Method and device for supporting multi-path-based communication in wireless communication system

Abstract

Disclosed are a method and device for supporting multi-path-based communication in a wireless communication system. The method performed by a terminal according to an embodiment of the present disclosure may comprise the steps of: receiving information, indicating whether to maintain a terminal-to-terminal connection on an indirect path, on the basis that at least one of a direct path or the indirect path for a multi-path operation is added or changed; and performing, on the basis of the information, one of a first operation of maintaining the terminal-to-terminal connection or a second operation of releasing the terminal-to-terminal connection and establishing a new terminal-to-terminal connection. Here, the information can be transferred through an RRC reconfiguration message from the base station.

Description

Method and device for supporting multipath-based communication in a wireless communication system

[0001] The present disclosure relates to a wireless communication system, and more particularly, to a method and device for supporting multi-path based communication in a wireless communication system.

[0002] Mobile communication systems were developed to provide voice services while ensuring user activity. However, they have expanded beyond voice to include data services. Currently, explosive growth in traffic is leading to resource shortages and users' demand for higher-speed services, necessitating a more advanced mobile communication system.

[0003] Next-generation mobile communication systems must support explosive data traffic growth, dramatically increasing data rates per user, a vastly increased number of connected devices, ultra-low end-to-end latency, and high energy efficiency. To achieve these goals, various technologies are being studied, including dual connectivity, massive multiple input multiple output (MIMO), in-band full duplex, non-orthogonal multiple access (NOMA), super wideband support, and device networking.

[0004] The technical problem of the present disclosure relates to a method and device for supporting multi-path based communication in a wireless communication system.

[0005] Specifically, the technical problem of the present disclosure relates to a method and device for clarifying whether an existing path is maintained when changing / adding a path in a wireless communication system.

[0006] The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by a person having ordinary skill in the technical field to which the present disclosure belongs from the description below.

[0007] A method performed by a base station according to one aspect of the present disclosure may include: establishing a direct path and an indirect path for a multi-path operation; and transmitting, based on addition or change of at least one of the direct path or the indirect path, information indicating whether to maintain a terminal-to-terminal connection on the indirect path to a terminal associated with the multi-path operation. Here, the terminal may correspond to at least one of a remote terminal of the direct path and the indirect path or a relay terminal providing the indirect path.

[0008] A method performed by a terminal according to an additional aspect of the present disclosure may include: receiving information indicating whether to maintain a terminal-to-terminal connection on an indirect path based on addition or change of at least one of a direct path and an indirect path for multi-path operation; and performing, based on the information, either a first operation of maintaining the terminal-to-terminal connection or a second operation of releasing the terminal-to-terminal connection and establishing a new terminal-to-terminal connection. Here, the information may be transmitted via an RRC (radio resource control) reconfiguration message by a base station.

[0009] According to various embodiments of the present disclosure, a method and apparatus for supporting multi-path based communication in a wireless communication system can be provided.

[0010] According to various embodiments of the present disclosure, a method and device for clarifying whether an existing path is maintained when changing / adding a path in a wireless communication system can be provided.

[0011] When adding / changing a direct / indirect path of the present disclosure, there is a technical effect of reducing unnecessary reconfiguration by allowing the base station to control whether to maintain a connection for the indirect path (e.g., PC5-RRC connection).

[0012] The effects that can be obtained from the present disclosure are not limited to the effects mentioned above, and other effects that are not mentioned will be clearly understood by a person having ordinary skill in the art to which the present disclosure pertains from the description below.

[0013] The accompanying drawings, which are incorporated in and are part of the detailed description to aid in understanding the present disclosure, provide embodiments of the present disclosure and, together with the detailed description, describe the technical features of the present disclosure.

[0014] Figure 1 illustrates the structure of a wireless communication system to which the present disclosure can be applied.

[0015] FIG. 2 illustrates a frame structure in a wireless communication system to which the present disclosure can be applied.

[0016] FIG. 3 illustrates a resource grid in a wireless communication system to which the present disclosure can be applied.

[0017] FIG. 4 illustrates a physical resource block in a wireless communication system to which the present disclosure can be applied.

[0018] FIG. 5 illustrates a slot structure in a wireless communication system to which the present disclosure can be applied.

[0019] FIG. 6 illustrates physical channels used in a wireless communication system to which the present disclosure can be applied and a general signal transmission and reception method using the same.

[0020] FIG. 7 illustrates a procedure for performing V2X or SL communication according to a transmission mode in a wireless communication system to which the present disclosure can be applied.

[0021] FIG. 8 illustrates a user plane protocol stack for a U2N (UE-to-network) relay procedure in a wireless communication system to which the present disclosure can be applied.

[0022] FIG. 9 illustrates a control plane protocol stack for a U2N relay procedure in a wireless communication system to which the present disclosure can be applied.

[0023] FIG. 10 is a diagram for explaining a process in which a base station performs communication according to one embodiment of the present disclosure.

[0024] FIG. 11 is a diagram for explaining a process in which a terminal performs communication according to one embodiment of the present disclosure.

[0025] FIG. 12 illustrates a signaling procedure between a terminal and a base station when adding a direct path according to an embodiment of the present disclosure.

[0026] FIG. 13 illustrates a signaling procedure between a terminal and a base station when a direct path is changed according to an embodiment of the present disclosure.

[0027] FIG. 14 illustrates a signaling procedure between a terminal and a base station when adding an indirect path according to an embodiment of the present disclosure.

[0028] FIG. 15 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.

[0029] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The detailed description set forth below, together with the accompanying drawings, is intended to explain exemplary embodiments of the present disclosure and is not intended to represent the only embodiments in which the present disclosure may be practiced. The following detailed description includes specific details to provide a thorough understanding of the present disclosure. However, one of ordinary skill in the art will appreciate that the present disclosure may be practiced without these specific details.

[0030] In some cases, to avoid obscuring the concepts of the present disclosure, known structures and devices may be omitted or illustrated in block diagram form focusing on the core functions of each structure and device.

[0031] In the present disclosure, when a component is said to be "connected," "coupled," or "connected" to another component, this may include not only a direct connection but also an indirect connection in which another component exists between them. Furthermore, the terms "comprises" or "has" in the present disclosure specify the presence of the mentioned features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0032] In this disclosure, terms such as “first,” “second,” etc. are used only to distinguish one component from another and are not used to limit the components, and do not limit the order or importance between the components unless specifically stated otherwise. Accordingly, within the scope of this disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and similarly, a second component in one embodiment may be referred to as a first component in another embodiment.

[0033] The terminology used herein is for the purpose of describing particular embodiments and is not intended to limit the scope of the claims. As used in the description of the embodiments and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. The term "and / or" as used herein may refer to any one of the associated enumerated items, or is meant to refer to and encompass any and all possible combinations of two or more of them. Furthermore, the use of " / " between words in this disclosure has the same meaning as "and / or" unless otherwise stated.

[0034] The present disclosure describes a wireless communication network or a wireless communication system, and operations performed in the wireless communication network may be performed in a process of controlling the network and transmitting or receiving a signal from a device (e.g., a base station) that manages the wireless communication network, or in a process of transmitting or receiving a signal to or between terminals connected to the wireless network.

[0035] In the present disclosure, transmitting or receiving a channel means transmitting or receiving information or a signal through the channel. For example, transmitting a control channel means transmitting control information or a signal through the control channel. Similarly, transmitting a data channel means transmitting data information or a signal through the data channel.

[0036] Hereinafter, downlink (DL) refers to communication from a base station to a terminal, and uplink (UL) refers to communication from a terminal to a base station. In downlink, a transmitter may be part of a base station, and a receiver may be part of a terminal. In uplink, a transmitter may be part of a terminal, and a receiver may be part of a base station. A base station may be expressed as a first communication device, and a terminal may be expressed as a second communication device. A base station (BS) may be replaced by terms such as a fixed station, Node B, eNB (evolved-NodeB), gNB (Next Generation NodeB), BTS (base transceiver system), access point (AP: Access Point), network (5G network), AI (Artificial Intelligence) system / module, RSU (road side unit), robot, drone (UAV: Unmanned Aerial Vehicle), AR (Augmented Reality) device, VR (Virtual Reality) device, etc.In addition, the terminal may be fixed or mobile, and may be replaced with terms such as UE (User Equipment), MS (Mobile Station), UT (user terminal), MSS (Mobile Subscriber Station), SS (Subscriber Station), AMS (Advanced Mobile Station), WT (Wireless terminal), MTC (Machine-Type Communication) device, M2M (Machine-to-Machine) device, D2D (Device-to-Device) device, vehicle, RSU (road side unit), robot, AI (Artificial Intelligence) module, UAV (Unmanned Aerial Vehicle), AR (Augmented Reality) device, VR (Virtual Reality) device, etc.

[0037] The following technologies can be used in various wireless access systems, such as CDMA, FDMA, TDMA, OFDMA, and SC-FDMA. CDMA can be implemented using wireless technologies such as UTRA (Universal Terrestrial Radio Access) or CDMA2000. TDMA can be implemented using wireless technologies such as GSM (Global System for Mobile communications) / GPRS (General Packet Radio Service) / EDGE (Enhanced Data Rates for GSM Evolution). OFDMA can be implemented using wireless technologies such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, and E-UTRA (Evolved UTRA). UTRA is part of UMTS (Universal Mobile Telecommunications System). 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) is a part of E-UMTS (Evolved UMTS) that uses E-UTRA, and LTE-A (Advanced) / LTE-A pro is an evolved version of 3GPP LTE. 3GPP NR (New Radio or New Radio Access Technology) is an evolved version of 3GPP LTE / LTE-A / LTE-A pro.

[0038] For clarity, the description is based on a 3GPP communication system (e.g., LTE-A, NR), but the technical idea of ​​the present disclosure is not limited thereto. LTE refers to technology after 3GPP TS (Technical Specification) 36.xxx Release 8. Specifically, LTE technology after 3GPP TS 36.xxx Release 10 is referred to as LTE-A, and LTE technology after 3GPP TS 36.xxx Release 13 is referred to as LTE-A pro. 3GPP NR refers to technology after TS 38.xxx Release 15. LTE / NR may be referred to as a 3GPP system. "xxx" refers to a standard document detail number. LTE / NR may be collectively referred to as a 3GPP system. For background technology, terms, abbreviations, etc. used in the description of the present disclosure, reference may be made to matters described in standard documents published prior to the present disclosure. For example, reference may be made to the following documents.

[0039] For 3GPP LTE, see TS 36.211 (Physical channels and modulation), TS 36.212 (Multiplexing and channel coding), TS 36.213 (Physical layer procedures), TS 36.300 (General description), and TS 36.331 (Radio resource control).

[0040] For 3GPP NR, see TS 38.211 (Physical channels and modulation), TS 38.212 (Multiplexing and channel coding), TS 38.213 (Physical layer procedures for control), TS 38.214 (Physical layer procedures for data), TS 38.300 (Overall description of NR and New Generation-Radio Access Network (NG-RAN)), and TS 38.331 (Radio Resource Control Protocol Specification).

[0041] Abbreviations for terms that may be used in this disclosure are defined as follows.

[0042] - BM: beam management

[0043] - CQI: Channel Quality Indicator

[0044] - CRI: Channel state information - reference signal resource indicator

[0045] - CSI: Channel State Information

[0046] - CSI-IM: Channel State Information - Interference Measurement

[0047] - CSI-RS: Channel state information - reference signal

[0048] - DMRS: Demodulation Reference Signal

[0049] - FDM: frequency division multiplexing

[0050] - FFT: fast Fourier transform

[0051] - IFDMA: interleaved frequency division multiple access

[0052] - IFFT: inverse fast Fourier transform

[0053] - L1-RSRP: Layer 1 reference signal received power

[0054] - L1-RSRQ: Layer 1 reference signal received quality

[0055] - MAC: Medium Access Control

[0056] - NZP: non-zero power

[0057] - OFDM: orthogonal frequency division multiplexing

[0058] - PDCCH: Physical downlink control channel

[0059] - PDSCH: Physical downlink shared channel

[0060] - PMI: precoding matrix indicator

[0061] - RE: resource element

[0062] - RI: Rank indicator

[0063] - RRC: Radio Resource Control

[0064] - RSSI: Received signal strength indicator

[0065] - Rx: Reception

[0066] - QCL: quasi co-location

[0067] - SINR: signal to interference and noise ratio

[0068] - SSB (or SS / PBCH block): Synchronization signal block (including primary synchronization signal (PSS), secondary synchronization signal (SSS), and physical broadcast channel (PBCH))

[0069] - TDM: Time Division Multiplexing

[0070] - TRP: transmission and reception point

[0071] - TRS: Tracking Reference Signal

[0072] - Tx: transmission

[0073] - UE: user equipment

[0074] - ZP: Zero Power

[0075] System General

[0076] As more and more communication devices demand greater communication capacity, the need for improved mobile broadband communications compared to existing radio access technologies (RATs) is emerging. Furthermore, massive machine type communications (MTC), which connects numerous devices and objects to provide diverse services anytime, anywhere, is also a key issue to be considered in next-generation communications. Furthermore, communication system design that considers reliability and latency-sensitive services / terminals is being discussed. Accordingly, the introduction of next-generation RATs that consider enhanced mobile broadband communication (eMBB), massive MTC (MMTC), and ultra-reliable and low latency communication (URLLC) is being discussed. For convenience, these technologies are referred to as NR in this disclosure. NR is an expression representing an example of 5G RAT.

[0077] A new RAT system, including NR, uses OFDM or a similar transmission scheme. The new RAT system may follow OFDM parameters different from those of LTE. Alternatively, the new RAT system may follow the existing LTE / LTE-A numerology but support a larger system bandwidth (e.g., 100 MHz). Alternatively, a single cell may support multiple numerologies. That is, terminals operating under different numerologies can coexist within a single cell.

[0078] A numerology corresponds to a single subcarrier spacing in the frequency domain. Different numerologies can be defined by scaling the reference subcarrier spacing by an integer N.

[0079] Figure 1 illustrates the structure of a wireless communication system to which the present disclosure can be applied.

[0080] Referring to Fig. 1, the NG-RAN consists of gNBs that provide NG-RA (NG-Radio Access) user plane (i.e., new AS (access stratum) sublayer / PDCP (packet data convergence protocol) / RLC (radio link control) / MAC / PHY) and control plane (RRC) protocol termination for UE. The gNBs are interconnected via Xn interfaces. The gNBs are also connected to the NGC (New Generation Core) via the NG interface. More specifically, the gNBs are connected to the AMF (Access and Mobility Management Function) via the N2 interface and to the UPF (User Plane Function) via the N3 interface.

[0081] FIG. 2 illustrates a frame structure in a wireless communication system to which the present disclosure can be applied.

[0082] NR systems can support multiple numerologies. Numerologies can be defined by subcarrier spacing and cyclic prefix (CP) overhead. Multiple subcarrier spacings can be derived by scaling the base (reference) subcarrier spacing by an integer N (or μ). Furthermore, even if it is assumed that very low subcarrier spacing is not used at very high carrier frequencies, the numerology used can be selected independently of the frequency band. Furthermore, NR systems can support various frame structures corresponding to multiple numerologies.

[0083] Below, we examine OFDM numerologies and frame structures that can be considered in NR systems. The various OFDM numerologies supported in NR systems can be defined as shown in Table 1 below.

[0084] μΔf=2 μ ·15 [kHz]CP015 Normal 130 Normal 260 Normal, Extended 3120 Normal 4240 Normal

[0085] NR supports multiple numerologies (or subcarrier spacing (SCS)) to support various 5G services. For example, when the SCS is 15 kHz, it supports a wide area in traditional cellular bands, when the SCS is 30 kHz / 60 kHz, it supports dense-urban, lower latency, and wider carrier bandwidth, and when the SCS is 60 kHz or higher, it supports a bandwidth larger than 24.25 GHz to overcome phase noise. The NR frequency band is defined by two types of frequency ranges (FR1, FR2). FR1 and FR2 can be configured as shown in Table 2 below. In addition, FR2 can mean millimeter wave (mmW).

[0086] Frequency Range Designation Corresponding Frequency Range Subcarrier Spacing FR1410MHz - 7125MHz 15, 30, 60kHz FR224250MHz - 52600MHz 60, 120, 240kHz

[0087] Regarding the frame structure in the NR system, the sizes of the various fields in the time domain are T c =1 / (Δf max ·N f ) is expressed as a multiple of the time unit. Here, Δf max =480·10 3 Hz, and N f =4096. Downlink and uplink transmissions are T f =1 / (Δf max N f / 100)·T c = It is organized into radio frames with a duration of 10ms. Here, each radio frame is T sf =(Δf max N f / 1000)·T c = It consists of 10 subframes with a duration of 1ms. In this case, there may be one set of frames for uplink and one set of frames for downlink. In addition, transmission in uplink frame number i from a terminal is T earlier than the start of the corresponding downlink frame from the terminal. TA =(N TA +N TA,offset )T c It should start before. For the subcarrier spacing configuration μ, slots are n within a subframe. s μ ∈{0,..., N slot subframe,μ-1} are numbered in increasing order, and n within a radio frame. s,f μ ∈{0,..., N slot frame,μ -1} are numbered in increasing order. One slot is N symb slot It consists of consecutive OFDM symbols, and N symb slot is determined by CP. Slot n in subframe s μ The start of OFDM symbol n in the same subframe s μ N symb slot are aligned temporally with the start of the OFDM signal. Not all terminals can transmit and receive simultaneously, which means that not all OFDM symbols in a downlink slot or uplink slot can be utilized.

[0088] Table 3 shows the number of OFDM symbols per slot in a general CP (N symb slot ), the number of slots per wireless frame (N slot frame,μ ), number of slots per subframe (N slot subframe,μ), and Table 4 shows the number of OFDM symbols per slot in the extended CP, the number of slots per radio frame, and the number of slots per subframe.

[0089] μN symb slot N slot frame,μ N slot subframe,μ01410111420221440431480841416016

[0090] μN symb slot N slot frame,μ N slot subframe,μ212404

[0091] FIG. 2 is an example when μ=2 (SCS is 60 kHz), and referring to Table 3, 1 subframe can include 4 slots. 1 subframe={1,2,4} slots illustrated in FIG. 2 is an example, and the number of slot(s) that can be included in 1 subframe is defined as in Table 3 or Table 4. In addition, a mini-slot can include 2, 4, or 7 symbols, or more or fewer symbols. With respect to physical resources in an NR system, antenna ports, resource grids, resource elements, resource blocks, carrier parts, etc. can be considered. Hereinafter, the physical resources that can be considered in an NR system will be described in detail. First, with respect to antenna ports, antenna ports are defined such that the channel through which a symbol on an antenna port is carried can be inferred from the channel through which another symbol on the same antenna port is carried. Two antenna ports are said to be in a QC / QCL (quasi co-located or quasi co-location) relationship if the large-scale properties of the channel through which a symbol on one antenna port is carried can be inferred from the channel through which a symbol on another antenna port is carried. Here, the large-scale properties include one or more of delay spread, Doppler spread, frequency shift, average received power, and received timing.

[0092] FIG. 3 illustrates a resource grid in a wireless communication system to which the present disclosure can be applied.

[0093] Referring to Figure 3, the resource grid is N in the frequency domain. RB μ N sc RB It consists of subcarriers, and one subframe is 14·2 μ It is described as an example, but not limited to, that it consists of OFDM symbols. In an NR system, the transmitted signal is N RB μ N sc RB One or more resource grids consisting of subcarriers and 2 μ N symb (μ) is described by OFDM symbols. Here, N RB μ ≤N RB max,μ is. The above N RB max,μ represents the maximum transmission bandwidth, which may vary not only between numerologies but also between uplink and downlink. In this case, one resource grid may be configured for each μ and antenna port p. Each element of the resource grid for μ and antenna port p is referred to as a resource element and is uniquely identified by an index pair (k, l').

[0094] Here, k=0,...,N RB μ N sc RB -1 is the index in the frequency domain, and l'=0,...,2 μ N symb (μ) -1 indicates the position of the symbol within the subframe. When referring to a resource element in a slot, an index pair (k,l) is used. Here, l=0,...,N symb μ-1. The resource element (k,l') for μ and antenna port p is a complex value a k,l' (p,μ) . If there is no risk of confusion or if a particular antenna port or numerology is not specified, the indices p and μ can be dropped, resulting in a complex value of a k,l' (p) or a k,l' This can be. Also, a resource block (RB) is N in the frequency domain. sc RB =12 is defined as consecutive subcarriers.

[0095] Point A serves as a common reference point of the resource block grid and is obtained as follows.

[0096] - offsetToPointA for the Primary Cell (PCell) downlink represents the frequency offset between point A and the lowest subcarrier of the lowest resource block overlapping the SS / PBCH block used by the UE for initial cell selection. It is expressed in resource block units assuming 15 kHz subcarrier spacing for FR1 and 60 kHz subcarrier spacing for FR2.

[0097] - absoluteFrequencyPointA represents the frequency-position of point A expressed as ARFCN (absolute radio-frequency channel number).

[0098] Common resource blocks (CRBs) are numbered from 0 upwards in the frequency domain for a subcarrier spacing setting μ. The center of subcarrier 0 of CRB 0 for a subcarrier spacing setting μ coincides with 'point A'. Common resource block number n in the frequency domain CRB μ The relationship between the resource elements (k, l) and the subcarrier spacing setting μ is given by the following mathematical expression 1.

[0099]

[0100] In Equation 1, k is defined relative to point A such that k = 0 corresponds to the subcarrier centered at point A. Physical resource blocks are numbered from 0 to N within the bandwidth part (BWP). BWP,i size,μ -Numbered from -1, where i is the number of BWP. Physical resource block n in BWP i PRB and common resource block n CRB The relationship between them is given by the mathematical formula 2 below.

[0101]

[0102] N BWP,i start,μ is a common resource block where BWP starts relative to common resource block 0.

[0103] FIG. 4 illustrates a physical resource block in a wireless communication system to which the present disclosure can be applied. FIG. 5 illustrates a slot structure in a wireless communication system to which the present disclosure can be applied.

[0104] Referring to FIGS. 4 and 5, a slot includes multiple symbols in the time domain. For example, in the case of a normal CP, one slot includes seven symbols, but in the case of an extended CP, one slot includes six symbols.

[0105] A carrier comprises multiple subcarriers in the frequency domain. An RB (Resource Block) is defined as multiple (e.g., 12) consecutive subcarriers in the frequency domain. A BWP (Bandwidth Part) is defined as multiple consecutive (physical) resource blocks in the frequency domain, and can correspond to a single numerology (e.g., SCS, CP length, etc.). A carrier can comprise up to N (e.g., 5) BWPs. Data communication is performed through activated BWPs, and only one BWP can be activated for a single terminal. Each element in the resource grid is referred to as a Resource Element (RE), to which one complex symbol can be mapped.

[0106] The NR system can support up to 400 MHz per component carrier (CC). If a terminal operating in such a wideband CC always operates with the radio frequency (RF) chip for the entire CC turned on, the terminal battery consumption may increase. Alternatively, when considering multiple use cases operating within a single wideband CC (e.g., eMBB, URLLC, Mmtc, V2X, etc.), different numerologies (e.g., subcarrier spacing, etc.) may be supported for each frequency band within the CC. Alternatively, each terminal may have different maximum bandwidth capabilities. Considering this, the base station can instruct the terminal to operate only in a portion of the bandwidth of the wideband CC, rather than the entire bandwidth. This portion of bandwidth is conveniently defined as the bandwidth part (BWP). A BWP can be composed of consecutive RBs on the frequency axis and can correspond to a single numerology (e.g., subcarrier spacing, CP length, slot / mini-slot interval).

[0107] Meanwhile, a base station can configure multiple BWPs within a single CC configured for a terminal. For example, a BWP occupying a relatively small frequency domain can be configured in a PDCCH monitoring slot, while the PDSCH indicated by the PDCCH can be scheduled on a larger BWP.

[0108] Alternatively, if UEs are concentrated in a specific BWP, some UEs can be assigned to different BWPs for load balancing. Alternatively, considering frequency domain inter-cell interference cancellation between neighboring cells, some spectrum in the middle of the total bandwidth can be excluded and both BWPs can be assigned within the same slot. In other words, the base station can assign at least one DL / UL BWP to UEs associated with a wideband CC.

[0109] The base station can activate at least one DL / UL BWP among the DL / UL BWP(s) configured at a specific point in time (by L1 signaling or MAC CE (Control Element) or RRC signaling, etc.). In addition, the base station can instruct switching to another configured DL / UL BWP (by L1 signaling or MAC CE or RRC signaling, etc.). Alternatively, switching to a designated DL / UL BWP may be performed when a timer value expires based on a timer. In this case, the activated DL / UL BWP is defined as an active DL / UL BWP. However, since the UE may not receive the configuration for the DL / UL BWP when performing the initial access process or before the RRC connection is set up, the DL / UL BWP assumed by the UE in such a situation is defined as the initially active DL / UL BWP.

[0110] FIG. 6 illustrates physical channels used in a wireless communication system to which the present disclosure can be applied and a general signal transmission and reception method using the same.

[0111] In wireless communication systems, terminals receive information from a base station via the downlink and transmit it to the base station via the uplink. The information transmitted and received between the base station and terminals includes data and various control information, and various physical channels exist depending on the type and purpose of the information being transmitted and received.

[0112] When the terminal is powered on or enters a new cell, it performs an initial cell search operation, such as synchronizing with the base station (S601). To this end, the terminal receives a primary synchronization signal (PSS) and a secondary synchronization signal (PSS) from the base station to synchronize with the base station and obtain information such as a cell identifier (ID). Afterwards, the terminal can receive a physical broadcast channel (PBCH) from the base station to obtain broadcast information within the cell. Meanwhile, the terminal can receive a downlink reference signal (DL RS) during the initial cell search phase to check the downlink channel status.

[0113] A terminal that has completed an initial cell search can obtain more specific system information by receiving a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) according to information carried in the PDCCH (S602).

[0114] Meanwhile, when accessing a base station for the first time or when there are no radio resources for signal transmission, the terminal may perform a random access procedure (RACH) with the base station (steps S603 to S606). To this end, the terminal may transmit a specific sequence as a preamble via the random access channel (RACH) (steps S603 and S605) and receive a response message to the preamble via the PDCCH and the corresponding PDSCH (steps S604 and S606). In the case of a contention-based RACH, a contention resolution procedure may additionally be performed.

[0115] The terminal that has performed the procedure described above can then perform PDCCH / PDSCH reception (S607) and physical uplink shared channel (PUSCH) / physical uplink control channel (PUCCH) transmission (S608) as general uplink / downlink signal transmission procedures. In particular, the terminal receives downlink control information (DCI) through the PDCCH. Here, DCI includes control information such as resource allocation information for the terminal, and its format varies depending on its intended use.

[0116] Meanwhile, the control information that the terminal transmits to the base station via the uplink or that the terminal receives from the base station includes downlink / uplink ACK / NACK (Acknowledgement / Non-Acknowledgement) signals, CQI (Channel Quality Indicator), PMI (Precoding Matrix Indicator), RI (Rank Indicator), etc. In the case of the 3GPP LTE system, the terminal can transmit the above-described control information such as CQI / PMI / RI via PUSCH and / or PUCCH.

[0117] Table 5 shows an example of the DCI format in the NR system.

[0118] DCI Format Utilization 0_0 Scheduling of PUSCH within a cell 0_1 Scheduling of one or multiple PUSCH within a cell, or indicating cell group (CG: cell group) downlink feedback information to the UE 0_2 Scheduling of PUSCH within a cell 1_0 Scheduling of PDSCH within a DL cell 1_1 Scheduling of PDSCH within a cell 1_2 Scheduling of PDSCH within a cell

[0119] Referring to Table 5, DCI formats 0_0, 0_1, and 0_2 may include resource information related to scheduling of PUSCH (e.g., UL / SUL (Supplementary UL), frequency resource allocation, time resource allocation, frequency hopping, etc.), transport block (TB) related information (e.g., MCS (Modulation Coding and Scheme), NDI (New Data Indicator), RV (Redundancy Version), etc.), HARQ (Hybrid - Automatic Repeat and request) related information (e.g., process number, DAI (Downlink Assignment Index), PDSCH-HARQ feedback timing, etc.), multi-antenna related information (e.g., DMRS sequence initialization information, antenna port, CSI request, etc.), power control information (e.g., PUSCH power control, etc.), and control information included in each DCI format may be predefined.

[0120] DCI format 0_0 is used for scheduling PUSCH in a cell. The information contained in DCI format 0_0 is transmitted with CRC (cyclic redundancy check) scrambled by C-RNTI (cell radio network temporary identifier, Cell RNTI), CS-RNTI (Configured Scheduling RNTI), or MCS-C-RNTI (Modulation Coding Scheme Cell RNTI).

[0121] DCI format 0_1 ​​is used to indicate scheduling of one or more PUSCHs in a cell, or configure grant (CG) downlink feedback information to the UE. The information contained in DCI format 0_1 ​​is CRC-scrambled and transmitted using the C-RNTI, CS-RNTI, SP-CSI-RNTI (Semi-Persistent CSI RNTI), or MCS-C-RNTI.

[0122] DCI format 0_2 is used for scheduling PUSCH in a cell. The information contained in DCI format 0_2 is CRC-scrambled and transmitted using C-RNTI, CS-RNTI, SP-CSI-RNTI, or MCS-C-RNTI.

[0123] Next, DCI formats 1_0, 1_1, and 1_2 may include resource information related to scheduling of PDSCH (e.g., frequency resource allocation, time resource allocation, virtual resource block (VRB)-physical resource block (PRB) mapping, etc.), transport block (TB) related information (e.g., MCS, NDI, RV, etc.), HARQ related information (e.g., process number, DAI, PDSCH-HARQ feedback timing, etc.), multi-antenna related information (e.g., antenna port, transmission configuration indicator (TCI), sounding reference signal (SRS) request, etc.), PUCCH related information (e.g., PUCCH power control, PUCCH resource indicator, etc.), and control information included in each DCI format may be predefined.

[0124] DCI format 1_0 is used for scheduling PDSCH in a DL cell. The information contained in DCI format 1_0 is CRC-scrambled and transmitted using C-RNTI, CS-RNTI, or MCS-C-RNTI.

[0125] DCI format 1_1 is used for scheduling PDSCH in a single cell. The information contained in DCI format 1_1 is CRC-scrambled and transmitted using C-RNTI, CS-RNTI, or MCS-C-RNTI.

[0126] DCI format 1_2 is used for scheduling PDSCH in a single cell. The information contained in DCI format 1_2 is CRC-scrambled and transmitted using C-RNTI, CS-RNTI, or MCS-C-RNTI.

[0127] V2X (vehicle-to-everything) / sidelink (SL) communication

[0128] FIG. 7 illustrates a procedure for performing V2X or SL communication according to a transmission mode in a wireless communication system to which the present disclosure can be applied.

[0129] The embodiment of FIG. 7 can be combined with various embodiments of the present disclosure. In various embodiments of the present disclosure, the transmission mode may be referred to as a mode or resource allocation mode. Hereinafter, for convenience of explanation, the transmission mode in LTE may be referred to as the LTE transmission mode, and the transmission mode in NR may be referred to as the NR resource allocation mode.

[0130] For example, Fig. 7(a) illustrates the operation of a UE related to LTE transmission mode 1 or LTE transmission mode 3. Or, for example, Fig. 7(a) illustrates the operation of a UE related to NR resource allocation mode 1. For example, LTE transmission mode 1 can be applied to general SL communication, and LTE transmission mode 3 can be applied to V2X communication.

[0131] For example, FIG. 7(b) illustrates the operation of a UE associated with LTE transmission mode 2 or LTE transmission mode 4. Or, for example, FIG. 7(b) illustrates the operation of a UE associated with NR resource allocation mode 2.

[0132] Referring to Fig. 7(a), in LTE transmission mode 1, LTE transmission mode 3, or NR resource allocation mode 1, the base station can schedule SL resources to be used by the UE for SL transmission (S8000). For example, the base station can transmit information related to SL resources and / or information related to UL resources to the first UE. For example, the UL resources can include PUCCH resources and / or PUSCH resources. For example, the UL resources can be resources for reporting SL HARQ feedback to the base station.

[0133] For example, a first UE may receive information related to a dynamic grant (DG) resource and / or information related to a configured grant (CG) resource from a base station. For example, a CG resource may include a CG type 1 resource or a CG type 2 resource. In the present disclosure, a DG resource may be a resource that a base station configures / allocates to the first UE via DCI. In the present disclosure, a CG resource may be a (periodic) resource that a base station configures / allocates to the first UE via DCI and / or an RRC message. For example, in the case of a CG type 1 resource, the base station may transmit an RRC message including information related to the CG resource to the first UE. For example, in the case of a CG type 2 resource, the base station may transmit an RRC message including information related to the CG resource to the first UE, and the base station may transmit a DCI related to activation or release of the CG resource to the first UE.

[0134] The first UE may transmit PSCCH (e.g., sidelink control information (SCI) or 1st-stage SCI) to the second UE based on the resource scheduling (S8010).

[0135] The first UE can transmit a PSSCH (e.g., a second-stage SCI, a MAC protocol data unit (PDU), data, etc.) related to the PSCCH to the second UE (S8020).

[0136] A first UE may receive a PSFCH related to a PSCCH / PSSCH from a second UE (S8030). For example, HARQ feedback information (e.g., NACK information or ACK information) may be received from the second UE via the PSFCH.

[0137] The first UE can transmit / report HARQ feedback information to the base station via PUCCH or PUSCH (S8040). For example, the HARQ feedback information reported to the base station may be information generated by the first UE based on HARQ feedback information received from the second UE. For example, the HARQ feedback information reported to the base station may be information generated by the first UE based on a rule set in advance. For example, the DCI may be DCI for scheduling SL. For example, the format of the DCI may be DCI format 3_0 or DCI format 3_1.

[0138] Referring to FIG. 7(b), in LTE transmission mode 2, LTE transmission mode 4, or NR resource allocation mode 2, the UE can determine SL transmission resources within SL resources configured by the base station / network or preset SL resources. For example, the configured SL resources or preset SL resources may be a resource pool. For example, the UE can autonomously select or schedule resources for SL transmission. For example, the UE can perform SL communication by selecting resources within the configured resource pool. For example, the UE can perform sensing and resource (re)selection procedures to select resources within a selection window. For example, the sensing may be performed on a sub-channel basis.

[0139] A first UE that has selected a resource within a resource pool can transmit a PSCCH (e.g., SCI or 1st-stage SCI) to a second UE using the resource (S8010).

[0140] The first UE can transmit a PSSCH (e.g., 2nd-stage SCI, MAC PDU, data, etc.) related to the PSCCH to the second terminal (S8020).

[0141] The first UE can receive a PSFCH related to the PSCCH / PSSCH from the second UE (S8030).

[0142] Referring to FIG. 7(a) or FIG. 7(b), for example, a first UE may transmit an SCI to a second UE on a PSCCH. Or, for example, the first UE may transmit two consecutive SCIs (e.g., 2-stage SCIs) to the second UE on the PSCCH and / or the PSSCH. In this case, the second UE may decode the two consecutive SCIs (e.g., 2-stage SCIs) to receive the PSSCH from the first UE. In the present disclosure, the SCI transmitted on the PSCCH may be referred to as a first (1st) SCI, a first SCI, a first-stage SCI, or a 1st-stage SCI format, and the SCI transmitted on the PSSCH may be referred to as a second (2nd) SCI. nd ) may be referred to as SCI, 2nd SCI, 2nd-stage SCI, or 2nd-stage SCI format. For example, a 1st-stage SCI format may include SCI format 1-A, and a 2nd-stage SCI format may include SCI format 2-A and / or SCI format 2-B.

[0143] Referring to FIG. 7(a) or FIG. 7(b), in step S8030, the first UE may receive a PSFCH based on the description described below. For example, the first UE and the second UE may determine a PSFCH resource based on the description described below, and the second UE may transmit HARQ feedback to the first UE using the PSFCH resource.

[0144] SL relay procedure

[0145] The SL Relay procedure was introduced to support 5G ProSe U2N relay functionality to provide network connectivity for U2N (UE-to-network) remote terminals. This means that both L2 and L3 U2N relay architectures can be supported.

[0146] A U2N relay terminal may be in the RRC_CONNECTED state to relay unicast data. The following RRC state combinations may be supported for L2 U2N relay operation.

[0147] - Both the U2N relay terminal and the U2N remote terminal must be in the RRC_CONNECTED state to transmit / receive relayed unicast data.

[0148] - If all U2N remote terminals connected to the U2N relay terminal are in RRC_INACTIVE or RRC_IDLE state, the U2N relay terminal may be in RRC_IDLE, RRC_INACTIVE or RRC_CONNECTED state.

[0149] For L2 U2N relay procedures, the U2N remote terminal may be configured to use only resource allocation mode 2 for data to be relayed.

[0150] A single unicast link can be established between a L2 U2N relay terminal and a L2 U2N remote terminal. Traffic from a U2N remote terminal and traffic from a U2N relay terminal through a specific U2N relay terminal must be separated into different Uu RLC channels via Uu.

[0151] When the U2N relay function is enabled for a relay terminal and a remote terminal, the relay terminal can provide network connectivity to the U2N remote terminal(s). In this case, the remote terminal may not have a direct connection to the network, but maintain an indirect connection based on the U2N relay function.

[0152] The protocol stacks for the user plane and the control plane of the L2 U2N relay architecture can be configured as shown in FIGS. 8 and 9, respectively. The sidelink relay adaptation protocol (SRAP) sublayer can be placed above the RLC sublayer for both the control plane (CP) and the user plane (UP) on both the PC5 interface and the Uu interface. Between the L2 U2N remote terminal and the base station, the Uu service data adaptation protocol (SDAP), packet data convergence protocol (PDCP), and RRC can be terminated, and 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), the SRAP, RLC, MAC, and PHY can be terminated.

[0153] For L2 U2N relay, the SRAP sublayer via PC5 hop can only be used for bearer mapping purposes. The SRAP sublayer for relaying messages of L2 U2N remote terminals via BCCH and PCCH may not exist in the PC5 hop. For L2 U2N remote terminal messages on signaling radio bearer (SRB) 0, the SRAP sublayer does not exist in the PC5 hop, but the SRAP sublayer may exist in both DL and UL via Uu hop. Here, SRB0 may be used for transmitting RRC messages associated with the common control channel (CCCH) logical channel.

[0154] As an example of the present disclosure, for uplink in an L2 U2N relay procedure, the Uu SRAP sublayer can support UL bearer mapping between a receiving PC5 relay RLC channel and a transmitting Uu relay RLC channel for relaying via an L2 U2N relay terminal Uu interface. For uplink relay traffic, different end-to-end RBs (e.g., SRBs or DRBs (data radio bearers)) of the same remote terminal and / or different remote terminals can be multiplexed via the same Uu relay RLC channel. Here, the Uu SRAP sublayer can support L2 U2N remote terminal identification for UL traffic.

[0155] The identification information of the L2 U2N remote terminal Uu radio bearer and the local remote terminal ID can be included in the Uu SRAP header of the UL to enable the base station to correlate the received packets to the specific PDCP entity associated with the correct Uu radio bearer of the remote terminal. The PC5 SRAP sublayer of the L2 U2N remote terminal can support UL bearer mapping between the remote terminal Uu radio bearer and the egress PC5 relay RLC channel.

[0156] As an example of the present disclosure, in the downlink in the L2 U2N relay procedure, the Uu SRAP lower layer can support DL bearer mapping at the base station to map the SRB, DRB (i.e., end-to-end radio bearer) of the remote terminal to the Uu relay RLC channel via the relay terminal Uu interface.

[0157] The Uu SRAP sublayer may support DL bearer mapping and data multiplexing between multiple end-to-end radio bearers (i.e., SRBs or DRBs) of L2 U2N remote terminals and / or other L2 U2N remote terminals and one Uu relay RLC channel over the relay terminal Uu interface.

[0158] The Uu SRAP sublayer may support remote UE identification for DL ​​traffic. In order to map packets received from the relay terminal and the remote terminal Uu radio bearer to the relevant PC5 relay RLC channel, the identification information of the remote terminal Uu radio bearer and the local remote terminal ID may be included in the Uu SRAP header by the base station in the DL. The PC5 SRAP sublayer of the relay terminal may support DL bearer mapping between the ingress Uu relay RLC channel and the egress PC5 relay RLC channel.

[0159] The PC5 SRAP sublayer of the remote terminal can correlate the received packet to a specific PDCP entity associated with the correct Uu radio bearer of the remote terminal based on the identification information contained in the Uu SRAP header.

[0160] The local remote terminal ID can be included in both the PC5 SRAP header and the Uu SRAP header. The L2 U2N relay terminal can be configured by the base station with the local remote terminal ID to be used in the SRAP header. The remote terminal can obtain the local remote ID from the base station through Uu RRC messages including RRCSetup, RRCReconfiguration, RRCResume, and RRCRefoundment. The Uu DRB(s) and Uu SRB(s) can be mapped to different PC5 relay RLC channels and Uu relay RLC channels in both the PC5 hop and the Uu hop.

[0161] It is the responsibility of the base station to prevent collisions when using local remote terminal IDs. The base station can update the local remote terminal ID by sending the updated local remote ID to the relay terminal via an RRCReconfiguration message. The serving base station can perform the local remote terminal ID update independently of the PC5 unicast link L2 ID update procedure.

[0162] For multi-path based communication, an action to control whether to maintain the existing indirect path when additional changes are made to the direct / indirect path.

[0163] In a conventional wireless communication system, when a U2N relay function is configured for a relay terminal and a remote terminal, the relay terminal can provide network connectivity to the U2N remote terminal(s). In this case, the remote terminal may not have a direct connection to the network while maintaining an indirect connection based on the U2N relay function.

[0164] In this regard, it may be advantageous for a remote terminal to support multipath (MP) operation by maintaining a direct connection only to the Uu interface, as well as indirect connections based on both the PC5 interface and the Uu interface. A remote terminal configured for multipath operation can select one or both connections for data transmission toward the network for more reliable transmission and / or higher throughput.

[0165] According to existing technology, when adding or modifying a direct / indirect path, remote and relay terminals can reconfigure PC5 unicast links in the indirect path. In this case, remote and relay terminals can disconnect existing PC5 unicast links before adding new ones, which can lead to service interruptions in the indirect path.

[0166] To solve such a problem, the present disclosure proposes a method for controlling whether an indirect path is maintained when adding / changing a direct / indirect path and a method for setting up a radio bearer related thereto through specific examples.

[0167] FIG. 10 is a diagram for explaining a process in which a base station performs communication according to one embodiment of the present disclosure.

[0168] The base station can establish a direct path and an indirect path for multi-path operation (S1010).

[0169] For example, a base station can establish direct and indirect paths to a remote terminal, and the indirect paths can be configured / provided by utilizing relay terminals.

[0170] Thereafter, when at least one of the aforementioned direct paths or indirect paths is added or changed, information indicating whether to maintain a terminal-to-terminal connection on the indirect path can be transmitted to a terminal related to multi-path operation (S1020).

[0171] In this regard, the terminal may correspond to at least one of a remote terminal of a direct path and an indirect path, or a relay terminal providing an indirect path. For example, the remote terminal and the relay terminal may be configured based on a terminal-to-network (UE-to-network, U2N) relay function.

[0172] Information indicating whether to maintain the terminal-to-terminal connection on the aforementioned indirect path can be transmitted via an RRC reset message by the base station.

[0173] Additionally, the end-to-end connection on the indirect path may correspond to a PC5 interface-based unicast link (e.g., a PC5 unicast link) between the remote terminal and the relay terminal.

[0174] In connection with the instructions given by the information, the following actions may be performed:

[0175] For example, if the information indicates that a terminal-to-terminal connection on an indirect path is to be released, the terminal-to-terminal connection is released, and a new terminal-to-terminal connection on the indirect path can be established between the remote terminal and the relay terminal. In this case, when the terminal-to-terminal connection is released, the radio bearer for data and signaling of the terminal is released, and after the new terminal-to-terminal connection described above is established, a new radio bearer for data and signaling can be established.

[0176] For another example, if the maintenance of a terminal-to-terminal connection on an indirect path is indicated by the information, sidelink radio bearers for data and signaling may be released and established, excluding sidelink radio bearers for PC5-S (PC5-sidelink) signaling of the terminal. In this case, at least one of the SL PDCP entity or the SL RLC entity of the sidelink radio bearer for PC5-S signaling of the terminal may be maintained, and at least one of the SL PDCP entity or the SL RLC entity of the sidelink radio bearer for data and signaling may be released and newly added.

[0177] For another example, if the maintenance of a terminal-to-terminal connection on an indirect path is indicated by the information, sidelink radio bearers for data and signaling may be released and established, excluding sidelink radio bearers for PC5-S signaling and PC5-RRC messages of the terminal. In this case, at least one of the SL PDCP entity or the SL RLC entity of the sidelink radio bearer for PC5-S signaling and PC5-RRC messages of the terminal may be maintained, and at least one of the SL PDCP entity or the SL RLC entity of the sidelink radio bearer for data and signaling may be released and newly added.

[0178] The method described in the example of FIG. 10 can be performed by the first device (100) of FIG. 15. That is, the base station of FIG. 15 can be implemented by the first device (100). For example, one or more processors (102) of the first device (100) of FIG. 15 can be configured to establish a direct path and an indirect path for a multi-path operation, and to transmit information indicating to a terminal related to the multi-path operation whether to maintain a terminal-to-terminal connection on the indirect path. Furthermore, one or more memories (104) of the first device (100) can store commands for performing the method described in the example of FIG. 10 or the examples described below when executed by one or more processors (102).

[0179] FIG. 11 is a flowchart illustrating a process in which a terminal performs communication according to one embodiment of the present disclosure.

[0180] For multi-path operation, direct and indirect paths can be established / established between remote terminals and base stations. In this case, the indirect path can be serviced / provided through a relay terminal.

[0181] If at least one of a direct path and an indirect path for multi-path operation is added or changed, the terminal can receive information from the base station indicating whether to maintain a terminal-to-terminal connection on the indirect path (S1110).

[0182] For example, the information may be conveyed via a radio resource control (RRC) reset message by the base station.

[0183] In this regard, the terminal may correspond to at least one of a remote terminal of a direct path and an indirect path, or a relay terminal providing an indirect path. For example, the remote terminal and the relay terminal may be configured based on a terminal-to-network (UE-to-network, U2N) relay function.

[0184] A terminal that has received the information can perform either a first operation of maintaining a terminal-to-terminal connection on an indirect path or a second operation of releasing the terminal-to-terminal connection and establishing a new terminal-to-terminal connection based on an instruction from the information.

[0185] That is, the terminal may maintain an existing connection between the remote terminal and the relay terminal, or may disconnect the existing connection and establish a new connection. Here, the new connection may include a connection to a new relay terminal or a new connection to an existing relay terminal.

[0186] In this regard, the terminal-to-terminal connection may correspond to a PC5 interface-based unicast link between a remote terminal and a relay terminal.

[0187] The description of information on whether to maintain an indirect path, a direct path, a terminal-to-terminal connection on an indirect path in FIG. 11, and link / bearer-related operations based on the information are the same as the example in FIG. 10, so redundant specific descriptions are omitted in FIG. 11.

[0188] The method described in the example of FIG. 11 can be performed by the second device (200) of FIG. 15. That is, the terminal of FIG. 15 can be implemented as the second device (200). For example, one or more processors (202) of the second device (200) of FIG. 15 can be configured to receive information indicating whether to maintain a terminal-to-terminal connection on an indirect path, and perform either a first operation of maintaining an existing terminal-to-terminal connection or a second operation of releasing the existing terminal-to-terminal connection and establishing a new terminal-to-terminal connection. Furthermore, one or more memories (204) of the second device (200) can store commands for performing the method described in the example of FIG. 11 or the examples described below when executed by one or more processors (202).

[0189] Hereinafter, operations related to direct paths and indirect paths for multi-path operations described with reference to FIGS. 10 and 11 will be described in detail. The terminals (e.g., remote terminals, relay terminals) and base stations of FIGS. 10 and 11 can perform operations according to the embodiments described below and combinations of the embodiments described above.

[0190] Specifically, when a specific bearer is added, released, or reconfigured by receiving an RRC reconfiguration message for addition / change of a direct path and / or indirect path from a base station (e.g., gNB), the remote terminal and relay terminal on the PC5 unicast link may perform the following operations for the PC5 unicast link. Here, the PC5 unicast link corresponds to the connection / link between the remote terminal and the relay terminal for the aforementioned indirect path.

[0191] First, the remote terminal and the relay terminal can maintain the current (i.e., existing) PC5 unicast link, but release all SL radio bearers for data and signaling (e.g., PC5-RRC messages, etc.) except all / specific SL (sidelink) radio bearer(s) for PC5-S signaling. Thereafter, the remote terminal and the relay terminal can establish all SL radio bearers for data and signaling (e.g., PC5-RRC messages, etc.) except all / specific SL radio bearer(s) for PC5-S signaling.

[0192] In this case, the corresponding SL packet data convergence protocol (PDCP) entity(ies) and / or the corresponding SL radio link control (RLC) entity(ies) of all / specific SL radio bearer(s) for PC5-S signaling may be maintained. On the other hand, the corresponding SL PDCP entity(ies) and / or the corresponding SL RLC entity(ies) of other (or remaining) SL radio bearer(s) may be released and newly added.

[0193] The operation of the aforementioned terminal can be set / instructed by the base station through an RRC reconfiguration message, etc.

[0194] Alternatively, the remote terminal and the relay terminal may maintain the current (i.e., existing) PC5 unicast link, but release at least all sidelink (SL) radio bearers for data, except all / specific SL radio bearers for PC5-S signaling and PC5-RRC messages. Thereafter, the remote terminal and the relay terminal may establish at least SL radio bearers for data, except all / specific SL radio bearers for PC5-S signaling and PC5-RRC messages.

[0195] In this case, the corresponding SL PDCP entity(ies) and / or the corresponding SL RLC entity(ies) of all / specific SL radio bearer(s) for PC5-S signaling and PC5-RRC messages may be maintained. On the other hand, the corresponding SL PDCP entity(ies) and / or the corresponding SL RLC entity(ies) of other (or remaining) SL radio bearer(s) may be released and newly added.

[0196] The operation of the aforementioned terminal can be set / instructed by the base station through an RRC reconfiguration message, etc.

[0197] Below, with respect to the operations of the terminal / base station described above, signaling procedures for adding a direct path, changing a direct path, and adding an indirect path are described through specific examples.

[0198] Example 1

[0199] This embodiment relates to a signaling procedure for adding a direct path over an indirect path in relation to multipath (MP) operation.

[0200] For example, the remote terminal in the signaling procedure may be an L2 MP remote terminal using a side link, and the relay terminal may be an L2 MP relay terminal using a side link.

[0201] FIG. 12 illustrates a signaling procedure between a terminal and a base station when adding a direct path according to an embodiment of the present disclosure.

[0202] Referring to FIG. 12, it is assumed that an indirect path through a relay terminal is established between a remote terminal and a base station, and that the remote terminal can transmit and receive UL / DL data through the indirect path.

[0203] (Step S1205) The remote terminal and relay terminal can perform measurements according to the measurement settings. The remote terminal can report the measurement results.

[0204] (Step S1210) The base station may decide to add a direct path to a remote terminal. The cell serving the direct path and the cell serving the relay terminal on the indirect path belong to the same base station, but may be the same or different.

[0205] (Step S1215) If necessary, the base station may transmit an RRC reset message to the relay terminal to update the indirect path settings.

[0206] For example, the base station may transmit the RRC reset message to the relay terminal before or after the RRC reset message transmission and reception step between the remote terminal and the base station (e.g., step S1220 of FIG. 12).

[0207] In this regard, when an indirect bearer or a split bearer is reconfigured as a direct bearer, an RRC reconfiguration message to the relay terminal may release the indirect path of the indirect bearer or the split bearer. In this case, the relay terminal may release the Uu / SL RLC entity of the indirect bearer or the Uu / SL RLC entity on the indirect path of the split bearer. Additionally, in this case, in order to release the Uu / SL PDCP entity, SRAP entity, and / or Uu / SL RLC entity of the indirect bearer at the remote terminal and add the PDCP entity and RLC entity of the direct bearer, the base station may transmit an RRC reconfiguration message to the remote terminal through the relay terminal in step S1220.

[0208] Additionally or alternatively, if the indirect bearer is reconfigured as a split bearer, the RRC reconfiguration message to the relay terminal may release the indirect bearer and add a split bearer. Alternatively, in this case, the RRC reconfiguration message to the relay terminal may reconfigure the indirect bearer as a split bearer by adding a direct path to the split bearer.

[0209] At this time, if the message releases the indirect bearer and adds a split bearer, the relay terminal may release the SRAP entity and / or the Uu / SL RLC entity of the indirect bearer, and add a new SRAP entity and / or a new Uu / SL RLC entity on the indirect path of the split bearer from the relay terminal. In this case, in order to add a PDCP entity and an RLC entity on the direct path of the split bearer from the remote terminal, the base station may transmit an RRC reconfiguration message to the remote terminal through the relay terminal in step S1220.

[0210] Additionally, if the message reconfigures the indirect bearer to a split bearer by adding a direct path of the split bearer, the relay terminal may maintain the SRAP entity and / or the Uu / SL RLC entity of the indirect bearer added / connected to the indirect path of the split bearer. In this case, in order to add a PDCP entity and an RLC entity on the direct path of the split bearer at the remote terminal, the base station may transmit an RRC reconfiguration message to the remote terminal through the relay terminal in step S1220.

[0211] Additionally or alternatively, when a direct bearer, an indirect bearer, or a split bearer is reconfigured to a new indirect bearer, the RRC reconfiguration message to the relay terminal may release the direct bearer, the indirect bearer, the split bearer, or the direct path of the split bearer. In this case, the relay terminal may release the Uu / SL RLC entity of the previous (or current) indirect bearer or the Uu / SL RLC entity on the indirect path of the split bearer, and then add a new Uu / SL RLC entity of the new indirect bearer. Additionally, in this case, in order to release the Uu / SL PDCP entity, the SRAP entity, and / or the Uu / SL RLC entity of the previous (or current) indirect bearer at the remote terminal and add the Uu / SL PDCP entity, the SRAP entity, and / or the Uu / SL RLC entity of the new indirect bearer, the base station may transmit an RRC reconfiguration message to the remote terminal via the relay terminal in step S1220.

[0212] During that phase, if a particular bearer is added, released, or re-established as described above, the relay terminal may release or maintain the bearer and / or PC5 unicast link based on one or more of the following methods:

[0213] (Method 1-1)

[0214] Relay terminals and remote terminals can release the current PC5 link and establish a new PC5 unicast link. In this case, all radio bearers for data / signaling are released when the current PC5 unicast link is released, and can be established / added after the new PC5 unicast link is established.

[0215] (Method 1-2)

[0216] The relay terminal and the remote terminal may maintain the current PC5 unicast link, but release all SL radio bearers for data and signaling (e.g., PC5-RRC messages, etc.), except all / specific SL radio bearer(s) for PC5-S signaling. After that, the relay terminal and the remote terminal may establish SL radio bearers for data and signaling (e.g., PC5-RRC messages, etc.), except all / specific SL radio bearer(s) for PC5-S signaling. In this case, the corresponding SL PDCP entity(s) and / or the corresponding SL RLC entity(s) of the all / specific SL radio bearer(s) for PC5-S signaling may be maintained. On the other hand, the corresponding SL PDCP entity(s) and / or the corresponding SL RLC entity(s) of the other (or remaining) SL radio bearer(s) are released and may be newly added.

[0217] (Method 1-3)

[0218] The relay terminal and the remote terminal may maintain the current PC5 unicast link, but may release at least all SL radio bearers for data, except all / specific SL radio bearer(s) for PC5-S signaling and PC5-RRC messages. After that, the relay terminal and the remote terminal may establish at least SL radio bearers for data, except all / specific SL radio bearer(s) for PC5-S signaling and PC5-RRC messages. In this case, the corresponding SL PDCP entity(ies) and / or the corresponding SL RLC entity(ies) of the all / specific SL radio bearer(s) for PC5-S signaling and PC5-RRC messages may be maintained. On the other hand, the corresponding SL PDCP entity(ies) and / or the corresponding SL RLC entity(ies) of the other (or remaining) SL radio bearer(s) are released and may be newly added.

[0219] In one or more of the above-described methods, the operation of the terminal may be set / instructed through an RRC reconfiguration message, etc.

[0220] (Step S1220) The base station may transmit an RRC reset message to a remote terminal via a relay terminal. The contents of the RRC reset message may include at least a target cell, direct path addition settings, etc.

[0221] (Step S1225) The remote terminal can synchronize to the DL of the target cell serving the direct path and perform a random access procedure toward the cell serving the direct path. The remote terminal can set the target cell as the PCell.

[0222] (Step S1230a) The remote terminal may transmit an RRC reconfiguration complete message to the base station at least through the direct path to complete the direct path addition procedure.

[0223] (Step S1230b) When a split SRB1 with duplication is set, the remote terminal can also transmit an RRC reconfiguration completion message to the base station through an indirect path provided by the relay terminal.

[0224] Thereafter, the remote terminal can perform DL / UL data transmission and reception with the base station via a direct path and / or an indirect path.

[0225] Example 2

[0226] This embodiment relates to a signaling procedure for changing a direct path in relation to multi-path (MP) operation.

[0227] FIG. 13 illustrates a signaling procedure between a terminal and a base station when a direct path is changed according to an embodiment of the present disclosure.

[0228] Referring to FIG. 13, it is assumed that a direct path and / or an indirect path are established between a remote terminal and a base station through a relay terminal, and that the remote terminal can perform UL / DL data transmission and reception through the direct path and / or the indirect path.

[0229] (Step S1305) The remote terminal can perform data transmission and reception by utilizing both a direct path in the PCell and an indirect path provided by the relay terminal.

[0230] (Step S1310) The remote terminal and relay terminal can perform measurements based on the measurement settings. At this time, the remote terminal can report the measurement results.

[0231] (Step S1315) The base station may decide to change the direct path of the remote terminal from the PCell (i.e., the source PCell) to a new cell (i.e., the target PCell). The source / target PCell serving the previous / new direct path and the cell serving the relay terminal via the indirect path belong to the same base station, but may be the same or different.

[0232] (Step S1320) If necessary, the base station may transmit an RRC reset message to the relay terminal to update the indirect path settings.

[0233] For example, the base station may transmit the RRC reset message to the relay terminal before or after the RRC reset message transmission and reception step between the remote terminal and the base station (e.g., step S1325 of FIG. 13). For example, the remote terminal may correspond to an L2 MP remote terminal, and the relay terminal may correspond to an L2 MP relay terminal.

[0234] In this regard, when an indirect bearer or a split bearer is reconfigured as a direct bearer, an RRC reconfiguration message to the relay terminal may release the indirect path of the indirect bearer or the split bearer. In this case, the relay terminal may release the Uu / SL RLC entity of the indirect bearer or the Uu / SL RLC entity on the indirect path of the split bearer. Additionally, in this case, in order to release the Uu / SL PDCP entity, SRAP entity, and / or Uu / SL RLC entity of the indirect bearer at the remote terminal and add the PDCP entity and RLC entity of the direct bearer, the base station may transmit an RRC reconfiguration message to the remote terminal through the relay terminal in step S1325.

[0235] Additionally or alternatively, if the indirect bearer is reconfigured as a split bearer, the RRC reconfiguration message to the relay terminal may release the indirect bearer and add a split bearer. Alternatively, in this case, the RRC reconfiguration message to the relay terminal may reconfigure the indirect bearer as a split bearer by adding a direct path to the split bearer.

[0236] At this time, if the message releases the indirect bearer and adds a split bearer, the relay terminal may release the SRAP entity and / or the Uu / SL RLC entity of the indirect bearer, and add a new SRAP entity and / or a new Uu / SL RLC entity on the indirect path of the split bearer from the relay terminal. In this case, in order to add a PDCP entity and an RLC entity on the direct path of the split bearer from the remote terminal, the base station may transmit an RRC reconfiguration message to the remote terminal through the relay terminal in step S1325.

[0237] Additionally, if the message adds a direct path of the split bearer to reconfigure the indirect bearer into a split bearer, the relay terminal may maintain the SRAP entity and / or the Uu / SL RLC entity of the indirect bearer added / connected to the indirect path of the split bearer. In this case, in order to add a PDCP entity and an RLC entity on the direct path of the split bearer at the remote terminal, the base station may transmit an RRC reconfiguration message to the remote terminal through the relay terminal in step S1325.

[0238] Additionally or alternatively, when a direct bearer, an indirect bearer, or a split bearer is reconfigured to a new indirect bearer, the RRC reconfiguration message to the relay terminal may release the direct bearer, the indirect bearer, the split bearer, or the direct path of the split bearer. In this case, the relay terminal may release the Uu / SL RLC entity of the previous (or current) indirect bearer or the Uu / SL RLC entity on the indirect path of the split bearer, and then add a new Uu / SL RLC entity of the new indirect bearer. Additionally, in this case, in order to release the Uu / SL PDCP entity, the SRAP entity, and / or the Uu / SL RLC entity of the previous (or current) indirect bearer at the remote terminal and add the Uu / SL PDCP entity, the SRAP entity, and / or the Uu / SL RLC entity of the new indirect bearer, the base station may transmit an RRC reconfiguration message to the remote terminal via the relay terminal in step S1325.

[0239] During that phase, if a particular bearer is added, released, or re-established as described above, the relay terminal may release or maintain the bearer and / or PC5 unicast link based on one or more of the following methods:

[0240] (Method 2-1)

[0241] Relay terminals and remote terminals can release the current PC5 link and establish a new PC5 unicast link. In this case, all radio bearers for data / signaling are released when the current PC5 unicast link is released, and can be established / added after the new PC5 unicast link is established.

[0242] (Method 2-2)

[0243] The relay terminal and the remote terminal may maintain the current PC5 unicast link, but release all SL radio bearers for data and signaling (e.g., PC5-RRC messages, etc.), except all / specific SL radio bearer(s) for PC5-S signaling. After that, the relay terminal and the remote terminal may establish SL radio bearers for data and signaling (e.g., PC5-RRC messages, etc.), except all / specific SL radio bearer(s) for PC5-S signaling. In this case, the corresponding SL PDCP entity(s) and / or the corresponding SL RLC entity(s) of the all / specific SL radio bearer(s) for PC5-S signaling may be maintained. On the other hand, the corresponding SL PDCP entity(s) and / or the corresponding SL RLC entity(s) of the other (or remaining) SL radio bearer(s) are released and may be newly added.

[0244] (Method 2-3)

[0245] The relay terminal and the remote terminal may maintain the current PC5 unicast link, but may release at least all SL radio bearers for data, except all / specific SL radio bearer(s) for PC5-S signaling and PC5-RRC messages. After that, the relay terminal and the remote terminal may establish at least SL radio bearers for data, except all / specific SL radio bearer(s) for PC5-S signaling and PC5-RRC messages. In this case, the corresponding SL PDCP entity(ies) and / or the corresponding SL RLC entity(ies) of all / specific SL radio bearer(s) for PC5-S signaling and PC5-RRC messages may be maintained. On the other hand, the corresponding SL PDCP entity(ies) and / or the corresponding SL RLC entity(ies) of the other (or remaining) SL radio bearer(s) are released and may be newly added.

[0246] In one or more of the above-described methods, the operation of the terminal may be set / instructed through an RRC reconfiguration message, etc.

[0247] (Step S1325) The base station may transmit an RRC reset message to the remote terminal on the direct path and / or on the indirect path for changing the direct path.

[0248] (Step S1330) The remote terminal can synchronize to the DL of the target PCell serving the new direct path and perform a random access procedure for the target PCell serving the new direct path.

[0249] (Step S1335a) The remote terminal may transmit an RRC reconfiguration complete message to the base station at least through the direct path to complete the direct path change procedure.

[0250] (Step S1335b) If a split SRB1 including duplication is set, the remote terminal can also transmit an RRC reconfiguration completion message to the base station through an indirect path provided by the target relay terminal.

[0251] Example 3

[0252] This embodiment relates to a signaling procedure for adding an indirect path on a direct path in relation to multi-path (MP) operation.

[0253] For example, the remote terminal in the signaling procedure may be an L2 MP remote terminal using a side link, and the relay terminal may be an L2 MP relay terminal using a side link.

[0254] FIG. 14 illustrates a signaling procedure between a terminal and a base station when adding an indirect path according to an embodiment of the present disclosure.

[0255] Referring to FIG. 14, it is assumed that a direct path is established between a remote terminal and a base station, and that the remote terminal can transmit and receive UL / DL data through the direct path.

[0256] (Step S1405) The remote terminal establishes an RRC connection with the base station and can transmit and receive data through a direct path.

[0257] (Step S1410) When the remote terminal is connected to the relay terminal using a side link, the remote terminal may report at least a list of identification information (e.g., ID) for candidate relay terminals and identification information (e.g., ID) for the cell of the candidate relay terminal. Otherwise, the remote terminal is connected to the relay terminal using a non-3GPP link, and the remote terminal may report at least a C-RNTI (only when the remote terminal is in RRC_connected state) and identification information (e.g., ID) for the cell of the connected relay terminal.

[0258] (Step S1415) The base station may determine to add a direct path for the remote terminal. The cell serving the direct path and the cell serving the relay terminal on the indirect path belong to the same base station, but may be the same or different. If the relay terminal is in the RRC_connected state, the base station may send an RRC reconfiguration message to the relay terminal to establish an indirect path for the remote terminal.

[0259] (Step S1420) The base station can perform RRC reconfiguration for a remote terminal with the relay terminal.

[0260] For example, the base station may transmit the RRC reset message to the relay terminal before or after the RRC reset message transmission and reception step between the remote terminal and the base station (e.g., step S1425 of FIG. 14). If the relay terminal is in the RRC_IDLE state or the RRC_INACTIVE state, the base station may transmit the RRC reset message to the relay terminal after the relay terminal successfully performs RRC connection establishment triggered by the RRC reset complete message in step S1435 or the PC5-RRC message in step S1430.

[0261] In this regard, when an indirect bearer or a split bearer is re-established as a direct bearer, an RRC re-establishment message to the relay terminal may release the indirect path of the indirect bearer or the split bearer. In this case, the relay terminal may release the Uu / SL RLC entity of the indirect bearer or the Uu / SL RLC entity on the indirect path of the split bearer. Additionally, in this case, in order to release the Uu / SL PDCP entity, SRAP entity, and / or Uu / SL RLC entity of the indirect bearer at the remote terminal and add the PDCP entity and RLC entity of the direct bearer, the base station may transmit an RRC re-establishment message to the remote terminal through the relay terminal in step S1425.

[0262] Additionally or alternatively, if the indirect bearer is reconfigured as a split bearer, the RRC reconfiguration message to the relay terminal may release the indirect bearer and add a split bearer. Alternatively, in this case, the RRC reconfiguration message to the relay terminal may reconfigure the indirect bearer as a split bearer by adding a direct path to the split bearer.

[0263] At this time, if the message releases the indirect bearer and adds a split bearer, the relay terminal may release the SRAP entity and / or the Uu / SL RLC entity of the indirect bearer, and add a new SRAP entity and / or a new Uu / SL RLC entity on the indirect path of the split bearer from the relay terminal. In this case, in order to add a PDCP entity and an RLC entity on the direct path of the split bearer from the remote terminal, the base station may transmit an RRC reconfiguration message to the remote terminal through the relay terminal in step S1425.

[0264] Additionally, if the message reconfigures the indirect bearer to a split bearer by adding a direct path of the split bearer, the relay terminal may maintain the SRAP entity and / or the Uu / SL RLC entity of the indirect bearer added / connected to the indirect path of the split bearer. In this case, in order to add a PDCP entity and an RLC entity on the direct path of the split bearer at the remote terminal, the base station may transmit an RRC reconfiguration message to the remote terminal through the relay terminal in step S1425.

[0265] Additionally or alternatively, when a direct bearer, an indirect bearer, or a split bearer is reconfigured to a new indirect bearer, the RRC reconfiguration message to the relay terminal may release the direct bearer, the indirect bearer, the split bearer, or the direct path of the split bearer. In this case, the relay terminal may release the Uu / SL RLC entity of the previous (or current) indirect bearer or the Uu / SL RLC entity on the indirect path of the split bearer, and then add a new Uu / SL RLC entity of the new indirect bearer. Additionally, in this case, in order to release the Uu / SL PDCP entity, the SRAP entity, and / or the Uu / SL RLC entity of the previous (or current) indirect bearer at the remote terminal and add the Uu / SL PDCP entity, the SRAP entity, and / or the Uu / SL RLC entity of the new indirect bearer, the base station may transmit an RRC reconfiguration message to the remote terminal via the relay terminal in step S1425.

[0266] During that phase, if a particular bearer is added, released, or re-established as described above, the relay terminal may release or maintain the bearer and / or PC5 unicast link based on one or more of the following methods:

[0267] (Method 3-1)

[0268] Relay terminals and remote terminals can release the current PC5 link and establish a new PC5 unicast link. In this case, all radio bearers for data / signaling are released when the current PC5 unicast link is released, and can be established / added after the new PC5 unicast link is established.

[0269] (Method 3-2)

[0270] The relay terminal and the remote terminal may maintain the current PC5 unicast link, but release all SL radio bearers for data and signaling (e.g., PC5-RRC messages, etc.), except all / specific SL radio bearer(s) for PC5-S signaling. After that, the relay terminal and the remote terminal may establish SL radio bearers for data and signaling (e.g., PC5-RRC messages, etc.), except all / specific SL radio bearer(s) for PC5-S signaling. In this case, the corresponding SL PDCP entity(s) and / or the corresponding SL RLC entity(s) of the all / specific SL radio bearer(s) for PC5-S signaling may be maintained. On the other hand, the corresponding SL PDCP entity(s) and / or the corresponding SL RLC entity(s) of the other (or remaining) SL radio bearer(s) are released and may be newly added.

[0271] (Method 3-3)

[0272] The relay terminal and the remote terminal may maintain the current PC5 unicast link, but may release at least all SL radio bearers for data, except all / specific SL radio bearer(s) for PC5-S signaling and PC5-RRC messages. After that, the relay terminal and the remote terminal may establish at least SL radio bearers for data, except all / specific SL radio bearer(s) for PC5-S signaling and PC5-RRC messages. In this case, the corresponding SL PDCP entity(ies) and / or the corresponding SL RLC entity(ies) of all / specific SL radio bearer(s) for PC5-S signaling and PC5-RRC messages may be maintained. On the other hand, the corresponding SL PDCP entity(ies) and / or the corresponding SL RLC entity(ies) of the other (or remaining) SL radio bearer(s) are released and may be newly added.

[0273] In one or more of the above-described methods, the operation of the terminal may be set / instructed through an RRC reconfiguration message, etc.

[0274] (Step S1425) The base station may transmit an RRC reset message to the remote terminal. The RRC reset message may include at least identification information for the target relay terminal, additional indirect path configuration, RLC channel configuration, bearer mapping, and associated end-to-end radio bearer(s).

[0275] (Step S1430) If a remote terminal using a side link does not have a PC5 unicast link with the target relay terminal, the remote terminal may establish a PC5 unicast link with the target relay terminal. If the remote terminal uses a non-3GPP link, this procedure may be omitted.

[0276] (Step S1435a) The remote terminal may transmit an RRC reconfiguration complete message to the base station at least through a direct path to complete the indirect path addition procedure.

[0277] (Step S1435b) If a split SRB1 including duplication is set, the remote terminal can also transmit an RRC reconfiguration completion message to the base station through an indirect path provided by the relay terminal.

[0278] In this regard, if the relay terminal selected for indirect path addition is in RRC_idle state or RRC_deactivated state, after receiving the path addition command, the remote terminal needs to switch the relay terminal in RRC_idle state or RRC_deactivated state to RRC_connected state.

[0279] If the non-partitioned SRB1 is set only on the direct path, the remote terminal can transmit the RRC re-establishment complete message only on the direct path.

[0280] A remote terminal using a sidelink can send a PC5-RRC message to the relay terminal. Upon receiving the PC5-RRC message, the relay terminal can initiate RRC connection establishment. Otherwise, if the remote terminal uses a non-3GPP link, the method by which the remote terminal triggers the relay terminal to initiate the RRC connection establishment procedure may depend on the remote terminal's implementation.

[0281] When a split SIB1 including duplication is configured, a relay terminal that receives an RRC reconfiguration complete message from a remote terminal can initiate RRC connection setup to transmit an RRC reconfiguration complete message to the base station.

[0282] Example 4

[0283] The present embodiment relates to various methods applicable on the RRC layer in relation to the multi-path operation described above in the present disclosure.

[0284] (Method 4-1. Message used to report indirect path failure)

[0285] In this regard, the following options may be considered:

[0286] - Indirect path failures are reported via the MCGFailureInformation message.

[0287] - Indirect path failures are reported via the SidelinkUEInformationNR message.

[0288] - Indirect path failures are reported via new messages.

[0289] Sending the MCGFailureInformation message initiates T316. Upon receiving RRCRelease, an RRC reconfiguration with reconfigurationwithSync for the PCell, a MobilityFromNRCommand, or initiating a re-establishment procedure, the UE must abort T316. Upon expiration of T316, the UE must initiate a connection re-establishment procedure.

[0290] It may not be desirable to start a timer upon indirect path failure and initiate a connection reestablishment procedure when the timer expires. In this sense, reporting indirect path failures via the MCGFailureInformation message may not be desirable. Furthermore, reporting indirect path failures via the SidelinkUEInformationNR message may not be desirable.

[0291] Therefore, the present disclosure proposes a method for reporting indirect path failures via a new IndirectPathFailureInformation message or the existing UEAssistanceInformation message. It may be advantageous for a UE to include measurement results of a relay UE (e.g., an L2 U2N Relay UE) and / or a candidate relay UE (e.g., a candidate L2 U2N Relay UE) in the message. For example, such a method may be possible for subsequent indirect path changes or releases.

[0292] (Method 4-2. CFRA for PCell providing direct path for direct path addition / change)

[0293] rach-ConfigDedicated can be included in ReconfigurationWithSync. Therefore, rach-ConfigDedicated can be included in ReconfigurationWithSync for direct path addition / change, as long as no restrictions are specified for CFRA for multipathing. Therefore, CFRA can be supported when direct path addition / change is performed without affecting the operation of the RRC layer.

[0294] That is, CFRA for target PCell for direct path addition / change can be supported without additional impact on the operation of RRC layer through ReconfigurationWithSync in existing rach-ConfigDedicated.

[0295] (Method 4-3. Measurement event of remote terminal for indirect path change)

[0296] To improve U2N service continuity, RAN2 agreed to introduce a new measurement event Z1 based on individual thresholds for i2i path switching procedures.

[0297] - Event Z1: The serving relay terminal (e.g., Serving L2 U2N Relay UE) becomes worse than threshold 1 and the candidate relay terminal (e.g., Candidate L2 U2N Relay UE) becomes better than threshold 2.

[0298] Separate thresholds for SL-RSRP and SD-RSRP can be configured for Threshold 1 of Z1.

[0299] In this regard, the aforementioned new event Z1 can also be applied to indirect path changes without additional impact.

[0300] (Method 4-4. How to handle handover (HO) of relay terminals)

[0301] Since relay terminals providing indirect paths to remote terminals can perform handovers, the indirect paths must be changed or removed from the network. In this regard, the following options are possible:

[0302] - Option 1: The network ensures that the indirect path is released from the remote terminal before the relay terminal is handed over.

[0303] - Option 2: The relay terminal can indicate a Uu handover in a notification message to the remote terminal in a conventional manner (e.g., 3GPP Rel-17 manner), and the remote terminal can stop the indirect path and wait for network reconfiguration.

[0304] In this regard, Option 1 can operate without affecting the specification. Furthermore, while notifications including relay UE handover (relayUE-HO) to remote terminals in Option 2 can exist alongside Option 1, whether or not to interrupt the remote terminal's indirect path needs to be discussed for Option 2.

[0305] The base station may release or change the relay terminal for a remote terminal upon issuing a handover command to the relay terminal or upon receiving a report from the remote terminal regarding an indirect path failure. Prior to the relay terminal's handover, the base station may also reconfigure the indirect path and / or the default path for all split bearers to a direct path based on measurement reports, or activate PDCP replication for all split bearers. Therefore, allowing the remote terminal to suspend the indirect path may be an optimal method to avoid delays.

[0306] That is, the network can determine when the indirect path is released from the remote terminal for the relay terminal's handover. It is up to the network to decide whether to release the indirect path before or after the relay terminal's handover. Without changing the specifications, the relay terminal sends a notification message to the remote terminal along with the relay terminal handover (relayUE-HO) as currently specified. Conversely, the remote terminal does not interrupt the indirect path.

[0307] (Method 4-5. Reporting relay terminal information for adding an indirect path in Scenario 2)

[0308] This relates to the message used to report relay terminal information for indirect path additions (and indirect path changes, if supported in Scenario 2) in Scenario 2, and whether multiple relay terminals can be reported. Candidate messages may include:

[0309] - Relay terminals are reported through the terminal information procedure.

[0310] - Relay terminals are reported via terminal support information.

[0311] - Relay terminals are reported through measurement reports.

[0312] In this regard, the terminal information procedure is based on a bidirectional procedure, where the terminal always expects a response from the network, whereas terminal assistance information is based on a unidirectional procedure, where all responses to terminal assistance information depend on the network. That is, whether or not to add an indirect path based on a report can depend on the network, and thus a unidirectional procedure may suffice.

[0313] Additionally, measurement reports can typically include measurement results from relay terminals, such as those from remote terminals. However, it is unclear what can be reported for non-3GPP-based terminal-to-terminal links. Therefore, it may be desirable to report the relay terminal's C-RNTI through terminal support information.

[0314] That is, the present disclosure proposes a method in which a remote terminal reports the C-RNTI of a relay terminal to a base station through an existing UEAssistanceInformation message.

[0315] (Method 4-6. Whether / how network or remote aliases can trigger the addition of indirect routes)

[0316] Upon receiving the C-RNTI of a relay terminal in a UEAssistanceInformation message, the base station can add or change an indirect path to the reported relay terminal. Additional mechanisms / signals for the base station to add or change an indirect path may not be required.

[0317] These indirect route change cases may share similarities with indirect route failure handling cases. Specifically, when an indirect route fails, the remote terminal can report an indirect route failure message to the base station, including the C-RNTI of the candidate relay terminal. Upon receiving the relay terminal's C-RNTI, the base station can release the previous relay terminal and add the reported relay terminal to the indirect route change.

[0318] That is, the present disclosure proposes a method by which a base station can add (or change, if supported) an indirect path to a reported relay terminal when receiving a C-RNTI of a relay terminal in a UEAssistanceInformation message or an indirect path failure message from a remote terminal.

[0319] (Method 4-7. Whether / how to report idle / inactive relay UEs in Scenario 2)

[0320] For the simplicity of Scenario 2, it may be desirable for the remote terminal to only report to relay terminals that are in at least the RRC_Connected state. That is, the present disclosure proposes a method that does not support reporting and indirect path addition / change by remote terminals to relay terminals that are in the RRC_Idle / Deactivated state in 3GPP Rel-18.

[0321] (Method 4-8. Whether to support indirect path changes)

[0322] Indirect path switching can be achieved by a remote terminal reporting a single target relay terminal to the base station. Upon receiving this report, the base station can release the previous relay terminal and add a new relay terminal through a single RRC reconfiguration procedure, as in Scenario 1, or through two separate RRC reconfiguration procedures.

[0323] (Method 4-9. Whether / how to support authorization for MP Scenario 2)

[0324] Since Scenario 2 involves multipath usage with non-3GPP links, it is unclear whether the multipath (MP) permissions granted for Scenario 1 can be reused. Given that terminals capable of MP in Scenario 2 may not be able to use 3GPP sidelinks, it may be preferable to leave this up to the base station implementation.

[0325] (Method 4-10. RRC Connection Reset Procedure Using MP Scenario 2)

[0326] When an L2 MP remote terminal using sidelink is configured with multipath and initiates an RRC connection re-establishment procedure, the L2 MP remote terminal does not perform the RRC connection re-establishment directly with the multipath configuration for Scenario 1.

[0327] In this regard, the present disclosure proposes to apply the same procedure to scenario 2.

[0328] Example 5

[0329] This embodiment relates to various methods applicable on the MAC layer in relation to the multi-path operation described above in the present disclosure.

[0330] (Method 5-1. Buffer size reporting for UL data via direct and indirect paths)

[0331] The buffer size field of Uu BSR and SL-BSR can identify the total amount of data available according to the data volume calculation procedure on all logical channels of the logical channel group after the MAC PDU is constructed (i.e., after the logical channel priority procedure, the buffer size field value can be 0).

[0332] In this regard, Uu BSR may only be relevant to direct bearers and split bearers.

[0333] For direct bearers on Uu BSR, there may be no problem in defining the total data amount in the Buffer Size field of the BSR MAC CE. The terminal may report the UL buffer size as specified for the current BSR.

[0334] However, for split bearers involving Uu BSR, a clearer explanation of the definition of the total amount of data in the buffer size fields for both Uu BSR and SL-BSR may be required, as the reported buffer sizes may be redundant.

[0335] SL BSR can be configured during SL Mode 1 allocation. If SL BSR is configured, one simple approach to address this issue could be to avoid reporting the SL RLC buffer size for Uu BSR. That is, only PDCP buffer and UL RLC buffer are considered for the total data amount for Uu BSR, and SL data is not currently reported in Uu BSR. However, using this approach, the UE would redundantly report the data amounts of the PDCP buffer for Uu BSR and SL BSR.

[0336] That is, the current Uu BSR does not report SL data. In this regard, in the present disclosure, the Uu BSR is used to report buffer sizes for direct bearers and split bearers, not indirect bearers, and a method is proposed in which only PDCP buffers and UL RLC buffers are considered in the data volume calculation of the Uu BSR for split bearers and direct bearers when the SL BSR is configured in SL mode 1.

[0337] Currently, SL BSR is unnecessary when SL mode 2 allocation is used. Assuming that the proposed method described above is agreed upon, the same approach can be taken for SL modes 1 and 2. In addition, when SL BSR is not configured, the terminal does not report the buffer size for the indirect bearer. Therefore, in the present disclosure, even when SL BSR is not configured (e.g., in SL mode 2), the terminal only considers PDCP buffer and UL RLC buffer in calculating the data volume of Uu BSR for split bearer and direct bearer, and when SL BSR is not configured (i.e., in the case of SL mode 2), the terminal only reports the buffer size for split bearer and direct bearer, and does not report the buffer size for indirect bearer.

[0338] (Method 5-2. SL-BSR reports Uu path traffic buffer)

[0339] SL BSR may only be relevant to indirect bearers and split bearers.

[0340] For indirect bearers on SL BSR, there may be no problem in defining the total amount of data in the Buffer Size field of the BSR MAC CE. The terminal may report the SL Buffer Size as currently specified for the SL BSR.

[0341] However, for split bearers involving SL BSR, a clearer explanation of the total amount of data in the buffer size fields for both Uu BSR and SL-BSR may be required, as the reported buffer sizes may be redundant.

[0342] SL BSR can be configured during SL Mode 1 allocation. If SL BSR is configured, one simple approach to address this issue could be to avoid reporting the UL RLC buffer size for SL BSR. That is, only PDCP buffer and SL RLC buffer are considered for the total data volume for SL BSR, and UL data is not currently reported in SL BSR.

[0343] That is, the current SL BSR may not report UL data. In this regard, in the present disclosure, the SL BSR is used to report the buffer size for indirect bearers and split bearers, not direct bearers, and when the SL BSR is configured in SL mode 1, a method is proposed in which only the PDCP buffer and the SL RLC buffer are considered in the data volume calculation of the SL BSR for the split bearer and indirect bearer.

[0344] (Method 5-3. How to enable / disable duplicates)

[0345] When using the Duplication RLC Activation / Deactivation MAC CE, it is necessary to clearly define how the RLCi field is used to indicate indirect bearers and direct DRBs. This field indicates the PDCP replication activation / deactivation status of RLC entity i for the DRB, where i is the ascending MCG and SCG logical channel IDs of the secondary RLC entity for the DRB.

[0346] Assuming that a MAC CE including a DRB ID field, an RLD_2 field, an RLC_1 field, and an RLC_0 field is applied to replication for multipath, for an RLC entity i, i may be the ascending order of logical channel IDs of secondary RLC entities in the order of direct path and indirect path for an MP split bearer. That is, in the present disclosure, when the existing Duplication RLC Activation / Deactivation MAC CE format is used for multipath, it is proposed that for an RLC entity i, i may be the ascending order of logical channel IDs of secondary RLC entities in the order of direct path and indirect path for an MP split bearer.

[0347] Using the methods described in the present disclosure, the network can re-establish direct and / or indirect paths for multi-path while remote terminals and relay terminals release and add specific radio bearers for data and PC5-RRC messages, but can also maintain signaling radio bearers for PC5-S signaling according to the present disclosure, particularly when direct or indirect paths are added or changed.

[0348] Based on the methods described in the present disclosure, there is a technical effect that a wireless communication system can provide multi-path operation including direct link and indirect link through U2N relay.

[0349] General devices to which the present disclosure may be applied

[0350] FIG. 15 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.

[0351] Referring to FIG. 15, the first device (100) and the second device (200) can transmit and receive wireless signals through various wireless access technologies (e.g., LTE, NR).

[0352] A first device (100) includes one or more processors (102) and one or more memories (104), and may additionally include one or more transceivers (106) and / or one or more antennas (108). The processor (102) controls the memories (104) and / or the transceivers (106), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure.

[0353] For example, the processor (102) may process information in the memory (104) to generate first information / signal and then transmit a wireless signal including the first information / signal through the transceiver (106). In addition, the processor (102) may receive a wireless signal including second information / signal through the transceiver (106) and then store information obtained from signal processing of the second information / signal in the memory (104).

[0354] The memory (104) may be connected to the processor (102) and may store various information related to the operation of the processor (102). For example, the memory (104) may perform some or all of the processes controlled by the processor (102), or may store software code including commands for performing the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in the present disclosure. Here, the processor (102) and the memory (104) may be part of a communication modem / circuit / chip designed to implement a wireless communication technology (e.g., LTE, NR). The transceiver (106) may be connected to the processor (102) and may transmit and / or receive wireless signals via one or more antennas (108). The transceiver (106) may include a transmitter and / or a receiver. The transceiver (106) may be used interchangeably with an RF (Radio Frequency) unit. In the present disclosure, a device may also mean a communication modem / circuit / chip.

[0355] The second device (200) includes one or more processors (202), one or more memories (204), and may further include one or more transceivers (206) and / or one or more antennas (208). The processor (202) controls the memories (204) and / or the transceivers (206), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure. For example, the processor (202) may process information in the memory (204) to generate third information / signals, and then transmit a wireless signal including the third information / signals via the transceivers (206). In addition, the processor (202) may receive a wireless signal including fourth information / signals via the transceivers (206), and then store information obtained from signal processing of the fourth information / signals in the memory (204). The memory (204) may be connected to the processor (202) and may store various information related to the operation of the processor (202). For example, the memory (204) may perform some or all of the processes controlled by the processor (202), or may store software code including commands for performing the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure. Here, the processor (202) and the memory (204) may be part of a communication modem / circuit / chip designed to implement a wireless communication technology (e.g., LTE, NR). The transceiver (206) may be connected to the processor (202) and may transmit and / or receive wireless signals via one or more antennas (208). The transceiver (206) may include a transmitter and / or a receiver. The transceiver (206) may be used interchangeably with an RF unit. In the present disclosure, a device may also mean a communication modem / circuit / chip.

[0356] Hereinafter, the hardware elements of the device (100, 200) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (102, 202). For example, one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as PHY, MAC, RLC, PDCP, RRC, SDAP). One or more processors (102, 202) may generate one or more Protocol Data Units (PDUs) and / or one or more Service Data Units (SDUs) according to the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in the present disclosure. One or more processors (102, 202) may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in the present disclosure. One or more processors (102, 202) can generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data or information according to the functions, procedures, proposals and / or methods disclosed in the present disclosure, and provide the signals to one or more transceivers (106, 206). One or more processors (102, 202) can receive signals (e.g., baseband signals) from one or more transceivers (106, 206) and obtain PDUs, SDUs, messages, control information, data or information according to the descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed in the present disclosure.

[0357] One or more processors (102, 202) may be referred to as a controller, a microcontroller, a microprocessor, or a microcomputer. One or more processors (102, 202) may be implemented by hardware, firmware, software, or a combination thereof. For example, one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), one or more Digital Signal Processing Devices (DSPDs), one or more Programmable Logic Devices (PLDs), or one or more Field Programmable Gate Arrays (FPGAs) may be included in one or more processors (102, 202). The descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in this disclosure may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, etc. The descriptions, functions, procedures, proposals, methods and / or operation flowcharts disclosed in this disclosure may be implemented using firmware or software configured to perform one or more processors (102, 202) or stored in one or more memories (104, 204) and driven by one or more processors (102, 202). The descriptions, functions, procedures, proposals, methods and / or operation flowcharts disclosed in this disclosure may be implemented using firmware or software in the form of codes, instructions and / or sets of instructions.

[0358] One or more memories (104, 204) may be coupled to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. The one or more memories (104, 204) may be configured as ROM, RAM, EPROM, flash memory, hard drives, registers, cache memory, computer-readable storage media, and / or combinations thereof. The one or more memories (104, 204) may be located internally and / or externally to the one or more processors (102, 202). Additionally, the one or more memories (104, 204) may be coupled to the one or more processors (102, 202) via various technologies, such as wired or wireless connections.

[0359] One or more transceivers (106, 206) can transmit user data, control information, wireless signals / channels, etc., as mentioned in the methods and / or flowcharts of the present disclosure, to one or more other devices. One or more transceivers (106, 206) can receive user data, control information, wireless signals / channels, etc., as mentioned in the descriptions, functions, procedures, proposals, methods and / or flowcharts of the present disclosure, from one or more other devices. For example, one or more transceivers (106, 206) can be connected to one or more processors (102, 202) and can transmit and receive wireless signals. For example, one or more processors (102, 202) can control one or more transceivers (106, 206) to transmit user data, control information, or wireless signals to one or more other devices. Additionally, one or more processors (102, 202) may control one or more transceivers (106, 206) to receive user data, control information, or wireless signals from one or more other devices. Additionally, one or more transceivers (106, 206) may be coupled to one or more antennas (108, 208), and one or more transceivers (106, 206) may be configured to transmit and receive user data, control information, wireless signals / channels, or the like, as referred to in the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure, via one or more antennas (108, 208). In the present disclosure, one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers (106, 206) can convert received user data, control information, wireless signals / channels, etc. from RF band signals to baseband signals in order to process the received user data, control information, wireless signals / channels, etc. using one or more processors (102, 202).One or more transceivers (106, 206) may convert user data, control information, wireless signals / channels, etc. processed by one or more processors (102, 202) from baseband signals to RF band signals. For this purpose, one or more transceivers (106, 206) may include an (analog) oscillator and / or filter.

[0360] The embodiments described above are combinations of components and features of the present disclosure in a predetermined form. Each component or feature should be considered optional unless explicitly stated otherwise. Each component or feature may be implemented without being combined with other components or features. Furthermore, it is also possible to combine some components and / or features to form an embodiment of the present disclosure. The order of operations described in the embodiments of the present disclosure may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment. It is self-evident that claims that are not explicitly cited in the scope of the patent may be combined to form an embodiment or incorporated as a new claim through a post-application amendment.

[0361] It will be apparent to those skilled in the art that the present disclosure may be embodied in other specific forms without departing from the essential characteristics of the present disclosure. Therefore, the above detailed description should not be construed as limiting in any respect, but rather as illustrative. The scope of the present disclosure should be determined by a reasonable interpretation of the appended claims, and all modifications within the scope of equivalents of the present disclosure are intended to be included within the scope of the present disclosure.

[0362] The scope of the present disclosure includes software or machine-executable instructions (e.g., an operating system, an application, firmware, a program, etc.) that cause operations according to the methods of various embodiments to be executed on a device or a computer, and a non-transitory computer-readable medium having such software or instructions stored thereon and executable on the device or computer. Instructions that can be used to program a processing system to perform the features described in the present disclosure can be stored on / in a storage medium or a computer-readable storage medium, and a computer program product including such a storage medium can be used to implement the features described in the present disclosure. The storage medium can include, but is not limited to, high-speed random access memory, such as DRAM, SRAM, DDR RAM, or other random access solid state memory devices, and can include non-volatile memory, such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid state storage devices. The memory optionally includes one or more storage devices remotely located from the processor(s). The memory or, alternatively, the non-volatile memory device(s) within the memory comprise a non-transitory computer-readable storage medium. The features described in this disclosure may be incorporated into software and / or firmware stored on any of the machine-readable media, which may control the hardware of the processing system and allow the processing system to interact with other mechanisms that utilize results according to embodiments of the present disclosure. Such software or firmware may include, but is not limited to, application code, device drivers, operating systems, and execution environments / containers.

[0363] Here, the wireless communication technology implemented in the device (100, 200) of the present disclosure may include not only LTE, NR, and 6G, but also Narrowband Internet of Things for low-power communication. At this time, for example, NB-IoT technology may be an example of LPWAN (Low Power Wide Area Network) technology, and may be implemented with standards such as LTE Cat NB1 and / or LTE Cat NB2, and is not limited to the above-described names. Additionally or alternatively, the wireless communication technology implemented in the device (100, 200) of the present disclosure may perform communication based on LTE-M technology. At this time, for example, LTE-M technology may be an example of LPWAN technology, and may be called by various names such as eMTC (enhanced Machine Type Communication). For example, LTE-M technology can be implemented by at least one of various standards such as 1) LTE CAT 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-BL (non-Bandwidth Limited), 5) LTE-MTC, 6) LTE Machine Type Communication, and / or 7) LTE M, and is not limited to the above-described names. Additionally or alternatively, the wireless communication technology implemented in the device (100, 200) of the present disclosure can include at least one of ZigBee, Bluetooth, and Low Power Wide Area Network (LPWAN) considering low-power communication, and is not limited to the above-described names. For example, ZigBee technology can create personal area networks (PAN) related to small / low-power digital communication based on various standards such as IEEE 802.15.4, and can be called by various names.

[0364] The method proposed in this disclosure is explained with a focus on examples applied to 3GPP LTE / LTE-A and 5G systems, but can be applied to various wireless communication systems in addition to 3GPP LTE / LTE-A and 5G systems.

Claims

1. In a method performed by a base station, the method: A step of establishing a direct path and an indirect path for multi-path operation; and A step of transmitting information indicating whether to maintain a terminal-to-terminal connection on the indirect path to a terminal associated with the multi-path operation based on addition or change of at least one of the direct path or the indirect path, A method wherein the terminal corresponds to at least one of a remote terminal of the direct path and the indirect path or a relay terminal providing the indirect path.

2. In paragraph 1, A method in which the above information is transmitted via an RRC (radio resource control) reset message.

3. In paragraph 1, The above terminal-to-terminal connection corresponds to a unicast link based on a PC5 interface between the remote terminal and the relay terminal.

4. In paragraph 1, Based on the above information indicating that the terminal-to-terminal connection is to be released, The above terminal-to-terminal connection is released, A method in which a new terminal-to-terminal connection is established between the remote terminal and the relay terminal.

5. In paragraph 4, Based on the termination of the terminal-to-terminal connection, the radio bearer for data and signaling of the terminal is released, A method wherein, after the above new terminal-to-terminal connection is established, a new radio bearer for data and signaling is established.

6. In paragraph 1, A method in which a sidelink radio bearer for data and signaling, excluding a sidelink radio bearer for PC5-S signaling of the terminal, is released and established based on the maintenance of the terminal-to-terminal connection being indicated by the above information.

7. In paragraph 6, At least one of the SL PDCP entity or SL RLC entity of the sidelink radio bearer for PC5-S signaling of the above terminal is maintained, A method wherein at least one of the SL PDCP entity or the SL RLC entity of the sidelink radio bearer for the above data and signaling is released and newly added.

8. In paragraph 1, A method in which a sidelink radio bearer for data and signaling is released and established, excluding a sidelink radio bearer for PC5-S signaling and PC5-RRC messages of the terminal, based on the maintenance of the terminal-to-terminal connection being indicated by the above information.

9. In paragraph 8, At least one of the SL PDCP entity or SL RLC entity of the sidelink radio bearer for the PC5-S signaling and PC5-RRC message of the above terminal is maintained, A method wherein at least one of the SL PDCP entity or the SL RLC entity of the sidelink radio bearer for the above data and signaling is released and newly added.

10. In paragraph 1, A method wherein the above remote terminal and the above relay terminal are set based on a terminal-to-network (UE-to-Network, U2N) relay function.

11. In the base station, the base station: one or more transceivers; and comprising one or more processors connected to said one or more transceivers, One or more of the above processors: Establish direct paths and indirect paths for multi-path operation; Based on the addition or change of at least one of the direct path or the indirect path, information is set to be transmitted to the terminal associated with the multi-path operation, indicating whether to maintain the terminal-to-terminal connection on the indirect path. A device wherein the terminal corresponds to at least one of a remote terminal of the direct path and the indirect path or a relay terminal providing the indirect path.

12. In a method performed by a terminal, the method: A step of receiving information indicating whether to maintain a terminal-to-terminal connection on an indirect path based on addition or change of at least one of a direct path and an indirect path for multi-path operation; and Based on the above information, a step of performing either a first operation of maintaining the terminal-to-terminal connection or a second operation of releasing the terminal-to-terminal connection and establishing a new terminal-to-terminal connection is included. A method in which the above information is transmitted via an RRC (radio resource control) reset message by a base station.

13. In the terminal, the terminal: one or more transceivers; and comprising one or more processors connected to said one or more transceivers, One or more of the above processors: Receive information indicating whether to maintain a terminal-to-terminal connection on an indirect path based on addition or change of at least one of a direct path and an indirect path for multi-path operation; and Based on the above information, set to perform either a first operation of maintaining the terminal-to-terminal connection or a second operation of releasing the terminal-to-terminal connection and establishing a new terminal-to-terminal connection, The above information is transmitted through an RRC (radio resource control) reset message by the base station, the device.

14. The processing device, one or more processors; and A processing device comprising one or more computer memories operatively connected to said one or more processors and storing instructions that, when executed by said one or more processors, perform a method according to any one of claims 1 to 10.

15. One or more non-transitory computer-readable media storing one or more instructions, A computer-readable medium, wherein the one or more commands are executed by one or more processors to control a device in a wireless LAN system to perform a method according to any one of claims 1 to 10.

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