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

Abstract

In the present invention, the method includes an operation of configuring a split bearer including a first radio path directly connected to a network and a second radio path indirectly connected to the network by a relay terminal, and an operation of transmitting an RRC (Radio Resource Control) message to the network via a basic path for the split bearer. When configuring the split bearer, the basic path for the split bearer is determined to be the first radio path according to the type of the split bearer, which is a specific type of SRB (Signaling Radio Bearer) that transmits the RRC message.

Description

Technical Field

[0001] The present invention relates to a wireless communication system, and more specifically, to a method and an 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 assist communication with multiple users. Examples of multiple access systems include a CDMA (code division multiple access) system, an FDMA (frequency division multiple access) system, a TDMA (time division multiple access) system, an OFDMA (orthogonal frequency division multiple access) system, an SC-FDMA (single carrier frequency division multiple access) system, an MC-FDMA (multi carrier frequency division multiple access) system, 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 the 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 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.

[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 before 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 CAM of the periodic message type and / or a DENM of the event triggered message type to other terminals.

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

[0009] Subsequently, various V2X scenarios have been defined in NR in relation to V2X communication. 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 groups and move together. For example, in order to perform platoon operations based on vehicle platooning, the vehicles belonging to the group receive periodic data from the leading vehicle. For example, the vehicles belonging to the group can use the periodic data to reduce or increase the inter-vehicle distance.

[0011] For example, based on improved driving, the vehicle is semi-automated or fully automated. Each vehicle can adjust its trajectories or maneuvers based on data obtained from local sensors of neighboring vehicles and / or neighboring logical entities. For example, each vehicle can share its driving intention 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 it can sense 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 a 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, and remote driving are being discussed in V2X communication based on NR. 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 achieved by the present invention are not limited to the above technical problems, and other technical problems not mentioned will be clearly understandable to those having 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 remote terminal (UE) to perform communication includes an operation of configuring a split bearer including a first radio path directly connected to a network and a second radio path indirectly connected to the network by a relay terminal, and an operation of transmitting an RRC (Radio Resource Control) message to the network via a basic path for the split bearer. When configuring the split bearer, the basic path for the split bearer is determined to be the first radio path according to the type of the split bearer which is a specific type of SRB (Signaling Radio Bearer) for transmitting the RRC message.

[0018] Preferably, the method further includes an operation of receiving an RRC configuration message for configuring the split bearer, and the RRC configuration message for configuring the split bearer related to the specific type of SRB always configures the basic path with the first radio path.

[0019] Preferably, the specific type is SRB1 for an RRC message using a DCCH (dedicated control channel) logical channel.

[0020] Preferably, the specific type is SRB2 for a NAS (non access stratum) message using a DCCH logical channel.

[0021] Preferably, the method further includes an operation of receiving an RRC configuration message for configuring the split bearer, and a basic path of the split bearer is determined for the first radio path based on the RRC configuration message in order to configure the split bearer without configuring a basic path.

[0022] Preferably, the method further includes an operation of receiving an RRC configuration message for configuring the split bearer, and a basic path of the split bearer is determined for the first radio path regardless of a basic path configured by the RRC configuration message.

[0023] Preferably, the method further includes an operation of receiving an RRC configuration message for configuring the split bearer, configuring the split bearer based on the RRC configuration message, and adding the first radio path to the remote terminal.

[0024] Preferably, the method further includes an operation of receiving an RRC configuration message for configuring the split bearer, and when a type of the split bearer is a data radio bearer (DRB) type, the basic path is determined for the second radio path based on the RRC configuration message.

[0025] Preferably, the method further includes an operation of receiving an RRC configuration message for configuring the split bearer, and the RRC configuration message is received via the second radio path.

[0026] 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.

[0027] According to another aspect of the present invention, there is provided an apparatus configured to perform the method.

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

Advantages of the Invention

[0029] According to the present invention, the wireless signal transmission and reception procedure can be accurately and efficiently performed. For example, even if split bearers for the first wireless path and the second wireless path are configured without indicating a basic path, the basic path of the split bearer can be clearly determined for a specific SRB type.

[0030] 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 with ordinary knowledge in the technical field to which the present invention pertains from the following description.

Brief Description of Drawings

[0031]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

DETAILED DESCRIPTION OF THE INVENTION

[0032] 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 so on.

[0033] For background technology, terms, definitions, and abbreviations related to this invention, the following documents can be referred to.

[0034] 3GPP (Registered Trademark) LTE

[0035] - 3GPP TS 36.211: Physical channels and modulation

[0036] - 3GPP TS 36.212: Multiplexing and channel coding

[0037] - 3GPP TS 36.213: Physical layer procedures

[0038] - 3GPP TS 36.214: Physical layer; Measurements

[0039] - 3GPP TS 36.300: Overall description

[0040] - 3GPP TS 36.304: User Equipment (UE) procedures in idle mode

[0041] - 3GPP TS 36.314: Layer 2 - Measurements

[0042] - 3GPP TS 36.321: Medium Access Control (MAC) protocol

[0043] - 3GPP TS 36.322: Radio Link Control (RLC) protocol

[0044] - 3GPP TS 36.323: Packet Data Convergence Protocol (PDCP)

[0045] - 3GPP TS 36.331: Radio Resource Control (RRC) protocol

[0046] 3GPP NR

[0047] - 3GPP TS 38.211: Physical channels and modulation

[0048] - 3GPP TS 38.212: Multiplexing and channel coding

[0049] - 3GPP TS 38.213: Physical layer procedures for control

[0050] - 3GPP TS 38.214: Physical layer procedures for data

[0051] - 3GPP TS 38.215: Physical layer measurements

[0052] - 3GPP TS 38.300: Overall description

[0053] - 3GPP TS 38.304: User Equipment (UE) procedures in idle mode and in RRC inactive state

[0054] - 3GPP TS 38.321: Medium Access Control (MAC) protocol

[0055] - 3GPP TS 38.322: Radio Link Control (RLC) protocol

[0056] - 3GPP TS 38.323: Packet Data Convergence Protocol (PDCP)

[0057] - 3GPP TS 38.331: Radio Resource Control (RRC) protocol

[0058] - 3GPP TS 37.324: Service Data Adaptation Protocol (SDAP)

[0059] - 3GPP TS 37.340: Multi-connectivity; Overall description

[0060] Sidelink (SL) refers to a communication method that directly establishes a link between terminals (User Equipment, UE) and enables direct communication of voice or data between terminals without going through a base station (Base Station, BS). Sidelink is one solution to address the burden on the base station caused by rapidly increasing data traffic.

[0061] V2X (vehicle-to-everything) means a communication technology that exchanges information with other vehicles, pedestrians, infrastructure-based things, etc. 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.

[0062] On the other hand, as more communication devices demand larger communication capacities, the need for improved mobile broadband communication compared to existing radio access technologies (RAT) is emerging. Accordingly, communication systems considering services or terminals sensitive to reliability and latency are being discussed. Next-generation radio access technologies considering enhanced mobile broadband communication, massive MTC, URLLC (Ultra-Reliable and Low Latency Communication), etc. are called new radio access technology (new radio) or NR (new radio). V2X (vehicle-to-everything) communication can also be supported in NR.

[0063] 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.

[0064] 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, including low-frequency bands below 1 GHz, intermediate-frequency bands from 1 GHz to 10 GHz, and high-frequency (millimeter-wave) bands above 24 GHz.

[0065] For a clearer explanation, the description will center around LTE-A or 5G NR, but the technical idea according to an embodiment of the present invention is not limited to these.

[0066] 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.

[0067] 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).

[0068] 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, and more specifically, is connected to the MME (mobility management entity) through S1-MME and to the S-GW (Serving gateway) through S1-U.

[0069] EPC30 consists 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 E-UTRAN as an endpoint, and the P-GW is a gateway with a PDN (Packet Date Network) as an endpoint.

[0070] The radio interface protocol layer between the terminal and the network is 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.

[0071] Figure 3 shows the structure of the NR system.

[0072] 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 including only the gNB is illustrated in Figure 3. The gNB and the eNB are connected to each other through an Xn interface. The gNB and the eNB are connected to the fifth-generation core network (5G Core Network: 5GC) through an NG interface. More specifically, the AMF (access and mobility management function) is connected through an NG-C interface, and the UPF (user plane function) is connected through an NG-U interface.

[0073] FIG. 4 shows the structure of the NR radio frame.

[0074] 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 by means of a CP (cyclic prefix).

[0075] When normal CP is used, each slot contains 14 symbols. When extended CP is used, each slot contains 12 symbols. Here, the symbols include OFDM symbols (or CP-OFDM symbols), SC-FDMA symbols (or DFT-s-OFDM symbols).

[0076] 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.

[0077]

Table 1

[0078] 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.

[0079]

Table 2

[0080] 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. Thereby, 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.

[0081] In NR, a number of numerologies or SCSs for supporting various 5G services are supported. 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.

[0082] 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 are changeable. 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).

[0083]

Table 3

[0084] 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, it is used for communication for vehicles (e.g., autonomous driving).

[0085]

Table 4

[0086] Figure 5 is a diagram showing the slot structure of the NR frame.

[0087] 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.

[0088] A carrier wave includes a plurality of sub-carriers in the frequency domain. An RB (Resource Block) is defined as a plurality (e.g., 12) of consecutive sub-carriers in the frequency domain. A BWP is defined as a plurality of consecutive (P)RBs ((Physical) Resource Block) in the frequency domain and corresponds to one numerology (e.g., SCS, CP length, etc.). A carrier wave 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.

[0089] 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.

[0090] Hereinafter, V2X or SL (sidelink) communication will be described.

[0091] 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.

[0092] Hereinafter, the Sidelink Synchronization Signal (SLSS) and synchronization information will be described.

[0093] The SLSS, as an SL-specific sequence, includes a PSSS (Primary Sidelink Synchronization Signal) and an SSSS (Secondary Sidelink Synchronization Signal). 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 and acquires synchronization using the S-PSS. For example, a terminal acquires detailed synchronization and detects the synchronization signal ID using the S-PSS and the S-SSS.

[0094] 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 related to SLSS, duplex mode (DM), TDD UL / DL (Time Division Duplex Uplink / Downlink) configuration, information related to resource pools, types of applications related to SLSS, subframe 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.

[0095] The 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 a pre-set SL BWP (Sidelink BWP). For example, the bandwidth of the S-SSB is 11 RBs (Resource Blocks). For example, the PSBCH spans 11 RBs. 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.

[0096] On the one hand, in the NR SL system, a plurality of numerologies having 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 for the transmitting terminal. For example, the S-SSB transmission period is 160 ms. For example, for all SCSs, a 160-ms S-SSB transmission period is supported.

[0097] 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.

[0098] 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.

[0099] 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 section of the S-SSB.

[0100] Figure 7 shows a terminal for performing V2X or SL communication.

[0101] Referring to Figure 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.

[0102] 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 within the resource pool.

[0103] 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.

[0104] Generally, a resource pool consists of a plurality of resource units, and each terminal selects one or more resource units for its own SL signal transmission.

[0105] FIG. 8 shows resource units for V2X or SL communication.

[0106] Referring to FIG. 8, the entire frequency resource of the resource pool is divided into NF, and the entire time resource of the resource pool is divided into NT. Therefore, 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.

[0107] As shown in FIG. 8, one resource unit (for example, 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 resource unit structure, the resource pool means a set of resource units available for transmission by a terminal attempting to transmit an SL signal.

[0108] The resource pool can be subdivided into various types. For example, according to the content of the SL signal transmitted from each resource pool, the resource pool can be classified as follows.

[0109] (1) Scheduling Assignment (SA) is a signal that contains 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 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 with SL data. SA is also called the SL control channel.

[0110] (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 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.

[0111] (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 be discovered by adjacent terminals.

[0112] Even when the content of the foregoing 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.

[0113] SL DRX (sidelink discontinuous reception)

[0114] SL supports SL DRX for unicast, groupcast, and broadcast. Define similar parameters (on-duration, inactivity-timer, retransmission-timer, cycle) for Uu for SL 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 inactive time, the terminal may skip SCI monitoring for data reception.

[0115] The actual parameters supported for each cast type (unicast, groupcast, broadcast) are specified in the following subsections.

[0116] The SL active time of the RX terminal includes the time when an SL on - duration timer, an SL inactive timer, or an SL retransmission timer applicable to (one of unicast, groupcast, or broadcast) is running. 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 regarded as the SL active time of the RX terminal.

[0117] For each source / destination L2 ID pair for unicast or each destination L2 ID for groupcast / broadcast, the TX terminal maintains a timer set corresponding to the SL DRX timer of the RX terminal. 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.

[0118] In the case of unicast, SL DRX is set for each pair of source L2 ID and destination L2 ID.

[0119] 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:

[0120] - The RX terminal can transmit assistance information including a desired on - duration timer, an SL DRX start offset, and an SL DRX period to the TX terminal, and the mode 2 TX terminal can use this to determine the SL DRX setting for the RX terminal.

[0121] 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 setting for the RX terminal. In the case of a TX terminal in RRC_CONNECTED that uses mode 1 resource allocation, the SL DRX setting for the RX terminal is determined by the serving base station of the TX terminal.

[0122] - The TX terminal transmits to the RX terminal the SL DRX setting used by the RX terminal.

[0123] - The RX terminal accepts or rejects the SL DRX setting.

[0124] The basic SL DRX setting (default SL DRX configuration) for groupcast / broadcast is used in the DCR message.

[0125] 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 setting in a dedicated RRC signal at the base station, it transmits the SL DRX setting to the RX terminal. When the RX terminal is in RRC_CONNECTED, the RX terminal reports the received SL DRX setting to its serving base station, for example, for the alignment of Uu settings and SL DRX settings.

[0126] 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 values for each of these timers, the SL HARQ RTT timer value is derived from the retransmission resource timing.

[0127] The SL DRX MAC CE is introduced for SL DRX operation with unicast only.

[0128] For groupcast / broadcast, SL DRX is configured commonly among multiple terminals based on the QoS profile and the destination L2 ID. Multiple SL DRX configurations can be supported for each groupcast / broadcast.

[0129] 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 configured 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 configured for each QoS profile or destination L2 ID. For 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 configured for that L2 ID. For groupcast and broadcast, when multiple QoS profiles are configured 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.

[0130] 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.

[0131] The common basic SL DRX setting between groupcast and broadcast is used for QoS profiles that are not mapped to non-default SL DRX settings.

[0132] TX terminals and RX terminals within the coverage of RRC_IDLE / RRC_INACTIVE acquire their SL DRX settings in the SIB. (TX or RX) terminals in RRC_CONNECTED acquire 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 acquired by pre-configuration.

[0133] In the case of groupcast, when a TX terminal receives new data with 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).

[0134] 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. A TX terminal assumes SL DRX for an RX terminal only if the associated TX profile corresponds to SL DRX support. An RX terminal determines that SL DRX is used if there is an associated TX profile corresponding to SL DRX support for all destination L2 IDs of interest.

[0135] 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.

[0136] 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.

[0137] 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 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.

[0138] RRC sets the following parameters to control the SL DRX operation.

[0139] - sl-drx-onDurationTimer: Duration at the start of the SL DRX cycle

[0140] - sl-drx-SlotOffset: Delay time before the start of sl-drx-onDurationTimer

[0141] - sl-drx-InactivityTimer (except for broadcast transmission): 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

[0142] - sl-drx-RetransmissionTimer (per SL process except for broadcast transmission): Maximum period until receiving an SL retransmission

[0143] - sl-drx-StartOffset: The slot at which the SL DRX cycle starts

[0144] - sl-drx-Cycle: SL DRX cycle

[0145] - sl-drx-HARQ-RTT-Timer (per SL process excluding broadcast transmission): The minimum period before the MAC entity anticipates an SL HARQ retransmission

[0146] When SL DRX is configured, the active time includes the following times.

[0147] - The time when the sl-drx-onDurationTimer or sl-drx-InactivityTimer is running, or

[0148] - The time when the sl-drx-RetransmissionTimer is running, or

[0149] - When the SL-CSI report MAC CE is not received, the sl-LatencyBoundCSI-Report interval set by RRC, or

[0150] - When the 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

[0151] - Slots related to the known periodic transmissions of the terminal that transmits SL-SCH data.

[0152] When one or more SL DRXs are configured, the MAC entity performs the following.

[0153] 1> When multiple SL DRX periods mapped to multiple SL-QoS-Profile of the destination Layer-2 ID and the interested cast type are related to multicast and broadcast:

[0154] 2> Among multiple SL DRX periods mapped to multiple SL-QoS-Profile related to the destination Layer-2 ID, select the sl-drx-Cycle with the shortest length.

[0155] 2> Among multiple SL DRX onduration timers mapped to multiple SL-QoS-Profile related to the destination Layer-2 ID, select the sl-drx-onDurationTimer with the longest length.

[0156] 1> When the sl-drx-HARQ-RTT-Timer expires:

[0157] 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:

[0158] 3> After the sl-drx-HARQ-RTT-Timer expires, start the sl-drx-RetransmissionTimer for the SL process in the first slot.

[0159] When the cast type is multicast or broadcast as instructed by the upper layer, sl-drx-StartOffset and sl-drx-SlotOffset are derived from the following formula.

[0160] sl-drx-StartOffset (ms) = Destination Layer-2 ID modulo sl-drx-Cycle (ms).

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

[0162] 1> When the SL DRX cycle is used and [(DFN Х 10) + subframe number] modulo (sl-drx-Cycle) = sl-drx-StartOffset:

[0163] 2> Start sl-drx-onDurationTimer after sl-drx-SlotOffset from the start of the subframe.

[0164] 1> When SL DRX is the active time:

[0165] 2> Monitor the SCI (i.e., one-step SCI and two-step SCI) in this SL DRX.

[0166] 2> When the SCI indicates a new SL transmission:

[0167] 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:

[0168] 4> Start or restart sl-drx-InactivityTimer for the source Layer-2 ID and destination Layer-2 ID pair after the first slot of SCI reception.

[0169] 3> When the destination Layer-1 ID of the SCI (i.e., two-step 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:

[0170] 4> Select the sl-drx-InactivityTimer with the longest length among the multiple SL DRX inactivity timers mapped to the destination Layer-2 IDs associated with the destination Layer-1 ID of the SCI.

[0171] 4> After the first slot of SCI reception, start or resume the sl-drx-InactivityTimer for its destination Layer-2 ID.

[0172] 2> When the SCI indicates an SL transmission:

[0173] 3> When no PSFCH resource is configured for the SL grant associated with the SCI:

[0174] 4> Start the sl-drx-HARQ-RTT-Timer for the SL process in the slot after the transmission of the PSSCH (i.e., the currently received PSSCH) has ended.

[0175] 3> When a PSFCH resource is configured for the SL grant associated with the SCI:

[0176] 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;

[0177] 5> After the transmission of the PSFCH for transmitting the SL HARQ feedback has ended, start the sl-drx-HARQ-RTT-Timer for the SL process in the first slot. Or

[0178] 5> When the SL HARQ feedback is not transmitted according to the UL / SL priority, after the PSFCH resource for the SL HARQ feedback is terminated, start the sl-drx-HARQ-RTT-Timer for that SL process in the first slot.

[0179] 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;

[0180] 5> After the PSFCH transmission for transmitting the SL HARQ feedback is completed, start the sl-drx-HARQ-RTT-Timer for that SL process in the first slot. Or

[0181] 5> When the SL HARQ feedback is not transmitted according to the UL / SL priority, after the PSFCH resource for the SL HARQ feedback is terminated, start the sl-drx-HARQ-RTT-Timer for that SL process in the first slot. Or

[0182] 5> When the SL HARQ feedback is a positive acknowledgment, after the PSFCH resource for the SL HARQ feedback is terminated, start the sl-drx-HARQ-RTT-Timer for that SL process in the first slot.

[0183] 4> When the SCI deactivates the HARQ feedback and the resources for one or more retransmission opportunities are not scheduled by the SCI:

[0184] 5> Start the sl-drx-HARQ-RTT-Timer for that SL process in the slot after the PSFCH resource is terminated.

[0185] 4> When HARQ feedback is deactivated in SCI and resources for one or more retransmission opportunities are scheduled by SCI:

[0186] 5> Start the sl-drx-HARQ-RTT-Timer for that SL process in the slot after the transmission of PSSCH (i.e., the currently received PSSCH) has ended.

[0187] Reference: When 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 SCI). The terminal uses the configured sl-drx-HARQ-RTT-Timer when SCI does not indicate the next transmission resource.

[0188] 3> Abort the sl-drx-RetransmissionTimer for that SL process.

[0189] 1> When an SL DRX command MAC CE for a unicast source Layer-2 ID and destination Layer-2 ID pair is received:

[0190] 2> Abort the sl-drx-onDurationTimer for the unicast source Layer-2 ID and destination Layer-2 ID pair.

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

[0192] Inter-UE Coordination (IUC)

[0193] 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.

[0194] - In IUC mode 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.

[0195] - In IUC mode 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.

[0196] In mode 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 mode. 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 may be based on the detection result of terminal - B (if available) and the adjustment information received at terminal - A, or may be based only on the adjustment information received at terminal - A. In the case of mode 1, IUC can be transmitted using MAC CE and two - stage SCI or MAC CE only. Explicit requests and reports for IUC are supported in unicast mode.

[0197] In mode 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 that 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 re - select using the collision resources and excludes the collision resources from the re - selected resources. In the case of mode 2, PSFCH is used to transmit IUC.

[0198] The adjustment request (SL-IUC Req) transmission procedure between SL terminals is used to trigger the transmission of adjustment information between SL terminals of a peer UE.

[0199] The adjustment information (SL-IUC Info) reporting procedure between SL terminals is used to provide adjustment information between terminals to a peer UE.

[0200] - sl-LatencyBoundIUC-Report is maintained for each PC5-RRC connection.

[0201] The MAC entity maintains sl-IUC-ReportTimer for each pair of source Layer-2 ID and destination Layer-2 ID corresponding to a 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.

[0202] The MAC entity performs the following for each pair of source Layer-2 ID and destination Layer-2 ID corresponding to a PC5-RRC connection set in the upper layer.

[0203] 1> When the SL-IUC information report is triggered by an SL-IUC request MAC CE (and / or SCI) and has not been cancelled:

[0204] 2> When the sl-IUC-ReportTimer is not running for the triggered SL-IUC information report:

[0205] 3> Start the sl-IUC-ReportTimer.

[0206] 2> When the sl-IUC-ReportTimer has expired for the triggered SL-IUC information report:

[0207] 3> Cancel the triggered SL-IUC information report.

[0208] 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 sub-header:

[0209] 3> As defined in 6.1.3.35, in the multiplexing and assembly procedure, instruct to generate the adjustment information MAC CE between SL terminals.

[0210] 3> Abort the sl-IUC-ReportTimer for the triggered SL-IUC information report.

[0211] 3> Cancel the triggered SL-IUC information report.

[0212] Figure 9 shows the adjustment information MAC CE between terminals.

[0213] The adjustment information MAC CE between terminals is identified by a MAC sub-header having the LCID specified in Table 5.

[0214]

Table 5

[0215] 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.

[0216] - 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.

[0217] - 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.

[0218] - LSIi: This field is the code point value of the SCI format 2-C lowestIndices field, indicating the lowest subchannel index for the first resource position of each TRIV. LSI0 indicates the lowest subchannel index for the first resource position of TRIV within the first resource combination, and LSI1 indicates the lowest subchannel index for the first resource position of 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.

[0219] - 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.

[0220] - 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 contains the firstResourceLocation field using the LSB bits.

[0221] - R: Reserved bit, set to 0.

[0222] Figure 10 shows the adjustment request MAC CE between terminals.

[0223] The adjustment request MAC CE between terminals is identified by a MAC sub-header 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.

[0224] - 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.

[0225] - 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 contains the resourceReservationPeriod field using the LSB bits.

[0226] - 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.

[0227] - 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.

[0228] - 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.

[0229] - R: Reserved bit, set to 0.

[0230] SL Relay

[0231] 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.

[0232] 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.

[0233] U2N Relay Terminal: A terminal that provides a function to assist in network connection to a U2N remote terminal.

[0234] U2N Remote Terminal: A terminal that communicates with the network through a U2N relay terminal.

[0235] Upstream: The direction from the IAB topology towards the parent node.

[0236] 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 relay between the L2 terminal and the network.

[0237] The U2N relay terminal needs to be in the RRC_CONNECTED state to relay unicast data.

[0238] For L2 U2N relay operation, the following combinations of RRC states are supported.

[0239] - The U2N relay terminal and the U2N remote terminal can only transmit / receive relayed unicast data after both are in the RRC CONNECTED state.

[0240] - 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.

[0241] In the case of L2 U2N relay, the U2N remote terminal is set to use only resource allocation mode 2 for the data to be relayed.

[0242] 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.

[0243] Protocol Stack of SL Relay

[0244] Figure 11 shows (a) the user plane protocol stack and (b) the control plane protocol stack of the L2 terminal - network relay.

[0245] The protocol stacks for the user plane and control plane of the L2 U2N relay architecture are shown in FIGS. 11(a) and (b). The SRAP sub - array is placed on the RLC sub - layer for both CP and UP in 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).

[0246] In the case of the L2 U2N relay, the SRAP sub - layer for the PC5 hop is only for bearer mapping. The SRAP sub - layer does not exist on the PC5 hop for relaying the messages of the L2 U2N remote terminal in BCCH and PCCH. For the L2 U2N remote terminal messages of SRB0, the SRAP sub - layer does not exist on the PC5 hop, but the SRAP sub - layer exists on the Uu hop for both DL and UL.

[0247] In the case of the L2 U2N relay, uplink:

[0248] - 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 relays via the L2 U2N relay terminal Uu interface. In the case of uplink relay traffic, other end-to-end RBs (SRB or DRB) between the same remote terminal and / or other terminals of other remote terminals are multiplexed via the same Uu relay RLC channel.

[0249] - 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.

[0250] - 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.

[0251] In the case of L2 U2N relay, downlink:

[0252] - 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 the radio bearers (SRB or DRB) of multiple terminals 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.

[0253] - 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 related PC5 Relay RLC channel.

[0254] - The PC5 SRAP sublayer of the relay terminal assists in DL bearer mapping between the received Uu Relay RLC channel and the transmitted PC5 Relay RLC channel.

[0255] - The PC5 SRAP sublayer of the remote terminal correlates the received packets to the specific PDCP entity related to the correct Uu radio bearer of the remote terminal based on the ID information included in the Uu SRAP header.

[0256] 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. The 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.

[0257] 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.

[0258] FIG. 12 shows a protocol stack of discovery messages for relay between a terminal and a network.

[0259] 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.

[0260] 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.

[0261] 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.

[0262] 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.

[0263] Whether a resource pool used for NR SL communication is used for relay discovery or the network can configure a resource pool dedicated to relay discovery. A resource pool dedicated to relay discovery and a resource pool for NR SL communication can be configured simultaneously through system information, dedicated signaling, and / or presetting. 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 a resource pool for NR SL communication is configured, all configured transmission resource pools can be used for relay discovery and SL communication.

[0264] 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 discovery messages.

[0265] Relay discovery reuses 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.

[0266] SL power control for transmitting relay discovery messages is performed in the same way as NR SL communication.

[0267] PDCP layer encryption or integrity protection is not applied to relay discovery messages.

[0268] The terminal determines whether the base station supports relay discovery, non-relay discovery, or both through SIB12.

[0269] Relay Selection / Reselection

[0270] The U2N remote terminal performs wireless measurements at the PC5 interface and uses this, 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 uses SD-RSRP measurements to evaluate whether the PC5 link quality to the U2N relay terminal meets the relay selection criteria.

[0271] 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.

[0272] 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 suitable U2N relay terminal candidates that meet 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.

[0273] In the following cases, the U2N remote terminal triggers U2N relay selection.

[0274] - When the direct Uu signal strength of the current serving cell of the U2N remote terminal is lower than the set signal strength threshold.

[0275] - When instructed by the upper layer of the U2N remote terminal.

[0276] In the following cases, the U2N remote terminal triggers U2N relay reselection.

[0277] - When the PC5 signal strength of the current U2N relay terminal is lower than the (pre-set) signal strength threshold.

[0278] - When the U2N relay terminal notifies cell (re)selection, handover or Uu RLF by the PC5-RRC signal.

[0279] - When the remote terminal receives a PC5-S link release message from the U2N relay terminal.

[0280] - When the U2N remote terminal detects PC5 RLF.

[0281] - When instructed by the upper layer.

[0282] For the L2 U2N remote terminal and L3 U2N remote terminal in RRC_IDLE / INACTIVE, the cell (re)selection procedure and the relay (re)selection procedure are performed independently. When 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.

[0283] 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 remote terminal to which they are connected. 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 Uu RLF. When receiving a 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.

[0284] Control Plane Procedure for L2 U2N Relay

[0285] 1) RRC Connection Management

[0286] The U2N remote terminal needs to configure its PDU session / DRB with the network before transmitting user plane data.

[0287] 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.

[0288] The Uu configuration procedure for relay between the L2 terminal and the network is applicable to the configuration of the Uu SRB1 / SRB2 and DRB of the U2N remote terminal.

[0289] 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.

[0290] 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.

[0291] 2. The U2N remote terminal uses the specified PC5 relay RLC channel configuration to send the first RRC message (i.e., RRCSetupRequest) for its connection setup with the base station by the relay terminal. If the U2N relay terminal is not in RRC_CONNECTED, when receiving a message on the specified PC5 relay RLC channel, it needs to perform its own connection setup. During the RRC connection setup procedure of the relay terminal, the base station can configure the Uu relay RLC channel for relaying SRB0 to the U2N relay terminal. The base station responds to the U2N remote terminal with an RRCSetup message. The RRCSetup message is sent to the U2N remote terminal using the SRB0 relay channel via Uu and the specified PC5 relay RLC channel via PC5.

[0292] 3. The base station and the U2N relay terminal perform a relay channel configuration procedure via Uu. According to the configuration from the base station, the U2N relay / remote terminal configures the PC5 relay RLC channel for relaying SRB1 to the U2N remote / relay terminal via PC5.

[0293] 4. The RRCSetupComplete 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 configured for the U2N relay terminal via Uu. Thereafter, the U2N remote terminal is RRC-connected via Uu.

[0294] 5. The U2N remote terminal and the base station set up security through the Uu procedure, and the security message is relayed by the U2N relay terminal.

[0295] 6. The base station sends an RRCReconfiguration message to the U2N remote terminal via the U2N relay terminal to configure the SRB2 / DRB for relaying 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 relayed traffic.

[0296] 2) Radio Link Failure

[0297] The U2N remote terminal in the RRC_CONNECTED state aborts the Uu RLM when it is connected to the base station by the U2N relay terminal.

[0298] The U2N relay terminal declares a Radio Link Failure (RLF) according to the same criteria.

[0299] After the RLF is declared, the U2N relay terminal performs the following operations.

[0300] - A PC5-RRC message is used to send an instruction to the U2N remote terminal connected to the U2N relay terminal, which triggers an RRC connection reconfiguration for the U2N remote terminal.

[0301] When detecting a PC5 RLF, the U2N remote terminal triggers a connection reconfiguration.

[0302] 3) RRC Connection Reconfiguration

[0303] The U2N remote terminal performs the following operations during the RRC connection reconfiguration procedure.

[0304] - If only a suitable cell is available, the U2N remote terminal starts the RRC reconfiguration procedure for the suitable cell.

[0305] - 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.

[0306] - 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 according to the implementation.

[0307] 4) Re-establishment of RRC connection

[0308] The RRC connection re-establishment mechanism is applied to the U2N remote terminal.

[0309] 5) System information

[0310] U2N remote terminals within the coverage can obtain all necessary SIBs via the Uu interface regardless of the PC5 connection with the relay terminal. After the PC5 connection with the U2N relay terminal is established, the U2N remote terminal may receive system information from the relay terminal.

[0311] U2N remote terminals in the RRC_CONNECTED state can request SIBs from the U2N relay terminal using an 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 an on-demand SI / SIB acquisition procedure according to its own RRC state (if necessary) and sends the SI / SIBs obtained by PC5-RRC to the U2N remote terminal.

[0312] The SIBs used by an RRC_IDLE or RRC_INACTIVE U2N remote terminal (for example, for the purpose of a relay) can be requested at the U2N remote terminal (from the U2N relay terminal or the network). In the case of an SIB requested by the U2N remote terminal from the U2N relay terminal, the U2N relay terminal re-transmits it if there is an update to the requested SIB. In the case of an RRC_CONNECTED U2N remote terminal, it is the responsibility of the network to transmit the updated SIB to the U2N remote terminal during an update. When the U2N remote terminal enters the RRC_CONNECTED state, it cancels the SI request with the U2N relay terminal.

[0313] 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 an RRC_IDLE or RRC_INACTIVE U2N remote terminal.

[0314] For an L2 U2N remote terminal in the RRC_IDLE or RRC_INACTIVE state, short messages via the Uu interface are not transmitted from the L2 U2N relay terminal to the L2 U2N remote terminal. The L2 U2N relay terminal can transmit the PWS SIB to the L2 U2N remote terminal connected to it.

[0315] 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 a discovery message before setting up a PC5-RRC connection.

[0316] 6) Paging

[0317] 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.

[0318] 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.

[0319] - 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.

[0320] - 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).

[0321] 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 at the U2N remote terminal.

[0322] 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.

[0323] The U2N relay terminal can transmit paging to the U2N remote terminal via PC5 using unicast signaling.

[0324] 7) Access Control

[0325] 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.

[0326] 8) Mobility Registration Update and RAN Area Update

[0327] 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. When the serving cell of the 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.

[0328] Service Continuity for L2 U2N Relay

[0329] 1) Switching from an indirect path to a direct path

[0330] Figure 14 shows the procedure for the U2N remote terminal to switch directly to the Uu cell.

[0331] For the service continuity of the L2 U2N relay, when the U2N remote terminal switches to the direct path, the following procedure is performed.

[0332] 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, serving cell ID (i.e., NCGI) of the U2N relay terminal, and SL measurement quantity information. The SL measurement quantity is the SL-RSRP of the serving U2N relay terminal, and if SL-RSRP is not available, SD-RSRP is used.

[0333] 2. The base station decides to switch the U2N remote terminal to the direct Uu path.

[0334] 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 aborts the UP and CP transmissions by the U2N relay terminal.

[0335] 4. The U2N remote terminal performs random access in synchronization with the base station.

[0336] 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, the terminal (i.e., the previous-stage U2N remote terminal) uses the RRC connection via the direct path to the base station.

[0337] 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 stages 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 setting between the PC5 RLC and the Uu RLC).

[0338] 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 the sixth stage, 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 the third stage.

[0339] 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 switching, DL / UL lossless transmission is performed according to the PDCP data recovery procedure.

[0340] 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.

[0341] 2) Switching from the direct path to the indirect path

[0342] Figure 15 shows the procedure for the U2N remote terminal to switch to the indirect path.

[0343] 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 switching.

[0344] 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.

[0345] 1. After measuring / discovering candidate U2N relay terminals, the U2N remote terminal reports one or more candidate U2N relay terminals and Uu measurement values.

[0346] - The terminal can appropriately filter the U2N relay terminals according to the relay selection criteria before reporting. The terminal needs to report only the candidate U2N relay terminals that meet the upper layer criteria.

[0347] - 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.

[0348] 2. The base station decides to switch the U2N remote terminal to the target U2N relay terminal. Thereafter, 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.

[0349] 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.

[0350] 4. The U2N remote terminal sets up a PC5 connection with the target U2N relay terminal.

[0351] 5. The U2N remote terminal sends an RRCReconfigurationComplete message to the base station via the relay terminal to complete the path switching procedure.

[0352] 6. The data path is switched from a direct path to an indirect path between the U2N remote terminal and the base station.

[0353] 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 sends 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 the 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 steps must be performed before the two steps.

[0354] SL Discovery

[0355] The terminal can perform NR SL discovery while inside or outside the coverage for non - relay operation.

[0356] The relay discovery mechanism (excluding the transmission of discovery messages based on U2N - relay - specific thresholds) is also applicable to SL discovery.

[0357] Multi-Path Operation

[0358] FIG. 16 is a diagram for explaining a method of setting up a U2N bearer for an L2 U2N remote terminal and an L2 U2N relay terminal.

[0359] The method by which a remote terminal forms a multi - path including a direct path and an indirect path and performs data transmission and reception based on the multi - path includes the following steps.

[0360] 1. The U2N remote terminal and the U2N relay terminal perform a discovery procedure and set up a PC5 - RRC connection using the NR V2X procedure (S161).

[0361] 2. After setting up the PC5-RRC connection through the PC5 unicast link configuration, the remote terminal and the relay terminal can trigger the side-link terminal capability transmission procedure where the remote terminal sends a UECapabilityEnquirySidelink message requesting the MP capability of the relay terminal to the relay terminal, and the relay terminal sends a UECapabilityInformationSidelink message including the MP capability to the remote terminal, and they can exchange their terminal capabilities. After that, the relay terminal sends a UECapabilityEnquirySidelink message requesting the MP capability of the remote terminal to the remote terminal, and the remote terminal sends a UECapabilityInformationSidelink message including the MP capability to the relay terminal.

[0362] The MP capability of the terminal includes any one or more of the following.

[0363] - Whether the terminal supports multi-path operation as a remote terminal and / or a relay terminal

[0364] - SL / UL / DL frequency carriers / bands that the terminal can support for MP operation for transmission and / or reception

[0365] - Combinations of SL carriers / bands and UL carriers / bands that the terminal can support for MP operation for its own transmission

[0366] - Combinations of SL carriers / bands and DL carriers / bands that the terminal can support for MP operation for its own reception

[0367] Based on the above-exchanged side-link terminal capabilities, the relay terminal confirms that both the relay terminal and the remote terminal support the MP capability. When the remote terminal is in the RRC_CONNECTED state, the relay terminal that is not in the RRC_CONNECTED state can start the RRC connection setup procedure.

[0368] 3. When there is no direct Uu RRC connection to the U2N remote terminal, the U2N remote terminal uses the specified PC5 relay RLC channel configuration to send a first RRC message (i.e., RRCSetupRequest) to set up a connection with the base station through the relay terminal. If the U2N relay terminal is not in the RRC_CONNECTED state, when it receives a message on the specified PC5 relay RLC channel, it needs to perform its own connection setup. During the RRC connection setup procedure of the relay terminal, the base station can configure a Uu relay RLC channel to relay SRB0 to the U2N relay terminal. The base station responds to the U2N remote terminal with an RRCSetup message. The RRCSetup message is sent to the U2N remote terminal using the SRB0 relay channel via Uu and the specified PC5 relay RLC channel via PC5 (S163).

[0369] 4. The base station and the U2N relay terminal perform a relay channel setup procedure via Uu. According to the settings of the base station, the U2N relay / remote terminal configures a PC5 relay RLC channel to relay SRB1 to the U2N remote / relay terminal via PC5 (S164).

[0370] 5. The RRCSetupComplete 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 configured for the U2N relay terminal via Uu. After this, the U2N remote terminal is RRC-connected via Uu (S165).

[0371] 6. The U2N remote terminal and the base station set up security according to the Uu procedure, and the security messages are transmitted by the U2N relay terminal (S166).

[0372] 7. The U2N remote terminal notifies the base station of the terminal capabilities of the remote terminal, for example, whether the remote terminal supports U2N bearer / channel and / or MP operations.

[0373] 8. The U2N relay terminal notifies the base station of the terminal capabilities of the relay terminal, including, for example, whether the relay terminal supports U2N bearer / channel and / or MP operation.

[0374] 9. The base station indirectly sends an RRCReconfiguration message to the U2N remote terminal via the U2N relay terminal to configure SRB2 / DRB for relay purposes and / or configure SL DRX (S162). The U2N remote terminal sends an RRCReconfigurationComplete message to the base station via the U2N relay terminal as a response. Also, the base station configures an additional Uu relay RLC channel between the base station and the U2N relay terminal and a PC5 relay RLC channel between the U2N relay terminal and the U2N remote terminal for relay traffic.

[0375] 10. The remote terminal uses the Uu relay RLC channel and the PC5 relay RLC channel to send upstream data to the base station via the relay terminal. The base station uses the Uu relay RLC channel and the PC5 relay RLC channel to send downstream data to the remote terminal via the relay terminal.

[0376] 11. The relay terminal can also notify the remote terminal of any one or more of the following by means of sidelink messages.

[0377] - The cell ID of the PCell for the relay terminal.

[0378] - The PLMN ID of the registered PLMN for the relay terminal.

[0379] - The tracking area code of the tracking area registered by the relay terminal for the PCell.

[0380] A. When the relay terminal and the remote terminal are composed of different serving cells, different tracking areas, and / or different PLMNs from each other, the remote terminal and / or the relay terminal shall inform the base station about one or more different serving cells, different tracking areas, and / or different PLMNs, for example, by means of the SidelinkUEInformationNR message.

[0381] B. The sidelink message is a RemoteUEInformationSidelink message, a UEAssistanceInformationSidelink message, an RRCReconfigurationSidelink message, or an RRCReconfigurationCompleteSidelink message.

[0382] 12. The remote terminal can receive system information from the relay terminal. Based on the received system information, the remote terminal can identify whether the serving cell of the relay terminal can support sidelink resources for sidelink transmission / reception and / or MP operation (for example, by the resource pool configuration or dedicated signal of the system information).

[0383] In the DL / UL carrier of the serving cell and the SL carrier where sidelink transmission and / or sidelink reception between the remote terminal and the relay terminal are performed, when the remote terminal and the relay terminal support MP operation or the serving cell supports sidelink resources for sidelink transmission / reception and / or MP operation (for example, by the configuration of the resource pool of the system information or dedicated signal), the remote terminal can perform any one or more of the following steps.

[0384] - If the serving cell of the relay terminal indicated by the received system information is different from the serving cell on which the remote terminal camps on, the remote terminal reselects the cell indicated according to the cell reselection process or aborts the multi-path operation with the relay terminal. If the remote terminal cannot reselect the cell indicated according to the cell reselection process, the remote terminal aborts the multi-path operation with the relay terminal.

[0385] - If the tracking area of the relay terminal indicated by the received system information is different from the tracking area in which the remote terminal is registered, the remote terminal can trigger a tracking area update procedure, register in the tracking area indicated by the system information, or abort the multi-path operation with the relay terminal. If the remote terminal cannot register in the tracking area indicated due to the failure of the tracking area update procedure or other related NAS procedures, the remote terminal aborts the multi-path operation with the relay terminal.

[0386] - If the PLMN of the relay terminal indicated by the received system information is different from the PLMN in which the remote terminal is registered, the remote terminal reselects and registers the PLMN indicated by the relay terminal or aborts the multi-path operation with the relay terminal. For example, if the remote terminal cannot register in the PLNN indicated due to the failure of the PLMN registration procedure or other related NAS procedures, the remote terminal aborts the multi-path operation with the relay terminal.

[0387] A. The relay terminal can send a PC5-RRC message such as a RemoteUEInformationSidelink message, a UEAssistanceInformationSidelink message, an RRCReconfigurationSidelink message, or an RRCReconfigurationCompleteSidelink message to notify the remote terminal of the serving cell, tracking area, and / or PLMN of the relay terminal.

[0388] 13. The remote terminal is set by the network to derive the NR SL measurement results of the serving L2 relay terminal or candidate L2 U2N relay terminal related to the measurement object set in measObjectRelay.

[0389] 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 measIdList in VarMeasConfig as follows and starts the measurement reporting procedure.

[0390] A. When measObject is related to an L2 U2N relay terminal, the remote terminal performs the corresponding measurement related to the candidate relay terminal at the frequency indicated by the related measObject (as described in 5.5.3.4 of TS38.331). When performing the measurement, the terminal filters the measurement results based on layer 3 filtering (as described in 5.5.3.2 of TS38.331) before using them for reporting criteria evaluation or measurement reporting for the measured quantities of each candidate L2 U2N relay terminal.

[0391] B. For the measured quantities of each L2 U2N relay terminal to be derived, the remote terminal performs the following.

[0392] - Derive the measured 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,

[0393] - Apply layer 3 filtering (as described in 5.5.3.2 of TS38.331).

[0394] C. When the measObject is related to an L2 U2N relay terminal:

[0395] - When eventY1-Relay is set in the reportConfig; or

[0396] - When the reportType set as periodical is included in the reportConfig: The remote terminal shall consider all L2 U2N relay terminals detected at the relevant frequency as applicable to this measId.

[0397] The ReportType (or, event type) is determined or set based on Tables 6 to 10 below.

[0398]

Table 6

[0399]

Table 7

[0400]

Table 8

[0401]

Table 9-1

Table 9-2

[0402]

Table 10-1

Table 10-2

[0403] In a state where the D.VarMeasReportList does not contain a measurement report item for this measId (the first L2 U2N relay terminal triggers the event), when reportType is set to eventTriggered, and the item conditions applicable to this event, i.e., 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 performs the following.

[0404] - Include a measurement report item in the VarMeasReportList for this measId.

[0405] - Set the numberOfReportsSent defined in the VarMeasReportList for this measId to 0.

[0406] - Include the L2 U2N relay terminals related to the relaysTriggeredList defined in the VarMeasReportList for this measId.

[0407] - Start the measurement reporting procedure as follows.

[0408] Otherwise, when reportType is set to eventTriggered, and the item conditions applicable to this event, i.e., 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 not included in the relaysTriggeredList (subsequent L2 U2N relay terminals trigger the event), the remote terminal performs the following.

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

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

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

[0412] E. Otherwise, if the reportType is set to eventTriggered and the detachment condition applicable to this event is met for all measurements after layer 3 filtering performed during the timeToTrigger defined for this event in the VarMeasConfig for one or more of the L2 U2N relay terminals included in the relaysTriggeredList defined in the VarMeasReportList for this measId, the remote terminal shall do the following.

[0413] - Remove the relevant L2 U2N relay terminal from the relaysTriggeredList defined in the VarMeasReportList for this measId.

[0414] - If reportOnLeave is set to true for the said reporting setting, start the measurement reporting procedure as follows.

[0415] - If the relaysTriggeredList defined in the VarMeasReportList for this measId is empty: remove the measurement report items in the VarMeasReportList for this measId; if the periodic reporting timer for this measId is running, stop it;

[0416] When F.reportType is set to periodical and the (first) measurement result is available:

[0417] - If reportAmount exceeds 1: 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, the terminal starts the measurement reporting procedure as shown in 5.5.5.

[0418] - Otherwise (i.e., if reportAmount is 1): Immediately after the amount to be reported becomes available for the NR SpCell and the strongest cell among the cells, or for the NR SpCell and the strongest L2 U2N relay terminal among the applicable L2 U2N relay terminals, the terminal starts the measurement reporting procedure as shown in 5.5.5; or, 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), the terminal starts the measurement reporting procedure as in the following step.

[0419] 14. In the previous step, when starting the measurement reporting procedure, for the measId for which the measurement reporting procedure was triggered, the terminal sets the measResults in the MeasurementReport message as follows, and then the remote terminal sends the MeasurementReport message to the network via the SRB.

[0420] A. If the terminal is connected to the L2 U2N relay terminal by a PC5-RRC connection (i.e., if the terminal is an L2 U2N remote terminal), the terminal needs to set sl-MeasResultServingRelay to include the SL-RSRP of the serving L2 U2N relay terminal.

[0421] - If there is no data transmission from the serving L2 U2N relay terminal to the L2 U2N remote terminal, when setting sl-MeasResultServingRelay of the serving L2 U2N relay terminal, whether to use SL-RSRP or SD-RSRP depends on the implementation of the terminal.

[0422] B. When there is one or more applicable neighboring cells to report (see Table 11):

[0423] - When 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 sl-MeasResultCandRelay to include the best candidate L2 U2N relay terminal up to maxReportCells as follows.

[0424] When reportType is set to eventTriggered: The terminal must include the L2 U2N relay terminals included in relaysTriggeredList as defined within VarMeasReportList for this measId.

[0425] Otherwise, the terminal must include applicable L2 U2N relay terminals for which new measurement results have become available after the last periodic report, or after the measurement has started or been reset.

[0426] - For each L2 U2N relay terminal included in sl-MeasResultsCandRelay, the terminal must include sl-RelayUEIdentity. For each included L2 U2N relay terminal, the terminal must include layer 3 filtered measurement results according to the reportConfig for this measId.

[0427] If the measObject associated with this measId is associated with an L2 U2N relay terminal, the terminal shall set the measResult to include the amount indicated from the reportQuantityRelay within the associated reportConfigRelay in descending order of the sorting quantity, with the best L2 U2N relay terminal included first.

[0428] For a candidate L2 U2N relay terminal, the terminal shall consider yN-Threshold2-Relay as the sorting quantity.

[0429] For a candidate L2 U2N relay terminal, the terminal shall consider reportQuantityRelay as the sorting quantity.

[0430]

Table 11

[0431] In the C.RRCReconfiguration message, the base station shall set the reportConfig associated with the measId that triggered the measurement report to eventTriggered, and as follows, the eventID can be set to one or more events for the event-triggered measurement report.

[0432] > In the case of the serving cell on which the remote terminal camps, the serving cell on which the relay terminal camps, or the cell with the highest suitability for the remote terminal, one or more of the following events can be set for the remote terminal.

[0433] - Event A1 (serving / best cell quality is better than the threshold)

[0434] - Event A2 (serving / best cell quality is worse than the threshold)

[0435] - Event A3 (adjacent cell is offset better than the serving / best cell in terms of cell quality)

[0436] - Event N1 (Adjacent cell quality is better than the threshold value)

[0437] The remote terminal can trigger this event only for the cell indicated by the base station in the RRCReconfiguration message.

[0438] - Event N2 (Adjacent cell quality is worse than the threshold value)

[0439] The remote terminal can trigger this event only for the cell indicated by the base station in the RRCReconfiguration message.

[0440] Whether the cell with the highest suitability for the remote terminal or the serving cell on which the remote terminal camps is the same as or different from the serving cell of the relay terminal.

[0441] The remote terminal can be set in the RRCReconfiguration message to trigger events A3, N1, and / or N2 only for the cell indicated by the base station.

[0442] > For the serving frequency of the serving cell on which the remote terminal camps or the cell with the highest suitability for the remote terminal, the reselection priority of the highest cell, or the reselection priority of the cell with a reselection priority higher than the priority threshold (e.g., a priority higher than the threshold), or the non-serving frequency of the remote terminal, one or more of the following events can be set for the remote terminal.

[0443] - Event S1 (Fitting / best cell quality is better than the threshold value at the frequency)

[0444] - Event S2 (Fitting / best cell quality is worse than the threshold value at the frequency)

[0445] - Event S3 (The qualified neighboring cell is better than the best cell by an offset in terms of cell quality)

[0446] When the above-mentioned event is triggered for the qualified / best cell or the neighboring cell, the remote terminal reports the following information to the base station.

[0447] Measurement results for the qualified / best cell and / or the qualified neighboring cell

[0448] Whether the neighboring cell is suitable as a result of the suitability check based on the SIB1 reading of the neighboring cell

[0449] Global cell ID of the qualified / best cell

[0450] Global cell ID of the neighboring cell

[0451] In the D.RRCReconfiguration message, the base station can set the reportType of the reportConfig related to the measId that triggered the measurement report to periodical, and the remote terminal is configured to perform the following operations.

[0452] > The terminal performs the corresponding measurement related to the best (qualified) cell of the remote terminal for the serving cell of the remote terminal, the serving cell of the relay terminal (when the serving cell is indicated by the relay terminal), and / or the frequency indicated by the base station.

[0453] > If the received measObject contains the cellsToAddModList of the RRCReconfiguration message, the terminal performs the corresponding measurement related to each cell corresponding to the physCellId value included in the cellsToAddModList or each cell detected at the frequency indicated by the base station.

[0454] > After that, the terminal periodically reports the measurement results for each cell (measured by the remote terminal at the above-mentioned stage) to the base station through the relay terminal.

[0455] - In the measurement report transmitted to the base station, the terminal first includes the measurement results for the serving cell of the remote terminal and / or the serving cell of the relay terminal (or the serving cell of the relay terminal and / or the serving cell of the remote terminal) in this order, and then includes the measurement results for each other cell in the cellsToAddModList in descending order of the alignment quantity (for example, in descending order of the measured RSRP or RSRQ results).

[0456] 15. In the DL / UL carrier of the serving cell and the SL carrier where sidelink transmission and / or sidelink reception between the remote terminal and the relay terminal are performed, if the remote terminal and the relay terminal can support the MP operation, or the serving cell supports the sidelink transmission / reception and / or the sidelink resources for the MP operation (for example, based on the resource pool configuration of the system information or the dedicated signal), the remote terminal can start the random access or RRC connection (re)configuration as follows:

[0457] A. In a previous stage, if any one or more entry conditions of the event are satisfied for the cell and any one or more of the events are triggered for the cell, the remote terminal having an indirect path with the base station by the relay terminal can perform any one or more of the following to establish a direct path with the base station:

[0458] > The remote terminal starts a random access procedure for the cell or the serving cell of the relay / remote terminal. In the random access, the remote terminal transmits MSG1 or MSGA.

[0459] - The MSG3 or MSGA PUSCH of the random access procedure includes a C-RNTI MAC CE indicating the C-RNTI (or other terminal ID) of the remote terminal assigned by the base station by the relay terminal.

[0460] - In the case of MSG1 or MSGA, the dedicated RACH preamble can be allocated by the base station for the relay terminal. If the dedicated RACH preamble cannot be allocated, the relay terminal can either transmit SIB1 to the remote terminal to provide the RACH configuration for this random access, or the remote terminal can directly receive SIB1 in the cell.

[0461] > The remote terminal initiates the RRC connection (re) establishment procedure for the relay / remote terminal cell or the serving cell.

[0462] > The remote terminal reports to the base station by transmitting, for example, a SidelinkUEInformationNR message or a measurement report indirectly by the relay terminal or directly after the random access or RRC connection (re) establishment is completed, regarding information about the cell, measurement results for the cell, and / or events triggered for the cell.

[0463] > The remote terminal reports to the relay terminal by transmitting, for example, a PC5 - RRC message regarding information about the cell, measurement results for the cell, and / or events triggered for the cell. When receiving the PC5 - RRC message, the relay terminal reports to the base station regarding information about the cell, measurement results for the cell, and / or events triggered for the cell, including the source or destination ID of the remote terminal.

[0464] Alternatively, as described in the following steps, the base station triggers the random access procedure and / or the RRC connection (re) establishment procedure of the remote terminal having an indirect path with the base station through the relay terminal, so that the remote terminal sets up a direct path with the base station.

[0465] 16. When the remote terminal having an indirect path with the base station through the relay terminal does not have a direct path with the base station, the base station can trigger the random access procedure and / or the RRC connection (re) establishment procedure so that the remote terminal sets up a direct path with the base station as follows.

[0466] A.Alt A: The base station triggers a paging procedure for the remote terminal.

[0467] > The base station configures a paging message and transmits the paging message to the remote terminal indirectly by the relay terminal and / or directly on the serving cell of the relay / remote terminal.

[0468] > The remote terminal monitors the paging opportunity of the remote terminal in the serving cell of the relay / remote terminal and receives the paging message indirectly or directly by the relay terminal.

[0469] - The paging message includes any one or more of the following.

[0470] A terminal ID that can be the s-TMSI, C-RNTI, or source / destination ID of the remote terminal.

[0471] The cell ID of the cell

[0472] The RACH configuration in the cell

[0473] The RACH trigger instruction

[0474] The dedicated RACH preamble

[0475] The multi-path or direct-path instruction

[0476] - When the remote terminal can directly monitor the paging opportunity (PO), the remote terminal can determine the PO of the remote terminal based on the C-RNTI assigned by the base station by the relay terminal.

[0477] - The paging message that triggers the RACH can trigger a random access procedure and / or an RRC connection (re)configuration for the indicated cell based on the RACH configuration provided from the paging message.

[0478] If there is no cell indicated in the paging message, the remote terminal triggers a random access procedure and / or an RRC connection (re)establishment in the serving cell of the relay terminal or the serving cell of the remote terminal or the cell with the highest suitability for the remote terminal as a result of the cell reselection process.

[0479] If there is no RACH configuration in the paging message, the remote terminal triggers a random access procedure and / or an RRC connection (re)establishment based on the RACH configuration in the system information.

[0480] If a dedicated RACH preamble is included in the paging message, the remote terminal triggers a random access procedure and / or an RRC connection (re)establishment with the dedicated RACH preamble. Otherwise, the remote terminal performs a contention-based RACH.

[0481] If multiple paths are indicated, the remote terminal triggers a random access procedure and / or an RRC connection (re)establishment while maintaining an indirect path with the relay terminal.

[0482] If a single path is indicated, the remote terminal triggers a random access procedure and / or an RRC connection (re)establishment after releasing the indirect path with the relay terminal and / or the PC5-RRC connection, or releases the indirect path with the relay terminal and / or the PC5-RRC connection after the random access procedure and / or the RRC connection (re)establishment.

[0483] B.Alt B: The relay terminal triggers the RACH and / or RRC connection (re)establishment of the remote terminal.

[0484] > If any one or more of the following conditions are met, the relay terminal can trigger the RACH and / or RRC connection (re)establishment of the remote terminal.

[0485] - When receiving an RRCReconfiguration message for multi-path operation configuration at the base station,

[0486] The relay terminal can report to the base station that the remote terminal is not in the RRC_CONNECTED state.

[0487] When the remote terminal is not in the RRC_CONNECTED state, the base station can request the relay terminal to initiate, for example, an RRC connection (re)setup by the remote terminal.

[0488] - When receiving system information from the base station for multi-path operation configuration

[0489] - When any one or more of the following conditions for the multi-path operation set by the base station are satisfied

[0490] The DL data transmission rate, UL data transmission rate, or SL data transmission rate of one or more or all of the relayed bearers for the remote terminal exceeds the threshold indicated by the base station or the remote terminal or determined by the relay terminal.

[0491] The amount of DL data, UL data, or SL data in the buffer of one or more or all of the relay bearers of the relay terminal exceeds the threshold indicated by the base station or the remote terminal or determined by the relay terminal.

[0492] One or more or all of the QoS requirements (e.g., delay requirements or error rates) for the relayed bearers for the remote terminal cannot be satisfied during a predetermined period.

[0493] - When the base station sets to allow multi-path operation for the relay terminal or the remote terminal or a pair of the relay terminal and the remote terminal using system information or terminal-specific signals

[0494] > The relay terminal can trigger the RACH and / or RRC connection (re)setup of the remote terminal by any one of the following.

[0495] - The code point of a specific field of the sidelink control information (SCI)

[0496] The SCI is either a one-stage SCI or a two-stage SCI.

[0497] The SCI indicates the destination ID of the remote terminal.

[0498] - Specific field values of the sidelink MAC control element

[0499] - Specific parameter values of the PC5-RRC message

[0500] > When the RRCReconfiguration message of the base station instructs the trigger for the RACH and / or RRC connection (re)configuration of the remote terminal, after the relay terminal instructs the trigger for the RACH and / or RRC connection (re)configuration of the remote terminal, the relay terminal sends an RRCReconfigurationCompletm message to the base station.

[0501] - When the relay terminal cannot instruct the trigger for the RACH and / or RRC connection (re)configuration of the remote terminal due to, for example, a sidelink failure or consecutive NACKs for the said instruction, the relay terminal either sends an RRCReconfigurationComplete message indicating "sidelink error" to the base station or starts an RRC reconfiguration procedure.

[0502] C.Alt C: The remote terminal triggers RACH and / or RRC connection (re)configuration based on whether a predetermined condition is met.

[0503] > When any one or more of the following conditions are met, the remote terminal can trigger RACH and / or RRC connection (re)configuration.

[0504] a. When receiving an RRCReconfiguration message from the base station for the configuration of multi-path operation.

[0505] b. When receiving system information from the base station for the configuration of multi-path operation.

[0506] c. When any one or more of the following conditions for the multi-path operation set by the base station are satisfied.

[0507] - The SL RX or SL TX data rate of one or more or all of the relayed bearers relayed at / by the relay terminal exceeds the threshold indicated by the base station or the relay terminal or determined by the remote terminal.

[0508] - The amount of SL RX or SL TX data in the buffer of one or more or all of the relayed bearers of the remote terminal for the relay terminal exceeds the threshold indicated by the base station or the relay terminal or determined by the remote terminal.

[0509] - The QoS requirements (e.g., delay requirements or error rate) of one or more or all of the relay bearers at / to the relay terminal cannot be satisfied during a predetermined period.

[0510] d. When the base station sets to allow multi-path operation for the relay terminal or the remote terminal or a pair of the relay terminal and the remote terminal by system information or a terminal-specific signal received by the relay terminal.

[0511] According to the aforementioned trigger, the remote terminal starts a random access procedure for the cell indicated by the base station (or the relay terminal) or the serving cell of the relay / remote terminal. Alternatively, the remote terminal performs cell reselection for the cell based on the cell reselection process, and then starts a random access procedure for the cell.

[0512] > In random access, the remote terminal transmits MSG1 or MSGA.

[0513] - The MSG3 or MSGA PUSCH of the random access procedure includes a C-RNTI MAC CE indicating the C-RNTI (or other terminal ID) of the remote terminal assigned by the base station by the relay terminal.

[0514] - For MSG1 or MSGA, a dedicated RACH preamble can be allocated by the base station for the relay terminal. If a dedicated RACH preamble cannot be allocated, the relay terminal can transmit SIB1 to the remote terminal to provide the RACH configuration for this random access, or the remote terminal can directly receive SIB1 in the cell.

[0515] > Through random access, the remote terminal can initiate the RRC connection (re)establishment procedure in the relay / remote terminal cell or the serving cell.

[0516] > If there is no indicated cell, the remote terminal triggers the random access procedure and / or (re)establishes the RRC connection in the cell with the highest suitability for the relay-remote terminal in the serving cell of the terminal or the serving cell of the remote terminal or as a result of the cell reselection process.

[0517] > If the RACH configuration is not provided by the dedicated signal of the base station, the remote terminal triggers the random access procedure and / or (re)establishes the RRC connection according to the RACH configuration of the system information.

[0518] > If the dedicated RACH preamble is provided by the dedicated signal of the base station, the remote terminal triggers the random access procedure and / or (re)establishes the RRC connection with the dedicated RACH preamble. Otherwise, the remote terminal performs RACH on the contention basis.

[0519] > If the base station indicates or allows multiple paths through the system information or the terminal dedicated signal, the remote terminal triggers the random access procedure and / or (re)establishes the RRC connection while maintaining the indirect path with the relay terminal.

[0520] > When the base station indicates a single path or does not allow multiple paths by system information or terminal-specific signals, the remote terminal shall trigger a random access procedure and / or RRC connection (re)configuration after releasing the indirect path and / or PC5-RRC connection with the relay terminal, or the remote terminal shall release the indirect path and / or PC5-RRC connection with the relay terminal after performing the random access procedure and / or RRC connection (re)configuration.

[0521] > The remote terminal shall transmit a SidelinkUEInformationNR message or a measurement report, either indirectly by the relay terminal or directly after completing a random access or RRC connection (re)configuration, and report information regarding the transmitting cell, measurement results for the cell, and / or events triggered for the cell to the base station.

[0522] 17. After RRC connection setup and PC5-RRC connection setup, the relay terminal and / or the remote terminal shall be able to perform SL terminal information for the NR sidelink communication procedure in which the terminal (or the relay terminal) transmits a SidelinkUEInformationNR message to the base station.

[0523] The terminal shall set the content of the SidelinkUEInformationNR message as follows.

[0524] 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 information, or when sl-L2u2n-Relayn is included in a specific SIB (e.g., SIB12) and is set by the upper layer to receive NR SL L2 U2N relay discovery information, 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 information, 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 information:

[0525] - The terminal includes sl-RxInterestedFreqListDisc and sets it as the frequency for receiving NR SL relay discovery information.

[0526] - When the terminal executes an L2 U2N remote terminal or the terminal performs multi-path operation as a remote terminal, the terminal includes sl-SourceIdentity-RemoteUE and sets it as the source ID set by the upper layer for NR SL L2 U2N relay communication transmission.

[0527] 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 the fields thereof as follows:

[0528] - Set sl-DestinationIdentityDisc as the destination ID set by the upper layer for NR SL discovery public knowledge transmission.

[0529] - When the terminal operates as an L2 U2N relay terminal, the terminal sets sl-SourceIdentity-RelayUE as the source ID set by the upper layer for NR SL L2 U2N relay discovery public knowledge transmission.

[0530] - Set sl-CastTypeDisc as the cast type of the related destination ID set by the upper layer for NR SL discovery public knowledge transmission.

[0531] - Set sl-InterestedFreqListDisc to indicate the frequencies of the related destinations for NR SL discovery public knowledge transmission.

[0532] - Set the sl-TypeTxSyncListDisc as the current synchronization reference type used in the sl-InterestedFreqList associated with the NR SL discovery known transmission.

[0533] - Set the sl-DiscoveryType as the current discovery type of the related destination ID set by the upper layer for the NR SL discovery known transmission.

[0534] C. When set by the upper layer to transmit NR SL L2 U2N relay communication and the terminal operates as an L2 U2N relay terminal for multi-path, the relay terminal shall perform the following.

[0535] - 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.

[0536] - Set the sl-DestinationIdentityL2U2N as the destination ID set by the upper layer for the NR SL L2 U2N relay communication transmission.

[0537] - Set the sl-TxInterestedFreqListL2U2N to indicate the frequencies of the related destinations for the NR SL L2 U2N relay communication transmission.

[0538] - Set the sl-TypeTxSyncListL2U2N as the current synchronization reference type used in the sl-InterestedFreqListL2U2N associated with the NR SL L2 U2N relay communication transmission.

[0539] - Set the sl-LocalID-Request to request the local ID for the L2 U2N remote terminal.

[0540] - Set the sl-PagingIdentity-RemoteUE as the paging terminal ID received by the peer L2 U2N remote terminal.

[0541] - Set to include the UECapabilityInformationSidelink message (if present) received by the peer terminal in the sl-CapabilityInformationSidelink.

[0542] - Include the ue-Type and set this as a relayUE.

[0543] - Include the multi-path support / request indication.

[0544] - Include an indication of the RRC state of the remote terminal or whether the remote terminal is in RRC_CONNECTED.

[0545] - Include the cell ID of the PCell for the remote terminal.

[0546] - Include the PLMN ID of the PLMN registered for the remote terminal.

[0547] - Include the tracking area code of the tracking area where the remote terminal is registered with the PCell.

[0548] D. If it is set by the upper layer to transmit NR sidelink L2 U2N relay communication and there is an L2 U2N relay terminal selected by the terminal for multi-path, the remote terminal shall do the following.

[0549] - Include the sl-TxResourceReqL2U2N-Relay in the sl-TxResourceReqListCommRelay and (if necessary) set this field as follows to request the network to allocate NR SL L2 U2N relay communication resources.

[0550] - Set sl-TxInterestedFreqListL2U2N to indicate the frequencies of the destinations relevant for NR SL L2 U2N relay communication transmission.

[0551] - Set sl-TypeTxSyncListL2U2N as the current synchronization reference type used in the related sl-InterestedFreqListL2U2N for NR SL L2 U2N relay communication transmission.

[0552] - If there is a UECapabilityInformationSidelink message received at the peer terminal, set Sl-CapabilityInformationSidelink to include this.

[0553] - Include ue-Type and set as remoteUE.

[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 the PCell cell ID of the relay terminal.

[0557] - Include the PLMN ID of the registered PLMN of the relay terminal.

[0558] - Include the tracking area code of the tracking area in which the relay terminal is registered with the PCell.

[0559] 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.

[0560] - Include sl-TxResourceReqL3u2n-Relay in sl-TxResourceReqListCommRelay and configure this field as follows (if necessary) for each destination for which the network requests the allocation of NR SL L3 U2N relay communication resources:

[0561] - Set sl-DestinationIdentity as the destination ID configured by the upper layer for NR SL L3 U2N relay communication transmission.

[0562] - Set sl-CastType as the cast type of the related destination ID configured by the upper layer for NR SL L3 U2N relay communication transmission.

[0563] - If the related two-way SL DRB is configured by the setting in RRCReconfigurationSidelink, set sl-RLC-ModeIndication to include the RLC mode of the related RLC mode of the SL QoS flow and optionally the QoS profile.

[0564] - Set sl-QoS-InfoList to include the QoS profile of the SL QoS flow of the related destination configured by the upper layer for NR SL L3 U2N relay communication transmission.

[0565] - Set sl-TxInterestedFreqList to indicate the frequencies of the related destination for NR SL L3 U2N relay communication transmission.

[0566] - Set sl-TypeTxSyncList as the current synchronization reference type used in the related sl-InterestedFreqList for NR SL L3 U2N relay communication transmission.

[0567] - When a UECapabilityInformationSidelink message is received from a peer terminal, set sl-CapabilityInformationSidelink to include this message.

[0568] - Include ue-Type, and if the terminal operates as an NR SL L3 U2N relay terminal, set it to relayUE; otherwise, set it to remoteUE.

[0569] - Include multi-path support / request indication.

[0570] - Include an indication of the RRC state of the relay terminal or whether the relay terminal is in RRC_CONNECTED.

[0571] - Include an indication of the RRC state of the remote terminal or whether the remote terminal is in RRC_CONNECTED.

[0572] - When the terminal operates as an NR SL U2N remote terminal:

[0573] Include the cell ID of the PCell for the relay terminal.

[0574] Include the PLMN ID of the registered PLMN for the relay terminal.

[0575] Include the tracking area code of the tracking area registered by the relay terminal for the PCell.

[0576] - When the terminal operates as an NR SL U2N relay terminal:

[0577] Include the cell ID of the PCell for the remote terminal.

[0578] Include the PLMN ID of the PLMN registered for the remote terminal.

[0579] Include the tracking area code of the tracking area registered by the remote terminal for the PCell.

[0580] 18. When receiving a report from a remote terminal and / or a relay terminal (e.g., a MeasurementReport message and / or a SidelinkUEInformationNR message from a remote terminal and / or a SidelinkUEInformationNR message from a relay terminal and / or a multi-path configuration described in the following stage), the base station determines whether to add a direct path to the remote terminal with respect to the base station.

[0581] 19. 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 performs a handover for the relay terminal and / or the remote terminal, and can move the relay terminal and / or the remote terminal to the same cell, the same tracking area and / or the same PLMN.

[0582] 20. If both the relay terminal and the remote terminal are in RRC_CONNECTED and the base station has determined whether to add a direct path to the remote terminal in the previous stage, for example, the base station sends an RRCReconfiguration message to each of the relay terminal and the remote terminal, and the base station sets a direct path to the remote terminal (S168). After random access and / or RRC connection (re)configuration, the base station can send the RRCReconfiguration message directly to the remote terminal or indirectly through the relay terminal.

[0583] - When the sl-L2RelayUEConfig is included in the RRCReconfiguration message, the relay terminal performs the L2 U2N relay terminal configuration procedure, (re)configures or releases zero, one or more indirect bearers, and releases zero, one or more split bearers.

[0584] - When the sl-L2RemoteUEConfig is included in the RRCReconfiguration message, the remote terminal performs the L2 U2N remote terminal configuration procedure, and (re)configures zero, one or more direct bearers and zero, one or more split bearers.

[0585] - If the configuration of the direct path of the bearer and / or the split bearer is directly included in the RRCReconfiguration message, the remote terminal (re)sets zero, one or more direct bearers and the direct paths of zero, one or more split bearers.

[0586] - The indirect bearer or the split bearer includes the setting of the Uu relay RLC channel.

[0587] - The indirect bearer is composed of an indirect link consisting of a Uu link and a sidelink.

[0588] - The direct bearer is composed of only a direct link via Uu.

[0589] - The split bearer is set with the indirect path and the direct path of the split bearer. The base station can select all or one of the indirect path and the direct path for downlink data transmission to the remote terminal, and the remote terminal can select all or one of the indirect path and the direct path for uplink data transmission to the base station.

[0590] A. Option 1: Joint RRC reconfiguration

[0591] a. 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 modification or release of the indirect / split bearer applied to the relay terminal, and the second part includes the modification or release of the indirect / split bearer applied to the remote terminal and the addition of the direct bearer or the configuration for the direct path of the split bearer.

[0592] > Option 1A: The relay terminal sends a Uu RRC message (e.g., RRCReconfiguration message) to the remote terminal and transmits the second part to the remote terminal.

[0593] - 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 configured between the base station and the relay terminal, and at the same time encrypts the second part with the second security key configured between the base station and the remote terminal. When the relay terminal receives the RRCReconfiguration message and can successfully apply the configuration of the first part, the layer of the relay terminal removes the first part from the RRCReconfiguration message, and sends the RRCReconfiguration message with the first part removed to the remote terminal to transmit 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, when the relay terminal cannot successfully apply the configuration of the first part, the relay terminal may not be able to transmit the second part of the RRC container to the remote terminal.

[0594] - When receiving the second part, the remote terminal decrypts the second part using the second security key. When 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 sends it directly to the base station or indirectly to the base station through the relay terminal. When the remote terminal cannot successfully 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 sends it directly to the base station or indirectly to the base station through the relay terminal. Alternatively, when the remote terminal cannot successfully apply the configuration of the second part, the remote terminal directly suspends the bearer and starts the RRC reconfiguration procedure to suspend or release the indirect / split bearer. The remote terminal can also release the PC5-RRC connection with the relay terminal.

[0595] 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 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.

[0596] 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 RRCReestablishmentComplet 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.

[0597] - If the remote terminal fails to apply the configuration of the second part, the remote terminal can release the PC5-RRC connection with the relay terminal or report a sidelink relay reconfiguration failure or a multi-path configuration failure to the relay terminal.

[0598] - 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 indicating a U2N configuration or multi-path configuration failure to the base station. The RRC container of the RRCReconfigurationComplete message sent from the relay terminal to the base station can include the RCReconfigurationComplete message received at the remote terminal. Alternatively, when the PC5-RRC connection is released, or a sidelink relay reconfiguration failure or a multi-path configuration failure is received or detected, or the relay terminal cannot successfully apply the configuration of the first part, the relay terminal starts the RRC reconfiguration procedure to directly abort the bearer and abort or release the indirect / split bearer. The relay terminal can also release the PC5-RRC connection with the remote terminal or report a sidelink relay reconfiguration failure or a multi-path configuration failure to the remote terminal. In the RRC reconfiguration procedure, the relay 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 a U2N configuration or multi-path configuration failure and the source or destination ID of the relay terminal and / or the remote terminal.

[0599] > Option 1B: The relay terminal sends a PC5 RRC message (e.g., RRCReconfigurationSidelink message or UuMessageTransferSidelink message) to the remote terminal to transmit the second part to the remote terminal.

[0600] - 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 configured 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). After that, the relay terminal encrypts the second part using the third security key configured on the PC5 interface between the relay terminal and the remote terminal. The relay terminal includes the second part in the RRCReconfigurationSidelink message sent 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 is reconfigured to be included in the RRCReconfigurationSidelink message.

[0601] - 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 RRCReconfigurationFailureSidelink 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 directly suspends the bearer and starts the RRC reconfiguration procedure to suspend or release the indirect / split bearer. The remote terminal can also release the PC5-RRC connection with the relay terminal.

[0602] In the case of an RRC reconfiguration procedure via the Uu interface, the remote terminal performs random access to the base station and, as a result of the procedure, directly configures only the 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.

[0603] In the case of an RRC reconfiguration procedure by the relay terminal, after the remote terminal transmits the 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.

[0604] - If the relay terminal receives an RRCReconfigurationFailureSidelink message, or receives a sidelink relay reconfiguration failure or a multi-path configuration failure, or detects a sidelink failure (e.g., due to the expiration of timer T400), or if the relay terminal fails to successfully apply the configuration of the first part, the relay terminal shall send an RRCReconfigurationFailure or RRCReconfigurationComplete message indicating a U2N configuration or multi-path configuration failure to the base station. Alternatively, if the relay terminal receives an RRCReconfigurationFailureSidelink message, or receives a sidelink relay reconfiguration failure or a multi-path configuration failure, or detects a sidelink failure (e.g., due to the expiration of timer T400), or if the relay terminal fails to successfully apply the configuration of the first part, the relay terminal shall initiate an RRC reconfiguration procedure to suspend or release its direct bearer and to suspend or release its indirect / split bearer. The relay terminal may also release the PC5-RRC connection with the remote terminal or report the sidelink relay reconfiguration failure or multi-path configuration failure to the remote terminal. 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 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.

[0605] > In Option 1, when the remote terminal or the relay terminal performs an RRC reconfiguration procedure, it can also inform the base station which terminal has failed to apply the U2N configuration or multi-path configuration, i.e., whether it is the remote terminal or the relay terminal.

[0606] B. Option 2: Separate transmission of RRC reconfiguration

[0607] a. The base station transmits a first RRCReconfiguration message to the relay terminal. The first RRCReconfiguration message at least includes configurations regarding modification or release of the indirect / split bearers applied to the relay terminal.

[0608] > If the relay terminal receives the first RRCReconfiguration message and can successfully apply the configuration of the first message, the relay terminal transmits an RRCReconfigurationComplete message to the base station. However, if after receiving the first message, the relay terminal cannot successfully apply the configuration of the first message, or if the PC5-RRC connection is released, or if a sidelink relay reconfiguration failure or a multi-path configuration failure is received or detected, the relay terminal suspends its direct bearer and initiates an RRC reconfiguration procedure to suspend or release the indirect / split bearers. 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 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.

[0609] b. The base station transmits a second RRCReconfiguration message to the remote terminal. The second RRCReconfiguration message includes configurations regarding modification or release of the indirect / split bearers and addition of the direct path of the direct bearers and split bearers applied to the remote terminal.

[0610] > The base station can directly transmit the second RRCReconfiguration message to the remote terminal from the Uu interface using, for example, SRB1.

[0611] - If the remote terminal receives the second message and can successfully apply the configuration of the second message, the remote terminal sends an RRCReconfigurationComplete message to the base station. If the remote terminal cannot successfully apply the configuration of the second message, the remote terminal directly or indirectly sends an RRCReconfigurationFailure or RRCReconfigurationComplete message to the base station to indicate a failure in the U2N configuration or multi-path configuration.

[0612] 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.

[0613] 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 report a sidelink relay reconfiguration failure or multi-path configuration failure to the relay terminal.

[0614] - Alternatively, if the remote terminal fails to apply the configuration of the second message, the remote terminal starts an RRC reconfiguration procedure to temporarily suspend its own direct bearers and temporarily suspend or release its indirect / split bearers. The remote terminal can also release the PC5-RRC connection with the relay terminal or report a sidelink relay reconfiguration failure or multi-path configuration failure to the relay terminal.

[0615] In the case of the RRC reconfiguration procedure via the Uu interface, the remote terminal performs a random access to the base station and configures only the direct bearers as a result of the procedure. In the RRC reconfiguration procedure, the relay terminal sends an RRCReestablishmentComplete message indicating a failure in the U2N configuration or multi-path configuration and the source or destination ID of the relay terminal and / or the remote terminal.

[0616] In the case of the RRC reconfiguration procedure by the relay terminal, after the remote terminal transmits the 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 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.

[0617] - When the PC5-RRC connection is released, or a side-link relay reconfiguration failure or a multi-path configuration failure is received, the relay terminal transmits an RCReconfigurationFailure or RRCReconfigurationComplete message indicating a failure of the U2N configuration or the multi-path configuration to the base station. When receiving an RCReestablishmentRequest message from 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 from the remote terminal.

[0618] - Alternatively, if the PC5-RRC connection is released, or a side-link relay reconfiguration failure or a multi-path configuration failure is received or detected, or the relay terminal fails to successfully apply the configuration of the first message, the relay terminal starts an RRC reconfiguration procedure to directly suspend the bearer and either 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 side-link 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 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 contains the RRCReestablishmentRequest message received at the remote terminal.

[0619] > 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.

[0620] - When the relay terminal receives the first RRCReconfiguration message and 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 sends 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 if the PC5-RRC connection is released, or if it receives or detects a side-link 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, directly suspends its own bearers, and initiates an RRC reconfiguration procedure to suspend or release the indirect / split bearers. The relay terminal can also release the PC5-RRC connection with the remote terminal or notify the remote terminal of a side-link 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 bearers. In the RRC reconfiguration procedure, the relay terminal transmits 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.

[0621] - When the relay terminal notifies the remote terminal of a side-link relay reconfiguration failure or a multi-path configuration failure, the remote terminal initiates an RRC reconfiguration procedure to directly suspend its own bearers and suspend or release the indirect / split bearers. The remote terminal can also release the PC5-RRC connection with the relay terminal.

[0622] In the case of an 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, configures only the direct bearers. In the RRC reconfiguration procedure, the relay terminal transmits 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.

[0623] In the case of the RRC reconfiguration procedure by the relay terminal, after the remote terminal uses SL-RLC1 for SRB1 to send the RRCReestablishmentComplete message to the relay terminal, 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.

[0624] In the above-described stage, the core network (CN) node (e.g., AMF or SMF) can provide the multi-path configuration to the base station and the terminal as follows.

[0625] > Alternative 1: When the remote terminal sets up an RRC connection with the base station (e.g., by the relay terminal), the remote terminal sends 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.

[0626] - 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 preference of the relay terminal for multi-path operation. Upon receiving the initial NAS message from the relay terminal and 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.

[0627] > Alternative 2: After the remote terminal sets up an RRC connection with the base station (e.g., via a relay terminal), 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 to perform multi-path operation.

[0628] - Upon receiving the instruction from the base station, the CN node provides the base station with terminal capabilities related to multi-path operation and NAS configurations related to multi-path. Upon receiving the terminal capabilities and / or NAS configurations, the base station configures multi-path operation as described above based on the received terminal capabilities and / or NAS configurations.

[0629] - Upon receiving the instruction from the base station, the CN node provides the remote terminal and / or relay terminal with NAS configurations related to multi-path. The remote terminal and / or relay terminal configures multi-path operation based on the NAS configurations related to multi-path on the RRC configuration provided by the base station as described above.

[0630] > Alternative 3: 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. Upon receiving the initial NAS message from the relay terminal, the CN node provides the base station with terminal capabilities related to multi-path operation and NAS configurations related to multi-path. Upon receiving the terminal capabilities and / or NAS configurations, the base station determines whether to configure multi-path operation as described above.

[0631] - Also, when the relay terminal sets up an RRC connection with the base station (e.g., by the relay terminal), the remote terminal can also send an initial NAS message to the CN node. The initial NAS message can indicate the preference of the remote terminal 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. When the terminal capabilities and / or the NAS configuration are received, the base station determines whether to configure multi-path operation as described above.

[0632] The CN node (e.g., AMF or SMF) can inform the base station about the multi-path configuration or the addition of a multi-path configuration, for example, by means of a QoS profile for the remote terminal and / or the relay terminal. The QoS profile is sent from the CN node to the base station.

[0633] - The information related to multi-path in the QoS profile can indicate whether multi-path can be configured for any one of the following.

[0634] Each PDU session

[0635] Each QoS flow

[0636] Each remote terminal

[0637] Each relay terminal

[0638] Each frequency

[0639] Each cell

[0640] Each RAT

[0641] Each PLMN

[0642] Each tracking area

[0643] Each base station

[0644] 21. At the above-described stage, the relay terminal and the remote terminal can release one or more or all of the indirect bearers and / or split bearers that are reconfigured with a direct bearer according to the base station's RRCReconfiguration message. By the base station's RRCReconfiguration message, the remote terminal still maintains both the direct link and the indirect link by the relay terminal.

[0645] By the base station's RRCReconfiguration message, to release the indirect path of the indirect bearer for reconfiguration with a direct bearer or the split bearer for the indirect path of the multi-path indirect path, the remote terminal or the relay terminal performs any one or more of the following.

[0646] A. The bearer receiving PDCP entity of the remote terminal can trigger a PDCP status report to be sent to the base station as follows.

[0647] > The PDCP status report is sent directly from the remote terminal to the base station or indirectly to the base station by the relay terminal.

[0648] > Upon receiving the PDCP status report, the bearer transmitting PDCP entity of the base station triggers "multi-path data switching" to retransmit or transmit PDCP SDUs on the direct path towards the remote terminal as follows.

[0649] > When receiving or before receiving the RRCReconfiguration message for bearer release, the SL RLC entity of the remote terminal or the relay terminal performs any one or more of the following.

[0650] - Opt 1 (or, Opt 21-1a): The remote terminal releases the Uu RLC entity and / or the PC5 RLC entity for the downstream indirect path of the bearer. As a result, the SL data buffered in the TX RLC entity is deleted / removed, or the DL data buffered in the RX RLC entity is deleted.

[0651] - Opt 2 (or, Opt 21-2a): For the SL RLC entity of the PC5 RLC channel for the downstream indirect path of the bearer, the AM RLC entity of the relay terminal polls the peer AM RLC entity to trigger the RLC status report of the peer AM RLC entity of the remote terminal. Based on the polling, the AM RLC entity of the remote terminal triggers the RLC status report to be sent to the peer AM RLC entity of the relay terminal.

[0652] - Opt 3 (or, Opt 21-3a): For the SL RLC entity of the PC5 RLC channel for the downstream indirect path of the bearer, the AM RLC entity of the remote terminal triggers the RLC status report to be sent to the peer AM RLC entity of the relay terminal.

[0653] > When receiving the RLC status report from the receiving RLC entity, the SL transmitting RLC entity of the relay terminal retransmits the RLC SDU or RLC SDU segment for which a negative acknowledgment has been received by the RLC status report as follows.

[0654] B. The receiving PDCP entity of the bearer of the base station can trigger the PDCP status report to be sent to the remote terminal as follows.

[0655] > The PDCP status report is sent directly from the base station to the remote terminal or indirectly to the remote terminal by the relay terminal.

[0656] > When receiving the PDCP status report, the transmitting PDCP entity of the bearer of the remote terminal triggers "multi-path data switching" to retransmit or transmit the PDCP SDU on the direct path towards the base station as follows.

[0657] > Before / after receiving the RRCReconfiguration message for bearer release, the SL RLC entity of the relay terminal or the remote terminal performs one or more of the following.

[0658] - Opt 1 (or, Opt 21-1b): The relay terminal releases the Uu RLC entity and / or the PC5 RLC entity for the bearer's upstream indirect path. As a result, the SL data buffered in the RX RLC entity is deleted / is deleted, or the UL data buffered in the TX RLC entity is deleted.

[0659] - Opt 2 (or, Opt 21-2b): In the case of the SL RLC entity of the PC5 RLC channel for the bearer's upstream indirect path, the AM RLC entity of the remote terminal polls the peer AM RLC entity and triggers the RLC status report of the peer AM RLC entity of the relay terminal. Based on the polling, the AM RLC entity of the relay terminal triggers the RLC status report to be sent to the peer AM RLC entity of the remote terminal.

[0660] - Option 3 (or, Option 21-3b): In the case of the SL RLC entity of the PC5 RLC channel for the bearer's upstream indirect path, the AM RLC entity of the relay terminal triggers the RLC status report to be sent to the peer AM RLC entity of the remote terminal.

[0661] > When receiving the RLC status report from the receiving RLC entity, the SL transmitting RLC entity of the remote terminal retransmits the SL RLC SDU or SL RLC SDU segment for which a negative acknowledgment has been received by the RLC status report over Uu / PC5 until the bearer is released.

[0662] - When receiving an SL RLC SDU and / or an SL RLC SDU segment from a remote terminal, the relay terminal retransmits the uplink of the UL RLC SDU or UL RLC SDU segment corresponding to the SL RLC SDU and / or SL RLC SDU segment until the bearer is released.

[0663] > After that, the relay terminal and / or the remote terminal notifies the base station of the bearer release, for example, by transmitting a terminal information message to the base station.

[0664] - Before / after receiving the terminal information message, the base station releases the PDCP / RLC entity (or entities) corresponding to the bearer and / or the PC5-RRC connection.

[0665] - Before / after transmitting the terminal information message or when transmitting the RRCReconfiguration message that releases the bearer to the remote terminal and / or the relay terminal, the relay terminal and / or the remote terminal releases the Uu / PC5 PDCP / RLC entity (or entities) corresponding to the bearer and / or the PC5-RRC connection.

[0666] C. When receiving / before receiving the RRCReconfiguration message that releases the bearer, for the downstream indirect path of the bearer, the relay terminal aborts all RLC status reporting procedures in the DL receiving RLC entity and / or the SL transmitting RLC entity, and releases the DL receiving RLC entity and / or the SL transmitting RLC entity. The relay terminal can also transmit an RRCReconfigurationSidelink message to the remote terminal to release the peer SL receiving RLC entity at the remote terminal.

[0667] When PDCP status reporting is triggered, the receiving PDCP entity performs the following.

[0668] > Compile the PDCP status report as instructed as follows.

[0669] - Set the FMC field to RX_DELIV.

[0670] - If RX_DELIV < RX_NEXT:

[0671] Start with the first missed PDCP SDU, not including this one, and including the last out-of-sequence PDCP SDU, assign a bitmap field with a value rounded up to the next multiple of 8 as the COUNT value up to this last PDCP SDU, or including up to the PDCP SDU where the resulting PDCP control PDU size becomes 9000 bytes, with the same bit length as the COUNT value up to this PDCP SDU.

[0672] For all PDCP SDUs not received and, optionally, for PDCP SDUs that failed decompression, set to "0" in the bitmap field.

[0673] For all received PDCP SDUs, set to "1" in the bitmap field.

[0674] - Submit a PDCP status report to the lower layer as the first PDCP PDU to be transmitted by the transmitting PDCP entity, as specified in 5.2.1 of 3GPP TS 38.323 for the Uu interface and as specified in 5.2.3 of 3GPP TS 38.323 for the PC5 interface.

[0675] For an AM DRB, when a PDCP status report is received on the downlink or sidelink, the transmitting PDCP entity shall do the following.

[0676] - Consider each PDCP SDU for which the bit in the bitmap is set to "1" or the associated COUNT value is less than the FMC field value as having been successfully transmitted and delete this PDCP SDU (as specified in 5.3 of 3GPP TS 38.323).

[0677] When multi-path data switching (e.g., from an indirect bearer to a direct bearer) is triggered for a bearer, the DL, UL, or SL transmitting PDCP entity shall perform the following for the bearer.

[0678] > For an AM DRB, from the first PDCP SDU for which successful delivery of the PDCP data PDU cannot be confirmed by the RLC entity associated with the indirect path, re-transmit or transmit all PDCP SDUs already associated with the PDCP SN in ascending order of the COUNT value associated with the PDCP SDU prior to multi-path data switching to the RLC entity associated with the direct path in DL, UL, or SL as follows.

[0679] - Perform header compression of the PDCP SDU using ROHC.

[0680] - Perform integrity protection and encryption of the PDCP SDU using the COUNT value associated with this PDCP SDU.

[0681] - Submit the resulting PDCP data PDU to the RLC entity of the direct path.

[0682] > For a UM DRB, for all PDCP SDUs that have been processed by PDCP but have not yet been submitted to the lower layer, transmit the PDCP SDUs to the RLC entity associated with the direct path in ascending order of the COUNT value in DL, UL, or SL as specified below.

[0683] - Perform header compression of the PDCP SDU using ROHC.

[0684] - Perform integrity protection and encryption of the PDCP SDU using the COUNT value associated with this PDCP SDU.

[0685] - Submit the resulting PDCP data PDU to the RLC entity of the direct path in DL, UL, or SL.

[0686] The AM RLC entity transmits a STATUS PDU to the peer AM RLC entity to provide positive and / or negative acknowledgments for RLC SDUs (or parts thereof).

[0687] The triggers for starting an A.STATUS report are as follows.

[0688] > Polling at the peer AM RLC entity:

[0689] - When an AMD PDU with SN = x and the P field set to '1' is received at the lower layer by the receiving side of the AM RLC entity, the following actions are taken.

[0690] If it is necessary to discard the AMD PDU as in 5.2.3.2.2, or

[0691] if x < RX_Highest_Status or x >= RX_Next + AM_Window_Size:

[0692] Trigger a STATUS report.

[0693] - Otherwise, delay the STATUS report trigger until x < RX_Highest_Status or x >= RX_Next + AM_Window_Size.

[0694] Reference 1: In this way, the RLC status report is sent after HARQ reordering.

[0695] > Detection of AMD PDU reception failure

[0696] - The receiving side of the AM RLC entity triggers a STATUS report when t-Reassembly expires.

[0697] > When receiving indirect path release for multi-path configuration

[0698] - The receiving side of the AM RLC entity for DL, UL or SL for the indirect path triggers a STATUS report.

[0699] Reference 2: When t-Reassembly expires, RX_Highest_Status update and STATUS report are triggered, but the STATUS report is triggered after RX_Highest_Status is updated.

[0700] When a STATUS report is triggered, the receiving side of the AM RLC entity performs the following.

[0701] > If t-StatusProhibit is not in execution: Configure a STATUS PDU at the first transmission opportunity indicated by the lower layer and submit it to the lower layer.

[0702] > Otherwise: After t-StatusProhibit is executed, at the first transmission opportunity indicated by the lower layer, even if the status report is triggered several times during the execution of t-StatusProhibit, configure a single STATUS PDU and submit it to the lower layer.

[0703] When the STATUS PDU is submitted to the lower layer, the receiving side of the AM RLC entity starts t-StatusProhibit.

[0704] When configuring the STATUS PDU, the AM RLC entity performs the following.

[0705] > For RLC SDUs where SN = RX_Next up to the point where the resulting STATUS PDU matches the full size of the RLC PDU indicated by the lower layer in ascending order of the SN of the RLC SDU and in ascending order of the byte segments within the RLC SDU, and where the SNs that have not been fully received are RX_Next <= SN < RX_Highest_Status

[0706] - For RLC SDUs for which byte segments have not yet been received:

[0707] Include the NACK_SN set in the SN of the RLC SDU in the STATUS PDU.

[0708] - For a continuous sequence of unreceived byte segments of a partially received RLC SDU:

[0709] Include the NACK_SN, SOstart, and SOend sets in the STATUS PDU.

[0710] - For a continuous sequence of RLC SDUs that have not yet been received:

[0711] Include the NACK_SN and NACK range set in the STATUS PDU.

[0712] Optionally, include the pair of SOstart and SOend in the STATUS PDU.

[0713] - Set the ACK_SN to the SN of the next unreceived RLC SDU that is not indicated as missing from the resulting STATUS PDU.

[0714] When receiving a STATUS report from the receiving RLC AM entity, the transmitting side of the AM RLC entity performs the following.

[0715] > If the STATUS report contains a positive or negative acknowledgment for an RLC SDU having the same sequence number as POLL_SN:

[0716] - If t-PollRetransmit is running, stop and reset the timer t-PollRetransmit used to retransmit the poll on the transmitting side of the AM RLC entity.

[0717] - Consider the RLC SDU or RLC SDU segment for which a negative acknowledgment has been received for retransmission.

[0718] On the other hand, when receiving an RRCReconfiguration message from the base station, for the bearer (e.g., split bearer), the remote terminal can reconfigure the direct path of the split bearer as the basic path as follows.

[0719] > If the RRCReconfiguration message does not set the basic path of the bearer, the remote terminal reconfigures the direct path of the split bearer as the basic path.

[0720] - Alternatively, if the RRCReconfiguration message does not set the basic path of the bearer, the remote terminal maintains (or configures) the indirect path of the split bearer as the basic path.

[0721] - Alternatively, if the RRCReconfiguration message does not set the basic path of the bearer, the remote terminal configures the direct path or indirect path of the split bearer as the basic path according to the specified configuration or basic configuration.

[0722] > If the RRCReconfiguration message sets the basic path of the bearer, the remote terminal configures the direct path or indirect path of the split bearer as the basic path according to the setting of the RRCReconfiguration message.

[0723] > A specific type of Signalling RB can always configure the direct path of the split bearer as the basic path (e.g., according to the specified configuration or basic configuration). For example, a specific type of Signalling RB is SRB1 and / or SRB2.

[0724] 22. If any one or more of the following conditions are satisfied, the relay terminal can request the base station to modify or release the indirect bearer and / or the indirect path of the split bearer, or report to the base station the conditions for triggering the modification or release using the first terminal information message (i.e., any one or more of the following conditions).

[0725] - When the relay terminal detects a buffer overflow for the relayed bearer / channel (e.g., TX or RX buffer overflow for SL transmission / reception between the relay terminal and the remote terminal or buffer overflow for UL transmission or DL reception for U2N relay).

[0726] - When the relay terminal cannot meet the QoS requirements of the relayed bearer / channel, for example, when it cannot meet the delay requirements or data rate requirements of the relayed bearer / channel.

[0727] - When the relay terminal sets up a PC5 unicast link with one or more remote terminals.

[0728] - When the relay terminal releases the PC5 unicast link with the remote terminal.

[0729] - When the relay terminal detects a side link error (e.g., side link radio link error or side link reconfiguration error or side link integrity protection error) for the PC5 unicast link with the remote terminal.

[0730] - When the remote terminal and / or the relay terminal cannot map to the previously configured Uu / PC5 RLC channel for relaying the newly configurable SL bearer.

[0731] - When the SL bearer mapped to the configured Uu / PC5 RLC channel is released by the remote terminal and / or the relay terminal.

[0732] - When the NAS layer of the relay terminal requests the addition, modification, or removal of an indirect path of a multi-path operation - capable indirect bearer and / or split bearer

[0733] The first terminal information message includes any one or more of the following.

[0734] - Identifiers of the relayed bearer / channel that comply with the above - described modification or modification conditions (e.g., bearer ID of the relayed bearer / channel, logical channel ID, source ID, or destination ID)

[0735] - Identifiers of the relayed bearer / channel that comply with the above - described removal or removal conditions (e.g., bearer ID of the relayed bearer / channel, logical channel ID, source ID, or destination ID)

[0736] - Reasons related to the above - described modification conditions

[0737] 23. The remote terminal requests the base station to modify or remove the indirect path of the indirect bearer and / or split bearer, or when any one or more of the following conditions are met, it can notify the base station of the conditions (i.e., any one or more of the following conditions) for triggering the modification or removal using the second terminal information message.

[0738] - When the remote terminal detects a buffer overflow for the relayed bearer / channel (e.g., TX or RX buffer overflow for SL transmission / reception between the relay terminal and the remote terminal)

[0739] - When the remote terminal cannot meet the QoS requirements of the relayed bearer / channel, for example, when it cannot meet the delay requirements of the relayed bearer / channel or the requirements of the relay bearer / channel

[0740] - When the remote terminal configures a PC5 unicast link with one or more relay terminals

[0741] - When the remote terminal releases the unicast link with the relay terminal and the PC5

[0742] - When the remote terminal detects a side link error (e.g., side link radio link error, side link reconfiguration error, or side link integrity protection error) in the unicast link with the relay terminal and the PC5

[0743] - When the remote terminal and / or the relay terminal cannot map the newly configurable SL bearer to the conventionally configured Uu / PC5 RLC channel for relaying

[0744] - When the SL bearer mapped to the configured Uu / PC5 RLC channel is released by the remote terminal and / or the relay terminal

[0745] - When the NAS layer of the remote terminal requests the addition, modification, or release of the indirect path of the configurable indirect bearer and / or split bearer for multi-path operation

[0746] The second terminal information message includes one or more of the following.

[0747] - Identifiers of the relayed bearer / channel that comply with the above-mentioned modification or modification conditions (e.g., bearer ID, logical channel ID, source ID, or destination ID of the relayed bearer / channel)

[0748] - Identifiers of the relayed bearer / channel that comply with the above-mentioned release or release conditions (e.g., bearer ID, logical channel ID, source ID, or destination ID of the relayed bearer / channel)

[0749] - The cause related to the above-mentioned release condition

[0750] 24. When the remote terminal deems that the entry condition for one of the following events is satisfied based on the above-mentioned measurement configuration, the remote terminal starts the first measurement reporting procedure (see Tables 6 to 10).

[0751] - Event X1 (The serving L2 U2N relay terminal deteriorates beyond threshold 1 and the NR cell improves beyond threshold 2)

[0752] - Event X3 (The serving L2 U2N relay terminal deteriorates beyond threshold 1 and the PCell (or PSCell or SCell) improves beyond threshold 2)

[0753] - Event X2 (The serving L2 U2N relay terminal deteriorates beyond the threshold)

[0754] - Event Y2 (The candidate L2 U2N relay terminal improves beyond the threshold)

[0755] - Event C1 (The NR sidelink channel utilization rate exceeds the threshold)

[0756] If the remote terminal deems that the detachment condition for one of the following events is satisfied based on the aforementioned measurement configuration, the remote terminal starts the first measurement reporting procedure.

[0757] - Event C2 (The NR sidelink channel utilization rate is less than the threshold)

[0758] - Event Y1 (The PCell is worse than threshold 1 and the candidate L2 U2N relay terminal is better than threshold 2)

[0759] If the relay terminal deems that the entry condition for one of the following events is satisfied according to the aforementioned measurement configuration, the relay terminal starts the second measurement reporting procedure.

[0760] - Event A2 (The serving deteriorates beyond the threshold)

[0761] - Event A3 (The adjacent cell is offset better than the SpCell)

[0762] - Event B1 (The adjacent cell between RATs is better than the threshold)

[0763] - Event B2 (The PCell is worse than threshold 1 and the adjacent cell between RATs is better than threshold 2)

[0764] - Event C1 (The NR sidelink channel utilization rate exceeds the threshold)

[0765] If the relay terminal is considered to meet the detachment condition for one of the following events according to the above-described measurement configuration, the relay terminal starts a second measurement reporting procedure.

[0766] - Event C2 (The NR sidelink channel utilization rate is less than the threshold)

[0767] - Event A1 (The serving is better than the threshold)

[0768] When the first measurement reporting procedure is started, the remote terminal notifies the base station of the measurement result of the relay terminal and the identifier of the relay terminal using the first measurement report.

[0769] When the second measurement reporting procedure is started, the relay terminal notifies the base station of the measurement result of the remote terminal and the identifier of the remote terminal using the second measurement report.

[0770] 25. The CN node (e.g., AMF or SMF) can notify the base station of, for example, the addition, modification, or removal of a multi-path configuration in the QoS profile for the remote terminal and / or the relay terminal. The QoS profile is transmitted from the CN node to the base station.

[0771] - The information about the multi-path of the QoS profile can indicate whether the multi-path can be configured for any one of the following.

[0772] Each PDU session

[0773] Each QoS flow

[0774] Each remote terminal

[0775] Each relay terminal

[0776] Each frequency

[0777] Each cell

[0778] Each RAT

[0779] Each PLMN

[0780] Each tracking area

[0781] Each base station

[0782] 26. Based on the first / second terminal information message and / or the first / second measurement report and / or the aforementioned multipath configuration, the base station determines to add, modify, or release the indirect path of the indirect bearer and / or split bearer for the relayed bearer / channel.

[0783] When the base station determines to add, modify, or release the indirect path of the indirect bearer and / or split bearer for the relayed bearer / channel according to the following Option 1 or Option 2, the base station transmits an RRCReconfiguration message to each of the relay terminal and the remote terminal, for example (S169). For the modification of the relayed bearer / channel, the base station can transmit an RRCReconfiguration message according to Option 1 as described below, while for the release of the relayed bearer / channel, the base station can transmit an RRCReconfiguration message according to Option 2 as described below.

[0784] - If the SL-DestinationIdentity corresponding to the remote terminal is included in the sl-L2RelayUEConfig of the RRCReconfiguration message, the relay terminal releases the L2 U2N remote terminal and releases all indirect bearers and one or more split bearers for the remote terminal.

[0785] - If the SL-DestinationIdentity corresponding to the remote terminal in the sl-L2RelayUEConfig of the RRCReconfiguration message and the BearerIdentity or SL-DestinationIdentity corresponding to the indirect bearer or split bearer for the remote terminal are included, the relay terminal releases one or more L2 entities (e.g., RLC entity) and the logical channels corresponding to the indirect bearer or split bearer for the remote terminal.

[0786] - If the (SL-DestinationIdentity corresponding to the relay terminal and) BearerIdentity or SL-DestinationIdentity corresponding to the indirect bearer or split bearer for the remote terminal are included in the l-L2RemoteUEConfig of the RRCReconfiguration message, the remote terminal releases or modifies one or more L2 entities (e.g., RLC entity) and the logical channels corresponding to the indirect bearer or split bearer for the relay terminal according to the message. The remote terminal can also add or modify a direct bearer to change the indirect / split bearer to a direct bearer.

[0787] - If the SL-DestinationIdentity corresponding to the relay terminal is included in the sl-L2RemoteUEConfi of the RRCReconfiguration message, the remote terminal releases all indirect bearers for the relay terminal according to the message and releases or modifies one or more split bearers. The remote terminal may add or modify a direct bearer to change the indirect / split bearer to a direct bearer.

[0788] A. Option 1: The joint RRC reconfiguration can be used for the remote terminal and the relay terminal to modify or release the indirect bearer and / or split bearer. Furthermore, the connection of the U2N infrastructure can also be released.

[0789] The base station transmits an RRCReconfiguration message to the relay terminal to modify or release an indirect bearer and / or a split bearer by the relay terminal. Further, the connection of the U2N infrastructure can be released by the relay terminal. The RRCReconfiguration message includes at least a first part and a second part. The first part includes configurations related to the indirect / split bearer applied to the relay terminal, and the second part includes configurations related to the indirect / split bearer applied to the remote terminal. The second part also includes configurations related to the direct bearer applied to the remote terminal.

[0790] a. Option 1A: The relay terminal transmits a Uu RRC message (e.g., an RRCReconfiguration message) to the remote terminal to convey the second part to the remote terminal.

[0791] - For example, the second part is included in the RRC container of the RRCReconfiguration message. The base station encrypts the first part with a first security key configured between the base station and the relay terminal, while encrypting the second part with a second security key configured between the base station and the remote terminal. When the relay terminal receives the RRCReconfiguration message and 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, when the relay terminal cannot successfully apply the configuration of the first part, the relay terminal may not convey the second part of the RRC container to the remote terminal.

[0792] - 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 directly suspends the bearer and initiates the RRC reconfiguration procedure to suspend or release the indirect / split bearer. The remote terminal can also release the PC5-RRC connection with the relay terminal.

[0793] 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 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.

[0794] In the case of the RRC reconfiguration procedure by the relay terminal, the remote terminal transmits the 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 RRCReestablishmentCompletemesage 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.

[0795] - If the remote terminal fails to 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.

[0796] - Upon receiving the release of the PC5-RRC connection or a sidelink relay reconfiguration failure or a multi-path configuration failure, the relay terminal transmits an RRCReconfigurationFailure or RRCReconfigurationComplete message indicating a failure in the U2N configuration or multi-path configuration to the base station. The RRC container of the RRCReconfigurationComplete message transmitted from the relay terminal to the base station can include the RRCReconfigurationComplete message received at the remote terminal. Alternatively, if the PC5-RRC connection is released or a sidelink relay reconfiguration failure or a multi-path configuration failure is received or detected, or if the relay terminal cannot successfully apply the configuration of the first part, the relay terminal initiates an RRC reconfiguration procedure to directly terminate the bearer and terminate or release the indirect / split bearer for the relay terminal. 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 in the U2N configuration or multi-path configuration and the source or destination ID of the relay terminal and / or the remote terminal.

[0797] b. Option 1B: The relay terminal transmits a PC5 RRC message (e.g., RRCReconfigurationSidelink message or UuMessageTransferSidelink message) to the remote terminal to convey the second part to the remote terminal.

[0798] - 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 configured 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). Then, the relay terminal encrypts the second part using the third security key configured on the PC5 interface between the relay terminal and the remote terminal. The relay terminal includes the second part in the RRCReconfigurationSidelink message sent to the remote terminal to transmit 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.

[0799] - 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 sends it to the relay terminal. If the remote terminal cannot successfully apply the configuration of the second part, the remote terminal encrypts the RRCReconfigurationFailureSidelink message indicating the failure of the U2N configuration or the multi-path configuration using the third security key and then sends it to the relay terminal. Alternatively, if the remote terminal fails to apply the configuration of the second part, the remote terminal directly suspends the bearer and starts the RRC reconfiguration procedure to suspend or release the indirect / split bearer. The remote terminal can also release the PC5-RRC connection with the relay terminal.

[0800] In the case of the RRC reconfiguration procedure in 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.

[0801] In the case of the RRC reconfiguration procedure by the relay terminal, after the remote terminal transmits the 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.

[0802] - Upon receiving an RRCReconfigurationFailureSidelink message, or upon receiving a sidelink relay reconfiguration failure or a multi-path configuration failure, or detecting 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 indicating a failure of the U2N configuration or the multi-path configuration to the base station. Alternatively, upon receiving an RRCReconfigurationFailureSidelink message, or upon receiving a sidelink relay reconfiguration failure or a multi-path configuration failure, or detecting a sidelink failure (e.g., due to expiration of timer T400), if the relay terminal cannot successfully apply the configuration of the first part, the relay terminal shall initiate an RRC reconfiguration procedure to temporarily suspend its direct bearers and to temporarily suspend or release its indirect / split bearers. The relay terminal may 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 shall perform a random access to the base station and, as a result of the procedure, configure only the direct bearers. In the RRC reconfiguration procedure, the relay terminal shall send 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.

[0803] In Option 1, when the remote terminal or the relay terminal performs an RRC reconfiguration procedure, it can also notify the base station which terminal was unable to apply the U2N configuration or the multi-path configuration, i.e., whether it was the remote terminal or the relay terminal.

[0804] B. Option 2: A separate transmission of the RRC reconfiguration is used for the remote terminal and the relay terminal to modify or release the indirect bearers and / or the split bearers, and further, the connection of the U2N infrastructure can be released.

[0805] > The base station can send a first RRCReconfiguration message to the relay terminal and release the connection of the U2N base by the relay terminal for modifying or releasing an indirect bearer and / or a split bearer. The first RRCReconfiguration message includes at least the configuration related to the indirect / split bearer applied to the relay terminal.

[0806] - If the relay terminal receives the first RRCReconfiguration message and can successfully apply the configuration of the first message, the relay terminal sends 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, when the PC5-RRC connection is released or it detects a side-link relay reconfiguration failure or a multi-path configuration failure, the relay terminal starts an RRC reconfiguration procedure to temporarily suspend or release its direct bearer and indirect / split bearers. The relay terminal can also release the PC5-RRC connection with the remote terminal or notify the remote terminal of a side-link 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 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.

[0807] > The base station can send a second RRCReconfiguration message to the remote terminal and release the connection of the U2N base by the relay terminal for modifying or releasing an indirect bearer and / or a split bearer. The second RRCReconfiguration message includes the configuration related to the indirect / split bearer applied to the remote terminal. The second RRCReconfiguration message can also include the configuration related to the direct bearer applied to the remote terminal.

[0808] - The base station can directly transmit a second RRCReconfiguration message to the remote terminal from the Uu interface using SRB1.

[0809] If the remote terminal receives the second message and can successfully apply the configuration of the second message, the remote terminal transmits an RRCReconfigurationComplete message to the base station. If the remote terminal fails to successfully apply the configuration of the second message, the remote terminal directly or indirectly transmits an RRCReconfigurationFailure or RRCReconfigurationComplete message indicating a U2N configuration or multi-path configuration failure to the base station. The RRCReconfigurationComplete or RCReconfigurationFailure message is directly transmitted to the base station using SRB1 or indirectly transmitted to the base station by the relay terminal using SL-RLC1 for SRB1. If the remote terminal fails to successfully apply the configuration of the second message, the remote terminal can release the PC5-RRC connection with the relay terminal or notify the relay terminal of a side-link relay reconfiguration failure or multi-path configuration failure.

[0810] Alternatively, if the remote terminal fails to apply the configuration of the second message, the remote terminal shall initiate an RRC reconfiguration procedure to directly suspend the bearer by itself and to suspend or release the indirect / split bearer. The remote terminal may also release the PC5-RRC connection with the relay terminal and / or inform the relay terminal of the sidelink relay reconfiguration failure or multi-path configuration failure. In the Uu interface, in the case of the RRC reconfiguration procedure, the remote 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 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. In the case of the RRC reconfiguration procedure by the relay terminal, after the remote terminal sends the RRCReestablishmentComplete message to the relay terminal using SL-RLC1 for SRB1, the relay terminal shall transmit the RRCReestablishmentComplete message to the base station. The RRCReestablishmentComplete message indicates 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.

[0811] When the PC5-RRC connection is released or a sidelink relay reconfiguration failure or multi-path configuration failure is received, the relay terminal shall send an RCReconfigurationFailure or RRCReconfigurationComplete message indicating the failure of the U2N configuration or multi-path configuration to the base station. At the remote terminal, when an RRCReestablishmentRequest message is received, the RRC container of the RRCReconfigurationComplete message sent from the relay terminal to the base station may include the RRCReestablishmentRequest message received at the remote terminal.

[0812] Alternatively, if the PC5-RRC connection is released, or the side-link relay reconfiguration fails or the multi-path configuration fails are received or detected, or the relay terminal fails to apply the configuration of the first message, the relay terminal shall initiate an RRC reconfiguration procedure to temporarily suspend its own direct bearer and to suspend or release the indirect / split bearer. The relay terminal may also release the PC5-RRC connection with the remote terminal or notify the remote terminal of the side-link relay reconfiguration failure or the 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 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 an RRCReestablishmentRequest message is received from the remote terminal, the RRC container of the RRCReestablishmentComplete message sent from the relay terminal to the base station may include the RRCReestablishmentRequest message received from the remote terminal.

[0813] - Alternatively, the base station may indirectly send the second RRCReconfiguration message to the relay terminal using the PC5 relay RLC channel for SRB1, i.e., SL-RLC1.

[0814] 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 from the base station to the remote terminal. The relay terminal also sends an RRCReconfigurationComplete message to the base station. However, if the relay terminal receives the first message and fails to successfully apply the configuration of the first message, or if the PC5-RRC connection is released, or if it 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, directly suspends its own bearers, and initiates an RRC reconfiguration procedure to suspend or release the indirect / split bearers. 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 bearers. In the RRC reconfiguration procedure, the relay terminal sends 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.

[0815] When the relay terminal notifies the remote terminal of a side-link relay reconfiguration failure or a multi-path configuration failure, the remote terminal initiates an RRC reconfiguration procedure to temporarily suspend its direct bearer and to temporarily suspend or release its indirect / split bearer. The remote terminal can also release its PC5-RRC connection with the relay terminal. In the case of an 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, 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. 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 conveys 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.

[0816] 27. In the above-described stage, the relay terminal and the remote terminal can release one or all of the indirect bearers and / or split bearers that can be reconfigured with the direct bearer. As a result of this stage, the remote terminal can maintain either the direct link and the indirect link by the relay terminal, or the remote terminal can release the indirect link by the relay terminal and maintain only the direct link and release the PC5-RRC connection with the relay terminal.

[0817] To release the indirect path of the split bearer for the indirect bearer or the multi-path indirect path, the remote terminal or the relay terminal performs one or more of the following.

[0818] A. The receiving PDCP entity of the bearer of the remote terminal can trigger a PDCP status report to be transmitted to the base station as described below.

[0819] > The PDCP status report is transmitted directly from the remote terminal to the base station or indirectly to the base station by the relay terminal.

[0820] > The PDCP status report is transmitted directly from the remote terminal to the base station or indirectly to the base station by the relay terminal.

[0821] > When receiving the PDCP status report, the bearer transmission PDCP entity of the base station triggers "multi-path data switching" to retransmit or transmit the PDCP SDU on the direct path towards the remote terminal as described below.

[0822] > When receiving / receiving before the RRCReconfiguration message for bearer release, or when releasing / before releasing the PC5-RRC connection, the SL RLC entity of the remote terminal or relay terminal performs one or more of the following.

[0823] - Option 1: The remote terminal releases the Uu RLC entity and / or the PC5 RLC entity for the downstream indirect path of the bearer. As a result, the SL data buffered in the TX RLC entity is deleted / is deleted, or the DL data buffered in the RX RLC entity is deleted.

[0824] - Option 2: In the case of the SL RLC entity of the PC5 RLC channel for the downstream indirect path of the bearer, the AM RLC entity of the relay terminal polls the peer AM RLC entity and triggers the RLC status report of the peer AM RLC entity of the remote terminal. Based on the polling, the AM RLC entity of the remote terminal triggers the RLC status report to be transmitted to the peer AM RLC entity of the relay terminal.

[0825] - Option 3: For the SL RLC entity of the PC5 RLC channel with respect to the downstream indirect path of the bearer, the AM RLC entity of the remote terminal triggers the RLC status report to be sent to the peer AM RLC entity of the relay terminal.

[0826] > When receiving the RLC status report from the receiving RLC entity, the SL transmitting RLC entity of the relay terminal retransmits the RLC SDU or RLC SDU segment for which a negative acknowledgment has been received by the RLC status report, as described below.

[0827] B. The bearer receiving PDCP entity of the base station can trigger the PDCP status report to be sent to the remote terminal, as described below.

[0828] > The PDCP status report is sent directly from the base station to the remote terminal or indirectly to the remote terminal by the relay terminal.

[0829] > When receiving the PDCP status report, the bearer transmitting PDCP entity of the remote terminal triggers "multi-path data switching" and retransmits or transmits the PDCP SDU on the direct path towards the base station, as described below.

[0830] > When receiving / receiving before the RRCReconfiguration message for bearer release or when releasing / before releasing the PC5-RRC connection, the SL RLC entity of the relay terminal or the remote terminal performs one or more of the following.

[0831] - Option 1: The relay terminal releases the Uu RLC entity and / or the PC5 RLC entity for the upstream indirect path of the bearer. As a result, the SL data buffered in the RX RLC entity is deleted / is removed, or the UL data buffered in the TX RLC entity is deleted.

[0832] - Option 2: For the SL RLC entity of the PC5 RLC channel for the upstream indirect path of the bearer, the AM RLC entity of the remote terminal polls the peer AM RLC entity and triggers the RLC status report of the peer AM RLC entity of the relay terminal. Based on the polling, the AM RLC entity of the relay terminal triggers the RLC status report to be sent to the peer AM RLC entity of the remote terminal.

[0833] - Option 3: For the SL RLC entity of the PC5 RLC channel for the upstream indirect path of the bearer, the AM RLC entity of the relay terminal triggers the RLC status report to be sent to the peer AM RLC entity of the remote terminal.

[0834] > When receiving the RLC status report from the receiving RLC entity, the SL transmitting RLC entity of the remote terminal retransmits the SL RLC SDU or SL RLC SDU segment for which a negative acknowledgment has been received by the RLC status report as described below until the PC5-RRC release and / or the bearer release of Uu / PC5 are performed.

[0835] - When receiving the SL RLC SDU and / or SL RLC SDU segment from the remote terminal, the relay terminal performs an uplink retransmission of the UL RLC SDU or UL RLC SDU segment corresponding to the SL RLC SDU and / or SL RLC SDU segment until the PC5-RRC connection or the bearer is released.

[0836] > Thereafter, the relay terminal and / or the remote terminal notify the base station of the release of the PC5-RRC connection and / or the bearer, for example, by transmitting a terminal information message to the base station.

[0837] - Before / after receiving the terminal information message, the base station releases the PDCP / RLC entity (or entities) corresponding to the bearer and / or the PC5-RRC connection.

[0838] - Before or after the relay terminal and / or remote terminal transmits a terminal information message, or when transmitting an RRCReconfiguration message that releases the bearer to the remote terminal and / or relay terminal, the bearer and / or the Uu / PC5 PDCP / RLC entity (or entities) corresponding to the PC5-RRC connection are released.

[0839] C. Before receiving or before receiving an RRCReconfiguration message that releases the bearer, or before receiving or before releasing the PC5-RRC connection for the downstream indirect path of the bearer, the relay terminal suspends all RLC status reporting procedures in the DL receive RLC entity and / or the SL transmit RLC entity, and the relay terminal releases the DL receive RLC entity and / or the SL transmit RLC entity. To release the peer SL receive RLC entity of the remote terminal, the relay terminal can also transmit an RRCReconfigurationSidelink message to the remote terminal.

[0840] According to the present invention described above, the network configures multi-path operation. In particular, when the UE can support the U2N relay function via SL, the present invention can release the indirect path of the multi-path operation for the relay terminal and the remote terminal without loss or with minimal loss.

[0841] The present invention has the advantage that the system can appropriately provide a multi-path operation including a direct link and an indirect link via U2N relay. The prior art does not have a mechanism for providing a multi-path operation in side-link relay.

[0842] Addition of Direct Path to Indirect Path Infrastructure for Multi-Path Operation

[0843] Hereinafter, a method of further configuring a direct path with a base station via an indirect path based on an RRC reconfiguration message and / or a method of forming both an indirect path and a direct path based on an RRC reconfiguration message will be described.

[0844] Also, when split radio bearers for the direct path and the indirect path are configured based on the RRC reconfiguration message, a method for determining the basic path for the split radio bearer (hereinafter referred to as the split bearer) will be described in detail.

[0845] On the other hand, the following is based on the content described in Sections "1" to "27" described with reference to FIG. 16.

[0846] FIG. 17 is a diagram for explaining a method by which a remote terminal configures a split bearer.

[0847] When an indirect path is configured for the remote terminal, the remote terminal can further configure a direct path by means of a U2N relay. Alternatively, while connecting the indirect path, the remote terminal can simultaneously configure the indirect path and the direct path by means of an RRC reconfiguration message (S171).

[0848] 1. The base station can determine the multi-path configuration according to the following information (S172).

[0849] > Option 1: The remote terminal (or relay terminal) reports measurement information for the relay terminal to the base station via the direct path or the indirect path.

[0850] > Option 2: The remote terminal reports the PC5-RRC connection setup to the base station by means of sidelink terminal information.

[0851] - At this time, the sidelink terminal information can be reported by the relay terminal.

[0852] - Alternatively, if the relay terminal (or remote terminal) does not have a direct RRC connection, the remote terminal (or relay terminal) can first perform a RACH procedure and directly transmit the sidelink terminal information to the base station.

[0853] > Option 3: The relay terminal reports the PC5-RRC connection setup by means of sidelink terminal information.

[0854] 2. The remote terminal can perform cell reselection before performing the RACH procedure.

[0855] In the case of cell reselection according to the prior art, the PCell of the remote terminal and the PCell of the relay terminal may be different. For example, the remote terminal preferentially selects the PCell of the relay terminal by cell reselection. Alternatively, the remote terminal selects the cell of the serving base station of the relay by cell reselection. For example, the base station instructs the remote terminal to preferentially select the PCell of the relay terminal.

[0856] On the other hand, the base station can instruct the cell selected by the remote terminal based on the measurement report of the relay terminal or the remote terminal.

[0857] 3. When there is no direct RRC connection to the remote terminal, the RACH procedure is performed as follows (S173).

[0858] For example, the remote terminal transmits a RACH MSG3 or MSGA PUSCH including a C-RNTI MAC CE.

[0859] > Alt 1: RACH procedure trigger for the remote terminal based on paging

[0860] - The base station can transmit indirect paging to the remote terminal (by the relay terminal). At this time, the paging may include the C-RNTI and s-TMSI of the remote terminal, or may not include the terminal ID. An indicator for triggering RACH (e.g., multiple paths as a paging cause) may be included in the paging message.

[0861] - Upon receiving the indirect paging, the remote terminal performs RACH to the base station.

[0862] - Alternatively, the remote terminal that supports multiple paths can monitor paging by itself.

[0863] For example, the remote terminal can calculate the PO based on the C-RNTI and monitor paging.

[0864] Alternatively, similar to the paging operation of the idle / inactive UE, the remote terminal can calculate the PO based on the s-TMSI and monitor paging.

[0865] > Alt 2: The RACH procedure of the remote terminal can be triggered by the relay terminal.

[0866] - The method by which the relay terminal triggers the RACH transmission of the remote terminal is as follows.

[0867] 2A: Trigger the RACH procedure in a specific field of the SCI

[0868] 2B: Trigger the RACH procedure with the SL MAC CE

[0869] 2C: Trigger the RACH procedure with the SL RRC message

[0870] > Alt 3: The RRC connection setup of the relay terminal can be triggered based on the SIB / capability.

[0871] - For example, the base station can configure multiple paths, and if the remote / relay terminal supports multiple paths, the remote terminal can initiate the RACH procedure.

[0872] For example, the base station can configure multiple paths for the relay terminal and / or the remote terminal by means of the SIB or the dedicated RRC signal. In this case, the remote terminal can initiate the RACH procedure.

[0873] > Alt 4: When the base station indirectly transmits an RRC reconfiguration message (as in the following process), the remote terminal can trigger an RACH procedure before transmitting an RRC reconfiguration complete message. For example, the remote terminal can use the RACH procedure triggering method of Alt 2.

[0874] 4. The base station can add a direct connection through an RRC reconfiguration process (S174).

[0875] - RRC reconfiguration is a message for the direct bearer or split bearer of the remote terminal, but the indirect bearer of the relay terminal needs to be switched to a direct bearer or split bearer by RRC reconfiguration. Therefore, an RRC reconfiguration message for switching from an indirect bearer to a direct bearer or split bearer may be defined separately. Alternatively, the switching from an indirect bearer to a direct bearer or split bearer is indicated or configured using a conventional RRC reconfiguration message.

[0876] - Alternatively, even if the remote terminal is already connected in a multi-path manner, bearer modification or radio reconfiguration is possible by RRC reconfiguration.

[0877] - For example, a U2N bearer (i.e., a Uu relay RLC channel and a PC5 relay RLC channel) may not be set for a relay terminal in the connected mode and a remote terminal with a PC5-RRC connection established. In this case, the base station can configure an indirect path and a direct path for the remote terminal at once through the RRC reconfiguration process.

[0878] - Here, the RRC reconfiguration process can be performed according to an RRC reconfiguration method using Sync according to the base station settings. In this case, the remote terminal can trigger an RACH procedure for transmitting an RRC reconfiguration complete message in the same way as the PCell change method. Also, the cell in which the remote terminal performs the RACH procedure is, for example, the target cell indicated by the RRC reconfiguration message.

[0879] On one hand, when the PCell of the remote terminal and the PCell of the relay terminal are configured differently, the RRC reconfiguration process is performed in the same or a similar manner as the method of simultaneously configuring the source cell and the target cell in DAPS HO (Dual Active Protocol Stack Handover).

[0880] Alternatively, the RRC reconfiguration message can instruct or configure to change the basic path of the split bearer from the indirect path to the direct path. For example, when the basic path is not set for a specific radio bearer, the direct path can be preferentially set as the basic path among the indirect path and the direct path.

[0881] Alternatively, for a specific type of SRB among multiple SRB types, the direct path can always be preferentially set as the basic path. For example, the basic path of the split bearer is not set. In this case, when the type of the split bearer is SRB1 and / or SRB2, the basic path of the split bearer is configured or determined to be the direct path (basic value).

[0882] Here, the multiple SRB types include SRB0, SRB1, SRB2, and SRB3. SRB0 is for RRC messages using the CCCH (Common Control Channel) logical channel. SRB1 is for RRC messages (including piggyback NAS messages) and NAS messages before the SRB2 setting, both of which use the DCCH logical channel. SRB2 is for NAS messages using the DCCH (Dedicated Control Channel) logical channel. SRB2 has a lower priority than SRB1 and is always configured by the network after security activation. SRB3 is for specific RRC messages using the DCCH logical channel when the terminal is in EN-DC.

[0883] Specifically, referring to the aforementioned "21", the remote terminal can receive an RRCReconfiguration message related to the configuration of a split bearer (split radio bearer) from the base station. The RRCReconfiguration message may not need to set the basic path of the split bearer among the direct path and the indirect path. In this case, the remote terminal can determine the basic path of the split bearer among the direct path and the indirect path according to the split bearer type.

[0884] For example, when the split bearer type is SRB1 or SRB2, the remote terminal can always determine the direct path as the basic path. Alternatively, even if the indirect path is indicated as the basic path in the RRCReconfiguration message, the remote terminal can always determine the direct path for the split bearer of SRB1 or SRB2 as the basic path.

[0885] That is, the basic paths for the split bearers SRB1 and SRB2 are always configured as the direct path.

[0886] 5. When the RRC reconfiguration process is completed, the base station can exchange messages regarding the modifications related to the PDU (Protocol Data Unit) session and bearers with the UPF and the AMF (S175).

[0887] Hereinafter, the direct path through which the remote terminal is directly connected to the base station or the network is defined as the first radio path. Also, the indirect path through which the remote terminal is indirectly connected to the base station or the network by means of a relay terminal is defined as the second radio path.

[0888] FIG. 18 is a diagram illustrating a method for the remote terminal to configure a split bearer for a multi-path including the first radio path and the second radio path by means of an RRC configuration message.

[0889] As shown in FIG. 16, the remote terminal can constitute a second radio path indirectly connected to the network by the relay terminal. Thereafter, the remote terminal reports quality information measured for the relay terminal and the sidelink configured for the second radio path to the network via the second radio path. The network can transmit an RRC configuration message (or an RRC reconfiguration message) for adding a first radio path (a radio path through which the network and the remote terminal are directly connected) to the remote terminal according to the quality information.

[0890] Alternatively, the remote terminal can transmit a request message to the network for further configuring a first radio path for direct connection with the network according to the quality information. In this case, the remote terminal can receive an RRC configuration message for further configuring the first radio path.

[0891] Referring to FIG. 18, the remote terminal can configure a split bearer for a multi-path including a first radio path and a second radio path (S801). The remote terminal can configure the split bearer according to a configuration message (for example, an RRC configuration message or an RRC reconfiguration message) for configuring the split bearer for the first radio path and the second radio path received from the network. Further, the remote terminal can configure a multi-path in which the first radio path is added by the configuration of the split bearer according to the RRC configuration message.

[0892] On one hand, the remote terminal needs to determine the basic path for the split bearer in order to transmit the RRC message. Specifically, the remote terminal can determine the basic path from the first radio path and the second radio path according to the split bearer type. When the split bearer is SRB1 and / or SRB2, the remote terminal can determine the basic path of the split bearer to the first radio path. Here, SRB1 is the SRB for the RRC message using the dedicated control channel (DCCH) logical channel, and SRB2 is the SRB for the non-access stratum (NAS) message using the dedicated control channel (DCCH) logical channel. That is, when the type of the configured split bearer is the split bearer related to SRB1 or SRB2, the remote terminal can determine the first radio path as the basic path for transmitting the RRC message even without another instruction for the basic path of the split bearer.

[0893] For example, when the split bearer is SRB1 and / or SRB2, the remote terminal can always determine the basic path of the split bearer to the first radio path. On the other hand, when the split bearer is of the data radio bearer (DRB) type, the remote terminal can determine the basic path of the split bearer to the first radio path or the second radio path.

[0894] Alternatively, when the split bearer is SRB1 and / or SRB2, the RRC configuration message can always configure the basic path for the split bearer to the first radio path.

[0895] Alternatively, when the split bearer is SRB1 and / or SRB2, the basic path for the split bearer is determined to the first radio path regardless of the basic path configured by the RRC configuration message.

[0896] Alternatively, when the RRC configuration message indicates the basic path to the second radio path, the remote terminal determines the basic path for the split bearer related to SRB1 or SRB2 to the first radio path without considering the indication. Also, the remote terminal can determine the basic path for other types of split bearers to the second radio path according to the RRC configuration message.

[0897] Next, when the configured split bearer is SRB1 or SRB2, the remote terminal can send an RRC-related message to the network via the first radio path, which is the determined basic path (S803). For example, a message related to an RRC control message can always be transmitted and received via the first radio path, which is the basic path of the split bearer.

[0898] In this way, even if the split bearers for the first radio path and the second radio path are configured without an indication of the basic path, the basic path of the split bearer for a specific SRB type can be clearly determined. That is, even without an indication in the RRC configuration message, the basic path for SRB1 or SRB2 related to the transmission of RRC messages can be clearly determined.

[0899] Also, since the RRC configuration message for multi-path configuration does not need to indicate a different basic path for the split bearer, the signal load of the RRC configuration message related to the split bearer configuration for multi-path can be minimized.

[0900] Although not limited thereto, the various descriptions, functions, procedures, proposals, methods, and / or flowcharts of the present invention disclosed in this specification can be applied to various fields that require wireless communication / connection between devices (e.g., 5G).

[0901] The following will be described more specifically 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.

[0902] FIG. 19 illustrates a communication system applicable to the present invention.

[0903] Referring to FIG. 19, 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. Not limited thereto, the wireless devices include a robot 100a, vehicles 100b-1, 100b-2, an XR (Extended Reality) device 100c, a hand-held device 100d, a home appliance 100e, an IoT (Internet of Thing) device 100f, and an AI device / server 400. For example, the vehicle includes a vehicle equipped with a wireless communication function, an autonomous driving vehicle, a vehicle capable of vehicle-to-vehicle communication, etc. Here, the vehicle includes a UAV (Unmanned Aerial Vehicle) (for example, a drone). The XR device includes an AR (Augmented Reality) / VR (Virtual Reality) / MR (Mixed Reality) device, and is embodied in the form of an HMD (Head-Mounted Device), a HUD (Head-Up Display) provided 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 device includes a smartphone, a smart pad, a wearable device (for example, a smartwatch, smart glasses), a computer (for example, a notebook personal computer, etc.). The home appliance includes a TV, a refrigerator, a washing machine, etc. The IoT device includes a sensor, a smart meter, 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.

[0904] 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.

[0905] Wireless communications / connections 150a, 150b, and 150c are performed between wireless devices 100a to 100f / base station 200 and between base station 200 / base station 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, the wireless device and the base station / wireless device, and the base station and the base station can transmit / receive wireless signals to / from each other. For example, wireless communications / connections 150a, 150b, and 150c can transmit / receive signals via various physical channels. For this purpose, based on various proposals of the present invention, any one of the setting process of various configuration information for transmitting / receiving wireless signals, various signal processing processes (e.g., channel encoding / decoding, modulation / demodulation, resource mapping / demapping, etc.), and resource allocation process is performed.

[0906] FIG. 20 illustrates a wireless device applicable to the present invention.

[0907] Referring to FIG. 20, the first wireless device 100 and the second wireless device 200 transmit and receive wireless signals using 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. 19 and / or {the wireless device 100x, the wireless device 100x}.

[0908] 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 that performs some or all of the processes controlled by the processor 102, or includes instructions 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.

[0909] Specifically, the terminal can include a processor 102 and a memory 104 connected to the RF transceiver. The memory 104 can include at least one program for performing operations related to the foregoing embodiments with reference to FIGS. 16 to 18. For example, the memory 104 can receive an RRC (Radio Resource Control) message that configures a split bearer for a first radio path directly connected to the network by the relay terminal and a second radio path indirectly connected to the network, and can include at least one program for transmitting a message to the network via a basic path for the split bearer. Here, the basic path of the split bearer is determined by the first radio path based on an RRC configuration message that configures a split bearer related to a specific type of SRB (Signaling Radio Bearer).

[0910] Alternatively, a chipset including the processor 102 and the 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.

[0911] 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 connected 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 connected to the processor 202 and transmits and / or receives wireless signals through 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, the wireless device also means a communication modem / circuit / chip.

[0912] 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.

[0913] 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, and the like. 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, instructions, and / or sets of instructions.

[0914] One or more memories 104, 204 are connected 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 composed of 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 connected to the one or more processors 102, 202 by various techniques such as wired or wireless connections.

[0915] One or more transceivers 106, 206 transmit user data, control information, radio signals / channels, etc. mentioned in this specification, such as in 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, etc. 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, etc. 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.

[0916] FIG. 21 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. 19).

[0917] Referring to FIG. 21, the wireless devices 100 and 200 correspond to the wireless devices 100 and 200 in FIG. 20 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, 202 and / or one or more memories 104, 204 in FIG. 20. For example, the transceiver 114 includes one or more transceivers 106, 206 and / or one or more antennas 108, 208 in FIG. 20. 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) by the communication unit 110 via a wireless / wired interface, or stores the information received from the outside (e.g., other communication devices) by the communication unit 110 via a wireless / wired interface in the memory unit 130.

[0918] The additional elements 140 are variously configured depending on the type of 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. 19, 100a), a vehicle (FIGS. 19, 100b-1, 100b-2), an XR device (FIGS. 19, 100c), a portable device (FIGS. 19, 100d), a home appliance (FIGS. 19, 100e), an IoT device (FIGS. 19, 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. 19, 400), a base station (FIGS. 19, 200), and a network node. The wireless device is movable depending on the usage example / service or is used at a fixed location.

[0919] In FIG. 21, 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 (for example, 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 such as a communication control processor, an application processor, an ECU (Electronic Control Unit), a graphic processing processor, and a memory control processor. As another example, the memory unit 130 is composed of a RAM (Random Access Memory), a DRAM (Dynamic RAM), a ROM (Read Only Memory), a flash memory, a volatile memory, a non-volatile memory, and / or a combination thereof.

[0920] FIG. 22 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.

[0921] Referring to FIG. 22, 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.

[0922] The communication unit 110 transmits and receives signals (such as data, control signals, etc.) with external devices such as other vehicles, base stations (e.g., base stations, roadside units, etc.), and servers. The control unit 120 controls the elements of the vehicle or the 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 the 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, etc. The power supply unit 140b supplies power to the vehicle or the autonomous driving vehicle 100 and includes a wired / wireless charging circuit, a battery, etc. The sensor unit 140c can obtain vehicle state, surrounding environment information, user information, etc. 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, etc. 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.

[0923] 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 the traffic information data of surrounding vehicles from the surrounding vehicles. Further, the sensor unit 140c obtains the vehicle state and the 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 the traffic information data in advance using AI technology, etc. 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.

[0924] Here, the wireless communication technology implemented in the wireless devices (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, the 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 devices (XXX, YYY) of this specification communicates based on LTE-M technology. At this time, as an example, the 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, the 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 devices (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, the 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.

[0925] 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 without being combined 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 the 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.

[0926] In this specification, the embodiments of this invention are mainly described centered around 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. 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 consisting 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.

[0927] Embodiments according to the present invention can be implemented by various means, such as hardware, firmware, software, or combinations thereof. In the case of implementation by hardware, an embodiment of the present invention is implemented by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, etc.

[0928] In the case of implementation by firmware or software, an 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.

[0929] 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

[0930] 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 remote terminal (UE) to perform communication, comprising: an operation of configuring a split bearer including a first radio path directly connected to a network and a second radio path indirectly connected to the network by a relay terminal; an operation of transmitting an RRC (Radio Resource Control) message to the network via a basic path for the split bearer; and When configuring the split bearer, the basic path for the split bearer is determined to be the first radio path according to the type of the split bearer, which is a specific type of SRB (Signaling Radio Bearer) for transmitting the RRC message.

2. further comprising an operation of receiving an RRC configuration message for configuring the split bearer; The RRC configuration message for configuring the split bearer related to the specific type of SRB always configures the basic path with the first radio path, according to the method of Claim 1.

3. The method according to Claim 1, wherein the specific type is SRB1 for an RRC message using a DCCH (dedicated control channel) logical channel.

4. The method according to Claim 1, wherein the specific type is SRB2 for a NAS (non access stratum) message using a DCCH logical channel.

5. further comprising an operation of receiving an RRC configuration message for configuring the split bearer; The basic path of the split bearer is determined to be the first radio path based on the RRC configuration message in order to configure the split bearer without configuring a basic path, according to the method of Claim 1.

6. further comprising an operation of receiving an RRC configuration message for configuring the split bearer; The basic path of the split bearer is determined to be the first radio path regardless of the basic path configured by the RRC configuration message, according to the method of Claim 1.

7. further comprising an operation of receiving an RRC configuration message for configuring the split bearer; configuring the split bearer based on the RRC configuration message, and adding the first radio path to the remote terminal, according to the method of Claim 1.

8. further comprising an operation of receiving an RRC configuration message for configuring the split bearer; The method according to claim 1, wherein when the type of the split bearer is a data radio bearer (DRB) type, the basic path is determined for the second radio path based on the RRC configuration message.

9. Further including the operation of receiving an RRC configuration message constituting the split bearer, The method according to claim 1, wherein the RRC configuration message is received via the second radio path.

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

11. An apparatus for wireless communication, A memory configured to store instructions, A processor configured to execute the instructions to perform operations, including: The operations performed by the processor include: The operation of configuring a split bearer including a first radio path directly connected to a network and a second radio path indirectly connected to the network by a relay terminal (UE); The operation of transmitting an RRC (Radio Resource Control) message to the network via a basic path for the split bearer; An apparatus, wherein when configuring the split bearer, the basic path for the split bearer is determined for the first radio path according to the type of the split bearer, which is a specific type of SRB (Signaling Radio Bearer) for transmitting the RRC message.

12. The apparatus according to claim 11, wherein the apparatus is an application-specific integrated circuit (ASIC) or a digital signal processor.

13. The apparatus according to claim 11, wherein the apparatus is a terminal (UE) operating in a 3GPP (registered trademark) (3rd generation partnership project) based wireless communication system.

14. In a wireless communication system, a method for a network to receive a signal, including: The operation of transmitting an RRC (Radio Resource Control) configuration message for configuring a split bearer for a first radio path directly connected to a remote terminal (UE) and a second radio path indirectly connected to the remote terminal by a relay terminal; The operation of receiving an RRC message from the remote terminal via a basic path for the split bearer. The method in which the RRC message is received via the first radio path determined as a basic path based on that the type of the split bearer is a specific type of SRB (signaling radio bearer) that transmits the RRC message.

15. A network for wireless communication, a transceiver, and a processor configured to control the transceiver, and includes: the processor is configured to transmit an RRC (radio resource control) configuration message that configures a split bearer for a first radio path directly connected to a remote terminal (UE) and a second radio path indirectly connected to the remote terminal by a relay terminal, and to receive an RRC message from the remote terminal via a basic path for the split bearer; The network in which the RRC message is received via the first radio path determined as a basic path based on that the type of the split bearer is a specific type of SRB (signaling radio bearer) that transmits the RRC message.

Images