#2, and U2N Relay UE#3.

3. Third example of disclosure of this specification

According to a third example of the disclosure of the present specification, path switching from a multi-hop indirect path to a multi-hop indirect path can be performed.

The description or operation of the third example of the disclosure of this specification for U2N Relay UE#3 (i.e., a 3-hop U2N Relay UE) may also be applied to a 2-hop or more hop U2N Relay UE (i.e., an intermediate UE-to-Network Relay UE).

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.

Figure 11 shows an example of a procedure according to the third example of the disclosure of the present specification.

Figure 11 is an example of a procedure involved in route switching from a multi-hop indirect route to a multi-hop indirect route.

Step 0~1: Can be performed in the same manner as steps 0~1 of Figs. 9a and 9b.

Step 2: The base station (e.g., NG-RAN#1) can decide to switch paths.

For example, the base station (e.g., NG-RAN#1) may decide to switch the path of the U2N Remote UE to an n-hop indirect path via n Target U2N Relay UEs (that can be connected to NG-RAN#1) based on the measurement results received in Step 1 (i.e., intra-gNB path switching). The Target U2N Relay UEs may be U2N Relay UE#1 to U2N Relay UE#3 that were involved in the multi-hop relay operation, or may be new U2N Relay UEs.

For another example, a base station (e.g., NG-RAN#1) may decide to switch the path of a U2N Remote UE to an n-hop indirect path via n Target U2N Relays that may be connected to other base stations (e.g., NG-RAN#2) located nearby (i.e., inter-gNB path switching). During this process, the Source NG-RAN (e.g., NG-RAN#1) may determine the path type (i.e., direct path or indirect path) that the U2N Remote UE should use to the Target NG-RAN (e.g., NG-RAN#2) and may transmit a HANDOVER REQUEST message including the path type to the Remote UE. In case of switching to an indirect path, the Target NG-RAN may also determine whether to use a single-hop indirect path or an n-hop indirect path during the process of selecting a Target U2N Relay. Alternatively, in the case of switching to an indirect path, the Source NG-RAN may decide whether to use a single-hop indirect path or an n-hop indirect path. During this process, the Source NG-RAN may also forward the measurement results received in Step 1 to the Target NG-RAN.

The example in Fig. 11 assumes the case of intra-gNB path switching, and assumes switching from a 3-hop indirect path to an n-hop indirect path.

Step 3: The base station may decide to indirect path switching to an n-hop indirect path through n Target U2N Relay UEs in Step 2. In this case, if the Target n-hop U2N Relay UE (e.g., a U2N Relay UE directly connected to the base station, or a Last hop U2N Relay UE) is in RRC_CONNECTED state, the base station may transmit information required for the n-hop U2N Relay UE to serve the U2N Remote UE to the Target n-hop U2N Relay UE through an RRC Reconfiguration process. For example, the information required for the n-hop U2N Relay UE to serve the U2N Remote UE may include the local ID and L2 ID for the U2N Remote UE, the Uu Relay RLC channel configuration and PC5 Relay RLC channel configuration for relaying signaling and/or data of the U2N Remote UE, the bearer mapping configuration, etc. If the target n-hop U2N Relay UE is RRC_IDLE or RRC_INACTIVE, step 3 can be performed in step 6.

The local ID for the U2N Remote UE may be newly allocated/configured by the base station, or the local ID allocated/configured by the base station during the process of setting up/assigning the 3-hop relay operation (e.g., before Step 0) may be reused. The local ID for the target n-hop U2N Relay UE may be allocated/configured by the base station and then transmitted to the target n-hop U2N Relay UE. Alternatively, during Step 5, either the U2N Remote UE or the target U2N Relay UE may allocate/configure the local ID for the target n-hop U2N Relay UE.

Step 4: It can be performed in the same manner as step 4 according to the examples of FIGS. 9a and 9b.

Step 5~6: Can be performed in the same manner as steps 5~6 according to the examples of FIG. 10a and FIG. 10b.

Step 7~8: Can be performed in the same manner as steps 7~8 according to the examples of FIGS. 9a and 9b.

Step 9: The U2N Remote UE connects to the base station via the Target U2N Relay UEs. Therefore, the U2N Remote UE can transmit UL/DL data to the base station or receive it from the base station via the Target U2N Relay UEs.

Unlike what was described in the first to third examples of the disclosure of the present specification, the name of the relay UE may be determined by considering the number of hops from the Remote UE. For example, 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).

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.

FIG. 12 illustrates an example of a procedure according to one embodiment of the disclosure of the present specification.

For reference, the procedure illustrated in FIG. 12 is merely an example, and the scope of the disclosure of this specification is not limited by the example in FIG. 12.

For example, with respect to the example of FIG. 12, the operations described in the examples of FIGS. 1 to 11 may also be applied. For example, even if operations, contents, etc. are not directly described in the example of FIG. 12, operations, contents, etc. described in various examples of the disclosure of this specification may be applied.

For reference, the example of FIG. 12 illustrates only the first relay UE among the relay UEs, but this is merely an example. A remote UE may connect to the base station via multiple UEs, including the first relay UE. For example, a remote UE may connect to the base station via the first relay UE, the second relay UE, and the third relay UE.

In the example below, a remote UE may be connected to a base station based on a multi-hop indirect path. In this case, communication between the remote UE and the base station may be performed via multiple relay UEs, including a first relay.

In step (S1201), the remote UE can transmit an RRC setup request message to the base station via the first relay UE.

In step (S1202), the base station can transmit an RRC setup message to the remote UE via the first relay UE.

In step (S1203), the base station can transmit the measurement settings to the remote UE via the first relay UE.

For example, the measurement settings may include measurement settings information related to inter-UE communication.

For example, the remote UE may perform measurements on the UE-to-UE connection between the first relay UE and the remote UE based on measurement configuration information related to the UE-to-UE communication.

For example, measurement configuration information related to inter-UE communication received from a base station may include measurement configuration information for each of a plurality of relay UEs including the first relay UE.

As another example, the remote UE may determine measurement configuration information for each of a plurality of relay UEs, including the first relay UE, based on measurement configuration information related to inter-UE communication received from the base station.

In step (S1204), the remote UE may transmit the measurement settings to the first relay UE.

For example, the measurement settings transmitted in step (S1204) may include measurement setting information for each of a plurality of relay UEs including the first relay UE.

For example, the remote UE may send an RRC reconfiguration sidelink message (e.g., an RRCReconfigurationSidelink message) containing the measurement settings to the first relay UE.

For example, a remote UE may receive, from a first relay UE, measurement results obtained by each of the plurality of relay UEs for measurements on UE-to-UE connections with one or more adjacent relay UEs.

For example, a remote UE may transmit measurement results obtained by each of a plurality of relay UEs for a connection between UEs with one or more adjacent relay UEs and measurement results for a connection between UEs with a first relay UE to the base station via the first relay UE.

For example, the base station may determine path switching of the remote UE based on measurement results received from the remote UE.

For example, the base station can determine whether to switch the path of the first relay UE to a direct path, a multi-hop indirect path, or a single-hop indirect path based on the measurement results of the remote UE and the measurement results of each of the plurality of relay UEs.

For example, if it is decided to switch to a single-hop indirect path, the base station can transmit to the target relay UE of the single-hop indirect path information necessary for the target relay UE to serve the remote UE.

For example, the remote UE may receive an RRC reset message from the base station via the first relay UE, the RRC reset message including a path switch configuration related to switching to a direct path, a path switch configuration related to switching to a multi-hop indirect path, or a path switch configuration related to switching to a single-hop indirect path.

According to one embodiment of the disclosure of the present specification, a base station can allocate/set information necessary to create/form a multi-hop indirect path during a path switching process and transmit it to nodes participating in multi-hop U2N relaying (e.g., remote UE, relay UE, etc.).

According to one embodiment of the disclosure of the present specification, a U2N Remote UE can report measurement results related to link quality information for each PC5 link involved in a multi-hop indirect path to a base station during a measurement process. Based on the measurement results, the base station can determine the path type (i.e., direct path, single-hop indirect path, or multi-hop indirect path) required to serve the U2N Remote UE.

This specification may have various effects.

For example, U2N relay can be effectively supported. For example, relay communication can be effectively supported in a multi-hop relay situation.

For example, path switching from a direct path or a single-hop indirect path to a multi-hop indirect path, or from a multi-hop indirect path to a direct path or a single-hop indirect path, can be efficiently supported. For example, to support path switching, measurement results related to each PC5 link can be provided/reported to the base station. Accordingly, signaling and/or data of a U2N Remote UE can be efficiently delivered to the network through a direct path, a single-hop indirect path, or a multi-hop indirect path, or can be delivered from the network to the U2N Remote UE.

For example, during a path switching process from a direct path or single-hop indirect path to a multi-hop indirect path, the base station can provide the U2N Remote UE with the information necessary to create/form a multi-hop indirect path in advance. Accordingly, the U2N Remote UE can quickly transmit UL/DL data to or receive UL/DL data from the base station.

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.

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.

In addition, commands for performing operations of a terminal (e.g., UE, remote UE, relay UE, U2N remote UE, U2N relay UE, etc.) described in the disclosure of this specification may be stored in a non-volatile computer-readable storage medium recording the commands. The storage medium may be included in one or more memories (104 or 204). In addition, 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.

For reference, the operations of a network node (e.g., AMF, SMF, UPF, PCF, NEF, UDM, DN, 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.

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.

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.

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.

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 (15)

A step of transmitting an RRC setup request message to a base station via a first relay User Equipment (UE); A step of receiving an RRC setup message from the base station via the first relay UE; A step of receiving measurement setting information related to communication between UEs from the base station via the first relay UE; and A method comprising the step of transmitting measurement setting information for each of a plurality of relay UEs including the first relay UE to the first relay UE. In the first paragraph, A method further comprising the step of receiving, from the first relay UE, a measurement result obtained by performing a measurement on a connection between UEs of each of the plurality of relay UEs and one or more adjacent relay UEs. In claim 1 or 2, A method further comprising a step of performing measurement on a connection between the UEs with the first relay UE based on measurement setting information related to the communication between the UEs. In any one of the first to third paragraphs, A method further comprising a step of transmitting, to the base station via the first relay UE, measurement results obtained by each of the plurality of relay UEs for a connection between UEs with one or more adjacent relay UEs and measurement results for a connection between UEs with the first relay UE. In any one of the first to fourth paragraphs, Measurement setting information for each of a plurality of relay UEs including the first relay UE is included in the measurement setting information related to communication between the UEs, or A method for determining measurement configuration information for each of a plurality of relay UEs including the first relay UE based on measurement configuration information related to communication between the UEs. In any one of the first to fifth paragraphs, A method further comprising the step of receiving, from the base station via the first relay UE, an RRC reset message including a path switch setting related to switching to a direct path, a path switch setting related to switching to a multi-hop indirect path, or a path switch setting related to switching to a single-hop indirect path. One or more transmitters and receivers; one or more processors; and comprising one or more memories capable of storing instructions and being operable to the one or more processors; A device wherein the operation performed based on the above command being executed by the one or more processors is a method according to any one of claims 1 to 6. one or more processors; and comprising one or more memories capable of storing instructions and being operable to the one or more processors; A device wherein the operation performed based on the command being executed by the one or more processors is a method according to any one of claims 1 to 7. A non-transitory computer-readable storage medium that records commands, A CRM wherein the above instructions, when executed by one or more processors, cause the one or more processors to perform a method according to any one of claims 1 to 7. A step of receiving an RRC setup request message from a remote UE via a plurality of relay UEs including a first relay UE; A step of transmitting an RRC setup message to the remote UE through the plurality of relay UEs; A step of transmitting measurement setting information related to communication between UEs to the remote UE through the plurality of relay UEs; and A method comprising a step of determining whether to switch the path of the first relay UE to a direct path, a multi-hop indirect path, or a single-hop indirect path based on the measurement results of the remote UE and the measurement results of each of the plurality of relay UEs. In Article 10, A method further comprising a step of receiving, from the remote UE via the plurality of relay UEs, measurement results obtained by each of the plurality of relay UEs for a connection between UEs with one or more adjacent relay UEs and measurement results for a connection between UEs with the first relay UE. In claim 10 or 11, A method wherein the measurement configuration information related to the communication between the UEs includes measurement configuration information for each of the plurality of relay UEs. In any one of the 10th to 12th clauses, A method further comprising the step of transmitting, to the target relay UE of the single-hop indirect path, information necessary for the target relay UE to serve the remote UE, if switching to the single-hop indirect path is determined. In any one of Articles 10 to 13, A method further comprising the step of transmitting an RRC reset message to the remote UE via the plurality of relay UEs, the RRC reset message including a path switch setting related to switching to the direct path, a path switch setting related to switching to the multi-hop indirect path, or a path switch setting related to switching to the single-hop indirect path. One or more transmitters and receivers; one or more processors; and comprising one or more memories capable of storing instructions and being operable to the one or more processors; A device wherein the operation performed based on the above command being executed by the one or more processors is a method according to any one of claims 10 or 14.