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

Abstract

In the present disclosure, a method for transmitting a signal by a user equipment (UE) in a wireless communication system may comprise the steps of: receiving a first message including configuration information on a multipath (MP) bearer configured with a plurality of radio link control (RLC) entities, the plurality of RLC entities comprise at least one first RLC entity related to a direct path to the network and at least one second RLC entity related to an indirect path to the network; receiving a second message including information on activation / deactivation of each RLC entity; and transmitting the data unit based on the MP bearer configured by the configuration information.

Description

Technical Field

[0001] The present disclosure relates to a wireless communication system, and more particularly, to a method and apparatus for transmitting / receiving a wireless signal. Background Art

[0002] Wireless communication systems have been widely deployed to provide various types of communication services, such as voice or data. Generally, wireless communication systems are multiple access systems that support communication for multiple users by sharing available system resources (bandwidth, transmit power, etc.). Examples of multiple access systems include CDMA systems, FDMA systems, TDMA systems, OFDMA systems, SC-FDMA systems, and MC-FDMA systems.

[0003] Sidelink (SL) refers to a communication scheme in which a direct link is established between a user equipment (UE) and the UEs and the UEs directly exchange voice or data without intervention of a base station (BS). SL is considered a solution to alleviate the rapidly growing data traffic constraints of the BS.

[0004] Vehicle-to-everything (V2X) is a communication technology in which a vehicle exchanges information with another vehicle, pedestrians, and infrastructure through wired / wireless communications. V2X can be divided into four types: vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), vehicle-to-network (V2N), and vehicle-to-pedestrian (V2P). V2X communication can be provided via a PC5 interface and / or a Uu interface.

[0005] As more and more communication devices require greater communication capacity, enhanced mobile broadband communication relative to existing RATs is needed. Therefore, communication systems that take into account services or UEs that are sensitive to reliability and latency are being discussed. The next generation RAT that takes into account eMBB, MTC, and URLLC is called new RAT or NR. In NR, V2X communication can also be supported.

[0006] Figure 1 The diagram illustrates, by comparison, V2X communication based on pre-NR-RAT and V2X communication based on NR.

[0007] For V2X communication, the technology of providing safety services based on V2X messages such as Basic Safety Message (BSM), Collaborative Awareness Message (CAM) and Decentralized Environment Notification Message (DENM) is mainly discussed in the pre-NR RAT. V2X messages may include location information, dynamic information and attribute information. For example, a UE may send a CAM of a periodic message type and / or a DENM of an event-triggered type to another UE.

[0008] For example, CAM may include basic vehicle information, including dynamic status information such as direction and speed, vehicle static data such as size, external lighting status, path details, etc. For example, UE may broadcast CAM, and the waiting time of CAM may be less than 100ms. For example, when an unexpected event such as vehicle damage or accident occurs, UE may generate DENM and send DENM to another UE. For example, all vehicles within the transmission range of UE may receive CAM and / or DENM. In this case, DENM may have a higher priority than CAM.

[0009] Regarding V2X communication, various V2X scenarios are proposed in NR. For example, V2X scenarios include vehicle platooning, advanced driving, extended sensors, and remote driving.

[0010] For example, vehicles may be dynamically grouped and driven together based on a vehicle platoon. For example, to perform a platooning operation based on a vehicle platoon, vehicles in a group may receive periodic data from a leading vehicle. For example, vehicles in a group may widen or narrow their gaps based on the periodic data.

[0011] For example, based on advanced driving, the vehicles can be semi-autonomous or fully autonomous. For example, each vehicle can adjust trajectory or maneuver based on data obtained from nearby vehicles and / or nearby logical entities. For example, each vehicle can also share driving intent with nearby vehicles.

[0012] For example, based on the extended sensors, raw or processed data or real-time video data obtained by local sensors can be exchanged between vehicles, logical entities, pedestrian terminals and / or V2X application servers. Therefore, the vehicle can perceive a high-level environment relative to the environment that can be perceived by the vehicle's sensors.

[0013] For example, based on remote driving, remote drivers or V2X applications can operate or control remote vehicles on behalf of people who are unable to drive or are in dangerous environments. For example, cloud-based driving can be used to operate or control remote vehicles when the path can be predicted as in public transportation. For example, access to a cloud-based backend service platform can also be used for remote driving.

[0014] In NR-based V2X communications, schemes for specifying service requirements for various V2X scenarios including vehicle platooning, advanced driving, extended sensors, and remote driving are discussed. Summary of the invention

[0015] Technical issues

[0016] An object of the present disclosure is to provide a method and apparatus for accurately and efficiently performing a wireless signal transmission / reception process.

[0017] Those skilled in the art will appreciate that the objectives that can be achieved using the present disclosure are not limited to the objectives that have been specifically described above, and the above objectives and other objectives that can be achieved by the present disclosure will be more clearly understood from the following detailed description.

[0018] Technical Solution

[0019] In one aspect of the present disclosure, a method for transmitting a signal by a user equipment (UE) in a wireless communication system may include the following steps: receiving a first message including configuration information about a multipath (MP) bearer configured with a plurality of radio link control (RLC) entities, the plurality of RLC entities including at least one first RLC entity associated with a direct path to a network and at least one second RLC entity associated with an indirect path to the network; receiving a second message including information about activation / deactivation of each RLC entity; and transmitting a data unit based on the MP bearer configured by the configuration information. The configuration information may include information about data replication for transmission of the data unit. The information about activation / deactivation of each RLC entity may be configured based on an RLC entity index for the plurality of RLC entities. The RLC entity index may be determined based on the following index order: at least one first RLC entity index of the at least one first RLC entity associated with the direct path may be followed by at least one second RLC entity index of the at least one second RLC entity associated with the indirect path. The data unit transmission may be based on the data replication replication on the activated RLC entity among the plurality of RLC entities.

[0020] Preferably, the information on activation / deactivation of each RLC entity may be configured as a Medium Access Control (MAC) Control Element (CE).

[0021] Preferably, the MAC CE may include an activation / deactivation indication for each RLC entity index.

[0022] Preferably, the second message including the information on activation / deactivation of each RLC entity may be received through the direct path.

[0023] Preferably, the second message including the information on activation / deactivation of each RLC entity may be received by a remote UE in the indirect path.

[0024] Preferably, the at least one first RLC entity index may be lower than the at least one second RLC entity index.

[0025] Preferably, the data unit may be a Packet Data Convergence Protocol (PDCP) data unit, and the data copy is a PDCP data unit copy.

[0026] Preferably, the at least one second RLC entity may be at least one sidelink (SL) RLC entity associated with a relay UE in the indirect path to the network.

[0027] Preferably, the first message may be received via Radio Resource Control (RRC) signaling.

[0028] Preferably, the multiple RLC entity indexes may be logical channel identifiers of the multiple RLC entities.

[0029] In another aspect of the present disclosure, a computer-readable storage medium storing instructions is provided. When the instructions are executed by a processor, the processor is caused to perform the above method.

[0030] In another aspect of the present disclosure, a UE configured to perform the method is provided.

[0031] In another aspect of the present disclosure, an apparatus configured to control a UE is provided, the UE being configured to perform the method.

[0032] Beneficial Effects

[0033] According to the embodiments of the present disclosure, a wireless signal transmission / reception process can be performed accurately and efficiently.

[0034] Those skilled in the art will understand that the effects that can be achieved by the present disclosure are not limited to the contents specifically described above, and other advantages of the present disclosure will be more clearly understood from the following detailed description in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a diagram illustrating, in contrast, vehicle-to-everything (V2X) communication based on a former new radio access technology (NR) RAT and V2X communication based on NR.

[0036] Figure 2 The structure of an LTE system to which the embodiments can be applied is illustrated.

[0037] Figure 3 The structure of an NR system to which the implementation scheme can be applied is illustrated.

[0038] Figure 4 The structure of an NR radio frame to which an embodiment can be applied is illustrated.

[0039] Figure 5 The time slot structure of the NR frame to which the implementation scheme can be applied is illustrated.

[0040] Figure 6 A radio protocol architecture for SL communications is illustrated.

[0041] Figure 7 A UE performing V2X or SL communication is illustrated.

[0042] Figure 8 Resource units used for V2X or SL communication are illustrated.

[0043] Fig. 9 The inter-UE coordination information MAC CE is illustrated.

[0044] Fig.10 An inter-UE coordination request MAC CE is illustrated.

[0045] Fig.11 (a) User plane protocol stack and (b) control plane protocol stack for L2 UE to network relay are illustrated.

[0046] Fig.12 A protocol stack for UE-to-network relay discovery messages is illustrated.

[0047] Fig.13 The procedure for L2 U2N remote UE connection establishment is illustrated.

[0048] Fig.14 The procedure for U2N remote UE handover to direct Uu cell is illustrated.

[0049] Fig.15 The procedure for U2N remote UE switching to an indirect path is illustrated.

[0050] Fig.16 The UP protocol stack for multipath is illustrated (scenario 1).

[0051] Fig.17 The UP protocol stack for UE aggregation (similar to scenario 2 of DC) is illustrated.

[0052] Fig.18 The UP protocol stack for UE aggregation (similar to scenario 2 of DAPS) is illustrated.

[0053] Fig.19 The DL MP duplication activation / deactivation MAC CE to be carried in the MAC PDU on the DL-SCH is illustrated.

[0054] Fig. 20 The SL MP duplication activation / deactivation MAC CE to be carried in the MAC PDU on the SL-SCH is illustrated.

[0055] Fig.21The DL MP duplicate RLC activation / deactivation MAC CE to be carried in a MAC PDU on the DL-SCH is illustrated.

[0056] Fig. 22 The SL copy RLC activation / deactivation MAC CE to be carried in the MAC PDU on the SL-SCH is illustrated.

[0057] Fig.23 The DL MP Dynamic Path Switching MAC CE to be carried in the MAC PDU on the DL-SCH is illustrated.

[0058] Fig.24 The SL MP dynamic path switching MAC CE to be carried in the MAC PDU on the SL-SCH is illustrated.

[0059] Fig.25 The simultaneous establishment of direct / indirect paths in U2N-based RRC connection establishment is illustrated.

[0060] Fig.26 An example of DL data delivery status is illustrated.

[0061] Fig. 27 An operation method of a UE in one embodiment of the present disclosure is illustrated.

[0062] Fig.28 Splitting bearers is illustrated.

[0063] Fig.29 A communication system applied to the present disclosure is illustrated.

[0064] Fig.30 A wireless device suitable for use with the present disclosure is illustrated.

[0065] Fig.31 Another example of a wireless device to which the present disclosure is applied is illustrated.

[0066] Fig.32 A vehicle or an autonomous driving vehicle to which the present disclosure is applied is illustrated. DETAILED DESCRIPTION

[0067] A wireless communication system is a multiple-access system that supports communication for multiple users by sharing available system resources (bandwidth, transmit power, etc.) Examples of multiple-access systems include CDMA systems, FDMA systems, TDMA systems, OFDMA systems, SC-FDMA systems, and MC-FDMA systems.

[0068] Details of the background, terminology, abbreviations etc. used herein can be found in the following documents.

[0069] 3GPP LTE

[0070] -3GPP TS 36.211: Physical channels and modulation

[0071] -3GPP TS 36.212: Multiplexing and channel coding

[0072] -3GPP TS 36.213: Physical layer procedures

[0073] -3GPP TS 36.214: Physical layer; Measurement

[0074] -3GPP TS 36.300: Overall description

[0075] -3GPP TS 36.304: User Equipment (UE) procedures in idle mode

[0076] -3GPP TS 36.314: Layer 2 - Measurement

[0077] -3GPP TS 36.321: Medium Access Control (MAC) Protocol

[0078] -3GPP TS 36.322: Radio Link Control (RLC) protocol

[0079] -3GPP TS 36.323: Packet Data Convergence Protocol (PDCP)

[0080] -3GPP TS 36.331: Radio Resource Control (RRC) protocol

[0081] 3GPP NR

[0082] -3GPP TS 38.211: Physical channels and modulation

[0083] -3GPP TS 38.212: Multiplexing and channel coding

[0084] -3GPP TS 38.213: Physical layer procedures for control

[0085] -3GPP TS 38.214: Physical layer procedures for data

[0086] -3GPP TS 38.215: Physical layer measurements

[0087] -3GPP TS 38.300: Overall description

[0088] -3GPP TS 38.304: User Equipment (UE) procedures in idle mode and RRC inactive state

[0089] -3GPP TS 38.321: Medium Access Control (MAC) Protocol

[0090] -3GPP TS 38.322: Radio Link Control (RLC) protocol

[0091] -3GPP TS 38.323: Packet Data Convergence Protocol (PDCP)

[0092] -3GPP TS 38.331: Radio Resource Control (RRC) protocol

[0093] -3GPP TS 37.324: Service Data Adaptation Protocol (SDAP)

[0094] -3GPP TS 37.340: Multi-connectivity; general description

[0095] Sidelink (SL) refers to a communication scheme in which a direct link is established between a user equipment (UE) and the UEs and the UEs directly exchange voice or data without intervention of a base station (BS). SL is considered a solution to alleviate the rapidly growing data traffic constraints of the BS.

[0096] Vehicle-to-everything (V2X) is a communication technology in which a vehicle exchanges information with another vehicle, pedestrians, and infrastructure through wired / wireless communications. V2X can be divided into four types: vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), vehicle-to-network (V2N), and vehicle-to-pedestrian (V2P). V2X communication can be provided via a PC5 interface and / or a Uu interface.

[0097] As more and more communication devices require greater communication capacity, enhanced mobile broadband communication relative to existing RATs is needed. Therefore, communication systems that take into account services or UEs that are sensitive to reliability and latency are being discussed. The next generation RAT that takes into account eMBB, MTC, and URLLC is called new RAT or NR. In NR, V2X communication can also be supported.

[0098] The technology described herein can be used for various wireless access systems such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), etc. CDMA can be implemented as a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can be implemented as a radio technology such as Global System for Mobile Communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rate for GSM Evolution (EDGE). OFDMA can be implemented as a radio technology such as IEEE 802.11 (Wi-Fi), IEEE802.16 (WiMAX), IEEE 802.20, Evolved UTRA (E-UTRA), etc. IEEE802.16m is an evolution of IEEE 802.16e, providing backward compatibility with IRRR 802.16e-based systems. UTRA is part of Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is a part of Evolved UMTS (E-UMTS) using Evolved UTRA (E-UTRA). 3GPP LTE adopts OFDMA for downlink (DL) and SC-FDMA for uplink (UL). LTE Advanced (LTE-A) is an evolution of 3GPP LTE. 3GPP NR (New Radio or New Radio Access Technology) is an evolved version of 3GPP LTE / LTE-A / LTE-A pro.

[0099] The successor to LTE-A, the fifth generation (5G) new radio access technology (NR), is a new clean-state mobile communication system characterized by high performance, low latency, and high availability. 5G NR can use all available spectrum resources, including low frequency bands below 1 GHz, mid-frequency bands between 1 GHz and 10 GHz, and high frequency (millimeter) bands of 24 GHz or above.

[0100] Although the following description is mainly given in the context of LTE-A or 5G NR for the sake of clarity, the technical ideas of the embodiments of the present disclosure are not limited thereto.

[0101] Figure 2 The structure of the LTE system according to the embodiment of the present disclosure is illustrated. This may also be referred to as an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) or an LTE / LTE-A system.

[0102] Reference Figure 2, E-UTRAN includes an evolved Node B (eNB) 20 that provides a control plane and a user plane to UE 10. UE 10 may be fixed or mobile, and may also be referred to as a mobile station (MS), a user terminal (UT), a subscriber station (SS), a mobile terminal (MT), or a wireless device. eNB 20 is a fixed station that communicates with UE 10, and may also be referred to as a base station (BS), a base transceiver system (BTS), or an access point.

[0103] The eNBs 20 may be connected to each other via an X2 interface. The eNBs 20 are connected to an Evolved Packet Core (EPC) 39 via an S1 interface. More specifically, the eNBs 20 are connected to a Mobility Management Entity (MME) via an S1-MME interface, and to a Serving Gateway (S-GW) via an S1-U interface.

[0104] The EPC 30 includes an MME, an S-GW, and a packet data network gateway (P-GW). The MME has access information or capability information about the UE, which is mainly used for mobility management of the UE. The S-GW is a gateway with the E-UTRAN as an endpoint, and the P-GW is a gateway with a packet data network (PDN) as an endpoint.

[0105] Based on the lowest three layers of the open system interconnection (OSI) reference model known in communication systems, the radio protocol stack between the UE and the network can be divided into layer 1 (L1), layer 2 (L2), and layer 3 (L3). These layers are defined in pairs between the UE and the evolved UTRAN (E-UTRAN) for data transmission via the Uu interface. The physical (PHY) layer at L1 provides information transfer services on physical channels. The radio resource control (RRC) layer at L3 is used to control radio resources between the UE and the network. For this purpose, the RRC layer exchanges RRC messages between the UE and the eNB.

[0106] Figure 3 The structure of the NR system according to an embodiment of the present disclosure is illustrated.

[0107] Reference Figure 3 , the next generation radio access network (NG-RAN) may include next generation Node Bs (gNBs) and / or eNBs that provide user plane and control plane protocol terminations to the UE. Figure 4 In the figure, for example, NG-RAN is shown as including only gNB. gNB and eNB are connected to each other via Xn interface. gNB and eNB are connected to 5G core network (5GC) via NG interface. More specifically, gNB and eNB are connected to access and mobility management function (AMF) via NG-C interface, and to user plane function (UPF) via NG-U interface.

[0108] Figure 4 The radio frame structure in NR to which the embodiments of the present disclosure are applicable is illustrated.

[0109] Reference Figure 4 , a radio frame can be used for UL transmission and DL transmission in NR. The length of a radio frame is 10ms and can be defined by two 5ms half frames. HF may include five 1ms subframes. A subframe may be divided into one or more slots, and the number of slots in a SF may be determined according to a subcarrier spacing (SCS). Each slot may include 12 or 14 OFDM (A) symbols depending on a cyclic prefix (CP).

[0110] In the case of normal CP (NCP), each time slot may include 14 symbols, and in the case of extended CP (ECP), each time slot may include 12 symbols. Herein, a symbol may be an OFDM symbol (or CP-OFDM symbol) or an SC-FDMA symbol (or DFT-s-OFDM symbol).

[0111] Table 1 below lists the number of symbols N per time slot according to the SCS configuration μ in the NCP case slot symb , the number of time slots per frame N frame,u slot And the number of time slots N in each subframe subframe,u slot .

[0112] [Table 1]

[0113] <![CDATA[SCS(15*2 u )]]> <![CDATA[N slot symb ]]> <![CDATA[N frame,u slot ]]> <![CDATA[N subframe,u slot ]]> 15kHz(u=0) 14 10 1 30kHz(u=1) 14 20 2 60kHz(u=2) 14 40 4 120kHz(u=3) 14 80 8 240kHz(u=4) 14 160 16

[0114] The following Table 2 lists the number of symbols per time slot, the number of time slots per frame, and the number of time slots per subframe according to SCS in the ECP case.

[0115] [Table 2]

[0116] SCS(15*2^u) <![CDATA[N slot symb ]]> <![CDATA[N frame,u slot ]]> <![CDATA[N subframe,u slot ]]> 60kHz(u=2) 12 40 4

[0117] In the NR system, different OFDM(A) parameter sets (e.g., SCS, CP length, etc.) may be configured for multiple cells aggregated for one UE. Therefore, the (absolute time) duration of a time resource (e.g., a subframe, a time slot, or a TTI) (collectively referred to as a time unit (TU) for convenience) including the same number of symbols may be configured to be different for the aggregated cells.

[0118] In NR, various parameter sets or SCS can be supported to support various 5G services. For example, with 15kHz SCS, wide areas in traditional cellular bands can be supported, while with 30kHz / 60kHz SCS, dense urban areas, lower latency and wide carrier bandwidth can be supported. With 60kHz or higher SCS, bandwidths greater than 24.25GHz can be supported to overcome phase noise.

[0119] The NR frequency band may be defined by two types of frequency ranges FR1 and FR2. The values ​​in each frequency range may vary. For example, two types of frequency ranges may be given in Table 3. In the NR system, FR1 may be a "range below 6 GHz" and FR2 may be a "range above 6 GHz" known as millimeter wave (mmW).

[0120] [Table 3]

[0121] Frequency range name Corresponding frequency range Subcarrier Spacing (SCS) FR1 450MHz-6000MHz 15,30,60kHz FR2 24250MHz-52600MHz 60,120,240kHz

[0122] As mentioned above, in the NR system, the values ​​in the frequency range can be changed. For example, as listed in Table 4, the range of FR1 can be from 410 MHz to 7125 MHz. That is, FR1 can include frequency bands of 6 GHz (or 5850, 5900, and 5925 MHz) or above. For example, frequency bands of 6 GHz (or 5850, 5900, and 5925 MHz) or above can include unlicensed frequency bands. Unlicensed frequency bands can be used for various purposes, for example, vehicle communications (e.g., autonomous driving).

[0123] [Table 4]

[0124] Frequency range name Corresponding frequency range Subcarrier Spacing (SCS) FR1 410MHz-7125MHz 15,30,60kHz FR2 24250MHz-52600MHz 60,120,240kHz

[0125] Figure 5 The time slot structure in the NR frame according to an embodiment of the present disclosure is illustrated.

[0126] Reference Figure 5 , a time slot includes multiple symbols in the time domain. For example, a time slot may include 14 symbols in the NCP case and 12 symbols in the ECP case. Alternatively, a time slot may include 7 symbols in the NCP case and 6 symbols in the ECP case.

[0127] A carrier includes multiple subcarriers in the frequency domain. An RB can be defined by multiple (e.g., 12) consecutive subcarriers in the frequency domain. A bandwidth part (BWP) can be defined by multiple consecutive (physical) RBs ((P)RBs) in the frequency domain and corresponds to a parameter set (e.g., SCS, CP length, etc.). A carrier can include up to N (e.g., 5) BWPs. Data communication can be performed in an activated BWP. Each element can be referred to as a resource element (RE) in a resource grid, and a complex symbol can be mapped to an RE.

[0128] The radio interface between UEs or the radio interface between UE and the network may include L1, L2 and L3. In various embodiments of the present disclosure, L1 may refer to a PHY layer. For example, L2 may refer to at least one of a MAC layer, an RLC layer, a PDCH layer or an SDAP layer. For example, L3 may refer to an RRC layer.

[0129] Now, a description will be given of V2X or Side Link (SL) communication.

[0130] Figure 6 The radio protocol architecture for SL communication is illustrated. Specifically, Figure 6 (a) shows the user plane protocol stack of NR, and Figure 6 (b) shows the control plane protocol stack of NR.

[0131] Next, the side link synchronization signal (SLSS) and the synchronization information will be described.

[0132] The SLSS as a SL specific sequence may include a primary side link synchronization signal (PSSS) and a secondary side link synchronization signal (SSSS). The PSSS may be referred to as a side link primary synchronization signal (S-PSS), and the SSSS may be referred to as a side link secondary synchronization signal (S-SSS). For example, an M sequence of length 127 may be used for the S-PSS, and a Gold sequence of length 127 may be used for the S-SSS. For example, the UE may detect an initial signal and acquire synchronization by using the S-PSS. For example, the UE may acquire fine synchronization and detect a synchronization signal ID by using the S-PSS and the S-SSS.

[0133] The physical side link broadcast channel (PSBCH) may be a (broadcast) channel that carries basic (system) information that the UE needs to know first before sending and receiving SL signals. For example, the basic information may include information related to SLSS, duplex mode (DM) information, time division duplex (TDD) UL / DL (UL / DL) configuration information, resource pool related information, information about the type of application related to SLSS, subframe offset information, broadcast information, etc. For example, the payload size of the PSBCH may be 56 bits, including a 24-bit cyclic redundancy check (CRC) for evaluating PSBCH performance in NR V2X.

[0134] The S-PSS, S-SSS, and PSBCH may be included in a block format that supports periodic transmission (e.g., SL synchronization signal (SLSS) / PSBCH block, hereinafter referred to as a sidelink synchronization signal block (S-SSB)). The S-SSB may have the same parameter set (i.e., SCS and CP length) as the physical sidelink control channel (PSCCH) / physical sidelink shared channel (PSSCH) in the carrier, and the transmission bandwidth of the S-SSB may be within a (pre-) configured SL BWP. For example, the bandwidth of the S-SSB may be 11 RBs. For example, the PSBCH may span 11 RBs. The frequency position of the S-SSB may be (pre-) set. Therefore, the UE does not need to perform frequency hypothesis detection to discover the S-SSB in the carrier.

[0135] In the NR SL system, multiple parameter sets including different SCS and / or CP lengths may be supported. As the SCS increases, the length of the time resources used for the S-SSB transmission of the UE may be shortened. Therefore, in order to ensure the coverage of the S-SSB, the transmitting UE may send one or more S-SSBs to the receiving terminal within an S-SSB transmission period according to the SCS. For example, the number of S-SSBs sent by the transmitting terminal to the receiving terminal within an S-SSB transmission period may be pre-configured or configured for the transmitting UE. For example, the S-SSB transmission period may be 160ms. For example, for all SCSs, an S-SSB transmission period of 160ms may be supported.

[0136] For example, when the SCS in FR1 is 15kHz, the transmitting UE can send one or two S-SSBs to the receiving UE in one S-SSB transmission period. For example, when the SCS in FR1 is 30kHz, the transmitting UE can send one or two S-SSBs to the receiving UE in one S-SSB transmission period. For example, when the SCS in FR1 is 60kHz, the transmitting UE can send one, two, or four S-SSBs to the receiving UE in one S-SSB transmission period.

[0137] For example, when the SCS in FR2 is 60kHz, the transmitting UE can send 1, 2, 4, 8, 16 or 32 S-SSBs to the receiving UE in one S-SSB transmission period. For example, when the SCS in FR2 is 120kHz, the transmitting UE can send 1, 2, 4, 8, 16, 32 or 64 S-SSBs to the receiving UE in one S-SSB transmission period.

[0138] When the SCS is 60kHz, two types of CP can be supported. In addition, the structure of the S-SSB sent by the transmitting UE to the receiving UE may be different according to the CP type. For example, the CP type may be NCP or ECP. Specifically, for example, when the CP type is NCP, the number of symbols to which the PSBCH in the S-SSB sent by the transmitting UE is mapped may be 9 or 8. On the other hand, for example, when the CP type is ECP, the number of symbols to which the PSBCH in the S-SSB sent by the transmitting UE is mapped may be 7 or 6. For example, the PSBCH may be mapped to the first symbol of the S-SSB sent by the transmitting UE. For example, after receiving the S-SSB, the receiving UE may perform an automatic gain control (AGC) operation in the first symbol period of the S-SSB.

[0139] Figure 7 A UE performing V2X or SL communication is illustrated.

[0140] Reference Figure 7 , the term "UE" in V2X or SL communication may mainly refer to a user's terminal. However, when a network device such as a BS transmits and receives signals according to a UE-UE communication scheme, the BS may also be regarded as a type of UE. For example, a first UE (UE 1) may be a first device 100, and a second UE (UE 2) may be a second device 200.

[0141] For example, UE 1 may select a resource unit corresponding to a specific resource in a resource pool as a group of resources. Then, UE 1 may send an SL signal in the resource unit. For example, UE 2 as a receiving UE may be configured with a resource pool in which UE 1 may send a signal, and detect a signal from UE 1 in the resource pool.

[0142] When UE1 is within the coverage of the BS, the BS may indicate the resource pool to UE1. On the contrary, when UE1 is out of the coverage of the BS, another UE may indicate the resource pool to UE1, or UE1 may use a predetermined resource pool.

[0143] Generally, a resource pool may include a plurality of resource units, and each UE may select one or more resource units and transmit a SL signal in the selected resource units.

[0144] Figure 8 Resource units used for V2X or SL communication are illustrated.

[0145] Reference Figure 8 , the total frequency resources of the resource pool can be divided into NF frequency resources, and the total time resources of the resource pool can be divided into NT time resources. Therefore, a total of NF×NT resource units can be defined in the resource pool. Figure 8 An example is illustrated in which the resource pool is repeated with a period of NT subframes.

[0146] like Figure 8 As illustrated in FIG, a resource unit (e.g., unit #0) may appear periodically repeatedly. Alternatively, in order to achieve a diversity effect in the time domain or frequency domain, the index of the physical resource unit to which a logical resource unit is mapped may change in a predetermined pattern over time. In the resource unit structure, a resource pool may refer to a collection of resource units that a UE can use to send SL signals.

[0147] Resource pools can be classified into several types. For example, each resource pool is classified according to the content of the SL signal transmitted in the resource pool as follows.

[0148] (1) Scheduling Assignment (SA) may include information about the location of resources used by the transmitting UE to transmit the SL data channel, the modulation and coding scheme (MCS) or multiple-input multiple-output (MIMO) transmission scheme required for data channel demodulation, timing advance (TA), etc. SA may be multiplexed with SL data in the same resource unit for transmission. In this case, the SA resource pool may refer to a resource pool in which SA is multiplexed with SL data for transmission. SA may be referred to as an SL control channel.

[0149] (2) The SL data channel (PSSCH) can be a resource pool used by a transmitting UE to send user data. When SA and SL data are multiplexed in the same resource unit for transmission, only the SL data channel other than the SA information can be sent in the resource pool used for the SL data channel. In other words, the RE used to send SA information in an individual resource unit in the SA resource pool can still be used to send SL data in the resource pool of the SL data channel. For example, the transmitting UE can send the PSSCH by mapping the PSSCH to consecutive PRBs.

[0150] (3) The discovery channel may be a resource pool used by a transmitting UE to transmit information such as its ID. The transmitting UE may enable neighboring UEs to discover itself on the discovery channel.

[0151] Even when the SL signal has the same content as described above, different resource pools may be used according to the transmission / reception properties of the SL signal. For example, although the SL data channel or discovery message is the same, different resource pools may be used for the SL signal according to the transmission timing determination scheme of the SL signal (for example, whether the SL signal is transmitted at the reception time of the synchronization reference signal (RS) or at the time obtained by applying a predetermined TA to the reception time), the resource allocation scheme of the SL signal (for example, whether the BS allocates transmission resources of individual signals to individual transmitting UEs or whether the individual transmitting UE selects its own individual signal transmission resources in the resource pool), the signal format of the SL signal (for example, the number of symbols occupied by each SL signal in a subframe or the number of subframes used to transmit one SL signal), the strength of the signal from the BS, the transmission power of the SL UE, etc.

[0152] SL DRX (Side Link Discontinuous Reception)

[0153] The sidelink supports SL DRX for unicast, multicast and broadcast. Similar parameters (on duration, inactivity timer, retransmission timer, period) as for Uu are defined for SL to determine the SL active time for SL DRX. During the SL active time, the UE performs SCI monitoring for data reception (i.e., second stage SCI on PSCCH and PSSCH). The UE can skip monitoring of SCI for data reception during the SL DRX inactive time.

[0154] The actual parameters supported for each broadcast type (unicast, multicast, broadcast) are specified in the following subsections.

[0155] The SL active time of the RX UE includes the time when any of its applicable SL on-duration timers, SL inactivity timers, or SL retransmission timers (for any of unicast, groupcast, or broadcast) are running. In addition, the time slots associated with periodic transmissions announced by the TX UE and the time when the UE is expecting a CSI report (for unicast) after a CSI request are also considered as the SL active time of the RX UE.

[0156] The TX UE maintains a set of timers corresponding to the SL DRX timers in the RX UE for each pair of source / destination L2 IDs for unicast or destination L2 IDs for groupcast / broadcast. When data is available for transmission to one or more RX UEs configured with SL DRX, the TX UE selects resources taking into account the activity time of the RX UE determined by the timers maintained at the TX UE.

[0157] For unicast, SL DRX is configured per pair of source L2 ID and destination L2 ID.

[0158] The UE maintains a set of SL DRX timers for each direction for each pair of source L2 ID and destination L2 ID. The SL DRX configuration for a pair of source / destination L2 IDs in one direction can be negotiated between UEs in the AS layer. For the SL DRX configuration for each direction, where one UE is the TX UE and the other is the RX UE:

[0159] - The RX UE may send assistance information including its desired On-Duration timer, SL DRX start offset and SL DRX cycle to the TX UE, and the Mode 2 TX UE may use it to determine the SL DRX configuration of the RX UE.

[0160] - Regardless of whether auxiliary information is provided, the TX UE in RRC_IDLE / RRC_INACTIVE / OOC or in RRC_CONNECTED and using Mode 2 resource allocation determines the SL DRX configuration of the RX UE. For a TX UE in RRC_CONNECTED and using Mode 1 resource allocation, the SL DRX configuration of the RX UE is determined by the serving gNB of the TX UE.

[0161] - The TX UE sends to the RX UE the SL DRX configuration to be used by the RX UE.

[0162] -RX UE can accept or reject the SL DRX configuration.

[0163] The default SL DRX configuration for multicast / broadcast may be used for DCR messages.

[0164] When the TX UE is in RRC_CONNECTED, the TX UE may report the received assistance information to its serving gNB and send the SL DRX configuration to the RX UE after receiving the SL DRX configuration in dedicated RRC signaling from the gNB. When the RX UE is in RRC_CONNECTED, the RX UE may report the received SL DRX configuration to its serving gNB, e.g., for alignment of Uu and SLDRX configurations.

[0165] SL on-duration timer, SL inactivity timer, SL HARQ RTT timer and SL HARQ retransmission timer are supported in unicast. At the RX UE, the SL HARQ RTT timer and SL HARQ retransmission timer are maintained per SL process. In addition to the (pre)configured values ​​for each of these timers, the SL HARQ RTT timer value may be derived from the retransmission resource timing when the SCI indicates more than one transmission resource.

[0166] The SL DRX MAC CE is introduced only for SL DRX operation in unicast.

[0167] For multicast / broadcast, SL DRX is configured jointly among multiple UEs based on QoS profile and destination L2 ID. For each multicast / broadcast, multiple SL DRX configurations can be supported.

[0168] For multicast, SL on duration timer, SL inactivity timer, SL HARQ RTT and SL retransmission timer are supported. For broadcast, only SL on duration timer is supported. SL DRX period, SL on duration and SL inactivity timer are configured per QoS profile (for multicast only). The start offset and slot offset of the SL DRX period are determined based on the destination L2 ID. SL HARQ RTT timer (for multicast only) and SL HARQ retransmission timer (for multicast only) are not configured per QoS profile or per destination L2 ID. For multicast, the RX UE maintains the SL inactivity timer for each destination L2 ID, and if multiple SL inactivity timer values ​​associated with different QoS profiles are configured for the L2 ID, the largest SL inactivity timer value is selected. For multicast and broadcast, when multiple QoS profiles are configured for each destination L2 ID, the RX UE maintains a single SL DRX period (selected as the minimum SL DRX period of any QoS profile for the L2 ID) and a single SL on duration (selected as the maximum SL on duration of any QoS profile for the L2 ID) for the L2 ID.

[0169] For multicast, at the RX UE, the SL HARQ RTT timer and SL retransmission timer are maintained per SL process. The SL HARQ RTT timer may be set to different values ​​to support both HARQ enabled transmission and HARQ disabled transmission.

[0170] For QoS profiles that are not mapped to any non-default SL DRX configuration, the default SL DRX configuration that is common between multicast and broadcast can be used.

[0171] TX UE and RX UE in coverage of RRC_IDLE / RRC_INACTIVE obtain their SL DRX configuration from SIB. UE (TX or RX) in RRC_CONNECTED can obtain SL DRX configuration from SIB or from dedicated RRC signaling during handover. For out-of-coverage cases, SL DRX configuration is obtained from pre-configuration.

[0172] For multicast, the TX UE, upon receiving new data with the same destination L2 ID, restarts its timer corresponding to the SL inactivity timer for that destination L2 ID (for determining the allowable transmission time).

[0173] TX profiles are introduced to ensure compatibility of multicast and broadcast transmissions between UEs that support / do not support SL DRX functionality. TX profiles are provided by upper layers to the AS layer and identify one or more sidelink functional groups. The TX UE assumes SL DRX for the RX UE only when the associated TX profile corresponds to support for SL DRX. If all destination L2 IDs of concern have an associated TX profile corresponding to support for SL DRX, the RX UE determines to use SL DRX.

[0174] For unicast, multicast and broadcast, alignment of Uu DRX and SL DRX of UE in RRC_CONNECTED is supported. Alignment of Uu DRX and SL DRX at the same UE is supported. In addition, for Mode 1 scheduling, alignment of Uu DRX of TX UE and SL DRX of RX UE is supported.

[0175] The alignment may include full or partial overlap in time between Uu DRX and SL DRX. For SL RX UE in RRC_CONNECTED, the alignment is implemented by the gNB.

[0176] The MAC entity can be configured with SL DRX functionality through RRC, which controls the SCI (i.e., first stage SCI and second stage SCI) monitoring activities of the UE for unicast, groupcast, and broadcast. When using SL DRX operation, the MAC entity shall also monitor the SCI (i.e., first stage SCI and second stage SCI) according to the requirements found in other clauses of this specification.

[0177] RRC controls the sidelink DRX operation by configuring the following parameters:

[0178] -sl-drx-onDurationTimer: duration when SL DRX cycle starts;

[0179] -sl-drx-SlotOffset: Delay before starting sl-drx-onDurationTimer;

[0180] -sl-drx-InactivityTimer (except for broadcast transmission): duration after the first timeslot of SCI (i.e., first phase SCI and second phase SCI) reception (where the SCI indicates a new SL transmission for the MAC entity);

[0181] -sl-drx-RetransmissionTimer (per-side link process except broadcast transmission): maximum duration until SL retransmission is received;

[0182] -sl-drx-StartOffset: The time slot where the SL DRX cycle starts;

[0183] -sl-drx-Cycle: sidelink DRX cycle;

[0184] -sl-drx-HARQ-RTT-Timer (per sidelink process except broadcast transmission): Minimum duration before SL HARQ retransmission expected by the MAC entity.

[0185] When SL DRX is configured, active time includes the following times:

[0186] -sl-drx-onDurationTimer or sl-drx-InactivityTimer is running; or

[0187] -sl-drx-RetransmissionTimer is running; or

[0188] - the period of sl-LatencyBoundCSI-Report configured by RRC in case no SL-CSI Report MAC CE is received; or

[0189] - in case of reception of a SL-CSI reporting MAC CE, the time between sending the SL-CSI reporting request and receiving the SL-CSI reporting MAC CE; or

[0190] -Time slot associated with periodic transmission announced by the UE sending SL-SCH data.

[0191] When one or more SL DRXs are configured, the MAC entity shall:

[0192] 1> If multiple SL DRX cycles are mapped with multiple SL-QoS-profiles of the destination layer-2 ID and the broadcast type of interest is associated with multicast and broadcast:

[0193] 2> Select an sl-drx-Cycle whose length is the shortest of the multiple SL DRX cycles mapped to the multiple SL-QoS-Profiles associated with the destination layer-2ID:

[0194] 2> Select a sl-drx-onDurationTimer whose length is the longest one among multiple SL DRX on-duration timers mapped to multiple SL-QoS-Profiles associated with the destination layer-2 ID.

[0195] 1> If sl-drx-HARQ-RTT-Timer expires:

[0196] 2> If the data of the corresponding sidelink process is not successfully decoded, or if HARQ feedback (i.e., negative acknowledgement) is not sent for unicast due to UL / SL prioritization:

[0197] 3> Start the sl-drx-RetransmissionTimer for the corresponding side link process in the first time slot after the expiration of the sl-drx-HARQ-RTT-Timer.

[0198] When the broadcast type is multicast or broadcast as indicated by the upper layer, sl-drx-StartOffset and sl-drx-SlotOffset are derived according to the following formula:

[0199] sl-drx-StartOffset (ms) = destination layer-2 ID modulo sl-drx-Cycle (ms).

[0200] sl-drx-SlotOffset (ms) = destination layer-2 ID modulo sl-drx-onDurationTimer (ms).

[0201] 1> If SL DRX cycle is used, and [(DFNX10) + subframe number] modulo (sl-drx-Cycle) = sl-drx-StartOffset:

[0202] 2> Start sl-drx-onDurationTimer after sl-drx-SlotOffset from the start of the subframe.

[0203] 1> If SL DRX is in active time:

[0204] 2> Monitor SCI (ie, first stage SCI and second stage SCI) in the SL DRX.

[0205] 2> If SCI indicates a new SL transfer:

[0206] 3> If the source layer-1 ID of the SCI is equal to the 8 LSBs of the expected destination layer-2 ID and the destination layer-1 ID of the SCI is equal to the 8 LSBs of the expected source layer-2 ID, and the broadcast type indicator in the SCI is set to unicast:

[0207] 4> After the first timeslot of SCI reception, start or restart the sl-drx-InactivityTimer for the corresponding source layer-2ID and destination layer-2ID.

[0208] 3> If the destination layer-1 ID of the SCI (i.e., second stage SCI) is equal to the 8 LSBs of the expected destination layer-1 ID, and the broadcast type indicator in the SCI is set to multicast:

[0209] 4> select a sl-drx-InactivityTimer whose length is the largest of the multiple SL DRX inactivity timers mapped to the multiple SL-QoS-Profiles of the destination layer-2 ID associated with the destination layer-1 ID of the SCI; and

[0210] 4> After the first timeslot of SCI reception, start or restart the sl-drx-InactivityTimer for the corresponding destination layer-2ID.

[0211] 2> If SCI indicates SL transfer:

[0212] 3> If PSFCH resources are not configured for SL grant associated with SCI:

[0213] 4>Start the sl-drx-HARQ-RTT-Timer for the corresponding side link process in the time slot after the PSSCH transmission (i.e., the currently received PSSCH) ends.

[0214] 3> If PSFCH resources are configured for SL grant associated with SCI:

[0215] 4> if HARQ feedback is enabled via SCI and the broadcast type indicator in the SCI is set to unicast; or 4> if HARQ feedback is enabled via SCI and the broadcast type indicator in the SCI is set to multicast, and positive-negative acknowledgement is selected;

[0216] 5> start the sl-drx-HARQ-RTT-Timer for the corresponding sidelink process in the first time slot after the corresponding PSFCH transmission carrying SL HARQ feedback ends; or

[0217] 5> When SL HARQ feedback is not sent due to UL / SL prioritization, the sl-drx-HARQ-RTT-Timer for the corresponding sidelink process is started in the first time slot after the corresponding PSFCH resource for SL HARQ feedback ends;

[0218] 4> If HARQ feedback is enabled via SCI and the broadcast type indicator in the SCI is set to multicast, and negative acknowledgement only is selected;

[0219] 5> start the sl-drx-HARQ-RTT-Timer for the corresponding sidelink process in the first time slot after the corresponding PSFCH transmission carrying SL HARQ feedback ends; or

[0220] 5> when SL HARQ feedback is not sent due to UL / SL prioritization, start the sl-drx-HARQ-RTT-Timer for the corresponding sidelink process in the first time slot after the end of the corresponding PSFCH resource used for SL HARQ feedback; or

[0221] 5> When the SL HARQ feedback is a positive confirmation, the sl-drx-HARQ-RTT-Timer for the corresponding side link process is started in the first time slot after the corresponding PSFCH resource used for the SL HARQ feedback ends.

[0222] 4> If HARQ feedback is disabled by SCI and resources for one or more retransmission opportunities are not scheduled in SCI:

[0223] 5> Start the sl-drx-HARQ-RTT-Timer for the corresponding side link process in the time slot after the PSFCH resource ends.

[0224] 4> If HARQ feedback is disabled by SCI and resources for one or more retransmission opportunities are scheduled in SCI:

[0225] 5>Start the sl-drx-HARQ-RTT-Timer for the corresponding side link process in the time slot after the PSSCH transmission (i.e., the currently received PSSCH) ends.

[0226] NOTE: When the SCI indicates the next retransmission resource, the sl-drx-HARQ-RTT-Timer is derived from the retransmission resource timing (i.e., the next immediately following retransmission resource indicated in the SCI). When the SCI does not indicate the next retransmission resource, the UE uses the configured sl-drx-HARQ-RTT-Timer.

[0227] 3> Stop the sl-drx-RetransmissionTimer for the corresponding side link process.

[0228] 1> If a SL DRX Command MAC CE is received for a source layer-2ID and destination layer-2ID pair for unicast:

[0229] 2> Stop sl-drx-onDurationTimer for the source layer-2ID and destination layer-2ID pair for unicast;

[0230] 2> Stop the sl-drx-InactivityTimer for the source layer-2ID and destination layer-2ID pair for unicast.

[0231] Inter-UE Coordination (IUC)

[0232] SL UEs can support inter-UE coordination (IUC) in Mode 2, whereby UE-A sends information about resources to UE-B, which then uses this information for resource (re)selection. The following inter-UE coordination schemes are supported:

[0233] - IUC scheme 1, where the coordination information sent from UE-A to UE-B is the preferred and / or non-preferred resources for UE-B's transmission, and

[0234] - IUC scheme 2, where the coordination information sent from UE-A to UE-B is that there is an expected / potential resource conflict on the resources indicated by UE-B's SCI.

[0235] In scheme 1, IUC may be triggered by an explicit request from UE-B or by a condition at UE-A. UE-A determines a set of resources reserved by other UEs or a time slot in which UE-A does not expect to perform SL reception from UE-B due to half-duplex operation when UE-A is the intended receiver of UE-B. UE-A uses these resources as a set of non-preferred resources or excludes these resources to determine a set of preferred resources, and sends preferred / non-preferred resources to UE-B. UE-B's resources for resource (re)selection may be based on both the sensing results of UE-B (if available) and the coordination information received from UE-A, or it may be based only on the coordination information received from UE-A. For scheme 1, MAC CE and the second stage SCI, or only MAC CE, may be used to send IUC. Explicit requests and reports for IUC in unicast are supported.

[0236] In scheme 2, UE-A determines expected / potential resource conflicts within the resources indicated by the SCI of UE-B as resources reserved by other UEs and identified by UE-A as fully / partially overlapping with the resources indicated by the SCI of UE-B, or as time slots where UE-A is the intended receiver of UE-B and does not expect to perform SL reception on those time slots due to half-duplex operation. UE-B uses the conflicting resources to determine the resources to be reselected, and excludes the conflicting resources from the reselected resources. For scheme 2, PSFCH is used to transmit IUC.

[0237] The Sidelink Inter-UE Coordination Request (SL-IUC Req) transmission procedure is used to trigger the peer UE to send sidelink inter-UE coordination information.

[0238] The Sidelink Inter-UE Coordination Information (SL-IUC Info) reporting procedure is used to provide inter-UE coordination information to peer UEs.

[0239] -sl-LatencyBoundIUC-Report, which is maintained for each PC5-RRC connection.

[0240] The MAC entity maintains a sl-IUC-ReportTimer for each pair of source layer-2 ID and destination layer-2 ID corresponding to the PC5-RRC connection. The sl-IUC-ReportTimer is used for the SL-IUC information reporting UE to comply with the latency requirement signaled by the UE from the IUC-Information trigger. The value of the sl-IUC-ReportTimer is the same as the latency requirement of the SL-IUC information in the sl-LatencyBoundIUC-Report configured via RRC.

[0241] The MAC entity shall, for each pair of source Layer-2 ID and destination Layer-2 ID corresponding to a PC5-RRC connection that has been established by upper layers:

[0242] 1> If the SL-IUC information report has been triggered by the SL-IUC request MAC CE (and / or SCI) and has not been cancelled:

[0243] 2> If the sl-IUC-ReportTimer for the triggered SL-IUC information report is not running:

[0244] 3>Start sl-IUC-ReportTimer.

[0245] 2> If the sl-IUC-ReportTimer for the triggered SL-IUC information report expires:

[0246] 3>Cancel the triggered SL-IUC information report.

[0247] 2> Otherwise, if the MAC entity has SL resources allocated for new transmissions and due to logical channel prioritization, the SL-SCH resources can accommodate the SL-IUC information MAC CE and its subheader:

[0248] 3> Indicates the multiplexing and assembly process to generate the sidelink inter-UE coordination information MAC CE as defined in clause 6.1.3.35;

[0249] 3> Stop the sl-IUC-ReportTimer for the triggered SL-IUC information report;

[0250] 3>Cancel the triggered SL-IUC information report.

[0251] Fig. 9 The inter-UE coordination information MAC CE is illustrated.

[0252] The inter-UE coordination information MAC CE is identified by a MAC subheader with LCID specified in Table 5.

[0253] [Table 5]

[0254]

[0255] The priority of the Inter-UE Coordination Information MAC CE is fixed to '1'. It has a variable size with the following fields:

[0256] -RT: This field indicates the resource set type, i.e., preferred resource set or non-preferred resource set, as the code point value of the SCI format 2-CresourceSetType field.

[0257] -RSL: This field indicates the location of the reference slot as the code point value of the referenceSlotLocation field of SCI format 2-C. The length of this field is 17 bits. If the length of the referenceSlotLocation field in SCI format 2-C is shorter than 17 bits, this field contains the referenceSlotLocation field using the LSB bit;

[0258] -LSIi: This field indicates the lowest subchannel index of the first resource position of each TRIV as the code point value of the Lowest Index field of SCI format 2-C. LSI0 indicates the lowest subchannel index of the first resource position of the TRIV within the first resource combination, LSI1 indicates the lowest subchannel index of the first resource position of the TRIV within the second resource combination, and so on. The length of this field is 5 bits. If the length of the Lowest Index field in SCI format 2-C is shorter than 5 bits, this field contains the Lowest Index field using the LSB bit;

[0259] -RCi: This field indicates the resource combination as the code point value of the resourceCombination field of SCI format 2-C. RC0 indicates the first resource combination, RC1 indicates the second resource combination, and so on. [The maximum number of resource combinations included is 8]. The length of this field is 26 bits. If the length of the resourceCombination field in SCI format 2-C is shorter than 26 bits, this field contains the resourceCombination field using the LSB bit;

[0260] -First Resource Location i-1: This field indicates the first resource location as the code point value of the firstResourceLocation field of SCI format 2-C. First Resource Location 0 indicates the first resource location of the second resource combination, first Resource Location 1 indicates the first resource location of the third resource combination, and so on. The length of this field is 13 bits. If the length of the firstResourceLocation field in SCI format 2-C is shorter than 13 bits, this field contains the firstResourceLocation field using the LSB bit;

[0261] -R: Reserved bit, set to 0.

[0262] Fig.10 An inter-UE coordination request MAC CE is illustrated.

[0263] The Inter-UE Coordination Request MAC CE is identified by a MAC subheader with LCID as specified in Table 5. The priority of the Inter-UE Coordination Request MAC CE is fixed to '1'. It has a variable size with the following fields:

[0264] -RT: This field indicates the resource set type, i.e., preferred resource set or non-preferred resource set, as the code point value of the SCI format 2-CresourceSetType field.

[0265] -RP: This field indicates the resource reservation period as the code point value of the resourceReservationPeriod field in SCI format 2-C. The length of this field is 4 bits. If the length of the resourceReservationPeriod field in SCI format 2-C is shorter than 4 bits, this field contains the resourceReservationPeriod field using the LSB bit;

[0266] - Priority: This field indicates the priority as the code point value of the SCI format 2-C priority field. The length of this field is 3 bits;

[0267] -RSWL: This field indicates the resource selection window location as the code point value of the SCI format 2-CresourceSelectionWindowLocation field. The length of this field is 34 bits. If the length of the resourceSelectionWindowLocation field in SCI format 2-C is shorter than 34 bits, this field contains the resourceSelectionWindowLocation field using the LSB bit;

[0268] - Number of subchannels: This field indicates the number of subchannels as the code point value of the SCI format 2-C numberOfSubchannel field. The length of this field is 5 bits. If the length of the numberOfSubchannel field in SCI format 2-C is shorter than 5 bits, this field contains the numberOfSubchannel field using the LSB bit;

[0269] -R: Reserved bit, set to 0.

[0270] Sidelink Relay

[0271] Sidelink relay is introduced to support 5G ProSe UE to Network Relay (U2N Relay) functionality to provide connectivity to the network for U2N remote UEs. Both L2 and L3 U2N relay architectures are supported. The L3 U2N relay architecture is transparent to the serving RAN of the U2N relay UE, except for controlling the sidelink resources.

[0272] Relay Discovery: The AS functionality enables 5G ProSe UE to network relay discovery, using NR technology but without traversing any network nodes.

[0273] U2N Relay UE: A UE that provides a U2N Remote UE with the functionality of supporting connection to the network.

[0274] U2N Remote UE: A UE that communicates with the network via a U2N Relay UE.

[0275] Upward: The direction toward the parent node in the IAB topology.

[0276] Uu Relay RLC Channel: RLC channel between L2 U2N Relay UE and gNB, which is used for L2UE to network relay transmission packets over Uu.

[0277] A U2N relay UE should be in RRC_CONNECTED to perform relay of unicast data.

[0278] For L2 U2N relay operation, the following RRC state combinations are supported:

[0279] - Both the U2N relay UE and the U2N remote UE should be in RRC_CONNECTED to perform transmission / reception of relayed unicast data.

[0280] - The U2N relay UE may be in RRC_IDLE, RRC_INACTIVE or RRC_CONNECTED as long as all U2N remote UEs connected to the U2N relay UE are in RRC_INACTIVE or RRC_IDLE.

[0281] For L2 U2N relay, the U2N remote UE can only be configured to use resource allocation mode 2 for the data to be relayed.

[0282] A single unicast link is established between one L2 U2N relay UE and one L2 U2N remote UE. Traffic of the U2N remote UE via a given U2N relay UE and traffic of the U2N relay UE should be separated in different Uu RLC channels on Uu.

[0283] Protocol stack for SL relay

[0284] Fig.11 (a) User plane protocol stack and (b) control plane protocol stack for L2 UE to network relay are illustrated.

[0285] exist Fig.11 (a) and Fig.11The protocol stacks for the user plane and control plane of the L2 U2N relay architecture are presented in (b). The SRAP sublayer is placed above the RLC sublayer of both CP and UP at both the PC5 interface and the Uu interface. UuSDAP, PDCP and RRC are terminated between the L2 U2N remote UE and the gNB, while SRAP, RLC, MAC and PHY are terminated in each hop (i.e., the link between the L2 U2N remote UE and the L2 U2N relay UE and the link between the L2 U2N relay UE and the gNB).

[0286] For L2 U2N relay, the SRAP sublayer on the PC5 hop is used only for bearer mapping purposes. The SRAP sublayer does not exist on the PC5 hop for relaying messages for L2 U2N remote UEs on BCCH and PCCH. For messages about SRB0 for L2 U2N remote UEs, the SRAP sublayer does not exist on the PC5 hop, but the SRAP sublayer exists on the Uu hop for both DL and UL.

[0287] For L2 U2N relay, for uplink:

[0288] - The Uu SRAP sublayer supports UL bearer mapping between the ingress PC5 relay RLC channel for relay and the egress Uu relay RLC channel on the L2 U2N relay UEUu interface. For uplink relay services, different end-to-end RBs (SRBs or DRBs) of the same remote UE and / or different remote UEs can be multiplexed on the same Uu relay RLC channel.

[0289] - The Uu SRAP sublayer supports L2 U2N remote UE identification for UL traffic. The identification information of the L2 U2N remote UE Uu radio bearer and the local remote UE ID are included in the Uu SRAP header at UL so that the gNB can associate the received packets with a specific PDCP entity associated with the correct Uu radio bearer of the remote UE.

[0290] -L2 U2N The PC5 SRAP sublayer at the remote UE supports UL bearer mapping between the remote UE Uu radio bearers and the egress PC5 relay RLC channels.

[0291] For L2 U2N relay, for downlink:

[0292] -The Uu SRAP sublayer supports DL bearer mapping at the gNB to map the end-to-end radio bearers (SRBs, DRBs) of the remote UE to the Uu relay RLC channel over the relay UE Uu interface. The Uu SRAP sublayer supports DL bearer mapping and data multiplexing between multiple end-to-end radio bearers (SRBs or DRBs) of one L2 U2N remote UE and / or different L2 U2N remote UEs and one Uu relay RLC channel over the relay UE Uu interface.

[0293] - The Uu SRAP sublayer supports remote UE identification for DL ​​traffic. The identification information of the remote UE Uu radio bearer and the local remote UE ID are included by the gNB into the Uu SRAP header at DL so that the relay UE maps packets received from the remote UE Uu radio bearer to its associated PC5 relay RLC channel.

[0294] - The PC5 SRAP sublayer at the relay UE supports DL bearer mapping between the ingress Uu relay RLC channel and the egress PC5 relay RLC channel.

[0295] - The PC5 SRAP sublayer at the remote UE associates the received packets of a specific PDCP entity associated with the correct Uu radio bearer of the remote UE based on the identification information included in the Uu SRAP header.

[0296] The Local Remote UE ID is included in both the PC5 SRAP header and the Uu SRAP header. The L2 U2N relay UE is configured by the gNB with the Local Remote UE ID to be used in the SRAP header. The remote UE obtains the Local Remote ID from the gNB via Uu RRC messages including RRCSetup, RRCReconfiguration, RRCResume, and RRCReestablishment. Uu DRBs and Uu SRBs are mapped to different PC5 relay RLC channels and Uu relay RLC channels in both the PC5 hop and the Uu hop.

[0297] The gNB is responsible for avoiding conflicts in the use of the Local Remote UE ID. The gNB may update the Local Remote UE ID by sending the updated Local Remote ID to the relay UE via an RRCReconfiguration message. The serving gNB may perform the Local Remote UE ID update independently of the PC5 unicast link L2 ID update procedure.

[0298] Fig.12 A protocol stack for UE-to-network relay discovery messages is illustrated.

[0299] Supports both Model A discovery model and Model B discovery model for U2N relay discovery. Fig.12 The protocol stack used for discovery is presented in .

[0300] The U2N remote UE may perform relay discovery message transmission and may monitor the relay discovery message on the sidelink when in RRC_IDLE, RRC_INACTIVE or RRC_CONNECTED. The network may broadcast a threshold value that is used by the U2N remote UE to determine whether it can send a relay discovery solicitation message to the U2N relay UE.

[0301] A U2N relay UE may perform relay discovery message transmission and may monitor relay discovery messages on the sidelink while in RRC_IDLE, RRC_INACTIVE, or RRC_CONNECTED. The network may broadcast a maximum Uu RSRP threshold, a minimum Uu RSRP threshold, or both, which the U2N relay UE uses to determine whether it can send a relay discovery message to a U2N remote UE.

[0302] The network may use broadcast or dedicated signaling to provide relay discovery configuration for relay discovery. In addition, U2N remote UE and U2N relay UE may use pre-configuration for relay discovery.

[0303] The resource pool for NR side link communication can be used for relay discovery, or the network can configure a resource pool dedicated to relay discovery. The resource pool dedicated to relay discovery can be configured simultaneously with the resource pool for NR side link communication in system information, dedicated signaling and / or pre-configuration. Whether to configure a resource pool dedicated to relay discovery is based on network implementation. If a resource pool dedicated to relay discovery is configured, only those resource pools dedicated to relay discovery should be used for relay discovery. If only resource pools for NR side link communication are configured, all configured transmission resource pools can be used for relay discovery and side link communication.

[0304] For a U2N remote UE that has connected to the network via a U2N relay UE (including both in-coverage and out-of-coverage cases), only resource allocation mode 2 is used for discovery message transmission.

[0305] Relay discovery reuses the NR sidelink resource allocation principles for in-coverage U2N relay UEs and for both in-coverage and out-of-coverage U2N remote UEs.

[0306] The sidelink power control used to transmit relay discovery messages is the same as that used for NR sidelink communications.

[0307] No ciphering or integrity protection in the PDCP layer is applied to the Relay Discovery message.

[0308] The UE can determine from SIB12 whether the gNB supports relay discovery, non-relay discovery, or both.

[0309] Relay selection / reselection

[0310] The U2N Remote UE performs radio measurements at the PC5 interface and uses them together with higher layer criteria for U2N Relay selection and reselection. When there is no unicast PC5 connection between the U2N Relay UE and the U2N Remote UE, the U2N Remote UE uses SD-RSRP measurements to evaluate whether the PC5 link quality towards the U2N Relay UE meets the relay selection criteria.

[0311] For relay reselection, when there is data transmission from the U2N relay UE to the U2N remote UE, the U2N remote UE uses the SL-RSRP measurement towards the serving U2N relay UE for relay reselection trigger evaluation, and in the absence of data transmission from the U2N relay UE to the U2N remote UE, whether SL-RSRP or SD-RSRP is used for relay reselection trigger evaluation depends on the UE implementation.

[0312] If the PC5 link quality measured by the U2N Remote UE towards the U2N Relay UE exceeds a configured threshold (pre-configured or provided by the gNB), the U2N Relay UE is considered suitable in terms of radio criteria. The U2N Remote UE searches for a suitable U2N Relay UE candidate that meets all AS layer and higher layer criteria (see TS 23.304 [xx]). If there are multiple such suitable U2N Relay UEs, one U2N Relay UE is selected among them depending on the U2N Remote UE implementation. For L2 U2N Relay (re)selection, PLMN ID and Cell ID may be used as additional AS criteria.

[0313] The U2N remote UE triggers the U2N relay selection in the following cases:

[0314] -The direct Uu signal strength of the current serving cell of the U2N remote UE is lower than the configured signal strength threshold;

[0315] - Indicated by upper layers of the U2N remote UE.

[0316] The U2N remote UE can trigger U2N relay reselection in the following situations:

[0317] -The current PC5 signal strength of the U2N relay UE is lower than the (pre-)configured signal strength threshold;

[0318] -Cell (reselection) selection, handover or Uu RLF has been indicated by the U2N relay UE via PC5-RRC signalling;

[0319] -When the remote UE receives a PC5-S link release message from the U2N relay UE;

[0320] -When the U2N remote UE detects PC5 RLF;

[0321] -Instructed by upper layer.

[0322] For L2 U2N remote UE and L3 U2N remote UE in RRC_IDLE / INACTIVE, the cell (re)selection process and relay (re)selection process run independently. If both a suitable cell and a suitable U2N relay UE are available, the selection of the cell or the U2N relay UE depends on the UE implementation. The L3 U2N remote UE can select both the cell and the U2N relay UE at the same time, and this depends on the implementation of the L3 U2N remote UE.

[0323] For both L2 and L3 U2N relay UEs in RRC_IDLE / INACTIVE, the PC5-RRC message is used to notify its connected remote UEs when the U2N relay UE selects a new cell. The PC5-RRC message is also used to notify its connected L2 or L3 U2N remote UEs when the L2 / L3 U2N relay UE performs a handover or detects a Uu RLF. After receiving the PC5 RRC message for notification, whether to release or maintain the unicast PC5 link depends on the U2N remote UE implementation. If the U2N remote UE decides to release the unicast PC5 link, it triggers the L2 release procedure and can perform relay reselection.

[0324] Control plane procedures for L2 U2N relay

[0325] 1)RRC connection management

[0326] U2N remote UE needs to establish its own PDU session / DRB with the network before user plane data transmission.

[0327] Before the U2N remote UE establishes a Uu RRC connection with the network via the U2N relay UE, the NR V2X PC5 unicast link establishment procedure may be reused to establish a secure unicast link between the U2N remote UE and the U2N relay UE.

[0328] The establishment of Uu SRB1 / SRB2 and DRB of U2N remote UE is subject to the Uu configuration process from L2 UE to network relay.

[0329] Fig.13 The procedure for L2 U2N remote UE connection establishment is illustrated. Fig.13 The following high-level connection establishment process applies to L2 U2N trunking:

[0330] 1. The U2N Remote and U2N Relay UEs perform the discovery procedure and establish a PC5-RRC connection using NR V2X procedures.

[0331] 2. The U2N Remote UE sends a first RRC message (i.e., RRCSetupRequest) via the Relay UE for its connection establishment with the gNB using the designated PC5 Relay RLC channel configuration. If the U2N Relay UE is not in RRC_CONNECTED, it needs to do its own connection establishment after receiving the message on the designated PC5 Relay RLC channel. During the RRC connection establishment procedure of the Relay UE, the gNB may configure the SRB0 Relay Uu Relay RLC channel to the U2N Relay UE. The gNB responds to the U2N Remote UE with an RRCSetup message. An RRCSetup message is sent to the U2N Remote UE using the SRB0 Relay channel on Uu and the designated PC5 Relay RLC channel on PC5.

[0332] 3. gNB and U2N Relay UE perform the Relay Channel Establishment Procedure on Uu. Based on the configuration from gNB, U2N Relay / Remote UE establishes PC5 Relay RLC channel for relaying SRB1 towards U2N Remote / Relay UE on PC5.

[0333] 4. The RRCSetupComplete message is sent by the U2N remote UE to the gNB via the U2N relay UE using the SRB1 relay channel on PC5 and the SRB1 relay channel configured for the U2N relay UE on Uu. The U2N remote UE then establishes an RRC connection on Uu.

[0334] 5. The U2N remote UE and gNB establish security following Uu procedures and forward security messages via the U2N relay UE.

[0335] 6. The gNB sends an RRCReconfiguration message to the U2N Remote UE via the U2N Relay UE to set up SRB2 / DRB for relay purposes. The U2N Remote UE sends an RRCReconfigurationComplete message to the gNB via the U2N Relay UE in response. In addition, the gNB configures an additional Uu Relay RLC channel between the gNB and the U2N Relay UE and a PC5 Relay RLC channel between the U2N Relay UE and the U2N Remote UE for relay services.

[0336] 2) Radio link failure

[0337] When a U2N remote UE is connected to the gNB via a U2N relay UE, the U2N remote UE in RRC_CONNECTED suspends Uu RLM.

[0338] The U2N relay UE declares a Radio Link Failure (RLF) following the same criteria.

[0339] After declaring RLF, the U2N relay UE also takes the following actions on top of the actions:

[0340] - The PC5-RRC message may be used to send an indication to the U2N remote UE to which it is connected, which may trigger the RRC connection re-establishment (Connection Re-establishmen) for the U2N remote UE.

[0341] After detecting PC5 RLF, the U2N remote UE can trigger connection re-establishment.

[0342] 3)RRC connection reestablishment

[0343] The U2N remote UE may perform the following actions during the RRC connection reestablishment procedure:

[0344] - If only a suitable cell is available, the U2N remote UE initiates the RRC re-establishment procedure towards the suitable cell;

[0345] - If only a suitable U2N relay UE is available, the U2N remote UE initiates an RRC re-establishment procedure towards the serving cell of the suitable relay UE;

[0346] - If both a suitable cell and a suitable relay are available, the U2N remote UE may select either one to initiate the RRC re-establishment procedure based on implementation.

[0347] 4)RRC connection recovery

[0348] The RRC connection recovery mechanism is applied to the U2N remote UE.

[0349] 5) System Information

[0350] The U2N remote UE in coverage is allowed to obtain any necessary SIBs over the Uu interface regardless of its PC5 connection with the relay UE. The U2N remote UE can also receive system information from the relay UE after the PC5 connection with the U2N relay UE is established.

[0351] A U2N remote UE in RRC_CONNECTED may request SIBs via a U2N relay UE using the on-demand SIB framework. A U2N remote UE in RRC_IDLE or RRC_INACTIVE may notify the U2N relay UE of the type of SIB it requested via a PC5-RRC message. The U2N relay UE then triggers the on-demand SI / SIB acquisition procedure based on its own RRC state (if necessary) and sends the acquired SI / SIB to the U2N remote UE via PC5-RRC.

[0352] A U2N Remote UE in RRC_IDLE or RRC_INACTIVE may request (from the U2N Relay UE or the network) any SIBs that the U2N Remote UE requires to use (e.g. for relay purposes). For SIBs that the U2N Remote UE has requested from the U2N Relay UE, the U2N Relay UE forwards them again in case of any updates to the requested SIBs. In the case of a U2N Remote UE in RRC_CONNECTED, the network is responsible for sending updated SIBs to the U2N Remote UE when the SIBs are updated. The U2N Remote UE deconfigures the SI request to the U2N Relay UE when entering the RRC_CONNECTED state.

[0353] For SIB1 forwarding, for U2N remote UEs, the U2N relay UE supports both request-based delivery (i.e., SIB1 request by the U2N remote UE) and unsolicited forwarding, where which one is used depends on the U2N relay UE implementation. If SIB1 changes, the U2N relay UE always forwards SIB1 for U2N remote UEs in RRC_IDLE or RRC_INACTIVE.

[0354] For L2 U2N remote UEs in RRC_IDLE or RRC_INACTIVE, the L2 U2N relay UE does not forward short messages on the Uu interface to the L2 U2N remote UEs. The L2 U2N relay UE may forward the PWS SIB to its connected L2 U2N remote UEs.

[0355] L2 U2N relay UE supports RAN sharing. In particular, before establishing a PC5-RRC connection, the L2 U2N relay UE can forward cell access related information via a discovery message.

[0356] 6) Paging

[0357] When both the U2N relay UE and the U2N remote UE are in RRC IDLE or RRC INACTIVE, the U2N relay UE monitors the paging occasion of the U2N remote UE to which it is connected. When the U2N relay UE needs to monitor the paging of the U2N remote UE, the U2N relay UE shall monitor all POs of the U2N remote UE.

[0358] When the U2N Relay UE is in RRC CONNECTED and the U2N Remote UE is in RRC_IDLE or RRC_INACTIVE, there are two options for paging delivery:

[0359] - If the active DL BWP of the U2N relay UE is configured with CORESET and paging search space, the U2N relay UE monitors the PO of its connected U2N remote UE.

[0360] - Delivery of paging of U2N remote UEs may be performed by a dedicated RRC message from the gNB to the U2N relay UE. The dedicated RRC message for delivering remote UE paging to an RRC_CONNECTED relay UE may contain one or more remote UE IDs (5G-S-TMSI or I-RNTI).

[0361] The decision of which of the above two options to use depends on the network implementation.If configured with a paging search space, a U2N relay UE in RRC CONNECTED may determine whether to monitor PO for a U2N remote UE based on PC5-RRC signaling received from the U2N remote UE.

[0362] The U2N remote UE in RRC_IDLE provides the 5G-S-TMSI and UE-specific DRX cycle (configured by upper layers) to the U2N relay UE to request the U2N relay UE to perform PO monitoring. The U2N remote UE in RRC_INACTIVE provides the minimum of two UE-specific DRX cycles (configured by upper layers and configured by RAN), 5G-S-TMSI and I-RNTI to the U2N relay UE for PO monitoring. The L2 U2N relay UE can notify the gNB of the remote UE information (i.e., 5G-S-TMSI / I-RNTI) via the SidelinkUEInformationNR message for paging delivery purposes. The U2N relay UE receives the paging message to check the 5G-S-TMSI / I-RNTI and sends the relevant paging record to the remote UE accordingly.

[0363] The U2N relay UE may use unicast signaling to send paging to the U2N remote UE via PC5.

[0364] 7) Access Control

[0365] The U2N remote UE performs unified access control. The U2N relay UE in RRC-CONNECTED does not perform UAC for the data of the U2N remote UE.

[0366] 8) Mobility registration update and RAN area update

[0367] When a L2 U2N remote UE is connected to a L2 U2N relay UE, it performs a mobility registration update / RNAU based on the serving cell of the L2 U2N relay UE. If the serving cell changes (due to a cell change of the U2N relay UE) and the new serving cell is outside the configured RNA / TA of the U2N remote UE, the L2 U2N remote UE in RRC_IDLE or RRC_INACTIVE initiates a mobility registration update / RNAU procedure.

[0368] Service continuity for L2 U2N trunking

[0369] 1) Switching from indirect to direct path

[0370] Fig.14 The process of U2N remote UE handover to direct Uu cell is illustrated.

[0371] For service continuity over L2 U2N relay, in case the U2N remote UE switches to direct path, the following procedure is used:

[0372] 1. Perform Uu measurement configuration and measurement report signaling procedures to evaluate both relay link measurements and Uu link measurements. When the configured measurement report criteria are met, the measurement results from the U2N remote UE are reported. The sidelink relay measurement report shall include at least the source L2 ID of the U2N relay UE, the serving cell ID (i.e., NCGI), and the sidelink measurement quantity information. The sidelink measurement quantity may be the SL-RSRP of the serving U2N relay UE, and if SL-RSRP is not available, SD-RSRP is used.

[0373] 2. The gNB decides to switch the U2N remote UE to the direct Uu path.

[0374] 3. The gNB sends an RRCReconfiguration message to the U2N remote UE. The U2N remote UE stops UP and CP transmission via the U2N relay UE after receiving the RRCReconfiguration message from the gNB.

[0375] 4. The U2N remote UE synchronizes with the gNB and performs random access.

[0376] 5. The UE (i.e., the U2N Remote UE in the previous step) sends an RRCReconfigurationComplete to the gNB via a direct path using the configuration provided in the RRCReconfiguration message. According to this step, the UE (i.e., the U2N Remote UE in the previous step) uses an RRC connection via a direct path to the gNB.

[0377] 6. The gNB sends an RRCReconfiguration message to the U2N Relay UE to reconfigure the connection between the U2N Relay UE and the gNB. The RRCReconfiguration message to the U2N Relay UE may be sent at any time after step 3 based on the gNB implementation (e.g., to release the Uu and PC5 Relay RLC channel configurations for relaying, and the bearer mapping configuration between PC5 RLC and Uu RLC).

[0378] 7. The U2N relay UE or the U2N remote UE may initiate a PC5 unicast link release (PC5-S). The timing of performing the link release depends on the UE implementation. After receiving the RRC reconfiguration from the gNB in ​​step 6, the U2N relay UE may perform a PC5 connection reconfiguration to release the PC5 relay RLC channel for relaying, or after receiving the RRC reconfiguration from the gNB in ​​step 3, the UE (i.e., the previous U2N remote UE) may perform a PC5 connection reconfiguration to release the PC5 relay RLC channel for relaying.

[0379] 8. The data path is switched from the indirect path between the UE (i.e., the previous U2N remote UE) and the gNB to the direct path. DL / UL lossless delivery during path switching is accomplished according to the PDCP data recovery procedure.

[0380] Note: Step 8 can be performed at any time after Step 4. Step 8 is independent of Step 6 and Step 7.

[0381] 2) Switching from direct to indirect paths

[0382] Fig.15 The process of U2N remote UE switching to indirect path is illustrated.

[0383] The gNB may select a U2N relay UE in any RRC state (i.e., RRC_IDLE, RRC_INACTIVE, or RRC_CONNECTED) as a target U2N relay UE for handover from a direct to indirect path.

[0384] For service continuity of L2 U2N remote UE, in case the L2 U2N remote UE switches to an indirect path via a U2N relay UE in RRC_CONNECTED, the following procedure is used:

[0385] 1. After the U2N remote UE measures / discovers the candidate U2N relay UE, the U2N remote UE reports one or more candidate U2N relay UEs and Uu measurements.

[0386] - The UE may filter appropriate U2N relay UEs according to the relay selection criteria before reporting. The UE shall only report U2N relay UE candidates that meet higher layer criteria.

[0387] - The report may include at least the U2N relay UE ID, the serving cell ID of the U2N relay UE and the sidelink measurement quantity information. The sidelink measurement quantity may be the SL-RSRP of the candidate U2N relay UE, and if the SL-RSRP is not available, the SD-RSRP is used.

[0388] 2. The gNB decides to handover the U2N remote UE to the target U2N relay UE. Then, the gNB sends an RRCReconfiguration message to the target U2N relay UE, which may include at least the local ID and L2ID of the remote UE, the Uu and PC5 relay RLC channel configurations for relaying, and the bearer mapping configuration.

[0389] 3. The gNB sends an RRCReconfiguration message to the U2N remote UE. The content in the RRCReconfiguration message may include at least the U2N relay UE ID, the PC5 relay RLC channel configuration for the relay service, and the associated end-to-end radio bearers. After receiving the RRCReconfiguration message from the gNB, the U2N remote UE stops UP and CP transmission over Uu.

[0390] 4. The U2N remote UE establishes a PC5 connection with the target U2N relay UE.

[0391] 5. The U2N remote UE completes the path switching process by sending an RRCReconfigurationComplete message to the gNB via the relay UE.

[0392] 6. The data path is switched from the direct path to the indirect path between the U2N remote UE and the gNB.

[0393] In the case where the selected U2N relay UE for direct to indirect path switching is in RRC_IDLE or RRC_INACTIVE, after receiving the path switching command, the U2N remote UE establishes a PC5 link with the U2N relay UE and sends an RRCReconfigurationComplete message via the U2N relay UE, which will trigger the U2N relay UE to enter the RRC_CONNECTED state. Fig.15 The process of U2N remote UE switching to indirect path in can also be applied to the case where the selected U2N relay UE for direct to indirect path switching is in RRC_IDLE or RRC_INACTIVE, except that step 4 is performed before step 2.

[0394] Sidelink Discovery

[0395] The UE may perform NR sidelink discovery when in-coverage or out-of-coverage for non-relay operation.

[0396] The relay discovery mechanism (in addition to the discovery message transmission based on U2N relay-specific thresholds) is also applied to sidelink discovery.

[0397] Dynamic path switching and activation and deactivation of PDCP replication for multipath operation

[0398] The benefits of multipathing are expected in the following areas:

[0399] - Relay and direct multipath operations (including scenario 1 and scenario 2) can provide efficient path switching between direct and indirect paths

[0400] -Remote UEs in multipath operation can provide enhanced user data throughput and reliability compared to a single link.

[0401] - The gNB may offload the direct connection of a congested remote UE to an indirect connection via a relay UE (e.g., at a different intra-frequency / inter-frequency cell).

[0402] Multipath with relaying and UE aggregation may improve throughput and reliability / robustness, for example, for UEs at the cell edge and UEs with limited UL transmission power.

[0403] The terms "relay UE" and "remote UE" are used for both scenario 1 and scenario 2. Additional terminology specific to scenario 2 will be used.

[0404] The remote UE in scenario 1 and the remote UE in scenario 2 are as follows:

[0405] - Scenario 1: Remote UE is connected to the same gNB via 1) Layer 2 UE to Network Relay using one direct path and one indirect path,

[0406] - Scenario 2: The remote UE is connected to the same gNB via 2) another UE (in which UE-UE interconnection is assumed to be ideal) using one direct path and one indirect path.

[0407] It is assumed that the relationship between the remote UE and the relay UE in scenario 2 is preconfigured or static, and how the relationship is preconfigured or static is outside the scope of 3GPP.

[0408] In scenario 2, the authorization and association mechanism between the remote UE and the relay UE can be discussed.

[0409] Rel-18 supports the following cell deployment scenarios for multipath relay:

[0410] - Scenario C1: The relay UE and the remote UE are served by the same cell.

[0411] - Scenario C2: Relay UE and remote UE are served by different intra-frequency cells of the same gNB

[0412] - Scenario C3: Relay UE and remote UE are served by different inter-frequency cells of the same gNB

[0413] The following sidelink scenarios for multipath are supported:

[0414] - Scenario S1: SL TX / RX and Uu share the same carrier at the remote UE.

[0415] - Scenario S2: SL TX / RX and Uu use different carriers at the remote UE.

[0416] - Scenario S3: SL TX / RX and Uu share the same carrier at the relay UE.

[0417] - Scenario S4: SL TX / RX and Uu use different carriers at the relay UE.

[0418] Direct bearers (bearers mapped to a direct path on Uu), indirect bearers (bearers mapped to an indirect path via a relay UE) and MP split bearers (bearers mapped to two paths based on the existing split bearer framework) are supported.

[0419] For MP split bearer in scenario 1, one PDCP entity at the remote UE is configured with one direct Uu RLC channel and one indirect PC5 RLC channel.

[0420] -For uplink data flow, the PDCP entity delivers to the Uu RLC entity at the remote UE side and the PC5 RLC entity with the SRAP entity.

[0421] -For downlink data flow, the PDCP entity receives from the Uu RLC entity and the PC5 RLC entity with the SRAP entity at the remote UE side.

[0422] In scenario 2 there may be a decision regarding the mapping of protocol entities.

[0423] From one perspective, multipath scenarios should be supported in Rel-18.

[0424] Both intra-DU case and inter-DU case shall be supported under the same gNB.

[0425] Control plane and user plane scenarios for multipath support need to be defined.

[0426] The primary path in multipath support needs to be defined.

[0427] The following supports adding direct / indirect paths:

[0428] - Add the direct path after establishing the indirect path.

[0429] - Add indirect paths after direct paths are established.

[0430] - This does not mean to exclude any other path addition possibilities.

[0431] The signaling impact of direct or indirect path change under the same gNB for UEs connected via multiple paths is studied. Other mobility scenarios may be further considered based on RAN2 decisions.

[0432] The following use cases may not be supported in Rel-18

[0433] -Configure two indirect paths

[0434] - More than two paths

[0435] -Inter-gNB multipath support

[0436] In the NR standard discussion, it is agreed that for MP split bearer in scenario 1, one PDCP entity at the remote UE is configured with one direct Uu RLC channel and one indirect PC5 RLC channel. For uplink data flow, the PDCP entity delivers to the Uu RLC entity and the PC5 RLC entity with SRAP entity at the remote UE side. For downlink data flow, the PDCP entity receives from the Uu RLC entity and the PC5 RLC entity with SRAP entity at the remote UE side. Note that it should be understood that the SRAP entity is also configured for the indirect path in scenario 1, considering that the indirect path corresponds to the Rel-17 U2N RLC channel.

[0437] An adaptation layer is also needed to support Fig.16 Scenario 2 in (e.g., for data routing with bearer mapping / identification), while other scenarios are considered not to require an adaptation layer (e.g., Fig.17 or Fig.18 middle).

[0438] According to the prior art, when the relay UE and the remote UE are configured with UE-to-network relay (U2N relay) functions, the relay UE provides the U2N remote UE with a connection to the network. In this case, the remote UE does not have a direct connection to the network, while maintaining an indirect connection based on the U2N relay function.

[0439] At the same time, it is beneficial for the remote UE to support multi-path (MP) operation by maintaining only a direct connection on Uu and an indirect connection based on both PC5 and Uu. A remote UE configured with MP operation can select one or both of the connections for data transmission towards the network to achieve more reliable transmission and / or higher throughput.

[0440] For MP operation, the remote UE configures an indirect connection and a direct connection. It is unclear how the remote UE selects one or both of the indirect connection and the direct connection for data transmission and how the remote UE performs path switching and PDCP duplication.

[0441] The method for performing data transmission by a UE comprises the following steps:

[0442] When both a direct path and an indirect path through a relay UE are configured between a base station and a remote UE, a method of activation / deactivation of PDCP duplication and path switching based on activation / deactivation of one or more RLC entities of a split bearer configured in the remote UE is proposed.

[0443] For MP split bearers, one PDCP entity is associated with one primary RLC entity and one or more split secondary RLC entities. When a bearer is configured, the gNB may inform the remote UE which RLC entity to use for the primary RLC entity or split secondary RLC entity, for example by indicating in the bearer configuration the path type associated with the RLC entity and / or the LCID (Logical Channel Identity) associated with the RLC entity, which may be sent to the remote UE indirectly via a relay UE or directly from the gNB.

[0444] In the configuration from the gNB,

[0445] - Each RLC entity of an MP split bearer can be associated with a direct path or an indirect path.

[0446] - Each RLC entity of the MP split bearer can be configured as a primary RLC entity or a split secondary path.

[0447] If no explicit configuration / command is received from the gNB, the remote UE considers one or more of the following:

[0448] - An RLC entity associated with a direct path is always configured as a primary RLC entity, and an RLC entity associated with an indirect path is always configured as a split secondary RLC entity.

[0449] - An RLC entity associated with an indirect path is always configured as a primary RLC entity, and an RLC entity associated with a direct path is always configured as a split secondary RLC entity.

[0450] Upon detecting one or more of the following conditions, if a primary RLC entity for an MP split bearer has been configured on a direct path, the RLC entity associated with the indirect path (i.e., the SL RLC entity) is (re)configured as a primary RLC entity and activated if in a deactivated state, while the RLC entity associated with the direct path (i.e., the UL RLC entity) is (re)configured as a split secondary RLC entity for the MP split bearer and deactivated if in an activated state.

[0451] - Detection of Uu failure in direct path

[0452] Upon detecting one or more of the following conditions, if a primary RLC entity for an MP split bearer has been configured on an indirect path, the RLC entity associated with the direct path (i.e., the UL RLC entity) is (re)configured as a primary RLC entity and activated if in a deactivated state, while the RLC entity associated with the indirect path (i.e., the SL RLC entity or the U2NRLC entity) is (re)configured as a split secondary RLC entity for the MP split bearer and deactivated if in an activated state.

[0453] - Detection of sidelink failures in the indirect path (i.e., between the remote UE and the relay UE)

[0454] - Receive failure information from relay UE (e.g., Uu failure between relay UE and gNB)

[0455] In the present application, failure may correspond to one or more of integrity protection failure, RLC retransmission failure, RLF, bearer reconfiguration failure, beam failure, measurement results below a threshold, (high) congestion level above a threshold, and LBT failure on the side link or Uu.

[0456] If one or more MP split RBs are configured with MP PDCP duplication, the gNB may activate and deactivate PDCP duplication for all or a subset of the associated RLC entities of the configured DRBs.

[0457] PDCP duplication of RBs for MP split bearer type configuration is activated and deactivated in the remote UE in the following ways:

[0458] -Receive a DL MP duplicated activation / deactivation MAC CE in DL directly from the gNB; or

[0459] - Receive the DL MP replicated RLC Activation / Deactivation MAC CE in DL directly from the gNB; or

[0460] - indirectly receiving the SL MP Duplication Activation / Deactivation MAC CE in the SL from the gNB via the relay UE; or

[0461] o For this reception in the remote UE, when the relay UE receives the MP duplication activation / deactivation MAC CE in DL from the gNB, the relay UE replicates and relays the MP duplication activation / deactivation MAC CE to be sent in the SL.

[0462] - indirectly receive the SL MP Copy RLC Activation / Deactivation MAC CE in the SL from the gNB via the relay UE; or

[0463] o For this reception in the remote UE, when the relay UE receives the MP replication RLC activation / deactivation MAC CE in DL from the gNB, the relay UE replicates and relays the MP replication activation / deactivation MAC CE to be sent in the SL.

[0464] - Each RLC entity and / or PDCP entity activating or deactivating MP split bearers is instructed by RRC message indirectly via relaying UE or directly from gNB.

[0465] PDCP duplication for all or a subset of the associated RLC entities of the configured RBs is activated and deactivated in the remote UE in the following manner:

[0466] - Receive DL MP replicated RLC Activation / Deactivation MAC CE directly from the gNB; or

[0467] - Indirect reception of SL MP replicated RLC Activation / Deactivation MAC CE from gNB via relay UE;

[0468] - Each RLC entity that activates or deactivates MP split bearers is instructed by an RRC message either indirectly via the relaying UE or directly from the gNB.

[0469] DL MP replication activation / deactivation MAC CE

[0470] Fig.19 The DL MP duplication activation / deactivation MAC CE to be carried in the MAC PDU on the DL-SCH is illustrated.

[0471] The one-octet DL MP Duplicate Activation / Deactivation MAC CE is identified by the MAC subheader with the specific LCID value of the MAC PDU on the DL-SCH. It has a fixed size and consists of a single octet containing eight D fields. The Duplicate Activation / Deactivation MAC CE is defined for the MAC entity as follows Fig.19 shown.

[0472] -Di: This field indicates the activation / deactivation status of PDCP duplication for RB i, where i is in ascending order of RB ID among the MP split RBs configured with PDCP duplication and the RLC entity associated with this MAC entity. The Di field is set to 1 to indicate that PDCP duplication for RB i should be activated. The Di field is set to 0 to indicate that PDCP duplication for RB i should be deactivated.

[0473] -UE ID: This field indicates the local identity of the U2N remote UE, which can be the same UE ID configured with the SRAP entity for MP split bearer.

[0474] SL MP replication activation / deactivation MAC CE

[0475] Fig. 20 The SL MP duplication activation / deactivation MAC CE to be carried in the MAC PDU on the SL-SCH is illustrated.

[0476] The one-octet SL MP Duplicate Activation / Deactivation MAC CE is identified by the MAC subheader with the specific LCID value of the MAC PDU on the SL-SCH. It has a fixed size and consists of a single octet containing eight D fields. The Duplicate Activation / Deactivation MAC CE is defined for the MAC entity as follows Fig. 20 shown.

[0477] Di: This field indicates the activation / deactivation status of PDCP duplication for RB i, where i is in ascending order of RB ID among the MP split RBs configured with PDCP duplication and the RLC entity associated with this MAC entity of the remote UE. The Di field is set to 1 to indicate that PDCP duplication for RB i should be activated. The Di field is set to 0 to indicate that PDCP duplication for RB i should be deactivated.

[0478] If the remote UE receives the SL MP duplication activation / deactivation MAC CE on the SL-SCH via the PC5 unicast link with the relay UE, the remote UE activates or deactivates the PDCP duplication of the corresponding PDCP entity associated with RB i of the MP split bearer type.

[0479] DL MP copy RLC activation / deactivation MAC CE

[0480] Fig.21 : DL MP duplicate RLC activation / deactivation MAC CE to be carried in MAC PDU on DL-SCH.

[0481] The duplicate RLC activation / deactivation MAC CE is identified by a MAC subheader with a specific LCID value of the MAC PDU on the DL SCH. It has a fixed size and is represented by Fig.21 It consists of a single octet as defined in .

[0482] -RB ID: This field indicates the identifier of the RB in the MP split bearer to which the MAC CE is applied. The length of this field is 5 bits;

[0483] - Path Type (or Path ID): This field indicates a 5-bit identifier of a path among a direct path and an indirect path, or a 1-bit indication of one of the direct path and the indirect path to which the MAC CE is applied. The length of this field is 1 bit or 5 bits;

[0484] o If more than one bit is configured (e.g., 5 bits), this field indicates one of multiple paths configured for the remote UE. For example, the remote UE may be configured with more than one direct path and / or more than one indirect path. Different direct paths are associated with different gNBs or cells, and different indirect paths are associated with different relay UEs and / or different gNBs / cells serving relay UEs for the remote UE. In this case, each of the direct and indirect paths is identified by a path ID, which may replace the path ID. Fig.21 The path type field in .

[0485] o If one bit is configured, this field indicates the direct path or indirect path to the remote UE.

[0486] o Alternatively, the path type field may be replaced by a cell ID or UL / SL BWP ID for UL / DL or a cell group ID for a specific path or a specific path type.

[0487] - RLCi: This field indicates the activation / deactivation status of the PDCP duplication for the secondary RLC entity i, where i is in ascending order of the logical channel ID of the secondary RLC entity (for RBs, in order of direct path and indirect path and vice versa).

[0488] o Alternatively, this field indicates the activation / deactivation status of PDCP replication for the primary RLC entity and the secondary RLC entity i, where i is in ascending order of the logical channel IDs of the primary RLC entity and the secondary RLC entity, and for RBs, in the order of the primary RLC entity and the secondary RLC entity (or vice versa).

[0489] o Alternatively, this field indicates the activation / deactivation status of the PDCP replication for the UL RLC entity and the SL RLC entity i, where i is in ascending order of the UL logical channel ID of the UL RLC entity and the SL logical channel ID of the SL RLC entity, in the order of the UL RLC entity and the SL RLC entity (or vice versa) for the RB.

[0490] o Note that different secondary RLC entities may be configured on both the direct and indirect paths or both the primary and secondary paths of MP operation.

[0491] o The RLCi field is set to 1 to indicate that PDCP duplication for RLC entity i should be activated. The RLCi field is set to 0 to indicate that PDCP duplication for RLC entity i should be deactivated.

[0492] -UE ID: This field indicates the local identity of the U2N remote UE, which can be the same UE ID configured with the SRAP entity for MP split bearer.

[0493] SL MP copies RLC to activate / deactivate MAC CE

[0494] Fig. 22 The SL copy RLC activation / deactivation MAC CE to be carried in the MAC PDU on the SL-SCH is illustrated.

[0495] The SL MP duplicate RLC activation / deactivation MAC CE is identified by a MAC subheader with a specific LCID value of the MAC PDU on the SL SCH. It has a fixed size and is represented by Fig. 22 It consists of a single octet as defined in .

[0496] -RB ID: This field indicates the identifier of the RB in the MP split bearer to which the MAC CE is applied. The length of this field is 5 bits;

[0497] - Path Type (or Path ID): This field indicates a 5-bit identifier of a path among a direct path and an indirect path, or a 1-bit indication of one of the direct path and the indirect path to which the MAC CE is applied. The length of this field is 1 bit or 5 bits;

[0498] o If more than one bit is configured (e.g., 5 bits), this field indicates one of multiple paths configured for the remote UE. For example, the remote UE may be configured with more than one direct path and / or more than one indirect path. Different direct paths are associated with different gNBs or cells, and different indirect paths are associated with different relay UEs and / or different gNBs / cells serving relay UEs for the remote UE. In this case, each of the direct and indirect paths is identified by a path ID, which may replace the path ID. Fig. 22 The path type field in .

[0499] o If one bit is configured, this field indicates the direct path or indirect path to the remote UE.

[0500] o Alternatively, the path type field may be replaced by a cell ID or UL / SL BWP ID for UL / DL or a cell group ID for a specific path or a specific path type.

[0501] - RLCi: This field indicates the activation / deactivation status of the PDCP duplication for the secondary RLC entity i, where i is in ascending order of the logical channel ID of the secondary RLC entity (for RBs, in order of direct path and indirect path and vice versa).

[0502] o Alternatively, this field indicates the activation / deactivation status of PDCP replication for the primary RLC entity and the secondary RLC entity i, where i is in ascending order of the logical channel IDs of the primary RLC entity and the secondary RLC entity, and for RBs, in the order of the primary RLC entity and the secondary RLC entity (or vice versa).

[0503] o Alternatively, this field indicates the activation / deactivation status of the PDCP replication for the UL RLC entity and the SL RLC entity i, where i is in ascending order of the UL logical channel ID of the UL RLC entity and the SL logical channel ID of the SL RLC entity, in the order of the UL RLC entity and the SL RLC entity (or vice versa) for the RB.

[0504] o Note that different secondary RLC entities may be configured on both the direct and indirect paths or both the primary and secondary paths of MP operation.

[0505] o The RLCi field is set to 1 to indicate that PDCP duplication for RLC entity i should be activated. The RLCi field is set to 0 to indicate that PDCP duplication for RLC entity i should be deactivated.

[0506] DL MP dynamic path switching MAC CE

[0507] Fig.23 The DL MP Dynamic Path Switching MAC CE to be carried in the MAC PDU on the DL-SCH is illustrated.

[0508] The MP dynamic path switching MAC CE is identified by a MAC subheader with a specific LCID value of the MAC PDU on the DL SCH. It has a fixed size and is represented by Fig.23 It consists of a single octet as defined in .

[0509] -RB ID: This field indicates the identifier of the RB in the MP split bearer to which the MAC CE is applied. The length of this field is 5 bits;

[0510] - Path Type (or Path ID): This field indicates a 5-bit identifier of a path among a direct path and an indirect path, or a 1-bit indication of one of the direct path and the indirect path to which the MAC CE is applied. The length of this field is 1 bit or 5 bits;

[0511] o If more than one bit is configured (e.g., 5 bits), this field indicates one of multiple paths configured for the remote UE. For example, the remote UE may be configured with more than one direct path and / or more than one indirect path. Different direct paths are associated with different gNBs or cells, and different indirect paths are associated with different relay UEs and / or different gNBs / cells serving relay UEs for the remote UE. In this case, each of the direct and indirect paths is identified by a path ID, which may replace the path ID. Fig.23 The path type field in .

[0512] o If one bit is configured, this field indicates the direct path or indirect path to the remote UE.

[0513] o Alternatively, the path type field may indicate a cell ID or UL / SL BWP ID for UL / DL or a cell group ID for a specific path or a specific path type (eg, primary path or secondary path or direct path or indirect path).

[0514] - RLCi: This field indicates the activation / deactivation status of the RLC entity i, where i is in ascending order of the logical channel IDs of the RLC entities (in order of direct path and indirect path for RBs and vice versa).

[0515] o Alternatively, this field indicates the activation / deactivation status of the primary RLC entity and / or secondary RLC entity i, where i is in ascending order of the logical channel IDs of the primary RLC entity and the secondary RLC entity, and for RBs, in the order of the primary RLC entity and the secondary RLC entity (or vice versa).

[0516] o Alternatively, this field indicates the activation / deactivation status of the UL RLC entity and / or SL RLC entity i, where i is in ascending order of the UL logical channel ID of the UL RLC entity and the SL logical channel ID of the SL RLC entity, and for the RB, in the order of the UL RLC entity and the SL RLC entity (or vice versa).

[0517] o Note that different secondary RLC entities may be configured on both the direct and indirect paths or both the primary and secondary paths of MP operation.

[0518] o The RLCi field is set to 1 to indicate that RLC entity i should be activated. The RLCi field is set to 0 to indicate that RLC entity i should be deactivated.

[0519] o Alternatively, if only the RLC entity is configured for the primary path or direct path, RLC 0 (i.e., i=0) is used to indicate activation or deactivation of the RLC entity for the primary path or direct path. The RLC i field (i>0) is used to indicate activation or deactivation of the RLC entity for the secondary path or indirect path.

[0520] SL MP dynamic path switching MAC CE

[0521] Fig.24 The SL MP dynamic path switching MAC CE to be carried in the MAC PDU on the SL-SCH is illustrated.

[0522] The MP dynamic path switching MAC CE is identified by a MAC subheader with a specific LCID value of the MAC PDU on the SL SCH. It has a fixed size and is represented by Fig.24 It consists of a single octet as defined in .

[0523] -RB ID: This field indicates the identifier of the RB in the MP split bearer to which the MAC CE is applied. The length of this field is 5 bits;

[0524] - Path Type (or Path ID): This field indicates a 5-bit identifier of a path among a direct path and an indirect path, or a 1-bit indication of one of the direct path and the indirect path to which the MAC CE is applied. The length of this field is 1 bit or 5 bits;

[0525] o If more than one bit is configured (e.g., 5 bits), this field indicates one of multiple paths configured for the remote UE. For example, the remote UE may be configured with more than one direct path and / or more than one indirect path. Different direct paths are associated with different gNBs or cells, and different indirect paths are associated with different relay UEs and / or different gNBs / cells serving relay UEs for the remote UE. In this case, each of the direct and indirect paths is identified by a path ID, which may replace the path ID. Fig.24 The path type field in .

[0526] o If one bit is configured, this field indicates the direct path or indirect path to the remote UE.

[0527] o Alternatively, the path type field may indicate a cell ID or UL / SL BWP ID for UL / DL or a cell group ID for a specific path or a specific path type (eg, primary path or secondary path or direct path or indirect path).

[0528] - RLCi: This field indicates the activation / deactivation status of the RLC entity i, where i is in ascending order of the logical channel IDs of the RLC entities (in order of direct path and indirect path for RBs and vice versa).

[0529] o Alternatively, this field indicates the activation / deactivation status of the primary RLC entity and / or secondary RLC entity i, where i is in ascending order of the logical channel IDs of the primary RLC entity and the secondary RLC entity, and for RBs, in the order of the primary RLC entity and the secondary RLC entity (or vice versa).

[0530] o Alternatively, this field indicates the activation / deactivation status of the UL RLC entity and / or SL RLC entity i, where i is in ascending order of the UL logical channel ID of the UL RLC entity and the SL logical channel ID of the SL RLC entity, and for the RB, in the order of the UL RLC entity and the SL RLC entity (or vice versa).

[0531] o Note that different secondary RLC entities may be configured on both the direct and indirect paths or both the primary and secondary paths of MP operation.

[0532] o The RLCi field is set to 1 to indicate that RLC entity i should be activated. The RLCi field is set to 0 to indicate that RLC entity i should be deactivated.

[0533] o Alternatively, if only the RLC entity is configured for the primary path or direct path, RLC 0 (i.e., i=0) is used to indicate activation or deactivation of the RLC entity for the primary path or direct path. The RLC i field (i>0) is used to indicate activation or deactivation of the RLC entity for the secondary path or indirect path.

[0534] Dynamic path switching MAC CE and PDCP duplication activation / deactivation in remote UE and relay UE

[0535] If the direct path is configured as the primary path for MP operation and / or if the direct path is not deactivated and / or if the indirect path is deactivated or a link failure occurs, then

[0536] - The gNB may send MP duplication activation / deactivation MAC CE and / or MP duplication RLC activation / deactivation MAC CE only through direct path, i.e., the remote UE receives the MP duplication activation / deactivation MAC CE and / or MP duplication RLC activation / deactivation MAC CE in DL.

[0537] Otherwise, if the indirect path is configured as the primary path for MP operation and / or if the indirect path is not deactivated and / or if the direct path is deactivated or a link failure occurs, then

[0538] - The gNB may send the MP replication activation / deactivation MAC CE and / or the MP replication RLC activation / deactivation MAC CE by using an indirect path via the relay UE only, i.e., the remote UE receives the MP replication activation / deactivation MAC CE and / or the MP replication RLC activation / deactivation MAC CE in the SL from the relay UE.

[0539] If the remote UE receives a DL MP duplication activation / deactivation MAC CE on the DL-SCH, the remote UE activates or deactivates PDCP duplication of the corresponding PDCP entity associated with RB i of the MP split bearer type.

[0540] If the remote UE receives a DL MP duplication RLC activation / deactivation MAC CE on the DL-SCH, the remote UE activates or deactivates PDCP duplication of the corresponding PDCP entity for the RLC entity associated with RLC i of the MP split bearer type.

[0541] If a relay UE receives a DL MP replication activation / deactivation MAC CE and / or a DL MP replication RLC activation / deactivation MAC CE on the DL-SCH, which may or may not have a UE ID that is the same as the local identity of the U2N remote UE configured for the SRAP entity of the MP split bearer, the relay UE forwards the received MAC CE to the remote UE corresponding to the UE ID by using a SL MP replication activation / deactivation MAC CE and / or a SL MP replication RLC activation / deactivation MAC CE, which is a copy of the received DL MP replication activation / deactivation MAC CE and / or a copy of the received DL MP replication RLC activation / deactivation MAC CE, respectively. Depending on whether more than one remote UE is configured for the relay UE, the UE ID field may be optionally included in the MAC CE. If more than one remote UE is configured for the relay UE, the gNB configures the UE ID field for the relay UE. If only one remote UE is configured for relay UE, the gNB does not configure the UE ID field for the relay UE. For this MAC CE, the MAC entity of the relay UE relays the MAC CE received from the gNB in ​​DL to the remote UE at MAC level.

[0542] In addition, the gNB may activate one or more RLC entities associated with the PDCP entity for the MP split bearer by sending an MP dynamic path switching MAC CE to the remote UE indirectly or directly via the relay UE.

[0543] Alternatively, the MP dynamic path switching MAC CE can only be used to activate one RLC entity. In this case, if more than one RLC entity is activated, the gNB sends an MP replication activation / deactivation MAC CE and / or an MP replication RLC activation / deactivation MAC CE to the remote UE.

[0544] If the remote UE receives a DL MP dynamic path switching MAC CE on the DL-SCH, the remote UE activates the RLC entity associated with the RLC i of the MP split bearer type. If only one RLC entity is activated based on the MAC CE, the PDCP duplication of the corresponding PDCP entity associated with the RLC entity is not activated. If more than one RLC entity is activated based on the MAC CE, the PDCP duplication of the corresponding PDCP entity associated with the RLC entity is activated.

[0545] If a relay UE receives a DL MP dynamic path switching MAC CE on the DL-SCH, which may or may not have a UE ID that is the same as the local identity of the U2N remote UE configured by the SRAP entity for MP split bearer, the relay UE forwards the received MAC CE to the remote UE corresponding to the UE ID by using the SL MP dynamic path switching MAC CE, which is a copy of the received DL MP dynamic path switching MAC CE. Depending on whether more than one remote UE is configured for the relay UE, the UE ID field may be optionally included in the MAC CE. If more than one remote UE is configured for the relay UE, the gNB configures the UE ID field for the relay UE. If only one remote UE is configured for the relay UE, the gNB does not configure the UE ID field for the relay UE. For this MAC CE, the MAC entity of the relay UE relays the MAC CE received from the gNB in ​​the DL to the remote UE at the MAC level.

[0546] The MAC entity of the remote UE triggers the activation of RLC entities or activation of PDCP duplication for a subset or all of the associated RLC entities of the configured RBs of the MP split bearer type in the following manner:

[0547] - receiving a specific uplink grant, e.g. addressed to a CS-RNTI with NDI=1 or a C-RNTI with a specific value of a specific DCI field of a logical channel associated with a DRB (or SRB) configured with specific parameters by the gNB; or

[0548] - receiving a specific sidelink grant, e.g. addressed to a SLCS-RNTI with NDI=1 or a C-RNTI with a specific value of a specific DCI field of a logical channel associated with a SLRB or U2N RLC channel configured with specific parameters by the gNB; or

[0549] - receiving a MAC PDU carrying data from a logical channel associated with an RB configured with specific parameters, wherein the MAC PDU is stored in a HARQ buffer for a corresponding HARQ process:

[0550] Whether to activate only one RLC entity, a subset of associated RLC entities or all associated RLC entities for configured RBs of the MP split bearer type may be configured for the remote UE through the received RRC message.

[0551] For each MP split RB configured with or without PDCP duplication, the MAC entity shall:

[0552] 1> If the MP dynamic path switching MAC CE of the RLC entity that activates the RB is received:

[0553] 2> Indicate the activation of the RLC entity of the RB to the PDCP / RLC entity of the RB configured for MP split bearer type

[0554] 1> If the MP dynamic path switching MAC CE of the RLC entity that deactivates the RB is received:

[0555] 2> Indicate the deactivation of the RLC entity of the RB to the PDCP / RLC entity of the RB configured for the MP split bearer type

[0556] 1> If, as a result of activating or deactivating the above RLC entity, PDCP duplication is activated or deactivated for the PDCP entity associated with the above RLC entity:

[0557] 2> Indicate the activation or deactivation of the PDCP duplication of the PDCP entity to the PDCP / RLC entity of the RB configured for the MP split bearer type.

[0558] Note that when more than one RLC entity is activated in the above steps, the remote UE determines activation of PDCP duplication, and when only one RLC entity is activated or no RLC entity is activated in the above steps, the remote UE determines deactivation of PDCP duplication.

[0559] The MAC entity shall split the RB for each MP configured with PDCP duplication:

[0560] 1> If a duplicate activation / deactivation MAC CE of a PDCP copy of an activated RB is received:

[0561] 2> Indicate activation of PDCP duplication of RB to a subset of associated RLC entities or all associated RLC entities of RB configured for MP split bearer type

[0562] 1> If a duplicate activation / deactivation MAC CE of a PDCP duplicate of a deactivated RB is received:

[0563] 2> Indicate the deactivation of the PDCP duplication of the RB to a subset of the associated RLC entities or all the associated RLC entities of the RB configured for MP split bearer type.

[0564] 1> If a Duplicate RLC Activation / Deactivation MAC CE is received to activate PDCP replication for the associated RLC entity of the RB configured with PDCP replication:

[0565] 2> Indicate to the PDCP / RLC entity the activation of the PDCP duplication of the secondary RLC entity for the indication of the RB.

[0566] 1> If a Duplicate RLC Activation / Deactivation MAC CE is received to deactivate PDCP replication for the associated RLC entity of the RB configured with PDCP replication:

[0567] 2> Indicate to the PDCP / RLC entity the deactivation of the PDCP copy of the secondary RLC entity for the indication of the RB.

[0568] 1> If activation of PDCP duplication for all configured RLC entities is triggered for an RB:

[0569] 2> Indicate to the PDCP / RLC entity the activation of PDCP duplication for all configured RLC entities for the RB.

[0570] RRC message for configuring PDCP duplication and / or dynamic path switching

[0571] RRC messages can configure MP split bearer and PDCP duplication by using the following parameters in Table 6:

[0572] [Table 6]

[0573]

[0574]

[0575] The gNB may configure PDCP duplication or dynamic path switching for each PDCP entity, for all SRBs, for all DRBs for the primary path, for the secondary path, for the direct path, for the indirect path, for each relay UE, or for each remote UE.

[0576] PUCCH SR and prioritization for MAC CE

[0577] When the above MAC CE is sent in SL, the relay UE can request SL authorization by sending a PUCCH-based scheduling request or a SLBSR MAC CE. To this end, the gNB can allocate specific PUCCH resources configured in the PUCCH resource configuration for each, a subset, or all of the above SL MAC CEs. In this case, if the relay UE creates one or more of the above MAC CEs and does not have SL authorization for the contained MAC CE, the relay UE triggers a PUCCH SR. If the relay UE creates one or more of the above MAC CEs and has SL authorization for the contained MAC CE, the relay UE sends a SL BSR MAC CE requesting SL authorization for the MAC CE.

[0578] Alternatively, if the relay UE creates one or more of the above MAC CEs, the relay UE triggers a PUCCH SR to directly notify the gNB of the availability of the MAC CE regardless of whether the SL grant is available. In this case, the PUCCH SR does not trigger the SL BSR.

[0579] If the priority of MAC CE is higher than the highest priority of MAC PDU on the conflicting SL-SCH or UL-SCH, PUCCH SR takes precedence over the conflicting SL-SCH or UL-SCH. Otherwise, PUCCH SR takes precedence over the priority of the conflicting SL-SCH or UL-SCH.

[0580] If the priority of MAC CE is higher than the highest priority of other PUCCHs on SL-SCH or UL-SCH in conflict, PUCCH SR takes precedence over other PUCCHs in conflict. Otherwise, PUCCH SR takes precedence over other PUCCHs in conflict.

[0581] The priority of the above MAC CE is configured or pre-configured by the gNB or fixed by the specification.

[0582] When the relay UE includes the above MAC CE in a MAC PDU on the SL-SCH, i.e. during logical channel prioritization, the relay UE prioritizes the above MAC CE during creation of the MAC PDU according to the following order (highest priority listed first) in one of the alternatives:

[0583] 1) Alternative 1:

[0584] - one, more or all of the above MAC CEs;

[0585] - Data from SCCH;

[0586] -Sidelink CSI reporting MAC CE;

[0587] -Sidelink inter-UE coordination request MAC CE and sidelink inter-UE coordination information report MAC CE;

[0588] -Sidelink DRX Command MAC CE;

[0589] - Data from any STCH.

[0590] 2) Alternative 2:

[0591] - Data from SCCH;

[0592] - one, more or all of the above MAC CEs;

[0593] -Sidelink CSI reporting MAC CE;

[0594] - Sidelink inter-UE coordination request MAC CE and sidelink inter-UE coordination information report MAC CE; - Sidelink DRX command MAC CE;

[0595] - Data from any STCH.

[0596] 3) Alternative 3:

[0597] - Data from SCCH;

[0598] -Sidelink CSI reporting MAC CE;

[0599] - one, more or all of the above MAC CEs;

[0600] -Sidelink inter-UE coordination request MAC CE and sidelink inter-UE coordination information report MAC CE;

[0601] -Sidelink DRX Command MAC CE;

[0602] - Data from any STCH.

[0603] 4) Alternative 4:

[0604] - Data from SCCH;

[0605] -Sidelink CSI reporting MAC CE;

[0606] -Sidelink inter-UE coordination request MAC CE and sidelink inter-UE coordination information report MAC CE;

[0607] - one, more or all of the above MAC CEs;

[0608] -Sidelink DRX Command MAC CE;

[0609] - Data from any STCH.

[0610] 5) Alternative 5:

[0611] - Data from SCCH;

[0612] -Sidelink CSI reporting MAC CE;

[0613] -Sidelink inter-UE coordination request MAC CE and sidelink inter-UE coordination information report MAC CE;

[0614] -Sidelink DRX Command MAC CE;

[0615] - one, more or all of the above MAC CEs;

[0616] - Data from any STCH.

[0617] 6) Alternative 6:

[0618] - Data from SCCH;

[0619] -Sidelink CSI reporting MAC CE;

[0620] -Sidelink inter-UE coordination request MAC CE and sidelink inter-UE coordination information report MAC CE;

[0621] -Sidelink DRX Command MAC CE;

[0622] - Data from any STCH.

[0623] - one, more or all of the above MAC CEs;

[0624] Primary / Secondary Path Determination

[0625] If the remote UE supports multipath (MP) operation, the remote UE in RRC_IDLE or RRC_INACTIVE sends an RRC request message or an RRC recovery request message to the gNB directly or indirectly via the relay UE. The remote UE receives an RRC establishment message in response to the RRC request message or an RRC recovery message in response to the RRC recovery request message from the gNB directly or indirectly via the relay UE.

[0626] In this case, the remote UE selects the direct path or the indirect path as the primary path for MP operation according to one of the following options:

[0627] - Option 1: The remote UE regards the path for sending the RRC SETUP REQUEST message or the RRC RESUMPTION REQUEST message as the primary path for the MP operation.

[0628] - Option 2: The remote UE regards the path on which the RRC setup message or the RRC resume message is received as the primary path for the MP operation.

[0629] - Option 3: The remote UE considers the path indicated by the gNB as the primary path for MP operation

[0630] o Option 3-1: The indication is included in the configuration of the primary path contained in the RRC Setup message or the RRC Resume message.

[0631] o Option 3-2: The indication is included in the DCI or MAC CE received directly from the gNB in ​​the DL.

[0632] o Option 3-3: The indication is included in the DCI or MAC CE received indirectly from the gNB via the relay UE.

[0633] o Option 3-4: The indication is included in the DCI or MAC CE received from the relay UE in the SL.

[0634] If the remote UE receives the multipath (MP) operation to an RRC reconfiguration message for reconfiguring a direct path or an indirect path or both paths (e.g., for mobility or handover), then after receiving and / or performing the RRC reconfiguration, the remote UE sends an RRC reconfiguration complete message to the gNB directly or indirectly via the relay UE.

[0635] - Option 1: The remote UE considers the path that is not reconfigured by the RRC reconfiguration message as the primary path for MP operation.

[0636] - Option 2: The remote UE considers the path reconfigured by the RRC reconfiguration message as the primary path for MP operation.

[0637] - Option 3: The remote UE considers the path indicated by the cell of the gNB as the primary path for MP operation

[0638] o Option 3-1: The indication is included in the configuration of the primary path contained in the RRC reconfiguration message.

[0639] o Option 3-2: The indication is included in the DCI or MAC CE received directly from the gNB in ​​the DL.

[0640] o Option 3-3: The indication is included in the DCI or MAC CE received indirectly from the gNB via the relay UE.

[0641] o Option 3-4: The indication is included in the DCI or MAC CE received from the relay UE in the SL.

[0642] - In the above options,

[0643] o A gNB can be a source gNB or a target gNB for mobility or handover.

[0644] o A cell can be a source cell or a target cell for mobility or handover.

[0645] o A cell can be a cell of an indirect path or a cell of a direct path for mobility or handover.

[0646] o The remote UE may change from the serving cell of the direct path to a new cell of the direct path through reconfiguration of the direct path.

[0647] o The remote UE may change from the serving relay UE of the indirect path to the new relay UE of the indirect path through reconfiguration of the indirect path.

[0648] o The remote UE may change from the cell serving the serving relay UE of the indirect path to a new cell serving the same relay UE of the indirect path through reconfiguration of the indirect path.

[0649] If the remote UE has been configured with multi-path (MP) operation, after initiating the RRC re-establishment procedure, the remote UE sends an RRC re-establishment request message to the gNB directly or indirectly via the relay UE. The remote UE receives an RRC re-establishment message in response to the RRC re-establishment request message from the gNB directly or indirectly via the relay UE.

[0650] In this case, after completing the RRC re-establishment procedure or after receiving the RRC re-establishment message, the remote UE selects the direct path or the indirect path as the primary path for MP operation according to one of the following options:

[0651] - Option 1: The remote UE considers the path for sending the RRC Reestablishment Request message as the primary path for MP operation.

[0652] - Option 2: The remote UE regards the path on which the RRC re-establishment message is received as the primary path for MP operation.

[0653] - Option 3: The remote UE considers the path indicated by the gNB as the primary path for MP operation

[0654] o Option 3-1: The indication is included in the configuration of the primary path contained in the RRC Reestablishment message.

[0655] o Option 3-2: The indication is included in the DCI or MAC CE received directly from the gNB in ​​the DL.

[0656] o Option 3-3: The indication is included in the DCI or MAC CE received indirectly from the gNB via the relay UE.

[0657] o Option 3-4: The indication is included in the DCI or MAC CE received from the relay UE in the SL.

[0658] A remote UE configured with multi-path (MP) operation may configure security keys for each of direct bearers, indirect bearers, and MP split bearers. The security keys are used to encrypt and decrypt data units in each PDCP entity.

[0659] In this application, the primary path may correspond to one or more of the following:

[0660] A. The primary path is the path by which the remote UE initially establishes the RRC connection.

[0661] B. The primary path is the path over which the remote UE has reestablished the RRC connection.

[0662] C. The primary path is the path indicated by the gNB for the remote UE during mobility.

[0663] D. The primary path is the path configured on the PCell of the remote UE.

[0664] - If the primary path is an indirect path, the PCell of the remote UE is the same as the PCell of the relay UE.

[0665] - Note: The direct path and the indirect path may be served by different cells as agreed in RAN2#119-e or by the same cell (ie, PCell).

[0666] E. The primary path is the path indicated by the gNB as the primary path.

[0667] E. The primary path is the path used as the AS security anchor.

[0668] G. The primary path is the path through which the remote UE obtains system information.

[0669] H. The primary path is the path through which remote UEs exchange NAS messages.

[0670] The remote UE is configured with a first security key for a direct bearer and a second security key for an indirect bearer. The MP split bearer may always be configured with a first security key (i.e., the same key as the direct bearer). Or the MP split bearer may always be configured with a second security key (i.e., the same key as the indirect bearer). Or, based on the configuration, the MP split bearer may be configured with either the first security key or the second security key. The second security key is derived from the first security key.

[0671] Each PDCP entity of the remote UE encrypts or decrypts the data unit based on the first security key or the second security key based on the type of bearer (i.e., direct bearer, indirect bearer, or MP split bearer). Direct bearer, indirect bearer, or MP split bearer can be used for signaling radio bearer (SRB) and data radio bearer (DRB).

[0672] For MP split RB, if the transmitting PDCP entity of the remote UE is associated with at least two RLC entities:

[0673] - If PDCP duplication is activated for RB:

[0674] - If the PDCP PDU is a PDCP data PDU:

[0675] o The remote UE replicates the PDCP data PDUs and submits the PDCP data PDUs to the associated RLC entity activated for PDCP duplication;

[0676] -otherwise:

[0677] o Submit PDCP control PDUs to the primary RLC entity;

[0678] - Otherwise (i.e., PDCP duplication is deactivated for the RB, or the RB is a DAPS bearer):

[0679] oThe remote UE performs one of the following options:

[0680] 1) Option 1: Configure separate thresholds mp-DataSplitThreshold and ul-DataSplitThreshold for MP split bearer and traditional DC / CA split bearer.

[0681] o if split secondary RLC entity is configured; and

[0682] o If the total amount of PDCP data and RLC data awaiting initial transmission in the primary RLC entity and the split secondary RLC entity (as specified in TS 38.322 [5]) is equal to or greater than the mp-DataSplitThreshold or ul-DataSplitThreshold configured for the RB, then: the transmitting PDCP entity submits the PDCP PDU to the primary RLC entity or the split secondary RLC entity;

[0683] o Otherwise, the transmitting PDCP entity submits the PDCP PDU to the primary RLC entity.

[0684] 2) Option 2: Configure separate thresholds primary-DataSplitThreshold and secondary-DataSplitThreshold for the primary path and secondary path of the MP split bearer.

[0685] o if the split secondary RLC entity is configured for MP operation; and

[0686] o If the total amount of PDCP data and the amount of RLC data awaiting initial transmission in the primary RLC entity for the MP split RB (as specified in TS 38.322 [5]) is equal to or greater than primary-DataSplitThreshold, then: the transmitting PDCP entity submits the PDCP PDU to the primary RLC entity or the split secondary RLC entity;

[0687] o Otherwise, if the total amount of PDCP data and the amount of RLC data awaiting initial transmission in the split secondary RLC entity for the MP split RB (as specified in TS 38.322 [5]) is equal to or greater than secondary-DataSplitThreshold, then: the transmitting PDCP entity submits the PDCP PDU to the primary RLC entity or the split secondary RLC entity;

[0688] o Otherwise, the transmitting PDCP entity submits the PDCP PDU to the primary RLC entity.

[0689] 3) Option 3: Only the PDCP data amount (ie, not the RLC data amount) is compared with the threshold.

[0690] o if the split secondary RLC entity is configured for MP operation; and

[0691] o If the total amount of PDCP data awaiting initial transmission in the PDCP entity for the MP split RB is equal to or greater than the mp-DataSplitThreshold or ul-DataSplitThreshold configured for the RB, then: the transmitting PDCP entity submits the PDCP PDU to the primary RLC entity or the split secondary RLC entity;

[0692] o Otherwise, the transmitting PDCP entity submits the PDCP PDU to the primary RLC entity.

[0693] 4) Option 4: Configure separate thresholds direct-DataSplitThreshold and indirect-DataSplitThreshold for the direct path and indirect path of the MP split bearer.

[0694] o if the split secondary RLC entity is configured for MP operation; and

[0695] o If the total amount of PDCP data and the amount of RLC data awaiting initial transmission in the RLC entities associated with the direct path of the MP split RB (as specified in TS 38.322 [5]) is equal to or greater than direct-DataSplitThreshold, then: the transmitting PDCP entity submits the PDCP PDU to the primary RLC entity or the split secondary RLC entity;

[0696] o Otherwise, if the total amount of PDCP data and the amount of RLC data awaiting initial transmission in the RLC entities associated with the indirect path of the MP split RB (as specified in TS 38.322 [5]) is equal to or greater than indirect-DataSplitThreshold, then: the transmitting PDCP entity submits the PDCP PDU to the primary RLC entity or the split secondary RLC entity;

[0697] o Otherwise, the transmitting PDCP entity submits the PDCP PDU to the primary RLC entity.

[0698] 5) Option 5: Compare the amount of data on only the direct path to a threshold.

[0699] o if split secondary RLC entity is configured; and

[0700] o If the total amount of PDCP data and RLC data awaiting initial transmission in the RLC entity (or all RLC entities) associated with the direct path of the MP split RB (as specified in TS 38.322 [5]) is equal to or greater than the mp-DataSplitThreshold or ul-DataSplitThreshold configured for that RB, then: the transmitting PDCP entity submits the PDCP PDU to the primary RLC entity or the split secondary RLC entity;

[0701] o Otherwise, the transmitting PDCP entity submits the PDCP PDU to the primary RLC entity.

[0702] 6) Option 6: Compare the amount of data on only the indirect path to a threshold.

[0703] o if split secondary RLC entity is configured; and

[0704] o If the total amount of PDCP data and RLC data awaiting initial transmission in the RLC entity (or all RLC entities) associated with the indirect path of the MP split RB (as specified in TS 38.322 [5]) is equal to or greater than the mp-DataSplitThreshold or ul-DataSplitThreshold configured for that RB, then: the transmitting PDCP entity submits the PDCP PDU to the primary RLC entity or the split secondary RLC entity;

[0705] o Otherwise, the transmitting PDCP entity submits the PDCP PDU to the primary RLC entity.

[0706] 7) Option 7: Compare the amount of data on only the primary path with a threshold.

[0707] o if split secondary RLC entity is configured; and

[0708] o If the total amount of PDCP data and RLC data awaiting initial transmission in the primary RLC entity of an MP split RB (as specified in TS 38.322 [5]) is equal to or greater than the mp-DataSplitThreshold or ul-DataSplitThreshold configured for that RB, then: the transmitting PDCP entity submits the PDCP PDU to the primary RLC entity or split secondary RLC entity;

[0709] o Otherwise, the transmitting PDCP entity submits the PDCP PDU to the primary RLC entity.

[0710] 8) Option 8: Compare the amount of data on only the secondary path with a threshold.

[0711] o if split secondary RLC entity is configured; and

[0712] o If the total amount of PDCP data and RLC data awaiting initial transmission in the split secondary RLC entity (or all split secondary RLC entities) of the MP split RB (as specified in TS 38.322 [5]) is equal to or greater than the mp-DataSplitThreshold or ul-DataSplitThreshold configured for that RB, then: the transmitting PDCP entity submits the PDCP PDU to the primary RLC entity or the split secondary RLC entity;

[0713] o Otherwise, the transmitting PDCP entity submits the PDCP PDU to the primary RLC entity.

[0714] Problem 1: Path addition / modification / release

[0715] Question 1 is related to what situations can or cannot be supported for Scenario 1 and Scenario 2, as shown in Items 1-1 and 1-2.

[0716] (1) Item 1-1: Are all of the following MP situations supported in Scenario 1? If not, which situation should be excluded in Scenario 1?

[0717] A. Only remote UEs configured on the direct path add the indirect path under the same gNB;

[0718] B. Remote UEs configured only on indirect paths add direct paths under the same gNB;

[0719] C. A remote UE configured with multiple paths releases the indirect path;

[0720] D. A remote UE configured with multiple paths releases the direct path;

[0721] E. A remote UE configured with multiple paths changes the serving cell for the remote UE for the direct path while keeping the serving relay UE for the indirect path under the same gNB;

[0722] F. A remote UE configured with multiple paths maintains the serving relay UE for the indirect path and the serving cell of the remote UE for the direct path while the serving relay UE changes the serving cell of the relay UE under the same gNB;

[0723] G. A remote UE configured with multi-path changes to a new relay UE for an indirect path while keeping the direct path under the same gNB.

[0724] Depending on the implementation, all cases may be supported.

[0725] (2) Item 1-2: Are all MP conditions in Item 1-1 supported in Scenario 2? If not, then Scenario 2 should Which situation is excluded?

[0726] According to one embodiment, supported cases may include A to F, and excluded cases may include G. Assume that in scenario 2 the remote UE does not reselect the preconfigured relay UE.

[0727] Problem 2: Primary Path for the Control Plane

[0728] Question 2 concerns whether to introduce the concept of a main path and what aspects can be considered as characteristics of the main path for scenarios 1 and 2 as shown in items 1-1 and 1-2. If necessary, the considered characteristics of the main path can be used to define the main path and specify the main path.

[0729] In one embodiment, the concept of the primary path is proposed mainly for the control plane, while the other aspects address the primary RLC entity with the concept of the primary path (i.e., mainly for layer 2). Therefore, question 2 focuses on the control plane aspects of the primary path, while question 3 will address the primary RLC entity for layer 2.

[0730] (3) Item 2-1: Is the concept of primary path introduced in Scenario 1 from the CP perspective? If so, which part(s) of the following CP aspects can be considered as characteristics of the primary path?

[0731] A. The primary path is the path over which the remote UE initially established the RRC connection.

[0732] B. The primary path is the path over which the remote UE has reestablished the RRC connection.

[0733] C. The primary path is the path indicated by the gNB for the remote UE during mobility.

[0734] D. The primary path is the path configured on the PCell of the remote UE.

[0735] - If the primary path is an indirect path, the PCell of the remote UE is the same as the PCell of the relay UE.

[0736] - Note: The direct path and the indirect path may be served by the same cell (ie, PCell) or by different cells as agreed in RAN2#119-e.

[0737] E. The primary path is the path indicated by the gNB as the primary path.

[0738] F. The primary path is the path used as the AS security anchor.

[0739] G. The primary path is the path through which the remote UE obtains system information.

[0740] H. The primary path is the path through which remote UEs exchange NAS messages.

[0741] In one embodiment, the concept of a primary path may be supported, and the characteristics considered may include A to F.

[0742] (4) Item 2-2: Is the concept of the main path introduced in Scenario 2? If so, which part(s) of the above aspects can be regarded as the characteristics of the main path?

[0743] In one embodiment, the concept of a primary path may be supported, and the characteristics considered may include A to F.

[0744] In one embodiment, the direct path is configured as the primary path and the indirect path is configured as the secondary path, in Rel-18, the other case where the primary path is the indirect path and the secondary path is the direct path is deprioritized.

[0745] (5) Item 3-1: Options related to scenario 1 when configuring two paths

[0746] - Option 3A: Always configure the primary path over the direct path.

[0747] - Option 3B: Always configure a primary path over an indirect path.

[0748] - Option 3C: The primary path can be configured on a direct path or an indirect path.

[0749] - Option 3D: excludes Option 3B. Option 3A and Option 3C can be further studied.

[0750] (6) Item 3-2: Options related to scenario 2 when configuring two paths

[0751] - Option 3A: Always configure the primary path over the direct path.

[0752] - Option 3B: Always configure a primary path over an indirect path.

[0753] - Option 3C: The primary path can be configured on a direct path or an indirect path.

[0754] - Option 3D: excludes Option 3B. Option 3A and Option 3C can be further studied.

[0755] (7) Item 4-1: Options related to Scenario 1, if Yes in Item 2 (Note: SRB0 is not subject to this item)

[0756] - Option 4A: SRB1, SRB2, SRB3, and SRB4 can be configured on the primary path only.

[0757] - Option 4B: SRB1, SRB2, SRB3 and SRB4 may be configured on both the primary and secondary paths.

[0758] - Option 4C: Some SRBs may be configured only on the primary path, while other SRBs may be configured on both the primary and secondary paths. It may be further discussed which SRBs may be configured only on the primary path.

[0759] (8) Item 4-2: Options related to Scenario 2, if the answer is yes in Item 2 (Note: SRB0 does not comply with this option)

[0760] - Option 4A: SRB1, SRB2, SRB3, and SRB4 can be configured on the primary path only.

[0761] - Option 4B: SRB1, SRB2, SRB3 and SRB4 may be configured on both the primary and secondary paths.

[0762] - Option 4C: Some SRBs may be configured only on the primary path, while other SRBs may be configured on both the primary and secondary paths. It may be further discussed which SRBs may be configured only on the primary path.

[0763] Based on the existing split bearer framework, it is agreed to support MP split bearer as a bearer mapped to two paths. It can be further discussed whether MP split bearer can support SRB as well as DRB. In 38.331, it is specified that all MR-DC options for both SRB1 and SRB2 support split SRB (split SRB is not supported for SRB0 and SRB3).

[0764] (9) Item 5-1: In scenario 1, can MP split bearer be supported for SRBs? If so, which SRBs can be configured as MP split bearers?

[0765] For example, SRB1 and SRB2 can be configured as MP split bearers, the same as MR-DC.

[0766] (10) Item 5-2: In scenario 2, can MP split bearer be supported for SRB? If so, which SRB can be configured as MP split bearer?

[0767] For example, SRB1 and SRB2 can be configured as MP split bearers, the same as MR-DC.

[0768] In addition, considering the existing split bearer framework, one primary RLC entity and one split secondary RLC entity can be supported for each MP split bearer. If MP split bearer can be supported for SRB, it can be further discussed whether the primary RLC entity of the MP split bearer is always configured on the primary path of the control plane or can be configured on any path.

[0769] (11) Item 6-1: Options related to Scenario 1 (if the answer is yes in Item 5)

[0770] - Option 6A: The primary RLC entity for MP split bearer for SRB is always configured on the primary path of the control plane

[0771] - Option 6B: The primary RLC entity for the MP split bearer of the SRB may be configured on the primary path or the secondary path. For example, the primary RLC entity for the MP split bearer of the SRB may be reconfigured on the secondary path at least after detecting the RLF on the primary path.

[0772] (12) Item 6-2: Options related to Scenario 2 (if the answer is yes in Item 5)

[0773] - Option 6A: The primary RLC entity for MP split bearer for SRB is always configured on the primary path of the control plane

[0774] - Option 6B: The primary RLC entity for the MP split bearer of the SRB may be configured on the primary path or the secondary path. For example, the primary RLC entity for the MP split bearer of the SRB may be reconfigured on the secondary path at least after detecting the RLF on the primary path.

[0775] Problem 3: Layer 2

[0776] In section 5.2.1 of TS 38.323, if the transmitting PDCP entity is associated with at least two RLC entities, the UE may submit PDCP PDUs to the primary RLC entity or the split secondary RLC entity as follows:

[0777] - Otherwise, if the transmitting PDCP entity is associated with at least two RLC entities:

[0778] - If PDCP duplication is activated for RB:

[0779] - If the PDCP PDU is a PDCP data PDU:

[0780] - duplicate the PDCP data PDUs and submit the PDCP data PDUs to the associated RLC entity activated for PDCP duplication;

[0781] -otherwise:

[0782] - Submit PDCP control PDU to the primary RLC entity;

[0783] - Otherwise (i.e., PDCP duplication is deactivated for the RB, or the RB is a DAPS bearer):

[0784] - if split secondary RLC entity is configured; and

[0785] - If the total amount of PDCP data and RLC data awaiting initial transmission in the primary RLC entity and the split secondary RLC entity (as specified in TS 38.322 [5]) is equal to or greater than ul-DataSplitThreshold:

[0786] - Submitting PDCP PDU to the primary RLC entity or splitting the secondary RLC entity;

[0787] Considering the existing split bearer framework, one primary RLC entity and one split secondary RLC entity are supported for each MP split bearer. Assuming that MP split bearers can be supported for DRBs, it can be discussed whether the primary RLC entity for MP split bearers of DRBs is always configured on the primary path of the control plane or can be configured on any path.

[0788] (13) Item 7-1: Options related to Scenario 1 (if the answer is yes in Item 2)

[0789] - Option 7A: Always configure the primary RLC entity for MP split bearer for DRB on the primary path of the control plane

[0790] - Option 7B: The primary RLC entity for MP split bearer of DRB can be configured on the primary path or the secondary path.

[0791] (14) Item 7-2: Options related to Scenario 2 (if the answer is yes in Item 2)

[0792] - Option 7A: Always configure the primary RLC entity for MP split bearer for DRB on the primary path of the control plane

[0793] - Option 7B: The primary RLC entity for MP split bearer of DRB can be configured on the primary path or the secondary path.

[0794] (15) Item 9A: Does scenario 2 require an adaptation layer? Provide the reason why scenario 2 requires an adaptation layer.

[0795] For example, an adaptation layer is required to support data routing. For example, the relay UE and the remote UE configure multiple PDCP / RLC entities for multiple indirect / split bearers. Therefore, when the PDCP entity of the remote UE submits a PDCP PDU to the lower non-standard layers of the remote UE, the lower non-standard layers of the relay UE cannot identify which RLC entity of the relay UE needs to process the PDCP PDU received from the remote UE.

[0796] (16) Item 9B: Can the adaptation layer for scenario 2 be based on Rel-17 SRAP? What type of changes are expected compared to Rel-17 SRAP?

[0797] For example, the adaptation layer of scenario 2 can be designed based on the SRAP specification. However, the adaptation layer of scenario 2 does not need to understand / process the SL data unit. If the same SRAP is used for scenario 1 and scenario 2, the SRAP entities in scenario 1 and scenario 2 need to additionally understand the type of the lower layer (e.g., based on the header of the SRAP PDU (e.g., 3GPP SL or non-standard)). Since the adaptation layer of scenario 2 does not need to distinguish the type of the lower layer, the adaptation layer of scenario 2 can be a new thing.

[0798] Fig.25 The simultaneous establishment of direct / indirect paths in U2N-based RRC connection establishment is illustrated.

[0799] The method for UE to perform data transmission and reception includes the following steps:

[0800] 1. The U2N Remote UE and the U2N Relay UE perform a discovery procedure and establish a PC5-RRC connection using NR V2X procedures.

[0801] 2. After the PC5-RRC connection established with the PC5 unicast link is established, the remote UE and the relay UE may exchange their own UE capabilities by triggering the sidelink UE capability transmission procedure, in which the remote UE sends a UECapabilityEnquirySidelink message requesting the MP capability of the relay UE to the relay UE, and then the relay UE sends a UECapabilityInformationSidelink message including its MP capability to the remote UE. Afterwards, the relay UE may send a UECapabilityEnquirySidelink message requesting the MP capability of the remote UE to the remote UE, and then the remote UE sends a UECapabilityInformationSidelink message including its MP capability to the relay UE.

[0802] The MP capabilities of the UE may include one or more of the following:

[0803] -Whether the UE supports multipath operation as a remote UE and / or as a relay UE

[0804] -SL / UL / DL frequency carriers / bands where the UE may support MP operation for transmission and / or reception

[0805] - Combination of SL carrier / band and UL carrier / band where the UE can support MP operation for transmission from the UE

[0806] - Combination of SL carrier / band and DL carrier / band where the UE can support MP operation for reception at the UE

[0807] 3. If the remote UE and the relay UE are capable of supporting MP operation on the SL carrier and the DL / UL carrier of the serving cell, wherein sidelink transmission and / or sidelink reception between the remote UE and the relay UE has been performed on the SL carrier, or the serving cell supports sidelink resources for sidelink transmission / reception and / or MP operation (e.g., based on resource pool configuration in system information or dedicated signaling), the relay UE may determine a request for multipath operation and initiate RRC connection establishment, and / or the relay UE may notify the remote UE of the request for multipath operation, the RRC state of the relay UE, or whether the relay UE is in RRC_CONNECTED by sending a first sidelink message to the remote UE. If the relay UE (and the remote UE) determine a request for multipath operation, the first RRC message (i.e., RRCSetupRequest or RRCResumeRequest) in the RRC connection establishment from the relay UE may indicate to the gNB the request for multipath operation, for example, in EstablishmentCause or ResumeCause in the first RRC message. If the above conditions are met (and if the relay UE requests multipath operation), the remote UE may also notify the remote UE of the request for multipath operation, the RRC state of the remote UE, or whether the remote UE is in RRC_CONNECTED by sending a second side link message including the multipath operation request to the relay UE.

[0808] A. The first sidelink message may include one or more of the following:

[0809] -The cell identity of the PCell of the relay UE.

[0810] -The PLMN identity of the relay UE’s registered PLMN.

[0811] - Tracking area code of the tracking area that the relay UE has registered for the PCell.

[0812] -Multipath operation request

[0813] B. Upon receiving the first sidelink message, the remote UE may perform one or more of the following steps, such as cell reselection before or during RRC connection establishment from the remote UE, or cell reselection during or after RRC connection establishment from the relay UE:

[0814] -If the cell indicated by the relay UE is different from the serving cell on which the remote UE is camping, the remote UE may reselect to the indicated cell based on a cell reselection procedure, or the remote UE aborts configuration of multipath operation with the relay UE. If the remote UE cannot reselect to the indicated cell based on the cell reselection procedure, the remote UE aborts configuration of multipath operation with the relay UE.

[0815] -If the tracking area indicated by the relay UE is different from the tracking area with which the remote UE has registered, the remote UE may trigger a tracking area update procedure to register to the tracking area indicated by the relay UE, or the remote UE aborts the configuration of the multipath operation with the relay UE. If the remote UE cannot register to the indicated tracking area, for example due to a failure of the tracking area update procedure or other related NAS procedures, the remote UE aborts the configuration of the multipath operation with the relay UE.

[0816] -If the PLMN indicated by the relay UE is different from the PLMN with which the remote UE has registered, the remote UE may reselect to the PLMN indicated by the relay UE to register to the indicated PLMN, or the remote UE aborts the configuration of the multipath operation with the relay UE. If the remote UE cannot register to the indicated PLNN, for example due to a failure of the PLMN registration procedure or other related NAS procedures, the remote UE aborts the configuration of the multipath operation with the relay UE.

[0817] C. The first sidelink message may be a RemoteUEInformationSidelink message, a UEAssistanceInformationSidelink message, a RRCReconfigurationSidelink message, or a RRCReconfigurationCompleteSidelink message.

[0818] 4. If the relay UE identifies based on the above-mentioned sidelink UE capability exchange that both the relay UE and the remote UE support MP capabilities and the remote UE is not in RRC_CONNECTED, the remote UE may determine a request for multipath operation and initiate an RRC connection establishment procedure via the relay UE as follows:

[0819] If the U2N remote UE does not have a direct Uu RRC connection, the U2N remote UE sends a first RRC message (i.e., RRCSetupRequest or RRCResumeRequest) for its connection establishment with the gNB via the relay UE using the specified PC5 relay RLC channel configuration. If the remote UE (and the relay UE) determine a request for multipath operation, the first RRC message from the remote UE may indicate the request for multipath operation to the gNB, for example, in the EstablishmentCause or ResumeCause in the first RRC message. The remote UE may also indicate the request for multipath operation to the relay UE, for example, via the SCI of the PSSCH that schedules the first RRC message in the SL, via a separate SL MAC PDU or a SL MAC CE in the SL MAC PDU that includes the first RRC message in the SL, via the MAC (sub) header of the SL MAC PDU that includes the first RRC message in the SL, or via a separate PC5-RRC message sent to the relay UE.

[0820] 5. If the U2N relay UE is not in RRC_CONNECTED, it needs to perform its own connection establishment after receiving the message on the designated PC5 relay RLC channel. If the relay UE (and the remote UE) determine the request for multipath operation, the first RRC message (i.e., RRCSetupRequest or RRCResumeRequest) in the RRC connection establishment from the relay UE can indicate to the gNB the request for multipath operation, such as in the EstablishmentCause or ResumeCause in the first RRC message. During the RRC connection establishment process of the relay UE, the gNB can configure the SRB0 relay Uu relay RLC channel to the U2N relay UE by sending a second RRC message (e.g., RRCSetup message or RRCResume message) to the U2N relay UE.

[0821] A. If the relay UE and the remote UE are not configured with the same cell, or are not registered in the same tracking area and / or the same PLMN, the gNB may send a handover command to the relay UE via a second RRC message so that both the relay UE and the remote UE are located in the same cell, the same tracking area and / or the same PLMN.

[0822] 6. The gNB responds to the U2N remote UE via the U2N relay UE with a second RRC message (e.g., RRCSetup message or RRCResume message). The second RRC message is sent to the U2N remote UE using the SRB0 relay channel on Uu and the designated PC5 relay RLC channel on PC5.

[0823] A. If the relay UE and the remote UE are not configured with the same cell, or are not registered in the same tracking area and / or the same PLMN, the gNB may send a handover command to the remote UE via a second RRC message so that the relay UE and the remote UE are located in the same cell, the same tracking area and / or the same PLMN.

[0824] 7. If both the relay UE and the remote UE are in RRC_CONNECTED and if the gNB determines whether to add a direct path as well as an indirect path for the remote UE based on a request for multipath operation from the relay UE and / or the remote UE, the gNB configures the direct path for the remote UE, for example, via a second RRC message sent to the relay UE and the remote UE, respectively.

[0825] To add a direct path as well as an indirect path for a remote UE, the gNB may send a (first) RRCReconfiguration message to the relay UE and / or the remote UE after completing the RRC connection (re)establishment (and AS security activation) for the relay UE or the remote UE, as an alternative message to adding the direct path or as an additional message after the second message to add the direct path. If the gNB sends the RRCReconfiguration message to the remote UE, the message may be sent to the remote UE indirectly via the relay UE or directly on the Uu interface only.

[0826] - If the second RRC message to the relay UE includes sl-L2RelayUEConfig, the relay UE performs the L2 U2N relay UE configuration procedure to (re)configure zero, one or more direct bearers, zero, one or more indirect bearers and zero, one or more split bearers for uplink data from the remote UE and / or downlink data to the remote UE.

[0827] - If the second RRC message to the remote UE includes sl-L2RemoteUEConfig, the remote UE performs the L2 U2N Remote UE Configuration procedure to (re)configure zero, one or more direct bearers, zero, one or more indirect bearers and zero, one or more split bearers for the remote UE for uplink data from the remote UE and / or downlink data to the remote UE.

[0828] -If the second RRC message to the relay UE includes configuration of direct bearers and / or direct paths of split bearers, the remote UE (re)configures zero, one or more direct bearers and zero, one or more direct paths of split bearers for uplink data from the remote UE and / or downlink data to the remote UE.

[0829] -If the second RRC message to the remote UE includes configuration of a direct bearer and / or a direct path for a split bearer, the remote UE (re)configures zero, one or more direct bearers and zero, one or more direct paths for a split bearer for uplink data from the remote UE and / or downlink data to the remote UE.

[0830] - Indirect bearer or split bearer involves the establishment of Uu relay RLC channel.

[0831] - Indirect bearer is configured with an indirect link consisting of a Uu link and a side link.

[0832] - Direct bearer is configured over direct link only over Uu.

[0833] -Split bearer is configured with an indirect path and a direct path for the split bearer. The gNB may select one or both of the indirect path and the direct path for downlink data transmission toward the remote UE, and the remote UE may select one or both of the indirect path and the direct path for uplink data transmission toward the gNB.

[0834] 8. gNB and U2N relay UE perform relay channel establishment procedure over Uu. Based on the configuration from gNB, U2N relay / remote UE establishes PC5 relay RLC channel for relaying SRB1 towards U2N remote / relay UE over PC5.

[0835] 9. A second message sent to the remote UE (e.g., an RRCSetup message or an RRCResume message) may trigger a RACH from the remote UE and may include a RACH configuration. In this case, the remote UE triggers a RACH procedure to send an RRCSetupComplete message.

[0836] -RRC configuration may also include a UE-specific preamble. In this case, the remote UE may perform RACH preamble transmission using the UE-specific preamble.

[0837] -The MAC PDU in the MSG A PUSCH or MSG3 PUSCH may include a C-RNTI MAC CE indicating the C-RNTI allocated by the second message. If the second message does not allocate a C-RNTI, the remote UE may include a C-RNTI MAC CE indicating a temporary C-RNTI determined by the RACH procedure. Alternatively, if the second message does not allocate a C-RNTI, the MAC PDU may include a MAC CE or an RRC message including other UE identities (e.g., s-TMSI or resumeID) of the remote UE.

[0838] - The MAC PDU in MSG A PUSCH or MSG3 PUSCH may (also) include a buffer status report to report the UL buffer size at least for transmission of the RRCSetupComplete message from the remote UE.

[0839] -If SL resource allocation mode 1 is configured for the remote UE, the remote UE may (also) include a sidelink buffer status report to report the SL buffer size and request SL resources to facilitate sending SL data via an indirect bearer or indirect path of a split bearer from the remote UE.

[0840] If the RACH procedure from the remote UE is successfully completed, the remote UE sends a third message (i.e., RRCSetupComplete message or RRCResumeComplete message) directly to the gNB. Then, the remote UE is in RRC_CONNECTED and has an indirect path via the relay UE and a direct path with the gNB.

[0841] If the RACH procedure from the remote UE is not successfully completed (i.e., RACH failure), the remote UE indirectly sends a third message (e.g., RRCSetupFailure message or RRCReumeFailure message) to the gNB via the U2N relay UE using the SRB1 relay channel through PC5 and the SRB1 relay channel configured to the U2N relay UE through Uu. The remote UE is then in RRC_CONNECTED and has only an indirect path with the gNB via the relay UE. In the case of RACH failure, the third message may notify the gNB of the RACH failure and / or failure of the direct path establishment or multipath operation.

[0842] Alternatively, if the RACH procedure from the remote UE is not successfully completed (i.e., RACH failure), the remote UE initiates an RRC reestablishment procedure by sending an RRCReestablishmentRequest message to the gNB indirectly or directly via the relay UE. If the RRCReestablishmentRequest message is sent directly to the gNB, the remote UE triggers the RACH procedure again to send an RRCReestablishmentRequest message indicating the resumption or failure of the multipath operation. In this procedure, the remote UE may perform cell reselection to the same cell as the relay UE.

[0843] Alternatively, if the RACH procedure from the remote UE is not successfully completed (i.e., RACH failure), the remote UE initiates an RRC recovery procedure by sending an RRCResumeRequest message to the gNB indirectly or directly via the relay UE. If the RRCResumeRequest message is sent directly to the gNB, the remote UE triggers the RACH procedure again to send an RRCResumeRequest message indicating the recovery or failure of the multipath operation. In this procedure, the remote UE may perform cell reselection to the same cell as the relay UE.

[0844] 10. If the RACH procedure from the remote UE is completed successfully, the U2N remote UE and the gNB establish AS security following the Uu procedure, e.g. via direct path.

[0845] However, if the RACH procedure from the remote UE is not completed successfully (i.e., RACH failure), the U2N remote UE and gNB establish AS security via an indirect path, and the AS security message is forwarded through the U2N relay UE.

[0846] 11. The third message from the remote UE may include an initial NAS message from the remote UE. The third message from the relay UE may include an initial NAS message from the relay UE. After receiving the third message, the gNB forwards the initial NAS message (e.g., a service request message) to a core network (CN) node (such as an AMF or SMF). After receiving the initial NAS message, the CN node may provide the multipath configuration to the gNB and the UE as follows:

[0847] 1) Alternative 1:

[0848] -When a remote UE establishes an RRC connection with a gNB, for example via a relay UE, the remote UE sends an initial NAS message to the CN node. The initial NAS message may indicate the remote UE's preference for multipath operation. Upon receiving the initial NAS message from the remote UE, the CN node provides the gNB with UE capabilities related to multipath operation and multipath-related NAS configurations. If UE capabilities and / or NAS configurations are received, the gNB determines whether to configure multipath operation as described above.

[0849] In addition, when the relay UE establishes an RRC connection with the gNB, the relay UE sends an initial NAS message to the CN node. The initial NAS message may indicate the relay UE's preference for multipath operation. Upon receiving the initial NAS message from the relay UE and the initial NAS message from the remote UE, the CN node provides the gNB with UE capabilities related to multipath operation and multipath-related NAS configuration. If UE capabilities and / or NAS configuration are received, the gNB determines whether to configure multipath operation as described above.

[0850] 2) Alternative 2:

[0851] -After the remote UE establishes an RRC connection with the gNB, e.g., via a relay UE, the gNB determines whether to configure multipath operation as described above. If the gNB determines multipath operation, the gNB indicates the multipath operation to the CN node.

[0852] Upon receiving the indication from the gNB, the CN node provides the gNB with UE capabilities related to multipath operation and multipath related NAS configuration. If UE capabilities and / or NAS configuration are received, the gNB configures the multipath operation as described above based on the received UE capabilities and / or NAS configuration.

[0853] Upon receiving the indication from the gNB, the CN node provides the multipath related NAS configuration to the remote UE and / or the relay UE. The remote UE and / or the relay UE configures the multipath operation as described above based on the multipath related NAS configuration on top of the above RRC configuration provided by the gNB.

[0854] 3) Alternative 3:

[0855] -When the relay UE establishes an RRC connection with the gNB, the relay UE sends an initial NAS message to the CN node. The initial NAS message may indicate the relay UE's preference for multipath operation. Upon receiving the initial NAS message from the relay UE, the CN node provides the gNB with UE capabilities related to multipath operation and multipath related NAS configuration. If UE capabilities and / or NAS configuration are received, the gNB determines whether to configure multipath operation as described above.

[0856] In addition, when the relay UE establishes an RRC connection with the gNB, for example via the relay UE, the remote UE may also send an initial NAS message to the CN node. The initial NAS message may indicate the remote UE's preference for multipath operation. Upon receiving the initial NAS message from the remote UE and the initial NAS message from the relay UE, the CN node provides the gNB with UE capabilities related to multipath operation and multipath-related NAS configurations. If UE capabilities and / or NAS configurations are received, the gNB determines whether to configure multipath operation as described above.

[0857] The CN node (e.g., AMF or SMF) may inform the gNB of the UE capabilities and multipath configuration (e.g., in the QoS profile for remote UEs and / or relay UEs), or add the multipath configuration. The QoS profile is sent from the CN node to the gNB.

[0858] - The multipath related information in the QoS profile may indicate whether multipath can be configured for one of the following:

[0859] Each PDU session

[0860] Each QoS flow

[0861] Each remote UE

[0862] Each relay UE

[0863] Each frequency

[0864] Each community

[0865] Each RAT

[0866] Each PLMN

[0867] Each tracking area

[0868] Each gNB

[0869] 12. If the CN node does not provide the UE capabilities of the remote UE, upon request from the gNB, the U2N remote UE informs the gNB of the UE capabilities of the remote UE (e.g., including whether the remote UE supports U2N bearers / channels and / or MP operations).

[0870] If the CN node does not provide the UE capabilities of the relay UE, then upon a request from the gNB, the U2N relay UE informs the gNB of the UE capabilities of the relay UE (e.g., including whether the relay UE supports U2N bearers / channels and / or MP operations).

[0871] 13. To add a direct path and an indirect path for a remote UE, as an alternative message to adding a direct path or as an additional message after a second message to add a direct path, the gNB may send an RRCReconfiguration message to the relay UE and / or the remote UE after completing the RRC connection (re)establishment (and AS security activation) for the relay UE or remote UE, for example, based on UE capabilities and multipath configuration from the CN node. The RRCReconfiguration message sent by the gNB to the U2N remote UE indirectly via the U2N relay UE or directly to the remote UE facilitates the establishment of SRB2 / DRB for the direct path and the indirect path. In addition, the gNB sends an RRCReconfiguration message to the U2N relay UE.

[0872] -If the RRCReconfiguration message to the relay UE includes sl-L2RelayUEConfig, the relay UE performs the L2U2N relay UE configuration procedure to (re)configure zero, one or more direct bearers, zero, one or more indirect bearers and zero, one or more split bearers for uplink data from the remote UE and / or downlink data to the remote UE.

[0873] - If the RRCReconfiguration message to the remote UE includes sl-L2RemoteUEConfig, the remote UE performs the L2 U2N Remote UE Configuration procedure to (re)configure zero, one or more direct bearers, zero, one or more indirect bearers and zero, one or more split bearers for the remote UE for uplink data from the remote UE and / or downlink data to the remote UE.

[0874] -If the second RRC message and / or the RRCReconfiguration message to the relay UE includes the configuration of direct bearers and / or direct paths for split bearers, the remote UE (re)configures zero, one or more direct bearers and zero, one or more direct paths for split bearers for uplink data from the remote UE and / or downlink data to the remote UE.

[0875] -If the second RRC message and / or the RRCReconfiguration message to the remote UE includes the configuration of a direct bearer and / or a direct path for a split bearer, the remote UE (re)configures zero, one or more direct bearers and zero, one or more direct paths for a split bearer for uplink data from the remote UE and / or downlink data to the remote UE.

[0876] A. Option 1: Joint RRC Reconfiguration

[0877] -The gNB sends an RRCReconfiguration message to the relay UE. The RRCReconfiguration message includes at least a first part and a second part. The first part includes a configuration for adding an indirect / split bearer applied to the relay UE, and the second part includes a configuration for adding an indirect / split bearer and adding a direct bearer or a direct path of the split bearer applied to the remote UE.

[0878] (i) Option 1A: The relay UE forwards the second part to the remote UE by sending a Uu RRC message (eg, RRCReconfiguration message) to the remote UE.

[0879] For example, the second part is included in the RRC container of the RRCReconfiguration message. The gNB encrypts the first part by a first security key configured between the gNB and the relay UE, and encrypts the second part by a second security key configured between the gNB and the remote UE. After receiving the RRCReconfiguration message, if the relay UE successfully applies the configuration of the first part, the layer of the relay UE removes the first part from the RRCReconfiguration message and forwards the second part in the RRC container to the remote UE by sending an RRCReconfiguration message that does not include the first part to the remote UE. The layer of the relay UE may be one of the PDCP layer, the SRAP layer, and the RRC layer of the relay UE. In addition, if the relay UE does not successfully apply the configuration of the first part, the relay UE may not forward the second part in the RRC container to the remote UE.

[0880] After receiving the second part, the remote UE decrypts the second part by using the second security key. If the remote UE successfully applies the configuration of the second part, the remote UE encrypts the RRCReconfigurationComplete message by using the second security key, and then sends it directly to the gNB or indirectly to the gNB via the relay UE. If the remote UE does not successfully apply the configuration of the second part, the remote UE encrypts the RRCReconfigurationFailure or RRCReconfigurationComplete message indicating the failure of U2N configuration or multipath configuration by using the second security key, and then sends it directly to the gNB or indirectly to the gNB via the relay UE. Alternatively, if the remote UE does not successfully apply the configuration of the second part, the remote UE initiates an RRC re-establishment procedure, for which the remote UE suspends the direct bearer and suspends or releases the indirect / split bearer. The remote UE may also release the PC5-RRC connection with the relay UE.

[0881] In case of RRC re-establishment procedure on Uu interface, as a result of the procedure, the remote UE performs random access to the gNB and configures only direct bearers. In the RRC re-establishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating the failure of U2N configuration or multipath configuration and the source identity or destination identity of the relay UE and / or the remote UE.

[0882] In case of RRC re-establishment procedure via relay UE, the remote UE sends an RRCReestablishmentComplete message to the relay UE by using SL-RLC1 for SRB1, and then the relay UE forwards the RRCReestablishmentComplete message to the gNB. The RRCRestablishmentComplete message indicates the failure of U2N configuration or multipath configuration and the source identity or destination identity of the relay UE and / or remote UE.

[0883] If the remote UE fails to successfully apply the configuration of the second part, the remote UE may release the PC5-RRC connection with the relay UE, or notify the relay UE of the sidelink relay reconfiguration failure or the multipath configuration failure.

[0884] After releasing the PC5-RRC connection or after receiving a sidelink relay reconfiguration failure or a multipath configuration failure, the relay UE sends an RRCReconfigurationFailure or RRCReconfigurationComplete message of U2N configuration or multipath configuration failure to the gNB. The RRC container of the RRCReconfigurationComplete message sent from the relay UE to the gNB may include the RRCReconfigurationComplete message received from the remote UE. Alternatively, after the release of the PC5-RRC connection, after receiving or detecting a sidelink relay reconfiguration failure or a multipath configuration failure, or if the relay UE fails to successfully apply the configuration of the first part, the relay UE initiates an RRC reestablishment procedure, for which the relay UE suspends the direct bearer and suspends or releases the indirect / split bearer. The relay UE may also release the PC5-RRC connection with the remote UE, or notify the remote UE of the sidelink relay reconfiguration failure or the multipath configuration failure. In the RRC reestablishment procedure, as a result of the procedure, the relay UE performs random access to the gNB and configures only the direct bearer. In the RRC re-establishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating the failure of the U2N configuration or the multi-path configuration and the source identity or the destination identity of the relay UE and / or the remote UE.

[0885] (ii) Option 1B: The relay UE forwards the second part to the remote UE by sending a PC5 RRC message (eg, an RRCReconfigurationSidelink message or a UuMessageTransferSidelink message) to the remote UE.

[0886] For example, the second part is included in the RRC container of the RRCReconfiguration message or the UuMessageTransferSidelink message. The gNB encrypts the first part by the first security key configured between the gNB and the relay UE, and encrypts the second part by the first security key (or the second security key configured between the gNB and the remote UE). After receiving the RRCReconfiguration message, the relay UE decrypts the second part by using the first security key (or the second security key). Then, the relay UE encrypts the second part by using the third security key configured on the PC5 interface between the relay UE and the remote UE. The relay UE forwards the second part to the remote UE by including the second part in the RRCReconfigurationSidelink message sent to the remote UE. The second part can be included in the RRC container of the RRCReconfigurationSidelink message, or the second part is reconstructed to be included in the RRCReconfigurationSidelink message.

[0887] After receiving the second part, the remote UE decrypts the second part by using the third security key. If the remote UE successfully applies the configuration of the second part, the remote UE encrypts the RRCReconfigurationCompleteSidelink message by using the third security key and then sends it to the relay UE. If the remote UE does not successfully apply the configuration of the second part, the remote UE encrypts the RRCReconfigurationFailureSidelink message indicating the failure of U2N configuration or multipath configuration by using the third security key and then sends it to the relay UE. Alternatively, if the remote UE does not successfully apply the configuration of the second part, the remote UE initiates an RRC re-establishment process, for which the remote UE suspends the direct bearer and suspends or releases the indirect / split bearer. The remote UE can also release the PC5-RRC connection with the relay UE.

[0888] In case of RRC re-establishment procedure on Uu interface, as a result of the procedure, the remote UE performs random access to the gNB and configures only direct bearers. In the RRC re-establishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating the failure of U2N configuration or multipath configuration and the source identity or destination identity of the relay UE and / or the remote UE.

[0889] In case of RRC re-establishment procedure via relay UE, the remote UE sends an RRCReestablishmentComplete message to the relay UE by using SL-RLC1 for SRB1, and then the relay UE forwards the RRCReestablishmentComplete message to the gNB. The RRCReestablishmentComplete message indicates the failure of U2N configuration or multipath configuration and the source identity or destination identity of the relay UE and / or remote UE.

[0890] After receiving the RRCReconfigurationFailureSidelink message, after receiving the sidelink relay reconfiguration failure or the multipath configuration failure, after detecting the sidelink failure (e.g., due to the expiration of the timer T400), or if the relay UE does not successfully apply the first part of the configuration, the relay UE sends an RRCReconfigurationFailure or RRCReconfigurationComplete message of U2N configuration or multipath configuration failure to the gNB. Alternatively, after receiving the RRCReconfigurationFailureSidelink message, after receiving the sidelink relay reconfiguration failure or the multipath configuration failure, after detecting the sidelink failure (e.g., due to the expiration of the timer T400), or if the relay UE does not successfully apply the first part of the configuration, the relay UE initiates an RRC reestablishment procedure for which the relay UE suspends the direct bearer and suspends or releases the indirect / split bearer. The relay UE may also release the PC5-RRC connection with the remote UE, or notify the remote UE of the sidelink relay reconfiguration failure or the multipath configuration failure. In the RRC re-establishment procedure, as a result of the procedure, the relay UE performs random access to the gNB and configures only direct bearers. In the RRC re-establishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating the failure of U2N configuration or multipath configuration and the source identity or destination identity of the relay UE and / or remote UE.

[0891] In option 1, when the remote UE or the relay UE performs the RRC re-establishment procedure, it may also inform the gNB which UE failed to apply the U2N configuration or multi-path configuration (i.e., the remote UE or the relay UE).

[0892] B. Option 2: Separate delivery of RRC reconfiguration

[0893] - The gNB sends a first RRCReconfiguration message to the relay UE. The first RRCReconfiguration message includes a configuration regarding the addition of at least an indirect / split bearer applied to the relay UE.

[0894] After receiving the first RRCReconfiguration message, if the relay UE successfully applies the configuration of the first message, the relay UE sends an RRCReconfigurationComplete message to the gNB. However, after receiving the first message, if the relay UE does not successfully apply the configuration of the first message, when releasing the PC5-RRC connection, or when receiving or detecting a sidelink relay reconfiguration failure or a multipath configuration failure, the relay UE initiates an RRC reestablishment process, for which the relay UE suspends direct bearers and suspends or releases indirect / split bearers. The relay UE may also release the PC5-RRC connection with the remote UE, or notify the remote UE of the sidelink relay reconfiguration failure or the multipath configuration failure. During the RRC reestablishment process, as a result of the process, the relay UE performs random access to the gNB and configures only direct bearers. During the RRC reestablishment process, the relay UE sends an RRCReestablishmentComplete message indicating the failure of the U2N configuration or the multipath configuration and the source identity or destination identity of the relay UE and / or the remote UE.

[0895] -The gNB sends a second RRCReconfiguration message to the remote UE. The second RRCReconfiguration message includes configurations regarding the addition of indirect / split bearers and the addition of direct paths and direct bearers for the split bearers applied to the remote UE.

[0896] The gNB may send the second RRCReconfiguration message directly to the remote UE over the Uu interface, for example by using SRB1.

[0897] After receiving the second message, if the remote UE successfully applies the configuration of the second message, the remote UE sends an RRCReconfigurationComplete message to the gNB. If the remote UE does not successfully apply the configuration of the second message, the remote UE directly or indirectly sends an RRCReconfigurationFailure or RRCReconfigurationComplete message indicating a failure of U2N configuration or multipath configuration to the gNB.

[0898] The RRCReconfigurationComplete or RRCReconfigurationFailure message is sent directly to the gNB by using SRB1, or indirectly to the gNB via the relay UE by using SL-RLC1 for SRB1.

[0899] If the remote UE fails to successfully apply the configuration of the second message, the remote UE may release the PC5-RRC connection with the relay UE, or notify the relay UE of the sidelink relay reconfiguration failure or the multipath configuration failure.

[0900] Alternatively, if the remote UE does not successfully apply the configuration of the second message, the remote UE initiates an RRC re-establishment process, for which the remote UE suspends the direct bearer and suspends or releases the indirect / split bearer. The remote UE may also release the PC5-RRC connection with the relay UE and / or notify the relay UE of a sidelink relay reconfiguration failure or a multipath configuration failure.

[0901] In case of RRC re-establishment procedure on Uu interface, as a result of the procedure, the remote UE performs random access to the gNB and configures only direct bearers. In the RRC re-establishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating the failure of U2N configuration or multipath configuration and the source identity or destination identity of the relay UE and / or the remote UE.

[0902] In case of RRC re-establishment procedure via relay UE, the remote UE sends an RRCReestablishmentComplete message to the relay UE by using SL-RLC1 for SRB1, and then the relay UE forwards the RRCReestablishmentComplete message to the gNB. The RRCReestablishmentComplete message indicates the failure of U2N configuration or multipath configuration and the source identity or destination identity of the relay UE and / or remote UE.

[0903] After releasing the PC5-RRC connection or after receiving a sidelink relay reconfiguration failure or a multipath configuration failure, the relay UE sends an RRCReconfigurationFailure or RRCReconfigurationComplete message of U2N configuration or multipath configuration failure to the gNB. If an RRCReestablishmentRequest message is received from the remote UE, the RRC container of the RRCReconfigurationComplete message sent from the relay UE to the gNB may include the RRCReestablishmentRequest message received from the remote UE.

[0904] Alternatively, after the PC5-RRC connection is released, after receiving or detecting a sidelink relay reconfiguration failure or a multipath configuration failure, or if the relay UE fails to successfully apply the configuration of the first message, the relay UE initiates an RRC reestablishment procedure, for which the relay UE suspends the direct bearer and suspends or releases the indirect / split bearer. The relay UE may also release the PC5-RRC connection with the remote UE, or notify the remote UE of the sidelink relay reconfiguration failure or the multipath configuration failure. In the RRC reestablishment procedure, as a result of the procedure, the relay UE performs random access to the gNB and configures only direct bearers. In the RRC reestablishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating a failure of U2N configuration or multipath configuration and a source identity or destination identity of the relay UE and / or the remote UE. If an RRCReestablishmentRequest message is received from the remote UE, the RRC container of the RRCReestablishmentComplete message sent from the relay UE to the gNB may include the RRCReestablishmentRequest message received from the remote UE.

[0905] Alternatively, the gNB may send the second RRCReconfiguration message indirectly via the relay UE by using the PC5 relay RLC channel for SRB1 (i.e., SL-RLC1).

[0906] After receiving the first RRCReconfiguration message, if the relay UE successfully applies the configuration of the first message, the relay UE forwards the second RRCReconfiguration message received from the gNB to the remote UE. The relay UE also sends an RRCReconfigurationComplete message to the gNB. However, after receiving the first message, if the relay UE does not successfully apply the configuration of the first message, after releasing the PC5-RRC connection, or after receiving or detecting a sidelink relay reconfiguration failure or a multipath configuration failure, the relay UE does not forward the second RRCReconfiguration message received from the gNB to the remote UE, and the relay UE initiates an RRC reestablishment procedure, for which the relay UE suspends the direct bearer and suspends or releases the indirect / split bearer. The relay UE may also release the PC5-RRC connection with the remote UE, or notify the remote UE of the sidelink relay reconfiguration failure or the multipath configuration failure. In the RRC reestablishment procedure, as a result of the procedure, the relay UE performs random access to the gNB and configures only the direct bearer. In the RRC re-establishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating the failure of the U2N configuration or the multi-path configuration and the source identity or the destination identity of the relay UE and / or the remote UE.

[0907] If the relay UE notifies the remote UE of the sidelink relay reconfiguration failure or the multipath configuration failure, the remote UE initiates an RRC reestablishment process, for which the remote UE suspends the direct bearer and suspends or releases the indirect / split bearer. The remote UE may also release the PC5-RRC connection with the relay UE.

[0908] In case of RRC re-establishment procedure on Uu interface, as a result of the procedure, the remote UE performs random access to the gNB and configures only direct bearers. In the RRC re-establishment procedure, the relay UE sends an RRCReestablishmentComplete message indicating the failure of U2N configuration or multipath configuration and the source identity or destination identity of the relay UE and / or the remote UE.

[0909] In case of RRC re-establishment procedure via relay UE, the remote UE sends an RRCReestablishmentComplete message to the relay UE by using SL-RLC1 for SRB1, and then the relay UE forwards the RRCReestablishmentComplete message to the gNB. The RRCReestablishmentComplete message indicates the failure of U2N configuration or multipath configuration and the source identity or destination identity of the relay UE and / or remote UE.

[0910] 14. The U2N Remote UE sends an RRCReconfigurationComplete message to the gNB indirectly via the U2N Relay UE, or directly sends an RRCReconfigurationComplete message to the gNB as a response. In addition, the gNB configures an additional Uu Relay RLC channel between the gNB and the U2N Relay UE and a PC5 Relay RLC channel between the U2N Relay UE and the U2N Remote UE for relay services.

[0911] 15. The remote UE sends uplink data to the gNB via the relay UE by using the Uu relay RLC channel and the PC5 relay RLC channel. The gNB sends downlink data to the remote UE via the relay UE by using the Uu relay RLC channel and the PC5 relay RLC channel.

[0912] 16. The remote UE and / or relay UE may perform flow control as follows to control the amount of data on the indirect path.

[0913] For example, the remote UE may report the downlink data delivery status to the relay UE, the relay UE may report the downlink data delivery status to the base station, or the remote UE may report the downlink data delivery status to the base station through the relay UE. The downlink data delivery status report may be reported through an RLC control PDU, reported through a MAC CE, reported through an RRC message, reported through a PDCP control PDU, or reported through another layer 2 control PDU.

[0914] For example, when the DL data delivery status is reported through the PDCP control PDU, it may be reported as follows: For example, the remote UE may report the DL data delivery status to the base station as follows.

[0915] The remote UE may report the downlink data delivery status to the base station through a direct path or an indirect path.

[0916] In case of data transmission without SL HARQ feedback or SL RLC feedback (eg, RLC UM or HARQ feedback disabled channel), the remote UE may be configured to report to the base station through a direct path.

[0917] In case of data transmission with SL HARQ feedback or SL RLC feedback (eg, RLC AM or HARQ feedback enabled channel), the remote UE may be configured to report to the base station via a direct path.

[0918] The Downlink Data Delivery Status procedure is used to provide feedback from a remote UE or relay UE to the gNB hosting the NR PDCP entity to allow the gNB hosting the NR PDCP entity to control the downlink user data flow for the corresponding data radio bearer via the relay UE. The relay UE may also transmit the uplink user data for the relevant data radio bearer together with the DL data delivery status in the same Layer 2 PDU carrying the uplink user data to the gNB hosting the NR PDCP entity.

[0919] [Table 7]

[0920]

[0921]

[0922] For example, when the DL data delivery status is reported through the RLC control PDU, it can be reported as follows: For example, the relay UE can report the DL data delivery status to the base station as follows.

[0923] To this end, the remote UE may provide a SL RLC status report to the relay UE. For example, before performing the downlink data transfer status procedure, the relay UE may trigger the remote UE's SL RLC status report through SL RLC polling.

[0924] The Downlink Data Delivery Status procedure is used to provide feedback from a remote UE or relay UE to the gNB hosting the NR PDCP entity to allow the gNB hosting the NR PDCP entity to control the downlink user data flow for the corresponding data radio bearer via the relay UE. The relay UE may also transmit uplink user data for the relevant data radio bearer together with the DL data delivery status in the same Layer 2 PDU carrying the uplink user data to the gNB hosting the NR PDCP entity.

[0925] [Table 8]

[0926]

[0927]

[0928] For example, the DL data delivery status reported to the gNB or relay UE may be constructed as follows, noting that the PDCP SN in the DL data delivery status may be replaced by the RLC SN of the DL data delivery status from the relay UE:

[0929] Fig.26 An example of DL data delivery status is illustrated.

[0930] -Through the RRC reconfiguration message, the base station can set SL resource allocation mode 1 to allocate SL resources for the remote UE. That is, the base station can allocate SL grants to be sent by the remote UE through DCI. In this case, the remote UE can perform the following operations:

[0931] (1) The remote UE may report the Uu BSR (Buffer Status Report MAC CE) and SL-BSR (Sidelink Buffer Status Report MAC CE) directly to the base station in one of the following ways: For example, when PDCP duplication is configured, the BSR may be reported according to method 1, otherwise the BSR may be reported according to method 2 or method 3. Alternatively, depending on the configuration of the base station, the BSR may be reported in one of the following ways:

[0932] 1) Method 1: The remote Uu BSR and SL-BSR can be configured to repeatedly report 100% buffer status for the same bearer. For example, when the SL RLC entity and the UL RLC entity are connected to the same PDCP entity, when the PDCP buffer size of the corresponding bearer is 100 bytes:

[0933] - In the SL BSR, for the buffer size of the corresponding bearer, the PDCP buffer size of 100 bytes and the SL RLC buffer size may be combined and reported.

[0934] Here, in the SL-BSR, the buffer state for a specific destination may be set for the SL relay. When the SL BSR MAC CE is configured for multiple destinations, the buffer size for a specific destination of the SL relay may be included in the SLBSR MAC CE with a higher priority than the buffer size for other destinations.

[0935] - In the Uu BSR, for the buffer size of the bearer, the PDCP buffer size of 100 bytes and the UL RLC buffer size may be combined and reported.

[0936] -After receiving the SL BSR and the Uu BSR, the base station may allocate UL resources and SL resources by allocating UL BS (buffer size) and SL BS.

[0937] 2) Method 2: When the SL RLC entity and the UL RLC entity are connected together to the same PDCP entity, the base station determines whether to include the PDCP buffer size in the Uu BSR or the SL BSR for each specific bearer, for each specific logical channel group, or for each specific destination. The remote UE can determine whether to report the PDCP buffer size by including it in the Uu BSR or the SL BSR for each specific bearer, for each specific logical channel group, or for each specific destination according to the setting of the base station.

[0938] 3) Method 3: When the SL RLC entity and the UL RLC entity are connected together to the same PDCP entity, the remote UE reports whether to include the PDCP buffer size in the Uu BSR or the SLBSR according to whether the RLC entity determined as the primary path is UL or SL.

[0939] - The buffer size of the PDCP entity for bearers where the direct path is the primary path is reported in the Uu BSR but not in the SL BSR.

[0940] - The buffer size of the PDCP entity for bearers whose indirect path is the primary path is reported in the SL BSR but not in the Uu BSR.

[0941] 4) Method 4: When the remote UE operates in SL mode 2, SL resources may be reserved. At this time, the remote UE may determine the Y% buffer status based on the reserved resources, and the Uu BSR may be configured to report (100-Y)% of the buffer size. The SL-BSR may be configured to report the remaining Y% buffer size, or the SL-BSR report may not be configured / sent.

[0942] 5) Method 5: The X% buffer status may be determined based on the UL resources allocated to the remote UE, and the SL-BSR may be configured to report (100-X)% buffer size. The Uu BSR may be configured to report or not report the X% buffer size. The remote UE may be set to SL Mode 1 or SL Mode 2. When set to SL Mode 2, the remote UE may reserve SL resources up to (100-X)% buffer size without reporting the (100-X)% buffer size by the SL-BSR.

[0943] In the Uu BSR of the above method, the remote UE may report the BS (buffer size) of the split bearer, the BS of the indirect bearer, the BS of the direct bearer, and the BS of the bearer for which PDCP duplication is set.

[0944] - For example, the BS for split bearers (buffer size), the BS for indirect bearers, the BS for direct bearers, and the BS for bearers with PDCP duplication set up may be reported as BSs for different LCGs.

[0945] Alternatively, the Uu BSR may be configured to include separate BS fields for a split bearer's BS (buffer size), an indirectly carried BS, a directly carried BS, and a bearer's BS with PDCP duplication set up.

[0946] (2) BSR reporting method or resource allocation method of relay UE

[0947] If the remote UE reports an SL-BSR or Uu BSR, the base station may set the relay UE not to report the buffer status of the corresponding U2N bearer. Alternatively, the relay UE may set a specific logical channel group for the corresponding U2N bearer, or set a specific destination to be included in the Uu BSR with a low priority. Alternatively, the buffer status of the destination for a specific remote UE may not be reported, or may be set to be included in the BSR with a low priority.

[0948] The base station may allocate SL resources of the remote UE according to the SL BSR of the remote UE, and allocate UL resources of the relay UE according to the SL resources.

[0949] -The base station may allocate UL resources for a specific remote UE or a logical channel for a U2N relay through DCI. The DCI may indicate the destination of the remote UE, or the CRC may be scrambled with a UE-specific RNTI mapped to the remote UE or an RNTI for the U2N relay.

[0950] - Alternatively, when SL data of a specific PC5 RLC channel is received from a remote UE, specific UL resources within a specific time interval may be preferentially used for uplink transmission of the SL data. For example, when a UL MAC PDU is configured in the UL logical channel prioritization process, data of a UL RLC channel mapped to a specific PC5 RLC channel may be preferentially mapped to specific UL resources within a specific time interval.

[0951] (3) The base station can set SL resource allocation mode 2 to allocate SL resources to the remote UE. That is, the remote UE can select and send SL resources in the resource pool allocated by the base station.

[0952] In this SL mode 2, the remote UE may be configured to report SLBSR only for logical channels used for U2N relay. For example, method 4 and method 5 may be applied as follows.

[0953] 4) Method 4: When the remote UE operates in SL mode 2, SL resources may be reserved. The remote UE may determine the Y% buffer status based on the reserved SL resources, and the Uu BSR may be configured to report (100-Y)% of the buffer size. The SL-BSR may be configured to report the remaining Y% buffer size, or the SL-BSR report may not be configured / sent.

[0954] Alternatively, out of the entire 100% uplink data rate, the remote UE may determine the Y% uplink data rate based on the reserved SL resources and send the remaining (100-Y)% data rate to the UL. Thus, the UL buffer size for the remaining (100-Y)% data rate may be reported as the Uu BSR. The SL-BSR may be configured to report up to the remaining Y% data rate, or may not be configured / sent.

[0955] 5) Method 5: The X% buffer status may be determined based on the UL resources allocated to the remote UE, and the SL-BSR may report (100-X)% buffer size. The Uu BSR may be configured to report or not report the X% buffer size. When set to SL Mode 2, the remote UE may reserve SL resources up to (100-X)% buffer size. The remote UE may not report the SL-BSR for the corresponding bearer.

[0956] Alternatively, out of the entire 100% uplink data rate, the remote UE may determine the X% uplink data rate based on the allocated UL resources and send the remaining (100-X)% data rate to the SL. Thus, the SL resources may be reserved for the (100-X)% data rate. The UL buffer size may be reported in the Uu BSR. The Uu BSR may be configured to report or not report the X% buffer size. The remote UE may not report the SL-BSR for the corresponding bearer.

[0957] (4) If SL BSR is not configured, the remote UE may only report Uu BSR.

[0958] Since the base station cannot control SL transmission, there is a problem of unnecessarily allocating UL or SL resources when the Uu BSR for the remote always reports a 100% buffer status.

[0959] Uplink resources for remote UEs

[0960] -Base stations can allocate UL resources by distributing UL BS and SL BS

[0961] -Except the amount of data sent to the UL resource, the rest of the data is sent to the SL relay.

[0962] - The remote UE may be configured to allocate only Y% of the PDCP buffer as SL resources.

[0963] The remote UE may configure Y% for all destinations or for each logical channel.

[0964] The remote UE may determine Y % using a value indicated by the base station or relay UE, or using a minimum value, a maximum value, or an average value among Y1 and Y2 indicated by the base station / relay UE.

[0965] - The remote UE may specify a maximum, minimum or average SL data rate for all destinations or for each logical channel. Accordingly, SL data transmissions exceeding the SL data rate may be discarded, SL resources not exceeding the SL data rate may be allocated, or SL resources exceeding the SL data rate may be cancelled.

[0966] For example, the SL resources reserved each time may be limited according to the SL data rate.

[0967] The remote UE can set the SL data rate for all destinations or for each logical channel.

[0968] The remote UE may determine the SL data rate having a value indicated by the base station or relay UE, or may determine the SL data rate having a minimum value, a maximum value or an average value among SL data rate 1 and SL data rate 2 indicated by the base station / relay UE.

[0969] - The base station or relay UE can set the CR limit to be applied by the remote UE. The remote UE can limit the amount of data to be sent to the SL according to the CR limit. Therefore, SL data transmission exceeding the CR limit can be discarded.

[0970] The CR limit can be set for all destinations or for each logical channel.

[0971] The remote UE may determine the CR limit using a value indicated by the base station or relay UE, or may determine the CR limit using a minimum value, a maximum value, or an average value among CR Limit 1 and CR Limit 2 indicated by the base station / relay UE.

[0972] - The base station or relay UE sets a resource pool for all destinations or for each logical channel, and the remote UE can reserve and send SL resources within the configured resource pool.

[0973] The base station may be set to limit the number of SL resources in the resource pool. In addition, the relay UE may again limit the number of SL resources in the resource pool set by the base station. Alternatively, the number of SL resources may be determined as the minimum, maximum or average value among the number of SL resources 1 and the number of SL resources 2 limited by the base station / relay UE.

[0974] (5) When U2N relay is configured, the remote UE and relay UE may report Uu BSR or SL BSR as follows.

[0975] 1) Remote UE BSR reporting method

[0976] -Uu BSR

[0977] In the case of a specific bearer or split bearer, for the PDCP entity and UL RLC entity of the bearer:

[0978] The remote UE may include and report only the PDCP buffer size in the BSR and not the RLC buffer size.

[0979] Alternatively, the remote UE may include both the RLC buffer size and the PDCP buffer size in the BSR and report it.

[0980] Alternatively, the remote UE may include and report only the RLC buffer size in the BSR and not the PDCP buffer size.

[0981] In case of a specific indirect bearer, the remote UE does not include the corresponding BS in the BSR.

[0982] -SL-BSR

[0983] In the case of a specific bearer or split bearer, for the PDCP entity and SL RLC entity of the bearer:

[0984] The remote UE may include and report only the PDCP buffer size in the SL BSR and not the RLC buffer size.

[0985] Alternatively, the remote UE may include both the RLC buffer size and the PDCP buffer size in the SL BSR and report them.

[0986] Alternatively, the remote UE may include and report only the RLC buffer size in the SL BSR, and not the PDCP buffer size.

[0987] In case of a specific direct bearer, the remote UE does not include the corresponding BS in the SL BSR.

[0988] 2) BSR reporting method of relay UE

[0989] -Uu BSR

[0990] In case of a specific bearer, split bearer or indirect bearer, only the RLC buffer size of the corresponding U2N bearer may be reported.

[0991] -SL-BSR

[0992] The base station may allocate SL resources to the relay UE based on the amount of DL U2N bearer data transmission, but the base station may not be aware of the SL RLC AM retransmission, SL RLC control PDU or SL MAC CE. Therefore, the relay UE may be configured to include only the size of the SL RLC AM retransmission, SL RLC control PDU or SL MAC CE in the SL BSR.

[0993] To reduce unnecessary SL BSR transmissions,

[0994] The relay UE may be configured not to report the SL BS for a specific destination.

[0995] The relay UE may be configured to report only specific data (eg, retransmission / control PDU / MAC CE) for a specific destination.

[0996] The remote UE may report the TX SL buffer size waiting for the remote UE to relay UE transmission. In this case, the relay UE may report a preemptive BSR to the base station. The preemptive BSR MAC CE may include the expected PDCP and / or RLC buffer size calculated based on the TX SL buffer size reported by the remote UE.

[0997] (6) When the remote UE configures a split bearer, the following operations may be performed for the split bearer having a direct path and an indirect path.

[0998] When the primary path of a specific bearer is a direct path, the remote UE may preferentially use UL resources for data of the corresponding bearer, and only the remaining data after all UL resources are consumed may be sent in the SL resources.

[0999] When the primary path of a specific bearer is an indirect path, the remote UE may preferentially use SL resources for the bearer's data, and only the remaining data after all SL resources are consumed may be sent as UL resources.

[1000] The remote UE may switch or maintain the primary path for a specific bearer to an indirect path if one or more of the following conditions are met.

[1001] - If the serving cell measurement result of the remote UE is below a certain threshold, the primary path of a specific bearer can be switched to an indirect path.

[1002] - If the CBR measurement result for the SL resources is below a certain threshold, the primary path for a specific bearer can be switched to an indirect path.

[1003] - If the SL relay measurement result for the SL resources (e.g., the SL-RSRP or SD-RSRP measurement result of the relay UE) exceeds a certain threshold, the primary path of the specific bearer can be switched to the indirect path.

[1004] - When Uu failure is detected in a specific bearer, the primary path of the specific bearer may be switched to an indirect path.

[1005] When integrity protection failure, RLC retransmission failure, RLF, bearer reconfiguration failure, beam failure, etc. are detected for a specific bearer, it can be switched to an indirect path.

[1006] The remote UE may switch or maintain the primary path for a particular bearer to the direct path if one or more of the following conditions are met.

[1007] - If the serving cell measurement result of the remote UE is equal to or greater than a certain threshold, the primary path of the specific bearer can be switched to the direct path.

[1008] - If the CBR measurement result for the SL resource exceeds a certain threshold, the primary path for a specific bearer can be switched to the direct path.

[1009] - If the SL relay measurement result for the SL resources (e.g., the SL-RSRP or SD-RSRP measurement result of the relay UE) is lower than a certain threshold, the primary path of the specific bearer can be switched to the direct path.

[1010] - When SL failure is detected in a specific bearer, the primary path of the specific bearer may be switched to the direct path.

[1011] When integrity protection failure, RLC retransmission failure, HARQ feedback-based SL failure, bearer reconfiguration failure, etc. are detected for a specific bearer, it can be switched to the direct path.

[1012] 17. The remote UE may be configured by the network to derive NR sidelink measurement results of the serving L2 relay UE or candidate L2 U2N relay UE associated with the measurement objects configured in measObjectRelay.

[1013] The remote UE may receive the measurement configuration in the RRCReconfiguration message. If the UE receives measConfig in the RRCReconfiguration message, the UE performs measurements for each measId included in the measIdList in VarMeasConfig and initiates the measurement reporting procedure as follows:

[1014] A. If the measObject is associated with a L2 U2N relay UE, the remote UE performs corresponding measurements associated with the candidate relay UE on the frequency indicated in the measObject in question. When performing measurements, the UE filters the measurement results based on layer 3 filtering before the measurement report used to evaluate the reporting criteria or for each candidate L2 U2N relay UE measurement quantity:

[1015] B. For each L2 U2N relay UE measurement quantity to be derived, the remote UE shall:

[1016] - derive the corresponding measurement quantity based on the DMRS of the L2 U2N relay UE associated with the NR sidelink frequency indicated in the measObjectRelay concerned, as described in TS 38.215; and

[1017] - Application layer 3 filtering.

[1018] C. If the corresponding measObject involves L2 U2N relay UE:

[1019] - if the event Y1-Relay is configured in the corresponding reportConfig; or

[1020] - If the corresponding reportConfig includes a reportType set to periodic:

[1021] The remote UE shall consider any L2 U2N relay UE detected on the associated frequency as applicable to this measId;

[1022] Table 9 describes the events used for measurement report triggering.

[1023] [Table 9]

[1024]

[1025]

[1026]

[1027]

[1028]

[1029]

[1030] D. If reportType is set to eventTriggered, and if, after layer 3 filtering during timeToTrigger defined in VarMeasConfig for this event (i.e. the event corresponding to eventId of the corresponding reportConfig in VarMeasConfig), all measurements for one or more applicable L2 U2N relay UEs meet the entry criteria applicable to this event, and VarMeasReportList does not include a measurement report entry for this measId (first L2 U2N relay UE triggering event), then the remote UE shall:

[1031] - Include the measurement report entry for the measId in VarMeasReportList;

[1032] - Set numberOfReportsSent defined for this measId in VarMeasReportList to 0;

[1033] - Include the L2 U2N relay UE involved in the relaysTriggeredList defined for the measId in VarMeasReportList;

[1034] - Initiate the measurement reporting procedure, as in the next step.

[1035] Otherwise, if reportType is set to eventTriggered, and if, after layer 3 filtering during timeToTrigger defined in VarMeasConfig for that event (i.e. the event corresponding to eventId of the corresponding reportConfig in VarMeasConfig), all measurements for one or more applicable L2 U2N relay UEs not included in relaysTriggeredList meet the entry criteria applicable to that event (the subsequent L2 U2N relay UE triggered event), then the remote UE shall:

[1036] - Set numberOfReportsSent defined for this measId in VarMeasReportList to 0;

[1037] - Include the L2 U2N relay UE involved in the relaysTriggeredList defined for the measId in VarMeasReportList;

[1038] - Initiate the measurement reporting procedure, as in the next step.

[1039] E. Otherwise, if reportType is set to eventTriggered and if, after layer 3 filtering during the timeToTrigger defined for this event in VarMeasConfig, all measurements for one or more applicable L2 U2N relay UEs included in the relaysTriggeredList defined for this measld in VarMeasReportList meet the leaving conditions applicable to this event, then the remote UE shall:

[1040] - Remove the L2 U2N relay UE involved from the relaysTriggeredList defined for the measId in VarMeasReportList;

[1041] - If reportOnLeave is set to true for the corresponding reporting configuration, the measurement reporting procedure is initiated, as in the next step.

[1042] - If the relaysTriggeredList defined for the measId in VarMeasReportList is empty, remove the measurement report entry for the measId in VarMeasReportList; if it is running, stop the periodic report timer for the measId;

[1043] F. If reportType is set to periodic, and if the (first) measurement result is available:

[1044] - if reportAmount exceeds 1: the UE shall initiate the measurement reporting procedure as specified in 5.5.5 (if the UE is a L2 U2N remote UE) immediately after the amount to be reported becomes available to the NR SpCell or serving L2U2N relay UE;

[1045] - Otherwise (i.e., reportAmount is equal to 1): immediately after the amount to be reported becomes available for the NR SpCell and the strongest cell among the applicable cells or for the NR SpCell and the strongest L2 U2N relay UE among the applicable L2 U2N relay UEs, initiate the measurement reporting procedure as specified in 5.5.5; or immediately after the amount to be reported becomes available for the serving L2 U2N relay UE and the strongest cell among the applicable cells, initiate the measurement reporting procedure as in the next step (if the UE is a L2 U2N remote UE);

[1046] 18. After initiating the measurement reporting procedure in the previous step, for the measId that triggered the measurement reporting procedure, the UE shall set the measResults in the MeasurementReport message as follows, and then the remote UE sends the MeasurementReport message to the network via the SRB.

[1047] A. If the UE is connected to a L2 U2N relay UE via a PC5-RRC connection (i.e., the UE is a L2 U2N remote UE), the UE sets sl-MeasResultServingRelay to include the SL-RSRP of the serving L2 U2N relay UE;

[1048] - In case there is no data transmission from L2 U2N relay UE to L2 U2N remote UE, when setting sl-MeasResultServingRelay serving L2U2N relay UE, whether to use SL-RSRP or SD-RSRP depends on UE implementation.

[1049] B. If there is at least one applicable neighboring cell to report:

[1050] - If reportType is set to eventTriggered or periodic, and if the measurement report concerns candidate L2 U2N relay UEs, the UE shall set sl-MeasResultCandRelay to include up to maxReportCell best candidate L2 U2N relay UEs according to:

[1051] If reportType is set to eventTriggered: the UE shall include the L2 U2N relay UEs included in the relaysTriggeredList defined for this measId in VarMeasReportList;

[1052] Otherwise: the UE shall include applicable L2 U2N relay UEs for which new measurement results have become available since the last periodic report or since the measurements were initiated or reset;

[1053] - For each L2 U2N relay UE included in sl-MeasResultsCandRelay, the UE shall include sl-RelayUEIdentity. For each included L2 U2N relay UE, the UE shall include the layer 3 filtered measurement results in order according to the reportConfig for that measId.

[1054] If the measObject associated with this measId relates to an L2 U2N relay UE, the UE shall set measResult to include the quantities indicated in reportQuantityRelay in descending order of the sorted quantities within the reportConfigRelays involved, including the best L2 U2N relay UE first;

[1055] For a candidate L2 U2N relay UE, the UE shall consider yN-Threshold2-Relay as the ranking quantity;

[1056] For a candidate L2 U2N relay UE, the UE shall consider reportQuantityRelay as the ranking quantity.

[1057] Table 10 describes the SL-MeasResultsSLRelay information element.

[1058] [Table 10]

[1059]

[1060]

[1061] C. In the second message or RRCReconfiguration message, the gNB may configure the reportConfig associated with the one or more events for which the triggered measurement report is set to eventTriggered and the eventID is set to measId for the event-triggered measurement report as follows:

[1062] - For the serving cell on which the remote UE camps, for the serving cell on which the relay UE camps, or for the best ranked suitable cell for the remote UE, the remote UE may be configured with one or more of the following events:

[1063] Event A1 (Service / best cell quality becomes better than threshold)

[1064] Event A2 (Service / Best Cell Quality Becomes Worse Than Threshold)

[1065] Event A3 (Neighbor cell becomes better in terms of cell quality than serving / best cell offset)

[1066] Event N1 (neighbor cell quality becomes better than the threshold)

[1067] The remote UE can trigger this event only for cells indicated by the gNB in ​​the RRCReconfiguration message.

[1068] Event N2 (neighbor cell quality becomes worse than the threshold)

[1069] The remote UE can trigger this event only for cells indicated by the gNB in ​​the RRCReconfiguration message.

[1070] Note that the best ranked suitable cell for the remote UE or the serving cell on which the remote UE is camped may be the same as or different from the serving cell of the relay UE.

[1071] Note that the remote UE may be configured to trigger events A3, N1 and / or N2 only for cells indicated by the gNB in ​​the RRCReconfiguration message.

[1072] - For a serving cell on which the remote UE is camped or a serving frequency of the best ranked suitable cell for the remote UE, for a frequency with a highest cell reselection priority or a cell reselection priority above a priority threshold (e.g., a priority above a threshold), or for a non-serving frequency for the remote UE, the remote UE may be configured with one or more of the following events:

[1073] Event S1 (Suitable / best cell quality on a frequency becomes better than a threshold)

[1074] Event S2 (Suitable / best cell quality on frequency becomes worse than threshold)

[1075] Event S3 (Neighbor suitable cell becomes better than the best cell offset in terms of cell quality)

[1076] Note that if the above events are triggered for a suitable / best cell or a neighboring cell, the remote UE reports the following information to the gNB.

[1077] Measurement results for suitable / best cells and / or neighbor suitable cells

[1078] As a result of the suitability check based on reading the SIB1 of the neighboring cell, whether the neighbor cell is suitable.

[1079] Global cell identification of suitable / best cell

[1080] Global cell identifier of the neighboring cell

[1081] D. In the second message or RRCReconfiguration message, the gNB may configure the reportConfig associated with the measId that triggers the measurement report to be set to periodic as reportType, so the remote UE performs as follows:

[1082] -The UE performs corresponding measurements associated with the remote UE's serving cell, the relay UE's serving cell (if the serving cell has been indicated by the relay UE) and / or the remote UE's best ranked (suitable) cell for the frequency indicated by the gNB.

[1083] -If the received measObject includes cellsToAddModList in the RRCReconfiguration message, the UE performs corresponding measurements associated with each cell or each detected cell corresponding to the physCellId value included in cellsToAddModList on the frequency indicated by the gNB.

[1084] -Then, the UE periodically reports the measurement results about each cell (as measured by the remote UE in the above steps) to the gNB via the relay UE.

[1085] In the measurement report to the gNB, the UE first includes measurement results about the serving cell of the remote UE and / or the serving cell of the relay UE (or the serving cell of the relay UE and / or the serving cell of the remote UE) in order, and then measurement results about each other cell in cellsToAddModList in descending order of the sorting amount (for example, in descending order of measured RSRP or RSRQ results).

[1086] 19. After RRC connection establishment and PC5-RRC connection establishment or after RRC reconfiguration, the relay UE and / or the remote UE may perform the sidelink UE1 information for the NR sidelink communication procedure, in which the UE sends a SidelinkUEInformationNR message to the gNB.

[1087] The UE shall set the content of the SidelinkUEInformationNR message as follows:

[1088] A. If a specific SIB (e.g., SIB12) includes sl-NonRelayDiscovery and if the specific SIB is configured by an upper layer to receive NR sidelink non-relay discovery announcements, or if a specific SIB (e.g., SIB12) includes sl-L2U2N-Relay and if the specific SIB is configured by an upper layer to receive NR sidelink L2 U2N relay discovery announcements, or if a specific SIB (e.g., SIB12) includes sl-L3U2N-RelayDiscovery and if the specific SIB is configured by an upper layer to receive NR sidelink L3U2N relay discovery announcements, or if a specific SIB (e.g., SIB12) includes an indication of multipath support and if the specific SIB is configured by an upper layer to receive NR sidelink U2N relay discovery announcements:

[1089] - The UE shall include sl-RxInterestedFreqListDisc and set it to the frequency for NR side link discovery announcement reception;

[1090] - If the UE is capable of operating as an L2 U2N remote UE, or the UE is capable of multipath operation as a remote UE, the UE shall include sl-SourceIdentity-RemoteUE and set it to the source identity configured by upper layers for NR sidelink L2 U2N relay communication transmission.

[1091] B. If a specific SIB (e.g., SIB12) includes sl-NonRelayDiscovery and if the specific SIB is configured by upper layers to send NR sidelink non-relay discovery advertisements, or if a specific SIB (e.g., SIB12) includes sl-L2U2N-Relay and if the specific SIB is configured by upper layers to send NR sidelink L2 U2N relay discovery advertisements, or if a specific SIB (e.g., SIB12) includes sl-L3U2N-RelayDiscovery and if the specific SIB is configured by upper layers to send NR sidelink L3U2 N relay discovery advertisements, or if a specific SIB (e.g., SIB12) includes an indication of multipath support and if the specific SIB is configured by upper layers to send NR sidelink U2N relay discovery advertisements: The UE shall include sl-TxResourceReqListDis and set its fields as follows (if necessary) for each destination for which it requests the network to assign NR sidelink discovery advertisement resources:

[1092] - sl-DestinationIdentityDisc is set to the destination identity configured by upper layers for NR sidelink discovery announcement transmission;

[1093] - If the UE acts as a L2 U2N relay UE, the UE shall set sl-SourceIdentity-RelayUE to the source identity configured by upper layers for NR sidelink L2 U2N relay discovery announcement transmission;

[1094] - sl-CastTypeDisc is set to the cast type of the associated destination identifier configured by upper layers for NR sidelink discovery announcement transmission;

[1095] - set sl-InterestedFreqListDisc to indicate the frequency of the associated destination for NR sidelink discovery advertisement transmission;

[1096] - Set sl-TypeTxSyncListDisc to the current synchronization reference type used on the associated sl-InterestedFreqList for NR sidelink discovery announcement transmission;

[1097] - sl-DiscoveryType is set to the current discovery type of the associated destination identifier configured by upper layers for NR sidelink discovery announcement transmission;

[1098] C. If configured by upper layers to send NR sidelink L2 U2N relay communications and the UE acts as a L2U2N relay UE for multipath, the relay UE shall:

[1099] - Include sl-TxResourceReqL2U2N-Relay in sl-TxResourceReqListCommRelay and set its fields as follows (if necessary) for each destination for which it requests the network to assign NR sidelink L2 U2N relay communication resources:

[1100] - sl-DestinationIdentityL2U2N is set to the destination identity configured by upper layers for NR sidelink L2 U2N relay communication transmission;

[1101] - set sl-TxInterestedFreqListL2U2N to indicate the frequencies of the associated destinations for NR sidelink L2 U2N relay communication transmissions;

[1102] - Set sl-TypeTxSyncListL2U2N to the current synchronization reference type used on the associated sl-InterestedFreqListL2U2N for NR sidelink L2 U2N relay communication transmissions;

[1103] - Set sl-LocalID-Request to the local ID of the requesting L2 U2N remote UE;

[1104] - Set sl-PagingIdentity-RemoteUE to the paging UE ID received from the peer L2 U2N remote UE;

[1105] - sl-CapabilityInformationSidelink is set to include the UECapabilityInformationSidelink message received from the peer UE, if any.

[1106] - Include ue-Type and set it to relayUE;

[1107] - Includes an indication of support / request for multipathing

[1108] - Includes an indication of the RRC state of the remote UE or whether the remote UE is in RRC_CONNECTED.

[1109] - Includes the cell identity of the PCell of the remote UE.

[1110] - Includes the PLMN identity of the remote UE's registered PLMN.

[1111] - The tracking area code including the tracking area where the remote UE is registered for the PCell.

[1112] D. If configured by upper layers to send NR sidelink L2 U2N relay communications and the UE has a selected L2 U2N relay UE for multipath, the remote UE shall:

[1113] - Include sl-TxResourceReqL2U2N-Relay in sl-TxResourceReqListCommRelay and set its fields (if necessary) as follows to request the network to assign NR sidelink L2 U2N relay communication resources:

[1114] - set sl-TxInterestedFreqListL2U2N to indicate the frequencies of the associated destinations for NR sidelink L2 U2N relay communication transmissions;

[1115] - Set sl-TypeTxSyncListL2U2N to the current synchronization reference type used on the associated sl-InterestedFreqListL2U2N for NR sidelink L2 U2N relay communication transmissions;

[1116] - sl-CapabilityInformationSidelink is set to include the UECapabilityInformationSidelink message received from the peer UE, if any.

[1117] - include ue-Type and set it to remoteUE;

[1118] - Includes an indication of support / request for multipathing

[1119] - Includes an indication of the RRC state of the relay UE or whether the relay UE is in RRC_CONNECTED.

[1120] - Includes the cell identity of the PCell of the relay UE.

[1121] - Includes the PLMN identity of the relay UE's registered PLMN.

[1122] - Includes the tracking area code of the tracking area where the relay UE is registered for the PCell.

[1123] E. If configured by upper layers to send NR sidelink L3 U2N relay communications, the relay UE or remote UE shall:

[1124] - Include sl-TxResourceReqL3U2N-Relay in sl-TxResourceReqListCommRelay and set its fields (if necessary) as follows for each destination for which it requests the network to assign NR sidelink L3 U2N relay communication resources:

[1125] - sl-DestinationIdentity is set to the destination identity configured by upper layers for NR sidelink L3 U2N relay communication transmission;

[1126] - sl-CastType is set to the cast type of the associated destination identifier configured by upper layers for the NR sidelink L3 U2N relay communication transmission;

[1127] - if the associated bidirectional sidelink DRB has been established due to configuration by RRCReconfigurationSidelink, sl-RLC-ModeIndication is set to the QoS profile including the RLC mode and optionally the sidelink QoS flow associated with the RLC mode;

[1128] - Set sl-QoS-InfoList to include the QoS profile of the sidelink QoS flow of the associated destination configured by the upper layer for NR sidelink L3 U2N relay communication transmission;

[1129] - set sl-TxInterestedFreqList to indicate the frequencies of the associated destinations for NR sidelink L3 U2N relay communication transmissions;

[1130] - Set sl-TypeTxSyncList to the current synchronization reference type used on the associated sl-InterestedFreqList for NR sidelink L3 U2N relay communication transmissions.

[1131] - sl-CapabilityInformationSidelink is set to include the UECapabilityInformationSidelink message received from the peer UE, if any.

[1132] - Include ue-Type, and if the UE acts as an NR sidelink L3 U2 N relay UE, set ue-Type to relayUE, otherwise set to remoteUE;

[1133] - Includes indication of multipath support / request

[1134] - Includes an indication of the RRC state of the relay UE or whether the relay UE is in RRC_CONNECTED.

[1135] - Includes an indication of the RRC state of the remote UE or whether the remote UE is in RRC_CONNECTED.

[1136] - If the UE acts as an NR sidelink U2N remote UE:

[1137] Includes the cell identifier of the PCell of the relay UE.

[1138] Includes the PLMN identifier of the registered PLMN of the relay UE.

[1139] Includes the tracking area code of the tracking area where the relay UE is registered for the PCell.

[1140] - If the UE acts as an NR sidelink U2N relay UE:

[1141] Includes the cell identity of the PCell of the remote UE.

[1142] Includes the PLMN identity of the remote UE's registered PLMN.

[1143] Contains the tracking area code of the tracking area where the remote UE is registered for the PCell.

[1144] 20. Upon receiving a report from the remote UE and / or the relay UE (e.g., a MeasurementReport message from the remote UE and / or a SidelinkUEInformationNR message from the relay UE and / or a SidelinkUEInformationNR message from the relay UE and / or a multipath configuration from the gNB), the gNB determines whether to modify or release the direct path with the gNB for the remote UE.

[1145] 21. When the gNB sends another RRCReconfiguration message, the relay UE and the remote UE may release one or more or all indirect bearers and / or split bearers that may be reconfigured as direct bearers according to the RRCReconfiguration message from the gNB. Note that with the RRCReconfiguration message from the gNB, the remote UE still maintains the direct link and the indirect link via the relay UE.

[1146] To release the indirect path of the split bearer for the indirect path of the multipath or the indirect bearer to be reconfigured as a direct bearer via the RRCReconfiguration message from the gNB, the remote UE or the relay UE performs one or more of the following:

[1147] A. The receiving PDCP entity of the bearer in the remote UE may trigger a PDCP status report to the gNB as follows:

[1148] -PDCP status report is sent directly from remote UE to gNB or indirectly via relay UE to gNB.

[1149] - Upon receiving the PDCP status report, the transmitting PDCP entity of the bearer in the gNB triggers 'Multi-path Data Exchange' to perform retransmission or transmission of the PDCP SDU on the direct path towards the remote UE as described below.

[1150] -After / before receiving the RRCReconfiguration message for releasing the bearer, the SL RLC entity in the remote UE or relay UE may perform one or more of the following:

[1151] Option 1: The remote UE releases the Uu RLC entity and / or PC5 RLC entity for the downlink indirect path of the bearer. As a result, the SL data buffered in the TX RLC entity is discarded and / or the DL data buffered in the RX RLC entity is discarded.

[1152] Option 2: For the SL RLC entity of the PC5 RLC channel of the downlink indirect path for the bearer, the AM RLC entity in the relay UE polls the peer AM RLC entity to trigger an RLC status report at the peer AM RLC entity in the remote UE. Based on the polling, the AM RLC entity in the remote UE triggers an RLC status report sent to the peer AM RLC entity in the relay UE.

[1153] Option 3: For the SL RLC entity of the PC5 RLC channel of the downlink indirect path of the bearer, the AM RLC entity in the remote UE triggers an RLC status report sent to the peer AM RLC entity in the relay UE.

[1154] - After receiving the RLC status report from the receiving RLC entity, the SL sending RLC entity in the relay UE performs retransmission of the RLC SDU or RLC SDU segment for which a negative acknowledgement was received via the RLC status report, as described below.

[1155] B. The receiving PDCP entity of the bearer in the gNB may trigger a PDCP status report to the remote UE as follows:

[1156] -PDCP status report is sent directly from the gNB to the remote UE or indirectly via the relay UE.

[1157] - Upon receiving the PDCP status report, the transmitting PDCP entity of the bearer in the remote UE triggers 'Multipath Data Exchange' to perform retransmission or transmission of the PDCP SDU on the direct path towards the gNB as described below.

[1158] -After / before receiving the RRCReconfiguration message for releasing the bearer, the SL RLC entity in the remote UE or relay UE may perform one or more of the following:

[1159] Option 1: The relay UE releases the Uu RLC entity and / or PC5 RLC entity for the uplink indirect path of the bearer. As a result, the SL data buffered in the RX RLC entity is discarded and / or the UL data buffered in the TX RLC entity is discarded.

[1160] Option 2: For the SL RLC entity of the PC5 RLC channel of the uplink indirect path for the bearer, the AM RLC entity in the remote UE polls the peer AM RLC entity to trigger an RLC status report at the peer AM RLC entity in the relay UE. Based on the polling, the AM RLC entity in the relay UE triggers an RLC status report sent to the peer AM RLC entity in the remote UE.

[1161] Option 3: For the SL RLC entity of the PC5 RLC channel of the uplink indirect path for the bearer, the AM RLC entity in the relay UE triggers an RLC status report sent to the peer AM RLC entity in the remote UE.

[1162] - After receiving the RLC status report from the receiving RLC entity, the SL sending RLC entity in the remote UE performs retransmission of the SL RLC SDU or SL RLC SDU segments for which negative acknowledgement was received via the RLC status report, as described below, until release of the bearer on Uu / PC5.

[1163] After receiving the SL RLC SDU and / or SL RLC SDU segment from the remote UE, the relay UE performs uplink retransmission of the UL RLC SDU or UL RLC SDU segment corresponding to the SL RLC SDU and / or SL RLC SDU segment until the release of the bearer.

[1164] Thereafter, the relay UE and / or the remote UE notifies the gNB of the release of the bearer, for example by sending a UE information message to the gNB.

[1165] Before / after receiving the UE INFORMATION message, the gNB releases the PDCP / RLC entity corresponding to the bearer and / or PC5-RRC connection.

[1166] Before / after sending the UE information message or after sending the RRCReconfiguration message to release the bearer to the remote UE and / or the relay UE, the relay UE and / or the remote UE releases the Uu / PC5-PDCP / RLC entity corresponding to the bearer and / or PC5-RRC connection.

[1167] C. After / before receiving the RRCReconfiguration message to release the bearer, the relay UE stops any RLC status reporting process in the DL receiving RLC entity and / or the SL sending RLC entity for the downlink indirect path of the bearer, and the relay UE releases the DL receiving RLC entity and / or the SL sending RLC entity. The relay UE may also send an RRCReconfigurationSidelink message to the remote UE to release the peer SL receiving RLC entity in the remote UE.

[1168] If PDCP status reporting is triggered, the receiving PDCP entity shall:

[1169] - Compile the PDCP status report as follows:

[1170] - Set the FMC field to RX_DELIV;

[1171] -if RX_DELIV <RX_NEXT:

[1172] - a bitmap field is allocated with a length in bits equal to the number of counts from the first missing PDCP SDU (excluding the first missing PDCP SDU) to the last out-of-sequence PDCP SDU (including the last out-of-sequence PDCP SDU) (rounded to the next multiple of 8), or to the PDCP SDU (including the PDCP SDU) with a resulting PDCP Control PDU size equal to 9000 bytes, whichever comes first;

[1173] - set to '0' in the Bitmap field for all PDCP SDUs that were not received, and optionally for PDCP SDUs for which decompression failed;

[1174] - set to '1' in the Bitmap field for all PDCP SDUs that have been received;

[1175] - The PDCP status report is submitted as the first PDCP PDU to lower layers for transmission via the transmitting PDCP entity as specified in section 5.2.1 of 3GPP TS 38.323 for the Uu interface and in section 5.2.3 of 3GPP TS 38.323 for the PC5 interface.

[1176] For an AM DRB, upon receiving a PDCP status report in the downlink or sidelink, the transmitting PDCP entity shall:

[1177] - For each PDCP SDU (if any), consider the bit in the bitmap to be set to '1' or the associated count value is less than the value of the successfully delivered FMC field and discard the PDCP SDU as specified in section 5.3 of 3GPP TS 38.323.

[1178] When multipath data exchange is triggered for a bearer (e.g. from an indirect bearer to a direct bearer), the transmitting PDCP entity in DL, UL or SL shall, for the bearer:

[1179] - For an AM DRB, before the multipath data switch to the RLC entity associated with the direct path in DL, UL or SL, retransmission or transmission of all PDCP SDUs already associated with the PDCP SNs are performed in ascending order of the count value associated with the PDCP SDUs, starting from the first PDCP SDU for which the RLC entity associated with the indirect path has not acknowledged the successful delivery of the corresponding PDCP data PDU, as specified below:

[1180] - Perform header compression of PDCP SDU using ROHC.

[1181] - performing integrity protection and ciphering of the PDCP SDU using the counter value associated with the PDCP SDU;

[1182] - Submit the obtained PDCP data PDU to the corresponding RLC entity of the direct path.

[1183] - For a UM DRB, for all PDCP SDUs that have been processed by PDCP but not yet submitted to lower layers, send the PDCP SDUs to the RLC entity associated with the direct path in DL, UL or SL in ascending order of the count value, as specified below:

[1184] - Perform header compression of PDCP SDU using ROHC

[1185] - Perform integrity protection and ciphering of the PDCP SDU using the counter value associated with the PDCP SDU

[1186] - Submit the obtained PDCP data PDU to the corresponding RLC entity of the direct path in DL, UL or SL.

[1187] [Table 11]

[1188]

[1189]

[1190] After receiving a status report from the receiving RLC AM entity, the transmitting side of the AM RLC entity shall:

[1191] - If the status report includes a positive or negative acknowledgement for the RLC SDU with sequence number equal to POLL_SN:

[1192] - If t-PollRetransmit is running:

[1193] - Stop and reset the timer t-PollRetransmit, which is used by the transmitting side of the AM RLC entity to retransmit polls.

[1194] - Consider an RLC SDU or RLC SDU segment for which a negative acknowledgement was received for retransmission.

[1195] In addition, upon receiving the RRCReconfiguration message from the gNB, for the above bearer (e.g., split bearer), the remote UE may reconfigure the direct path of the split bearer as the primary path as follows:

[1196] - If the RRCReconfiguration message does not configure the primary path for the bearer, the remote UE reconfigures the direct path of the split bearer as the primary path.

[1197] Alternatively, if the RRCReconfiguration message does not configure the primary path of the bearer, the remote UE maintains (or configures) the indirect path of the split bearer as the primary path.

[1198] Alternatively, if the RRCReconfiguration message does not configure the primary path of the bearer, the remote UE configures the direct path or the indirect path of the split bearer as the primary path according to a specified configuration or a default configuration.

[1199] -If the RRCReconfiguration message configures the primary path of the bearer, the remote UE configures the direct path or indirect path of the split bearer as the primary path according to the configuration in the RRCReconfiguration message.

[1200] - A certain type of signaling RB may always be configured with the direct path of the split bearer as the primary path (eg, according to a specified configuration or a default configuration).

[1201] 22. If one or more of the following conditions are met, the relay UE may request modification or release of the indirect path and / or indirect bearer of the split bearer to the gNB, and / or notify the gNB of the conditions that may trigger the modification or release (i.e., one or more of the following conditions) by using a first UE information message:

[1202] - If the relay UE detects a buffer overflow for the relayed bearer / channel (e.g., a TX or RX buffer overflow for SL transmission / reception between the relay UE and the remote UE, or a buffer overflow for UL transmission or DL ​​reception for U2N relay)

[1203] - If the relay UE cannot meet the QoS requirements of the relay bearer / channel (e.g., cannot meet the delay requirements or data rate requirements of the relay bearer / channel)

[1204] - If the relay UE establishes a PC5 unicast link with one or more remote UEs

[1205] - If the relay UE releases the PC5 unicast link with the remote UE

[1206] - If the relay UE detects a sidelink failure of the PC5 unicast link with the remote UE (e.g., sidelink radio link failure or sidelink reconfiguration failure or sidelink integrity protection failure)

[1207] - If the SL bearer that may be newly configured by the remote UE and / or relay UE cannot be mapped to any existing established Uu / PC5 RLC channel for relaying SL bearer

[1208] - If the SL bearer mapped to any established Uu / PC5 RLC channel is released by the remote UE and / or relay UE

[1209] - If the NAS layer of the relaying UE requests to add, modify or release an indirect path and / or indirect bearer of a split bearer that can be configured with multi-path operation.

[1210] The first UE information message includes one or more of the following items:

[1211] - an identifier of the intermediate bearer / channel that is subject to the above modification or the above modification condition (e.g., a bearer identity, a logical channel identity, a source identity, or a destination identity of the intermediate bearer / channel)

[1212] - an identifier of the intermediate bearer / channel subject to the above release or the above release condition (e.g., a bearer identity, a logical channel identity, a source identity or a destination identity of the intermediate bearer / channel)

[1213] -Reasons related to the above modification conditions

[1214] 23. The remote UE may request modification or release of the indirect path and / or indirect bearer of the split bearer to the gNB if one or more of the following conditions are met, and / or notify the gNB of the conditions that may trigger the modification or release (i.e., one or more of the following conditions) by using a second UE information message:

[1215] - If the remote UE detects a buffer overflow for the relay bearer / channel (e.g., a TX or RX buffer overflow for SL transmission / reception between the relay UE and the remote UE)

[1216] - If the remote UE cannot meet the QoS requirements of the overlay bearer / channel (e.g., cannot meet the delay requirements or data rate requirements of the overlay bearer / channel)

[1217] - If the remote UE establishes a PC5 unicast link with one or more relay UEs

[1218] - If the remote UE releases the PC5 unicast link with the relay UE

[1219] - If the remote UE detects a sidelink failure of the PC5 unicast link with the relay UE (e.g., sidelink radio link failure or sidelink reconfiguration failure or sidelink integrity protection failure)

[1220] - If the SL bearer that may be newly configured by the remote UE and / or relay UE cannot be mapped to any existing established Uu / PC5 RLC channel for relaying SL bearer

[1221] - If the SL bearer mapped to any established Uu / PC5 RLC channel is released by the remote UE and / or relay UE

[1222] - If the NAS layer of the remote UE requests to add, modify or release an indirect path and / or indirect bearer of a split bearer that can be configured with multipath operation.

[1223] The second UE information message includes one or more of the following:

[1224] - an identifier of the intermediate bearer / channel subject to the above modification or the above modification condition (eg a bearer identity, a logical channel identity, a source identity or a destination identity of the intermediate bearer / channel).

[1225] - an identifier of the overriding bearer / channel subject to the above release or the above release condition (eg a bearer identity, a logical channel identity, a source identity or a destination identity of the overriding bearer / channel).

[1226] - Reasons related to the above release conditions

[1227] 24. If the remote UE considers that one of the following events is met based on the above measurement configuration, the remote UE initiates the first measurement report process:

[1228] - Event X1 (serving L2 U2N relay UE becomes worse than threshold 1, and NR cell becomes better than threshold 2)

[1229] - Event X3 (the serving L2 U2N relay UE becomes worse than threshold 1, and the PCell (or PSCell or SCell) becomes better than threshold 2)

[1230] - Event X2 (serving L2 U2N relay UE becomes worse than threshold)

[1231] - Event Y2 (Candidate L2 U2N relay UE becomes better than threshold)

[1232] - Event C1 (NR side link channel busy rate is higher than the threshold)

[1233] If the remote UE considers that one of the following events is satisfied based on the above measurement configuration, the remote UE initiates the first measurement report process:

[1234] - Event C2 (NR side link channel busy rate is lower than the threshold)

[1235] - Event Y1 (PCell becomes worse than threshold 1, and candidate L2 U2N relay UE becomes better than threshold 2)

[1236] If the relay UE considers that one of the following events is met based on the measurement configuration, the relay UE initiates the second measurement report process:

[1237] - Event A2 (Service becomes worse than threshold)

[1238] - Event A3 (Neighbor becomes better than SpCell offset)

[1239] - Event B1 (Inter-RAT neighbor becomes better than threshold)

[1240] - Event B2 (PCell becomes worse than threshold 1, and inter-RAT neighbors become better than threshold 2)

[1241] - Event C1 (NR side link channel busy rate is higher than the threshold)

[1242] If the relay UE considers that the leaving condition of one of the following events is satisfied based on the above measurement configuration, the relay UE initiates the second measurement report process.

[1243] - Event C2 (NR side link channel busy rate is lower than the threshold)

[1244] - Event A1 (Service becomes better than threshold)

[1245] If the first measurement reporting procedure is initiated, the remote UE notifies the gNB of the measurement result of the relay UE and the identifier of the relay UE by using the first measurement report.

[1246] If the second measurement reporting procedure is initiated, the relay UE notifies the gNB of the measurement result of the remote UE and the identifier of the remote UE by using the second measurement report.

[1247] 25. A CN node (e.g., AMF or SMF) may notify the gNB of, for example, the addition, modification or release of a multipath configuration in the QoS profile of a remote UE and / or relay UE. The QoS profile is sent from the CN node to the gNB.

[1248] - The multipath related information in the QoS profile may indicate whether multipath can be configured for one of the following:

[1249] Each PDU session

[1250] Each QoS flow

[1251] Each remote UE

[1252] Each relay UE

[1253] Each frequency

[1254] Each community

[1255] Each RAT

[1256] Each PLMN

[1257] Each tracking area

[1258] Each gNB

[1259] 26. Based on the first / second UE information message and / or the first / second measurement report and / or the above-mentioned multipath configuration, the gNB determines the addition, modification or release of an indirect bearer and / or an indirect path for the split bearer of the relay bearer / channel.

[1260] If the gNB determines the addition, modification or release of the indirect path of the split bearer and / or the indirect bearer for the relay bearer / channel based on the following option 1 or option 2, for example by sending an RRCReconfiguration message to the relay UE and the remote UE respectively. The gNB may send the RRCReconfiguration message for modifying the relay bearer / channel based on option 1 as described below, and send the RRCReconfiguration message for releasing the relay bearer / channel based on option 2 as described below.

[1261] - If the RRCReconfiguration message includes the SL-DestinationIdentity corresponding to the remote UE in the sl-L2RelayUEConfig, the relay UE performs L2 U2N remote UE release to release all indirect bearers and one or more split bearers for the remote UE.

[1262] -If the RRCReconfiguration message includes the SL-DestinationIdentity corresponding to the remote UE and the BeaerIdentity or SL-DestinationIdentity corresponding to the indirect bearer or split bearer for the remote UE in sl-L2RelayUEConfig, the relay UE releases one or more L2 entities (e.g., RLC entities) and the logical channels corresponding to the indirect bearer or split bearer for the remote UE.

[1263] -If the RRCReconfiguration message includes the SL-DestinationIdentity corresponding to the relay UE and the BeaerIdentity or SL-DestinationIdentity corresponding to the indirect bearer or split bearer for the remote UE in sl-L2RemoteUEConfig, the remote UE releases or modifies one or more L2 entities (e.g., RLC entities) and the logical channels corresponding to the indirect bearer or split bearer for the relay UE according to the message. The remote UE may also add or modify a direct bearer to change an indirect / split bearer to a direct bearer.

[1264] -If the RRCReconfiguration message includes the SL-DestinationIdentity corresponding to the relay UE in sl-L2RemoteUEConfig, the remote UE releases all indirect bearers according to the message and releases or modifies one or more split bearers for the relay UE. The remote UE may also add or modify a direct bearer to change an indirect / split bearer to a direct bearer.

[1265] The following options for RRC reconfiguration as described above may be considered for this step.

[1266] A. Option 1: Joint RRC reconfiguration is used for the remote UE and relay UE to modify or release indirect bearers and / or split bearers to possibly release the U2N based connection.

[1267] B. Option 2: Separate delivery of RRC reconfiguration is used for remote UE and relay UE to modify or release indirect bearers and / or split bearers to possibly release U2N based connections.

[1268] 27. In the above steps, the relay UE and the remote UE may release one or more or all indirect bearers and / or split bearers that may be reconfigured as direct bearers. As a result of this step, the remote UE may maintain both the direct link and the indirect link via the relay UE, or the remote UE may maintain only the direct link while releasing the indirect link via the relay UE, and may release the PC5-RRC connection with the relay UE.

[1269] For the release of the indirect path of the split bearer or the indirect bearer of the indirect path of the multipath, the remote UE or the relay UE performs one or more of the following:

[1270] A. The receiving PDCP entity of the bearer in the remote UE may trigger a PDCP status report to the gNB as follows:

[1271] -PDCP status report is sent directly from remote UE to gNB or indirectly via relay UE to gNB.

[1272] - Upon receiving the PDCP status report, the transmitting PDCP entity of the bearer in the gNB triggers 'Multi-path data exchange' to perform retransmission or transmission of the PDCP SDU on the direct path towards the remote UE as described below.

[1273] -After / before receiving the RRCReconfiguration message for releasing the bearer or after / before the release of the PC5-RRC connection, the SL RLC entity in the remote UE or relay UE may perform one or more of the following:

[1274] Option 1: The remote UE releases the Uu RLC entity and / or PC5 RLC entity for the downlink indirect path of the bearer. As a result, the SL data buffered in the TX RLC entity is discarded and / or the DL data buffered in the RX RLC entity is discarded.

[1275] Option 2: For the SL RLC entity of the PC5 RLC channel of the downlink indirect path for the bearer, the AM RLC entity in the relay UE polls the peer AM RLC entity to trigger an RLC status report at the peer AM RLC entity in the remote UE. Based on the polling, the AM RLC entity in the remote UE triggers an RLC status report sent to the peer AM RLC entity in the relay UE.

[1276] Option 3: For the SL RLC entity of the PC5 RLC channel of the downlink indirect path of the bearer, the AM RLC entity in the remote UE triggers an RLC status report sent to the peer AM RLC entity in the relay UE.

[1277] - After receiving the RLC status report from the receiving RLC entity, the SL sending RLC entity in the relay UE performs retransmission of the RLC SDU or RLC SDU segment for which a negative acknowledgement was received via the RLC status report, as described below.

[1278] B. The receiving PDCP entity of the bearer in the gNB may trigger a PDCP status report to the remote UE as follows:

[1279] -PDCP status report is sent directly from the gNB to the remote UE or indirectly via the relay UE.

[1280] -After receiving the PDCP status report, the transmitting PDCP entity of the bearer in the remote UE triggers 'Multipath Data Exchange' to perform retransmission or transmission of the PDCP SDU on the direct path towards the gNB as described below.

[1281] -After / before receiving the RRCReconfiguration message for releasing the bearer or after / before the release of the PC5-RRC connection, the SL RLC entity in the remote UE or relay UE may perform one or more of the following:

[1282] Option 1: The relay UE releases the Uu RLC entity and / or PC5 RLC entity for the uplink indirect path of the bearer. As a result, the SL data buffered in the RX RLC entity is discarded and / or the UL data buffered in the TX RLC entity is discarded.

[1283] Option 2: For the SL RLC entity of the PC5 RLC channel of the uplink indirect path for the bearer, the AM RLC entity in the remote UE polls the peer AM RLC entity to trigger an RLC status report at the peer AM RLC entity in the relay UE. Based on the polling, the AM RLC entity in the relay UE triggers an RLC status report sent to the peer AM RLC entity in the remote UE.

[1284] Option 3: For the SL RLC entity of the PC5 RLC channel of the uplink indirect path for the bearer, the AM RLC entity in the relay UE triggers an RLC status report sent to the peer AM RLC entity in the remote UE.

[1285] -After receiving the RLC status report from the receiving RLC entity, the SL sending RLC entity in the remote UE performs retransmission of the SL RLC SDU or SL RLC SDU segment for which a negative acknowledgement was received via the RLC status report, as described below, until release of the PC5-RRC release and / or release of the bearer on Uu / PC5.

[1286] After receiving the SL RLC SDU and / or SL RLC SDU segments from the remote UE, the relay UE performs uplink retransmission of the UL RLC SDU or UL RLC SDU segments corresponding to the SL RLC SDU and / or SL RLC SDU segments until the release of the PC5-RRC connection or bearer.

[1287] Thereafter, the relay UE and / or remote UE notifies the gNB of the release of the PC5-RRC connection and / or the release of the bearer, for example by sending a UE information message to the gNB.

[1288] Before / after receiving the UE INFORMATION message, the gNB releases the PDCP / RLC entity corresponding to the bearer and / or PC5-RRC connection.

[1289] Before / after sending the UE information message or after sending the RRCReconfiguration message for releasing the bearer to the remote UE and / or the relay UE, the relay UE and / or the remote UE releases the Uu / PC5 PDCP / RLC entity corresponding to the bearer and / or PC5-RRC connection.

[1290] C. After / before receiving the RRCReconfiguration message for releasing the bearer or after / before releasing the PC5-RRC connection, the relay UE stops any RLC status reporting process in the DL receiving RLC entity and / or the SL sending RLC entity for the downlink indirect path of the bearer, and the relay UE releases the DL receiving RLC entity and / or the SL sending RLC entity. The relay UE may also send an RRCReconfigurationSidelink message to the remote UE to release the peer SL receiving RLC entity in the remote UE.

[1291] Using the disclosed invention, the network can configure direct and indirect paths for multipath operation, and dynamically activate or deactivate RLC entity and PDCP duplication according to the present invention, especially when the UE can support U2N relay functionality via SL.

[1292] The benefit of the present invention is that the system can dynamically provide multipath operation including direct links and indirect links via U2N relay.In the prior art, there is no mechanism to provide multipath operation using sidelink relay.

[1293] Fig. 27 A method for transmitting a signal by a user equipment (UE) in one embodiment of the present disclosure is illustrated. The UE may be a remote UE.

[1294] Reference Fig. 27 , the UE may receive a first message (2705) including configuration information about a multipath (MP) bearer configured with a plurality of radio link control (RLC) entities, the plurality of RLC entities including at least one first RLC entity associated with a direct path to a network and at least one second RLC entity associated with an indirect path to the network. The configuration information may include information about data duplication for data unit transmission.

[1295] The UE may receive a second message including information about activation / deactivation of each RLC entity (2710). The information about activation / deactivation of each RLC entity may be configured based on an RLC entity index for the plurality of RLC entities. The RLC entity index may be determined based on the following index order: at least one first RLC entity index of at least one first RLC entity associated with a direct path may be followed by at least one second RLC entity index of at least one second RLC entity associated with an indirect path. Data unit transmission may be based on data replication on an activated RLC entity among the plurality of RLC entities.

[1296] The UE may send a data unit based on the MP bearer configured by the configuration information (2715).

[1297] Preferably, the information on activation / deactivation of each RLC entity may be configured as a Medium Access Control (MAC) Control Element (CE).

[1298] Preferably, the MAC CE may include an activation / deactivation indication for each RLC entity index.

[1299] Preferably, the second message including the information on activation / deactivation of each RLC entity may be received through a direct path.

[1300] Preferably, the second message including the information on activation / deactivation of each RLC entity may be received by the remote UE in an indirect path.

[1301] Preferably, the at least one first RLC entity index may be lower than the at least one second RLC entity index.

[1302] Preferably, the data unit may be a Packet Data Convergence Protocol (PDCP) data unit, and the data copying is a PDCP data unit copying.

[1303] Preferably, the at least one second RLC entity may be at least one side link (SL) RLC entity associated with a relay UE in an indirect path to the network.

[1304] Preferably, the first message may be received through radio resource control (RRC) signaling.

[1305] Preferably, the multiple RLC entity indexes may be logical channel identifiers of the multiple RLC entities.

[1306] Fig.28 Splitting bearers is illustrated. Fig.28 (a) is the split bearer for DC. Fig.28(b) is a split bearer configured with a direct path and an indirect path. PDCP duplication may be performed by an RLC entity. In the DC case (a), PDCP duplication may be performed by two or more of RLC entities 0 to 2. In the MP case (b), PDCP duplication may be performed by two or more of RLC entities 0 to 3. In the MP case (b), the UL RLC entity in the direct path is assigned a lower index than the index of the SL RLC entity in the indirect path.

[1307] Although not limited thereto, the various descriptions, functions, processes, proposals, methods and / or operational flowcharts of the present disclosure described herein may be applied to various fields requiring wireless communication / connection between devices (e.g., 5G).

[1308] Hereinafter, a description will be given in more detail with reference to the accompanying drawings. In the following drawings / descriptions, unless otherwise described, the same reference numerals may represent the same or corresponding hardware blocks, software blocks or functional blocks.

[1309] Fig.29 A communication system applied to the present disclosure is illustrated.

[1310] Reference Fig.29 , the communication system 1 applied to the present disclosure includes a wireless device, a BS, and a network. Herein, a wireless device refers to a device that performs communication using a RAT (e.g., 5G NR or LTE), and may be referred to as a communication / radio / 5G device. The wireless device may include, but is not limited to, a robot 100a, a vehicle 100b-1 and 100b-2, an extended reality (XR) device 100c, a handheld device 100d, a home appliance 100e, an Internet of Things (IoT) device 100f, and an artificial intelligence (AI) device / server 400. For example, a vehicle may include a vehicle with a wireless communication function, an autonomous driving vehicle, and a vehicle capable of performing inter-vehicle communication. Herein, a vehicle may include an unmanned aerial vehicle (UAV) (e.g., a drone). The XR device may include an augmented reality (AR) / virtual reality (VR) / mixed reality (MR) device and may be implemented in the form of a head-mounted device (HMD), a head-up display (HUD) installed in a vehicle, a television, a smart phone, a computer, a wearable device, a home appliance device, a digital signage, a vehicle, a robot, and the like. Handheld devices may include smart phones, smart boards, wearable devices (e.g., smart watches or smart glasses), and computers (e.g., notebooks). Home appliances may include TVs, refrigerators, and washing machines. IoT devices may include sensors and smart meters. For example, a BS and a network may be implemented as wireless devices, and a specific wireless device 200a may operate as a BS / network node relative to other wireless devices.

[1311] The wireless devices 100a to 100f may be connected to the network 300 via the BS 200. AI technology may be applied to the wireless devices 100a to 100f, and the wireless devices 100a to 100f may be connected to the AI ​​server 400 via the network 300. The network 300 may be configured using a 3G network, a 4G (e.g., LTE) network, or a 5G (e.g., NR) network. Although the wireless devices 100a to 100f may communicate with each other via the BS 200 / network 300, the wireless devices 100a to 100f may perform direct communication (e.g., sidelink communication) with each other without passing through the BS / network. For example, the vehicles 100b-1 and 100b-2 may perform direct communication (e.g., V2V / V2X communication). An IoT device (e.g., a sensor) may perform direct communication with other IoT devices (e.g., a sensor) or other wireless devices 100a to 100f.

[1312] Wireless communication / connection 150a, 150b or 150c can be established between wireless devices 100a to 100f / BS200 or BS200 / BS200. Herein, wireless communication / connection can be established through various RATs (e.g., 5G NR) such as UL / DL communication 150a, side link communication 150b (or D2D communication) or inter-BS communication (e.g., relay, integrated access backhaul (IAB)). The wireless device and the BS / wireless device can send / receive radio signals to each other through wireless communication / connection 150a and 150b. For example, wireless communication / connection 150a and 150b can send / receive signals through various physical channels. To this end, various configuration information configuration processes for sending / receiving radio signals, various signal processing processes (e.g., channel coding / decoding, modulation / demodulation, and resource mapping / demapping) and at least a portion of the resource allocation process can be performed based on various proposals of the present disclosure.

[1313] Fig.30 A wireless device suitable for use with the present disclosure is illustrated.

[1314] Reference Fig.30 , the first wireless device 100 and the second wireless device 200 may transmit radio signals through various RATs (e.g., LTE and NR). Herein, {the first wireless device 100 and the second wireless device 200} may correspond to Fig.29 {wireless device 100x and BS200} and / or {wireless device 100x and wireless device 100x} in.

[1315] The first wireless device 100 may include one or more processors 102 and one or more memories 104, and further include one or more transceivers 106 and / or one or more antennas (antenna units) 108. The processor 102 may control the memory 104 and / or the transceiver 106, and may be configured to implement the descriptions, functions, processes, proposals, methods and / or operational flow charts disclosed herein. For example, the processor 102 may process the information in the memory 104 to generate first information / signals, and then transmit a radio signal including the first information / signals through the transceiver 106. The processor 102 may receive a radio signal including second information / signals through the transceiver 106, and then store information obtained by processing the second information / signals in the memory 104. 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 store software codes including commands for executing part or all of the processing controlled by the processor 102 or for executing the descriptions, functions, processes, proposals, methods, and / or operational flowcharts disclosed herein. Herein, the processor 102 and the memory 104 may be part of a communication modem / circuit / chip designed to implement a RAT (e.g., LTE or NR). The transceiver 106 may be connected to the processor 102 and transmit and / or receive radio signals through one or more antennas 108. Each of the transceivers 106 may include a transmitter and / or a receiver. The transceiver 106 may be used interchangeably with (one or more) radio frequency (RF) units. In the present disclosure, a wireless device may represent a communication modem / circuit / chip.

[1316] Specifically, the UE may include a processor 102 connected to an RF transceiver and a memory 104. The memory 104 may include a processor for executing the above-referenced Figures 11 to 27 At least one procedure of operations related to the described embodiments.

[1317] Alternatively, a chipset including the processor 102 and the memory 104 may be configured. The chipset may include: at least one processor; and at least one memory operatively connected to the at least one processor and configured to cause the at least one processor to perform operations when executed.

[1318] The second wireless device 200 may include one or more processors 202 and one or more memories 204, and further include one or more transceivers 206 and / or one or more antennas 208. The processor 202 may control the memory 204 and / or the transceiver 206, and may be configured to implement the description, functions, processes, proposals, methods, and / or operation flowcharts disclosed herein. For example, the processor 202 may process the information in the memory 204 to generate third information / signals, and then transmit a radio signal including the third information / signals through the transceiver 206. The processor 202 may receive a radio signal including fourth information / signals through the transceiver 106, and then store information obtained by processing 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 store software codes including commands for executing part or all of the processing controlled by the processor 202 or for executing the description, functions, processes, proposals, methods, and / or operation flowcharts disclosed herein. Herein, the processor 202 and the memory 204 may be part of a communication modem / circuit / chip designed to implement a RAT (e.g., LTE or NR). The transceiver 206 may be connected to the processor 202 and transmit and / or receive radio signals through one or more antennas 208. Each of the transceivers 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 wireless device may represent a communication modem / circuit / chip.

[1319] Hereinafter, the hardware elements of the wireless devices 100 and 200 will be described in more detail. One or more protocol layers may be implemented by one or more processors 102 and 202 without limitation. For example, one or more processors 102 and 202 may implement one or more layers (e.g., functional layers such as PHY, MAC, RLC, PDCP, RRC, and SDAP). One or more processors 102 and 202 may generate one or more protocol data units (PDUs) and / or one or more service data units (SDUs) according to the descriptions, functions, processes, proposals, methods, and / or operational flow diagrams disclosed herein. One or more processors 102 and 202 may generate messages, control information, data, or information according to the descriptions, functions, processes, proposals, methods, and / or operational flows disclosed herein. One or more processors 102 and 202 may generate a signal (e.g., a baseband signal) including a PDU, SDU, message, control information, data, or information according to the description, functions, procedures, proposals, methods, and / or operational flow diagrams disclosed herein, and provide the generated signal to one or more transceivers 106 and 206. One or more processors 102 and 202 may receive a signal (e.g., a baseband signal) from one or more transceivers 106 and 206 and obtain the PDU, SDU, message, control information, data, or information according to the description, functions, procedures, proposals, methods, and / or operational flow diagrams disclosed herein.

[1320] One or more processors 102 and 202 may be referred to as controllers, microcontrollers, microprocessors, or microcomputers. One or more processors 102 and 202 may be implemented by hardware, firmware, software, or a combination thereof. As an 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 and 202. Firmware or software may be used to implement the description, function, process, proposal, method, and / or operational flow chart disclosed herein, and the firmware or software may be configured to include modules, processes, or functions. Firmware or software configured to perform the description, function, process, proposal, method, and / or operational flow chart disclosed herein may be included in one or more processors 102 and 202 or stored in one or more memories 104 and 204 so as to be driven by one or more processors 102 and 202. The descriptions, functions, processes, proposals, methods and / or operational flows disclosed herein may be implemented using firmware or software in the form of codes, commands and / or command sets.

[1321] One or more memories 104 and 204 may be connected to one or more processors 102 and 202 and store various types of data, signals, messages, information, programs, codes, instructions and / or commands. One or more memories 104 and 204 may be composed of read-only memory (ROM), random access memory (RAM), electrically erasable programmable read-only memory (EPROM), flash memory, hard drive, register, cache memory, computer-readable storage medium and / or a combination thereof. One or more memories 104 and 204 may be located inside and / or outside of one or more processors 102 and 202. One or more memories 104 and 204 may be connected to one or more processors 102 and 202 by respective technologies such as wired or wireless connections.

[1322] One or more transceivers 106 and 206 can send the user data, control information and / or radio signal / channel mentioned in the method and / or operation flow chart of this article to one or more other devices. One or more transceivers 106 and 206 can receive the user data, control information and / or radio signal / channel mentioned in the description, function, process, proposal, method and / or operation flow chart disclosed in this article from one or more other devices. For example, one or more transceivers 106 and 206 can be connected to one or more processors 102 and 202, and send and receive radio signals. For example, one or more processors 102 and 202 can perform control so that one or more transceivers 106 and 206 can send user data, control information or radio signal to one or more other devices. One or more processors 102 and 202 can perform control so that one or more transceivers 106 and 206 can receive user data, control information or radio signal from one or more other devices. One or more transceivers 106 and 206 may be connected to one or more antennas 108 and 208, and one or more transceivers 106 and 206 may be configured to send and receive user data, control information, and / or radio signals / channels mentioned in the description, functions, processes, proposals, methods, and / or operation flow charts disclosed herein through one or more antennas 108 and 208. In this document, one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers 106 and 206 may convert received radio signals / channels, etc. from RF band signals into baseband signals so as to process received user data, control information, radio signals / channels, etc. using one or more processors 102 and 202. One or more transceivers 106 and 206 may convert user data, control information, radio signals / channels, etc. processed using one or more processors 102 and 202 from baseband signals into RF band signals. To this end, one or more of the transceivers 106 and 206 may include (analog) oscillators and / or filters.

[1323] Fig.31 Another example of a wireless device applied to the present disclosure is illustrated. The wireless device can be implemented in various forms according to use cases / services (refer to Fig.29 ).

[1324] Reference Fig.31 , the wireless devices 100 and 200 may correspond to Fig.30The wireless devices 100 and 200 of the present invention may be composed of various elements, components, units / portions and / or modules. For example, each of the wireless devices 100 and 200 may include a communication unit 110, a control unit 120, a storage unit 130 and an additional component 140. The communication unit may include a communication circuit 112 and (one or more) transceivers 114. For example, the communication circuit 112 may include Fig.30 The one or more processors 102 and 202 and / or the one or more memories 104 and 204 of the present invention. For example, the transceiver 114 may include Fig.30 The control unit 120 is electrically connected to the communication unit 110, the storage unit 130, and the additional components 140, and controls the overall operation of the wireless device. For example, the control unit 120 can control the electrical / mechanical operation of the wireless device based on the program / code / command / information stored in the storage unit 130. The control unit 120 can send the information stored in the storage unit 130 to the outside (e.g., other communication devices) via the communication unit 110 through a wireless / wired interface, or store the information received from the outside (e.g., other communication devices) via the communication unit 110 through a wireless / wired interface in the storage unit 130.

[1325] The additional component 140 may be configured in various ways depending on the type of the wireless device. For example, the additional component 140 may include at least one of a power unit / battery, an input / output (I / O) unit, a drive unit, and a computing unit. The wireless device may be implemented in the following forms without limitation: a robot ( Fig.29 100a), vehicles ( Fig.29 100b-1 and 100b-2), XR devices ( Fig.29 100c), handheld device ( Fig.29 100d), household appliances ( Fig.29 100e), IoT devices ( Fig.29 100f), digital broadcast terminal, hologram device, public safety device, MTC device, medical device, FinTech device (or financial device), security device, climate / environmental device, AI server / device ( Fig.29 400), BS( Fig.29 200), network nodes, etc. Depending on the use case / service, the wireless device can be used in a mobile or fixed place.

[1326] exist Fig.31In the wireless devices 100 and 200, various elements, components, units / parts and / or modules in the wireless devices 100 and 200 may all be connected to each other through a wired interface, or at least a part thereof may be wirelessly connected through the communication unit 110. For example, in each of the wireless devices 100 and 200, the control unit 120 and the communication unit 110 may be connected by wire, and the control unit 120 and the first unit (e.g., 130 and 140) may be wirelessly connected through the communication unit 110. Each element, component, unit / part and / or module in the wireless devices 100 and 200 may also include one or more elements. For example, the control unit 120 may be composed of a set of one or more processors. As an example, the control unit 120 may be composed of a set of a communication control processor, an application processor, an electronic control unit (ECU), a graphics processing unit and a memory control processor. As another example, the storage unit 130 may be composed of a RAM, a DRAM, a ROM, a flash memory, a volatile memory, a non-volatile memory and / or a combination thereof.

[1327] Fig.32 The vehicle or autonomous driving vehicle applied to the present disclosure is illustrated. The vehicle or autonomous driving vehicle can be realized by a mobile robot, a car, a train, a manned / unmanned aerial vehicle (AV), a ship, etc.

[1328] Reference Fig.32 , the vehicle or autonomous driving vehicle 100 may include an antenna unit 108, a communication unit 110, a control unit 120, a drive unit 140a, a power supply unit 140b, a sensor unit 140c, and an autonomous driving unit 140d. The antenna unit 108 may be configured as a part of the communication unit 110. Blocks 110 / 130 / 140a to 140d correspond to Fig.31 Block 110 / 130 / 140.

[1329] The communication unit 110 may send signals (e.g., data and control signals) to and receive signals from external devices such as other vehicles, BSs (e.g., gNBs and roadside units), and servers. The control unit 120 may perform various operations by controlling elements of the vehicle or autonomous driving vehicle 100. The control unit 120 may include an ECU. The drive unit 140a may enable the vehicle or autonomous driving vehicle 100 to travel on a road. The drive unit 140a may include an engine, a motor, a powertrain, wheels, brakes, a steering device, and the like. The power supply unit 140b may supply power to the vehicle or autonomous driving vehicle 100 and include a wired / wireless charging circuit, a battery, and the like. The sensor unit 140c may acquire vehicle status, surrounding environment information, user information, and the like. The sensor unit 140c may include an inertial measurement unit (IMU) sensor, a collision sensor, a wheel sensor, a speed sensor, a slope sensor, a weight sensor, a heading sensor, a position module, a vehicle forward / reverse sensor, a battery sensor, a fuel sensor, a tire sensor, a steering sensor, a temperature sensor, a humidity sensor, an ultrasonic sensor, an illumination sensor, a pedal position sensor, etc. The autonomous driving unit 140d may implement a technology for maintaining a lane on which the vehicle is driving, a technology for automatically adjusting a speed such as an adaptive cruise control, a technology for autonomous driving along a determined path, a technology for driving by automatically setting a path when a destination is set, and the like.

[1330] For example, the communication unit 110 may receive map data, traffic information data, etc. from an external server. The autonomous driving unit 140d may generate an autonomous driving path and a driving plan from the obtained data. The control unit 120 may control the drive unit 140a so that the vehicle or the autonomous driving vehicle 100 may move along the autonomous driving path according to the driving plan (e.g., speed / direction control). In autonomous driving, the communication unit 110 may obtain the latest traffic information data from the external server irregularly / regularly, and may obtain surrounding traffic information data from neighboring vehicles. In autonomous driving, the sensor unit 140c may obtain vehicle status and / or surrounding environment information. The autonomous driving unit 140d may update the autonomous driving path and driving plan based on the newly obtained data / information. The communication unit 110 may transmit information about the vehicle position, autonomous driving path, and / or driving plan to an external server. The external server may predict traffic information data based on information collected from the vehicle or autonomous driving vehicle, using AI technology, etc., and provide the predicted traffic information data to the vehicle or autonomous driving vehicle.

[1331] Here, the wireless communication technology implemented in the wireless device (XXX, YYY) of this specification may include LTE, NR and 6G, as well as narrowband Internet of Things for low-power communication. At this time, for example, NB-IoT technology may be an example of low-power wide area network (LPWAN) technology, and may be implemented in standards such as LTE Cat NB1 and / or LTE Cat NB2, and is not limited to the above names. Additionally or alternatively, the wireless communication technology implemented in the wireless device (XXX, YYY) of this specification may perform communication based on LTE-M technology. In this case, as an example, LTE-M technology may be an example of LPWAN technology, and may be referred to by various names such as eMTC (enhanced machine type communication). For example, LTE-M technology may be implemented in 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 names. Additionally or alternatively, the wireless communication technology implemented in the wireless device (XXX, YYY) of the present specification is at least one of ZigBee, Bluetooth, and a low power wide area network (LPWAN) considering low power communication, and is not limited to the above names. As an example, ZigBee technology can generate a personal area network (PAN) related to small / low power digital communication based on various standards such as IEEE 802.15.4, and can be called various names.

[1332] The above-mentioned embodiments are embodiments in which the components and features of the present disclosure are combined in a predetermined form. Unless otherwise expressly stated, each component or feature should be considered optional. Each component or feature can be implemented in a form not combined with other components or features. In addition, the embodiments of the present disclosure can also be constituted by combining some parts and / or features. The order of operations described in the embodiments of the present disclosure can be changed. Some configurations or features of an embodiment can be included in other embodiments, or can be replaced by corresponding configurations or features of other embodiments. It is obvious that the embodiment can be configured by combining claims that do not have a clear reference relationship in the claims, or can be included as a new claim by modification after submission.

[1333] In this document, the embodiments of the present disclosure are described mainly based on the signal transmission / reception relationship between the terminal and the base station. This transmission / reception relationship is extended to the signal transmission / reception between the terminal and the repeater or the base station and the repeater in the same / similar manner. In some cases, the specific operations described in this document as being performed by the base station can be performed by its superior node. That is, it is obvious that various operations for communicating with a terminal in a network of multiple network nodes including a base station can be performed by a base station or a network node other than the base station. The base station can be replaced by terms such as a fixed station, a node B, an eNode B (eNB), an access point, etc. In addition, the terminal can be replaced by terms such as a user equipment (UE), a mobile station (MS), a mobile user station (MSS), etc.

[1334] In hardware configuration, the embodiments of the present disclosure may be implemented by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, etc.

[1335] In firmware or software configuration, the method according to the embodiment of the present disclosure can be implemented in the form of modules, processes, functions, etc. The software code can be stored in a memory unit and executed by a processor. The memory unit is located inside or outside the processor and can send data to and receive data from the processor via various known means.

[1336] As mentioned above, a detailed description of the preferred embodiments of the present disclosure has been given so that those skilled in the art can implement and perform the present disclosure. Although the above has been referred to the preferred embodiments of the present disclosure, it will be understood by those skilled in the art that various modifications and changes can be made to the present disclosure within the scope of the present disclosure. For example, those skilled in the art can use the components described in the aforementioned embodiments in combination. Therefore, the above embodiments are interpreted as illustrative and not restrictive in all aspects. The scope of the present disclosure should be determined by the attached claims and their legal equivalents, rather than by the above description, and all changes falling within the meaning and equivalent scope of the attached claims are intended to be included therein.

[1337] Industrial Applicability

[1338] The present disclosure is applicable to UE, BS or other devices in a wireless mobile communication system.

Claims

1. A method for sending a signal by a user equipment UE in a wireless communication system, the method comprising the following steps: receiving a first message including configuration information about a multipath MP bearer configured with a plurality of radio link control RLC entities, the plurality of RLC entities including at least one first RLC entity associated with a direct path to a network and at least one second RLC entity associated with an indirect path to the network; receiving a second message including information about activation / deactivation of each RLC entity; as well as Sending a data unit based on the MP bearer configured by the configuration information, wherein the configuration information includes information on data replication for data unit transmission, wherein the information about activation / deactivation of each RLC entity is based on an RLC entity index configuration for the plurality of RLC entities, wherein the RLC entity index is determined based on the following index order: at least one first RLC entity index of the at least one first RLC entity associated with the direct path is followed by at least one second RLC entity index of the at least one second RLC entity associated with the indirect path, and The data unit transmission is based on the data replication on an activated RLC entity among the multiple RLC entities.

2. The method according to claim 1, wherein: The information on activation / deactivation of each RLC entity is configured as a Medium Access Control MAC Control Element CE.

3. The method according to claim 2, wherein: The MAC CE includes an activation / deactivation indication for each RLC entity index.

4. The method according to claim 1, wherein: The second message including the information on activation / deactivation of each RLC entity is received through the direct path.

5. The method according to claim 1, wherein: The second message including the information on activation / deactivation of each RLC entity is received by a remote UE in the indirect path.

6. The method according to claim 1, wherein: The at least one first RLC entity index is lower than the at least one second RLC entity index.

7. The method according to claim 1, wherein: The data unit is a Packet Data Convergence Protocol (PDCP) data unit, and the data copy is a PDCP data unit copy.

8. The method according to claim 1, wherein: The at least one second RLC entity is at least one sidelink SL RLC entity associated with a relay UE in the indirect path to the network.

9. The method according to claim 1, wherein: The first message is received through radio resource control RRC signaling.

10. The method according to claim 1, wherein: The plurality of RLC entity indexes are logical channel identifiers of the plurality of RLC entities.

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

12. An apparatus for wireless communication, the apparatus comprising: a memory configured to store instructions; as well as a processor configured to perform operations by executing the instructions, The operations performed by the processor include: receiving a first message including configuration information about a multipath MP bearer configured with a plurality of radio link control RLC entities, the plurality of RLC entities including at least one first RLC entity associated with a direct path to a network and at least one second RLC entity associated with an indirect path to the network; receiving a second message including information on activation / deactivation of each RLC entity; and Sending a data unit based on the MP bearer configured by the configuration information, wherein the configuration information includes information on data replication for data unit transmission, wherein the information about activation / deactivation of each RLC entity is based on an RLC entity index configuration for the plurality of RLC entities, wherein the RLC entity index is determined based on the following index order: at least one first RLC entity index of the at least one first RLC entity associated with the direct path is followed by at least one second RLC entity index of the at least one second RLC entity associated with the indirect path, and The data unit transmission is based on the data replication on an activated RLC entity among the multiple RLC entities.

13. The device according to claim 12, wherein: The apparatus is a user equipment UE operating in a wireless communication system based on the 3rd Generation Partnership Project 3GPP.

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