Method and apparatus for transmitting and receiving a wireless signal in a wireless communication system

Abstract

In the present invention, the apparatus performs a procedure for setting a direct path connected to a network, receives setting information for an indirect path between the apparatus and the network in an RRC (radio resource control) connection state in which the direct path is set, and receives a sidelink message from another apparatus set as a relay apparatus for the indirect path. Based on the failure information being included in the sidelink message from the other apparatus, the apparatus performs bearer suspension for a first bearer related to the indirect path.

Description

Technical Field

[0001] The present invention relates to a wireless communication system, and more particularly, to a method and apparatus for transmitting and receiving wireless signals.

Background Art

[0002] A wireless communication system is a multiple access system that shares available system resources (such as bandwidth, transmission power, etc.) to support communication with multiple users. Examples of multiple access systems include CDMA (code division multiple access) systems, FDMA (frequency division multiple access) systems, TDMA (time division multiple access) systems, OFDMA (orthogonal frequency division multiple access) systems, SC-FDMA (single carrier frequency division multiple access) systems, MC-FDMA (multi carrier frequency division multiple access) systems, and the like.

[0003] Sidelink (SL) refers to a communication method in which a direct link is established between terminals (User Equipment, UE) to directly exchange voice or data between the terminals without going through a base station (Base Station, BS). SL is one solution to solve the burden on the base station due to rapidly increasing data traffic.

[0004] V2X (vehicle-to-everything) refers to a communication technology that exchanges information with other vehicles, pedestrians, infrastructure, and other things through wireless communication. V2X is classified into four types, such as V2V (vehicle-to-vehicle), V2I (vehicle-to-infrastructure), V2N (vehicle-to-network), and V2P (vehicle-to-pedestrian). V2X communication is provided by the PC5 interface and / or the Uu interface.

[0005] On the other hand, as more communication devices require larger communication capacities, the need for improved mobile broadband communication compared to existing radio access technologies (RATs) is emerging. As a result, the design of communication systems considering services or terminals sensitive to reliability and latency is being discussed. The next-generation radio access technology considering enhanced mobile broadband communication, massive MTC, URLLC (Ultra-Reliable and Low Latency Communication), etc. is called new radio access technology (new radio) or NR (new radio). V2X (vehicle-to-everything) communication can also be supported in NR.

[0006] FIG. 1 is a diagram for explaining a comparison between V2X communication based on RAT prior to NR and V2X communication based on NR.

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

[0008] For example, CAM includes dynamic state information of a vehicle such as direction and speed, static vehicle data such as dimensions, external lighting status, basic vehicle information such as route details. For example, a terminal can broadcast CAM, and the delay of CAM is less than 100 ms. For example, when an emergency situation such as a vehicle breakdown or accident occurs, the terminal can generate and send DENM to other terminals. For example, all vehicles within the transmission range of the terminal can receive CAM and / or DENM. In this case, DENM has a higher priority than CAM.

[0009] Subsequently, in relation to V2X communication, various V2X scenarios are defined in NR. For example, various V2X scenarios include vehicle platooning, advanced driving, extended sensors, remote driving, etc.

[0010] For example, based on vehicle platooning, vehicles dynamically form a group and move together. For example, in order to perform platoon operations based on vehicle platooning, vehicles belonging to the above group receive periodic data from the leading vehicle. For example, vehicles belonging to the above group can use the periodic data to reduce or increase the inter-vehicle distance.

[0011] For example, based on improved driving, a vehicle is semi-automated or fully automated. Each vehicle can adjust trajectories or maneuvers based on data obtained from local sensors of neighboring vehicles and / or neighboring logical entities. For example, each vehicle can share driving intentions with neighboring vehicles.

[0012] For example, based on extended sensors, raw data, processed data, or live video data obtained by local sensors can be exchanged between vehicles, logical entities, pedestrian terminals, and / or V2X application servers. Thus, for example, a vehicle can recognize an environment that is better than the environment that can be sensed using its own sensors.

[0013] For example, based on remote driving, for a person who cannot drive or a remote vehicle located in a dangerous environment, a remote driver or V2X application can operate or control the remote vehicle. For example, when the route can be predicted, such as in public transportation, cloud computing-based driving is used for the operation or control of the remote vehicle. For example, access to a cloud-based back-end service platform is considered for remote driving.

[0014] On the other hand, solutions for specifying service requirements for various V2X scenarios such as platooning vehicles, improved driving, extended sensors, remote driving, etc. are being discussed in NR-based V2X communication. Summary of the Invention Problems to be Solved by the Invention

[0015] An object of the present invention is to provide a method for accurately and efficiently performing a wireless signal transmission and reception procedure and an apparatus therefor.

[0016] The technical problems to be solved by the present invention are not limited to the above technical problems, and other technical problems not mentioned will be clearly understandable to those with ordinary knowledge in the technical field to which the present invention belongs from the following description.

Means for Solving the Problems

[0017] According to one aspect of the present invention, in a wireless communication system, a method for a first UE (user equipment) to set a multi-radio communication path includes executing a procedure for setting a direct path connected to a network, receiving setting information for an indirect path between the first UE and the network in an RRC (radio resource control) connected state in which the direct path is set, and receiving a sidelink message from a second UE set as a relay UE for the indirect path. Based on the fact that failure information is included in the sidelink message from the second UE, the first UE performs a bearer suspension for a first bearer related to the indirect path.

[0018] Preferably, the failure information is related to a failure in setting the indirect path.

[0019] Preferably, the first bearer is an indirect bearer.

[0020] Preferably, the first bearer is a split bearer, and while the direct path of the first bearer is not suspended, the indirect path of the first bearer is suspended.

[0021] Preferably, the first UE performs an RRC reconfiguration procedure based on the failure information included in the sidelink message.

[0022] Preferably, the sidelink message is received directly from the second UE via a sidelink interface between the first UE and the second UE.

[0023] Preferably, the sidelink interface between the first UE and the second UE is released based on failure information included in the sidelink message.

[0024] Preferably, the sidelink message includes information indicating that the sidelink message is related to the multi-path configuration of the first UE.

[0025] Preferably, based on the failure information included in the sidelink message, the first UE reports the configuration failure for the indirect path to the network via the direct path.

[0026] Preferably, the first UE operates as a remote UE in the indirect path.

[0027] According to another aspect of the present invention, there is provided a computer-readable medium storing instructions that, when executed by a processor, cause the processor to perform the method described above.

[0028] According to another aspect of the present invention, there is provided a terminal configured to perform the method.

[0029] According to another aspect of the present invention, there is provided an apparatus for controlling a terminal configured to perform the method.

Advantages of the Invention

[0030] According to the present invention, the wireless signal transmission and reception procedure can be performed accurately and efficiently.

[0031] The effects that can be obtained from various examples of the present disclosure, and other effects not mentioned, will be clearly derived and understood by those having ordinary knowledge in the technical field to which the present invention pertains from the following description.

Brief Description of the Drawings

[0032]

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Embodiments for Carrying Out the Invention

[0033] A wireless communication system is a multiple access system that shares available system resources (such as bandwidth, transmission power, etc.) to support communication with multiple users. Examples of multiple access systems include CDMA (code division multiple access) systems, FDMA (frequency division multiple access) systems, TDMA (time division multiple access) systems, OFDMA (orthogonal frequency division multiple access) systems, SC-FDMA (single carrier frequency division multiple access) systems, MC-FDMA (multi carrier frequency division multiple access) systems, etc.

[0034] For background technology, terms, definitions, and abbreviations related to this invention, the following documents can be referred to.

[0035] 3GPP (Registered Trademark) LTE

[0036] - 3GPP TS 36.211: Physical channels and modulation

[0037] - 3GPP TS 36.212: Multiplexing and channel coding

[0038] - 3GPP TS 36.213: Physical layer procedures

[0039] - 3GPP TS 36.214: Physical layer; Measurements

[0040] - 3GPP TS 36.300: Overall description

[0041] - 3GPP TS 36.304: User Equipment (UE) procedures in idle mode

[0042] - 3GPP TS 36.314: Layer 2 - Measurements

[0043] - 3GPP TS 36.321: Medium Access Control (MAC) protocol

[0044] - 3GPP TS 36.322: Radio Link Control (RLC) protocol

[0045] - 3GPP TS 36.323: Packet Data Convergence Protocol (PDCP)

[0046] - 3GPP TS 36.331: Radio Resource Control (RRC) protocol

[0047] 3GPP NR

[0048] - 3GPP TS 38.211: Physical channels and modulation

[0049] - 3GPP TS 38.212: Multiplexing and channel coding

[0050] - 3GPP TS 38.213: Physical layer procedures for control

[0051] - 3GPP TS 38.214: Physical layer procedures for data

[0052] - 3GPP TS 38.215: Physical layer measurements

[0053] - 3GPP TS 38.300: Overall description

[0054] - 3GPP TS 38.304: User Equipment (UE) procedures in idle mode and in RRC inactive state

[0055] - 3GPP TS 38.321: Medium Access Control (MAC) protocol

[0056] - 3GPP TS 38.322: Radio Link Control (RLC) protocol

[0057] - 3GPP TS 38.323: Packet Data Convergence Protocol (PDCP)

[0058] - 3GPP TS 38.331: Radio Resource Control (RRC) protocol

[0059] - 3GPP TS 37.324: Service Data Adaptation Protocol (SDAP)

[0060] - 3GPP TS 37.340: Multi-connectivity; Overall description

[0061] Sidelink (SL) refers to a communication method in which a direct link is established between user equipment (UE) terminals, and voice or data is directly exchanged between the terminals without going through a base station (BS). Sidelink is one solution to address the burden on the base station due to the rapidly increasing data traffic.

[0062] V2X (vehicle-to-everything) means a communication technology that exchanges information with other vehicles, pedestrians, infrastructure, and other things through wired or wireless communication. V2X is classified into four types such as V2V (vehicle-to-vehicle), V2I (vehicle-to-infrastructure), V2N (vehicle-to-network), and V2P (vehicle-to-pedestrian). V2X communication is provided by the PC5 interface and / or the Uu interface.

[0063] On the one hand, as more communication devices require greater communication capacity, the need for mobile broadband communication that is improved compared to existing radio access technologies (RATs) is emerging. Accordingly, communication systems that take into account services or terminals sensitive to reliability and latency are being discussed. Next-generation radio access technologies that consider enhanced mobile broadband communication, massive MTC, Ultra-Reliable and Low Latency Communication (URLLC), etc. are called new radio access technology (new RAT) or NR (new radio). V2X (vehicle-to-everything) communication can also be supported in NR.

[0064] The following technologies can be used in various radio access systems such as CDMA (Code Division Multiple Access), FDMA (Frequency Division Multiple Access), TDMA (Time Division Multiple Access), OFDMA (Orthogonal Frequency Division Multiple Access), SC-FDMA (Single Carrier Frequency Division Multiple Access), etc. CDMA can be implemented by radio technologies such as UTRA (Universal Terrestrial Radio Access) and CDMA2000. TDMA can be implemented by radio technologies such as GSM (Global System for Mobile communications) / GPRS (General Packet Radio Service) / EDGE (Enhanced Data Rates for GSM Evolution). OFDMA can be implemented by radio technologies such as IEEE802.11 (Wi-Fi), IEEE802.16 (WiMAX), IEEE802-20, E-UTRA (Evolved UTRA), etc. IEEE 802.16m is an evolution of IEEE 802.16e and provides backward compatibility with systems based on IEEE 802.16e. UTRA is part of UMTS (Universal Mobile Telecommunications System). 3GPP (3rd Generation Partnership Project) LTE (long term evolution) is part of E-UMTS (Evolved UMTS) that uses E-UTRA, adopts OFDMA in the downlink, and adopts SC-FDMA in the uplink. LTE-A (Advanced) is an evolution of 3GPP LTE.

[0065] 5G NR is a technology that follows LTE-A and is a new clean-slate mobile communication system with characteristics such as high performance, low latency, and high availability. 5G NR can utilize all available spectrum resources, such as low-frequency bands below 1 GHz, intermediate-frequency bands from 1 GHz to 10 GHz, and high-frequency (millimeter-wave) bands above 24 GHz.

[0066] For a clearer explanation, the description will be centered around LTE-A or 5G NR, but the technical idea according to an embodiment of the present invention is not limited to these.

[0067] Figure 2 shows the structure of an LTE system according to an embodiment of the present invention. This is also called E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network), or an LTE (Long Term Evolution) / LTE-A system.

[0068] Referring to Figure 2, E-UTRAN includes a base station 20 that provides a control plane and a user plane to the terminal 10. The terminal 10 can be fixed or mobile and is also called by terms such as MS (mobile station), UT (user terminal), SS (Subscriber station), MT (mobile terminal), and wireless device. Generally, the base station 20 is a fixed station that communicates with the terminal 10 and is also called by applications such as eNB (evolved NodE-B), BTS (base transceiver system), and AP (access point).

[0069] The base stations 20 are connected to each other through the X2 interface. The base station 20 is connected to the EPC (evolved Packet core, 30) through the S1 interface, more specifically, connected to the MME (mobility management entity) through S1-MME and to the S-GW (Serving gateway) through S1-U.

[0070] EPC30 is composed of an MME, an S-GW, and a P-GW (Packet data network-gateway). The MME has access information of the terminal and information regarding the capabilities of the terminal, and such information is mainly used for the mobility management of the terminal. The S-GW is a gateway with the E-UTRAN as an endpoint, and the P-GW is a gateway with the PDN (Packet Date Network) as an endpoint.

[0071] The radio interface protocol layers between the terminal and the network are classified into a first layer (L1), a second layer (L2), and a third layer (L3) based on the lower three layers of the well-known Open System Interconnection (OSI) reference model in a communication system. Among them, the physical layer belonging to the first layer provides an information transmission service using a physical channel, and the RRC (Radio Resource Control) layer belonging to the third layer controls radio resources between the terminal and the network. For this purpose, the RRC layer exchanges RRC messages between the terminal and the base station.

[0072] Figure 3 shows the structure of the NR system.

[0073] Referring to Figure 3, the NG-RAN (Next Generation-Radio Access Network) includes a gNB (next generation-Node BF cell) and / or an eNB that provide user plane and control plane protocol termination to the terminal. The case where only the gNB is included is illustrated in Figure 7. The gNB and the eNB are connected to each other by an Xn interface. The gNB and the eNB are connected to the fifth-generation core network (5G Core Network: 5GC) by an NG interface. More specifically, the AMF (access and mobility management function) is connected by an NG-C interface, and the UPF (user plane function) is connected by an NG-U interface.

[0074] Fig. 4 shows the structure of an NR radio frame.

[0075] Referring to Fig. 4, in NR, radio frames are used for uplink and downlink transmissions. The radio frame has a length of 10 ms and is defined by two 5-ms half-frames (HF). A half-frame contains five 1-ms subframes (SF). A subframe is divided into one or more slots, and the number of slots in a subframe depends on the subcarrier spacing (SCS). Each slot contains 12 or 14 OFDM(A) symbols with a cyclic prefix (CP).

[0076] When normal CP is used, each slot contains 14 symbols. When extended CP is used, each slot contains 12 symbols. Here, the symbol includes an OFDM symbol (or CP-OFDM symbol), an SC-FDMA symbol (or DFT-s-OFDM symbol).

[0077] Table 1 exemplifies the number of symbols per slot (N slot symbol ), the number of slots per frame (N frame,u slot ), and the number of slots per subframe (N subframe,u slot ) according to the SCS setting (μ) when normal CP is used.

[0078]

Table 1

[0079] Table 2 exemplifies the number of symbols per slot, the number of slots per frame, and the number of slots per subframe according to the SCS when extended CP is used.

[0080]

Table 2

[0081] In the NR system, the OFDM(A) numerology (e.g., SCS, CP length, etc.) can be set to be different among a plurality of cells merged into one terminal. As a result, the (absolute time) intervals of time resources (e.g., subframes, slots or TTIs) (for convenience, commonly referred to as TUs (Time Unit)) composed of the same number of symbols are set to be different among the merged cells.

[0082] In NR, a number of numerologies or SCSs are supported to support various 5G services. For example, when the SCS is 15 kHz, a wide area in a traditional cellular band is supported. When the SCS is 30 kHz / 60 kHz, a dense-urban area, lower latency, and wider carrier bandwidth are supported. When the SCS is 60 kHz or higher, a bandwidth greater than 24.25 GHz is supported to overcome phase noise.

[0083] The NR frequency band is defined by two types of frequency ranges. The two types of frequency ranges are FR1 and FR2. The numerical values of the frequency ranges can be changed. For example, the two types of frequency ranges are as shown in Table 3 below. Among the frequency ranges used in the NR system, FR1 means "sub 6GHz range", and FR2 means "above 6GHz range", which is also called millimeter wave (mmW).

[0084]

Table 3

[0085] As described above, the numerical values in the frequency range of the NR system can be changed. For example, FR1 includes a band from 410 MHz to 7125 MHz as shown in Table 4 below. That is, FR1 includes a frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or higher. For example, the frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or higher included within FR1 includes an unlicensed band. The unlicensed band is used for various applications, for example, for communication for vehicles (e.g., autonomous driving).

[0086]

Table 4

[0087] Figure 5 is a diagram showing the slot structure of an NR frame.

[0088] Referring to Figure 5, a slot includes a plurality of symbols in the time domain. For example, in the case of normal CP, one slot includes 14 symbols, while in the case of extended CP, one slot includes 12 symbols. Or in the case of normal CP, one slot includes 7 symbols, while in the case of extended CP, one slot includes 6 symbols.

[0089] A carrier includes a plurality of subcarriers in the frequency domain. An RB (Resource Block) is defined as a plurality (e.g., 12) of consecutive subcarriers in the frequency domain. A BWP is defined as a plurality of consecutive (P)RBs ((Physical) Resource Blocks) in the frequency domain and corresponds to one numerology (e.g., SCS, CP length, etc.). A carrier includes a maximum of N (e.g., 5) BWPs. Data communication is performed with the activated BWP. Each element is referred to as a resource element (RE) in the resource grid, and one complex symbol can be mapped.

[0090] On one hand, the wireless interface between terminals or the wireless interface between a terminal and a network is composed of an L1 layer, an L2 layer, and an L3 layer. In various embodiments of the present invention, the L1 layer means the physical layer. The L2 layer means, for example, any one of a MAC layer, an RLC layer, a PDCP layer, and an SDAP layer. The L3 layer means, for example, an RRC layer.

[0091] Hereinafter, V2X or SL (sidelink) communication will be described.

[0092] FIG. 6 shows a radio protocol architecture for SL communication. More specifically, FIG. 6(a) shows the user plane protocol stack of NR, and FIG. 6(b) shows the control plane protocol stack of NR.

[0093] Hereinafter, the sidelink synchronization signal (SLSS) and synchronization information will be described.

[0094] The SLSS includes a PSSS (Primary Sidelink Synchronization Signal) and an SSSS (Secondary Sidelink Synchronization Signal) as SL-specific sequences. The PSSS is called S-PSS (Sidelink Primary Synchronization Signal), and the SSSS is called S-SSS (Sidelink Secondary Synchronization Signal). For example, length-127 M-sequences are used for the S-PSS, and length-127 Gold sequences are used for the S-SSS. For example, a terminal detects the first signal using the S-PSS and acquires synchronization. For example, a terminal acquires detailed synchronization using the S-PSS and the S-SSS and detects the synchronization signal ID.

[0095] The Physical Sidelink Broadcast Channel (PSBCH) is a (broadcast) channel on which the basic (system) information that a terminal should know first before SL signal transmission and reception is transmitted. For example, the basic information includes information about SLSS, duplex mode (DM), TDD UL / DL (Time Division Duplex Uplink / Downlink) configuration, information about resource pools, the type of application related to SLSS, subframe offset, broadcast information, etc. For example, in order to evaluate the performance of the PSBCH, in NR V2X, the payload size of the PSBCH is 56 bits including a 24-bit CRC.

[0096] S-PSS, S-SSS, and PSBCH are included in a block format (e.g., SL SS (Synchronization Signal) / PSBCH block, hereinafter, S-SSB (Sidelink-Synchronization Signal Block)) that supports periodic transmission. The S-SSB has the same numerology (i.e., SCS and CP length) as the PSCCH (Physical Sidelink Control Channel) / PSSCH (Physical Sidelink Shared Channel) within the carrier, and the transmission bandwidth is within the (pre-set) SL BWP (Sidelink BWP). For example, the bandwidth of the S-SSB is 11 Resource Blocks (RB). For example, the PSBCH spans 11 RB. Also, the frequency position of the S-SSB is (pre-set). Therefore, the terminal does not need to perform hypothesis detection in terms of frequency to discover the S-SSB on the carrier.

[0097] On the one hand, in the NR SL system, a plurality of numerologies with different SCSs and / or CP lengths are supported. At this time, as the SCS increases, the length of the time resource for the transmitting terminal to transmit the S-SSB becomes shorter. As a result, the coverage of the S-SSB decreases. Therefore, in order to ensure the coverage of the S-SSB, the transmitting terminal transmits one or more S-SSBs to the receiving terminal within one S-SSB transmission period according to the SCS. For example, the number of S-SSBs transmitted by the transmitting terminal to the receiving terminal within one S-SSB transmission period is pre-configured or configured in the transmitting terminal. For example, the S-SSB transmission period is 160 ms. For example, a 160-ms S-SSB transmission period is supported for all SCSs.

[0098] For example, when the SCS is 15 kHz in FR1, the transmitting terminal transmits one or two S-SSBs to the receiving terminal within one S-SSB transmission period. For example, when the SCS is 30 kHz in FR1, the transmitting terminal transmits one or two S-SSBs to the receiving terminal within one S-SSB transmission period. For example, when the SCS is 60 kHz in FR1, the transmitting terminal transmits one, two, or four S-SSBs to the receiving terminal within one S-SSB transmission period.

[0099] For example, when the SCS is 60 kHz in FR2, the transmitting terminal transmits one, two, four, eight, sixteen, or thirty-two S-SSBs to the receiving terminal within one S-SSB transmission period. For example, when the SCS is 120 kHz in FR2, the transmitting terminal transmits one, two, four, eight, sixteen, thirty-two, or sixty-four S-SSBs to the receiving terminal within one S-SSB transmission period.

[0100] On the one hand, when the SCS is 60 kHz, two types of CPs are supported. Also, depending on the CP type, the structure of the S-SSB transmitted by the transmitting terminal to the receiving terminal may be different. For example, the CP type is Normal CP (NCP) or Extended CP (ECP). Specifically, for example, when the CP type is NCP, the number of symbols for mapping the PSBCH in the S-SSB transmitted by the transmitting terminal is 9 or 8. On the other hand, for example, when the CP type is ECP, the number of symbols for mapping the PSBCH in the S-SSB transmitted by the transmitting terminal is 7 or 6. For example, the PSBCH is mapped to the first symbol in the S-SSB transmitted by the transmitting terminal. For example, the receiving terminal that receives the S-SSB performs an AGC (Automatic Gain Control) operation in the first symbol interval of the S-SSB.

[0101] FIG. 7 shows a terminal performing V2X or SL communication.

[0102] Referring to FIG. 7, in V2X or SL communication, the term "terminal" mainly means the user's terminal. However, when network equipment such as a base station transmits and receives signals according to the communication method between terminals, the base station may also be regarded as a kind of terminal. For example, terminal 1 is the first device 100, and terminal 2 is the second device 200.

[0103] For example, terminal 1 selects a resource unit corresponding to a specific resource in a resource pool that means a set of a series of resources. Also, terminal 1 transmits an SL signal using the resource unit. For example, terminal 2, which is a receiving terminal, has a resource pool set in which it can transmit a signal to terminal 1, and detects the signal of terminal 1 in the resource pool.

[0104] Here, when the terminal 1 is within the connection range of the base station, the base station notifies the terminal 1 of the resource pool. On the other hand, when the terminal 1 is outside the connection range of the base station, another terminal notifies the terminal 1 of the resource pool, or the terminal 1 uses a preset resource pool.

[0105] Generally, a resource pool consists of a plurality of resource units, and each terminal selects one or more resource units to use for its own SL signal transmission.

[0106] FIG. 8 shows resource units for V2X or SL communication.

[0107] Referring to FIG. 8, the entire frequency resource of the resource pool is divided into NF pieces, and the entire time resource of the resource pool is divided into NT pieces. Thus, a total of NF*NT resource units are defined within the resource pool. FIG. 8 shows an example in which the resource pool is repeated with a period of NT subframes.

[0108] As shown in FIG. 8, one resource unit (e.g., Unit #0) is shown periodically repeated. Alternatively, in order to obtain the effect of diversity in the time or frequency dimension, the index of the physical resource unit to which one logical resource unit is mapped may change in a pattern predetermined by time. In this structure of the resource unit, the resource pool means a set of resource units that can be used for transmission by a terminal attempting to transmit an SL signal.

[0109] The resource pool can be subdivided into several types. For example, according to the content of the SL signal transmitted from each resource pool, the resource pool can be classified as follows.

[0110] (1) Scheduling Assignment (SA) is a signal that includes information such as the position of resources used by a transmitting terminal for transmitting on the SL data channel, the MCS (Modulation and Coding Scheme) or MIMO (Multiple Input Multiple Output) transmission method required for demodulating other data channels, and TA (Timing Advance). SA can also be multiplexed and transmitted together with SL data on the same resource unit. In this case, the SA resource pool means the resource pool on which SA is multiplexed and transmitted together with SL data. SA is also called the SL control channel.

[0111] (2) The Physical Sidelink Shared Channel (PSSCH) is the resource pool used by a transmitting terminal for transmitting user data. If SA is multiplexed and transmitted together with SL data on the same resource unit, only the SL data channel in a form excluding SA information is transmitted from the resource pool for the SL data channel. In other words, the REs (Resource Elements) used for transmitting SA information on individual resource units within the SA resource pool can still be used for transmitting SL data in the resource pool of the SL data channel. For example, a transmitting terminal maps and transmits the PSSCH to consecutive PRBs.

[0112] (3) The discovery channel is the resource pool for a transmitting terminal to transmit information such as its own ID. This enables the transmitting terminal to allow adjacent terminals to discover it.

[0113] Even when the content of the aforementioned SL signal is the same, different resource pools can be used according to the attributes of the SL signal transmission and reception. As an example, even for the same SL data channel or discovery message, depending on the SL signal transmission timing determination method (for example, whether it is transmitted at the reception time of the synchronization reference signal, or transmitted by applying a certain timing advance to the reception time), the resource allocation method (for example, whether the base station designates the transmission resources of individual signals to individual transmission terminals, or whether individual transmission terminals themselves select individual signal transmission resources within the resource pool), the signal format (for example, the number of symbols occupied by each SL signal in one subframe, or the number of subframes used for the transmission of one SL signal), the signal strength from the base station, the transmission power strength of the SL terminal, etc., it may be divided into different resource pools.

[0114] SL DRX (sidelink discontinuous reception)

[0115] SL supports SL DRX for unicast, groupcast, and broadcast. Define similar parameters (on-duration, inactivity-timer, retransmission-timer, cycle) for SL as for Uu to determine the SL active time for SL DRX. During the SL active time, the terminal performs SCI monitoring for data reception (for example: two-stage SCI of PSCCH and PSSCH). During the SL DRX inactivity time, the terminal may skip SCI monitoring for data reception.

[0116] The actual parameters supported for each cast type (unicast, groupcast, broadcast) are specified in the following subsections.

[0117] The SL active time of the RX terminal includes the time when an applicable SL on-duration timer, SL inactivity timer, or SL retransmission timer is running (for one of unicast, groupcast, or broadcast). Also, the slots related to the known periodic transmissions of the TX terminal and the time when the terminal expects a CSI report associated with a CSI request (for unicast) are considered the SL active time of the RX terminal.

[0118] The TX terminal maintains a timer set corresponding to the SL DRX timer of the RX terminal for each source / destination L2 ID pair for unicast or each destination L2 ID for groupcast / broadcast. If there is data to be transmitted to one or more RX terminals with SL DRX set, the TX terminal selects resources considering the active time of the RX terminal determined by the timer maintained at itself.

[0119] In the case of unicast, SL DRX is set for each pair of source L2 ID and destination L2 ID.

[0120] The terminal maintains an SL DRX timer set for each direction for each pair of source L2 ID and destination L2 ID. For a source / destination L2 ID pair, the SL DRX setting for one direction can be negotiated between terminals in the AS layer. In the case of the SL DRX setting for each direction where one terminal is the TX terminal and the other is the RX terminal:

[0121] - The RX terminal can send assistance information including the desired on-duration timer, SL DRX start offset, and SL DRX period to the TX terminal, and all 2TX terminals can use this to determine the SL DRX setting for the RX terminal.

[0122] Regardless of whether support information is provided or not, a TX terminal in RRC_IDLE / RRC_INACTIVE / OOC, or a TX terminal in RRC_CONNECTED that uses mode 2 resource allocation determines the SL DRX configuration for the RX terminal. For a TX terminal in RRC_CONNECTED that uses mode 1 resource allocation, the SL DRX configuration for the RX terminal is determined by the serving base station of the TX terminal.

[0123] - The TX terminal sends the SL DRX configuration used by the RX terminal to the RX terminal.

[0124] - The RX terminal accepts or rejects the SL DRX configuration.

[0125] The basic SL DRX configuration (default SL DRX configuration) for groupcast / broadcast is used in the DCR message.

[0126] When the TX terminal is in RRC_CONNECTED, the TX terminal reports the received support information to the serving base station, and when it receives the SL DRX configuration in a dedicated RRC signal at the base station, it sends the SL DRX configuration to the RX terminal. When the RX terminal is in RRC_CONNECTED, the RX terminal reports the received SL DRX configuration to its serving base station, for example, for the alignment of the Uu configuration and the SL DRX configuration.

[0127] The SL on-duration timer, SL inactivity timer, SL HARQ RTT timer, and SL HARQ retransmission timer are supported in unicast. The SL HARQ RTT timer and SL HARQ retransmission timer are maintained for each SL process at the RX terminal. When the SCI indicates two or more transmission resources, in addition to the (pre-)set value for each of these timers, the SL HARQ RTT timer value is derived from the retransmission resource timing.

[0128] The SL DRX MAC CE is introduced for SL DRX operation with unicast only.

[0129] In the case of groupcast / broadcast, the SL DRX is commonly configured among multiple terminals based on the QoS profile and the destination L2 ID. For each groupcast / broadcast, multiple SL DRX configurations can be supported.

[0130] For groupcast, the SL on-duration timer, SL inactivity timer, SL HARQ RTT timer, and SL retransmission timer are supported. For broadcast, only the SL on-duration timer is supported. The SL DRX period, SL on-duration, and (applicable only to groupcast) SL inactivity timer are set for each QoS profile. The start offset and slot offset of the SL DRX period are determined according to the destination L2 ID. The (applicable only to groupcast) SL HARQ RTT timer and the (applicable only to groupcast) SL HARQ retransmission timer are not set for each QoS profile or destination L2 ID. In the case of groupcast, the RX terminal maintains an SL inactivity timer for each destination L2 ID and selects the maximum SL inactivity timer value when multiple SL inactivity timer values associated with different QoS profiles are set for its L2 ID. In the case of groupcast and broadcast, when multiple QoS profiles are set for each destination L2 ID, the RX terminal maintains a single SL DRX period (selected as the minimum SL DRX period of all QoS profiles of that L2 ID) and a single SL on-duration (selected as the maximum SL on-duration of all QoS profiles of that L2 ID) for that L2 ID.

[0131] In the case of groupcast, the SL HARQ RTT timer and the SL retransmission timer are maintained at the RX terminal for each SL process. The SL HARQ RTT timer may be set to different values from each other so as to support both HARQ enabled transmission and HARQ disabled transmission.

[0132] A common basic SL DRX setting between groupcast and broadcast is used for QoS profiles that are not mapped to non-default SL DRX settings.

[0133] TX terminals and RX terminals within the coverage of RRC_IDLE / RRC_INACTIVE obtain their SL DRX settings in the SIB. (TX or RX) terminals in RRC_CONNECTED obtain the SL DRX settings in the SIB or from dedicated RRC signals during handover. In the case of out-of-coverage, the SL DRX settings are obtained by pre-configuration.

[0134] In the case of groupcast, when the TX terminal receives new data having the same destination L2 ID, it resumes its timer corresponding to the SL inactivity timer for the destination L2 ID (which is used to determine the allowed transmission time).

[0135] The TX profile is introduced to ensure compatibility for groupcast and broadcast transmissions between terminals that support / do not support the SL DRX function. The TX profile is provided from the upper layer to the AS layer and identifies one or more SL function groups. The TX terminal assumes SL DRX for the RX terminal only when the relevant TX profile corresponds to SL DRX support. The RX terminal determines that SL DRX is used when there is a relevant TX profile corresponding to SL DRX support for all destination L2 IDs of interest.

[0136] For unicast, groupcast, and broadcast, alignment of Uu DRX and SL DRX for RRC_CONNECTED terminals is supported. Alignment of Uu DRX and SL DRX is supported for the same terminal. Also, in mode 1 scheduling, alignment of the Uu DRX of the TX terminal and the SL DRX of the RX terminal is supported.

[0137] Alignment is performed with overall or partial time overlap between Uu DRX and SL DRX. In the case of an RRC_CONNECTED SL RX terminal, alignment is performed at the base station.

[0138] The SL DRX function that controls the SCI (i.e., one-stage SCI and two-stage SCI) monitoring activities of the terminal for unicast, groupcast, and broadcast is set by RRC to the MAC entity. When using the SL DRX operation, the MAC entity also needs to monitor the SCI (i.e., one-stage SCI and two-stage SCI) according to the requirements in other sections of the present invention.

[0139] RRC sets the following parameters to control the SL DRX operation.

[0140] - sl-drx-onDurationTimer: Duration at the start of the SL DRX cycle

[0141] - sl-drx-SlotOffset: Delay time before the start of sl-drx-onDurationTimer

[0142] - sl-drx-InactivityTimer (excluding broadcast transmissions): Period after the first slot of receiving an SCI (i.e., one-stage SCI and two-stage SCI) indicating a new SL transmission for the MAC entity

[0143] - sl-drx-RetransmissionTimer (per SL process excluding broadcast transmissions): Maximum period until receiving an SL retransmission

[0144] - sl-drx-StartOffset: The slot at which the SL DRX cycle starts

[0145] - sl-drx-Cycle: SL DRX cycle

[0146] - sl-drx-HARQ-RTT-Timer (per SL process excluding broadcast transmission): The minimum period before the MAC entity anticipates an SL HARQ retransmission

[0147] When SL DRX is configured, the active time includes the following times.

[0148] - The time when the sl-drx-onDurationTimer or sl-drx-InactivityTimer runs, or

[0149] - The time when the sl-drx-RetransmissionTimer runs, or

[0150] - When no SL-CSI report MAC CE is received, the sl-LatencyBoundCSI-Report interval set by RRC, or

[0151] - When an SL-CSI report MAC CE is received, the time between the SL-CSI report request transmission and the SL-SCI report MAC CE reception, or

[0152] - Slots related to the known periodic transmissions of terminals transmitting SL-SCH data.

[0153] When one or more SL DRXs are configured, the MAC entity performs the following.

[0154] 1> When multiple SL DRX periods mapped to multiple SL-QoS-Profile of destination Layer-2 ID and interest cast type are related to group cast and broadcast:

[0155] 2> Among multiple SL DRX periods mapped to multiple SL-QoS-Profile related to destination Layer-2 ID, select the sl-drx-Cycle with the shortest length.

[0156] 2> Among multiple SL DRX onduration timers mapped to multiple SL-QoS-Profile related to destination Layer-2 ID, select the sl-drx-onDurationTimer with the longest length.

[0157] 1> When the sl-drx-HARQ-RTT-Timer expires:

[0158] 2> If the data of the SL process is not successfully decoded or HARQ feedback (i.e., negative acknowledgment) is not unicast according to the UL / SL priority:

[0159] 3> After the sl-drx-HARQ-RTT-Timer expires, start the sl-drx-RetransmissionTimer for the SL process in the first slot.

[0160] When the cast type is group cast or broadcast as instructed by the upper layer, sl-drx-StartOffset and sl-drx-SlotOffset are derived from the following formula.

[0161] sl-drx-StartOffset (ms) = Destination Layer-2 ID modulo sl-drx-Cycle (ms).

[0162] sl-drx-SlotOffset (ms) = Destination Layer-2 ID modulo sl-drx-onDurationTimer (ms).

[0163] 1> When the SL DRX cycle is used and [(DFN Х 10) + subframe number] modulo (sl-drx-Cycle) = sl-drx-StartOffset:

[0164] 2> Start sl-drx-onDurationTimer after sl-drx-SlotOffset from the start of the subframe.

[0165] 1> When SL DRX is the active time:

[0166] 2> Monitor the SCI (i.e., one-stage SCI and two-stage SCI) in this SL DRX.

[0167] 2> When the SCI indicates a new SL transmission:

[0168] 3> When the source Layer-1 ID of the SCI is equal to the 8 LSBs of the intended destination Layer-2 ID, the destination Layer-1 ID of the SCI is equal to the 8 LSBs of the intended source Layer-2 ID, and the cast type indicator of the SCI is set to unicast:

[0169] 4> Start or resume sl-drx-InactivityTimer for the pair of its source Layer-2 ID and destination Layer-2 ID after the first slot of SCI reception.

[0170] 3> When the destination Layer-1 ID of the SCI (i.e., two-stage SCI) is equal to the 8 LSBs of the intended destination Layer-1 ID and the cast type indicator of the SCI is set to group cast:

[0171] 4> Select the sl-drx-InactivityTimer with the longest length among the multiple SL DRX inactivity timers mapped to the multiple SL-QoS-Profiles of the destination Layer-2 ID related to the destination Layer-1 ID of the SCI.

[0172] 4> After the first slot of SCI reception, start or resume the sl-drx-InactivityTimer for the destination Layer-2 ID.

[0173] 2> When the SCI indicates an SL transmission:

[0174] 3> When no PSFCH resources are configured for the SL grant related to the SCI:

[0175] 4> Start the sl-drx-HARQ-RTT-Timer for the SL process in the slot after the PSSCH (i.e., the currently received PSSCH) transmission ends.

[0176] 3> When PSFCH resources are configured for the SL grant related to the SCI:

[0177] 4> When HARQ feedback is activated by the SCI and the cast type indicator of the SCI is set to unicast; or, 4> When HARQ feedback is activated by the SCI, the cast type indicator of the SCI is set to groupcast, and positive-negative acknowledgment is selected;

[0178] 5> After the PSFCH transmission for transmitting the SL HARQ feedback ends, start the sl-drx-HARQ-RTT-Timer for the SL process in the first slot. Or

[0179] 5> When the SL HARQ feedback is not transmitted according to the UL / SL priority, after the PSFCH resource for the SL HARQ feedback ends, start the sl-drx-HARQ-RTT-Timer for that SL process in the first slot.

[0180] 4> When HARQ feedback is activated in the SCI, the cast type indicator of the SCI is set to group cast, and only negative-only acknowledgment is selected;

[0181] 5> After the PSFCH transmission for transmitting the SL HARQ feedback ends, start the sl-drx-HARQ-RTT-Timer for that SL process in the first slot. Or

[0182] 5> When the SL HARQ feedback is not transmitted according to the UL / SL priority, after the PSFCH resource for the SL HARQ feedback ends, start the sl-drx-HARQ-RTT-Timer for that SL process in the first slot. Or

[0183] 5> When the SL HARQ feedback is a positive acknowledgment, after the PSFCH resource for the SL HARQ feedback ends, start the sl-drx-HARQ-RTT-Timer for that SL process in the first slot.

[0184] 4> When the SCI deactivates the HARQ feedback and resources for one or more retransmission opportunities are not scheduled by the SCI:

[0185] 5> Start the sl-drx-HARQ-RTT-Timer for that SL process in the slot after the PSFCH resource ends.

[0186] 4> When HARQ feedback is deactivated in SCI and resources for one or more retransmission opportunities are scheduled by SCI:

[0187] 5> Start the sl-drx-HARQ-RTT-Timer for that SL process in the slot after the transmission of the PSSCH (i.e., the currently received PSSCH) has ended.

[0188] Reference: When the SCI indicates the next retransmission resource, the sl-drx-HARQ-RTT-Timer is derived from the retransmission resource timing (i.e., the next retransmission resource indicated by the SCI). The terminal uses the configured sl-drx-HARQ-RTT-Timer when the SCI does not indicate the next transmission resource.

[0189] 3> Abort the sl-drx-RetransmissionTimer for that SL process.

[0190] 1> When an SL DRX command MAC CE for a unicast source Layer-2 ID and destination Layer-2 ID pair is received:

[0191] 2> Abort the sl-drx-onDurationTimer for the unicast source Layer-2 ID and destination Layer-2 ID pair.

[0192] 2> Abort the sl-drx-InactivityTimer for the unicast source Layer-2 ID and destination Layer-2 ID pair.

[0193] Inter-UE Coordination (IUC)

[0194] The SL terminal supports inter-UE coordination (IUC) in mode 2. Here, terminal-A sends information about resources to terminal-B, and terminal-B uses this for resource (re)selection. The following inter-UE coordination methods are supported.

[0195] - IUC method 1. The adjustment information transmitted from terminal-A to terminal-B indicates the preferred and / or non-preferred resources for the transmission of terminal-B.

[0196] - IUC method 2. The adjustment information transmitted from terminal-A to terminal-B indicates the existence of expected / potential resource collisions for the resources indicated by the SCI of terminal-B.

[0197] In method 1, IUC can be triggered by an explicit request from terminal-B or the state of terminal-A. Terminal-A determines a set of resources reserved by other terminals or a set of slots that are not expected to receive SL from terminal-B when terminal-A is the intended receiver of terminal-B and terminal-A operates in half-duplex. Terminal-A uses this resource as a set of non-preferred resources or excludes this resource to determine a set of preferred resources, and transmits the preferred / non-preferred resources to terminal-B. The resources of terminal-B for (re)selection can be based on the detection result of terminal-B (if available) and the adjustment information received at terminal-A, or only on the adjustment information received at terminal-A. In the case of method 1, IUC can be transmitted using MAC CE and two-stage SCI or MAC CE only. The explicit request and report for IUC are supported in unicast mode.

[0198] In method 2, terminal-A determines the resources reserved by other terminals and identified as completely / partially overlapping with the resources indicated by the SCI of terminal-B at terminal-A, or the slots that are not expected to receive SL in this slot by half-duplex operation when terminal-A is the intended receiver of terminal-B, as the expected / potential collision resources within the resources indicated by the SCI of terminal-B. Terminal-B determines the resources to reselect using the collision resources and excludes the collision resources from the reselected resources. In the case of method 2, PSFCH is used to transmit IUC.

[0199] The procedure for transmitting the adjustment request (SL-IUC Req) between SL terminals is used to trigger the transmission of adjustment information between the SL terminals of the peer UE.

[0200] The procedure for reporting the adjustment information (SL-IUC Info) between SL terminals is used to provide the adjustment information between terminals to the peer UE.

[0201] - sl-LatencyBoundIUC-Report is maintained for each PC5-RRC connection.

[0202] The MAC entity maintains the sl-IUC-ReportTimer for each pair of the source Layer-2 ID and the destination Layer-2 ID corresponding to the PC5-RRC connection. The sl-IUC-ReportTimer is used for the SL-IUC information reporting terminal to comply with the delay requirement notified by the IUC-Information triggering terminal. The value of the sl-IUC-ReportTimer is the same as the delay requirement of the SL-IUC information of sl-LatencyBoundIUC-Report set in RRC.

[0203] The MAC entity performs the following for each pair of the source Layer-2 ID and the destination Layer-2 ID corresponding to the PC5-RRC connection set in the upper layer.

[0204] 1> When the SL-IUC information reporting is triggered by the SL-IUC request MAC CE (and / or SCI) and has not been cancelled:

[0205] 2> When the sl-IUC-ReportTimer is not running for the triggered SL-IUC information reporting:

[0206] 3> Start the sl-IUC-ReportTimer.

[0207] 2> When the sl-IUC-ReportTimer has expired for the triggered SL-IUC information reporting:

[0208] 3> Cancel the triggered SL-IUC information report.

[0209] 2> Otherwise, if the MAC entity has the SL resources assigned to a new transmission and, as a result of logical channel prioritization, the SL-SCH resources can accommodate the SL-IUC information MAC CE and its subheader:

[0210] 3> As defined in 6.1.3.35, instruct to generate the adjustment information MAC CE between SL terminals in the multiplexing and assembly procedures.

[0211] 3> Abort the sl-IUC-ReportTimer for the triggered SL-IUC information report.

[0212] 3> Cancel the triggered SL-IUC information report.

[0213] Figure 9 shows the adjustment information MAC CE between terminals.

[0214] The adjustment information MAC CE between terminals is identified by a MAC subheader having the LCID specified in Table 5.

[0215]

Table 5

[0216] The priority of the adjustment information MAC CE between terminals is fixed at "1". The adjustment information MAC CE between terminals has a variable size and includes the following fields.

[0217] - RT: This field is the code point value of the SCI format 2-C resourceSetType field and indicates the resource set type, i.e., the preferred resource set or the non-preferred resource set.

[0218] - RSL: This field is the code point value of the SCI format 2-C referenceSlotLocation field, indicating the position of the reference slot. The length of said field is 17 bits. If the length of the referenceSlotLocation field in SCI format 2-C is shorter than 17 bits, this field contains the referenceSlotLocation field using the LSB bits.

[0219] - LSIi: This field is the code point value of the SCI format 2-C lowestIndices field, indicating the lowest sub-channel index for the first resource position of each TRIV. LSI0 indicates the lowest sub-channel index for the first resource position of the TRIV within the first resource combination, and LSI1 indicates the lowest sub-channel index for the first resource position of the TRIV within the second resource combination. The length of said field is 5 bits. If the length of the lowestIndices field in SCI format 2-C is shorter than 5 bits, this field contains the lowestIndices field using the LSB bits.

[0220] - RCi: This field is the code point value of the SCI format 2-C resourceCombination field, indicating the resource combination. RC0 indicates the first resource combination, and RC1 indicates the second resource combination. [The maximum number of resource combinations included is 8.] The length of said field is 26 bits. If the length of the resourceCombination field in SCI format 2-C is shorter than 26 bits, this field contains the resourceCombination field using the LSB bits.

[0221] - First resource locationi-1: This field is the code point value of the SCI format 2-C firstResourceLocation field and indicates the first resource location. First Resource location0 indicates the first resource location of the second resource combination, and First Resource location1 indicates the first resource location of the third resource combination. The length of the field is 13 bits. If the length of the firstResourceLocation field in SCI format 2-C is shorter than 13 bits, this field includes the firstResourceLocation field using the LSB bit.

[0222] - R: Reserved bit, set to 0.

[0223] Figure 10 shows the adjustment request MAC CE between terminals.

[0224] The adjustment request MAC CE between terminals is identified by a MAC subheader with the LCID specified in Table 5. The priority of the adjustment request MAC CE between terminals is fixed at "1". The adjustment request MAC CE between terminals has a variable size and includes the following fields.

[0225] - RT: This field is the code point value of the SCI format 2-C resourceSetType field and indicates the resource set type, i.e., the preferred resource set or the non-preferred resource set.

[0226] - RP: This field is the code point value of the SCI format 2-C resourceReservationPeriod field and indicates the resource reservation period. The length of the field is 4 bits. If the length of the resourceReservationPeriod field in SCI format 2-C is shorter than 4 bits, this field includes the resourceReservationPeriod field using the LSB bit.

[0227] - Priority: This field is the code point value of the SCI format 2-C priority field, indicating the priority. The length of the field is 3 bits.

[0228] - RSWL: This field is the code point value of the SCI format 2-C resourceSelectionWindowLocation field, indicating the position of the resource selection window. The length of the field is 34 bits. If the length of the resourceSelectionWindowLocation field in SCI format 2-C is shorter than 34 bits, this field contains the resourceSelectionWindowLocation field using the LSB bits.

[0229] - Number of Subchannel: This field is the code point value of the SCI format 2-C numberOfSubchannel field, indicating the number of subchannels. The length of the field is 5 bits. If the length of the numberOfSubchannel field in SCI format 2-C is shorter than 5 bits, this field contains the numberOfSubchannel field using the LSB bits.

[0230] - R: Reserved bit, set to 0.

[0231] SL Relay

[0232] The SL relay was introduced to support the 5G ProSe terminal-network relay (U2N relay) function that provides network connection to the U2N remote terminal. Both L2 and L3 U2N relay architectures are supported. The L3 U2N relay architecture is transparent to the serving RAN of the U2N relay terminal, except for SL resource control.

[0233] Relay Discovery: An AS function that activates UE-to-Network Relay Discovery between 5G ProSe terminals that use NR technology and do not go through network nodes.

[0234] U2N Relay Terminal: A terminal that provides a function to assist in network connection to U2N remote terminals.

[0235] U2N Remote Terminal: A terminal that communicates with the network through a U2N relay terminal.

[0236] Upstream: The direction from the IAB topology towards the parent node.

[0237] Uu Relay RLC Channel: An RLC channel between the L2 U2N relay terminal and the base station, which is used to transmit packets via Uu for L2 terminal-to-network relay.

[0238] The U2N relay terminal needs to be in the RRC_CONNECTED state to relay unicast data.

[0239] For L2 U2N relay operation, the following combinations of RRC states are supported.

[0240] - The U2N relay terminal and the U2N remote terminal can transmit / receive relayed unicast data only after both are in the RRC CONNECTED state.

[0241] - When all U2N remote terminals connected to the U2N relay terminal are in RRC_INACTIVE or RRC_IDLE, the U2N relay terminal can be in RRC_IDLE, RRC_INACTIVE or RRC_CONNECTED.

[0242] In the case of L2 U2N relay, the U2N remote terminal is configured to use only resource allocation mode 2 for the data to be relayed.

[0243] A single unicast link is established between one L2 U2N relay terminal and one L2 U2N remote terminal. The traffic of the U2N remote terminal and the U2N relay terminal via a given U2N relay terminal needs to be separated into different Uu RLC channels on Uu.

[0244] Protocol Stack of SL Relay

[0245] Figure 11 shows (a) the user plane protocol stack and (b) the control plane protocol stack of the L2 terminal-network relay.

[0246] The protocol stacks for the user plane and control plane of the L2 U2N relay architecture are shown in Figures 11(a) and (b). The SRAP subarray is placed on the RLC sublayer for both CP and UP at both the PC5 interface and the Uu interface. Uu SDAP, PDCP, and RRC are terminated between the L2 U2N remote terminal and the base station, while SRAP, RLC, MAC, and PHY are terminated at each hop (i.e., the link between the L2 U2N remote terminal and the L2 U2N relay terminal and the link between the L2 U2N relay terminal and the base station).

[0247] For the L2 U2N relay, the SRAP sublayer over the PC5 hop is only for bearer mapping. The SRAP sublayer does not exist on the PC5 hop for relaying messages of the L2 U2N remote terminal in BCCH and PCCH. For the L2 U2N remote terminal messages of SRB0, the SRAP sublayer does not exist on the PC5 hop, but the SRAP sublayer exists on the Uu hop for both DL and UL.

[0248] For the L2 U2N relay, uplink:

[0249] - The Uu SRAP sublayer assists in the UL bearer mapping between the receiving PC5 relay RLC channel and the transmitting Uu relay RLC channel for relay via the L2 U2N relay terminal Uu interface. In the case of uplink relay traffic, other end-to-end RBs (SRB or DRB) of the same remote terminal and / or other terminals of other remote terminals are multiplexed via the same Uu relay RLC channel.

[0250] - The Uu SRAP sublayer assists in the identification of the L2 U2N remote terminal for UL traffic. The ID information of the L2 U2N remote terminal Uu radio bearer and the local remote terminal ID are included in the UL Uu SRAP header so that the base station can correlate the received packets with the specific PDCP entity associated with the correct Uu radio bearer of the remote terminal.

[0251] - The PC5 SRAP sublayer of the L2 U2N remote terminal assists in the UL bearer mapping between the remote terminal Uu radio bearer and the transmitting PC5 relay RLC channel.

[0252] In the case of the L2 U2N relay, downlink:

[0253] - The Uu SRAP sublayer assists in the DL bearer mapping at the base station to map the radio bearers (SRB, DRB) between the terminals of the remote terminal to the Uu relay RLC channel via the relay terminal Uu interface. The Uu SRAP sublayer assists in the DL bearer mapping and data multiplexing between multiple end-to-end radio bearers (SRB or DRB) of the L2 U2N remote terminal and / or other L2 U2N remote terminals and one Uu Relay RLC channel via the relay terminal Uu interface.

[0254] - The Uu SRAP sublayer assists in identifying the remote terminal for DL traffic. The ID information of the remote terminal Uu radio bearer and the local remote terminal ID are included in the Uu SRAP header by the base station in the DL so that the relay terminal maps the packets received in the remote terminal Uu radio bearer to the associated PC5 Relay RLC channel.

[0255] - The PC5 SRAP sublayer of the relay terminal assists in the DL bearer mapping between the received Uu Relay RLC channel and the transmitted PC5 Relay RLC channel.

[0256] - The PC5 SRAP sublayer of the remote terminal correlates the received packets to the specific PDCP entity associated with the correct Uu radio bearer of the remote terminal based on the ID information contained in the Uu SRAP header.

[0257] The local remote terminal ID is included in both the PC5 SRAP header and the Uu SRAP header. The local remote terminal ID used for the SRAP header by the base station is set in the L2 U2N relay terminal. The remote terminal obtains the local remote ID from the base station by Uu RRC messages including RRCSetup, RRCReconfiguration, RRCResume and RRCReestablishment. Uu DRB and Uu SRB are mapped to other PC5 relay RLC channels and Uu relay RLC channels in both the PC5 hop and the Uu hop.

[0258] The base station is responsible for preventing collisions in the use of the local remote terminal ID. The base station can update the local remote terminal ID by transmitting the updated local remote ID to the relay terminal by the RRCReconfiguration message. The serving base station can perform the local remote terminal ID update independently of the procedure for updating the PC5 unicast link L2 ID.

[0259] FIG. 12 shows the protocol stack of the discovery message for relay between the terminal and the network.

[0260] For U2N relay discovery, discovery models of Model A and Model B are supported. The protocol stack used for discovery is shown in FIG. 12.

[0261] The U2N remote terminal can send a relay discovery message and can monitor the SL for relay discovery messages while in RRC_IDLE, RRC_INACTIVE, or RRC_CONNECTED. The network can broadcast a threshold, which is used to determine whether the U2N remote terminal can send a Relay discovery solicitation message to the U2N relay terminal.

[0262] The U2N relay terminal can send a relay discovery message and can monitor the SL for relay discovery messages while in RRC_IDLE, RRC_INACTIVE, or RRC_CONNECTED. The network can broadcast the maximum Uu RSRP threshold, the minimum Uu RSRP threshold, or both, which are used to determine whether the U2N relay terminal can send a relay discovery message to the U2N remote terminal.

[0263] The network can provide relay discovery settings using broadcast or dedicated signaling for relay discovery. Also, the U2N remote terminal and the U2N relay terminal can use pre-configurations for relay discovery.

[0264] For relay discovery, a resource pool used for NR SL communication can be used, or the network can configure a resource pool dedicated to relay discovery. The resource pool dedicated to relay discovery and the resource pool for NR SL communication can be configured simultaneously through system information, dedicated signaling, and / or pre-configuration. Whether a resource pool dedicated to relay discovery is configured depends on the implementation of the network. If a resource pool dedicated to relay discovery is configured, only the resource pool dedicated to relay discovery is used for relay discovery. If only the resource pool for NR SL communication is configured, all configured transmission resource pools can be used for relay discovery and SL communication.

[0265] In the case of a U2N remote terminal connected to the network by a U2N relay terminal (including both inside and outside the coverage), only resource allocation mode 2 is used for transmitting the discovery message.

[0266] Relay discovery re-uses the NR SL resource allocation principle for U2N relay terminals within the coverage and the NR SL resource allocation principle for all U2N remote terminals both inside and outside the coverage.

[0267] SL power control for transmitting relay discovery messages is performed in the same way as NR SL communication.

[0268] PDCP layer encryption or integrity protection is not applied to relay discovery messages.

[0269] The terminal determines whether the base station supports relay discovery, non-relay discovery, or both through SIB12.

[0270] Relay Selection / Re-selection

[0271] The U2N remote terminal performs wireless measurements at the PC5 interface and uses these, together with upper layer criteria, for U2N relay selection and reselection. If there is no unicast PC5 connection between the U2N relay terminal and the U2N remote terminal, the U2N remote terminal evaluates whether the PC5 link quality for the U2N relay terminal meets the relay selection criteria using SD-RSRP measurements.

[0272] For relay reselection, if there is data transmission from the U2N relay terminal to the U2N remote terminal, the U2N remote terminal uses SL-RSRP measurements for the serving U2N relay terminal for relay reselection trigger evaluation. If there is no data transmission from the U2N relay terminal to the U2N remote terminal, whether to use SL-RSRP or SD-RSRP for relay reselection trigger evaluation depends on the implementation of the terminal.

[0273] If the PC5 link quality measured by the U2N remote terminal for the U2N relay terminal exceeds a set threshold (pre-set or provided by the base station), the U2N remote terminal considers the U2N relay terminal suitable from the wireless criteria aspect. The U2N remote terminal searches for a suitable U2N relay terminal candidate that meets all AS layer and upper layer criteria (see TS 23.304[xx]). If there are multiple suitable U2N relay terminals, selecting one of them depends on the implementation of the U2N remote terminal. For L2 U2N relay (re)selection, the PLMN ID and cell ID can be used as additional AS criteria.

[0274] The U2N remote terminal triggers U2N relay selection in the following cases.

[0275] - When the direct Uu signal strength of the current serving cell of the U2N remote terminal is lower than the set signal strength threshold.

[0276] - When instructed by the upper layer of the U2N remote terminal.

[0277] The U2N remote terminal triggers U2N relay reselection in the following cases.

[0278] - When the PC5 signal strength of the current U2N relay terminal is lower than the (pre-set) signal strength threshold value.

[0279] - When the U2N relay terminal notifies cell (re)selection, handover, or Uu RLF by means of a PC5-RRC signal.

[0280] - When the remote terminal receives a PC5-S link release message from the U2N relay terminal.

[0281] - When the U2N remote terminal detects a PC5 RLF.

[0282] - When instructed by the upper layer.

[0283] For the L2 U2N remote terminal and the L3 U2N remote terminal in RRC_IDLE / INACTIVE, the cell (re)selection procedure and the relay (re)selection procedure are performed independently. If both a suitable cell and a suitable U2N relay terminal are available, the terminal implementation selects either the cell or the U2N relay terminal. The L3 U2N remote terminal can select a cell and a U2N relay terminal simultaneously, which varies depending on the implementation of the L3 U2N remote terminal.

[0284] For the L2 and L3 U2N relay terminals in RRC_IDLE / INACTIVE, when the U2N relay terminal selects a new cell, a PC5-RRC message is used to notify the connected remote terminal. The PC5-RRC message is also used to notify the connected L2 or L3 U2N remote terminal when the L2 / L3 U2N relay terminal performs a handover or detects a Uu RLF. Upon receiving the PC5 RRC message for notification, whether to release or maintain the unicast PC5 link depends on the implementation of the U2N remote terminal. If the U2N remote terminal decides to release the unicast PC5 link, it can trigger the L2 release procedure and perform relay reselection.

[0285] Control Plane Procedures for L2 U2N Relay

[0286] 1) RRC Connection Management

[0287] The U2N remote terminal needs to configure its PDU session / DRB with the network before transmitting user plane data.

[0288] Before the U2N remote terminal configures the Uu RRC connection with the network through the U2N relay terminal, the NR V2X PC5 unicast link setup procedure is reused to set up a secure unicast link between the U2N remote terminal and the U2N relay terminal.

[0289] The Uu configuration procedure for relay between the L2 terminal and the network is applied to the configuration of the Uu SRB1 / SRB2 and DRB of the U2N remote terminal.

[0290] Figure 13 shows the L2 U2N remote terminal connection setup procedure. The following high-level connection setup procedure in Figure 13 is applicable to the L2 U2N relay.

[0291] 1. The U2N remote terminal and the U2N relay terminal perform a discovery procedure and configure the PC5-RRC connection using the NR V2X procedure.

[0292] 2. The U2N remote terminal uses the specified PC5 relay RLC channel settings to send the first RRC message (i.e., RRC Setup Request) for its connection settings with the base station by the relay terminal. When the U2N relay terminal is not in RRC_CONNECTED, it is necessary to perform its own connection settings when receiving a message on the specified PC5 relay RLC channel. During the RRC connection setup procedure of the relay terminal, the base station can set the Uu relay RLC channel for relaying SRB0 to the U2N relay terminal. The base station responds to the U2N remote terminal with an RRC Setup message. The RRC Setup message is sent to the U2N remote terminal using the SRB0 relay channel via Uu and the specified PC5 relay RLC channel via PC5.

[0293] 3. The base station and the U2N relay terminal perform a relay channel setup procedure via Uu. According to the settings from the base station, the U2N relay / remote terminal sets the PC5 relay RLC channel for relaying SRB1 to the U2N remote / relay terminal via PC5.

[0294] 4. The RRC Setup Complete message is sent from the U2N remote terminal to the base station by the U2N relay terminal using the SRB1 relay channel via PC5 and the SRB1 relay channel set for the U2N relay terminal via Uu. Thereafter, the U2N remote terminal is RRC connected via Uu.

[0295] 5. The U2N remote terminal and the base station set security through the Uu procedure, and the security message is transmitted by the U2N relay terminal.

[0296] 6. The base station sends an RRCReconfiguration message to the U2N remote terminal via the U2N relay terminal to configure the SRB2 / DRB for relay purposes. The U2N remote terminal sends an RRCReconfigurationComplete message to the base station via the U2N relay terminal as a response. Also, the base station further configures the Uu relay RLC channel between the base station and the U2N relay terminal, and configures the PC5 relay RLC channel between the U2N relay terminal and the U2N remote terminal for relay traffic.

[0297] 2) Radio Link Failure

[0298] When the U2N remote terminal in RRC_CONNECTED is connected to the base station by the U2N relay terminal, it suspends the Uu RLM.

[0299] The U2N relay terminal declares a Radio Link Failure (RLF) according to the same criteria.

[0300] After RLF is declared, the U2N relay terminal performs the following operations.

[0301] - The PC5-RRC message is used to send an instruction to the U2N remote terminal connected to the U2N relay terminal, which triggers the RRC connection reconfiguration for the U2N remote terminal.

[0302] When detecting the PC5 RLF, the U2N remote terminal triggers the connection reconfiguration.

[0303] 3) RRC Connection Reconfiguration

[0304] The U2N remote terminal performs the following operations during the RRC connection reconfiguration procedure.

[0305] - If only appropriate cells are available, the U2N remote terminal starts the RRC reconfiguration procedure for the appropriate cell.

[0306] - If only a suitable U2N relay terminal is available, the U2N remote terminal starts an RRC reconfiguration procedure for the serving cell of the suitable relay terminal as appropriate.

[0307] - If both a suitable cell and a suitable relay are available, the U2N remote terminal selects one of the two to start the RRC reconfiguration procedure depending on the implementation.

[0308] 4) RRC connection re-establishment

[0309] The RRC connection re-establishment mechanism is applied to the U2N remote terminal.

[0310] 5) System information

[0311] U2N remote terminals within coverage can obtain all necessary SIBs via the Uu interface, regardless of the PC5 connection with the relay terminal. The U2N remote terminal may receive system information from the relay terminal after the PC5 connection with the U2N relay terminal is established.

[0312] U2N remote terminals in the RRC_CONNECTED state can request SIBs from the U2N relay terminal using the on-demand SIB framework. U2N remote terminals in the RRC_IDLE or RRC_INACTIVE state can inform the U2N relay terminal of the SIB types requested by the PC5-RRC message. Subsequently, the U2N relay terminal triggers the on-demand SI / SIB acquisition procedure according to its own RRC state (if necessary) and sends the SI / SIB obtained by PC5-RRC to the U2N remote terminal.

[0313] The SIBs used by RRC_IDLE or RRC_INACTIVE U2N remote terminals (for example, for the purpose of relays) can be requested in the U2N remote terminals (from the U2N relay terminals or the network). In the case of SIBs requested by the U2N remote terminal from the U2N relay terminal, the U2N relay terminal will re-transmit them if there are updates to the requested SIBs. In the case of RRC_CONNECTED U2N remote terminals, it is the responsibility of the network to send the updated SIBs to the U2N remote terminals during updates. When the U2N remote terminal enters the RRC_CONNECTED state, it releases the SI request with the U2N relay terminal.

[0314] In the case of SIB1 transmission, both the requested base transmission (i.e., the SIB1 request of the U2N remote terminal) and the unrequested transmission to the U2N remote terminal are supported by the U2N relay terminal, and its use is implemented by the U2N relay terminal. When SIB1 is changed, the U2N relay terminal always transmits SIB1 to the U2N remote terminal in the RRC_IDLE or RRC_INACTIVE state.

[0315] Short messages via the Uu interface are not transmitted from the L2 U2N relay terminal to the L2 U2N remote terminal for RRC_IDLE or RRC_INACTIVE L2 U2N remote terminals. The L2 U2N relay terminal can transmit the PWS SIB to the L2 U2N remote terminal connected to it.

[0316] RAN sharing is supported by the L2 U2N relay terminal. In particular, the L2 U2N relay terminal can transmit information regarding cell access by means of discovery messages before setting up a PC5-RRC connection.

[0317] 6) Paging

[0318] When both the U2N relay terminal and the U2N remote terminal are in the RRC IDLE or RRC INACTIVE state, the U2N relay terminal monitors the paging occasions of the U2N remote terminal connected to it. When the U2N relay terminal needs to monitor paging for the U2N remote terminal, the U2N relay terminal must monitor all the POs of the U2N remote terminal.

[0319] When the U2N relay terminal is in the RRC CONNECTED state and the U2N remote terminal is in the RRC_IDLE or RRC_INACTIVE state, there are two options for paging transmission.

[0320] - If a CORESET and a paging search space are configured in the active DL BWP of the U2N relay terminal, the U2N relay terminal monitors the POs of the U2N remote terminal connected to it.

[0321] - The paging transmission of the U2N remote terminal can be performed by a dedicated RRC message from the base station to the U2N relay terminal. The dedicated RRC message for transmitting remote terminal paging to an RRC_CONNECTED relay terminal contains one or more remote terminal IDs (5G-S-TMSI or I-RNTI).

[0322] Which of the two options described above is used depends on the implementation of the network. When a paging search space is configured for the RRC CONNECTED U2N relay terminal, it is possible to determine whether to monitor the POs for the U2N remote terminal based on the PC5-RRC signal received by the U2N remote terminal.

[0323] The U2N remote terminal in RRC_IDLE requests the U2N relay terminal to perform PO monitoring by providing the 5G-S-TMSI (configured at the upper layer) and the terminal-specific DRX period. The U2N remote terminal in RRC_INACTIVE provides the minimum value of the two terminal-specific DRX periods (configured at the upper layer and set by the RAN), the 5G-S-TMSI, and the I-RNTI to the U2N relay terminal for PO monitoring. The L2 U2N relay terminal can notify the base station of the remote terminal information (i.e., 5G-S-TMSI / I-RNTI) via the SidelinkUEInformationNR message for paging transmission purposes. The U2N relay terminal receives the paging message, verifies the 5G-S-TSMI / I-RNTI, and transmits the relevant paging record to the remote terminal accordingly.

[0324] The U2N relay terminal can transmit paging to the U2N remote terminal via PC5 using unicast signaling.

[0325] 7) Access Control

[0326] The U2N remote terminal performs unified access control (UAC). The RRC-CONNECTED U2N relay terminal does not perform UAC on the data of the U2N remote terminal.

[0327] 8) Mobility Registration Update and RAN Area Update

[0328] When the L2 U2N remote terminal is connected to the L2 U2N relay terminal, it performs a mobility registration update / RNAU based on the serving cell of the L2 U2N relay terminal. If the serving cell of an L2 U2N remote terminal in the RRC_IDLE or RRC_INACTIVE state is changed (due to cell change by the U2N relay terminal) and the new serving cell is outside the configured RNA / TA of the U2N remote terminal, it starts the mobility registration update / RNAU procedure.

[0329] Service Continuity for L2 U2N Relay

[0330] 1) Switching from an indirect path to a direct path

[0331] Figure 14 shows the procedure for the U2N remote terminal to switch directly to the Uu cell.

[0332] For the service continuity of the L2 U2N relay, when the U2N remote terminal switches to the direct path, the following procedure is performed.

[0333] 1. The Uu measurement setting and measurement reporting signaling procedures are performed to evaluate both the relay link measurement and the Uu link measurement. When the set measurement reporting criteria are met, the measurement results of the U2N remote terminal are reported. The SL relay measurement report should include at least the source L2 ID of the U2N relay terminal, the serving cell ID (i.e., NCGI), and the SL measurement quantity information. The SL measurement quantity is the SL-RSRP of the serving U2N relay terminal, and if the SL-RSRP is not available, the SD-RSRP is used.

[0334] 2. The base station decides to switch the U2N remote terminal to the direct Uu path.

[0335] 3. The base station sends an RRCReconfiguration message to the U2N remote terminal. After receiving the RRCReconfiguration message from the base station, the U2N remote terminal stops the UP and CP transmissions by the U2N relay terminal.

[0336] 4. The U2N remote terminal performs random access in synchronization with the base station.

[0337] 5. The terminal (i.e., the previous-stage U2N remote terminal) uses the settings provided in the RRCReconfiguration message to send RRCReconfigurationComplete to the base station via the direct path. From this stage onwards, the terminal (i.e., the previous-stage U2N remote terminal) uses the RRC connection via the direct path to the base station.

[0338] 6. The base station sends an RRCReconfiguration message to the U2N relay terminal to reconfigure the connection between the U2N relay terminal and the base station. The RRCReconfiguration message to the U2N relay terminal is sent at any time after three steps by the implementation of the base station (e.g., to release the Uu and PC5 relay RLC channel settings for relaying and the bearer mapping settings between PC5 RLC and Uu RLC).

[0339] 7. The U2N relay terminal or the U2N remote terminal initiates PC5 unicast link release (PC5-S). The timing of link release depends on the implementation of the terminal. The U2N relay terminal performs PC5 connection reconfiguration to release the PC5 relay RLC channel for relaying when the base station receives RRC Reconfiguration in step 6, or the terminal (i.e., the previous U2N remote terminal) performs PC5 connection reconfiguration to release the PC5 relay RLC channel when the base station receives RRCReconfiguration in step 3.

[0340] 8. The data path is switched from the indirect path to the direct path between the terminal (i.e., the previous U2N remote terminal) and the base station. During the path switch, DL / UL lossless transmission is performed according to the PDCP data recovery procedure.

[0341] Reference: The 8th step can be performed at any time after the 4th step. The 8th step is independent of the 6th and 7th steps.

[0342] 2) Switching from the direct path to the indirect path

[0343] FIG. 15 shows the procedure for the U2N remote terminal to switch to the indirect path.

[0344] The base station can select a U2N relay terminal in all RRC states such as RRC_IDLE, RRC_INACTIVE, or RRC_CONNECTED as the target U2N relay terminal for the direct-indirect path switch.

[0345] For the service continuity of the L2 U2N remote terminal, when the L2 U2N remote terminal is switched to the indirect path by a U2N relay terminal in the RRC_CONNECTED state, the following procedure is performed.

[0346] 1. After measuring / discovering candidate U2N relay terminals, the U2N remote terminal reports one or more candidate U2N relay terminals and Uu measurement values.

[0347] - The terminal can appropriately filter the U2N relay terminals according to the relay selection criteria before reporting. The terminal needs to report only the U2N relay terminal candidates that meet the upper layer criteria.

[0348] - The report includes at least the U2N relay terminal ID, the serving cell ID of the U2N relay terminal, and the SL measurement quantity information. The SL measurement quantity is the SL-RSRP of the candidate U2N relay terminal, and when the SL-RSRP is not available, the SD-RSRP is used.

[0349] 2. The base station decides to switch the U2N remote terminal to the target U2N relay terminal. Subsequently, the base station sends an RRCReconfiguration message to the target U2N relay terminal. This includes at least the local ID and L2 ID of the remote terminal, the Uu and PC5 relay RLC channel settings for relaying, and the bearer mapping settings.

[0350] 3. The base station sends an RRCReconfiguration message to the U2N remote terminal. The content of the RRCReconfiguration message includes at least the U2N relay terminal ID, the PC5 relay RLC channel settings for relay traffic, and the radio bearers between the associated endpoints. After receiving the RRCReconfiguration message from the base station, the U2N remote terminal suspends UP and CP transmissions via Uu.

[0351] 4. The U2N remote terminal sets up a PC5 connection with the target U2N relay terminal.

[0352] 5. The U2N remote terminal sends an RRCReconfigurationComplete message to the base station via the relay terminal to complete the path switching procedure.

[0353] 6. The data path is switched from a direct path to an indirect path between the U2N remote terminal and the base station.

[0354] When the U2N relay terminal selected for direct - indirect path switching is in RRC_IDLE or RRC_INACTIVE, after receiving the path switching command, the U2N remote terminal sets up a PC5 link with the U2N relay terminal and transmits an RRCReconfigurationComplete message through the U2N relay terminal. In that case, the U2N relay terminal is switched to the RRC_CONNECTED state. In FIG. 15, the U2N remote terminal procedure for switching to an indirect path is also applicable when the U2N relay terminal selected for direct - indirect path switching is in RRC_IDLE or RRC_INACTIVE, but the four - step process must be performed before the two - step process.

[0355] SL Discovery

[0356] The terminal can perform NR SL discovery while inside or outside coverage for non - relayed operation.

[0357] The relay discovery mechanism (excluding the transmission of discovery messages based on U2N - relay - specific thresholds) is also applicable to SL discovery.

[0358] RRC Reconfiguration and Failure Handling for Direct Link and Relay Link

[0359] According to the prior art, when a terminal - network relay (U2N relay) function is set up between a relay terminal and a remote terminal, the relay terminal provides a network connection to the U2N remote terminal. In this case, the remote terminal is not directly connected to the network while maintaining an indirect connection based on the U2N relay function.

[0360] On the other hand, it is advantageous for the remote terminal to maintain not only an indirect connection based on both PC5 and Uu but also a direct connection only through Uu to support multi - path (MP) operation. A remote terminal with MP operation set can select one or both of the connections for data transmission to the network for more stable transmission and / or higher throughput.

[0361] In the case of MP operation, the remote terminal needs to set up an indirect connection while having a direct connection. However, according to the prior art, setting up an indirect connection based on a direct connection is not supported.

[0362] The method for executing data transmission of the terminal includes the following steps.

[0363] The remote terminal directly sets up an RRC connection with the base station and directly sets up a secondary connection through the RRC connection.

[0364] 1. Addition of U2N connection by RRC reconfiguration procedure

[0365] (1) Option 1: Joint RRC reconfiguration

[0366] The RRC reconfiguration message sent to the relay terminal includes both the U2N configuration for the relay terminal and the U2N configuration for the remote terminal.

[0367] - Option 1A: The RRC container of the DL RRC reconfiguration message includes the RRC reconfiguration message sent from the SL.

[0368] - Option 1B: The relay terminal sends the RRC container of the RRC sidelink message including the RRC reconfiguration of the remote terminal to the remote terminal based on the DL RRC reconfiguration message.

[0369] The relay terminal and the remote terminal can each independently send their respective RRC reconfiguration completion messages.

[0370] Alternatively, the RRC reconfiguration completion message of the remote terminal is included in the RRC container of the RRC reconfiguration completion message of the relay terminal sent to the base station.

[0371] The RRC reconfiguration failure of the relay terminal or the remote terminal can trigger the RRC reconfiguration failure of the remote terminal or the relay terminal.

[0372] When the relay terminal reports an RRC reconfiguration failure to the base station, the relay terminal can indicate whether the RRC reconfiguration failure is due to the RRC reconfiguration failure of the remote terminal or the RRC reconfiguration failure of the relay terminal.

[0373] (2) Option 2: Separate transmission of RRC reconfiguration

[0374] The RRC configuration message for the relay terminal and the RRC configuration message for the remote terminal are transmitted separately.

[0375] The RRC configuration message for the remote terminal can be transmitted via U2N SRB1 or direct SRB1.

[0376] (i) Direct SRB1

[0377] The RRC reconfiguration failure of the relay terminal or the remote terminal is not related to the RRC reconfiguration failure of the remote terminal or the relay terminal.

[0378] In the case of a reconfiguration failure of the relay terminal or the remote terminal, the base station can abandon the U2N connection setup and re-trigger the RRC reconfiguration of the remote terminal or the relay terminal.

[0379] (ii) SL-RLC1 for SRB1 of the U2N base

[0380] The relay terminal transmits the RRC reconfiguration of the remote terminal only when the RRC reconfiguration of the relay terminal is successful.

[0381] The relay terminal does not transmit the RRC reconfiguration of the remote terminal when the RRC reconfiguration of the relay terminal fails.

[0382] When the relay terminal reports an RRC reconfiguration failure to the base station, the relay terminal indicates the RRC reconfiguration failure to the base station.

[0383] 2. CN impact

[0384] CN can affect the multi - path configuration.

[0385] (1) Method 1: When the NAS of the UE sends an IDT (Service Request) to the CN, the CN provides the multi - path configuration to the base station.

[0386] The multi - path configuration is provided to the base station by the initial UE context setup.

[0387] (2) Method 2: When the base station determines the multi - path, the CN provides the multi - path configuration to the base station.

[0388] If necessary, the base station may re - trigger the RRC re - configuration to set additional multi - path operations.

[0389] The method for the terminal to execute data transmission and reception includes the following steps.

[0390] 1. The remote terminal performs random access, performs RRC connection setup with the network, and can also perform relay terminal and PC5 discovery and PC5 - RRC connection setup as follows.

[0391] A. While the RRC connection is terminated and there is no U2N relay connection, the remote terminal in RRC_IDLE or RRC_INACTIVE selects a cell, performs random access in the cell, and then directly sends the first RRC message (i.e., RRCSetupRequest or RRCResumeRequest) in the UL for RRC connection setup with the base station. The base station directly responds to the remote terminal in the DL with an RRCSetup or RRCResume message.

[0392] Upon receiving an RRCSetup or RRCResume message, the terminal transmits an RRCSetupComplete or RRCResumeComplete message to the base station. Thereafter, the base station can transmit a SecurityModeCommand message to the terminal for AS security activation between the terminal and the base station. After RRC connection setup and AS security activation, the base station can transmit a first RRCReconfiguration message to the terminal to configure radio parameters and direct data bearers for the terminal.

[0393] B. On the other hand, the U2N remote terminal and the U2N relay terminal perform a discovery procedure and configure a PC5-RRC connection using the NR V2X procedure. Thereafter, the U2N remote terminal can configure a first SL DRX setting and transmit it to the U2N relay terminal by means of an RRCReconfigurationSidelink message for the PC5-RRC connection, or vice versa.

[0394] The present invention can assist all procedures for RRC connection setup, PC5 discovery, and PC5-RRC connection setup. For example, the RRC connection setup can precede the PC5 discovery and the PC5-RRC connection setup. Alternatively, the PC5 discovery and the PC5-RRC connection setup can precede the RRC connection setup. Alternatively, the terminal can perform the PC5 discovery, the RRC connection setup, and then the PC5-RRC connection setup in sequence according to the implementation of the terminal.

[0395] 2. The remote terminal is configured by the network to derive NR SL measurement results of the serving L2 relay terminal or the candidate L2 U2N relay terminal related to the measurement object set in measObjectRelay.

[0396] 3. The remote terminal can receive measurement settings in the RRCReconfiguration message. When the terminal receives measConfig in the RRCReconfiguration message, the terminal performs measurements for each measId included in the measIdList in VarMeasConfig as follows and starts the measurement reporting procedure.

[0397] A. When the measObject is related to an L2 U2N relay terminal, the remote terminal performs the measurement related to the candidate relay terminal at the frequency indicated by the related measObject. When performing the measurement, the terminal filters the measurement results based on layer 3 filtering before using them for report criteria evaluation or measurement reporting for the measurement quantities of each candidate L2 U2N relay terminal.

[0398] B. For the measurement quantities of each L2 U2N relay terminal to be derived, the remote terminal performs the following.

[0399] - Derive the measurement quantity based on the DMRS as shown in TS 38.215 of the L2 U2N relay terminal related to the NR SL frequency indicated by the related measObjectRelay. Also,

[0400] - Apply layer 3 filtering.

[0401] C. When the measObject is related to an L2 U2N relay terminal:

[0402] - When eventY1-Relay is set in the reportConfig; or

[0403] - When the reportConfig includes a reportType set to periodical:

[0404] The remote terminal needs to consider all L2 U2N relay terminals detected at the related frequency as applicable to this measId.

[0405] Table 6 describes the events for measurement report triggering.

[0406]

Table 6-1

Table 6-2

Table 6-3

Table 6-4

[0407] In the state where the measurement report items for this measId are not included in D.VarMeasReportList (the first L2 U2N relay terminal triggers the event), when reportType is set to eventTriggered and the item conditions applicable to this event, that is, the event corresponding to the eventId of the said reportConfig in VarMeasConfig, are satisfied for all measurements after layer 3 filtering performed during the timeToTrigger defined for this event in VarMeasConfig for one or more applicable L2 U2N relay terminals, the remote terminal shall do the following.

[0408] - Include the measurement report items in the VarMeasReportList for this measId.

[0409] - Set the numberOfReportsSent defined in the VarMeasReportList for this measId to 0.

[0410] - Include the L2 U2N relay terminals related to the relaysTriggeredList defined in the VarMeasReportList for this measId.

[0411] - Start the measurement reporting procedure as follows.

[0412] If not, when reportType is set to eventTriggered and the applicable item conditions for this event, i.e., the event corresponding to the eventId of the relevant reportConfig in VarMeasConfig, are met for all measurements after layer 3 filtering performed during the timeToTrigger defined for this event in VarMeasConfig for one or more applicable L2 U2N relay terminals not included in the relaysTriggeredList (subsequent L2 U2N relay terminals trigger the event), the remote terminal shall do the following.

[0413] - Set the numberOfReportsSent defined in VarMeasReportList for this measId to 0.

[0414] - Include the L2 U2N relay terminal in the relaysTriggeredList defined in VarMeasReportList for this measId.

[0415] - Start the measurement reporting procedure as follows.

[0416] E. If not, when reportType is set to eventTriggered and the applicable detachment conditions for this event are met for one or more of the L2 U2N relay terminals included in the relaysTriggeredList defined in VarMeasReportList for this measId for all measurements after layer 3 filtering performed during the timeToTrigger defined for this event in VarMeasConfig, the remote terminal shall do the following.

[0417] - Remove the relevant L2 U2N relay terminals from the relaysTriggeredList defined within the VarMeasReportList for this measId.

[0418] - For the said reporting settings, when reportOnLeave is set to true, start the measurement reporting procedure as follows.

[0419] - If the relaysTriggeredList defined within the VarMeasReportList for this measId is empty: Remove the measurement report items within the VarMeasReportList for this measId; If the periodic reporting timer for this measId is running, stop it.

[0420] If F.reportType is set to periodical and (the first) measurement results are available:

[0421] - If reportAmount exceeds 1: The terminal starts the measurement reporting procedure as shown in 5.5.5 immediately after the amount to be reported becomes available for the NR SpCell or, if the terminal is an L2 U2N remote terminal, for the serving L2 U2N relay terminal.

[0422] - Otherwise (i.e., if reportAmount is 1): Start the measurement reporting procedure as shown in 5.5.5 immediately after the amount to be reported becomes available for the NR SpCell and the strongest cell among the said cells, or for the NR SpCell and the strongest L2 U2N relay terminal among the applicable L2 U2N relay terminals; or start the measurement reporting procedure as follows immediately after the amount to be reported becomes available for the serving L2 U2N relay terminal and the strongest cell among the applicable cells (if the terminal is an L2 U2N remote terminal).

[0423] 4. In the previous stage, when starting the measurement reporting procedure, for the measId for which the measurement reporting procedure is triggered, after the terminal sets the measResults in the MeasurementReport message as follows, the remote terminal sends the MeasurementReport message to the network via the SRB.

[0424] A. When the terminal is connected to the L2 U2N relay terminal through the PC5-RRC connection (i.e., when the terminal is an L2 U2N remote terminal), the terminal needs to set the sl-MeasResultServingRelay to include the SL-RSRP of the serving L2 U2N relay terminal.

[0425] - When there is no data transmission from the L2 U2N relay terminal to the L2 U2N remote terminal, when setting the sl-MeasResultServingRelay of the serving L2 U2N relay terminal, whether to use SL-RSRP or SD-RSRP depends on the implementation of the terminal.

[0426] B. When there is one or more applicable adjacent cells to be reported:

[0427] - When the reportType is set to eventTriggered or periodical and the measurement report is related to the candidate L2 U2N relay terminal, the terminal needs to set the sl-MeasResultCandRelay to include the best candidate L2 U2N relay terminal up to maxReportCells as follows.

[0428] When the reportType is set to eventTriggered: The terminal must include the L2 U2N relay terminals included in the relaysTriggeredList as defined in the VarMeasReportList for this measId.

[0429] Otherwise, the terminal shall include applicable L2 U2N relay terminals for which new measurement results have become available after the last periodic report or after the measurement has been started or reset.

[0430] - For each L2 U2N relay terminal included in sl-MeasResultsCandRelay, the terminal shall include sl-RelayUEIdentity. For each included L2 U2N relay terminal, the terminal shall include layer 3 filtered measurement results according to the reportConfig for this measId.

[0431] If the measObject related to this measId is related to an L2 U2N relay terminal, the terminal shall set the measResult to include the quantity indicated from reportQuantityRelay within the related reportConfigRelay in descending order of the sorting quantity, with the best L2 U2N relay terminal included first.

[0432] For candidate L2 U2N relay terminals, the terminal shall consider yN-Threshold2-Relay as the sorting quantity.

[0433] For candidate L2 U2N relay terminals, the terminal shall consider reportQuantityRelay as the sorting quantity.

[0434] Table 7 describes the SL-MeasResultsSLRelay information element.

[0435]

Table 7

[0436] 5. After the PC5-RRC connection is established through the PC5 unicast link configuration, the remote terminal and the relay terminal can trigger the SL terminal capability transmission procedure to exchange their respective terminal capabilities. In this procedure, the remote terminal sends a UECapabilityEnquirySidelink message to the relay terminal to request the relay terminal's MP capability, and the relay terminal sends a UECapabilityInformationSidelink message including the MP capability to the remote terminal. Then, the relay terminal sends a UECapabilityEnquirySidelink message to the remote terminal to request the remote terminal's MP capability, and the remote terminal sends a UECapabilityInformationSidelink message including the MP capability to the relay terminal.

[0437] The MP capability of the terminal includes any one or more of the following.

[0438] - Whether the terminal supports multi-path operation as a remote terminal and / or a relay terminal

[0439] - The SL / UL / DL frequency carriers / bands that the terminal supports for MP operation for transmission and / or reception

[0440] - The combination of the SL carrier / band and the UL carrier / band that the terminal supports for MP operation for its own transmission

[0441] - The combination of the SL carrier / band and the DL carrier / band that the terminal supports for MP operation for its own reception

[0442] Based on the above-mentioned exchange of SL terminal capabilities, when the relay terminal confirms that both the relay terminal and the remote terminal support the MP capability, and the remote terminal is in RRC_CONNECTED, the relay terminal that is not in RRC_CONNECTED can initiate the RRC connection setup procedure.

[0443] 6. If the remote terminal and the relay terminal assist the MP operation in the DL / UL carrier of the serving cell and the SL carrier where SL transmission and / or SL reception between the remote terminal and the relay terminal are performed, or if the serving cell assists the SL resources for SL transmission / reception and / or MP operation (e.g., according to the resource pool setting of the system information or dedicated signal), the relay terminal starts the RRC connection setup, or the relay terminal transmits a first SL message to the remote terminal to notify the RRC state of the relay terminal or whether the relay terminal is in RRC_CONNECTED.

[0444] A. The first SL message includes any one or more of the following.

[0445] - The PCell cell ID of the relay terminal.

[0446] - The PLMN ID of the registered PLMN of the relay terminal.

[0447] - The tracking area code of the tracking area registered by the relay terminal for the PCell.

[0448] B. When receiving the first SL message, the remote terminal performs any one or more of the following steps.

[0449] - If the cell indicated by the relay terminal is different from the serving cell where the remote terminal camps on, the remote terminal reselects the indicated cell according to the cell reselection procedure, or the remote terminal aborts the multi-path operation setup with the relay terminal. If the remote terminal cannot reselect the indicated cell according to the cell reselection procedure, the remote terminal aborts the multi-path operation setup with the relay terminal.

[0450] - If the tracking area indicated by the relay terminal is different from the registered tracking area of the remote terminal, the remote terminal triggers a tracking area update procedure to register in the tracking area indicated by the relay terminal, or the remote terminal aborts the multi-path operation setting with the relay terminal. For example, if the remote terminal cannot register in the tracking area indicated by the relay terminal due to the failure of the tracking area update procedure or other related NAS procedures, the remote terminal aborts the multi-path operation setting with the relay terminal.

[0451] - If the PLMN indicated by the relay terminal is different from the registered PLMN of the remote terminal, the remote terminal reselects the PLMN indicated by the relay terminal and registers in the indicated PLMN, or the remote terminal aborts the multi-path operation setting with the relay terminal. For example, if the remote terminal cannot register in the PLNN indicated by the relay terminal due to the failure of the PLMN registration procedure or other related NAS procedures, the remote terminal aborts the multi-path operation setting with the relay terminal.

[0452] C. The first SL message is a RemoteUEInformationSidelink message, a UEAssistanceInformationSidelink message, an RRCReconfigurationSidelink message, or an RRCReconfigurationCompleteSidelink message.

[0453] 7. When the remote terminal directly enters RRC_CONNECTED by RRC connection setup (i.e., by the RACH procedure), the remote terminal sets up the PC5-RRC connection by PC5 unicast link setup, and whether the remote terminal and the relay terminal assist MP operation in the DL / UL carrier and the SL carrier of the serving cell where SL transmission and / or SL reception between the remote terminal and the relay terminal are performed, or the serving cell supports SL resources for SL transmission / reception and / or MP operation (e.g., by resource pool setting of system information or dedicated signal base):

[0454] A. (Upon receiving the first SL message) The remote terminal can request the relay terminal to send a second SL message and start the RRC connection setup for entering the RRC_CONNECTED state. The second SL message includes one or more of the following.

[0455] - A request for multi-path operation or a request for the relay terminal to set up an RRC connection for multi-path

[0456] If this request is included, the relay terminal triggers the RRC connection setup.

[0457] - The RRC state of the remote terminal or whether the remote terminal is in the RRC_CONNECTED state

[0458] - The cell ID of the serving cell on which the remote terminal camps.

[0459] - The PLMN ID of the registered PLMN of the remote terminal.

[0460] - The tracking area code of the tracking area in which the remote terminal is registered with the PCell.

[0461] At this stage, (based on the first SL message), the remote terminal requests the relay terminal to start the RRC connection setup if one or more of the following conditions are met.

[0462] - If the relay terminal is not in the RRC_CONNECTED state

[0463] - If the relay terminal camps on the same cell on which the remote terminal camps.

[0464] - If the relay terminal camps on the cell corresponding to the best cell of the remote terminal, i.e., the cell with the best cell quality among the multiple cells measured by the remote terminal.

[0465] - When the remote terminal measures the cell instructed by the relay terminal and the measurement result of the cell instructed by the relay terminal exceeds the threshold value set by the network (SIB or dedicated signal).

[0466] In this case, among all the candidate cells, regardless of whether the cell is the highest-ranked cell in terms of cell quality, if the cell is suitable, the remote terminal performs cell reselection on the cell.

[0467] - When the remote terminal reselects the cell instructed by the relay terminal (for example, when the instructed cell is not the blocked cell of the remote terminal / or when the instructed cell is an appropriate cell of the remote terminal)

[0468] - After the remote terminal receives the first SL message, if it successfully reselects the cell instructed by the relay terminal as a result of the cell reselection procedure.

[0469] - When the relay terminal is registered in the same tracking area as the tracking area in which the remote terminal is registered.

[0470] - When the remote terminal can register in the tracking area instructed by the relay terminal (for example, when the tracking area is not in the prohibited tracking area list of the remote terminal, or when the tracking area does not correspond to a tracking area that could not be registered by the tracking area update of the remote terminal).

[0471] - After the remote terminal receives the first SL message, if it successfully registers in the tracking area instructed by the relay terminal.

[0472] - When the relay terminal is registered in the same PLMN as the PLMN in which the remote terminal is registered.

[0473] - When the remote terminal can register in the PLMN instructed by the relay terminal (for example, when the PLMN is not in the prohibited PLMN list of the remote terminal, or when the PLMN does not correspond to a PLMN that the remote terminal could not register).

[0474] - When the remote terminal successfully registers with the PLMN instructed by the relay terminal after receiving the first SL message.

[0475] In the above-mentioned stage, if any one or more of the above conditions are not met, the remote terminal does not request the relay terminal to start the RRC connection setup, and aborts the MP operation with the relay terminal.

[0476] B. After receiving the second SL message (and / or after sending the first SL message), when any one or more of the following conditions are met, the relay terminal sends an RRCSetupRequest message or an RRCResumeRequest message to the base station to start the RRC connection setup procedure.

[0477] - When the relay terminal is not in the RRC_CONNECTED state

[0478] - When the relay terminal camps on the same cell as the cell where the remote terminal camps (i.e., the cell instructed by the remote terminal).

[0479] - When the remote terminal camps on the cell corresponding to the best cell of the relay terminal, that is, among the multiple cells measured by the relay terminal, the cell with the best cell quality.

[0480] - When the relay terminal measures the cell instructed by the remote terminal, and the measurement result of the cell instructed by the remote terminal exceeds the threshold set by the network (SIB or dedicated signal).

[0481] In this case, regardless of whether the cell occupies the highest rank in terms of cell quality among all candidate cells, if the cell is appropriate, the relay terminal performs cell reselection on the cell.

[0482] - When the relay terminal can reselect the cell instructed by the remote terminal (for example, when the instructed cell is not the blocked cell of the remote terminal / or the instructed cell is an appropriate cell of the remote terminal)

[0483] - After the relay terminal receives the second SL message, if it successfully reselects the cell instructed by the remote terminal as a result of the cell reselection procedure.

[0484] - If the remote terminal is registered in the same tracking area as the tracking area in which the relay terminal is registered.

[0485] - If the relay terminal can be registered in the tracking area instructed by the remote terminal (for example, if the tracking area is not in the relay terminal's prohibited tracking area list or does not correspond to a tracking area that could not be registered by the relay terminal's tracking area update).

[0486] - After the relay terminal receives the second SL message, if it successfully registers in the tracking area instructed by the remote terminal.

[0487] - If the remote terminal is registered in the same PLMN as the PLMN in which the relay terminal is registered.

[0488] - If the relay terminal can be registered in the PLMN instructed by the remote terminal (for example, if the PLMN is not in the relay terminal's prohibited PLMN list or does not correspond to a PLMN that the relay terminal could not register).

[0489] - After the relay terminal receives the second SL message, if it successfully registers in the PLMN instructed by the remote terminal.

[0490] In the above-described stage, if any one or more of the above conditions are not satisfied, the relay terminal aborts the RRC connection setup or the relay terminal does not start the RRC connection setup. The relay also aborts the MP operation with the relay terminal.

[0491] - When the second SL message requesting multi-path operation or RRC connection setup is the RRCReconfigurationSidelink message transmitted by the remote terminal,

[0492] If the RRC connection setup of the relay terminal is not successfully completed, the relay terminal sends an RRCReconfigurationFailureSidelink message to the remote terminal.

[0493] The RRCReconfigurationFailureSidelink message may include a failure cause indicating "RRC connection setup failure".

[0494] Upon receiving the RRCReconfigurationFailureSidelink message, the remote terminal aborts the MP operation with the relay terminal and reselects another relay terminal.

[0495] Otherwise, if the RRC connection setup of the relay terminal is successfully completed, the relay terminal sends an RRCReconfigurationCompleteSidelink message to the remote terminal. The RRCReconfigurationCompleteSidelink message includes one or more of the following.

[0496] Whether the RRC connection setup of the relay terminal was successfully completed.

[0497] The PCell cell ID of the relay terminal.

[0498] The PLMN ID of the PLMN registered by the relay terminal.

[0499] The tracking area code of the tracking area where the relay terminal is registered with the PCell.

[0500] C. In the above-described stage, the first SL message and / or the second SL message is a RemoteUEInformationSidelink message, a UEAssistanceInformationSidelink message, an RRCReconfigurationSidelink message, or an RRCReconfigurationCompleteSidelink message.

[0501] 8. When the relay terminal sends an SL message and reports to the remote terminal that the RRC connection setup of the relay terminal has been successfully completed, the relay terminal may instruct the remote terminal with one or more of the following by means of the SL message.

[0502] - The PCell cell ID of the relay terminal.

[0503] - The PLMN ID of the PLMN in which the relay terminal is registered.

[0504] - The tracking area code of the tracking area in which the relay terminal is registered with the PCell.

[0505] A. When the relay terminal and the remote terminal are set to different serving cells, different tracking areas and / or different PLMNs from each other, the remote terminal and / or the relay terminal shall notify the base station of one or more different serving cells, different tracking areas and / or different PLMNs by means of, for example, the SidelinkUEInformationNR message.

[0506] B. The SL message is a RemoteUEInformationSidelink message, a UEAssistanceInformationSidelink message, an RRCReconfigurationSidelink message, or an RRCReconfigurationCompleteSidelink message.

[0507] 9. After the RRC connection setup and the PC5 - RRC connection setup, the relay terminal and / or the remote terminal shall perform SL terminal information for the NR sidelink communication procedure in which the terminal sends the SidelinkUEInformationNR message to the base station.

[0508] The terminal shall set the content of the SidelinkUEInformationNR message as follows.

[0509] A. When sl-NonRelayDiscovery is included in a specific SIB (e.g., SIB12) and is set by the upper layer to receive NR SL non-relay discovery knowledge, or when sl-L2U2N-Relay is included in a specific SIB (e.g., SIB12) and is set by the upper layer to receive NR SL L2 U2N relay discovery knowledge, or when sl-L3U2N-RelayDiscovery is included in a specific SIB (e.g., SIB12) and is set by the upper layer to receive NR SL L3 U2N relay discovery knowledge, or when an instruction for multi-path support is included in a specific SIB (e.g., SIB12) and is set by the upper layer to receive NR SL U2N relay discovery knowledge:

[0510] - The terminal includes sl-RxInterestedFreqListDisc and sets it to the frequency for receiving NR SL relay discovery knowledge.

[0511] - When the terminal acts as an L2 U2N remote terminal or when the terminal performs multi-path operation as a remote terminal, the terminal includes sl-SourceIdentity-RemoteUE and sets it to the source ID set by the upper layer for NR SL L2 U2N relay communication transmission.

[0512] B. When sl-NonRelayDiscovery is included in a specific SIB (e.g., SIB12) and is set by the upper layer to transmit NR SL non-relay discovery public knowledge, or when sl-L2U2N-Relay is included in a specific SIB (e.g., SIB12) and is set by the upper layer to transmit NR SL L2 U2N relay discovery public knowledge, or when sl-L3U2N-RelayDiscovery is included in a specific SIB (e.g., SIB12) and is set by the upper layer to transmit NR SL L3 U2N relay discovery public knowledge, or when a specific SIB (e.g., SIB12) includes an instruction for multi-path support and is set by the upper layer to transmit NR SL U2N relay discovery public knowledge, the terminal includes sl-TxResourceReqListDis and, for each destination for which it requests the network to allocate NR SL discovery public knowledge resources, (if necessary) sets its fields as follows:

[0513] - Set sl-DestinationIdentityDisc to the destination ID set by the upper layer for NR SL discovery public knowledge transmission.

[0514] - When the terminal operates as an L2 U2N relay terminal, the terminal sets sl-SourceIdentity-RelayUE to the source ID set by the upper layer for NR SL L2 U2N relay discovery public knowledge transmission.

[0515] - Set sl-CastTypeDisc to the cast type of the related destination ID set by the upper layer for NR SL discovery public knowledge transmission.

[0516] - Set sl-InterestedFreqListDisc to indicate the frequencies of the related destinations for NR SL discovery public knowledge transmission.

[0517] - Set the sl-TypeTxSyncListDisc to the current synchronization reference type used in the related sl-InterestedFreqList for NR SL discovery known transmission.

[0518] - Set the sl-DiscoveryType to the current discovery type of the related destination ID set by the upper layer for NR SL discovery known transmission.

[0519] C. Set by the upper layer to transmit NR SL L2 U2N relay communication. When the terminal operates as an L2 U2N relay terminal for multi-path, the relay terminal shall perform the following.

[0520] - Include sl-TxResourceReqL2U2N-Relay in sl-TxResourceReqListCommRelay and set this field as follows for each destination that requests (if necessary) the network to allocate NR SL L2 U2N relay communication resources.

[0521] - Set the sl-DestinationIdentityL2U2N to the destination ID set by the upper layer for NR SL L2 U2N relay communication transmission.

[0522] - Set the sl-TxInterestedFreqListL2U2N to indicate the frequencies of the related destinations for NR SL L2 U2N relay communication transmission.

[0523] - Set the sl-TypeTxSyncListL2U2N to the current synchronization reference type used in the related sl-InterestedFreqListL2U2N for NR SL L2 U2N relay communication transmission.

[0524] - Set the sl-LocalID-Request to request the local ID for the L2 U2N remote terminal.

[0525] - Set the sl-PagingIdentity-RemoteUE to the paging terminal ID received at the peer L2 U2N remote terminal.

[0526] - Set the sl-CapabilityInformationSidelink to include the UECapabilityInformationSidelink message (if present) received at the peer terminal.

[0527] - Include the ue-Type and set this to the relay UE.

[0528] - Include the multi-path support / request indication.

[0529] - Include an indication of whether the RRC state of the remote terminal or whether the remote terminal is in RRC_CONNECTED.

[0530] - Include the cell ID of the PCell for the remote terminal.

[0531] - Include the PLMN ID of the PLMN registered for the remote terminal.

[0532] - Include the tracking area code of the tracking area where the remote terminal is registered to the PCell.

[0533] D. NR sidelink L2 U2N relay communication is set by the upper layer to transmit. If there is an L2 U2N relay terminal selected by the terminal for multi-path, the remote terminal shall perform the following.

[0534] - Include the sl-TxResourceReqL2U2N-Relay in the sl-TxResourceReqListCommRelay and (if necessary) set its fields as follows to request the network to allocate NR SL L2 U2N relay communication resources.

[0535] - Set sl-TxInterestedFreqListL2U2N to indicate the frequencies of the destinations relevant for NR SL L2 U2N relay communication transmission.

[0536] - Set sl-TypeTxSyncListL2U2N to the current synchronization reference type used in the relevant sl-InterestedFreqListL2U2N for NR SL L2 U2N relay communication transmission.

[0537] - If there is a terminal CapabilityInformationSidelink message received at the peer terminal, set sl-CapabilityInformationSidelink to include this.

[0538] - Include ue-Type and set it to remoteUE.

[0539] - Include multi-path support / request indication.

[0540] - Include an indication of the RRC state of the relay terminal or whether the relay terminal is in RRC_CONNECTED.

[0541] - Include the PCell cell ID of the relay terminal.

[0542] - Include the PLMN ID of the registered PLMN of the relay terminal.

[0543] - Include the tracking area code of the tracking area in which the relay terminal is registered with the PCell.

[0544] If configured by the upper layer to transmit E.NR SL L3 U2N relay communication, the relay terminal or the remote terminal shall perform the following.

[0545] - Include sl-TxResourceReqL3U2N-Relay in sl-TxResourceReqListCommRelay and configure the fields of this as follows for each destination (as required) for which the network is requested to allocate NR SL L3 U2N relay communication resources:

[0546] - Set sl-DestinationIdentity to the destination ID configured at the upper layer for NR SL L3 U2N relay communication transmission.

[0547] - Set sl-CastType to the cast type of the associated destination ID configured at the upper layer for NR SL L3 U2N relay communication transmission.

[0548] - If the associated two-way SL DRB is configured by the setting in RRCReconfigurationSidelink, set sl-RLC-ModeIndication to include the RLC mode of the RLC mode of the associated SL QoS flow and optionally the QoS profile.

[0549] - Set sl-QoS-InfoList to include the QoS profile of the SL QoS flow of the associated destination configured at the upper layer for NR SL L3 U2N relay communication transmission.

[0550] - Set sl-TxInterestedFreqList to indicate the frequencies of the associated destination for NR SL L3 U2N relay communication transmission.

[0551] - Set sl-TypeTxSyncList to the current synchronization reference type used in the associated sl-InterestedFreqList for NR SL L3 U2N relay communication transmission.

[0552] - When the UECapabilityInformationSidelink message is received from the peer terminal, set sl-CapabilityInformationSidelink to include this message.

[0553] - Include ue-Type and set it to relayUE if the terminal operates as an NR SL L3 U2N relay terminal, or set it to remoteUE otherwise.

[0554] - Include multi-path support / request indication.

[0555] - Include an indication of the RRC state of the relay terminal or whether the relay terminal is in RRC_CONNECTED.

[0556] - Include an indication of the RRC state of the remote terminal or whether the remote terminal is in RRC_CONNECTED.

[0557] - When the terminal operates as an NR SL U2N remote terminal:

[0558] Include the cell ID of the PCell for the relay terminal.

[0559] Include the PLMN ID of the registered PLMN for the relay terminal.

[0560] Include the tracking area code of the tracking area registered by the relay terminal for the PCell.

[0561] - When the terminal operates as an NR SL U2N relay terminal:

[0562] Include the cell ID of the PCell for the remote terminal.

[0563] Include the PLMN ID of the registered PLMN for the remote terminal.

[0564] Include the tracking area code of the tracking area registered by the remote terminal for the PCell.

[0565] When the base station receives a report from a remote terminal and / or a relay terminal (e.g., a MeasurementReport message (Alt 1-1 in FIG. 16) and / or a SidelinkUEInformationNR message of the remote terminal (Alt 1-2 in FIG. 17) and / or a SidelinkUEInformationNR message of the relay terminal (Alt 1-3 in FIG. 18)), the base station determines whether to add an indirect path via the relay terminal for the remote terminal.

[0566] If the relay terminal is not in the RRC_CONNECTED state, the base station can request, for example, via the remote terminal, the relay terminal to start an RRC connection setup. For example, the base station can send the SL message and request the remote terminal to request the relay terminal to start an RRC connection setup.

[0567] Alternatively, if the relay terminal is not in the RRC_CONNECTED state, the base station can page the relay terminal as follows.

[0568] A. If the relay terminal is in RRC_INACTIVE (or RRC_IDLE), the base station sends a paging indication and / or a paging message to page the relay terminal. If the relay terminal is in RRC_IDLE, the base station can transmit the terminal ID of the relay terminal and request the core network (CN) node (e.g., AMF) to page the relay terminal. When requesting, the CN node sends a paging message to the relay terminal by the base station. The request to the CN node includes the source ID or destination ID of the relay terminal.

[0569] B. Alternatively, if the relay terminal is in RRC_INACTIVE (or RRC_IDLE), the base station can send an RRCReconfiguration message including a paging message to the dedicatedPagingDeliver to the remote terminal to page the relay terminal.

[0570] - When the remote terminal receives the message, for example, it starts transmitting a Uu message in the SL and sends a paging message to the relay terminal. The relay terminal receives the paging message from the remote terminal. In this case, the paging message contains a PagingCause indicating "multi-path" or "relay" without a terminal ID. When the relay terminal receives the paging message from the remote terminal in the SL, it starts the RRC connection setup.

[0571] C. The paging indication and / or the paging message contain the terminal ID of the relay terminal (e.g., C-RNTI, ResumeIdentity, s-TMSI or the source ID or destination ID belonging to the relay terminal) and a PagingCause indicating "multi-path" or "U2N relay connection".

[0572] D. After receiving the paging indication and / or the paging message, if the relay terminal is not in the RRC_CONNECTED state and the terminal ID belonging to the relay terminal is included in the paging indication and / or the paging message, the relay terminal starts the RRC connection setup procedure in the cell of the base station and enters the RRC_CONNECTED state.

[0573] 11. If the relay terminal and the remote terminal are not set in the same cell or not registered in the same tracking area and / or the same PLMN, the base station can perform a handover for the relay terminal and / or the remote terminal to move the relay terminal and / or the remote terminal to the same cell, the same tracking area and / or the same PLMN.

[0574] 12. If both the relay terminal and the remote terminal are in the RRC_CONNECTED state and the base station determines whether to add an indirect path via the relay terminal for the remote terminal according to the previous stage, the base station, for example, sends an RRCReconfiguration message to each of the relay terminal and the remote terminal to configure an indirect path via the relay terminal for the remote terminal.

[0575] - If sl-L2RelayUEConfig is included in the RRCReconfiguration message, the relay terminal performs the configuration procedure for the L2 U2N relay terminal and (re)configures zero, one or more indirect bearers and zero, one or more split bearers.

[0576] - If sl-L2RemoteUEConfig is included in the RRCReconfiguration message, the remote terminal performs the configuration procedure for the L2 U2N remote terminal and (re)configures zero, one or more direct bearers and zero, one or more split bearers.

[0577] - The indirect bearer or split bearer includes the configuration of the Uu relay RLC channel.

[0578] - An indirect link composed of a Uu link and an SL is configured for the indirect bearer.

[0579] - The direct bearer is configured by a link that goes only through the Uu.

[0580] - Both an indirect link and a direct link are configured for the split bearer. The base station can select one or both of the indirect link and the direct link for downstream data transmission to the remote terminal, while the remote terminal can select one or both of the indirect link and the direct link for upstream data transmission to the base station.

[0581] (1) Option 1: Joint RRC Reconfiguration

[0582] - The base station sends an RRCReconfiguration message to the relay terminal. The RRCReconfiguration message includes at least a first part and a second part. The first part includes the configuration related to the indirect / split bearer applied to the relay terminal, while the second part includes the configuration related to the indirect / split bearer applied to the remote terminal. The second part may include the configuration related to the direct bearer applied to the remote terminal.

[0583] i) Option 1A: The relay terminal transmits a Uu RRC message (e.g., RRCReconfiguration message) to the remote terminal to convey the second part to the remote terminal.

[0584] For example, the second part is included in the RRC container of the RRCReconfiguration message. The base station encrypts the first part with the first security key set between the base station and the relay terminal, while encrypting the second part with the second security key set between the base station and the remote terminal. After receiving the RRCReconfiguration message, if the relay terminal can successfully apply the configuration of the first part, the layer of the relay terminal removes the first part from the RRCReconfiguration message, transmits the RRCReconfiguration message with the first part removed to the remote terminal, and conveys the second part of the RRC container to the remote terminal. The layer of the relay terminal is any one of the PDCP layer, SRAP layer, and RRC layer of the relay terminal. On the other hand, if the relay terminal cannot successfully apply the configuration of the first part, the relay terminal cannot convey the second part of the RRC container to the remote terminal.

[0585] After receiving the second part, the remote terminal decrypts the second part using the second security key. If the remote terminal can successfully apply the configuration of the second part, the remote terminal encrypts the RRCReconfigurationComplete message using the second security key and then directly transmits it to the base station or indirectly transmits it to the base station through the relay terminal. If the remote terminal fails to apply the configuration of the second part, the remote terminal encrypts the RRCReconfigurationFailure or RRCReconfigurationComplete message indicating the failure of the U2N configuration or the multi-path configuration using the second security key and then directly transmits it to the base station or indirectly transmits it to the base station through the relay terminal. Alternatively, if the remote terminal fails to apply the configuration of the second part, the remote terminal starts an RRC reconfiguration procedure in which the remote terminal directly suspends the bearer and suspends or releases the indirect / split bearer. The remote terminal may release the PC5-RRC connection with the relay terminal.

[0586] In the case of the RRC reconfiguration procedure via the Uu interface, the remote terminal performs a random access to the base station and, as a result of the procedure, only configures the direct bearer. In the RRC reconfiguration procedure, the relay terminal transmits an RRCReestablishmentComplete message indicating the failure of the U2N configuration or the multi-path configuration and the source or destination ID of the relay terminal and / or the remote terminal.

[0587] In the case of the RRC reconfiguration procedure by the relay terminal, the remote terminal transmits an RRCReestablishmentComplete message to the relay terminal using SL-RLC1 for SRB1, and then the relay terminal transmits the RRCReestablishmentComplete message to the base station. The RRCReestablishmentComplete message indicates the failure of the U2N configuration or the multi-path configuration and the source or destination ID of the relay terminal and / or the remote terminal.

[0588] If the remote terminal cannot apply the configuration of the second part, the remote terminal can either release the PC5-RRC connection with the relay terminal or notify the relay terminal of a sidelink relay reconfiguration failure or a multi-path configuration failure.

[0589] Upon receiving the release of the PC5-RRC connection or a sidelink relay reconfiguration failure or a multi-path configuration failure, the relay terminal sends an RRCReconfigurationFailure or RRCReconfigurationComplete message to the base station to notify of the failure of the U2N configuration or the multi-path configuration. The RRC container of the RRCReconfigurationComplete message sent from the relay terminal to the base station can include the RRCReconfigurationComplete message received by the remote terminal. Alternatively, upon receiving or detecting the release of the PC5-RRC connection or a sidelink relay reconfiguration failure or a multi-path configuration failure, or if the relay terminal cannot apply the configuration of the first part, the relay terminal starts an RRC reconfiguration procedure, during which the relay terminal directly aborts the bearer and aborts or releases the indirect / split bearer. The relay terminal can also release the PC5-RRC connection with the remote terminal or notify the remote terminal of a sidelink relay reconfiguration failure or a multi-path configuration failure. In the RRC reconfiguration procedure, the relay terminal performs a random access to the base station and, as a result of the procedure, configures only the direct bearer. In the RRC reconfiguration procedure, the relay terminal sends an RRCReestablishmentComplete message indicating the failure of the U2N configuration or the multi-path configuration and the source or destination ID of the relay terminal and / or the remote terminal.

[0590] ii) Option 1B: The relay terminal sends a PC5 RRC message (e.g., RRCReconfigurationSidelink message or UuMessageTransferSidelink message) to the remote terminal to convey the second part to the remote terminal.

[0591] For example, the second part is included in the RRC container of the RRCReconfiguration message or the UuMessageTransferSidelink message. The base station encrypts the first part with the first security key set between the base station and the relay terminal, and at the same time encrypts the second part with the first security key (or the second security key configured between the base station and the remote terminal). When receiving the RRCReconfiguration message, the relay terminal decrypts the second part using the first security key (or the second security key). Thereafter, the relay terminal encrypts the second part using the third security key set for the PC5 interface between the relay terminal and the remote terminal. The relay terminal includes the second part in the RRCReconfigurationSidelink message transmitted to the remote terminal and transmits the second part to the remote terminal. The second part is included in the RRC container of the RRCReconfigurationSidelink message, or the second part is reconfigured to be included in the RRCReconfigurationSidelink message.

[0592] When receiving the second part, the remote terminal decrypts the second part using the third security key. If the remote terminal can successfully apply the configuration of the second part, the remote terminal encrypts the RRCReconfigurationCompleteSidelink message using the third security key and then transmits it to the relay terminal. If the remote terminal fails to apply the configuration of the second part, the remote terminal encrypts the RCReconfigurationFailureSidelink message indicating the failure of the U2N configuration or the multi-path configuration using the third security key and then transmits it to the relay terminal. Alternatively, if the remote terminal fails to apply the configuration of the second part, the remote terminal starts an RRC reconfiguration procedure in which the remote terminal directly suspends the bearer and suspends or releases the indirect / split bearer. The remote terminal may release the PC5-RRC connection with the relay terminal.

[0593] In the case of an RRC reconfiguration procedure via the Uu interface, the remote terminal performs random access to the base station and directly configures only the bearer as a result of the procedure. In the RRC reconfiguration procedure, the relay terminal transmits an RRCReestablishmentComplete message indicating the failure of the U2N configuration or the multi-path configuration, and the source or destination ID of the relay terminal and / or the remote terminal.

[0594] In the case of an RRC reconfiguration procedure by the relay terminal, after the remote terminal transmits an RRCReestablishmentComplete message to the relay terminal using SL-RLC1 for SRB1, the relay terminal transmits the RRCReestablishmentComplete message to the base station. The RRCReestablishmentComplete message indicates the failure of the U2N configuration or the multi-path configuration, and the source or destination ID of the relay terminal and / or the remote terminal.

[0595] Receive an RRCReconfigurationFailureSidelink message, receive a sidelink relay reconfiguration failure or a multi-path configuration failure, or detect a sidelink failure (e.g., due to expiration of timer T400). If the relay terminal cannot apply the configuration of the first part, the relay terminal shall send an RRCReconfigurationFailure or RRCReconfigurationComplete message to the base station as a U2N configuration or multi-path configuration failure. Alternatively, receive an RRCReconfigurationFailureSidelink message, receive a sidelink relay reconfiguration failure or a multi-path configuration failure, or detect a sidelink failure (e.g., due to expiration of timer T400). If the relay terminal cannot apply the configuration of the first part, the relay terminal shall initiate an RRC reconfiguration procedure to initiate an RRC reconfiguration procedure in which the relay terminal directly suspends the bearer and indirectly / split bearers are suspended or released. The relay terminal can also release the PC5-RRC connection with the remote terminal or notify the remote terminal of a sidelink relay reconfiguration failure or a multi-path configuration failure. In the RRC reconfiguration procedure, the relay terminal shall perform a random access to the base station and, as a result of the procedure, configure only the direct bearer. In the RRC reconfiguration procedure, the relay terminal shall send an RRCReestablishmentComplete message indicating a U2N configuration or multi-path configuration failure and the source or destination ID of the relay terminal and / or the remote terminal.

[0596] In Option 1, when the remote terminal or the relay terminal performs an RRC reconfiguration procedure, it can also inform the base station which UE cannot apply the U2N configuration or the multi-path configuration, i.e., the remote terminal or the relay terminal.

[0597] (2) Option 2: Separate Transmission of RRC Reconfiguration

[0598] - The base station transmits a first RRCReconfiguration message to the relay terminal. The first RRCReconfiguration message includes at least the configuration related to the indirect / split bearer applied to the relay terminal.

[0599] After receiving the first RRCReconfiguration message, if the relay terminal can successfully apply the configuration of the first message, the relay terminal transmits an RRCReconfigurationComplete message to the base station. However, after receiving the first message, if the relay terminal cannot apply the configuration of the first message, or if the PC5-RRC connection is released, or if the sidelink relay reconfiguration failure or multi-path configuration failure is received or detected, the relay terminal starts an RRC reconfiguration procedure in which the relay terminal suspends the direct bearer and either suspends or releases the indirect / split bearer. The relay terminal can also release the PC5-RRC connection with the remote terminal or notify the remote terminal of the sidelink relay reconfiguration failure or multi-path configuration failure. In the RRC reconfiguration procedure, the relay terminal performs a random access to the base station and, as a result of the procedure, configures only the direct bearer. In the RRC reconfiguration procedure, the relay terminal transmits an RRCReestablishmentComplete message indicating the failure of the U2N configuration or multi-path configuration and the source or destination ID of the relay terminal and / or the remote terminal.

[0600] - The base station transmits a second RRCReconfiguration message to the remote terminal. The second RRCReconfiguration message includes the configuration related to the indirect / split bearer applied to the remote terminal. The second RRCReconfiguration message may also include the configuration related to the direct bearer applied to the remote terminal.

[0601] The base station can directly transmit the second RCReconfiguration message from the Uu interface to the remote terminal using SRB1.

[0602] Upon receiving the second message, if the remote terminal can successfully apply the configuration of the second message, the remote terminal sends an RRCReconfigurationComplete message to the base station. If the remote terminal fails to apply the configuration of the second message, the remote terminal directly or indirectly sends an RCReconfigurationFailure or RRCReconfigurationComplete message to inform the base station of the failure of the U2N configuration or the multi-path configuration.

[0603] The RRCReconfigurationComplete or RRCReconfigurationFailure message is sent directly to the base station using SRB1 or indirectly to the base station by the relay terminal using SL-RLC1 for SRB1.

[0604] If the remote terminal fails to apply the configuration of the second message, the remote terminal can release the PC5-RRC connection with the relay terminal or inform the relay terminal of the sidelink relay reconfiguration failure or multi-path configuration failure.

[0605] Alternatively, if the remote terminal fails to apply the configuration of the second message, the remote terminal starts an RRC reconfiguration procedure in which the remote terminal temporarily suspends or releases the direct bearer and temporarily suspends or releases the indirect / split bearer. The remote terminal can also release the PC5-RRC connection with the relay terminal or inform the relay terminal of the sidelink relay reconfiguration failure or multi-path configuration failure.

[0606] In the case of the RRC reconfiguration procedure via the Uu interface, the remote terminal performs random access to the base station and configures only the direct bearer as a result of the procedure. In the RRC reconfiguration procedure, the relay terminal sends an RRCReestablishmentComplete message indicating the failure of the U2N configuration or the multi-path configuration and the source or destination ID of the relay terminal and / or the remote terminal.

[0607] In the case of the RRC reconfiguration procedure by the relay terminal, after the remote terminal transmits an RRCReestablishmentComplete message to the relay terminal using SL-RLC1 for SRB1, the relay terminal forwards the RRCReestablishmentComplete message to the base station. The RRCReestablishmentComplete message indicates a failure of the U2N configuration or the multi-path configuration, and the source or destination ID of the relay terminal and / or the remote terminal.

[0608] When the PC5-RRC connection is released, or a sidelink relay reconfiguration failure or a multi-path configuration failure is received, the relay terminal sends an RRCReconfigurationFailure or RRCReconfigurationComplete message to the base station to notify the failure of the U2N configuration or the multi-path configuration. When receiving an RRCReestablishmentRequest message at the remote terminal, the RRC container of the RRCReconfigurationComplete message transmitted from the relay terminal to the base station can include the RRCReestablishmentRequest message received at the remote terminal.

[0609] Alternatively, if the PC5-RRC connection is released, or if the sidelink relay reconfiguration fails or the multi-path configuration fails are received or detected, or if the relay terminal cannot apply the configuration of the first message, the relay terminal starts an RRC reconfiguration procedure in which the relay terminal directly aborts the bearer and aborts or releases the indirect / split bearer. The relay terminal can also release the PC5-RRC connection with the remote terminal or notify the remote terminal of the sidelink relay reconfiguration failure or the multi-path configuration failure. In the RRC reconfiguration procedure, the relay terminal performs a random access to the base station and, as a result of the procedure, configures only the direct bearer. In the RRC reconfiguration procedure, the relay terminal transmits an RRCReestablishmentComplete message indicating the failure of the U2N configuration or the multi-path configuration and the source or destination ID of the relay terminal and / or the remote terminal. When receiving an RRCReestablishmentRequest message at the remote terminal, the RRC container of the RRCReestablishmentComplete message transmitted from the relay terminal to the base station can include the RRCReestablishmentRequest message received at the remote terminal.

[0610] Alternatively, the base station can indirectly transmit a second RRCReconfiguration message to the relay terminal using the PC5 Relay RLC channel for SRB1, i.e., SL-RLC1.

[0611] After receiving the first RRCReconfiguration message, if the relay terminal can successfully apply the configuration of the first message, the relay terminal transmits the second RRCReconfiguration message received at the base station to the remote terminal. The relay terminal also transmits an RRCReconfigurationComplete message to the base station. However, if the relay terminal fails to apply the configuration of the first message after receiving the first message, or the PC5-RRC connection is released, or the relay terminal receives or detects a sidelink relay reconfiguration failure or a multi-path configuration failure, the relay terminal does not transmit the second RRCReconfiguration message received at the base station to the remote terminal, and the relay terminal starts an RRC reconfiguration procedure in which the relay terminal temporarily suspends the direct bearer and can temporarily suspend or release the indirect / split bearer. The relay terminal can also release the PC5-RRC connection with the remote terminal or notify the remote terminal of a sidelink relay reconfiguration failure or a multi-path configuration failure. In the RRC reconfiguration procedure, the relay terminal performs a random access to the base station and, as a result of the procedure, configures only the direct bearer. In the RRC reconfiguration procedure, the relay terminal transmits an RRCReestablishmentComplete message indicating a failure of the U2N configuration or the multi-path configuration and the source or destination ID of the relay terminal and / or the remote terminal.

[0612] If the relay terminal notifies the remote terminal of a sidelink relay reconfiguration failure or a multi-path configuration failure, the remote terminal starts an RRC reconfiguration procedure in which the remote terminal temporarily suspends the direct bearer and can temporarily suspend or release the indirect / split bearer. The remote terminal can also release the PC5-RRC connection with the relay terminal.

[0613] In the case of the RRC reconfiguration procedure via the Uu interface, the remote terminal performs random access to the base station and directly constitutes only the bearer as a result of the procedure. In the RRC reconfiguration procedure, the relay terminal transmits an RRCReestablishmentComplete message indicating the failure of the U2N configuration or the multi-path configuration and the source or destination ID of the relay terminal and / or the remote terminal.

[0614] In the case of the RRC reconfiguration procedure by the relay terminal, after the remote terminal transmits an RRCReestablishmentComplete message to the relay terminal using SL-RLC1 for SRB1, the relay terminal transmits the RRCReestablishmentComplete message to the base station. The RRCReestablishmentComplete message indicates the failure of the U2N configuration or the multi-path configuration and the source or destination ID of the relay terminal and / or the remote terminal.

[0615] In the above-described stage, the core network (CN) node (e.g., AMF or SMF) can provide a multi-path configuration to the base station and the UE as follows.

[0616] 1) Option 1:

[0617] - When the remote terminal sets up an RRC connection with the base station, the remote terminal transmits an initial NAS message to the CN node. The initial NAS message can indicate the preference of the remote terminal for multi-path operation. Upon receiving the initial NAS message from the remote terminal, the CN node provides the terminal capabilities related to multi-path operation and the NAS configuration related to multi-path to the base station. Upon receiving the terminal capabilities and / or the NAS configuration, the base station determines whether to configure multi-path operation as described above.

[0618] Also, when the relay terminal sets up an RRC connection with the base station, the relay terminal sends an initial NAS message to the CN node. The initial NAS message can indicate the relay terminal's preference for multi-path operation. When the CN node receives the initial NAS message from the relay terminal and also receives the initial NAS message from the remote terminal, the CN node provides the base station with the terminal capabilities related to multi-path operation and the NAS configuration related to multi-path. Upon receiving the terminal capabilities and / or the NAS configuration, the base station determines whether to configure multi-path operation as described above.

[0619] 2) Alternative 2:

[0620] - After the remote terminal sets up an RRC connection with the base station, the base station determines whether to configure multi-path operation as described above. If the base station determines to perform multi-path operation, the base station instructs the CN node of the multi-path operation.

[0621] Upon receiving the instruction from the base station, the CN node provides the base station with the terminal capabilities related to multi-path operation and the NAS configuration related to multi-path. Upon receiving the terminal capabilities and / or the NAS configuration, the base station configures multi-path operation as described above based on the received terminal capabilities and / or NAS configuration.

[0622] Upon receiving the instruction from the base station, the CN node provides the remote terminal and / or the relay terminal with the NAS configuration related to multi-path. The remote terminal and / or the relay terminal configure multi-path operation based on the NAS configuration related to multi-path on the RRC configuration provided by the base station as described above.

[0623] 3) Alternative 3:

[0624] - When the relay terminal sets up an RRC connection with the base station, the relay terminal sends an initial NAS message to the CN node. The initial NAS message can indicate the relay terminal's preference for multi-path operation. When receiving the initial NAS message from the relay terminal, the CN node provides the base station with the terminal capabilities related to multi-path operation and the NAS configuration related to multi-path. Upon receiving the terminal capabilities and / or the NAS configuration, the base station determines whether to configure multi-path operation as described above.

[0625] Also, when the relay terminal sets up an RRC connection with the base station, the remote terminal can also send an initial NAS message to the CN node. The initial NAS message can indicate the remote terminal's preference for multi-path operation. When receiving the initial NAS message from the remote terminal and the initial NAS message from the relay terminal, the CN node provides the base station with the terminal capabilities related to multi-path operation and the NAS configuration related to multi-path. Upon receiving the terminal capabilities and / or the NAS configuration, the base station determines whether to configure multi-path operation as described above.

[0626] According to the present invention, the network can configure multi-path operation for the relay terminal and the remote terminal. In particular, when the terminal can support the U2N relay function by SL, the present invention can handle the failure of the configuration according to the present invention.

[0627] The present invention is advantageous in that the system can appropriately apply multi-path operation including direct and indirect links by U2N relay. In the prior art, there is no mechanism to provide side-link relay for multi-path operation.

[0628] FIG. 19 shows a method for a first UE (user equipment) to set up a multi-radio communication path in an embodiment of the present invention.

[0629] Referring to FIG. 19, the first UE performs a procedure for setting up a direct path connected to the network (1905).

[0630] The first UE receives configuration information regarding an indirect path between the first UE and the network in an RRC (radio resource control) connected state in which a direct path is configured (1910).

[0631] The first UE receives a sidelink message from a second UE configured as a relay UE for the indirect path (1915).

[0632] Preferably, based on the failure information being included in the sidelink message from the second UE, the first UE performs bearer suspension for a first bearer associated with the indirect path.

[0633] Preferably, the failure information is related to a configuration failure for the indirect path.

[0634] Preferably, the first bearer is an indirect bearer.

[0635] Preferably, the first bearer is a split bearer, and while the direct path of the first bearer is not suspended, the indirect path of the first bearer is suspended.

[0636] Preferably, the first UE performs an RRC reconfiguration procedure based on the failure information included in the sidelink message.

[0637] Preferably, the sidelink message is received directly from the second UE via a sidelink interface between the first UE and the second UE.

[0638] Preferably, the sidelink interface between the first UE and the second UE is released based on the failure information included in the sidelink message.

[0639] Preferably, the sidelink message includes information indicating that the sidelink message is related to the multi-path configuration of the first UE.

[0640] Preferably, the first UE reports the setup failure for the indirect path to the network via the direct path based on the failure information included in the sidelink message.

[0641] Preferably, the first UE operates as a remote UE in the indirect path.

[0642] Hereinafter, a more specific description will be given with reference to the drawings. In the following figures / descriptions, the same reference numerals exemplify the same or corresponding hardware blocks, software blocks, or functional blocks unless otherwise specifically mentioned.

[0643] FIG. 20 illustrates a communication system applicable to the present invention.

[0644] Referring to FIG. 20, the communication system 1 applied to the present invention includes a wireless device, a base station, and a network. Here, the wireless device means a device that communicates using a wireless access technology (for example, 5G NR (New RAT), LTE (Long Term Evolution)), and is also referred to as a communication / wireless / 5G device. Without being limited thereto, the wireless devices include a robot 100a, vehicles 100b-1, 100b-2, XR (Extended Reality) devices 100c, a hand-held device 100d, home appliances 100e, IoT (Internet of Thing) devices 100f, and an AI device / server 400. For example, the vehicles include vehicles equipped with a wireless communication function, autonomous driving vehicles, vehicles capable of vehicle-to-vehicle communication, etc. Here, the vehicles include UAVs (Unmanned Aerial Vehicles) (for example, drones). The XR devices include AR (Augmented Reality) / VR (Virtual Reality) / MR (Mixed Reality) devices, and are embodied in the form of an HMD (Head-Mounted Device), a HUD (Head-Up Display) equipped in a vehicle, a TV, a smartphone, a computer, a wearable device, a home appliance, a digital signage, a vehicle, a robot, etc. The hand-held devices include smartphones, smart pads, wearable devices (for example, smartwatches, smart glasses), computers (for example, notebook personal computers, etc.). The home appliances include TVs, refrigerators, washing machines, etc. The IoT devices include sensors, smart meters, etc. For example, the base station and the network are also embodied in the wireless device, and a specific wireless device 200a can also operate as a base station / network node for other wireless devices.

[0645] Wireless devices 100a to 100f are connected to network 300 via base station 200. AI (Artificial Intelligence) technology is applied to wireless devices 100a to 100f, and wireless devices 100a to 100f are connected to AI server 400 via network 300. Network 300 is configured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR) network, or the like. Wireless devices 100a to 100f can communicate with each other via base station 200 / network 300, but can also communicate directly without going through the base station / network (e.g., sidelink communication). For example, vehicles 100b-1 and 100b-2 can communicate directly (e.g., V2V (Vehicle to Vehicle) / V2X (Vehicle to everything) communication). Also, IoT devices (e.g., sensors) can communicate directly with other IoT devices (e.g., sensors) or other wireless devices 100a to 100f.

[0646] Wireless communications / connections 150a, 150b, and 150c are performed between wireless devices 100a to 100f / base station 200 and between base stations 200 / 200. Here, the wireless communications / connections are uplink / downlink communication 150a, sidelink communication 150b (or D2D communication), and inter-base station communication 150c (e.g., performed by various radio access technologies such as relay and IAB (Integrated Access Backhaul) (e.g., 5G NR). Through wireless communications / connections 150a, 150b, and 150c, wireless devices and base stations / wireless devices, and base stations and base stations can send / receive wireless signals to / from each other. For example, wireless communications / connections 150a, 150b, and 150c can send / receive signals via various physical channels. For this purpose, based on various proposals of the present invention, any one of a setting process of various configuration information for sending / receiving wireless signals, various signal processing processes (e.g., channel encoding / decoding, modulation / demodulation, resource mapping / demapping, etc.), and a resource allocation process is performed.

[0647] FIG. 21 illustrates a wireless device applicable to the present invention.

[0648] Referring to FIG. 21, the first wireless device 100 and the second wireless device 200 transmit and receive wireless signals by various wireless access technologies (e.g., LTE, NR). Here, {the first wireless device 100, the second wireless device 200} corresponds to {the wireless device 100x, the base station 200} in FIG. 20 and / or {the wireless device 100x, the wireless device 100x}.

[0649] The first wireless device 100 includes one or more processors 102 and one or more memories 104, and further includes one or more transceivers 106 and / or one or more antennas 108. The processor 102 controls the memory 104 and / or the transceiver 106, and is configured to implement the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification. For example, after the processor 102 processes the information in the memory 104 to generate a first piece of information / signal, the transceiver 106 transmits a wireless signal including the first piece of information / signal. Also, after the processor 102 receives a wireless signal including a second piece of information / signal by the transceiver 106, the information obtained from the signal processing of the second piece of information / signal is stored in the memory 104. The memory 104 is connected to the processor 102 and stores various information related to the operation of the processor 102. For example, the memory 104 stores software code including instructions for performing part or all of the processes controlled by the processor 102, or for performing the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification. Here, the processor 102 and the memory 104 are part of a communication modem / circuit / chip designed to implement wireless communication technologies (e.g., LTE, NR). The transceiver 106 is connected to the processor 102 and transmits and / or receives wireless signals through one or more antennas 108. The transceiver 106 includes a transmitter and / or a receiver. The transceiver 106 can also be used interchangeably with an RF (radio Frequency) unit. In the present invention, the wireless device can also mean a communication modem / circuit / chip.

[0650] Specifically, the UE includes a processor 102 and a memory 104 that are coupled to the RF transceiver. The memory 104 includes at least one program capable of performing operations related to the embodiments shown in FIGS. 11 to 27.

[0651] Alternatively, a chipset including a processor 102 and a memory 104 is configured. In this case, the chipset includes at least one processor and at least one memory that is operably coupled to the at least one processor and causes the at least one processor to operate when executed.

[0652] The second wireless device 200 includes one or more processors 202 and one or more memories 204, and further includes one or more transceivers 206 and / or one or more antennas 208. The processor 202 controls the memory 204 and / or the transceiver 206, and is configured to implement the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification. For example, after the processor 202 processes the information in the memory 204 to generate third information / signals, the transceiver 206 transmits a wireless signal including the third information / signals. Also, after the processor 202 receives a wireless signal including fourth information / signals by the transceiver 206, the information obtained from the signal processing of the fourth information / signals is stored in the memory 204. The memory 204 is coupled to the processor 202 and stores various information related to the operation of the processor 202. For example, the memory 204 stores software code that performs some or all of the processes controlled by the processor 202, or includes instructions for performing the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification. Here, the processor 202 and the memory 204 are part of a communication modem / circuit / chip designed to implement wireless communication technologies (e.g., LTE, NR). The transceiver 206 is coupled to the processor 202 and transmits and / or receives wireless signals via one or more antennas 208. The transceiver 206 includes a transmitter and / or a receiver. The transceiver 206 can also be used interchangeably with an RF unit. In the present invention, a wireless device also means a communication modem / circuit / chip.

[0653] Hereinafter, the hardware elements of the wireless devices 100 and 200 will be described in more detail. Although not limited thereto, one or more protocol layers are implemented by one or more processors 102 and 202. For example, one or more processors 102 and 202 implement one or more layers (for example, functional layers such as PHY, MAC, RLC, PDCP, RRC, and SDAP). One or more processors 102 and 202 generate one or more PDUs (Protocol Data Units) and / or one or more SDUs (Service Data Units) according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification. One or more processors 102 and 202 generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification. One or more processors 102 and 202 generate a signal (for example, a baseband signal) including a PDU, an SDU, a message, control information, data, or information according to the functions, procedures, proposals, and / or methods disclosed in this specification, and provide it to one or more transceivers 106 and 206. One or more processors 102 and 202 receive a signal (for example, a baseband signal) from one or more transceivers 106 and 206, and can obtain PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification.

[0654] One or more processors 102, 202 are also referred to as a controller, microcontroller, microprocessor, or microcomputer. One or more processors 102, 202 are implemented by hardware, firmware, software, or a combination thereof. As an example, one or more ASICs (Application Specific Integrated Circuits), one or more DSPs (Digital Signal Processors), one or more DSPDs (Digital Signal Processing Devices), one or more PLDs (Programmable Logic Devices), or one or more FPGAs (Field Programmable Gate Arrays) are included in one or more processors 102, 202. The descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification are implemented using firmware or software, and the firmware or software is implemented to include modules, procedures, functions, etc. The firmware or software configured to perform the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification is included in one or more processors 102, 202, or stored in one or more memories 104, 204 and driven by one or more processors 102, 202. The descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification are implemented using firmware or software in the form of code, instruction, and / or set of instructions.

[0655] One or more memories 104, 204 are coupled to one or more processors 102, 202 and store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. The one or more memories 104, 204 are constituted by ROM, RAM, EPROM, flash memory, hard drive, register, cache memory, computer-readable storage medium, and / or combinations thereof. The one or more memories 104, 204 are located inside and / or outside the one or more processors 102, 202. Also, the one or more memories 104, 204 are coupled to the one or more processors 102, 202 by various techniques such as wired or wireless connection.

[0656] One or more transceivers 106, 206 transmit user data, control information, radio signals / channels, etc. mentioned in this specification, such as methods and / or flowcharts, to one or more other devices. One or more transceivers 106, 206 receive user data, control information, radio signals / channels, etc. mentioned in the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification from one or more other devices. For example, one or more transceivers 106, 206 are connected to one or more processors 102, 202 and transmit and receive radio signals. For example, one or more processors 102, 202 control one or more transceivers 106, 206 to transmit user data, control information, or radio signals to one or more other devices. Also, one or more processors 102, 202 control one or more transceivers 106, 206 to receive user data, control information, or radio signals from one or more other devices. One or more transceivers 106, 206 are connected to one or more antennas 108, 208, and one or more transceivers 106, 206 are configured to transmit and receive user data, control information, radio signals / channels, etc. mentioned in the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification by one or more antennas 108, 208. In this specification, one or more antennas are multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers 106, 206 convert received radio signals / channels, etc. from RF band signals to baseband signals (Convert) in order to process received user data, control information, radio signals / channels, etc. using one or more processors 102, 202. One or more transceivers 106, 206 convert user data, control information, radio signals / channels, etc. processed using one or more processors 102, 202 from baseband signals to RF band signals. For this purpose, one or more transceivers 106, 206 include (analog) oscillators and / or filters.

[0657] FIG. 22 illustrates another example of a wireless device to which this invention is applied. The wireless device can be embodied in various forms depending on usage examples / services (see FIG. 20).

[0658] Referring to FIG. 22, the wireless devices 100 and 200 correspond to the wireless devices 100 and 200 in FIG. 21 and are composed of various elements, components, units / parts, and / or modules. For example, the wireless devices 100 and 200 include a communication unit 110, a control unit 120, a memory unit 130, and additional elements 140. The communication unit includes a communication circuit 112 and a transceiver 114. For example, the communication circuit 112 includes one or more processors 102 and 202 and / or one or more memories 104 and 204 in FIG. 21. For example, the transceiver 114 includes one or more transceivers 106 and 206 and / or one or more antennas 108 and 208 in FIG. 21. The control unit 120 is electrically connected to the communication unit 110, the memory unit 130, and the additional elements 140 and controls various operations of the wireless device. For example, the control unit 120 controls the electrical / mechanical operations of the wireless device based on programs / codes / instructions / information stored in the memory unit 130. Also, the control unit 120 transmits the information stored in the memory unit 130 to the outside (e.g., other communication devices) through a wireless / wired interface by the communication unit 110, or stores the information received from the outside (e.g., other communication devices) through a wireless / wired interface by the communication unit 110 in the memory unit 130.

[0659] The additional elements 140 are variously configured depending on the type of the wireless device. For example, the additional elements 140 include any one of a power unit / battery, an input / output unit (I / O unit), a driving unit, and a computer unit. Without being limited thereto, the wireless device is embodied in the form of a robot (FIGS. 20, 100a), a vehicle (FIGS. 20, 100b-1, 100b-2), an XR device (FIGS. 20, 100c), a portable device (FIGS. 20, 100d), a home appliance (FIGS. 20, 100e), an IoT device (FIGS. 20, 100f), a digital broadcast terminal, a hologram device, a public safety device, an MTC device, a medical device, a fintech device (or financial device), a security device, a climate / environment device, an AI server / device (FIGS. 20, 400), a base station (FIGS. 20, 200), and a network node, etc. The wireless device is movable depending on the usage example / service or is used at a fixed location.

[0660] In FIG. 22, various elements, components, units / parts, and / or modules within the wireless devices 100 and 200 are all connected to each other by a wired interface, or at least some of them are wirelessly connected by the communication unit 110. For example, within the wireless devices 100 and 200, the control unit 120 and the communication unit 110 are wired-connected, and the control unit 120 and the first units (e.g., 130, 140) are wirelessly connected by the communication unit 110. Also, each element, component, unit / part, and / or module within the wireless devices 100 and 200 further includes one or more elements. For example, the control unit 120 is composed of one or more sets of processors. For example, the control unit 120 is composed of a set including a communication control processor, an application processor, an ECU (Electronic Control Unit), a graphic processing processor, a memory control processor, etc. As another example, the memory unit 130 is composed of RAM (Random Access Memory), DRAM (Dynamic RAM), ROM (Read Only Memory), flash Memory, volatile Memory, non-volatile memory, and / or a combination thereof.

[0661] FIG. 23 illustrates a vehicle or an autonomous driving vehicle to which the present invention is applied. The vehicle or the autonomous driving vehicle is embodied as a mobile robot, a vehicle, a train, an aerial vehicle (AV), a ship, etc.

[0662] Referring to FIG. 23, the vehicle or the autonomous driving vehicle 100 includes an antenna unit 108, a communication unit 110, a control unit 120, a driving unit 140a, a power supply unit 140b, a sensor unit 140c, and an autonomous driving unit 140d. The antenna unit 108 is composed of a part of the communication unit 110. Each of the blocks 110 / 130 / 140a to 140d corresponds to the blocks 110 / 130 / 140 in FIG. 21.

[0663] The communication unit 110 transmits and receives signals (such as data, control signals, etc.) to and from external devices such as other vehicles, base stations (e.g., base stations, roadside units, etc.), and servers. The control unit 120 controls elements of the vehicle or autonomous driving vehicle 100 to perform various operations. The control unit 120 includes an ECU (Electronic Control Unit). The driving unit 140a enables the vehicle or autonomous driving vehicle 100 to travel on the ground. The driving unit 140a includes an engine, a motor, a power train, wheels, brakes, a steering device, and the like. The power supply unit 140b supplies power to the vehicle or autonomous driving vehicle 100 and includes a wired / wireless charging circuit, a battery, and the like. The sensor unit 140c can obtain vehicle state, surrounding environment information, user information, and the like. The sensor unit 140c includes an IMU (Inertial Measurement Unit) sensor, a collision sensor, a wheel sensor, a speed sensor, an inclination sensor, a weight sensing sensor, a heading sensor, a position module, a vehicle forward / backward sensor, a battery sensor, a fuel sensor, a tire sensor, a steering sensor, a temperature sensor, a humidity sensor, an ultrasonic sensor, an illuminance sensor, a pedal position sensor, and the like. The autonomous driving unit 140d implements technologies such as maintaining the lane during driving, automatically adjusting the speed like an adaptive cruise control, automatically driving along a predetermined route, and automatically setting and driving along a route when a destination is set.

[0664] As an example, the communication unit 110 receives map data, traffic information data, etc. from an external server. The autonomous driving unit 140d generates an autonomous driving route and a drive plan based on the obtained data. The control unit 120 controls the drive unit 140a so that the vehicle or the autonomous driving vehicle 100 moves along the autonomous driving route according to the drive plan (for example, speed / direction adjustment). The communication unit 110 periodically obtains the latest traffic information data from the external server during autonomous driving and also obtains traffic information data of surrounding vehicles from the surrounding vehicles. Further, the sensor unit 140c obtains vehicle state and surrounding environment information during autonomous driving. The autonomous driving unit 140d updates the autonomous driving route and the drive plan based on the newly obtained data / information. The communication unit 110 transmits information regarding the vehicle position, the autonomous driving route, the drive plan, etc. to the external server. The external server can predict traffic information data in advance using AI technology or the like based on the information collected from the vehicle or the autonomous driving vehicle and provide the predicted traffic information data to the vehicle or the autonomous driving vehicle.

[0665] Here, the wireless communication technology implemented in the wireless device (XXX, YYY) of this specification includes not only LTE, NR, and 6G, but also Narrowband Internet of Things for low-power communication. At this time, for example, NB-IoT technology is an example of LPWAN (Low Power Wide Area Network) technology, and is implemented in standards such as LTE Cat NB1 and / or LTE Cat NB2, and is not limited to the above-mentioned names. Further or alternatively, the wireless communication technology implemented in the wireless device (XXX, YYY) of this specification communicates based on LTE-M technology. At this time, as an example, LTE-M technology is an example of LPWAN technology, and is also called by various names such as eMTC (enhanced Machine Type Communication). For example, LTE-M technology is implemented in any of various standards such as 1) LTE CAT0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-BL (non-Bandwidth Limited), 5) LTE-MTC, 6) LTE Machine Type Communication, and / or 7) LTE M, and is not limited to the above-mentioned names. Further or alternatively, the wireless communication technology implemented in the wireless device (XXX, YYY) of this specification includes any one of ZigBee (registered trademark), Bluetooth (registered trademark), and Low Power Wide Area Network (LPWAN) considering low-power communication, and is not limited to the above-mentioned names. As an example, ZigBee technology generates PAN (personal area networks) related to small / low-power digital communication based on various standards such as IEEE802.15.4, and is called by various names.

[0666] The embodiments described above combine the components and features of the present invention in a predetermined form. Each component or feature is considered optional unless otherwise explicitly stated. Each component or feature can be implemented in a form that does not combine with other components or features, or some components and / or features can be combined to form embodiments of the present invention. The order of operations described in the embodiments of the present invention may be changed. Some components and features of one embodiment may be included in other embodiments, or may replace corresponding components or features of other embodiments. It is obvious that claims not explicitly cited in the claims can be combined to form embodiments or included as new claims by amendment after filing.

[0667] In this specification, the embodiments of this invention are mainly described centering on the signal transmission and reception relationship between the terminal and the base station. Such a transmission and reception relationship can be similarly / identically extended to the signal transmission and reception between the terminal and the relay or between the base station and the relay. The specific operations assumed to be performed by the base station in this document may in some cases be performed by its upper node. That is, it is obvious that various operations performed for communication with the terminal in a network composed of a plurality of network nodes including the base station can be performed by the base station or other network nodes other than the base station. The base station may be referred to by terms such as fixed station, Node b, eNode b (eNB), access point, etc. Also, the terminal may be referred to by terms such as UE (User Equipment), MS (Mobile Station), MSS (Mobile Subscriber Station), etc.

[0668] Embodiments according to the present invention are implemented by various means, such as hardware, firmware, software, or combinations thereof. In the case of implementation by hardware, one embodiment of the present invention is implemented by one or more ASICs (application specific integrated circuits), DSPs (digital signal processors), DSPDs (digital signal processing devices), PLDs (programmable logic devices), FPGAs (field programmable gate arrays), processors, controllers, microcontrollers, microprocessors, etc.

[0669] In the case of implementation by firmware or software, one embodiment of the present invention is implemented in the form of modules, procedures, functions, etc. that perform the functions or operations described above. The software code is stored in a memory and driven by a processor. The memory unit is provided inside or outside the processor and exchanges data with the processor by various known means.

[0670] It is obvious to those skilled in the art that the present invention can be embodied in other specific forms without departing from the features of the present invention. Therefore, the above detailed description should not be construed restrictively in all aspects and should be considered as exemplary. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all changes within the equivalent scope of the present invention are included in the scope of the present invention.

Industrial Applicability

[0671] The present invention can be applied to terminals, base stations, or other devices in a wireless mobile communication system.

Claims

1. In a wireless communication system, a method for a first UE (user equipment) to set up a multi-hop wireless communication path, comprising: executing a procedure for setting up a direct path connected to a network; receiving configuration information for an indirect path between the first UE and the network in an RRC (radio resource control) connected state where the direct path is set up; receiving a sidelink message from a second UE configured as a relay UE for the indirect path; based on the failure information being included in the sidelink message from the second UE, the first UE suspends a first bearer related to the indirect path.

2. The method according to claim 1, wherein the failure information is related to a failure in setting up the indirect path.

3. The method according to claim 1, wherein the first bearer is an indirect bearer.

4. The method according to claim 1, wherein the first bearer is a split bearer, and the indirect path of the first bearer is suspended while the direct path of the first bearer is not suspended.

5. The method according to claim 1, further comprising performing an RRC reconfiguration procedure based on the failure information included in the sidelink message.

6. The method according to claim 1, wherein the sidelink message is received directly from the second UE via a sidelink interface between the first UE and the second UE.

7. The method according to claim 1, wherein the sidelink interface between the first UE and the second UE is released based on the failure information included in the sidelink message.

8. The method according to claim 1, wherein the sidelink message includes information indicating that the sidelink message is related to the multi-hop path configuration of the first UE.

9. The method according to claim 1, further comprising reporting a failure in setting up the indirect path to the network via the direct path based on the failure information included in the sidelink message.

10. The method according to claim 1, wherein the first UE operates as a remote UE in the indirect path.

11. A computer-readable medium that stores instructions that, when executed by a processor, cause the processor to perform the method according to claim 1.

12. An apparatus for wireless communication, comprising a memory configured to store instructions and a processor configured to execute the instructions to perform operations, wherein the operations performed by the processor include executing a procedure for setting a direct path connected to a network and receiving configuration information for an indirect path between the apparatus and the network in an RRC (radio resource control) connected state in which the direct path is set, including receiving a sidelink message from another apparatus configured as a relay apparatus for the indirect path, and based on the failure information being included in the sidelink message from the other apparatus, the apparatus performs bearer suspension for a first bearer related to the indirect path.

13. The apparatus according to claim 12, further comprising a transceiver configured to transmit or receive signals under the control of the processor.

14. The apparatus according to claim 12, wherein the apparatus is an ASIC (application-specific integrated circuit) or a digital signal processor.

15. The apparatus according to claim 12, wherein the apparatus is a UE (user equipment) operating in a 3GPP (registered trademark) (3rd generation partnership project) based wireless communication system.

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